Monitoring device with signal monitoring assembly for monitoring microwave plasma and method

Abstract

A microwave plasma monitoring system including one or more sensors structured to generate a signal based on a measured parameter of the microwave plasma, a plasma monitoring device in communication with the one or more sensors, and at least one measurement device in communication with the plasma monitoring device. The plasma monitoring device includes a signal processing assembly that includes one or more high-gain amplifiers that receive and amplify one or more weak frequency components of the signal generated by the one or more sensors, and one or more filters in communication with the one or more high-gain amplifiers that attenuate or block one or more undesired frequency components of the signal. The at least one measurement device is structured to convert the amplified and filtered signal from the plasma monitoring device to a value of the measured parameter and to output the value of the measured parameter.

Description

MONITORING DEVICE WITH SIGNAL MONITORING ASSEMBLY FOR MONITORING MICROWAVE PLASMA AND METHODCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to, and the benefit of, U.S. Provisional Patent Application Serial No. 63 / 760,350, filed on February 19, 2025. The entire contents of said application are incorporated by reference.TECHNOLOGICAL FIELD

[0002] The disclosure is directed to the field of manufacturing and more specifically to a monitoring device with a plasma signal monitoring assembly and associated method for monitoring a microwave plasma as part of a manufacturing process.BACKGROUND

[0003] Manufacturing processes, such as semiconductor manufacturing processes often involve the use of microwave plasma to enable precise etching, deposition, and cleaning. Monitoring the characteristics of microwave plasma in real-time is critical to maintaining process consistency and achieving high-quality outcomes. However, current monitoring systems are often limited by signal interference, low sensitivity, and insufficient frequency selectivity.

[0004] These are just some of the disadvantages associated with monitoring systems for microwave plasmas that are currently used.50100100.1BRIEF SUMMARY OF THE INVENTION

[0005] The following disclosure relates to embodiments of a signal processing assembly including one or more filters, switches, and amplifiers for monitoring signals from a microwave plasma in semiconductor processes. Embodiments of the disclosed assembly include frequency-selective filters to isolate plasma signals and a low noise, high-gain amplifier to enhance signal strength. Tunable components allow adaptation to various plasma environments, ensuring accurate real-time monitoring. Embodiments of the disclosed invention minimizes signal interference, enhances sensitivity, and provides reliable feedback for process control, enabling improved performance in semiconductor manufacturing applications.

[0006] Aspects of the following disclosure are directed to embodiments of a microwave plasma monitoring system including one or more sensors configured to generate a signal based on a measured parameter of the microwave plasma, a plasma monitoring device in communication with the one or more sensors and including signal monitoring assembly that includes, and at least one measurement device in communication with the plasma monitoring device. In some embodiments, the signal monitoring assembly includes one or more high-gain amplifiers that receive and amplify one or more weak frequency components of the signal generated by the one or more sensors, and one or more filters in communication with the one or more high-gain amplifiers that attenuate or block one or more undesired frequency components of the signal. In some embodiments, the at least one measurement device is configured to convert the amplified and filtered signal from the plasma monitoring device to a value of the measured parameter and to output the value of the measured parameter.

[0007] In some embodiments of the system, the signal monitoring assembly includes at least two filters and at least one switch positioned between the one or more high-gain250100100.1amplifiers and configured to switch between the at least two filters to adapt to different plasma environments or different process conditions. In some embodiments of the system, the signal monitoring assembly is positioned in a housing that includes an input interface to receive signals from the one or more sensors and an output interface to output amplified and filtered signals to the measurement device. In some embodiments of the system, at least one of: a filter setting; or (ii) an amplifying setting, is adjusted based on the value of the measured parameter. In some embodiments of the system, the signal processing assembly and the measurement device are positioned in a single housing that includes an input interface to receive signals from the one or more sensors and an output interface to output the value of the measured parameter. In some embodiments of the system, each of the one or more sensors requires a signal monitoring assembly. In some embodiments of the system, the at least one measurement device includes at least one RF balun. In some embodiments of the system, the at least one measurement device includes at least one of: (i) a dual matched amplifier; or (ii) a differential amplifier.

[0008] Aspects of the following disclosure are directed to embodiments of a method of monitoring a micro wave plasma. In some embodiments, the method includes measuring a parameter of the microwave plasma in a process chamber using a sensor and generating a signal via the sensor in response to the detected parameter and transmitting the signal to a plasma monitoring device. In some embodiments, the method includes filtering out undesired frequencies and amplifying desired frequencies via the plasma monitoring device to produce an amplified signal that is output to a measurement device. In some embodiments, the method includes converting the amplified signal to a plasma parameter value via the measurement device and outputting the plasma parameter value.

[0009] In some embodiments, the method further includes adjusting at least one of:350100100.1a filter setting; or (ii) an amplifying setting, based on the plasma parameter value. In some embodiments, the method further includes outputting the plasma parameter value to monitoring equipment, wherein the monitoring equipment includes at least one of: (i) a spectrum analyzer; (ii) a time domain signal analyzer; or (iii) a semiconductor manufacturing process control systemBRIEF DESCRIPTION OF DRAWINGS

[0010] A more particular description of the invention briefly summarized above may be had by reference to the embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. Thus, for further understanding of the nature and objects of the invention, references can be made to the following detailed description.

[0011] Fig. 1 schematically illustrates an embodiment of a plasma monitoring device with an embodiment of a signal monitoring assembly configured to switch between two filters, according to embodiments of the disclosure.

[0012] Fig. 2 schematically illustrates an embodiment of a plasma monitoring device with a signal monitoring assembly including a single filter, according to embodiments of the disclosure.

[0013] Fig. 3 schematically illustrates an embodiment of a plasma monitoring system including a plasma sensor, the plasma monitoring device of Fig. 1, and a measurement device, according to embodiments of the disclosure.

[0014] Fig. 4 schematically illustrates another embodiment of a plasma monitoring450100100.1system including a plasma sensor, a plasma monitoring device of Fig. 2, and a measurement device included in a single housing, according to embodiments of the disclosure.

[0015] Figs. 5a-d graphically illustrate frequency responses for: (a) a bandwidth filter; (b) a high pass filter; (c) a low pass filter; and (d) notch / band stop filter, according to embodiments of the disclosure.

[0016] Fig. 6 is a flow chart of an embodiment of a method for monitoring a plasma, according to embodiments of the disclosure.DETAILED DESCRIPTION

[0017] The following discussion relates to various embodiments of a microwave plasma monitoring assembly. It will be understood that the herein described versions are examples that embody certain inventive concepts as detailed herein. To that end, other variations and modifications will be readily apparent to those of sufficient skill. In addition, certain terms are used throughout this discussion in order to provide a suitable frame of reference with regard to the accompanying drawings. These terms such as “upper,” “lower,” “forward,” “rearward,” “interior,” “exterior,” “front,” “back,” “top,” “bottom,” “inner,” “outer,” “first,” “second,” and the like are not intended to limit these concepts, except where so specifically indicated. The terms “about” or “approximately” as used herein may refer to a range of 80%- 125% of the claimed or disclosed value. With regard to the drawings, their purpose is to depict salient features of the microwave plasma monitoring assembly and are not specifically provided to scale.

[0018] An embodiment of a microwave plasma monitoring device 100 including a signal monitoring assembly 101 is shown in Figs. 1 and 2. In some embodiments, the microwave plasma monitoring device 100 includes a housing 100a that at least partially contains the signal550100100.1monitoring assembly 101 and may be installed and uninstalled as a single unit. In some embodiments, the micro wave plasma monitoring device 100 is configured to receive input signals from one or more plasma sensors 200, such as a magnetic and / or an electric field sensors and monitor a microwave plasma 50 in a process chamber 20 during a semiconductor manufacturing process using the received input signals. In some embodiments, such as shown in Fig. 2, the signals are received from the one or more sensors 200 at an input interface 180 of the microwave plasma monitoring device 100. In some embodiments, the input interface 180 may include or more connections to the one or more sensors 200 and / or user inputs, such as buttons, which may be actuated to adjust functions of the plasma monitoring device 100 and specifically the signal monitoring assembly 101. In some embodiments, the signal monitoring assembly 101 of the plasma monitoring device 100 processes the signals received from the plasma sensor 200 and transmits the processed signal to a measurement device 300. In some embodiments, such as shown in Fig. 2, the processed signal is transmitted to the measurement device 300 via an output interface 185. In some embodiments, the In some embodiments, the measurement device 300 is configured to generate a measurement parameter of the plasma 50 based on the plasma monitoring signal.

[0019] In some embodiments, very specific plasma conditions are necessary for carrying out certain semiconductor manufacturing processes. The main signal that excites the plasma 50 is large in comparison to the harmonic content being measured. For example, when a 40.68 MHz and a 60 MHz source are used, then these can be in the kilowatt range of power. They are often pulsed on and off and the harmonic content produced in the plasma 50 may be less than that by several orders of magnitude. Accordingly, in some embodiments, such as in Figs. 1 and 3, the signal monitoring assembly 101 of the plasma monitoring device 100 includes one or more frequency selective filters 106, 108, 110, 112 that isolate frequencies of interest from the650100100.1microwave plasma 50. In this manner, the signal monitoring assembly 101 of the plasma monitoring device 100 minimizes, attenuates, or otherwise blocks unwanted high amplitude or undesired signals or unwanted noise. For example, when 40.68 MHz and a 60 MHz source are used, then these can be in the kilowatt range of power producing a high signal in the presence of the lower level signals being measured. They are often pulsed on and off and the desired harmonic content produced in the plasma may be less than that by several orders of magnitude. In some embodiments, the signal monitoring assembly 101 of the plasma monitoring device 100 includes at least one low noise, high-gain amplifier 102 configured to enhance weak plasma signals obtained by the one or more sensors 200 to improve the accuracy of the signal analysis. In some embodiments, the weak plasma signals are near the noise floor of the measuring instrument. In some embodiments, the weak plasma signals are on the order of -1 lOdB. In some embodiments, the signal monitoring assembly 101 of the plasma monitoring device 100 includes at least two low noise, high-gain amplifiers 102, 104 that enhance weak plasm signals from the one or more sensors 200 in order to improve the accuracy of the signal analysis. In some embodiments, the measurement device 300 includes an RF balun 302. In some embodiments, an output from the amplifier(s) 102, 104 is fed into the RF balun 302, which further rejects unwanted noise. In some embodiments, the measurement device 300 includes a dual matched amplifier, or a differential amplifier instead of the balun 302. In some embodiments, the micro wave plasma monitoring device 100, 150 is in communication or otherwise integrated with monitoring equipment 30 (Fig.4) configured to facilitate real-time feedback during a semiconductor manufacturing process. In some embodiments, the monitoring equipment 30 includes a frequency monitoring device(s), frequency analyzer(s), time domain signal analyzer(s), and / or process other process control systems. In some embodiments, the signal monitoring assembly 101 of the micro wave plasma750100100.1monitoring device 100 further includes one or more tunable or switchable components 103, 105, 107, 109 configured to adapt to different plasma environments and process conditions. For example, the switchable components 103, 105, 107, 109 could be set during the setup of the plasma monitoring device 100 for each use case. In this manner, the plasma monitoring device 100 would be tailored for each system or even each step of the semiconductor manufacturing process. For example, ff the 40.68 MHz was on, then this would be one set of conditions, and if the 60 and 40.68 MHz were on together, then this would be another set of conditions for, for example, another system or process step. In some embodiments, the microwave plasma monitoring device 100 further includes multiple channels for multiple sensors 200, for example magnetic and / or electric field sensors. In some embodiments, each of the multiple channels includes its own signal monitoring assembly 101, 151. Accordingly, this embodiment of the signal monitoring assembly improves signal clarity, enhances sensitivity, and ensures reliable monitoring, enabling better control over semiconductor processes.

[0020] Referring to Figs, 3 and 4, in some embodiments, the plasma monitoring system 10, 10’, 11 includes a signal monitoring assembly 101, 151 that includes one or more a high pass, band-pass, band-stop filters 106, 108, 110, 112, 156, 158 that are configured to isolate specific frequency ranges associated with plasma emissions while rejecting noise. In some embodiments, the filter(s) may use LC circuits, SAW filters, or other advanced filtering topologies. The signal monitoring assembly 101, 151 may further include one or more low-noise, high-gain amplifier 102, 104, 152, 154 configured to boost the filtered signal for downstream processing. In some embodiments, the amplifier 102, 104, 152, 154 may include adjustable gain controls configured to optimize signal output.

[0021] Referring to Fig. 4, another embodiment of the plasma monitoring device850100100.1150 is shown schematically. In this embodiment, the plasma monitoring device 150 comprises a signal monitoring assembly 151 including two (2) low noise, high-gain amplifiers 152, 154 that are each electrically coupled to a frequency selective filter 156, 158. In this embodiment, there are no switches so that each amplifier 152, 154 outputs a signal to a single filter 156, 158. In some embodiments, the plasma monitoring device 150 further includes multiple channels for multiple sensors, for example magnetic and / or electric field sensors, which improves signal clarity, enhances sensitivity, and ensures reliable monitoring, enabling better control over the plasma processes being monitored. The embodiments of the plasma monitoring device 100, 150 disclosed herein are configured to be positioned outside of a process chamber 20.

[0022] In some embodiments, the one or more plasma sensors 200 are positioned outside of the process chamber 20. In some embodiments, a portion of the sensor 200 may be positioned inside of the process chamber 20. In some embodiments, the sensor or probe 200 is configured to detect signals from a microwave plasma 50. In some embodiments, the sensor 200 may include a single ended or differential probe. In some embodiments, the sensor 200 comprises an electric field probe and / or a magnetic field probe. Accordingly, each sensor 200 requires its own signal monitoring assembly 101, 151.

[0023] In some embodiments, the plasma monitoring system 10’ includes an output interface that transmits the amplified signal from the filter and amplifier assembly 100, 150 to the measurement device 300. In some embodiments, the system further incudes monitoring equipment 30, such as spectrum analyzers, time domain signal analyzers, or semiconductor manufacturing process control systems. In some embodiments, the amplified signal of the system is used for realtime adjustment of filter and amplifier settings. For example, in some embodiments, the real-time adjustment may take place during950100100.1

[0024] Referring to Figs. 5a-d, the filter gain / loss is plotted relative to angular frequency for a bandwidth filter (Fig. 5a); a high pass filter (Fig. 5b); a low pass filter (Fig. 5c); and a notch / band stop filter (Fig. 5d). Referring to Fig. 6, an embodiment of a method 600 of monitoring a plasma will be described. At 602, a parameter of the plasma in a process chamber 20 is detected via a probe 200. A signal is generated by the probe 200 in response to the detected plasma parameter and transmitted to a signal monitoring assembly 101, 151 of a microwave plasma monitoring device 100, 150 at 604. At 606, the signal is processed in the signal monitoring assembly 101, 151 of the microwave plasma device 100, 150 to filter out undesired frequencies and amplify desired lower amplitude spectra. At 608, the amplified signal is output to one or more measurement devices 300 and / or monitoring devices, which convert the signal to a plasma parameter value. At 610, the plasma parameter value is output to an operator and / or used to adjust one or more semiconductor manufacturing processes and / or filter / amplifier settings. In some embodiments, the plasma parameter value is output to the monitoring equipment 30. In some embodiments, a feedback loop is formed by the monitoring equipment automatically adjusting a setting affecting the plasma 50 in the process chamber 20 based on the plasma parameter value.

[0025] While the present invention has been particularly shown and described with reference to certain exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention that can be supported by the written description and drawings. Further, where exemplary embodiments are described with reference to a certain number of elements, it will be understood that the exemplary embodiments can be practiced utilizing either less than or more than the certain number of elements.1050100100.1

Claims

PATENT3222619WO01CLAIMS1. A microwave plasma monitoring system comprising:one or more sensors configured to generate a signal based on a measured parameter of the microwave plasma;a plasma monitoring device in communication with the one or more sensors and comprising signal monitoring assembly that includes,one or more high-gain amplifiers that receive and amplify one or more weak frequency components of the signal generated by the one or more sensors, andone or more filters in communication with the one or more high-gain amplifiers that attenuate or block one or more undesired frequency components of the signal; and at least one measurement device in communication with the plasma monitoring device and configured to convert the amplified and filtered signal from the plasma monitoring device to a value of the measured parameter and to output the value of the measured parameter.

2. The system of claim 1, wherein the signal monitoring assembly comprises at least two filters and at least one switch positioned between the one or more high-gain amplifiers and configured to switch between the at least two filters to adapt to different plasma environments or different process conditions.

3. The system of claim 1, wherein the signal monitoring assembly is positioned in a housing that includes an input interface to receive signals from the one or more sensors and an output interface to output amplified and filtered signals to the measurement device.

4. The system of claim 1 , wherein at least one of: a filter setting; or (ii) an amplifying setting, is adjusted based on the value of the measured parameter.

5. The system of claim 1, wherein the signal monitoring assembly and the at least one measurement device are positioned in a single housing including an input interface to receive signals from the one or more sensors and an output interface to output the value of the measured parameter.1150100100.1PATENT3222619WO016. The system of claim 1, wherein each of the one or more sensors requires a signal monitoring assembly.

7. The system of claim 1, wherein the measurement device includes at least one RF balun.

8. The system of claim 1, wherein the measurement device includes at least one of: (i) a dual matched amplifier; or (ii) a differential amplifier.

9. A method of monitoring a microwave plasma, comprising:measuring a parameter of the microwave plasma in a process chamber using a sensor; generating a signal via the sensor in response to the detected parameter and transmitting the signal to a plasma monitoring device;filtering out undesired frequencies and amplifying desired frequencies via the plasma monitoring device to produce an amplified signal;outputting the amplified signal to a measurement device;converting the amplified signal to a plasma parameter value via the measurement device; andoutputting the plasma parameter value.

10. The method of claim 9, further comprising adjusting at least one of: a filter setting; or (ii) an amplifying setting, based on the plasma parameter value.

11. The method of claim 9, further comprising outputting the plasma parameter value to monitoring equipment, wherein the monitoring equipment includes at least one of: (i) a spectrum analyzer; (ii) a time domain signal analyzer; or (iii) a semiconductor manufacturing process control system.1250100100.1

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