Integration of capacitive sensing data for plasma chamber state monitoring

Abstract

To provide capacitive sensors and capacitive sensing data integration for plasma chamber condition monitoring.SOLUTION: A plasma chamber monitoring system 250 includes a plurality of capacitive sensors 254A-254D each including a capacitance digital converter, and an applied process server 276 coupled to capacitance digital converter outputs. The applied process server includes a system software. The capacitance digital converter includes: an isolation interface 262 coupled to the plurality of capacitive sensors; a power supply 264 coupled to the isolation interface; a field-programmable gate-array firmware 268 coupled to the isolation interface; and an application-specific integrated circuit 272 coupled to the field-programmable gate-array firmware.SELECTED DRAWING: Figure 2B

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Patent Application No. 16 / 812,081, filed on March 6, 2020, the entire content of which is incorporated herein by reference.

[0002] Embodiments of the present disclosure relate to the field of plasma chamber state monitoring, and more particularly to capacitive sensing data integration for plasma chamber state monitoring.

Background Art

[0003] The manufacture of microelectronic devices, display devices, microelectromechanical systems (MEMS), etc. requires the use of one or more processing chambers. For example, to manufacture various devices, processing chambers such as, but not limited to, plasma etching chambers, plasma chemical vapor deposition chambers, physical vapor deposition chambers, plasma processing chambers, or ion implantation chambers may be used. As the critical dimensions are scaled down in such devices, the need for uniform processing conditions (e.g., uniformity across a single substrate, uniformity between different lots of substrates, and uniformity between chambers within a facility) has become increasingly important in high - volume manufacturing (HVM) environments.

[0004] Due to many different causes, processing non - uniformity occurs. One such cause is the state of the chamber itself. That is, when a substrate is processed within the chamber, the chamber environment can change. For example, in an etching process, etching by - products can be deposited on the inner surface of the chamber as a result of a redeposition process. As a redeposition layer accumulates on the inner surface of the chamber, the plasma chemistry can change in subsequent repetitions of the process recipe, potentially causing a process drift.

[0005] To counteract process drift, the processing chamber may be cleaned periodically. In-situ chamber cleaning (ICC) may be performed to reset the chamber state. Currently, ICC is primarily policy-based; that is, a set policy is executed to clean the processing chamber. Some ICCs may use optical emission spectrometry (OES) systems to determine the endpoint of the process policy. However, there is no way to directly measure the state of the internal surface of the processing chamber (e.g., the thickness of the redeposited layer, the thickness of the seasoning layer, etc.).

[0006] The processing chamber may be opened to manually clean parts of it or to replace worn consumables inside. However, opening the processing chamber results in considerable downtime, as it needs to be pumped back to the desired vacuum pressure, seasoned, and re-examined before production substrates can be processed. The processing chamber may be opened at predetermined intervals (e.g., after a certain number of substrates have been processed) or after an excursion is detected. Relying on predetermined intervals can result in opening the chamber too frequently, thus reducing throughput. If an excursion is detected, correction of the chamber condition is performed after damage to the production substrates has already occurred, thus reducing yield. [Overview of the Initiative]

[0007] Embodiments of this disclosure include capacitive sensing data integration for plasma chamber state monitoring.

[0008] In the embodiment, the plasma chamber monitoring system includes a plurality of capacitive sensors, a capacitive digital converter, and an application process server connected to the capacitive digital converter, the application process server including system software. The capacitive digital converter includes an isolation interface connected to the plurality of capacitive sensors, a power supply connected to the isolation interface, field programmable gate array firmware connected to the isolation interface, and an application-specific integrated circuit connected to the field programmable gate array firmware.

[0009] In another embodiment, the interconnection for the plasma chamber monitoring system includes a first connector for connecting to a capacitive digital converter of a capacitive sensor module, a second connector for connecting to electronic equipment and an external power supply, and a shielded cable connected to and between the first and second connectors. The shielded cable includes a shielding metal for physically connecting the interconnection to the frame of the plasma chamber, power lines housed within the shielding metal, ground lines housed within the shielding metal, and one or more communication lines housed within the shielding metal.

[0010] In another embodiment, a method for integrating data for plasma chamber state monitoring includes streaming data from a capacitive sensor module to a data server. The data includes capacity data and temperature data. This method also includes collecting data on an application process server. This method also includes correlating the data with one or more process policy operations. This method also includes synchronizing the capacitive sensor module with one or more process policy operations. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing a conventional plasma chamber monitoring system. [Figure 2A]This is a schematic diagram showing a plasma chamber monitoring system according to an embodiment of the present disclosure. [Figure 2B] This is a schematic diagram showing a plasma chamber monitoring system according to another embodiment of the present disclosure. [Figure 3] This disclosure illustrates an interconnection for a plasma chamber monitoring system according to an embodiment of this disclosure. [Figure 4] This is a schematic diagram showing plasma chamber monitoring hardware according to another embodiment of the present disclosure. [Figure 5A] This is a plot of signal data and capacitance and temperature data including noise, according to an embodiment of the present disclosure. [Figure 5B] Figure 5A shows the volume and temperature data plots following the filtering operation according to the embodiments of this disclosure. [Figure 5C] Figure 5B shows the volume and temperature data plots following data processing and fitting according to an embodiment of the present disclosure. [Figure 6] This is a plot of the capacity parameter definition according to the embodiments of this disclosure. [Figure 7A] This is a plot of higher-order regression fitting, such as quadratic fit and exponential fit, according to embodiments of the present disclosure. [Figure 7B] This is a plot of exemplary data from a temperature parametric extraction / regression model according to embodiments of the present disclosure. [Figure 8] The image shows a cross-sectional view of a plasma processing chamber including one or more capacitive sensors according to an embodiment of the present disclosure. [Figure 9] This is a schematic diagram showing a cross-sectional view of a capacitive sensor according to an embodiment of the present disclosure. [Figure 10] This is a schematic diagram showing a sensor system including a sensor module having a capacitive sensor according to an embodiment of the present disclosure. [Figure 11]Provide a schematic diagram showing a processing device including integration of capacitive sensor modules at various locations according to an embodiment of the present disclosure. [Figure 12A] It is a schematic diagram showing a cross-sectional view of a plasma processing device including one or more sensor modules according to an embodiment of the present disclosure. [Figure 12B] It is a schematic diagram showing the layout of an access tube in the spoke of a chamber body assembly of the plasma processing device of FIG. 12A according to an embodiment of the present disclosure. [Figure 13] It is a cross-sectional view of a processing device that may include one or more capacitive sensor modules according to an embodiment of the present disclosure. [Figure 14] Show a block diagram of an exemplary computer system of a processing tool according to an embodiment of the present disclosure.

MODE FOR CARRYING OUT THE INVENTION

[0012] Capacitive sensors and capacitive sensing data integration for plasma chamber state monitoring are described. In the following description, numerous specific details such as chamber configuration and capacitive sensor architecture are described to enable a complete understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the embodiments of the present disclosure can be implemented without these specific details. In other instances, well-known aspects such as detailed chamber specifications are not described in detail so as not to unnecessarily obscure the embodiments of the present disclosure. Furthermore, it should be understood that the various embodiments shown in the figures are exemplary representations and are not necessarily drawn to scale.

[0013] One or more embodiments are directed to capacitive sensors and systems for monitoring the state of a processing chamber. Embodiments may be applicable to or include data integration and processing algorithms, strategic sensors located within the processing chamber, sensor structures and materials, electronics, data processing algorithms, and system integration of one or more sensors with a processing tool.

[0014] According to embodiments of the present disclosure, the sensors are used for chamber wall monitoring at one or more of at least four locations, namely, the chamber wall, the chamber lid, inside the underfloor vacuum (SVF) port, and / or the edge ring. The sensor module / housing structures and assemblies described herein can be adapted, for example, to processing temperatures up to 400 degrees Celsius. Certain embodiments can include capacitive wall sensors, on-chip thermal sensors, and / or sensors on a substrate such as a ceramic substrate.

[0015] To provide context, compared to other chamber wall monitoring approaches (e.g., optical, piezoelectric, RF impedance, etc.), the sensors and sensor locations disclosed herein enable the measurement of capacitance changes (and optionally temperature measurements) directly related to conditions such as wall deposition or cleaning in each operation of the process recipe for ICC optimization or chamber seasoning, and further enable minimizing the preventive maintenance (PM) frequency (e.g., reduction greater than 2x, exceeding a 2-fold increase). Embodiments can also enable prediction of process stability or drift to significantly improve productivity and yield in production.

[0016] Some embodiments include implementations of two sensing technologies, for example, a combination of a capacitive sensor and a thermal sensor for chamber wall condition monitoring with high sensitivity and real-time measurement. Embodiments including sensors-on-substrate can be implemented not only to provide the benefits of miniaturization of the sensor module and signal integrity, but also to provide robust device performance similar to reliability. Data synchronization schemes as well as process algorithms can enable direct feedback to process control.

[0017] In some embodiments, the in-chamber sensors described herein may be used to measure by-product accumulation, optimize ICC routines, identify deviations, and / or provide faster PM recovery. Some embodiments enable temperature measurements in locations where state-of-the-art approaches cannot perform temperature measurements. Embodiments of the embodiments described herein may enable chamber matching, optimization of seasoning procedures, identification of deviations, particle generation prediction, process performance prediction (e.g., etching rate and etching non-uniformity), PM prediction, ring erosion prediction for ring position compensation, process deviation prediction, wall absorption and desorption measurement, fab excursion detection, and / or monitoring of the chamber baseline by mixed lot.

[0018] Embodiments described herein may include data synchronization for sensor data. In one embodiment, the data synchronization approach described herein can be implemented to correlate sensor data, such as wall sensor data, with process information (such as process policy behavior) at a predetermined integration time. In certain such embodiments, the predetermined integration time is on a scale such as 20 ms, 50 ms, or 100 ms. In one embodiment, the data synchronization approach described herein can be implemented to correlate sensor data, such as wall sensor data, with other in-situ sensor data (e.g., optical emission spectroscopy (OES) data, pressure data, gas flow data, temperature data, radio frequency (RF) data, etc.). In one embodiment, the data synchronization approach described herein can be implemented to enable automated data extraction from wall (or other location) sensors for process characterization and process development. In one embodiment, the data synchronization approach described herein can be implemented to establish new measurements from wall sensors for process control and monitoring.

[0019] For comparison, Figure 1 is a schematic diagram showing a conventional plasma chamber monitoring system 100. Referring to Figure 1, the system 100 includes a capacitive sensor module 102 having a capacitive sensor 104 connected to an application-specific electronic device 106 by an interconnect 108. The application-specific electronic device 106 includes a memory card 110 such as an SD card. Sensor data is delivered to an offline personal computer 112 by a manual procedure 114. A user interface 116 is connected to the offline personal computer 112 by a route 118.

[0020] Referring again to Figure 1, the conventional plasma chamber monitoring system 100 supports only one capacitive sensor per controller assembly. The data is captured and stored locally on a removable medium. It is not connected to a process control server. The data is also manually moved to the process control server for offline analysis.

[0021] In comparison with Figure 1, Figure 2A is a schematic diagram showing a plasma chamber monitoring system 200 according to an embodiment of the present disclosure. Referring to Figure 2A, the system 200 shows several capacitive sensors (e.g., four exemplary sensors shown as 204A, 204B, 204C, and 204D) connected to an application-specific electronic device 206 by corresponding interconnects 208A, 208B, 208C, or 208D. The application-specific electronic device 206 is connected to a server 210 by an interconnect 212 such as an etherCAT line.

[0022] Referring again schematically to Figure 2A, in the embodiment, the plasma chamber monitoring system 200 supports several capacitive sensors per controller assembly. Data is captured and transferred in real time to a process server, for example via etherCAT. The system 200 enables process policy synchronization of capacitive sensor data with process policy information and / or other system sensors. In one embodiment, the data stream goes from the sensor to the data server. In one embodiment, there is an interface (e.g., etherCAT) to an external electronic controller and a corresponding data processing unit. In one embodiment, the sensor data is correlated with process information. In one embodiment, the system 200 can enable or perform operations such as data extraction, data processing, and / or data analysis.

[0023] System 200 can also perform and control sensor status. In embodiments, the data server can tune and prime the sensor, initialize the sensor, reset the sensor, and / or actively compensate for sensor drift. In embodiments, the data server can perform data processing such as data denoising and regression, parameter extraction, and data modeling. The data server may also be implemented with algorithms for machine learning by the sensor to predict and monitor process and chamber performance.

[0024] Figure 2B is a schematic diagram showing a plasma chamber monitoring system 250 according to another embodiment of the present disclosure.

[0025] Referring to Figure 2B, the plasma chamber monitoring system 250 includes multiple capacitive sensors with capacitive digital converters (CDCs) (in the example shown, four are illustrated as 254A, 254B, 254C, and 254D, but any appropriate number of sensors can be used). The output of the CDC is any form of digital data stream, such as I2C, SPI, or UART. The plasma chamber monitoring system 250 may also include an application process server 276 connected to the capacitive digital converter output via an electronics plug-in module (EPM) 260. The application process server 276 includes system software. The EPM260 includes an isolation interface 262 connected to multiple outputs of the CDC of capacitive sensors 254A, 254B, 254C, and 254D; a power supply 265 (266) connected to the isolation interface 262; field-programmable gate array (FPGA) firmware 268 connected to the isolation interface 262; and an application-specific integrated circuit (ASIC) 272 (274) connected to the field-programmable gate array firmware 268.

[0026] In one embodiment, the application-specific integrated circuit 272 of the EPM260 is an etherCAT application-specific integrated circuit. In one such embodiment, the etherCAT application-specific integrated circuit provides seamless integration of system software and simultaneous control of several sensors among the multiple capacitive sensors 254A, 254B, 254C, and 254D. In another such embodiment, the etherCAT application-specific integrated circuit initializes and calibrates the individual sensors of the multiple capacitive sensors 254A, 254B, 254C, and 254D. In one embodiment, the application-specific integrated circuit 272 of the EPM260 is connected to an application process server 276 via an etherCAT connection (278).

[0027] In one embodiment, the application process server 276 synchronizes capacitive sensor data from multiple capacitive sensors 254A, 254B, 254C, and 254D with the process policy. In one embodiment, the field-programmable gate array firmware 268 of the EPM 260 provides deterministic timing and simultaneous communication with multiple sensors among the multiple capacitive sensors 254A, 254B, 254C, and 254D.

[0028] In one embodiment, the individual sensors of the multiple capacitive sensors 254A, 254B, 254C, and 254D are connected in parallel to the isolation interface 262 of the EPM260, as shown in the figure.

[0029] Referring again schematically to Figure 2B, in an embodiment, the application process server of the plasma chamber monitoring system 250 synchronizes capacitive sensor data with the process policy and other system sensors to improve on-wafer results. In an embodiment, the etherCAT device definition is customized to ensure seamless system software integration and simultaneous control of multiple capacitive sensors. In an embodiment, custom firmware on the ECAT ASIC initializes and calibrates the capacitive sensors to achieve fast integration time, high accuracy, and repeatable measurements. In an embodiment, the custom firmware can monitor sensor drift (capacitive drift, temperature drift) as feedback and compensate for sensor drift with a predetermined algorithm to reset the sensor. In an embodiment, custom FPGA firmware enables deterministic timing and simultaneous communication with multiple capacitive sensors. In an embodiment, power distribution and isolation design ensures high signal-to-noise (SNR) and data communication robustness for capacitive sensor analog measurements.

[0030] In another embodiment, a connector for interface connection with a sensor module is described. Such a connector can route power from the EPM to the sensor. Such a connector can provide a common ground between the sensor and the EPM. Such a connector can provide a data stream from the sensor to the EPM. Such a connector can synchronize sensor data clocking. Such a connector can be used to provide hardware radio frequency (RF) grounding.

[0031] As an exemplary connector, Figure 3 shows an interconnect 300 for a plasma chamber monitoring system according to an embodiment of the present disclosure.

[0032] Referring to Figure 3, the interconnection 300 includes a first connector 306 for connecting to the capacitive digital converter of the capacitive sensor module 302, a second connector 308 for connecting to the EPM 310 and an external power supply 312 (such as a 5V DC power supply), and a shielded cable 304 connected to and between the first connector 306 and the second connector 308. The shielded cable 304 includes, for example, a shielding metal 328 for physically connecting the interconnection 300 at position 330 to the frame of the plasma chamber. The shielded cable 304 also includes power lines (lines 326A to 326B) housed within the shielding metal 328, ground lines (lines 324A to 324B) housed within the shielding metal 328, and one or more communication lines 322 (two are shown) housed within the shielding metal 328.

[0033] In one embodiment, the power lines (lines 326A to 326B) housed within the shield metal 328 are 3-4 volt power lines. In one embodiment, each of the one or more communication lines 322 housed within the shield metal 328 is or includes a data bus (I2C, SPI, or UART). In one embodiment, the ground lines (lines 324A to 324B) housed within the shield metal 328 provide a common ground for the capacitive sensor module 302 and the electronic equipment 310. In one embodiment, the one or more communication lines 322 housed within the shield metal 328 synchronize sensor data clocking.

[0034] In another embodiment, hardware embodiments are described. As an exemplary embodiment, Figure 4 is a schematic diagram showing plasma chamber monitoring hardware 400 according to another embodiment of the present disclosure.

[0035] Referring to Figure 4, the plasma chamber monitoring hardware 400 includes a sensor ASIC 402 (such as a wall sensor ASIC), an application printed circuit board (PCB) 404, and an etherCAT master 406 including a device 407. The sensor ASIC 402 is connected to a connector (or multiple connectors) 408 (410 / 412) on the PCB 404. The connector (or multiple connectors) 408 is connected to a power supply 414 (416 / 418) on the PCB 404. The power supply 414 is connected to a power supply 420 (such as a 24V source), and the power supply 420 is connected to ground 422. The PCB 404 includes an isolation barrier 424. The power supply 414 is connected to the isolation 426 of the isolation barrier 424 (428). The isolation 426 is connected to one or more application integrated circuits 430 (432) on the isolation barrier 424. The second PCB 434 is contained within the isolation barrier 424 of the application PCB 404. The second PCB 434 includes an etherCAT ASIC 436, an FPGA 438, and an isolation 440. One or more application integrated circuits 430 of the isolation barrier 424 are connected to the isolation 440 of the second PCB 434 (437). The etherCAT ASIC 436 is connected to the isolation 440 of the second PCB 434 (442) and to the FPGA 438 (444). The FPGA 438 is also connected to the isolation 440 of the second PCB 434 (446). A power supply 448 is connected to the isolation 440 of the second PCB 434. The second PCB 434 also includes an etherCAT connector 452 connected to the etherCAT ASIC 436 (454). The etherCAT connector 452 on the second PCB is connected to the etherCAT master 406 and may also be connected to a further etherCAT connector 458 on the application PCB 404 (460). If included, the additional etherCAT connector 458 may be connected to the etherCAT master 406 as shown in the illustration (462).

[0036] Referring again schematically to Figure 4, in the embodiment, the etherCAT plug-in module includes an interface to a sensor having a connector with I2C or a serial peripheral interface (SPI). In the embodiment, the hardware provides power to one or more sensors. In the embodiment, FPGAs and ASICs are included for data streaming and data extraction control. In the embodiment, the hardware includes firmware implementation for sensor operation configuration and channel assignment. In the embodiment, the hardware includes an etherCAT (ECAT) process unit. In the embodiment, the hardware includes a connector to the ECAT master. In the embodiment, the hardware provides a grounding scheme to minimize RF noise.

[0037] In embodiments for the system or hardware implementation described herein, the basic configuration may include one or more of the following: (1) channel configuration and reconfiguration including multi-channel capability; (2) each sensor can be operated individually or all sensors can be combined and operated together, which may depend on or be controlled by software commands; and / or (3) input / output channel reconfiguration including temperature channel control (e.g., for external thermal sensors), clock (CLK) control (e.g., double conversion time), and / or capacitor conversion time control.

[0038] In embodiments for the software implementation described herein, the requirements include: (1) data streaming from the sensor to a data server, sensor data collection on the server, correlation to a process sequence, and sensor synchronization with the manufacturing process; (2) data processing and parametric extraction which may include data filtering (e.g., sensor data filtering and denoising), sensor data regression modeling, sensor parameter extraction, and process report generation; and (3) (a) resetting the power cycle, plugging in the sensor, providing sensor initialization, reading data, verifying the sensor status, and / or capacitance (pF) and temperature (°C). The control of the sensor's operation may include one or more of the following: (b) a startup operating mode that can output values; (c) a production mode that can synchronize with the policy and stream capacity and temperature data before the process policy starts (e.g., to provide data buffer time), provide a timestamp that matches the process policy time, and / or enable data acquisition while the tool is idle; (d) an engineering mode in which the data stream and data logging can be manually determined; (e) performing calibration and / or offset correction; (f) compensating for parasitic capacitance (e.g., by system offset calibration and / or gain coefficient calibration); (g) achieving drifting compensation (zero-in); and / or (g) performing data acquisition through data streaming and storage.

[0039] According to one or more embodiments described herein, the sensor generates two types of traces, namely, capacitance and temperature. In one embodiment, for engineering use cases, both raw capacitance and temperature data are stored as unmodified on a server. Data acquisition is synchronized with a process sequence during processing. Data acquisition can be performed during idle periods. The data stream during idle periods can be used as a baseline for the capacitive sensor for calibration, correction, and reset. In addition, the data stream during idle periods is also used to monitor the baseline state of the chamber and to detect deviations within the chamber. The data is further processed and reported. In one embodiment, for production use cases, temperature traces are stored. Temperature traces are also processed, and capacitance traces are processed.

[0040] According to one or more embodiments described herein, data processing such as filtering and denoising may be performed by (1) calculating a moving average (N~2) based on the following formula: TIFF0007880920000001.tif13170; j=1,2,3,4, and / or (2) parameter extraction which may include regression modeling, data extraction and filtering (from sensor modules), data report generation (capacity vs. time / process operation), and / or the use of temperature data (for time / process operation).

[0041] According to one or more embodiments described herein, a data processing flow (which may include the use of a data processing algorithm) may include (1) data (capacity and temperature) streams and collection for states such as plasma off, plasma on, and idle state; (2) data filtering by policy (e.g., plasma off) and / or denoising process (e.g., moving average); (3) data fitting, which may include the use of regression models, model fitting, parameter extraction, and / or data output algorithms; and / or (4) process feedback for process control.

[0042] In another embodiment, exemplary embodiments of data integration for capacity sensor data (which in some embodiments may also include temperature data) are described based on exemplary datasets.

[0043] Figure 5A is a plot 500 of capacity and temperature data, including signal data for temperature 502 and capacity 504, according to an embodiment of the present disclosure. The capacity and temperature data in plot 500 may be raw capacity and temperature data provided to the server.

[0044] Figure 5B shows a plot 520 of the capacitance and temperature data of plot 500 after a filtering operation, according to an embodiment of the present disclosure. The capacitance and temperature data of plot 520 includes temperature data 502 and denoised capacitance data 522. The resulting filtered trace can be based on an RF power setpoint.

[0045] Figure 5C shows a plot 540 of volume and temperature data after data processing and fitting according to an embodiment of the present disclosure. In one embodiment, individual volume and temperature traces can be fitted using a previously applicable model. Data can be output by associating the parameters extracted from the traces with policy behavior, recording the fitted parameters with the relevant process policy behavior, and / or generating data plots (e.g., extracted parameters versus process time or behavior). Process feedback control can be implemented by monitoring the above parameters for outlier detection, drift, etching rate (ER) / process control (PC) / other sensor data, etc. The data can be used to provide a visual indicator of the clean / dirty status of the walls for a plasma process chamber.

[0046] Figure 6 is a plot 600 of capacitance parameter definitions according to an embodiment of the present disclosure. Referring to Figure 6, in the embodiment, the capacitance data is when the plasma is off, for example, the data 606 in the range from the plasma off event 602 to the plasma on event 604. Traces such as 606 are extracted during plasma events as defined by the policy set points. Trace data processes and parameters are extracted. The extracted parameters can be associated with the preceding steps / policies / actions. In one embodiment, the trace length = tw - to, and xs < trace length < ys. If the trace length is less than xs, it is ignored. If the trace length is greater than ys, it can be truncated to include only the first ys.

[0047] In one embodiment, the capacitance parametric extraction / regression model can include the following. Primary parameter: Capacitance baseline: Cbase;; Capacitance change: TIFF0007880920000002.tif10170; Capacitance drift during plasma off: TIFF0007880920000003.tif10170; Average capacitance during plasma off (e.g., for determining depth / washing amount): TIFF0007880920000004.tif10170, where TIFF0007880920000005.tif8170 is recorded.

[0048] Figure 7A is a plot 700 of higher - order regression fits such as a quadratic fit 702 and an exponential fit 704 according to an embodiment of the present disclosure. The regression process can include (1) extracting the fit parameters by the regression process, (2) deriving Co, t, and Cinf from the fit parameters, and (3) recording Co, t, Cinf, and R2.

[0049] FIG. 7B is a plot 750 of exemplary data from a temperature parametric extraction / regression model according to an embodiment of the present disclosure. The temperature parametric extraction / regression process includes: (1) extracting a temperature trace corresponding to the same time as the capacitance trace defined above: trace length (excluding 756, portions 758 and 760) = tw; ignore if trace length < zs, but truncate to include only the first zs if trace length is greater than zs, (2) fitting by a linear model TIFF0007880920000006.tif9170, and (3) recording M, in To(752) and Tw(754).

[0050] FIG. 8 shows a cross-sectional view of a plasma processing chamber including one or more capacitive sensors according to an embodiment of the present disclosure.

[0051] Referring to FIG. 8, the plasma processing chamber 800 includes a chamber wall 802 surrounding a processing region 811. A wafer or substrate 812 can be processed within the processing region 811. The chamber lid 804 is on the chamber wall 802 and above the processing region 811. The chamber floor 806 is under the chamber wall 802 and below the processing region 811. The support pedestal 808 is within the processing region 811 (more specifically, can include a support surface 810 within the processing region 811). The support pedestal 808 is below the chamber lid 804 and above the chamber floor 806 and is surrounded by the chamber wall 804.

[0052] Referring again to Figure 8, in one embodiment, the wall of the chamber 804 has an opening through it. The capacitive sensor module 816 is located within the opening in the chamber wall 804. In another embodiment, the chamber lid 804 includes the capacitive sensor module 814. In another embodiment, the chamber floor 806 includes an outlet. The capacitive sensor module 820 is located within or adjacent to the outlet. In another embodiment, the support pedestal includes a ring structure (e.g., location 818) surrounding a substrate support area. The ring structure includes an opening through it. The capacitive sensor module is located within the opening in the ring structure. In one embodiment, the plasma processing chamber 800 includes one or more of the following: the capacitive sensor module 816 located within the opening in the chamber wall 804, the capacitive sensor module 814 in the chamber lid 804, the capacitive sensor module located within or adjacent to the outlet 820 of the chamber floor 806, and / or, for example, a capacitive sensor module located within the opening of the ring structure at location 818.

[0053] Figure 9 is a schematic diagram showing a cross-sectional view of a capacitive sensor according to an embodiment of the present disclosure.

[0054] Referring to Figure 9, the capacitive sensor module 900 includes a drive electrode 904 and a sensing electrode 902. The measured capacitance 908 of the material 906 between the drive electrode 904 and the sensing electrode 902 may vary if the composition, thickness, etc., of the material 906 changes or fluctuates. In one embodiment, the material 906 represents the material to be deposited on a wafer or substrate in a process chamber. The purpose may be to remove / discharge such excess material 906 that is not deposited on the wafer or substrate, but some of the material 906 may accumulate in the processing chamber and ultimately on the capacitive sensor module 900 in the processing chamber. In another embodiment, in one embodiment, the material 906 represents etching byproducts formed during etching of a wafer or substrate in a processing chamber. The purpose may be to remove / discharge such etching byproducts 906, but some of the etching byproducts 906 may accumulate in the processing chamber and ultimately on the capacitive sensor module 900 in the processing chamber.

[0055] The sensor system may include a sensor module, interface electronics, a controller, and integration with a chamber data server for process control and data / process synchronization. As an example, Figure 10 is a schematic diagram showing a sensor system including a sensor module having a capacitive sensor according to an embodiment of the present disclosure.

[0056] Referring to Figure 10, the sensor system includes a sensor module 1002 connected to a controller 1004, which in turn is connected to a user interface 1006. The sensor module 1002 includes a capacitive sensor ( schematically shown as 1010 or structurally as 1020). The capacitive sensor 1010 is connected to a capacitive-to-digital converter (CDC) interface circuit 1012. Communication within module 1002 is possible along path 1014A from the capacitive sensor 1010 to the CDC interface circuit 1012 and / or along path 1014B from the CDC interface circuit 1012 to the capacitive sensor 1010. Communication between module 1002 and the outside is possible between the CDC interface 1012 and the controller 1004 along paths 1016A and 1016B. The controller 1004 may be connected to the CDC interface circuit 1012 by Vdd 1018.

[0057] Referring now to Figure 10, a cross-sectional view of the sensor 1020 according to an embodiment is shown. In the embodiment, the sensor 1020 includes a substrate 1022, and electrodes 1024 are disposed on the substrate 1022. In the embodiment, electrodes 1024 are made of a conductive material suitable for miniature electronic processing operations, or include a conductive material. For example, the material for electrodes 1024 may include, but is not limited to, aluminum, molybdenum, tungsten, titanium, nickel, chromium, and alloys thereof.

[0058] In some embodiments, the electrode 1024 is electrically connected to a pad 1030 on the back side of the substrate 1022 by a conductive path 1028 running through the substrate 1022. For example, the conductive path 1028 may include one or more vias, traces, etc. In some embodiments, the conductive path 1028 embedded in the substrate 1022 may include, but are not limited to, conductive materials such as tungsten, molybdenum, titanium, tantalum, or alloys thereof. In some embodiments, the pad 1030 may include, but are not limited to, materials such as titanium, nickel, palladium, or copper. In some embodiments, the pad 1030 is a multilayer stack to improve integration with the CDC. For example, the pad 1030 may include stacks such as titanium / nickel / palladium, titanium / copper / palladium, or other material stacks commonly used for interconnect pads.

[0059] In embodiments, the upper surfaces of the electrode 1024 and the substrate 1022 are covered by a layer 1026 (e.g., a barrier layer). In embodiments, the upper layer 1026 is a material that is resistant to attack or erosion of plasma chemical species and limits their diffusion. In certain cases of etching chambers, a common etchant used is fluorine. Therefore, the layer 1026 used under such conditions should be resistant to fluorine etchants. In certain embodiments of plasma chambers used for etching, the layer 1022 may include one or more metal oxides, metal fluorides, and metal fluoride oxides. The layer 1022 may include, but is not limited to, materials such as aluminum oxide, magnesium oxide, yttrium oxyfluoride, yttrium zirconium oxyfluoride, yttrium aluminum oxide, or hafnium oxide.

[0060] In some embodiments, the substrate 1022 includes a suitable substrate material resistant to processing conditions in the processing chamber (e.g., etching conditions). The substrate 1022 may be a ceramic material, glass, or other insulating material. In some embodiments, the substrate 1022 is a flexible substrate such as a polymer material. For example, the substrate 1022 may include, but is not limited to, materials such as silicon, silicon oxide, aluminum oxide, aluminum nitride, plastic, or other insulating materials. To enable mass production of sensors, the substrate 1022 may be a material suitable for high-volume manufacturing (HVM) processes. That is, the substrate 1022 may be a material available in panel form, wafer form, etc.

[0061] According to one embodiment of the present disclosure, both a capacitive sensor and a thermal sensor are integrated (embedded) in a single sensor module. In such one embodiment, the wall sensor module includes a capacitive sensor, a CDC, and a thermal sensor, and a housing unit for assembling the capacitive sensor, CDC, and thermal sensor together.

[0062] Referring again to Figure 10, in this embodiment, the thermal sensor is located on the substrate 1022. For example, the thermal sensor may be formed on the back side of the substrate 1022 (i.e., the surface opposite to the electrode 1024). The thermal sensor may include any suitable sensing technique. For example, the thermal sensor may include multiple traces to form a resistance temperature detector (RTD). However, it should be understood that other thermal sensors, such as thermocouple (TC) sensors, thermistor (TR) sensors, or photothermal sensors, may be used, but are not limited to these. In this embodiment, the thermal sensor is integrated directly onto the substrate 1022. However, it should be understood that in some embodiments, a separate component including the thermal sensor may be mounted on the substrate 1022. In other embodiments, the thermal sensor may be integrated into a CDC attached to sensor 1020.

[0063] According to one or more embodiments of the present disclosure, a method for integrating data for plasma chamber state monitoring includes streaming data from a capacitive sensor module to a data server. The data includes capacity data and temperature data. The method also includes collecting data on an application process server. The method also includes correlating the data with one or more process policy operations. The method also includes synchronizing the capacitive sensor module with one or more process policy operations.

[0064] In some embodiments, a method for integrating data for plasma chamber state monitoring further includes performing data processing and parameter extraction after collecting data on an applied process server and before correlating the data with one or more process policy operations. In one such embodiment, performing data processing includes filtering and denoising the data. In certain such embodiments, filtering and denoising the data includes using a moving average approach. In another such embodiment, performing data processing and parametric extraction includes regression modeling of the data.

[0065] In one embodiment, a method for integrating data for plasma chamber state monitoring further includes monitoring one or more parameters of one or more process policy operations using a capacitive sensor module. In such one embodiment, the method further includes determining a clean / dirty status for the plasma chamber based on the monitoring of one or more parameters of one or more process policy operations by the capacitive sensor module.

[0066] Wall / Lid Sensor Solution The following are exemplary parameters and their corresponding (a) importance, (b) solution, and (c) benefit / use.

[0067] Wall and lid temperatures: (a) one or more first wafer effects (limiting dimension (CD) and etching rate (ER)), particle size, coefficient of thermal expansion (CTE), (b) thermometer on the back of the sensor, (c) accurate measurement of in-situ temperature. ICC may be triggered to bring the wall / lid to the target temperature.

[0068] Chamber conditions: (A) one or more first wafer effects, long-term ER / CD drift, preventive maintenance (PM) recovery, and stepwise process stability; (b) direct detection of deposition and removal, gas emission monitoring; (c) monitoring of chamber conditions, process stability, reduced PM, and faster time to identify and resolve drift problems after each wafer / ICC and each step.

[0069] Displacement detection (e.g., backflow): (a) Unknown yield killers, process shifts, (b) Changes in chamber conditions can be detected by continuous measurement, and (c) Absorption and desorption of residual species can be detected.

[0070] Mixing operation (high / low depending on the product): (a) affecting chamber conditions, (b) directly detecting deposits and their removal, and (c) monitoring chamber wall conditions for optimal strategies or lot sequences to minimize process crosstalk.

[0071] ICC optimization: (a) stability of the processing chamber (PC) / ER / CD, (b) direct detection of deposition and its removal, (c) detection of inefficient ICC, development of the optimal ICC strategy in situ, and monitoring the condition of the liner / chamber wall for optimal surface protection of the chamber wall / liner during the etching process (e.g., BCl3 / Cl2-based etching).

[0072] Capacitive Sensor Solutions The following are exemplary parameters and their corresponding (a) importance, (b) solution, and (c) benefit / use.

[0073] Deposition on a single ring: (A) particles, (b) cap sensors attached to a single ring, (c) developing a more effective ICC without coupons and regularly cleaning the endpoint.

[0074] A single ring erosion monitor: (a) helps determine ring erosion and (c) when the ring needs to be changed, and automatically sets the ring height.

[0075] RF ON via product monitoring: (A) Episodic Point Detection (EPD), an additional method for capturing particles, (b) installation of a cap sensor in the lower chamber near the SFV, (c) detection when etching passes through one film to the next, determined by the product in the lower chamber.

[0076] Part wear rate (time to failure): (a) to quickly determine the impact of process changes on the MTBC, (b) to develop sensors made of chamber material installed on parts at specific locations, and (c) to quickly determine the impact of process changes on the part in order to calculate the MTBC.

[0077] Residual chemical reaction sensor (on wafer): (a) Sensors are embedded in test wafers to measure waiting time and (b) post-process chemical reactions, and (c) waiting time and process optimization are understood to reduce / eliminate residual chemical reactions.

[0078] PVD / CVD / ALD chamber walls: (a) cleaning and seasoning of chamber walls, (b) installing sensors at specific locations to monitor the condition of the walls, and (c) in-situ monitoring of the chamber walls.

[0079] Case study The following are exemplary problems and corresponding (a) impacts, and (b) wall / lid sensor detection solutions to mitigate or eliminate those impacts.

[0080] The effect of CD on lid / wall temperature after some idle time (due to failure or other delays):(A) 1 to 3 scrapped wafers, (b) a sensor automatically detects the temperature outside the specifications and invokes the warm-up procedure.

[0081] Unoptimized warm-up procedures: (a) Lost production time, (b) End-Point Detection (EPD) warm-up / season procedure.

[0082] Backflow events (e.g., backing pump failure): (a) wafer scrap due to chamber state shift, (b) wall / lid state changes are automatically detected.

[0083] Fab deviation (e.g., power anomaly): (a) Determine which chamber is problematic without performing wafer scrap, requalification, necessary PM, or (b) etching rate (ER) monitoring.

[0084] Measures to overcome lid thermal balance: (a) damaged lid, scrapped wafer, required PM, (b) failure chamber if lid temperature exceeds specifications.

[0085] Monitor wafer run that affects unoptimized ICC and chamber conditions: (A) shortened MTBC, extended season, ICC, yield loss, and (B) wall / lid condition.

[0086] Plasma stability: (a) yield loss; (b) detection of capacitance changes at high speed (e.g., 50 Hz).

[0087] Application A to B conversion: (a) determining the top / bottom of the season (e.g., loss of production time / first wafer effect), and (b) determining when the chamber becomes production ready.

[0088] In the embodiment, a capacitive sensor assembly (or sensor assembly) includes a sensor module and a sensor housing assembly. The sensor module may include a capacitor (e.g., a first electrode and a second electrode) placed on a substrate. The sensor module may also include a capacitive-to-digital converter (CDC) for converting the capacitance output from the capacitor into a digital signal for subsequent processing. To integrate the sensor module with a processing tool, a sensor housing assembly may be used to house the sensor module. The sensor housing assembly may include features that allow the sensor module's capacitor to be exposed to the processing environment while fixing the sensor module within the processing chamber. The sensor housing assembly may also include components for interface connection to a port through the chamber wall or chamber lid of the processing tool so that data can be captured in real time.

[0089] In certain embodiments, the sensor housing assembly includes a hollow shaft and a cap. The sensor module may be secured to the end of the shaft by the cap. A hole through the cap may expose the capacitor of the sensor module. The hollow shaft protects the interconnects from the sensor module (e.g., wires, pins, etc.) from the processing environment and allows them to be supplied to the vacuum electrical feedthrough, so that they can exit the chamber without disturbing the chamber vacuum.

[0090] Different locations for the sensor module can be achieved by modifying various components of the sensor housing assembly and / or by modifying how the components interface with the chamber itself. For example, in the case of a chamber wall sensor, the shaft may extend through a port in the chamber wall, and the vacuum electrical feedthrough may be outside the chamber. In the case of a lid sensor, the shaft may extend from the lid into the chamber, and the vacuum electrical feedthrough may be embedded within the lid. In the case of a processing ring sensor, the shaft may extend upward from the bottom chamber surface and intersect with a plasma screen adjacent to the processing ring. In such embodiments, the vacuum electrical feedthrough may be located within a port through the bottom chamber surface. In the case of an exhaust area sensor, the shaft may be inserted through a port through the chamber wall, and the vacuum electrical feedthrough may be outside the chamber wall. In some embodiments, adapters may be fitted around a portion of the sensor housing assembly to provide an airtight seal along a port of any size.

[0091] In some embodiments, parts of the sensor assembly may be considered consumable parts. For example, a sensor module may be replaced after a certain period of time or after significant sensor drift is detected. The sensor housing assembly may be easily disassembled to allow for simple replacement. In certain embodiments, the shaft may have a threaded end that screws into a main housing that is mounted to a vacuum electrical feedthrough. Thus, the shaft and other components attached to it (e.g., caps and sensor modules) can be removed and replaced by screwing a new shaft into the main housing. In other embodiments, the entire sensor assembly may be considered consumable parts and may be replaced after a certain period of time or after significant sensor drift is detected.

[0092] By incorporating a capacitive sensor module as described herein into the processing apparatus, it becomes possible to monitor the chamber state during the execution of various processing strategies, during transfers between substrates, during cleaning operations (e.g., ICC operations), during chamber verification, or at any other desired time. Furthermore, the sensor module architecture disclosed herein allows for integration in many different locations. Such flexibility allows many different components of the processing apparatus to be monitored simultaneously to provide an enhanced ability to determine the cause of chamber drift. For example, Figure 11 provides a schematic diagram showing a processing apparatus 1100 including the integration of a capacitive sensor module 1111 in various locations.

[0093] As shown in Figure 11, the processing apparatus 1100 may include a chamber 1142. A cathode dryer 1145 may surround the lower electrode 1161. A substrate 1105 may be fixed to the lower electrode 1161. A processing ring 1197 may surround the substrate 1105, and a plasma screen 1195 may surround the processing ring 1197. In the embodiment, a lid assembly 1110 may seal the chamber 1142. The chamber 1142 may include a processing area 1102 and an exhaust area 1104. The exhaust area 1104 may be close to an exhaust port 1196.

[0094] In some embodiments, the sidewall sensor module 1111A may be located along the sidewall of the chamber 1142. In some embodiments, the sidewall sensor module 1111A passes through the wall of the chamber 1142 and is exposed to the processing area 1102. In some embodiments, the lid sensor module 1111B is integrated with the lid assembly 1110 and faces the processing area 1102. In some embodiments, the processing ring sensor module 1111C is located adjacent to the processing ring 1197. For example, the processing ring sensor module 1111C may be integrated with the plasma screen 1195 surrounding the processing ring 1197. In yet another embodiment, the discharge area sensor module 1111D may be located in the discharge area 1104. For example, the discharge area sensor module 1111D may pass through the bottom surface of the chamber 1142. As shown, each of the sensor modules 1111 includes an electrical lead 1199 exiting the chamber 1142. Therefore, real-time monitoring can be performed using the sensor module 1111.

[0095] In one embodiment, the sidewall sensor module 1111A is located at location 1120A along the side of the chamber 1142. In one embodiment, the sidewall sensor module 1111A is located at location 1122A laterally adjacent to the substrate 1105 support area of ​​the lower electrode 1161. In one embodiment, the sidewall sensor module 1111A is located at vertical location 1124A between the substrate 1105 support area of ​​the lower electrode 1161 and the lid assembly 1110. In one embodiment, the sidewall sensor module 1111A is located at vertical location 1126A between the substrate 1105 support area of ​​the lower electrode 1161 and the floor of the processing unit 1100.

[0096] In one embodiment, the lid sensor module 1111B is located at position 1120B along the lid assembly 1110. In one embodiment, the lid sensor module 1111B is located at position 1122B coaxial with the substrate 1105 support region of the lower electrode 1161. In one embodiment, the lid sensor module 1111B is located at position 1124B vertically on the substrate 1105 support region of the lower electrode 1161. In one embodiment, the lid sensor module 1111B is located at position 1126B vertically on the region outside the substrate 1105 support region of the lower electrode 1161.

[0097] In one embodiment, the processing ring sensor module 1111C is located on the inner circumference of the plasma screen 1195. In another embodiment, the processing ring sensor module 1111C is located on the outer circumference of the plasma screen 1195.

[0098] In one embodiment, the discharge area sensor module 1111D is located at location 1120D along the bottom surface of the chamber 1142. In one embodiment, the discharge area sensor module 1111D is located at vertical location 1122D below the area outside the substrate support area of ​​the lower electrode 1161. In one embodiment, the discharge area sensor module 1111D is located at vertical location 1124D below the substrate support area of ​​the lower electrode 1161.

[0099] In the embodiment, one or more of the capacitive sensor modules 1111 further include a thermal sensor. In one such embodiment, the capacitive sensor module includes a capacitive sensor adjacent to the substrate processing area and a thermal sensor distal to the substrate processing area. In another such embodiment, the capacitive sensor module includes a capacitive sensor adjacent to the substrate support area and a thermal sensor distal to the substrate support area.

[0100] Figure 12A is a schematic cross-sectional view of a plasma processing apparatus 1200, including one or more sensor modules as described herein, according to an embodiment. The plasma processing apparatus 1200 may be a plasma etching chamber, a plasma chemical vapor deposition chamber, a physical vapor deposition chamber, a plasma processing chamber, an ion implantation chamber, or other suitable vacuum processing chamber. As shown in Figure 12A, the plasma processing apparatus 1200 generally includes a chamber lid assembly 1210, a chamber body assembly 1240, and an exhaust assembly 1290, which collectively surround the processing area 1202 and the exhaust area 1204. In practice, a processing gas is introduced into the processing area 1202 and the plasma is ignited using RF power. A substrate 1205 is placed on a substrate support assembly 1260 and exposed to the plasma generated in the processing area 1202 to perform a plasma process on the substrate 1205, such as etching, chemical vapor deposition, physical vapor deposition, implantation, plasma annealing, plasma processing, mitigation, or other plasma processes. A vacuum is maintained within the processing area 1202 by an exhaust assembly 1290, which removes spent processing gases and by-products from the plasma process through an exhaust area 1204.

[0101] The lid assembly 1210 generally includes an upper electrode 1212 (or anode) that is separated from and supported by the chamber body assembly 1240, and a chamber lid 1214 surrounding the upper electrode 1212. The upper electrode 1212 is connected to an RF power supply 1203 via a conductive gas inlet tube 1226. The conductive gas inlet tube 1226 is coaxial with the central axis of the chamber body assembly 1240, and as a result, both RF power and processing gas are supplied symmetrically. The upper electrode 1212 includes a showerhead plate 1216 attached to a heat transfer plate 1218. The showerhead plate 1216, the heat transfer plate 1218, and the gas inlet tube 1226 are all manufactured from an RF conductive material such as aluminum or stainless steel.

[0102] The showerhead plate 1216 has a central manifold 1220 and one or more outer manifolds 1222 for distributing the process gas within the processing area 102. One or more outer manifolds 1222 surround the central manifold 1220. The central manifold 1220 receives the process gas from the gas source 1206 through a gas inlet tube 1226, and the outer manifolds 1222 receive the process gas from the gas source 1206 through one or more gas inlet tubes 1227, which may be the same or different mixtures of the gas received in the central manifold 1220. The dual manifold configuration of the showerhead plate 1216 allows for improved control of the gas supply to the processing area 1202. The multi-manifold showerhead plate 116 allows for enhanced control of the processing results from the center to the edge, in contrast to the conventional single-manifold version.

[0103] The heat transfer fluid is supplied from the fluid source 1209 to the heat transfer plate 1218 through the fluid inlet tube 1230. The fluid circulates through one or more fluid channels 1219 located within the heat transfer plate 1218 and returns to the fluid source 1209 via the fluid outlet tube 1231. Suitable heat transfer fluids include water, water-based ethylene glycol mixtures, perfluoropolyethers (e.g., Galden® fluids), oil-based heat transfer fluids, or similar fluids.

[0104] The chamber body assembly 1240 includes a chamber body 1242 manufactured from a conductive material resistant to the processing environment, such as aluminum or stainless steel. The substrate support assembly 1260 is centrally located within the chamber body 1242 and positioned symmetrically with respect to the central axis (CA) to support the substrate 1205 in the processing area 1202. The substrate support assembly 1260 may also support a processing ring 1297 surrounding the substrate 1205. The chamber body 1242 includes a ledge that supports the outer flange of the upper liner assembly 1244. The upper liner assembly 1244 may be constructed from a conductive, processing-compatible material such as aluminum, stainless steel, and / or yttria (e.g., aluminum coated with yttria). In practice, the upper liner assembly 1244 can be removed to shield the top of the chamber body 1242 from the plasma in the processing area 1202 and to allow for periodic cleaning and maintenance. The inner flange of the upper liner assembly 1244 supports the upper electrode 1212. To provide electrical insulation between the chamber body assembly 1240 and the upper electrode 1212, an insulator 1213 is placed between the upper liner assembly 1244 and the upper electrode 1212.

[0105] The upper liner assembly 1244 includes an outer wall 1247 attached to the inner and outer flanges, a bottom wall 1248, and an inner wall 1249. The outer wall 1247 and the inner wall 1249 are substantially vertical cylindrical walls. The outer wall 1247 is positioned to shield the chamber body 1242 from the plasma in the processing area 1202, and the inner wall 1249 is positioned to at least partially shield the sides of the substrate support assembly 1260 from the plasma in the processing area 1202. The bottom wall 1248 joins the inner wall 1249 and the outer wall 1247, except in certain areas where the discharge passage 1289 is formed.

[0106] The processing area 1202 is accessed through a slit valve tunnel 1241 located within the chamber body 1242, which allows the substrate 1205 to enter the substrate support assembly 1260 and to be removed from the substrate support assembly 1260. The upper liner assembly 1244 has a slot 1250 positioned to fit the slit valve tunnel 1241, allowing the substrate 1205 to pass through. A door assembly (not shown) closes the slit valve tunnel 1241 and the slot 1250 during operation of the plasma processing apparatus.

[0107] The substrate support assembly 1260 generally includes a lower electrode 1261 (or cathode) and a hollow pedestal 1262, through which the center of the central axis (CA) of the substrate support assembly 1260 passes. The substrate support assembly 1260 is then supported by a central support member 1257 located in a central region 1256 and supported by the chamber body 1242. The central axis (CA) also passes through the center of the central support member 1257. The lower electrode 1261 is connected to an RF power supply 1203 via a matching network (not shown) and a cable (not shown) routed through the hollow pedestal 1262. When RF power is supplied to the upper electrode 1212 and the lower electrode 1261, the electric fields formed therein ignite the processing gas present in the processing region 1202 into a plasma.

[0108] The central support member 1257 is sealed to the chamber body 1242 by fasteners and O-rings (not shown), and the lower electrode 1261 is sealed to the central support member 1257 by bellows 1258, etc. Thus, the central region 1256 is sealed from the processing region 1202 and can be maintained at atmospheric pressure while the processing region 1202 is maintained under vacuum conditions.

[0109] The actuator assembly 1263 is positioned within the central region 1256 and attached to the chamber body 1242 and / or the central support member 1257. The actuator assembly 1263 provides vertical movement of the lower electrode 161 relative to the chamber body 142, the central support member 1257, and the upper electrode 1212. Such vertical movement of the lower electrode 1261 within the processing region 1202 increases control of the electric field formed therein by creating a variable gap between the lower electrode 1261 and the upper electrode 1212, and subsequently provides better control of the density in the plasma formed within the processing region 1202. Furthermore, since the substrate 1205 is supported by the lower electrode 1261, the gap between the substrate 1205 and the showerhead plate 1216 can also be varied. As a result, better control of the process gas distribution across the substrate 1205 is achieved.

[0110] In one embodiment, the lower electrode 1261 is an electrostatic chuck and therefore includes one or more electrodes (not shown) disposed therein. A voltage source (not shown) biases one or more electrodes to the substrate 1205, generating an attractive force to hold the substrate 1205 in place during processing. Cables connecting one or more electrodes to the voltage source are routed through a hollow pedestal 1262 and exit the chamber body 1242 through one of a plurality of access tubes 1280.

[0111] Figure 12B is a schematic diagram of the layout of the access tubes 1280 within the spokes 1291 of the chamber body assembly 1240. The spokes 1291 and access tubes 1280 are arranged symmetrically around the central axis (CA) of the processing apparatus 1200 in a spoke pattern as shown. In the illustrated embodiment, three identical access tubes 1280 are located within the central region 1256 through the chamber body 1242, facilitating the supply of multiple pipes and cables from outside the chamber body 1242 to the lower electrode 1261. Each of the spokes 1291 is adjacent to a discharge passage 1289 that fluidly connects the processing region 1202 above the central region 1256 to the discharge region 1204 below the central region 1256. The symmetrical arrangement of the access tubes 1280 further provides electrical and thermal symmetry in the chamber body 1242, particularly in the processing region 1202, enabling more uniform plasma formation in the processing region 1202 and improving plasma density control across the surface of the substrate 1205 during processing.

[0112] Similarly, the discharge passage 1289 is positioned within the upper liner assembly 1244 symmetrically with respect to the central axis (CA). The discharge passage 1289 allows gas to be discharged from the chamber body 1242 through the processing area 1202, the discharge area 1204, and the exhaust port 1296. The exhaust port 1296 is centered around the central axis (CA) of the chamber body assembly 1240 so that the gas is evenly drawn out through the discharge passage 1289.

[0113] Referring again to Figure 12A, a conductive mesh liner 1295 is positioned on the upper liner assembly 1244. The mesh liner 1295 may be constructed from a conductive process-compatible material such as aluminum, stainless steel, and / or yttria (e.g., yttria-coated aluminum). The mesh liner 1295 may have a number of openings (not shown) formed through it. The openings are symmetrically arranged with respect to the central axis of the mesh liner 1295, allowing exhaust gases to be uniformly drawn through them, which in turn facilitates uniform plasma formation within the processing area 1202, enabling better control of plasma density and gas flow within the processing area 1202. In one embodiment, the central axis of the mesh liner 1295 is aligned with the central axis (CA) of the chamber body assembly 1240.

[0114] The mesh liner 1295 can be electrically connected to the upper liner assembly 1244. When the RF plasma is present within the processing region 1202, the RF current seeking a return path to ground can travel along the surface of the mesh liner 1295 to the outer wall 1247 of the upper liner assembly 1244. Thus, the annular symmetrical configuration of the mesh liner 1295 provides a symmetrical RF return to ground, bypassing any geometric asymmetry of the upper liner assembly 1244.

[0115] In the embodiment, one or more sensor modules may be positioned at various locations throughout the processing unit 1200. For example, a sensor module (or part of a sensor module) may be positioned in one or more locations, including, but not limited to, along the side wall of the chamber 1242, within the discharge area 1204, adjacent to the processing ring 1297 (e.g., integrated with the mesh liner 1295), or integrated with the lid assembly 1210. Thus, detection of various chamber conditions at multiple locations throughout the processing unit 1200 can be determined. The chamber conditions provided by one or more sensor modules may be used to modify one or more parameters, such as processing policy parameters, the cleaning schedule of the processing unit 1200, or parts replacement decisions.

[0116] In the embodiment, the processing unit 1200 includes, for example, a chamber wall capacitive sensor module at location 1299A. In the embodiment, the processing unit 1200 includes, for example, a chamber lid capacitive sensor module at location 1299B. In the embodiment, the processing unit 1200 includes a discharge port capacitive sensor module in the chamber floor or inside or adjacent to the discharge port (for example, at location 1299D). In the embodiment, the processing unit 1200 includes, for example, a ring structure capacitive sensor module at location 1299C.

[0117] In one embodiment, the processing unit 1200 includes two or more different capacitive sensors selected from the group consisting of a chamber wall capacitive sensor module, a chamber lid capacitive sensor module, a chamber floor or outlet capacitive sensor module, and a ring structure capacitive sensor module. In another embodiment, the processing unit 1200 includes two or more identical capacitive sensors selected from the group consisting of a chamber wall capacitive sensor module, a chamber lid capacitive sensor module, a chamber floor or outlet capacitive sensor module, and a ring structure capacitive sensor module.

[0118] In the embodiments, one or more of the chamber wall capacitive sensor module, chamber lid capacitive sensor module, chamber floor or outlet capacitive sensor module, and / or ring structure capacitive sensor module further include a thermal sensor. In one embodiment, such a chamber wall capacitive sensor module, chamber lid capacitive sensor module, or chamber floor or outlet capacitive sensor module includes a capacitive sensor adjacent to the processing area 1202 and a thermal sensor distal to the processing area 1202. In one embodiment, the ring structure capacitive sensor module includes a capacitive sensor adjacent to the substrate 1205 support area and a thermal sensor distal to the substrate 1205 support area.

[0119] While the processing apparatus 1200 in Figures 12A and 12B provides a specific example of a tool that can benefit from including a sensor module, such as the sensor module disclosed herein, it should be understood that embodiments are not limited to the specific configurations in Figures 12A and 12B. In other words, many different plasma chamber configurations, such as the plasma chamber configurations used in the microelectronics manufacturing industry, can also benefit from the integration of sensor modules as disclosed herein.

[0120] For example, Figure 13 is a cross-sectional view of a processing apparatus 1300, which may include one or more capacitive sensor modules as described above, according to an embodiment. The plasma processing apparatus 100 may be a plasma etching chamber, a plasma chemical vapor deposition chamber, a physical vapor deposition chamber, a plasma processing chamber, an ion implantation chamber, or other suitable vacuum processing chamber.

[0121] The processing apparatus 1300 includes a grounded chamber 1342. In some examples, the chamber 1342 may also include a liner (not shown) to protect the inner surface of the chamber 1342. The chamber 1342 may include a processing area 1302 and an exhaust area 1304. The chamber 1342 may be sealed with a lid assembly 1310. Process gas is supplied from one or more gas sources 1306 through a mass flow controller 1349 to the lid assembly 1310 and then to the chamber 1305. An exhaust port 1396 adjacent to the exhaust area 1304 can maintain a desired pressure in the chamber 1342 and remove by-products from processing in the chamber 1342.

[0122] The lid assembly 1310 generally includes an upper electrode comprising a showerhead plate 1316 and a heat transfer plate 1318. The lid assembly 1310 is insulated from the chamber 1342 by an insulating layer 1313. The upper electrode is connected to a source RF generator 1303 through a matching device (not shown). The source RF generator 1303 may have a frequency between, for example, 100 MHz and 180 MHz, and in a particular embodiment, is in the 162 MHz band. Gas from the gas source 1306 enters the manifold 1320 within the showerhead plate 1316 and exits into the processing area 1302 of the chamber 1342 through an opening into the showerhead plate 1316. In an embodiment, the heat transfer plate 1318 includes a channel 1319 through which a heat transfer fluid flows. The showerhead plate 1316 and the heat transfer plate 1318 are manufactured from an RF conductive material such as aluminum or stainless steel. In certain embodiments, instead of (or in addition to) the showerhead plate 1316, a gas nozzle or other suitable gas distribution assembly is provided for distributing process gas into the chamber 1342.

[0123] The processing area 1302 may include a lower electrode 1361 to which the substrate 1305 is fixed. The portion of the processing ring 1397 surrounding the substrate 1305 may be supported by the lower electrode 1361. The substrate 1305 may be inserted into (or extracted from) the chamber 1342 through the slit valve tunnel 1341. For simplification, the door for the slit valve tunnel 1341 is omitted. The lower electrode 1361 may be an electrostatic chuck. The lower electrode 1361 may be supported by a support member 1357. In embodiments, the lower electrode 1361 may include a plurality of heating zones. Each zone is independently controllable to a temperature setpoint. For example, the lower electrode 1361 may include a first heating zone close to the center of the substrate 1305 and a second heating zone close to the periphery of the substrate 1305. The bias power RF generator 1325 is connected to the lower electrode 1361 through a match 1327. The bias power RF generator 1325 supplies bias power to energize the plasma as needed. The bias power RF generator 1325 may have a low frequency, for example, between approximately 2 MHz and 60 MHz, but in certain embodiments, it is within the 13.56 MHz band.

[0124] In the embodiment, one or more sensor modules may be positioned at various locations throughout the processing unit 1300. For example, a sensor module (or part of a sensor module) may be positioned at one or more locations, for example, but not limited to, location 1399A along the side wall of chamber 1342, location 1399D near or within discharge area 1304, location 1399C adjacent to or inside processing ring 1397, and / or integrated with lid assembly 1310 at location 1399B, etc. Thus, detection of various chamber conditions at multiple locations throughout the processing unit 1300 can be determined. The chamber conditions provided by one or more sensor modules may be used to modify one or more parameters, for example, processing policy parameters, cleaning schedule for processing unit 1300, and part replacement decisions.

[0125] Referring here to Figure 14, a block diagram showing an exemplary computer system 1460 of a processing tool is shown according to an embodiment. In the embodiment, the computer system 1460 is coupled to the processing tool and controls the processing in the processing tool. The computer system 1460 may be communicatively coupled to one or more sensor modules as disclosed herein. The computer system 1460 may utilize the outputs from one or more sensor modules to modify one or more parameters, for example, processing strategy parameters, a cleaning schedule for the processing tool, or a parts replacement decision.

[0126] Computer system 1460 may be connected to (e.g., networked) other machines in a local area network (LAN), intranet, extranet, or the internet. Computer system 1460 may act as a server or client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system 1460 may be a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), mobile phone, web appliance, server, network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or distinct) that specify the actions performed by that machine. Furthermore, although only a single machine is shown as computer system 1460, the term “machine” should also be interpreted to include any collection of machines (e.g., computers) that individually or collectively execute a set (or set) of instructions in order to perform any one or more of the methods described herein.

[0127] The computer system 1460 may include a computer program product or software 1422 having a non-transient, machine-readable medium on which instructions are stored. These instructions may be used to program the computer system 1460 (or other electronic device) to perform the processing according to the embodiment. The machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, the machine-readable (e.g., computer-readable) medium includes machine (e.g., computer)-readable storage media (e.g., read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.), machine (e.g., computer)-readable transmission media (e.g., propagated signals in electrical, optical, acoustic, or other forms (e.g., infrared signals, digital signals, etc.)), etc.

[0128] In this embodiment, the computer system 1460 includes a system processor 1402, a main memory 1404 (e.g., read-only memory (ROM), dynamic random access memory (DRAM) (flash memory, synchronous DRAM (SDRAM), or rhombus DRAM (RDRAM)), static memory 1406 (e.g., flash memory or static random access memory (SRAM)), and a secondary memory 1418 (data storage device, etc.), all of which communicate with each other via a bus 1430.

[0129] The system processor 1402 represents one or more general-purpose processing devices (e.g., a microsystem processor or a central processing unit). More specifically, the system processor may be a composite instruction set arithmetic (CISC) microsystem processor, a reduced instruction set arithmetic (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system processor implementing another instruction set, or a system processor implementing a combination of instruction sets. The system processor 1402 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 system processor (DSP), or a network system processor. The system processor 1402 is configured to execute processing logic 1426 for performing the steps described herein.

[0130] The computer system 1460 may further include a system network interface device 1408 for communicating with other devices or machines. The computer system 1460 may also include a video display unit 1410 (e.g., a liquid crystal display (LCD), a light-emitting diode display (LED), or a cathode ray tube (CRT), an alphanumeric input device 1412 (e.g., a keyboard), a cursor control device 1414 (e.g., a mouse), and a signal generating device 1416 (e.g., a speaker).

[0131] The secondary memory 1418 may include a machine-accessible storage medium 1431 (or more specifically, a computer-readable storage medium) that stores one or more instruction sets (e.g., software 1422) that perform any one or more of the methods or functions described herein. The software 1422 may also reside, all or at least partially, in the main memory 1404 and / or the system processor 1402 while being executed by the computer system 1460, and the main memory 1404 and the system processor 1402 may also constitute the machine-readable storage medium. The software 1422 may further be transmitted or received over the network 1461 via the system network interface device 1408. In embodiments, the network interface device 1408 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0132] In exemplary embodiments, the machine-accessible storage medium 1431 is shown as a single medium, but the term “machine-readable storage medium” should be interpreted to include a single or multiple mediums that store one or more instruction sets (e.g., a centralized or distributed database, and / or associated caches and servers). The term “machine-readable storage medium” should also be interpreted to include any medium capable of storing or encoding a set of instructions executed by a machine, and causing the machine to execute any one or more of these methods. Accordingly, the term “machine-readable storage medium” should be interpreted to include, but not be limited to, solid-state memory, optical media, and magnetic media.

[0133] Accordingly, embodiments of the present disclosure include capacitive sensors and capacitive sensing locations for monitoring the plasma chamber state.

[0134] The above description of the illustrated embodiments of the embodiments of the Disclosure, including those described in the Abstract, is not intended to be exhaustive or to limit the Disclosure to the exact form disclosed. While specific embodiments and examples of the Disclosure are described herein for illustrative purposes only, various equivalent modifications are possible within the scope of the Disclosure, as those skilled in the art will recognize.

[0135] Examples of these modifications may be made to this disclosure in light of the detailed description above. The terms used in the following claims should not be construed as limiting this disclosure to the specific embodiments disclosed herein and in the claims. Rather, the scope of this disclosure is entirely determined by the following claims, which shall be construed in accordance with established principles of claims interpretation.

[0136] Exemplary Embodiment 1: A plasma chamber monitoring system includes a plurality of capacitive sensors, a capacitive digital converter, and an application process server connected to the capacitive digital converter, the application process server including system software. The capacitive digital converter includes an isolated interface connected to the plurality of capacitive sensors, a power supply connected to the isolated interface, field-programmable gate array firmware connected to the isolated interface, and an application-specific integrated circuit connected to the field-programmable gate array firmware.

[0137] Exemplary Embodiment 2: The plasma chamber monitoring system according to Exemplary Embodiment 1, wherein the application-specific integrated circuit for the capacitive digital converter is an etherCAT application-specific integrated circuit.

[0138] Exemplary Embodiment 3: The etherCAT application-specific integrated circuit provides seamless integration of system software and simultaneous control of several sensors among multiple capacitive sensors in the plasma chamber monitoring system described in Exemplary Embodiment 2.

[0139] Exemplary Embodiment 4: The etherCAT application-specific integrated circuit is a plasma chamber monitoring system according to Exemplary Embodiment 2 or 3, which initializes and calibrates individual sensors of a plurality of capacitive sensors.

[0140] Exemplary Embodiment 5: An applied process server is a plasma chamber monitoring system according to any one of the exemplary embodiments 1 to 4, which synchronizes capacitive sensor data from multiple capacitive sensors with a process policy.

[0141] Exemplary Embodiment 6: A plasma chamber monitoring system according to any of the exemplary embodiments 1 to 5, wherein the field-programmable gate array firmware of the capacitive digital converter provides deterministic timing and simultaneous communication with some of the multiple capacitive sensors.

[0142] Exemplary Embodiment 7 A plasma chamber monitoring system according to any one of the exemplary embodiments 1 to 6, wherein the individual sensors of a plurality of capacitive sensors are connected in parallel to the isolation interface of a capacitive digital converter.

[0143] Exemplary Embodiment 8 A plasma chamber monitoring system according to any one of the exemplary embodiments 1 to 7, wherein each individual sensor of a plurality of capacitive sensors is connected to an isolated interface of a capacitive digital converter by interconnections including an inter-integrated bus and power lines.

[0144] Exemplary Embodiment 9 A plasma chamber monitoring system according to any of the exemplary embodiments 1 to 8, wherein one or more of the multiple sensors are located on the chamber wall of the plasma chamber.

[0145] Exemplary Embodiment 10 A plasma chamber monitoring system according to any of the exemplary embodiments 1 to 9, wherein one or more of the multiple sensors are located on the chamber lid of the plasma chamber.

[0146] Exemplary Embodiment 11 A plasma chamber monitoring system according to any of the exemplary embodiments 1 to 10, wherein one or more of the sensors are located in the exhaust region of the plasma chamber.

[0147] Exemplary Embodiment 12 A plasma chamber monitoring system according to any of the exemplary embodiments 1 to 11, wherein one or more of the multiple sensors are located in the process ring within the plasma chamber.

[0148] Exemplary Embodiment 13: An interconnection for a plasma chamber monitoring system includes a first connector for connecting to a capacitive digital converter of a capacitive sensor module, a second connector for connecting to electronic equipment and an external power supply, and a shielded cable connected to and between the first and second connectors. The shielded cable includes a shielding metal for physically connecting the interconnection to the frame of the plasma chamber, power lines housed within the shielding metal, ground lines housed within the shielding metal, and one or more communication lines housed within the shielding metal.

[0149] Exemplary Embodiment 14: The interconnection described in Exemplary Embodiment 13, wherein the power lines housed within the shielding metal are 3-4 volt power lines.

[0150] Exemplary Embodiment 15: The interconnection according to Exemplary Embodiment 13 or 14, wherein each of the one or more communication lines housed within the shield metal is an inter-integrated bus or includes an inter-integrated bus.

[0151] Exemplary Embodiment 16: An interconnection according to any of the exemplary embodiments 13 to 15, wherein the grounding line housed within the shielding metal provides a common ground for the capacitive sensor module and electronic equipment.

[0152] Exemplary Embodiment 17: One or more communication lines housed within a shielding metal are interconnected according to any of the exemplary embodiments 13 to 16, synchronizing sensor data clocking.

[0153] Exemplary Embodiment 18: The interconnection according to any of the exemplary embodiments 13 to 17, wherein the sensor of the capacitive sensor module is for being located on the chamber wall of the plasma chamber.

[0154] Exemplary Embodiment 19: The sensor of the capacitive sensor module is for being located in the chamber lid of the plasma chamber, as described in any of the exemplary embodiments 13 to 18.

[0155] Exemplary Embodiment 20: The sensor of the capacitive sensor module is for positioning in the exhaust region of the plasma chamber, as described in any of the exemplary embodiments 13 to 19.

[0156] Exemplary Embodiment 21: The sensor of the capacitive sensor module is intended to be located in the process ring within the plasma chamber, as described in any of the exemplary embodiments 13 to 20 of the interconnection.

[0157] Exemplary Embodiment 22 A method for integrating data for plasma chamber state monitoring includes streaming data from a capacitive sensor module to a data server. The data includes capacity data and temperature data. This method also includes collecting data on an application process server. This method also includes correlating the data with one or more process policy operations. This method also includes synchronizing the capacitive sensor module with one or more process policy operations.

[0158] Exemplary Embodiment 23: The method according to Exemplary Embodiment 22, further comprising performing data processing and parametric extraction after collecting data on an application process server and before correlating the data into one or more process policy operations.

[0159] Exemplary Embodiment 24: The method according to Exemplary Embodiment 23, wherein performing data processing includes filtering the data and denoising the data.

[0160] Exemplary Embodiment 25 The method according to Exemplary Embodiment 24, wherein filtering and denoising the data includes using a moving average approach.

[0161] Exemplary Embodiment 26: The method according to any of the exemplary embodiments 23 to 25, which includes performing data processing and parametric extraction, and includes regression modeling of the data.

[0162] Exemplary Embodiment 27 The method according to any one of the exemplary embodiments 22 to 26, further comprising monitoring one or more parameters of one or more process policy operations using a capacitive sensor module.

[0163] Exemplary Embodiment 28 The method of Exemplary Embodiment 27, further comprising determining the clean / dirty status of a plasma chamber based on monitoring one or more parameters of one or more process policy operations using a capacitive sensor module.

[0164] Exemplary Embodiment 29 Plasma chamber state monitoring is performed on the chamber wall of the plasma chamber, as described in any of the exemplary embodiments 22 to 28.

[0165] Exemplary Embodiment 30 Plasma chamber state monitoring is performed on the chamber lid of the plasma chamber, as described in any of the exemplary embodiments 22 to 29.

[0166] Exemplary Embodiment 31 Plasma chamber state monitoring is performed in the exhaust region of the plasma chamber, according to any one of the exemplary embodiments 22 to 30.

[0167] Exemplary Embodiment 32 Plasma chamber state monitoring is performed in a process ring within the plasma chamber, according to any of the exemplary embodiments 22 to 31.

Claims

1. An interconnect for a plasma chamber monitoring system, A first connector for connecting the capacitive sensor module to the capacitive digital converter, A second connector for connecting to electronic equipment and an external power supply, A shielded cable connected to the first connector and the second connector and between them The shielded cable is equipped with, A shielding metal for physically connecting the plasma chamber frame between the first connector and the second connector, The power line housed within the aforementioned shield metal, The grounding line housed within the shield metal, and One or more communication lines housed within the aforementioned shield metal Interconnections, including

2. The interconnection according to claim 1, wherein the power line housed within the shield metal is a 3-4 volt power line.

3. The interconnection according to claim 1, wherein each of the one or more communication lines housed within the shield metal is an inter-integrated bus or includes an inter-integrated bus.

4. The interconnection according to claim 1, wherein the ground line housed within the shield metal provides a common ground for the capacitive sensor module and the electronic equipment.

5. The interconnection according to claim 1, wherein the one or more communication lines housed within the shield metal synchronize sensor data clocking.

6. Plasma chamber and A plasma chamber monitoring system connected to the aforementioned plasma chamber and A system equipped with, The plasma chamber monitoring system includes an interconnection, and this interconnection is A first connector for connecting the capacitive sensor module to the capacitive digital converter, A second connector for connecting to electronic equipment and an external power supply, A shielded cable connected to the first connector and the second connector and between them The shielded cable is equipped with, A shielding metal for physically connecting the first connector and the second connector to the frame of the plasma chamber, The power line housed within the aforementioned shield metal, The grounding line housed within the shield metal, and One or more communication lines housed within the aforementioned shield metal A system equipped with these features.

7. The system according to claim 6, wherein the power line housed within the shield metal is a 3-4 volt power line.

8. The system according to claim 6, wherein each of the one or more communication lines housed within the shield metal is an inter-integrated bus or includes an inter-integrated bus.

9. The system according to claim 6, wherein the ground line housed within the shield metal provides a common ground for the capacitive sensor module and the electronic equipment.

10. The system according to claim 6, wherein the one or more communication lines housed within the shield metal synchronize sensor data clocking.

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