High-Frequency System Protection Based on Temperature Estimation

Abstract

A method for thermally protecting an electronic circuit is disclosed. In at least one embodiment, the electronic circuit comprises at least a first component and a second component. In at least one embodiment, the method comprises measuring a first input voltage and a first input current of the first component. In at least one embodiment, the method further comprises calculating a second input voltage and a second input current of the second component. In at least one embodiment, the method further comprises calculating a first temperature of the first component and a second temperature of the second component, wherein the first temperature is a function of the first input current and the second temperature is a function of the second input current

Description

Priority Claim

[0001] This application claims the benefit of priority based on U.S. Provisional Patent Application No. 63 / 365,992, filed on June 7, 2022, entitled "RADIO FREQUENCY SYSTEM PROTECTION BASED ON TEMPERATURE INFERENCE", which provisional patent application is hereby incorporated by reference in its entirety for all purposes. BACKGROUND OF THE INVENTION

[0002] Processing tools are utilized to perform processes such as film deposition and etching on semiconductor wafer substrates. These processing tools can utilize plasma for etching, substrate cleaning, and deposition. Plasma can be generated and maintained by capacitive coupling or inductive coupling to a field that is generated, controlled, and distributed by an external power supply network of the chamber. The power supply network can supply power from a high-frequency power generator to a coupling interface. The coupling interface can be an inductance coil, an antenna, or a capacitive electrode, and couples RF energy stored in a magnetic field or an electric field to the plasma. Due to fluctuations in the electron density and current in the coupled plasma, the impedance load of the power supply network can vary. Impedance mismatches between the plasma and the power supply network (including the impedance matching circuit) can occur randomly or regularly due to process drifts, causing coupling losses due to power reflections at the coupling interface. As a result of the losses, a decrease in power efficiency and a change in processing performance can occur. The power supply network can comprise a plurality of components in series and parallel combinations. The components of the power supply network can include passive LC filters, transmission lines, and the like. The power reflected due to a large impedance mismatch at the interface can cause overcurrents through one or more components in the power supply network, causing overheating of the components. Some components can be damaged by overheating. Current solutions for the protection of sensitive power supply components include introducing a plurality of temperature sensors along the power supply network component chain to monitor the temperature of individual or group-wise heat-sensitive components. A solution for overcurrent draw can be to flag the situation and automatically or manually limit the power to the plasma. Other solutions can include setting an upper limit on the maximum power available to the plasma tool. These solutions involving a plurality of temperature sensors can be costly and difficult to implement. Furthermore, the reduction of plasma power can unnecessarily limit the peak power available to the plasma. Brief Description of the Drawings

[0003] The materials described in this specification are shown by way of example and not by way of limitation in the accompanying drawings. For the sake of simplicity and clarity of the figures, the elements shown in the drawings are not necessarily drawn to scale in their exact positions. For example, the dimensions of some elements may be exaggerated for simplicity relative to other elements. Also, various physical features may be represented in a “simplified” or “idealized” form and shape for simplicity of discussion, but it is understood that actual implementations may only approximate the ideal described. For example, smooth surfaces and right-angled intersections may be drawn ignoring the finite roughness, rounded corners, and imperfect angular intersections characteristic of structures formed by nanomachining techniques. Further, reference numerals are repeated in the figures as appropriate to indicate corresponding or similar elements.

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[0010] In this specification, apparatuses and methods for protecting components of a plasma power supply network from overheating and potential failure are disclosed, according to at least one embodiment. Overheating of such components can occur when there is a mismatch between the instantaneous plasma impedance and the impedance matching between components of the plasma power supply network. A large impedance mismatch can cause a large amount of power to be reflected from the plasma coupling interface (such as a coil), through the impedance matching circuitry, and back through the power supply network. The reflected power can lead to impedance mismatches between components and can cause excessive current to flow through one or more components. Some components may include single or multiple temperature-sensitive circuit elements, which can be overheated by excessive current. The temperature reached can exceed the temperature limits of the circuit elements provided by the manufacturer. Thus, the circuit elements may be damaged or destroyed by the large heat input, potentially causing a failure of the power supply network.

[0011] The disclosed method provides, according to at least one embodiment, among other advantages, an improvement over existing methods for protecting power supply components in a plasma processing system. The disclosed method utilizes, according to at least one embodiment, a single measurement point for RF voltage and current along the power supply network. The advantages provided include, according to at least one embodiment, in particular, reducing or eliminating temperature sensors conventionally used to monitor the temperature of plasma circuit components. Such temperature sensors are often difficult to install and, when utilized, increase the operational complexity of the plasma processing tool. Further, incorporating temperature sensors can increase the purchase and maintenance costs of the plasma processing tool.

[0012] In at least one embodiment, voltage and current may be physically measured at a single convenient node between any two components along a cascade-connected configuration of components of the power supply network. In at least one embodiment, the measured RF voltage and current may include the RF voltage across the input port of the first component downstream of the node, and the RF current flowing into the input port of the first component. In at least one embodiment, the measured RF voltage and current may be equal to the voltage across the output port of the second or upstream component, and the current flowing out of the output port of the upstream component.

[0013] In at least one embodiment, when measured, the RF current and voltage may be converted to power and voltage at other nodes along the power supply network component chain by application of a transfer function and / or transfer matrix. In at least one embodiment, by monitoring the voltage and current at a single node within the power supply network, the current and voltage at multiple nodes within the power supply network may be calculated simultaneously. In at least one embodiment, the current flowing into each component, and / or the node voltage across the input terminals of an individual component, may be known within an acceptable error tolerance. In at least one embodiment, once determined, the calculated current and / or voltage may be converted to input power to the individual components. In at least one embodiment, a portion of the input power may be dissipated as heat due to circuit element resistance and dielectric losses.

[0014] In at least one embodiment, circuit elements within individual components may have a predetermined thermal constant. In at least one embodiment, after determining the current and voltage at a plurality of nodes within a power supply network, the calculated input power may be applied to a heat quantity calculation adjusted for each circuit element within the component. The instantaneous estimated temperature of each circuit element can be determined. In at least one embodiment, a single voltage / power sensor may be periodically read by a microprocessor to update the state of the measurement target node. In at least one embodiment, by repeating the series of the above calculations, the temperature state of one or more within the component may be periodically updated.

[0015] Thus, when a significant impedance mismatch condition occurs, the disclosed method can provide the temperature calculated for each circuit element within each component within a power supply network according to at least one embodiment without using a temperature sensor. In at least one embodiment, any significant temperature rise of a component or an individual circuit element within the component can be detected. In at least one embodiment, an alarm to the user of the plasma chamber tool is set to mitigate the excessive temperature. In at least one embodiment, a correction routine is triggered to reduce the excessive temperature. In at least one embodiment, RF energy may be burst-supplied to the plasma. Such a burst may have a duty cycle, where the on-time and off-time may be adjusted within the duty cycle period. In at least one embodiment, by reducing the on-time of the duty cycle, the average power supplied to the plasma can be reduced without reducing the amplitude of the voltage or current of the power waveform.

[0016] In at least one embodiment, the calculated temperature may indicate an over-temperature (i.e., overheat) condition of a particular circuit element. To correct the overheat condition, in at least one embodiment, the peak RF power and the RMS (root mean square) power from the RF source may be kept constant while the average power supplied to the plasma is reduced. In at least one embodiment, the voltage and current at individual nodes along the power supply network follow a duty cycle adjustment of the RF current. In at least one embodiment, an overall reduction in the current time phase of the duty cycle may enable a reduction in the temperature of all circuit elements, while protecting most heat-sensitive components by keeping the peak levels of the current and voltage substantially constant. In at least one embodiment, the duty cycle may be readjusted after an impedance mismatch condition has been corrected or mitigated.

[0017] In some instances, well-known methods and devices are not shown in detail in order to avoid obscuring the present disclosure and are shown in the form of block diagrams. References herein to "an embodiment" or "one embodiment" or "some embodiments" mean that a particular feature, structure, function, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases "in an embodiment" or "in one embodiment" or "in some embodiments" in various places in this specification are not necessarily all referring to the same embodiment of the present disclosure. Further, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, where the particular features, structures, functions, or characteristics associated with two embodiments are not mutually exclusive, the first embodiment may be combined with the second embodiment.

[0018] As used herein, "coupled" and "connected," along with their derivatives, can be used to describe a functional or structural relationship between components. These terms are not intended to be synonymous with each other. Rather, in certain embodiments, "connected" can be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. As used herein, "coupled" can be used to indicate that two or more elements are in physical, electrical, or magnetic contact with each other either directly or indirectly (with other intervening elements between the elements), and / or that two or more elements cooperate with each other, or interact (e.g., in a cause-and-effect relationship, etc.). As used herein, "coupled" can generally also mean the direct attachment of one electronic component to another. An electric field or a magnetic field may couple one component to another, where the field is controlled by one component to affect the other in some way.

[0019] As used herein, "over," "under," "between," and "on" can refer to the relative position of one component or material with respect to another component or material when such physical relationships are of interest. These terms can be used with the presence of one or more intervening components or materials, unless they are modified by "direct" or "directly." A similar distinction is made in the context of component assembly. As used throughout this description and in the claims, a list of items joined by "at least one of" or "one or more of" can mean any combination of the listed terms.

[0020] As used herein, "adjacent" generally can refer to an arrangement where one thing is next to (e.g., immediately next to or near another thing with one or more things in between) or in contact with (e.g., abutting) another thing.

[0021] Unless otherwise specified in the context of use, "substantially equal", "about equal", and "approximately equal" can mean that there are only incidental differences between the two things so described. In at least one embodiment, such differences are typically within + / - 10% of a reference value.

[0022] As used herein, "processing tool" generally can mean a semiconductor processing tool (such as a plasma processing tool), and such a tool can include a chamber having an antenna coil coupled to a radio frequency (RF) signal source. In at least one embodiment, the antenna coil is used to generate an electromagnetic field, and the electromagnetic field generates an inductive electric field that maintains a plasma by transformer action.

[0023] As used herein, "upstream" and "downstream" can generally refer mainly to the dominant direction of power flow with respect to an electric current. In at least one embodiment, an upstream component is on the source side or generator side of a node, and a downstream component is on the load side of the node, where power flow is from the source to the load.

[0024] As used herein, a "node" can generally refer to a point between an output port of an upstream component and an input port of an adjacent downstream component. In at least one embodiment, a component of a power supply network is treated as a two-port network having an input port and an output port. In at least one embodiment, each port has two terminals. In at least one embodiment, the two-port network may be or include a passive LC filter or an individual inductor, a resistor, and a capacitor. In addition to passive LC devices, in at least one embodiment, the two-port network may include a transmission line, a switch, an RF choke, and the like.

[0025] As used herein, a "terminal" can generally refer to an end of a conductor or an electrical component (such as a wire) and can be a connection point to another conductor or electrical component. In the context of a coil, in at least one embodiment, a terminal is an end of a winding. Referring to a coil segment, in at least one embodiment, a coil segment can include terminals at the beginning and end of the coil segment conductor.

[0026] As used herein, an "inductor" can generally refer to a passive electrical device that stores magnetic energy from the current flowing through it. In at least one embodiment, the inductor may comprise a conductor (e.g., a metal wire) that can couple an electrically generated magnetic field to another nearby conductor to induce a voltage and current in the second conductor. In at least one embodiment, the magnetic field can be generated by a current flowing in the first conductor in accordance with Faraday's law of electromagnetic induction. The conductor has the property of inductance, which is a function of the magnitude of the current flowing in the conductor and the shape or geometry of the conductor. Any conductor can be an inductor, but some shapes produce a stronger inductance than others. A straight wire can have a small inductance that depends on its diameter and length. By winding a straight wire into a coil, for example, the inductance can be increased by a factor equal to the number of turns per unit length due to the additional mutual coupling of the magnetic fields between each turn, strengthening the overall magnetic field. The magnetic field from each pair of windings increases the magnetic field generated by the straight wire in accordance with Ampere's law. In at least one embodiment, the coil can be a planar coil or a helical coil (such as a solenoid or a tapered helix, etc.).

[0027] As used herein, a "capacitor" can generally refer to a passive electrical device that stores charge and electrical energy in the form of an electric field. In at least one embodiment, a capacitor generally has at least two conductive plates that are separated by a dielectric material and are in close proximity to each other. In at least one embodiment, the dielectric material can be air (or other gas) or a vacuum. In at least one embodiment, the dielectric can generally be a solid or liquid material such as a polymer, ceramic, or semi-liquid electrolyte. In at least one embodiment, opposite charges can accumulate on adjacent plates to form an electric field that extends through the dielectric from plate to plate. In at least one embodiment, the electric field can store electrical energy.

[0028] As used herein, "radio frequency" (abbreviated as "RF") can generally refer to a part of the electromagnetic spectrum having frequencies in the range from 10 kilohertz (kHz) to several hundred gigahertz (GHz).

[0029] As used herein, "plasma" can generally refer to a gas composition containing charged particles such as positively or negatively charged atomic or molecular ions and electrons. Plasma is considered the fourth state of matter.

[0030] As used herein, "inductively coupled plasma" (abbreviated as "ICP") can generally refer to a plasma generated by a time-varying magnetic field generated from a primary inductor or plasma antenna (generally in the form of a coil) that conducts an RF current. In at least one embodiment, low concentrations of ionized atoms or molecules and free electrons in the gas can be generated by a discharge. In at least one embodiment, a slightly ionized gas may be regarded as a secondary inductor coupled to the plasma antenna, and the plasma antenna may be regarded as the primary inductor of a transformer, where the plasma can be regarded as the secondary inductor of the transformer to which the primary inductor is coupled. In at least one embodiment, the gas may pass through an electromagnetic field generated by an adjacent ICP antenna, where charges are accelerated by a time-varying electric field associated with the time-varying magnetic field (in accordance with Faraday's law of electromagnetic induction and the Faraday-Maxwell equations). In at least one embodiment, the accelerated electrons can collide with neutral atoms or molecules to generate more ions and secondary electrons, increasing the plasma density of charged particles. In at least one embodiment, the magnitude of the particle acceleration and thus the collision velocity is proportional to the strength of the electric field, and the strength of the electric field is proportional to the magnetic field strength. In at least one embodiment, ultimately, the magnetic field strength is proportional to the magnitude of the current flowing in the ICP antenna.

[0031] As used herein, an "ICP antenna" generally may refer to an inductor through which an RF current passes and that can radiate RF power to a limited extent as a near electrostatic field and a propagating electromagnetic field. In at least one embodiment, an RF current flows through the ICP antenna and generates an electromagnetic field that couples to a partially ionized gas and a fully developed plasma. In at least one embodiment, the former can be made into a plasma by the action of the electromagnetic field.

[0032] As used herein, a "capacitively coupled plasma" (CCP) generally may refer to a plasma capacitively coupled to an electric field between two or more electrodes within a plasma chamber.

[0033] As used herein, a "transmission line" generally may refer to a cable having at least two conductors in parallel and close proximity. In at least one embodiment, a transmission line generally carries equal and opposite currents and voltages for each conductor. The magnetic fields of the opposite currents cancel each other out to reduce or eliminate electromagnetic radiation from the conductors. In at least one embodiment, a transmission line can carry RF current and voltage from a source to a load (such as an antenna) without radiating RF energy. A transmission line has a characteristic impedance.

[0034] As used herein, a "dielectric material" generally may refer to a non-conductive material such as a polymer, ceramic, glass, wood, etc.

[0035] Here, "radio frequency" (RF) generally may refer to electromagnetic radiation oscillating at a frequency within a spectrum substantially including frequencies between 10 kilohertz (kHz) and 1 terahertz (THz, i.e., 10 15 Hz). In at least one embodiment, the upper limit of the RF spectrum may only extend up to several hundred gigahertz (GHz). The term radio frequency is generally abbreviated as "RF".

[0036] As used herein, a "RF signal source" can generally refer to an electronic device capable of generating high-frequency electrical signals. In at least one embodiment, the RF signal source can output a large RF current (e.g., 1 ampere rms or more) at a large voltage. In at least one embodiment, the RF signal source for an ICP antenna can generally output up to several hundred volts and up to several hundred amperes to generate a large amount of power.

[0037] As used herein, a "circuit element" can generally refer to an active or passive electronic device that can be part of an electronic circuit.

[0038] As used herein, a "passive element" can generally refer to an electronic element having an output response that is not controllable by an electronic signal, and the output response is related to an input signal (such as voltage and / or current). In at least one embodiment, the passive element is a resistor, where the voltage drop across the resistor is not controllable by a separate electronic signal and is simply a function of the current flowing through it. Other examples of passive elements are capacitors and inductors. In at least one embodiment, the passive element may be modeled as a two-port component. In at least one embodiment, an active element is an electronic device (such as a transistor) having at least a third port to which a control signal is applied to control the output of the device.

[0039] Here, a "component" can generally refer to a circuit element or a combination of circuit elements (passive and / or active) that is part of a circuit network.

[0040] Here, a "circuit network" can generally refer to a plurality of circuit elements connected together to form an electronic circuit. In at least one embodiment, the circuit network generally has two or more ports.

[0041] As used herein, a "port" can generally refer to a network terminal through which a signal can enter or leave a network. In at least one embodiment, the network generally has at least two ports, at least one of which is an input port and at least a second port is an output port.

[0042] As used herein, an "input" can generally refer to a network port through which a signal enters the network. Input signals can be input voltage and input current.

[0043] As used herein, an "output" can generally refer to a network port through which a signal leaves the network. In at least one embodiment, output signals can be output voltage and output current.

[0044] Here, "impedance" can generally refer to the resistance of a circuit element to alternating current at generally audible frequencies and RF frequencies. In at least one embodiment, impedance can be a general term for electrical resistance. In at least one embodiment, reactance is the impedance of a capacitor or an inductor. In at least one embodiment, reactance is different from resistance in that it is non-dissipative (there is no power loss as heat). Impedance is defined as the ratio of voltage to current. Complex impedance is a combination of resistance and reactance, where reactance is an imaginary value and resistance is a real value. Complex impedance can be expressed as magnitude and phase angle in polar coordinates, where the phase angle is the phase between voltage and current.

[0045] As used herein, "input impedance" and "output impedance" can generally refer to the impedance of the input port and the output port, respectively. They are, respectively, the ratio of input voltage to input current, and the ratio of output voltage to output current.

[0046] As used herein, an "impedance matching circuit network" can generally refer to an electronic circuit network that matches an output impedance to an input impedance.

[0047] As used herein, an "LC filter" can generally refer to an electronic circuit network that includes a combination of a passive inductor (L) and a capacitor (C) to pass a specific frequency input to the filter circuit. In at least one embodiment, the LC filter is a high-pass filter, a low-pass filter, a band-pass filter, and a notch filter. In at least one embodiment, the LC filter can also be an impedance matching circuit network.

[0048] As used herein, a "power supply network" can generally refer to an electronic circuit that includes a plurality of electrical components that can be coupled to each other. In at least one embodiment, the components are coupled in series (in cascade). In at least one embodiment, the power supply network can be designed to carry RF power from a source to a load.

[0049] As used herein, "cascade" can generally refer to combining circuit networks in series such that the output of a first circuit network becomes the input of a second circuit network coupled to the first circuit network.

[0050] As used herein, a "processing tool" can generally refer to a part of a device used in semiconductor manufacturing and is also referred to as a "semiconductor processing tool" for semiconductor processing. In at least one embodiment, the processing tool can generally include a vacuum chamber in which processes such as substrate plasma etching or plasma enhanced chemical vapor deposition are performed. In at least one embodiment, other non-plasma related processes can also be performed in the processing tool.

[0051] As used herein, a "chuck" can generally refer to a stage or platform to which a substrate (e.g., a wafer) can be attached.

[0052] As used herein, "substrate" generally may refer to a wafer including a semiconductor (e.g., silicon) or an insulator (e.g., aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, float glass, borosilicate glass, etc.). In at least one embodiment, the wafer may be a thin slice of single crystal semiconductor or insulator. In at least one embodiment, the wafer may also include polycrystalline or amorphous (glass-like) materials. In at least one embodiment, the wafer may generally have a diameter in the range of 100 mm to 500 mm and a thickness in the range of generally 100 microns to 1 mm.

[0053] As used herein, "processing chamber" generally may refer to the vacuum chamber of a processing tool into which a substrate can be introduced for processing. In at least one embodiment, the processing chamber may include a chuck for holding the substrate. In at least one embodiment, the processing chamber is a plasma etching chamber.

[0054] As used herein, "magnetic field" generally may refer to lines of the direction and intensity of magnetic flux generated from a magnetized material or an energized material.

[0055] As used herein, "plasma enhanced processing" generally may refer to semiconductor processing in which plasma is used, for example, to assist processing in some way. In at least one embodiment, the plasma enhanced processing is enhanced compared to a similar or same processing that does not utilize plasma. Examples are reactive ion etching and plasma enhanced chemical vapor deposition or plasma enhanced atomic layer deposition.

[0056] As used herein, "reactant species" generally may refer to electrons, ions, or neutral radicals formed within the plasma.

[0057] As used herein, "ion" generally may refer to a charged atom or a charged molecule. In at least one embodiment, the ion may be an atom or molecule of a gas that loses or gains electrons within the plasma.

[0058] As used herein, a "machine-readable storage medium" generally can refer to a memory that stores binary code or data readable by a processor. In at least one embodiment, the machine-readable storage medium can be a non-volatile solid-state storage medium, volatile memory, magnetic hard drive, optical disk, etc.

[0059] As used herein, a "machine-readable instruction" generally can refer to binary code stored in a machine-readable storage medium. When executed, the binary instruction can cause a processor to perform a specific function.

[0060] As used herein, a "transfer matrix" generally can refer to a set of interdependent linear equations in matrix form for calculating a first voltage and a first current at a first node from a second voltage and a second current at a second node. In at least one embodiment, the second voltage and the second current can be measured or calculated. In at least one embodiment, the matrix generally can be a 2×2 matrix, although larger matrices (such as a 3×3 matrix) may be applied. In at least one embodiment, the transfer matrix can be applied to convert a first voltage and a first current at a first node in an electronic circuit to a second voltage and a second current at a second node. In at least one embodiment, impedance can be similarly converted.

[0061] As used herein, a "transfer function" generally can refer to an equation for calculating an input voltage or current of a circuit or circuit component to an output voltage or current of the circuit or circuit component. The terms of the equation can include combinations of values of circuit components. The transfer function can be equally applied to calculate an output voltage and / or current from an input voltage and / or current.

[0062] FIG. 1 is a cross-sectional view showing a plasma processing tool 100 in accordance with at least one embodiment. In at least one embodiment, the plasma processing tool 100 includes a plasma chamber 102 for plasma-enhanced processing of a wafer 104, a chuck 106, a plasma 108, an antenna 110, a wall 112, and a power supply network 114.

[0063] In at least one embodiment, the chuck 106 supports the wafer 104 and can electrically stabilize the wafer 104 in the presence of the plasma 108. In at least one embodiment, the chuck 106 may be grounded or biased. In at least one embodiment, the bias may be a DC voltage or a periodic voltage waveform applied to the chuck 106. In at least one embodiment, the plasma 108 is an inductively coupled plasma (ICP) and may be generated and maintained within the plasma chamber 102 by a radio frequency (RF) electromagnetic field radiated by the ICP antenna 110. In at least one embodiment, the radiated electromagnetic field is indicated by a downward arrow (symbol H) representing the RF magnetic field and a horizontal arrow (symbol “E”) representing the RF electric field. In at least one embodiment, the RF E field can ionize the atoms and molecules of the gas introduced into the plasma chamber 102 to generate gas ions and free electrons. In at least one embodiment, the free electrons can form a plasma current following an orbit perpendicular to the RF H field as shown in the figure. In at least one embodiment, the plasma current can then generate an induced magnetic field B that couples back to the ICP antenna 110. In at least one embodiment, the plasma 108 is electromagnetically coupled to the ICP antenna 110. In at least one embodiment, the plasma 108 may be a capacitively coupled plasma (CCP), where an electrode (not shown) within the plasma chamber 102 is coupled to the plasma 108 by, for example, an RF electric field extending between the electrode and the chuck 106.

[0064] In at least one embodiment, the ICP antenna 110 can be isolated from the plasma chamber 102 by a wall 112 to protect the ICP antenna 110 and any associated electronics from the plasma 108. The ICP antenna 110 may be powered by an RF power distribution network 114. In at least one embodiment, the power supply network 114 may comprise a plurality of N components represented by components 116, 118, 120, and 122, where N≧1. In at least one embodiment, components 116 - 122 may be part of the RF power supply network 114. In at least one embodiment, N may be 4 or more. Component 116 is labeled as component 1 and can be regarded as the first component in the component chain of the RF power supply network 114. In at least one embodiment, a part of the RF power supply network 114 can be regarded as a source end. In at least one embodiment, the next component in the component chain (component 118) is labeled as component N - 2. When N>4, N - 2>2, and one or more components may be included between component 116 and component 118. In at least one embodiment, the remaining components 120 and 122 are labeled as component N - 1 and component N, respectively, where component N is the last component in the component chain. In at least one embodiment, although components 116 - 122 (and additional components not shown) are shown to be connected in series, some components may be connected in parallel.

[0065] In at least one embodiment, components 116, 118, 120, and 122 are represented as a cascaded two-port network, and each component has an input port and an output port. In at least one embodiment, in the arrangement of the RF power supply network 114, component 116 is upstream of components 118-122 in terms of the power flow within the RF power supply network 114. Repeating the above definitions, "upstream" herein means "towards the source", and "downstream" means "towards the load". In at least one embodiment, power flows from the source to the load. Here, according to at least one embodiment, the source may be RF source 126 and / or RF source 128, and the load may be ICP antenna 110.

[0066] In at least one embodiment, the output port of the upstream component may be coupled to the input port of the adjacent downstream component. According to at least one embodiment, output port 130 of component 118 may be coupled to input port 132 of component 120, where component 120 is downstream of component 118. The coupling between the output port and the input port may be referred to as a node. In at least one embodiment, the node may be bounded by the input port of the upstream component and the output port of the adjacent downstream component. The node may be characterized by a node voltage and a node current. In at least one embodiment, the node voltage may be the output voltage V of the upstream component measured across two terminals out that may be. In at least one embodiment, the node current may be the output current I of the upstream component flowing into the input port of the downstream component as I in and may be. out

[0067] In at least one embodiment, the input impedance Z in of each input port defined as the ratio of V in / I in is such that the output impedance Z out of each output port defined as V out / I outWhen matched with V out = V in and I out = I in is. In at least one embodiment, in an impedance mismatch condition, V out and V in across the node can be different, while I out and I in can also be different. In at least one embodiment, the lack of continuity of voltage and current at the mismatch node can be the result of reflected voltage and current waves due to impedance mismatch.

[0068] In at least one embodiment, the individual components 116 - 122 may comprise a passive circuit comprising circuit elements such as inductors (L), capacitors (C), resistors (R), and switches. In at least one embodiment, at least some of the components 116 - 122 may comprise LCR (inductor, capacitor, and resistor) circuit elements that can be combined within a filter circuit, where a low-pass filter, high-pass filter, band-pass filter, or notch filter may be constructed. In at least one embodiment, one or more of the components 116 - 122 may comprise an impedance matching network including an LC circuit arranged as an "L-shaped" network topology, "T-shaped" network topology, "π-shaped" network topology, or a combination thereof.

[0069] In at least one embodiment, components 116 - 122 may include passive circuit elements such as switches, transmission lines, transformers, directional couplers, power splitters, power combiners, individual inductors (e.g., RF chokes), and capacitors (but not limited to these). In at least one embodiment, these components may be used, for example, to isolate and block LF (low frequency) and HF (high frequency) currents. The transmission line (e.g., transmission line 124) may be a coaxial transmission line or a two - conductor bare wire. In at least one embodiment, the transmission line may couple component 122, which is at the load end of the RF power supply network 114, to the ICP antenna 110. In at least one embodiment, component 122 itself may be a transmission line, and transmission line 124 may be an extension of component 122 that couples to the ICP antenna 110.

[0070] In at least one embodiment, the ICP antenna 110 may be coupled to RF signal sources 126 and 128 at the input port 134 of component 116, which is at the upstream end (i.e., the generator side) of the component chain. In at least one embodiment, RF signal source 126 is a low - frequency (LF) RF signal source, i.e., a generator, and RF signal source 128 is a high - frequency (HF) signal generator. In at least one embodiment, RF signal source 126 may generate a frequency lower than 1 MHz, while RF signal source 128 may generate a frequency higher than 1 MHz. RF signal sources 126 and 128 may output a pure sine - wave voltage or other voltage waveforms (such as square waves, sawtooth waves, triangular waves, and other suitable waveforms). In at least one embodiment, RF signal sources 126 and 128 may be capable of outputting high - power generation, for example, with a power of up to 10 kilowatts (hundreds of volts and dozens of amperes).

[0071] In at least one embodiment, RF signal source 126 is shown as being differentially coupled to power supply network 114, but may optionally be coupled by a single-ended connection, in which case one end is grounded. In at least one embodiment, this configuration is shown by a dashed line connecting a ground symbol to the underside of RF source 126. In at least one embodiment, RF signal source 128 is also shown as being differentially coupled to RF power supply network 114, but may be coupled to RF power supply network 114 by a single-ended connection. In at least one embodiment, two RF signal sources are shown as being coupled to RF power supply network 114. In some embodiments, a single RF signal source may be used. In at least one embodiment, multiple RF (e.g., three or more) signal sources may be used.

[0072] In at least one embodiment, ICP antenna 110 is in the form of a coil. As described above, ICP antenna 110 may be isolated from plasma chamber 102 by wall 112. In at least one embodiment, wall 112 includes a dielectric material that allows the electric and magnetic fields from ICP antenna 110 to couple with plasma 108 within plasma chamber 102. In at least one embodiment, ICP antenna 110 is shown as a flat coil, i.e., a "pancake" coil, but ICP antenna 110 may have other suitable shapes (such as a serpentine coil or a helical solenoid coil). Individual turns of the antenna coil are shown in cross-section. ICP antenna 110 is shown as a flat spiral coil (e.g., a "pancake coil") in the illustrated embodiment and includes a plurality of windings as shown in the cross-sectional view. In at least one embodiment, for a tubular chamber shape, ICP antenna 110 may have a helical (e.g., solenoid) shape. In at least one embodiment, the solenoid may generally have a cylindrical form factor, where the conductor may be in the form of a helical coil.

[0073] In at least one embodiment, as already described, the plasma 108 is coupled to the ICP antenna 110 through an RF electromagnetic field generated from the ICP antenna 110. In at least one embodiment, the electromagnetic field sustains the plasma 108. In at least one embodiment, the electric field E can be large enough to ionize the low-pressure gas introduced into the plasma chamber 102, and the plasma chamber 102 is generally pumped to a high vacuum. In at least one embodiment, the free electrons formed by the electric field can form a circular plasma current under the influence of the magnetic field H spreading from the ICP antenna 110. In at least one embodiment, the density n of free electrons in the plasma 108 e is at least partially a function of the supplied RF power, and the supplied RF power can appear as the electric field strength E and the magnetic field strength H. In at least one embodiment, the RF frequency can also affect the free electron density n e . In at least one embodiment, a higher frequency can increase the formation rate of free electrons by increasing the number of collisions between ions and gas atoms or molecules, and between electrons and gas atoms.

[0074] In at least one embodiment, the density n of free electrons in the plasma 108 e can be a parameter that determines the plasma impedance. In at least one embodiment, the plasma impedance can be represented as an electrical impedance Z including a series combination of resistance and inductance p . In at least one embodiment, the plasma impedance Z p can be proportional to the free electron density. In at least one embodiment, the inductance of the plasma can be related to the induced magnetic field B generated by the circular plasma current i (which is also proportional to n e ) coupled to return to the ICP antenna 110. In at least one embodiment, the interaction between the ICP antenna 110 and the plasma 108 can be similar to the interaction between the primary and secondary windings of a transformer.

[0075] In at least one embodiment, the coupling between the plasma 108 and the ICP antenna 110 can affect the input impedance Z of the ICP antenna 110. ant In at least one embodiment, an impedance matching network may be required to match Z to components within the RF power supply network 114 upstream of the ICP antenna 110 towards the RF signal sources 126 and 128. ant In at least one embodiment, both RF signal sources 126 and 128 may have an output impedance Z, for example, of 50 Ω. gen In at least one embodiment, the system impedance of the RF power supply network may be designed to be 50 Ω, meaning that the Z of each component and Z in and Z out are also substantially 50 Ω in a matched state. The Z of the ICP antenna 110 ant can be significantly different from 50 Ω.

[0076] In at least one embodiment, a matching circuit network can convert Z ant to 50 Ω. In at least one embodiment, a component 122 (component N) at the load end of the RF power supply network 114 may comprise, for example, an LC impedance matching L-shaped or π-shaped circuit network to provide appropriate matching. In at least one embodiment, the component 122 may be a transmission line designed to convert Z ant to the system impedance. In at least one embodiment, the transmission line may have a characteristic impedance Z0 between Z ant and 50 Ω. In at least one embodiment, the length of the transmission line (such as the transmission line 124) may be adjusted to match Z ant to the system impedance (e.g., 50 Ω). In at least one embodiment, the length of the transmission line may be cut to one quarter of the wavelength at an HF frequency (e.g., the Q section) when Z0 is approximately equal to the geometric mean of Zant and the system impedance.

[0077] In at least one embodiment, Z antThe variation of [Z] is partly due to, for example, an instantaneous change in the gas flow rate or pressure in the plasma chamber 102, the plasma impedance Z during processing p may be caused by the variation of. In at least one embodiment, Z p The variation of may cause the detuning of the matching network of component 122, thereby causing a change in the input impedance of component 122 (e.g., Z Nin ). In at least one embodiment, the detuning of component 122 causes a change in Z Nin which may cause a mismatch to the output impedance Z of component 120 (component N - 1) N-1out . In at least one embodiment, the mismatch to the output impedance may cause the propagation of impedance mismatches at each node in the component chain of the RF power supply network 114 all the way to the RF signal sources 126 and 128.

[0078] In at least one embodiment, the matching network (e.g., component 122) may comprise variable capacitors and / or inductors as circuit elements so that the matching network can be adjusted according to the variation of Zant caused by the variation of Zp. In at least one embodiment, the matching network (e.g., component 122) may be adjusted to match a small range of plasma impedances. In at least one embodiment, the adjustment may be partly performed by providing a variable capacitor or inductor in the upstream component to match the output and input impedances Z in and Z out between adjacent components. In at least one embodiment, the value of the LC filter circuit element in a certain component may be adjusted to produce a desired matching impedance to match the impedances of the adjacent upstream and downstream components. This approach can be cumbersome as it requires the control of each component for driving the variable capacitor or inductor.

[0079] The output impedance of component 122 is a specific Z antAssuming that it can be adjusted with respect to, the output impedance Z of component 120 N-1out The input impedance Z of component 122 as seen by Nin can change such that component 120 can draw a larger current. Further, the power to plasma 108 can be reduced by current and voltage reflections occurring at the output port 136 of component 122. The amount of power reflected to the input port 138 of component 122 can be represented by the reflection coefficient ρ for the current and voltage reflected from node 142 between component 122 and transmission line 124. The reflected RF current and voltage waves can cause standing waves along transmission line 124 and, partially, within component 122. At a large standing wave ratio (SWR), the standing wave of current can include current peaks much larger than the ratings of the circuit elements within component 122. Some circuit elements cannot safely conduct such high currents. When a circuit element is exposed to a current exceeding the rating of the circuit element manufacturer, overheating can occur. Overheating of individual circuit elements can lead to failure of the entire component. In some examples, the coupling of the power supply (e.g., RF signal sources 126 and / or 128) to the ICP antenna 110 can gradually detune over time. This gradual detuning can gradually cause a larger impedance mismatch between the RF signal source and the plasma 108. The impedance mismatch can gradually increase over time.

[0080] In the above description, the inductively coupled plasma system has been described with attention. However, in at least one embodiment, a capacitively coupled plasma (CCP) system may be used in the plasma processing tool 100. In at least one embodiment, in the CCP system, the plasma chamber 102 includes a pair of electrodes separated by a certain distance. In at least one embodiment, one of the pair of electrodes may be a CCP electrode. In at least one embodiment, the CCP electrode may be a metal body within the plasma chamber 102, where the CCP electrode is in direct contact with the plasma (e.g., plasma 108). In at least one embodiment, the second electrode of the pair of electrodes may be, for example, the chuck 106. In at least one embodiment, the plasma may be generated between the CCP electrode and the chuck 106. In at least one embodiment, the wafer 104 is placed on the chuck 106 as shown in the figure. In at least one embodiment, the chuck 106 may be grounded or biased within the CCP system. In at least one embodiment, the bias may be DC or RF. In at least one embodiment, when the RF source 126 is coupled to a low-pass filter, it can supply a low-frequency RF bias to the chuck 106. The RF signal source 128 can supply a primary high-frequency RF coupled to the plasma 108. In at least one embodiment, the electrode is a gas distribution manifold (e.g., a heated showerhead) disposed above the wafer 104 supported on the chuck 106. In at least one embodiment, the frequency difference between the RF signal sources 126 and 128 may be substantial, for example, having a separation of 10:1 or more.

[0081] In at least one embodiment, during operation, plasma 108 is formed above wafer 104 and chuck 106. An RF magnetic field passing through plasma chamber 102 can generate a plasma current that oscillates at the same frequency as the RF current flowing in power supply network 114. In at least one embodiment, the RF current can have peak values in the tens to hundreds of amperes. In at least one embodiment, sensor 140 may be coupled to any suitable node in RF power supply network 114 to measure voltage and current. In at least one embodiment, sensor 140 may be an RF current and / or voltage measurement sensor (e.g., a V, I sensor), a vector network sensor, an impedance sensor, etc. In at least one embodiment, sensor 140 may be a V, I sensor coupled to RF power supply network 114 at node 142 between components 120 and 122 to measure both RF voltage and current, as shown in the figure. In at least one embodiment, sensor 140 may be interfaced to a circuit that enables connection to processor 144. In at least one embodiment, sensor 140 may supply a digitized output stream to processor 144, and the output stream may be read and analyzed by software code stored in memory 146 coupled to processor 144. In at least one embodiment, memory 146 may be a machine-readable storage medium such as non-volatile solid-state memory, a hard disk magnetic drive, an optical drive, and other suitable storage formats. In at least one embodiment, memory 146 may store a computer program containing machine-executable instructions. In at least one embodiment, processor 144 may be part of a control circuit for plasma processing tool 100 coupled locally or remotely through a network.

[0082] In at least one embodiment, processor 144 may execute software code comprising routines for calculating the voltage and current at each node in RF power supply network 114 based only on the voltage and / or current read at a single node 142. In at least one embodiment, the software routine stored in memory 146 may comprise instructions according to the method embodiments described in this disclosure. In at least one embodiment, the calculated current and / or voltage may be converted into power dissipated as heat within individual components (e.g., components 116-122). In at least one embodiment, the derived power amount may be inserted into a heat equation included within the software code stored in memory 146, thereby determining the calculated temperature of a component or individual circuit elements within an individual component. In at least one embodiment, a series of calculations may be made for selected components or their circuit elements, for example, if they are identified as being temperature sensitive. In at least one embodiment, processor 144 is also coupled to RF signal sources 126 and 128, as shown in the figure. In at least one embodiment, processor 144 may communicate with RF signal sources 126 and 128 to control the output power and / or duty cycle, for example, in response to a detected overheat condition. Control instructions are described in more detail below.

[0083] FIG. 2 is a diagram showing a method for obtaining component temperatures within an RF power supply network 200 having cascaded components, according to at least one embodiment. Voltage and current conditions at each node are shown. In FIG. 2, a portion of an RF power supply network 200 having components 202, 204, and 206 is shown, according to at least one embodiment. Components 202, 204, and 206 are labeled as component N-1, component N, and component N+1, respectively. In at least one embodiment, components 202-206 are part of a larger RF power supply network 200 that includes a preceding portion and a succeeding portion. In at least one embodiment, the preceding portion may include a plurality of upstream components (e.g., components labeled 1, 2... N-2). In at least one embodiment, the succeeding portion may include a plurality of downstream components (e.g., components labeled N+2, N+3, etc.).

[0084] In at least one embodiment, adjacent upstream and downstream components are coupled by a node. In at least one embodiment, node 210 couples component 202 to component 204, and node 212 couples component 204 to component 206. In at least one embodiment, nodes 208 and 214 are terminal nodes. In at least one embodiment, terminal nodes 208 and 214 appear to be open ends in the drawing, but it is understood that node 208 is also coupled to an adjacent upstream component N-2 (not shown), and node 214 is coupled to an adjacent downstream component N+2 (also not shown).

[0085] In at least one embodiment, the individual components within the RF power supply network 200 may be represented as two-port networks having an input port and an output port. In at least one embodiment, component 202 includes an input port 216 and an output port 218. Each of the individual nodes 208-214 is bounded by the output port of the upstream component and the input port of the adjacent downstream component. In at least one embodiment, node 210 is bounded by the output port 218 of component 202 and the input port 220 of component 204, and node 212 is bounded by the output port 222 of component 204 and the input port 224 of component 206. In at least one embodiment, a port includes two terminals. In at least one embodiment, the input ports 216, 220, 224 may be characterized by an input voltage V in and an input current I in . In at least one embodiment, for the individual ports 216, 220, and 224, the input voltages are indicated by V N-1in , VN in , and V N+1in , respectively. In at least one embodiment, the numbers follow the position of the components within the component chain. For example, V N-1in corresponds to component N-1, and so on. In at least one embodiment, the output ports 218, 222, and 226 may be similarly characterized by an indication of an output voltage and an output current. In at least one embodiment, the nodes 208, 210, 212, and 214 may also be characterized by a node voltage and a node current. In at least one embodiment, node 210 may be characterized by a node voltage V N and a node current i N , where the subscript N refers to the downstream component (e.g., component 204).

[0086] In at least one embodiment, similarly, the node 212 between components N and N+1 (204 and 206, respectively) is V N+1 and i N+1Characterized by, etc. In at least one embodiment, within each individual node, the output impedance Z of the upstream component out is matched to the input impedance Z of the downstream component in When (e.g., Z out = V / i = Z i n), the upstream output voltage and output current can be substantially equal to the downstream input voltage and input current. In at least one embodiment, when an impedance mismatch occurs downstream within the component chain of the RF power supply network 200, the Z of the downstream component in can vary significantly with respect to the Z of the upstream component out In at least one embodiment, when the plasma impedance Z p oscillates and is no longer matched by the matching network, an impedance mismatch condition occurs at the load end of the RF power supply network 200. In at least one embodiment, the impedance mismatch can propagate through the component chain and cause impedance mismatches at each node within the component chain. In at least one embodiment, V at the output port 218 of component 202 N-1out and i N-1out are substantially equal to V at the input port 220 of component 204 N=1out = Z Nin At this time, and I at the input port 220 of component 204 Nin and I Nin are substantially equal. In at least one embodiment, when Z N=1out ≠ Z Nin at this time, the equivalence between the output and input voltages and currents no longer holds. In at least one embodiment, reflections of voltage waves and current waves can occur at node boundaries.

[0087] In at least one embodiment, due to the impedance mismatch condition, the output ports 218 and 222 can experience a mismatched Z in towards the adjacent input ports 220 and 224. In at least one embodiment, this condition propagates through the component chain (where the Z of each component inAlso, it terminates at any RF signal source (e.g., RF signal sources 126 and / or 128 shown in FIG. 1) that appears to change in view of the adjacent component upstream thereof. In at least one embodiment, power is also reflected by each mismatch node and can cause an increase in current draw in some or all of the components within the RF power supply network 200. In at least one embodiment, the current draw by some components increases beyond the rated limit and can potentially cause overheating of the individual circuit elements within the individual components. In at least one embodiment, component 204 may comprise an LC filter circuit including capacitors and inductors. In at least one embodiment, at normal current levels, one or both of the circuit elements can dissipate heat, but at excessive current, overheating of one or both of the circuit elements can occur. In at least one embodiment, the circuit element can have a maximum temperature rating. Exceeding the maximum temperature rating can damage or destroy the circuit element.

[0088] In at least one embodiment, a method for obtaining the temperatures of components 202, 204, and 206 for the protection of temperature-sensitive components or circuit elements within some or all of the components is shown by FIG. 2. In at least one embodiment, a sensor 228 (e.g., sensor 140 of FIG. 1, etc.) for measuring RF current and voltage may be coupled to any node within the RF power supply network 200. In at least one embodiment, sensor 228 is coupled to node 212 between components 204 and 206 (e.g., components N and N + 1). In at least one embodiment, sensor 228 may continuously measure the node voltage and node current V N+1 and i N+1 and. In at least one embodiment, when measured, the values of V N+1 and i N+1 may be continuously read by processor 230. In at least one embodiment, processor 230 uses mathematical transformations using transfer functions and / or transfer matrices to determine the values of V and i at other nodes (e.g., V at nodes 208, 210, 214 respectively, and i)N-1 , i N-1 , V N , i N , V N+2 , i N+2 ) may be calculated. In at least one embodiment, the transfer matrix includes a set of interdependent linear equations in the form of a matrix for calculating, for example, a first voltage and a first current at a first node from a second voltage and a second current at a second node. In at least one embodiment, the second voltage and the second current may be measured or calculated.

[0089] In at least one embodiment, the second voltage and the second current may be linearly combined by matrix coefficients. In at least one embodiment, the matrix coefficients convert the second voltage and the second current into the first voltage and the second current. In at least one embodiment, the matrix coefficients may be transfer functions for converting the second voltage and the second current into the first voltage and for converting the second voltage and the second current into the first current. In at least one embodiment, the transfer matrix may be encoded into machine-readable instructions that may be stored in a memory 232 coupled to a processor 230. In at least one embodiment, the transfer matrix may be used to convert voltages and currents measured at node 212 into voltage and current values at node 210. In at least one embodiment, an example of a transfer matrix for a two-port electrical network may have a form given by Equation [1].

Equation

[0090] In at least one embodiment, the transfer matrix may be cascaded to calculate the voltage and current at nodes upstream and downstream of node 212 along the component chain of RF power supply network 200.

[0091] In at least one embodiment, the calculation of the nodes based on the cascaded transfer matrix may have the form given by Equation [2].

Equation

[0092] In at least one embodiment, Equation [2] may be encoded in software stored in memory 232 and numerically solved. In at least one embodiment, coefficients A, B, C, and D may be predetermined for some or all of the components or for circuit elements sensitive to a selected temperature. In at least one embodiment, processor 230 may read sensor 228 at predetermined time intervals. In at least one embodiment, sensor 228 is coupled to node 212 and measures the values of V N+1 and i N+1 In at least one embodiment, processor 230 may calculate the values of the voltage and current V N+1 and I N+1 at node 210 by conversion of the V N and I N measured at node 208. In at least one embodiment, the values of the input voltage and current at other nodes 208, 210, and 214 may be determined.

[0093] In at least one embodiment, i in N+1 is measured, and when i inN and i inN+1 are calculated based on i in N+1 , the power dissipation in the individual components 202, 204, and 206 is determined, for example, from the calculated values of i inN-1 and i inN . In at least one embodiment, knowledge of the circuit topology of the individual circuit elements (capacitors and inductors) as well as the dielectric losses and series resistance losses may be invoked. In at least one embodiment, based on the calculated node currents, for example, the heat generated by the Joule heating (I 2 R) losses for each component may be calculated. Here, for example, knowledge of the parameters of the series resistance and dielectric losses of the inductors and capacitors may be used.

[0094] In at least one embodiment, due to excessive Joule heating due to I 2 R losses (where I may include excessive input current to the component), temperature changes may occur within each component. R may represent the series resistance or dielectric losses. In at least one embodiment, the temperature rise within the individual components may be determined by numerical calculations executed by the processor 230. In at least one embodiment, the processor 230 may execute software instructions stored in the memory 232 to calculate a pseudo-instantaneous temperature, for example, for input into a numerical heat conduction differential equation. In at least one embodiment, such a numerical heat conduction differential equation may have the form of Equation [3].

Number

[0095] FIG. 3 shows a method 300 for obtaining thermal constants of electrical components in a power supply network (e.g., power supply network 114 or 200) according to at least one embodiment. In at least one embodiment, various blocks or operations may be performed by hardware, software, or a combination of both. Method 300 provides thermal protection for temperature-sensitive components within a power supply network according to at least one embodiment. In at least one embodiment, method 300 may be performed by a digital processor executing machine-executable instructions within a computer program stored in a memory coupled to the processor, according to some embodiments. In at least one embodiment, the thermal characteristics of a component under test used in an RF power supply network (such as RF power supply network 114 shown in FIG. 1 or RF power supply network 200 shown in FIG. 2) may be determined empirically. In at least one embodiment, the component under test is subjected to actual power supply conditions that may be expected during actual use of the power supply network. In at least one embodiment, the method shows operations that may be utilized to obtain thermal characteristics (such as thermal constants k1 and k2 of the component under test). In at least one embodiment, the component under test may be an actual component used in an RF power supply network.

[0096] In at least one embodiment, in operation 301, an RF current may be generated by an RF signal source (such as RF signal source 126 or 128), and the RF signal source is coupled to the component under test. In at least one embodiment, the RF current may flow through the component under test. In at least one embodiment, the component under test may comprise a combination of passive circuit elements or a single circuit element. In at least one embodiment, the circuit elements may include passive elements such as, but not limited to, capacitors, inductors, transformers, resistors, directional couplers, power splitters and combiners, switches, and transmission lines. In at least one embodiment, the RF current is I 2It may be selected to have an RMS value that heats the component by Joule heating, which is quantified as R heating. In at least one embodiment, the quantity R may be a series resistance equivalent to the component and may contribute to the dissipation loss in the component. In at least one embodiment, the current I may be an RMS RF current value, and that current value is the same quantity of I in the component. 2 It is substantially numerically equivalent to the DC current passing through the same component that causes R heating. In at least one embodiment, a sinusoidal RF current with a peak amplitude of 1 ampere has an RMS value of approximately I = 0.7 amperes, which is I. 2 It is equivalent to I = 0.7 ampere DC in terms of R heating. In at least one embodiment, the RF current may be supplied in bursts controlled by a certain duty cycle, where the RF current is switched on and off periodically, as opposed to a continuous supply of RF current that can be controlled by adjusting the peak amplitude. In at least one embodiment, for an RF current controlled by a duty cycle, the relevant parameters may be the length of the duty cycle period, as well as the ratio of the on-time and off-time within the duty cycle period.

[0097] In at least one embodiment, the duty cycle period may be the sum of the on-time phase and off-time phase of the duty cycle. In at least one embodiment, by managing the RF current as a controlled burst or pulse, the average RF current supplied to the component under test may be adjusted by adjusting the duration of the on-time and off-time of the duty cycle. In at least one embodiment, the temperature rise within the component under test may be proportional to the average RF current when pulsed, rather than the peak RF current. In at least one embodiment, the peak RF current may remain constant, which means that the peak power supplied to the plasma is the desired plasma characteristic (electron density n). eIt is possible to increase it to the extent required to maintain (such as). In at least one embodiment, the on-time phase and off-time phase of the duty cycle may be measured on a time scale of seconds. Both parameters may be optimized.

[0098] In at least one embodiment, passing RF current in bursts can limit the time that components are exposed to Joule heating while providing the maximum peak power supply to the plasma. In at least one embodiment, the peak power may be maintained, for example, to create a desired electron density in the plasma. In at least one embodiment, the components may support peak current values significantly exceeding the manufacturer's ratings for a short period of time. In at least one embodiment, adjusting the on-time of the duty cycle can allow the temperature transients that occur during the current burst to be mitigated and allow the component under test to cool between current bursts. In at least one embodiment, during operation 301, the component is allowed to heat to a high temperature by passing current for a set period of time.

[0099] In at least one embodiment, in operations 302 and 303, the current is stopped and the component under test is allowed to cool. In at least one embodiment, during the cooling phase, the decreasing temperature of the component under test may be recorded by a temperature sensor. In at least one embodiment, a thermocouple, an infrared camera, a resistance temperature detector (RTD), a Peltier element, etc. may be used as a temperature probe to obtain an accurate temperature measurement of the component. In at least one embodiment, the decreasing temperature-time profile of the component under test may be specific to the geometry of the component under test, the local environment of the enclosure around the component under test and nearby objects including any insulators, and the exposure to natural and forced convection. In at least one embodiment, the temperature may be measured by periodically reading a temperature probe or a set of probes. For example, a microprocessor may read the temperature probe at appropriate time intervals and store the readings in a memory buffer.

[0100] In at least one embodiment, in operation 304, a set of recorded temperature data may be subjected to a fitting routine to determine the thermal constants k1 and k2. In at least one embodiment, appropriate methods may be used, such as finite elements for two-dimensional and three-dimensional analysis, time increments in one-dimensional and two-dimensional analysis, etc. In at least one embodiment, a set of recorded temperatures may be numerically fitted to a heat transfer equation similar to Equation [3].

[0101] In at least one embodiment, heat constants k1 and k2 may be calculated for the components under test by numerically solving the heat transfer equation. In at least one embodiment, method 300 may be repeated for some or all of the components within an RF power supply network similar to the RF power supply network 114 of FIG. 1. In at least one embodiment, all of the components within a particular RF power supply network may be evaluated by method 300, or selected components exhibiting temperature sensitivity may be so evaluated. In at least one embodiment, once the values of k1 and k2 are determined for the component of interest, they may be applied to the temperature calculation based on Equation [3] as described for FIGS. 2 and FIG. 4 below.

[0102] FIG. 4 shows a method 400 for determining the temperatures of a plurality of components within a power supply network (such as the power supply network 114 shown in FIG. 1) according to at least one embodiment. In at least one embodiment, the operations of method 400 may be performed by software, hardware, or a combination thereof. In at least one embodiment, method 400 protects temperature-sensitive circuit elements and components from overheating. In at least one embodiment, the thermal characteristics of the components used in the power supply network may be determined empirically as shown in and described above with respect to FIG. 3. In at least one embodiment, method 400 may be similar to the description regarding FIG. 2. In at least one embodiment, method 400 shows operations 401-404 that may be used to convert the current and voltage measured at a single node within the power supply network to voltages and currents at some or all of the power supply network and to calculate the temperature of the components. In at least one embodiment, the temperature calculation may be based on the individual component heat constants k1 and k2 obtained by the method 300 described above.

[0103] In at least one embodiment, in operation 401, RF voltage and current are measured at a single node within the power supply network by a sensor (such as sensor 140 shown in FIG. 1) for measuring RF voltage and current. In at least one embodiment, the sensor may be an RF current-voltage probe (such as sensor 228 shown in FIG. 2), a vector network analyzer, an impedance analyzer, etc. In at least one embodiment, the relevant data may include instantaneous RF voltage, RF current, and optionally the phase angle between the RF voltage and the RF current. In at least one embodiment, a vector network analyzer or an impedance analyzer may automatically measure all three parameters. In at least one embodiment, the phase angle may be necessary for calculating the complex impedance of the input and output ports of the component. In at least one embodiment, finally, the current and / or voltage at the measurement node is converted into the voltage, current, and optionally complex impedance at some or all of the nodes within the power supply network.

[0104] In at least one embodiment, the measurement may be performed sequentially by a microprocessor (such as microprocessor 144 shown in FIG. 1) reading the sensor at programmed time intervals. In at least one embodiment, the microprocessor may execute software instructions stored in a memory (such as memory 146 shown in FIG. 1) coupled to the microprocessor. In at least one embodiment, the instructions may be included within a software loop such that the measurement can be performed at consistent time intervals. In at least one embodiment, the read data may be stored in a buffer.

[0105] In at least one embodiment, at operation 402, a sensor coupled to a single node within an RF power network may measure the input voltage and current of a downstream component coupled to the same node. In at least one embodiment, the measured voltage, current, and optionally phase angle may be numerically transformed by a processor into voltages and currents at nodes upstream and downstream of the measurement node. In at least one embodiment, the numerical transformation may be performed by a subroutine included within software that includes machine-readable instructions for calculating a [V, I] vector for individual nodes (e.g., nodes 208, 210, 214 shown in FIG. 2) by digital manipulation of Equation [2]. In at least one embodiment, Equation [2] incorporates a transmission matrix for a two-port network similar to that shown above. In at least one embodiment, matrix coefficients (such as the A, B, C, and D coefficients described above) may be empirically determined or may be known for individual components of the RF power transmission network. In at least one embodiment, the voltages and currents at the upstream and downstream nodes may be packaged into a calculated [V, I] vector and may be considered equivalent to the input voltage and current to the associated individual component.

[0106] In at least one embodiment, at operation 403, the input current and / or voltage of a first component (e.g., component N) calculated from the transformation of the measurement data performed at operation 402 may be converted into power dissipation by joule heating. In at least one embodiment, the input current i Nin to component N may be inserted into a calculation including i 2 Nin R to obtain power loss by joule heating. In at least one embodiment, the input voltage V Nin may be similarly used by calculating V 2 Nin / R. In at least one embodiment, the parameter R may be the total series resistance associated with circuit elements within the component.

[0107] In at least one embodiment, the temperature of the first component is I 2 It may be determined by inserting the R data or simply the input current to the first component into Equation [3]. In at least one embodiment, the thermal constants k1 and k2 may be determined empirically by a prior execution of method 300. Referring again to FIG. 4, by numerically solving Equation [3], in at least one embodiment, the calculated time-dependent temperature T(t) may be compared to a maximum temperature limit to determine whether it has exceeded the limit. In at least one embodiment, the maximum temperature limit may be obtained from the manufacturer of one or more temperature-sensitive circuit elements within the component. In at least one embodiment, if it is exceeded, the software may include instructions for monitoring the overheated state by setting an alarm so that the user takes avoidance actions to notice the overheated state and lower the temperature of the component.

[0108] In at least one embodiment, the avoidance action may be a reduction of the entire duty cycle period and / or a reduction of the on-time phase of the duty cycle. Such an action may allow the component to cool to some extent, where the transient temperature can relax to a temperature lower than the limit. In at least one embodiment, the operation of the duty cycle may allow the peak power to remain high when it is necessary to maintain a desired / target electron density (at least 10 10 / cm 3 of n e etc.) within the plasma.

[0109] In at least one embodiment, in operation 404, the process described for operation 403 may be repeated for a second component (e.g., component N-1) within the power supply network. In at least one embodiment, the calculated time-dependent temperature of the second component may be compared to the maximum temperature limit of one or more temperature-sensitive circuit elements of the second component. In at least one embodiment, improvement measures for a similar overheated state as for the first component may be taken for the second component as described for operation 403.

[0110] Method 400 can describe measurements, conversions, and processes for temperature calculation and overheat condition improvement for two components in a power supply network, and this process may be repeated to calculate the temperatures of some or all of the remaining components in the same power supply network according to at least one embodiment. As a result, overheat conditions that may occur in any one component in the power supply network can be avoided or quickly improved.

[0111] FIG. 5 shows a plot 500 of measured and calculated temperatures over time for an example component used in a power distribution network (such as power supply network 114) according to at least one embodiment. In at least one embodiment, the example component may be individual passive circuit elements such as capacitors, inductors, resistors, switches, transmission lines, etc. In at least one embodiment, the component may be a combination of individual passive elements such as an LC filter or an impedance matching circuit network. Plot 500 shows a comparison of a calculated temperature-time profile (curve 502) and a measured temperature-time profile (curve 504) displayed over a certain time interval according to at least one embodiment. Curve 502 is represented by a dashed line so as to be easily distinguishable from curve 504 represented by a solid line. In at least one embodiment, the calculated temperature-time profile may be based on the methods described with respect to FIGS. 2, 3, and 4.

[0112] Referring again to FIG. 5, plot example 500 shows that, according to at least one embodiment, by applying the method described above, the calculated temperature-time profile substantially follows the measured temperature-time profile. In at least one embodiment, the RF current level is also shown in plot 500 as a series of current bursts or pulses, shown as pulse train 506. In at least one embodiment, the current pulse duration can be based on an on-time phase spaced by a constant duty cycle period. In at least one embodiment, the pulse duration can be governed by a substantially constant duty cycle. In plot example 500, the current pulses include a small current pulse 510 after a large current pulse 508, according to at least one embodiment. Plot 500 shows an initial sharp temperature rise within region 512, where the RF current is continuous. Region 514 follows region 512. In region 514, the on and off periods of current pulse train 506 remain the same as in region 512. In at least one embodiment, the current peak has a lower magnitude, enabling a steady state to occur in both the measured and calculated temperature-time profiles. In at least one embodiment, the duration of the burst (e.g., the width of current pulses 508 and 510) can correspond to the on-time phase of the duty cycle and can be, for example, 10 to 20 seconds. In at least one embodiment, in region 516, the magnitudes of current pulses 508 and 510 substantially increase to the level in region 512. In at least one embodiment, both the measured and calculated temperature-time profiles react by rising. In at least one embodiment, in region 518, the current pulse train is stopped and the temperature monotonically decreases. Calculated curve 504 exactly follows measured curve 502.

[0113] FIG. 6 shows a processor system 600 including a machine-readable storage medium having machine-readable instructions that, when executed, cause a microcontroller (e.g., processor 144 of FIG. 1 or processor 230 of FIG. 2) within a circuit board of a control unit for plasma processing tool 100 to execute the machine-readable instructions according to method 400. In at least one embodiment, the microcontroller may measure and report voltage and / or current at nodes within RF power delivery network 114 that couples RF signal sources 126 and 128 to plasma chamber 102. In at least one embodiment, the processing may be stored as computer-executable instructions on a machine-readable medium (e.g., 603). In at least one embodiment, the machine-readable medium may be, for example, memory 146 of FIG. 1 or memory 232 of FIG. 2. In at least one embodiment, processor system 600 includes a memory 601 coupled as shown, a processor 602, a machine-readable storage medium 603 (also referred to as a tangible machine-readable medium), a communication interface 604 (e.g., a wireless or wired interface), and a network bus 605. In at least one embodiment, processor 602 may be processor 144 of FIG. 1.

[0114] In at least one embodiment, processor 602 is a digital signal processor (DSP), an application specific integrated circuit (ASIC), a general purpose central processing unit (CPU), or low-power logic implementing a simple finite state machine for performing the various processes described herein.

[0115] In at least one embodiment, various logic blocks of the processor system 600 are coupled to each other via a network bus 605. Any suitable protocol may be used to implement the network bus 605. In at least one embodiment, the machine-readable storage medium 603 includes instructions (also referred to as program software code / instructions) for measuring voltage and current, converting the measured voltage and current, and calculating temperature, as described above with reference to various embodiments.

[0116] In at least one embodiment, the machine-readable storage medium 603 is a machine-readable storage medium comprising instructions for measuring current and voltage at nodes between components within an RF power supply network (e.g., the RF power supply network 114 of FIG. 1). In at least one embodiment, the machine-readable storage medium 603 (e.g., the memory 146 of FIG. 1) has machine-readable instructions that, when executed, cause the processor 602 to execute a method with reference to various embodiments.

[0117] In at least one embodiment, the program software code / instructions associated with various embodiments may be implemented as part of an operating system or a particular application, a component, a program, an object, a module, a routine, or other instruction sequence or organized instruction sequence, referred to as "program software code / instructions", "operating system program software code / instructions", "application program software code / instructions", or simply "software" or firmware embedded in the processor. In at least one embodiment, the program software code / instructions may be executed by the processor system 600.

[0118] In at least one embodiment, the machine-readable storage medium 603 is a computer-executable storage medium. In at least one embodiment, the program software code / instructions associated with the various embodiments are stored in the computer-executable storage medium 603 and executed by the processor 602. Here, the computer-executable storage medium 603 is a tangible machine-readable medium 603 that can be used to store program software code / instructions and data that cause one or more processors (e.g., processor 602) to execute processing when executed by a computer device.

[0119] In at least one embodiment, the tangible machine-readable medium 603 may comprise storage of executable software program code / instructions and data at various tangible locations such as, for example, ROM, volatile RAM, non-volatile memory, and / or cache, and / or other tangible memory referenced in this application. In at least one embodiment, portions of this program software code / instructions and / or data may be stored in any one of these storage and memory devices. In at least one embodiment, the program software code / instructions may be obtained from other storage through, for example, a central server or a peer-to-peer network including the Internet. In at least one embodiment, different portions of the software program code / instructions and data may be obtained at different times in different communication sessions or in the same communication session.

[0120] In at least one embodiment, software program code / instructions related to various embodiments may be retrieved in their entirety before the execution of each software program or application. In at least one embodiment, alternatively, some of the software program code / instructions and data may be retrieved dynamically (e.g., just-in-time) when needed for execution. In at least one embodiment, alternatively, some combination of these ways of retrieving software program code / instructions and data may be implemented for, e.g., different applications, components, programs, objects, modules, routines, or other instruction sequences or organized instruction sequences. In at least one embodiment, it may not be necessary for data and instructions to be entirely on a tangible machine-readable medium 603 at a particular time.

[0121] In at least one embodiment, the tangible machine-readable medium 603 includes, but is not limited to, recordable and non-recordable types of media such as, in particular, volatile and non-volatile memory devices, read-only memory (ROM), random access memory (RAM), flash memory devices, floppy and other removable disks, magnetic storage media, optical storage media (compact disc read-only memory (CD ROM), digital versatile disc (DVD), etc.). In at least one embodiment, software program code / instructions may be temporarily stored in a digital tangible communication link while being propagated in electrical, optical, acoustic, or other forms as signals (carrier waves, infrared signals, digital signals, etc.) through the tangible communication link.

[0122] Examples for explaining various embodiments are provided below. These examples can be combined with other examples. Thus, various embodiments can be combined with other embodiments without changing the scope of the present invention.

[0123] Example 1 is a method for measuring temperature, comprising supplying a high-frequency (RF) current to an RF power supply network, the RF power supply network comprising at least a first component coupled to a second component, the first component comprising a first node, the second component comprising a second node, the second node interconnecting the first component and the second component, measuring a first voltage and a first current at the first node, calculating a second voltage and a second current at the second node based on the measurement of the first voltage and the measurement of the first current, and calculating a first temperature of the first component and a second temperature of the second component, the first temperature being a function of the first current and the second temperature being a function of the second current.

[0124] Example 2 is a method according to any example herein (in particular, Example 1), wherein calculating the second voltage and the second current comprises converting the first voltage to the second voltage and the first current to the second current based on a first transfer matrix.

[0125] Example 3 is a method according to any example herein (in particular, Example 2), further comprising determining a third voltage and a third current, wherein the second voltage is converted to the third voltage and the second current is converted to the third current based on a second transfer matrix.

[0126] Example 4 is a method according to any example herein (in particular, Example 2), further comprising converting the first current to a first dissipated power of the first component and converting the second current to a second dissipated power of the second component.

[0127] Example 5 is a method according to any example herein (in particular, Example 4), wherein calculating the first temperature of the first component comprises calculating a first integral of the first dissipated power over a time interval.

[0128] Example 6 is a method according to any example herein (in particular, Example 5), wherein calculating the second temperature of the second component comprises calculating a second integral of the second dissipated power over a time interval and multiplying the second integral by a second thermal constant of the second component.

[0129] Example 7 is a method of any example (in particular, Example 6) of this specification, further comprising comparing a first temperature with a first temperature limit of a first component and comparing a second temperature with a second temperature limit of a second component.

[0130] Example 8 is a method of any example (in particular, Example 7) of this specification, further comprising adjusting a duty cycle of an RF current coupled to an RF power supply network when at least the first temperature exceeds the first temperature limit or at least the second temperature exceeds the second temperature limit.

[0131] Example 9 is a method of any example (in particular, Example 2) of this specification, wherein measuring the first voltage and the first current includes measuring a phase angle between the first current and the first voltage.

[0132] Example 10 is a method of any example (in particular, Example 9) of this specification, wherein the first output impedance of the first component is determined from the first voltage, the first current, and the phase angle between the first current and the first voltage.

[0133] Example 11 is a machine-readable storage medium comprising a computer program for thermally protecting an electronic circuit, the electronic circuit comprising at least a first component and a second component, the computer program including machine-executable instructions that, when executed by one or more machines, cause the one or more machines to execute a method, the method comprising measuring a first input voltage and a first input current of the first component, calculating a second input voltage and a second input current of the second component, and calculating a first temperature of the first component and a second temperature of the second component, the first temperature being a function of the first input current and the second temperature being a function of the second input current.

[0134] Example 12 is a machine-readable storage medium of any example (in particular, Example 11) of this specification, the method further comprising comparing the first temperature with a first temperature limit and comparing the second temperature with a second temperature limit.

[0135] Example 13 is a machine-readable storage medium of any example in this specification (particularly, Example 12), wherein the method further comprises adjusting a duty cycle of an RF current when at least a first temperature exceeds a first temperature limit or at least a second temperature exceeds a second temperature limit.

[0136] Example 14 is a system comprising: a plasma chamber having a plasma coupling interface; a radio frequency (RF) signal source coupled to the plasma coupling interface through an RF power supply network, the RF power supply network comprising a plurality of components, a sensor coupled to a first component among the plurality of components for measuring a first voltage across the first component and a first current through the first component; and a processor coupled to the sensor for determining a second voltage across a second component among the plurality of components and a second current through the second component, and for determining a first temperature at the first component and a second temperature at the second component.

[0137] Example 15 is a system of any example in this specification (particularly, Example 14), wherein the processor determines the second voltage and the second current based on the first voltage and the first current.

[0138] Example 16 is a system of any example in this specification (particularly, Example 15), wherein the processor determines the second voltage and the second current based on a transfer matrix.

[0139] Example 17 is a system of any example in this specification (particularly, Example 14), wherein the plasma coupling interface comprises an inductively coupled plasma (ICP) antenna, and the ICP antenna inductively couples to the plasma in the plasma chamber.

[0140] Example 18 is a system of any example in this specification (in particular, Example 14), wherein the plasma coupling interface is a capacitively coupled plasma (CCP) electrode, and the CCP electrode capacitively couples to the plasma in the plasma chamber.

[0141] Example 19 is a system of any example in this specification (in particular, Example 18), wherein the CCP electrode is a gas distribution manifold, and the gas distribution manifold capacitively couples to the plasma in the plasma chamber.

[0142] In addition to what is described herein, various modifications may be made to the disclosed implementation examples without departing from their scope. Accordingly, the description of the examples herein is to be construed as illustrative only and not as limiting the scope of the present disclosure. The scope of the present invention should be evaluated only by reference to the following claims.

Claims

1. A method for measuring temperature, comprising: applying a high-frequency (RF) current to an RF power supply network, wherein the RF power supply network comprises at least a first component coupled to a second component, the first component comprising a first node, the second component comprising a second node, the second node interconnecting the first component and the second component, the method further comprising: measuring a first voltage and a first current at the first node, calculating a second voltage and a second current at the second node based on the measurement of the first voltage and the measurement of the first current, calculating a first temperature of the first component and a second temperature of the second component, the first temperature being a function of the first current and the second temperature being a function of the second current.

2. The method according to claim 1, wherein calculating the second voltage and the second current comprises converting the first voltage to the second voltage and converting the first current to the second current based on a first transfer matrix.

3. The method according to claim 2, further comprising determining a third voltage and a third current, wherein the second voltage is converted to the third voltage and the second current is converted to the third current based on a second transfer matrix.

4. The method according to claim 2, further comprising: converting the first current to a first dissipated power of the first component and converting the second current to a second dissipated power of the second component.

5. The method according to claim 4, wherein calculating the first temperature of the first component comprises calculating a first integral of the first dissipated power over a certain time interval.

6. The method according to claim 5, wherein calculating the second temperature of the second component comprises: calculating a second integral of the second dissipated power over the time interval, and multiplying the second integral by a second thermal constant of the second component.

7. The method according to claim 6, further comprising comparing the first temperature with a first temperature limit of the first component and comparing the second temperature with a second temperature limit of the second component.

8. The method according to claim 7, further comprising adjusting a duty cycle of the RF current coupled to the RF power supply network when at least the first temperature exceeds the first temperature limit or at least the second temperature exceeds the second temperature limit.

9. The method according to claim 2, wherein measuring the first voltage and the first current comprises measuring a phase angle between the first current and the first voltage.

10. The method according to claim 9, wherein a first output impedance of the first component is determined from the first voltage, the first current, and the phase angle between the first current and the first voltage.

11. A machine-readable storage medium, comprising a computer program for thermally protecting an electronic circuit, the electronic circuit comprising at least a first component and a second component, the computer program including machine-executable instructions that cause one or more machines to perform a method when executed by the one or more machines, The method comprises, measuring a first input voltage and a first input current of the first component, calculating a second input voltage and a second input current of the second component, calculating a first temperature of the first component and a second temperature of the second component, the first temperature being a function of the first input current and the second temperature being a function of the second input current.

12. The machine-readable storage medium according to claim 11, wherein the method further comprises comparing the first temperature with a first temperature limit and comparing the second temperature with a second temperature limit.

13. The machine-readable storage medium according to claim 12, wherein the method further comprises adjusting a duty cycle of an RF current when at least the first temperature exceeds the first temperature limit or at least the second temperature exceeds the second temperature limit.

14. A system, a plasma chamber having a plasma coupling interface, a radio frequency (RF) signal source coupled to the plasma coupling interface through an RF power supply network, the RF power supply network comprising a plurality of components, A sensor coupled to a first component of the plurality of components, the sensor measuring a first voltage at both ends of the first component and a first current flowing through the first component; A processor coupled to the sensor, the processor determining a second voltage at both ends of a second component of the plurality of components and a second current passing through the second component, and determining a first temperature in the first component and a second temperature in the second component; A system comprising the above.

15. The system according to claim 14, wherein the processor determines the second voltage and the second current based on the first voltage and the first current.

16. The system according to claim 15, wherein the processor determines the second voltage and the second current based on a transfer matrix.

17. The system according to claim 14, wherein the plasma coupling interface comprises an inductively coupled plasma (ICP) antenna, and the ICP antenna inductively couples to the plasma in the plasma chamber.

18. The system according to claim 14, wherein the plasma coupling interface is a capacitively coupled plasma (CCP) electrode, and the CCP electrode capacitively couples to the plasma in the plasma chamber.

19. The system according to claim 18, wherein the CCP electrode is a gas distribution manifold, and the gas distribution manifold capacitively couples to the plasma in the plasma chamber.

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