JP2010114001A - Power source device for plasma generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power source device for plasma generation, using a simple structure and at low cost. <P>SOLUTION: In the power source device for plasma generation in which AC power such as commercial AC power is converted into DC power by a rectifier and the DC power is converted into high-frequency AC power by an inverter, and the high-frequency AC power is supplied to a load circuit constituted of a matching part and a plasma generating unit; by making the switching frequency for driving the inverter variable to adjust the power of the power source so that high-frequency current which is supplied to the plasma generating unit is made constant, the high-frequency voltage made constant, or the high-frequency power made constant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma generating power supply device, and more specifically, plasma is generated in a semiconductor manufacturing apparatus that performs a semiconductor manufacturing process such as high-frequency sputtering, plasma CVD (chemical vapor deposition) or etching. The present invention relates to a plasma generating power supply device that is suitable for use in generating the plasma.

  As a conventional plasma generating power supply device, for example, a so-called inverter type plasma generating power supply device including an inverter is known.

Here, FIG. 1 shows an explanatory block diagram of a conventional inverter type plasma generation power supply device.

  FIG. 2 shows a variable matching unit of the plasma generating power supply apparatus shown in FIG. 1 and an equivalent circuit of the plasma generating apparatus.

  The plasma generating power supply apparatus 100 converts AC power supplied from an AC power supply 120 into high-frequency AC power having a desired voltage and supplies the high-frequency AC power to a plasma generating apparatus 130 as a load.

  As the AC power supply 120, for example, a commercial AC power supply can be used. In this case, the plasma generating power supply apparatus 100 converts the commercial AC power into high-frequency AC power and supplies it to the plasma generating apparatus 130. .

  More specifically, the plasma generating power supply apparatus 100 includes a variable rectifier 102 that converts AC power supplied from the AC power supply 120 into DC power and outputs the DC power, an electrolytic capacitor 104, and high-frequency AC power by inputting DC power. Output from the inverter 106, the variable high frequency AC power output from the inverter 106, the variable matching unit 108 having a variable circuit constant that is output to the plasma generator 130, and the variable matching unit 108 A detection unit 110 that performs phase detection and power detection of high-frequency AC power, a matching control unit 112 that controls a matching condition in the variable matching unit 108 based on a detection result by the detection unit 110, and a detection result by the detection unit 110 A frequency control unit 114 for controlling a switching frequency for driving the inverter 106; Variable rectifier 102 based on the detection result by the detection section 110 is configured to have a voltage control unit 116 for controlling the DC voltage to be converted.

In the configuration described above, the plasma generating power supply device 100 converts the AC power supplied from the AC power source 120 into DC power by the variable rectifier 102, and reversely converts the DC power to high frequency AC power by the inverter 106. Is supplied to a load circuit composed of the variable matching unit 108 and the plasma generator 130.

  In such a plasma generating power supply apparatus 100, the reactive power is reduced by driving the inverter 106 at a switching frequency equal to the resonance frequency.

By the way, in the plasma generating power supply apparatus that drives the inverter as described above at the same switching frequency as the resonance frequency, it is necessary to change the DC voltage when adjusting the output. In general, thyristors have been used as variable rectifiers.

  However, the use of thyristors has the following problems (1) to (3).

  (1) Since excessive ripples are generated, a large-capacity electrolytic capacitor (the electrolytic capacitor 104 in the plasma generating power supply device 100) is necessary for removing ripples. However, the electrolytic capacitor has a problem that the component life is overwhelmingly short compared to a semiconductor element or a passive element, and it is necessary to periodically replace the electrolytic capacitor.

  (2) The rectification by the thyristor has a problem that the power factor is greatly reduced when the low output is set.

  (3) Since the control by the thyristor is feedback control at a commercial frequency, there is a problem that tracking control for load fluctuation of the plasma generator is delayed.

In addition, in the plasma generation power supply device that drives the inverter at a switching frequency that is the same frequency as the resonance frequency, a chopper power supply or a PWM (Pulse Width Modulation) inverter is used in addition to the thyristor. There is a method of varying the voltage, but when a power supply of several kW or more is configured, there is a problem that the DC power conversion unit becomes large and expensive.

In addition, frequency stability is determined in a plasma generating power supply device using an ISM (Industry-Science-Medical) band.

  More specifically, in the 13.56 MHz plasma generation power supply device, it is necessary to adjust the frequency matching to be ± 0.05% (± 7 kHz) with respect to a change in the load of the plasma generation device. The matching circuit employs a constant variable system of L and C.

  For this reason, the conventional plasma generating power supply device using the band for ISM has a problem that the configuration of the matching unit is very complicated, and further, an advanced adjustment operation or an automatic adjustment function is required. It was.

In addition, there is known an apparatus using a technique for matching the output impedance of the plasma generating power supply apparatus and the input impedance of the plasma generating apparatus with 50Ω.

  Specifically, the plasma generating power supply device of such a plasma generating device is a plasma generating power supply device constituted by a class A / B class / AB class / D class amplifier.

Here, FIG. 3 shows a block configuration explanatory diagram of a plasma generating power supply apparatus constituted by a conventional class A / class B / class AB / class D amplifier.

  FIG. 4 shows an equivalent circuit of the variable matching unit and the plasma generator of the plasma generating power supply device shown in FIG.

  The plasma generating power supply device 200 converts AC power supplied from the AC power supply 220 into high-frequency AC power having a desired voltage and supplies the high-frequency AC power to a plasma generating device 230 that is a load.

  As the AC power supply 220, for example, a commercial AC power supply can be used. In this case, the plasma generating power supply device 200 converts the commercial AC power into high-frequency AC power and supplies it to the plasma generating device 230. .

  More specifically, the plasma generating power supply apparatus 200 includes a rectifier 202 that converts alternating current power supplied from the alternating current power supply 220 into direct current power, an electrolytic capacitor 204, an oscillation circuit 206, an amplifier 208, a circuit, and the like. A variable matching unit 210 having a variable constant, a directional coupler 212, a reflected power detection unit 214, and a matching control unit 216 that controls a matching condition in the variable matching unit 210 based on a detection result by the reflected power detection unit 214, And an output control unit 218 that controls the output of the amplifier 208 based on the detection result by the reflected power detection unit 214.

By the way, in the plasma generating power supply device configured by the class A / B / AB / D class amplifier as described above, it is necessary to adjust the matching circuit with respect to the change in the input impedance of the plasma generator, Variable elements with L and C constants were used.

  For this reason, in such a plasma generating power supply device, the configuration of the matching unit (which is the variable matching unit 210 in the plasma generating power supply device 200) is complicated, and an advanced adjustment operation or automatic adjustment function is required. There was a problem that it was.

In addition, as a technique related to the conventional plasma generating power supply apparatus as described above, there are techniques disclosed in Patent Documents 1 to 5 shown below.
JP 2004-80846 A JP-A-11-288796 JP-A-9-247945 JP 2003-125586 A JP-A-7-142387

  The present invention has been made in view of the various problems of the conventional techniques as described above, and an object of the present invention is to provide a plasma generating power supply apparatus that is simple in structure and inexpensive. It is.

  In order to achieve the above object, the plasma generating power supply apparatus according to the present invention adjusts the output by varying the switching frequency for driving the inverter.

  Here, the output adjustment means that the high-frequency current supplied to the plasma generator is made constant, the high-frequency voltage is made constant, or the high-frequency power is made constant.

  As a result, the circuit constant of the matching circuit can be fixed, and a plasma generating power supply device that is simple and inexpensive can be obtained.

  That is, the present invention converts AC power such as commercial AC power into DC power with a rectifier, reversely converts DC power into high-frequency AC power with an inverter, and converts the high-frequency AC power into a load circuit composed of a matching unit and a plasma generator. In the power supply device for plasma generation that is supplied, the power frequency is adjusted by changing the switching frequency for driving the inverter, the high frequency current supplied to the plasma generation device is made constant, or the high frequency voltage is made constant. Alternatively, the high frequency power is made constant.

  According to such a plasma generating power supply device according to the present invention, a plasma generating power supply device having a simple structure and a low cost can be obtained.

  In the plasma generating power supply device according to the present invention, the switching frequency for driving the inverter may be set to a frequency near the resonance frequency or higher than the resonance frequency.

That is, the invention according to claim 1 of the present invention converts alternating current power into direct current power with a rectifier, reversely transforms the direct current power into high frequency alternating current power with an inverter, and generates the high frequency alternating current power with a matching unit and plasma generation. A power supply device for plasma generation supplied to a load circuit comprising the device, wherein a high frequency current supplied to the plasma generation device is made constant by varying a switching frequency for driving the inverter.

  According to the second aspect of the present invention, AC power is converted into DC power by a rectifier, the DC power is inversely converted to high frequency AC power by an inverter, and the high frequency AC power is generated by a matching unit and plasma generation. A power supply device for plasma generation supplied to a load circuit comprising the device, wherein a high frequency voltage supplied to the plasma generator is made constant by varying a switching frequency for driving the inverter.

  According to a third aspect of the present invention, the AC power is converted into DC power by a rectifier, the DC power is inversely converted to high frequency AC power by an inverter, and the high frequency AC power is generated by the matching unit and the plasma generation. A power supply device for plasma generation supplied to a load circuit comprising the device, wherein a high frequency power supplied to the plasma generator is made constant by varying a switching frequency for driving the inverter.

  According to a fourth aspect of the present invention, in the invention according to any one of the first, second, and third aspects of the present invention, the switching frequency is automatically fixed by fixing the constant of the element in the matching section. It is intended to be tracked.

  The invention according to claim 5 of the present invention is the invention according to any one of claims 1, 2, or 3 of the present invention, wherein the switching frequency for driving the inverter is varied. The high frequency power supplied to the plasma generator is adjusted to be constant.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the switching frequency is varied in a frequency region higher than the resonance frequency in the resonance characteristics.

  Since the present invention is configured as described above, it has an excellent effect that it is possible to provide a plasma generating power supply apparatus that is simple and inexpensive.

  Hereinafter, an example of an embodiment of a plasma generating power supply device according to the present invention will be described in detail with reference to the accompanying drawings.

Here, FIG. 5 is a block diagram illustrating a plasma generating power supply device according to the first embodiment of the present invention.

  FIG. 6A shows a variable matching unit of the plasma generating power supply apparatus according to the first embodiment of the present invention shown in FIG. 5 and an equivalent circuit of the plasma generating apparatus. FIG. 6B shows an equivalent circuit in which the plasma generator of FIG. 6A is replaced with an impedance Zp.

  The plasma generation power supply device 10 according to the first embodiment of the present invention converts AC power supplied from an AC power supply 22 into high-frequency AC power of a desired voltage and supplies it to a plasma generation device 24 as a load. To do.

  As the AC power source 22, for example, a commercial AC power source can be used. In this case, the plasma generating power source device 10 converts commercial AC power into high frequency AC power and supplies it to the plasma generating device 24. .

  More specifically, the plasma generating power supply device 10 converts the AC power supplied from the AC power source 22 into DC power and outputs the DC power, and the DC power output from the rectifier 12 to input the high frequency AC power. 14 that is converted back to and output, the high-frequency AC power output from the inverter 14 and the fixed matching unit 16 having a fixed circuit constant that is output to the plasma generator 24 and the high-frequency AC output from the inverter 14 The detection unit 18 performs power phase detection, current detection, voltage detection, and power detection, and a frequency control unit 20 that controls a switching frequency for driving the inverter 14 based on a detection result by the detection unit 18. ing.

In the above configuration, the plasma generating power supply device 10 converts the AC power supplied from the AC power source 22 into DC power by the rectifier 12, reversely converts the DC power to high frequency AC power by the inverter 14, and converts the high frequency AC power to A load circuit including the fixed matching unit 16 and the plasma generator 24 is supplied.

  In such a plasma generation power supply device 10, the frequency control unit 20 varies the switching frequency of the inverter 14 within a range that does not affect the plasma generation state with respect to the resonance frequency based on the detection result by the detection unit 18.

  As described above, in the plasma generating power supply device 10, since the matching can be adjusted by changing the switching frequency of the inverter 14 by the frequency control unit 20, the circuit of the matching unit is used as if the fixed matching unit 16 is used. The constant may be fixed (no adjustment is required).

  That is, according to the plasma generating power supply apparatus 10, the power frequency is adjusted by changing the switching frequency for driving the inverter 14, the high frequency current supplied to the plasma generating apparatus 24 is made constant, or the high frequency voltage is made constant. Or a high-frequency power can be made constant, and a plasma generating power supply device that is simple and inexpensive can be realized.

Next, FIG. 7 is a block diagram illustrating a plasma generating power supply device according to the second embodiment of the present invention.

  In the description of the plasma generating power supply device according to the second embodiment of the present invention shown in FIG. 7, the same or equivalent to the plasma generating power supply device 10 according to the first embodiment of the present invention shown in FIG. About the structure to do, it shall suppose that the detailed structure and description of an effect | action are abbreviate | omitted suitably by showing using the code | symbol same as the code | symbol used above.

  When the plasma generating power supply device 30 according to the second embodiment of the present invention shown in FIG. 7 and the plasma generating power supply device 10 according to the first embodiment are compared, phase detection, current detection, Only the connection state of the detection unit that performs voltage detection and power detection is different.

  That is, in the plasma generating power supply device 10, the detection unit 18 is connected so as to detect the phase, current, voltage, and power of the high-frequency AC power output from the inverter 14.

  On the other hand, in the plasma generating power supply device 30, a detection unit 32 is connected so as to detect the phase, current, voltage, and power of the high-frequency AC power output from the fixed matching unit 16.

  Similar to the plasma generation power supply device 10, the plasma generation power supply device 30 is configured so that the frequency control unit 20 determines the inverter 14 within a range that does not affect the plasma generation state with respect to the resonance frequency based on the detection result by the detection unit 32. The switching frequency of is variable.

  That is, in the plasma generating power supply device 30, since the matching can be adjusted by changing the switching frequency of the inverter 14 by the frequency control unit 20, the circuit constant of the matching unit is as in the case of using the fixed matching unit 16. It may be fixed (adjustment unnecessary).

  Therefore, the plasma generation power supply device 30 can also realize a plasma generation power supply device that has a simple configuration and is inexpensive.

Here, FIG. 8 shows a graph showing the relationship between the frequency representing the resonance characteristic (matching characteristic) and the output power in the plasma generating power supply device according to the first embodiment of the present invention.

The impedance calculation formula is shown below. First, the angular velocity is expressed by ω = 2πf Formula 1
And

Here, in FIG. 6B,
Zp = Rp−j (1 / ωCp) Equation 2
It is.

The impedance of the equivalent circuit shown in FIG.
Z = {− j (1 / ωCp · Zp)} / {− j (1 / ωCp) + Zp} + jωL Equation 3
It becomes.

Therefore, from Equation 2 and Equation 3,
Z = {Rp / (ω ² C · Cp) + (Rp / ωC) (1 / ωC + 1 / ωCp)} / {Rp ² + (1 / ωC + 1 / ωCp) ² } + j [[{1 / (ω ² C · Cp)} (1 / ωC + 1 / ωCp) -Rp 2 / ωC] / {Rp 2 + (1 / ωC + 1 / ωCp) 2} + ωL ]
It becomes.

here,
A = Rp / (ω ² C · Cp) + (Rp / ωC) (1 / ωC + 1 / ωCp)
B = Rp ² + (1 / ωC + 1 / ωCp) ²
C = {1 / (ω ² C · Cp)} (1 / ωC + 1 / ωCp) −Rp ² / ωC
D = ωL
Then,
Z = B / A + j (C / A + D)
And
^{| Z | = √ {(B} / A) 2 + (C / A + D) 2} ··· Equation 4
It is.

From Equation 1 and Equation 4, the characteristics of the output power with respect to the normalized frequency F = f / f ₀ are as shown in FIG.

In the plasma generating power supply device 10, by changing the switching frequency for driving the inverter 14, the high frequency current supplied to the plasma generating device 24 is adjusted to be constant, the high frequency voltage is adjusted to be constant, or The high frequency power is adjusted to be constant.

FIG. 9 is a graph showing the relationship between the frequency and the output power when the inverter 14 is driven at a switch frequency higher than the resonance frequency and the output is adjusted in the plasma generating power supply device 10 (see the solid line portion). )It is shown.

  When driving the inverter 14 of the plasma generating power supply devices 10 and 30, when adjusting the output by driving at a switching frequency higher than the resonance frequency, as in the frequency region indicated by the solid line in the graph shown in FIG. When the switching frequency is increased, the phase delay of the high-frequency alternating current increases, and as a result, the load input power, that is, the power output decreases.

  The rectifier 12 does not need the function of changing the DC voltage, and can be constituted by, for example, a simple diode stack.

  As described above, when the inverter 14 is driven at the switching frequency higher than the resonance frequency in the plasma generating power supply devices 10 and 30, the following effects (1) to (3) are obtained.

  (1) Since the ripple is reduced, no electrolytic capacitor is required. For this reason, maintenance can be simplified.

  (2) By using a diode stack as the rectifier 12, the power factor is improved, and a power factor of 90% or more can be maintained even at 50% of the rated output.

  (3) Since the switching frequency control of the inverter 14 is feedback control of high-frequency alternating current, high-speed tracking control can be performed with respect to load fluctuations of the plasma generator 24.

Further, in the plasma generating power supply devices 10 and 30, when the output is adjusted by driving the inverter 14 at a switching frequency higher than the resonance frequency as in the frequency region indicated by the solid line in the graph shown in FIG. For example, a diode stack can be used, but a diode stack corresponding to a large current is modularized and generally commercially available.

  For this reason, even when a plasma generating power supply device having an output of several kW or more is configured by the plasma generating power supply devices 10 and 30, it is possible to configure the plasma generating power supply device in a small size and at a low price.

In the plasma generating power supply devices 10 and 30, when the output is adjusted by driving the inverter 14 at a switching frequency higher than the resonance frequency as in the frequency region indicated by the solid line in the graph shown in FIG. A switching frequency of several tens of kHz to several hundreds of kHz is assumed. Based on this assumption, the fixed matching unit is previously set so that the resonance frequency of the resonance circuit including the fixed matching unit 16 and the plasma generator 24 becomes a desired value. Sixteen circuit constants are set.

  As described above, by adjusting the switching frequency of the inverter 14 within a range that does not affect the plasma generation state with respect to the resonance frequency, matching adjustment can be performed, and the circuit constant of the matching unit is fixed ( Adjustment is unnecessary), and a simple configuration can be obtained.

Further, in the plasma generation power supply devices 10 and 30, when the inverter 14 is driven at a state where the impedance of the series resonance circuit including the fixed matching unit 16 and the plasma generation device 24 is the lowest, that is, at a switching frequency near the resonance frequency. Maximum efficiency is obtained.

As described above, the circuit constant of the fixed matching unit is set in advance so that the resonance frequency of the resonance circuit composed of the fixed matching unit 16 and the plasma generator 24 becomes a desired value, and the plasma generation is affected by the resonance frequency. Matching adjustment can be performed by changing the switching frequency of the inverter 14 within a range that does not reach, and the circuit constant of the matching unit is fixed (no adjustment is required), and a simple configuration can be achieved.

  INDUSTRIAL APPLICABILITY The present invention can be used as a plasma generation power supply device in a CCP (Capacitively Coupled Plasma) CVD apparatus, an ozone generator, a laser, a plasma display panel, or an excitation apparatus using discharge such as a lamp. .

FIG. 1 is a block diagram illustrating a conventional inverter type plasma generating power supply device. FIG. 2 is an equivalent circuit of the variable matching unit and the plasma generator of the plasma generating power supply device shown in FIG. FIG. 3 is a block diagram for explaining the configuration of a plasma generating power supply device composed of a conventional class A / class B / class AB / class D amplifier. FIG. 4 is an equivalent circuit of the variable matching unit and the plasma generator of the plasma generating power supply device shown in FIG. FIG. 5 is a block diagram illustrating a plasma generating power supply device according to the first embodiment of the present invention. FIG. 6A is an equivalent circuit of the variable matching unit and the plasma generator of the plasma generating power supply device according to the first embodiment of the present invention shown in FIG. 5, and FIG. This is an equivalent circuit in which the plasma generator 6 (a) is replaced with an impedance Zp. FIG. 7 is a block diagram illustrating a plasma generating power supply device according to the second embodiment of the present invention. FIG. 8 is a graph showing the relationship between the frequency representing the resonance characteristic (matching characteristic) and the output power in the plasma generating power supply device according to the first embodiment of the present invention. FIG. 9 shows the relationship between the frequency and the output power when the inverter in the power source device for plasma generation according to the first embodiment of the present invention is driven with the switch frequency higher than the resonance frequency to adjust the output. It is a graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma generation power supply device 12 Rectifier 14 Inverter 16 Fixed matching part 18 Detection part 20 Frequency control part 22 AC power supply 24 Plasma generator 30 Plasma generation power supply apparatus 32 Detection part 100 Plasma generation power supply apparatus 102 Variable rectifier 104 Electrolytic capacitor 106 Inverter 108 Variable matching unit 110 Detection unit 112 Matching control unit 114 Frequency control unit 116 Voltage control unit 120 Rectifier 130 Plasma generator 200 Plasma generating power supply device 202 Rectifier 204 Electrolytic capacitor 206 Oscillator circuit 208 Amplifier 210 Variable matching unit 212 Directional coupling Unit 214 reflected power detection unit 216 matching control unit 218 output control unit 220 AC power supply 230 plasma generator

Claims (6)

A plasma generating power supply device that converts AC power into DC power using a rectifier, reverse-converts the DC power into high-frequency AC power using an inverter, and supplies the high-frequency AC power to a load circuit including a matching unit and a plasma generator. And
A high frequency current supplied to the plasma generator is made constant by changing a switching frequency for driving the inverter. A plasma generating power supply device that converts AC power into DC power using a rectifier, reverse-converts the DC power into high-frequency AC power using an inverter, and supplies the high-frequency AC power to a load circuit including a matching unit and a plasma generator. And
A high frequency voltage supplied to the plasma generator is made constant by changing a switching frequency for driving the inverter. A plasma generating power supply device that converts AC power into DC power using a rectifier, reverse-converts the DC power into high-frequency AC power using an inverter, and supplies the high-frequency AC power to a load circuit including a matching unit and a plasma generator. And
A high frequency power supplied to the plasma generator is made constant by changing a switching frequency for driving the inverter. In the power supply device for plasma generation of any one of Claim 1, 2, or 3,
The plasma generating power supply apparatus, wherein the switching frequency is automatically tracked by fixing a constant of the element in the matching unit. In the power supply device for plasma generation of any one of Claim 1, 2, or 3,
A plasma generating power supply device characterized in that the high frequency power supplied to the plasma generator is adjusted to be constant by varying a switching frequency for driving the inverter. In the plasma generating power supply device according to claim 5,
A power supply device for plasma generation, characterized in that the switching frequency is varied in a frequency range higher than the resonance frequency in the resonance characteristics.

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