High-frequency power supply device

Abstract

Protection control is performed regardless of the output setting value of the traveling wave power during the repetition cycle. [Solution] A high-frequency power supply device 101 that outputs a traveling wave power PF having multiple power levels during a repeating period T toward a load, wherein the output set value PF corresponds to the elapsed time. set1 A first output setting unit 61 that sequentially outputs the following, an average power upper limit setting unit 71 that sets an average power upper limit for the average power value during the repetition period T, an instantaneous power upper limit setting unit 72 that sets an instantaneous allowable power value of the traveling wave power PF as an instantaneous power upper limit, within the range where the average power value of the traveling wave power output during the repetition period T does not exceed the average power upper limit, and the first output setting value PF set1 and instantaneous power limit PF high_limit The smaller of the two is the second output setting value PF. set2 A second output setting unit 80 outputs as the forward wave power value pf, and the second output setting value PF set2 It includes an output power control unit 90 that controls the output power to be equal to [a certain value].

Description

Technical Field

[0001] The present invention relates to a high-frequency power supply device that supplies power to a load such as a plasma processing apparatus that performs, for example, plasma etching or plasma CVD.

Background Art

[0002] Conventionally, in a plasma processing apparatus used in semiconductor manufacturing, a configuration has been adopted to control and output traveling-wave power PF. In such a plasma processing apparatus, with the increase in density and accuracy of thin film formation such as ashing and etching, a function capable of supplying high-frequency power to the plasma load in a pulsed state has been desired.

[0003] In particular, Low power PF, which is the minimum power required to maintain the generated plasma without extinguishing it avg , low , and High power PF required for thin film formation high are desired to be supplied periodically by two-level pulse power control.

[0004] Here, the two-level pulse power control will be described in detail. The average power value PF of the traveling-wave power PF in the two-level pulse power control corresponding to the plasma device avg can be expressed by Equation (1).

[0005] PF avg = D × PF high + (1 - D) × PF low ……(1) Here, D is the High output duty ratio (0 ≤ D ≤ 1). Also, PF low represents the power setting value of Low power PF low , and PF high represents the power setting value of PF high .

[0006] From Equation (1), the average power value PF when PF low = 0 avg can be expressed by Equation (2). PFavg =D×PF high ...(2) Furthermore, when the high output duty cycle D=0, the power PF is always low. low When a high output duty cycle D=1, the power PF is always high. high The following will be output.

[0007] In actual plasma processing equipment, the maximum rated instantaneous power value PF is the upper limit of the traveling wave power PF according to the equipment specifications. high_max High power PF exceeding high and Low Power PF low Setting this value is not possible as it may cause damage to the device. Also, the average power value PF is determined by the device specifications. avg The upper limit is the maximum rated average power value PF avg_max High power PF exceeding high and Low Power PF low Setting this is also not possible as it could damage the device.

[0008] In order to design a high-frequency power supply unit used in such plasma processing equipment that meets the above requirements, the maximum rated instantaneous power value PF, which depends on the withstand voltage, is determined. high_max and the maximum rated average power value PF, which depends on the loss tolerance of the element. avg_max It is possible to consider these separately. If the High output duty cycle D is small, the average power value PF avg This is because it becomes smaller, which in turn allows for the miniaturization of selected components.

[0009] Furthermore, in high-frequency power supply units used in conventional plasma processing equipment, reflective protection control is sometimes used as a protective control mechanism. Instantaneous power value PR of reflected wave power PR cur (The following is the reflected wave power value PR) cur If the value is large, there is a risk of damage to internal components of the power supply, so the instantaneous power value PF of the traveling wave power PF should be considered. cur (The following are forward wave power values ​​PF) cur ) needs to be reduced.

[0010] Therefore, conventional technology applied control methods to reduce reflected wave power PR. Specifically, the reflected wave power value PR cur If it exceeds a certain threshold, the traveling wave power value PF cur It reduced the absolute value of the reflection coefficient Γ |Γ|=√(PR cur / PF cur The forward wave power PF was reduced using a reflection protection threshold stored in response to the reflection coefficient Γ. Alternatively, a table was created showing the output power values ​​corresponding to the absolute value |Γ| of the reflection coefficient Γ, and the maximum power value calculated according to the absolute value |Γ| of the reflection coefficient Γ was used as the upper limit of the set power. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2014-167902 [Patent Document 2] Japanese Patent Publication No. 2014-207214 [Patent Document 3] Japanese Patent Publication No. 2014-209420 [Overview of the project] [Problems that the invention aims to solve]

[0012] By the way, even with reflective protection control in place, depending on the settings for the two-level pulse, there may be cases where proper protection control cannot be performed.

[0013] For example, the maximum rated instantaneous power value PF high_max = 50kW, maximum rated average power value PF avg_max Assuming =25kW, the setting conditions for the 2-level pulse are: • High power PF high = 50kW • Low power PF low = 10kW • High output duty cycle D = 0.4 Let's assume that.

[0014] In this case, according to equation (1), the average power value PF avg = 26kW, which is the maximum rated average power value PF. avg_max Since it exceeds 25kW, conventional reflection protection control alone cannot provide adequate protection. Therefore, in a high-frequency power supply that outputs a traveling wave power PF having multiple power levels during the repetition period toward the load, the traveling wave power value PF during the repetition period is... cur The maximum rated instantaneous power value PF high_max (In the example above, it should not exceed 50 kW), and the average power value PF of the traveling wave power PF during the repetition period should not exceed PF. avg The maximum rated average power value PF avg_max To prevent the output of the traveling wave power PF from exceeding (25 kW in the example above), it is necessary to control the output.

[0015] The present invention has been made in view of the above, and aims to provide a high-frequency power supply device that outputs traveling wave power having multiple levels of power values ​​to a load during a repeating cycle, and that can perform appropriate protection control regardless of the output set value. [Means for solving the problem]

[0016] The high-frequency power supply device of the embodiment is a high-frequency power supply device that outputs traveling wave power having multiple levels of power values ​​to a load by changing the output setting value of the traveling wave power one or more times during a predetermined repetition period, During the aforementioned repetition period, a forward wave power output unit amplifies the high-frequency signal and outputs it as forward wave power, A first output setting unit sequentially outputs a first output setting value corresponding to the elapsed time from the start of the repeating period, based on the output setting value of the traveling wave power during the repeating period. An average power upper limit setting unit sets an average power upper limit, which is the upper limit of the average power value of the forward wave power output during the aforementioned repeating period. An instantaneous power limit setting unit sets an instantaneous allowable power value of the traveling wave power as an instantaneous power limit to prevent the average power value from exceeding the average power limit, A second output setting unit outputs the smaller of the first output setting value and the instantaneous power upper limit value as the second output setting value, The system includes an output power control unit that controls the traveling wave power output unit so that the power value of the traveling wave power becomes equal to the second output set value. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a high-frequency power supply that can perform appropriate protection control regardless of the output setting value of the high-frequency power supply. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 shows an example of a high-frequency power supply system to which the high-frequency power supply device according to the present invention is applied. [Figure 2] Figure 2 is an explanatory diagram illustrating an example configuration of the high-frequency power supply device according to the first embodiment. [Figure 3] Figure 3 illustrates an example of the traveling wave power value PFcur during the repetition period T when performing two-level pulse power control. [Figure 4] Figure 4 is an explanatory diagram illustrating an example configuration of a high-frequency power supply device according to the second embodiment. [Figure 5] Figure 5 illustrates an example of how the average power upper limit PFavg_limit changes with respect to the absolute value |Γ| of the reflection coefficient Γ. [Figure 6] Figure 6 illustrates another example of the traveling wave power value PFcur during the repetition period T when performing two-level pulse power control. [Figure 7] Figure 7 is an explanatory diagram illustrating an example configuration of a high-frequency power supply device according to the third embodiment. [Figure 8] Figure 8 illustrates an example of how the average power limit PFavg_limit changes with respect to the reflected wave power value PRcur. [Figure 9] Figure 9 illustrates an example of the traveling wave power value PFcur during the repetition period T when performing 3-level pulse power control. [Modes for carrying out the invention]

[0019] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows an example of a high-frequency power supply system to which the high-frequency power supply device according to the present invention is applied. The high-frequency power supply system 100 supplies traveling wave power PF to workpieces such as semiconductor wafers and liquid crystal substrates to perform processing such as plasma etching.

[0020] As shown in Figure 1, the high-frequency power supply system 100 includes a high-frequency power supply unit 101, a transmission line 102, an impedance matching unit 103, a load connection unit 104, and a load 105. It is also possible to configure the system without using the impedance matching unit 103.

[0021] The high-frequency power supply unit 101 amplifies the high-frequency signal output from the oscillator and outputs a traveling wave power PF having an output frequency in the radio frequency band, which is then supplied to the load 105. The traveling wave power PF output from the high-frequency power supply unit 101 is supplied to the load 105 via a transmission line 102 configured as a coaxial cable, an impedance matching unit 103, and a load connection section 104 configured as a shielded copper plate.

[0022] Generally, this type of high-frequency power supply outputs a traveling wave power PF with frequencies of several hundred kHz or higher (for example, frequencies of 13 MHz, 40 MHz, etc.). Furthermore, as will be described later, the high-frequency power supply unit 101 is configured to output forward wave power having multiple power levels to the load during a predetermined repetition period T by changing the output setting value of the forward wave power PF once or more during the repetition period T. For example, if the output setting value of the traveling wave power PF is changed once during the repetition period T, the two-level pulse power control described above will be performed. Furthermore, if the output setting value of the traveling wave power PF is changed twice during the repetition period T, three-level pulse power control will be performed. In this way, the high-frequency power supply unit 101 is capable of performing so-called multi-level pulse power control.

[0023] The impedance matcher 103 matches the impedance between the high-frequency power supply 101 and the load 105. More specifically, for example, if the impedance seen from the output terminal of the high-frequency power supply 101 towards the high-frequency power supply 101 side (output impedance) is designed to be, for example, 50Ω, and the high-frequency power supply 101 is connected to the input terminal of the impedance matcher 103 via a transmission line 102 with a characteristic impedance of 50Ω, then the impedance matcher 103 converts the impedance seen from the input terminal of the impedance matcher 103 towards the load 105 side to 50Ω.

[0024] Load 105 is a device equipped with a processing section for processing (etching, CVD, etc.) workpieces such as wafers and liquid crystal substrates that are brought into the processing section. To process the workpiece, Load 105 introduces a plasma discharge gas into the processing section and applies traveling wave power PF (traveling wave voltage VF) supplied from the high-frequency power supply unit 101 to the plasma discharge gas, thereby discharging the plasma discharge gas and changing it from a non-plasma state to a plasma state. The workpiece is then processed using this plasma.

[0025] [1] First Embodiment Figure 2 is an explanatory diagram illustrating an example configuration of the high-frequency power supply device according to the first embodiment. As shown in Figure 2, the high-frequency power supply unit 101 includes a traveling wave power output unit 10, a low-pass filter 20, a directional coupler 30, a power calculation unit 40, a first output setting unit 60, an upper limit setting unit 70, a second output setting unit 80, and an output control unit 90. In the first embodiment, the two-level pulse power control described above will be explained.

[0026] The traveling wave power output unit 10 includes a DC power supply (not shown), an oscillator, an amplifying element, etc. It amplifies the high-frequency signal output from the oscillator using the DC power output from the DC power supply and the amplifying element, outputting high-frequency power having an output frequency in the radio frequency band (RF band). The amplification method of the traveling wave power output unit 10 is not limited. For example, it may be a so-called linear amplifier method such as Class A or Class B, or a so-called switching amplifier method such as Class D. Furthermore, as the amplifying element of the traveling wave power output unit 10, for example, an FET or a transistor may be used.

[0027] In this case, the high-frequency power flowing from the high-frequency power supply 101 to the load 105 is called the forward wave power PF. The high-frequency power reflected by the load 105 and returning to the high-frequency power supply 101 is called the reflected wave power PR. The instantaneous power value of the forward wave power PF is called the forward wave power value PF. cur The instantaneous power value of the reflected wave power PR is the reflected wave power value PR cur Furthermore, these types of high-frequency power supplies generally output traveling wave power PF with frequencies of several hundred kHz or higher (for example, frequencies of 13 MHz, 40 MHz, etc.).

[0028] Furthermore, the output of the traveling wave power output unit 10 is controlled by the output control unit 90. Specifically, the traveling wave power output unit 10 receives an output control signal P output from the output control unit 90. cnt Based on this, for example, by changing the amplitude of a high-frequency signal, the power value of the output forward wave power PF is the forward wave power value PF. cur Control. The traveling wave power PF output from the traveling wave power output unit 10 is supplied to the load 105 via a low-pass filter 20, a directional coupler 30, and an impedance matching unit 103, which are mainly used to remove harmonics.

[0029] The low-pass filter 20 removes harmonic components from the output of the traveling wave power output section 10. Alternatively, a band-pass filter may be used instead of the low-pass filter 20. Furthermore, the low-pass filter 20 may be omitted in some cases.

[0030] The directional coupler 30 is inserted between the traveling wave power output unit 10 and the load 105 (as well as the impedance matching unit 103 and the load connection unit 104), and outputs a traveling wave detection signal Vf which includes information on the traveling wave power PF output from the traveling wave power output unit 10, and a reflected wave detection signal Vr which includes information on the reflected wave power PR reflected by the load. Strictly speaking, the traveling wave power PF output from the traveling wave power output unit 10 is slightly attenuated when it passes through the low-pass filter 20 and the directional coupler 30. However, for the sake of simplicity, as shown in Figure 2, the traveling wave power PF output from the traveling wave power output unit 10 and the traveling wave power PF that passes through the directional coupler 30 are given the same sign.

[0031] The power calculation unit 40 includes a traveling wave power calculation unit 41 and a reflected wave power calculation unit 42. The traveling wave power calculation unit 41 calculates the traveling wave power value PF based on the traveling wave detection signal Vf. cur The reflected wave power calculation unit 42 calculates the reflected wave power value PR based on the reflected wave detection signal Vr. cur Perform the calculation and output the result.

[0032] The traveling wave power value PF output from the traveling wave power calculation unit 41 cur and the reflected wave power value PR output from the reflected wave power calculation unit 42 cur It can output to an external source, for example, by displaying it on a monitor.

[0033] The first output setting unit 60 sets a preset High Power PF. high Low power PF low Based on the high output duty cycle D and the repetition period T, a first output setpoint PF is determined. set1 The settings are configured and output to the second output setting unit 80. These data are set by the user and stored, for example, in the first output setting unit 60. Alternatively, they are transmitted from an external control device to the first output setting unit 60 by a communication means (not shown). To further explain, the first output setting unit 60 sets the output setting value of the traveling wave power PF with the repetition period T as described above (High power PF high Based on the above, a first output setpoint PF is determined according to the elapsed time from the start of the repetition period T. set1 The following are output sequentially. This enables two-level pulse power control. However, as will be described later, the second output setting unit 80 sets the first output setting value PF set1 The size may be limited.

[0034] The upper limit setting unit 70 includes an average power upper limit setting unit 71 and an instantaneous power upper limit setting unit 72. Note that the maximum rated instantaneous power value PF in this embodiment is... high_max It is 50kW, and the maximum rated average power value is PF. avg_max Let's assume it's 25kW.

[0035] The average power upper limit setting unit 71 sets an average power upper limit PF that is appropriate for the actual operating conditions. avg_limit The value is set and output to the instantaneous power upper limit setting unit 72. In this embodiment, the average power upper limit PF is set. avg_limit Let's assume it's 25kW. That is, the maximum rated average power value PF. avg_max The average power upper limit PF avg_limit Set it as follows. This average power upper limit PF avg_limit This allows for safer protection and control, with a maximum rated average power value PF. avg_max These are protection control parameters that allow you to set the following values. Note that this average power limit value PF avg_limit High power PF high Low power PF low And it is determined according to the High output duty cycle D, etc. Therefore, the average power upper limit setting unit 71 sets the average power upper limit PF avg_limit To determine this, for example, the average power value PF avgLow power PF low The High output duty cycle D and other parameters may also be obtained from the first output setting unit 60. Also, the average power limit PF avg_limit For example, this may be stored in the average power upper limit setting unit 71 in advance, or it may be provided to the average power upper limit setting unit 71 from an external control device or the like by a communication means (not shown).

[0036] The instantaneous power upper limit setting unit 72 receives the Low power PF output from the first output setting unit 60. low The High output duty cycle D is input. Also, the average power upper limit PF output from the average power upper limit setting unit 71 is input. avg_limit Enter the input. The instantaneous power limit setting unit 72 sets the input Low power PF low High output duty cycle D and average power limit PF avg_limit Set the upper limit of the instantaneous power of the corresponding output forward wave power PF, and the instantaneous power upper limit PF high_limit The output is then directed towards the second output setting unit 80. This is the maximum rated instantaneous power value PF high_max To enable safer protection and control, the maximum rated instantaneous power value PF high_max These are protection control parameters that allow you to set the following values. The setting method will be described later.

[0037] The second output setting unit 80 receives the input first output setting value PF set1 and instantaneous power limit PF high_limit Compare the two values, and use the smaller one as the second output setting value PF. set2 The output is then sent to the output control unit 90.

[0038] The output control unit 90 sets the second output set value PF. set2 and the traveling wave power value PF cur Based on the output control signal P cnt The output is directed towards the traveling wave power output unit 10. The output control unit 90 includes a subtractor 91 and a compensation unit 92.

[0039] The subtractor 91 controls the second output setpoint PF.set2 From the traveling wave power value PF cur Subtract to obtain the second output set value PF set2 And the traveling wave power value PF cur Output the difference with the compensation unit 92.

[0040] The compensation unit 92 is based on the difference between the second output set value PF set2 And the traveling wave power value PF cur Based on the difference, the traveling wave power value PF cur Becomes equal to the second output set value PF set2 Output control signal P so that cnt Output to the traveling wave power output unit 10. As a result, the output of the traveling wave power output unit 10 is finally controlled to be equal to the second output set value PF set2 Becomes equal to.

[0041] Next, a specific example of the operation of the first embodiment will be described. In the following description, the maximum rated instantaneous power value PF high_max = 50 kW, average power upper limit value PF avg_limit = 25 kW. Also, the setting conditions for the two-level pulse are High power PF high = 50 kw, Low power PF low = 10 kW, High output duty ratio D = 0.5.

[0042] Figure 3 is an example of the traveling wave power value PF cur During the repetition period T when performing two-level pulse power control. Using this Figure 3, the operation of the first embodiment will be described.

[0043] Figure 3(A) shows the first output set value PF output from the first output setting unit 60 to the second output setting unit 80 set1 Is a diagram schematically showing the traveling wave power value PF cur When it is assumed that it is input to the output control unit 90 without passing through the second output setting unit 80. That is, it corresponds to the case where the first output set value PF set1 Is not restricted by the second output setting unit 80. Also, Figure 3(B) shows that the first output set value PF is obtained by the second output setting unit 80set1 The forward wave power value PF when it is limited cur This is a schematic diagram illustrating the concept. Note that the amplitude of the signal waveform in Figure 3 does not accurately represent the amplitude of the traveling wave voltage VF, but rather the traveling wave power value PF. cur This diagram illustrates the size of the object in an easy-to-understand way.

[0044] First, under the conditions shown in Figure 3(A), the average power value PF avg =D×PF high +(1-D)×PF low =30kW, which is the average power limit PF avg_limit (This exceeds 25kW) High Power PF high The output needs to be limited.

[0045] In this embodiment, the instantaneous power limit PF high_limit High power PF high This limits the average power limit PF. avg_limit However, the instantaneous power limit PF must satisfy the relationship in equation (3). high_limit You just need to calculate that. PF avg_limit =D×PF high_limit +(1-D)×PF low ...(3)

[0046] In other words, the instantaneous power limit PF high_limit This can be expressed by equation (4). In this way, the average power value PF avg is the average power upper limit PF avg_limit It does not exceed that. PF high_limit ={PF avg_limit -(1-D)×PF low} / D ……(4)

[0047] In this embodiment, the instantaneous power limit PF high_limit This becomes 40kW. This instantaneous power limit value PF high_limit This is output from the instantaneous power upper limit setting unit 72 and input to the second output setting unit 80. Therefore, the first output setting value PF corresponding to 50kW is set from the first output setting unit 60.set1 Even if this is output, the second output setting value PF set2 Since it is limited to 40kW, the actual output waveform is as shown in Figure 3(B), PF high =Limited to 40kW

[0048] By adopting the above configuration, a high-frequency power supply device that outputs traveling wave power having multiple power levels to the load during a repetition period T has a traveling wave power value PF of the traveling wave power during the repetition period. cur The maximum rated instantaneous power value PF high_max The average power value of the traveling wave power during the repetition period should not exceed the average power upper limit PF. avg_limit The output of the forward wave power can be controlled so as not to exceed a certain limit. In other words, in a high-frequency power supply device that outputs traveling wave power having multiple power levels during the repetition cycle to a load, appropriate protection control can be performed regardless of the output setpoint.

[0049] [2] Second embodiment Figure 4 is an explanatory diagram illustrating an example configuration of a high-frequency power supply device according to the second embodiment. In Figure 4, the same reference numerals are used for parts that are the same as those in the first embodiment in Figure 2. As shown in Figure 4, the high-frequency power supply unit 101A includes a traveling wave power output unit 10, a low-pass filter 20, a directional coupler 30, a power calculation unit 40, a first output setting unit 60, an upper limit setting unit 70A, a second output setting unit 80, and an output control unit 90.

[0050] In this case, the difference between the second embodiment and the first embodiment is that the forward wave power value PF calculated by the forward wave power calculation unit 41 of the power calculation unit 40 is set to the average power upper limit value setting unit 71A of the upper limit value setting unit 70A. cur and the reflected wave power value PR calculated by the reflected wave power calculation unit 42 cur At the point where the input is received, the average power upper limit setting unit 71A of the upper limit setting unit 70A is set to the traveling wave power value PF cur and reflected wave power value PR curBased on this, the absolute value of the reflection coefficient Γ, |Γ|, is calculated, and the average power upper limit PF is calculated based on the result of this calculation. avg_limit The point is to set that.

[0051] In the second embodiment, the average power upper limit setting unit 71A sets the traveling wave power value PF. cur and reflected wave power value PR cur Enter the following, and the absolute value of the reflection coefficient Γ, |Γ|, is √(PR cur / PF cur The calculation is performed using ) and the average power upper limit PF is then determined based on the calculation result. avg_limit Set it. In other words, the average power upper limit PF avg_limit This value changes depending on the absolute value |Γ| of the reflection coefficient Γ. Roughly speaking, as the absolute value |Γ| of the reflection coefficient Γ increases, the upper limit of the average power PF decreases. avg_limit Set it so that it becomes smaller. Because the reflected wave power value PR cur If the reflection coefficient Γ is large, there is a risk of damage to internal components of the power supply, and the average power limit PF is determined according to the magnitude of the absolute value of the reflection coefficient Γ||. avg_limit By reducing the average power value PF, avg Because it can be made smaller. Average power limit PF avg_limit By setting this to the optimal value, the instantaneous power limit PF can be adjusted. high_limit This is also optimized, allowing for more suitable output control of the traveling wave power PF.

[0052] Figure 5 shows the average power upper limit PF for the absolute value |Γ| of the reflection coefficient Γ. avg_limit This is a diagram illustrating an example of change. In this embodiment, the maximum rated average power value PF avg_max The power is 25kW, and when the absolute value of the reflection coefficient Γ |Γ| is 0, the average power upper limit PF avg_limit The maximum rated average power value PF avg_max It is made to have the same value as [the other value].

[0053] As shown in Figure 5, in the range of absolute value of the reflection coefficient Γ |Γ| = 0 to 0.2, the reflected wave power PR is small, and the influence of the reflected wave power PR is considered to be small, so the upper limit of the average power PF avg_limit It's set to 25kW.

[0054] Furthermore, in the range of absolute values ​​of the reflection coefficient Γ |Γ|=0.2 to 1, the reflected wave power PR gradually increases, and the effect of the reflected wave power PR can no longer be ignored, thus limiting the average power to the upper limit PF. avg_limit The power gradually decreases from 25 kW, and when the absolute value of the reflection coefficient Γ becomes |Γ|=1, it becomes 5 kW.

[0055] Note that the average power limit is PF. avg_limit The settings can be configured using either a formula or a table. Using a formula, the average power upper limit PF avg_limit When setting this, it can be expressed by equations (5) and (6). When 0 ≤ |Γ| ≤ 0.2, PF avg_limit =25[kW] ……(5) When 0.2 < |Γ| ≤ 1, PF avg_limit =30-(20 / 0.8)×|Γ|[kW] ……(6)

[0056] Using a table, the average power upper limit PF avg_limit When setting this, for example, the average power upper limit PF corresponds to each of the absolute values ​​of the reflection coefficient Γ |Γ| = 0 to 0.2, greater than 0.2 to 0.4, greater than 0.4 to 0.6, greater than 0.6 to 0.8, and greater than 0.8 to 1. avg_limit You can use a table containing five data points: 25kW, 20kW, 15kW, 10kW, and 5kW. Of course, you are not limited to the above and can further subdivide it if you wish.

[0057] Furthermore, the average power upper limit PF is calculated by linear interpolation using the data stored in the table. avg_limit You may also calculate the following. For example, if the absolute value of the reflection coefficient Γ is |Γ| = 0.5, then the average power upper limit PF when the absolute value of the reflection coefficient Γ is |Γ| is 0.4 can be calculated. avg_limitThe data (20kW) and the average power limit PF when the absolute value of the reflection coefficient Γ |Γ| is 0.6 avg_limit Based on the data (15kW), the average power upper limit PF was calculated by linear interpolation. avg_limit You may also calculate the average power upper limit PF. In this case, the average power upper limit PF may be calculated. avg_limit This will be 17.5kW.

[0058] Next, a specific example of the operation of the second embodiment will be described. In the following explanation, the maximum rated instantaneous power value PF is used. high_max Let's assume it's = 50kW. Also, the setting conditions for the 2-level pulse are High power PF. high = 50kW, Low Power PF low Assume the power output is 10kW and the high power duty cycle D=0.5. Also, assume the absolute value of the reflection coefficient Γ|| is 0.6. Therefore, the average power upper limit PF is... avg_limit This will be 15kW.

[0059] Figure 6 shows the traveling wave power value PF during the repetition period T when performing two-level pulse power control. cur This is another example. The operation of the second embodiment will be explained using Figure 6.

[0060] Figure 6(A) shows the first output setting value PF output from the first output setting unit 60 to the second output setting unit 80. set1 The forward wave power value PF is calculated assuming that the signal is input to the output control unit 90 without going through the second output setting unit 80. cur This diagram schematically illustrates the first output setting value PF, which is set by the second output setting unit 80. set1 This corresponds to a case where there are no restrictions. Figure 6(B) also shows that the second output setting unit 80 sets the first output setting value PF. set1 The forward wave power value PF when it is limited cur This is a schematic diagram illustrating the concept. Note that the amplitude of the signal waveform in Figure 6 does not accurately represent the amplitude of the traveling wave voltage VF, but rather the traveling wave power value PF. cur This diagram illustrates the size of the object in an easy-to-understand way.

[0061] First, under the conditions shown in Figure 6(A), the average power value PF avg =D×PF high +(1-D)×PF low =30kW, which is the average power limit PF avg_limit (This exceeds 15kW) High Power PF high The output needs to be limited.

[0062] In this embodiment, the instantaneous power limit PF high_limit High power PF high This limits the average power limit PF. avg_limit However, the instantaneous power limit PF must satisfy the relationship in equation (3). high_limit You just need to calculate that. In other words, from equation (4), the instantaneous power limit PF high_limit ={PF avg_limit -(1-D)×PF low} / D = 20kW. This instantaneous power limit PF high_limit This is output from the instantaneous power upper limit setting unit 72 and input to the second output setting unit 80. Therefore, the first output setting value PF corresponding to 50kW is set from the first output setting unit 60. set1 Even if this is output, the second output setting value PF set2 Since it is limited to 20kW, the actual output waveform is as shown in Figure 3(B), PF high =Limited to 20kW

[0063] As described above, the same effects as in the first embodiment can be obtained in the second embodiment as well. Furthermore, compared to the first embodiment, it is possible to control the output of the traveling wave power while taking into account the magnitude of the absolute value |Γ| of the reflection coefficient Γ, thus enabling more appropriate protection control.

[0064] [3] Third embodiment Figure 7 is an explanatory diagram illustrating an example configuration of a high-frequency power supply device according to the third embodiment. In Figure 7, the same reference numerals are used for parts that are the same as those in the second embodiment of Figure 4. As shown in Figure 7, the high-frequency power supply unit 101B includes a traveling wave power output unit 10, a low-pass filter 20, a directional coupler 30, a power calculation unit 40, a first output setting unit 60, an upper limit setting unit 70B, a second output setting unit 80, and an output control unit 90.

[0065] In this case, the difference between the third embodiment and the second embodiment is that the upper limit setting unit 70B is set to the reflected wave power value PR calculated by the reflected wave power calculation unit 42 of the power calculation unit 40. cur The input is, but the traveling wave power calculation unit 41 calculates the traveling wave power value PF. cur The point that the input is not, the average power upper limit setting unit 71B of the upper limit setting unit 70B is the reflected wave power value PR cur Based on the average power upper limit PF avg_limit The point is to set that.

[0066] The upper limit setting unit 70B of the high-frequency power supply device of the third embodiment sets the reflected wave power value PR cur Enter the reflected wave power value PR cur Based on the average power upper limit PF avg_limit Set it. In other words, the average power upper limit PF avg_limit PR is the reflected wave power value. cur It varies depending on the reflected wave power value PR. cur As the average power limit PF increases avg_limit Set it so that it becomes smaller. Because the reflected wave power value PR cur If the value is large, there is a risk of damage to internal components of the power supply, etc., and the reflected wave power value PR cur The average power limit PF is determined according to the magnitude. avg_limit By reducing the average power value PF, avg Because it can be made smaller. Average power limit PF avg_limit By setting this to the optimal value, the instantaneous power limit PF can be adjusted. high_limit This is also optimized, allowing for more suitable output control of the traveling wave power PF.

[0067] Figure 8 shows the reflected wave power value PR cur The average power upper limit PF foravg_limit This is a diagram illustrating an example of change. In this embodiment, the maximum rated average power value PF avg_max It is 25kW, and the reflected wave power value PR cur When it is 0, the average power upper limit PF avg_limit The maximum rated average power value PF avg_max It is made to have the same value as [the other value].

[0068] The second and third embodiments are defined by the average power upper limit PF. avg_limit Is it set based on the absolute value |Γ| of the reflection coefficient Γ, or the reflected wave power value PR? cur Since the only difference is whether or not it is set based on [the specified method], a detailed explanation of Figure 7 will be omitted, but the same effects as in the first embodiment can be obtained in the third embodiment as well. Furthermore, according to the third embodiment, the reflected wave power value PR is lower than in the first embodiment. cur Since output control of forward wave power can be performed while taking this into consideration, more appropriate protection control can be implemented.

[0069] [4] Fourth Embodiment Although the embodiments described above corresponded to two-level pulse power control, the present invention can also be similarly applied to multi-level pulse power control.

[0070] Figure 9 shows the traveling wave power value PF during the repetition period T when 3-level pulse power control is performed. cur This is one example. In the example shown in Figure 9, the forward wave power value PF is calculated when performing 3-level pulse power control as an example of multi-level pulse power control. cur This is an example. Note that the amplitude of the signal waveform in Figure 9 does not accurately represent the amplitude of the traveling wave voltage VF, but rather the traveling wave power value PF. cur This diagram illustrates the size of the object in an easy-to-understand way.

[0071] In the example in Figure 9, the pulse level is defined as the high power PF, which is the power of the high-level pulse P1. highMid power PF is the power of the Mid level pulse P2. Mid Low power PF is the power of the low-level pulse P3. low The relationship between the High output duty cycle D1, Mid output duty cycle D2, Low output duty cycle D3, and repetition period T is illustrated. Even when performing such three-level pulse power control, it can be achieved by changing the output conditions of the first output setting unit 60 in the configuration examples of the high-frequency power supply device shown in the first to third embodiments.

[0072] For example, High Power PF high =30kW, Mid power PF Mid =30kW=20kW, Low power PF low If the power output duty cycle is 10kW, the High output duty cycle D1=0.45, the Mid output duty cycle D2=0.25, and the Low output duty cycle D3=0.30, then the average power value PF will be... avg This equals 21.5kW. In this case, similar to the second embodiment, the average power upper limit PF is determined according to the magnitude of the absolute value |Γ| of the reflection coefficient Γ. avg_limit Let's assume we change the value of the reflection coefficient Γ. If the absolute value of the reflection coefficient Γ is |Γ| = 0.4, then the upper limit of the average power PF avg_limit = 20kW (see Figure 5). In other words, the average power value PF avg is the average power upper limit PF avg_limit This would exceed [a certain threshold].

[0073] Here, the mean prime upper limit PF avg_limit The one that exceeds this is High Power PF high Only, Mid Power PF Mid and Low Power PF low This is the average power upper limit PF avg_limit It does not exceed [a certain value]. Therefore, High Power PF high By limiting the average power value PF, avg The solution is to reduce it. Specifically, High Power PF high The limit should be 26.6kW or less.

[0074] Thus, even when performing 3-level pulse power control, the same effects as those of the first to third embodiments can be obtained. Furthermore, the same approach can be used for protection control in N-level pulse power control with 4 or more levels.

[0075] [5] Note The present invention can also be in the following other embodiments.

[0076] [5.1] Other aspects of the first aspect A high-frequency power supply device that outputs traveling wave power having multiple power levels to a load by changing the output setting value of the traveling wave power once or more during a predetermined repetition period, During the aforementioned repetition period, a forward wave power output unit amplifies the high-frequency signal and outputs it as forward wave power, A first output setting unit sequentially outputs output setting values ​​corresponding to the elapsed time from the start of the repeating period, based on the output setting value of the traveling wave power during the repeating period. An average power upper limit setting unit sets an average power upper limit, which is the upper limit of the average power value of the forward wave power output during the aforementioned repeating period. An instantaneous power limit setting unit sets an instantaneous allowable power value of the traveling wave power as an instantaneous power limit to prevent the average power value from exceeding the average power limit, A second output setting unit outputs the smaller of the first output setting value and the instantaneous power upper limit value as the second output setting value, The system is characterized by comprising: an output power control unit that controls the traveling wave power output unit so that the power value of the traveling wave power becomes equal to the second output set value.

[0077] According to the above embodiment, in a high-frequency power supply device that outputs traveling wave power having multiple power levels to a load during a repeating cycle, the output of the traveling wave power can be controlled such that the instantaneous power value of the traveling wave power during the repeating cycle does not exceed the instantaneous power upper limit, and the average power value of the traveling wave power during the repeating cycle does not exceed the average power upper limit. In other words, in a high-frequency power supply device that outputs traveling wave power having multiple power levels during the repetition cycle to a load, appropriate protection control can be performed regardless of the output setpoint. For example, even if the output setting value for the traveling wave power during the repetition period is not appropriate and the setting is made such that the average power value of the traveling wave power exceeds the average power upper limit, the output is controlled so that the average power value of the traveling wave power does not exceed the average power upper limit, thereby preventing damage to the elements inside the traveling wave power output section.

[0078] [5.2] Second Other Mode A second, other embodiment of a high-frequency power supply device is characterized by changing the average power limit based on the magnitude of the reflected wave power or the absolute value of the reflection coefficient.

[0079] According to the above embodiment, if the magnitude of the reflected wave power or the absolute value of the reflection coefficient increases, there is a risk that elements inside the forward wave power output section (e.g., switching elements) may be damaged. Therefore, if the average power upper limit can be changed according to the magnitude of the reflected wave power or the absolute value of the reflection coefficient, the average power upper limit can be lowered when the magnitude of the reflected wave power or the absolute value of the reflection coefficient increases. Therefore, according to the above embodiment, even if the magnitude of the reflected wave power or the absolute value of the reflection coefficient changes, the output of the traveling wave power can be controlled in accordance with the magnitude of the reflected wave power or the absolute value of the reflection coefficient, such that the instantaneous power value of the traveling wave power during the repetition period does not exceed the instantaneous power upper limit, and the average power value of the traveling wave power does not exceed the average power upper limit.

[0080] [5.3] A third other aspect A third other embodiment of a high-frequency power supply device relates to an average power value during the repetition period, characterized in that the average power value during the repetition period is a power value calculated based on the output setpoint of each power value of multiple levels of power values ​​during the repetition period and the duty cycle of the interval corresponding to each power value.

[0081] According to the above embodiment, an average power value can be determined even if the output setting value of the traveling wave power is changed two or more times during a predetermined repetition period.

[0082] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented 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 variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0083] 10 Traveling wave power output section 20 Low-pass filters 30 Directional coupler 40 Power calculation section 41 Traveling wave power calculation section 42 Reflected wave power calculation section 60 First output setting section 70 Upper limit setting section 71 Average power upper limit setting section 72 Instantaneous power limit setting unit 80 Second output setting section 90 Output control unit 100 High-Frequency Power Supply Systems 101 High frequency power supply equipment 102 Transmission line 103 Impedance Matcher 104 Load connection section 105 load D High Output Duty Cycle D1 High Output Duty Cycle D2 Mid Output Duty Cycle D3 Low Output Duty Cycle P1 High-Level Pulse P2 MiD level pulse P3 Low-Level Pulse PF avgAverage power value PF high_limit Instantaneous power limit PF avg_limit Average power limit PF set1 First output setting value PF set2 Second output setting value PFcur (Forward Wave Power Value) PRcur reflected wave power value T is the repetition period. Vf forward wave detection signal Vr reflected wave detection signal

Claims

1. A high-frequency power supply device that outputs traveling wave power having multiple power levels to a load by changing the output setting value of the traveling wave power one or more times during a predetermined repetition period, During the aforementioned repetition period, a forward wave power output unit amplifies the high-frequency signal and outputs it as forward wave power, A first output setting unit sequentially outputs a first output setting value corresponding to the elapsed time from the start of the repeating period, based on the output setting value of the traveling wave power during the repeating period. An average power upper limit setting unit sets an average power upper limit, which is the upper limit of the average power value of the forward wave power output during the aforementioned repeating period. An instantaneous power limit setting unit sets an instantaneous allowable power value of the traveling wave power as an instantaneous power limit to prevent the average power value from exceeding the average power limit, A second output setting unit outputs the smaller of the first output setting value and the instantaneous power upper limit value as the second output setting value, An output power control unit controls the traveling wave power output unit so that the power value of the traveling wave power becomes equal to the second output setting value, A high-frequency power supply unit equipped with this device.

2. The average power limit is changed based on the magnitude of the reflected wave power or the absolute value of the reflection coefficient. The high-frequency power supply device according to claim 1.

3. The average power value during the repetition period is a power value calculated based on the output setpoint of each power value at multiple levels during the repetition period and the duty cycle of the interval corresponding to each power value. A high-frequency power supply device according to claim 1 or claim 2.

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