Pulse output monitor device

Abstract

To provide a pulse output monitor device that appropriately detects information regarding pulse output using a voltage at an output terminal of an impedance matching device.SOLUTION: In a pulse output monitor device 5, a first reference waveform generation portion 51 and a second reference waveform generation portion 52 generate a first reference waveform WF1 and a second reference waveform WF2. An intra-period voltage waveform generation unit 53 generates an intra-period voltage waveform. A first similarity calculation unit 54 calculates the similarity between the first reference waveform WF1 and the intra-period voltage waveform. Further, a second similarity calculation unit 55 calculates the similarity between the second reference waveform WF2 and the intra-period voltage waveform. A first determining unit 56 and a second determining unit 57 determine the rising timing of the pulse output and the falling timing of the pulse output on the basis of the similarity, and an output unit 58 outputs information on pulse output on the basis of the rising timing of the pulse output and the falling timing of the pulse output.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present embodiment relates to a device for monitoring information related to pulse output. [Background technology]

[0002] A plasma processing apparatus generates plasma in a plasma generating section using high frequency power supplied from a high frequency power supply apparatus, and performs plasma processing such as etching on a workpiece such as a wafer.

[0003] Typically, an impedance matching device is placed between the high frequency power supply and the plasma processing unit to ensure that power is efficiently supplied to the plasma generating section of the plasma processing unit, which acts as a load. The output frequency of the high frequency power supply unit is in a frequency band such as 13.56 MHz or 27.12 MHz.

[0004] In such plasma processing, the state of the plasma varies depending on the type of gas, gas flow rate, the magnitude of the high-frequency power supplied from the high-frequency power supply device, etc., so these are controlled to maintain an appropriate state and monitored for any abnormalities.

[0005] To this end, there is a technology that detects the voltage at the input end of the plasma generating unit or the output end of the impedance matching box, and monitors information (pulse frequency and duty ratio) related to the pulse output from the high-frequency power supply device based on the detected voltage information (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-91526 Summary of the Invention [Problem to be solved by the invention]

[0007] When monitoring information related to pulse output based on the detected voltage at the input terminal of the plasma generating unit or the output terminal of the impedance matching box, the detected voltage is affected not only by the forward wave voltage but also by the reflected wave voltage, resulting in various changes in the detected voltage. As a result, it may be difficult to monitor information related to pulse output. Therefore, an object of the present invention is to provide a pulse output monitoring device that can output information related to pulse output even when the detected voltage is affected by the reflected wave voltage. [Means for solving the problem]

[0008] The pulse output monitor device according to the present invention is a pulse output monitor device that outputs information about a pulse output when a pulse output is performed in which the shape of the envelope of the voltage waveform of a traveling wave voltage output from a high frequency power supply device to a load is pulsed, and includes a voltage detector that detects a voltage at a position between the high frequency power supply device and the load, a first reference waveform generation unit that generates a first reference waveform that serves as a reference waveform at a rising timing based on voltage information detected by the voltage detector in a first period near the rising timing of a pulse command signal that determines the shape of the envelope of the voltage waveform of the traveling wave voltage, a second reference waveform generation unit that generates a second reference waveform that serves as a reference waveform at a falling timing based on voltage information detected by the voltage detector in a second period near the falling timing of the pulse command signal, and a second reference waveform generation unit that generates a second reference waveform that serves as a reference waveform at a falling timing based on voltage information detected by the voltage detector in a second period near the falling timing of the pulse command signal, every predetermined time period. the voltage detector includes an in-period voltage waveform generation unit that generates a voltage waveform within a predetermined period based on voltage information detected by the voltage detector; a first similarity calculation unit that calculates, for each predetermined time period, a similarity between the first reference waveform and the voltage waveform generated by the in-period voltage waveform generation unit; a second similarity calculation unit that calculates, for each predetermined time period, a similarity between the second reference waveform and the voltage waveform generated by the in-period voltage waveform generation unit; a first judgment unit that judges the rising timing of a pulse output at the position of the voltage detector based on the similarity calculated by the first similarity calculation unit; a second judgment unit that judges the falling timing of the pulse output at the position of the voltage detector based on the similarity calculated by the second similarity calculation unit; and an output unit that outputs information related to the pulse output based on the judgment result of the first judgment unit and the judgment result of the second judgment unit. [Effects of the Invention]

[0009] According to the present invention, even when the detected voltage is affected by the reflected wave voltage, information relating to the pulse output can be monitored. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a plasma processing system according to a first embodiment. [Figure 2]5A and 5B are diagrams illustrating an example of waveforms of a pulse command signal and a Vpp detection voltage. [Figure 3] 1 is a diagram showing an example of a configuration including a pulse output monitor device according to a first embodiment. [Figure 4] 10 is a diagram showing the relationship between a pulse command signal and an adjustment time and a detection time when a first reference waveform WF1 is generated. FIG. [Figure 5] FIG. 10 is a diagram showing an example of a voltage waveform within a period. [Figure 6] FIG. 10 is a diagram illustrating an example of a first similarity. [Figure 7] 10 is a flowchart showing a processing procedure for outputting information related to pulse output. [Figure 8] FIG. 10 is a diagram showing another example of the configuration including the pulse output monitor device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] A pulse output monitor according to the present invention is used, for example, as one of the components of a plasma processing system, and will be described in detail below with reference to the drawings showing an embodiment thereof.

[0012] (First embodiment) 1 is a schematic diagram showing an example of the configuration of a plasma processing system according to the first embodiment. The plasma processing system is used when performing plasma processing such as etching in a semiconductor matching process, and includes, for example, a high-frequency power supply device 1, a matching box 2, and a plasma load 3.

[0013] A plasma load 3 such as a plasma processing device has a plasma chamber (not shown) in which plasma is generated, and generates plasma in the plasma chamber using high-frequency power supplied from a high-frequency power supply device 1, thereby performing plasma processing such as etching in a semiconductor alignment process.

[0014] The matching box 2 is interposed between the high frequency power supply 1 and the plasma load 3. In order to accommodate the load impedance that fluctuates from moment to moment in the plasma load 3, the matching box 2 changes the capacitance of a capacitor provided inside, for example, so that the impedance seen from the input end of the matching box 2 toward the load side becomes a predetermined value (for example, 50 Ω, the output impedance of the high frequency power supply 1). This matches the impedance on the high frequency power supply 1 side with the impedance on the plasma load 3 side, thereby suppressing the reflected wave power from the plasma load 3. Note that the matching box 2 is not an essential component, and the plasma load 3 and the high frequency power supply 1 may be directly connected.

[0015] The high-frequency power supply 1 is an AC power supply that outputs high-frequency power having a voltage component of an industrial RF (Radio Frequency) band frequency, such as 400 kHz, 2 MHz, 13.56 MHz, 27.12 MHz, 40.68 MHz, or 60 MHz, and its output impedance is set to a specified value, such as 50 Ω. The high-frequency power output from the high-frequency power supply 1 is supplied to a plasma load 3 via a matching box 2. The high-frequency power supply 1 converts an input DC voltage to a predetermined DC voltage and outputs the DC voltage. The output voltage is then converted to a predetermined high-frequency AC voltage (RF voltage) using, for example, an inverter circuit. The high-frequency power supply 1 is also equipped with a control device that controls the high-frequency power supply 1, and controls the output so that, for example, the power value of the output high-frequency power (traveling wave power) or the voltage value of the output voltage (traveling wave voltage) reaches a target value. The high-frequency power flowing from the high-frequency power supply 1 to the plasma load 3 is called traveling wave power, and its voltage component is called traveling wave voltage. Moreover, the high frequency power reflected by the plasma load 3 and directed toward the high frequency power supply device 1 is called reflected wave power, and the voltage component thereof is called reflected wave voltage.

[0016] The form of high-frequency power (traveling wave power) output from the high-frequency power supply device 1 is called pulse output, in which the output voltage (traveling wave voltage) alternates between high and low periods. For example, the output voltage of the high-frequency power supply device 1 is controlled so that the power supplied to the plasma load 3 is 1000 W during the high period and 0 W during the low period. Of course, the power value during the low period may be greater than 0 W.

[0017] When performing such pulse output, the control device of the high frequency power supply 1 sets the pulse period and duty ratio in advance. The control device of the high frequency power supply 1 generates, for example, a rectangular pulse command signal based on the pulse period and duty ratio. The high frequency power supply 1 outputs high frequency power (traveling wave power) modulated based on the pulse command signal. The control device of the high frequency power supply 1 outputs the pulse command signal to a pulse output monitor device 5, which will be described later. The shape of the envelope of the voltage waveform of the traveling wave voltage is determined by the pulse command signal.

[0018] In the plasma processing system described above, the state of the plasma varies depending on the type of gas, gas flow rate, the magnitude of the high-frequency power supplied from the high-frequency power supply device 1, etc., so these may be controlled to maintain an appropriate state and monitored for any abnormalities.

[0019] One of the targets is the voltage at the plasma load 3. However, since it is difficult to directly detect the voltage at the plasma load 3, a detector is provided at a detectable location such as the input terminal of the plasma load 3 or the output terminal of the matching box 2 to detect the voltage. This voltage is referred to as the Vpp detection voltage, and the detector is referred to as the Vpp detector. The Vpp detector is an example of a voltage detector.

[0020] As described above, the form of the high-frequency power (traveling wave power) output from the high-frequency power supply device 1 is a form called pulse output, in which the output voltage (traveling wave voltage) alternates between high and low periods. For example, the output voltage of the high-frequency power supply device 1 is controlled so that the power supplied to the plasma load 3 is 1000 W during the high period and 0 W during the low period. The power value during the low period may be greater than 0 W.

[0021] When performing such a pulse output, there will be a slight delay on the time axis, but the voltage value of the Vpp detection voltage detected by the Vpp detector should be large (High period) when the pulse output is High, and the voltage value of the Vpp detection voltage detected by the Vpp detector should be small (Low period) when the pulse output is Low. In other words, the magnitude relationship between the pulse output command value and the magnitude relationship between the voltage values ​​of the Vpp detection voltage should match.

[0022] However, in reality, there are cases where the magnitude relationship between the command values ​​of the pulse output and the voltage value of the Vpp detection voltage differ.

[0023] FIG. 2 is a diagram showing an example of the waveform of a pulse command signal and a Vpp detection voltage. Fig. 2(a) shows a pulse command signal generated by the high-frequency power supply 1. Fig. 2(b) shows an example of a voltage waveform detected by a Vpp detector in a certain process. The shape of the envelope of the waveform shown in Fig. 2(a) is similar to the shape of the envelope of the waveform shown in Fig. 2(b).

[0024] Figure 2(c) shows an example of the waveform of the Vpp detection voltage in a process different from that in Figure 2(b). As shown in Figure 2(c), there are cases where the Vpp detection voltage detected by the Vpp detector is small during the high period of the pulse output, and large during the low period of the pulse output.

[0025] The reason for this is thought to be that at the position of the Vpp detector, the voltage output from the high-frequency power supply 1 and directed toward the plasma load 3 (forward wave voltage) and the voltage directed from the plasma load 3 toward the high-frequency power supply 1 (reflected wave voltage) are detected by the Vpp detector as a combined standing wave, and the Vpp detected voltage changes depending on the degree of reflection (reflection coefficient) and the relationship between the phase of the forward wave voltage and the phase of the reflected wave voltage.

[0026] For example, even if the relationship between the phase of the forward wave voltage and the phase of the reflected wave voltage is constant, if the reflected wave voltage acts to cancel out the forward wave voltage, the detected value of the Vpp detection voltage will be small. Conversely, if the reflected wave voltage acts to amplify the forward wave voltage, the detected value of the Vpp detection voltage will be large. As a result, as shown in Figure 2(c), there may be cases where the magnitude relationship between the pulse output command value and the Vpp detection voltage value does not match. Even in such a case, if the shape of the envelope of the waveform of the Vpp detection voltage repeats a certain pattern, this is not a problem in itself, and what is important is whether the results of the plasma processing such as etching are good or bad.

[0027] In addition to the above-mentioned phenomenon, it has been confirmed that the shape of the envelope of the waveform of the Vpp detection voltage is not constant but changes over time. For example, even if the magnitude of the reflection coefficient remains the same, if the relationship between the phase of the forward wave voltage and the phase of the reflected wave voltage changes over time, the Vpp detection voltage will change over time. Furthermore, if the reflection coefficient changes over time, the Vpp detection voltage may change in various ways.

[0028] Furthermore, when two high frequency power supply devices are used to supply high frequency powers of different frequencies to a load, the reflected wave voltage is likely to increase due to the influence of the high frequency power of the other frequency, so the Vpp detection voltage may vary in even more diverse ways.

[0029] This can cause problems when performing control or monitoring for abnormalities based on the Vpp detection voltage. For example, it may be impossible to determine whether pulse output is being performed correctly based on the Vpp detection voltage. Therefore, in the plasma system according to this embodiment, even if the Vpp detection voltage changes in various ways, the pulse output monitor device 5 described below monitors information related to the pulse output at the load and outputs that information.

[0030] Fig. 3 is a diagram showing an example of a configuration including a pulse output monitoring device according to the first embodiment. The configuration shown in Fig. 3 is included in, for example, a matching box 2. The matching box 2 includes a Vpp detector 21, a filter 22, and a pulse output monitoring device 5. The matching box 2 also includes, for example, a variable capacitor necessary for impedance matching, but these are omitted here. Pulse output monitoring device 5 includes first reference waveform generating section 51, second reference waveform generating section 52, intra-period voltage waveform generating section 53, first similarity calculating section 54, second similarity calculating section 55, first determining section 56, second determining section 57, and output section 58. Pulse output monitoring device 5 may not be built into matching box 2 but may be provided externally.

[0031] Pulse output monitor device 5 includes an MPU (Micro-processing unit), a system LSI (Large-Scale Integration), or an FPGA (Field-Programmable Gate Array) equipped with a storage unit (not shown) such as RAM (Random Access Memory) or ROM (Read Only Memory), and performs various control processes, arithmetic processes, etc. by reading and executing programs and data stored in the storage unit. By executing the programs, pulse output monitor device 5 functions as first reference waveform generator 51, second reference waveform generator 52, in-period voltage waveform generator 53, first similarity calculator 54, second similarity calculator 55, first judgment unit 56, second judgment unit 57, and output unit 58.

[0032] The Vpp detector 21 is installed at a position close to the plasma load 3, such as the output end of the matching box 2. The Vpp detector 21 detects the voltage at its installation position and outputs the detected voltage information to the filter 22. For example, this is voltage amplitude information. This may be output as an analog detection signal, or may be output after being converted into a digital detection signal by an A / D converter (not shown).

[0033] The filter 22 removes noise from the waveform of the Vpp detection voltage and outputs information about the Vpp detection voltage to the first reference waveform generating section 51, the second reference waveform generating section 52, and the in-period voltage waveform generating section 53. It should be noted that an analog filter is used if the input signal to filter 22 is an analog detection signal, and a digital filter is used if the input signal to filter 22 is a digital detection signal. Since the output of filter 22 is output to first reference waveform generating section 51, second reference waveform generating section 52, and in-period voltage waveform generating section 53, in the case of an analog filter, the output is converted into a digital detection signal by an A / D converter (not shown) before being output.

[0034] <Reference waveform generation> The first reference waveform generating unit 51 generates a first reference waveform WF1 that serves as a reference waveform at the rising timing of the pulse command signal based on voltage information detected by the Vpp detector 21 during a first period near the rising timing of the pulse command signal. The generated first reference waveform WF1 is output to the first similarity calculating unit 54. The first reference waveform WF1 is represented, for example, by the envelope of the waveform of the Vpp detection voltage. Furthermore, the second reference waveform generating unit 52 generates a second reference waveform WF2 that serves as a reference waveform at the falling timing of the pulse command signal based on voltage information detected by the Vpp detector 21 during a second period near the falling timing of the pulse command signal. The generated second reference waveform WF2 is output to the second similarity calculating unit 55. The second reference waveform WF2 is represented, for example, by the envelope of the waveform of the Vpp detection voltage.

[0035] The first reference waveform generating unit 51 and the second reference waveform generating unit 52 receive a pulse command signal from, for example, a control device of the high-frequency power supply 1. The first reference waveform generating unit 51 and the second reference waveform generating unit 52 also receive, for example, an adjustment time Tadj and a detection time Tdet from the control device of the high-frequency power supply 1. The adjustment time Tadj and the detection time Tdet are predetermined parameters. The adjustment time Tadj can be a positive value as well as a negative or zero value.

[0036] The first period starts from a timing shifted by the adjustment time Tadj from the rising timing of the pulse command signal, and ends when the detection time Tdet has elapsed. The first reference waveform generating unit 51 stores information about the Vpp detection voltage detected during the first period in a storage means (not shown), and after the first period ends, reads out the stored information to generate the first reference waveform WF1. The timing for reading out the stored information and the timing for generating the first reference waveform WF1 are set according to the situation.

[0037] The second period starts from a timing shifted by the adjustment time Tadj from the falling timing of the pulse command signal, and ends when the detection time Tdet has elapsed. The second reference waveform generating unit 52 stores information about the Vpp detection voltage detected during the second period in a storage means (not shown), and after the second period ends, reads out the stored information to generate the second reference waveform WF2. The timing for reading out the stored information and the timing for generating the first reference waveform WF1 are set according to the situation.

[0038] Next, the adjustment time Tadj and the detection time Tdet will be further described with reference to FIG. FIG. 4 is a diagram showing the relationship between the pulse command signal and the adjustment time Tadj and detection time Tdet when generating the first reference waveform WF1. 4(a) shows an example in which the adjustment time Tadj is negative. The first reference waveform generating unit 51 starts detection the adjustment time Tadj before the rising edge of the pulse command signal, detects the Vpp detection voltage for the detection time Tdet, and generates a first reference waveform WF1 corresponding to the dashed line area as shown in FIG. 4(a) based on information about the detected Vpp detection voltage.

[0039] Fig. 4(b) shows an example where the adjustment time Tadj is 0. The first reference waveform generating unit 51 starts detection simultaneously with the rising edge of the pulse command signal, detects the Vpp detection voltage for the detection time Tdet, and generates a first reference waveform WF1 corresponding to the dashed line area as shown in Fig. 4(b) based on information about the detected Vpp detection voltage.

[0040] 4(c) shows an example in which the adjustment time Tadj is positive. The first reference waveform generating unit 51 starts detection when the adjustment time Tadj has elapsed since the rising edge of the pulse command signal, detects the Vpp detection voltage for the detection time Tdet, and generates a first reference waveform WF1 corresponding to the dashed line area as shown in FIG. 4(c) based on information about the detected Vpp detection voltage.

[0041] By using the adjustment time Tadj and the detection time Tdet in this way, the region of the first reference waveform WF1 can be adjusted, thereby generating a first reference waveform WF1 suitable for similarity determination, which will be described later. Furthermore, the appropriate adjustment time Tadj and detection time Tdet vary depending on the pulse frequency, duty cycle, etc. of the pulse output, so they can be set appropriately depending on the pulse output conditions, etc. For example, there are situations where the configuration shown in Figure 4(a) is more appropriate, and there are also situations where the configuration shown in Figure 4(b) is more appropriate.

[0042] Although detailed description will be omitted, the second reference waveform generating unit 52 also generates the second reference waveform WF2 using the adjustment time Tadj and detection time Tdet for the falling edge of the pulse command signal. Therefore, like the first reference waveform generating unit 51, the second reference waveform WF2 suitable for similarity determination, which will be described later, can be generated.

[0043] The first reference waveform generating unit 51 may also detect the Vpp detection voltage multiple times, generate multiple reference waveforms based on voltage information about the detected Vpp detection voltage, and generate the first reference waveform WF1 by, for example, averaging them. Similarly, the second reference waveform generating unit 52 may detect the Vpp detection voltage multiple times, generate multiple reference waveforms based on voltage information about the detected Vpp detection voltage, and generate the second reference waveform by, for example, averaging them. This is because, although the waveform of the Vpp detection voltage is reproducible to a certain extent, it is not the same waveform every time. Averaging in this manner makes it possible to generate stable first reference waveform WF1 and second reference waveform WF2.

[0044] The first reference waveform generating unit 51 and the second reference waveform generating unit 52 store information on the Vpp detection voltage detected multiple times in storage means (not shown), and after multiple detections are completed, read out the stored information to generate the first reference waveform WF1 and the second reference waveform WF2. The timing for reading out the stored information and the timing for generating the first reference waveform WF1 and the second reference waveform WF2 are set according to the situation.

[0045] The first reference waveform WF1 and the second reference waveform WF2 do not need to be set once, but must be updated as appropriate. For example, they are updated once every 100 cycles of the pulse output. The update rate is set according to the situation.

[0046] <Generation of voltage waveform within the period> The in-period voltage waveform generation unit 53 receives the output signal of the filter 22 and generates a voltage waveform within a predetermined period (hereinafter referred to as the in-period voltage waveform) based on the voltage information detected by the Vpp detector 21 at each predetermined time period. This in-period voltage waveform is represented, for example, by the envelope of the waveform of the Vpp detection voltage. The in-period voltage waveform is output to the first similarity calculation unit 54 and the second similarity calculation unit 55. That is, in the case of the in-period voltage waveform generation unit 53 shown in FIG. 3, the same in-period voltage waveform is input to the first similarity calculation unit 54 and the second similarity calculation unit 55. In this case, the above-mentioned predetermined period is a period having the same duration as the first period and the second period. Naturally, the first period and the second period are periods having the same duration.

[0047] FIG. 5 is a diagram showing an example of a voltage waveform within a period. Figure 5(a) shows the voltage waveform WFdet1 within the first period. Figure 5(b) shows the voltage waveform WFdet2 within the second period. Figure 5(c) shows the voltage waveform WFdet3 within the third period. Figure 5(d) shows the voltage waveform WFdetn within the nth period. In this way, the in-period voltage waveform generating section 53 generates the first in-period voltage waveform using a certain timing (for example, the rising edge of the pulse command signal) as a reference, and then generates successive in-period voltage waveforms.

[0048] As shown in Fig. 5, the voltage waveforms within each period overlap with the pulse command signal on the time axis. In the example of Fig. 5, for the sake of simplicity, the overlap is set to 50% of the detection time Tdet, but this is not limiting. The degree of overlap may be increased (e.g., 90%) or decreased (e.g., 10%). In principle, increasing the degree of overlap to obtain more detailed data increases accuracy, but this also increases the computational load, so the degree of overlap can be determined according to the situation.

[0049] The in-period voltage waveform generator 53 stores information about the detected Vpp detection voltage in a storage means (not shown), and then reads out the stored Vpp detection voltage information to generate the in-period voltage waveform. The timing for reading out the stored information and the timing for generating the in-period voltage waveform are set according to the situation.

[0050] <Similarity calculation> The first similarity calculation section 54 calculates the similarity between the first reference waveform WF1 and the intra-period voltage waveform generated by the intra-period voltage waveform generation section 53 for each predetermined time period. 5, the first similarity calculation unit 54 calculates the similarity between each of the first to nth in-period voltage waveforms and the first reference waveform WF1. The first similarity calculation unit 54 outputs the calculated similarity to the first determination unit 56 as a first similarity SM1(n), where "n" is the detection timing.

[0051] The second similarity calculation section 55 calculates the similarity between the second reference waveform WF2 and the intra-period voltage waveform generated by the intra-period voltage waveform generation section 53 for each predetermined time period. 5, the second similarity calculation unit 55 calculates the similarity between each of the first to nth in-period voltage waveforms and the second reference waveform WF2. The second similarity calculation unit 55 outputs the calculated similarity to the second determination unit 57 as the second similarity SM2(n), where "n" is the detection timing.

[0052] Fig. 6 shows an example of the first similarity SM1(n) calculated by the first similarity calculation unit 54 when the intra-period voltage waveform shown in Fig. 5 is used as the similarity calculation target. The processing performed by the second similarity calculation unit 55 is similar to that performed by the first similarity calculation unit 54, and therefore a description thereof will be omitted here.

[0053] The first similarity calculation unit 54 and the second similarity calculation unit 55 calculate the similarity using, for example, normalized cross-correlation, which may be NCC (Normalized Cross-Correlation) or ZNCC (Zero-mean Normalized Cross-Correlation). In this embodiment, for the sake of simplicity, it is assumed that the first similarity calculation unit 54 calculates the similarity on a scale of 1 to 10. In the example shown in FIG. 6, the second in-period voltage waveform WFdet2 has the highest similarity.

[0054] The first determination unit 56 determines that the detection timing corresponding to the first similarity SM1(max), which has the highest similarity among the first similarities SM1(1) to SM1(n) calculated by the first similarity calculation unit 54, is the rising edge of a pulse. The first determination unit 56 outputs information related to this first similarity SM1(max) to the output unit 58. In other words, the first determination unit 56 outputs to the output unit 58 the similarity corresponding to the detection timing determined to be the rising edge of a pulse.

[0055] 6, the voltage waveform WFdet2 within the second period has the highest similarity, so it can be inferred that the actual Vpp detection voltage rose at time point 2. Therefore, the first determination unit 56 outputs information indicating that detection time point n is the second and that the similarity at that time is 8 to the output unit 58.

[0056] The second determination unit 57 determines that the detection timing corresponding to the first similarity SM2(max), which has the highest similarity among the first similarities SM1(1) to second similarities SM2(n) calculated by the second similarity calculation unit 55, is the falling edge of the pulse. The second determination unit 57 outputs information related to this second similarity SM1(max) to the output unit 58. The processing in the second determination unit 57 is similar to that in the first determination unit 56, and therefore a description using figures will be omitted.

[0057] <Output of information about pulse output> The output unit 58 receives the first similarity SM1(max) output from the first determination unit 56 and the second similarity SM2(max) output from the second determination unit 57. The output unit 58 determines that the rising timing of the pulse output is the timing indicated by the first similarity SM1(max) output from the first determination unit 56. It also determines that the falling timing of the pulse output is the timing indicated by the second similarity SM2(max) output from the second determination unit 57. Then, based on this information, it outputs the frequency (which may be expressed as a period) of the pulse output and the duty ratio of the pulse output (the ratio of the High period to the period of the pulse output). Note that the output unit 58 may output only one of the frequency of the pulse output and the duty ratio of the pulse output. The frequency of the pulse output and the duty ratio of the pulse output are examples of information about the pulse output based on the determination results of the first determination unit 56 and the second determination unit 57.

[0058] 3, the output unit 58 can receive a pulse command signal from the high-frequency power supply 1. In this way, the amount of deviation between the rising timing of the actual pulse output and the rising timing of the pulse command signal can be determined. Also, the amount of deviation between the falling timing of the actual pulse output and the falling timing of the pulse command signal can be determined. Therefore, the output unit 58 can output these pieces of information.

[0059] The information output from output unit 58 is sent to, for example, high frequency power supply device 1 and a control device that controls the entire plasma processing system.

[0060] By monitoring at least one of the information output from the output unit 58 (e.g., the frequency of the pulse output, the duty ratio, the deviation in the rising timing, and the deviation in the falling timing), it is possible to know how the monitored information changes over time. Furthermore, by analyzing such information, it is possible to estimate, for example, the degree of contamination due to particles in the chamber of the plasma processing apparatus. This can serve as a guide for determining when to clean the chamber. It can also be used to infer that some kind of abnormality has occurred. For example, if the duty ratio of the pulse output differs from the initial value by more than a reference value, it is possible that the degree of contamination in the chamber has increased. Of course, there are cases where it is not possible to make a judgment based on this information alone, but it can be one factor in making a judgment. In this way, the information output from the output unit 58 is important in terms of process management, so it is useful to be able to appropriately monitor information related to pulse output.

[0061] 7 is a flowchart showing the processing steps for outputting information about pulse output executed by pulse output monitor device 5. First, first reference waveform generator 51 and second reference waveform generator 52 generate first reference waveform WF1 and second reference waveform WF2 (step S1). Next, intra-period voltage waveform generator 53 generates an intra-period voltage waveform for each predetermined time period (step S2). Next, first similarity calculator 54 calculates the similarity between first reference waveform WF1 and the intra-period voltage waveform. Furthermore, second similarity calculator 55 calculates the similarity between second reference waveform WF2 and the intra-period voltage waveform (step S3).

[0062] Next, first determination unit 56 and second determination unit 57 determine the rising and falling timings of the pulse output based on the calculated similarity (step S4). Output unit 58 outputs information about the pulse output based on the rising and falling timings of the pulse output (step S5).

[0063] (Second embodiment) FIG. 8 is a diagram showing another example of the configuration including the pulse output monitoring device according to the second embodiment. 8 includes an in-period voltage waveform generating section 53 including a first in-period voltage waveform generating section 531 and a second in-period voltage waveform generating section 532. In this respect, it differs from the first embodiment. In addition, in the first embodiment, the first reference waveform generating unit 51 and the second reference waveform generating unit 52 input a common adjustment time Tadj and detection time Tdet, but in the second embodiment, they each input their own dedicated adjustment time Tadj and detection time Tdet. More specifically, the first reference waveform generating unit 51 receives a first adjustment time Tadj1 as the adjustment time Tadj for the first period, and receives a first detection time Tdet1 as the detection time Tdet for the first period. The second reference waveform generating unit 52 receives a second adjustment time Tadj2 as the adjustment time Tadj for the second period, and receives a second detection time Tdet2 as the detection time Tdet for the second period. In the second embodiment, the pulse command signal is common to the first reference waveform generating section 51 and the second reference waveform generating section 52.

[0064] The first period begins at a timing shifted by a first adjustment time Tadj1 from the rising edge of the pulse command signal and ends when a first detection time Tdet1 has elapsed. The first reference waveform generating unit 51 stores information about the Vpp detection voltage detected during the first period in a storage device (not shown), and after the first period ends, reads out the stored information to generate the first reference waveform WF1. The timing for reading out the stored information and the timing for generating the first reference waveform WF1 are set according to the situation.

[0065] The second period begins at a timing shifted by the second adjustment time Tadj2 from the falling edge of the pulse command signal and ends when the second detection time Tdet2 has elapsed. The second reference waveform generation unit 52 stores information about the Vpp detection voltage detected during the second period in storage means (not shown), and after the second period ends, reads out the stored information to generate the second reference waveform WF2. The timing for reading out the stored information and the timing for generating the first reference waveform WF1 are set according to the situation.

[0066] The first-period voltage waveform generation unit 531 generates a voltage waveform within the first period (hereinafter referred to as the first-period voltage waveform) based on voltage information detected within that period having the same duration as the first period. This first-period voltage waveform is represented, for example, by the envelope of the waveform of the Vpp detection voltage. The generated first-period voltage waveform is output to the first similarity calculation unit 54.

[0067] The second-period voltage waveform generation unit 532 generates a voltage waveform within the second period (hereinafter referred to as the second-period voltage waveform) based on voltage information detected within the period having the same duration as the second period. This second-period voltage waveform is represented, for example, by the envelope of the waveform of the Vpp detection voltage. The generated second-period voltage waveform is output to the second similarity calculation unit 55.

[0068] In the case of the in-period voltage waveform generation unit 53 of FIG. 8, the first period and the second period may be periods having the same length of time, or may be periods having different lengths of time. If the periods have the same length of time, control can be simplified. If the periods have different lengths of time, control appropriate for the first period and the second period can be performed. In this way, if the in-period voltage waveform generation unit 53 is divided into the in-first-period voltage waveform generation unit 531 and the in-second-period voltage waveform generation unit 532, the options for control methods can be increased.

[0069] As described above, the pulse output monitoring device 5 of the present embodiment (first embodiment, second embodiment) generates voltage waveforms at the rise and fall of the pulse output as reference waveforms. It also generates a voltage waveform within a period during pulse output. Then, based on the similarity between the reference waveform and the voltage waveform within the period, it determines the rise and fall timings of the pulse output. Therefore, even if the Vpp detection voltage detected by the Vpp detector is affected by the voltage of the reflected wave, it is possible to appropriately monitor information related to the pulse output. Information related to the pulse output includes, for example, the frequency of the pulse output, the duty ratio of the pulse output, etc. Since this information is important for process management, it is useful to be able to appropriately monitor information related to the pulse output.

[0070] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0071] 1 high frequency power supply device, 2 matching box, 3 plasma load, 5 pulse output monitor device, 21 Vpp detector, 22 filter, 51 first reference waveform generation unit, 52 second reference waveform generation unit, 53 in-period voltage waveform generation unit, 54 first similarity calculation unit, 55 second similarity calculation unit, 56 first judgment unit, 57 second judgment unit, 58 output unit.

Claims

1. A pulse output monitor device that outputs information about a pulse output when a pulse output is performed in which the shape of the envelope of the voltage waveform of a traveling wave voltage output from a high frequency power supply device to a load is pulsed, comprising: a voltage detector that detects a voltage at a position between the high frequency power supply device and the load; a first reference waveform generating unit that generates a first reference waveform serving as a reference waveform at a rising timing based on voltage information detected by the voltage detector during a first period near a rising timing of a pulse command signal that determines a shape of an envelope of a voltage waveform of the traveling wave voltage; a second reference waveform generating unit that generates a second reference waveform serving as a reference waveform at a falling timing of the pulse command signal based on voltage information detected by the voltage detector during a second period near the falling timing of the pulse command signal; an in-period voltage waveform generating unit that generates a voltage waveform within a predetermined period based on voltage information detected by the voltage detector for each predetermined time period; a first similarity calculation unit that calculates a similarity between the first reference waveform and the voltage waveform generated by the in-period voltage waveform generation unit for each predetermined time period; a second similarity calculation unit that calculates a similarity between the second reference waveform and the voltage waveform generated by the in-period voltage waveform generation unit for each predetermined time period; a first determination unit that determines a rising timing of a pulse output at a position of the voltage detector based on the similarity calculated by the first similarity calculation unit; a second determination unit that determines a falling timing of a pulse output at a position of the voltage detector based on the similarity calculated by the second similarity calculation unit; an output unit that outputs information related to pulse output based on a determination result of the first determination unit and a determination result of the second determination unit; A pulse output monitor device comprising:

2. the first reference waveform generating unit generates the first reference waveform based on voltage information detected multiple times; the second reference waveform generating unit generates the second reference waveform based on voltage information detected multiple times.

2. The pulse output monitor device according to claim 1.

3. the first period starts at a timing shifted by a predetermined first adjustment time from the rising timing of the pulse command signal and ends when a predetermined first detection time has elapsed; the second period starts at a timing shifted by a predetermined second adjustment time from the falling timing of the pulse command signal, and ends when a predetermined second detection time has elapsed.

3. The pulse output monitor according to claim 1 or 2.

4. The in-period voltage waveform generating unit a first-period voltage waveform generating unit that generates a voltage waveform within the first period based on voltage information detected within a period having the same duration as the first period; a second period voltage waveform generating unit that generates a voltage waveform within the second period based on voltage information detected within a period having the same duration as the second period; the first similarity calculation unit calculates a similarity between the first reference waveform and the voltage waveform generated by the first in-period voltage waveform generation unit; the second similarity calculation unit calculates a similarity between the second reference waveform and the voltage waveform generated by the second in-period voltage waveform generation unit; 4. The pulse output monitor device according to claim 1.

5. the output unit outputs information regarding pulse output based on the pulse command signal, the determination result of the first determination unit, and the determination result of the second determination unit.

5. A pulse output monitor device according to claim 1.

6. voltage information detected by the voltage detector is input to a first reference waveform generating unit, a second reference waveform generating unit, and an in-period voltage waveform generating unit via a filter; 6. A pulse output monitor device according to claim 1.

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