JP4319514B2 - Plasma processing apparatus having high frequency power supply with sag compensation function - Google Patents

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus suitable for performing an etching process on a sample such as a semiconductor element substrate by using plasma and applying a high frequency voltage to the sample.

In a conventional plasma processing apparatus for etching, for example, as described in Patent Document 1 below, a sinusoidal high-frequency voltage is applied to an electrode on which a wafer that is a material to be processed is placed. In this case, as shown in FIG. 12, the energy distribution of ions incident on the wafer has a saddle peak shape having two peaks on the high energy side and the low energy side. High energy peak ions contribute to etching, but low energy peak ions contribute little to etching. When a sinusoidal high frequency voltage is applied, the ratio of the amount of ions on the high energy side and the low energy side is approximately 1: 1. Even if the high frequency voltage is changed, the high / low energy ion ratio hardly changes, and there is a problem that the etching efficiency is not good.
JP-A-5-174959

  An object of the present invention is to provide a plasma processing apparatus suitable for high-speed and high-precision etching processing.

In order to achieve the above object, a high-frequency applying means is used in which a high-frequency voltage waveform generated in a material to be processed is rectangular. A high-frequency power source that oscillates a rectangular wave is processed via a high-frequency voltage waveform control circuit (sag compensation circuit) that changes the absolute value of at least one of the positive and negative voltages of the rectangular high-frequency voltage over time. It connected to the electrode which mounts material. The high-frequency voltage waveform control circuit (sag compensation circuit) is automatically controlled with respect to the monitored amount so that a rectangular wave is applied to the material to be processed. Thereby, a rectangular high frequency voltage is applied to the material to be processed. Ions incident on the wafer, which is the material to be processed, are accelerated by electrolysis in an ion sheath formed on the wafer. Electric field in the ion sheath is related to the thickness of the potential difference and the ion sheath between the plasma potential and wafer potential on the ion sheath. When a rectangular high-frequency voltage is applied to the wafer, low energy ions are incident on the wafer during a period in which a positive voltage is applied, and high energy ions are incident on the wafer in a period in which a negative voltage is applied. Therefore, by changing the duty ratio of the rectangular high-frequency voltage, the ratio of high energy ions and low energy ions incident on the wafer can be changed. As a result, high-speed and high-precision etching can be performed.

  According to the present invention, the absolute value of the high frequency voltage increases with time, and a voltage waveform that switches between a positive voltage and a negative voltage is applied to the wafer mounting electrode 9, and as a result, a rectangular high frequency voltage is generated on the wafer 10. Thus, it is possible to perform highly efficient and highly accurate etching, and the material selection ratio is improved.

  A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a magnetic field UHF etching apparatus which is an embodiment of the plasma processing apparatus of the present invention. After the pressure inside the processing chamber 1 defined by the container 1a, the discharge tube 1b and the quartz window 2 is reduced by a vacuum exhaust device (not shown), an etching gas is introduced into the processing chamber 1 by a gas supply device (not shown). Adjust to the desired pressure. The processing chamber 1 is in a magnetic field region generated by the coil 3 and the yoke 4. In this case, the 450 MHz UHF wave oscillated from the high-frequency power source 5 propagates through the coaxial waveguide 7 through the matching unit 6, passes through the quartz window 2 from the antenna 8, and passes through the processing chamber. 1 is incident. The UHF wave generates plasma in the processing chamber 1 by interaction with the magnetic field. The wafer 10 disposed on the wafer mounting electrode 9 is etched from the plasma generated by the UHF wave. Further, in order to control the etching shape of the wafer 10, a rectangular high frequency power source 13 is connected to the wafer mounting electrode 9 via a matching unit 11 and a high frequency voltage waveform control circuit (sag compensation circuit) 12 to apply a high frequency voltage. It is possible. An electrode current monitor 15 is connected to the high frequency voltage application section of the wafer mounting electrode, and the current waveform generated in the electrode can be measured. The measured electrode current is used as a control signal for the high-frequency voltage waveform control circuit (sag compensation circuit) 12.

The wafer mounting electrode 9 has an electrode surface covered with a sprayed film (not shown) and is connected to a DC power source 14. Thereby, the wafer 10 is fixed to the wafer mounting electrode through electrostatic spraying by electrostatic adsorption. Further, a quartz shower plate 2a is provided immediately below the quartz window 2, and an etching gas flows between the quartz window 2 and the shower plate 2a, and from a gas inlet provided in the center of the shower plate 2a, It is introduced into the processing chamber 1. Since etching gas is supplied from directly above the wafer 10, highly uniform etching processing is possible. A quartz cover 12 is provided inside the processing chamber 1 to prevent contamination.

FIG. 2 shows a circuit configuration example of the matching unit 11, the high-frequency voltage waveform control circuit (sag compensation circuit) 12, and the DC power supply 14 connected to the wafer mounting electrode 9. The matching unit 11 is composed of an inductor and a capacitor. However, in order to maintain a rectangular voltage waveform input from the rectangular high-frequency power source 13, a broadband frequency characteristic is required. For example, the impedance may be converted by a high frequency transformer. The high-frequency voltage waveform control circuit (sag compensation circuit) 12 includes a semiconductor element such as a diode and FET and a capacitor. Basically, it has a function of clipping an input waveform with an arbitrary voltage of positive voltage and negative voltage. The high-frequency voltage waveform control circuit (sag compensation circuit) 12 includes variable capacitors VC1 and VC2 in series with the diodes D1 and D2. The waveform can be changed from a waveform clipped flat by the capacitor capacities of VC1 and VC2 to a waveform in which the absolute value of the voltage increases with time. The high-frequency voltage waveform control circuit (sag compensation circuit) 12 is not limited to the circuit shown in FIG. 2, but may be any circuit that can shape the waveform so that the absolute value of the high-frequency voltage increases with time, such as an integration circuit or a phase control circuit. good. In addition, an automatic control circuit 16 capable of varying the capacitor capacity according to the monitor amount is connected to VC1 and VC2. In FIG. 1, the monitor amount is the current obtained from the electrode current monitor 15 installed on the electrode. For example, the monitor amount is the voltage generated in the material to be processed, the current flowing into the material to be processed, the electrode for placing the wafer. At least one of the voltage, the power applied to the processing material, and the output power of the high frequency power source may be used. In FIGS. 1 and 2 , VC1 and VC2 are controlled so that the electrode current waveform is closest to a rectangular wave. The waveform-shaped high frequency voltage is applied to the wafer mounting electrode 9 via a capacitor C2 that blocks a DC voltage. The DC power source 14 is connected to the wafer mounting electrode 9 via the inductor L3. The inductor L3 prevents the high frequency voltage from flowing into the DC power supply 14.

FIG. 3 shows a high-frequency voltage waveform applied to the wafer mounting electrode 9, and FIG. 4 shows a high-frequency voltage waveform on the wafer 10. In this case, the frequency of the high frequency voltage is 400 kHz. FIG. 5 shows the energy distribution of ions incident on the wafer when the duty ratio of the rectangular high-frequency voltage is changed. Here, as shown in FIG. 4, the duty ratio is set to positive voltage application time T ₁ / cycle T in the high-frequency voltage waveform. If the duty ratio of 50%, as in the case of applying a sine-wave high-frequency voltage shown in FIG. 9, the amount of ions the ratio of the high energy side and the low energy side is approximately 1: 1, the duty ratio When the ratio is decreased, the ratio of the amount of ions on the high energy side increases. Conversely, when the duty ratio is increased, the ratio of the amount of ions on the low energy side increases. As the ion energy increases, the etching reaction efficiency (chemical sputtering rate) increases. Therefore, the etch rate increases as the amount of ions on the high energy side increases. In other words, since the ion energy distribution is monochromatic, the etching shape is vertical and high-precision processing can be performed. For example, vertical and high-precision processing in gate etching. Furthermore, since the relationship between the ion energy and the chemical sputtering rate differs depending on the material to be etched, the etching selectivity of a plurality of materials to be etched can be improved by selecting the optimum ion energy . For example, the improvement of the hard mask selection ratio in low dielectric constant (Low-k) insulating film etching and the improvement of the selection ratio with the underlying ultrathin oxide film in gate etching. In the low dielectric constant (Low-k) insulating film etching, the frequency of the high frequency power source was set to 800 kHz.

When a rectangular high frequency voltage as shown in FIG. 6 is applied to the wafer mounting electrode 9, the high frequency voltage at the wafer 10 has a waveform as shown in FIG. That is, the absolute value of the high-frequency voltage decreases with time (hereinafter referred to as sag). Here, the sag is defined as shown in FIG. The amplitude of the rectangular wave voltage waveform is V ₀ (V), the sag amount is V _S (V), and the sag amount ratio (%) is defined by the following equation.

で与えられる。プラズマ抵抗を一定とした場合のサグ量比率のコンデンサ容量依存性の計算結果を図１０に示しておく。ウェハ１０での高周波電圧は図７に示すようなサグ量比率の高い波形の場合、エネルギー分布は、高エネルギーピ−ク、低エネルギーピ−クにおけるエネルギー幅が増加し、ピークでのイオン量が減少したブロードな分布となる。このため、エッチングレート、加工精度および材料選択比が減少する。このような高周波電圧の絶対値が時間とともに減少する、いわゆるサグを補償するために、高周波電圧波形制御回路（サグ補償回路）１２により高周波電圧の絶対値が時間とともに増加するように波形整形し、ウェハ載置用電極９に高周波電圧を印加することが必要である。また、エッチング処理の条件によってプラズマ抵抗は異なるため、サグ量も異なる。エッチング処理の条件によらず、ウェハ１０に図４のような矩形高周波電圧を発生させるため、高周波電圧波形制御回路（サグ補償回路）１２を自動制御しなければならない。本方式では、ウェハに発生するサグ量と相関のあるパラメータをモニター量とし、高周波電圧波形制御回路（サグ補償回路）１２を自動制御している。また、モニター量を演算処理した値を用いて高周波電圧波形制御回路（サグ補償回路）１２を自動制御しても良い。 FIG. 9 shows the UHF output dependency of the sag amount ratio. When the UHF output is increased and the plasma density is increased, the sag amount ratio is increased. Further, FIG. 10 shows the capacitance dependency of the sag amount ratio formed by a sprayed film for electrostatic chuck or the like. Increasing the capacitor capacity decreases the sag amount ratio. As described above, the cause of the sag is that an effective differentiating circuit is constituted by the capacitor capacity of the sprayed film for the electrostatic chuck provided on the surface of the wafer mounting electrode 9 and the plasma resistance of the generated plasma. It can be said. The sag Vs in the differentiation circuit is generally determined by a resistor R and a capacitor C.

Given in. FIG. 10 shows the calculation result of the capacitor capacity dependency of the sag amount ratio when the plasma resistance is constant. When the high-frequency voltage on the wafer 10 has a waveform with a high sag amount ratio as shown in FIG. 7, the energy distribution increases the energy width at the high energy peak and the low energy peak , and the ion amount at the peak increases. Reduced broad distribution. For this reason, an etching rate , processing accuracy, and a material selection ratio decrease. In order to compensate for the so-called sag in which the absolute value of the high-frequency voltage decreases with time, the high-frequency voltage waveform control circuit (sag compensation circuit) 12 shapes the waveform so that the absolute value of the high-frequency voltage increases with time, It is necessary to apply a high frequency voltage to the wafer mounting electrode 9. Further, since the plasma resistance varies depending on the etching process conditions, the sag amount also varies. In order to generate a rectangular high frequency voltage as shown in FIG. 4 on the wafer 10 regardless of the conditions of the etching process, the high frequency voltage waveform control circuit (sag compensation circuit) 12 must be automatically controlled. In this method, a parameter having a correlation with the sag amount generated on the wafer is used as a monitor amount, and the high-frequency voltage waveform control circuit (sag compensation circuit) 12 is automatically controlled. Further, the high-frequency voltage waveform control circuit (sag compensation circuit) 12 may be automatically controlled using a value obtained by calculating the monitor amount.

  As described above, the absolute value of the high-frequency voltage increases with time, and a voltage waveform that switches between a positive voltage and a negative voltage is applied to the wafer mounting electrode 9, thereby generating a rectangular high-frequency voltage on the wafer 10. High-efficiency and high-precision etching is possible, and the material selection ratio is improved.

FIG. 11 shows a voltage waveform on the wafer 10 when the duty ratio T ₁ / T of the rectangular wave is increased to 50% or more. As the duty ratio increases, the absolute value Vdc of the DC voltage component of the high-frequency voltage increases. That is, the positive voltage decreases. In general, the plasma potential is a positive voltage. The plasma potential when the wafer 10 is positive is about wafer potential + about 20V, and the plasma potential when the wafer 10 is negative is about 20V. Since the processing chamber 1 is grounded, an ion sheath is formed in the vicinity of an effective ground portion on the inner surface of the processing chamber 1, and a high-frequency voltage corresponding to a plasma potential is applied to the ion sheath. Since ions accelerated by the electric field of the ion sheath sputter the wall surface of the processing chamber, the wafer 10 is contaminated with metal, which ultimately causes a problem that the electrical characteristics of the device deteriorate. In general, the smaller the ratio of the wafer 10 area to which the high frequency voltage is applied / the effective earth area is, the Vdc / Vpp ratio (where Vpp is as shown in FIG. The high-frequency voltage peak-to-peak voltage is large. By increasing the diameter of the wafer 10 from φ200 mm to φ300 mm, the ratio of the wafer 10 area / effective earth area is increased and the plasma potential is increased, so that metal contamination countermeasures have become important. In the case of the present embodiment, the plasma potential can be reduced as the duty ratio increases, so that there is an effect that metal contamination can be suppressed.

In each of the above embodiments, the case where a high frequency voltage is applied to the wafer 10 has been described. However, there is no particular limitation as long as the high frequency voltage is applied to the inside of the processing chamber. For example, in the case of an insulating film etching apparatus, a silicon plate is installed at a position facing the wafer 10 and a high frequency voltage is applied to remove excess fluorine radicals in the plasma generated by the chlorofluorocarbon-based gas. Improve selectivity. In the case of such an apparatus, even if the voltage of the silicon plate has a rectangular high-frequency voltage waveform, the same effect is obtained. Further, even if the voltage is set to a rectangular high-frequency voltage waveform on both the wafer 10 and the silicon plate , the same effect can be obtained, and the frequency of both high-frequency voltages is made the same, and the phase difference between the two voltages is controlled (particularly the phase difference) By setting the angle to around 180 degrees, a greater effect (especially a plasma potential suppressing effect) can be obtained. In particular, in the case of an insulating film etching apparatus, since a high-output high-frequency voltage is applied to the wafer 10, the plasma potential increases, the side wall of the processing chamber 1 is sputtered, and the plasma diffuses to the lower portion of the processing chamber 1. Occurrence is a problem. In the case of the present embodiment, since the plasma potential can be suppressed, there is an effect in reducing foreign matter, and there is an effect in that the apparatus operating rate can be improved and the device yield can be improved.

In the above embodiment, the matching unit 11 is used. However, if matching with the plasma load can be achieved to some extent, the matching unit 11 may be a high-frequency transformer or the matching unit 11 may be omitted for simplification. For simplification, the same effect can be obtained even when a voltage waveform in which the absolute value of the high frequency voltage increases with time as shown in FIG. 3 is applied to the wafer mounting electrode 9 by an arbitrary signal generator and a high frequency power amplifier . An effect is obtained. In the above-described embodiment, a rectangular wave is used as an ideal case. However, substantially the same operation and effect can be obtained by using a trapezoidal wave or a similar waveform in which some waveforms are disturbed due to frequency characteristics.

A second embodiment of the present invention will be described with reference to FIG. In this figure, the same reference numerals as those in FIG. The difference between FIG. 1 and FIG. 1 will be described below. The rectangular high-frequency power source 13 includes a DC power source 17 and a switching circuit 18 (chopper circuit). A pulse waveform can be output by repeatedly turning on and off a DC voltage output from a DC power source at high speed by a switching element. As a result, the same effects as those of the first embodiment can be obtained, and the configuration of the rectangular high-frequency power source can be simplified. The switching element used for the switching circuit (chopper circuit) 18 may be a thyristor, a GTO (Gate Turn-Off Thyristor), an IGBT (Insulated Gate Bipolar Transistor), a MOSFET, a power transistor, or the like. Further, by switching these switching elements in series and in parallel, the switching frequency, withstand voltage, and withstand current can be increased, and the frequency of the rectangular wave that can be applied to the wafer can be increased to about several MHz. Further, by controlling the ON / OFF signal of the switching element, a voltage waveform in which the absolute value of the high frequency voltage increases with time as shown in FIG. 3 is generated and applied to the wafer mounting electrode 9. 1 is obtained. In this case, the high-frequency voltage waveform control circuit (sag compensation circuit) 12 can be omitted, and for example, a signal from the electrode current monitor 15 is used as a monitor amount, and the switching circuit 18 (chopper circuit) is automatically controlled.

A third embodiment of the present invention will be described with reference to FIGS. In this figure, the same reference numerals as those in FIG. The difference between this figure and FIGS. 1 and 2 will be described below. The rectangular high frequency power supply 13 is constituted by a sine wave output power supply 19. The sine wave voltage waveform output from the sine wave power source 19 is clipped by the high frequency voltage waveform control circuit (sag compensation circuit) 12 to generate a voltage waveform in which the absolute value of the voltage increases with time in the clip portion. As a result, a waveform close to a rectangular high-frequency voltage waveform can be applied to the wafer . Thereby, the effect similar to Example 1 can be acquired, and the structure of a rectangular high frequency power supply can be simplified.

と定義する。図１７に高エネルギーピーク比率のＶｐｐ依存性を示す。理想の単色のイオンエネルギー分布は高エネルギーピーク比率が１００％であるのに対して、従来の正弦波バイアスでは高エネルギーピーク比率が５０％程度となる。図１５で示したサグ量比率０％の正弦波クリップ電圧波形では高エネルギーピーク比率を約８５％まで増加できる。 FIG. 15B shows a voltage waveform obtained by actually clipping the sine wave voltage waveform and achieving a sag amount ratio of 0% on the wafer . The clip voltage was changed to −400 V and −200 V with respect to the sine wave voltage waveform of Vpp 700 V, and sag compensation was performed to control the sag amount ratio to 0% at the wafer potential. FIG. 15A three-dimensionally shows the measurement result of ion energy distribution in each wafer voltage waveform. In the sine wave voltage waveform of Vpp 700V, the ratio of the amount of ions of the high energy peak and the low energy peak is about 50%. However, the clip voltage is set to -400V and -200V and the flat time of the clip portion is increased. The amount of ions at the energy peak increases. In other words, an ion energy distribution close to a single color can be obtained. Here, the peak ion amount of the low-energy side P _L as shown in FIG. _16, the peak ion of the high energy side as P _H, a high energy peak ratio

It is defined as FIG. 17 shows the Vpp dependence of the high energy peak ratio. The ideal monochromatic ion energy distribution has a high energy peak ratio of 100%, whereas the conventional sine wave bias has a high energy peak ratio of about 50%. In the sine wave clip voltage waveform with the sag amount ratio of 0% shown in FIG. 15, the high energy peak ratio can be increased to about 85%.

FIG. 18 shows the sag amount dependency of the ion energy distribution. FIG. 18B shows a wafer voltage waveform in which sag compensation is performed and the sag amount ratio is changed from 0% to 13% at the wafer potential. FIG. 18A shows the measurement result of the ion energy distribution at each sag amount ratio. Shown in three dimensions. As the sag amount ratio increases, the high energy side peak ion amount PH decreases. FIG. 19 shows the dependence of the high energy peak ratio on the sag amount ratio. In order to achieve a high energy peak ratio of 80% or more and an ion energy distribution close to a single color, the sag amount ratio must be 10% or less.

In the above embodiment, the frequency of the rectangular high frequency power supply 13 is set to 400 kHz and 800 kHz. However, when considering the followability of ions to an alternating electric field, about 10 kHz to 4 MHz is preferable. In particular, considering the incident efficiency of ions to the wafer , 100 kHz To about 2 MHz is preferable.

  In the above embodiment, the etching apparatus using the magnetic field UHF discharge has been described as an example. A dry etching apparatus using a coupled discharge has the same effect. In each of the above embodiments, the etching apparatus has been described. However, other plasma processing apparatuses that perform plasma processing, such as a plasma CVD apparatus, an ashing apparatus, and a surface modification apparatus, have similar operational effects.

The longitudinal cross-sectional view of the magnetic field UHF etching apparatus which is one Example of the plasma processing apparatus of this invention. 1 is a circuit configuration explanatory diagram of a matching unit 11, a high-frequency voltage waveform control circuit (sag compensation circuit) 12, and a DC power supply 14 connected to a wafer mounting electrode 9 in one embodiment of the present invention. The high frequency voltage waveform figure applied to the electrode 9 for wafer mounting in one Example of this invention. The high frequency voltage waveform figure in the wafer 10 in one Example of this invention. The energy distribution diagram of the ion which injects on a wafer at the time of changing the duty ratio of the rectangular high frequency voltage in one Example of this invention. The rectangular high frequency voltage waveform figure applied to the electrode 9 for wafer mounting as a comparative example. The high frequency voltage waveform figure in the wafer 10 at the time of applying a rectangular high frequency voltage to the electrode 9 for wafer mounting as a comparative example. The definition explanatory drawing of the amount of sag of a rectangular wave in one example of the present invention. The graph which shows the relationship between the sag amount ratio in the wafer 10 voltage waveform and UHF output in one Example of this invention. The graph which shows the sag amount ratio and capacitor | condenser capacity | capacitance in the wafer 10 voltage waveform in one Example of this invention. Voltage waveform diagram of the wafer 10 when the duty ratio T _{1 /} T of the rectangular waves was increased to 50% or more in an embodiment of the present invention. The energy distribution explanatory drawing of the ion which injects into a wafer in the case of applying the sinusoidal high frequency voltage in a conventional system to the electrode for wafer mounting. The longitudinal cross-sectional view of the magnetic field UHF etching apparatus which is one Example of the plasma processing apparatus of this invention. The longitudinal cross-sectional view of the magnetic field UHF etching apparatus which is one Example of the plasma processing apparatus of this invention. The wafer 10 voltage waveform which sag-compensated and clipped the sine wave voltage waveform, and the energy distribution diagram of the ion which injects into the wafer 10 in each voltage waveform. The figure explaining the high energy ion ratio in one Example of this invention. The figure which shows the Vpp dependence of the high energy peak ratio in one Example of this invention. The wafer 10 voltage waveform which controlled the sag amount ratio of the sine wave voltage waveform, and the energy distribution diagram of the ion which injects into the wafer 10 in each voltage waveform. The figure which shows the dependence of the sag amount ratio of the high energy peak ratio in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Processing chamber, 1a ... Container, 1b ... Discharge tube, 2 ... Quartz window, 2a ... Shower plate , 3 ... Coil, 4 ... Yoke, 5 ... High frequency power supply, 6 ... Matching device, 7 ... Coaxial waveguide ( cable 8 ... Antenna, 9 ... Wafer mounting electrode, 10 ... Wafer, 11 ... Matching device, 12 ... High frequency voltage waveform control circuit (sag compensation circuit), 13 ... Rectangular high frequency power supply, 14 ... DC power supply, 15 ... Electrode Current monitor, 16 ... automatic control circuit, 17 ... DC power supply, 18 ... switching circuit (chopper circuit), 19 ... sine wave output power supply.

Claims (8)

Plasma generating means for generating plasma in the processing chamber; means for applying a high-frequency voltage to the material to be processed; a processing chamber to which an evacuation device is connected and whose inside can be decompressed; a gas supply device to the processing chamber; In a plasma processing apparatus comprising a substrate electrode disposed in the vacuum processing chamber and having a surface coated with a dielectric to place a material to be processed, and a substrate bias power supply circuit for supplying a substrate bias voltage to the substrate electrode,
The substrate bias power supply circuit is configured as a rectangular high-frequency power supply that has a high-frequency power supply circuit and a high-frequency voltage waveform control circuit and outputs a rectangular high-frequency voltage of a substantially rectangular wave,
The high-frequency voltage waveform control circuit includes a series circuit of a diode and a variable capacitor connected between output terminals of the high-frequency power supply circuit, and a clip circuit including a semiconductor element connected in parallel to the variable capacitor, The diode, the variable capacitor, and the semiconductor element remove a voltage whose absolute value of the positive or negative voltage of the high-frequency voltage waveform output from the high-frequency power circuit is not less than an arbitrary DC voltage , and An operation for changing the DC voltage by changing the capacitance of the variable capacitor and causing the absolute value of the output voltage of the high-frequency voltage waveform control circuit to increase with time ,
A plasma processing apparatus, wherein a high-frequency voltage waveform generated in the material to be processed by the operation is controlled to be a voltage waveform that repeats a positive constant voltage and a negative constant voltage in a given cycle. Plasma generating means for generating plasma in the processing chamber; means for applying a high-frequency voltage to the material to be processed; a processing chamber to which an evacuation device is connected and whose inside can be decompressed; a gas supply device to the processing chamber; In a plasma processing apparatus comprising a substrate electrode disposed in the vacuum processing chamber and having a surface coated with a dielectric to place a material to be processed, and a substrate bias power supply circuit for supplying a substrate bias voltage to the substrate electrode,
The substrate bias power supply circuit is configured as a rectangular high-frequency power supply that has a high-frequency power supply circuit and a high-frequency voltage waveform control circuit and outputs a rectangular high-frequency voltage of a substantially rectangular wave,
The high frequency voltage waveform control circuit includes a series circuit of the high frequency power supply circuit connected to a diode and a variable capacitance capacitor between the output terminals of the clip circuit composed of semiconductor elements connected in parallel to said variable capacitor, The diode, the variable capacitor, and the semiconductor element remove a voltage whose absolute value of the positive or negative voltage of the high-frequency voltage waveform output from the high-frequency power circuit is not less than an arbitrary DC voltage , and varying the DC voltage by varying the capacitance of the variable capacitor and said <br/> be controlled so that rise to slope increases with time to the absolute value of the output voltage of the high frequency voltage waveform control circuit Plasma processing equipment. The plasma processing apparatus according to claim 1 or 2 ,
The plasma processing apparatus , wherein the high-frequency power supply circuit includes a rectangular wave high-frequency power supply or a DC power supply and a switching circuit (chopper circuit) . The plasma processing apparatus according to claim 3 , wherein
A plasma processing apparatus, wherein a switching element of the switching circuit (chopper circuit) is formed of any of a thyristor, a GTO (Gate Turn-Off thyristor), an IGBT (Insulated Gate Bipolar Transistor), a MOSFET, and a power transistor. . In the plasma processing apparatus according to claim 1 or 2 ,
The plasma processing apparatus , wherein the high frequency power supply circuit can vary a duty ratio of an output rectangular wave . The plasma processing apparatus according to claim 1 or 2 ,
The plasma processing apparatus , wherein the high-frequency power supply circuit comprises a sine wave output power supply . The plasma processing apparatus according to any one of claims 1 to 6,
The plasma processing apparatus , wherein the high frequency power supply circuit has an output frequency of 10 kHz to 4 MHz . The plasma processing apparatus according to claim 1 or 2 ,
The high-frequency voltage waveform control circuit (sag compensation circuit) can monitor the current of the wafer mounting electrode, the voltage generated in the processing target material, the current flowing into the processing target material, the voltage of the wafer mounting electrode, At least one of the power applied to the processing material and the output power of the high-frequency power source is detected, and the absolute value of at least one of the positive and negative voltages of the rectangular high-frequency voltage is detected with respect to the monitoring amount. A plasma processing apparatus having a function of controlling the high-frequency voltage waveform generated in the material to be processed to be approximately rectangular, which increases with time .

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