PACKAGING FOR A SENSOR AND METHOD FOR MANUFACTURING SAME - Patent application

Abstract

Disclosed herein are embodiments of a sensor assembly, a method of manufacturing the sensor assembly, and a method of using the sensor assembly. In one embodiment, the sensor assembly comprises a substrate comprising an outer region, an inner region, and a middle region disposed between the outer region and the inner region, the substrate further comprising an electrical contact pad on at least the inner region. The sensor assembly further comprises a housing coupled to the substrate at the outer region or the middle region to form a hermetic seal. The sensor assembly further comprises a sensor device coupled to the substrate via the electrical contact pad at the inner region. In certain embodiments, the sensor assembly further comprises a conformal coating deposited on at least a portion of the sensor assembly.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to sensors for monitoring and controlling, for example, gas flow rates. [Background technology]

[0002] Various manufacturing systems (e.g., for semiconductor applications) may involve measuring gas flow characteristics (e.g., flow rate, temperature, pressure, etc.). Sensors used to make such measurements may not be compatible with aggressive environments that may be used in a particular manufacturing system (e.g., corrosive environments, environments with high-energy plasma, environments with vacuum, and environments with high temperatures and / or frequent temperature cycling, etc.). Creating sensors and / or sensor packaging with specialized geometries that do not adversely affect the properties of the process gases while being compatible with a particular aggressive environment can present a challenge.

[0003] For example, in some manufacturing systems, process gases (e.g., gases used during semiconductor manufacturing processes) and / or cleaning gases (e.g., gases used to clean fabricated devices and / or chambers used in the manufacture of electronic devices) may have precise delivery targets that include large mass flow rates, and may even have the ability to precisely control small flow rates. Conventional manufacturing systems often use one or more mass flow controllers (MFCs) to measure and control the mass flow rates of the process gases.

[0004] It would be advantageous to develop MFCs and / or other sensors that are compatible with harsh manufacturing environments (e.g., resistant to corrosion and / or material contamination), maintain a vacuum seal, are robust, have a long operating life, are highly reliable, and have geometries that minimize adverse effects on gas flow characteristics. Summary of the Invention

[0005] Certain embodiments of the present disclosure relate to a sensor assembly having a substrate, a housing, and a sensor device. In certain embodiments, the substrate has an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region. In certain embodiments, the substrate further has electrical contact pads on at least the inner region. In certain embodiments, the housing is coupled to the substrate at the outer region to provide a hermetic seal. In certain embodiments, the sensor device is coupled to the substrate via the electrical contact pads at the inner region.

[0006] In another aspect of the present disclosure, a sensor assembly includes a multilayer ceramic substrate having an outer region, an inner region, and an intermediate region disposed between the outer and inner regions. The multilayer ceramic substrate can further include electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the outer region to the inner region. In certain embodiments, the sensor assembly further includes a housing coupled to the substrate at the intermediate region to form a hermetic seal. In certain embodiments, the sensor assembly further includes a sensor device coupled to the substrate via the electrical contact pads at the inner region.

[0007] In another embodiment of the present disclosure, a sensor assembly includes a multilayer ceramic substrate having a first end and a second end opposite the first end. In certain embodiments, the first end of the multilayer ceramic substrate includes a first outer region, an inner region, and a first intermediate region disposed between the first outer region and the inner region. In certain embodiments, the second end of the multilayer ceramic substrate includes a second outer region and a second intermediate region disposed between the second outer region and the inner region. In certain embodiments, the multilayer ceramic substrate includes electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the first end to the second end. In certain embodiments, the sensor assembly further includes a housing coupled to the multilayer ceramic substrate at the first intermediate region and the second intermediate region to form a hermetic seal. In certain embodiments, the sensor assembly further includes a sensor device coupled to the substrate via the electrical contact pads at the inner region. In certain embodiments, the sensor assembly further includes a conformal coating disposed on at least a portion of the sensor assembly.

[0008] Certain embodiments of the present disclosure relate to methods of manufacturing a sensor assembly. In certain embodiments, the method of manufacturing the sensor assembly includes providing a substrate having an outer region, an inner region, and an intermediate region disposed between the outer and inner regions, the substrate further having electrical contact pads overlying at least the inner region. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding a sensor device to the substrate at the inner region. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding the substrate to a housing at the outer region to form a hermetic seal.

[0009] In another aspect of the present disclosure, a method of manufacturing a sensor assembly includes providing a multilayer ceramic substrate having an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, the multilayer ceramic substrate further having electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the outer region to the inner region. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding a sensor device to the electrical contact pads at the inner region of the multilayer ceramic substrate. In certain embodiments, the method of manufacturing the sensor assembly further includes inserting the multilayer ceramic substrate bonded to the sensor device into a housing. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding the multilayer ceramic substrate to the housing at the intermediate region, such that the substrate is configured to form a hermetic seal in the cantilevered position.

[0010] In another aspect of the present disclosure, a method of manufacturing a sensor assembly includes providing a multilayer ceramic substrate having a first end, a second end opposite the first end, and an inner region between the first end and the second end, wherein the first end has a first outer region and a first intermediate region disposed between the first outer region and the inner region, and the second end has a second outer region and a second intermediate region disposed between the second outer region and the inner region, and the multilayer ceramic substrate has electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the first end to the second end. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding a sensor device to the electrical contact pads at the inner region of the multilayer ceramic substrate. In certain embodiments, the method of manufacturing the sensor assembly further includes inserting the multilayer ceramic substrate bonded to the sensor device into a housing. In certain embodiments, the method of manufacturing the sensor assembly further includes bonding the multi-layer ceramic substrate to the housing at the first intermediate region and the second intermediate region such that the substrate extends from one end of the housing to a second, opposite end of the housing to form a hermetic seal. In certain embodiments, the method of manufacturing the sensor assembly further includes disposing a conformal coating on at least a portion of the sensor assembly.

[0011] Certain embodiments of the present disclosure relate to a flow control device. In certain embodiments, the flow control device includes a gas flow channel defining a gas flow path, a flow regulation valve configured to regulate gas flow in the gas flow channel, a sensor assembly coupled to the gas flow channel, and a processing device. In certain embodiments, the sensor assembly includes a substrate, a housing, a sensor device, and a conformal coating disposed on at least a portion of the sensor assembly. In certain embodiments, the substrate includes an outer region, an inner region, and a middle region disposed between the outer region and the inner region, and the substrate further includes electrical contact pads on at least the inner region. In certain embodiments, the housing is coupled to the substrate at the middle region or the outer region to form a hermetic seal. In certain embodiments, the sensor device is coupled to the substrate via the electrical contact pads at the inner region. In certain embodiments, a processing device is operably coupled to the flow regulation valve and the sensor device and configured to adjust the flow control valve based on a signal from the sensor device.

[0012] The present disclosure is illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which like reference numerals indicate like elements. It should be noted that references to "one" embodiment in the present disclosure are not necessarily to the same embodiment, but such references mean at least one. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates an exemplary system having a processing chamber, a gas source, and a flow controller according to an embodiment of the present disclosure. FIG. 1 also provides an exemplary illustration of how a sensor assembly according to an embodiment of the present disclosure may be incorporated into various locations in a processing chamber and / or manufacturing system. [Figure 2] 1 illustrates an exemplary flow control device according to an embodiment of the present disclosure. [Figure 3] 1A-1C illustrate exemplary sensor devices that may be used in sensor assemblies according to embodiments of the present disclosure. [Figure 4A]FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 4B] FIG. 4B is an enlarged view showing area A of FIG. 4A. [Figure 4C] 4B is a cross-sectional side view of an exemplary flow channel with the sensor assembly of FIG. 4A installed thereon, according to an embodiment of the present disclosure. [Figure 4D] 1 is a cross-sectional view illustrating a conformal coating formed on a surface of an exemplary sensor assembly according to an embodiment of the present disclosure. [Figure 5A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 5B] FIG. 5B is an enlarged view showing region B of FIG. 5A. [Figure 5C] FIG. 5B is a perspective view illustrating a multilayer ceramic substrate included in the sensor assembly of FIG. 5A according to an embodiment of the present disclosure. [Figure 5D] FIG. 5D is a side view showing the multilayer ceramic substrate of FIG. 5C. [Figure 5E] FIG. 5D is a top view showing the multilayer ceramic substrate of FIG. 5C. [Figure 5F] 5B is a cross-sectional side view of an exemplary flow channel with the sensor assembly of FIG. 5A installed, according to an embodiment of the present disclosure. [Figure 6A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 6B] FIG. 6B is an enlarged view showing area C of FIG. 6A. [Figure 6C] FIG. 6B is a perspective view illustrating a substrate included in the sensor assembly of FIG. 6A according to an embodiment of the present disclosure. [Figure 6D] 6B is a side cross-sectional view illustrating an exemplary flow channel comprising the sensor assembly of FIG. 6A according to an embodiment of the present disclosure. [Figure 7A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 7B] FIG. 7B is a perspective view illustrating a multilayer ceramic substrate included in the sensor assembly of FIG. 7A with a sensor device bonded thereto at an interior region according to an embodiment of the present disclosure. [Figure 7C] FIG. 7C is a side view showing the multilayer ceramic substrate of FIG. 7B. [Figure 7D] FIG. 7C is a top view showing the multilayer ceramic substrate of FIG. 7B. [Figure 7E] FIG. 7B is a front view showing section AA of FIG. 7A. [Figure 8A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 8B] FIG. 7B is a front view showing cross section BB of FIG. 7E. [Figure 9A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 9B] FIG. 9B is a perspective view illustrating a multilayer ceramic substrate included in the sensor assembly of FIG. 9A with a sensor device bonded thereto at an interior region according to an embodiment of the present disclosure. [Figure 9C] FIG. 9B is a front view showing section CC of FIG. 9A. [Figure 10A] FIG. 1 is a perspective view illustrating a sensor assembly according to an embodiment of the present disclosure. [Figure 10B] FIG. 10B is a perspective view illustrating a multilayer ceramic substrate included in the sensor assembly of FIG. 10A according to an embodiment of the present disclosure. [Figure 10C] FIG. 10B is a front view showing section DD of FIG. 10A. [Figure 10D] FIG. 1 is a cross-sectional side view of a sensor assembly according to an embodiment of the present disclosure. [Figure 11A] 1 is a flowchart illustrating a method of adapting a sensor device for use in a flow control device according to an embodiment of the present disclosure. [Figure 11B] 1 is a flowchart illustrating a method of manufacturing a sensor assembly according to an embodiment of the present disclosure. [Figure 11C] FIG. 11C illustrates the method 1200 of FIG. 11B. [Figure 12] FIG. 1 is a block diagram illustrating a computer system for use in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The embodiments described herein relate to a sensor assembly (which may also be referred to as sensor packaging) adapted for use in a mass flow controller, a system incorporating the sensor assembly, a method for adapting the sensor assembly for such use, and a method for using the sensor assembly. In certain embodiments, the sensor assembly may be further adapted for uses other than as part of a mass flow controller. For example, the sensor assembly may be adapted for use in temperature control, pressure control, and the like. In some embodiments, the sensor assembly includes a sensor device (such as a MEMS device, a hot-wire anemometer (HWA), or any other suitable sensor) having a free-standing sensing element for direct placement within a flow path of a gas flow channel. In some embodiments, the sensor assembly further includes a substrate, to which the sensor device is secured (e.g., via a metal seal). In some embodiments, the sensor assembly further includes a housing, to which the substrate is secured (e.g., via a metal seal). In certain embodiments, the sensor device may be secured to the substrate via a metal seal (e.g., via soldering or brazing with a brazing alloy), and the substrate may be secured to the housing via another metal seal (e.g., through soldering or brazing with a brazing alloy). In certain embodiments, an O-ring may also be disposed between the substrate and the housing. In certain embodiments, the various components of the sensor assembly are assembled together in a manner that provides a hermetic seal between the substrate (to which the sensor device is secured) and the housing (to which the substrate is secured at an outer region of the substrate or at an intermediate region of the substrate). In certain embodiments, the various components of the sensor assembly may be connected in a manner that establishes continuous electrical conductivity from the free-standing sensing element through the sensor assembly to one or more external devices (such as a processing device) so that a property measured by the sensing element can be transmitted to the processing device.Additionally, the various components of the sensor assembly may be connected in a manner that minimizes the effects of flow turbulence on the sensor measurements and / or provides an airtight seal to accommodate high vacuum and minimize outgassing or leakage. The sensor assembly, in some embodiments, further includes a conformal coating (on portions of the assembly or on the entire assembly) to protect various parts of the sensor assembly from corrosive gases.

[0015] It is generally advantageous to precisely control the temperature and flow rate of process gases used in manufacturing processes to better control the process and to enable compliance with detailed processing constraints. The slow transient response speed of current flow sensors makes them unsuitable for applications requiring precise control of gas dosage, such as delivery of small amounts of gas, or even precise control of successive pulses of one or more gases.

[0016] Embodiments of the present disclosure advantageously overcome the limitations of current sensors by utilizing a sensor device (such as a MEMS device, a hot wire anemometer (HWA), or any other suitable sensor) that resides directly in the gas flow path to provide fast and accurate flow feedback. In addition to flow feedback, the sensor device may advantageously be utilized to provide fast and accurate temperature measurements anywhere in the gas delivery line, including at the source, near a valve, near the inlet to the process chamber (e.g., point of delivery), within the process chamber, or in the foreline. The temperature measurements may be monitored in real time by a processing device, which may further send output commands to heating units at various locations in the gas delivery line.

[0017] Certain embodiments advantageously adapt a sensor device for direct insertion into a gas flow path while protecting the sensor device from corrosive chemicals. For example, embodiments described herein relate to sensor assemblies and materials for the sensor assembly that may be exposed to corrosive chemicals, such as those used during semiconductor processing. The sensor assemblies described herein can be adapted to protect the sensor device from corrosive chemicals while maintaining the electrical properties (e.g., establishing electrical conductivity to the sensor), relative shape, and geometric configuration of the sensor device. In one embodiment, a sensing element (e.g., a nanowire portion) is positioned within the sensor device so as to be exposed to the flow path and enable accurate measurement of the gas flow. The sensor assembly can be further adapted to minimize flow turbulence effects on the sensor device's measurements, minimize corrosion, minimize deposition on the sensor die that may inhibit sensor performance, minimize outgassing or leakage to the external environment, maintain vacuum, maintain thermal properties, maintain the sensitivity and / or measurement accuracy of the sensor device, and maintain a rapid response of the sensor device.

[0018] FIG. 1 illustrates a system 100 having a processing chamber 101, a gas source 160, and a flow controller 200 according to an embodiment of the present disclosure. The processing chamber 101 may be used for a process in which a corrosive plasma environment is realized. For example, the processing chamber 101 may be a chamber for a plasma etcher or plasma etching reactor, a plasma cleaning device, or the like. In alternative embodiments, other processing chambers may be used that may or may not be exposed to a corrosive plasma environment. Some examples of chamber components include a chemical vapor deposition (CVD) chamber, a physical vapor deposition (PVD) chamber, an ALD chamber, an IAD chamber, an etch chamber, and other types of processing chambers. In some embodiments, the processing chamber 101 may be any chamber used in an electronic device manufacturing system.

[0019] In one embodiment, the processing chamber 101 includes a chamber body 102 and a showerhead 130 that surrounds the interior space 106. The showerhead 130 can include a showerhead base and a showerhead gas distribution plate (GDP) that can have multiple gas delivery holes 132 (also referred to herein as channels) that pass completely through the GDP. Alternatively, the showerhead 130 can be replaced by a lid and nozzle in some embodiments, or by multiple pie-shaped showerhead sections and plasma generation units in other embodiments. The chamber body 102 can be fabricated from other suitable materials, such as aluminum, stainless steel, or titanium. The chamber body 102 generally includes a sidewall 108 and a bottom 110.

[0020] An outer liner 116 may be disposed adjacent the sidewall 108 to protect the chamber body 102. The outer liner 116 may be fabricated with one or more apertures. In one embodiment, the outer liner 116 is fabricated from aluminum oxide.

[0021] An exhaust port 126 may be defined in the chamber body 102 and may couple the interior volume 106 to a pumping system 128. The pumping system 128 may have one or more pumps and a throttle valve utilized to evacuate the interior volume 106 of the processing chamber 101 and manage the pressure therein.

[0022] A gas source 160 may be coupled to the processing chamber 101 via supply lines 112 to provide process gases and / or cleaning gases through the showerhead 130 to the interior space 106. A flow controller 200 may be coupled to the gas source 160 and the processing chamber 101. The flow controller 200 may be used to measure and control the flow of gas from the gas source 160 to the interior space 106. An exemplary flow controller 200 is described in more detail below in connection with FIG. 2 . In some embodiments, one or more gas panels 160 may be coupled to the processing chamber 101 to provide gases to the interior space 106. In such embodiments, one or more flow control systems 200 may be coupled to each gas source 160 and processing chamber 101. In other embodiments, a single flow controller 200 may be coupled to one or more gas panels 160. In some embodiments, the flow controller 200 may comprise a flow ratio controller for controlling the flow of gas to the processing chamber 101 (e.g., through one or more supply lines 112) or to other processing chambers.

[0023] A showerhead 130 may be supported on the sidewall 108 of the chamber body 10. The showerhead 130 (or lid) may be open to allow access to the interior space 106 of the processing chamber 101 and may provide a seal for the processing chamber 101 when closed. A gas source 160 may be coupled to the processing chamber 101 to provide process gases and / or cleaning gases to the interior space 106 through the showerhead 130 or the lid and nozzles (e.g., through apertures in the showerhead or lid and nozzles).

[0024] In some embodiments, one or more sensor assemblies 170 may be disposed within the interior space 106. For example, one or more sensor assemblies 170 may be located near (e.g., within 10 centimeters of) the showerhead 130. As another example, one or more sensor devices may be located near (e.g., within 10 centimeters of) the substrate 144, which may be used to monitor conditions near the reaction site.

[0025] In one embodiment, the substrate support assembly 148 has a pedestal 152 that supports the electrostatic chuck 150. The electrostatic chuck 150 further has a thermally conductive base and an electrostatic puck bonded to the thermally conductive base with an adhesive, which in one embodiment may be a silicone adhesive. The thermally conductive base and / or the electrostatic puck of the electrostatic chuck 150 may have one or more optional embedded heating elements, embedded thermal insulators, and / or conduits for controlling the lateral temperature profile of the substrate support assembly 148. The electrostatic puck may further have a plurality of gas passages, such as grooves, mesas, and other surface features, that may be formed in the upper surface of the electrostatic puck. The gas passages may be fluidly coupled to a source of heat transfer gas (or backside gas), such as helium, through holes drilled in the electrostatic puck. During operation, backside gas may be provided into the gas passages under controlled pressure to improve heat transfer between the electrostatic puck and the supported substrate 144. The electrostatic chuck 150 can have one or more clamping electrodes controlled by a chuck power supply.

[0026] 2 depicts a flow controller 200 according to an embodiment of the present disclosure. The flow controller 200 may be configured to measure and control the mass flow rate of a process gas and / or a cleaning gas used in a measurement system and may therefore be considered a type of MFC. The flow controller 200 may be coupled to the gas source 160 and the chamber 101 via a gas flow channel 240. The gas flow channel may correspond to the supply line 112 of FIG. 1. In some embodiments, the flow controller 200 may be incorporated into a flow ratio controller or a pulsed mass flow system.

[0027] In some embodiments, the flow control device 200 can include at least a flow regulator 210, a sensor assembly 220, and a processing device 230. Gas from the gas source 160 flows through a flow path 242 defined through a gas flow channel 240 through the flow regulator 210 to the chamber 101. In other embodiments, the gas flow channel 240 may terminate somewhere other than the chamber 101. For example, the gas flow channel 240 can supply gas to an open environment (e.g., an exhaust system) or a closed environment (e.g., a building or vehicle ventilation system). In some embodiments, the gas flow channel 240 is a gas line, a branch channel of a gas line, or a separate component with an inlet and an outlet attached to a gas line.

[0028] In some embodiments, flow regulator 210 may comprise one or more flow control valves configured to restrict gas flow through flow path 242, each of which may be an actuatable valve, such as a solenoid valve or a piezoelectric valve. In some embodiments, flow regulator 210 has other components in addition to the valves, such as flow-sensing components and temperature-sensing components. In some embodiments, flow regulator 210 functions as an MFC, such as a thermal-based MFC, a pressure-based MFC, or a damping-rate-based MFC.

[0029] In some embodiments in which the flow regulator 210 functions as a thermal-based MFC, the flow regulator 210 has a capillary bypass channel that branches off from the gas flow channel 240. Temperature sensors at the beginning and end of the capillary are used (e.g., by the processing device 230 or an on-board processing device) to calculate a temperature differential that is proportional to the gas flow rate.

[0030] In some embodiments, sensor assembly 220 is disposed downstream of flow regulator 210. Sensor assembly 220 may be part of flow regulator 210 (e.g., adjacent to a flow control valve of flow regulator 210), may be near (e.g., within 10 centimeters of) flow regulator 210, may be near (e.g., within 10 centimeters of) an inlet to chamber 101 or showerhead 130, or may be within chamber 101 (as shown in FIG. 1 in connection with sensor assembly 170, which may be the same as or similar to sensor assembly 220).

[0031] In some embodiments, the sensor assembly 220 includes a sensor device 222 that can be configured to generate one or more signals in response to a condition of the gas flow. For example, the sensor device 222 can be configured to generate one or more signals indicative of a gas temperature or a gas flow rate. Exemplary sensor assemblies are described in more detail below in connection with FIGS. 4A through 10C . In some embodiments, the sensor assembly 220 is coupled to the gas flow channel 240 such that the sensor device 222 is inserted directly into the flow path 242. The sensor assembly 220 is coupled to the gas flow channel such that a seal is formed to prevent gas leakage. In some embodiments, the sensor assembly 220 further includes a housing, and the substrate and the sensor device 222 (e.g., a MEMS device, a hot wire anemometer (HWA), or any other suitable sensor) are secured to the housing via a seal (e.g., a metal seal).

[0032] In some embodiments, the processing device 230 includes a central processing unit (CPU), a microcontroller, a programmable logic controller (PLC), a system-on-chip (SoC), a server computer, or other suitable type of computing device. The processing device 230 may be configured to execute programming instructions associated with the operation of the flow regulator 210. The processing device 230 receives feedback signals from the sensor device 222 and optionally from the flow regulator 210 to calculate the temperature, flow rate, and / or other parameters of the gas flow. The processing device 230 further sends control signals to the flow regulator 210 based on the received feedback signals. In some embodiments, the processing device 230 is configured for fast feedback processing and may include, for example, an EPM. In some embodiments, the processing device is configured to execute a process recipe, or one or more steps of a process recipe, for a manufacturing process using the chamber 101. For example, a recipe may refer to a gas flow at a specific flow rate that occurs for a specific gas at a specific time for a specific duration. As another example, a recipe may refer to pulses of one or more gases.

[0033] 3 shows a top view of an exemplary sensor device 300 that may be fabricated using fabrication techniques well known to those skilled in the art. The sensor device 300 has a support structure 302 that has a substantially planar shape. The support structure 302 may be formed from an insulating material or a semiconductor, such as silicon, silicon with one or more oxide layers formed thereon, or any other suitable material.

[0034] In some embodiments, sensor device 300 has an interface region (interface region 304) at one end of the sensor device and a sensor region (e.g., sensor region 306) at an opposite end of the sensor device. Interface region 304 may be suitable for coupling sensor device 300 to an external device, such as a substrate, for example, via electrical contact pads on the substrate (as further described in connection with FIGS. 4A-10D ). Sensor region 306 may define a cavity 312 across which a freestanding sensing element 308 is suspended.

[0035] 3 also shows an electrode 314 extending from one end of the sensor device 300 (e.g., one end of the interface region 304) to the opposite end of the sensor device 300 (e.g., the opposite end over the sensor region 306) and / or to the sensing element 308. The sensing element 308 may be suspended between two electrodes 314. In one embodiment, the sensing element 308 may be a nanowire. The electrode 314 may be formed from one or more conductive metals. In particular embodiments, the sensing element 308 may be made from the same conductive metal as the electrode 314. In one embodiment, the sensing element 308 and / or the electrode 314 may be made from platinum. The electrode may function as an electrical contact to which one or more devices (e.g., the processing device 230) may be operably coupled. In some embodiments, a portion of the electrode 314 may be fixed to a substrate, as described in further detail in connection with the example sensor assemblies depicted in FIGS. 4A through 10D. The electrodes 314 may serve as electrical contacts for interfacing with such external devices and may form a closed circuit during operation.

[0036] Certain embodiments described herein advantageously adapt a sensor device, such as the sensor device described in connection with FIG. 3 (or any other suitable sensor device), for direct insertion into a gas flow channel (such as gas flow channel 240 of FIG. 2 ) while protecting the sensor device from the corrosive effects of aggressive gases (e.g., halogen-containing gases such as C2F6, SF6, SiCl4, HBr, NF3, CF4, CHF3, CH2F3, F, NF3, Cl2, CCl4, BCl2, and SiF4, among others, and other gases such as O2 or NO) that may be utilized in a processing chamber (e.g., processing chamber 101).

[0037] For example, embodiments described herein relate to sensor assemblies and materials for sensor assemblies that may be exposed to corrosive chemicals, such as those used during semiconductor processing. The sensor assemblies described herein may be adapted to protect the sensor device from corrosive chemicals while maintaining the electrical properties, relative shape, and geometric configuration of the sensor device. The sensor assemblies may be further adapted to minimize flow turbulence effects on the sensor device's measurements, minimize outgassing or leakage to the external environment, maintain vacuum, maintain thermal properties, maintain the sensitivity and / or measurement accuracy of the sensor device, and maintain rapid response of the sensor device. In certain embodiments, the sensor assemblies / packaging described herein enable fast-response sensor devices (such as fast-response MEMS-based hot-wire silicon flow sensors) to be used in corrosive environments. In certain embodiments, the packaging described herein enables the sensor device (such as fast-response MEMS-based hot-wire silicon flow sensors) and / or sensor assembly to be packaged and hermetically sealed without any leakage (e.g., of vacuum and / or corrosive gases) to the external environment. In certain embodiments, the sensor assemblies and / or packaging described herein enable the sensor device to be positioned to maximize its ability to avoid flow turbulence effects. In certain embodiments, the sensor assemblies / packaging described herein enable the sensor device to be positioned symmetrically relative to the center of the flow path. In certain embodiments, the sensor assemblies / packaging described herein enable the coating thickness to be optimized to reduce its impact on the sensitivity of the sensor device. Benefits of such assemblies / packaging include the ability to use fast-response sensor devices (such as fast-response MEMS-based hot-wire silicon flow sensors) in corrosive environments while being compact (in terms of size) and cost-effective. This may advantageously enable rapid and accurate measurement of gas flow and temperature virtually anywhere within a tool (such as anywhere within a processing chamber).

[0038] FIG. 4A shows a perspective view of a sensor assembly 400 according to an embodiment of the present disclosure. In one or more embodiments, a sensor assembly (e.g., sensor assembly 400) has a substrate (e.g., substrate 402). In particular embodiments, the substrate (e.g., substrate 402) has an outer region (e.g., outer region 402O) for coupling the substrate to a housing (e.g., housing 404), an inner region (e.g., inner region 402I) for coupling a sensor device (e.g., sensor device 300) to the substrate, and an intermediate region (e.g., intermediate region 402M) disposed between the outer and inner regions. The term “outer region” as used herein with reference to substrate 402 or any of the substrates illustrated in any of the other figures refers to a region of the substrate that is near an external environment outside of gas fluid channel 240. The term “inner region” as used herein with reference to substrate 402 or any of the substrates illustrated in any of the other figures refers to a region of the substrate that is near an internal environment within gas fluid channel 240. The term "middle region" as used herein with reference to substrate 402 or any of the substrates illustrated in any of the other figures means the region of the substrate that is between the outer region and the inner region.

[0039] In certain embodiments, the substrate may be made of a dielectric material, such as sapphire. Sapphire may be a suitable substrate material due to its good corrosion resistance and ability to be machined into suitable shapes. In certain embodiments, the dielectric sapphire substrate may be machined into suitable shapes according to methods known to those skilled in the art. In certain embodiments, the substrate 402 may have an elongated body with rounded ends (e.g., a cylindrical shape). In certain embodiments, the substrate 402 has a cylindrical shape in its outer region 402O and at least a portion of its middle region 402M, which transitions to a semi-cylindrical shape in its inner region 402I.

[0040] In certain embodiments, the substrate (e.g., substrate 402) can further have electrical contact pads (e.g., electrical contact pads 414) on at least the inner region of the substrate. In one embodiment, the substrate 402 has electrical contact pads 414 on the flat surface of the semi-cylindrical shape of the inner region 402I. The electrical contacts 314 on the interface region of the sensor device 300 can be fixed (e.g., via a metal seal) to the electrical contact pads 414 on the inner region of the substrate. The electrical contacts 314 on the sensor device, together with the electrical contact pads 414 on the substrate and one or more external devices (such as the processing device 230), form a closed circuit during operation. The electrical contact pads (e.g., 414) on the substrate can be of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the electrical contact pads 414 are made of platinum, which can be metallized on the flat surface of the inner region 402I of the substrate 402 via procedures known to those skilled in the art.

[0041] In certain embodiments, a substrate (e.g., substrate 402) may be coupled to a housing (e.g., housing 404) at its outer region (e.g., 402O) to form a hermetic seal. In certain embodiments, the housing may be made of stainless steel, a nickel alloy (e.g., Hastelloy® C-276 alloy, an alloy of nickel, molybdenum, and chromium), Kovar (e.g., a nickel-cobalt iron alloy), or another suitable material. In one embodiment, the housing may be made of stainless steel. In certain embodiments, the substrate may be secured to the housing via a metal seal, e.g., via soldering or brazing, to minimize gas leakage from the processing chamber environment to the external environment. In certain embodiments, the substrate may be further secured to the housing via at least one additional leak-proof seal, such as a counterbore C-seal. In certain embodiments, an o-ring may further be disposed between the substrate and the housing to further assist in a hermetic seal between the substrate and the housing and to minimize and / or eliminate vacuum leakage and / or corrosive gas leakage from the gas channel 240 through the sensor assembly 400. In certain embodiments, a cap may be disposed between the substrate and the housing to engage (e.g., compress) the o-ring.

[0042] 4A , the substrate 402 may be further machined to define conductor pin holes that extend completely through the length of the substrate, from the top of the outer region 402O through the middle region 402M to at least a portion of the inner region 402I. In certain embodiments, the substrate 402 further has conductor pins 416 that are within the conductor pin holes, and the conductor pins 416 extend completely through the outer region 402O and the middle region 402M of the substrate 402 and into at least a portion of the inner region 402I of the substrate 402. In certain embodiments, the conductor pins 416 are secured to electrical contact pads 414 disposed on the inner region 402I of the substrate 402, for example via a metal seal. The electrical contacts 314 on the sensor device, the electrical contact pads 414 on the substrate, and the conductor pins 416 together form a closed circuit during operation with one or more external devices (such as the processing device 230). The conductive pins (e.g., 416) that extend completely through the substrate may be the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the conductive pins 416 are made of platinum.

[0043] FIG. 4B shows an expanded view of region A of FIG. 4A , enlarging the connections between the sensor device 300, the substrate 402, the electrical contact pads 414, and the conductor pins 416. In the embodiment shown in FIG. 4B , the sensor device 300 is coupled via its electrical contacts 314 to the electrical contact pads 414 on the inner region 402I of the substrate 402. In one embodiment, the sensor device is coupled via a first seal 420A, which may be a metal seal, such as with a first brazing alloy. In certain embodiments, the sensor device is secured to the substrate such that the support structure (e.g., 302) of the sensor device (e.g., 300) is oriented perpendicular to the gas flow direction (e.g., 242), as further illustrated in connection with FIG. 4C . In certain embodiments, the sensor device is secured to the substrate such that the elongated support structure of the sensor device is oriented parallel to the gas flow direction, as further illustrated in connection with at least the sensor assembly shown in FIG. 6D .

[0044] In one embodiment, the outer region 402O of the substrate 402 is coupled / secured to the housing 404 via a second seal 420B, which may be a metal seal, such as by using a second braze alloy. In certain embodiments, the outer region 402O of the substrate 402 may further be secured to the housing 404 via at least one additional leak-proof seal, such as a counterbore C-seal.

[0045] 4B , the conductor pin 416 is bonded / secured to an electrical contact pad 414 on the inner region 402I of the substrate 402. In one embodiment, the conductor pin 416 is secured to the electrical contact pad 414 via a third seal 420C, which may be a metallic seal, such as with a third brazing alloy. In certain embodiments, the conductor pin 416 may be further secured to the substrate 402, for example at the middle region 402M, via a fourth seal 420D, which may be a metallic seal, such as with a fourth brazing alloy, thereby forming a hermetic seal to minimize or eliminate vacuum leakage and / or gas (e.g., corrosive gas) from the gas channel 240 through the conductor pin hole (through which the conductor pin 416 passes) in the substrate 402.

[0046] When present, each of the first seal, second seal, third seal, and fourth seal may independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, the brazing alloy used for all seals is the same. In other embodiments, two or more different brazing alloys may be used for different seals. In one embodiment, at least one of seals 420A, 420B, 420C, or 420D comprises a Sn-Ag-Ti brazing alloy. It should be recognized that the meanings of "first seal," "second seal," "third seal," "fourth seal," etc., should not be construed as limiting with respect to the ordering of various components within the sensor assembly described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assembly. Rather, these meanings are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in connection with Figures 11A and 11B.

[0047] In some embodiments, the sensor assembly (e.g., sensor assembly 400) further includes a non-conductive conformal coating on one or more surfaces or on at least a portion of the sensor assembly. In some embodiments, the coating covers some or all of the sensor device (e.g., 300). In some embodiments, the coating covers some or all of the sensor region 306 and / or interface region 304 of sensor device 300. In some embodiments, the coating covers some or all of the sensor region 306, including some or all of the sensing element 308. In other embodiments, the conformal coating covers the sensor region 306 without covering the sensing element 308. In some embodiments, the coating covers some or all of the substrate 402. In some embodiments, the coating covers some or all of the outer region 402O, the middle region 402M, and / or the inner region 402I. In some embodiments, the coating covers some or all of the inner region 402I, including some or all of the electrical contact pads 414. In some embodiments, the coating covers some or all of the middle region 402M, including some or all of the conductor pins 416. In some embodiments, the coating covers some or all of the various seals (e.g., first seal 420A, second seal 420B, third seal 420C, and / or fourth seal 420D), and in certain embodiments, the sensor assembly may remain completely uncovered.

[0048] In some embodiments, the sensor assembly is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device and the substrate and between the substrate and the conductor pins), and then the assembled sensor assembly is coated with a coating to cover the portions of the sensor assembly that will be exposed to the gas flow when the sensor assembly is coupled into the gas flow channel, as discussed later in connection with FIG. 4C.

[0049] In some embodiments, the coating is deposited using, for example, ALD, IAD, low pressure plasma spray (LPPS), chemical vapor deposition (CVD), plasma spray chemical vapor deposition (PS-CVD), sputtering, combinations thereof, or other techniques or modifications of these other techniques suitable for forming a conformal coating. In some embodiments, the coating comprises a ceramic material that is resistant to corrosion by process gases or reactive species. For example, in some embodiments, the coating is deposited using a ceramic material such as YO, YZrO, Y x Zr y O z , YZrOF, Y3Al5O 12 , Y4Al2O9, YF3, Y x O y F z , YOF, Er2O3, Er3Al5O 12 , ErF3, E x O y F z The plasma-resistant ceramic coating may include a rare earth ceramic selected from ErOF, La2O3, Lu2O3, Sc2O3, ScF3, ScOF, Gd2O3, Sm2O3, Dy2O3, YO3-ZrO2 solid solution, a ceramic including YO3Al4O9 and YO3-ZrO2 solid solution, or a combination thereof. In some embodiments, the coating includes Al2O3. In one embodiment, the coating includes Al2O3 deposited by atomic layer deposition (ALD). In some embodiments, the coating has a substantially uniform thickness, is conformal to the underlying surface being coated, is void-free, crack-free, acts as a diffusion barrier for metallic contamination, and has high purity (e.g., greater than about 99% purity, or greater than about 99.95% purity). In certain embodiments, ALD may be advantageously utilized to cover all dimensions of the sensor assembly. In some embodiments, the coating is resistant to cracking and / or delamination at various temperatures (such as up to 350°C).

[0050] In certain embodiments, the coating can have a uniform thickness with less than about + / -20% thickness variation, less than about + / -10% thickness variation, less than about + / -5% thickness variation, or even less thickness variation when comparing the coating thickness at one location to the coating thickness at another location (or when comparing the coating thickness at one location to the average thickness of the coating, or when evaluating the standard deviation of the coating thickness across multiple locations).

[0051] In certain embodiments, the coating can conform to the underlying surface it coats, including underlying surface features and / or coated features having complex geometries and / or high aspect ratios. For example, the coating can conformally and uniformly coat features having high aspect ratios, e.g., length:width (L:W) or length:diameter (L:D), ranging from about 2:1 to about 500:1, about 5:1 to about 300:1, about 10:1 to about 150:1, about 15:1 to about 100:1, or about 20:1 to about 50:1.

[0052] In certain embodiments, the coating may be very dense and may have a very low porosity, such as a porosity of less than about 1%, less than about 0.5%, less than about 0.1%, or no porosity (0% porosity). In certain embodiments, the coating may have a crack-free microstructure, may be hermetic, and may have high dielectric breakdown resistance.

[0053] In certain embodiments, the coating can be deposited at low deposition temperatures, such as deposition temperatures up to 350° C., which can enable its use with a wide variety of materials.

[0054] FIG. 4D illustrates a cross-sectional view of a conformal coating formed on a surface of an exemplary sensor assembly according to an embodiment of the present disclosure. For simplicity, FIG. 4D illustrates coating 420 on a portion of sensor assembly 400, which may be any portion of sensor assembly 400 described herein. In a similar manner, coating 420 may be deposited on any portion of any of the other sensor assemblies described herein. In some embodiments, the coating has multiple layers 422A-422D deposited in succession. In some embodiments, there may be more or fewer layers than shown, and the number of layers may range from 1 to 100, up to 500, or more. For example, multiple atomically thin or near-atomically thin layers may be deposited using, for example, ALD. In some embodiments, the composition of each of layers 422A-422D may alternate. In some embodiments, the total thickness of the coating may range from 10 nanometers to 500 nanometers, or any subrange therein, or any single value therein. In certain embodiments, the thickness of the coating is optimized to reduce the effect of the coating on the sensitivity of the measurement while protecting the sensor assembly (and its various components) from aggressive chemicals to which the sensor assembly may be exposed during processing.

[0055] 4C shows a cross-sectional side view of an example flow channel (such as flow channel 240) having the sensor assembly 400 of FIG. 4A coupled thereto, according to an embodiment of the present disclosure. As shown in this figure, the sensor assembly 400 can be installed in a manifold, such as a K1S T-manifold (comprising a T-joint 492), via an appropriate seal, such as a leak-proof seal (e.g., a C-seal). The manifold can be coupled to the gas flow channel 240 (such as tubing) at both ends.

[0056] In certain embodiments, a housing (e.g., housing 404) can have a gas-side surface 460 and an opposing surface 470 opposite the gas-side surface. The housing 404 can have at least one slot (e.g., slot 480B) formed therethrough that is shaped to receive a substrate (e.g., substrate 402). The substrate 402 can be inserted into the slot (e.g., slot 480B) such that an interior region of the substrate 402I extends from the gas-side surface 460 into, for example, the interior environment of the gas flow channel (e.g., gas flow channel 240). In certain embodiments, the housing 404 can have at least one additional slot (e.g., 480A and 480C) that can be configured to mount the housing 404 to the gas flow channel 240, for example, via an appropriate manifold and / or appropriate seal (e.g., C-seal 490) and / or appropriate fitting (e.g., T-fitting 492). Seal 490 may be a gas-tight seal to prevent gas leakage to the external environment from gas flow channel 240. In some embodiments, seal 490 is a metallic seal formed, for example, by brazing or soldering.

[0057] FIG. 5A shows a perspective view of a sensor assembly 500 according to an embodiment of the present disclosure. In one or more embodiments, the sensor assembly (e.g., sensor assembly 500) has a substrate (e.g., substrate 502). In certain embodiments, the substrate (e.g., substrate 502) has an outer region (e.g., outer region 502O) for coupling the substrate to a housing (e.g., housing 504), an inner region (e.g., inner region 502I) for coupling a sensor device (e.g., sensor device 300) to the substrate, and an intermediate region (e.g., intermediate region 502M) disposed between the outer and inner regions. In certain embodiments, the dielectric substrate may be a multilayer ceramic made of multiple layers of ceramic sheets. The multilayer ceramic substrate may be made of any dielectric ceramic material that can be formed into an appropriate shape. In certain embodiments, the dielectric multilayer ceramic substrate may be made of alumina (Al2O3) or aluminum nitride (AlN). In certain embodiments, the substrate may be made of AlN, Si, SiC, Al2O3, SiO2, or the like. Multilayer ceramic substrates can be advantageously used due to their high strength, good electrical insulation, low coefficient of thermal expansion, and good chemical stability. Multilayer ceramics can be made by methods known to those skilled in the art, such as through processes including one or more of the following operations: tape casting, tape cutting, assembly, via punching, via filling, screen printing, lamination, cutting, co-firing, Ni plating, Au plating, or a combination thereof, without limitation.

[0058] FIG. 5C shows a perspective view of a multilayer ceramic substrate included in the sensor assembly of FIG. 5A according to an embodiment of the present disclosure. FIG. 5D shows a side view of the multilayer ceramic substrate of FIG. 5C. FIG. 5E shows a top view of the multilayer ceramic substrate of FIG. 5C. In the embodiment shown in FIGS. 5C-5E, two layers of ceramic sheets are shown (e.g., a first layer 502A and a second layer 502B covering a portion of the first layer 502A). In the depicted embodiment, the ceramic layers 502A and 502B are in contact to achieve an airtight seal between the layers. In the illustrated embodiment, electrical contact pads 514 are formed / incorporated between the layers of the multilayer ceramic substrate 502 (e.g., the electrical contact pads 514 are formed between the first and second ceramic layers 502A and 502B). The electrical contact pads 514 extend completely through the multilayer ceramic substrate from its outer region 502O to its inner region 502I. One advantage of this substrate is that a hermetic seal is achieved between the ceramic layers of the multi-layer ceramic, with electrical contact pads formed between the layers. This hermetic seal reduces the number of locations where various components of the sensor assembly must be secured via metal seals (e.g., via brazing), minimizing potential locations for vacuum and / or gas leakage from the internal environment within gas channel 240.

[0059] 5C-5E as having sharp corners (e.g., a rectangular shape in each of the layers), the present disclosure also contemplates multilayer ceramic substrates with rounded edges, similar to the shape shown for substrate 402 in sensor assembly 400. In certain embodiments, other substrate shapes may also be used, and the present disclosure should not be considered limited to only the shapes shown in the figures.

[0060] In certain embodiments, electrical contacts 314 on the interface region of the sensor device 300 may be secured (e.g., via a metal seal) to electrical contact pads 514 on the inner region 502I of the substrate 502. The electrical contacts 314 on the sensor device, along with the electrical contact pads 514 on the substrate and one or more external devices (such as the processing device 230), together form a closed circuit during operation. The electrical contact pads (e.g., 514) located between the layers of the multi-layer ceramic substrate 502 may be of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the electrical contact pads 514 are made of platinum.

[0061] In certain embodiments, a substrate (e.g., substrate 502) may be coupled to a housing (e.g., housing 504) at its outer region (e.g., 502O). In certain embodiments, the housing may be made of stainless steel, a nickel alloy (e.g., Hastelloy® C-276 alloy, an alloy of nickel, molybdenum, and chromium), Kovar (e.g., a nickel-cobalt iron alloy), or another suitable material. In one embodiment, the housing may be made of stainless steel. In certain embodiments, the substrate may be secured to the housing via a metal seal, e.g., via soldering or brazing, to minimize gas leakage from the processing chamber environment to the external environment. In certain embodiments, the substrate may be further secured to the housing via at least one additional leak-proof seal, such as a counterbore C-seal.

[0062] In certain embodiments, an o-ring 580 may further be disposed between the substrate 502 and the housing 504 to further assist in a hermetic seal between the substrate and the housing and / or to minimize and / or eliminate vacuum leakage and / or corrosive gas leakage from the gas channel 240 through the sensor assembly 500. In certain embodiments, a cap may be disposed between the substrate and the housing to engage (e.g., compress) the o-ring.

[0063] FIG. 5B shows an expanded view of region B of FIG. 5A , enlarging the connections between the sensor device 300, the substrate 502, and the electrical contact pads 514. In the embodiment shown in FIG. 5B , the sensor device 300 is coupled via its electrical contacts 314 to the electrical contact pads 514 on the inner region 502I of the substrate 502. In one embodiment, the sensor device is coupled to the electrical contact pads 514 via a first seal 520A, which may be a metal seal formed via soldering or brazing, such as, for example, using a first brazing alloy. In certain embodiments, the sensor device is secured to the substrate such that the support structure (e.g., 302) of the sensor device (e.g., 300) is oriented perpendicular to the gas flow direction (e.g., 242), as further illustrated in connection with FIG. 5F . In certain embodiments, the sensor device is secured to the substrate such that the support structure of the sensor device is oriented parallel to the gas flow direction, as further illustrated in connection with at least the sensor assembly shown in FIG. 6D .

[0064] In one embodiment, the outer region 502O of the substrate 502 is coupled / secured to the housing 504 via a second seal 520B, which may be a metal seal, such as with a second braze alloy. In certain embodiments, the outer region 502O of the substrate 502 may further be secured to the housing 504 via at least one additional leak-proof seal, such as a counterbore C-seal. In certain embodiments, the substrate is secured to the housing via a hermetic seal to minimize and / or eliminate vacuum and / or gas leakage from the gas channels 240.

[0065] Each of the first seal (520A) and the second seal (520B), when present, can independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, the brazing alloy used for all seals is the same. In other embodiments, two or more different brazing alloys may be used for different seals. In one embodiment, at least one of seals 520A or 520B comprises an Ag—Cu brazing alloy. It should be recognized that the terms “first seal,” “second seal,” etc., should not be construed as limiting with respect to the order of the various components constrained within the sensor assemblies described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assembly. Rather, these terms are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in conjunction with FIGS. 11A and 11B.

[0066] In some embodiments, the sensor assembly (e.g., sensor assembly 500) further has a non-conductive conformal coating on one or more surfaces or on at least a portion of the sensor assembly. In some embodiments, the coating covers some or all of the sensor device (e.g., 300). In some embodiments, the coating covers some or all of the sensor region 306 and / or interface region 304 of sensor device 300. In some embodiments, the coating covers some or all of the sensor region 306, including some or all of the sensing element 308. In other embodiments, the conformal coating covers the sensor region 306 without covering the sensing element 308. In some embodiments, the coating covers some or all of the substrate 502. In some embodiments, the coating covers some or all of the outer region 502O, the middle region 502M, and / or the inner region 502I. In some embodiments, the coating covers some or all of the inner region 502I, including some or all of the electrical contact pads 514. In some embodiments, the coating covers some or all of the middle region 502M. In some embodiments, a coating covers some or all of the various seals (e.g., first seal 520A and / or second seal 520B). In some embodiments, sensor assembly 500 is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device and the substrate), and then the assembled sensor assembly is coated with a coating to cover portions of the sensor assembly that will be exposed to gas flow when the sensor assembly is coupled into a gas flow channel, as discussed below in connection with FIG. 5F. In some embodiments, the coating deposited on at least a portion of sensor assembly 500 may be similar to the coatings described herein above that are suitable for covering at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.).In certain embodiments, the sensor assembly 500 remains completely uncovered.

[0067] 5F shows a cross-sectional side view of an example flow channel (such as flow channel 240) having the sensor assembly 500 of FIG. 5A coupled thereto, according to an embodiment of the present disclosure. As shown in this figure, the sensor assembly 500 can be installed in a manifold, such as a K1S T-manifold (T-joint 592), via an appropriate seal, such as a leak-proof seal (e.g., a C-seal). The manifold can be coupled to the gas flow channel 240 (such as tubing) at both ends.

[0068] In certain embodiments, a housing (e.g., housing 504) can have a gas-side surface 560 and an opposing surface 570 opposite the gas-side surface. The housing 504 can have at least one slot (e.g., slot 580B) molded therethrough that is configured to receive a substrate (e.g., substrate 502). The substrate 502 can be inserted into the slot (e.g., slot 580B) such that an interior region of the substrate 502I extends from the gas-side surface 560 into, for example, the interior environment of the gas flow channel (e.g., gas flow channel 240). In certain embodiments, the housing 504 can have at least one additional slot (e.g., 580A and 580C) that can be configured to mount the housing 504 to the gas flow channel 240, for example, via an appropriate manifold and / or appropriate seal (e.g., C-seal 590) and / or appropriate fitting (e.g., T-fitting 592). Seal 590 may be a gas-tight seal to prevent leakage of gas to the external environment from gas flow channel 240. In some embodiments, seal 590 is a metallic seal formed, for example, by brazing or soldering.

[0069] Although sensor assembly 400 and sensor assembly 500 are shown in embodiments in which sensor device 300 is secured to a corresponding substrate with a perpendicular orientation of the support structure of the sensor device relative to the gas flow direction (e.g., 242), in some embodiments, sensor device 300 may be secured to a substrate with a parallel orientation of the support structure of the sensor device relative to the gas flow direction (e.g., 242). Such an example embodiment is described with reference to at least sensor assembly 600 of FIG. 6D.

[0070] 6A shows a perspective view of a sensor assembly 600 according to an embodiment of the present disclosure. In one or more embodiments, the sensor assembly (e.g., sensor assembly 600) has a substrate (e.g., substrate 602). In particular embodiments, the substrate (e.g., substrate 602) has an outer region (e.g., outer region 602O) for coupling the substrate to a housing (e.g., housing 604), an inner region (e.g., inner region 602I) for coupling a sensor device (e.g., sensor device 300) to the substrate, and an intermediate region (e.g., intermediate region 602M) disposed between the outer and inner regions.

[0071] FIG. 6C shows a perspective view of a substrate, such as the substrate included in the sensor assembly 600 of FIG. 6A , in accordance with an embodiment of the present disclosure. In the embodiment depicted in FIG. 6C , the substrate is made of a dielectric material, such as sapphire. In the embodiment depicted in FIG. 6C , the substrate is machined sapphire with rounded edges. The substrate 602 shown has a cylindrical shape in its middle region 602M. In the embodiment shown, the cylindrical shape of region 602M transitions to a semi-cylindrical shape in the inner region 602I. In the embodiment shown, the cylindrical shape of region 602M continues into a portion of the outer region 602O, eventually reaching the top of the outer region 602O. In the embodiment shown, the top of the outer region 602O is shaped as a disk having a diameter larger than the diameters of the cylindrical portions of regions 602O and 602M. The illustrated substrate further defines a conductor pin hole 616H extending from the top of the outer region 602O of the substrate 602 to the bottom of the inner region 602I of the substrate 602, shaped to receive a conductor pin 616, as will be described in more detail below. In certain embodiments, a substrate (whether sapphire or multi-layer ceramic) with rounded edges can mitigate stress factors, thereby extending the operational life of the sensor assembly. The substrate 602 can be machined into the shape shown or any other suitable shape by means known to those skilled in the art.

[0072] In certain embodiments, the substrate (e.g., substrate 602) can further include electrical contact pads (e.g., electrical contact pads 614) on at least an inner region of the substrate. The electrical contacts 314 on the interface region of the sensor device 300 can be secured (e.g., via a metal seal) to the electrical contact pads 614 on the inner region of the substrate. The electrical contacts 314 on the sensor device, together with the electrical contact pads 614 on the substrate and one or more external devices (such as the processing device 230), together form a closed circuit during operation. The electrical contact pads (e.g., 614) on the substrate can be of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the electrical contact pads 614 are platinum, which can be metallized onto the substrate (e.g., the machined sapphire substrate 602) via procedures known to those skilled in the art.

[0073] In certain embodiments, a substrate (e.g., substrate 602) may be coupled to a housing (e.g., housing 604) at its outer region (e.g., 602O). In certain embodiments, the housing may be made of stainless steel, a nickel alloy (e.g., Hastelloy® C-276 alloy, which is an alloy of nickel, molybdenum, and chromium), Kovar (e.g., a nickel-cobalt iron alloy), or another suitable material. In one embodiment, the housing may be made of stainless steel. In certain embodiments, the substrate may be secured to the housing via a metal seal, e.g., via soldering or brazing, to minimize gas leakage from the processing chamber environment to the external environment.

[0074] In certain embodiments, an o-ring may further be disposed between the substrate 602 and the housing 604 to further assist in a hermetic seal between the substrate and the housing and to minimize and / or eliminate vacuum leakage and / or corrosive gas leakage from the gas channel 240 through the sensor assembly 600. In certain embodiments, a cap may be disposed between the substrate and the housing to engage (e.g., compress) the o-ring.

[0075] 6A , the substrate 602 further includes a conductive pin 616 that extends completely through the outer region 602O and the middle region 602M of the substrate 602 to the bottom of the inner region 602I of the substrate 602. The conductive pin 616 is received within the substrate 602 through a conductive pin hole 616H that extends from the top of the outer region 602O of the substrate 602 to the bottom of the inner region 602I of the substrate 602. In a particular embodiment, the conductive pin 616 is secured to an electrical contact pad 614 disposed on the bottom of the inner region 602I of the substrate 602. The electrical contacts 314 on the sensor device, the electrical contact pads 614 on the substrate, and the conductive pin 616 together form a closed circuit during operation with one or more external devices (such as the processing device 230). The conductive pins (e.g., 616) that extend completely through the substrate may be made of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the conductive pin 616 is made of platinum.

[0076] FIG. 6B shows an expanded view of region C of FIG. 6A , enlarging the connection between sensor device 300 and substrate 602. In the embodiment shown in FIG. 6B , sensor device 300 is coupled via its electrical contacts 314 to electrical contact pads 614 on inner region 602I of substrate 602. In one embodiment, the sensor device is coupled via a first seal 620A, which may be a metal seal, such as with a first brazing alloy. In certain embodiments, the sensor device is secured to the substrate such that the support structure (e.g., 302) of the sensor device (e.g., 300) is oriented parallel to the gas flow direction (e.g., 242), as further shown in connection with FIG. 6D . One of the key differences between sensor assembly 600 and sensor assembly 400 is the orientation of sensor device 300. In certain embodiments, measurements achieved with a sensor assembly comprising a sensor device fixed in a parallel orientation may be less affected by gas flow recirculation and / or turbulence, improving conductivity through the flow path. In certain embodiments, a sensor device (such as sensor device 300) fixed to a substrate in a parallel orientation (with respect to the gas flow direction, e.g., 242) directs gas recirculation away from the sensor tip, thereby minimizing its effect on the accuracy of the sensor measurement.

[0077] In one embodiment, the outer region 602O of the substrate 602 is coupled / secured to the housing 604 via a second seal 620B, which may be a metallic seal, such as with a second braze alloy, and / or via a third seal 620C, which may also be a metallic seal, such as with a third braze alloy. In certain embodiments, the outer region 602O of the substrate 602 may further be secured to the housing 604 via at least one additional seal, such as a leak-proof seal (e.g., a counterbore C-seal).

[0078] 6B , the conductor pin 616 may be coupled / secured to the electrical contact pad 614 and / or the sensor device 300 at the bottom of the inner region 602I of the substrate 602 via a fourth seal 620D, which may be a metal seal, such as with a fourth brazing alloy. In certain embodiments, the conductor pin 616 may further be secured to the substrate 602, e.g., at the bottom of the inner region 602I, via a fifth seal 620E, which may be a metal seal, such as with a fifth brazing alloy. In certain embodiments, the conductor pin 616 may be secured to the substrate 602 via a seal to minimize and / or eliminate vacuum leakage and / or corrosive gas leakage from the gas channel 240 through the sensor assembly 600 (e.g., through the conductor pin hole 616H through which the conductor pin 616 passes).

[0079] Each of the first seal (620A), second seal (620B), third seal (620C), fourth seal (620D), and fifth seal (620E), if present, can independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, the brazing alloy used for all seals is the same. In other embodiments, two or more different brazing alloys may be used for different seals. In one embodiment, at least one of seals 620A, 620B, 620C, 620D, or 620E comprises Sn-Ag-Ti as the brazing alloy. It should be appreciated that the meanings of "first seal," "second seal," "third seal," "fourth seal," "fifth seal," etc. should not be construed as limiting with respect to the ordering of the various components constrained within the sensor assemblies described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assemblies. Rather, these meanings are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in connection with FIGS. 11A and 11B.

[0080] In some embodiments, the sensor assembly (e.g., sensor assembly 600) further has a non-conductive conformal coating on one or more surfaces or on at least a portion of the sensor assembly. In some embodiments, the coating covers some or all of the sensor device (e.g., 300). In some embodiments, the coating covers some or all of the sensor region 306 and / or interface region 304 of sensor device 300. In some embodiments, the coating covers some or all of the sensor region 306, including some or all of the sensing element 308. In other embodiments, the conformal coating covers the sensor region 306 without covering the sensing element 308. In some embodiments, the coating covers some or all of the substrate 602. In some embodiments, the coating covers some or all of the outer region 602O, the middle region 602M, and / or the inner region 602I. In some embodiments, the coating covers some or all of the inner region 602I, including some or all of the electrical contact pads 614 and / or the conductor pins 616. In some embodiments, the coating covers some or all of the middle region 602M. In some embodiments, a coating covers some or all of the various seals (e.g., first seal 620A, second seal 620B, third seal 620C, fourth seal 620D, and / or fifth seal 620E). In some embodiments, the sensor assembly is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device, conductor pins, and substrate), and then the assembled sensor assembly is coated with a coating to cover at least the portions of the sensor assembly that will be exposed to gas flow when the sensor assembly is coupled into a gas flow channel, as discussed below in connection with FIG. 6D .In certain embodiments, if the coating covers the conductor pin 616 at a top portion of the outer region 602O of the substrate 602 (e.g., a top portion exposed to the external environment that extends from the opposite surface of the housing 670 opposite the gas-side surface 660), a portion of the coating may be uncovered (e.g., etched), thereby exposing at least a portion of the conductor pin 616. The exposed part of the conductor pin 616 (in the external environment) can then be coupled to one or more external devices (such as the processing device 230) to form a closed electrical circuit during operation. In certain embodiments, the sensor assembly 600 remains completely uncovered.

[0081] In some embodiments, the coating deposited on at least a portion of sensor assembly 600 may be similar to the coatings described herein above that are suitable for covering at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.).

[0082] FIG. 6D shows a cross-sectional side view of an example flow channel (such as flow channel 240) having the sensor assembly 600 of FIG. 6A coupled thereto, according to an embodiment of the present disclosure.

[0083] In certain embodiments, a housing (e.g., housing 604) can have a gas-side surface 660 and an opposing surface 670 opposite the gas-side surface. Housing 604 can have at least one slot (e.g., slot 680B) formed through housing 504 shaped to receive a substrate (e.g., substrate 602). Substrate 602 can be inserted into the slot (e.g., slot 680B) such that an inner region 602I of the substrate extends from gas-side surface 660 into, for example, the internal environment of a gas flow channel (e.g., gas flow channel 240). In certain embodiments, housing 604 can have at least one additional slot (e.g., 680A and 680C) that can be configured to mount housing 604 to gas flow channel 240, for example, via an appropriate manifold (e.g., a K1H manifold) and / or an appropriate seal (e.g., C-seal 590), and / or via an appropriate fitting. Seal 690 may be a gas-tight seal to prevent leakage of gas from gas flow channel 240. In some embodiments, seal 690 is a metallic seal formed, for example, by brazing or soldering.

[0084] In certain embodiments, the dimensions of sensor assembly 600 are larger than the dimensions of sensor assemblies 400 and 500 because substrate 602 is inserted into slot 680B with sensor device 300 secured to substrate 602 in a parallel orientation (as opposed to a perpendicular orientation as shown for sensor assemblies 400 and 500) relative to the direction of gas flow 242. In certain embodiments, slot 680B may be shaped to accept the insertion of substrate 602 such that sensor device 300 is coupled to substrate 602 in a parallel orientation without sensing element 308 touching the borders of slot 680B.

[0085] 7A shows a perspective view of a sensor assembly 700 according to certain other embodiments of the present disclosure. In one or more embodiments, the sensor assembly (e.g., sensor assembly 700) has a substrate (e.g., substrate 702). In particular embodiments, the substrate (e.g., substrate 702) has an outer region (e.g., outer region 702O), an inner region (e.g., inner region 702I) for coupling a sensor device (e.g., sensor device 300) to the substrate, and an intermediate region (e.g., intermediate region 702M) disposed between the outer and inner regions. In particular embodiments, the substrate may be coupled to a housing (e.g., housing 704) at intermediate region 702M. In particular embodiments, substrate 702 may be a multilayer ceramic made of multiple layers of ceramic sheets, similar to multilayer ceramic substrate 502 described in connection with sensor assembly 500.

[0086] FIG. 7B shows a perspective view of a multilayer ceramic substrate included in the sensor assembly of FIG. 7A , in which a sensor device 300 is bonded to a substrate 702 at an inner region 702I, according to an embodiment of the present disclosure. FIG. 7C shows a side view of the multilayer ceramic substrate of FIG. 7B . FIG. 7D shows a top view of the multilayer ceramic substrate of FIG. 7B . In the embodiment shown in FIGS. 7B-7D , two layers of ceramic sheets are shown (e.g., a first layer 702A and a second layer 702B covering a portion of the first layer 702A in an intermediate region 702M). In the depicted embodiment, the ceramic layers 702A and 702B are in contact to achieve an airtight seal between the layers (similar to the multilayer ceramic substrate 502). In the illustrated embodiment, electrical contact pads 714 are formed / integrated between the layers of the multilayer ceramic substrate 702 (e.g., the electrical contact pads 714 are formed between the first ceramic layer 702A and the second ceramic layer 702B). Electrical contact pads 714 extend completely through the multi-layer ceramic substrate from its outer region 702O to its inner region 702I. This substrate, similar to substrate 502, has the advantage that a hermetic seal is achieved between the ceramic layers of the multi-layer ceramic substrate, with electrical contact pads formed between the layers. This hermetic seal reduces the number of locations where various components of the sensor assembly must be secured via metal seals (e.g., via brazing).

[0087] Ceramic substrate 702 may be made of any suitable plasma-resistant ceramic that can be formed into a suitable multi-layer ceramic according to methods known to those skilled in the art, as described hereinabove in connection with substrate 502. Likewise, ceramic substrate 702 may be made of materials similar to those described hereinabove for substrate 502.

[0088] In certain embodiments, electrical contacts 314 on the interface region of sensor device 300 may be secured (e.g., via a metal seal) to electrical contact pads 714 on the interior region of substrate 702. The electrical contacts 314 on the sensor device, along with the electrical contact pads 714 on the substrate and one or more external devices (such as processing device 230), together form a closed circuit during operation. The electrical contact pads (e.g., 714) located between the layers of multilayer ceramic substrate 702 may be of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the electrical contact pads 714 are made of platinum.

[0089] In certain embodiments, a substrate (e.g., substrate 702) may be coupled to a housing (e.g., housing 704) at its mid-region (e.g., 702M). In certain embodiments, the housing may be made of stainless steel, a nickel alloy (e.g., Hastelloy® C-276 alloy, which is an alloy of nickel, molybdenum, and chromium), Kovar (e.g., a nickel-cobalt iron alloy), or another suitable material. In one embodiment, the housing may be made of stainless steel. In certain embodiments, the substrate may be secured to the housing via a metal seal, e.g., via brazing, to minimize gas leakage from the processing chamber environment to the external environment. In certain embodiments, an o-ring may be disposed between the substrate 702 and the housing 704. In certain embodiments, a cap configured to engage (e.g., compress) the o-ring may be disposed between the substrate 702 and the housing 704.

[0090] In an embodiment, the sensor device 300 is coupled via its electrical contacts 314 to electrical contact pads 714 on the inner region 702I of the substrate 702. In one embodiment, the sensor device is coupled to the electrical contact pads 714 via a first seal 720A, which may be a metal seal formed via soldering or brazing, such as with a first brazing alloy. In certain embodiments, the sensor device is secured to the substrate such that the support structure (e.g., 302) of the sensor device (e.g., 300) is oriented parallel to the gas flow direction (e.g., 242). In certain embodiments, the sensor device may be secured to the substrate 702 such that the support structure of the sensor device is oriented perpendicular to the gas flow direction (not shown).

[0091] In one embodiment, the middle region 702M of the substrate 702 is coupled / secured to the housing 704 via a second seal 720B, which may be a metal seal, such as with a second braze alloy. In certain embodiments, the substrate 702 may be secured to the housing 704 via a hermetic seal to minimize vacuum and / or gas leakage from the processing chamber environment and / or gas channel 240 to the external environment.

[0092] Each of the first seal (720A) and the second seal (720B), when present, can independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, the brazing alloy used for all seals is the same. In other embodiments, two or more different brazing alloys may be used for different seals. In one embodiment, at least one of seals 720A or 720B comprises an Ag-Cu brazing alloy. It should be recognized that the terms "first seal," "second seal," and the like should not be construed as limiting with respect to the order of the various components constrained within the sensor assemblies described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assembly. Rather, these terms are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in conjunction with FIGS. 11A and 11B.

[0093] In some embodiments, the sensor assembly (e.g., sensor assembly 700) further has a non-conductive conformal coating on one or more surfaces or on at least a portion of the sensor assembly. In some embodiments, the coating covers some or all of the sensor device (e.g., 300). In some embodiments, the coating covers some or all of the sensor region 306 and / or interface region 304 of sensor device 300. In some embodiments, the coating covers some or all of the sensor region 306, including some or all of the sensing element 308. In other embodiments, the conformal coating covers the sensor region 306 without covering the sensing element 308. In some embodiments, the coating covers some or all of the substrate 702. In some embodiments, the coating covers some or all of the outer region 702O, the middle region 702M, and / or the inner region 702I. In some embodiments, the coating covers some or all of the inner region 702I, including some or all of the electrical contact pads 714. In some embodiments, the coating covers some or all of the middle region 702M. In some embodiments, the coating covers some or all of the various seals (e.g., first seal 720A and / or second seal 720B). In some embodiments, sensor assembly 700 is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device and the substrate), and then the assembled sensor assembly is coated such that the coating covers the portions of the sensor assembly that will be exposed to the gas flow when the sensor assembly is coupled into the gas flow channel. In some embodiments, the coating deposited on at least a portion of sensor assembly 700 may be similar to the coatings described herein above that are suitable for coating at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.). In certain embodiments, sensor assembly 700 remains completely uncoated.

[0094] 7E shows a front view of section AA of FIG. 7A. In certain embodiments, a housing (e.g., housing 704) can have a gas-side surface 760 and an opposing surface 770 opposite the gas-side surface. The housing 704 can be shaped as a gas flow channel similar to gas flow channel 240. The housing can have a diameter or width and / or height (if the housing has a shape other than a cylinder / tube) that is larger than the diameter of the gas flow channel (e.g., 240). The larger diameter or width and / or height of the housing 704 can be configured to provide space for the sensor assembly without restricting gas flow, resulting in minimal (or substantially zero) effect on the gas flow parameters measured by the sensor device.

[0095] The housing 704 can have at least one slot (e.g., slot 780B) formed therethrough that is shaped to receive a substrate (e.g., substrate 702). The substrate 702 can be inserted into the slot (e.g., slot 780B) such that an inner region 702I of the substrate extends from the gas-side surface 760 into, for example, the internal environment of a gas flow channel (e.g., gas flow channel 240). In certain embodiments, the substrate 702 can be inserted into the slot 780A in a cantilevered orientation and secured to the housing 704 at a middle region 702M of the substrate such that the inner region 702I of the substrate extends from the gas-side surface 760 into the internal environment of the gas flow channel, and the outer region 702O of the substrate extends from the opposite surface 770 to an outer region, as shown in the front view of section AA of FIG. 7E .

[0096] 8A and 8B , the housing 704 has a first slot 780A formed on a first end 765A (e.g., from the gas-side surface 760 to the opposite surface 770 opposite the gas-side surface) and a second slot 780B formed on an opposite second end 765B (e.g., from the gas-side surface 760 to the opposite surface 770 opposite the gas-side surface). Such a housing can receive a substrate 802, which can be similar to the substrate 702. In a specific embodiment, the substrate 802 is a multi-layer ceramic substrate. Similar to the substrates 502 and 702, the substrate 802 has the advantage that a hermetic seal is achieved between the ceramic layers of the multi-layer ceramic substrate with electrical contact pads formed between the layers. This hermetic seal reduces the number of locations where various components of the sensor assembly must be secured via metal seals (e.g., via brazing).

[0097] Ceramic substrate 802 may be made of any suitable plasma-resistant ceramic that can be formed into a suitable multilayer ceramic according to methods known to those skilled in the art, as described hereinabove in connection with substrate 502. Likewise, ceramic substrate 802 may be made of materials similar to those described hereinabove for substrate 502.

[0098] The multilayer ceramic substrate 802 can have a first end 802A and a second end 802B opposite the first end. The first end 802A of the substrate 802 can have a first outer region 802O1, an inner region 8021, and a first intermediate region 802M1 disposed between the first outer region 802O1 and the inner region 802I. The second end 802B of the substrate 802 can have a second outer region 802O2, the same inner region 802I, and a second intermediate region 802M2 disposed between the second outer region 802O2 and the inner region 802I. The multilayer ceramic substrate 802 can have electrical contact pads 814 formed between the layers of the multilayer ceramic substrate 802. Electrical contact pads 814 can extend completely through the multi-layer ceramic substrate 802 from a first end 802A to a second, opposite end 802B, as shown in the front view of cross section BB in FIG. 8B.

[0099] The multilayer ceramic substrate 802 may be secured to the housing 704 at a first intermediate region 802M1 and a second intermediate region 802M2. In certain embodiments, the multilayer ceramic substrate may be inserted into the housing 704 via a first slot 780A that extends completely through the entire diameter (or width) of the housing 704 to the second slot 708B. A first end 802A of the multilayer ceramic substrate 802 may be disposed through the first slot 780A, and a second, opposite end 802B of the multilayer ceramic substrate 802 may be disposed through the second, opposite slot 780B. In this configuration, a first outer region 802O1 of the substrate 802 may extend from the opposite surface 770 of the housing 704 at the first end 765A to the outer region at the first end. Further, in this configuration, a second outer region 802O2 of the substrate 802 can extend from the opposite surface 770 of the housing 704 at the second opposite end 765B to the outer region at the second opposite end. Further, in this configuration, an inner region 802I of the substrate 802 can extend from the gas-side surface 760 of the housing 704 at the first end 765A to the gas-side surface 760 of the housing 704 at the second end 765B. In certain embodiments, the substrate 802 can be secured to the housing via a metal seal, for example via brazing, to form a hermetic seal to minimize gas leakage from the processing chamber environment to the external environment (e.g., a first end 765A of the housing 704 is secured to a first intermediate region 802M1 of the substrate 802 and a second end 765B of the housing 704 is secured to a second intermediate region 802M2 of the substrate 802). The seal between the housing 704 and the substrate 802 (or between the housing 704 and the substrate 702) may be a gas-tight seal to prevent gas and / or vacuum leakage from the gas flow channels 240. In some embodiments, the seal is a metallic seal formed by, for example, brazing or soldering using any of the brazing alloys described hereinabove. As described and shown in further detail in connection with FIGS. 9A-9C and 10A-10D, various sealing configurations may be suitably used.

[0100] In the embodiment shown in FIGS. 8A-8B, the sensor device 300 may be bonded / anchored to the substrate 802 at the inner region 802I. As described in connection with the previously shown sensor assemblies, the sensor device 300 may be affixed to the substrate via a metal seal between the electrical contacts 314 (on the sensor device 300) and the electrical contact pads 814 on the substrate 802. The electrical contacts 314 on the sensor device, together with the electrical contact pads 814 on the substrate and one or more external devices (such as the processing device 230), form a closed circuit during operation. The electrical contact pads (e.g., 714) located between the layers of the multilayer ceramic substrate 802 may be of the same conductive material as the electrical contacts 314 on the sensor device. For example, in one embodiment, the electrical contact pads 814 are made of platinum.

[0101] The sensor device 300 may be secured to the substrate 802 with the support structure (e.g., 302) oriented parallel to the gas flow direction (e.g., 242). In certain embodiments, the sensor device is secured to the substrate 802 with the support structure of the sensor device oriented perpendicular to the gas flow direction (not shown).

[0102] In some embodiments, the sensor assembly shown in FIGS. 8A-8B further includes a non-conductive conformal coating on one or more surfaces or on at least a portion of the sensor assembly. In some embodiments, the coating covers some or all of the sensor device (e.g., 300). In some embodiments, the coating covers some or all of the sensor region 306 and / or interface region 304 of the sensor device 300. In some embodiments, the coating covers some or all of the sensor region 306, including some or all of the sensing element 308. In other embodiments, the conformal coating covers the sensor region 306 without covering the sensing element 308. In some embodiments, the coating covers some or all of the substrate 802. In some embodiments, the coating covers some or all of the outer regions 802O1 and 801O2, the middle regions 802M1 and 802M2, and / or the inner region 802I. In some embodiments, the coating covers some or all of the inner region 802I, including some or all of the electrical contact pads 814. In some embodiments, the coating covers some or all of the various seals (e.g., the first seal 820A between the sensor device 300 and the substrate 802, and / or the second seal 820B between the first intermediate region 802M2 of the substrate 802 and the first end 765A of the housing 704, and / or the third seal 820C between the second intermediate region 802M2 of the substrate 802 and the second end 765B of the housing 704). In some embodiments, the sensor assembly 800 is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device and the substrate), and then the assembled sensor assembly is coated with a coating to cover portions of the sensor assembly that will be exposed to gas flow when the sensor assembly is coupled into a gas flow channel.In some embodiments, the coating deposited over at least a portion of sensor assembly 800 may be similar to the coatings described herein above that are suitable for covering at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.). In certain embodiments, sensor assembly 800 remains completely uncovered.

[0103] It should be appreciated that the meanings of "first seal," "second seal," "third seal," etc. should not be construed as limiting with respect to the ordering of the various components within the sensor assemblies described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assemblies. Rather, these meanings are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in connection with FIGS. 11A and 11B.

[0104] As previously indicated, a substrate (e.g., 702 or 802) may be affixed to a housing (e.g., 704) at the intersection between the boundary of a slot through the housing (e.g., the boundary of slot 780A or slot 780B) and the boundary of the mid-region of the substrate (e.g., 702M, 802M1, or 802M2). However, in certain embodiments, the mid-region of the substrate and the slot through the housing may be shaped to allow face-to-face bonding between the two. While not intended to be limiting, it is believed that face-to-face bonding between the substrate (e.g., at the mid-region) and the housing reduces stresses that may occur during bonding. Exemplary such face-to-face bonding is shown in FIGS. 9A-9C and 10A-10D.

[0105] 9A shows a perspective view of a sensor assembly 900 according to an embodiment of the present disclosure. As can be seen in FIG. 9A , the sensor assembly 900 can have a housing 904, which can be similar to the housing 704. The housing 904 can further have a gas-side surface 960 and an opposing surface 970 opposite the gas-side surface. The housing 904 can further have a slot 980A therethrough. In certain embodiments, the housing 904 can have a tapered region at the boundary of the slot 980A configured to establish a flat surface at the boundary of the slot 980A, and the middle region 902M of the substrate 902 can be secured within the slot 980A in a parallel orientation.

[0106] 9B shows a perspective view of a multilayer ceramic substrate 902, in which the sensor device 300 is bonded to the multilayer ceramic substrate 902 at an inner region. Similar to the other multilayer ceramic substrates described herein above, the multilayer ceramic substrate 902 can be prepared by methods known to those skilled in the art. The multilayer ceramic 902 can have an inner region 902I (to which the sensor device 300 can be fixed), an outer region 902O, and an intermediate region 902M disposed between the inner region 902I and the outer region 902O. In certain embodiments, the intermediate region 902M has a greater thickness and / or length than the inner region 902I and / or the outer region 902O. In certain embodiments, the intermediate region 902M has a first surface 902M1 and a second surface 902M2 opposite the first surface. When the substrate 902 is secured to the housing 904, the first surface 902M1 may be proximate to an opposite surface 970 of the housing 904 and may be affixed to the opposite surface 970 of the housing 904 in a face-to-face configuration.

[0107] In certain embodiments, the shape of the substrate 902 is formed using multi-layer ceramic layers by methods known to those skilled in the art. In certain embodiments, a hermetic seal is achieved between the layers of the multi-layer ceramic substrate. In certain embodiments, electrical contact pads 914 are formed / incorporated between the layers of the multi-layer ceramic substrate 902 (extending completely through the entire substrate 902 from the outer region 902O to the inner region 902I), and the hermetic seal is maintained despite the presence of the electrical contact pads 914 between the layers.

[0108] Ceramic substrate 902 may be made of any suitable plasma-resistant ceramic that can be formed into a suitable multi-layer ceramic according to methods known to those skilled in the art, as described herein above in connection with substrate 502. Likewise, ceramic substrate 902 may be made of materials similar to those described herein above for substrate 502.

[0109] At least a portion or all of sensor assembly 900 may be covered with a protective coating already described for other sensor assemblies. The coating deposited on at least a portion of sensor assembly 900 may be similar to the coatings described herein above that are suitable for covering at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.). In certain embodiments, sensor assembly 900 may remain completely uncovered.

[0110] FIG. 9C shows a front view of cross section CC of FIG. 9A. As shown in FIG. 9C, sensor assembly 900 is similar to sensor assembly 700, except for the bonding between substrate 902 and housing 904. In sensor assembly 900, multilayer ceramic substrate 902, to which sensor device 300 is fixed (at inner region 902I) in a parallel orientation (with respect to gas flow 242), is inserted into slot 980A in a cantilever configuration (shown in FIG. 9C) until a first surface 902M1 of a middle region 902M of the substrate contacts (face-to-face with) the tapered boundary of slot 980A (located on the opposite surface 970 of housing 904). Substrate assembly 902 can then be secured to housing 904, for example, via a metal seal (such as with a brazing alloy) to form a hermetic seal to minimize leakage of gas and / or vacuum from gas channel 240 to the external environment.

[0111] Although not shown, sensor assembly 900 may be modified to have a substrate extending from one end of the housing to the opposite end of the housing, similar to sensor assembly 800. With such a modification, each end of the modified substrate may be secured to a corresponding end of the housing via similar face-to-face bonding as described in connection with sensor assembly 900.

[0112] FIG. 10A shows a perspective view of a sensor assembly 1000 according to an embodiment of the present disclosure. As can be seen in FIG. 10A , the sensor assembly 1000 can have a housing 1004, which can be similar to the housings 704 and 904. The housing 1004 can further have a gas-side surface 1060 and an opposing surface 1070 opposite the gas-side surface. The housing 1004 can further have a slot 1080A therethrough. In certain embodiments, the housing 1004 can have a tapered region at the boundary of the slot 1080A configured to establish a flat surface at the boundary of the slot 1080A, and the middle region 1002M of the substrate 1002 can be secured within the slot 1080A in a parallel orientation. 10A, the housing 1004 can have a region 1004M with square or rectangular flat sidewalls, and a middle region 1002M of the substrate 1002 can be affixed to the region 1004M in a parallel, face-to-face orientation. In certain embodiments, the housing 1004 can have tubular gas channels 1004C extending from two opposite sides of the region 1004M with square or rectangular flat sidewalls.

[0113] 10B shows a perspective view of a multilayer ceramic substrate 1002. Similar to the other multilayer ceramic substrates described herein above, the multilayer ceramic substrate 1002 can be prepared by methods known to those skilled in the art. The multilayer ceramic 1002 can have an inner region 1002I (to which the sensor device 300 can be fixed), an outer region 1002O, and an intermediate region 1002M disposed between the inner region 1002I and the outer region 1002O. In certain embodiments, the intermediate region 1002M has a greater thickness and / or length than the inner region 1002I and / or the outer region 1002O. In certain embodiments, the intermediate region 1002M is shaped as a disk with rounded ends (e.g., an oval or circle) and has a first surface 1002M1 and a second surface 1002M2 opposite the first surface. When the substrate 1002 is secured to the housing 1004, the first surface 1002M1 may be proximate to an opposite surface 1070 of the housing 1004 and may be affixed to the housing 1004 in a face-to-face configuration.

[0114] In certain embodiments, the shape of the substrate 1002 is formed using multiple ceramic layers by methods known to those skilled in the art. In certain embodiments, a hermetic seal is achieved between the layers of the multi-layer ceramic substrate. In certain embodiments, electrical contact pads 1014 are formed / incorporated between the layers of the multi-layer ceramic substrate 1002 (extending completely through the entire substrate 1002, from the outer region 1002O to the inner region 1002I), and the hermetic seal is maintained despite the presence of the electrical contact pads 1014 between the layers.

[0115] Ceramic substrate 1002 may be made of any suitable plasma-resistant ceramic that can be formed into a suitable multilayer ceramic according to methods known to those skilled in the art, as described herein above in connection with substrate 502. Likewise, ceramic substrate 1002 may be made of materials similar to those described herein above for substrate 502.

[0116] In certain embodiments, the sensor assembly 1000 further includes an adapter / flange 1300. The adapter / flange 1300 may be shaped as a flat plate with a ring defined through a central region of the flat plate, the ring configured to surround a portion of the ceramic substrate 1002. The adapter / flange 1300 may have a first side 1300S1 (e.g., the side facing the housing) and a second side 1300S2 (e.g., the side facing the substrate) opposite the first side. The adapter / flange 1300 may have a rounded border (e.g., an oval or circular border, or a rectangular shape with curved corners). The adapter / flange 1300 may be secured to the housing 1004, for example, near the location of the slot 1080A (e.g., around the border of the slot 1080A), for example, to the opposite surface 1070 of the housing 1004. For example, the flange / adapter 1300 may be welded to the housing 1004, for example via e-beam welding, so that a first side 1300S1 of the adapter / flange 1300 is proximate to the housing 1004 (e.g., near the opposing surface 1070 of the housing 1004), for example, as shown by numeral 1300D in FIG. 10D. The adapter / flange 1300 may be secured to the housing 1004 in a parallel, face-to-face configuration.

[0117] The adapter / flange 1300 may be made of a material having a thermal expansion coefficient between that of the multilayer ceramic substrate 1002 and that of the housing 1004. In certain embodiments, the housing 1004 has a first thermal expansion coefficient (CTE1), the substrate 1002 has a second thermal expansion coefficient (CTE2), and the adapter / flange 1300 has a third thermal expansion coefficient (CTE3). In certain embodiments, the CTE3 has a value between CTE1 and CTE2. For example, the housing 1004 may be made of stainless steel having a CTE1, the dielectric multilayer ceramic substrate may be made of ceramic having a CTE2, and the adapter / flange 1300 may be made of Kovar (nickel-cobalt-iron alloy) having a CTE3 between CTE1 and CTE2. In certain embodiments, the adapter / flange 1300 comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof. In certain embodiments, the substrate 1002 is secured to the adapter / flange 1300 such that the first flange 1200M1 can be proximate to the second side 1300S2 of the adapter / flange 1300 and can be secured to the second side 1300S2 of the adapter 1300 in a face-to-face configuration.

[0118] The substrate 1002 may be secured to the adapter / flange 1300 (if present) or to the housing 1004 (if the adapter / flange 1300 is not present) via a first metal seal 1300A, such as via brazing using any of the metal alloys described hereinabove or any other suitable metal alloy. In one embodiment, the substrate 1002 may be secured to the adapter / flange 1300 via brazing using an Al alloy.

[0119] In certain embodiments, a backup ring 1500 may also be disposed around a portion of the substrate 1002 between the flange 1300 and the housing 1004. The backup ring may be shaped as a flat plate with a ring defined in a central region of the flat plate, configured to surround a portion of the ceramic substrate 1002. The backup ring may have a side facing toward the housing and a side facing toward the substrate opposite the side facing toward the housing. In certain embodiments, the side facing toward the substrate of the backup ring may be secured to the side facing toward the housing of the flange / adapter 1300 via a second metal seal 1300B. The second metal seal 1300B may be a metal brazed seal formed using any of the metal alloys described hereinabove or any other suitable metal alloy. In certain embodiments, the ceramic backup ring 1500 is configured to reduce stress within a joint (such as the joint between the flange / adapter 1300 and the housing 1004). The backup ring 1500 may be secured to the flange / adapter 1300 and / or the housing 1004 via a parallel face-to-face arrangement.

[0120] The backup ring 1500 may be made of a material having a coefficient of thermal expansion between the coefficient of thermal expansion of the multilayer ceramic substrate 1002 and the coefficient of thermal expansion of the housing 1004. In certain embodiments, the backup ring 1500 is made of a ceramic material.

[0121] In certain embodiments, when the backup ring 1500 and the adapter / flange 1300 are secured to the substrate 1200, a sensor device (such as the sensor device 300) may be secured to an inner region of the substrate 1002 via the third seal 1300C. The substrate 1002, including the backup ring 1500, the adapter / flange 1300, and the sensor device 300, may then be inserted into the housing 1004, after which the adapter / flange 1300 is secured to the housing 1004 (e.g., via e-beam welding), thereby forming a hermetic seal to minimize leakage of vacuum and / or gas from the gas channel 240 to the external environment.

[0122] Each of the first seal 1300A, second seal 1300B, third seal 1300C, and optional fourth seal 1300D (if not welded), if present, can independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, the brazing alloy used for all seals is the same. In other embodiments, two or more different brazing alloys may be used for different seals. It should be recognized that the meanings of "first seal," "second seal," "third seal," "fourth seal," etc., should not be construed as limiting with respect to the order of the various components constrained within the sensor assemblies described herein, nor should they be construed as limiting with respect to the total number of seals within the sensor assembly. Rather, these meanings are merely used for convenience to distinguish one seal from another. Exemplary methods for manufacturing the various sensor assemblies described herein are described in more detail below in conjunction with FIGS. 11A and 11B.

[0123] At least a portion or all of sensor assembly 1000 may be covered with a protective coating already described for other sensor assemblies. The coating deposited on at least a portion of sensor assembly 1000 may be similar to the coatings described herein above that are suitable for covering at least a portion of sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.). In certain embodiments, sensor assembly 1000 may not be completely covered.

[0124] Figure 10C shows a front view of cross section CC of Figure 10A. As shown in Figure 10C, sensor assembly 1000 is similar to sensor assemblies 700 and 900, except for the bonding between substrate 1002 and housing 1004. In sensor assembly 1000, multilayer ceramic substrate 1002, to which sensor device 300 is fixed (at inner region 1002I), is inserted into slot 1080A in a cantilever configuration (shown in Figure 10C) in a parallel orientation (with respect to gas flow 242) until first surface 902M1 of intermediate region 1002M of substrate contacts (face-to-face) either a tapered boundary (not shown) of slot 1080A or second side 1300S2 of adapter / flange 1300 (which can be located on the opposite surface 1070 of housing 1004). The substrate assembly 1002 may then be secured to the adapter / flange 1300, for example via a metal seal (such as with a brazing alloy).

[0125] Although not shown, sensor assembly 1000 may be modified to extend the substrate from one end of the housing to the opposite end of the housing, similar to sensor assembly 800. Using such a modification, each end of the modified substrate may be secured to a respective corresponding end of the housing via similar face-to-face bonding via an intermediate adapter / flange as described in connection with sensor assembly 1000.

[0126] 11A illustrates a method 1100 of adapting a sensor device for use in a flow control device according to an embodiment of the present disclosure. At block 1110, a substrate is provided. The substrate can have an outer region, an inner region, and an intermediate region disposed between the outer and inner regions, and can further have electrical contact pads on at least the inner region of the substrate. Such exemplary substrates are shown in the sensor assemblies described hereinabove, such as substrates 402, 502, 602, 702, 802, 902, and 1002. In certain embodiments, prior to providing the substrate, the substrate can be machined to have the shapes described hereinabove or any other suitable shape. In certain embodiments, the electrical contact pads can be metallized into the inner region of the substrate. In certain embodiments, prior to providing the substrate, the substrate may be formed as a multi-layer ceramic substrate having any of the shapes described herein above (or any other suitable shape) with electrical contact pads formed between the layers of the multi-layer ceramic substrate, such that the electrical contact pads extend completely through the multi-layer ceramic substrate from the outer region to the inner region.

[0127] At block 1120, a sensor device, such as sensor device 300 illustrated in FIG. 3 or any other suitable device, may be coupled to the substrate at an interior region of the substrate. In some embodiments, the sensor device comprises a support structure comprising an interface region (e.g., interface region 304) at one end of the sensor device and a sensor region (e.g., sensor region 306) at an opposite end of the sensor device. The sensor region may have a free-standing sensing element (e.g., sensing element 308) suspended at the sensor region. The sensor device may further have electrical contacts (e.g., electrical contact 314) extending completely through the length of the elongated support structure from the sensing element to the top of the interface region. The sensor device may be secured / coupled to the substrate such that the electrical contacts on the sensor device contact electrical contact pads on the substrate to establish a continuous, closed electrical circuit for transmitting a signal from the sensor device to a processing device (e.g., processing device 230).

[0128] In certain embodiments, the sensor device may be secured to the substrate by forming a first seal between an electrical contact pad (e.g., 414, 514, 614, 714, 814, 914, or 1014) on the substrate and an electrical contact (e.g., 314) on the sensor device. In certain embodiments, the sensor device in any of the sensor assemblies contemplated herein may be secured to the substrate by brazing (or any other chemical mode of attaching the sensor device to the substrate). In certain embodiments, the sensor device in any of the sensor assemblies contemplated herein may be secured to the substrate via a heat source (e.g., via laser welding). The sensor device may be secured to the substrate in a perpendicular orientation (e.g., in sensor assemblies 400 and 500) or a parallel orientation (e.g., in sensor assemblies 600, 700, 800, 900, and 1000).

[0129] In certain embodiments in which the substrate has a conductive pin that extends completely through the outer and middle regions of the substrate and into at least a portion of the inner region of the substrate (e.g., substrates 402 and 602), the method may further include securing the conductive pin to an electrical contact pad at the inner region of the substrate (e.g., as described for sensor assemblies 400 and 600), for example, using a third metal seal (e.g., via brazing).

[0130] At block 1130, a substrate is inserted into a slot in a housing (such as any of housings 404, 504, 604, 704, 904, or 1004 described herein above) so that an inner region of the substrate extends from the gas-side surface of the housing. In certain embodiments, the substrate is then coupled / secured to the housing with a second seal (e.g., via soldering and / or brazing with an appropriate brazing alloy) to form a sensor assembly. In certain embodiments, the substrate may be secured to the housing at an outer region of the substrate, as shown in sensor assemblies 400, 500, and 600. In certain embodiments, the substrate may be secured to the housing in a cantilevered configuration at a mid-region of the substrate, as shown in sensor assemblies 700 and 900. In certain embodiments, the substrate may be inserted into two slots at two opposite ends of the housing in an extended configuration and coupled / secured to the housing at two mid-regions of the substrate, as shown in sensor assembly 800. In certain embodiments, the substrate may be secured to the housing via a face-to-face arrangement at a mid-region of the substrate, as shown in sensor assembly 900. In certain embodiments, the substrate may be secured to the adapter / flange via a face-to-face arrangement at a mid-region of the substrate, and the adapter / flange may be coupled (e.g., welded) to the housing, as shown in sensor assembly 100 and as described in more detail in connection with FIG.

[0131] In certain embodiments, forming one or more of the metal seals described herein (e.g., the first seal, the second seal, the third seal, and any additional metal seals) can include brazing one component to another (e.g., brazing a sensor device to a substrate, brazing a substrate to a housing, or brazing a conductor pin to an electrical contact pad). The brazing alloy for any of the seals can independently include an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof. In certain embodiments, a separate o-ring can be disposed between the substrate and the housing (optionally, a separate cap configured to engage or compress the o-ring can be disposed between the substrate and the housing), thereby reinforcing the hermetic seal between the substrate and the housing. In certain embodiments, the seal provides an airtight seal to minimize leakage of vacuum and / or gas from the gas channel 240 to the external environment (e.g., to minimize leakage within the interface between the substrate and the housing and / or to minimize leakage through pin holes through which the conductive pins can pass).

[0132] At block 1140, a conformal coating may be deposited over the sensor assembly to cover at least a portion of the sensor assembly. In some embodiments, the conformal coating is a non-conductive material, such as a non-conductive ceramic material. In some embodiments, the conformal coating covers at least a portion of the sensing element 308. In other embodiments, the conformal coating covers the sensor area and does not cover or minimally covers the sensing element. In some embodiments, the coating covers some or all of the substrate (including an inner region of the base, one or more middle regions, and one or more outer regions). In some embodiments, the coating covers some or all of the electrical contacts on the substrate. In some embodiments, the coating covers some or all of the conductor pins extending from the substrate. In some embodiments, the coating covers some or all of the various seals (e.g., seals between the substrate and the sensor device, seals between the substrate and the conductor pins, seals between the conductor pins and electrical contact pads on the substrate, seals between the substrate and the housing, seals between the substrate and the adapter / flange, etc.). In some embodiments, the sensor assembly is first assembled to form electrical contacts between all components of the sensor assembly (e.g., between the sensor device and the substrate and / or between the substrate and conductive pins, if present), and then the assembled sensor assembly is coated such that the coating covers the portions of the sensor assembly that will be exposed to the gas flow when the sensor assembly is coupled into the gas flow channel. In some embodiments, the coating deposited on at least a portion of the sensor assembly may be similar to the coatings described herein above that are suitable for coating at least a portion of the sensor assembly 400 (e.g., similar in deposition technique, coating composition / material, and / or coating uniformity, conformality, porosity, architecture, etc.). In certain embodiments, the sensor assembly may remain completely uncoated.

[0133] In some embodiments, the conformal coating is deposited using one or more of ALD, IAD, LPPS, CVD, PS-CVD, or sputtering. In some embodiments, the conformal coating is deposited using one or more of Y2O3, YZrO, Y x Zr y O z , YZrOF, Y3Al5O 12 , Y4Al2O9, YF3, Y x O y F z , YOF, Er2O3, Er3Al5O 12 , ErF3, E x O y F z , ErOF, La2O3, Lu2O3, Sc2O3, ScF3, ScOF, Gd2O3, Sm2O3, Dy2O3, Y2O3-ZrO2 solid solution, ceramics including Y2Al4O9 and Y2O3-ZrO2 solid solution, or combinations thereof. In some embodiments, the conformal coating comprises Al2O3. In some embodiments, the conformal coating comprises Al2O3 deposited by ALD. In some embodiments, the conformal coating comprises multiple layers. In some embodiments, the conformal coating has a thickness of about 10 nanometers to about 500 nanometers, or any subrange or single value therein.

[0134] 10D follows method 1200 as shown as a flowchart in FIG. 11B and as described in FIG. 11C. First, via block 1210, a substrate such as substrate 1002 is provided, comprising outer region 1002O, inner region 1002I, and middle region 1002M (disposed between outer region 1002O and inner region 1002I). Thereafter, via block 1220, a metal flange / adapter 1300 may be secured to the substrate via a first seal 1300A in a parallel, face-to-face configuration between a side of flange / adapter 1300 facing the substrate and a first side of the middle region of substrate 1002M1. Block 1230 then allows the backup ceramic ring 1500 to be secured via the second seal 1300B in a parallel, face-to-face configuration between the side of the backup ceramic ring facing the substrate and the side of the flange / adapter 1300 facing the housing.

[0135] Thereafter, per block 1240, a sensor device (e.g., sensor device 300) may be secured to the inner region 1002I of the substrate 1002 such that electrical contacts on the sensor device contact electrical contact pads on the substrate to establish a continuous, closed electrical circuit for transmitting a signal from the sensor device to a processing device (e.g., processing device 230). In certain embodiments, the sensor device may be secured to the substrate by forming a third seal 1300C between the electrical contact pads on the substrate and the electrical contacts on the sensor device. The sensor device may be secured to the substrate in a vertical orientation or a parallel orientation.

[0136] Thereafter, block 1250 may insert substrate 1002 (which is assembled with metal flange 1300 double-brazed to the substrate on one side and to ceramic backup ring 1500 on the other side and includes a sensor device) into a slot in a housing (such as 1004 described herein above) so that block 1250 causes an inner region of the substrate to extend from the gas-side surface of the housing. In certain embodiments, block 1250 then couples / secures metal flange 1300 to the housing with fourth seal 1300D, which may be welded (e.g., e-beam welded), soldered, and / or brazed using a suitable brazing alloy, thereby forming a sensor assembly (such as sensor assembly 1000). In certain embodiments, the substrate may be secured to the housing in a cantilevered configuration at a mid-region of the substrate. In certain embodiments, the substrate may be inserted into two slots at two opposite ends of the housing in an extended configuration and coupled / secure to the housing at two mid-regions of the substrate. In certain embodiments, at least a portion of a substrate assembly assembled according to method 1200 may be covered, as described hereinabove in connection with block 1140 of method 1100 and as described throughout this description in connection with various sensor assemblies. In certain embodiments, a substrate assembly assembled according to method 1200 may remain completely uncovered.

[0137] 11A or 1200, the sensor assembly may then be installed in a gas flow channel or attached (e.g., welded) to tubing, for example, through appropriate fittings (e.g., one or more VCR fittings). The sensor assembly may be further connected to one or more external devices (e.g., processing device 230) to form a closed gas flow measurement and control circuit. In certain embodiments, before connecting the sensor assembly to one or more external devices, certain portions of the sensor assembly (e.g., external portions of the conductor pins in sensor assembly 600) may be at least partially uncovered (e.g., laser etched), thereby exposing conductive portions that may be connected to an external device to form a closed electrical circuit during operation.

[0138] For simplicity of explanation, the methods of the present disclosure are depicted and described as a series of acts. However, unless otherwise specified, acts according to the present disclosure may occur in various orders and / or simultaneously, and other acts are not presented or described herein. Moreover, not all acts shown may be required to implement a method in accordance with the disclosed subject matter. In addition, those skilled in the art will understand and appreciate that the methods may alternatively be represented as a series of interrelated states via a state diagram or events. Additionally, it should be appreciated that the methods disclosed herein may be stored on an article of manufacture to aid in the transport and transmission of instructions for implementing the method to a computing device. As used herein, the term "article of manufacture" is intended to encompass a computer program accessible from any computer-readable device or storage medium.

[0139] 12 shows a diagrammatic representation of a machine, an exemplary form of computer system 1200, within which a set of instructions (e.g., causing the machine to perform any one or more of the methodologies discussed herein) may be executed. In alternative implementations, the machine may be connected (e.g., networked) to other machines over a LAN, a WAN, an intranet, an extranet, or the Internet. The machine may operate within the processing capacity of a server or client machine in a client-server network environment, or may operate as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be a personal computer (PC), a tablet PC, a PDA, a mobile phone, a web appliance, a server, a network router, switch, or bridge, or any machine capable of executing (sequentially or otherwise) a set of instructions that specify actions to be taken by the machine. Additionally, while only a single machine is shown, the term "machine" shall also be considered to include any collection of machines that individually or collectively execute a set (or sets) of instructions to implement any one or more of the methodologies discussed herein. Some or all of the components of computer system 1200 may be utilized by or illustrative of any of the electronic components described herein (e.g., processing device 230 or any electronic components utilized in connection with the operation of chamber 101 or flow regulator 210).

[0140] The exemplary computer system 1200 includes a processing device (processor) 1202, a main memory 1204 (e.g., ROM, flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 1206 (e.g., flash memory, static random access memory (SRAM), etc.), and a data storage device 1200 that communicate with each other via a bus 1210.

[0141] Processor 1202 represents one or more general-purpose processing devices, such as a microprocessor or central processing unit. More specifically, processor 1202 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or a processor implementing other instruction sets or a combination of instruction sets. Processor 1202 may also be one or more special-purpose processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), or a network processor. Processor 1202 is configured to execute instructions 1240 to perform the operations and steps discussed herein.

[0142] Computer system 1200 may further include a network interface device 1208. Computer system 1200 may further include a video display unit 1212 (e.g., a liquid crystal display (LCD), a cathode ray tube (CRT), or a touch screen), an alphanumeric input device 1214 (e.g., a keyboard), a cursor control device 1216 (e.g., a mouse), and a signal generating device 1222 (e.g., a speaker).

[0143] Power device 1218 can monitor the power level of a battery used to power computer system 1200 or one or more of the components of computer system 1200. Power device 1218 can provide one or more interfaces to provide an indication of the power level, a remaining time window before an outage of computer system 1200 or one or more components of computer system 1200, power consumption, an indicator of whether the computer system is utilizing external or battery power, or other power-related information. In some implementations, indicators related to power device 1218 can be remotely accessible (e.g., accessible from a remote backup management module via a network connection). In some implementations, the battery utilized by power device 1218 can be an uninterruptible power supply (UPS) locally connected to computer system 1200 or remote from computer system 1200. In such implementations, power device 1218 can provide information regarding the power level of the UPS.

[0144] Data storage device 1220 may have computer-readable storage medium 1224 (non-transitory computer-readable storage medium) on which one or more sets of instructions 1240 (e.g., software) embodying any one or more of the methodologies or functions described herein are stored. These instructions 1240 may also reside, completely or at least partially, within main memory 1204 and / or processor 1202 during execution of the instructions 1240 by computer system 1200, with main memory 1204 and processor 1202 also constituting computer-readable storage media. The instructions 1240 may also be transmitted or received over network 1230 via network interface device 1208. While the computer-readable storage medium 1224 is shown as a single medium in the illustrated implementation, it should be understood that the computer-readable storage medium 1224 may comprise a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store one or more sets of instructions 1240.

[0145] Numerous details are set forth in the above description. However, it will be apparent to one skilled in the art having the benefit of this disclosure that the present disclosure may be practiced without these specific details. While specific embodiments have been described herein, it should be understood that these are presented by way of example only, and not limitation. The breadth and scope of the present application should not be limited by any embodiment described herein, but should be defined only in accordance with the following later-filed claims and their equivalents. Indeed, various other implementations and modifications of the present disclosure, in addition to those described herein, will be apparent to those skilled in the art from the above description and accompanying drawings. Accordingly, such other implementations and modifications are intended to be within the scope of the present disclosure.

[0146] Reference has been made to the accompanying drawings that form a part of this description, which show, by way of example, specific embodiments. While these disclosed embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, it should be understood that these examples are not limiting, and thus, other embodiments may be used, and modifications may be made to the disclosed embodiments, without departing from the spirit and scope of the invention. For example, the blocks of the methods shown and described herein are not necessarily performed in the order shown in some other embodiments. Additionally, in some other embodiments, the disclosed methods may include more or fewer blocks than those described. As another example, some blocks described herein as separate blocks may be combined in some other embodiments. Conversely, a block that may be described herein as a single block may be implemented as multiple blocks in some other embodiments. Additionally, the conjunction "or" is intended herein to be inclusive where appropriate, unless otherwise noted; i.e., the phrase "A, B, or C" is intended to include the possibilities of "A," "B," "C," "A and B," "B and C," "A and C," and "A, B, and C."

[0147] The word "embodiment" or "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as an "embodiment" or "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word "embodiment" or "exemplary" is intended to present a concept in a concrete manner. When the term "about" or "approximately" is used herein, it is intended to mean that the nominal value presented is accurate to within ±10%.

[0148] Additionally, the articles "a" and "an," as used in this specification and the appended claims, should generally be construed to mean "one or more" unless otherwise specified or unless the singular form is clearly intended from the context. References throughout this specification to "an embodiment," "one embodiment," "some embodiments," or "particular embodiments" indicate that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrases "an embodiment," "one embodiment," "some embodiments," or "particular embodiments" in various places throughout this specification do not necessarily all refer to the same embodiment.

[0149] Some portions of the detailed descriptions may be presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. These steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0150] It should be noted, however, that all of these or similar terms are associated with the appropriate physical quantities and are merely convenient notations applied to these quantities. Unless otherwise specified as is clear from the discussion below, discussions utilizing terms such as "receive," "retrieve," "transmit," "calculate," "generate," "process," "reprocess," "add," "subtract," "multiply," "divide," "optimize," "calibrate," "detect," "implement," "analyze," "determine," "enable," "identify," "modify," "convert," "apply," "cause," "store," or "compare" refer to the actions and processes of a computer system or similar electronic computing device that manipulates and converts data represented as physical quantities (e.g., electronic physical quantities) in the computer system's registers and memory into other data similarly represented as physical quantities in the computer system's memory or registers or in other such information storage, transmission, or display devices.

[0151] Moreover, while the present disclosure has been described in the context of particular implementations in particular environments for particular purposes, those skilled in the art will recognize that the usefulness of the present disclosure is not so limited and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. A sensor assembly comprising: a substrate comprising an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, the substrate further comprising electrical contact pads overlying at least the inner region; a housing coupled to the substrate at the outer region to provide a hermetic seal; a sensor device coupled to the substrate via the electrical contact pads at the interior region; Equipped with a sensor assembly, wherein the sensor device is coupled to the electrical contact pads via a first seal, the substrate is fixed to the housing at the outer region via a second seal, an O-ring is disposed between the substrate and the housing, the substrate is a multilayer ceramic, the electrical contact pads are formed between layers of the multilayer ceramic substrate, and the electrical contact pads extend completely through the multilayer ceramic substrate from the outer region to the inner region.

2. The sensor assembly of claim 1 , further comprising a conformal coating deposited on at least a portion of the sensor assembly.

3. 10. The sensor assembly of claim 1, wherein the sensor device comprises a free-standing sensing element coupled to a support structure, the sensor device being fixed to the substrate such that the support structure is perpendicular to a gas flow direction.

4. 10. The sensor assembly of claim 1, wherein the sensor device comprises a free-standing sensing element coupled to a support structure, the sensor device being fixed to the substrate such that the support structure is parallel to a gas flow direction.

5. 2. The sensor assembly of claim 1, wherein the housing comprises a gas-side surface and an opposing surface opposite the gas-side surface, the housing having a slot formed therethrough, and the substrate is disposed within the slot such that the inner region of the substrate extends from the gas-side surface.

6. 2. The sensor assembly of claim 1, wherein the substrate is machined sapphire and the electrical contact pads are metallized in the interior region.

7. 7. The sensor assembly of claim 6, further comprising a conductive pin extending completely through the outer region and the intermediate region of the substrate and into at least a portion of the inner region of the substrate, the conductive pin being secured to the electrical contact pad disposed in the inner region via a third seal.

8. the first seal, the second seal, and the third seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads and the conductive pins comprise one or more conductive metals; The sensor assembly of claim 7, wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

9. the first seal and the second seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads comprise one or more conductive metals; The sensor assembly of claim 1 , wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

10. 1. A sensor assembly comprising: a multilayer ceramic substrate comprising an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, the multilayer ceramic substrate comprising electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the outer region to the inner region; a housing coupled to the substrate at the intermediate region to form a hermetic seal; a sensor device coupled to the substrate via the electrical contact pads at the interior region; A sensor assembly comprising:

11. The sensor assembly of claim 10 , further comprising a conformal coating deposited on at least a portion of the sensor assembly.

12. 11. The sensor assembly of claim 10, wherein the sensor device comprises a free-standing sensing element coupled to a support structure, the sensor device being fixed to the substrate such that the support structure is parallel to a gas flow direction.

13. 11. The sensor assembly of claim 10, wherein the housing comprises a gas-side surface and an opposing surface opposite the gas-side surface, the housing having a slot formed therethrough, the substrate being disposed within the slot in a cantilevered orientation such that the inner region of the substrate extends from the gas-side surface and the outer region of the substrate extends from the opposing surface to an exterior region.

14. 14. The sensor assembly of claim 13, wherein the intermediate region of the substrate comprises a first surface and a second surface opposite the first surface, the first surface being secured to the opposite surface of the housing in a face-to-face configuration, and an O-ring being disposed between the substrate and the housing.

15. 15. The sensor assembly of claim 14, wherein the sensor device is coupled to the electrical contact pads via a first seal, and the first surface is secured to the opposing surface of the housing via a second seal.

16. the first seal and the second seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads comprise one or more conductive metals; The sensor assembly of claim 15, wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

17. The sensor assembly of claim 14 further comprising a flange secured to the opposing surface of the housing.

18. 18. The sensor assembly of claim 17, wherein the sensor device is coupled to the electrical contact pads via a first seal, the flange is secured to the opposing surface of the housing using welding, and the first surface is secured to the flange via a second seal.

19. 20. The sensor assembly of claim 18, wherein the housing has a first coefficient of thermal expansion (CTE1), the substrate has a second coefficient of thermal expansion (CTE2), and the flange has a third coefficient of thermal expansion (CTE3), CTE3 being between CTE1 and CTE2.

20. 20. The sensor assembly of claim 18, further comprising a backup ring disposed between the flange and the opposing surface of the housing, the backup ring having a surface facing toward the housing and a surface facing toward the flange opposite the surface facing toward the housing, the flange being secured to the surface of the backup ring facing toward the flange via a third seal.

21. the first seal, the second seal, and the third seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads comprise one or more conductive metals; the housing and the flange independently comprise stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof; the backup ring comprises ceramic; 21. The sensor assembly of claim 20.

22. 1. A sensor assembly comprising:

1. A multilayer ceramic substrate having a first end and a second end opposite the first end, the first end portion comprises a first outer region, an inner region, and a first intermediate region disposed between the first outer region and the inner region; the second end portion comprises a second outer region and a second intermediate region disposed between the second outer region and the inner region; the multilayer ceramic substrate including electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the first end to the second end; a multilayer ceramic substrate; a housing coupled to the multilayer ceramic substrate at the first intermediate region and the second intermediate region to form a hermetic seal; a sensor device coupled to the substrate via the electrical contact pads at the interior region; a conformal coating deposited on at least a portion of the sensor assembly; A sensor assembly comprising:

23. 23. The sensor assembly of claim 22, wherein the housing comprises a gas-side surface and an opposing surface opposite the gas-side surface, the housing having a first slot formed therethrough at a first end and a second slot formed therethrough at an opposite second end, the first end of the substrate being disposed through the first slot and the second end of the substrate being disposed through the second slot.

24. 1. A method of manufacturing a sensor assembly, the method comprising: providing a substrate comprising an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, the substrate further comprising electrical contact pads overlying at least the inner region; coupling a sensor device to the substrate at the interior region; coupling the substrate to a housing at the exterior region to form a hermetic seal; depositing a conformal coating on at least a portion of the sensor assembly; Including, The method wherein the conformal coating is deposited using an atomic layer deposition process, and the conformal coating comprises Al 2 O 3 .

25. securing the sensor device to the substrate by forming a first seal between the electrical contact pads on the substrate and electrical contacts on the sensor device, the sensor device comprising a free-standing sensing element coupled to a support structure, the sensor device being secured to the substrate such that the support structure is perpendicular to a gas flow direction; securing the substrate to the housing by forming a second seal between the substrate and the housing; 25. The method of claim 24, further comprising:

26. 26. The method of claim 25, wherein the substrate comprises a conductive pin extending completely through the outer region and the middle region of the substrate and into at least a portion of the inner region of the substrate, the method further comprising fixing the conductive pin to the electrical contact pad disposed on the bottom region via a third seal.

27. 27. The method of claim 26, wherein forming one or more of the first seal, the second seal, or the third seal comprises brazing the sensor device to the substrate, brazing the substrate to the housing, or brazing conductive pins to the electrical contact pads, respectively.

28. the first seal, the second seal, and the third seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads and the conductive pins independently comprise one or more conductive metals; 28. The method of claim 27, wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

29. Prior to providing the substrate, machining the substrate, wherein the substrate is sapphire; metallizing electrical contact pads on the interior region of the substrate; 25. The method of claim 24, further comprising:

30. Prior to providing the substrate, forming a multilayer ceramic substrate with electrical contact pads formed between layers of the multilayer ceramic substrate, such that the electrical contact pads extend completely through the multilayer ceramic substrate from the outer region to the inner region; 26. The method of claim 25, further comprising:

31. 31. The method of claim 30, wherein forming one or more of the first seal or the second seal comprises brazing the sensor device to the substrate or brazing the substrate to the housing, respectively.

32. the first seal and the second seal independently comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au—Ni alloy, a Ni—Pd alloy, a Ni—Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads comprise one or more conductive metals; The method of claim 31 , wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

33. 25. The method of claim 24, wherein the housing comprises a gas-side surface and an opposing surface opposite the gas-side surface, the housing having a slot formed therethrough, the method further comprising inserting the substrate coupled to the sensor device into the slot formed therethrough before coupling the substrate to the housing at the outer region, such that the inner region of the substrate extends from the gas-side surface.

34. 1. A method of manufacturing a sensor assembly, comprising: providing a multilayer ceramic substrate comprising an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, the multilayer ceramic substrate comprising electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the outer region to the inner region; coupling a sensor device to the electrical contact pads at the interior region of the multilayer ceramic substrate; inserting the multilayer ceramic substrate coupled to the sensor device into a housing; bonding the multilayer ceramic substrate to the housing at the intermediate region such that the substrate is configured to form a hermetic seal in a cantilevered position; A method comprising:

35. 35. The method of claim 34, further comprising depositing a conformal coating on at least a portion of the sensor assembly.

36. The conformal coating is deposited using an atomic layer deposition process, and the conformal coating is Al ２ O ３ 36. The method of claim 35, comprising:

37. prior to bonding a sensor device to the electrical contact pads at the interior region of the multilayer ceramic substrate; securing a side of the flange facing the substrate to a first surface of the intermediate region of the substrate; fixing the side of the flange facing the housing to the side of the backup ring facing the substrate via a second seal; 37. The method of claim 36, further comprising:

38. coupling a sensor device to the electrical contact pads at the interior region of the multilayer ceramic substrate; and securing the sensor device to the substrate by forming a third seal between the electrical contact pads at the inner region of the substrate and electrical contacts on the sensor device, the sensor device comprising a free-standing sensing element coupled to a support structure, the sensor device being secured to the substrate with the support structure oriented parallel to the gas flow direction.

38. The method of claim 37, comprising:

39. inserting the multilayer ceramic substrate coupled to the sensor device into a housing; Inserting the substrate assembled with the sensor device, the backup ring, and the flange into the housing.

38. The method of claim 37, comprising:

40. coupling the multilayer ceramic substrate to the housing at the intermediate region; securing the flange to the housing by forming a fourth seal between the flange and the housing at the intermediate region of the base plate, wherein securing the flange to the housing includes welding the flange to the housing. Including, the housing has a gas-side surface and an opposite surface opposite the gas-side surface, and the side of the flange facing the housing is fixed to the opposite surface of the housing via a parallel facing arrangement; 38. The method of claim 37.

41. The second seal and the third seal, independently, comprise an Al alloy, an Ag alloy, an Au alloy, a Ni alloy, a Si alloy, an Au-Ni alloy, a Ni-Pd alloy, a Ni-Y alloy, a Ti alloy, or a combination thereof; the electrical contact pads comprise one or more conductive metals; 39. The method of claim 38, wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-iron alloy, or a combination thereof.

42. 1. A method for manufacturing a sensor assembly, comprising: A multilayer ceramic substrate is provided, comprising: a first end, a second end opposite the first end, and an interior region between the first end and the second end, the first end portion comprises a first outer region and a first intermediate region disposed between the first outer region and the inner region; the second end portion comprises a second outer region and a second intermediate region disposed between the second outer region and the inner region; the multilayer ceramic substrate including electrical contact pads formed between layers of the multilayer ceramic substrate, the electrical contact pads extending completely through the multilayer ceramic substrate from the first end to the second end; providing a multilayer ceramic substrate; coupling a sensor device to the electrical contact pads at the interior region of the multilayer ceramic substrate; inserting the multilayer ceramic substrate coupled to the sensor device into a housing; bonding the multilayer ceramic substrate to the housing at the first intermediate region and the second intermediate region such that the substrate extends from one end of the housing to a second, opposite end of the housing to form a hermetic seal; depositing a conformal coating over at least a portion of the sensor assembly; A method comprising:

43. A flow control device, a gas flow channel defining a gas flow path; a flow control valve configured to regulate gas flow within the gas flow channel; a sensor assembly coupled to the gas flow channel, the sensor assembly comprising: a substrate comprising an outer region, an inner region, and an intermediate region disposed between the outer region and the inner region, and further comprising electrical contact pads on at least the inner region; a housing coupled to the substrate at the intermediate region or the outer region to form a hermetic seal; a sensor device coupled to the substrate at the inner region via the electrical contact pads, the sensor device coupled to the electrical contact pads via a first seal, the substrate secured to the housing at the outer region via a second seal, an o-ring disposed between the substrate and the housing, the substrate being a multilayer ceramic, the electrical contact pads formed between layers of the multilayer ceramic substrate, and the electrical contact pads extending completely through the multilayer ceramic substrate from the outer region to the inner region; and a conformal coating deposited over at least a portion of the sensor assembly; a sensor assembly comprising: a processing device operably coupled to the flow regulation valve and the sensor device and configured to adjust the flow regulation valve based on a signal received from the sensor device; A flow control device comprising:

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