Microplasma chamber

Abstract

A device may include a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air. A device may include a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes comprise a conductive beam structure extending lengthwise in a lateral direction over the substrate.

Description

MICROPLASMA CHAMBERINCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Application No. US 63 / 653940, titled “MICROPLASMA CHAMBER,” filed May 30, 2024, the entire disclosure of which is incorporated herein by reference for all purposes.BACKGROUNDField

[0002] The disclosed technology generally relates to microplasma devices and more particularly to integrated microplasma devices that sustain a microplasma on a substrate.Description of Related Art

[0003] Plasma is a state of matter comprising a highly ionized gas generated by ionizing molecules, e.g., using a constant electric field, an alternating electric field, or a combination thereof. Electronic characteristics of plasma and optical emissions by plasma can be used in a variety of applications. Plasma-based devices that are miniaturized can advantageously be integrated as part of a system-on-chip or system-on-package. Thus, there is a need to develop devices that can generate and sustain plasma reliability and repeatability, while also being capable of being fabricated or co-fabricated using existing fabrication technologies, such as semiconductor fabrication and / or packaging technologies. As an example, such devices can be used to protect certain electronic systems exposed to electrical overstress (EOS) events from being damaged by a current and / or a voltage that is beyond specified limits of the electronic device.SUMMARY

[0004] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrodeand the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes include a conductive beam structure extending lengthwise in a lateral direction over the substrate.

[0005] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes include a conductive pad structure extending lengthwise in a lateral direction over the substrate.

[0006] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein the first electrode is formed as part of the capping structure.

[0007] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon a metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode includes a metallization structure of the metallization layer, and wherein the second electrode is formed in the substrate.

[0008] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode includesa first metallization structure of the metallization layer and the second electrode includes a second metallization structure metallization layer.

[0009] In some aspects, the techniques described herein relate to a micro-plasma device including: a substrate having formed thereon an interconnect layer; a recessed volume formed under the interconnect layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, a plasma control electrode disposed over a central region of the recessed volume and configured to be independently biased for electrostatically affecting the plasma.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments of this disclosure will now be described, by way of non-limiting example, with reference to the accompanying drawings.

[0011] FIG. 1 illustrates the relationship between inter-electrode voltage and electric current passing through a vacuum tube, illustrating distinct voltage-current behavior regimes for various types of cathodes.

[0012] FIGS. 2A-2B schematically illustrate side (vertical) cross-sectional views (top panels) and top cross-sectional views (bottom panels) of two microplasma devices (MPDs) comprising a microplasma chamber (MPC) formed by a capping structure over a substrate.

[0013] FIG. 3 schematically illustrates a top-down view of two electrodes of a MPD each comprising a common section and a plurality of electrode fingers configured to form interelectrode and triggering gaps.

[0014] FIG. 4A schematically illustrates an example MPD having electrode fingers formed on a top surface of a substrate on which the capping structure is disposed.

[0015] FIG. 4B schematically illustrates an example MPD similar to the MPD shown in FIG. 4 A having a middle electrode formed between electrode fingers.

[0016] FIGS 5A-5C schematically illustrates example electrode pair configurations that may serve as the electrodes of a MPD.

[0017] FIG. 6A schematically an example MPD comprising a MPC formed by a capping structure over a substrate and a vertical inter-electrode gap formed by a conductive layer and a conductive bridge formed above the conductive layer.

[0018] FIG. 6B schematically an example MPD comprising a MPC formed by a capping structure over a substrate and a vertical inter-electrode gap formed between a conductive region of the capping structure and a conductive layer.

[0019] FIGS. 7A-7B schematically illustrate vertical and top cross-sectional views of an example MPD with a MPC comprising a capping structure formed on an etched substrate.

[0020] FIGS. 8A-8C schematically illustrate example MPDs comprising a MPC formed below an etched or patterned top layer and in an etched bottom layer of an etched substrate.

[0021] FIGS. 9A-9C schematically illustrate example patterned structures (e.g., patterned wafers), comprising a plurality of homogeneous capping structures (FIG. 9A), heterogenous capping structures (FIG. 9B), and capping structures comprising conductive vias (FIG. 9C), before singulation.

[0022] FIG. 10 schematically illustrates example conductive regions that may be formed in a capping structure or on a surface of a capping structure.

[0023] FIGS. 11A-11B schematically illustrate example MPDs comprising capping structures configured to provide electric connection between a layer or structure formed on a major top external surface of the capping structures and corresponding substrate on which the capping structures are formed.

[0024] FIG. 12 schematically illustrates an example process for fabricating the capping structure shown in FIG. 11 A.

[0025] FIG. 13 schematically illustrates an example process for fabricating an MPD comprising the capping structure shown in FIG. 1 IB.

[0026] FIG 14A schematically illustrates an example MPD having a capping structure comprising electric contacts configured for high current transmission to vertical conductive vias formed in the capping structure.

[0027] FIGS 14B-14C schematically illustrates example MPDs comprising electrically conductive clips configured for high current transmission from vertical conductive vias formed in the capping structure and conductive connector pads formed on a substrate of the MPD.

[0028] FIG. 15 schematically illustrates an example MPC formed by a capping structure comprising a secondary reservoir configured to trap certain gas molecules.

[0029] FIGS. 16A-16E schematically illustrate engineered capping structures having tailored geometrical and structural features.

[0030] FIGS. 16F-16J schematically illustrate example capping structures each comprising a piezoelectric layer.

[0031] FIG. 17A illustrates a top view (top panel) and a cross-sectional view (bottom panel) of an example integrated MPD comprising an etched sealed gas-filled chamber configured to sustain plasma formation, according to some embodiments.

[0032] FIG. 17B illustrates a top view (top panel) and a cross-sectional view (bottom panel) of another example integrated MPD comprising and etched sealed gas-filled chamber having current control barriers configured to sustain plasma formation, according to some embodiments.

[0033] FIG. 18 schematically illustrates two cross-sectional views in two planes perpendicular to each other and to a horizontal major surface of a substrate (top panels), and a top view (bottom panel) of another example of MPD comprising vertically separated electrodes and a recessed MPC formed in the substrate.

[0034] FIGS. 19A-19C schematically illustrate cross-sectional views of intermediate structures that may be formed during fabrication of the MPD shown in FIG. 18, in a plane perpendicular to a horizontal major surface of the substrate.

[0035] FIG. 20 schematically illustrates two cross-sectional views in two planes perpendicular to each other and to a horizontal major surface of a substrate (top panels), and a top view (bottom panel), of another example of MPD comprising vertically separated electrodes, a recessed MPC and current control barriers formed in the substrate.

[0036] FIG. 21 schematically illustrates a cross-sectional view (top panel), in a plane perpendicular to a horizontal major surface of a substrate, and a top view (bottom panel), of another example of MPD comprising laterally separated electrodes and a recessed MPC that is formed in the substrate and comprises vertically and horizontally extended dielectric regions formed in the substrate.

[0037] FIG. 22A schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate (top panel), and a top view (bottompanel), of another example MPD comprising laterally separated main electrodes, an auxiliary electrode, and a recessed MPC formed in the substrate, where the recessed MPC comprises vertically and horizontally extended dielectric regions.

[0038] FIG. 22B schematically illustrates electric connection between electrodes of MPD shown in FIG. 22A and a voltage source. The inset depicts variation of the breakdown voltage (BV) of the MPD as a function of lateral separations between the auxiliary electrode and the main electrodes of the MPD.

[0039] FIG. 22C schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate (top panel), and a top view (bottom panel), of another example MPD comprising laterally separated main electrodes, a gate electrode embedded in the capping layer, and a recessed MPC formed in the substrate, where the recessed MPC comprises vertically and horizontally extended dielectric regions.

[0040] FIG. 23 A schematically illustrates a cross-sectional view (top panel), in a plane perpendicular to a horizontal major surface of a substrate (top panel), and a top view (bottom panel), of another example of MPD comprising two laterally separated electrodes, a recessed MPC formed in the substrate that comprises vertical current barriers and a laterally extended conductive region.

[0041] FIG. 23B schematically illustrates a cross-sectional view (top panel), in a plane perpendicular to a horizontal major surface of a substrate, and a top view (bottom panel), of another example of MPD comprising two laterally separated electrodes, an isolated gate electrode, and a recessed MPC formed in the substrate, where the MPC comprises vertical current barriers and a laterally extended conductive region.

[0042] FIG. 24A schematically illustrates a configuration for generating and sustaining a plasma in an MPD and electrically connecting the plasma to an electronic circuit.

[0043] FIG. 24B schematically illustrates discharge current plotted against voltage applied between two electrodes for the integrated microplasma device shown in FIG. 24A.

[0044] FIG. 25 schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD configured to support formation of plasma and controlling the plasma using radio frequency (RF) waves received from an external RF source.

[0045] FIG. 26 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of three MPDs configured to support formation of plasma and allow control and manipulation of the plasma using light waves.

[0046] FIG. 27 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of three MPDs configured to support formation of plasma in a recessed MPC and comprising a flexible layer configured to control gas pressure in the MPC.

[0047] FIG. 28 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of two MPDs configured to support formation of plasma and comprising a radio frequency antenna configured to monitor RF radiation emitted by the plasma.

[0048] FIG. 29 schematically illustrates cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD configured to support formation of plasma and comprising a magnetic shield configured to block magnetic field generate by the plasma.

[0049] FIG. 30 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of four MPDs configured to support formation of plasma and comprising a photodetector configured to monitor light generated by the plasma.

[0050] FIG. 31A schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD configured to support formation of plasma and comprising an antenna and a photodetector configured to detect light and RF waves generated by the plasma and radiate an RF signal indictive of the detected light and RF waves.

[0051] FIG. 3 IB schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD configured to support formation of plasma and comprising a photodetector and an RF antenna configured to detect light and RF waves generated by the plasma, respectively, where the RF antenna re-radiates the detected RF based on the detected light.

[0052] FIG. 32 schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of two MPDs configured to support formation of plasma and comprising a shielding layer configured to electrically, electromagnetically, thermally, and / or optically isolate the plasma from a region above the MPD.

[0053] FIG. 33 schematically illustrates a block diagram of an electric protection and monitoring system configured to monitor and protect an electronic circuit and generate and transmit data indicative of signals generated by one or more circuit breaker devices.

[0054] FIG. 34 schematically illustrates a block diagram of a computing system configured to receive and analyze data received from the electric protection and monitoring system shown in FIG. 33.

[0055] FIGS. 35-37 schematically illustrates block diagrams of three different electric protection and monitoring systems having different interconnection architectures.

[0056] FIG. 38 schematically illustrates block diagram of an example implementation of the electric protection and monitoring system shown in FIG. 33.

[0057] FIG. 39 illustrates a side cross-sectional view of the integrated microplasma device shown in FIG. 17B, configured as an electro-optical modulator.

[0058] FIG. 40 illustrates a side cross-sectional view of an example integrated microplasma device configured to function as an electronically controlled resistor.

[0059] FIG. 41 illustrates a side cross-sectional view of an optoelectronic gas detector comprising an integrated microplasma device.DETAILED DESCRIPTION

[0060] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings where like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and / or a subset of the illustrated elements. Further, some embodiments can incorporate any suitable combination of features from two or more drawings. The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of the claims.Integrated Microplasma Devices and Applications

[0061] Plasma is a state of matter comprising a highly ionized gas generated by ionizing molecules, e.g., using a constant electric field, an alternating electric field, or a combination thereof. Plasma can have electronic and / or optical properties that may be used to provide certain functionalities that may not be supported or easily implemented based on movement of charge carriers in a conductor or a semiconductor material. In order to exploit these properties in a device, the plasma should be generated, sustained, and controlled during an operational period of the device. In various applications, it can be desirable to exploit the properties of plasma in a compact device (e.g., an on-chip device) configured to be integrated with other devices and components of a system (e.g., a system comprising an integrated circuit). However, generating, sustaining, and controlling plasma on a chip can be a challenging task. Thus, there is a need to develop on-chip devices that can generate and sustain plasma reliability and repeatability, while also capable of being fabricated or co-fabricated with integrated electronic, electromechanical, optical, and / or optoelectronic devices using existing fabrication technologies (e.g., microfabrication technologies).

[0062] In some embodiments, a microfabricated device (e.g., a device fabricated using IC fabrication process) may comprise a micro-plasma device. The micro-plasma device comprises a sealed gas-filled chamber configured to allow generation of plasma within the chamber and, in some cases, sustain the plasma during an operational period. In cases, when the microfabricated gas filled chamber comprises an integrated microdevice formed on a substrate the, the plasma formed in the gas-filled chamber may be referred to as microplasma, the gas-filled chamber may be referred to as microplasma chamber (MPC), and a microdevice that is configured to operate based on the microplasma may be referred to as a microplasma device. Advantageously, electrical and electro-optical characteristics of the microplasma may be exploited to provide functionalities that may not be easily accessible by commonly used integrated electronic and optoelectronic devices and components. These functionalities may be used to design electronic and optoelectronic circuits and systems for a variety of applications including but not limited to EOS protection, electronic switching, sensing (e.g., gas sensing), RF signal generation, electronic amplification, and other applications. To provide these and other advantages, microplasma devices are disclosed according to various embodiments. The inventors have discovered that, by utilizing existing fabrication methods and technologies (e.g., methods used for fabricating integrated circuits andmicroelectromechanical systems), a microplasma device can be fabricated on chip to generate, sustain, and control a microplasma within an on-chip cavity and provide electrical and optical access to the microplasma to exploit its electronic and optical characteristics in different applications. In some embodiments, the microplasma devices described below may be cofabricated with one or more electronic and / or optical devices on a common chip and can electronically and / or optically communicate with these electronic and / or optical devices via on- chip or off-chip connections.

[0063] The disclosed microplasma devices may allow using electronic and optical properties an on-chip microplasma for providing, e.g., electronic oscillation, non-linear currentvoltage relation, high current connections, electronic switching, electronic amplification, optical modulation, electrical overstress protection and monitoring, optical molecule detection, light generation and the like.

[0064] Various electronic devices for various applications including automotive and consumer electronics that are fabricated using low voltage CMOS processes are increasingly using input / output (I / O) interface pins that operate at relatively high bidirectional voltages. These devices often operate in relatively harsh environments and should comply with applicable electrostatic discharge (ESD) and electromagnetic interference (EMI) immunity specifications. Integrated circuits (ICs) can be particularly susceptible to damage from electrical overstress (EOS) events, such as ESD events. Robust ESD and EMI immunity is desirable because the electronic devices can be subject to a wide range of high voltage transient electrical events that exceed ordinary operating conditions. High voltage events are particularly common in the automotive electronics field. The transient electrical events can be, e.g., a rapidly changing high energy signal such as an electrostatic discharge (ESD) event. The transient electrical event can be associated with an overvoltage event caused by a user contact or contact with other objects, or simply from malfunctions in electrical systems. In other circumstances, the transient electrical event can be generated by a manufacturer to test the robustness of the transceiver integrated circuit under a defined stress condition, which can be described by standards set by various organizations, such as the Joint Electronic Device Engineering Council (JEDEC), the International Electrotechnical Commission (IEC), and the Automotive Engineering Council (AEC). Electronic circuit reliability can be enhanced by providing protection devices, e.g., ESD protection devices. Such protection devices can maintain relatively high voltage levels at certain locations, e.g., IC power high supplyvoltage, within a predefined safe range by transitioning from a high-impedance state to a low-impedance state when the voltage of the transient electrical event reaches a trigger voltage. Thereafter, the protection device can shunt at least a portion of the current associated with the transient electrical event to, e.g., ground, before the voltage of a transient electrical event reaches a positive or negative failure voltage that can lead to one of the most common causes of IC damage. The EDS protection devices can be configured, for example, to protect an internal circuit against transient signals that exceed the IC power high and power low (for instance, ground) voltage supply levels.

[0065] Various techniques can be employed to protect a core or a main circuitry of the electronic devices, such as ICs against these damaging transient electrical events. Some systems employ external off-chip protection devices to ensure that core electronic systems are not damaged in response to a transient electrostatic and electromagnetic events. However, due to performance, cost, and spatial considerations, there is an increasing need for protection devices that are monolithically integrated with the main circuitry, that is, the circuitry to be protected. It can be desirable for an ESD protection device to be fabricated on a chip and to be configurable for high current and voltage (I-V) blocking characteristics. To provide these and other advantages, microplasma EOS monitoring and protection devices are disclosed according to various embodiments.

[0066] In some cases, any or the microplasma devices described below may serve as an integrated surge protection device configured to provide a low resistance electric path between two terminals by forming a plasma in response to an EOS event (e.g., the electric potential difference between the two terminals exceeding a threshold value). In some embodiments, pressure inside the MPC and the electrode spacing of an on-chip MPD may be configured to allow ignition of plasma inside the MPC and thereby establishing a low resistance electric path between the electrodes, in response to an EOS event. In various implementations, the electric current transmitted via the electric path formed by plasma in the MPC can be from 2 to 10 Amps, 10 to 20 Amps, 20 to 40 Amps, 40 to 60 Amps, 60 to 80 Amps, 80 to 100 Amps, or any ranges formed by these values or larger values.

[0067] In some embodiments, a microplasma device (MPD) may comprise a pair of spaced conductive structures separated by an inter-electrode gap enclosed in a gas-filled chamber herein referred to microplasma chamber (MPC). In some such embodiments, inter-electrode gapand the pressure of the MPC may be configured to allow formation of a plasma and thereby electric current flow between the pair of conductive structures via the plasma, in response to a voltage difference between the pair of conductive structures. In some cases, the pair of conductive structures may comprise a first electrode electrically connected to a first electric terminal (e.g., a first voltage node) by a first electrode line and a second electrode electrically connected to a second electric terminal by a second electrode line. In some cases, the first electrode may comprise a cathode and the second electrode may comprise an anode. In some cases, the MPD may be configured to provide an electric path between the first and second electrodes via a plasma formed in the MPC. In some cases, resistance of the electric path may depend on a voltage applied between the first and second electrodes, the pressure of a gas inside the MPC, and geometrical characteristics of the chamber, among other parameters.

[0068] FIG. 1 illustrates the relationship between inter-electrode voltage (V) and electric current (I) passing through a vacuum tube, highlighting distinct voltage-current behavior regimes for various types of cathodes. In some cases, the relationship between inter-electrode voltage and electric current passing through a MPD may comprise one or more features of voltagecurrent behavior in FIG. 1. For example, MPD may provide a substantially constant positive V-I slope for a first characteristic voltage range, a near zero V-I slope for a second characteristic voltage range, a very large negative V-I slope at or near a breakdown voltage, and substantially constant positive V-I slope for a third characteristic voltage range greater than the break down voltage. In various implementations, the characteristic voltage ranges associated with different electrical behavior of the MPD may be designed and / or controlled by tailoring inter-electrode distance, electrode properties, geometrical characteristics of the MPC, and other parameters. In some cases, for different applications, the operational voltage range of the MPD may overlap with one or more characteristic voltage ranges of the MPD.

[0069] In various implementations, the MPD may be fabricated on and / or within a substrate comprising a bottom layer and top layer. In some cases, the bottom layer may comprise a semiconductor substrate (e.g., silicon) and the top layer may comprise a dielectric layer (e.g., silicon dioxide). In some cases, each electrode may comprise a single electrode finger and the inter-electrode gap may comprise a vertical or lateral distance between the electrode fingers. In some cases, one or both electrodes may comprise two or more electrode fingers. In some such cases, the inter-electrode gap may comprise a plurality of gaps formed between individualelectrode fingers of an electrode and one or more electrode fingers of the other electrode. In some embodiments, the MPC may be formed above the substrate (e.g., on a top major surface of the substrate) using a capping structure. In some embodiments, the MPC may be formed at last partially below a top major surface of the substrate (e.g., within the substrate). In various implementations, the electrodes may be formed over or withing the top layer of the substrate. In some embodiments, an electrode line may comprise a conductive line formed within the top layer of the substrate to provide electric connection between the electrode finger and a conductive contact pad or a electric terminal. In some examples, a first end of the electrode line can be electrically connected to the electrode finger (e.g., directly or by a conductive connector such as a vertical via) and a second end of the electrode line can be electrically connected to the conductive contact pad (e.g., directly or by a conductive connector such as a vertical via).

[0070] According to various embodiments disclosed herein, an MPD comprises a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air. The MPD additionally comprises a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased. In some embodiments, one or both of the first and second electrodes comprise a conductive beam structure extending lengthwise in a lateral direction over the substrate. In some other embodiments, one or both of the first and second electrodes comprise a conductive pad structure extending lengthwise in a lateral direction over the substrate. In yet some other embodiments, the first electrode is formed as part of the capping structure.

[0071] FIG. 2A schematically illustrates a side (vertical) cross-sectional view (top panel) and a top cross-sectional view (bottom panel) of a MPD 200 comprising a gas-filled chamber or MPC 205 formed by a capping structure 208 over a substrate 203 having a top layer 206 and a bottom layer 204. The capping structure 208 forms an enclosed volume filled with a gas other than ambient air. In the illustrated embodiment, one or both of the first and second electrodes for striking and sustaining a plasma comprise a conductive pad structure extending lengthwise in a lateral direction over the substrate. In some embodiments, a first electrode of MPD 200 may comprise a first conductive pad arranged as a first group of electrode fingers 212a- 1, 212a-2 electrically connected to a first electric terminal T1 (e.g., a first voltage node) by a first electrode pattern or electrode line 210a. A second electrode of MPD 200 may comprise a second conductivepad arranged as a second group of electrode fingers 212a-l, 212a-2 electrically connected to a second electric terminal T2 (e.g., a second voltage node) by a second electrode pattern or electrode line 210b. In some examples, the electrode fingers 212a-l, 212a-2, 212b-l, 212b-2 and electrode lines 210a, 210b, may be extended along a lateral direction parallel to a major surface of the substrate 203. In some cases, the electrode fingers 212a-l, 212a-2, 212b-l, 212b-2 may be formed such that that a top surface of the top layer 206 comprises the top surfaces of the electrode fingers 212a-l, 212a-2, 212b-l, 212b-2. In some cases, an electrode finger can have a length (L) along a first lateral direction, a width (W) along a second lateral direction perpendicular to the first lateral direction, and a thickness (t) along a vertical direction perpendicular to a major surface of the substrate 203. In some cases, L can be larger than W by a factor ranging from 1.5 to 2 microns, from 2 to 6 microns, from 6 to 10 microns, from 10 to 30 microns, from 30 to 50 microns, from 50 to 70 microns, from 70 to 100 microns, or any ranges formed by these values or larger values. In some cases, electrode fingers of the first and second groups of electrode fingers may have a common geometrical characteristic (e.g., same length, width, and or thickness).

[0072] In some embodiments, the first and second groups of the electrode fingers may be aligned to form a plurality of lateral inter- finger gaps where each finger-gap is formed between two nearest electrode fingers each associated with a different electrode. In some cases, an interfinger gap can be a shortest distance between the two nearest electrode fingers. For example, the first group of the electrode fingers 212a-l, 212a-2, may be interleaved with the second group of the electrode fingers 212b-l, 212b-2 to form a plurality of inter-finger gaps extending along the second lateral direction (e.g., along y-axis). For example, an inter-finger gap can be a separation between the electrode finger 212a-2 of the first electrode and the electrode finger 212b-2 of the second electrode, along the second lateral direction. In some examples, inter-finger gaps of the plurality of inter-finger gaps can be substantially equal. For example, the first and second groups of the electrode fingers 212a-l, 212a-2, 212b-l, 212b-2 form four inter-finger gaps having the same gap-size (g). In some examples, the gap-size can be from 0.5 to 1, from 1 to 2 microns, from 2 to 4 microns, from 4 to 6 microns, from 6 to 10 microns, from 10 to 30 microns, from 30 to 50 microns, from 50 to 70 microns, from 70 to 100 microns, or any ranges formed by these values or larger values.

[0073] In some cases, the first and second electrode lines 210a, 210b, may be formed within the top layer 206 (also referred to ass electrode layer) below the corresponding electrodefingers. In the example shown, each electrode line comprises a U-shape conductive structure having two prongs each connected to the bottom surface of a corresponding electrode finger and thereby electrically connecting the pair of electrode fingers to a common electric terminal.

[0074] In some embodiments, the capping structure 208 may be aligned with respect to the electrode fingers such that at least the plurality of inter-finger gaps are in contact with the gas inside the MPC 205 formed between the capping structure 208 and the substrate 203. In some embodiments, the capping structure 208 may enclose an area of the top layer 206 comprising top surfaces of the inter-finger gaps and the electrode fingers. In some cases, the capping structure 208 can be hermetically sealed to form the MPC 205 (gas-filled cavity) comprising a specified composition and pressure such that the plurality of inter-finger gaps can transform the gas into a plasma medium. In some implementations, the capping structure 208 can be hermetically sealed such that the gas or gas mixture inside its enclosed volume does not substantially mix with outside air. For example, the enclosure can be fabricated under an atmosphere other than air at a sufficient pressure such that the cavity inside the capping structure 208 remains isolated with an internal pressure that is about the same or slightly higher relative to the outside air. In various implementations, by selecting a suitable gas filling the sealed cavity inside the capping structure 208, the breakdown or trigger voltage of the MPC 205 can be tuned. Additionally, the trigger voltage of the MPC 205 may be tuned by selecting the material and composition of the electrode fingers.

[0075] In some embodiments, the capping structure 208 may be fabricated separate from the substrate 203 and then bonded or otherwise connected to the substrate 203. In some embodiments, one or more sealing connections 207 may be configured to from a hermetic seal between the capping structure 208 and the substrate 203 (e.g., the top surface of the top layer 206). In some embodiments, a sealing connection 207 may comprise a sealing pad or a bond frame formed on the substrate 203 and / or on the capping structure 208. For example, a sealing connection may comprise a first sealing pad disposed on the substrate 203 and a second sealing pad may be formed on the capping structure 208 (e.g., on a bottom surface of the capping structure 208) where the first and second sealing pads are bonded via thermal bonding, soldering, and the like. In some cases, the sealing pad may comprise glass (e.g., glass frit).

[0076] FIG. 2B schematically illustrates a side (vertical) cross-sectional view (top panel) and a top cross-sectional view (bottom panel) of another MPD 202 comprising a gas-filledchamber or MPC 205 formed by a capping structure 208 over the substrate 203. The MPD 202 may comprise one or more features similar to those described above with respect to MPD 200 (FIG. 2A). Features similar to those described above with respect to FIG. 2 A may not be described in detail herein for brevity. In the illustrated embodiment, one or both of the first and second electrodes for striking and sustaining a plasma comprise a conductive beam structure extending lengthwise in a lateral direction over the substrate 203. In some embodiments, MPD 202may comprise first and second groups of conductive beam structures 214a-l / 214a-2 and 214b-l / 214b- 2, respectively, formed above the top surface of the top layer 206. In some examples, the first and second groups of conductive beam structures 214a-l / 214a-2 and 214b-l / 214b-2 may be suspended above the top surface of the top layer 206 and electrically connected to first and second electrode patterns or lines 210a, 210b, respectively. In some examples, each electrode finger of the first and second groups of electrode fingers 214a-l / 214a-2 and 214b-l / 214b-2 may be electrically connected to a corresponding electrode line formed in the top layer 206 by at least one conductive via 215. In some examples, the conductive via may be formed in the top layer 206. In some cases, the conductive via 215 may comprise a conductive line vertically extended from the electrode finger (an end of the electrode finger) to a prong of an electrode line formed below the electrode finger. In the example shown, an electrode finger 214a-2 is electrically connected by two conductive vias 215 vertically extending from two opposite ends of the electrode finger 214a-2 to two opposite ends of a prong of the corresponding electrode line below the electrode finger 214a- 2.

[0077] In some embodiments, the capping structure 208 of any of the MPDs 200, 202, may comprise a getter layer 209 configured to control the pressure and / or composition of the gas mixture enclosed in the MPC 205. In some embodiments, the getter layer 209 may comprise a material configured to absorb certain gas molecules enclosed in the MPC 205.

[0078] In some embodiments, the capping structure 208 of any of the MPDs 200, 202, may comprise an ionization source configured to increase a number of ionized molecules in the MPC 205 and thereby facilitate and / or imitate plasma formation in MPC 205. In some cases, the ionization source may comprise a source of particles (e.g., alpha particles) or a source of radiation (e.g., gamma radiation), or other sources. In some cases, the ionization source may be disposed on an internal surface of the capping structure 208 or a region of the top surface of the top layer 206 enclosed in the capping structure 208.

[0079] In some embodiments, at least a portion of a MPD 200 and MPD 202 can be fabricated using a microelectromechanical systems (MEMS) fabrication technique. For example, the electrode fingers (conductive bridges) 214a-l, 21a-2, 214b-l, 214b-2, may be fabricated using methods used for fabricating bridges and capping structures for MEMS device (e.g., co-fabricated with a MEMS structure or device). In some examples, the conductive bridges may be fabricated using a plating process (e.g., a gold electroplating process). As another example, the capping structure 208 may be fabricated and bonded to the substrate 203 using common MEMS fabrication and bonding techniques. In some embodiments, other portions of a MPD may be co-fabricated with corresponding regions or regions of one more MEMS devices on a common substrate.

[0080] In some embodiments, individual electrodes of a MPD may comprise a plurality of electrode fingers connected to a common electrode section where the electrode fingers and at least a portion of the common electrode section are exposed to the gas inside MPC. For example, the electrode fingers and at least a portion of the common electrode section may be enclosed in the capping structure 208.

[0081] In some such embodiments, a triggering gap formed between an the first electrode and the second electrode can be configured to generate an ionizing radiation when the voltage is applied between the first and second electrodes. In some cases, by increasing the density of ionized molecules within the MPC, the ionizing radiation may trigger formation of plasma between the first and second electrodes (e.g., between the fingers of the first and second electrodes). In some embodiments, one or both electrodes may comprise a triggering finger, electrically connected to the corresponding electrode, and configured to form a triggering gap with the other electrode. In some such embodiments, the electrodes and the triggering fingers may comprise different electrically conductive compositions. For example, the electrode may comprise gold and the triggering fingers may comprise Ruthenium.

[0082] In some embodiments, the inter-electrode or inter-finger gaps and the triggering gaps, formed may be configured such that for a given pressure within the MPC and a given electric potential difference between the first and second electrodes, the electric charge transmitted through the triggering gaps comprises thermionic emission and the electric charge transmitted through the inter-electrode or inter-finger gaps comprise plasma discharge. In some such embodiments, a triggering gap can be smaller than an inter-electrode or inter-finger gap by a factor ranging from 2 to 6, from 6 to 10, from 10 to 14 or any ranges formed by these values or larger values.

[0083] FIG. 3 schematically illustrates first and second electrodes 301, 303, of a MPD each comprising a main electrode section and plurality triggering fingers. In some examples, the triggering fingers may be extended along a first lateral direction, and the main electrode sections 302, 304, may be extended along a second lateral direction perpendicular to the first lateral direction. In some cases, the triggering fingers of the first and second electrodes 301, 303, may be interleaved to form a plurality of triggering gaps, where an individual triggering gap is extended in the first lateral direction between a triggering finger of the first (or second) electrode 301 (303) and the main electrode section 304 (302) of the second (or first) electrode 303 (301). In some examples, the plurality of lateral triggering gaps may have substantially the same size (e.g., length along the first lateral direction). In some cases, the inter-electrode gap between the two main electrode sections 302, 304, may have a length Lp and the plurality of lateral triggering gaps may have a length L_te. In some cases, Lp may be within a plasma discharge range and L_te can be within a thermionic emission range. The inset in FIG. 3 schematically illustrates breakdown voltage of a MPD indicating that for a given MPC, and gas mixture and pressure within the MPC, the breakdown voltage may decrease within a thermionic emission distance range and increase within a plasma discharge distance range where the upper bound of the thermionic emission distance range is equal to a lower bound of the plasma discharge distance (e.g., 6 microns) at which the breakdown voltage is minimized. In some embodiments, when Lp is within the plasma discharge range and L_te is within the thermionic emission range, for a given MPC and a voltage applied between the first and second electrodes, 302, 304, the triggering gaps may emit ionizing radiation and trigger the formation of a plasma discharge between the first and second electrodes, 302, 304.

[0084] In some embodiments, an individual electrode finger may comprise a conductive structure (e.g., a thick conductive contact pad) formed on the top layer of the substrate and electrically connected to a contact pad (e.g., an electric terminal) by an electrode line formed inside the top layer (e.g., a dielectric layer formed in a substrate).

[0085] In some embodiments, the electrode fingers of the first electrode of a MPD may be aligned with respect to the electrode fingers of the second electrode of the MPD such that the plurality of inter-fingers gaps are formed between two longitudinal ends of opposing electrode fingers and are extended in the first lateral direction along which the electrode fingers are extended. FIG. 4A is an example MPD comprising a capping structure 208 and two electrode fingers 404aformed on a top layer 206 of the substrate 203 on which the capping structure 208 is formed. The MPD shown in FIG. 4A may comprise one or more features described above with respect to FIG. 2A. In some cases, the two electrode fingers 404a, 404b, form an inter-finger gap (e.g., the shortest distance between the two electrode-fingers) extended along a first lateral direction (e.g., along x- axis) between an edge of the electrode finger 404a and an edge of the electrode finger 404b. In some cases, the first electrode finger 404a may comprise a first thick conductive block electrically connected to a first conductive contact pad 406a by a first electrode line 402a and the second electrode finger 404b may comprise a second thick conductive block electrically connected to a second conductive contact pad 406b by a second electrode line 402b. In some cases, thickness of the first and second conductive blocks along a vertical direction normal to a major surface of the substrate 203 (e.g., along z-axis) can be from 0.1 to 5 microns.

[0086] FIG. 4B schematically illustrates another example MPD comprising a capping structure 208 and two electrode fingers 404a formed on a top layer 206 of the substrate 203. In some cases, the MPD shown in FIG. 4A may comprise one or more features described above with respect to FIG. 4A. In some embodiments, the MPD shown in FIG. 4A may comprise a middle electrode 408 formed in the top layer 206 and below the top major surface of the top layer 206. In some embodiments, the middle electrode 408 may be extended along the first lateral direction (e.g., along x-axis) substantially parallel to the top major surface of the substrate 203. In some cases, the middle electrode 408, also referred to as control electrode, may be configured to control the plasma 410 (e.g., microplasma) formed between the first and second electrode fingers 404a, 404b and may have a length along the first lateral direction shorter than the inter-electrode gap formed between the first and second electrode fingers 404a, 404b.

[0087] In some embodiments, the electrode lines 210a, 210b, 402a, 402b, and the middle electrode 408 may comprise highly doped semiconductors (e.g., highly doped silicon) formed in the top layer 206 (e.g., a silicon dioxide layer) dielectric layer and can be vertically separated from the top surface of the top layer 206. In some examples, the electrode lines 210a, 210b, 402a, 402b, and the middle electrode 408 may comprise different regions of a pattered conductive layer (e.g., a highly doped semiconductor layer) formed in the top layer 206 and vertically separated from the top major surface of the top layer 206.

[0088] In some embodiments, the electrode fingers of the MPDs 200, 202, the electrodes 301, 302, and the electrode fingers 404a, 404b, may comprise a patterned metal layerformed on the top layer 206. In some examples, the patterned metal layer can be fabricated by depositing a metal layer on the top layer 206 and patterning the metal layer using photobiography. In some examples, the patterned metal layer can be fabricated by depositing a metal layer on the top layer 206 via shadow mask. In some examples, the metal layer, and thereby electrodes and electrode fingers may comprise aluminum, copper, gold, or a combination thereof.

[0089] In various implementations, the electrodes and respective electrode fingers of a MPD may comprise conductive structures having different geometries (e.g., shapes and dimensions).

[0090] FIGS5A-5C schematically illustrates example electrode pair configurations that may serve as the electrodes of a MPD. In various implementations, these electrode pairs may be formed on or over a top major surface a substrate or at least partially within the substrate. In some examples, an electrode pair may be formed within a top layer of the substrate such that a top major surface of the substrate comprises a top major surface of the electrode pair.

[0091] FIG 5A schematically illustrates five example electrode pair configurations that may serve as the electrodes of a MPD. The example electrode pair 502 may include first and second electrodes 502a, 502b, electrically connected to first and second electric terminals, respectively. The first electrode 502a may comprise a first electrode pad (e.g., square shape pad) and at least one electrode finger that is electrically connected to the electrode pad and extended away from an edge of the electrode pad closer to the second electrode 502b, along a first lateral direction parallel to a major surface of the substrate. The second electrode 502b may comprise a second electrode pad (e.g., square shape pad) and at least one U-shape or dual prong electrode finger configured to form two parallel inter-electrode gaps with a finger of the first electrode 502b. In some examples, the U-shape electrode finger may comprise an elongated U-shape concave (recessed) region extended along the first lateral direction and configured to surround a longitudinal portion of the electrode finger.

[0092] The example electrode pair 504 may include first and second electrodes 504a, 504b, electrically connected to first and second electric terminals, respectively. The first and second electrodes 504a, 504b, each may comprise a plurality of triangular electrode fingers forming a plurality of inter-finger gaps, extended along a first lateral direction, with respective triangular electrode fingers of the other electrode. In some examples, the plurality of triangular electrode fingers can be formed along a second lateral direction, normal to the first lateral direction,at an edge of the corresponding electrode pad. In some examples the first and second electrodes 504a, 504b may be aligned such that the tip of an electrode finger of the first electrode forms an inter-electrode gap with the tip of an electrode finger of the second electrode. In other words, the shortest distance between the first and second electrodes is the separation between tips of respective electrode fingers along the first lateral direction.

[0093] The example electrode pair 506 may comprise a first plurality of electrodes fingers 506a electrically connected to a first electric terminal and a second plurality of electrode fingers 506b electrically connected to a second electric terminal where an individual electrode finger of the first plurality electrode fingers 506a forms two or more inter-finger gaps with two or more electrode fingers of the second plurality electrode fingers 506b. In the example shown, six electrode fingers of the second plurality electrode fingers 506b are distributed around an individual electrode finger of the first plurality electrode fingers 506a to from six inter-finger gaps. In some cases, each electrode finger may comprise a hexagonal shape and the six inter-electrode fingers may be formed by six edges of an electrode finger of the first plurality electrode fingers 506a and six edges of six electrode fingers of the second plurality electrode fingers 506b. Advantageously, by providing a large number of inter-finger gaps within a small area, the electrode pair 506 may facilitate formation of plasma and may enable fabrication of MPDs having a small form factor.

[0094] The example electrode pair 508 may include first and second electrodes 510a, 510b, each comprising an electrode pad and an electrode finger, where the electrode finger comprises a thick metal block formed at least partially on the electrode pad. First and second electrode fingers 511a, 511b, may form an inter-finger gap (shortest distance between the two electrode fingers) comprising a distance, along a first lateral direction, between an edge or vertical surface of the first electrode finger 511a and an edge or vertical surface of the second electrode finger 511b. In some examples, the first and second electrode pads 509a, 509b, may comprise rectangular shapes having widths along the first lateral direction and lengths along the second lateral direction.

[0095] The example electrode pair 510 may include one or more features described above with respect to the electrode pair 502 and electrode pair 508. A first electrode 510a of the electrode pair 510 may comprise a first electrode pad 507a and a first electrode finger 512a where the first electrode finger 512a is formed at least partially on the first electrode 510a. A second electrode 510b of the electrode pair 510 may comprise a second electrode pad 507b and a secondelectrode finger 512b comprising a U-shape or dual prong structure, formed at least partially on the second electrode 510b, and configured to form two parallel inter-electrode gaps with the first electrode finger 512a of the first electrode 510a. In some examples, the second electrode finger 512b may comprise an elongated U-shape concave (recessed) region extended along the first lateral direction and configured to surround a longitudinal portion of the first electrode finger 512a.

[0096] FIG 5B schematically illustrates two other example electrode pair configurations that may serve as the electrodes of a MPD. The example electrode pair 513 may include first and second electrodes 513a, 513b, formed on or over a substrate and electrically connected to first and second electric terminals, respectively. The first and second electrodes 504a, 504b, each may comprise a plurality of elongate electrode fingers electrically connected via a common electrode section and extended away from the common electrode section along a first lateral direction. In some cases, the first and second pluralities of the electrode fingers may be interleaved to form a plurality of inter-finger gaps, extended along a second lateral direction perpendicular to the first lateral direction. In some examples, an individual electrode finger of the first plurality of electrode fingers may form two inter-electrode gaps with two immediately adjacent electrode fingers of the second plurality of electrode fingers where each electrode gap comprises a separation between an edge or sidewall of the individual electrode finger and an edge or sidewall of an adjacent electrode finger.

[0097] The example electrode pair 516 may include two circular electrodes 516a, 516b, formed on or over a substrate 203 to form an inter-electrode gap comprising the shortest distance between an edge or side wall of the first circular electrode 516a and an edge or side wall of the second circular electrode 516b. Each of the first and second circular electrodes 516a, 516b, may be electrically connected to first and second electric terminals, respectively, e.g., by two separate electrode lines, formed in the substrate 203, each electrically connected to one of the first and second circular electrodes 516a, 516b by a vertical conductive via in the substrate 203.

[0098] FIG 5C schematically illustrates a plurality of electrode pairs formed on or over a substrate 203 where first and second electrode fingers 520a, 520b, of an individual electrode pair are electrically connected to first and second contact pads 406a, 406b via first and second electrode lines 402a, 402b, respectively. In some cases, different electrode pairs can be connected to different pairs of electrode pads where different pairs of electrode pads are electrically isolated to allow independent electrical connection and control for each electrode pair. In some examples, first andsecond electrode fingers 520a, 520b, may form an inter-finger gap extended along a first lateral direction parallel to a major surface of the substrate 203. In some examples, an individual electrode may comprise one or more features described above with respect to electrode pair 502, 508, or 510. In the example shown in FIG. 5C, an individual electrode may comprise an electrode pad 522b formed on or over the substrate 203 and an electrode finger 520b formed at least partially on the electrode pad 522b to establish electric contact with the electrode pad 522b. One or both the electrode finger 520b and electrode pad 522b may comprise a rectangular shape having a width along the first lateral direction and a length along a second lateral direction perpendicular to the first lateral direction. In some cases, the electrode finger 520b may comprise a thick conductive block (a metal block). In some embodiments, the electrode pad 522b may be formed on a top major surface of a substrate and can be electrically connected to an electrode line 402b formed below the top major surface of the substrate, e.g., by direct contact or by an intermediate conductive layer (e.g., by a conductive via).

[0099] FIG. 6A schematically illustrates an example MPD 602 comprising a MPC 205 formed by a capping structure 208 over a substrate 203 and a vertical inter-electrode gap formed between a bottom conductive layer 606 and a top conductive layer 604 vertically separated from the bottom conductive layer 606. In some embodiments, the MPD 602 may comprise one or more features described above with respect to MPDs 200, 202, in FIGS 2A-2B. In some embodiments, a first electrode of the MPD 602 may comprise the bottom conductive layer 606 formed on or above the top major surface of the substrate 203. In some cases, the bottom conductive layer 606 may be electrically connected to a first electrode line 402a formed in the substrate 203 below the top major surface of the substrate 203 (e.g., by a vertical via). The first electrode line 402a may be configured to electrically connect the bottom conductive layer 606 to a first conductive contact pad 406a. The second electrode of the MPD 602 may comprise the top conductive layer 604 suspended above the substrate 203 by a plurality of posts 610 vertically extended between the substrate 203 and the top conductive layer 604. In some cases, at least one of the posts 610 can be a conductive post electrically connecting the top conductive layer 604 to a second electrode line 402 formed in the substrate 203 below the top major surface of the substrate 203 (e.g., by a vertical via). The second electrode line 402b may be configured to electrically connect the top bottom conductive layer 604 to a second conductive contact pad 406a. In some cases, the capping structure 208 may be fabricated over the top and bottom conductive layers 604, 606, to form the MPC 205containing the top and bottom conductive layers 604, 606, and the inter-electrode gap therebetween, the MPC 205 may comprise a sealed (e.g., hermetically sealed) enclosure containing a gas or gas mixture with a specified composition and at a specified pressure. In some implementations, the second electrode may comprise a conductive bridge comprising the top conductive layer 604 and the plurality of posts 610. In some such cases, the plurality of the posts 610 and the top conductive layer 604 may comprise the same or different conductive materials (e.g., a metal such as aluminum, gold, copper, or a combination thereof). In some embodiments, at least a portion of a MPD 602 can be fabricated using a microelectromechanical systems (MEMS) fabrication technique (e.g., co-fabricated with a MEMS structure or device). For example, the suspended top conductive layer 604 and the plurality of posts 610 may be co-fabricated with a suspended MEMS structure (e.g., a conductive bridge or cantilever) using a plating process (e.g., a gold electroplating process) on a common substrate. In some cases, the capping structure 208 may be fabricated and bonded to the substrate 203 using common MEMS A and bonding techniques.

[0100] Advantageously, the large areas of the top and bottom conductive layers 604, 606 may allow formation of plasma and thereby current flow through a larger volume of the MPC 205, compared to electrode configurations described above with respect to FIGS. 2A-2B, 3, 4A- 4B, and 5A-5C, and thereby the MPD 602 can support a greater current flow between the first and second contact pads 406a, 406b, when the plasma is ignited (e.g., by an EOS event), compared to MPDs described above with respect to FIGS. 2A-2B, 3, 4A-4B or an MPD that uses the electrode structures shown in FIGS. 5A-5C.

[0101] In some embodiments, a first electrode of a MPD may be formed within or on an internal surface of the capping structure 208 and the second electrode may be formed closer to a major top surface of the substrate on which the capping structure is bonded (e.g., on, in, or above the substrate). In some embodiments, the first electrode may comprise a laterally extended conductive structure formed on or in the top portion or section of the capping structure, substantially parallel to and facing the top major surface of the substrate. In some embodiments, the second electrode may comprise a conductive layer formed on, above or in the top major surface of the substrate, forming a vertical inter-electrode gap vertically extending between the two electrodes across the corresponding MPC. For example, the MPD 602 may be modified by replacing the top conductive layer 604 supported by a plurality of posts 610 with a conductivelayer formed on or in the top section of the capping structure 208 (the horizontal section parallel to the top major surface of the substrate 203. In some cases, such electrode configuration may facilitate fabrication of a large area top electrode (e.g., by eliminating fabrication of the posts 610) and may allow further extending the top conductive layer to increase the maximum current that can flow between the two electrodes when the plasma is ignited (e.g., by an EOS event). In embodiments, the top electrode can be integrated with the capping structure 208 and can be electrically connected to the conductive connector pad 406b by vertical conductive paths formed in the capping structure or external wire bonds.

[0102] FIG. 6B schematically an example MPD 607 comprising a MPC formed by a capping structure 612 having a conductive region 613 and a vertical inter-electrode gap formed between the conductive region 613 and a conductive layer 606 formed on or within the substrate 203. In some cases, the conductive region 613 may be electrically connected to the second conductive pad 406b via the second electrode line 402b formed in the substrate 203 below the top major surface of the substrate 203 (e.g., by a vertical via). In some cases, the MPD 607 may comprise one or more features described above with respect to MPD 602.

[0103] As another example, the MPD 602 may be modified by removing the bottom conductive layer 606 and forming a conductive layer on or in the top section of the capping structure 208 such the top conductive layer 604 and the conductive layer formed on or in the top section of the capping structure 208, form a vertical inter-electrode gap. As such, in this case the top conductive layer 604 or the conductive bridge may serve as the bottom electrode of the MPD.

[0104] In some embodiments, the capping structure may comprise a highly doped semiconductor (e.g., highly doped silicon) and may be configured to serve as the top electrode. In some such cases, a lateral distance between the bottom electrode and the vertical section of the capping structure and a vertical distance between the bottom and the lateral section of the capping structure may be configured to allow formation of plasma and electric discharge between the bottom electrode and the capping structure. For example, the lateral distance between the bottom electrode and the vertical section of the capping structure can be larger than the vertical distance between the bottom and the lateral section of the capping structure.

[0105] In some embodiments, a portion of MPC of a MPD may be extended below the top surface of a substrate on which the MPD and corresponding capping structure is formed. In some such embodiments, the MPC may comprise an etched portion of the substrate comprisingone or more cavities formed in the substrate by etching a region of the substrate below the capping structure along a vertical direction perpendicular to the top major surface of the substrate (e.g., along z-axis). Advantageously, extending the MPC within the substrate may increase the interaction between electric field formed within the inert-electrode gas or interfinger gaps and the gas filing the MPC without fabricating suspended structures above the substrate.

[0106] FIGS. 7A-7B schematically illustrate vertical and top cross-sectional views of an example MPD 700 with a MPC comprising a capping structure 208 formed on an etched substrate 705. In some embodiments, the etched substrate 705 may comprise an etched top layer 707 formed on a bottom layer 204, and first and second pluralities of electrode fingers 702a, 702b, formed on or near a top major surface of the etched top layer 707. In some cases, the first and second pluralities of electrode fingers 702a, 702b, may be formed in the etched top layer 707 such that the top surface of etched top layer 707 comprises top surfaces of the and first and second pluralities of electrode fingers 702a, 702b. In some embodiments, the first and second pluralities of electrode fingers 702a, 702b, may be extended along a first lateral direction (e.g., along x-axis) and may be interleaved to form a plurality of inter-finger gaps extended along a second lateral direction perpendicular to the first lateral direction (e.g., along y-axis). In some examples, an electrode finger may comprise a highly doped semiconductor region or a metallic region formed in the etched top layer.

[0107] In some embodiments, a region of the etched top layer 707 below an interelectrode gap may comprise an etched cavity 704 fluidically connected to (or in fluid communication with) the first region or portion 703 of the PMC above the etched substrate 705. Advantageously, providing a cavity between adjacent electrodes may prevent interaction of the plasma with the etched top layer 707, which may damage the etched top layer 707 (e.g., silica layer). In some examples, a length of the etched cavity along the first lateral direction (x-axis) can be equal or smaller than a length of an individual electrode finger, a maximum width of the etched cavity along the second lateral direction (y-axis) can be equal or larger than the inter-ginger gap (g), and a depth of the etched cavity along the vertical direction (z-axis) can smaller or equal to the thickness of the etched top layer 707.

[0108] In various implementations, the etched top layer 707 may comprise a dielectric or a semiconductor material and the inter-electrode cavities may be formed by wet or dry etching. In some examples, the electrode fingers may be used as an etching mask for fabrication of theinter-electrode cavities. In some cases, one or more etched cavities may be extended to the bottom layer 204 of the substrate such that a bottom surface of an inter-electrode cavity comprises a top surface region of the bottom layer 204. In some cases, the bottom layer 204 may serve as an etch stop.

[0109] In some embodiments, the capping structure 208 may be formed above the electrode fingers and the etched gaps therebetween to form a composite MPC comprising a first region or portion 703 enclosed in the capping structure 208 and a second region or portion comprising a plurality of inter-electrode cavities formed in the etched top layer 707.

[0110] In some applications, a MPD, e.g., an MPD configured as an EOS monitor or protection device may be configured to handle high electric current (e.g., during a short electric discharge event or a period of continues current flow through a spark gap). In some embodiments, the overall current handling capacity of such MPD may be improved by dividing the current across multiple inter-finger gaps connected in parallel (e.g., similar to the MPDs 200. 202, or 700 described above). However, providing multiple inter-finger gaps may not lead to sufficiently high current handling capability under some circumstances, because the current may not necessarily flow through all of the multiple inter-finger gaps, or through all of the inter-finger gaps in substantially equal amounts. This is because the current may flow preferentially through a path of least resistance that can include a single or a small subset the multiple spark gaps. In some embodiments, providing a series resistance with particular magnitudes across the paths of electric current flow through one or more of the inter-finger gaps, e.g., by connecting the series resistors between the electrode fingers and the corresponding contact pad or voltage nodes, the MPD can be induced to conduct the current through multiple inter-finger gaps. These series resistors between the electrode fingers and a contact pad or voltage nodes is also referred to herein as series ballast resistors.

[0111] In some embodiments, each one of the first pluralities of the electrode fingers 702a may be electrically connected to a first terminal (Tl) by a ballast resistor 7061, 706-2, 706- 3, or 706-4. In some examples, the ballast resistors 7061, 706-2, 706-3, or 706-4 may comprise substantially the same resistance. In some examples, the first pluralities of the electrode fingers 702a may be connected to a common node by individual ballast resistors 7061, 706-2, 706-3, or 706-4, and the common node may be electrically connected to the first terminal Tl via a surge control resistor 708. In some embodiments, the second pluralities of the electrode fingers 702bmay be directed connected to a second terminal (T2). However, the embodiments are not so limited and, in some cases, the second pluralities of the electrode fingers 702b may be electrically connected to the second terminal (T2) by individual ballast resistors and, in some cases, additionally a common surge resistor.

[0112] In some embodiments, a MPD may comprise an MPC formed below the top layer of the substrate in the bottom layer of an etched substrate. In some such embodiments, one of the electrodes of MPD, e.g., a bottom electrode, may be formed below the top layer at or near the bottom surface of the MPC. In some cases, the other electrode of the MPD, e.g., a top electrode, can be formed in the top layer to form a vertical interelectrode gap extended from a top surface of the bottom electrode to a bottom surface of the top electrode. In some embodiments, MPD may additionally comprise a capping structure formed on the top layer to isolate the MPC from the surrounding environment and maintain a specified composition and pressure inside the MPC. In some cases, a volume enclosed in the capping structure (a capped volume) can be fluidically connected to the MPC by one or more openings (e.g., though holes) formed in the top layer.

[0113] FIGS. 8A-8B schematically illustrate example MPDs comprising a MPC 805 formed below an etched or patterned top layer 809 and in an etched bottom layer 807 of an etched substrate 705. The MPD 800 shown in FIG. 8A may comprise a bottom electrode 804a formed in the etched bottom layer 807 and electrically connected to electrode lines 803 a, 803b formed in the patterned top layer 809. In some implementations, the bottom electrode 804a may comprise a lateral portion laterally extended in the etched bottom layer 807 below MPC 805 and a vertical portion vertically extended from the lateral portion to an interface between the patterned top layer 809 and the etched bottom layer 807. In some examples, the vertical portion can be electrically connected to the electrode lines 803a, 803b, via one or more conductive vias formed in the patterned top layer 809, thereby electrically connecting the lateral portion to the two electrode lines 803a, 803b, which can be connected to a first electric terminal or voltage node. In some cases, the bottom electrode 804a may comprise a highly doped region formed in the etched bottom layer 807.

[0114] In some embodiments, the MPC 805 may comprise an isotopically etched region of the etched bottom layer 807 vertically extended from the interface between the patterned top layer 809 and the etched bottom layer 807 to the lateral portion of the bottom electrode 804a. In some cases, a bottom surface of the MPC 805 may comprise a top surface of the lateral portion of the bottom electrode 804a.

[0115] In some embodiments, one or both lateral and vertical portions of the bottom electrode 804a may comprise graded dopant concentration. In some cases, the lateral portion may have a height along the vertical direction and its dopant concentration may be graded along the vertical direction such that a peak dopant concentration is at or near a middle vertical position with respect to height. In some embodiments, the MPC 805 may be vertically extended to a vertical position at or near the peak dopant concentration in the lateral portion of the bottom electrode 804a. Advantageously, in these embodiments, the highly conductive region of the lateral portion the bottom electrode 804a can be in contact with the gas mixture in the MPC 805 to facilitate formation of plasma in the MPC 805. In some embodiments, the vertical region of the bottom electrode 804a can be electrically isolated from MPC 805 by a region of the etched bottom layer 807 between the MPC 805 and the vertical region. In some embodiments, the vertical region of the bottom electrode 804a may at least partially surround the MPC 805 to provide shorter electrical paths between the lateral portion of the bottom electrode the bottom electrode and the electrode lines 803a, 803b.

[0116] In some embodiments, the top electrode 804b of the MPD 800 may comprise a plurality of electrode fingers vertically extending from respective electrode pads, formed in the top patterned layer 809, to a bottom surface of the patterned top layer 809. In some cases, an individual electrode pad may comprise a conductive region (e.g., a highly doped semiconductor region) and an individual electrode finger may comprise a conductive via (e.g., a metallic via). In some cases, a bottom surface or a tip of the electrode finger can be in electric contact with the gas molecules I the MPC 805. In some cases, the plurality of electrode fingers of the top electrode 804b may form a plurality of inter-electrode gaps with the bottom electrode 804a, where an interelectrode gap comprises a vertical separation between the top surface of the bottom electrode 804a and a bottom surface of the electrode finger. In some embodiments, the electrode fingers of the top electric 804b may be laterally separated by though holes vertically extended across the top patterned layer 809.

[0117] In some embodiments, the MPD 800 may comprise a capping structure 208 formed on the top patterned layer 809 above the MPC 805 and configured to enclose at least the through holes formed in the patterned top layer 809. In some cases, a capped volume 806 formed between the capping structure 208 and the top patterned layer 809 may be fluidically connected to the MPC 805 via the though holes formed in the top patterned layer 809. As such, the cappingstructure 208 may be configured to isolate the MPC 805 from the surrounding environment and maintain a specified composition and pressure within the MPC 805.

[0118] FIG. 8B schematically illustrates another example MPD 802 comprising a MPC 811 formed below the patterned top layer 809 and in the etched bottom layer 807 of an etched substrate 705. In some embodiments, the MPD 802 may comprise one or more features described above with respect to the MPD 800. In some embodiments, the MPD 802 may additionally comprise current control barriers 808 formed within the etched bottom layer 807 and configured to control and / or redirect electric current flow from the lateral region to the vertical region of the bottom electrode 804a. In some implementations, the current control barriers 808 may be vertically extended from a bottom surface of the top patterned layer 809 to a middle region of the lateral portion of the bottom electrode 804a (e.g., near the peak dopant concentration), to form side walls of the MPD 802. In some implementations, the current control barriers 808 may comprise a dielectric material (e.g., silicon dioxide, silicon nitride, or the like). In some implementations, an individual current control barrier may comprise a polysilicon core covered by a silicon dioxide layer that isolates the polysilicon core from the substrate 102 (e.g., the silicon substrate).

[0119] FIG. 8C schematically illustrates another example MPD 814 comprising a MPC 816 formed below the patterned top layer 809 and in the etched bottom layer 807 of an etched substrate 815. In some embodiments, the MPD 814 may comprise one or more features described above with respect to MPD 802. In some embodiments, the etched bottom layer 807 of the MPD 814 may comprise a dielectric layer 812 serving as a lateral isolating layer for MPC 816. In some such embodiments, the MPC 816 may be laterally extended between control barriers 808 formed within the etched substrate 815 and vertically extended between the patterned top layer 809 and the dielectric layer 812. In some embodiments, the MPD 814 may comprise two laterally separated electrodes 810a, 810b, formed in the patterned top layer 809. In some embodiments, the first electrode 810a may comprise a first plurality of electrode fingers vertically extended from a first electrode line 803a to the MPC 816 and the second electrode 810b may comprise a second plurality of electrode fingers vertically extended from a second electrode line 803a to the MPC 816. The first electrode line 803 a may electrically connect the first plurality of electrode fingers to a first electric terminal (first voltage node) and the second plurality of electrode fingers to a second electric terminal (second voltage node). In some examples, a bottom surface or a tip of an individual electrode finger can be in electric contact with the gas molecules in the MPC 816. Insome embodiments, the patterned top layer 809 of the MPD 814 may comprise one or more through holes (pass-through holes) vertically extended across the top patterned layer 809.

[0120] In some embodiments, the MPD 814 may comprise a capping structure 208 formed on the top patterned layer 809 above the MPC 805 and configured to enclose at least the through holes formed in the patterned top layer 809. In some cases, a capped volume 806 formed between the capping structure 208 and the top patterned layer 809 may be fluidically connected to the MPC 816 via the though holes formed in the top patterned layer 809. As such, similar to MPD 802 the capping structure 208 may be configured to isolate the MPC 816 from the surrounding environment and maintain a specified composition and pressure within the MPC 816.

[0121] In some embodiments, the capping structure 208 of any of the MPDs described above, may be tailored and engineered to provide electric connection between the capping structure and the substrate on which the capping structure is formed or to include layers or regions having properties usable to control certain chrematistics of the plasma formed in the MPC. As described above, in some embodiments, a capping structure or an engineered capping structure may be fabricated separate from the substrate and then bonded to the MPD substrate. In some such amendments, a plurality of capping structures may be fabricated (e.g., monolithically fabricated) by pattering a wafer or chip and dicing the patterned wafer or chip to provide individual capping structures for bonding to separately fabricated MPDs.

[0122] FIGS. 9A-9C schematically illustrate example patterned substrates (e.g., patterned wafers), each comprising a plurality of capping structures, prior to singulation.

[0123] In some embodiments, a patterned substrate 902, and thereby the resulting capping structures, shown in FIG.9A may comprise a uniform material composition.

[0124] In some embodiments, the patterned substrate 904 shown in FIG.9B may comprise a heterogeneous structure different from the wafer or substrate used to fabricate the patterned structure. In some cases, the patterned substrate 904 may include a region 905 comprising a dielectric, conductive, or magnetic material. In some cases, the region 905 may be formed within a top portion or layer of an individual capping structure (e.g., a portion parallel to the substrate to which the capping structure is configured to be bonded). In some cases, the region 905 of the individual capping structure may be vertically extended from a top surface of the top layer to a middle position above a bottom surface of the top layer. In some embodiments, the region 905 may comprise an implanted dopant profile.

[0125] In some embodiments, the patterned structure 906 shown in FIG.9C may comprise a conductive region 907 (e.g., a conductive via) within a top portion or layer of individual capping structures (e.g., a portion parallel to the substrate to which the capping structure is configured to be bonded). In some cases, the conductive region 907 of an individual capping structure may be vertically extended from a top surface of the top layer to bottom surface of the top layer thereby providing electrical connection between a surrounding environment and internal volume (caped volume) of the individual capping structure. In some embodiments, the conductive region 907 may comprise aluminum, gold, copper, chromium, other conductive materials, or a combination thereof. In some embodiments, the conductive region 907 may comprise highly doped polysilicon.

[0126] In some embodiments, the capping structure of a MPD may comprise a conductive region or a conductive layer formed on an external or internal surface of the capping structure.

[0127] In some embodiments, the conductive region of a capping structure (e.g., capping structure singulated from the patterned structure 906) may be configured to serve as an electrode of the corresponding MPD fabricated using the patterned structure 906.

[0128] FIG. 10 schematically illustrates example conductive regions that may be formed in a capping structure or on a surface of a capping structure. As shown in FIG. 10 the conductive regions can have different geometries, each configured to provide certain functionalities with respect to the MPD and formation and control of a plasma formed in the corresponding MPC (e.g., some of these conductive patterns may be used as one of the electrodes, e.g., a top electrode, of a MPD).

[0129] In various implementations, the inter-electrode or the inter-finger gap can be from 1 to 2 microns, from 3 to 4 microns, 4 to 6 microns, 6 to 8 microns, 8 to 10 microns, 10 to 16 microns, or any values formed by these values or larger or smaller values.

[0130] In various implementations, the pressure of the gas mixture in the MPC can be from 0.1 to 1 pascals, 1 to 10 pascals, 10 to 100 pascals, 100 to 1000 pascals, or any values formed by these values or larger or smaller values.

[0131] In various implementations, the gas mixture in a MPC may comprise a nitrogen, argon, xenon or another inter gas or a gas having low ionization potential. In some cases, gasmixture in a MPC may comprise a first gas with lower ionization potential and a second gas with a higher ionization potential, where the first gas serves as a trigger for the second gas.

[0132] In various implementations, for various MPD configurations described above the pressure inside the MPC and the inter-electrode or inter-finger gaps may be configured to prevent electric discharge via a spark between the two electrodes.

[0133] In some examples, the electrode and electrode fingers of an MPD may comprise, TiW, ruthenium, gold, aluminum, copper, or a combination thereof. In some examples, an electrode or electrode finger of an MPD may comprise polysilicon (e.g., highly doped poly silicon).

[0134] FIGS. 11A-11B schematically illustrate example MPDs comprising capping structures 1101, 1108 configured to provide electric connection between a structure or layer 1004 formed on a major top external surface of the capping structure 1101 or 1108 and a conductive line or a connector pad formed on or in an etched substrate 1104 or 1107. In the examples shown in FIGS. 11 A-l IB, the layer 1004 is electrically connected to the etched substrates by a conductive line or region 1102 vertically extended in the capping structure 1101 or 1108 between the layer 1004 and the etched substrates 1104, or 1107. In some implementations, the layer 1004 may comprise a conductive layer or an electro-active layer. In some implementations, the layer 1004 can be a conductive layer configured to provide a low resistive sink for electrical current and thermal heat.

[0135] The MPD shown in FIG .11A may comprise one or more features described above with respect to MPD 814. In some embodiments, the MPC of the MPD shown in FIG .11A may comprise a cavity formed in an etched bottom layer 807 of the etched substrate 1104. In some examples, bottom surface and the sidewalls of the MPC 805 may comprise teched surfaces of the etched substrate 1104. In some cases, the patterned top layer 1105 of the etched substrate 1104 may comprise a plurality of through holes and a plurality of middle electrode fingers 1109 formed in the patterned top layer 1105 between the through holes and electrically isolated by the through holes. In some examples, the plurality of middle electrode fingers 1109 may be configured to control a plasma formed between the first and second electrodes 810a, 810b. In some cases, an individual middle electrode finger can be electrically connected to a highly doped region in the patterned top layer 1105 through which the middle electrode finger may receive a control signal.

[0136] The MPD shown in FIG .1 IB may comprise a MPC 1110 formed in an etched substrate 1107 and a capping structure 1108 bonded to the etched substrate 1107. In some cases, the etched substrate 1107 may comprise a patterned layer 1112 and the MPC 1110 may be vertically extended from a top major surface of the etched substrate 1107 to the patterned layer 1112. In some cases, the patterned layer 1112 may comprise one or more features described above with respect to the patterned top layer 1105. For example, the patterned layer 1112 first and second electrodes and middle electrode fingers positioned at the bottom of the MPC 1110 and configured to generate and control plasma in the MPC 1110.

[0137] FIG. 12 schematically illustrates an example process for fabricating the capping structure 1001 described above with respect to FIG. 11 A. The fabrication process may compromise forming vertical conductive lines 1102 or vias in a chip or wafer 1200, forming a patterned structure 1202 by patterning (e.g., etching) a major surface of the chip or wafer 1200 comprising the vertical conductive lines 1102, forming a composite structure 1204 by forming a layer 1004 (e.g. a conductive or electroactive layer) on a non-patterned major surface of the patterned structure 1202, and dicing the composite structure 1204 to singulate capping structures 1206-1, 1206-2, ..., 1206-n, which may comprise one or more features described above with respect to capping structure 1101.

[0138] FIG. 13 schematically illustrates an example process for fabricating MPDs comprising the capping structure 1003 described above with respect to FIG. 11B. The fabrication process may compromise forming vertical conductive lines 1102 or vias in a chip or wafer 1302, forming a capping structure 1304 by forming electrical contacts 1310 on a first major surface of the chip or wafer 1302 above respective conductive lines 1102, where individual electrical contacts 1310 are electrically connected to the individual conductive lines 1102, forming a patterned structure 1306 comprising a plurality of etched cavities (e.g., substantially identical cavities), where an individual cavity of the plurality of etched cavities may be configured to serve as a MPC, and bonding a second major surface of capping structure 1304, opposite to the first major surface, to a MPD structure 1308 comprising a plurality of MPDs.

[0139] As described above in some embodiments, electrical connection between the capping structure, or a layer formed on the capping structure, and the substrate, e.g., a conductive region of the substrate, may be provided by a conductive line or region formed in the capping structure or a wire bond, ribbon bond, or conductive clip (e.g., copper clip) separate from thecapping structure. FIGS. 14A-14C schematically illustrate example MPDs having capping structures electrically connected to a substrate on which the capping structures are formed. The capping structure of the MPD shown in FIGS. 14A-14C may compromise one or more features described above with respect to capping structure 1101 of MPD shown in FIG. 11A. In some cases, the capping structure shown in FIGS 14A-14C can be one of the capping structures 1206-n singulated from the composite structure 1204 described above with respect to FIG. 12.

[0140] The capping structure of the MPD shown in FIG. 14A may comprise electric contacts 1310 (e.g., copper pillars or other high current electric contacts) electrically connected to the vertical conductive lines 1102 and configured to provide electric connection between the vertical conductive lines 1102 and another electronic device or circuit. In some cases, each conductive line 1102 may be connected to one of the electric contacts 1310 to one of the electrodes of MPD. The capping structure of the MPD shown in FIGS. 14B-14C may comprise electrically conductive clips (e.g., copper clips) or ribbons 1402 configured to electrically connect the conductive lines 1102 or a conducive structure formed on the capping structure to a conductive contact pad formed on the substrate. Thus, in some cases, the conductive clips 1402 may electrically connect the electrodes of the MPD to a conductive contact pad, e.g., a conductive contact pad connected to a voltage node. Advantageously, providing electrical connection to the electrodes of the MPD via electrically conductive clips may allow the MPD to transmit a larger current and be used for high current applications, e.g., when the MPD is used as a high current surge protector. In some embodiments, where the MPD comprises a top electrode formed on top lateral section of the capping structure, the electric contacts 1310 or conductive clips or ribbons 1402, may be connected to the top electrode by a short via passing through the top lateral section of the capping structure.

[0141] FIG. 15 schematically illustrates an example MPC 805 comprising a capped volume (top chamber portion) 1503. In some cases, the capped volume 1503 can be formed by a capping structure 1501 comprising a secondary reservoir 1502 configured to trap certain gas molecules and thereby control the pressure and / or composition of the gas mixture in the capped volume 1503 (and thereby the MPC 805). In some examples, the capped volume 1503 may comprise a getter layer 1504 formed on top horizontal internal surface of the capping structure 1501, and the secondary reservoir 1502 may comprise a horizontal getter layer 1505 and a verticalhorizontal getter 1506 formed on bottom surface and a sidewall of the secondary reservoir, respectively.

[0142] FIGS. 16A-16E schematically illustrate engineered capping structures having tailored geometrical and structural features. The capping structure shown in FIG. 16A comprises two layers 1602-1, 1602-2 separated by an air gap 1604 and can be configured to regulate the pressure inside the chamber. The capping structure shown in FIG. 16B comprises two layers 1602- 1, 1602-2 separated by an electro-active layer 1606 (e.g., a piezoelectric layer) and can be configured to regulate the pressure inside the chamber. The capping structure shown in FIG. 16C comprises two layers 1602-1, 1602-2 separated by a composite material or laminate 1607. The capping structure shown in FIG. 16D and 16E comprise a convex and concave top sections.

[0143] In various implementations a piezo electric layer may be formed over an inner surface and / or an outer surface of the capping structure to control gas pressure inside the MPC. FIGS. 16F-16J schematically illustrate example capping structures each comprising a piezoelectric layer 1614.

[0144] In various embodiments, the a gettering layer (getter layers 209, 1505, 1504, or 1509) can be configured to getter one or both of oxygen and moisture in an enclosed volume (in an MPC or a capped volume above an MPC).Microplasma Devices with Recessed Microplasma Chamber

[0145] In some embodiments, a MPD may comprise a recessed MPC formed in a substrate (e.g., silicon substrate) and is fluidically isolated from the surrounding atmosphere by a capping structure formed on or above the substrate and the MPC. In some embodiments, the MPD may comprise at least two electrodes configured to strike and sustain plasma in the MPC in response to an electric potential difference applied therebetween.

[0146] In some embodiments, the capping structure may comprise a dielectric layer (e.g., silicon dioxide) configured to electrically isolate at least a portion of one or both an electrode line and an electrode from one or both the substrate and the gas molecules inside the MPC. In some examples, the capping structure may comprise a metallization layer comprising a metallic layer formed therein where the metallic layer is configured to serve as one or both the electrode and the electrode line.

[0147] In some cases, an electrode line may comprise a conductive structure configured to provide electrical connection between the gas molecules in the MPC and a voltage node via a portion of the electrode line serving as an electrode or an electrode. In some cases, the conductive structure may comprise a highly doped semiconductor (e.g., highly doped silicon), a metal or a combination thereof. In some cases, an electrode line can be electrically connected to an electrode by conductive via formed in the substrate. In some cases, the electrode line may be formed in or on the capping structure.

[0148] In some embodiments, an electrode may comprise a conductive layer or structure having a surface in electric contact with the gas molecules in the MPC or with a region of the substrate where electric charge can be transmitted between the gas molecules and the electrode through the surface. In some embodiments, an electrode may comprise a region of an electrode line above the MPC or in electric contact with the substrate. In some embodiments, a surface of at least one of the electrodes may be exposed to the recessed MPC and thereby to the gas molecules therein. In some cases, an electrode may comprise one or more electrode fingers extended (e.g., along a vertical direction perpendicular to a major surface of the substrate) between the MPC and an electrode line. In some cases, one of the electrodes may be formed in or on the capping structure. In some cases, one of the electrodes may be formed in the substrate near the MPC. In some such embodiments, a bottom internal surface of the MPC may comprise a top surface of the electrode. In various embodiments, an interelectrode gap or spacing formed between the first and second electrodes that generate and sustain the plasma in the MPC may be laterally extended parallel to a major surface of the substrate or vertically extended perpendicular to the major surface of the substrate.

[0149] In some cases, the MPC may comprise a dielectric region formed in the substrate and configured to electrically isolate a portion of the recessed volume of the MPC from the substrate. In some such cases, the dielectric region may serve as a barrier configured to electrically isolated at least a portion of the MPC from the substrate. In some examples, the barrier may comprise a current barrier configured to at least partially block current flow between an electrode and the gas molecules in the MPC, through the substrate. In some examples, the dielectric region may comprise a vertical wall (e.g., a trench oxide) extended in a direction normal to a major surface of the substrate. In some examples, the dielectric region may comprise a horizontal layer(e.g. a buried oxide layer) laterally extended in a direction parallel to the major surface of the substrate.

[0150] In some cases, a MPD that generates and sustains plasma may allow using the electrical and electro-optical characteristics of the plasma to provide functionalities that may not be easily accessible by commonly used solid-state integrated electronic and optoelectronic devices and components. These functionalities may be used to design electronic and optoelectronic circuits and systems for a variety of applications including but not limited to sensing (e.g., gas sensing), protection against EOS, surge protection, RF signal generation, electronic switching or amplification, and other applications. The inventors have discovered that, by utilizing existing fabrication methods and technologies (e.g., methods used for fabricating integrated circuits and microelectromechanical systems), a microplasma device can be fabricated on chip to generate, sustain, and control a microplasma within an on-chip cavity and provide electrical and optical access to the microplasma to exploit its electronic and optical characteristics in different applications. In some embodiments, the microplasma devices described below may be cofabricated with one or more electronic and / or optical devices on a common chip and can electronically and / or optically communicate with these electronic and / or optical devices via on- chip or off-chip connections.

[0151] In some cases, disclosed MPDs (describe above and below) may allow using electronic and optical properties of an on-chip plasma formed in an MPC for providing, e.g., electronic oscillation, non-linear current-voltage relation, high current connections, electronic switching, electronic amplification, optical modulation, electrical overstress protection and monitoring, optical molecule detection, light generation and the like.

[0152] FIG. 17A illustrates a top view (top panel) and a cross-sectional view (bottom panel) of an example integrated MPD 1700 configured to generate and sustain the plasma 410 in a substrate 1702, according to some embodiments. In some cases, the substrate 1702 can be a region or a chip or wafer (e.g., a semiconductor chip or wafer). In some cases, the chip or wafer may comprise another device (e.g., an electronic device fabricated on the chip). In some cases, the other device can be electrically connected to the MPD 1700. In some embodiments, the MPD 1700 may include a recessed MPC 1714 comprising a sealed (e.g., hermetically sealed) volume configured to contain a gas or gas mixture and, in some cases, maintain a property (e.g., pressure,partial pressure, composition, or the like) of the gas or gas mixture and allow formation of plasma by at least two electrodes of the MPD 1700 for a transitory or extended period.

[0153] In some cases, the MPC 1714 may comprise a recessed volume (cavity) formed in the substrate 1702 (e.g., below a major horizontal surface of the substrate) and a capping layer 1704 formed over the MPC 1714 and substratel702 and configured to seal the recessed volume.

[0154] In some examples, the substrate 1702 may comprise a semiconductor (e.g., silicon), a glass (e.g., silicon dioxide), silicon carbide, a ceramic, a laminate or composite structure (e.g., a multilayer structure).

[0155] In some examples, the capping layer 1704 may comprise silicon, a glass (e.g., silicon dioxide), another dielectric material (e.g., a silicon-based dielectric material). A ceramic material, a composite material, a laminate, a composite structure or any combination thereof. In some cases, the capping layer 1704 may comprise a multilayer structure.

[0156] In some the capping layer 1704 (e.g., dielectric capping layer) may include a conductive layer configured to provide electric connection with the gas molecules in the MPC 1714. In some examples, the conductive layer may comprise a highly doped semiconductor or a metal. In some examples, at least a portion of the conductive layer may be formed in the dielectric layer 1704.

[0157] In some examples, a first electrode of the MPD 1700 may comprise one or more electrode fingers 1710 formed in the capping layer 1704 and electrically connected to a first terminal (e.g., a first voltage node) by a first electrode line 1706a. In some cases, the first electrode line 1706a may comprise a laterally extended conductive layer formed in the dielectric layer 1704 and at least some of the one or more electrode fingers 1710 can be vertically extended from the first electrode line 1706a to the MPC 1714.

[0158] In some examples, an end surface of at least one electrode finger is in direct electric contact with the gas molecules in the MPC 1714. In some examples, at least one electrode finger can be electrically isolated from the gas molecules in the MPC 1714 (e.g., by a portion of the capping layer 1704).

[0159] A second electrode of the MPD 1700 may comprise a conductive region 1717 formed in the substrate 1702 below the horizontal major surface of the substrate 1702 and electrically connected to second terminal (e.g., a second voltage node) by a second electrode line 1706b. In some examples, the conductive region 117 may comprise a doped semiconductor (e.g.,highly doped polysilicon). In some cases, the second electrode line 1706b may comprise a laterally extended conductive layer formed in the capping layer 1704 and the conductive region 1717 can be electrically connected to the second electrode line 1706b by one or more conductive vias 1707 vertically extended between second electrode line 1706b and the conductive region 1717.

[0160] In some cases, one or more electrode fingers 1710 and the conductive region 1717 may be laterally separated by a gap 1705 (gp), e.g., a lateral gap, where the gap 1705 at least partially overlaps with the underlying MPC 1714. In some implementations, the gap 1705 can be from 6.0 to 20 microns, from 20 to 1000 microns, or any ranges formed by these values, or larger or smaller values. In some cases, the gap 1705 may comprise the shortest electric path between the one or more electrode fingers 1710 and the conductive region 1717 that can be established through the MPC 1714. In some embodiments, the one or more electrode fingers 1710 and the conductive region 1717 may be configured to generate and sustain the plasma 410 in the MPC 1714.

[0161] In some implementations, first and second electrodes of the MPD 1700 may be further configured to provide electrical connection to the plasma 410, e.g., to exploit electrical properties (e.g., nonlinear electrical properties) of the microplasma. For example, the electrodes may provide an electrical path through the plasma 410 and allow the plasma 410 to serve as a component in an electronic circuit. In some examples, the electronic circuit may comprise one or more electronic components fabricated on substrate 1702 and electrically connected to the plasma 410, e.g., via the electrodes. In some embodiments, first and second electrodes of the MPD 1700 may be used to generate and sustain the plasma 410 and two additional electrodes may provide electrical connection between the microplasma 103 and other components.

[0162] In some embodiments, the MPD 1700 may be fabricated by forming a cavity (e.g., using wet or dry etching techniques such as xenon difluoride etching) below a major surface of the substrate 1702 and then bonding the capping layer 1704 on a major top surface of the substrate 1702 above the etched cavity. In some examples, at least a portion of the first electrode line 1706a, electrode fingers 1710, and the second electrode line 1706b may be embedded in the capping layer 1704 prior to bonding. In some examples, at least a portion of the first electrode line 1706a, electrode fingers 1710, and the second electrode line 1706b may formed on the capping layer 1704 after bonding. In some embodiments, the MPD 1700 may be fabricated by forming an initial dielectric layer over the substrate 1702, forming the cavity in the substrate 1702, and sealing the cavity to form MPC 1714. In some such embodiments, the capping layer 1704 may compriseone or more through-holes or openings 1718 (e.g., slots having rectangular or other shapes) configured to allow etching the chamber cavity below the capping layer 1704 and filing the chamber cavity with a desired gas mixture and pressure. In some such implementations, the through-holes 1718 may be covered or at least partially filled to seal the chamber 1714 (e.g., by forming a cladding layer on or over the openings). In some embodiments, a material composition of the capping layer (e.g., dielectric capping layer) 1704 may be selected or determined based at least in part on a specific application for the MPD 1700. In some embodiments, a material composition and / or a structure of the capping layer 1704 may be determined based at least in part on a component integrated or incorporated with the capping layer 1704. In some examples, the component may comprise a conductive trace, a heating element, a conductive vias, a coil, a magnetic structure, and the like. In various embodiments, the capping layer 1704 and integrated components therein may be fabricated using chemical vapor deposition techniques, sputtering, plating, screen-printing, bonding / attaching, prefabricated structures, and the like. In some embodiments, the capping layer 1704 may prefabricated and then bonded (or attached) to the substrate using glass frit, anodic bonding, eutectic bonding, adhesive paste or other methods. In some embodiments, the fabrication processes used to fabricate the capping layer 1704 may be selected based at least in part on the requirements of a specific application and corresponding operational / environmental conditions .

[0163] In some examples, MPC 1714 may be filled with a gas or a gas mixture having a specified pressure before being sealed. For example, chamber 1714 may be sealed in an atmosphere comprising a desired gas (or gas mixture) having a specified pressure. In some implementations, the internal pressure inside the MPC can be lower relative to the atmosphere outside the MPC. In some implementations, the internal pressure of the MPC can be greater relative to the atmosphere outside the MPC. In some cases, the specified pressure of the gas can be from 0.1 to 10 millitorrs, from 10 to 100 millitorrs, from 100 to 760 millitorrs or any ranges formed by these values or larger or smaller values. In some cases, the gas or gas mixture may comprise nitrogen, helium, neon, argon, xenon or a combination thereof. In various implementations, bonding the capping layer 1704 and / or fabrication of the electrodes of the MPD 1700 may comprise aligning the lateral gap (gp) 1705 between the electrodes with respect to the MPC 1714 such that the gap 1705 at least partially overlaps with the chamber 1714.

[0164] In some cases, the first electrode line al706a and / or the electrode fingers 1710 may comprise a first conductive layer laterally extending from a first end of the gap 1705 away from the second electrode line 1706b and conductive region 1717 may comprise a second conductive layer laterally extending from a second end of the gap 1705, opposite to the first end, away from the first electrode line 1706a.

[0165] In some embodiments, MPC 1714 and the electrode fingers 1710, the lateral gap 1705, and the conductive region 1717 may be configured to form the plasma 410 inside MPC 714 upon applying an electric potential difference between the first and second electrode lines 1706a, 1706b, and thereby the electrode fingers 1710 and the conductive region 1717. For example, the geometry (e.g., shape, depth, width, and the like) of the MPC 1714 may be configured to allow formation and stability of the plasma 410 inside the chamber 1714 (e.g., in a region of the chamber 1714 below the gap 1705 (e.g., between the electrodes of the MPD 1700) such that a current flow between the electrode fingers 1710 and the conductive region 1717 can be established at least partially through the microplasma and, in some cases, through a portion of the substrate 1702. In some embodiments, at least a portion of the electrode fingers 1710 (first electrode) can be directly in contact with the plasma 410 and the conductive region 1717 (second electrode), which is electrically isolated from the first electrode, may be formed away from the MPC 1714 and can be electrically and directly in contact with the substrate 1702. In some such embodiments, the first electrode line 1706a and thereby electrode fingers 1710 may be electrically connected to electrical ground and the first electrode line 1706b and thereby the conductive region 1717 can be electrically connected to a positive or negative voltage with respect to ground. In some implementations, the second electrode line 1706b and the conductive region 1717 can be symmetrically extended with respect to one or both the MPC 1714 and the first electrode line 1706a and the electrode fingers 1710.

[0166] In some embodiments, when a suitable potential difference is provided (e.g., by a voltage source) between the first and second electrodes of the MPD 1700 (e.g., the electrode fingers 1710 and the conductive region 1717), the plasma 410 may be formed in the MPC 1714 and a discharge current may flow between the electrode fingers 1710 and the conductive region 1717 via a current path established through the plasma 410 and the substrate 1702. In some implementations, the discharge current may comprise a plasma current within MPC 1714 and a current 1712 flowing between MPC 1714 and the conductive region 1717. In someimplementations, the conductive vias 1707 may be directly in contact with the substrate 1702 and may serve as electrode fingers of the second electrodes. In some such implementations, he MPD 1700 may not include the conductive region 1717 and the first and second electrodes may comprise electrode fingers 1710 and 1707, separated by the lateral gap 1705 and electrically connected to the first and second electrode lines 1706a, 1706b, respectively.

[0167] In various implementations, an amplitude of a potential difference between first and second electrodes of the MPD 1700 (e.g., a voltage applied across MPC 1714) can be modulated at a specified frequency (e.g., within a radio frequency (RF) range) to generate the plasma 410, and / or sustain the plasma 410 during the operation the MPD 1700. In some examples, a potential difference between first and second electrodes may comprise a constant (DC) component and an alternating (AC) component where the DC and AC components are configured to generate and / or sustain the plasma 410.

[0168] FIG. 17B illustrates a top view (top panel) and a cross-sectional view (bottom panel) of another example integrated MPD 1701 comprising a MPC 1715 (e.g., sealed gas-filed recessed cavity) configured to allow formation of the plasma 410 within a substrate 172, according to some embodiments. In some cases, the MPD 1701 and the MPC 1715 may comprise one or more features described above with respect to MPD 1700 and the MPC 1714. In some embodiments, MPC 1715 may additionally comprise one or more current control barriers 1716 (e.g., two current control barriers 1716-1, 1716-2), formed in the substrate 1702 and configured to control and / or redirect electric current flow from MPC 1715 to the second electrode (e.g., the conductive region 1717 or conductive vias 1707), e.g., by electrically isolating a portion the MPC 1715 from the substrate 1702. In some implementations, the current control barriers 1716 may comprise a dielectric material (e.g., silicon dioxide, silicon nitride, or the like). In some implementations, each current control barrier may comprise a polysilicon core covered by a silicon dioxide layer that isolates the polysilicon core from the substrate 1702 (e.g., the silicon substrate). In some implementations, the current control barriers 1716-1, 1716-2, may comprise dielectric regions (e.g., oxide trenches) vertically extended to the substrate 102 from a bottom surface of the capping layer 1704 to form one or more side walls of the MPC 1715. In some embodiments, when a suitable potential difference is provided between the first and second electrodes of the MPD 1701, the plasma 410 may be formed in MPC 1715 and a discharge current may flow between the first and second electrodes, e.g., between the electrode fingers 1710 and the conductive region1717 (or conductive vias / electrode fingers 1707), via a current path established through the plasma 410 and a region of the substrate 1702 (. In some implementations, the discharge current may comprise currents 1713 flowing between a bottom surface of MPC 1715 and the second electrode 1717 through regions of the substrate 1702 under the current control barrier control barriers 1716- 1, 1716-2.

[0169] In some implementations, the current control barriers (or trenches) 1716-1, 1716-2, can be formed in the substrate 1702 prior to forming (e.g., etching) the MPC 1715. In some embodiments, in addition to controlling current flow in the substrate 1702 the current control barriers 1716 may enable or facilitate etching the chamber 1714 along the vertical direction (perpendicular to the main surface of the substrate 1702) during a fabrication process and enable formation of the MPC 1715 having a desired geometry (e.g., a cubical geometry as shown in FIG. 17B). As such, in some cases, the current control barriers 1716-1, 1716-b may allow formation of devices with more compact geometries and improved current control. In some examples, a current control barrier (or trench) may be fabricated by forming a trench in the substrate 1702, covering the side walls and the bottom of the trench by a dielectric layer (e.g., by silicon dioxide that can be thermally grown on the internal surfaces of the trench) filling the trench (e.g., the volume surrounded by the dielectric layer) with poly silicon. In some examples, the current barriers 1716- 1, 1716-b, may comprise a cubical shell surrounding the MPC 1715 (as shown in FIG. 17B).

[0170] FIG. 18 schematically illustrates two cross-sectional views in two planes perpendicular to each other and to a horizontal major surface of a substrate (top panels), and a top view (bottom panel), of another example of MPD comprising vertically separated electrodes and a recessed MPC 1714 formed in the substrate 1702. In some embodiments, the MPD shown in FIG. 18 may comprise one or more features described above with respect to MPD 1700. In some embodiments, the MPD shown in FIG. 18 may comprise a top electrode at least partially formed in the capping layer 1704 above the MPC 1714 and a bottom electrode formed in the substrate 1702 below the MPC 1714 and the top electrode. In some cases, the top electrode may comprise one or more electrode fingers 1710 electrically connected to and vertically extended from a first electrode line 1706a to the MPC 1714. In some cases, at least one electrode finger can be in contact with the gas molecules in the MPC 1714. In some cases, the bottom electrode may comprise a lateral conductive region 1810 formed in the substrate 1702 below the MPC 1714. In some such cases, the bottom electrode may comprise a top surface portion of the lateral conductive region1810. In some examples, the lateral conductive region 1810 may comprise a highly doped region of the substrate 1702 horizontally extended substantially parallel to a major horizontal surface of the substrate 1702. In some cases, the lateral conductive region 1810 may be electrically connected to a second electrode line formed in on or over the capping layer 1704 and electrically isolated from the first electrode line 1706a. In some cases, the electric connection between the lateral conductive region 1810 and the second electrode may comprise one or more vertical conductive regions 1808 formed in the in the substrate 1702. In some examples, the vertical conductive regions 1808 may comprise highly doped regions of the substrate 1702 vertically extended substantially normal a major horizontal surface of the substrate 1702, between the lateral conductive region 1810 and the capping structure or layer 1704. In some examples, a plurality of vertical conductive vias 1814-1, 1814-2, formed in the capping layer 1704 may electrically connect the vertical conductive regions 1808 to different portions of the second electrode line. In the example shown two laterally separated portions of the vertical conductive regions 1808 are electrically connected to first and second portions 1706b-l and 1706b-2 of the second electrode line.

[0171] In some examples, a depth (d) of the MPC 1714 may comprise a vertical distance between bottom surface of the capping payer 1704 and a bottom surface of the MPC 1714 or a top surface of the lateral conductive region 1810. In some examples, d can be from 1.0 to 22.0 microns.

[0172] In some embodiments, a doping of the lateral conductive region 1810 may be graded, e.g., in a vertical direction (e.g., along z-axis). In some such embodiments a peak dopant concentration of the lateral conductive region 1810 may be positioned at or below the top surface of the lateral conductive region 1810. In some cases, a vertical distance (Zl) between the peak dopant concentration of the lateral conductive region 1810 and a surface of the lateral conductive region 1810 or a bottom surface of the MPC 1714 can be from 0.0 to 1.0 microns.

[0173] In some embodiments, as described above with respect to the MPD 1700, the capping layer 1704 may comprise one or more openings or through-holes 1718 formed above the etched chamber cavity configured to allow etching the chamber cavity and filling the chamber cavity with gas mixture. In some cases, the through-holes 1718 may comprise an elongate shape having a length along y-axis and a width along x-axis (perpendicular to y-axis), where x-axis and y-axis are lateral axes parallel to a major horizontal surface of the substrate 1702. In some cases, the plurality of electrode fingers 1710 may comprise two or more electrode finger groups wherean individual electrode finger group comprises an array of electrode fingers extended along y-axis and two adjacent electrode finger groups are laterally separated along the x-axis by at least one of the through-holes. In some implementations, the capping layer 1704 may comprise through-holes having shapes different from the through-holes 1718, in these implementations a geometrical characteristic (e.g., diameter of a circular through-hole) may be configured to allow sufficient molecule transport between the MPC 1714 and an atmosphere above the capping layer 1704 for substantially equalizing the pressure and composition of gas mixture in the MPC 1714 with those of the surrounding atmosphere.

[0174] In the example shown, the capping layer 1704 comprises four rectangular through-holes 1718 extended along y-axis and the top electrode of the MPD comprises three rows of electrode fingers 1710-1, 1710-2, 1710-3 extended along y-axis and separated along x-axis by two through-holes of the four through holes 1718. The three electrode fingers 1710-1, 1710-2, 1710-3 are vertically extended (along z-axis), from three sections 1706a-l, 1706a-2, 1706a-3 of the first electrode line 1706a to a top surface of the MPC 1714.

[0175] FIG.19A-19C schematically illustrate cross-sectional views of intermediate structures that may be formed during fabrication of the MPD shown in FIG. 18, in z-x plane perpendicular to a horizontal major surface of the substrate 1702 and the electrode fingers 1710-1, 1710-2, 1710-3. In some embodiments, the fabrication process of MPD may comprise: forming a dielectric layer on the substrate 1702, patterning the dielectric layer to form the through-holes 1718 and additionally finger through-holes for forming the electrode fingers 1710, filling the finger through holes with a conductive material (e.g., a metal) to form the electrode fingers 1710-1, 1710-2, 1710-3, and forming and patterning a conductive layer on the capping layer 1704 to form the three sections 1706a-l, 1706a-2, 1706a-3 of the first electrode line 1706. FIG. 19A illustrates a cross-sectional view of a first intermediate structure prior to formation of the MPC 1714. Next, the substrate 1702 may be etched etching (e.g., dry etching using xenon difluoride), via the through holes 1718, to form the MPC 1714 (as shown in FIG. 19B). In some cases, to fill the MPC 1714 with a gas mixture having desired composition and pressure, the intermediate MPD structure shown in FIG. 19B may be placed in an atmosphere (e.g., inside a vacuum chamber) comprising the gas mixture having desired composition and pressure so that the gas molecules from the atmosphere fill out the MPC 1714 via the through-holes 1718. When an equilibrium is reached, e.g., when the composition and pressure of the MPC 1714 is substantially equal to the surroundingatmosphere, a cladding layer 1806 (e.g., an insulating or dielectric layer such as silicon nitride) may be formed on the capping layer 1704 and, in some cases, on the top electrode line sections 1706a-l, 1706a-2, 1706a-3, to block the through-holes 1718 and thereby seal the MPC 1714. In some embodiments, the width and length of the through-holes 1718 may be configured (can be large enough) to allow sufficient molecule transport between the MPC 1714 and an atmosphere above the capping layer 1704 for substantially equalizing the pressure and composition of gas mixture in the MPC 1714 with those of the surrounding atmosphere. In some examples, a width (xl) of an individual section of the top electrode line, along x-axis, can be from 1.0 to 30.0 microns. In some examples, a width (x2 of an individual through-hole, along x-axis, can be from 0.7 to 50 microns.

[0176] FIG. 20 schematically illustrates two cross-sectional views in two planes perpendicular to each other and to a horizontal major surface of a substrate (top panels), and a top view (bottom panel), of another example of MPD comprising vertically separated electrodes and a recessed MPC 1714. In some embodiments, the MPD shown in FIG. 20 may comprise one or more features described above with respect to MPD 1700 and MPD 1701. In some embodiments, the MPD shown in FIG. 20 may additionally comprise a current control barrier formed in the substrate 1702. In some examples, at least a portion of the internal surface of the MPC 1714 may compromise a surface of the current barrier. In some cases, the current barrier may be formed below a region of the capping layer 1704 between the two electrode lines an the two electrodes that generate plasma in the MPC 1714. In the example shown in FIG. 20, the MPD may comprise two current control barriers 1716-1, 1716-2; a first current barrier 1716-1 comprises a first elongate insulating region longitudinally extended along x-axis at a first position along y-axis and a second current barrier 1716-2 comprises a second elongate insulating region longitudinally extended along x-axis at a second position along y-axis, such that a width of the MPC 1714 is substantially equal a lateral distance along y-axis between the first and second current barriers 1716-1, 1716-2. In some examples, the first and second positions along y-axis may be selected such the first and second current barriers 1716-1, 1716-2, are positioned below first and second regions of the capping layer 1704 that electrically isolate the first electrode line from the first and second sections 1706b-l, 1706b-2 of the second electrode line, respectively.

[0177] FIG. 21 schematically illustrates a cross-sectional view (top panel), in a plane perpendicular to a horizontal major surface of the substrate 1702, and a top view (bottom panel)of another example of MPD comprising laterally separated electrodes and a recessed MPC 1714 formed in the substrate 1702 that comprises vertically and horizontally extended insulating regions formed in the substrate 1702. In some embodiments, the MPD shown in FIG. 21 may comprise one or more features described above with respect to the MPDs shown in FIGS. 18 and 20. In some embodiments, both electrodes of the MPD shown in FIG. 21 may be formed above the MPC 1714 and a bottom surface of the MPC 1714 may comprise a horizontally extended insulating layer 2104 (e.g., a dielectric layer such as a buried oxide layer), formed in the substrate below the electrodes and the chamber cavity. In some examples, first and second electrodes of the MPD may comprise first and second pluralities of electrode fingers 1710a, 1710b, formed in the capping layer 1704 and separated by a lateral inter-electrode gap substantially extended along y-axis. The first and second pluralities of electrode fingers 1710a, 1710b, may be electrically connected and fed by first and second electrode lines 1706a, 1706b, formed on the capping structure 1704. In some examples, at least a portion of an electrode line may be formed in the capping layer 1704 or the electrode line can be embedded in the capping layer 1704 (as shown in FIGS .17A and 17B). In some examples, the first and second pluralities of electrode fingers 1710a, 1710b, may be vertically extended from the first and second electrode lines 1706a, 1706b, respectively, to the MPC 1714. In some cases, at least one of the electrode fingers may be separated from the MPC 1714 by a portion of the capping layer 1704. In some cases, the current barriers 1716-1, 1716-2, of the MPD may be vertically extended between the capping layer 1704 and the insulating layer 2104. In some such cases, the first and second current barriers 1716-1, 1716-2, may be vertically extended from the capping layer 1704 to the insulating layer 2104. In some embodiments, the first and second current barriers 1716-1, 1716-2, may be formed below the first and second electrode lines 1706a, 1706b, respectively. In some embodiments, the first and second pluralities of electrode fingers 1710a, 1710b, may each comprise an array (e.g., a one dimensional or two-dimensional array) of electrode fingers laterally separated by a region of the capping layer 1704 comprising the through- holes 1718.

[0178] FIGS. 22A schematically illustrates a cross-sectional view (top panel), in a plane perpendicular to a horizontal major surface of the substrate 1702, and a top view (bottom panel), of another example of MPD comprising laterally separated main electrodes, and a recessed MPC 1714 formed in the substrate 1702 that comprises vertically and horizontally extended insulating regions. In some embodiments, the MPD shown in FIG. 22A may comprise one or morefeatures described above with respect to the MPD shown in FIG 21. In some embodiments, the MPD shown in FIG. 22A may additionally comprise a third electrode formed in the capping layer 1704 above the MPC 1714 and between the first and second electrodes and the first and second electrode lines 1706a, 1706b. In some embodiments, the third electrode may comprise a third plurality of electrode finger 2201 formed between the first and second pluralities of electrode fingers 1710a, 1710b. In some embodiments, the third electrode can be an auxiliary electrode configured to control ignition of plasma in the MPC 1714 or a characteristic (e.g., a charge density) of a plasma formed in the MPC 1714. In some cases, a lateral position of the third electrode (e.g., the third plurality of electrode fingers 2201), thereby its lateral separation from the first and second electrodes, along the y-axis may be configured to form a first inter-electrode gap, herein referred to as ignition gap, and a second inter-electrode gap, herein referred to as plasma discharge gap, where the plasma discharge gap is larger than the ignition gap. In some embodiments, the ignition gap may be configured to provide thermionic emission (e.g., emission of an ionizing emission such as ultraviolet radiation) to ignite the plasma 410, and the plasma discharge gap may be configured to sustain the plasma 410 and establish an electric path (e.g., a high current electric path) through the plasma. In some embodiments, when a MPD having an auxiliary electrode is configured to serve as a surge protection device between two voltage nodes and is exposed to an EOS event, a first voltage drop across the ignition gap may generate thermionic radiation to ignite plasma in the MPC and a second voltage drop across the plasma discharge gap may sustain the plasma and establish a low-resistance electric path through the plasma, e.g., to prevent damage to a device protected connected between the two voltage nodes. In some embodiments, the first electrode line 1706a can be electrically connected to the third electrode line 2202 and a first voltage node and the second electrode line 1706b may be electrically connected to a second voltage node of the two voltage nodes.

[0179] FIGS. 22B schematically illustrates a circuit formed by the electrodes of MPD shown in FIG. 22A depicting the variation of the breakdown voltage (BV) as a function of the plasma discharge gap (LI) and the ignition gap (L2), where the plasma discharge gap comprises a lateral separation (along y-axis) between the first electrode (the first plurality of electrode fingers 1710a) and the third electrode (third plurality of electrode fingers 2201) and the ignition gap comprises a lateral separation (along y-axis) between the second electrode (the second plurality of electrode fingers 1710b) and the third electrode. Similar to electrode arrangement shown in FIG.3, the third electrode 2201 may be electrically connected to the first electrode line 1706a and configured to serve as an ignition electrode to facilitate ignition of plasma (e.g., by thermionic emission) in the MPC 1714 when a voltage difference (V) between the first and second electrode 1710a, 1710b, exceeds a threshold voltage (e.g., damage voltage for device protected by the MPD).

[0180] To serve as an ignition electrode, the plasma discharge gap (LI) can be larger than a plasma discharge distance gap, do, for the MPC 1714 and the ignition gap (L2) can be smaller than do. The inset in FIG. 22B schematically illustrates breakdown voltage (BV) of the MPD indicating that for a given MPC 1714 and gas mixture and pressure within the MPC 1714, the BV may decrease within a thermionic emission distance range and increase within a plasma discharge distance range where the plasma discharge gap can be an upper bound of the thermionic emission distance range and a lower bound of the plasma discharge distance at which the breakdown voltage is minimized. As such, LI can be within the plasma discharge range and L2 can be within the thermionic emission range, for a given MPC and a range of voltage applied between the first and second electrode lines, 1706a, 1706b.

[0181] In these embodiments, the third electrode 2201 may comprise a control electrode that is electrically isolated from the first and second electrodes 1710a, 1710b, and connected to a control voltage source configured to control the plasma 410 formed in MPC 1714 (by a voltage provided to the first and second electrodes 1710a, 1710b), by providing a control voltage to the control electrode 2201. In some such embodiments, the third electrode 2201 of the MPD shown in FIG. 22 A may be in contact with the gas molecules in the MPC 1714 and can be used to control the plasma 410 formed in the MPC 1714 by receiving electric charge from and / or providing electric charge to the plasma (junction effect). In some other embodiments, the third electrode 2201 of the MPD shown in FIG. 22A may be isolated from the gas molecules in the MPC 1714 (e.g., by a portion of the capping layer 1704) and can be used to control the plasma 410 formed in the MPC 1714 by applying an electric field to the plasma 410 (field effect). As such, in some embodiments, the MPD shown in FIG. 22A may be configured to function as a plasma-based junction or field effect switch and / or transistor.

[0182] FIGS. 22C schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate (top panel), and a top view (bottom panel), of another example MPD comprising laterally separated first and second electrodes and a gate electrode 2205 embedded in the capping layer 1704 and positioned between the first andsecond electrodes comprising the first and second of electrode fingers 1710a, 1710b, respectively. In some embodiments, the MPD shown in FIG. 22C may comprise one or more features described above with respect to FIG. 22A. In some cases, the gate electrode 2205 may comprise one or more features described above with respect to the auxiliary electrode 2201.

[0183] FIGS. 23 A schematically illustrates a cross-sectional view (in a plane perpendicular to a horizontal major surface of the substrate 1702), top panel, and a top view, bottom panel, of another example of MPD comprising two laterally separated electrodes 2302, 2303, a recessed MPC 1714 formed in the substrate 1702 and comprising vertical current barriers 1716-1, 1716-2, and a laterally extended conductive region 1810. In some embodiments, the MPD shown in FIG. 23A may comprise one or more features described above with respect to the MPDs shown in FIGS 20 and 21. In some embodiments, the first and second electrodes 2302, 2303, may be electrically connected to a first voltage node and the conductive region 1810 may be connected to second voltage node to generate and sustain the plasma 410. In some embodiments, the first and second electrodes 2302, 2303, may generate and sustain the plasma 410 in the MPC 1714 and the conductive region 1810 may be configured to control the plasma 410 (e.g., via a field effect or a junction effect). In some embodiments, the one of the first or second electrodes 2302, 2303, and the conductive region 1810 may generate and sustain the plasma 410 and the other one of the first or second electrodes 2302, 2303, may be configured to control the plasma 410 (e.g., via a field effect or a junction effect). In some cases, an electrode or conductive region that controls the plasma 410 can be in contact with gas molecules in the MPC 1714 and exchange electric charge with the plasma or can be isolated from the gas molecules in the MPC 1714 and interact with the plasma via an electric field.

[0184] FIGS. 23B schematically illustrates a cross-sectional view (in a plane perpendicular to a horizontal major surface of the substrate 1702), top panel, and a top view, bottom panel, of another example of MPD comprising two laterally separated electrodes 2302, 2303, a recessed MPC 1714 formed in the substrate 1702 and comprising vertical current barriers 1716-1, 1716-2, and a laterally extended conductive region 1810. In some embodiments, the MPD shown in FIG. 23A may comprise one or more features described above with respect to the MPDs shown in FIGS 20, 21, 23 A. In some cases, compared to the MPD shown in FIG. 23 A, the MPD shown in FIG. 23B may additionally comprise a gate electrode 2305 embedded in the capping layer 1704 between the first and second electrodes 2302, 2303. In some cases, the gate electrode2305 may comprise a conductive region (e.g., a highly doped polysilicon region) formed in the capping layer 1704. In some cases, the gate electrode 2305 may be isolated from the MPC 1714 by a region of the capping layer 1704 and may be configured to control the plasma 410 by generating an electric field in the MPC 1714.

[0185] FIG. 24A schematically illustrates a circuit for generating and sustaining a plasma 410 in the MPD devices described above. In some embodiments, the first and second electrodes a MPD, can be electrically connected to a microplasma driver 2408 configured to generate and sustain a plasma 410 in the corresponding MPC. In some embodiments, the microplasma driver 2408 may comprise a voltage supply and controller configured to control a voltage and / or current provided to first and second electrodes 2406-1, 2406-2. In some implementations, the voltage source may comprise one or both of a DC source and an AC source (e.g., an RF source). In some examples, the voltage supply may comprise an RF source configured to provide an alternating potential difference between the first and the second electrodes 2406-1, 2406-2, having an amplitude and a frequency determined based at least in part on the size of the gap size (between the first and second electrodes 2406-1, 2406-2), composition of gas in the MPC, and a size of the MPC among other parameters. In various implementations, an amplitude of RF voltage can be from 50 to 200 volts, from 200 to 500 volts, from 500 to Ikilovolts or any ranges formed by these values or larger or smaller values. In various implementations, the frequency of RF voltage can be from 1 to 20 MHz, from 20 to 100 MHz, from 100 to 1 GHz or any ranges formed by these values or larger or smaller values.

[0186] In some implementations, the microplasma driver 2408 can include a voltage sensor and / or a current sensor configured to measure a voltage drop and / or a current flow between the first and second electrodes 2406-1, 2406-2. In some cases, the controller may be configured to control the voltage and limit the current provided to first and second electrodes 2406-1, 2406-2, based at least in part on a measured value of voltage drop and / or current flow between the first and second electrodes 2406-1, 2406-2. In some embodiments, the microplasma driver 2408 may be configured to ramp the a plasma ignition voltage under transient or DC conditions with minimum leakage current, supply the current to the microplasma after ignition (establishing conduction through microplasma), maintain the current and voltage needed to hold the gas in plasma state, control the current to prevent runaway, monitor currents and voltages provided to the plasma chamber (e.g., via the first and second electrodes 2406-1, 2406-2) at various operation stages ofthe MPD, vary the electric power provided to the microplasma to control the carrier density within the microplasma, among other functions.

[0187] In some embodiments, two terminals 2401, 2402 (e.g., two voltage nodes), may be electrically connected to the first and second electrodes 2406-1 , 2406-2, respectively, to provide electrical access to the plasma 410 generated and sustained in MPC 1714 by the microplasma driver 2408. In some embodiments, the MPD may comprise a third electrode 2404 and a third terminal 2405 electrically connected to the third electrode 2404. In some implementations, the third electrode 2404 can be electrically connected to the plasma 410. In some implementations, the third electrode 2404 may comprise one or more features described above with respect to the electrodes of the MPDs described above. In some embodiments, the first and second electrodes 2406-1, 2406-2 may be used to generate and sustain the plasma 410, and the second and third terminals may provide electrical access to the plasma 410 (via the third and second electrodes 2404 2406-2).

[0188] In some embodiments, the MPD in the configuration shown in FIG. 24 A may serve as an electrical overstress (EOS) protection device configured to protect an electronic circuit electrically connected to the MPD device via the third terminal 2405 and the third electrode 2404. In these embodiments, an external EOS or surge event may initiate a plasma (a transient plasma) in the MPD such that a corresponding EOS current passes through the plasma and is safely directed to ground by the second electrode 2406-2 via the terminal 2402 (e.g., terminal 2402 can be connected to the ground potential) until the EOS event ends and the microplasma quenches.

[0189] FIG. 24B schematically illustrates discharge current (Ip) plotted against voltage (Va) applied between the first and second electrodes 2406- 1 , 2406-2 of the MPD shown in FIG. 24A. In some cases, the current-voltage (IV) curve 2410 may comprise a snap back region 2414 indicating a bistable behavior of the discharge current (Ip) with respect to the applied voltage (Va). In some embodiments, increasing the voltage above a threshold value (Vth) 2412 can form and sustained the plasma 410 inside the MPC 1714 and decrease the resistance of the current path through the plasma 410 resulting in increased current flow. As such, in various implementations, the plasma 410 (e.g., in a sustained state) may be configured to support flow of a large electric current in portion of a circuit (e.g., electric over stress protection circuit). For example, when the voltage applied between the first and second electrodes 2406-1, 2406-2, is larger than Vth 2412, the current (Ip) passing between the first and second electrodes 2406-1, 2406-2, through the MPC1714 can be larger than 1 nano- Amp, larger than 1 micro-Amp, larger than 1 Amp, or larger values. In some cases, when the voltage applied between the first and second electrodes 2406-1, 2406-2, is larger than Vth 2412, a resistance between the first and second electrodes 2406-1, 2406-2 (Ron) can be smaller than IM ohms, smaller than Ik ohms, or smaller than 1 ohms.

[0190] In some examples, the current handling capability and highly nonlinear currentvoltage behavior of the plasma 410 (e.g., a sustained microplasma when Va> Vth) and thereby the integrated microplasma device MPD may allow usage of the MPD as a bistable electronic switch, an electronic oscillator, an electric over stress (EOS) protection and / or monitoring device among other applications. For example, the electrodes of the MPD, can be electrically connected to two voltage nodes in an electronic circuit and can be configured to protect the circuit when an EOS event (e.g., an unexpected high voltage between the two voltage nodes) occurs, by providing a low resistance and high current capacity electrical path between the two electrodes via the plasma.

[0191] In some embodiments, the snapback behavior and high current capacity of the MPD may be exploited to provide protection against an EOS event. For example, the integrated MPD 1701 may serve as a high-power EOS snapback cell with low Ron.

[0192] In some embodiments, a two-terminal electronic device 2409 may comprise the MPD shown in FIG. 24A, the microplasma driver 2408, which generates and sustains the MPD device via the first and second electrodes 2406-1, 2406-2, and two terminals that provide external access to the resulting plasma 410. As such the plasma 410 can be internally driven and externally used. In some examples, when an external voltage is applied to the terminals of device 2409, the resulting current-voltage dependence may comprise one or more features described above with respect to the I-V curve 2410. In some implementations, the two terminals may comprise the first and second terminals 2401, 2402. In some implementations, the two terminals may comprise the second and third terminals 2402, 2405. In some embodiments, a two-terminal electronic device may comprise the MPD and the first and second terminals 2401, 2402, without the microplasma driver 2408. In some such embodiments, an applied external voltage to the terminals 2401, 2402 electronic device 2409 may generate and sustain plasma 410, and the resulting current-voltage dependence may comprise one or more features described above with respect to the I-V curve 2410. As such, in some embodiments, the plasma 410 may be externally driven and externally used.

[0193] In some embodiments, the carrier concentration in the chamber 1714 can be changed by one or more orders of magnitude by changing a driving voltage and / or current (voltage and / or current provided to the first and second electrodes 2406-1, 2406-2). Given the dependence of the chamber 1714 resistance between the first and second electrodes 2406-1, 2406-2, on the carrier concentration in the chamber may be changed by changing a voltage difference between these electrodes.

[0194] In some embodiments, the MPD or the two-terminal device 2409 may be configured to function as an electronic oscillator (high frequency electronic oscillator). In some implementations, an electronic oscillator (e.g., a high frequency electronic oscillator) may comprise the MPD or the device 2409. In some embodiments, the MPD or the two-terminal device 2409 may be configured to convert a DC current or voltage provide by a power supply (e.g., the microplasma driver 2408) to an alternating current (AC). Ins some implementations, the resulting oscillatory signal may be coupled to an external circuit directly through the first, second, or the third electrodes 2406-1, 2406-2, 2404 t or by an antenna (e.g., an independent antenna that can be isolated from the microplasma device / oscillator).

[0195] In some examples, the integrated microplasma devicel701 or device 2409 may be electrically connected to one or more components that together with the integrated microplasma devicel701 or device 2409, form the electronic oscillator. In some embodiments, the electronic oscillator comprising the MPD or the two-terminal device 2409 can be configured as a current / voltage-controlled oscillator. For example, the oscillation frequency of such an oscillator may be dependent on the carrier concentration within the plasma 410 and a voltage and / or current provided to the first and second electrodes 2406-1, 2406-2 (e.g., by the current driver 2408) may be used to control the oscillation frequency by controlling the carrier concentration within the plasma 410. In some cases, when a length of chamber 1714 extending below the gap 1405 between the first and second electrodes is less than the Debye length of the plasma, plasma oscillations can be externally coupled.

[0196] In various embodiments, charge carrier or ion concentration in a plasma (e.g., plasma 410) formed in a MPC of the MPDs may be modulated using a microplasma driver (e.g., the microplasma driver 2408 or another circuit connected to the MPD, to control an optical property of plasma and thereby interaction of an optical wave or beam with the plasma. In various implementations, interaction of the optical wave or beam with the plasma may comprisetransmission of the optical wave or beam through the plasma, reflection of the optical wave or beam by the plasma, a change of the phase of group of the optical wave or beam by the plasma, or other type of interactions. For example, a MPD may be configured as an optical modulator (e.g., electro-optical modulator) that can modulate optical phase and / or optical amplitude of the light propagating at least partially through the plasma formed in MPC, by varying a voltage applied on the plasma (e.g., provided between two electrodes of the corresponding MPD).

[0197] As shown in FIG. 24B the I-V curve 2410 of a MPD (e.g., the MPD shown in FIG. 24A) may comprise a nonlinear behavior indicative of a voltage and / or current dependent electric resistance provided by the plasma 410 that may be used as a switch or transistor. In some embodiments, for a given voltage (e.g., a voltage larger than Vth) applied between the two electrodes of a MPD the current flow between the two electrodes via the plasma may be controlled by a voltage applied on a control electrode to exploit a region of the I-V curve 2410 for amplification, switching, or another functionality. For example, a control electrode may be formed control between the two electrodes to control electric resistance of the plasma in a corresponding MPC. For example, the two electrodes may comprise first and second electrodes 2406-1, 2406-2 (or third and second electrodes 2404, 2406) of the MPD shown in FIG. 24A, or first and second electrodes 2302, 2303, of the MPD shown in FIG. 23B. In some cases, the control electrode may be electrically isolated from the MPC to prevent electric current flow between the control electrode and the plasma while allowing an electric field generated by the control electrode to interact with the plasma.Plasma Control and Monitoring in Microplasma Devices

[0198] In some embodiments, a characteristic of plasma formed in any of the MPDs described above may be controlled to adjust a parameter of the MPD serving as a switch or circuit breaker in a system. In some embodiments, the characteristics of the plasma may be controlled by In some embodiments, a characteristic of plasma formed in any of the MPDs described above may be controlled by manipulating the plasma formed in the corresponding MPC using an external field configured to interact with the plasma, changing a temperature or pressure of gas inside the MPC (e.g., by changing a boundary of the MPC). In some embodiments, the external field may comprise an electric field or magnetic applied on the plasma or an electromagnetic field (e.g., light wave or radio frequency wave) transmitted from an external source to the plasma directly or by an antenna.

[0199] In some embodiments, the performance and status of a MPD may be monitored by detecting and measuring an electric or magnetic field generated or an electromagnetic field emitted by the plasma formed in the corresponding MPC using a sensor. In some embodiments, the sensor may comprise an optical detector or a radio frequency (RF) antenna integrated with the MPD to detect light or RF waves emitted by the plasma. In some embodiments, a sensor signal generated by the sensor may be wirelessly transmitted to an electronic processing and control system or module configured to analyze the sensor signal to extract value of a parameter of the plasma and thereby performance and / or status of the corresponding MPD. In some embodiments the electronic processing and control system may generate a control signal and transmit the control signal to the MPD to control the MPD based at least in part on the extracted value of the plasma parameter (e.g., by controlling pressure of MPC or a parameter or the plasma using an external field as described above).

[0200] FIG. 25 schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate 1702, of a MPD comprising a recessed MPC 1714 formed below the capping layer 1704 in the substrate 1702 and configured to support formation of plasma 410. In some embodiments, a portion of the capping layer 1704 above the MPC 1714 may comprise a conductive region or element 2508. In examples, the conductive region or element 2508 may comprise a first radio frequency (RF) antenna. In some embodiments, a second RF antenna 2502 may be formed on, above, or at least partially in that capping structure. In some such embodiments, the second RF antenna 2502 may receive RF waves from an RF source 2506, generate an RF signal based on the received RF waves, transmit the RF signal to an amplifier 2504 that amplifies the RF signal and provides the amplified RF signal to the first RF antenna 2508. In some such embodiments, the first RF antenna 2508 may generate an electromagnetic field or a secondary RF wave in the MPC 1714. In some cases, the electromagnetic field or a secondary RF wave may interact with the plasma 410 and thereby allows controlling a parameter or property of the plasma 410 using the RF source 2506. In some embodiments, a control circuit 2510 may be used to control the amplifier 2504 and thereby the amplitude or power of the electromagnetic field or a secondary RF wave that interacts with, and thereby controls, the plasma 410. In some embodiments, the configuration shown in FIG. 25 may comprise a remotely controlled MPD configured to allow controlling certain parameters of the MPD using a wireless signal. In some examples, where the remotely controlled MPD is configured as a surge protector, a thresholdvoltage for triggering the MPD (e.g., igniting the plasma 410) may be remotely controlled using the RF source and additionally parameters of the control circuit 2510.

[0201] FIG. 26 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of three MPDs configured to support formation of plasma and allow control and manipulation of the plasma using light waves. In some embodiments, a MPD 2601 may be configured such that its MPC 1714 receives a light beam (e.g., a laser beam 2605) from a light source (e.g., a laser 2604) via the capping layer 1704. In some cases, the capping layer 1704 can be transparent within a wavelength range including an absorption wavelength of a gas molecule in the MPC 1714 and wavelength of the laser beam 2605 can be substantially equal to the absorption wavelength of the molecule. In some examples, the capping layer 1704 may comprise an optical absorption layer 2606 formed above the MPC 1715 and configured to absorb light having wavelength in an absorption range comprising the wavelength of the laser beam 2605. In some such examples, the optical absorption layer 2606 may comprise a through-hole, opening, or a window, that allows transmission of the laser beam 2605 to the MPC 1714. In some embodiments, the laser beam 2605 may interact with the plasma 410 formed in the MPC 1714 and change a parameter or property (e.g., temperature, charge density, or the like) of the plasma.

[0202] In some embodiments, a MPD 2602 may be configured such that its MPC 1714 receives the laser beam 2605 from the laser 2604 via an adjustable optical filter 2611 formed on the capping layer 1704. In some cases, a transparency bandwidth / wavelength, transmission bandwidth / wavelength, optical absorption within a passband, and / or another parameter of the adjustable optical filter 2611 may be adjusted by providing a control signal to the adjustable optical filter 2611. In some cases, the control signal may be generated and provided by an optical filter control circuit 2608. In some cases, the control signal may be provided to an electro-optic control electrode (e.g., a transparent conductive layer) formed on the optical filter 2611 and cause optical transmission of the optical filter 2611 for the laser beam 2605 to be adjusted via an electro-optic effect. Advantageously, the adjustable optical filter 12611 may allow optically controlling the plasma 410 by controlling a portion of the laser beam 2605 transmitted to the MPC 1714 and plasma 410.

[0203] In some embodiments, a MPD 2603 may comprise an optically reflective structure 2614 formed on the capping layer 1704 above the MPC 1714. In some cases, the reflective structure 2614 may be configured to receive a light beam (e.g., a laser beam) from a lightsource (e.g., a laser source 2604) and redirect at least a portion of the light beam to the MPC 1714 via the capping layer 1704. In some cases, the reflective structure 2614 may comprise one or more reflective internal surfaces configured to reflect at least a portion of the laser beam received from the laser 2604. In some examples, the reflective structure 2614 may comprise first and second reflective internal surfaces 2612-1, 2612-2, formed on two opposing internal surfaces of the reflective structure 2614 and configured to transmit a portion of laser beam incident on the second internal reflective surface 2612-2, formed on the capping structure or layer 1704, to the MPC 1714 via an opening in the second internal reflective surface 2612-2. In some cases, multiple portions of the laser beam may enter MPC 1714, at different positions as a result of multiple reflections of the laser beam between the reflective internal surfaces 2612-1, 2612-2.

[0204] In some embodiments, at least an internal surface of a MPC may comprise a movable region configured to change internal volume of the MPC upon being actuated. In various implementations, the movable region may comprise a material or geometry different from other regions of the internal surface of a MPC. In some cases, the movable region may be configured to be thermally, electrically, mechanically, or piezoelectrically actuated. However, embodiments are not so limited the movable region may be actuated based on other mechanisms.

[0205] FIG. 27 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of three MPDs configured to support formation of plasma in a recessed MPC 1714 and comprising a flexible or movable layer configured to control gas pressure in the respective MPCs. In some embodiments, the MPD 2701 may comprise a recessed MPC 2705 formed in the substrate 1702 and vertically extended between a capping layer 1704 formed on or over the substrate and a bottom section 2706 formed in the substrate 1702. In some embodiments, the bottom section 2706 may comprise a region formed in the substrate 1702 (e.g., by deposing a material in the cavity etched in the substrate to form the MPC 2705). In some cases, the bottom section 2706 may comprise a material having large expansion coefficient. In some such cases, the internal volume of the MPC 2705 may be reduced (e.g., to increase the gas pressure) by heating and thereby expanding the bottom section 2706. In some examples, the bottom section 2706 may be locally heated using a resistive heater formed inside or below the bottom section. In some other examples, the bottom section 2706 may be indirectly heated by heating the substrate 1702.

[0206] In some embodiments, MPC of a MPD may comprise a flexible membrane (e.g., a thinned region of a side wall or the capping layer or structure 1704) configured to be deformed by a negative external pressure applied on an external surface of the flexible membrane. In some embodiments, MPD 2702 may comprise a MPC 2707 having a thin side wall 2708 (e.g., a portion of the current barrier 1716-1) formed between MPC 2707 and an auxiliary cavity 2709 formed in the substrate 1702. In some cases, internal volume of the MPC 2707 and thereby the pressure inside the of the MPC 2707 may be increased or decreased by increasing or decreasing the pressure inside the auxiliary cavity 2709. In some embodiments, the capping layer 1704 of the MPDs 2703, 2704 may comprise a thin portion 2710 configured to be deformed and thereby change the pressure inside the respective MPCs when pressure above the capping structure or layer 1704, or above a portion of the capping structure or layer 1704, above the respective MPC changes. In some cases, MPD 2704 may comprise an auxiliary cavity 2711 formed by a structure 2614 fabricated on the capping layer 1704 above the MPC. Advantageously, similar to the auxiliary cavity 2709, the auxiliary cavity 2711 in the structure 2614 may allow locally changing the pressure above the thin portion 2710 and thereby provide an effective pneumatic actuation mechanism for deforming the thin portion 2710.

[0207] FIG. 28 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate, of two MPDs 2801, 2802, configured to support formation of plasma 410 and comprising a radio frequency (RF) antenna 2502 configured to receive and re-emit RF radiation emitted by the plasma 410. In some examples, the RF antenna 2502 may comprise conductive regions on one or both major surfaces of a dielectric layer 2511 formed on the capping layer 1704 or a structure fabricated in capping layer 1704. In some embodiments, the MPD 2802 may comprise a structure 2615 fabricated on the capping layer 1704 above the MPC 1714 and an antenna 2502 formed on the top surface of the structure 2615 and vertically separated from the plasma 410. In some cases, the internal side walls of the structure 2615 may be covered by RF absorbing layers configured to prevent reflection of the RF waves and thereby canceling the indirect RF paths between the antenna 2502 and the plasma 410.

[0208] FIG. 29 schematically illustrates cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD 2803 configured to support formation of plasma 410 and comprising a magnetically shielded chamber 2808 configured to block magnetic field generated by the plasma.

[0209] FIG. 30 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of a substrate 1702, of four MPDs 3001, 3002, 3003, 3004, each configured to support formation of plasma 410 and comprising a photodetector 3006 integrated with the respective MPDs and configured to detect light generated by the plasma 410. In some embodiments, the MPD 3001 may comprise a photodetector 3006 formed or otherwise embedded in the substrate near the MPC 2705 and optically connected to the MPC 2705 via an optical waveguide 3008. In some embodiments, the MPD 3002 may comprise a photodetector 3006 formed on the capping layer 1704 and configured to receive and detect light generated by the plasma 410 via the capping structure or layer 1704, which is transparent to light generated by the plasma 410. In some cases, the MPD 3002 may comprise a structure formed on the capping layer 1704 having a light absorbing chamber formed therein. In some cases, the light absorbing chamber may comprise an optical absorption layer 3010 formed on its internal surface and configured to absorb light emitted by the plasma 410. In some embodiments, the MPD 3003 may comprise a capping structure or layer 1704, which is transparent to light generated by the plasma 410 and an optical absorption layer 3010 formed on a portion of the capping layer 1704 and configured to absorb light emitted by the plasma 410. In some cases, the MPD 3002 may comprise a photodetector 3006 formed on a portion of the capping layer 1704 not covered by the optical absorption layer 3010 and configured to receive and detect light generated by the plasma 410 via the capping layer 1704. In some cases, the MPD 3004 may comprise a structure formed on the capping layer 1704 having a light absorbing chamber formed therein. In some cases, the light absorbing chamber may comprise an optical absorption layer 3010 formed on a portion of its internal surface and configured to absorb light emitted by the plasma 410. In some embodiments, the MPD 3004 may comprise a photodetector 3006 formed in a portion of the light absorbing chamber not covered by the optical absorption layer 3010 and may be configured to receive and detect light generated by the plasma 410 via the capping structure or layer 1704.

[0210] FIGS. 31A-31B schematically illustrates a cross-sectional view, in a plane perpendicular to a horizontal major surface of a substrate, of a MPD configured to support formation of plasma 410 in a MPC and comprising an antenna and a photodetector configured to detect light and RF waves generated by the plasma and radiate an RF signal indictive of the detected light and RF waves.

[0211] In some embodiments, the MPD shown in FIG. 31 A may comprise a primary antenna 2508 formed above the MPC 1714. In some examples, the primary antenna 2508 may comprise a conductive patten formed on or at least partially in the capping structure and configured to receive RF waves by the plasma 410 formed in the MPC 1714. In some cases, the primary antenna 2508 may generate an RF signal proportional to the received RF waves and transmit the RF signal to an RF amplifier 3102 configured amplify the RF signal and transmit the amplified RF signal to an RF antenna 2502 configured to emit a wireless signal indicative a frequency and amplitude of the RF waves generated by the plasma 410. In some examples, the antenna 2502 may be integrated with the MPD (e.g., formed on the capping structure 1704). In some embodiments, the MPD shown in FIG. 31 A may further comprise photodetector 3006 formed or disposed on or at least partially in the capping layer 1704 close to the MPC 1714 and configured to detect light generated by the plasma 410. In some cases, the photodetector 3006 may generate a generate a photodetection signal proportional to detected light and transmit the signal to the RF amplifier 3102 to control a parameter of the RF amplifier 3102 and thereby modulate the amplified RF signal output by the RF amplifier 3102 based on the detected light. As such, in some embodiments, the wireless signal emitted by the RF antenna 2502 may comprise information pertaining the amplitude and frequency of the RF waves and intensity / power of light generated by the plasma 410. In some embodiments, the wireless signal emitted by the RF antenna 2502 may be received by an electronic monitoring and control system configured to use the wireless signal to determine a status or parameter of the MPD and, in some case, generate a control signal to adjust a parameter of the MPD based on the information carries by the wireless signal (e.g., using one or more of methods described above with respect to FIGS. 25, 26, 27).

[0212] In some embodiments, the MPD shown in FIG. 3 IB may comprise one more features described above with respect to the MPD in FIG. 31 A, MPD 2802 in FIG. 28, and MPD 3004 in FIG. 30. In some embodiments, the MPD shown in FIG. 3 IB may comprise a dielectric layer 2511 formed on the capping structure 2614 and above the MPC 1714 and an antenna 2502 formed on or in the dielectric layer 2511. In some embodiments, the capping structure 2614 may serve as a spacer that provides a specified vertical separation between the plasma 410 and the antenna 2502. In some cases, an integrated photodetector 3006 may be formed or disposed in the structure 2614 and receive light generated by the plasma 410 via the capping layer 1704 (e.g., transparent capping layer 1704). In some embodiments the antenna 2502 may be configured toreceive RF waves generated by the plasma 410 and re-radiate the receive RF waves as a wireless signal. In some cases, a photodetection signal generated by the photodetector 3006 may be amplified by an amplifier 3102 and the amplified photodetection signal may be used to control a property of the RF antenna 2502 and thereby phase or amplitude of the wireless signal such that the wireless signal carries information pertaining to both light and RF waves generated by the plasma 410. In some examples, an internal surface of a chamber formed between the capping structure 2614 and the capping layer 1704 may be coated with an RF and / or light absorbing layer 3010 configured to absorb RF waves and / or light incident on the internal surface and block indirect RF and / or optical paths between the plasma 410 and the antenna 2502 and / or between the plasma 410 and the photodetector 3006.

[0213] FIG. 32 schematically illustrates cross-sectional views, in a plane perpendicular to a horizontal major surface of the substrate 1702, of two MPDs configured to support formation of plasma and comprising a shielding layer configured to electrically, electromagnetically, thermally, and / or optically isolate the plasma from a region above the MPD. In some embodiments, the shielding layer of the MPD 3201 may be formed on the capping layer 1704 and that of the MPD 3201 may be formed on a structure 2614 formed on the capping structure above the MPC 1714. In various implementations, the shielding layer may comprise a thermally insulating material, a magnetic shielding material, a material that strongly absorbs RF waves or light emitted by the plasma, a conductive material, or a combination thereof.

[0214] In some embodiments, a signal generated by an antenna or photodetector in communication with the plasma formed in a MPD may be received by an electronic monitoring and control system via wired or wireless link. In some such embodiments, the electronic monitoring and control system may comprise devices and circuits configured to extract information pertaining a status or a parameter of the MPD from the signal and, in some cases, generate a control signal to control or adjust the MPD based on the extracted information (e.g., using one or more of methods described above with respect to FIGS. 25, 26, 27).

[0215] FIG. 33 schematically illustrates a block diagram of an electric protection and monitoring module (or system) 3302 configured to monitor, protect and manage an electronic circuit using a circuit breaker and generate and transmit data indicative of a status or parameter of the circuit breaker device and / or the protected electronic circuit. In some cases, the module 3302 may include a first block or segment comprising circuit breaker 3304 connected to the electroniccircuit (e.g., to one or more voltage nodes connected to the electronic circuit) and a voltage sensing device 3306 that monitors a voltage at a voltage node connected to the electronic circuit. In some cases, the circuit breaker may comprise a MPD (e.g., any of the MPDs described above). In some cases, the module 3302 may include a second block or segment comprising a communication unit 3308, an electronic control unit (ECU) 3310, and a current sensing unit 3312. In some examples, the ECU may comprise a microcontroller, a central processing unit (CPU). In some cases, the first and second blocks or segments may be electrically isolated. In some cases, the first block or segment may comprise a high voltage block and the second block may comprise low voltage block. In some cases, the ECU 3310 may receive signals from the circuit breaker 3304, voltage sensing unit or module 3306, and current sensing unit 3312, analyze and / or process the received signals and transmit the signal indicative of a status or parameter of the circuit breaker device and / or the electronic circuit protected by the circuit breaker to the communication unit 3308 for transmission to another system. In some cases, the ECU 3310 may generate a control signal based at least in part on the signal received from one or more of the circuit breaker 3304, voltage sensing unit 3306, and current sensing unit 3312, and transmit the control signal to the circuit breaker 3304 to adjust a parameter of the circuit breaker 3304. Additionally, or alternatively, in some cases, the ECU 3310 may receive a control command from another system, via the communication unit 3308 and transmit generate the control signal based at least in part on the received control command. For example, the module 3302 may allow switching the circuit breaker 3304 on or off over the internet. In some cases, the module 3302 may determine the power consumption of the electronic circuit based on signals received from the voltage and current sensing units 3306, 3312, an environmental parameter (e.g., temperature of an environment surrounding the electronic circuit) and send telemetry related to power consumption and environment.

[0216] FIG. 34 schematically illustrates a block diagram of a computing system 3402 configured to receive and analyze data received from the electric protection and monitoring system shown in FIG. 33. In some cases, the ECU 3310 may comprise the computing system 3402. In some cases, the computing system 3402 may comprise computing and analytical units 3406, 3404 comprising a non-transitory memory and a hardware processor configured to execute machine readable instructions stored in the memory to analyze and processes signals received from the circuit breaker 3304, voltage sensing unit 3306, and / or current sensing unit 3312, an alerting system 3408 configured to generate an alert message in response to a determination made by thecomputing unit with regards to a parameter of the circuit breaker or the electronic circuit exceeding a specified threshold, a data base 3410 configured to store processed and measured data, an authentication unit configured to authenticate a signal received from the circuit breaker 3304, voltage sensing unit 3306, current sensing unit 3312, or the communication unit, and an internet of things (IOT) authentication configured to authenticate a communication link established (e.g., over internet) with another system (e.g., a cloud computing system).

[0217] FIG. 35-37 schematically illustrates block diagrams of three different electric protection and monitoring systems having different interconnection architectures.

[0218] FIG. 35 shows a panel 3500 comprising several modules 3502-1, 3502-2, 3502- 3, e.g., similar to module 3302, installed in at or near a single location. In some cases, individual each could have its own wired or wireless connection to the internet. In some cases, edge analytics or application of an artificial intelligence mode may be handled within the module.

[0219] FIGS. 36 shows a panel 3600, comprising a plurality of modules 3602-1, 3602- 2, 3602-3 installed in nearby locations where the modules share a single hub 3604 which connects to the internet. In some cases, these modules may be connected to each other and the hub via a separate mesh network. This architecture may reduce cost per module and may be used in applications where Wifi cannot reach all locations in an area. FIGS. 37 shows a system 3700 comprising three panels 3701, 3702, 3703, each comprising a plurality of modules. In some cases, the panels 3701, 3702, 3703, may be connected to a single hub 3604 which connects to the internet.

[0220] In some examples, the hub 3604 may comprise a more powerful processor compared to an IOT node in each module. In some cases, the hub 3604 may be programmed as part of a functionally safe system to interpret data and initiate shutdowns if needed based on data received from modules and other sources. In some cases, an Al module may be integrated with hub 3604 to enable the hub 3604 to autonomously make inferences from the data and respond to anomalies that are detected. In some examples, the hub 3604 may be configured to respond to an anomaly by turning off a switch (e.g., a circuit breaker) and / or generating and transmitting an alert signal and / or message.

[0221] FIG. 38 schematically illustrates block diagram of an example implementation of the electric protection and monitoring system shown in FIG. 33 where an EOS event may be detected and reported based on RF waves and / or light generated by plasma formed in a MPD. As described above, in some embodiments, an RF antenna (and / or a photodetector) may be integratedwith a MPD and a signal generated by the antenna (and / or the photodetector) may be transmitted as a wireless signal. In some cases, the plasma formed inside MPC of the MPD (e.g., an MPD serving as a spark gap or surge protector) can emit RF waves (radiation) in response to being generated, activated or exposed to an EOS event. In some such cases, the n RF antenna in the vicinity of plasma may generate an RF signal upon receiving the initial RF wave from the plasma or in response to charge and / or field variations produced by the plasma. As such, in some cases, RF radiation and / or field variations produced by the plasma may be used as non-contact EOS detection mechanism where the RF circuit (e.g., the RF amplifier) and antenna can be electrically isolated from the MPD. In some embodiments, a panel 3800 may comprise several modules 3802- 1, 3802-2, 3802-3, each comprising a MPD serving as circuit breaker, a RF detection unit 3804 and an ECU 3310 in communication with the RF detection unit 3804. In some such embodiments, when plasma is generated by an EOS event, or an existing plasma is exposed to an EOS event, the one of the corresponding MPD, in which the plasma is formed, may emit a wireless signal indicative of the EOS event to the RF detection unit 3804. In response to receiving the wireless signal the RF detection unit 3804 may transmit a signal to the ECU 3310 and the ECU 3310 may generate alert, or transmit a signal (e.g., via a wired or wireless link) to another system (e.g., a system local to a factory).Additional Applications

[0222] FIG. 39 illustrates a cross-sectional view of an MPD 3900 configured as an electro-optical modulator. In some embodiments, the dependence of the optical properties of the plasma 410 on the carrier or ion concentration in the plasma 410 may be used to modulate an amplitude and / or phase of an optical beam transmitted via the plasma 410. For example, the magnitude of a voltage applied on the MPD 3900 (e.g., between the first and second electrodes via the first and second electrode lines 1706a, 1706b) and / or an electric current provided to the MPD 3900 may change the carrier concentration in the plasma 410, in some cases, by one or more orders of magnitude. As a result, the integrated microplasma device 1701 can be modulated at a modulation frequency to modulate the optical properties of the microplasma 103 and thereby the amplitude and / or phase of a beam of light transmitted through the microplasma 103.

[0223] In some embodiments, the composition and geometry of the dielectric or capping layer 3901 and / or the substrate 3903 may be configured to allow transmission of anincident beam of light 3902 (or 3904) through the plasma 410. In these embodiments, applying a modulated current and / or voltage between the first and second electrode lines 1706a, 1706b, and thereby between the electrode fingers and / or conductive regions that are in contact or electric communication with the plasma 410, may result in modulation of the amplitude and / or phase of the transmitted portion 3906 (or 3908) of the incident light beam 3902 (or 3904). In various implementations, the composition of the capping structure 39601 and the substrate 3903 may be configured to allow low loss transmission light having wavelengths within the visible wavelength range (e.g., 450 nm - 750 nm), or an infrared wavelength range (e.g., near, mid, or far infrared). In some embodiments, the capping layer 3901 may include an optical coating, a lens, an optical window, an optical filter, and / or a layer configured to transmit light within a specified operational wavelength range and prevent transmission of light within certain wavelength ranges outside the operational wavelength range.

[0224] FIG. 40 schematically illustrates a cross-sectional view (in a plane perpendicular to a major surface of the substrate 1702) of an example MPD 4000 comprising a recessed MPC 1714 configured to support formation of plasma. In some embodiments, the MPD 4000 may comprise one or more features of the MPDs described above. For example, the MPC 1714 may comprise a recessed cavity formed within the substrate 1702 and a capping layer 1704 disposed over the substrate 1702 and the cavity to provide a sealed enclosed volume. In some implementations, the MPC 1714 may comprise vertical insulating trenches 4005-1, 4005-2, formed within substrate 1702, e.g., serving as side walls of the MPC 1714 and / or current control barriers In various implementations, the insulating trenches 4005-1, 4005-2, may comprise one or more features described above with respect to the current control barriers 1716-1, 1716-2. For example, the insulating trenches 4005-1, 4005-2, may be configured to spatially confine the geometry of the MPC 1714 and control electric current conduction paths in the substrate 1702. In some embodiments, the MPD 4000 may comprise first and second electrodes electrically connected to first and second electrode lines 1706a, 1706b, and in electric contact with the gas molecules in the MPC 1714. In some cases, the first and second electrodes may comprise one or more features of the electrodes of the MPDs described above (e.g., each may include one or more electrode fingers extending from the respective electrode line to the MPC 1714). In some implementations, the first and second electrodes may be configured to generate and sustain plasma and / or establish a current path 4003 through the plasma. In some embodiments, MPD 4000 mayfurther comprise a control or gate electrode 2305 embedded in the capping layer 1704 above the chamber 1714 between the first and second electrodes, and the respective electrode lines 1706a, 1706b, and configured to control a current flow between the first and second electrodes, e.g., by controlling and / or perturbing the plasma 410 (e.g. by forming an electric field in the MPC 1714). In some examples, the gate electrode 2305 may be electrically connected to a device (e.g. a gate controller 4008) that generates a voltage difference between the gate electrode 2305 and the first electrode (or the second electrode) to perturb or extinguish the plasma 410 and thereby the current path 4003.

[0225] In some examples, the control electrode 2305 may comprise a conductive layer laterally extending parallel to a major surface of substrate 1702. In some implementations, the control electrode 2305 can be electrically isolated from the first and second electrodes and electrically connected to the gate controller 4008. In various implementations, the gate controller 4008 may comprise an electronic circuit, component, and / or device (e.g., a voltage source), or a system. In some embodiments, plasma 410 may be generated and sustained by a microplasma driver 2408 electrically connected to the first and second electrode lines 1706a, 1706bm and thereby the first and second electrodes.

[0226] In some implementations, the MPD 4000 may be configured to serve as a voltage-controlled switch or amplifier where a current flow between the first and second electrodes is directly or inversely proportional to a control voltage applied on the gate electrode 2305. In some embodiments, the plasma 410 may be generated and sustained via the electrical connection and corresponding devices that use the integrated microplasma device 4000 as a voltage-controlled switch (or amplifier) in an electronic circuit. In some embodiments, the plasma 410 may be generated and sustained by the microplasma driver 2408 that can be separated from an electronic circuit that uses the integrated MPD 400 as a voltage-controlled switch (or amplifier).

[0227] In some embodiments, the MPD 400 may serve as a three- terminal switch or transistor having a first terminal electrically connected to the first electrode via electrode line 1706a, a second terminal electrically connected to the second electrode via the second electrode line 1706b, and a control terminal electrically connected to the gate electrode 2305. In some examples, an electrical connection between the first and the second terminals may be controlled by a voltage on the gate terminal. For example, when the plasma 410 is sustained, for a given voltage applied between the first and second terminal a current flow (and thereby the resistance)between the first and second terminals may decrease as an electric potential difference between the first terminal and the control terminal increases. In some examples, when the electric potential difference between the first terminal and the control terminal increases above a threshold value the plasma may be extinguished and the first terminal may be electrically disconnected from the second terminal. Similar to the two terminal device 2409 described above with respect to FIG. 24A, in some embodiments, the plasma formed in the of the three-terminal switch or transistor may be generated and sustained by driving voltage received via the first and second terminals or via one of the first or second terminals and a third terminal electrically connected to a fourth electrode dedicated to plasma generation and stabilization. The driving voltage (e.g., a constant voltage and / or and RF voltage) may be provided by a microplasma driver (e.g., a microplasma driver similar to microplasma driver 2408) or, in some cases, the electronic circuit that uses three- terminal switch (or transistor) for current control.

[0228] FIG. 41 illustrates a side cross-sectional view of an optoelectronic gas detector system 4104 comprising an integrated MPD 4102. In some embodiments the MPD 4102 may serve as a light source (e.g., IR light source) in a gas sensing system to generate light having a spectrum similar or substantially identical to the absorption spectrum of a target or specified gas molecule. In some implementations, the chamber of the integrated MPD 4102 may be filled with a gas or a gas mixture so that upon applying a voltage on the MPD 4102 (e.g., across the corresponding MPC) the resulting plasma emits light 4105 having an optical spectrum similar or substantially identical to the absorption spectrum of a specified or target gas molecule in a gas sample 4106. In some embodiments, the gas or gas mixture in MPC of the MPD 4102, which emits light 4105, may comprise the specified or target gas molecules. For example, when the target gas molecule is carbon dioxide, the MPC of the MPD 4102 may comprise carbon dioxide and, in some cases, other types of molecules. In some embodiments, in addition of the specified / target gas molecule, the gas or gas mixture in MPC of the MPD 4102 may comprise one or more other gas molecules included in the gas sample 4106. In some implementations, the gas mixture (e.g., type, pressure and / or concentration of different gas species) within the MPC may be optimized to increase emission of light by the target gas molecules. Advantageously, when the molecules that emit light 4105 and the target gas molecules in the gas sample 4106 are of the same type, the optical spectrum of light 4105 can be substantially similar to the optical absorption of the target molecules in the gas sample 4106. In some examples, at least one optical emission peak of light 4105 can be substantially equalto an optical absorption peak of the target gas (e.g., within an optical absorption bandwidth), resulting in efficient absorption of light by the target molecules residing in the gas sample 4106.

[0229] In some embodiments, the optoelectronic gas detector system 4104, may comprise a light detector 4108 configured to receive light 4105 emitted by the integrated microplasma device 4102, and generate an electric detector signal (e.g., a photocurrent) proportional to the intensity and / or power of the received light. When the gas sample 4106 interferes with an optical path from the microplasma device 4102 and the light detector 4108, the intensity of the received light 4107 (transmitted through the gas sample 4106) may decrease due to optical absorption by the target gas molecules within the gas sample 4106 resulting in reduction of the electric detector signal (e.g., amplitude or magnitude of the photocurrent) generated by the light detector (or photodetector) 4108 indicative of presence of the target gas molecules in the gas sample 4106. In some implementations, the voltage applied on the microplasma device 4102 can be modulated with a modulation frequency and the light detector 4108 can be locked to the modulation frequency to allow lock-in measurement of the current associated with the modulated portion of received light 507 and thereby high signal-to-noise ratio measurement.

[0230] In some embodiments, a microplasma device and the corresponding microplasma chamber may be formed above a substrate. In some embodiments, some of the electrodes or electrode fingers may be suspended above a horizontal major surface of the substrate by a support structure, e.g., a bridge anchored to the substrate. In some embodiments, an electrode of such microplasma device can be formed above the substrate (e.g., using a conductive bridge or beam anchored to the substrate). In some embodiments, the plasma chamber (the enclosed volume) of a microplasma device can be formed over the substrate to allow controlling a composition and pressure of gas-filled inter-electrode or arcing region. In some embodiments, the plasma chamber may comprise a capping structure (“Silicon Cap”) enclosing at least some of the electrodes (e.g., those comprising a conductive beam) and / or the corresponding the electrode fingers. The capping structure can be hermetically sealed to form a gas-filled cavity such that microplasma can be generated and sustained between the capping structure a major surface of the substrate by the electrodes.

[0231] In some implementations, the capping structure can be hermetically sealed such that the gas or gas mixture inside its enclosed volume does not substantially mix with outside air. For example, the enclosure can be fabricated under an atmosphere other than air at a sufficientpressure such that the cavity inside the capping structure remains isolated with an internal pressure that is about the same or slightly higher relative to the outside air. In some embodiments, the capping structure may be fabricated separate from the substrate and then bonded or otherwise connected to the substrate.

[0232] In some embodiments, at least a portion of a microplasma device (e.g., a microplasma device comprising a capping structure and / or a suspended electrodes) can be fabricated using a microelectromechanical systems (MEMS) fabrication technique. In some embodiments, a microplasma device can be co-fabricated with a MEMS device on a common substrate such that at least a layer or portion of the microplasma device and a corresponding portion of the MEMS device have the same physical dimensions.

[0233] In some embodiments, any of the MPD and configurations illustrated and described above with respect to FIGS. 2A-2B, 3, 4A-4B, 6, 7A-7B, 8A-8C11A-11B, 14A-14C, 15, 16A-16J, 17A-17B, 18, 19A-19C, 21, 22A-22B, 23A-23B, and 24A-24B, may comprise one or more features described above with respect to the MPDs in FIGS. 24A-24B, 39, 40, and 41, and / or can be used in the respective applications. In some embodiments, any of the MPD and configurations illustrated and described above with respect to FIGS. 24A-24B, 39, 40, and 41 may comprise one or more features described above with respect to the MPDs in FIGS 2A-2B, 3, 4A- 4B, 6, 7A-7B, 8A-8C11A-11B, 14A-14C, 15, 16A-16J, 17A-17B, 18, 19A-19C, 21, 22A-22B, 23A-23B, and 24A-24B.

[0234] In some embodiments, any the MPDs described above may serve as a surge protector configured to protect an electronic circuit from an electrical overstress (EOS) event. In some such embodiments, the MPD may be connected between two terminals (e.g., two voltage nodes). In some embodiments, the MPD may be connected in parallel with the electronic circuit that it protects. In some embodiments, the MPD may be configured to provide a low resistance electric path between the two terminals, by forming a plasma, in response to a voltage difference between the two terminals exceeding a specified value (e.g., a voltage corresponding to a damage voltage of the electronic circuit). In some cases, the MPD may be configured such that a threshold or ignition voltage (Vth) for igniting plasma in the corresponding MPC is substantially equal to the specified value. For example, one or more of an inter-electrode gap, a gas mixture, a gas pressure, an electrode geometry, a structural characteristic of the MPC, and a control electrode of the MPD may be configured to provide an ignition voltage (Vth) substantially equal to the specified value.In some embodiments, an external EOS or surge event may initiate plasma (a transient plasma) in the MPD such that a corresponding EOS current passes through the plasma and is safely directed to ground until the EOS event ends and the plasma quenches. In some cases, the MPD may be configured such that upon ignition the plasma and electrodes can provide a low resistance path for a large electric current exceeding damage threshold of some of the existing surge protectors (e.g., integrated solid-sate surge protectors). In various implementations, upon plasma ignition a MPD can transmit electric currents from 10 to 50 Amps, from 50 to 100 Amps, from 100 to 150 Amps, from 150 to 200 Amps, from 200 to 250 Amps from 250 to 300 Amps or any ranges formed by these values or larger or smaller values.Example Embodiments

[0235] Clauses (example embodiments) described herein have several features, no single one of which is indispensable or solely responsible for their desirable attributes. A variety of example systems and methods are provided below.

[0236] Clause 1. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes comprise a conductive beam structure extending lengthwise in a lateral direction over the substrate.

[0237] Clause 2. The micro-plasma device of Clause 1, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, wherein the second electrode is electrically connected to a second metallization layer embedded in the substrate and electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0238] Clause 3. The micro-plasma device of Clause 1 or 2, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0239] Clause 4. The micro-plasma device of any preceding Clause, wherein the first and second electrodes comprise a pair of adjacently disposed conductive beam structures having elongated edges that face each other while being separated by an arcing gap in a second lateral direction.

[0240] Clause 5. The micro-plasma device of any preceding Clause, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

[0241] Clause 6. The micro-plasma device of any preceding Clause, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

[0242] Clause 7. The micro-plasma device of any preceding Clause, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

[0243] Clause 8. The micro-plasma device of any preceding Clause, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0244] Clause 9. The micro-plasma device of Clause 8, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

[0245] Clause 10. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes comprise a conductive pad structure extending lengthwise in a lateral direction over the substrate.

[0246] Clause 11. The micro-plasma device of Clause 10, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, wherein the second electrode is electrically connected toa second metallization layer embedded in the substrate and electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0247] Clause 12. The micro-plasma device of Clause 10 or 11, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0248] Clause 13. The micro-plasma device of any of Clauses 10 to 12, wherein the first and second electrodes comprise a pair of adjacently disposed conductive pad structures having the exposed electrode surfaces that face the capping structure while being separated by an arcing gap in a second lateral direction.

[0249] Clause 14. The micro-plasma device of any of Clauses 10 to 13, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

[0250] Clause 15. The micro-plasma device of any of Clauses 10 to 14, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

[0251] Clause 16. The micro-plasma device of any of Clauses 10 to 15, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

[0252] Clause 17. The micro-plasma device of any of Clauses 10 to 16, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0253] Clause 18. The micro-plasma device of Clause 17, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

[0254] Clause 19. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured tostrike and sustain a plasma in the enclosed volume in response to being externally biased, wherein the first electrode is formed as part of the capping structure.

[0255] Clause 20. The micro-plasma device of Clause 19, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second metallization layer embedded in the substrate and electrically connected to a second terminal, wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0256] Clause 21. The micro-plasma device of Clause 19 or 20, wherein the exposed surface of the first electrode is disposed at an upper inner surface of the capping structure.

[0257] Clause 22. The micro-plasma device of Clause 21, wherein the first electrode comprises a conductive layer formed on the upper inner surface of the capping structure.

[0258] Clause 23. The micro-plasma device of Clause 21 or 22, wherein the first electrode comprises a conductive structure embedded in the capping structure.

[0259] Clause 24. The micro-plasma device of any of Clauses 21 to 23, wherein the second electrode comprises a conductive beam structure extending lengthwise in a lateral direction over the substrate.

[0260] Clause 25. The micro-plasma device of any of Clauses 21 to 24, wherein the second electrode comprises a conductive pad structure extending lengthwise in a lateral direction over the substrate.

[0261] Clause 26. The micro-plasma device of any of Clauses 21 to 25, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0262] Clause 27. The micro-plasma device of any of Clauses 19 to 26, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

[0263] Clause 28. The micro-plasma device of any of Clauses 19 to 27, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

[0264] Clause 29. The micro-plasma device of any of Clauses 19 to 28, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

[0265] Clause 30. The micro-plasma device of any of Clauses 19 to 29, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0266] Clause 31. The micro-plasma device of Clause 30, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

[0267] Clause 32. A micro-plasma device comprising: a substrate having formed thereon a metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode comprises a metallization structure of the metallization layer, and wherein the second electrode is formed in the substrate.

[0268] Clause 33. The micro-plasma device of Clause 32, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

[0269] Clause 34. The micro-plasma device of Clause 33, wherein the metallization structure comprises the metal layer.

[0270] Clause 35. The micro-plasma device of Clause 33 or 34, wherein the metallization structure comprises the via.

[0271] Clause 36. The micro-plasma device of any of Clauses 32 to 35, wherein the substrate comprises a silicon substrate, and the second electrode comprises a doped region within the substrate.

[0272] Clause 37. The micro-plasma device of Clause 36, wherein the doped region comprises a bottom doped region and side doped regions surrounding the recessed volume.

[0273] Clause 38. The micro-plasma device of Clause 36 or 37, wherein the doped region is electrically connected to a second metallization structure of the metallization layer.

[0274] Clause 39. The micro-plasma device of any of Clauses 36 to 38, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

[0275] Clause 40. The micro-plasma device of any of Clauses 32 to 39, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0276] Clause 41. The micro-plasma device of any of Clauses 32 to 40, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0277] Clause 42. The micro-plasma device of any of Clauses 32 to 41, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

[0278] Clause 43. The micro-plasma device of any of Clauses 32 to 42, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0279] Clause 44. The micro-plasma device of Clause 43, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

[0280] Clause 45. A micro-plasma device comprising: a substrate having formed thereon metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode comprises a first metallization structure of the metallization layer and the second electrode comprises a second metallization structure metallization layer.

[0281] Clause 46. The micro-plasma device of Clause 45, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

[0282] Clause 47. The micro-plasma device of Clause 45 or 46, wherein the one or both of the first and second metallization structures comprise metal layers.

[0283] Clause 48. The micro-plasma device of any of Clauses 45 to 47, wherein one or both of the first and second metallization structures comprise vias.

[0284] Clause 49. The micro-plasma device of any of Clauses 45 to 48, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

[0285] Clause 50. The micro-plasma device of Clause 49, further comprising a buried oxide (BOX) layer defining a bottom surface of the recessed volume.

[0286] Clause 51. The micro-plasma device of any of Clauses 45 to 50, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0287] Clause 52. The micro-plasma device of any of Clauses 45 to 51, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0288] Clause 53. The micro-plasma device of any of Clauses 45 to 52, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

[0289] Clause 54. The micro-plasma device of any of Clauses 45 to 53, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0290] Clause 55. The micro-plasma device of Clause 54, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

[0291] Clause 56. A micro-plasma device comprising: a substrate having formed thereon an interconnect layer; a recessed volume formed under the interconnect layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in responseto being externally biased, a plasma control electrode disposed over a central region of the recessed volume and configured to be independently biased for electrostatically affecting the plasma.

[0292] Clause 57. The micro-plasma device of Clause 56, wherein the first electrode comprises a first metallization structure of the interconnect layer and the second electrode comprises a second metallization structure of the interconnect layer.

[0293] Clause 58. The micro-plasma device of Clause 57, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

[0294] Clause 59. The micro-plasma device of Clause 58, wherein the one or both of the first and second metallization structures comprise metal layers.

[0295] Clause 60. The micro-plasma device of Clause 58 or 59, wherein one or both of the first and second metallization structures comprise vias.

[0296] Clause 61. The micro-plasma device of any of Clauses 56 to 60, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

[0297] Clause 62. The micro-plasma device of Clause 61, further comprising a buried oxide (BOX) layer defining a bottom surface of the recessed volume.

[0298] Clause 63. The micro-plasma device of any of Clauses 56 to 62, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

[0299] Clause 64. The micro-plasma device of any of Clauses 56 to 63, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

[0300] Clause 65. The micro-plasma device of any of Clauses 56 to 64, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

[0301] Clause 66. The micro-plasma device of any of Clauses 56 to 65, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

[0302] Clause 67. The micro-plasma device of Clause 66, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.Additional Considerations

[0303] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” “include,” “including” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0304] Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and / or states. Thus, such conditional language is not generally intended to imply that features, elements and / or states are in any way required for one or more embodiments or whether these features, elements and / or states are included or are to be performed in any particular embodiment.

[0305] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of themethods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and / or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these blocks may be implemented in a variety of different ways. Any suitable combination of the elements and acts of the various embodiments described above can be combined to provide further embodiments. The various features and processes described above may be implemented independently of one another, or may be combined in various ways. All possible combinations and subcombinations of features of this disclosure are intended to fall within the scope of this disclosure.

[0306] In addition, unless otherwise specified, none of the steps of the methods of the present disclosure are confined to any particular order of performance. Modifications of the disclosed examples incorporating the spirit and substance of the disclosure may occur to persons skilled in the art and such modifications are within the scope of the present disclosure. Furthermore, all references cited herein are incorporated by reference in their entirety.

[0307] While the methods and devices described herein may be susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but, to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various examples described and the appended claims. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an example can be used in all other examples set forth herein. Any methods disclosed herein need not be performed in the order recited. Depending on the example, one or more acts, events, or functions of any of the algorithms, methods, or processes described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the method). In some examples, acts or events can be performed concurrently. Further, no element, feature, block, or step, or group of elements, features, blocks, or steps, are necessary or indispensable to each example. Additionally, all possible combinations, subcombinations, and rearrangements of systems, methods, features, elements, modules, blocks, and so forth are within the scope of this disclosure. The use ofsequential, or time-ordered language, such as “then,” “next,” “after,” “subsequently,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to facilitate the flow of the text and is not intended to limit the sequence of operations performed. Thus, some examples may be performed using the sequence of operations described herein, while other examples may be performed following a different sequence of operations.

[0308] The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc.). For example, “about 1 V” includes “1 V.” Numbers not preceded by a term such as “about” or “approximately” may be understood to based on the circumstances to be as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc. For example, “1 V” includes “0.9-1.1 V.” Phrases preceded by a term such as “substantially” include the recited phrase and should be interpreted based on the circumstances (e.g., as much as reasonably possible under the circumstances). For example, “substantially perpendicular” includes “perpendicular.” Unless stated otherwise, all measurements are at standard conditions including temperature and pressure. The phrase “at least one of’ is intended to require at least one item from the subsequent listing, not one type of each item from each item in the subsequent listing. For example, “at least one of A, B, and C” can include A, B, C, A and B, A and C, B and C, or A, B, and C.

Claims

WHAT IS CLAIMED IS1. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes comprise a conductive beam structure extending lengthwise in a lateral direction over the substrate.

2. The micro-plasma device of Claim 1, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, wherein the second electrode is electrically connected to a second metallization layer embedded in the substrate and electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

3. The micro-plasma device of Claim 1 or 2, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

4. The micro-plasma device of any preceding Claim, wherein the first and second electrodes comprise a pair of adjacently disposed conductive beam structures having elongated edges that face each other while being separated by an arcing gap in a second lateral direction.

5. The micro-plasma device of any preceding Claim, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

6. The micro-plasma device of any preceding Claim, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

7. The micro-plasma device of any preceding Claim, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

8. The micro-plasma device of any preceding Claim, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected toa second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

9. The micro-plasma device of Claim 8, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

10. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein one or both of the first and second electrodes comprise a conductive pad structure extending lengthwise in a lateral direction over the substrate.

11. The micro-plasma device of Claim 10, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, wherein the second electrode is electrically connected to a second metallization layer embedded in the substrate and electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

12. The micro-plasma device of Claim 10 or 11, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

13. The micro-plasma device of any of Claims 10 to 12, wherein the first and second electrodes comprise a pair of adjacently disposed conductive pad structures having the exposed electrode surfaces that face the capping structure while being separated by an arcing gap in a second lateral direction.

14. The micro-plasma device of any of Claim 10 to 13, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

15. The micro-plasma device of any of Claim 10 to 14, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

16. The micro-plasma device of any of Claim 10 to 15, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

17. The micro-plasma device of any of Claim 10 to 16, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

18. The micro-plasma device of Claim 17, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

19. A micro-plasma device comprising: a substrate having formed thereon a capping structure forming an enclosed volume filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the enclosed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the enclosed volume in response to being externally biased, wherein the first electrode is formed as part of the capping structure.

20. The micro-plasma device of Claim 19, wherein the first electrode is electrically connected to a first metallization layer embedded in the substrate and configured to be electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second metallization layer embedded in the substrate and electrically connected to a second terminal, wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

21. The micro-plasma device of Claim 19 or 20, wherein the exposed surface of the first electrode is disposed at an upper inner surface of the capping structure.

22. The micro-plasma device of Claim 21, wherein the first electrode comprises a conductive layer formed on the upper inner surface of the capping structure.

23. The micro-plasma device of Claim 21 or 22, wherein the first electrode comprises a conductive structure embedded in the capping structure.

24. The micro-plasma device of any of Claims 21 to 23, wherein the second electrode comprises a conductive beam structure extending lengthwise in a lateral direction over the substrate.

25. The micro-plasma device of any of Claims 21 to 24, wherein the second electrode comprises a conductive pad structure extending lengthwise in a lateral direction over the substrate.

26. The micro-plasma device of any of Claims 21 to 25, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

27. The micro-plasma device of any of Claims 19 to 26, wherein one or both of the first and second electrodes comprise a protrusion formed at respective ones of the exposed electrode surfaces configured to facilitate striking the plasma.

28. The micro-plasma device of any of Claims 19 to 27, wherein an inner surface of the capping structure is coated with a gettering layer configured to getter one or both of oxygen and moisture in the enclosed volume.

29. The micro-plasma device of any of Claims 19 to 28, wherein the capping structure comprises a silicon capping structure bonded to the substrate.

30. The micro-plasma device of any of Claims 19 to 29, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the enclosed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

31. The micro-plasma device of Claim 30, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

32. A micro-plasma device comprising: a substrate having formed thereon a metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode comprises a metallization structure of the metallization layer, and wherein the second electrode is formed in the substrate.

33. The micro-plasma device of Claim 32, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

34. The micro-plasma device of Claim 33, wherein the metallization structure comprises the metal layer.

35. The micro-plasma device of Claim 33 or 34, wherein the metallization structure comprises the via.

36. The micro-plasma device of any of Claims 32 to 35, wherein the substrate comprises a silicon substrate, and the second electrode comprises a doped region within the substrate.

37. The micro-plasma device of Claim 36, wherein the doped region comprises a bottom doped region and side doped regions surrounding the recessed volume.

38. The micro-plasma device of Claim 36 or 37, wherein the doped region is electrically connected to a second metallization structure of the metallization layer.

39. The micro-plasma device of any of Claim 36 to 38, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

40. The micro-plasma device of any of Claim 32 to 39, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

41. The micro-plasma device of any of Claims 32 to 40, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

42. The micro-plasma device of any of Claims 32 to 41, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

43. The micro-plasma device of any of Claims 32 to 42, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

44. The micro-plasma device of Claim 43, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

45. A micro-plasma device comprising: a substrate having formed thereon metallization layer; a recessed volume formed under the metallization layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the second electrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, wherein the first electrode comprises a first metallization structure of the metallization layer and the second electrode comprises a second metallization structure metallization layer.

46. The micro-plasma device of Claim 45, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

47. The micro-plasma device of Claim 45 or 46, wherein the one or both of the first and second metallization structures comprise metal layers.

48. The micro-plasma device of any of Claims 45 to 47, wherein one or both of the first and second metallization structures comprise vias.

49. The micro-plasma device of any of Claims 45 to 48, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

50. The micro-plasma device of Claim 49, further comprising a buried oxide (BOX) layer defining a bottom surface of the recessed volume.

51. The micro-plasma device of any of Claims 45 to 50, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

52. The micro-plasma device of any of Claims 45 to 51 , wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

53. The micro-plasma device of any of Claims 45 to 52, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

54. The micro-plasma device of any of Claims 45 to 53, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured to strike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

55. The micro-plasma device of Claim 54, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

56. A micro-plasma device comprising: a substrate having formed thereon an interconnect layer; a recessed volume formed under the interconnect layer and filled with a gas other than ambient air; and a first electrode and a second electrode having respective exposed electrode surfaces exposed to the recessed volume, wherein the first electrode and the secondelectrode are configured to strike and sustain a plasma in the recessed volume in response to being externally biased, a plasma control electrode disposed over a central region of the recessed volume and configured to be independently biased for electrostatically affecting the plasma.

57. The micro-plasma device of Claim 56, wherein the first electrode comprises a first metallization structure of the interconnect layer and the second electrode comprises a second metallization structure of the interconnect layer.

58. The micro-plasma device of Claim 57, wherein the metallization layer comprises one or more of a metal layer, a via and a dielectric layer.

59. The micro-plasma device of Claim 58, wherein the one or both of the first and second metallization structures comprise metal layers.

60. The micro-plasma device of Claim 58 or 59, wherein one or both of the first and second metallization structures comprise vias.

61. The micro-plasma device of any of Claims 56 to 60, further comprising a dielectric isolation defining one or more sidewalls of the recessed volume.

62. The micro-plasma device of Claim 61, further comprising a buried oxide (BOX) layer defining a bottom surface of the recessed volume.

63. The micro-plasma device of any of Claims 56 to 62, wherein the first electrode is electrically connected to a first terminal, and wherein the second electrode is electrically connected to a second terminal, and wherein the first and second terminals are configured to receive a driving signal from a plasma power source.

64. The micro-plasma device of any of Claims 56 to 63, wherein a smallest physical distance between the exposed electrode surfaces of the first and second electrodes is greater than about 6 microns.

65. The micro-plasma device of any of Claims 56 to 64, further comprising a capping structure formed on the substrate and over the recessed volume, thereby defining an enclosed volume in fluid communication with the recessed volume.

66. The micro-plasma device of any of Claims 56 to 65, wherein the first electrode is electrically connected to a first voltage node and the second electrode is electrically connected to a second voltage node, and wherein the first electrode and the second electrode are configured tostrike and sustain the plasma in the recessed volume in response to a voltage difference between the first and second voltage nodes exceeding a threshold value.

67. The micro-plasma device of Claim 66, wherein the micro-plasma device is configured as a surge protector and wherein the plasma provides a low resistance electrical path between the first and second voltage nodes to protect a device connected between the first and second voltage nodes.

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