High-speed arc detection matching network

Abstract

1. A method for detecting plasma asymmetry in a radio frequency plasma processing system, the method comprising: supplying radio frequency power to reaction chambers having adjacent chamber axes of symmetry and receiving radio frequency signals from a plurality of broadband electromagnetic sensors, processing the radio frequency signals using Fourier analysis, and determining that plasma asymmetry has occurred in the reaction chambers based on the Fourier analysis of the radio frequency signals.

Description

Technical Field

[0001] Cross - References to Related Applications This application claims priority to U.S. Provisional Application No. 62 / 959,650, filed on January 10, 2020, and U.S. Non - Provisional Patent Application No. 17 / 145,228, filed on January 8, 2021, the contents of which are incorporated herein by reference.

Background Art

[0002] Radio - frequency (RF) plasma enhanced processes are widely used in semiconductor manufacturing to etch different types of films, deposit thin films at low to moderate process temperatures, and perform surface treatment and cleaning. A characteristic of such processes is the use of plasma, i.e., a partially ionized gas. It generates neutral species and ions from precursors within a reaction chamber, provides energy for ion bombardment, and / or is used to perform other actions. There are challenges in controlling the plasma density during such processes, and the non - uniformity of the plasma within the reaction chamber affects the uniformity of wafer processing and the yield of the integrated circuits or other devices being manufactured.

Summary of the Invention

[0003] Non-uniform plasma density within a reaction chamber may cause non-uniform etching rates or specific properties across the substrate. In certain systems, this is done using probes to monitor the uniformity of plasma density within the reaction chamber. Such probes may be exposed to a coating-dependent plasma environment, and active electronics may be used to infer plasma density. Such systems may take several milliseconds or more to respond to changes in plasma. Alternatively, emission spectroscopy can be used to determine the plasma density profile within the reaction chamber; however, such systems require multiple lines of sight through the plasma, and complex analysis can be used to infer non-uniformity. Neither of these methods has sufficient sensitivity and speed to effectively solve the problem of non-uniformity, and they do not incur additional costs for implementation. [Brief explanation of the drawing]

[0004] This disclosure is best understood when read in conjunction with the attached diagrams, as described below. It should be emphasized that, due to standard industry practices, various functions are not depicted in constant proportions. In fact, for the sake of clarity in the discussion, the dimensions of various functions may be arbitrarily increased or decreased.

[0005] [Figure 1] This is a schematic side view of an RF plasma processing system according to an embodiment of the present disclosure. [Figure 2] This is a schematic side view of a plasma chamber equipped with high-bandwidth sensors mounted at various positions on the electrodes, according to an embodiment of the present disclosure. [Figure 3] This is a cross-sectional view of a dual-plate electrode assembly having a sensor that provides a voltage signal via an electrical connector having a low shunt capacitance to electrical ground, according to an embodiment of the present disclosure. [Figure 4] This is a cross-sectional view of a pedestal equipped with an embedded high-bandwidth voltage sensor according to an embodiment of the present disclosure. [Figure 5] This is a schematic side view of a pedestal according to an embodiment of the present disclosure. [Figure 6] This is a top view of the propagation of an axisymmetric surface wave across a pedestal in which the plasma in the reaction chamber is axisymmetric, according to an embodiment of the present disclosure. [Figure 7] This is a top view of transverse electromagnetic surface wave propagation across an electrode according to an embodiment of the present disclosure. [Figure 8] This is a top cross-sectional view of a sensor mounted on a reaction chamber in the azimuthal direction (around the chamber's axis of symmetry) according to an embodiment of the present disclosure. [Figure 9] This is a side cross-sectional view of the electrodes, electrode base, upper dielectric plate, viewport, and sensors mounted in the azimuthal direction on the dielectric wall of the reaction chamber according to an embodiment of the present disclosure. [Figure 10] This is a side cross-sectional view of a capacitively coupled plasma reaction chamber with several sensor array positions according to an embodiment of the present disclosure. [Figure 11] This is a side cross-sectional view of a model induction plasma reaction chamber according to an embodiment of the present disclosure. [Figure 12] This is a schematic side cross-sectional view of an RF plasma processing system with several possible sensor positions according to an embodiment of the present disclosure. [Figure 13] This is a schematic partial cross-sectional view including a dielectric wall of an RF plasma processing system in which a sensor is mounted on a dielectric surface adjacent to an inductively coupled antenna, according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0006] An illustrative embodiment of the subject matter claimed below is disclosed herein. For the sake of clarity, not all functionalities of actual implementations are described in this specification. In developing such actual implementations, numerous implementation-specific decisions may be made to achieve developer-specific goals, such as compliance with system-related and business-related constraints, and these will vary from implementation to implementation. Furthermore, it should be understood that such development efforts, even if complex and time-consuming, are routine work for those skilled in the art who are interested in this disclosure.

[0007] Furthermore, where used herein, the article “a” is intended to have its usual meaning in patented technology, namely “one or more.” In this specification, the term “about” where applied to a value generally means within the permissible range of the equipment used to generate the value, or, in some examples, means a range of 10%, or a range of 5%, or a range of 1%, unless otherwise specified. Furthermore, the term “substantially” as used herein means, for example, the majority, or almost all, or all, or a quantity ranging from about 51% to about 100%. Furthermore, the examples herein are for illustrative purposes only and are presented for discussion purposes, not as limitations.

[0008] Referring to 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 plasma feeding device such as a sheath 125, a showerhead 130 or an equivalent feeding element such as an electrode, and a pedestal 135. As used herein, the plasma feeding device may refer to any device that introduces power to generate plasma and may include, for example, the showerhead 130 and / or other types of electrodes, as well as an antenna and the like.

[0009] The RF plasma processing system 100 may include one or more RF generators 105, 110 that supply power to the reaction chamber 140 via one or more impedance matching networks 115, 120. RF power flows from the first RF generator 105 through the impedance matching network 115 to the plasma in the reaction chamber 140, the showerhead 130 or sidewalls, electrodes other than the showerhead 130, or an inductive antenna (not shown) that electromagnetically supplies power to the plasma. Here, power flows from the plasma to the ground and / or pedestal 135 and / or second impedance matching network 120. Generally, the first impedance matching network 115 compensates for variations in the load impedance in the reaction chamber 140, so the combined impedance of the showerhead 130 and the first impedance matching network 115 is equal to the output impedance of the first RF generator 105, e.g., 50 ohms, by adjusting the reactive component in the first impedance matching network 115, e.g., a variable capacitor. Furthermore, adjusting the frequency within approximately 10 percent of the RF power range may correct reflected power. The term "approximately" as used herein acknowledges that some inaccuracy with respect to the range or value may be experienced in practice, and yet satisfactory results may still be obtained. Such inaccuracies may be due, for example, to loss, degradation, or drift of calibration during operation. However, in these situations, the expressed range or value is a nominal target of the operating conditions at the time of use.

[0010] In certain embodiments, the first RF generator 105 may supply power at an RF frequency between approximately 400 kHz and 150 MHz, while the second RF generator 110 connected to the pedestal 135 may supply power at an RF frequency lower than that of the first RF generator 105. However, in certain implementations, the second RF generator 110 may not supply power at an RF frequency lower than that of the first RF generator 105. Typically, the frequencies of the first and second RF generators 105, 110 are such that the first RF generator 105 is at an RF frequency that is neither an integer multiple nor an integer fraction of the frequency of the second RF generator 110. Additionally, one or more of the first and second RF generators 105, 110 may have their frequencies tuned to change the reflected power.

[0011] The impedance matching networks 115, 120 are designed to adjust their internal reactive elements so that the load impedance matches the source impedance. Generally, low reflected power is considered positive, but in embodiments of the present disclosure, the supplied power is maintained within the reaction chamber 140 and reflected toward the first and second RF generators 105, 110, and the reflected power is relatively high, and the associated impedance matching networks 115, 120 monitor the forward and reflected power to and from the reaction chamber 140, and a motor-driver system can be used to adjust the adjustable reactive elements, such as a vacuum variable capacitor. In certain embodiments, an electronically controlled capacitor, such as a pin diode for an electronically variable capacitor, can be used. The impedance matching networks 115, 120 may include circuits for measuring the phase and magnitude of the signal to determine the levels of forward and reflected power from the intended load. Thus, embodiments of the present disclosure may be effective even when the amount of reflected power is high. If there is a significant amount of reflected power at the primary frequency, the capacitor is changed to, for example, less than about 5 watts and / or less than about 1 percent over that period, or in certain embodiments, less than 1 watt, until the reflected power is minimized. Typically, harmonic frequency signals, including reflected power at harmonic frequencies, are not measured. Furthermore, the frequency may be adjusted within a range of about 10 percent of the RF power, thereby correcting the reflected power.

[0012] While the RF plasma processing system 100 offers many advantages, maintaining control of plasma density throughout the multi-stage process has historically been a challenge. For example, a design tolerance of about 1% non-uniformity across density ranges of the same order of magnitude relative to the nominal value remains a challenge. As the shape shrinks to less than approximately 3 nm and the layer thickness to less than approximately 10 nm, achieving optimal integrated circuit (IC) yield on any wafer requires strict, stepwise control of plasma and neutral species uniformity down to the 1% level or even lower. Non-uniform plasma density, or average density deviating from the desired value beyond the desired range within the reaction chamber, can be caused by slow changes in the chamber, changes in the RF circuit, or rapid growth (on the order of less than 1 millisecond) of parasitic or secondary plasma, which can lead to non-uniform nanoscale features across the processed wafer due to non-uniform etching rates.

[0013] Even a 1 percent difference in etching rate across the entire wafer can cause yield problems in advanced technologies, and since it often takes a considerable amount of time to complete wafer processing to confirm yield loss, it is necessary to quickly and accurately detect non-uniform plasma density or plasma density deviating from the desired range within the reaction chamber in a period that may need to be less than approximately 1 millisecond to avoid irreversible deviation of the wafer from the desired feature profile.

[0014] Those skilled in the art will understand that electromagnetic (EM) surface waves can propagate along the surface of the RF-driven plasma within the reaction chamber 140. These surface waves have considerable energy at both the fundamental RF driving frequency and the RF harmonics. The mean power and power distribution of the harmonics are sensitive functions of plasma density and heterogeneity. Herein, a harmonic profile is defined as the spectrum of surface waves having frequencies that are integer multiples of the fundamental driving frequency of the RF plasma-based reaction chamber 140. For example, if an RF driving power of 2 MHz is supplied to the reaction chamber 140, the injected power generates surface waves at its frequency propagating along the interface between the plasma and the surface of the internal reaction chamber 140. Tuning the frequency within a range of about 10 percent of the RF power can thereby alter the reflected power. Multiple integer harmonic surface waves may also be generated. For example, a 2 MHz electromagnetic wave may generate surface waves at 4, 6, or 8 MHz. Both odd and even harmonics (2nd, 3rd, 4th, 5th, etc.) may appear, but in some embodiments, odd harmonics may be dominant.

[0015] Aspects of the present disclosure provide sensor locations around the reaction chamber 140 and its components, thereby enabling the detection and analysis of RF surface waves to determine the amplitude and phase of fundamental and harmonic waves at multiple points within or near the reaction chamber 140. Fundamental and harmonic waves can be detected by sensing RF voltage or RF current at the fundamental and harmonic frequencies on the surface of the chamber components. In some embodiments, the voltage sensor would include a pickup configured on the surface of an electrode, pedestal base, chamber wall, or strap, and near a conductor that transmits a signal from the pickup to a connector or cable. The current sensor may include a conductive element comprising one or more loops, partial loops, or linear conductors, one end of which is at a reference potential, which may be a local electrical ground.

[0016] A plurality of sensors, e.g., two or more sensors, may be positioned at different angles around the chamber symmetry axis on specific chamber components, which are described in detail below, to measure the surface voltage or surface current associated with such surface waves. Here, the angle measured around the symmetry axis from a reference point of the chamber is defined as the azimuth angle. In some embodiments, such sensors may be positioned at approximately the same distance from the symmetry axis of the chamber.

[0017] The sensors may be attached at various locations on the reaction chamber and / or its components or its periphery. For example, the sensors may be attached to the surface of electrodes such as the pedestal 135 and / or the showerhead 130. The sensors may be attached to the base of the electrodes either inside or outside the vacuum. The sensors may be placed inside the chamber on the surface of one or more metal walls of the reaction chamber 140, and inside or outside the wall region containing the dielectric material, or attached to an antenna that can be used to inductively power the plasma. Also, the sensors may be located in proximity to the plasma boundary or placed on a plurality of conductive buses or straps that connect the first or second impedance matching networks 115, 120 to electrodes, such as the pedestal 135 and / or the showerhead 130, the antenna, or other components that transmit power to the plasma inside the reaction chamber 140, or on a passive antenna that can be used to sense the nearby EM waves. Also, the sensors may be connected to electrical ground. Thereby, the sensors can receive signals from different parts of the RF plasma processing system 100 as the signals propagate along the surfaces of the respective components.

[0018] The RF harmonic spectrum is generated at the electrode-plasma interface, for example, the sheath 125 in Figure 1. Since RF harmonics propagate in all directions, both the amplitude and phase of all wave components vary depending on their position on the electrode or support base. Furthermore, such RF harmonics propagate along the inner surface of metal walls adjacent to the plasma and through any dielectric walls that may be adjacent to the plasma. The amplitude and phase of such waves change in response to changes in the plasma, such as plasma density and heterogeneity, with response times on the order of a few microseconds or less. Moreover, the frequency and phase distribution of RF harmonic surface waves propagating at the electrode-plasma interface determines the frequency and phase distribution of RF harmonic surface waves propagating along the surface of the electrode base toward the electrode or plasma-wall interface, or the impedance matching networks 115, 120 of surfaces connected to the wall. The amplitude and phase of the fundamental and harmonic signals at different sensor positions allow us to determine which parts of the overall EM wave field are azimuthal symmetric and which are asymmetric for each frequency.

[0019] In the case of an induced plasma, signals from the plasma, such as fundamental and harmonics, may propagate to an antenna and return, and then propagate to an impedance matching network that powers the antenna. The frequency and phase distributions of both fundamental and harmonic RF waves can be monitored on a timescale of microseconds or more using sensors mounted on such a surface. They may also be compared to a specified range-phase relationship as an indicator of plasma asymmetry or changes in plasma density or electrical conductivity. Signals from such sensors may be transmitted via cable or by other means to detectors that analyze the component frequencies of the signal and generate amplitude and phase values ​​for each frequency component at each sensor location.

[0020] In a particular implementation, the amplitude and phase of the detected RF harmonic components can be quickly determined by a circuit (detector) within a separate metal box or chassis, or within a signal analysis component that is part of or connected to impedance matching networks 115, 120. Such amplitude and phase can be used to determine conditions including the radial distribution and plasma asymmetry by applying algorithms and plasma non-uniformity calibration. Signals from the sensors are Fourier analyzed by a dedicated circuit (detector) at a speed sufficient to perform a virtually continuous spectrum analysis, updated as frequently as possible, and a high-speed data stream is generated. For example, in the case of 13.56 MHz plasma power, 512 cycles may take less than 50 microseconds to process by Fourier analysis, and in the case of a pulsed plasma where each element of the pulse is generated at 5 kHz, this allows the plasma status to be updated at a rate of 10 kHz.

[0021] The results of dedicated Fourier analyses of the fundamental and harmonics may be read and / or written to a separate storage medium by an analysis processor associated with the signal analysis section. Either the stored results or the real-time signals may be sent to a high-speed computing processor to determine the respective asymmetric parameters of the fundamental and harmonics. The asymmetric parameters can be compared with values ​​previously stored in a separate storage medium (or a different storage medium) using an algorithm (which can also be stored in a separate storage medium or a different storage medium) to very quickly recognize a “plasma failure” condition. The analysis processor may then send appropriate commands to, for example, continue the process under the current conditions, or make the necessary changes to the process conditions in the first and second RF generators 105, 110, and in certain implementations, two or more RF generators, and, where appropriate, the impedance matching network associated with these generators. In certain implementations, three, four, or more RF generators may be used. The first and second RF generators 105 and 110 may then continue, stop, or change the power supplied, correct reflected power by changing the frequency by about 10 percent of the RF power, or respond in other appropriate ways, for example, by entering a low-power mode or pulse mode to avoid improper wafer processing during plasma failure or other unacceptable conditions, or by commanding specific corrective measures, such as an alarm trigger or power cut-off.

[0022] In some embodiments, the location of sensors for detecting and characterizing surface waves (their electric and magnetic fields) may be on the peripheral surface (bare or covered by a dielectric) of the pedestal 135 outside the area covered by the wafer. For example, when the reaction chamber 140 processes a circular wafer with a radius of 150 mm, the sensors mounted on the pedestal may be positioned at a radius greater than 150 mm from the wafer center, and in some cases, they may be under an annular peripheral dielectric for controlling edge effects. Sensors may also be additionally or alternatively positioned on the surface or periphery of the wafer-facing showerhead 130, or on the surface of the base of the pedestal 135 or the base of the showerhead 130, regardless of whether these locations are inside or outside the vacuum process environment. Sensors may also be positioned at various other locations, which are described in detail below, and can be continuously or periodically monitored to provide uniformity of the process plasma.

[0023] By using sensors outside the vacuum process environment, for example, in a strap or bus connecting the base to one or more of the impedance matching networks 115, 120, the base of the pedestal 135 and / or showerhead 130 may not require the transmission of signals through a vacuum feedthrough or the installation of transmission cables within the vacuum volume of the reaction chamber 140. Sensors in such locations can monitor the fundamental and harmonic EM waves substantially continuously. This allows the RF plasma processing system 100 to continuously provide uniformity of plasma density and determine, within a very short time, whether a fault condition has occurred or whether proper wafer or substrate processing can continue.

[0024] In certain exemplary implementations, the disclosure can provide apparatus and methods for detecting plasma deviation from a required “process window” within an RF plasma processing system 100. The RF plasma processing system 100 may include a reaction chamber 140. The reaction chamber 140 may include a showerhead 130 for injecting reaction gas into the reaction chamber 140, and may also include a wafer support pedestal 135. However, in other implementations, the showerhead 130 may not be able to inject gas into the reaction chamber 140. In some embodiments, the showerhead 130 may be centered near the approximate axis of symmetry of the reaction chamber 140 and may be equipped with a plurality of sensors positioned at selected azimuthal angles around the axis of symmetry. Additionally or alternatively, such sensors may be positioned on the wafer-facing surface in a peripheral area of ​​the showerhead 130 to detect and measure EM surface waves propagating while the wafer is being processed.

[0025] Furthermore, in some embodiments, there may be multiple sensors mounted on the outer surface of the wafer support pedestal 135 outside the area occupied by the wafer, in order to detect both the amplitude and phase of the RF harmonic and fundamental surface waves. Such sensors may be exposed to the plasma or covered with a dielectric or dielectric-metal cover. Additionally or alternatively, sensors may be located around the base of the pedestal 135, inside or outside the exhausted volume, and / or below a plane determined by the wafer. In some implementations, sensors may be located on the pedestal base to detect surface electromagnetic waves propagating toward the wafer support area of ​​the pedestal or on the surface of the pedestal base. In certain embodiments, sensors may be mounted close to the wafer surface (e.g., less than 10 centimeters).

[0026] Alternatively, the sensor may be made of metal or another conductive material and mounted on a portion of the pedestal 135 located outside the vacuum region of the reaction chamber 140 under atmospheric conditions. The sensor located outside the vacuum region may be mounted on the region of the pedestal 135 at a radius from the pedestal symmetry axis that is at least 50% of the maximum pedestal 135 radius, or more than 75% of the maximum pedestal 135 radius. In some embodiments, such a sensor can be positioned within a few centimeters of the supporting pedestal 135, for example, the vacuum seal for the O-ring. In some embodiments, the sum of the radial and axial propagation distances from the wafer edge to the sensor may be less than about 25 cm, or less than about 15 cm in some embodiments, or even less than about 10 cm. Specific positions and orientations of the sensor according to embodiments of this disclosure will be discussed in detail below.

[0027] Referring to Figure 2, a schematic side view of a plasma chamber with high-impedance sensors mounted at various positions on the electrodes according to an embodiment of the present disclosure is shown. Each of the two components that function as electrodes, namely the pedestal 235 and the showerhead 230, or other equivalent feeding elements, may use a separate RF generator 205 or 210 and impedance matching networks 215 and 220. Alternatively, the electrodes may have multiple generators and matching networks supplying power to them. Arrow 245 along the surface of the pedestal 235 indicates the inward radial flow of RF current and power from the bottom (bias) RF generator 210, which is electrically connected to the pedestal 235 via the impedance matching network 220. Along the underside of the showerhead 235 or other feeding element, and ultimately along the selective grounding circuit in the impedance matching network 215 for the showerhead 230 or other feeding element, the generated electric field contributes to the formation of plasma (not shown) between the electrodes and the radially outward reverse flow of current and power, indicated by arrow 250.

[0028] In certain embodiments, a reaction chamber 240 having RF power from first and second RF generators 205, 210 and impedance matching networks 215, 220 may include sensors 255 around a pedestal 235 that can be covered by a dielectric 260. A communication line 265 can transmit signals from each of the sensors 255, and in some embodiments, it may be approximately equidistant from the pedestal symmetry axis to a Fourier analysis circuit (not shown) that calculates the amplitude and phase of both the fundamental and harmonic surface waves received by each sensor 255.

[0029] In some implementations, a Fourier analysis circuit can calculate the magnitude and phase of the fundamental and higher harmonics of a periodic electromagnetic surface waveform. The resulting series of magnitudes is called a Fourier series, and their phases derive from the relationship between a function in the time domain and a function in the frequency domain.

[0030] Furthermore, some embodiments of the disclosed matching network 220 include a signal analysis section 275 or an accessory to the matching network 220, which is isolated from the RF power processing and impedance matching circuits or components of the matching network 220 and is RF isolated. The signal analysis section 275 may include a Fourier analysis circuit (detector) for analyzing the sensor signal and generating digital amplitudes and phases of the RF fundamental and harmonics. The signal analysis section 275 may also include a high-speed digital logic or computing processor for analyzing the relative magnitudes and phases of the signal at harmonic frequencies and deriving quantitative parameters characterizing the relative magnitudes and phases of the axially and non-axially symmetric harmonic components at each frequency. Furthermore, in some embodiments, the disclosed matching network 220 may be connected via a very high-speed network to a controller (not shown) of the reaction chamber 240 or RF plasma processing system 200 in which the second RF generator 210 and sensor 255 are located. In some embodiments, the disclosed extended impedance matching network 220 may be able to transmit commands to the first RF generator 205 and communicate its calculated parameters to the processing chamber controller and / or tool control system.

[0031] Furthermore, another first RF generator 205 and impedance matching network 215 may also be electrically coupled to other electrodes, which may be showerheads 230 within the reaction chamber 240. In one implementation, 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.

[0032] Similarly, the impedance matching network 215 can monitor reflected power from the electrodes and processing chamber 240 and make adjustments if there is significant reflected power from the electrodes. In some embodiments, the second RF generator 210 may be a 400 kHz RF generator, a 2 MHz RF generator, a 13.56 MHz RF generator, or something else, while the first RF generator 205 may operate at a somewhat higher frequency. In some embodiments, the first RF generator 205 can operate at a frequency greater than 25 MHz, for example, 60 MHz, 100 MHz, or higher.

[0033] In one embodiment, the primary function of the first RF generator 205 may be to power the reaction chamber 240 to generate plasma between it and another power source such as a showerhead 230 or an electrode and pedestal 235, both of which generate reactive chemical species such as fluorine, chlorine, or compositions thereof, and to accelerate ions from the generated plasma to collide with a wafer placed on the pedestal 235.

[0034] A set of sensors 280 may be positioned on the upper electrode surface, i.e., the showerhead 230, and facing the lower electrode, i.e., the pedestal 235, having a bandwidth exceeding approximately 10 times the frequency of the RF generator, which is the highest frequency connected to that electrode. In some embodiments, each of these may have an impedance exceeding approximately 100 ohms, and in some embodiments, an impedance exceeding 500 ohms. Sensors 280 may be voltage or current sensors, or both functions may be combined in a single package, for example, the current sensor may include one or more segments of wire which may be covered by an electrostatic shield.

[0035] In some embodiments, the sensor 280 has an electrical connection to a Fourier analysis circuit in a signal analysis section 285 of an impedance matching network 215. The Fourier analysis circuit can output the amplitude and phase of different frequency components from each of the sensors 280 and compare them to reference levels stored in other sensors 280 and / or memory. The signal analysis in some embodiments may include pattern recognition of amplitude or phase, or both, or artificial intelligence (AI) using a learning algorithm that can use a neural network or conventional digital algorithmic processing of signals from the sensors 280.

[0036] Signal processing by a Fourier analysis circuit to find both the fundamental and harmonic component signals of both amplitude and phase can be performed in less than approximately 10 microseconds, and in a preferred embodiment, in less than 1 microsecond for each sensor signal. The isolated signal analysis section 285 of the impedance matching network 215 can incorporate at least one computing or logic processor with substantial computing power, featuring ultrafast (<1 ns cycle time) circuitry using ultrafast logic ICs. In some embodiments, the processor within the signal analysis section 285 is programmable, so that the supplier or user of the processing chamber 240 can provide or implement their own algorithms or analysis software on the computing “platform” provided in the impedance matching network 215.

[0037] In some embodiments, a software program for calculating parameters from the signal amplitude and phase, and a further logic algorithm for determining the impact of deviations from acceptable plasma conditions on processing uniformity, may reside in a removable “plug-in” component connected to the signal processing section, which includes data storage. This software or logic calculates the range of deviations in the RF electromagnetic surface wave spectrum from the nominal or suitable operating conditions. Based on this, a processor associated with the controller can “decide” within about 1 millisecond to correct or terminate the process before the wafer is misprocessed. In some embodiments, a quantitative judgment regarding the expected effect of the deviation on process uniformity or other characteristics can be made within about 500 microseconds from occurrence, and as a result, corrective action can be initiated within 1 millisecond. Furthermore, actions can be taken to minimize or eliminate damage to the wafer or substrate being processed in the reaction chamber 240 at that point, thereby avoiding yield loss on that wafer or substrate.

[0038] The evaluation and / or decision made in the signal analysis section 285 of the impedance matching network 215 can, in some embodiments, be performed by a very fast computing or analysis system using algorithms present in plug-in storage and / or removable data processing devices. In yet other embodiments, the evaluation and decision made in the signal analysis section 285 can be performed using an analog or neural network processor. Such decisions can further utilize decision algorithms that may be present in removable storage or processing devices. Corrective action commands can then be rapidly transmitted by a high-speed data line from section 275 of the impedance matching network 215 to the RF generator 205, thereby temporarily interrupting, changing, or terminating power to the plasma. This ensures that the factory manager can quickly take or plan corrective actions for its processing chamber 240 and RF plasma processing system 200.

[0039] Also shown in Figure 2 is a pair of sensors 290 configured on the outer surface of the base 295 of the showerhead 230, outside the vacuum region within the reaction chamber 240 under atmospheric conditions. In some embodiments, an additional sensor 296 may be mounted on a pedestal base 297 and, like the sensor 290, connected by a high-speed signal cable to the disclosed signal processing section 275 of the impedance matching network 220. The sensor 296, located outside the vacuum environment of the reaction chamber 240, does not require a vacuum supply and is therefore substantially less expensive and less difficult to integrate into the information and processing network.

[0040] The sensors 255 may be positioned in several configurations to sense voltage and / or current on the surface of the pedestal 235 and may be covered and protected from the plasma by the dielectric cover 260. Because this type and position of sensor is close to the wafer and / or substrate, it may have a sensitivity advantage when detecting certain modes of EM surface waves that exhibit plasma asymmetry. This is a significant type of plasma inhomogeneity. These chamber sensors 255 may use a communication line that passes through the vacuum wall via a feedthrough, or in some embodiments, a wireless communication link operating at light or a lower frequency.

[0041] Generally, the phase and amplitude patterns of each frequency of EM surface waves on the surfaces of the showerhead 230 and pedestal 235 can be determined by analyzing signals from any of the groups of voltage, current, phase, or combined sensors 255, 280, 290, and 296. Generally, EM surface waves of a particular frequency generate voltage and current signals that have a phase relationship with signals of other frequencies. The magnitude of the voltage at each frequency and each point is the sum of the voltages from all waves of that frequency originating from all points on the entire electrode surface. In the case of an axially symmetric electrode surface where power is supplied symmetrically and the plasma is axially symmetric, the axially symmetric surface wave modes arise from the superposition of waves from all parts of the electrode and other surfaces within the reaction chamber 240. Generally, a perfectly symmetric plasma in a symmetric chamber with a symmetric electrode centered on the symmetry axis of the chamber will have a line of symmetry with equal phase and amplitude, mainly in the form of a circle centered on the center of the pedestal 235.

[0042] Referring to Figure 3, a cross-sectional view is shown of a dual-plate electrode assembly according to an embodiment of the present disclosure, having a broadband sensor that provides a voltage signal via an electrical connector having low shunt capacitance to the peripheral region of the electrode and to electrical ground. In some embodiments, the electrode, such as a showerhead 330, may include two conductive plates 331, 332 configured substantially parallel, center-aligned, and having substantially the same shape as a substrate or wafer. The surface of the first plate 331, facing outward as seen from the second plate 332, may be exposed to a vacuum environment and plasma. The first plate 331 is separated from the second plate 332 by a distance equal to the length of a dielectric standoff support 333. The first plate 331 may have a sensor 334 embedded in it, the pack or pickup of which is a conductive material, and whose surface is substantially coplanar with the surface of the first plate 331, facing outward as seen from the second plate 332.

[0043] In some embodiments, the sensor 334 may be mounted on 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 336 may have a dielectric constant of less than 5, and in some embodiments, the dielectric constant of an inorganic material such as aerogel based on quartz may be less than 2. The sensor 334 may have a high bandwidth ranging from 100 kHz to at least 10 times the highest driving frequency connected to its chamber, which may be equal to or greater than 300 MHz, and may be able to sense surface voltage, surface current, or both. In some embodiments, the sensitivity of the sensor 334 may vary by less than 30% over a range of harmonic frequencies of the primary fundamental RF frequency used in the reaction chamber. In some embodiments, at least one lead wire 337 from each sensor is connected to an internal conductor 338 of a vacuum electrical signal feedthrough 339, the base 341 of which is mounted on a second plate 215 which is electrically grounded. In some embodiments, the leads from each sensor can be directly connected to a circuit board located similarly to 332, which has a ground plane and a detector circuit, one for each sensor, in order to determine the amplitude and phase of each frequency component.

[0044] The total shunt capacitance from the sensor 334, the lead wire 337, and the feedthrough 339 to the ground must be less than 5 picofarads, and in some embodiments less than 3 picofarads, so the internal conductor 338 of the feedthrough 339 may have a small shunt capacitance relative to the base 341 of the feedthrough 339 mounted on a grounded second plate 332, e.g., less than 5 picofarads, and in some embodiments less than 2 picofarads. In some embodiments, the output from the base 341 mounted on the grounded second plate 332 may be connected to an attenuator (not shown). In some embodiments, the attenuator may include an electrical resistor having a resistance greater than about 100 ohms. A shunt resistor to ground 405 may be in parallel with the electrical resistor 404. The resistance of the shunt resistor may be, for example, 50 ohms, or it may be equal to the impedance of the cable connecting the attenuator to a communication network or a plasma chamber controller. If the detector is located in Figure 3 instead of the connector as shown in the diagram, the signal output from the detector is the amplitude and phase of the voltage or current at each frequency of the sensor, which is transmitted to the analysis processor and may be located in a section of the matching network.

[0045] Each sensor 334 can measure the voltage or current amplitude of a combined electromagnetic surface wave mode, which has the fundamental and harmonic frequencies of all RF generators supplying power to the plasma as components. The fundamental and harmonic frequencies span the same range from about 10 kHz to about 500 MHz or more. In other embodiments, the sensor can measure voltage at fundamental and harmonic frequencies in the range of about 100 kHz to about 1 GHz.

[0046] Figure 4 shows a cross-sectional view of a pedestal equipped with a recessed broadband voltage sensor according to an embodiment of the present disclosure. The voltage sensor 401 may be mounted on an electrode such as a pedestal 400. In some embodiments, the sensor 401 may be connected to electrical ground 406 via a resistor. The tip or pack of the sensor 401 may have lead wires 402 surrounded by a dielectric 403 (which may be air or vacuum, depending on the circumstances). In some embodiments, the lead wires 402 from the sensor 401 may pass through an attenuator such as a resistor 404 with a shunt resistor 405, the shunt resistor 405 may be about 50 ohms in some embodiments and may also be connected to electrical ground 406. Such a resistor 404 may be non-inductive and may have a resistance in the range of about 100 ohms to about 100,000 ohms. In some embodiments, the resistance may be between about 500 ohms and about 10,000 ohms. The resistor 405 may also be non-inductive.

[0047] Furthermore, the dielectric 403 is generally nonmagnetic and has low-loss tangents, which should be less than about 0.01 in some embodiments and less than about 0.001 in other embodiments. The shunt capacitance between the tip of the sensor 401 and the lead wire 402 to the ground electrode should be less than about 5 picofarads, or less than about 2 picofarads in some embodiments, and as a result, the reactance between the sensor 401 and the pedestal 400 or electrode should be greater than about 100 ohms at 300 MHz. The purpose of such low shunt capacitance is to reduce the surface wave load by the sensor 401, thereby absorbing the wave energy to the minimum extent and allowing the wave to propagate as if there were no sensor 401. Under such conditions, the detected surface potential will not differ significantly from that at the electrode without such sensor 401.

[0048] Referring to Figure 5, a schematic side view of a pedestal with the relevant RF and control components according to an embodiment of the present disclosure is shown. The pedestal 501 power supply circuit is an RF generator 505and an impedance matching network 506. High-speed signal lines, for example, cables 511, 512 carry signals from sensors 502, 503 to a section that, in some embodiments, may be in or connected to the impedance matching network 506. High-speed lines 513 of the data network take information from the impedance matching network 506 to a controller 514 of the reaction chamber, generator, or tool or factory (not shown). Sensors 502, 503 are mounted on or near the base 504 of a pedestal 501, and the pedestal 501 may be inside or outside the vacuum area of ​​the reaction chamber.

[0049] In some embodiments, there may be a fault detection compartment 510 related to signal analysis, for example, 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 electronic equipment. The signal analysis compartment 510 is connected to cable 511, 512 Signals are received from sensors 502 and 503 via the signal analysis section 510. The signal analysis section 510 then directs the signals from each sensor 502 and 503 to an internal circuit which may be called a detector and may include electronic components such as transistors and passive components. In an alternative embodiment in which the amplitude and phase are observed in close proximity to the sensor for each frequency component, the signals coming to the signal analysis section may be the amplitude and phase for each frequency component rather than the raw signals.

[0050] Each detector (not shown) within section 510 can perform RF spectral analysis of signals from one sensor 502, 503, or from a group of sensors which may be analyzed in parallel. The analysis may include averaging the signals from the group of sensors, or one or more sensors 502, 503, over time for noise reduction. In some embodiments, each detector may have amplitude and phase outputs for each frequency component of the signal obtained by each sensor 502, 503, e.g., the fundamental and harmonics. The outputs from each detector may then be input to an analog-to-digital converter for each harmonic signal to generate digitized values ​​of both the amplitude and phase of each measured harmonic.

[0051] The frequency components and these digital amplitude and phase values ​​for each sensor can be input to a high-speed digital processor in a signal analysis section associated with the disclosed impedance matching network with little to no delay, for example, less than 10 microseconds. The digital processor analyzes both the amplitude and phase information of the fundamental wave and each harmonic from the sensor and determines the relative magnitudes of the various surface wave modes, including axisymmetric and non-axisymmetric modes, for both the fundamental wave and harmonics. There may be different non-axisymmetric modes for each frequency component, and one or more of these may be indicators of plasma inhomogeneity.

[0052] In some embodiments, such non-axisymmetric modes may be rapidly identified by an algorithm present in the plug-in. A reference database correlating the magnitude of non-axisymmetric modes with the percentage of plasma inhomogeneity may also be present in this plug-in or a removable processor. The digital processor may also calculate the rate of change of the amplitude of wave modes and the acceleration of the amplitude of one or more wave modes to determine the likelihood of a near-future failure. One measure of the magnitude of a non-axisymmetric mode at a given frequency may be the difference between the phases of a given frequency surface wave at different sensor positions that have the same radial distance from the center of the circular electrode and are symmetrically arranged in an axisymmetric chamber. Alternatively, a second measure of a non-axisymmetric mode may be the difference between the amplitudes of a given frequency surface wave at different sensor positions that have the same radial distance from the center of the circular electrode and are symmetrically arranged in an axisymmetric chamber.

[0053] A matched network 506 having an isolated compartment 510 including a multi-channel detector system (not shown) can simultaneously perform Fourier analysis, digitize, and record the voltage amplitude and phase of EM waves propagating at various locations on the pedestal 501. Due to inherent noise, each of the determined voltage amplitudes and phases can be averaged over short time intervals as needed, and also averaged over groups of sensors 502, 503 to determine the relative magnitude or time average over a relatively large number of pulses.

[0054] A showerhead, pedestal, or other power supply element such as an electrode equipped with a group or array of sensors may be used as a test system to generate data for characterizing and recording the relationship between the spectrum and spatial pattern of EM wave modes, and various non-uniformities of plasma density during an RF process. In some embodiments, this data may be analyzed offline by an engineer to characterize and classify the plasma behavior and be placed into a database that can be stored in a plug-in storage device that can be connected to a matching network section or other controller or monitoring system.

[0055] The relationship between the amplitude and phase pattern characteristics of non-axisymmetric and axisymmetric EM modes and process and plasma heterogeneity or deviation from suitable conditions may be stored in a plug-in connected to a disclosed signal analysis section of the matching network. In implementations where the RF plasma processing system may be used as a manufacturing tool, plasma and process heterogeneity can thus be rapidly detected when the chamber operation is being monitored. For example, a sensor of the type disclosed as shown in Figure 4, configured as shown in Figure 2, may be retrofitted to an RF plasma system such as the one shown in Figure 1.

[0056] To determine whether a process plasma may have experienced a plasma failure condition, an analysis processor in a signal analysis section associated with an impedance matching network may calculate parameters for each of a pre-specified set of harmonics of the drive frequencies of some electrodes or antennas, partially based on the magnitude of the non-axisymmetric EM mode. The processor in some embodiments can then compare these parameters to a reference range in a database. Such a reference database may reside in a section within the impedance matching network, or in a plug-in connected to a signal analysis section that may be a section associated with the impedance matching network.

[0057] The database can store parameters characterizing various plasma states to help determine how severe and to what extent the plasma deviation from the acceptable “process window” is. In some embodiments, the analysis may include a comparison of the phases of each harmonic from all sensors or groups thereof at a given distance from the center of the electrode. The dispersion of such phases of a sensor or group of sensors with respect to any azimuthal angle may be a measure of the asymmetry of the generation and / or propagation of its harmonic modes, and therefore a measure of the asymmetry and heterogeneity of the plasma. In some embodiments, the analysis may include a calculation of the amplitude difference between sensors or groups of sensors at a given distance from the axis of symmetry. The dispersion of such amplitudes of sensors within a range of azimuthal angles or groups of adjacent sensors may be a measure of the asymmetry of the generation and / or propagation of its harmonic modes, and therefore a measure of the asymmetry and heterogeneity of the plasma.

[0058] Next, parameters, which are quantitative measurements of the asymmetry of each harmonic in a set, may be stored in a plug-in unit or transmitted to the chamber and tool controllers via a data network. Furthermore, the trend and acceleration of the parameters can be calculated and compared with reference values ​​and decision criteria in a database as part of a process to determine whether a fault condition has occurred. In some embodiments, when such a fault condition occurs, the algorithms and decision criteria that can be stored in the plug-in may be executed by a processor in the compartment to determine a course of remediation or preventive action. Such action may then be rapidly transmitted to the RF generator and / or chamber and / or tool controllers.

[0059] In some embodiments, a database of parameters, algorithms, criteria, and specifications for comparing parameters, their rate of change, and their acceleration may reside on a data storage device or removable processor, which may be connected to a port that is an input / output port of the signal analysis section. Analysis of surface wave modes based on signals from sensors and parameters derived therefrom is performed very quickly by the processor, allowing fault declarations and a sequence of corrective actions to be transmitted to the RF generator, reported to the chamber or system controller via the network within 5 milliseconds of occurrence. In some embodiments, the fault condition and specified corrective action commands can be transmitted to the generator within 1 millisecond.

[0060] In some embodiments, many types of plasma deviations from the desired plasma uniformity can be detected quickly enough for a tool or chamber controller to take corrective action to address the plasma fault condition before the wafer or substrate is misprocessed. Depending on the situation, specified corrective actions may include briefly changing the RF power format (such as continuous wave (CW) or pulsed), briefly turning off the power completely, stopping the processing of the current wafer and saving or discarding wafers for later processing, or shutting down the reaction chamber for maintenance. Thus, adjusting the frequency within a range of approximately 10 percent of the RF power may thereby change the reflected power.

[0061] In certain embodiments, upon detection of a plasma fault condition, a disclosed signal analysis section related to the matching network can command appropriate corrective actions to be performed by the RF generator and / or, in some embodiments, by the matching network. For example, the RF process generator can initiate a termination process to end wafer processing in response to a signal measured by sensors on the showerhead and / or pedestal. In certain embodiments, the frequency can be adjusted, i.e., increased or decreased by approximately 1 / 10 to 10 percent. Alternatively, power may be interrupted by the RF plasma processing deposition system to stop or pulse the plasma so that the secondary plasma stops or is significantly reduced. In some cases, after a very brief interruption, processing may be able to resume by a specified remedial action. In certain implementations, the remedial action can be determined, for example, through a programmed remedial program based on machine learning and / or yield data or other wafer diagnostics.

[0062] Referring to Figure 6, a top view is shown of the propagation of axially symmetric surface waves across a pedestal in a reaction chamber where the plasma is axially symmetric, according to an embodiment of the present disclosure. In Figure 6, circle 601 is a constant phase and amplitude curve of the fundamental and harmonic frequency components of an axially symmetric surface wave mode. The circle is concentric with the electrode. These modes are very powerful when the electrode and plasma are all axially symmetric and coaxial in the chamber. The propagation vector 602 of the surface waves at any frequency is radial. The waves propagate toward and away from the center, and as they propagate, such waves inject power into the plasma.

[0063] Referring to Figure 7, a top view of transverse electromagnetic surface wave propagation across an electrode according to an embodiment of the present disclosure is shown. In Figure 7, lines 701–704 of constant phase and equal amplitude for a particular single non-axisymmetric mode are nearly straight and parallel, whether at the fundamental frequency or its harmonic frequency. Such surface waves can be detected by sensors positioned on the pedestal or showerhead of the RF plasma deposition system. This mode is sometimes referred to as “transverse,” meaning that the direction of propagation is across the electrode surface from one side to the other, or both to the left and right of the center plane, as seen in the propagation vectors 705–707. Other non-axisymmetric modes may exist, where lines of constant phase are curves with a center of curvature displaced from the center of the electrode. Detector readings per frequency can be decomposed into the sum of axisymmetric modes and (often a small number) non-axisymmetric modes, reflecting the major inhomogeneities of the plasma. Typically, decomposition allows for the identification of transverse mode components and / or one major “off-center” or displaced radial mode, either of which is characteristic of the plasma heterogeneity configuration. Correlation between the plasma heterogeneity configuration and specific non-axisymmetric modes is performed prior to production processing as part of building a database that may reside in a plug-in unit or elsewhere.

[0064] Referring to Figure 8, a top view is shown of one preferred arrangement of azimuthal sensors for a reaction chamber according to an embodiment of the present disclosure. In this embodiment, a plurality of sensors 800 may be arranged azimuthally around one or more components of the reaction chamber and / or within the reaction chamber itself. As briefly described above, a plurality of sensors 800, which may be four in this embodiment, may be arranged at different angles around the chamber symmetry axis 805 to measure surface voltage or current related to surface waves, on certain chamber components such as showerheads and / or pedestals. In this case, the intervals are 90 degrees, but in some embodiments, the intervals may be irregular in azimuthal angles.

[0065] The sensors 800 may include passive sensors 800 that receive changing potentials or magnetic fields. The sensors 800 may be positioned at different azimuthal angles to detect EM waves having different types of propagation modes with respect to the chamber symmetry axis 805. The sensors 800 may be positioned equidistant from the chamber symmetry axis 805 and / or components within the reaction chamber, or around the reaction chamber itself. Similarly, the sensors 800 may be positioned opposite each other so that the distance between the sensors 800 and the symmetry axis is approximately the same. For example, the distance between sensors 800-1 and 800-2 is approximately the same as the distance between 800-3 and 800-4. Similarly, each sensor 800 is positioned at the same distance from the chamber symmetry axis 805. Examples of the spacing and position of the sensors 800 will be discussed in more detail below.

[0066] As illustrated, the sensors 800 are positioned in diametrically opposed locations. For example, sensor 800-1 is directly opposite sensor 800-3, while sensor 800-2 is directly opposite sensor 800-4. Thus, for non-axisymmetric plasmas, sensors 800 may detect waveform differences on different sides of the reaction chamber and / or its components, and when waveform differences occur, provide notification as described above, which may result in corrective or preventive measures being taken. For example, if sensors 800-1 and 800-4 detect and report waveform differences from their diametrically opposed positions, such differences may indicate that the phases of the harmonics are shifted or that the amplitudes are different. This may indicate that there is heterogeneity and asymmetry in the plasma. Such waveform differences occur when there is a difference between the diametrically opposed detectors in the relative phase or amplitude of one or more harmonics of the signal received by the opposite sensor.

[0067] In certain embodiments, four sensors 800 may be used, as shown in Figure 8. However, in other embodiments, different numbers of sensors 800 may be used, such as 6, 8, 12, 14, 16, 18, 20, or more sensors 800. In some embodiments, the azimuthal angles between sensors may not be equal, but nevertheless, the same characteristics of the non-azimuthal symmetric plasma mode can be observed by the sensors. In certain implementations, having 6 to 12 sensors 800 may be beneficial. A larger number of sensors 800 allows for the collection of more data, thereby providing an enhanced ability to identify noise and sensitivity for recognizing heterogeneity. However, increasing the number of sensors 800 may slow down data processing, but this results in slower-acting corrective and preventive measures. Those skilled in the art will understand that the RF plasma process can be optimized by balancing the number of sensors 800 with a desired level of data granularity. Thus, as computing power increases and the speed at which data can be processed increases, increasing the number of sensors 800 may be beneficial. In certain embodiments, specific sensors 800 can be selectively turned off and on, thereby allowing the controller to access specific required data. For example, in a system with eight sensors, selecting and turning off four sensors can reduce the amount of data they generate. In other embodiments, additional sensors can be added or removed from operation, thereby changing the amount of data they generate.

[0068] Furthermore, the sensor 800 may include various types of sensors, both circular and other shapes. In certain embodiments, the sensor 800 may be circular with an area between approximately 0.1 square centimeters and approximately 10 square centimeters. The sensor 800 may further include a surface insulating layer or coating to protect the sensor 800 from plasma or reaction species in the reaction chamber, and may also include a Faraday shield for current sensors, an aluminum coating, and any other coatings and layers of the same kind.

[0069] Referring to Figure 9, a side cross-sectional view of a sensor mounted in the reaction chamber in the azimuthal direction according to an embodiment of the present disclosure is shown. In this embodiment, the reaction chamber 940 has a symmetry axis 905 extending longitudinally from the center of the shower head 930 through the pedestal 935. In other embodiments, the symmetry axis 905 It may extend longitudinally from the center of another electrode, such as an antenna. Multiple sensors 900 may be positioned at various locations around and inside the reaction chamber 940, and around or in relation to specific components such as the showerhead 930 and / or pedestal 935 in the azimuthal direction. Figure 9 is a cross-sectional view and shows only two sensors 900 per location, but more sensors 900 may be used during the implementation of the RF plasma monitoring process, as will be discussed in detail with respect to Figure 8.

[0070] In certain embodiments, the sensor 900-1 may be positioned on or around the edge of the shower head 930. In such an implementation, the sensor 900-1 is located on the shower head 930The sensors 900-1 may be at least partially or completely embedded within the showerhead 930, and the outer surface of the sensor 900-1 may be coated with an insulating layer, thereby protecting the sensor 900-1 from the environment within the reaction chamber 940. In such embodiments, two or more sensors 900-1 may be arranged azimuthally around the edge of the showerhead 930, and preferably four or more sensors, thereby enabling the detection of non-uniformity and asymmetry in the RF plasma processing.

[0071] In other embodiments, sensor 900-2 may be positioned along the edge of pedestal 935 within the vacuum of reaction chamber 940. As described 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 positioned on its outer surface. Furthermore, in some embodiments, sensors 900-2 may have a dielectric protective portion covering them. In addition to sensors 900-2 positioned around pedestal 935 within the vacuum, other sensors 900-3 and 900-4 may be positioned outside the vacuum of reaction chamber 940 and around pedestal 935. Such sensors 900-3 and 900-4 may be positioned on a metal surface along pedestal 935 and / or its base portion. Sensor 900 may also be positioned on or in relation to other support structures of pedestal 935.

[0072] In yet another embodiment, sensors 900-5 may be positioned and / or otherwise incorporated into the side wall of the reaction chamber 940. In such embodiments, where the wall is dielectric, sensors 900-5 may be positioned outside the reaction chamber 940 on the outer chamber wall 915, or sensors 900-5 may be incorporated into the side wall so as to be within the vacuum of the reaction chamber 940. In the case of a metal wall, the sensors should have their pickups exposed to the inner surface of the wall so as to be able to sense the EM field in the chamber. Another sensor 900-6 may be positioned in a viewport 920 located along the outer chamber wall 915. In such embodiments, sensors 900-6 in the viewport may be positioned outside the vacuum of the reaction chamber 940, or they may be positioned inside the reaction chamber 940.

[0073] In yet another embodiment, the sensor 900-7 may be located, for example, in a dielectric located around the showerhead 930, while in another implementation, the sensor 900-7 may be located in a dielectric located around the pedestal 935. Although specific locations of the sensor 900 are discussed herein, the sensor 900 may be located in various other locations within and around the reaction chamber 940. For example, the sensor 900 may be located inside or outside the dielectric wall near the antenna or other components. Furthermore, the sensor 900 may be located in various other locations within the metal wall of the reaction chamber 940.

[0074] In certain embodiments, combinations of sensors 900-1 to 900-7 may be used to more accurately monitor the RF plasma processing. For example, sensor 900-1 around the edge of the showerhead 930 may be combined with sensor 900-2 around the edge of the pedestal 935. Similarly, combinations of sensors 900-5 outside the reaction chamber 940 may be combined with sensors 900-1 / 900-2 located inside the reaction chamber 940. In yet another embodiment, combinations of 3, 4, 5, 6, 7, or more variations of the sensor 900 positions can be used to further optimize the monitoring of the RF plasma processing.

[0075] Referring to Figure 10, a side cross-sectional view of a model reaction chamber according to an embodiment of the present disclosure is shown. In this embodiment, preferred positions of a plurality of sensors 1000 arranged in the azimuthal direction are shown, positioned around the lower electrode, which is a pedestal 1035 in this embodiment. Similar to the sensors 1000 discussed above with respect to Figure 9, Figure 10 shows sensors 1000 positioned in various locations. Sensor 1000-1 is positioned around the outer edge of the pedestal 1035. The azimuthal position of sensor 1000-2 is positioned around the inside of the reaction chamber 1040, while the azimuthal position of sensor 1000-3 is positioned around the outer periphery of the reaction chamber 1040 in an adjacent viewport.

[0076] In this embodiment, 12 sensors 1000 are shown at each location; however, other implementations may use other numbers of sensors 1000, both fewer and more. In addition to the explicitly shown sensor 1000 locations, other sensor 1000 locations may also be used to further enhance RF plasma processing.

[0077] Referring to Figure 11, a schematic side cross-sectional view of a reaction chamber according to an embodiment of the present disclosure is shown. In this embodiment, the sensor 1100 is shown positioned around the antenna of the inductively coupled plasma source 1105. Thus, the sensor 1100 can sense an RF current or voltage from the plasma source located within the reaction chamber 1140.

[0078] Referring to Figure 12, a partial cross-sectional view of an RF plasma processing system according to an embodiment of the present disclosure is shown. In this embodiment, the RF plasma processing system 1200 includes a pedestal 1235. The pedestal 1235 includes a sensor 1240 positioned along the upper outer edge of the pedestal 1235. As described above, the sensor 1240 may be positioned on the upper outer edge embedded within the pedestal 1235, or it may be positioned alternately around either the inner or outer outer edge of the vacuum of the reaction chamber.

[0079] Furthermore, the RF plasma processing system 1200 includes a circuit 1245 connected to the sensor 1240 via a communication line 1250. Since the sensor 1240 receives data sensed from the RF plasma processing system 1200, the data can be transmitted to the circuit 1245 for processing. Because the circuit 1245 is relatively close to the sensor 1240, the time required to transfer the sensed data between them can be reduced. Therefore, initial calculations regarding the electrical characteristics sensed by the sensor 1240 can be performed more quickly and then transferred to other components 1255 of the RF plasma processing system 1200. Other components 1255 may include, for example, an RF generator, an impedance matching network, a fault detection compartment, an operating controller for the reaction chamber, an operating controller for a tool, a plug-in device, a signal analysis compartment, or other components connected to the RF plasma processing system 1200.

[0080] Subsequently, components 1255 or any other components of 1200 not shown can be used to adjust the configuration of the RF plasma processing system 1200 to correct faults detected by the sensor 1240 and processed at least partially within the circuit 1245. The circuit 1245 may be located in an isolated structure within the pedestal 1235 outside the vacuum of the reaction chamber to protect the circuit 1245 from conditions within the reaction chamber. In other embodiments, the circuit 1245 may be located at the base of the pedestal 1235 or in other areas adjacent to the pedestal 1235.

[0081] Figure 12 shows a cross-section of the components of the RF plasma processing system 1200, and those skilled in the art will understand that the circuits 1245 may be arranged at approximately the same radius at different azimuth angles around the pedestal 1235. Thus, an independent circuit 1245 may be available for each sensor 1240, or the sensors 1240 may be connected to a centralized circuit 1245 located at one or more selected locations around and / or inside the pedestal 1235.

[0082] Referring to Figure 13, a partial cross-sectional view of an inductively coupled RF plasma processing system according to an embodiment of the present disclosure is shown. The sensor 1340 is shown configured in close proximity to the induction antenna 1330 and can be mounted outside or inside a dielectric wall (not shown) adjacent to the antenna.

[0083] The foregoing descriptions use specific nomenclature for illustrative purposes to provide a complete understanding of the Disclosure. However, it will be apparent to those skilled in the art that specific details are not required to implement the systems and methods described herein. The foregoing descriptions of specific embodiments are presented for illustrative and descriptive purposes. They are not intended to exhaust this Disclosure or to limit it to the exact form described herein. Obviously, many modifications and variations are possible, taking into account the teachings above. The embodiments are shown and described in order to best illustrate the principles and practical applications of the Disclosure, thereby enabling those skilled in the art to best utilize various embodiments with various modifications suitable for the Disclosure and the specific use intended. The scope of this Disclosure is intended to be defined by the following claims and their equivalents. Some aspects of the present invention are described below. [Aspect 1] An automatic impedance matching network for controlling a radio frequency generator, Each signal input port is connected to a different broadband radio frequency detector, and each of the multiple signal input ports and multiple broadband radio frequency detectors is located in a radio frequency isolation section within the automatic impedance matching network, where each of the multiple broadband radio frequency detectors is equipped with a circuit configured to analyze signals by frequency, and each of the multiple broadband radio frequency detectors is externally connected to a broadband radio frequency sensor associated with a reaction chamber and is capable of receiving signals from the broadband radio frequency sensor. A computation and logic processor programmed to determine the difference between the amplitude and phase of each frequency component, and connected to multiple outputs of the multiple broadband radio frequency signal detectors, An automatic impedance matching network comprising an output from a computation and logic processor configured to provide input data to at least one of the radio frequency generator and processing controller of the reaction chamber. [Aspect 2] The automatic impedance matching network according to embodiment 1, further comprising at least one additional input and output port, which is internally connected to the compute and logic processors within the compartment and further connected to a removable device that stores data and provides programming instructions for the compute and logic processors. [Aspect 3] The automatic impedance matching network according to Embodiment 1, wherein a plurality of detectors within the section of the impedance matching network are connected to at least one of the broadband radio frequency detectors via the signal input ports, and the broadband radio frequency detector is located inside or near the reaction chamber. [Aspect 4] The automatic impedance matching network according to Embodiment 1, wherein the plurality of broadband radio frequency detectors may be configured to sense radio frequency signals at other radio frequencies, including fundamental and harmonic frequencies, associated with a second radio frequency generator that supplies power to the reaction chamber. [Aspect 5] The automatic impedance matching network according to Embodiment 1, wherein the plurality of broadband radio frequency detectors include the circuit configured to perform a Fourier analysis of the execution time series of signal inputs to the plurality of broadband radio frequency detectors into the fundamental frequency, the harmonic frequencies and relative phase, and each of the plurality of broadband radio frequency detectors has an output port connected to the input port of the computation and logic processor. [Aspect 6] Automated impedance matching network section, The computation and logic processors within the section of the automatic impedance matching network, and the plurality of signal input ports to the section of the automatic impedance matching network, each of the signal input ports is externally connected to at least one broadband radio frequency detector associated with the reaction chamber, and An automatic impedance matching network comprising output ports from the computation and logic processors for providing input data to at least one of the radio frequency generator and the processing controller of the reaction chamber. [Aspect 7] The automatic impedance matching network according to embodiment 6, further comprising at least one input port and an output port that are internally connected to a computing processor in the compartment and connected to a removable device that stores data and programming instructions for the computing processor. [Aspect 8] The automatic impedance matching network according to embodiment 6, wherein the at least one broadband radio frequency detector within the compartment of the automatic impedance matching network is connected to at least one of the broadband radio frequency detectors via the signal input port, and the broadband radio frequency detector is located inside or in close proximity to the reaction chamber. [Aspect 9] The automatic impedance matching network according to Embodiment 1, wherein the broadband radio frequency detector includes a circuit that performs the Fourier analysis on the fundamental frequency and harmonic frequencies of the execution time series of signal inputs to the at least one broadband radio frequency detector, and provides the computation and logic processor with the amplitude and phase of the fundamental frequency components and harmonic frequency components of the signal received by the at least one broadband radio frequency detector as outputs. [Aspect 10] A method for rapidly detecting secondary plasma in plasma-based processing, To automatically adjust the inactive impedance and supply radio frequency power to an impedance matching network that substantially absorbs the radio frequency power from the generator through the reaction chamber, To provide a radio frequency isolated section of the impedance matching network having multiple broadband radio frequency detectors, each having multiple outputs connected to a computing processor, wherein the input of each detector is externally connected to a broadband radio frequency sensor associated with the reaction chamber, To conduct signals to a plurality of broadband radio frequency detectors, which transmit spectral information to a processor programmed to perform radio frequency spectral analysis of signals from the sensors in the reaction chamber and to calculate the difference between the broadband radio frequency detectors in the amplitude and phase of each frequency component of each frequency component detected by each broadband radio frequency detector, To determine the asymmetry between the fundamental and harmonics of the radio frequency within the reaction chamber, and A method comprising determining, based on the determination of the asymmetry, whether there was a rapid change in the plasma symmetry caused by the secondary plasma. [Aspect 11] The method according to embodiment 10, wherein there is at least one input port and output port that are internally connected to a computing processor in the compartment and further connected to a removable device that stores data and programming instructions for the computing processor, the computing processor further retrieves an algorithm from the removable device to calculate at least one recommended action for the radio frequency generator and the impedance matching network. [Aspect 12] The method according to embodiment 10, wherein the broadband radio frequency detector in the reaction chamber is arranged in an azimuthal direction around the axis of symmetry of the electrode in the reaction chamber, thereby determining the asymmetry of the plasma adjacent to the electrode. [Aspect 13] The method according to embodiment 10, further comprising the broadband radio frequency detector which analyzes the radio frequency signal at other radio frequencies, including fundamental and harmonic frequencies, related to another radio frequency generator that supplies power to the reaction chamber. [Aspect 14] The method according to embodiment 10, further comprising each broadband radio frequency detector performing the Fourier analysis on the fundamental and harmonic frequencies, amplitudes, and relative phases of a running time series of signal inputs from the broadband radio frequency sensor to the broadband radio frequency detector within an azimuthal angle range around the electrode, wherein the computing processor determines the asymmetry of the plasma adjacent to the electrode using the amplitude and phase changes of the fundamental and harmonic frequencies having an azimuthal angle. [Aspect 15] A method for detecting plasma asymmetry in a radio frequency plasma processing system, To supply radio frequency power to a reaction chamber having adjacent chamber symmetry axes, Receiving radio frequency signals from multiple broadband electromagnetic sensors, Processing the radio frequency signal using Fourier analysis, and A method comprising determining, based on the Fourier analysis of the radio frequency signal, that an asymmetry has occurred in the plasma within the reaction chamber. [Aspect 16] The method according to embodiment 15, wherein the determination includes comparing the Fourier analysis of the radio frequency signal with a historical dataset indicating when the plasma asymmetry occurs. [Aspect 17] The method according to embodiment 15, wherein processing the radio frequency signal using the Fourier analysis includes comparing at least one of the amplitudes and phases of the Fourier components for at least one of the fundamental frequency and harmonic frequency received on different sides of the reaction chamber. [Aspect 18] The method according to embodiment 15, further comprising determining an asymmetric trajectory based on the Fourier analysis of the radio frequency signal. [Aspect 19] The method according to embodiment 15, wherein the processing of the radio frequency signal using the Fourier analysis is performed in about 1 microsecond. [Aspect 20] The method of embodiment 15, further comprising providing a programming instruction to a radio frequency generator based on the determination, based on the Fourier analysis of the radio frequency signal, that the plasma asymmetry occurred in the reaction chamber.

Claims

1. An automatic impedance matching network for controlling a radio frequency generator, The system has multiple signal input ports and multiple broadband radio frequency detectors, each of the multiple signal input ports being connected to a different broadband radio frequency detector, each of the multiple broadband radio frequency detectors having a circuit configured to analyze signals by frequency, each of the multiple broadband radio frequency detectors being externally connected to one of a plurality of broadband radio frequency sensors associated with the reaction chamber, and a radio frequency isolated signal analysis section capable of receiving signals from the broadband radio frequency sensor, It comprises a computation or logic processor programmed to determine the difference between the amplitude and phase of each frequency component, and connected to multiple outputs of the multiple broadband radio frequency detectors, An automatic impedance matching network is configured to provide input data to at least one of the radio frequency generator and processing controller of the reaction chamber, from the output of the calculation or logic processor.

2. The automatic impedance matching network according to claim 1, further comprising at least one additional input and output port, which is internally connected to the computing or logic processor in the signal analysis section and further connected to a removable device that stores data and provides programming instructions for the computing or logic processor.

3. The automatic impedance matching network according to claim 1, wherein a plurality of broadband radio frequency detectors within the signal analysis section of the impedance matching network are connected to at least one of the broadband radio frequency sensors via the signal input port, and the broadband radio frequency sensor is located inside or near the reaction chamber.

4. The automatic impedance matching network according to claim 1, wherein the plurality of broadband radio frequency detectors may be configured to sense radio frequency signals at radio frequencies including fundamental and harmonic frequencies related to a second radio frequency generator that supplies power to the reaction chamber.

5. The automatic impedance matching network according to claim 1, wherein the plurality of broadband radio frequency detectors include the circuit configured to perform a Fourier analysis of the fundamental frequency, harmonic frequencies, and phase of the execution time series of signal inputs to the plurality of broadband radio frequency detectors, and each of the plurality of broadband radio frequency detectors has an output port connected to the input port of the computation or logic processor.

6. An automatic impedance matching network, Radio frequency isolation signal analysis section, A computing or logic processor in the partition within the automatic impedance matching network, A plurality of signal input ports in the section within the automatic impedance matching network, each of which is a signal input port externally connected to at least one broadband radio frequency sensor associated with the reaction chamber, An output port from the calculation or logic processor for providing input data to at least one of the radio frequency generator and processing controller of the reaction chamber, It has, The automatic impedance matching network comprises an automatic impedance matching network in which at least one broadband radio frequency detector within the section is connected to at least one broadband radio frequency sensor via the signal input port, and the broadband radio frequency sensor is located inside or in close proximity to the reaction chamber.

7. The automatic impedance matching network according to claim 6, further comprising at least one input / output port that is internally connected to a computing processor in the compartment and connected to a removable device that stores data and programming instructions for the computing processor.

8. The automatic impedance matching network according to claim 1, wherein the broadband radio frequency detector includes a circuit that performs a Fourier analysis of the execution time series of the signal input to the at least one broadband radio frequency detector into fundamental frequency and harmonic frequency, and provides the computation or logic processor with the amplitude and phase of the fundamental frequency component and the harmonic frequency component of the signal received by the at least one broadband radio frequency detector as outputs.

9. A method for rapidly detecting secondary plasma in plasma-based processing, The system automatically adjusts its reactive impedance and supplies radio frequency power to an impedance matching network that substantially absorbs the radio frequency power from the generator through the reaction chamber, The impedance matching network is provided with a radio frequency isolation signal analysis section having multiple broadband radio frequency detectors, each having multiple outputs connected to a computing processor, the input of each broadband radio frequency detector being externally connected to a broadband radio frequency sensor associated with the reaction chamber, The signal from the broadband radio frequency sensor in the reaction chamber is transmitted to the plurality of broadband radio frequency detectors, the radio frequency spectral analysis of the signal is performed, and the spectral information is transmitted to a processor programmed to calculate the difference between the broadband radio frequency detectors in the amplitude and phase of each frequency component of each frequency component detected by each broadband radio frequency detector. To determine the asymmetry between the fundamental and harmonics of the radio frequency within the reaction chamber, A method comprising determining, based on the determination of the asymmetry, whether there was a rapid change in the plasma symmetry caused by the secondary plasma.

10. The method according to claim 9, wherein there is at least one input / output port that is internally connected to a computing processor in the compartment and further connected to a removable device that stores data and programming instructions for the computing processor, the computing processor further retrieves an algorithm from the removable device to calculate at least one recommended action for the radio frequency generator and the impedance matching network.

11. The method according to claim 9, wherein the broadband radio frequency sensors in the reaction chamber are arranged in an azimuthal direction around the axis of symmetry of the electrodes in the reaction chamber, thereby determining the asymmetry of the plasma adjacent to the electrodes.

12. The method according to claim 9, further comprising a broadband radio frequency detector that analyzes a radio frequency signal at radio frequencies including fundamental and harmonic frequencies related to another radio frequency generator that supplies power to the reaction chamber.

13. The method according to claim 9, further comprising each broadband radio frequency detector performing a Fourier analysis on the fundamental frequency, harmonic frequencies, amplitude, and relative phase of a running time series of signal inputs from the broadband radio frequency sensor to the broadband radio frequency detector over a range of azimuthal angles around the electrode, wherein the computing processor determines the asymmetry of the plasma adjacent to the electrode using the amplitude and phase changes of the fundamental and harmonic frequencies having azimuthal angles.

14. A method for detecting plasma asymmetry in a radio frequency plasma processing system, To supply radio frequency power to a reaction chamber having a chamber symmetry axis, Receiving radio frequency signals from multiple broadband electromagnetic sensors, Processing the radio frequency signal using Fourier analysis within the radio frequency isolation signal analysis section of the impedance matching network, and A method comprising determining that plasma asymmetry has occurred in the reaction chamber based on the Fourier analysis of the radio frequency signal.

15. The method according to claim 14, wherein the determination includes comparing the Fourier analysis of the radio frequency signal with a historical dataset indicating when the plasma asymmetry occurs.

16. The method according to claim 14, wherein processing the radio frequency signal using the Fourier analysis includes comparing at least one of the amplitude and phase of the Fourier components for at least one of the fundamental frequency and harmonic frequency received on different sides of the reaction chamber.

17. The method according to claim 14, wherein the processing of the radio frequency signal using the Fourier analysis is performed in about 1 microsecond.

18. The method of claim 14, further comprising providing a programming instruction to a radio frequency generator based on the determination, based on the Fourier analysis of the radio frequency signal, that the plasma asymmetry occurred in the reaction chamber.

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