High-frequency power

Abstract

To perform protection control regardless of an output set value of progressive wave power of a repetition period.SOLUTION: The high-frequency power supply device 101 outputs progressive wave power PF having a plurality of levels of power values during a repetition period T to a load, and includes an instantaneous power upper limit setting unit 50 that sets a first instantaneous power upper limit value Pmax, a first output setting unit 60 that sequentially outputs an output power set value Pfset corresponding to an elapsed time, a coefficient setting unit 61 that sets an output power coefficient k within a range in which an average power value during the repetition period does not exceed an average power upper limit value, a multiplication unit 70 that outputs a second instantaneous power upper limit value k·Pmax obtained by multiplying the first instantaneous power upper limit value Pmax by the output power coefficient k, a second output setting unit 80 that outputs a second output set value PFset2 that is a smaller one of the first instantaneous power upper limit value Pmax and the second instantaneous power upper limit value k·Pmax, and an output power control unit 90 that performs control so that a progressive wave power value pf becomes equal to the second output set value PFset2.SELECTED DRAWING: Figure 2

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 plasma etching or plasma CVD. [Background technology]

[0002] Conventionally, plasma processing equipment used in semiconductor manufacturing has been configured to control and output traveling wave power PF. With the trend toward higher density and higher precision in thin film deposition during ashing and etching, such plasma processing equipment is required to have the ability to supply high frequency power in pulsed form to the plasma load.

[0003] In particular, the minimum power required to maintain the generated plasma without extinguishing it is called low power P Low and the high power P required for thin film generation. High There is a demand for a two-level pulse power control that periodically supplies

[0004] Here, the two-level pulse power control will be described in detail. Average power value P in two-level pulse power control for plasma equipment avg can be expressed by the following equation (1).

[0005] P avg =D×P High +(1-D)×P Low ……(1) Here, D is the high output duty ratio (0≦D≦1).

[0006] where P Low When = 0, the average power value P avg becomes as follows: P avg =D×P High Also, when the high output duty ratio D=0, the low power P Lowis output, and when the high output duty ratio D=1, the high power P High will be output.

[0007] In actual plasma processing equipment, the average power value P avg The upper limit of P avgmax High power P High and Low power P Low It is not possible to set the

[0008] In order to optimally design a high frequency power supply device used in such a plasma processing apparatus to satisfy the above requirements, the maximum rated power P Highmax and the average power upper limit P, which depends on the loss tolerance of the element. avgmax It may be possible to consider these separately. If the high output duty ratio D is small, the average power value P avg This is because the size of the selected components can be reduced accordingly.

[0009] Furthermore, in a high frequency power supply device used in a conventional plasma processing apparatus, a reflection protection control is sometimes used as a protection control. If the reflected power PR is large, there is a risk that elements inside the power supply may be damaged, and therefore a mechanism is required to suppress the power value pf of the forward power PF (hereinafter referred to as the forward power value pf).

[0010] For this reason, conventional technology has applied a control method for suppressing the power value pr of the detected reflected wave power PR (hereinafter referred to as the reflected wave power value pr). Specifically, when the reflected wave power value pr exceeds a certain threshold, the forward wave power value pf is suppressed. Alternatively, the forward wave power pf is suppressed using a reflection protection threshold value stored corresponding to the absolute value of the reflection coefficient Γ, |Γ| = √(pr / pf). Alternatively, the available output power values ​​corresponding to the absolute value of the reflection coefficient Γ, |Γ|, are compiled into a table, and the maximum power value corresponding to the calculated absolute value of the reflection coefficient Γ, |Γ|, is set as the upper limit of the set power. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-167902 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-207214 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-209420 Summary of the Invention [Problem to be solved by the invention]

[0012] However, even if reflection protection control is performed, there are cases where appropriate protection control cannot be performed depending on the setting conditions of the two-level pulse.

[0013] For example, the maximum rated power P Highmax = 50 kW, average power upper limit P avgmax = 25kW, and the setting conditions for the two-level pulse are: ·High power P High =50kw ·Low power P Low =10kW High output duty ratio D=0.4 Let's say.

[0014] In this case, according to equation (1), the average power value P avg = 26 kW, and the average power upper limit P avgmax =25kW, so that appropriate protection control cannot be performed by the reflection protection control of the prior art alone. Therefore, in a high frequency power supply device that outputs a forward power PF having multiple levels of power values ​​during a repetition period to a load, the instantaneous power value of the forward power during the repetition period is set to the maximum rated power P Highmax (In the above example, 50 kW) and the average power value of the forward power PF during the repetition period is set to the average power upper limit value P avgmax It is necessary to control the output of the forward power PF so that it does not exceed the specified value (25 kW in the above example).

[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 ​​during a repetition period to a load, and that can perform appropriate protection control regardless of the output setting value. [Means for solving the problem]

[0016] A high frequency power supply device according to the present disclosure is a high frequency power supply device that outputs forward power having a plurality of power levels to a load during a predetermined repetition period by changing an output setting value of forward power at least once during the repetition period, a forward power output unit that amplifies a high frequency signal and outputs the amplified signal as forward power during the repetition period; an instantaneous power upper limit value setting unit that sets an instantaneous allowable power value of the forward power as a first instantaneous power upper limit value; a first output setting unit that sequentially outputs a first output setting value according to the elapsed time from the start point of the repetition period based on the output setting value of the forward wave power during the repetition period; a coefficient setting unit that sets an output power coefficient, which is a coefficient by which the first instantaneous power upper limit value is multiplied, within a range in which an average power value of forward wave power output during the repetition period does not exceed a predetermined average power upper limit value; a multiplication unit that multiplies the first instantaneous power upper limit value by the output power coefficient and outputs the result as a second instantaneous power upper limit value; a second output setting unit that outputs the smaller of the first output setting value and the second instantaneous power upper limit value as a second output setting value; an output power control unit that controls the forward power output unit so that the forward power is equal to the second output setting value; [Effects of the Invention]

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

[0018] [Figure 1] FIG. 1 is a diagram showing an example of a high frequency power supply system to which a high frequency power supply device according to the present invention is applied. [Figure 2] FIG. 2 is an explanatory diagram of a configuration example of the high frequency power supply device of the first embodiment. [Figure 3] FIG. 3 is an explanatory diagram of a specific example of the coefficient table according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of output of the forward wave power value pf during the repetition period T when two-level pulse power control is performed. [Figure 5] FIG. 5 is an explanatory diagram of a specific example of a coefficient table according to a modification of the first embodiment. [Figure 6] FIG. 6 is an explanatory diagram of a configuration example of a high frequency power supply device according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating the change in the first upper limit value Pmax of instantaneous power relative to the absolute value |Γ| of the reflection coefficient Γ. [Figure 8] FIG. 8 is an explanatory diagram of a configuration example of a high frequency power supply device according to the third embodiment. [Figure 9] FIG. 9 is a diagram illustrating the change in the first instantaneous power upper limit Pmax relative to the reflected wave power value pr. [Figure 10] FIG. 10 is a diagram showing an example of output of the forward wave power value pf during the repetition period T when three-level pulse power control is performed. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of a high frequency power supply system to which a high frequency power supply device according to the present invention is applied.

[0020] The high frequency power supply system 100 supplies traveling wave power PF to a workpiece such as a semiconductor wafer or a liquid crystal substrate to perform processing such as plasma etching. As shown in FIG. 1, the high-frequency power supply system 100 includes a high-frequency power supply device 101, a transmission line 102, an impedance matching device 103, a load connection unit 104, and a load 105. It is also possible to configure the system without using impedance matching device 103.

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

[0022] Generally, this type of high frequency power supply device outputs traveling wave power PF having a frequency of several hundred kHz or more (for example, a frequency of 13 MHz, 40 MHz, etc.). Furthermore, as will be described later, the high-frequency power supply device 101 is configured to be able to output forward power having multiple levels of power values ​​to a load during a predetermined repetition period T by changing the output setting value of the forward power PF one or more times during the repetition period T.

[0023] For example, if the output set value of the forward power PF is changed once during the repetition period T, the above-mentioned two-level pulse power control is performed. Also, if the output set value of the forward power PF is changed twice during the repetition period T, three-level pulse power control is performed. In this way, the high-frequency power supply device 101 is capable of performing so-called multi-level pulse power control.

[0024] Impedance matching box 103 matches the impedance between high frequency power supply device 101 and load 105. More specifically, if the impedance (output impedance) seen from the output end of high frequency power supply device 101 to the high frequency power supply device 101 side is designed to be, for example, 50Ω, and high frequency power supply device 101 is connected to the input end of impedance matching box 103 via transmission line 102 with a characteristic impedance of 50Ω, impedance matching box 103 converts the impedance seen from the input end of impedance matching box 103 to 50Ω.

[0025] Load 105 is a device equipped with a processing section and used to process (etch, CVD, etc.) workpieces such as wafers and liquid crystal substrates that have been carried into the processing section. To process the workpieces, load 105 introduces plasma discharge gas into the processing section and applies traveling wave power PF (traveling wave voltage VF) supplied from high frequency power supply device 101 to the plasma discharge gas, thereby causing discharge in the plasma discharge gas, changing it from a non-plasma state to a plasma state. The workpieces are then processed using the plasma.

[0026] [1] First embodiment FIG. 2 is an explanatory diagram of a configuration example of the high frequency power supply device of the first embodiment. As shown in FIG. 2, the high-frequency power supply device 101 includes a traveling-wave power output section 10, a low-pass filter 20, a directional coupler 30, a power calculation section 40, an instantaneous power upper limit value setting section 51, a first output / coefficient setting section 60, a multiplier 70, a second output setting section 80, and an output control section 90.

[0027] In the first embodiment, the above-mentioned two-level pulse power control is performed.

[0028] Here, the forward wave power output section 10 functions as a forward wave power output section. The directional coupler 30 functions as a power information detector. The power calculation section 40 functions as a forward wave power calculation section and a reflected wave power calculation section. The first output / coefficient setting section 60 functions as a first output setting section, a coefficient table and a coefficient setting section. The output control section 90 functions as an output power control section.

[0029] The traveling wave power output unit 10 has a DC power supply, an oscillation unit (oscillator), an amplification element, etc., which are not shown, and amplifies the high frequency signal output from the oscillation unit using the DC power output from the DC power supply with the amplification element, and outputs high frequency power having an output frequency in the radio frequency band (RF band).

[0030] 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.

[0031] In this case, the high frequency power traveling from high frequency power supply device 101 toward load 105 is called forward power PF. Moreover, the high frequency power reflected by load 105 and returning to high frequency power supply device 101 is called reflected power PR. Furthermore, the power value of forward power PF is called forward power value pf, and the power value of reflected power PR is called reflected power value pr. Furthermore, this type of high frequency power supply device generally outputs forward power PF having a frequency of several hundred kHz or more (for example, a frequency of 13 MHz, 40 MHz, etc.).

[0032] Furthermore, the output of the forward power output unit 10 is controlled by the output control unit 90. Specifically, the forward power output unit 10 controls the forward power value pf, which is the power value of the forward power PF to be output, based on the output control signal Pcnt output from the output control unit 90, for example, by changing the amplitude of the high-frequency signal.

[0033] The forward power PF output from the forward power output unit 10 is supplied to a load 105 via a low-pass filter 20 for mainly removing harmonics, a directional coupler 30 and an impedance matching device 103 .

[0034] Here, as the amplifying element of the traveling wave power output section 10, for example, a FET, a transistor, or the like is used. The low-pass filter 20 removes harmonic components from the output of the forward-wave power output unit 10. A band-pass filter may be used instead of the low-pass filter 20. In some cases, the low-pass filter 20 may be omitted.

[0035] The directional coupler 30 is inserted between the forward 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 forward wave detection signal Vf containing information on the forward wave power PF output from the forward wave power output unit 10, and a reflected wave detection signal Vr containing information on the reflected wave power PR reflected by the load.

[0036] Strictly speaking, the forward power PF output from the forward power output unit 10 is slightly attenuated when passing through the low-pass filter 20 and the directional coupler 30. However, to simplify the explanation, as shown in FIG. 2, the forward power PF output from the forward power output unit 10 and the forward power PF passing through the directional coupler 30 have the same sign.

[0037] The power calculation unit 40 includes a forward wave power calculation unit 41 and a reflected wave power calculation unit 42 . The forward wave power calculation unit 41 calculates and outputs a forward wave power value pf based on the forward wave detection signal Vf. Furthermore, the reflected wave power calculation unit 42 calculates and outputs a reflected wave power value pr based on the reflected wave detection signal Vr.

[0038] The forward power value pf output from the forward power calculation unit 41 and the reflected power value pr output from the reflected power calculation unit 42 can be output to the outside and can be displayed on a monitor, for example.

[0039] The instantaneous power upper limit value setting unit 51 sets the instantaneous allowable power value of the forward power PF as a first instantaneous power upper limit value P max and output to the multiplier 70. First instantaneous power upper limit P maxcan be set using, for example, information acquired from the impedance matching device 103 and the load 105 used, or the detected forward power value pf and reflected power value pr. The maximum rated power P in this embodiment Highmax is 50 kW, and the first instantaneous power upper limit value P max is the maximum rated power P Highmax The first instantaneous power upper limit value P max does not necessarily mean the maximum rated power P Highmax It does not have to be the same as the maximum rated power P Highmax The following is fine.

[0040] The first output / coefficient setting unit 60 sets the preset high power P High , Low power P Low Based on the high output duty ratio D and the repetition period T, the first output setting value PFset1 is set and output to the second output setting unit 80, and the output power coefficient k is set and output to the multiplier .

[0041] In this case, the first output / coefficient setting unit 60 includes a first output setting unit 61, a coefficient table 62, and a coefficient setting unit 63. The first output setting unit 61 sets a preset high power P High , Low power P Low , the first output setting value PFset1 is set based on the High output duty ratio D and the repetition period T, and is output to the second output setting section 80.

[0042] More specifically, the first output setting unit 61 determines the output setting value of the forward power PF (High power P High Based on the above, the power setting value is sequentially output according to the elapsed time from the start point of the repetition period T. This allows two-level pulse power control.

[0043] The coefficient setting unit 63 refers to the coefficient table 62 based on the high output duty ratio D input via the first output setting unit 61, and outputs the corresponding output power coefficient k to the multiplier 70. Therefore, the coefficient setting unit 63 can set an appropriate output power coefficient with a simple configuration, and therefore, appropriate protection control can be performed despite the simple configuration.

[0044] The coefficient setting unit 63 calculates the average power value P of the forward power PF output during the repetition period T. avg The first instantaneous power upper limit value P max Set the output power coefficient k, which is the coefficient to be multiplied by.

[0045] In the case of two-level pulse power control, the average power value P avg is expressed by the above-mentioned formula (1), the output setting value of the forward power PF of the repetition period T (High power P High Based on the above, the first instantaneous power upper limit value P is set within a range that does not exceed the average power upper limit value. max It is sufficient to set the output power coefficient k, which is the coefficient by which to multiply.

[0046] In this embodiment, the first output setting unit 61 sets a preset high power P High , Low power P Low It is assumed that the repetition period T is fixed and the high output duty ratio D is variable. In other words, it is assumed that the high output duty ratio D is a variable. Therefore, the high output duty ratio D is obtained from the first output setting unit 61, and the output power coefficient k is set in accordance with the high output duty ratio D.

[0047] The coefficient setting unit 63 may calculate the output power coefficient k by calculation based on the high output duty ratio D, but in this embodiment, the coefficient table 62 is used to set the output power coefficient with a simple configuration.

[0048] The coefficient table 62 is a table that indicates the correspondence between the high output duty ratio D and the output power coefficient k. FIG. 3 is an explanatory diagram of a specific example of the coefficient table according to the first embodiment. The coefficient table 62 includes high output duty ratio data 62A and output power coefficient data 62B.

[0049] Specifically, in the example of FIG. 3, when the high output duty ratio D is in the range of 0 to 0.3, the output power coefficient k is 1, and when the high output duty ratio D is in the range of 0.31 to 1, the output power coefficient k is 0.5.

[0050] 3, the high output duty ratio D is set in units of 0.01. That is, the range of high output duty ratio D=0.31 to 1 indicates a range greater than 0.3.

[0051] When such a coefficient table 62 is used, there is no need to perform complex calculations, and the output power coefficient k can be found more easily. In this embodiment, the High output duty ratio D is used as a variable, but the variable is not limited to this. For example, the Low output duty ratio (1-D) may be used as a variable, or multiple parameters (for example, the High output duty ratio D and the repetition period T) may be used as variables.

[0052] That is, the coefficient table 62 may be a table in which the variables are the repetition period T, the output setting values ​​for each of the multiple levels of power values ​​during the repetition period T, and some of the duty ratios for the sections corresponding to each power value. In this case, the coefficient setting unit 63 may acquire the parameters set as variables from, for example, the first output setting unit 61. Then, the output power coefficient k may be set by referring to the coefficient table 62 based on the parameters set as variables.

[0053] Of course, the coefficient table 62 may be a table in which the repetition period T, the output setting values ​​for each power value of the multiple levels of power values ​​during the repetition period T, and the duty ratios of the sections corresponding to each power value are all variables, but it is simpler to use a table in which only some of them are variables.

[0054] The multiplier 70 multiplies the input first instantaneous power upper limit value P max is multiplied by the output power coefficient k to obtain the second instantaneous power upper limit value k·P max to the second output setting unit 80. The second output setting unit 80 calculates the second instantaneous power upper limit k·P max and the smaller one is output to the output control unit 90 as the second power set value PFset2.

[0055] The output control unit 90 outputs an output control signal Pcnt to the forward power output unit 10 based on the input second output set value PFset2 and the forward power value pf. The output control unit 90 includes a compensation unit 91 and a subtractor 92.

[0056] The subtractor 92 subtracts the input forward power value pf from the input second output set value PFset2 and outputs the result to the compensation unit 91 as the difference between the second output set value PFset2 and the forward power value pf.

[0057] The compensation unit 91 outputs an output control signal Pcnt to the forward power output unit 10 based on the difference between the second output set value PFset2 and the forward power value pf so that the forward power value pf becomes equal to the second output set value PFset2.

[0058] As a result, the output of the forward power output unit 10 is finally equal to the second output set value PFset2 under the control of the output control signal Pcnt. In this case, in the example of FIG. 3, when the high output duty ratio D is in the range of 0 to 0.3, the output power coefficient k is 1, so the second instantaneous power upper limit k·P max = First instantaneous power upper limit value P max and the first output set value PFset1 and the first instantaneous power upper limit value P max The smaller one of these is output to the compensation unit 91 as the second power set value PFset2.

[0059] On the other hand, when the high output duty ratio D is in the range of 0.31 to 1, the output power coefficient is 0.5, so the second instantaneous power upper limit k·P max = 0.5 First instantaneous power upper limit value P max The first output set value PFset1 and 0.5·first instantaneous power upper limit value P max The smaller one of these is output to the compensation unit 91 as the second power set value PFset2.

[0060] That is, when the high output duty ratio D is in the range of 0.31 to 1, the upper limit value of the high frequency power output from the forward power output section 10 is half the value when the high output duty ratio D is in the range of 0 to 0.3.

[0061] Next, a specific example of the operation of the first embodiment will be described. Next, a specific example of the operation of the first embodiment will be described. In the following description, the first instantaneous power upper limit value P max = 50 kW, average power upper limit P avgmax = 25kW, and the setting conditions for the two-level pulse are: ·High power P High =50kw ·Low power P Low =10kW Let's say.

[0062] 4 is a diagram showing an example of output of the forward power value pf during the repetition period T when two-level pulse power control is performed. The coefficient table shown in FIG. 3 will be described with reference to FIG. First, the case where the High output duty ratio D is in the range of 0 to 0.3 will be described. FIG. 4A is a diagram schematically showing the forward power value pf when the High output duty ratio D=0.25 as a specific example when the High output duty ratio D is in the range of 0 to 0.3.

[0063] The amplitude of the signal waveforms in FIG. 4 and FIG. 10 described later is not an accurate depiction of the amplitude of the forward voltage VF, but is depicted to make the magnitude of the forward power value pf easier to understand.

[0064] As described above, in this embodiment, when the high output duty ratio D is in the range of 0 to 0.3, the output power coefficient k is 1. Therefore, the second instantaneous power upper limit k·P max = 50 kW, and the high power P High =50kW, Low power P Low = 10kW is the second upper limit of instantaneous power k·P max The following is the result.

[0065] Therefore, the high power P High =50kW, Low power P Low =10 kW is outputted as is to the subtractor 92 of the output control unit 90.

[0066] Therefore, as shown in FIG. 4A, when the high output duty ratio D is in the range of 0 to 0.3, the high power P High and Low power P Low There is no limit to the high power P High =50kw, Low power P Low = 10kW of forward power PF will be output.

[0067] When the high output duty ratio D is in the range of 0 to 0.3, the average power value Pavg is greatest when the high output duty ratio D is 0.3, so only this case will be considered. When the high output duty ratio D=0.3, P avg =D×P High +(1-D)×P Low ……(1) P avg =0.3×50kW+(0.7)×10kW =15kW+7kW =22kW That is, the average power value P avg is P avgmax The set value is less than 25kW.

[0068] Next, the case where the High output duty ratio D is in the range of 0.3 to 1 will be described. 4B and 4C are diagrams schematically showing the forward power value pf when the High output duty ratio D=0.5 as a specific example when the High output duty ratio D is in the range of 0.31 to 1. In FIG. The output set by the first output set value PFset1 is assumed to be as shown in FIG. 4(B).

[0069] However, as described above, in this embodiment, when the High output duty ratio D is in the range of 0.31 to 1, the output power coefficient k is 0.5. Therefore, the second upper limit of instantaneous power k·P max = 25 kW, and the high power P High = 50kW is the second upper limit of instantaneous power k·P max That's all.

[0070] Therefore, the high power P High = 50 kW is limited to 25 kW and output to the subtractor 92 of the output control unit 90. On the other hand, the low power P Low =10 kW is outputted as is to the subtractor 92 of the output control unit 90.

[0071] Therefore, the final output is the high power P High is limited to 0.5 times, and high power P High =25kw, Low power P Low = 10kW of forward power PF will be output.

[0072] When the high output duty ratio D is in the range of 0.31 to 1, the average power value Pavg is greatest when the high output duty ratio D=1, so only this case will be considered. Also, high power P High Since the first instantaneous power upper limit value Pmax is limited to 0.5 times, the maximum value is limited to 0.5·50kW=25kW.

[0073] Therefore, when the high output duty ratio D=1, P avg =D×P High +(1-D)×P Low ……(1) P avg = 1 x 25kW + 0 x 10kW =25kW That is, the average power value Pavg is avgmax This is the same as the set value of 25kW.

[0074] As described above, in a high-frequency power supply device that outputs forward power having multiple levels of power values ​​to a load during a repetition period T, output control of the forward power can be performed so that the instantaneous power value of the forward power during the repetition period does not exceed the second instantaneous power upper limit value, and so that the average power value of the forward power during the repetition period does not exceed the average power upper limit value. That is, in a high frequency power supply device that outputs traveling wave power having a plurality of power levels during a repetition period to a load, appropriate protection control can be performed regardless of the output setting value.

[0075] [1.1] Modification of the first embodiment In the first embodiment, FIG. 3 shows the correspondence relationship between the high output duty ratio D and the output power coefficient k. In the example of FIG. 3, only the high output duty ratio D is a variable, but the low power P Low may also be a variable.

[0076] Therefore, in the modified example of the first embodiment, when setting the output power coefficient k, the low power P LowTaking this into consideration, the output power coefficient k is configured to be set more precisely. FIG. 5 is an explanatory diagram of a specific example of a coefficient table according to a modification of the first embodiment. The coefficient table 62X of the second embodiment includes high output duty ratio data 62XA and output power coefficient data 62XB to 62XE.

[0077] The high output duty ratio data 62XA is divided into three cases: when the high output duty ratio D=0 to 0.3, when the high output duty ratio D=0.31 to 0.5, and when the high output duty ratio D=0.5 to 1. The output power coefficient data 62XB is Low The output power coefficient corresponding to a high output duty ratio D of 0 W to less than 5 kW is stored in three data sets: when the high output duty ratio D is 0 to 0.3, when the high output duty ratio D is 0.31 to 0.5, and when the high output duty ratio D is 0.5 to 1.

[0078] The output power coefficient data 62XC is the low power P Low The output power coefficients corresponding to high output duty ratios D=5kW to less than 10kW are stored in three data sets: high output duty ratios D=0 to 0.3, high output duty ratios D=0.31 to 0.5, and high output duty ratios D=0.5 to 1.

[0079] The output power coefficient data 62XD is the low power P Low The output power coefficients corresponding to high output duty ratios D=10 kW to less than 20 kW are stored in three data sets: high output duty ratios D=0 to 0.3, high output duty ratios D=0.31 to 0.5, and high output duty ratios D=0.5 to 1.

[0080] The output power coefficient data 62XE is the low power P LowThe output power coefficients corresponding to high output duty ratios D=20kW to 25kW are stored in three data sets: high output duty ratios D=0 to 0.3, high output duty ratios D=0.31 to 0.5, and high output duty ratios D=0.5 to 1.

[0081] Specifically, in the example of FIG. 5, the high output duty ratio D is in the range of 0 to 0.3, and the low power P Low =0W to less than 5kW, the output power coefficient k=1. Similarly, when the high output duty ratio D is in the range of 0.31 to 0.5 and the low power P Low = 0W to less than 5kW, the output power coefficient k = 0.8, the high output duty ratio D = 0.51 to 1, and the low power P Low = 0W to less than 5kW, the output power coefficient k = 0.5.

[0082] In addition, the high output duty ratio D is in the range of 0.31 to 0.5, and the low power P Low = 20kW to 25kW, the output power coefficient k = 0.5. In this way, in the modification of the first embodiment, the high power P High In addition, low power P Low Since the output of the traveling wave is suppressed while taking into consideration the above, it is possible to perform reflection protection control without increasing the amount of suppression of the output of the traveling wave more than necessary. In addition, the high output duty ratio D is in the range of 0.31 to 0.5, and the low power P Low = 20kW to 25kW, the output power coefficient k = 0.5. In this way, in the modification of the first embodiment, the high power P High In addition, low power P Low It is also possible to suppress the output of traveling waves by taking into consideration the above.

[0083] [2] Second embodiment FIG. 6 is an explanatory diagram of a configuration example of a high frequency power supply device according to the third embodiment. In FIG. 6, the same parts as those in the first embodiment in FIG. 2 are denoted by the same reference numerals. As shown in FIG. 6, the high-frequency power supply device 101 includes a traveling wave power output section 10, a low-pass filter 20, a directional coupler 30, a power calculation section 40, a reflection-considered instantaneous power upper limit value setting section 50, a first output / coefficient setting section 60, a multiplier 70, a second output setting section 80, and an output control section 90.

[0084] In this case, the second embodiment differs from the first embodiment in that the second embodiment includes a reflection-considered instantaneous power upper limit value setting unit 50 instead of the instantaneous power upper limit value setting unit 51. The reflection-considered instantaneous power upper limit value setting unit 50 includes an instantaneous power upper limit value setting unit 51A, a reflection coefficient calculation unit 52, and an instantaneous power upper limit value table 53.

[0085] The instantaneous power upper limit value setting unit 51A sets a first instantaneous power upper limit value Pmax by referring to the instantaneous power upper limit value table 53 based on the absolute value (=|Γ|) of the reflection coefficient Γ output by the reflection coefficient calculation unit 52, and outputs the set first instantaneous power upper limit value Pmax to the multiplier 70.

[0086] The reflection coefficient calculation unit 52 receives the forward wave power value pf calculated by the forward wave power calculation unit 41 of the power calculation unit 40 and the reflected wave power value pr calculated by the reflected wave power calculation unit 42, calculates the absolute value |Γ| of the reflection coefficient Γ expressed by equation (2), and outputs the absolute value |Γ| of the reflection coefficient Γ to the instantaneous power upper limit value setting unit 51A. |Γ|=√(pr / pf) (2)

[0087] The instantaneous power upper limit value table 53 is a table showing the correspondence relationship between the absolute value of the reflection coefficient Γ and the first instantaneous power upper limit value Pmax. FIG. 7 is a diagram illustrating an example of a change in the first upper limit value Pmax of instantaneous power relative to the absolute value of the reflection coefficient Γ.

[0088] When the absolute value of the reflection coefficient Γ is |Γ|=0, the first upper limit of instantaneous power Pmax=50 kw. As shown in FIG. 7, when the absolute value of the reflection coefficient Γ is in the range of |Γ|=0 to 0.2, the reflected power pr is small and the influence of the reflected power pr is considered to be small, so the first instantaneous power upper limit value Pmax=50 kW.

[0089] Furthermore, in the range of the absolute value of the reflection coefficient Γ |Γ| = 0.2 to 1, the reflected wave power pr gradually increases and the influence of the reflected wave power pr cannot be ignored, so the first instantaneous power upper limit value Pmax is gradually reduced from 50 kW, and when the absolute value of the reflection coefficient Γ |Γ| = 1, it becomes 10 kW.

[0090] The above is a theoretical explanation, and in reality, the instantaneous power upper limit value table 53 stores, for example, five pieces of data of first instantaneous power upper limit values ​​Pmax=50kW, 40kW, 30kW, 20kW, and 10kW, which correspond to 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. Of course, the above is not limiting, and further subdivision may be possible, or calculation may be performed using a mathematical formula.

[0091] By adopting such a configuration, according to the second embodiment, it is possible to set a more appropriate first instantaneous power upper limit value Pmax according to the absolute value |Γ| of the reflection coefficient Γ corresponding to the actual operating state, thereby enabling reliable protection control.

[0092] [3] Third embodiment FIG. 8 is an explanatory diagram of a configuration example of a high frequency power supply device according to the third embodiment. 8, the high-frequency power supply device 101 includes a traveling-wave power output section 10, a low-pass filter 20, a directional coupler 30, a power calculation section 40, a reflection-considered instantaneous power upper limit value setting section 50A, a first output / coefficient setting section 60, a multiplier 70, a second output setting section 80, and an output control section 90. The reflection-considered instantaneous power upper limit value setting section 50A also includes an instantaneous power upper limit value setting section 51B and an instantaneous power upper limit value table 53A.

[0093] In the third embodiment, the reflected power value pr calculated by the reflected power calculation unit 42 is input to an instantaneous power upper limit setting unit 51, which sets a first instantaneous power upper limit Pmax based on the reflected power value pr. That is, unlike the second embodiment, the third embodiment does not include a reflection coefficient calculation unit 52.

[0094] In addition, the instantaneous power upper limit value setting unit 51B of the high-frequency power supply device of the third embodiment refers to the instantaneous power upper limit value table 53A based on the reflected wave power value pr to set a first instantaneous power upper limit value Pmax, and outputs the set first instantaneous power upper limit value Pmax to the multiplier 70. The instantaneous power upper limit value table 53A is a table showing the correspondence relationship between the reflected wave power value pr and the first instantaneous power upper limit value Pmax. Fig. 9 is a diagram illustrating the change in the first instantaneous power upper limit value Pmax relative to the reflected power value pr. Fig. 9 can be thought of in the same way as Fig. 7, because the horizontal axis of the instantaneous power upper limit value table 53 shown in Fig. 7 is replaced with the reflected power value pr from the absolute value |Γ| of the reflection coefficient Γ. Specifically, the instantaneous power upper limit value table 53A stores five pieces of data, for example, first instantaneous power upper limit values ​​Pmax=50kW, 40kW, 30kW, 20kW, and 10kW, which correspond to reflected wave power values ​​pr=0 to 10, over 10 to 20, over 20 to 30, over 30 to 40, and over 40 to 50, respectively. Of course, the above is not limiting, and further subdivision may be possible, or calculation may be performed using a mathematical formula. By adopting such a configuration, according to the third embodiment, it is possible to set a more appropriate first instantaneous power upper limit value Pmax according to the reflected wave power value pr corresponding to the actual operating state, thereby enabling reliable protection control.

[0095] [4] Fourth embodiment Although the above-described embodiments are directed to two-level pulse power control, the present invention can also be applied to multi-level pulse power control.

[0096] FIG. 10 is a diagram showing an example of output of the forward wave power value pf during the repetition period T when three-level pulse power control is performed. In the example of FIG. 10, an output example of the forward wave power value pf when three-level pulse power control is performed is shown as an example of multi-level pulse power control.

[0097] In the example of FIG. 10, the pulse level is a high power P High , Mid power PMid is the power of the Mid level pulse P2, Low power P3 is the Low level pulse Low 10 shows the relationship between the High output duty ratio D1, the Mid output duty ratio D2, the Low output duty ratio D3, and the repetition period T.

[0098] Even when such three-level pulse power control is performed, it can be realized by changing the output conditions of the first output setting section 61 in the configuration examples of the high frequency power supply devices shown in the first to third embodiments.

[0099] Also in the fourth embodiment, similarly to the first to third embodiments, the coefficient table 62 may be a table in which the variables are the repetition period T, the output setting values ​​for each of the multiple levels of power values ​​during the repetition period T, and some of the duty ratios for the sections corresponding to each power value. In this case, the coefficient setting unit 63 may acquire the parameters set as variables from, for example, the first output setting unit 61. Then, the output power coefficient k may be set by referring to the coefficient table 62 based on the parameters set as variables.

[0100] Of course, the coefficient table 62 may be a table in which the repetition period T, the output setting values ​​for each power value of the multiple levels of power values ​​during the repetition period T, and the duty ratios of the sections corresponding to each power value are all variables, but it is simpler to use a table in which only some of them are variables.

[0101] As in the second and third embodiments, the first instantaneous power upper limit Pmax may be changed based on the absolute value |Γ| of the reflection coefficient Γ or the reflected power value pr. Alternatively, the first instantaneous power upper limit Pmax may be changed using a table such as instantaneous power upper limit table 53 or instantaneous power upper limit table 53A, which indicates the correspondence between the absolute value |Γ| of the reflection coefficient Γ or the reflected power value pr and the first instantaneous power upper limit Pmax.

[0102] The above explanation has been about three-level pulse power control, but in N-level pulse power control, it is also possible to determine the output power coefficient k for the first powers PW1 to PWN corresponding to the first level pulse P1 to the Nth level pulse PN based on the first duty ratio D1 to the Nth duty ratio DN and the repetition period T, and perform protection control.

[0103] As a result, even when multilevel pulse power control is performed as in the fourth embodiment, protection control can be performed reliably.

[0104] [5] Note The present invention can also be embodied in other ways as follows. [5.1] First Alternative Aspect A first alternative embodiment of the high frequency power supply device is a high frequency power supply device that outputs forward power having a plurality of power levels to a load during a predetermined repetition period by changing an output setting value of the forward power at least once during the repetition period, a forward power output unit that amplifies a high frequency signal and outputs the amplified signal as forward power during the repetition period; an instantaneous power upper limit value setting unit that sets an instantaneous allowable power value of the forward power as a first instantaneous power upper limit value; a first output setting unit that sequentially outputs a first output setting value according to the elapsed time from the start point of the repetition period based on the output setting value of the forward wave power during the repetition period; a coefficient setting unit that sets an output power coefficient, which is a coefficient by which the first instantaneous power upper limit value is multiplied, within a range in which an average power value of forward wave power output during the repetition period does not exceed a predetermined average power upper limit value; a multiplication unit that multiplies the first instantaneous power upper limit value by the output power coefficient and outputs the result as a second instantaneous power upper limit value; a second output setting unit that outputs the smaller of the first output setting value and the second instantaneous power upper limit value as a second output setting value; an output power control unit that controls the forward power output unit so that the forward power is equal to the second output setting value; Equipped with.

[0105] According to the above aspect, in a high-frequency power supply device that outputs forward wave power having multiple levels of power values ​​during a repetition period to a load, output control of the forward wave power can be performed so that the instantaneous power value of the forward wave power during the repetition period does not exceed a second instantaneous power upper limit value, and so that the average power value of the forward wave power during the repetition period does not exceed the average power upper limit value. That is, in a high frequency power supply device that outputs traveling wave power having a plurality of power levels during a repetition period to a load, appropriate protection control can be performed regardless of the output setting value.

[0106] For example, even if the output setting value of the forward wave power in the repetition period is inappropriate and the setting is made so that the average power value of the forward wave power exceeds the average power upper limit value, the output is controlled so that the average power value of the forward wave power does not exceed the average power upper limit value, thereby preventing damage to the elements inside the forward wave power output unit.

[0107] In a second alternative embodiment of the high frequency power supply device, the instantaneous power upper limit value is changed based on the magnitude of the reflected wave power or the absolute value of the reflection coefficient. 1 is a high frequency power supply device according to a first alternative embodiment.

[0108] According to the above aspect, if the magnitude of the reflected wave power or the absolute value of the reflection coefficient becomes large, there is a risk that an element (e.g., a switching element) inside the forward wave power output unit may be damaged. Therefore, by making it possible to change the second instantaneous power upper limit value according to the magnitude of the reflected wave power or the absolute value of the reflection coefficient, the instantaneous power upper limit value can be lowered when the magnitude of the reflected wave power or the absolute value of the reflection coefficient becomes large.

[0109] The multiplication unit generates the second instantaneous power upper limit value by multiplying the first instantaneous power upper limit value by the output power coefficient, so the effect of lowering the first instantaneous power upper limit value can also be reflected in the output control of the average power value of the forward wave power.

[0110] Therefore, according to the above aspect, even if the magnitude of the reflected wave power or the absolute value of the reflection coefficient changes, output control of the forward wave power can be performed according to the magnitude of the reflected wave power or the absolute value of the reflection coefficient so that the instantaneous power value of the forward wave power during the repetition period does not exceed the first instantaneous power upper limit value, and so that the average power value of the forward wave power does not exceed the average power upper limit value.

[0111] In a third alternative embodiment of the high frequency power supply device, the average power value during the repetition period is a power value calculated based on the repetition period, an output setting value for each power value of a plurality of levels of power values ​​during the repetition period, and a duty ratio of a section corresponding to each power value. The high frequency power supply device according to the first or second alternative embodiment.

[0112] According to the above aspect, it is possible to determine the average power value even when the output setting value of the forward power is changed two or more times during a predetermined repetition period.

[0113] A fourth alternative embodiment of the high frequency power supply device further includes a coefficient table having variables of the repetition period, an output setting value of each power value of a plurality of levels in the repetition period, and a part of a duty ratio of a section corresponding to each power value, the coefficient table is set with output power coefficients corresponding to the part of variables, the coefficient setting unit acquires the part of variables from the first output setting unit, and sets an output power coefficient by referring to the coefficient table based on the acquired part of variables. A high frequency power supply device according to a third alternative embodiment.

[0114] According to the above aspect, the output power coefficient can be set with a simple configuration. [Explanation of symbols]

[0115] 10 Traveling wave power output section 20 Low-pass filter 30 Directional coupler 40 Power calculation section 41 Traveling wave power calculation section 42 Reflected wave power calculation section 50,50A Reflection-considered instantaneous power upper limit setting section 51, 51A Instantaneous power upper limit setting section 52 Reflection coefficient calculation unit 53,53A Instantaneous power upper limit table 60 Coefficient setting section 61 First output setting unit 62 Coefficient Table 63 Coefficient setting section 70 Multiplier 80 Second output setting section 90 Output control section 91 Compensation Department 92 Subtractor 100 High frequency power supply system 101 High frequency power supply equipment 105 Load PFset1 First output setting value PFset2 Second output setting value Pcnt Output control signal Pmax First instantaneous power upper limit pf Forward wave power value pr reflected wave power value T repeat period Vf Traveling wave detection signal Vr Reflected wave detection signal k output power coefficient

Claims

1. 1. A high frequency power supply device that outputs forward power having a plurality of power levels to a load during a predetermined repetition period by changing an output setting value of forward power at least once during the repetition period, a forward power output unit that amplifies a high frequency signal and outputs the amplified signal as forward power during the repetition period; an instantaneous power upper limit value setting unit that sets an instantaneous allowable power value of the forward power as a first instantaneous power upper limit value; a first output setting unit that sequentially outputs a first output setting value according to an elapsed time from a start point of the repetition period, based on an output setting value of forward wave power during the repetition period; a coefficient setting unit that sets an output power coefficient, which is a coefficient by which the first instantaneous power upper limit value is multiplied, within a range in which an average power value of forward wave power output during the repetition period does not exceed a predetermined average power upper limit value; a multiplication unit that multiplies the first instantaneous power upper limit value by the output power coefficient and outputs the result as a second instantaneous power upper limit value; a second output setting unit that outputs the smaller of the first output setting value and the second instantaneous power upper limit value as a second output setting value; an output power control unit that controls the forward power output unit so that the forward power is equal to the second output setting value; A high frequency power supply device equipped with:

2. changing the upper limit of the instantaneous power based on the magnitude of the reflected wave power or the absolute value of the reflection coefficient; 2. 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 repetition period, an output setting value for each power value of a plurality of levels during the repetition period, and a duty ratio of a section corresponding to each power value; 3. The high frequency power supply device according to claim 1 or 2.

4. a coefficient table in which variables are the repetition period, the output setting value of each power value of a plurality of levels during the repetition period, and a part of the duty ratio of the section corresponding to each power value; the coefficient table is set with output power coefficients corresponding to the part of variables, the coefficient setting unit acquires the part of variables from the first output setting unit, and sets an output power coefficient by referring to the coefficient table based on the acquired part of variables.

4. The high frequency power supply device according to claim 3.

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