Uniformity Control of Radio Frequency Plasma Processing System

Abstract

A radio frequency plasma processing system includes: a reaction chamber; a susceptor disposed in the reaction chamber; and a plurality of sector plates disposed azimuthally around the susceptor in a ring between the susceptor and the reaction chamber.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 62 / 959,630 filed on January 10, 2020 and U.S. Non-Provisional Patent Application No. 17 / 145,190 filed on January 8, 2021, the contents of which are incorporated herein by reference. Background Art

[0003] Radio frequency (RF) plasma enhanced processing is widely used in semiconductor manufacturing to etch different types of films, deposit thin films at low to moderate processing temperatures, and perform surface treatment and cleaning. This process is characterized by the use of plasma, i.e., partially ionized gas, to generate neutral species and ions from precursors inside a reaction chamber, to provide energy for ion bombardment, and / or to perform other actions. During such processing, there are challenges in controlling the plasma density, and non-uniformity of the plasma within the reaction chamber affects wafer processing uniformity and the yield of the integrated circuit or other device being fabricated.

[0004] Non-uniform plasma density within the reaction chamber may result in non-uniform etch rates or certain characteristics across the substrate. In some systems, a probe is used to monitor the uniformity of the plasma density within the reaction chamber. Such a probe may rely on a coating to be exposed to the plasma environment and may use active electronics to infer the plasma density. Such a system may take milliseconds or longer to respond to changes in the plasma. Emission spectroscopy can also be used to determine the plasma density profile within the reaction chamber, but such a system may require multiple lines of sight through the plasma and use complex analysis to infer non-uniformity. None of these techniques are sensitive and fast enough to effectively address non-uniformity issues and may be more expensive to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] When with Figure 1 The present disclosure can be best understood from the following detailed description when read together. It should be emphasized that, according to standard practice in the industry, various features are not drawn to scale. In fact, for the sake of clarity of discussion, the size of various features can be arbitrarily increased or reduced.

[0006] Figure 1 is a side view schematic diagram of an RF plasma processing system according to an embodiment of the present disclosure.

[0007] Figure 2 is a schematic side view of a plasma chamber according to an embodiment of the present disclosure, wherein high impedance sensors are mounted at various locations on the electrode.

[0008] Figure 3is a cross-sectional view of a dual-plate electrode assembly having a sensor providing a voltage signal through an electrical connector having low shunt capacitance according to an embodiment of the present disclosure.

[0009] Figure 4 is a cross-sectional view of a base with an embedded high impedance voltage sensor according to an embodiment of the present disclosure.

[0010] Figure 5 is a schematic side view of a base according to an embodiment of the present disclosure.

[0011] Figure 6 is a top view of an axisymmetric surface wave propagating across a susceptor according to an embodiment of the present disclosure, wherein the plasma in the reaction chamber is axisymmetric.

[0012] Figure 7 is a top view of transverse electromagnetic surface wave propagation across electrodes according to an embodiment of the present disclosure.

[0013] Figure 8 is a side cross-sectional view of a sensor mounted azimuthally on a reaction chamber according to an embodiment of the present disclosure.

[0014] Fig. 9 is a side cross-sectional view of a sensor mounted azimuthally on a reaction chamber according to an embodiment of the present disclosure.

[0015] Fig.10 is a side schematic cross-sectional view of a reaction chamber according to an embodiment of the present disclosure.

[0016] Fig.11 is a side schematic cross-sectional view of a reaction chamber according to an embodiment of the present disclosure.

[0017] Fig.12 is a partial cross-sectional view of an RF plasma processing system according to an embodiment of the present disclosure.

[0018] Fig.13 is a top view of an RF plasma processing system according to an embodiment of the present disclosure.

[0019] Fig.14 is a partial cross-sectional view of an RF plasma processing system according to an embodiment of the present disclosure.

[0020] Fig.15 is a partial cross-sectional view of an RF plasma processing system according to an embodiment of the present disclosure.

[0021] Fig.16 According to the embodiment of the present disclosure Fig.13 A partial top view of an RF plasma processing system is first shown. DETAILED DESCRIPTION

[0022] An illustrative example of the subject matter claimed below will now be disclosed. For the sake of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual implementation, many implementation-specific decisions may be made to achieve the developer's particular goals, such as compliance with system-related and business-related constraints, which will vary from implementation to implementation. Moreover, it will be appreciated that such development work, even if complex and time-consuming, is a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0023] In addition, as used herein, the article "a" is intended to have its ordinary meaning in the patent field, i.e., "one or more". Here, the term "approximately" when applied to a value generally means within the tolerance range of the equipment used to produce the value, or in some examples, means plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise expressly specified. In addition, the term "substantially" as used herein here, for example, means most, or almost all, or all, or an amount ranging from about 51% to about 100%. In addition, the examples here are for illustrative purposes only and are presented for discussion purposes and not in a limiting manner.

[0024] Steering Figure 1 , a schematic side view of an RF plasma processing system 100 according to an embodiment of the present disclosure is shown. The RF plasma processing system 100 includes a first RF generator 105 and a second RF generator 110, a first impedance matching network 115, a second impedance matching network 120, a sheath 125, a plasma power supply device, and a base 135. The plasma power supply device is such as a showerhead 130 or an equivalent power supply element such as an electrode. As used herein, a plasma power supply device may refer to any device that introduces power to generate plasma, and may include, for example, a showerhead 130 and / or other types of electrodes and antennas, etc.

[0025] The RF plasma processing system 100 may include one or more RF generators 105, 110 that deliver power to a reaction chamber 140 through one or more impedance matching networks 115, 120. RF power flows from the first RF generator 105 through the impedance matching network 115 into the plasma in the reaction chamber 140 to the showerhead 130 or sidewalls, to electrodes outside the showerhead 130, or to an inductive antenna (not shown) that electromagnetically provides power to the plasma, after which the power flows from the plasma to ground and / or to the pedestal 135 and / or to the second impedance matching network 120. In general, the first impedance matching network 115 compensates for changes in load impedance within the reaction chamber 140 by adjusting reactive components, such as variable capacitors, within the first impedance matching network 115 so that the combined impedance of the showerhead 130 and the first impedance matching network 115 is equal to the output of the first RF generator 105, such as 50 ohms. In addition, adjusting the frequency within a range of approximately plus or minus ten percent of the RF power can modify the reflected power. The term "about" is used herein to recognize that in practice, some imprecision with respect to the range or value may occur and still obtain satisfactory results. Such imprecision may be due to, for example, loss or degradation of calibration or drift during operation. However, in these cases, the range or value expressed is the nominal target for the operating conditions at the time of use.

[0026] In some examples, the first RF generator 105 may provide power at an RF frequency between about 400 KHz and 150 MHz, and the second RF generator 110 connected to the base 135 may supply power at an RF frequency lower than the RF frequency of the first RF generator 105, however, in some embodiments, the second RF generator 110 may not supply power at an RF frequency lower than the RF frequency of the first RF generator 105. Typically, the frequencies of the first and second RF generators 105, 110 are such that the RF frequency of the first RF generator 105 is not an integer multiple of the frequency of the second RF generator 110. One or more of the first and second RF generators 105, 110 may also adjust the frequency in order to modify the reflected power.

[0027] The impedance matching networks 115, 120 are designed to adjust their internal reactive elements so that the load impedance matches the source impedance. Generally speaking, low reflected power is considered positive, however, embodiments of the present disclosure ensure that the delivered power and the power reflected back toward the first and second RF generators 105, 110 are maintained in the reaction chamber 140, and even when the reflected power is relatively high, the associated impedance matching networks 115, 120 can monitor the forward and reflected power entering and coming from the reaction chamber 140, and use a motor drive system to make adjustments to adjustable reactive elements, such as vacuum variable capacitors. In some embodiments, electronically controlled capacitors, such as pin diodes of electronic variable capacitors, can be used. The impedance matching networks 115, 120 can include circuit systems that measure the phase and magnitude of the signal to determine the level of forward and reflected power from the expected load. Therefore, even when the amount of reflected power is high, embodiments of the present disclosure can be effective. If there is a large amount of reflected power at a main frequency, the capacitor changes until the reflected power is minimized, for example, less than about 5 watts and / or less than about one percent, or in some embodiments, less than 1 watt during the period. Typically, harmonic frequency signals, including reflected power at harmonic frequencies, are not measured. In addition, the frequency can be adjusted within a range of approximately plus or minus ten percent of the RF power, which can modify the reflected power.

[0028] Despite the many advantages of the RF plasma processing system 100, they have historically been challenged to maintain plasma density control throughout a multi-step process. For example, design tolerances on the order of one percent non-uniformity relative to a nominal density range of the same order remain a challenge. As feature sizes shrink to less than approximately 3 nm and layer thicknesses less than or greater than 10 nm, achieving optimal integrated circuit (IC) yields on each wafer requires increasingly tighter control of plasma and neutral uniformity to levels of 1% or even less. Non-uniform plasma density within a reaction chamber, or an average density that deviates from a desired value beyond a desired range, can be caused by slow changes to the reaction chamber, changes to the RF circuitry, or rapid growth (on the order of less than milliseconds) of parasitic or secondary plasmas, which can result in non-uniformity of nanoscale features across the entire processed wafer due to non-uniform etch rates.

[0029] Because even a one percent difference in etch rate across a wafer can cause yield issues for advanced technologies, and because it often takes a significant amount of time to complete wafer processing to see yield loss, there is a need to timely and accurately detect non-uniform plasma density or plasma density that deviates from a desired range within a reaction chamber within a time period that may require less than approximately 10 microseconds to avoid irreversible deviations from desired feature profiles on the wafer.

[0030] It will be appreciated by those skilled in the art that electromagnetic (EM) surface waves can propagate on surfaces within the RF-powered plasma in the reaction chamber 140. These surface waves are affected by both the fundamental RF drive frequency and the RF harmonics. The average power and power distribution of the harmonics are sensitive functions of the plasma density and uniformity. In this article, the harmonic profile is defined as the spectrum of the surface waves, whose frequencies are integer multiples of the fundamental drive frequency of the reaction chamber 140 based on the RF plasma. For example, if a 2MHz RF drive power is provided to the reaction chamber 140, the injected power will generate surface waves of this frequency, which propagate along the interface between the plasma and the inner surface of the reaction chamber 140. The reflected power can be modified by adjusting the frequency by adding or subtracting approximately ten percent of the RF power. Harmonic surface waves of integer multiple frequencies can also be generated. For example, a 2MHz electromagnetic wave can generate a surface wave of 4, 6, or 8MHz. Both odd and even harmonics (2nd, 3rd, 4th, 5th, etc.) may appear, but in some examples, odd harmonics may be dominant.

[0031] Various aspects of the present disclosure may provide sensor locations on and around the reaction chamber 140 and its components that may allow for detection and analysis of RF surface waves to find the amplitude and phase of fundamental and harmonic waves at multiple points within or near the reaction chamber 140. These waves may be detected by sensing surface voltages or surface currents on the surfaces of the chamber components. In some embodiments, the sensor for voltage will include a pickup configured at or near the surface of an electrode, pedestal base, chamber wall, or strap and a conductive line that communicates the signal to a connector or cable. The current sensor may include a conductive element that may include one or more loops or partial loops or linear conductors, wherein one end of the conductive element is at a reference potential, which may be an electrical ground.

[0032] Multiple sensors, such as four or more, can be positioned on a chamber component, as will be discussed in detail below, at different angles about the chamber axis of symmetry for measuring surface voltages or currents associated with such surface waves. Here, the angle measured about the axis of symmetry from a reference point of the chamber is defined as an azimuth angle. In some embodiments, such sensors can be positioned at approximately the same distance from the axis of symmetry of the chamber.

[0033] The sensor can be mounted at various locations on or around the reaction chamber and / or its components. For example, the sensor can be mounted on the surface of an electrode, such as the surface of the pedestal 135 and / or the showerhead 130. The sensor can also be mounted on the base of an electrode inside or outside the vacuum environment. The sensor can be mounted on one or more metal wall surfaces of the reaction chamber 140, on an inner or outer wall area containing a dielectric material, or on an antenna that can be used to inductively provide power to the plasma. The sensor can also be placed on a passive antenna that can be used to sense EM waves on the plasma boundary, or on or near multiple conductive buses or strips that connect the first or second impedance matching network 115, 120 to electrodes, antennas, or other components that transmit power to the plasma in the reaction chamber 140, such as the pedestal 135 and / or the showerhead 130. The sensor can also be connected to an electrical ground. Therefore, the sensor can pick up signals from different parts of the RF plasma processing system 100 because they propagate on the surfaces of their respective components.

[0034] At the electrode-plasma interface, e.g. Figure 1 In the sheath 125 in the electrode, a spectrum of RF harmonics is generated, and the waves propagate in all directions, so the amplitude and phase of all wave components will vary with the position on the electrode or support base. Such waves also propagate along the inner surface of the metal wall adjacent to the plasma and propagate through any dielectric wall that may be adjacent to the plasma. The amplitude and phase of such waves change in response to changes in the plasma, for example, in response to changes in plasma density and non-uniformity, with a response time of the order of a few microseconds. In addition, the frequency and phase distribution of the RF harmonic surface waves propagating on the electrode-plasma interface determines the frequency and phase distribution of the harmonic surface waves propagating along the electrode base toward the impedance matching network 115, 120 on the surface or wall connected to the electrode or plasma-wall interface. In the case of an inductive plasma, the signal, for example, the fundamental wave and the harmonic wave, can propagate back to the antenna and then propagate to the impedance matching network that feeds the antenna. The frequency and phase distribution of both fundamental and harmonic RF waves can be monitored on a microsecond time scale with sensors mounted on these surfaces and compared to specified ranges and phase relationships as an indicator of plasma asymmetry or changes in plasma density or conductivity. Signals from such sensors can be transmitted by cables or other means to detectors which analyze the component frequencies of the signal to produce amplitude and phase values ​​for each frequency component at each sensor location.

[0035] In certain embodiments, the amplitude and phase of the detected RF harmonic components can be quickly determined by circuitry in a signal analysis compartment, which can be a separate metal box or chassis, or can be within or connected to or part of the impedance matching network 115, 120. Such amplitude and phase can be used to determine the asymmetry of the plasma by applying algorithms and plasma non-uniformity calibration. The signals from the sensors can be Fourier analyzed by dedicated circuitry that is fast enough to perform nearly continuous spectral analysis, updating as frequently as possible and producing a high-speed data stream. For example, at 13.56 MHz, when each element of the pulse occurs at 5 KHz, 512 time periods may take 35 microseconds to be processed by Fourier analysis, allowing updates at a rate of 10 KHz.

[0036] The results of the dedicated Fourier analysis of the fundamental and harmonics may be stored on a separate storage medium that may be read and / or written by an analysis processor associated with the signal analysis compartment. The stored results or real-time signals may be routed to a high-speed computing processor to determine asymmetry parameters for each of the fundamental and harmonics. The asymmetry parameters may be compared to values ​​previously stored on a separate storage medium (or on a different storage medium) using an algorithm (also stored on a separate storage medium or on a different storage medium) to quickly identify a "plasma fault" condition. The analysis processor may then transmit appropriate commands to the first and second RF generators 105, 110, and in some embodiments more than just two RF generators, for example, to continue processing under current conditions, or to make necessary changes to processing conditions. In some embodiments, three, four, or more RF generators may be used. The first and second RF generators 105, 110 may then continue, stop, change the power provided, change the frequency by adding or subtracting approximately ten percent of the RF power to modify the reflected power, or respond in some other suitable manner - for example, entering a reduced power mode or a pulse mode, or commanding some corrective action, such as alarm triggering, power interruption, etc., to avoid improper wafer processing in the event of a plasma failure or other unacceptable condition.

[0037] The location of the sensor for detecting and characterizing the surface waves can be on the peripheral surface (exposed or covered by a dielectric) of the pedestal 135 outside the area covered by the wafer. For example, if the reaction chamber 140 is to process a circular wafer with a radius of 150 mm, the sensor mounted on the pedestal can be located at a radius greater than 150 mm from the center of the wafer. The sensor can be additionally or alternatively located on the surface or periphery of the showerhead 130 facing the wafer, or on the base of the pedestal 135 or the surface of the base of the showerhead 130, whether these locations are inside or outside the evacuated processing environment. The sensor can also be located in various other locations, which will be discussed in detail below.

[0038] Using sensors outside the evacuated processing environment, such as in a band or bus connecting the base to one or more of the impedance matching networks 115, 120, the base of the pedestal 135, and / or the showerhead 130, may not require the need to pass signals through vacuum feedthroughs or install transmission cables within the evacuated volume of the reaction chamber 140. Therefore, sensors in such locations can monitor fundamental and harmonic EM waves almost continuously. This can enable the RF plasma processing system 100 to closely monitor the uniformity of the plasma density and determine in a very short time whether a fault condition has occurred or whether to continue with proper wafer or substrate processing.

[0039] In certain example embodiments, the present disclosure may provide an apparatus and method for detecting a deviation of a plasma within an RF plasma processing system 100 from a desired "processing window". The RF plasma processing system 100 may include a reaction chamber 140, which may include a showerhead 130 for injecting a reactive gas into the reaction chamber 140 and may also include a wafer support pedestal 135. However, in other embodiments, the showerhead 130 may not inject a gas into the reaction chamber 140. In some embodiments, the showerhead 130 may be mounted with its center proximate an approximate axis of symmetry of the reaction chamber 140 and equipped with a plurality of sensors positioned at selected azimuth angles around the axis of symmetry. Additionally, or alternatively, such sensors may be positioned on a wafer-facing surface in a peripheral region of the showerhead 130 to detect and measure propagating EM surface waves as the wafer is processed.

[0040] In addition, in some embodiments, there may be multiple sensors mounted on the outer surface of the wafer support base 135, outside the area occupied by the wafer, for detecting both the amplitude and phase of the RF harmonics and the fundamental surface wave. Such sensors may be exposed to the plasma, or may also be covered by a dielectric or a dielectric and a metal cover. In addition or alternatively, the sensor may be located on the periphery of the base of the base 135, in or outside the evacuated volume and / or below the plane defined by the wafer. In some embodiments, the sensor may be positioned on the base of the base to detect surface electromagnetic waves propagating toward or away from the wafer support area of ​​the base and on the surface of the base of the base. In some embodiments, the sensor may be mounted close to the wafer plane (e.g., less than 10 cm).

[0041] Alternatively, the sensor can be mounted on a portion of the pedestal 135 that is metal or other conductive material and is located outside the evacuated region of the reaction chamber 140 under atmospheric conditions. The sensor located outside the evacuated region can be mounted on an area of ​​the pedestal 135 that has a diameter of at least 50% of the maximum pedestal 135 diameter, or even more than 75% of the maximum pedestal 135 diameter. Such a sensor can be positioned within a few centimeters of a vacuum seal, such as an O-ring, that supports the pedestal 135. In some embodiments, the sum of the radial and axial propagation distances from the wafer edge to the sensor can be less than about 25 cm, or less than about 15 cm, or even about 10 cm. The specific location and orientation of the sensor according to embodiments of the present disclosure will be discussed in detail below.

[0042] Steering Figure 2 , shows a schematic side view of a plasma chamber with high impedance sensors mounted at various locations on the electrode according to an embodiment of the present disclosure. As each of the two components of the electrode, i.e., the base 235 and the showerhead 230 or equivalent other power supply element, a separate RF generator 205 or 210 and an impedance matching network 215 and 220 are used. Arrows 245 along the surface of the base 235 indicate the radial direction and location of the RF current and power flowing inward from the bottom (bias) RF generator 210, which is electrically connected to the base 235 through the impedance matching network 220. The generated electric field helps to form a plasma (not shown) between the electrodes and the radially outward counterflow of current and power indicated by arrows 250, which flows along the lower surface of the showerhead 235 or another power supply element and ultimately to the selective grounding circuit in the impedance matching network 215 of the showerhead 230 or another power supply element.

[0043] In some embodiments, the reaction chamber 240 having RF power from the first and second RF generators 205, 210 and the impedance matching networks 215, 220 may include a sensor 255 on the periphery of the base 235, which may be covered by a dielectric 260. A communication line 265 may transmit a signal from the sensor 255 to a Fourier analysis circuit (not shown) that calculates the amplitude and phase of both the fundamental frequency and the harmonic frequency surface waves picked up by the sensor 255.

[0044] In some embodiments, the Fourier analysis circuit can calculate the magnitude and phase of the fundamental and higher-order harmonics of the periodic surface waveform. The resulting series, called the Fourier series, establishes the relationship between the function in the time domain and the function in the frequency domain.

[0045] In addition, some embodiments of the disclosed matching network 220 may include a signal analysis compartment 275 or an appendage of the matching network 220 that is RF-isolated from the RF power handling and impedance matching circuitry or components of the matching network 220. The signal analysis compartment 275 may include (one or more) Fourier analysis circuits for analyzing the sensor signal and generating digital amplitudes and phases of the RF fundamental and harmonics. The signal analysis compartment 275 may also include a high-speed digital logic or computational processor for analyzing the relative magnitude and phase of the signal at the harmonic frequencies and deriving quantitative parameters characterizing the relative magnitudes of the axisymmetric and non-axisymmetric harmonic components and their relative phases. In addition, in some embodiments, the disclosed matching network 220 may be connected to the second RF generator 210 and the controller (not shown) of the reaction chamber 240 or RF plasma processing system 200 where the sensor 255 is located via a very fast network. In some embodiments, the disclosed enhanced impedance matching network 220 may be capable of sending commands to the first RF generator 205 and communicating its calculated parameters to the process chamber controller and / or tool control system.

[0046] In addition, another first RF generator 205 and an impedance matching network 215 may also be electrically coupled to another electrode, which may be a showerhead 230 in the reaction chamber 240. In one embodiment, the first RF generator 205 may operate at a different frequency than the second RF generator 210, and its frequency may not be an integer multiple of the frequency of the second RF generator 210.

[0047] Similarly, the impedance matching network 215 monitors the reflected power from the electrode and the processing chamber 240, and can make adjustments if there is significant reflected power from the electrode. In some embodiments, the second RF generator 210 can be a 400KHz RF generator, a 2MHz RF generator, or a 13.56MHz RF generator, or other, and the first RF generator 205 can operate at a slightly higher frequency. In some embodiments, the first RF generator 205 can operate at a frequency greater than 25MHz, such as at 60MHz, 100MHz, or higher.

[0048] In one embodiment, the primary function of the first RF generator 205 may be to power the reaction chamber 240 to generate a plasma between the showerhead 230 or another power source such as an electrode and the pedestal 235 to both generate reactive chemicals such as fluorine, chlorine, or a combination thereof, and to accelerate ions from the generated plasma and impact a wafer disposed on the pedestal 235.

[0049] A set of sensors 280 deployed on the upper electrode surface, i.e., showerhead 230, facing the lower electrode, i.e., pedestal 235, may have an impedance greater than about 100 ohms, and in some embodiments greater than 500 ohms. Sensors 280 may be voltage or current sensors, or may combine both capabilities in a single package—for example, where a current sensor may include one or more lengths of wire that may be covered by an electrostatic shield.

[0050] In some embodiments, the sensors 280 have electrical connections to the Fourier analysis circuit in the signal analysis compartment 285 of the impedance matching network 215. The Fourier analysis circuit can output the amplitude and phase of the different frequency components from each sensor 280 and compare them with other sensors 280 and / or with reference levels stored in memory. In some embodiments, the analysis of the signal can include pattern recognition of amplitude or phase or both or employ artificial intelligence (AI) that can use a learning algorithm of a neural network or traditional digital algorithm processing of the signal from the sensor 280.

[0051] The signal processing of the Fourier analysis circuit to find the fundamental and harmonic component signals, including both amplitude and phase, can be completed in less than about 10 microseconds, and in a preferred embodiment, can be completed in 1 microsecond or less for each sensor signal. The isolated signal analysis compartment 285 of the impedance matching network 215 can contain at least one computing or logic processor with a large amount of computing power, with very high speed (<1ns cycle time) circuits using very high speed logic ICs. In some embodiments, the processor in the signal analysis compartment 285 is programmable so that the supplier or user of the processing chamber 240 can provide or implement proprietary algorithms or analysis software on the computing "platform" provided in the impedance matching network 215.

[0052] In some embodiments, a software program for calculating parameters from signal amplitude and phase and further logic algorithms for determining the effect of deviations from acceptable plasma conditions on wafer yield may reside on a removable "plug-in" component that contains data storage and is connected to the signal processing compartment. The software or logic calculates the extent to which the RF surface wave spectrum has deviated from nominal or appropriate operating conditions. Based on this, a processor associated with the controller can "decide" corrective action or terminate processing within approximately milliseconds before the wafer is processed incorrectly. In some embodiments, the expected effect of the deviation can be quantitatively determined within approximately 100 microseconds after occurrence so that remedial action can be initiated within milliseconds. In addition, such actions can be taken so that there is minimal or no damage to the wafer or substrate being processed in the reaction chamber 240 at this time, thereby avoiding yield loss of the wafer or substrate.

[0053] The evaluation and / or decision made in the signal analysis compartment 285 of the impedance matching network 215 can be performed by a very fast computing or analysis system using an algorithm resident on a plug-in storage unit and / or a removable data processing device in some embodiments. In still other embodiments, the evaluation decision made in the signal analysis compartment 285 can be performed using an analog or neural network type processor. Such a decision can further use a decision algorithm, which can reside on a removable storage unit or processing device. Then, the command for corrective action can be quickly transmitted from the compartment 275 of the impedance matching network 215 to the RF generator 205 via a high-speed data line, and the RF generator 205 can temporarily interrupt, change, or terminate the power or RF frequency to the plasma. This ensures that the factory management can take or plan corrective actions on the processing chamber 240 and the RF plasma processing system 200 in a timely manner.

[0054] Figure 2Also shown is a set of sensors 290, which are arranged on the outer surface of the base 295 of the showerhead 230, whose surface is located outside the reaction chamber 240 under atmospheric conditions. In some embodiments, additional sensors 296 can be mounted on the base 297 and connected to the signal processing compartment 275 of the disclosed impedance matching network 220 through high-speed signal cables, just like the sensors 290. The sensors 296 are located outside the vacuum environment of the reaction chamber 240, which greatly reduces the cost and is easier to integrate into the information and processing network because vacuum feeding is not required.

[0055] Sensors 255 are deployed to sense voltage and / or current on the surface of pedestal 235 and may be covered and protected from the plasma by dielectric cover 260. Sensors of this type and location are close to the wafer and / or substrate and therefore may have a sensitivity advantage in detecting certain EM surface wave modes indicative of plasma asymmetry—an important type of plasma non-uniformity. These in-chamber sensors 255 may use a communication link through the vacuum wall via a feedthrough or a wireless communication link operating optically or at a lower frequency.

[0056] In general, the phase and amplitude patterns of each frequency of the EM surface waves on the surfaces of the showerhead 230 and the pedestal 235 can be determined by analyzing the signals from any group of the voltage, current, phase or combination sensors 255, 280, 290 and 296. In general, the EM surface waves at a given frequency produce voltage, current and phase signals. The amplitude and phase of these signals are the sum of the waves of that frequency from all points on the electrode-plasma interface. For an axisymmetric electrode surface, the power is fed symmetrically and the plasma is axisymmetric, and the axisymmetric surface wave mode will be generated by the superposition of waves from all parts of the electrode and other surfaces in the reaction chamber 240. In general, a completely symmetrical plasma in a symmetrical chamber with a symmetrical electrode centered on the symmetry axis of the chamber will have mainly circular symmetry lines of equal phase and amplitude centered on the center of the pedestal 235.

[0057] Steering Figure 3, shows a cross-sectional view of a dual-plate electrode assembly according to an embodiment of the present disclosure, the dual-plate electrode assembly having a sensor that provides a voltage signal through an electrical connector with low shunt capacitance. In some embodiments, an electrode such as a showerhead 330 may include two conductive plates 331, 332 that are configured to be approximately parallel, center-aligned, and have a shape that is approximately the same as a substrate or wafer. The surface of the first plate 331 away from the second plate 332 can be exposed to a vacuum environment and a plasma. The first plate 331 is separated from the second plate 332 by a distance that is the length of the dielectric support 333. The first plate 331 may have an embedded sensor 334, the puck or tip of which is a conductive material and the surface of the sensor 334 is approximately coplanar with the surface of the first plate 331 away from the second plate 332.

[0058] In some embodiments, the sensors 334 may be mounted into the first plate 331, surrounded by a dielectric 336 having a low dielectric constant, such as quartz or some other suitable material. In some embodiments, the dielectric constant of the dielectric 336 may be less than 5, and in some embodiments, for inorganic materials, such as quartz-based aerogels, the dielectric constant may be less than 2. The sensors 334 may have a high bandwidth extending from 100 kHz to around 300 MHz, and may be able to sense surface voltage, surface current, or both. The sensitivity of the sensors 334 may vary by less than 30% over the harmonic frequency range of the primary fundamental RF frequency used in the reaction chamber. At least one lead 337 is connected from each sensor 334 to an inner conductor 338 of a vacuum electrical signal feedthrough 339, the base 341 of which is mounted in the electrically grounded second plate 215.

[0059] The inner conductor 338 of the feedthrough 339 can have a small shunt capacitance to the base 341 of the feedthrough 339 mounted in the grounded second plate 332 - for example, less than 5 picofarads (pf, and in some embodiments less than 2pf) so that the total shunt capacitance from the sensor 334 plus the leads 337 plus the feedthrough 339 to ground should be less than 5pf. In some embodiments, the output from the base 341 of the second plate 332 mounted to ground can be connected to an attenuator (not shown). In some embodiments, the attenuator can include a resistor having a resistance greater than about 100 ohms. There can be a grounded shunt resistor in series with the resistor. The resistance of the shunt resistor can be, for example, 50 ohms, or alternatively can be equal to the impedance of the cable connecting the attenuator to a communication network or a controller of the plasma chamber.

[0060] Each sensor 334 can measure the voltage or current amplitude of the combined electromagnetic surface wave mode of all RF generators providing power to the plasma at a fundamental and harmonic frequency range. The fundamental and harmonic frequencies can range from about 100 kHz to about 500 MHz.

[0061] Figure 4 4 is a cross-sectional view showing a base with an embedded high impedance voltage sensor according to an embodiment of the present disclosure. The voltage sensor 401 can be mounted into an electrode, such as a base 400. In some embodiments, the sensor 401 can be connected to an electrical ground 406. The tip or locator of the sensor 401 can have a lead 402 surrounded by a dielectric 403 (which can be optionally air or vacuum). In some embodiments, the lead 402 from the sensor 401 can pass through an attenuator, such as (one or more) resistors 404 and a shunt resistor 405, which can be about 50 ohms and can be connected to an electrical ground 406. Such resistors 404, 405 can be non-inductive and can have a resistance in a range between about 100 ohms and about 100,000 ohms. In some embodiments, the resistance can be between about 500 ohms and about 10,000 ohms.

[0062] In addition, the dielectric 403 should be generally non-magnetic and have a low loss tangent, less than about 0.01 in some embodiments or less than about 0.001 in other embodiments. The shunt capacitance between the tip of the sensor 401 and the lead 402 to the ground electrode should be less than about 5 pf, or less than about 2 pf in some embodiments, so that the reactance between the sensor 401 and the base 400 electrode should be greater than about 100 ohms at 300 MHz. The purpose of such a low shunt capacitance is to reduce the loading of the sensor 401 on the surface wave, so that it absorbs the energy of the wave to a minimum and allows the wave to propagate as it would without the sensor 401. Under such conditions, the detected surface potential will not be significantly different from the surface potential on the electrode without such a sensor 401.

[0063] Steering Figure 5 , shows a schematic side view of a pedestal according to an embodiment of the present disclosure. The pedestal 501 power feed circuit includes an RF power generator 405 and an impedance matching network 506. High-speed signal lines, such as cables 511, 512, carry signals from sensors 502, 503 to the impedance matching network 506. High-speed lines 513 of a data network carry information from the impedance matching network 506 to a controller (or controllers) 514 of a reaction chamber, or a generator, or a tool or a factory (not shown). Sensors 502, 503 are mounted on or near a base 504 of the pedestal 501, and the sensors may be inside or outside the vacuum region of the reaction chamber.

[0064] In some embodiments, there may be a signal analysis, e.g., fault detection compartment 510 associated with the impedance matching network 506. The signal analysis compartment 510 may be electrically and / or RF isolated from certain components of the impedance matching network 506, such as vacuum capacitors and high voltage electronics. The signal analysis compartment 510 receives signals from the sensors 502, 503 via cables 511, 12. The signal analysis compartment 510 then passes the signal from each sensor 502, 503 to an internal circuit, which may be referred to as a detector and may include electronic components, such as transistors, and passive components.

[0065] Each detector (not shown) in compartment 510 can perform RF spectrum analysis on the signal from one sensor 502, 503 or from a group of sensors that can be analyzed in parallel. The analysis may include averaging the signals of a group of sensors or one or more sensors 502, 503 over a period of time to reduce noise. In some embodiments, for each frequency component of the signal obtained by each sensor 502, 503, such as the fundamental and harmonics, there may be an output of the amplitude and phase from each detector. The output from each detector for each harmonic signal can then be input to an analog-to-digital converter to produce a digitized value of both the amplitude and phase of each measured harmonic.

[0066] These digital amplitude and phase values ​​for each frequency component and each sensor can be input into a high-speed digital processor in a signal analysis compartment associated with the disclosed impedance matching network with almost no delay, for example <10 microseconds. The digital processor can analyze both the amplitude and phase information of the fundamental and each harmonic obtained from the sensor, and determine the relative sizes of different surface wave modes, including axisymmetric modes and non-axisymmetric modes, for both the fundamental and harmonic frequencies obtained. There may be different non-axisymmetric modes for each frequency component, one or more of which may be an indicator of plasma inhomogeneity.

[0067] In some embodiments, such non-axisymmetric modes can be quickly identified by an algorithm resident on the plug-in. A reference database correlating the magnitude of non-axisymmetric modes to plasma non-uniformity percentages can also reside on the plug-in. The digital processor can also calculate the rate of increase of the wave modes and the acceleration of one or more wave modes to determine the likelihood of a failure in the near future. One measure of the magnitude of a non-axisymmetric mode at a given frequency can be the difference between the phases of the surface waves of the given frequency at different sensor locations that are the same radial distance from the center of the circular electrode and are symmetrically located in the axisymmetric chamber. Alternatively, a second indicator of a non-axisymmetric mode can be the difference between the amplitudes of the surface waves of the given frequency at different sensor locations that are the same radial distance from the center of the circular electrode and are symmetrically located in the axisymmetric chamber.

[0068] A matching network 506 with an isolated compartment 510 containing a multi-channel detector system (not shown) can simultaneously Fourier analyze, digitize, and record the voltage amplitude and phase of the propagating EM wave at various locations on the pedestal 501. Due to inherent noise, each determined voltage amplitude and phase can be averaged over brief time intervals as desired, and a group of sensors 502, 503 can be averaged to determine a relative magnitude or time average over a relatively large number of pulses.

[0069] A showerhead, pedestal, or other powered element such as an electrode equipped with a sensor group or array can be used as a test system to generate data to characterize and record the relationship between the pattern of EM wave modes and various non-uniformities of plasma density during RF processing. This data can be analyzed to characterize and classify the plasma behavior and put into a database that can be stored in a plug-in storage device that can be connected to a matching network compartment or other controller or monitoring system.

[0070] The relationship between the amplitude and phase pattern characteristics of the non-axisymmetric mode and the axisymmetric mode can be stored in a disclosed signal analysis compartment plug-in connected to the matching network. In embodiments where the RF plasma processing system may be used as a production tool, plasma non-uniformities can thereby be quickly detected while monitoring the operation of the chamber. For example, Figure 2 The configuration shown in Figure 4 A sensor of the disclosed type shown in FIG. 1 may be incorporated into a Figure 1 The RF plasma system shown in FIG.

[0071] To determine whether the processing plasma may have experienced a plasma fault condition, an analysis processor in a signal analysis compartment associated with the impedance matching network may calculate parameters based in part on the magnitude of the non-axisymmetric mode of each of a pre-specified set of harmonics. The processor may then, in some embodiments, compare these parameters to reference ranges in a database. Such a reference database may reside on a plug-in connected to the signal analysis compartment associated with the impedance matching network.

[0072] The database may store parameters characterizing various plasma conditions to help determine if a situation is occurring where the plasma is deviating from an acceptable "processing window". In some embodiments, the analysis may include comparing the phase of each harmonic from each sensor or group thereof at a given distance from the center of the electrode. The difference in such phase for a group of sensors about any azimuth angle may be a measure of the asymmetry of the generation and / or propagation of that harmonic mode, and therefore a measure of plasma asymmetry and non-uniformity. A quantitative measure of the asymmetry of each harmonic in a group of harmonics, i.e., a parameter, may be stored in the plug-in unit and may be transmitted to the chamber and tool controllers via a data network. In addition, trends and accelerations of the parameters may be calculated and compared to reference values ​​and standards in the database as part of the process of determining if a fault condition has occurred. In some embodiments, when such a fault condition occurs, algorithms and standards that may be stored on the plug-in may be executed in a processor residing in the compartment to determine a course of remedial or preventive action. Such action may then be rapidly transmitted to the RF generator and / or chamber and / or tool controller.

[0073] In some embodiments, all of these databases of parameters, algorithms, standards, and specifications for comparing parameters, parameter change rates, and parameter accelerations may reside on a data storage device that may be connected to an input / output port of the signal analysis compartment. The analysis of the surface wave pattern based signals from the sensors and the parameters derived therefrom are performed by the processor so quickly that any fault declaration and remedial action commands may be transmitted to the RF generator via the network and reported to the controller of the chamber or system within five milliseconds or less after occurrence. In some embodiments, a fault condition and a specified remedial action command may be transmitted to the generator within one millisecond.

[0074] In some embodiments, many types of plasma deviations from the desired plasma uniformity can be detected quickly enough so that the tool or chamber controller can take action to correct the plasma fault condition before the wafer or substrate is processed incorrectly. In some cases, the specified remedial action may be to temporarily change the RF power format, such as continuous wave (CW) or pulse, or completely shut down the power for a short period of time, or the processing of the current wafer may be stopped and the wafer discarded, or the reaction chamber may be shut down for maintenance. Therefore, adjusting the frequency within a range of approximately plus or minus ten percent of the RF power can thereby modify the reflected power.

[0075] In certain embodiments, upon detection of a plasma fault condition, a disclosed signal analysis compartment associated with the matching network can command appropriate corrective action to be performed by the RF generator. For example, the RF processing generator can initiate termination processing in response to a signal measured by a sensor on the showerhead and / or pedestal to end processing of the wafer. In a specific embodiment, the frequency can be adjusted, i.e., increased or decreased in a range of approximately one thousandth to ten percent. Alternatively, power can be interrupted by the RF plasma processing deposition system, for example, the establishment of a power pulse to stop or pulse the plasma, thereby stopping the secondary plasma. In some cases, after a very brief interruption, a specified remedial action may be provided and then processing can continue. In certain embodiments, the remedial action can be determined by, for example, machine learning and / or a programmed remedial program.

[0076] Steering Figure 6 , shows a top view of an axisymmetric surface wave propagating across a susceptor according to an embodiment of the present disclosure, wherein the plasma in the reaction chamber is axisymmetric. Figure 6 In FIG. 6 , circle 601 is a graph of constant phase and amplitude for fundamental and harmonic axisymmetric surface wave modes. The circle is concentric with the electrode. These modes are highly dominant when both the electrode and the plasma are axisymmetric and coaxial in the chamber. The propagation vector 602 of the surface wave at any frequency will be radial. The waves will propagate toward and away from the center, and as they propagate, such waves will inject power into the plasma.

[0077] Steering Figure 7 , showing a top view of transverse electromagnetic surface wave propagation across electrodes according to an embodiment of the present disclosure. Figure 7In FIG. 7 , the lines 701-704 of constant phase and equal amplitude of the non-axisymmetric modes are approximately straight and parallel, both at the fundamental frequency and its harmonics. Such surface waves can be detected by sensors deployed on the pedestal or showerhead of the RF plasma deposition system. Such modes can be called "transverse", which means that the propagation direction, as seen by the propagation vectors 705-707, spans the electrode surface from one side to the other or from the central plane to the left and right sides. There may be other non-axisymmetric modes, where the lines of constant phase may be curved, with the center of curvature displaced from the center of the electrode. The detector readings for each frequency can be decomposed into the sum of the axisymmetric modes and (usually a small number of) non-axisymmetric modes, which reflect the main inhomogeneities of the plasma. Typically, this decomposition allows the identification of transverse mode components and a major "off-center" or displaced radial mode, each of which is characteristic of the plasma inhomogeneity configuration. The association of the plasma inhomogeneity configuration with a particular non-axisymmetric mode is done prior to production processing as part of building a database, which can reside on the plug-in unit or elsewhere.

[0078] Steering Figure 8 , shows a top view of an exemplary azimuthal sensor deployment of a reaction chamber according to an embodiment of the present disclosure. In this embodiment, multiple sensors 800 can be deployed azimuthally around one or more components of the reaction chamber and / or on the reaction chamber itself. As briefly discussed above, multiple sensors 800, which can be four in this embodiment, can be positioned at different angles about the chamber symmetry axis 805 on certain chamber components, such as showerheads and / or pedestals, for measuring surface voltages or currents associated with surface waves.

[0079] The sensors 800 may include passive sensors 800 that pick up changing electric or magnetic potentials. The sensors 800 may be deployed at different azimuth angles for detecting signals from different directions of the chamber symmetry axis 805. The sensors 800 may be deployed at equidistant locations around the chamber symmetry axis 805 and / or components within the reaction chamber or the reaction chamber itself. Similarly, the sensors 800 may be deployed diametrically relative to each other so that the spacing between the sensors 800 may be consistent. For example, the distance between sensors 800-1 is the same as 800-2, the same as 800-3, and the same as 800-4. Similarly, each sensor 800 is located at the same distance from the chamber symmetry axis 805. Examples of spacing and positions of sensors 800 will be discussed in more detail below.

[0080] As shown, sensors 800 are deployed at diametrically opposed locations. For example, sensor 800-1 is diametrically opposed to sensor 800-3, and sensor 800-2 is diametrically opposed to sensor 800-4. Thus, sensor 800 can look for waveform differences on different sides of a reaction chamber and / or its components, and provide notification when waveform differences occur, as explained above, so that remedial or proactive actions can be taken. For example, if sensor 800-1 and sensor 800-4 sense and report differences in waveforms from their diametrically opposed locations, such differences can provide an indication that the harmonics are out of phase, which can therefore indicate the presence of plasma non-uniformity and asymmetry.

[0081] In some embodiments, four sensors 800 may be used, such as Figure 8 . However, in other embodiments, a different number of sensors 800 may be used, such as six, eight, twelve, fourteen, sixteen, eighteen, twenty or more sensors 800. In some embodiments, it may be beneficial to have six to twelve sensors 800. The greater the number of sensors 800, the more data that can be collected, thereby providing enhanced identification of non-uniformity instances. However, by increasing the number of sensors 800, data processing may be slowed down, resulting in slower remedial and preventive actions. Those of ordinary skill in the art will understand that balancing the number of sensors 800 with the desired level of data granularity may allow RF plasma processing to be optimized. Therefore, with the increase in computing power and the increase in the speed at which data can be processed, it may be beneficial to increase the number of sensors 800. In some embodiments, specific sensors 800 may be selectively turned off and on, thereby allowing the controller to access certain desired data. For example, in a system with eight sensors, four of the sensors may be selected and turned off, thereby reducing the amount of data generated. In other embodiments, additional sensors may be added or removed from the operation, thereby changing the amount of data generated.

[0082] Additionally, a plurality of sensors include a wire having a length of conductive material parallel to a direction radially away from the chamber symmetry axis 805 and axially parallel to the chamber symmetry axis 805, wherein one end of the wire is connected to a local electrical ground.

[0083] The sensor 800 may also include various types of sensors, including circular and other geometric shapes. To improve functionality, the outer edge of the sensor 800 may be substantially smooth or radial, thereby improving the ability to detect RF current with greater accuracy. The sensor 800 may include varying thicknesses, however, the sensor 800 may be thick enough not to cause thermal stability issues, while being thin enough not to reflect power. In certain embodiments, the sensor 800 may be circular with an area of ​​approximately 1 cm. The sensor 800 may further include an insulating layer to protect the sensor 800 from the plasma in the reaction chamber, and may also include other optional coatings and layers, such as a Faraday shield, an aluminum coating, and the like.

[0084] Steering Fig. 9 , shows a side cross-sectional view of an azimuthally mounted sensor on a reaction chamber according to an embodiment of the present disclosure. In this embodiment, the reaction chamber 940 has an axis of symmetry 905 that extends longitudinally from the center of the showerhead 930 through the base 935. In other embodiments, the axis of symmetry 05 can extend longitudinally from the center of another electrode such as an antenna. Multiple sensors 900 can be deployed in azimuth at various locations around and within the reaction chamber 940 and around or associated with specific components such as the showerhead 930 and / or the base 935. Due to Fig. 9 is a cross-section, illustrating only two sensors 900 at each location, however, four or more sensors 900 may be used during implementation of the RF plasma monitoring process, as described with respect to Figure 8 Discussed in detail.

[0085] In certain embodiments, the sensor 900-1 may be deployed around the edge or periphery of the showerhead 930. In such an embodiment, the sensor 900-1 may be deployed at least partially or completely embedded within the showerhead 900-1, and the outer surface of the sensor 900-1 may be coated with an insulating layer to protect the sensor 900-1 from the environment within the reaction chamber 940. In such an embodiment, four or more sensors 900-1 may be deployed in azimuth around the edge of the showerhead 930, thereby allowing detection of non-uniformity and asymmetry in RF plasma processing.

[0086] In other embodiments, sensor 900-2 may be deployed along the edge of pedestal 935 within the vacuum of reaction chamber 940. As explained above with respect to sensor 900-1, sensor 900-2 may be partially or completely embedded in pedestal 935 and may or may not include an insulating layer deployed on its outer surface. In addition to sensor 900-2 deployed around pedestal 935 within the vacuum, other sensors 900-3 and 900-4 may be deployed outside the vacuum of reaction chamber 940 and around pedestal 935. Such sensors 900-3 and 900-4 may be deployed along pedestal 935 and / or its base portion on a metal surface. Sensor 900 may also be deployed on other support structures of pedestal 935 or associated with pedestal 935.

[0087] In other embodiments, sensor 900-5 may be disposed and / or otherwise built into a sidewall of reaction chamber 940. In such embodiments, sensor 900-5 may be disposed outside reaction chamber 940 on outer chamber wall 915, or may be built into the sidewall so that sensor 900-5 is within the vacuum of reaction chamber 940. Other sensors 900-6 may be disposed in viewing ports 920 that are disposed along outer chamber wall 915. In such embodiments, sensor 900-6 in the viewing port may be located outside the vacuum of reaction chamber 940 or within reaction chamber 940.

[0088] In yet other embodiments, the sensor 900-7 may be disposed in a dielectric located, for example, around the showerhead 930, while in other embodiments, the sensor 900-7 may be disposed in a dielectric located around the pedestal 935. Although specific locations of the sensor 900 are discussed herein, the sensor 900 may be located at various other locations in and around the reaction chamber 940. For example, the sensor 900 may be disposed around an antenna or other component. The sensor 900 may further be located at various other locations inside or outside the reaction chamber 940, as long as the sensor 900 can detect differences in waveforms during RF plasma processing.

[0089] In certain embodiments, in order to more accurately monitor the RF plasma process, a combination of sensors 900-1-900-7 may be used. For example, a sensor 900-1 around the edge of the showerhead 930 may be combined with a sensor 900-2 around the edge of the pedestal 935. Similarly, a combination of sensors 900-5 outside the reaction chamber 940 may be combined with sensors 900-1 / 900-2 located within the reaction chamber 940. In still other embodiments, combinations of three, four, five, six, seven, or more variations of sensor 900 locations may be used to further optimize the monitoring of the RF plasma process.

[0090] Steering Fig.10 , shows a side schematic cross-sectional view of a reaction chamber according to an embodiment of the present disclosure. In this embodiment, a plurality of azimuthally deployed sensors 1000 are located around a bottom electrode, which in this example is a base 1035. Fig. 9 The sensor 1000 discussed is similar, Fig.10 Sensors 1000 are illustrated deployed in various locations. Sensor 1000-1 is deployed around the outer edge of base 1035. Sensor 1000-2 is deployed around the interior of reaction chamber 1040, while sensor 1000-3 is deployed around the periphery of reaction chamber 1040.

[0091] In this embodiment, 12 sensors 1000 are shown at each location, however, in other embodiments, other numbers of sensors 1000, including fewer and more, may be used. In addition, in addition to the sensor 1000 locations explicitly shown, other sensor 1000 locations may be used to further enhance RF plasma processing.

[0092] Steering Fig.11 , shows a side schematic cross-sectional view of a reaction chamber according to an embodiment of the present disclosure. In this embodiment, the sensor 1100 is illustrated as being deployed around the inductively coupled plasma source 1105. Thus, the sensor 1100 can sense the RF current from the plasma source located within the reaction chamber 1140.

[0093] Steering Fig.12 , shows a partial cross-sectional view of an RF plasma processing system according to an embodiment of the present disclosure. In this embodiment, the RF plasma processing system 1200 includes a pedestal 1235. The pedestal 1235 includes a sensor 1240 deployed along an upper outer edge of the pedestal 1235. As described above, the sensor 1240 can be deployed on the upper outer edge, embedded in the pedestal 1235, or can be alternately deployed around the outer edge of the reaction chamber inside or outside the vacuum.

[0094] The RF plasma processing system 1200 also includes circuitry 1245 connected to the sensor 1240 via a communication line 1250. When the sensor 1240 receives sensed data from the RF plasma processing system 1200, the data can be sent to the circuitry 1245 for processing. Because the circuitry 1245 is relatively close to the sensor 1240, the time spent transferring the sensed data between the two can be reduced. Therefore, the initial calculation of the electrical property sensed by the sensor 1240 can be performed more quickly and then transferred to other components 1255 of the RF plasma processing system 1200. The other components 1255 can include, for example, an RF generator, an impedance matching network, a fault detection compartment, an operating controller of a reaction chamber, an operating controller of a tool, a plug-in device, a signal analysis compartment, or (one or more) other components connected to the RF plasma processing system 1200.

[0095] Other components 1200 can then adjust various aspects of the RF plasma processing system 1200 to correct the fault detected by sensor 1240 and at least partially handled within circuit system 1245. Circuit system 1245 can be located within pedestal 1235 outside the vacuum of the reaction chamber in an isolated structure to protect circuit system 1245 from conditions within the reaction chamber. In other embodiments, circuit system 1245 can be located in the base of pedestal 1235, or in other areas near pedestal 1235.

[0096] along with Fig.12 A cross-sectional view of an RF plasma processing system 1200 is illustrated, and one of ordinary skill in the art will appreciate that the circuitry 1245 can be radially deployed around the pedestal 1235. Thus, a separate circuitry 1245 can be used for each sensor 1240, or the sensors 1240 can be connected to a centralized circuitry 1245 located in one or more selected locations around and / or within the pedestal 1235.

[0097] Turn together Fig.13 , Fig.14 and Fig.15 , respectively, show a top view of an RF plasma processing system according to an embodiment of the present disclosure, a partial cross-sectional view of a resonator in the plasma processing system, and a second cross-sectional view of a resonator in the plasma processing system. In this embodiment, the plasma processing system 1300 includes an impedance matching network 1305, which is operatively connected to the reaction chamber 1310. The impedance matching network 1305 can include any of the example impedance matching networks 1305 described above. The plasma processing system 1300 also includes a plurality of resonators 1315 disposed around the reaction chamber 1310.

[0098] Fig.14The diagram shows resonators 1315 configured to operate in parallel. Fig.15 Resonators configured to operate in series are illustrated. Resonator 1315 may include capacitor 1320 and coil 1325, and may be used to isolate one or more sector plates 1330 associated therewith. Thus, when RF power is supplied to reaction chamber 1310, the power relative to a single sector plate 1330 may be modified, thereby allowing more or less power to be supplied to specific areas within reaction chamber 1310. Sector plates 1330 may be deployed azimuthally around pedestals 1335 and located in a ring between pedestals 1335 within reaction chamber 1310. By adjusting the power supplied to various areas of sector plates 1330, the plasma uniformity within reaction chamber 1310 may be varied. As shown in FIG. Fig.14 As shown in , the parallel resonator 1315 can result in less power consumption, thereby increasing the RF voltage. Fig.15 As shown in , the serial resonator 1315 can increase power consumption, thereby reducing the RF voltage.

[0099] During operation, when the electrical property exceeds a predefined limit, which may be defined by a reference value set, a fault signal may be sent to the impedance matching network 1305 or other plasma power supply to adjust the plasma parameters. Examples of electrical properties may include electromagnetic surface wave signals and / or other properties discussed above. In some embodiments, the electrical property may include the amplitude and phase of the RF fundamental and harmonics at each of several sensor locations (not shown), which are described in detail above.

[0100] In certain embodiments, the fault detector 1340 can be physically or operationally connected to the impedance matching network 1305. The fault detector 1340 can receive the electrical properties identified above and, for example, can compare the amplitude and phase of the RF fundamental and harmonics relative to the chamber symmetry axis to determine the non-axisymmetric phase and amplitude pattern. The fault detector 1340 can include a removable memory (not shown) that includes a database of information related to the operation of the plasma processing system 1300, such as, but not limited to, electrical properties, reference value sets, plasma parameters, etc.

[0101] In certain embodiments, when a defined electrical property is detected, the fault detector 1340 can be used to implement a remediation protocol based on one or more remediation parameters. Examples of remediation parameters include, for example and without limitation, shutting down a plasma power supply, adjusting properties of the impedance matching network 1305, adjusting power and / or frequency variables provided to the reaction chamber 1310, and the like.

[0102] Steering Fig.16, shows a partial top view of a plasma processing system according to an embodiment of the present disclosure. In this embodiment, plasma processing system 1600 includes a matching network 1605 operatively connected to reaction chamber 1610. Matching network 1605 can be connected to coil 1615. Coil 1615 can be used to increase power by induction within reaction chamber 1610. By providing power by induction, power can be increased without consuming RF power.

[0103] In operation, the method of the present disclosure can allow for providing uniformity control in an RF plasma processing system. The method can include, for example, detecting electromagnetic surface wave signals from an RF plasma in a reaction chamber with a plurality of sensors. The sensors can include any of the exemplary sensors described above. The method can further include determining the amplitude and phase of the RF fundamental and harmonics at each sensor location, and comparing the amplitude and phase of the RF fundamental harmonics at a specified distance from the reaction chamber axis of symmetry.

[0104] The method may also include extracting the non-axisymmetric phase and amplitude pattern and comparing the magnitude of the non-axisymmetric phase and amplitude pattern to a reference value set. Based on the comparison, when the non-axisymmetric phase and amplitude pattern exceeds a predefined range, a command may be sent to a plasma power supply, a matching network, etc. to adjust an operating parameter. In certain embodiments, machine learning, neural networks, etc. may be used to determine and / or define the predefined range. When the non-axisymmetric phase and amplitude pattern does not exceed a predefined limit, the method may include continuing to detect, determine, compare, extract, and compare.

[0105] In still other embodiments, a method for providing uniformity control in an RF plasma processing system may include detecting electrical properties of an RF frequency plasma using one or more sensors azimuthally deployed around an axis of symmetry of a reaction chamber. The method may further include determining the presence of plasma non-uniformity based on the detected electrical properties, and adjusting operating parameters of a plasma power supply, a matching network, etc. based on the determined plasma non-uniformity.

[0106] The foregoing description, for the purpose of explanation, uses specific terms to provide a thorough understanding of the present disclosure. However, it is clear to those skilled in the art that the specific details of the systems and methods described herein are not required to practice. The above descriptions of specific examples are for the purpose of illustration and description. They are not intended to be exhaustive or limit the present disclosure to the precise form described. Obviously, in view of the above teachings, many modifications and variations are possible. These examples are shown and described in order to best explain the principles and practical applications of the present disclosure, so that other technicians in the field can best utilize the present disclosure and various examples, and make various modifications thereto to suit the specific purposes contemplated. The scope of the present disclosure is defined by the appended claims and their equivalents.

Claims

1. A radio frequency plasma processing system, comprising: Reaction chamber; a base, disposed in the reaction chamber; Features include: Fault detectors; and a plurality of sector plates azimuthally disposed about the pedestal in a ring between the pedestal and the reaction chamber, the sector plates being adjustably powered in operation to control plasma uniformity, in: When the electrical property does not exceed the limit defined by the reference value set, the fault detector continues to receive the electrical property from a plurality of sensors having a high bandwidth from 100 KHz to 300 MHz deployed on the RF plasma processing system and compares the electrical property with the reference value set; and The fault detector compares the amplitude and phase of the RF fundamental and harmonics relative to the reaction chamber axis of symmetry to determine a non-axisymmetric phase and amplitude pattern.

2. The system according to claim 1, wherein: When the electrical property exceeds a limit defined by the set of reference values, the fault detector coupled to the RF plasma processing system sends a signal to a plasma power supply coupled to the reaction chamber to adjust a plasma parameter.

3. The system according to claim 2, wherein: The electrical property includes an electromagnetic surface wave signal.

4. The system according to claim 2, wherein: The electrical properties include amplitude and phase of a radio frequency fundamental and harmonics at each of a plurality of sensor locations.

5. The system according to claim 1, wherein: The fault detector is connected to an impedance matching network.

6. The system according to claim 1, wherein: A reference database is stored on a detachable memory that is removably connected to the fault detector.

7. The system according to claim 1, wherein: When a remediation protocol is detected, remediation parameters are implemented, and wherein the remediation parameters include shutting down a plasma power supply.

8. The system according to claim 7, wherein: The remediation parameter includes adjusting at least one of power and frequency provided to the reaction chamber.

9. A method for providing uniformity control in a radio frequency plasma processing system, the method comprising: adjustably powering a plurality of sector plates azimuthally disposed about the susceptor in a ring between the susceptor and the reaction chamber to control plasma uniformity in the reaction chamber; Detecting electromagnetic surface wave signals from the radio frequency plasma in the reaction chamber using a plurality of sensors having a high bandwidth ranging from 100 KHz to 300 MHz; determining the amplitude and phase of the radio frequency fundamental and harmonics at each of the plurality of sensor locations; comparing the amplitude and phase of the radio frequency fundamental and harmonics at each of the plurality of sensor locations located at a specified distance from the chamber symmetry axis; extracting non-axisymmetric phase and amplitude patterns from the comparison; comparing the magnitudes of the non-axisymmetric phase and amplitude patterns to a set of reference values; as well as When the non-axisymmetric phase and amplitude pattern exceeds a predefined range, a command is sent to the plasma power supply to adjust operating parameters.

10. The method according to claim 9, wherein: When the non-axisymmetric phase and amplitude pattern does not exceed the predefined limits, the detecting, determining, comparing the amplitude and phase of the RF fundamental and harmonics, extracting and comparing the magnitude of the non-axisymmetric phase and amplitude pattern with a reference value set are continued.

11. The method according to claim 9, wherein: The operating parameter includes at least one of a power and a frequency value generated by the plasma power supply.

12. The method according to claim 9, further comprising: The plasma power supply is deactivated when the non-axisymmetric phase and amplitude pattern exceeds the predefined range.

13. The method according to claim 9, wherein: The plurality of sensors are disposed around an edge of the plasma power device.

14. The method according to claim 9, wherein: The plurality of sensors include a high impedance sensor having an impedance of 100 ohms or greater.

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