System and method for simultaneously calibrating multiple RF generators

Abstract

Systems and methods for calibrating radio frequency (RF) generators are disclosed. One method includes receiving a plurality of analog measurement signals from a plurality of RF sensors and outputting a plurality of digital signals. The plurality of analog signals is received by an analysis controller. The method further includes simultaneously calibrating the RF generators based on the plurality of digital signals. The RF generators are calibrated by a processing controller.

Description

[Technical Field]

[0001] The present embodiments relate to a system and method for simultaneously calibrating multiple radio frequency (RF) generators. [Background technology]

[0002] Generally, in a plasma system, a radio frequency (RF) generator is coupled to a matching network, which is coupled to a plasma chamber. The RF generator generates an RF signal for processing a wafer in the plasma chamber and supplies the RF signal to the plasma chamber via the matching network. Furthermore, one or more process gases are supplied to the plasma chamber to generate a plasma for processing the wafer. During wafer processing, the RF generator preferably provides RF power of the RF signal according to a setpoint.

[0003] The background art provided herein is intended to provide a general background to the present disclosure, and the work of the inventors named herein, to the extent described in this background art, along with aspects of the description that would not normally be considered prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure. Summary of the Invention

[0004]

[0006] Embodiments of the present disclosure provide a system, apparatus, method, and computer program for simultaneously calibrating multiple radio frequency (RF) generators. It should be appreciated that the present embodiments can be embodied in various forms, such as a process, an apparatus, a system, a device, or a method recorded on a computer-readable medium. Some embodiments are described below.

[0005] In one embodiment, a system for calibrating an RF generator is described. The system includes a first RF generator connected to a first input of an impedance matching circuit via a first RF cable and a second RF generator connected to a second input of the impedance matching circuit via a second RF cable. The first input of the impedance matching circuit is connected to a first RF sensor. The second input of the impedance matching circuit is connected to the second RF sensor. The system further includes a processing controller and an analysis controller connected to the processing controller. The analysis controller is connected to the first and second RF sensors. The analysis controller receives a plurality of analog measurement signals from the first and second RF sensors and outputs a plurality of digital signals. The processing controller receives the digital signals and calibrates the first and second RF generators.

[0006] In one embodiment, a system for calibrating an RF generator is described. The system includes a first RF generator connected to a first input of a first impedance matching circuit via a first RF cable, a second RF generator connected to a second input of the first impedance matching circuit via a second RF cable, and a third RF generator connected to an input of the second impedance matching circuit via a third RF cable. The first input of the first impedance matching circuit is connected to a first RF sensor. The second input of the first impedance matching circuit is connected to the second RF sensor, and the input of the second impedance matching circuit is connected to the third RF sensor. The system further includes a processing controller and an analysis controller connected to the processing controller. The analysis controller is connected to the first, second, and third RF sensors. The analysis controller receives a plurality of analog measurement signals from the first, second, and third RF sensors and outputs a plurality of digital signals. The processing controller receives the plurality of digital signals and calibrates the first, second, and third RF generators.

[0007] In one embodiment, a method for calibrating RF generators (such as two RF generators or three RF generators) is described. The method includes receiving a plurality of analog measurement signals from a plurality of RF sensors and outputting a plurality of digital signals. The plurality of analog signals is received by an analysis controller. The method further includes simultaneously calibrating the RF generators based on the plurality of digital signals. The RF generators are calibrated by a processing controller.

[0008] In one embodiment, a method for determining an ideal amplitude value is described. The method includes determining an average frequency of one of a plurality of analog measurement signals. The average frequency is determined for a predetermined number of cycles of the one of the plurality of analog measurement signals. The method further includes determining, for a cycle of the one of the plurality of analog measurement signals, a time of occurrence of a first threshold crossing of the one of the plurality of analog measurement signals, the cycle occurring after the predetermined number of cycles. The method further includes determining a first phase of a first sample point based on the average frequency and the time of occurrence of the first threshold crossing. The first sample point is a first measurement value of the one of the plurality of analog measurement signals during a first half of the cycle. The method includes determining a first correction function from the first predetermined phase and the first phase, determining a first ideal amplitude value of the one of the plurality of analog measurement signals based on the first correction function, and controlling an RF generator based on the first ideal amplitude value.

[0009] In one embodiment, the systems and methods described herein can be utilized for any maximum, minimum, or amplitude measurement of any sinusoidal wave in a measurement signal. An accurate measurement of amplitude can be obtained from a few wave periods of the measurement signal. If the fundamental tone (periodicity) of the measurement signal is known from a few wave periods, the exact amplitude can be calculated by replacing the measured periodicity with an actual or predetermined periodicity that allows only a single period to occur in order to determine the exact maximum, minimum, or other amplitude by the end of a single period.

[0010] In one embodiment, the systems and methods described herein can be utilized to determine the maximum or minimum amplitude relative to an explicitly defined edge in any periodic signal (e.g., a measured signal) having an explicitly defined edge and an ideal phase. As an example, for any periodic signal, the maximum or minimum amplitude occurs at a phase that is specific to the explicitly periodic signal of interest. In that example, the phase is not 90° or 270°. Furthermore, in that example, for any periodic signal, the explicitly defined edge does not cross zero, but instead crosses a particular threshold (magnitude). As another example, for any periodic signal, the maximum amplitude occurs at the 90° phase and the minimum amplitude occurs at the 270° phase.

[0011] Advantages of the systems and methods described herein include calibrating multiple RF generators simultaneously (e.g., within the same period or time frame). The RF generators are connected to multiple RF sensors. Measurement information from the RF sensors is received by an analysis controller and converted from analog to digital format to output digital signals. The digital signals are provided to a process controller for analysis of the digital signals. The process controller calibrates the RF generators based on the digital signals. Calibrating the RF generators within the same period saves time compared to when the RF generators are calibrated sequentially. Furthermore, when the RF generators are calibrated simultaneously, the RF generators are connected to the plasma chamber via one or more impedance matching networks. Therefore, any malfunctions in the plasma chamber, the RF generators, and the plasma tool components having the impedance matching networks can be determined simultaneously.

[0012] Further advantages of the systems and methods described herein include correcting a first amplitude (e.g., a maximum amplitude) and a second amplitude (e.g., a minimum amplitude) of the measurement signal based on information provided by a single cycle of the measurement signal. Once the average frequency of the measurement signal is determined, the phase within the single cycle at which the first amplitude occurs and the phase within the single cycle at which the second amplitude occurs are determined. These phases are compared to corresponding ideal phases to determine first and second phase correction functions. A first ideal amplitude value (e.g., an ideal maximum amplitude) is determined as a sample in the sum of the phase at which the first amplitude occurs and the first correction function. A second ideal amplitude value (e.g., an ideal minimum amplitude) is determined as a sample in the sum of the phase at which the second amplitude occurs and the second correction function. Instead of the first and second amplitudes, the first and second ideal amplitude values are provided to a processing controller to calibrate the RF generator within the same period. Therefore, applying information within a single cycle to correct the first and second amplitudes saves time.

[0013] Additional advantages of the systems and methods described herein include reduced time for simultaneously calibrating RF generators. Simultaneous calibration, in which the RF generators are operated together within the same time period (e.g., simultaneously), utilizes a short time window for calibrating the RF generators. Furthermore, further time savings are achieved by determining the first and second ideal amplitude values from a single periodic wave of the measurement signal. Note that a method for determining the first and second ideal amplitude values over a minimum number of periods of the periodic signal enables measurement of the behavior of a first one of the RF generators within a small number of periods of the measurement signal associated with a second one of the RF generators. If determining the first and second ideal amplitude values requires a large number of periods of the periodic signal associated with the first one of the RF generators, it would be difficult to determine the behavior of a first one of the RF generators within a small number of periods of a second one of the RF generators.

[0014] Other aspects will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0015] The embodiments can be best understood by referring to the following description taken in conjunction with the accompanying drawings.

[0016] [Figure 1] FIG. 1 illustrates one embodiment of a system for calibrating a radio frequency (RF) generator.

[0017] [Figure 2] 1 is a graph illustrating a method for calibrating one or more RF generators.

[0018] [Figure 3] FIG. 2 is a diagram of one embodiment of a system illustrating removal of a sensor from the system of FIG. 1 after calibrating the RF generator of the system.

[0019] [Figure 4] Analysis: A graph illustrating analysis by a processor of a processing controller of measurement information in a plurality of digital signals received from the controller.

[0020] [Figure 5] 2 is a diagram of an embodiment of a system illustrating that calibration of an RF generator takes longer than calibration of the RF generator of the system of FIG. 1 within a given period of time.

[0021] [Figure 6] A graph of the measured signal showing how the average frequency is calculated.

[0022] [Figure 7] FIG. 1 illustrates a method for determining the ideal maximum and minimum amplitudes of a measurement signal to compensate for errors introduced by an analog-to-digital converter (ADC) of an analysis controller when converting the measurement signal from analog to digital form. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following embodiments describe systems and methods for simultaneously calibrating multiple radio frequency (RF) generators. It will be apparent that the embodiments may be practiced without some or all of these specific details. Furthermore, detailed descriptions of well-known operations have been omitted to avoid unnecessarily obscuring the embodiments.

[0024] 1 illustrates one embodiment of a system 100 for simultaneously calibrating RF generators 102, 104, and 106. System 100 may be referred to herein as a plasma system or a plasma tool. System 100 includes RF generators 102, 104, and 106, an analysis controller 108, a matcher 110, a matcher 112, a plasma chamber 114, a process controller 116, RF sensors 118, 120, and 122, and a voltage sensor 124. By way of example, matcher 110 has a housing separate from the housing of matcher 112.

[0025] Each of the RF generators 102 and 106 operates at a low frequency (LF). Examples of low frequencies include frequencies in the range of 400 kilohertz (kHz) to 2 megahertz (MHz), inclusive. For example, a low frequency is a baseline or fundamental frequency of 400 kHz. Furthermore, the RF generator 104 operates at a high frequency (HF). Examples of high frequencies include frequencies in the range of 60 megahertz (MHz) to 120 MHz, inclusive. For example, a high frequency is a baseline or fundamental frequency of 60 MHz or 100 MHz. A high frequency is greater than a low frequency. For example, a low frequency is 400 kHz, and a high frequency is 60 MHz. Note that each of the RF generators 102 and 104 may be referred to herein as an LF RF generator, and the RF generator 106 may be referred to herein as an HF RF generator.

[0026] As an example, the analysis controller 108 includes an analog-to-digital converter (ADC), a processor, and a memory device. The ADC is connected to the processor of the analysis controller 108, and the processor is connected to the memory device of the analysis controller 108. As an example, the processor used herein may be an application-specific integrated circuit (ASIC), a central processing unit (CPU) of the analysis controller 108, a field-programmable gate array (FPGA), a programmable logic device (PLD), an integrated controller, or a microcontroller. Examples of memory devices used herein include read-only memory (ROM) and random-access memory (RAM). For example, the memory device is flash memory or a redundant array of independent disks (RAID). Further, as an example, the processing controller 116 includes a processor and a memory device. The processor of the processing controller 116 is connected to the memory device of the processing controller 116.

[0027] Examples of matchers include impedance matching circuits or impedance matching networks. For example, a matcher is a series of circuit components (such as capacitors, inductors, and resistors). The circuit components are coupled to each other. For example, two of the circuit components are coupled to each other in series or parallel.

[0028] Examples of RF sensors used herein include power meters or power sensors. For example, a power meter measures forward power and reverse power. Furthermore, for example, the forward power of an RF signal generated by an RF generator is the power supplied by the RF generator to the plasma chamber 114 through a matcher, and the reverse power is the power reflected from the plasma chamber 114 to the RF generator through the matcher. The reverse power is also referred to herein as reflected power.

[0029] The plasma chamber 114 includes a substrate support 126 (e.g., an electrostatic chuck (ESC)). The plasma chamber 114 further includes an upper electrode 128 disposed above the substrate support 126 such that a gap 130 is formed between the upper electrode 128 and the substrate support 126. The upper electrode 128 faces toward the substrate support 126. A lower electrode 132 is embedded within the substrate support 126, which is made of a metal (e.g., aluminum or an aluminum alloy) and a ceramic (e.g., aluminum oxide (Al2O3)). The upper electrode 128 is made of metal and is connected to ground potential.

[0030] The plasma chamber 114 further includes an edge ring 134 (e.g., an adjustable edge sheath (TES) ring), which surrounds the substrate support 126. By way of example, the edge ring 134 is fabricated from a conductive material, such as silicon, boron-doped single crystal silicon, silicon carbide, an alloy of silicon, or a combination thereof. Note that the edge ring 134 has an annular body (e.g., a circular body, a ring-shaped body, or a dish-shaped body). For example, the edge ring 134 has an inner radius and an outer radius, and the inner radius is larger than the radius of the substrate support 126. One example of a plasma chamber 114 is a capacitively coupled plasma (CCP) chamber.

[0031] RF generator 102 is connected to input I1 of matcher 110 via RF cable 136 and RF sensor 118, RF generator 104 is connected to input I2 of matcher 110 via another RF cable 138 and RF sensor 120, and RF generator 106 is connected to input I11 of matcher 112 via RF cable 140 and RF sensor 122. RF sensor 118 is connected to input I1, RF sensor 120 is connected to input I2, and RF sensor 122 is connected to input I11. For example, during a given period when two or more of RF generators 102, 104, and 106 are being calibrated simultaneously, RF sensor 118 remains connected to the first port of matcher 110 to which RF cable 136 is connected, RF sensor 120 remains connected to the second port of matcher 110 to which RF cable 138 is connected, and RF sensor 122 remains connected to the port of matcher 112 to which RF cable 140 is connected. In this example, RF sensor 120 is not connected to matcher 110 after RF sensor 118 is disconnected from matcher 110. Also, in this example, RF sensor 122 is not connected to matcher 112 after RF sensor 120 is disconnected from matcher 110. Rather, in this example, RF sensors 118, 120, and 122 remain coupled to matchers 110 and 112 within the same predetermined period. An example of an input is a port. Output O1 of matcher 110 is connected to lower electrode 132 via RF transmission line 142, and output O11 of matcher 112 is connected to edge ring 134 via RF transmission line 144.

[0032] An example of an RF transmission line includes an RF rod surrounded by an RF tunnel with an insulator between the RF rod and the RF tunnel. Another example of an RF transmission line includes a combination of one or more RF straps, an RF rod, and an RF tunnel. In this example, the one or more RF straps are coupled to the RF rod.

[0033] The ports of each of the RF sensors 118-122 are connected to the analysis controller 108 via respective transfer cables. For example, the first port of the RF sensor 118 is connected to channel 1 of the analysis controller 108 via transfer cable TC1, and the second port of the RF sensor 118 is connected to channel 2 of the analysis controller 108 via transfer cable TC2. Also, in this example, the first port of the RF sensor 120 is connected to channel 3 of the analysis controller 108 via transfer cable TC3, and the second port of the RF sensor 120 is connected to channel 4 of the analysis controller 108 via transfer cable TC4. Also, in this example, the first port of the RF sensor 122 is connected to channel 5 of the analysis controller 108 via transfer cable TC5, and the second port of the RF sensor 122 is connected to channel 6 of the analysis controller 108 via transfer cable TC6. Examples of transfer cables include cables that transfer analog signals in parallel, serially, or using the Universal Serial Bus (USB) protocol.

[0034] Voltage sensor 124 is connected to channel 7 of analysis controller 108 via transfer cable TC7. Analysis controller 108 has channel 8, which is connected to LF RF generator 106 via transfer cable TC8. Analysis controller 108 sends transistor-transistor logic (TTL) signals (such as clock signals) to LF RF generator 106 via transfer cable TC8. The processor of analysis controller 108 is also connected to the processor of process controller 116 via transfer cable 146. Process controller 116 is connected to LF RF generator 102 via transfer cable 148. Process controller 118 is also connected to HF RF generator 104 via transfer cable 150 and to LF RF generator 106 via transfer cable 152.

[0035] No substrate is disposed on the upper surface of the substrate support 126. An example of a substrate includes a semiconductor wafer. The processor of the process controller 116 generates and transmits a recipe signal 154 to the LF RF generator 102 via the transfer cable 148. By way of example, the recipe signal transmitted to the RF generator includes a power level and a frequency level for the RF generator's operation. Each power level includes one or more RF power values. Similarly, the processor of the process controller 116 generates and transmits a recipe signal 156 to the HF RF generator 104 via the transfer cable 150 and a recipe signal 158 to the LF RF generator 106 via the transfer cable 152. A digital signal processor (DSP) in each of the RF generators 102, 104, and 106 stores information received in each of the recipe signals 154, 156, and 158 (e.g., the respective power level and the respective frequency level) in the RF generator's respective memory device. Additionally, the processor of the processing controller 116 transmits trigger signals to each of the RF generators 102, 104, and 106 via transmission cables 148, 150, and 152, respectively.

[0036] Upon receiving the trigger signal, each RF generator 102, 104, and 106 generates a respective RF signal according to information in a respective recipe signal received from process controller 116. For example, RF generator 102 generates RF signal 160 having a power level and frequency level received in recipe signal 154, RF generator 104 generates RF signal 162 having a power level and frequency level received in recipe signal 156, and RF generator 106 generates RF signal 164 having a power level and frequency level received in recipe signal 158. Note that RF signals 160-164 are generated simultaneously, not sequentially, to facilitate simultaneous calibration of RF generators 102-106.

[0037] Matching network 110 receives RF signals 160 and 162 and modulates the impedance of RF signals 160 and 162 by matching the impedance of a load connected to output O1 with the impedance of multiple sources connected to inputs I1 and I2. Examples of sources connected to inputs I1 and I2 include RF cables 136 and 138 and RF generators 102 and 104. Examples of loads connected to output O1 include RF transmission line 142 and plasma chamber 114. Additionally, the impedance of RF signals 160 and 162 is modulated to output modulated RF signal 166. Modulated RF signal 166 is transmitted from output O1 to lower electrode 132.

[0038] Similarly, matcher 112 receives RF signal 164 and modulates the impedance of RF signal 164 by matching the impedance of a load connected to output O11 with the impedance of a source connected to input I11. Examples of sources connected to input I11 include RF cable 140 and RF generator 106, and examples of loads connected to output O11 include RF transmission line 144 and plasma chamber 114. The impedance of RF signal 164 is modulated to output modulated RF signal 168. Modulated RF signal 168 is transmitted from output O11 to edge ring 134. For example, modulated RF signals 166 and 168 are simultaneously received by plasma chamber 114 to facilitate simultaneous calibration of RF generators 102-106.

[0039] When RF signals 160, 162, and 164 are simultaneously supplied to matchers 110 and 112, RF sensors 118, 120, and 122 each measure the forward power and reverse power, output a respective measurement signal, and transmit the measurement signal to the processor of analysis controller 108. For example, RF sensor 118 measures the forward power at input I1 and outputs a measurement signal MS2, measures the reverse power at input I1 and outputs a measurement signal MS1, transmits measurement signal MS1 to the processor of analysis controller 108 via transfer cable TC1 and channel 1, and transmits measurement signal MS2 to the processor of analysis controller 108 via transfer cable TC2 and channel 2. In this example, RF sensor 120 measures forward power at input I2 and outputs measurement signal MS4, measures reverse power at input I2 and outputs measurement signal MS3, transmits measurement signal MS3 to the processor of analysis controller 108 via transfer cable TC3 and channel 3, and transmits measurement signal MS4 to the processor of analysis controller 108 via transfer cable TC4 and channel 4. Further in this example, RF sensor 122 measures forward power at input I11 and outputs measurement signal MS6, measures reverse power at input I11 and outputs measurement signal MS5, transmits measurement signal MS5 to the processor of analysis controller 108 via transfer cable TC5 and channel 5, and transmits measurement signal MS6 to the processor of analysis controller 108 via transfer cable TC6 and channel 6. Further in this example, voltage sensor 124 measures voltage at output O1 and outputs measurement signal MS7, and transmits measurement signal MS7 to the processor of analysis controller 108 via transfer cable TC7 and channel 7. For example, measurement signals MS1-MS7 are simultaneously transmitted from RF sensors 118-122 and voltage sensor 124 to analysis controller 108.

[0040] The ADC of the analysis controller 108 receives the measurement signals MS1-MS7 received via channels 1-7, converts each of the measurement signals MS1-MS7 from analog format to digital format, and outputs a plurality of digital signals 147. For example, the digital signals include a first digital signal generated based on the measurement signal MS1, a second digital signal generated based on the measurement signal MS2, a third digital signal generated based on the measurement signal MS3, a fourth digital signal generated based on the measurement signal MS4, a fifth digital signal generated based on the measurement signal MS5, a sixth digital signal generated based on the measurement signal MS6, and a seventh digital signal generated based on the measurement signal MS7. For example, the ADC simultaneously converts the measurement signals MS1-MS7 from analog format to digital format. Furthermore, for example, the ADC applies time division multiplexing to convert the measurement signals MS1-MS7 from analog format to digital format. Furthermore, for example, the ADC converts a first portion of measurement signal MS1, then converts a first portion of measurement signal MS3, then converts a second portion of measurement signal MS1, and then converts a second portion of measurement signal MS3. As an example, the processor of analysis controller 108 stores correspondence information in a memory device of analysis controller 108. For example, the processor of analysis controller 108 stores, in the memory device of analysis controller 108, a one-to-one correspondence between each digital power value of measurement signals MS1-MS7 and the time at which the digital power value was output from the ADC.

[0041] The ADC also stores measurement signals MS1-MS7 in a memory device of analysis controller 108. Furthermore, the processor of analysis controller 108 determines, based on the clock signal, the time at which each power value in each of measurement signals MS1-MS7 was received from sensors 118-124. Digital signal 147 includes measured information (e.g., the forward and reverse power indicated by measurement signals MS1-MS6 and the voltage indicated by measurement signal MS7). An example of forward power includes multiple forward power levels, and an example of reverse power includes multiple reverse power levels. The ADC transmits digital signal 147 to analysis controller 108.

[0042] The processor of analysis controller 108 indicates, based on the channel, which combination of digital signals 147 was received from each input of the matcher. For example, if the processor of analysis controller 108 determines that measurement signals MS1 and MS2 were received from channels C1 and C2, it includes an identifier for input I1 of matcher 110 in the set of digital signals 147 output based on measurement signals MS1 and MS2. In this example, if the processor of analysis controller 108 determines that measurement signals MS3 and MS4 were received from channels C3 and C4, it includes an identifier for input I2 of matcher 110 in the set of digital signals 147 output based on measurement signals MS3 and MS4. Furthermore, in this example, if the processor of analysis controller 108 determines that measurement signals MS5 and MS6 were received from channels C5 and C6, it includes an identifier for input I11 of matcher 112 in the set of digital signals 147 output based on measurement signals MS5 and MS6. Also in this example, when the processor of analysis controller 108 determines that measurement signal MS7 is received from channel C7, it includes an identifier of output O1 of matcher 110 in one of digital signals 147 output based on measurement signal MS7. An indication of the respective input or respective output of a matcher (such as matcher 110 or 112) is an example of matcher information.

[0043] The processor of analysis controller 108 transmits digital signals 147 having identifiers of inputs I1, I2, and I11 and output O1 to the processor of processing controller 116 via transfer cable 146. For example, digital signals 147 are transmitted within a predetermined time range (e.g., simultaneously or substantially simultaneously) to facilitate calibration of two or more of RF generators 102, 104, and 106 within a predetermined time window. The processor of processing controller 116 receives digital signals 147, stores the measurement information and matcher information represented by digital signals 147 in a memory device of processing controller 116, and determines whether to calibrate two or more of RF generators 102-106 within the predetermined time period based on the identifiers I1, I2, I11, and O1. For example, the processor of processing controller 116 receives digital signals 147 from analysis controller 108 simultaneously or substantially simultaneously. In this example, the processor of the processing controller 116 identifies that the input I1 is connected to the LF RF generator 102 based on the identifier of the input I1 received in the digital signal 147. In this example, the processor retrieves the correspondence between the input I1 and the LF RF generator 102 from a memory device of the processing controller 116. Furthermore, in this example, the processor calculates the transmitted power from the forward power and reverse power at the input I1 and determines whether the transmitted power meets a first predetermined threshold (e.g., a range of power values). For example, the processor calculates the transmitted power as the difference between the forward power and the reverse power. In this example, if the processor compares the transmitted power with the first predetermined threshold and determines that the transmitted power is less than the first predetermined threshold, the processor controls the RF generator 102 to increase the supplied power of the RF signal 160 to calibrate the RF generator 102 until the transmitted power is within the first predetermined threshold. For example, to control the RF generator 102, the processor increases the power level previously transmitted in the recipe signal 154 to output the increased power level and transmits the increased power level in the recipe signal RS1 to the LF RF generator 102 via the transfer cable 148.In this example, on the other hand, if the processor compares the transmitted power to the first predetermined threshold and determines that the transmitted power is greater than the first predetermined threshold, the processor controls RF generator 102 to decrease the supplied power of RF signal 160 to calibrate RF generator 102 until the transmitted power is within the first predetermined threshold. For example, the processor decreases the power level previously transmitted in recipe signal 154 to output the decreased power level and transmits the decreased power level in recipe signal RS1 to LF RF generator 102 via transfer cable 148.

[0044] Continuing with this example, the processor of the processing controller 116 identifies that input I2 is connected to the HF RF generator 104 based on the identifier of input I2 received in digital signal 147. In this example, the processor retrieves the mapping between input I2 and the HF RF generator 104 from a memory device of the processing controller 116. Further, in this example, the processor calculates the transmitted power from the forward power and reverse power at input I2 and determines whether the transmitted power meets a second predetermined threshold. In this example, the processor compares the transmitted power with the second predetermined threshold and, upon determining that the transmitted power is less than the second predetermined threshold, controls the HF RF generator 104 to increase the supplied power of RF signal 162 to calibrate the HF RF generator 104. For example, to control the HF RF generator 104, the processor increases the power level previously transmitted in recipe signal 156 to output the increased power level and transmits the increased power level in recipe signal RS2 to the HF RF generator 104 via transfer cable 150.

[0045] Further, in this example, the processor of the process controller 116 identifies that the input I11 is connected to the LF RF generator 106 based on the identifier of the input I11 received in the digital signal 147. In this example, the processor obtains the correspondence between the input I11 and the LF RF generator 106 from the memory device of the process controller 116. Also, in this example, the processor calculates the transmitted power from the forward power and reverse power at the input I11 and determines whether the transmitted power meets a third predetermined threshold. In this example, the processor compares the transmitted power with the third predetermined threshold and, if it determines that the transmitted power is less than the third predetermined threshold, controls the LF RF generator 106 to increase the supplied power of the RF signal 164 to calibrate the LF RF generator 106. For example, to control the LF RF generator 106, the processor increases the power level previously transmitted in the recipe signal 158 to output the increased power level and transmits the increased power level in the recipe signal RS3 to the LF RF generator 106 via the transfer cable 152. In this example, the processor transmits recipe signals RS1-RS3 to RF generators 102-106 within a predetermined time window to simultaneously (e.g., within a predetermined time period) calibrate RF generators 102-106. For example, recipe signals RS1-RS3 are transmitted simultaneously or substantially simultaneously. Further, for example, recipe signal RS2 or RS3 is transmitted within 1-10 nanoseconds before or after transmitting recipe signal RS1.

[0046] In this example, the processor analyzes the first through seventh digital signals within a predetermined time window to facilitate calibration of RF generators 102 through 106 within a predetermined period of time. For example, the processor identifies identities of inputs I1, I2, and I11, calculates transmitted power from the forward and reverse power at inputs I1, I2, and I11, determines whether the transmitted power meets first, second, and third predetermined thresholds, and controls RF generators 102, 104, and 106 based on the determination within the predetermined time frame.

[0047] In this example, the DSP of each of RF generators 102-106 stores a respective recipe signal RS1-RS3 in the RF generator's respective memory device. For example, the DSP of RF generator 102 receives recipe signal RS1 and stores the increased or decreased power level received in recipe signal RS1 in the memory device of RF generator 102, the DSP of RF generator 104 receives recipe signal RS2 and stores the increased or decreased power level received in recipe signal RS2 in the memory device of RF generator 104, and the DSP of RF generator 106 receives recipe signal RS3 and stores the increased or decreased power level received in recipe signal RS3 in the memory device of RF generator 106. Further, in this example, upon receiving a trigger signal, each of RF generators 102-106 increases or decreases the respective power level of its respective RF signal 160, 162, or 164 to the respective increased or decreased power level. In this manner, RF generators 102-104 are calibrated simultaneously (eg, within a predetermined period of time) when RF signals 160, 162, and 164 are being generated simultaneously.

[0048] Receipt of digital signal 147 facilitates determination of one or more malfunctions in one or more components within system 100. For example, one or more malfunctions in any component of system 100 may be determined within a predetermined time period (e.g., simultaneously). For example, upon determining that the transmitted power of RF signal 164 is less than a third predetermined threshold and the transmitted power of RF signal 162 is less than a second predetermined threshold, the processor of process controller 116 may determine that either edge ring 134 or LF RF generator 106, or a combination thereof, is malfunctioning, or either HF RF generator 104 or substrate support 126, or a combination thereof, is malfunctioning. As another example, if the processor of the process controller 116 determines that the transmitted power of RF signal 164 is less than a third predetermined threshold, the transmitted power of RF signal 162 is less than a second predetermined threshold, and the transmitted power of RF signal 160 is less than a first predetermined threshold, the processor of the process controller 116 determines that the edge ring 134 or the LF RF generator 106, or a combination thereof, is faulty, the HF RF generator 104 or the substrate support 126, or a combination thereof, is faulty, or the LF RF generator 102 or the substrate support 126, or a combination thereof, is faulty. As yet another example, a failure in two or more of the RF generators 102, 104, and 106 is determined simultaneously. For example, if the processor of the process controller 116 determines that the transmitted power of RF signal 160 is less than a first predetermined threshold, the transmitted power of RF signal 162 is less than a second predetermined threshold, and the transmitted power of RF signal 164 is less than a third predetermined threshold, the processor of the process controller 116 determines that all of the RF generators 102, 104, and 106 are faulty.

[0049] In one embodiment, if the comparison indicates that the transmitted power generated from measurement signals MS1 and MS2 does not meet a first predetermined threshold, the processor controls RF generator 102, RF generator 104, and / or RF generator 106 until the first predetermined threshold is met. Similarly, in that embodiment, if the comparison indicates that the transmitted power generated from measurement signals MS3 and MS4 does not meet a second predetermined threshold, the processor controls RF generator 102, RF generator 104, and / or RF generator 106 until the second predetermined threshold is met. Also, in that embodiment, if the comparison indicates that the transmitted power generated from measurement signals MS5 and MS6 does not meet a third predetermined threshold, the processor controls RF generator 102, RF generator 104, and / or RF generator 106 until the third predetermined threshold is met.

[0050] In one embodiment, the processor of analysis controller 108 sends a TTL signal to LF RF generator 102 via a transfer cable (not shown) and a TTL signal to HF RF generator 104 via another transfer cable (not shown) to synchronize the operation of RF generators 102, 104, and 106. Additionally, the processor of analysis controller 108 sends a TTL signal to the processor of treatment controller 116 via transfer cable 146 (FIG. 1).

[0051] In one embodiment, instead of placing a substrate, a dummy substrate (such as a glass plate) is placed on top of the substrate support 126 .

[0052] In one embodiment, instead of the two LF RF generators 102 and 106 and the HF RF generator 104, a single LF RF generator is used and two HF RF generators are used.

[0053] In one embodiment, two RF generators are used instead of two LF RF generators 102 and 106 and HF RF generator 104. For example, system 100 includes LF RF generators 102 and 106 without HF RF generator 104. As another example, system 100 includes LF RF generator 102 and HF RF generator 104 without LF RF generator 106. As yet another example, system 100 includes LF RF generator 106 and HF RF generator 104 without LF RF generator 102. The methods described herein apply to these two RF generators.

[0054] In one embodiment, in addition to the two LF RF generators 102 and 106 and the HF RF generator 104, one or more additional RF generators are used in the system 100. For example, in addition to the LF RF generator 106, an HF RF generator is connected to another input of the matcher 112. An RF sensor (such as RF sensor 122) is also coupled to another input of the matcher 112. The methods described herein apply to the LF RF generators 102 and 106, the HF RF generator 104, and the one or more additional RF generators.

[0055] In one embodiment, in addition to the LF RF generator 102 and the HF RF generator 104, an intermediate frequency (MF) RF generator is coupled to the input of the matcher 110. Examples of MF RF generators are generators with operating frequencies (e.g., fundamental frequencies) of 13.56 MHz or 27 MHz.

[0056] In one embodiment, a voltage or current sensor is used instead of a power meter.

[0057] 2 is a graph 200 illustrating a method for calibrating an RF generator, such as RF generators 102, 104, or 106 (FIG. 1), or a combination thereof. Graph 200 plots the power level of an RF signal provided by the RF generator versus time t. The power level is plotted on the y-axis and time t is plotted on the x-axis.

[0058] The power levels range from a value P0 to a value P10, and the time t ranges from a time t0 to a time t30. The power levels increase from a value P0 to a value P10, and the time t progresses from a time t0 to a time t30. The graph 200 includes a plot of a predicted envelope 202 and another plot of a measured envelope 204. Examples of an envelope as used herein are peak-to-peak amplitude or zero-to-peak amplitude.

[0059] A predetermined range from predicted envelope 202 is an example of a first, second, or third predetermined threshold. For example, if plot 202 represents predicted transmitted power from LF RF generator 102 and plot 204 represents transmitted power calculated from measurement signals MS1 and MS2, a first predetermined range from predicted envelope 202 is an example of a first predetermined threshold. As another example, if predicted plot 202 represents predicted transmitted power from HF RF generator 104 and plot 204 represents transmitted power calculated from measurement signals MS3 and MS4, a second predetermined range from predicted envelope 202 is an example of a second predetermined threshold. As yet another example, if predicted envelope 202 represents predicted transmitted power from LF RF generator 106 and plot 204 represents transmitted power calculated from measurement signals MS5 and MS6, a third predetermined range from predicted envelope 202 is an example of a third predetermined threshold.

[0060] The processor of the process controller 116 stores the multiple values of the predicted envelope 202 in a memory device of the process controller 116. For example, a correspondence (e.g., a one-to-one relationship) between each value of the predicted envelope 202 and each of the times t0 to t20 during each cycle of the clock signal is stored. The cycles of the clock signal include cycle n and cycle (n+1), where n is an integer greater than zero.

[0061] During each cycle of the clock signal, the processing controller 116 receives the measurement signals MS1 and MS2 and calculates the measured transmitted power from the measurement signals MS1 and MS2. For example, the measured transmitted power is the difference between the measurement signals MS2 and MS1. An example of the measured transmitted power is shown as the measurement envelope 204.

[0062] The processor of the process controller 116 compares one or more values of the measured envelope 204 to one or more values of the predicted envelope 202 for one or more of times t0-t20 to determine whether the measured envelope 204 meets a predetermined threshold (e.g., a first predetermined threshold, a second predetermined threshold, or a third predetermined threshold). For example, the processor of the process controller 116 compares the value of the measured envelope 204 at time t1 to the value of the predicted envelope 202 at time t1 to determine whether the value of the measured envelope 204 is greater than or less than the predetermined threshold. In this example, upon determining that the value of the measured envelope 204 is greater than the value of the predicted envelope 202, the processor of the process controller 116 controls the RF generator to increase the power provided by the RF generator until the value of the measured envelope 204 is within a predetermined range (e.g., matches the value of the predicted envelope 202 or is within a predetermined percentage of the value of the predicted envelope 202). In this manner, the processor of the processing controller 116 calibrates one or more of the RF generators 102-106.

[0063] In one embodiment, the processor of the processing controller 116 receives the digital signal 147 and concatenates the sample values of the digital signal 147 to generate the measurement envelope 204 .

[0064] 3 is a diagram of an embodiment of system 300 illustrating the removal of RF sensors 118-122 ( FIG. 1 ) and voltage sensor 124 ( FIG. 1 ) from system 100 after calibrating RF generators 102-106. System 300 includes the same components as system 100, except that system 300 does not include RF sensors 118, 120, and 122 and voltage sensor 124. For example, during processing of a substrate in plasma chamber 114 ( FIG. 1 ), RF cable 136 is connected to input I1 without being connected to RF sensor 118. Also, in this example, RF cable 138 is connected to input I2 without being connected to RF sensor 120, and RF cable 140 is connected to input I11 without being connected to RF sensor 122. For example, RF cable 136 is connected directly to input I1 without being connected to input I1 via RF sensor 118. As another example, RF sensor 118 is decoupled (e.g., disconnected) from input I1 to be removed from system 100. Furthermore, in this example, output O1 is connected to lower electrode 132 (FIG. 1) via RF transmission line 142 without being connected to voltage sensor 124. Note that system 300 includes analysis controller 108; for example, analysis controller 108 is connected to process controller 116.

[0065] 4 is a graph 400 illustrating analysis by a processor of the process controller 116 (FIG. 1) of measurement information in the digital signal 147 received from the analysis controller 108. The measurement information is analyzed for a predetermined time window 402. Additionally, the measurement information is analyzed by the processor of the process controller 116 after calibrating two or more of the RF generators 102-106 for a predetermined period of time. For example, the measurement information may be analyzed before processing the substrate S for recipe formation or while processing the substrate S for fault detection. The recipe information is the generation of recipe signals (e.g., recipe signals RS1-RS3) by the processor of the process controller 116. Graph 400 is the same as graph 200, except that in graph 400, plots 202 and 204 are shown for the predetermined time window 402. After two or more of the RF generators 102-106 (FIG. 1) have been calibrated within a predetermined period of time, and after the RF sensors 118-122 and the voltage sensor 124 (FIG. 1) have been removed from the system 100, the processor of the process controller 116 retrieves from the memory device of the process controller 116 a portion 404 of the predicted envelope 202 and a portion 406 of the measured envelope 204 corresponding to the predetermined time window 402 and compares the portion 404 to the portion 406 for modulating the recipe signals RS1-RS3 to achieve recipe formation or for fault detection within the system 300. For example, if the processor of the process controller 116 determines that one or more values of the portion 406 are not within a preset threshold (e.g., a preset range) from one or more values of the portion 404, the processor determines that one or more components of the system 300 (FIG. 3) are faulty. For example, the preset threshold is narrower than the predetermined range and closer to the portion 404. In the illustration, both the preset range and the predetermined range extend around portion 404 .

[0066] FIG. 5 is a diagram of an embodiment of a system 500 illustrating that calibration of an RF generator 502 takes longer than calibration of RF generators 102-106 (FIG. 1) within a given period of time. An example of the RF generator 502 is any of RF generators 102, 104, and 106 (FIG. 1). The system 500 includes the RF generator 502, a power measurement system 504, a 50 ohm load 506, and a host computer 508. An example of the 50 ohm load 506 is a combination of one or more resistors. For example, the 50 ohm load 506 is not a plasma chamber. Examples of the host computer 508 include a desktop computer, a laptop computer, a smartphone, and a tablet.

[0067] Power measurement system 504 includes a power meter 510 and an analysis controller 512. RF generator 502 is connected to power meter 510, which is connected to analysis controller 512. Power meter 510 is also connected to a 50 ohm load 506, which is connected to analysis controller 512. Host computer 508 is connected to RF generator 502. It should be noted that system 500 does not include a matcher (such as matcher 110 or matcher 112 (FIG. 1)).

[0068] RF generator 502 generates an RF signal 514 and provides the RF signal 514 to a power meter 510. Power meter 510 measures the transmitted power of RF signal 514 to generate an analog measurement and transmits the analog measurement to analysis controller 512. Analysis controller 512 converts the analog measurement from analog format to digital format and outputs a digital measurement that is transmitted to host computer 508.

[0069] The host computer 508 calibrates the RF generator 502 based on the digital measurements. After the RF generator 502 is calibrated, the RF generator 502 is disconnected from the power meter 510 and the host computer 508, and another RF generator (not shown) is connected in place of the RF generator 502. The other RF generator (not shown) is then calibrated in the same manner that the RF generator 502 was calibrated. Thus, the RF generator 502 and the other RF generators are calibrated sequentially rather than within a predetermined time period. This takes time. For example, it takes longer to calibrate the RF generators 102-106 sequentially than to calibrate them within a predetermined time period (e.g., simultaneously). Calibrating the RF generators 102-106 within a predetermined time period rather than sequentially saves time. Additionally, because the system 500 does not utilize a matching box, a malfunction in the matching box will not be detected during the calibration of the RF generator 502 or the other RF generators (not shown). Furthermore, because the system 500 utilizes a 50 ohm load 506 in place of the plasma chamber 114 (FIG. 1), any failure of any component of the plasma chamber 114 will not be detected based on analog measurements received from the power meter 510.

[0070] Figure 6 shows the average frequency f av Graph 600 illustrates how the power (e.g., forward power, reflected power, or transmitted power) of an RF generator (e.g., RF generator 102, 104, or 106 (FIG. 1)) is calculated. Graph 600 plots power (e.g., forward power, reflected power, or transmitted power) of an RF generator (e.g., RF generator 102, 104, or 106 (FIG. 1)) on the y-axis and time t on the x-axis. Time t ranges from time t0 to time t2. As an example, time t on graph 600 indicates the time when a power value of measurement signal 602 is received by analysis controller 108 (FIG. 1) from any of sensors 118, 120, or 122 (FIG. 1). The power plotted on graph 600 ranges from a power value Pb to a power value Pa. The power values on graph 600 increase from Pb to Pa. For example, power value Pa is greater than power value Po, which is greater than power value Pb. An example power value Po is a positive power value. Also, in this example, the power value Pa is a positive power value, and the power value Pb is a positive power value.

[0071] A period (e.g., from time t0 to time t2) lasts for a predetermined number of cycles of the measurement signal 602. Examples of the measurement signal 602 include measurement signals MS1 or MS2 or MS3 or MS4 or MS5 or MS6 (FIG. 1). Another example of the measurement signal 600 is a transmitted power signal calculated from the set of measurement signals MS2 and MS1, or the set of measurement signals MS4 and MS3, or the set of measurement signals MS6 and MS5. Examples of the predetermined number of cycles of the measurement signal 602 include two or more cycles of the measurement signal 602 (e.g., cycle 1 and cycle 2). For example, the predetermined number of cycles includes 5, 7, 10, or 20 cycles of the measurement signal 602.

[0072] As shown in graph 600, the measurement signal 602 is a sinusoid that repeats during each cycle of the measurement signal 602. For example, during cycle 1 of the measurement signal 602, the measurement signal 602 has a power value P0 at time t0, reaches a power value Pa at time t0.25, reaches a power value P0 at time t0.5, reaches a power value Pb at time t0.75, and reaches a power value P0 at time t1. In this example, the measurement signal 602 repeats through power values P0, Pa, P0, Pb, and P0 during cycle 2 of the measurement signal 602.

[0073] The processor of analysis controller 108 receives measurement information (such as power values P0, Pa, P0, Pb, and P0) in each cycle of measurement signal 602. The processor of analysis controller 108 determines the time at which power value P0 was output by the ADC of analysis controller 108 from power values P0, Pa, P0, Pb, and P0 to determine the frequency of measurement signal 602 for each of a predetermined number of cycles of measurement signal 602, and further determines the average frequency of measurement signal 600 from the frequency over the predetermined number of cycles of measurement signal 602. For example, the processor of analysis controller 108 identifies the output from the ADC at times t0, t0.5, and t1 during cycle 1 of measurement signal 602. Furthermore, in this example, the processor of analysis controller 108 determines that a positive threshold crossing of measurement signal 600 occurred at each of times t0 and t1 when the power value was P0 during cycle 1 of measurement signal 602. For example, the processor of analysis controller 108 determines that a positive threshold crossing occurred if the power value output from the ADC of analysis controller 108 before power value P0 is less than power value P0 and the power value output from the ADC of analysis controller 108 immediately after power value P0 is greater than power value P0. Further, in this example, the processor of analysis controller 108 identifies that power value P0 was output by the ADC at each of times t1, t1.5, and t2, and further determines that a positive threshold crossing occurred at each of times t1 and t2 during cycle 2. Further, in this example, the processor of analysis controller 108 calculates the inverse of the difference between the times t1 and t0 at which the positive threshold crossings occurred during cycle 1 of measurement signal 602 to determine a first frequency of measurement signal 600 for cycle 1 of measurement signal 600. In this example, the processor of analysis controller 108 further calculates the inverse of the difference between times t2 and t1 when a positive threshold crossing occurred during cycle 2 of measurement signal 602 to determine a second frequency of measurement signal 600 for cycle 2 of measurement signal 600. Also in this example, the processor of analysis controller 108 calculates the average of the first and second frequencies to determine an average frequency for a predetermined number of cycles of measurement signal 602.

[0074] In one embodiment, instead of the measurement signal 602 being a sinusoidal signal, the measurement signal 602 is a periodic signal, e.g., the measurement signal 602 has another periodic shape.

[0075] FIG. 7 illustrates a method 700 for determining an ideal maximum amplitude and an ideal minimum amplitude of the measurement signal 602 using the average frequency. The ideal maximum amplitude is an example of an ideal amplitude value, and the ideal minimum amplitude is an example of an ideal amplitude value. The method 700 corrects for errors due to the ADC of the analysis controller 108 when converting the measurement signal 602 from analog to digital format. A graph 600 beginning at time t20 and ending at time t22 is shown in FIG. 7. Time t progresses from time t2 (FIG. 6) to time t20, and from time t20 to time t22. Note that the method 700 is performed during calibration of the RF generators 102, 106, and 108 within a predetermined period of time.

[0076] Method 700 is executed by a processor in analysis controller 108 (FIG. 1). The ADC in analysis controller 108 outputs multiple digital samples 702, 704, 706, 708, and 710 (which are sample values) of measurement signal 602 during the first half of cycle 20 of measurement signal 602. The first half of cycle 20 is the positive half of cycle 20. Cycle 20 occurs after a predetermined number of cycles of measurement signal 602. However, an error occurs in outputting digital sample 710. Instead of outputting the IdealMax sample, digital sample 710 is output from the ADC.

[0077] In method 700, the processor of analysis controller 108 determines time t20 as the time at which a positive threshold crossing occurs. For example, the processor of analysis controller 108 determines that a positive threshold crossing occurred if the power value output from the ADC of analysis controller 108 before power value P0 is less than power value P0 and the power value output from the ADC immediately after power value P0 is greater than power value P0. Further, in this example, the processor of analysis controller 108 identifies from the mapping information that power value P0 was output from the ADC at time t20 of the positive threshold crossing during cycle 20.

[0078] Continuing with the method 700, the processor of the analysis controller 108 calculates the phase Φ of the digital sample 710 having the maximum value during cycle 20. maxsample To determine the mean frequency f at the time t when a positive threshold crossing occurs, av For example, the processor of the analysis controller 108 determines from the digital samples output from the ADC during cycle 20 that the digital sample 710 has the maximum value or amplitude. In this example, the average frequency f av Based on this, the processor of analysis controller 108 calculates the distance from time t20, when a positive threshold crossing occurs during cycle 20, to time t20.5, when the digital sample 710 with the maximum amplitude is output from the ADC. Furthermore, in this example, time t20.5 corresponds to the phase Φ of digital sample 710. maxsample is.

[0079] Also in the method 700, the processor of the analysis controller 108 calculates the phase Φ of the digital samples 710. maxsample For example, the processor of analysis controller 108 identifies that ideally the maximum amplitude of measurement signal 602 occurs at a first predetermined phase (such as the 90° phase Φ90° or a first predefined phase). Further, in this example, the processor of analysis controller 108 determines the relationship between the first predetermined phase and the phase Φ of digital samples 710. maxsampleand calculate the absolute difference between the phase correction function Φcorrectionfunction1. In this example, the first preset phase is other than the 90° phase.

[0080] In the method 700, the processor of the analysis controller 108 calculates the phase Φ of the digital samples 710. maxsample and a sum of a phase correction function Φcorrectionfunction1. Further in the method 700, the processor of the analysis controller 108 determines an ideal maximum amplitude IdealMax of the measurement signal 602 occurring at a first sum phase, which is the phase Φ of the digital samples 710. maxsample and a phase correction function Φcorrectionfunction1. For example, the processor of analysis controller 108 determines that digital samples 710 do not have an ideal maximum amplitude. In this example, the processor of analysis controller 108 retrieves analog form of measurement signal 602 from a memory device of analysis controller 108 and identifies the ideal maximum amplitude, IdealMax, received by the ADC from one of RF sensors 118-122 (FIG. 1) at the first summation phase.

[0081] The processor of analysis controller 108 transmits the ideal maximum amplitude IdealMax in place of digital samples 710 to the processor of process controller 116 via transfer cable 146. For example, during calibration of RF generators 102, 104, and 106 within a predetermined period of time, the processor of analysis controller 108 replaces digital samples 710 transmitted to process controller 116 in digital signal 147 with the ideal maximum amplitude IdealMax and transmits IdealMax in digital signal 147 to process controller 116.

[0082] The processor of the processing controller 116 determines whether one or more of the RF generators 102, 104, and 106 are calibrated based on the ideal maximum amplitude IdealMax within a predetermined period of time and controls one or more of the RF generators 102, 104, and 106 to calibrate the one or more of the RF generators 102, 104, and 106. For example, if the ideal maximum amplitude IdealMax is the amplitude of the measurement signal MS2 from the RF generator 102, the processor of the processing controller 116 calculates the transmitted power from the ideal maximum amplitude IdealMax and the corresponding digital value of the measurement signal MS1 at the first summation phase. In this example, the processor of the processing controller 116 controls the RF generator 102 based on the transmitted power. For example, if the processor of the processing controller 116 determines that the transmitted power is less than a first predetermined threshold, the processor of the processing controller 116 controls the RF generator 102 to increase the power supplied by the RF generator 102 until the transmitted power falls within the first predetermined threshold. For example, the processor of the process controller 116 transmits an increase in the amount of power to be supplied by the RF generator 102 in recipe signal RS1 (FIG. 1) to the RF generator 102 via transfer cable 154 (FIG. 1). In this example, upon receiving the increase in power, the RF generator 102 generates an RF signal having the increased amount of power.

[0083] The ADC of the analysis controller 108 outputs multiple digital samples 712, 714, 716, 718, and 720 of the measurement signal 602 during the second half (e.g., negative half) of cycle 20 of the measurement signal 602. However, an error occurs in outputting the digital samples 720. Instead of outputting the IdealMin sample, the digital sample 720 is output from the ADC.

[0084] In method 700, the processor of analysis controller 108 determines time t21 as the time at which a negative threshold crossing occurs. For example, the processor of analysis controller 108 determines that a negative threshold crossing occurred if the power value output from the ADC of analysis controller 108 before power value P0 is greater than power value P0 and the power value output from the ADC immediately after power value P0 is less than power value P0. Further, in this example, the processor of analysis controller 108 identifies from the mapping information that power value P0 was output from the ADC at time t21 of the negative threshold crossing during cycle 20.

[0085] Continuing with the method 700, the processor of the analysis controller 108 determines the phase Φ of the digital sample 720 having the minimum value during cycle 20. minsample To determine the mean frequency f av For example, the processor of the analysis controller 108 determines from the digital samples output from the ADC during cycle 20 that digital sample 720 has the minimum value or amplitude. In this example, the average frequency f av Based on this, the processor of analysis controller 108 calculates the distance from time t21, when the negative threshold crossing occurs during cycle 20, to time t21.5, when the digital sample 720 with the minimum amplitude is output from the ADC. Furthermore, in this example, time t21.5 corresponds to the phase Φ of digital sample 720. minsample is.

[0086] Also in the method 700, the processor of the analysis controller 108 calculates the phase Φ of the digital samples 720. minsample For example, the processor of analysis controller 108 identifies that ideally the minimum amplitude of measurement signal 602 occurs at a second predetermined phase (such as the 270° phase Φ or a second predefined phase). Further, in this example, the processor of analysis controller 108 determines the relationship between the second predetermined phase and the phase Φ of digital samples 720. minsampleand the absolute difference is the phase correction function Φcorrectionfunction2. In this example, the second preset phase is other than the 270° phase.

[0087] In the method 700, the processor of the analysis controller 108 calculates the phase Φ of the digital samples 720. minsample and a sum of a phase correction function Φcorrectionfunction2. Further in the method 700, the processor of the analysis controller 108 determines an ideal minimum amplitude IdealMin of the measurement signal 602 occurring at a second sum phase, which is the phase Φ of the digital samples 720. minsample and a phase correction function Φcorrectionfunction2. For example, the processor of analysis controller 108 determines that digital samples 720 do not have an ideal minimum amplitude. In this example, the processor of analysis controller 108 retrieves analog form of measurement signal 602 from a memory device of analysis controller 108 and identifies the ideal minimum amplitude, IdealMin, received by the ADC from one of RF sensors 118-122 at the second summation phase.

[0088] The processor of analysis controller 108 transmits the ideal minimum amplitude, IdealMin, in place of digital samples 720 to the processor of process controller 116 via transfer cable 146. For example, during calibration of RF generators 102, 104, and 106 during a predetermined period, the processor of analysis controller 108 replaces digital samples 720 transmitted to process controller 116 in digital signal 147 with the ideal minimum amplitude, IdealMin, and transmits IdealMin in digital signal 147 to process controller 116.

[0089] The processor 116 of the processing controller 116 determines whether one or more of the RF generators 102, 104, and 106 are calibrated within a predetermined period based on the ideal minimum amplitude IdealMin, and controls one or more of the RF generators 102, 104, and 106. For example, if the ideal minimum amplitude IdealMin is the amplitude of the measurement signal MS2 from the RF generator 102, the processor of the processing controller 116 calculates the transmitted power from the ideal minimum amplitude IdealMin and the corresponding digital value of the measurement signal MS1 in the second summation phase. In this example, the processor of the processing controller 116 controls the RF generator 102 based on the transmitted power. Thus, when a single cycle (such as cycle 20) is used to determine the first and second summation phases, as described in the above example, the time to calibrate or control the RF generator 102 is reduced.

[0090] In one embodiment, the predetermined number of cycles and 20 cycles of measurement signal 602 occur during a cycle of another measurement signal. For example, if measurement signal 602 is an example of measurement signal MS4, the other measurement signal is an example of measurement signal MS2. In this example, the predetermined number of cycles and 20 cycles of measurement signal MS4 occur during a cycle (e.g., a single cycle) of measurement signal MS2. In this example, measurement signal MS4 has a high frequency, and measurement signal MS2 has a low frequency. Furthermore, in this example, the low frequency is also the frequency of RF signal 160, and the high frequency is the frequency of RF signal 162.

[0091] In one embodiment, an example of a positive threshold crossing is a constant value (e.g., a positive value). Further, in this embodiment, an example of a negative threshold crossing is that constant value.

[0092] In one embodiment, the digital values are also referred to herein as sample points or digital samples or digital sample values.

[0093] In one embodiment, method 700 is performed after calibration of RF generators 102, 106, and 106 within a predetermined period of time. For example, method 700 is performed during processing of a substrate in plasma chamber 114 (FIG. 1).

[0094] In one embodiment, method 700 is equally applicable to determining ideal amplitude values other than ideal maximum and minimum amplitudes. For example, method 700 is equally applicable to determining ideal amplitude values at phases other than 90° or 270°. For example, method 700 is equally applicable to determining ideal amplitude values at phases other than 80° or 170°.

[0095] The embodiments described herein may be practiced with various computer system configurations, including handheld hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, etc. Embodiments may also be practiced in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a network.

[0096] In some embodiments, the controller is part of a system, which may be part of the examples described above. Such systems include semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (e.g., wafer pedestals, gas flow systems, etc.). These systems are integrated with electronics for controlling the operation of the system before, during, and after processing of semiconductor wafers or substrates. The electronics may be referred to as a "controller" and may control various components or subcomponents of one or more systems. Depending on the processing requirements and / or type of system, the controller is programmed to control any of the processes disclosed herein, such as supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid supply settings, position and motion settings, and wafer movement in and out of load locks connected or coupled to the tool and other moving tools and / or systems.

[0097] Generally, in various embodiments, a controller is defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. Integrated circuits include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions are instructions that are communicated to the controller in the form of various individual settings (or program files) to define parameters, factors, variables, etc., for or to a system to perform a particular process on or for a semiconductor wafer. Program instructions, in some embodiments, are part of a recipe defined by a process engineer to accomplish one or more process steps during processing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0098] In some embodiments, the controller is part of or connected to a computer that is integrated with, connected to, or otherwise networked with the system, or a combination thereof. For example, the controller may be in the "cloud" or all or part of a fab host computer system that enables remote access of wafer processing. The computer enables remote access to the system to change parameters of a current process, set process steps according to a current process, or initiate a new process, monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, or examine trends or performance indicators from multiple manufacturing operations.

[0099] In some embodiments, a remote computer (e.g., a server) provides process recipes to the system over a network (including a local network or the Internet). The remote computer includes a user interface that allows for entry or programming of parameters and / or settings, which are communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters, factors, and / or variables for each of the process steps performed during one or more operations. It should be understood that the parameters, factors, and / or variables are specific to the type of process being performed and the type of tool the controller is configured to interface with or control. Thus, as described above, the controller is distributed, such as by having one or more separate controllers that are networked and operate toward a common purpose (such as the process and control described herein). One example of a distributed controller for such purposes includes one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., located at the platform level or remotely as part of a remote computer) that cooperate to control the process at the chamber.

[0100] In various embodiments, examples of systems to which the methods may be applied include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or utilized in the fabrication and / or manufacturing of semiconductor wafers.

[0101] It should also be noted that in some embodiments, the operations described above apply to several types of plasma chambers, such as plasma chambers with inductively coupled plasma (ICP) reactors, transformer-coupled plasma chambers, plasma chambers with conductor tools, dielectric tools, electron cyclotron resonance (ECR) reactors, etc. For example, one or more RF generators are connected to an inductor in an ICP reactor. Examples of inductor shapes include a solenoid, a dome-shaped coil, a planar coil, etc.

[0102] As described above, depending on the processing step or steps being performed by the tool, the host computer communicates with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to or from tool locations and / or load ports within the semiconductor fabrication factory.

[0103] With the above embodiments in mind, it should be understood that some of the embodiments employ various computer-implemented operations involving data stored in computer systems. These operations are operations that physically manipulate physical quantities. Any of the operations described herein that form part of the present embodiments are useful machine operations.

[0104] Some embodiments further relate to hardware units or apparatus for performing these operations, where the apparatus is specifically configured for a special purpose computer. When defined as a special purpose computer, the computer can operate for a specific purpose while performing other processes, program execution, or routines not included in the specific purpose.

[0105] In some embodiments, operations may be processed on a computer selectively activated or configured by one or more computer programs stored in computer memory, cache, or obtained over a computer network. When data is obtained over a computer network, the data may be processed by other computers on the computer network (e.g., a cloud of computing resources).

[0106] One or more embodiments may be fabricated as computer-readable code on a non-transitory computer-readable medium. The non-transitory computer-readable medium is any data storage hardware unit (e.g., a memory device) that stores data, which is then read by a computer system. Examples of non-transitory computer-readable media include hard drives, network-attached storage (NAS), ROM, RAM, compact disc-ROMs (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (CD-RWs), magnetic tapes, and other optical and non-optical data storage hardware units. In some embodiments, the non-transitory computer-readable medium comprises a tangible computer-readable medium distributed over network-connected computer systems such that the computer-readable code is stored and executed in a distributed manner.

[0107] Although the method operations described above are presented in a particular order, it should be understood that in various embodiments, other housekeeping processes may be performed between operations, or the method operations may be performed at slightly different times, may be distributed across a system that allows method operations to occur at various intervals, or may be arranged to be performed in an order different from that described above.

[0108] Furthermore, it should be noted that in one embodiment, one or more features of any embodiment described herein may be combined with one or more features of any other embodiment described herein without departing from the scope described in the various embodiments described in this disclosure.

[0109] Although the present embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. The present embodiments are therefore to be considered as illustrative and not restrictive, and the embodiments are not limited to the details given herein.

Claims

1. A system for calibrating a radio frequency (RF) generator, A first RF generator connected to the first input of an impedance matching circuit via a first RF cable, A second RF generator connected to the second input of the impedance matching circuit via a second RF cable, The first input of the impedance matching circuit is configured to be connected to the first RF sensor. The second input of the impedance matching circuit is configured to be connected to a second RF sensor, and is connected to a second RF generator. Processing controller and An analysis controller connected to the processing controller, wherein the analysis controller is configured to be connected to the first and second RF sensors, Equipped with, The analysis controller is configured to receive multiple analog measurement signals from the first and second RF sensors and output multiple digital signals. The system is configured such that the processing controller receives the plurality of digital signals and calibrates the first and second RF generators.

2. The system according to claim 1, wherein the first and second inputs of the impedance matching circuit are configured to be connected to the first and second RF sensors during the same period.

3. The system according to claim 1, wherein the plurality of digital signals include a first set of digital signals received from the first RF sensor and a second set of digital signals received from the second RF sensor, and the processing controller is configured to analyze the first and second sets of digital signals in order to calibrate the first and second RF generators within a predetermined period of time.

4. The system according to claim 3, wherein, in order to calibrate the first and second RF generators within the predetermined period, the processing controller is: The first measured RF power value calculated based on the first set of digital signals is compared with a first predetermined threshold of the operating RF power of the first RF generator. The system is configured to compare a second measured RF power value calculated based on the second set of digital signals with a second predetermined threshold of the operating RF power of the second RF generator. In order to calibrate the first and second RF generators within the predetermined period, the processing controller: When it is determined that the first measured RF power value does not meet the first predetermined threshold, the first RF generator, the second RF generator, or a combination thereof is controlled to achieve the first predetermined threshold. A system configured to control the first RF generator, the second RF generator, or a combination thereof, to achieve the second predetermined threshold when it is determined that the second measured RF power value does not meet the second predetermined threshold.

5. The system according to claim 1, wherein the first and second RF sensors are configured to be disconnected from the first and second inputs of the impedance matching circuit after the first and second RF generators have been calibrated, the analysis controller remains connected to the processing controller after the first and second RF generators have been calibrated, and the processing controller A portion of the measured power generated from the set of multiple digital signals is compared with a preset threshold. Based on the above comparison, it is determined that a portion of the measured power is outside the preset threshold, A system configured to change the RF power of the first RF generator, the second RF generator, or a combination thereof when it is determined that a portion of the measured power is outside the preset threshold.

6. The system according to claim 1, wherein the analysis controller is The average frequency of one of the aforementioned multiple analog measurement signals is determined. The average frequency is determined over a predetermined number of cycles of one of the plurality of analog measurement signals. For the cycle of one of the plurality of analog measurement signals, the time at which the first threshold crossover occurs for the one of the plurality of analog measurement signals is determined. The aforementioned cycle occurs after the predetermined number of cycles, Based on the average frequency and the occurrence time of the first threshold crossover, the first phase of the first sample point is determined. The first sample point is the first measurement value of one of the plurality of analog measurement signals during the first half of the cycle. A first correction function is determined from the first predetermined phase and the first phase. A system configured to determine a first ideal amplitude value of one of the plurality of analog measurement signals based on the first correction function.

7. The system according to claim 6, wherein the analysis controller is For the cycle of one of the plurality of analog measurement signals, the time of occurrence of the second threshold crossover of the one of the plurality of analog measurement signals is determined. Based on the average frequency and the occurrence time of the second threshold crossover, the second phase of the second sample point is determined. The second sample point is the second measurement value of one of the plurality of analog measurement signals during the latter half of the cycle. A second correction function is determined from the second predetermined phase and the second phase. A system configured to determine a second ideal amplitude value of one of the plurality of analog measurement signals based on the second correction function.

8. The system according to claim 7, wherein the analysis controller is configured to provide the first ideal amplitude value and the second ideal amplitude value to the processing controller, and the processing controller is configured to calibrate one or more of the first and second RF generators based on the first ideal amplitude value and the second ideal amplitude value.

9. A system according to claim 1, wherein the first and second RF generators are not calibrated sequentially, and the impedance matching circuit is connected to a plasma chamber for calibrating the first and second RF generators.

10. A method for calibrating a radio frequency (RF) generator, A process of receiving multiple analog measurement signals from multiple RF sensors and outputting multiple digital signals, wherein the multiple analog measurement signals are received by an analysis controller. A step of simultaneously calibrating the RF generator based on the plurality of digital signals, wherein the RF generator is calibrated by a processing controller, A method that includes [a certain feature].

11. A method according to claim 10, wherein the plurality of RF sensors include a first RF sensor and a second RF sensor, the plurality of RF generators include a first RF generator and a second RF generator, the first RF generator is connected to a first input of an impedance matching circuit via a first RF cable, the second RF generator is connected to a second input of the impedance matching circuit via a second RF cable, and the first and second inputs of the impedance matching circuit are connected to the first and second RF sensors during the same period.

12. A method according to claim 10, wherein the plurality of RF sensors include a first RF sensor and a second RF sensor, the plurality of digital signals include a first set of digital signals received from the first RF sensor and a second set of digital signals received from the second RF sensor, and the method comprises the step of analyzing the first and second sets of digital signals in order to calibrate the first and second RF generators within a predetermined period of time.

13. The method according to claim 12, wherein the step of analyzing the first and second sets of digital signals is: A step of comparing a first measured RF power value calculated based on the first set of digital signals with a first predetermined threshold of the operating RF power of the first RF generator, A step of comparing a second measured RF power value calculated based on the second set of digital signals with a second predetermined threshold of the operating RF power of the second RF generator, Includes, The step of calibrating the RF generator includes the step of calibrating the first and second RF generators within the predetermined period, and the step of calibrating the first and second RF generators within the predetermined period is When it is determined that the first measured RF power value does not meet the first predetermined threshold, the first RF generator, or the second RF generator, or a combination thereof, is controlled to achieve the first predetermined threshold of the operating RF power. When it is determined that the second measured RF power value does not meet the second predetermined threshold, the first RF generator, or the second RF generator, or a combination thereof, is controlled to achieve the second predetermined threshold for the operating RF power. Methods that include...

14. The method according to claim 10, wherein the plurality of RF sensors include a first RF sensor and a second RF sensor, the plurality of RF generators include a first RF generator and a second RF generator, the first RF generator is connected to a first input of an impedance matching circuit via a first RF cable, the second RF generator is connected to a second input of the impedance matching circuit via a second RF cable, the first and second RF sensors are configured to be disconnected from the first and second inputs of the impedance matching circuit after the first and second RF generators have been calibrated, the analysis controller remains connected to the processing controller after the first and second RF generators have been calibrated, and the method further comprises: A step of comparing a portion of the measured power generated from the set of multiple digital signals with a pre-set threshold, A step of determining, based on the above comparison, that a portion of the measured power is outside the preset threshold, When it is determined that a portion of the measured power is outside the preset threshold, the step of changing the RF power of one of the first RF generator, the second RF generator, or a combination thereof, A method that includes [a certain feature].

15. The method according to claim 10, further, A step of determining the average frequency of one signal among the plurality of analog measurement signals, wherein the average frequency is determined for a predetermined number of cycles of the one signal among the plurality of analog measurement signals. A step of determining the time at which a first threshold crossover occurs for one of the plurality of analog measurement signals, for the cycle of one of the plurality of analog measurement signals, wherein the cycle occurs after a predetermined number of cycles. A step of determining the first phase of a first sample point based on the average frequency and the time of occurrence of the first threshold crossover, wherein the first sample point is a first measurement value of one of the plurality of analog measurement signals during the first half of the cycle. A step of determining a first correction function from a first predetermined phase and the first phase, A step of determining a first ideal amplitude value of one of the plurality of analog measurement signals based on the first correction function, A method that includes [a certain feature].

16. The method according to claim 15, further, A step of determining the time at which a second threshold crossover occurs for one of the multiple analog measurement signals for the cycle of the one of the multiple analog measurement signals, A step of determining the second phase of a second sample point based on the average frequency and the time of occurrence of the second threshold crossover, wherein the second sample point is the second measurement value of one of the plurality of analog measurement signals in the latter half of the cycle. A step of determining a second correction function from a second predetermined phase and the second phase, A step of determining a second ideal amplitude value of one of the plurality of analog measurement signals based on the second correction function, A method that includes [a certain feature].

17. The method according to claim 16, further, A method comprising the step of providing the first ideal amplitude value and the second ideal amplitude value to the processing controller by the analysis controller, wherein one or more of the RF generators are calibrated based on the first ideal amplitude value and the second ideal amplitude value.

18. A method according to claim 10, wherein the plurality of RF generators include a first RF generator and a second RF generator, the first RF generator being connected to a first input of an impedance matching circuit via a first RF cable, the second RF generator being connected to a second input of the impedance matching circuit via a second RF cable, the first and second RF generators not being calibrated sequentially, and the impedance matching circuit being connected to a plasma chamber for calibrating the first and second RF generators.

19. A method for determining the ideal amplitude value, A step of determining the average frequency of one signal among a plurality of analog measurement signals, wherein the average frequency is determined for a predetermined number of cycles of the one signal among the plurality of analog measurement signals. A step of determining the time at which a first threshold crossover occurs for one of the plurality of analog measurement signals, for the cycle of one of the plurality of analog measurement signals, wherein the cycle occurs after a predetermined number of cycles. A step of determining the first phase of a first sample point based on the average frequency and the time of occurrence of the first threshold crossover, wherein the first sample point is a first measurement value of one of the plurality of analog measurement signals during the first half of the cycle. A step of determining a first correction function from a first predetermined phase and the first phase, A step of determining a first ideal amplitude value of one of the plurality of analog measurement signals based on the first correction function, A step of controlling a first radio frequency (RF) generator based on the first ideal amplitude value, A method that includes [a certain feature].

20. The method according to claim 19, further, A step of determining the time at which a second threshold crossover occurs for one of the multiple analog measurement signals for the cycle of the one of the multiple analog measurement signals, A step of determining the second phase of a second sample point based on the average frequency and the time of occurrence of the second threshold crossover, wherein the second sample point is the second measurement value of one of the plurality of analog measurement signals in the latter half of the cycle. A step of determining a second correction function from a second predetermined phase and the second phase, A step of determining a second ideal amplitude value of one of the plurality of analog measurement signals based on the second correction function, A step of controlling the first RF generator based on the second ideal amplitude value, A method that includes [a certain feature].

21. A method according to claim 19, wherein the predetermined number of cycles of one of the plurality of analog measurement signals and the cycles occur during the cycles of an RF signal generated by a second RF generator, the second RF generator having an operating frequency lower than the operating frequency of the first RF generator.

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