JP2004140391A - Plasma processing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the selection ratio of a mask or/and a base material sufficiently and to perform a highly accurate surface processing. <P>SOLUTION: Plasma generation and the control of a bias voltage to a material to be processed are independently performed. Also, a high frequency voltage waveform for the bias voltage is leveled at an optional voltage, and applied to a substrate electrode 115 on which the material to be processed 116 is mounted and ion energy distribution made incident on the material is controlled as desired. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a plasma processing method and apparatus, and more particularly to a plasma processing method and apparatus suitable for performing surface treatment of a sample such as a semiconductor device using plasma.

When performing an etching process using plasma, the process gas is ionized and activated to increase the speed of the process. In addition, high-frequency bias power is supplied to the material to be processed, and ions in the plasma are vertically incident on the material to be processed. By doing so, high-precision etching processing for anisotropic shapes and the like is realized.

As a plasma processing apparatus for performing such a process, an air-core coil is provided on the outer peripheral portion outside the vacuum vessel, a circular conductor plate is provided so as to face a sample table provided in the vacuum vessel, and a UHF band power supply is provided on the circular conductor plate. A first high-frequency power supply is connected, a second high-frequency power supply is connected to the sample stage, and an electric field having a frequency in the UHF band and an electric field having a frequency different from the frequency in the UHF band are superimposed on the circular conductive plate and supplied. A plasma is formed using an electron cyclotron resonance phenomenon caused by an interaction between an electromagnetic wave generated by a UHF band power supply and a magnetic field generated by an air-core coil. The conductive plate reacts with the plasma so that more active species contributing to etching can be generated. Controls the incident energy on the sample have been proposed (e.g., see Patent Document 1).
JP-A-9-321031 (USP 5,891,252)

In such a conventional apparatus, the ion energy incident on the material to be processed is determined by the self-bias potential generated by the bias power supplied to the material to be processed. Since the ratio of the ground area decreases, sufficient supply of electrons from the plasma to the substrate electrode is not performed.
Therefore, the ratio of Vdc / Vpp decreases and the plasma potential increases. As a result, the application efficiency of the RF bias is reduced, the ground electrode and the side wall member are sputtered by ions in the plasma to generate metal contamination, and the plasma is diffused into the space below the processing chamber to increase foreign substances. There is a problem of doing.

Further, a high frequency electric field of a sine wave is applied to the sample stage, that is, the substrate electrode. With a high frequency bias having a fixed frequency, the ion energy distribution is fixed, and with the miniaturization of semiconductor elements, SAC (Self) is applied. In the case of a material to be processed typified by (Aligned @ Contact), if the processing is performed while maintaining the etching rate, the selectivity between the mask and the base material becomes small, and it is difficult to perform high-precision processing.

A first object of the present invention is to provide a plasma processing method and apparatus capable of performing a high-precision surface treatment while ensuring a sufficient selection ratio with respect to a mask and / or a base material.

A second object of the present invention is to provide a plasma processing method and apparatus capable of suppressing an increase in plasma potential and suppressing an increase in metal contamination and foreign matter.

The object is to independently control the generation of a plasma and the application of a bias voltage to a sample, and to perform a plasma treatment on the sample, wherein a bias voltage to be applied to the sample is given as a high-frequency voltage, and the voltage waveform of the high-frequency voltage is changed to an arbitrary voltage. This is achieved by flattening with.

(4) The voltage waveform on the negative voltage side of the high-frequency voltage applied to the substrate electrode is flattened.

(4) The voltage waveform on the positive voltage side of the high-frequency voltage applied to the substrate electrode is flattened.

(4) The voltage waveform on both the positive and negative sides of the high frequency voltage applied to the substrate electrode is flattened.

Also, an electrode facing the substrate electrode is provided, and a high-frequency voltage of the same frequency is applied to both electrodes, and the phase of the high-frequency voltage is controlled.

To achieve the above object, according to one aspect of the present invention, a plasma processing apparatus includes a processing chamber to which a vacuum exhaust device is connected, the inside of which can be depressurized, and a gas supply device that supplies gas into the processing chamber. A substrate electrode provided in the processing chamber, on which a material to be processed can be placed, a high-frequency power supply connected to the substrate electrode via a matching device, plasma generating means for generating plasma in the processing chamber; A voltage waveform control circuit for flattening a voltage waveform provided inside the container or between the substrate electrode and the matching device is included.

The voltage waveform control circuit is a circuit that flattens the negative voltage side of the high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage.

The voltage waveform control circuit is a circuit that flattens the positive voltage side of the high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage.

The voltage waveform control circuit is a circuit for flattening both positive and negative voltage sides of the high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage.

The voltage waveform control circuit includes a semiconductor device and a DC power supply.

Also, an electrode facing the substrate electrode was provided, and a high-frequency power supply was connected to the electrode.

{Circle around (2)} Further, the frequency of the high-frequency voltage applied to the two electrodes is made the same, and a phase controller for controlling the phase difference between the high-frequency voltages is provided.

According to another aspect of the present invention, a method of independently controlling the generation of a plasma and the application of a bias voltage to a sample, and performing a plasma treatment on the sample includes providing the bias voltage to be applied to the sample with a high-frequency voltage, Flattening the voltage waveform of the voltage to an arbitrary voltage on the positive voltage side and the negative voltage side.

Further, in the above method, an electrode facing the substrate electrode is provided, and a high-frequency voltage having the same frequency is applied to both electrodes, and a phase of the high-frequency voltage is controlled.

(4) The phase of the high-frequency voltage has a phase difference within a range of 180 ° ± 30 °.

According to another aspect of the present invention, a plasma processing apparatus includes a processing chamber to which an evacuation device is connected and whose inside can be depressurized, a gas supply device for supplying gas into the processing chamber, and a plasma processing apparatus provided in the processing chamber. A substrate electrode on which a processing material can be placed, a high-frequency power supply connected to the substrate electrode via a matching device, plasma generation means for generating plasma in the processing chamber, and the inside of the matching device or the substrate electrode; A voltage waveform control circuit is provided between the matching device and the flattening device to flatten the high-frequency voltage waveform to an arbitrary voltage on the positive voltage side and an arbitrary voltage on the negative voltage side.

に お い て In the above device, the voltage waveform control circuit includes a diode and a DC power supply.

Also, an electrode facing the substrate electrode was provided, and a high-frequency power supply was connected to the electrode.

{Circle around (2)} Further, the frequency of the high-frequency voltage applied to the two electrodes is made the same, and a phase controller for controlling the phase of the high-frequency voltage is provided.

Furthermore, the phase controller can control the phase difference within a range of 180 ° ± 30 °.

According to another aspect of the present invention, there is provided a method of performing plasma processing on a sample in a processing chamber in which plasma is generated, comprising applying a high-frequency voltage to a sample stage on which the sample is placed, and changing a voltage waveform of the high-frequency voltage to an arbitrary voltage. And flattening.

(4) In the above method, at least one of the positive and negative high-frequency voltages applied to the substrate electrode is flattened.

A plasma processing apparatus according to another embodiment of the present invention includes a processing chamber to which a vacuum exhaust device is connected and whose inside can be depressurized, a gas supply device that supplies gas into the processing chamber, and a processing object provided in the processing chamber. A mountable substrate electrode, a high-frequency power supply connected to the substrate electrode via a matching device, and a voltage for flattening a voltage waveform provided in the matching device or between the substrate electrode and the matching device. Includes waveform control circuit.

In the above device, the voltage waveform control circuit can flatten at least one of the positive and negative voltages of the high-frequency voltage applied to the substrate electrode.

As described above, by controlling the high-frequency voltage waveform applied to the substrate electrode, the distribution of ion energy incident on the sample can be controlled, and the ion energy mainly contributes to the etching of the material to be etched. Since the distribution of ion energy that does not contribute to the etching of the material can be obtained, it is possible to perform a high-precision surface treatment with a sufficient selection ratio between the mask and the base material without greatly changing the speed. it can.

Also, by flattening the voltage on the negative side of the high-frequency voltage applied to the substrate electrode, the width of the ion energy distribution that has been widened vertically can be narrowed, and a large amount of ion energy useful for processing can be distributed. As a result, the efficiency of the plasma processing can be improved.

Further, by flattening the voltage on the positive voltage side in accordance with the flattening of the voltage on the negative voltage side, a stable plasma potential can be obtained, and the plasma processing can be stabilized, and the plasma characteristics can be improved. Since the influence of the in-plane distribution of the plasma sheath characteristics caused by the in-plane distribution is reduced, charging damage can be suppressed, and low-damage and high-accuracy etching can be performed.

Further, an electrode is provided facing the substrate electrode, a high-frequency voltage of the same frequency is applied to both electrodes, and the phase difference between the high-frequency voltages is set within a range of 180 ° ± 30 °, so that the positive voltage side of the high-frequency voltage is reduced. Since a potential rise can be suppressed, a stable plasma potential can be obtained, and plasma processing can be stabilized.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a longitudinal sectional view of an etching apparatus as an example of a plasma processing apparatus to which the present invention is applied. At the upper opening of the vacuum vessel 101, a cylindrical processing vessel 102, a flat plate-like antenna electrode 103 made of a conductor, and a dielectric window 104 capable of transmitting electromagnetic waves are hermetically provided, and a processing chamber is formed therein. I have. A magnetic field generating coil 105 is provided on the outer periphery of the processing container 102 so as to surround the processing chamber. The antenna electrode 103 has a porous structure for flowing an etching gas, and is connected to a gas supply device 107. A vacuum exhaust device (not shown) is connected to a lower portion of the vacuum vessel 101 via a vacuum exhaust port 106.

同軸 A coaxial line 108 is provided above the antenna electrode 103, and a high-frequency power supply 111 (for example, frequency 450 MHz) for plasma generation is connected via the coaxial line 108, a filter 109, and a matching unit 110. In addition, an antenna bias power supply 114 (for example, a frequency of 13.56 kHz) is connected to the antenna electrode 103 via a coaxial line 108, a filter 112, and a matching unit 113. Here, the filter 109 allows the high-frequency power from the high-frequency power supply 111 to pass, and effectively cuts the bias power from the antenna bias power supply 114. The filter 112 allows the bias power from the antenna bias power supply 114 to pass, and effectively cuts the high-frequency power from the high-frequency power supply 111.

基板 A substrate electrode 115 on which a material to be processed 116 can be arranged is provided at a lower portion in the vacuum vessel 101. A substrate bias power supply 119 (for example, a frequency of 800 kHz) is connected to the substrate electrode 115 via a filter 117 and a matching unit 118. In this case, the matching unit 118 includes a matching unit 200 on the power supply side and a clip circuit 201 on the load side. Note that the clip circuit 201 may be provided separately from the inside of the matching unit 118. The clip circuit 201 flattens a high-frequency voltage waveform from the substrate bias power supply 119 with an arbitrary voltage value. The clip circuit 201 has the function of the embodiment described later. Further, an electrostatic chuck power supply 121 for electrostatically adhering the processing target material 116 via a filter 120 is connected to the substrate electrode 115.

Here, the filter 117 allows the bias power from the substrate bias power supply 119 to pass, and effectively cuts the high-frequency power from the high-frequency power supply 111 and the bias power from the antenna bias power supply 114. Normally, the high frequency power is absorbed in the plasma and does not flow to the substrate electrode 115 side, but is provided as a filter 117 for cutting the high frequency power for safety. The filter 120 allows DC power from the electrostatic chuck power supply 121 to pass therethrough, and effectively cuts power from the high frequency power supply 111, the antenna bias power supply 114, and the substrate bias power supply 119.

FIG. 2 shows a circuit configuration example of the matching unit 118. A diode (D1) and a DC power supply (Vb1) are connected in series between the active line 202 and the ground line 203 on the load side of the matching unit 200 including the inductors (L1 and L2) and the capacitor (C1). A clip circuit (flattening circuit) 201a is connected. In this case, the diode (D1) cuts the negative side of the high frequency voltage and gives a negative potential by the DC power supply (Vb1). Thus, the operating voltage of the diode (D1) is set according to the set value of the DC power supply (Vb1). With this circuit configuration, a voltage waveform can be clipped (flattened or cut) with an arbitrary voltage value, and a voltage waveform 301 of a high-frequency voltage as shown in FIG. 3 can be obtained.

In the apparatus configured as described above, the inside of the processing chamber is depressurized by a vacuum exhaust device (not shown), and then a process gas, in this case, an etching gas, is introduced into the processing chamber by the gas supply device 107 and adjusted to a desired pressure. . For example, high-frequency power of a frequency of 450 MHz oscillated from the high-frequency power supply 111 propagates through the coaxial line 108 and is introduced into the processing chamber via the upper electrode 103 and the dielectric window 104. The electric field generated by the high-frequency power introduced into the processing chamber generates high-density plasma in the processing chamber by interaction with a magnetic field generated in the processing chamber by the magnetic field generating coil 105, for example, a solenoid coil. In particular, when a magnetic field intensity (for example, 160 G) that causes electron cyclotron resonance is formed in the processing chamber, high-density plasma can be efficiently generated.

Further, high-frequency power (for example, frequency of 13.56 MHz) is supplied from the antenna bias power supply 114 to the antenna electrode 103 via the coaxial line 108. When a high-frequency voltage is applied to the antenna electrode 103 by the antenna bias power supply 114, when a desired material is used for the antenna electrode, the material reacts with radicals in the plasma, and the composition of the generated plasma can be controlled. For example, when the oxide film etching, by using a Si material of the antenna electrode 103, the etching characteristics of the oxide film, in particular those of the SAC _structure, the F amount of radicals in the plasma that affects the SiO 2 / SiN selection ratio, etc. It can be reduced.

Further, high frequency power (for example, 800 kHz) is supplied from the substrate bias power supply 119 to the processing target material 116 placed on the substrate electrode 115, and the processing target material 116 on the substrate electrode 115 is subjected to surface processing. It is processed.

In the apparatus having this configuration, plasma is mainly generated by the 450 MHz high frequency power supply 111, the plasma composition or plasma distribution is controlled by the antenna bias power supply 114, and the incident energy of ions in the plasma to the workpiece 116 is controlled by the substrate bias power supply 119. Is controlling. Such an apparatus has an advantage that the plasma generation (ion amount) and the plasma composition (radical concentration ratio) can be controlled independently.

By arbitrarily setting the DC power supply (Vb) in the clipping circuit 201a of the present apparatus, the Vb of the voltage waveform 301 shown in FIG. 3 can be arbitrarily set. Can be clipped at the voltage.

FIG. 4A shows the energy of ions incident on the workpiece 116 when the output of the substrate bias power supply 119 is fixed and the DC voltage (Vb1) is changed to control the clip voltage (Vb) of the voltage waveform 301. Shows the distribution. FIG. 4B shows the energy of ions incident on the workpiece 116 when the output of the substrate bias power supply 119 is changed while the value of the clip voltage (Vb) of the voltage waveform 301 is kept constant by the DC power supply (Vb1). Shows the distribution. The vertical axis represents the ion amount and the horizontal axis represents the ion energy. Generally, the ion energy distribution when high frequency power is applied to a wafer is described by M.P. J. Kushner, @J. {Appl. {Phys. As shown in # 58 and # 4024 (1985), it is known that the distribution has peaks at two places on the high energy side and the low energy side. FIG. 4A shows an ion energy distribution waveform 401 when a sine wave voltage waveform is applied to the substrate electrode 115, an ion energy distribution waveform 402 when the clip voltage (Vb) is set to −500 V, and a clip voltage. The ion energy distribution waveform 403 when (Vb) is set to -250 V is shown three-dimensionally. As shown in the figure, by keeping the output of the substrate bias power supply 119 constant and changing the clipping voltage (Vb) to -500 V and -250 V, the potential value of the ion energy distributed more on the high energy side is gradually increased. It can be shifted to a lower potential value. At the same time, the amount of ions distributed on the high energy side can be gradually increased.

FIG. 4B shows the ion energy distribution waveform 404 when the clip voltage (Vb) of the substrate electrode 115 is set to −500 V and the output of the substrate bias power supply 119 is 500 W, An ion energy distribution waveform 405 when the output is 1000 W and an ion energy distribution waveform 406 when the output of the substrate bias power supply 119 is 1500 W are shown three-dimensionally. As shown in the drawing, the value of the clip voltage (Vb) is kept constant, and the output of the substrate bias power supply 119 is gradually increased, so that the amount of ions of ion energy distributed on the high energy side is gradually increased. be able to.

As described above, it is possible to control the ion energy distribution by adjusting the bias voltage waveform applied to the substrate electrode 115. Further, by controlling the ion energy distribution in accordance with the output of the substrate bias power supply, a finer ion energy can be obtained. The distribution can be controlled. Thus, ions having an arbitrary ion energy can be efficiently incident on the material to be processed 116. Therefore, by using a distribution having a large amount of ions with high ion energy, for example, as shown in FIG. Processing of HARC (High Aspect Ratio Contact) formed in SiO ₂ which is a deep hole (a deep hole having a diameter of 0.1 μm and a depth of 2 μm such as an aspect ratio of 20) and deep trench formed in Si becomes easy. .

In addition, it is possible to select and control ion energy that is effective for the material to be processed and is not effective for the mask and the base material. Can be performed. Thereby, there is an effect that high-quality etching can be performed.

In the case of oxide film etching, high-energy ions are incident, which may cause lattice defects in the underlying film or the like and cause damage. However, according to the ion energy control of this embodiment, the etch rate is reduced. Etching can be performed while ensuring no damage, and surface processing with high quality and high throughput and high yield can be performed.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows a circuit configuration example of the matching unit 118. This drawing is different from FIG. 2 in that the clipping circuit 201a shown in FIG. 2 has a diode (D1) and a DC power supply (Vb2) connected in opposite directions, and a diode (D2) and a DC power supply (Vb2). (Planarization circuit) 201b. In this case, the diode (D2) cuts the positive side of the high-frequency voltage and gives a positive potential by the DC power supply (Vb2). Thus, the operating voltage of the diode (D2) is set according to the set value of the DC power supply (Vb2). With this circuit configuration, a voltage waveform can be clipped (flattened or cut) at an arbitrary voltage value, and a voltage waveform 302 of a high-frequency voltage as shown in FIG. 7 can be obtained.

By setting the DC power supply (Vb2) in the clipping circuit 201b of the present apparatus to an arbitrary clipping voltage, the voltage Vb of the voltage waveform 302 shown in FIG. 7 can be set arbitrarily. The positive side can be clipped at any voltage.

FIG. 8 shows the energy distribution of ions incident on the material 116 when the voltage waveform 302 is controlled by changing the DC power supply (Vb2). The vertical axis represents the ion amount and the horizontal axis represents the ion energy. FIG. 8 shows an ion energy distribution waveform 401 when a sine wave voltage waveform is applied to the substrate electrode 115, an ion energy distribution waveform 407 when the positive voltage side clip voltage (Vb) is set to 50 V, and a negative voltage. 7 shows an ion energy distribution waveform 408 when the clip voltage (Vb) on the side is set to −600 V. As shown in the figure, by setting the clip voltage (Vb) to 50 V and suppressing the plasma potential, the potential value of the ion energy distributed more on the high energy side is reduced, and the amount of ions distributed on the lower energy side is reduced. Can be increased. As can be seen from FIG. 8, if the negative voltage side of the voltage waveform is clipped, a distribution with a large amount of ions of high ion energy can be obtained, and if the positive voltage side of the voltage waveform is clipped, the amount of ions of low ion energy can be reduced. There can be many distributions.

Therefore, by adjusting the bias voltage waveform applied to the substrate electrode 115, the ion energy distribution can be controlled. Accordingly, ions having an arbitrary ion energy can be efficiently incident on the processing target material 116. Therefore, by using a distribution having a large amount of ions with low ion energy, for example, as shown in FIG. This is effective for the SAC etching process that requires a selectivity with the underlying material.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 10 shows a circuit configuration example of the embodiment in addition to the matching unit 118. Diodes (D1, D2) and DC power supplies (Vb1, Vb2) are provided between the active line 202 and the ground line 203 on the load side of the matching unit 200 composed of the inductors (L1, L2) and the capacitor (C1). A clip circuit (flattening circuit) 201c connected in series is connected. The diode (D1) cuts off the negative voltage side of the high-frequency voltage and gives a negative potential by the DC power supply (Vb1), and sets the operating voltage of the diode (D1) by the set value of the DC power supply (Vb1). The diode (D2) cuts off the positive voltage side of the high frequency voltage and gives a positive potential by the DC power supply (Vb2), and sets the operating voltage of the diode (D2) by the set value of the DC power supply (Vb2). With this circuit configuration, the voltage waveform can be clipped (flattened or cut) at arbitrary voltage values on the positive voltage side and the negative voltage side, and a voltage waveform 303 of a high-frequency voltage as shown in FIG. 12 can be obtained. . FIG. 12 shows a voltage waveform 303 applied to the substrate electrode 115 output using the clip circuit 201c of the matching unit 118. The vertical axis is voltage and the horizontal axis is time.

FIG. 11 shows another example of the matching unit 118. In this matching device, a clipping circuit 201d in which switching elements, for example, transistors Tr1 and Tr2 are provided on the active line 202 on the load side of the matching unit 200, and DC power supplies Vb1 and Vb2 are connected to base electrodes of the transistors Tr1 and Tr2. Is provided. The clipping circuit 201d performs switching operation of the transistors according to the set values of the DC power supplies Vb1 and Vb2, thereby setting the positive voltage side and the negative voltage side of the voltage waveform to arbitrary voltage values in the same manner as the matching device shown in FIG. It is possible to clip with.

で は In the clip circuit 201c shown in FIG. 10, when the amount of DC current passing through the diode is large, the operating voltage of the diode may fluctuate because a voltage drop occurs due to the internal resistance of the DC power supply. However, when the transistor shown in FIG. 11 is used, the voltage fluctuation due to the internal resistance of the DC power supply can be ignored, so that the clipping operation can be performed with high accuracy.

任意 By arbitrarily setting the DC power supplies (Vb1, Vb2) in the clipping circuits 201c and 201d in FIGS. 10 and 11, for example, a sine wave voltage waveform having a frequency of 800 kHz can be clipped with an arbitrary voltage. Thus, by changing the DC power supply (Vb) and controlling the voltage waveform 303, the energy distribution of ions incident on the material to be processed 116 can be made the energy distribution as shown in FIGS. 4 and 8 described above. .

By using a clipping circuit that can clip the positive voltage side and the negative voltage side of such a voltage waveform with an arbitrary voltage value, the same operation and effect as those of the first and second embodiments can be obtained. In addition to this, it is also possible to provide both characteristics, so that there is an effect that the process window can be further expanded.

As described above, according to these embodiments, since the voltage waveform of the high-frequency voltage applied to the substrate electrode can be flattened, it is possible to apply a bias voltage having an optimum ion energy distribution to the substrate electrode in each of various processes. Thus, there is an effect that highly accurate surface treatment can be performed.

In addition, by flattening the positive voltage side of the voltage waveform of the high-frequency voltage applied to the substrate electrode, it is possible to suppress an increase in the plasma potential, so that ions in the plasma do not sputter the inner wall of the processing chamber. Since contamination can be reduced and plasma diffusion into the space below the processing chamber can be prevented, there is an effect that an increase in foreign substances can be suppressed.

The clipping circuits shown in the first to third embodiments are not limited to the above-described configuration, but may use the configuration of a clipping circuit generally used in an electronic circuit.

In these embodiments, a magnetic field UHF plasma processing apparatus having an antenna electrode in a vacuum vessel has been described as an example, but a magnetic field UHF plasma processing apparatus having an antenna electrode outside the vacuum vessel as shown in FIG. Also applicable to 1 differs from the apparatus in FIG. 1 in that the processing chamber is airtightly configured by the processing container 102 and the dielectric window 123, and the antenna electrode 103 is provided above the dielectric window 123, outside the processing chamber, that is, The point is that the antenna electrode 103 is disposed outside the vacuum vessel, and the antenna electrode 103 is provided with only the circuit of the high frequency power supply 111 for plasma generation.

In addition, devices other than the UHF plasma device, for example, CCP (capacitively coupled @ plasma), dual-frequency excitation (Dual-frequency @ plasma), SWP (surface @ wave @ excited @ plasma), magnetron devices, VHF plasma, etc. Is similarly applicable. 14 to 16 show some of these devices. In the apparatus shown in FIG. 14, a processing window is formed by installing and sealing a dielectric window 603 on the upper part of the processing container 102 whose upper part is opened. A magnetron 601 is connected to the upper part of the dielectric window 603 via a waveguide 602. The microwave of, for example, 2.45 GHz emitted from the magnetron 601 propagates through the waveguide 602, is introduced into the processing chamber through the dielectric window 603, and is generated by the magnetic field generating coil 105, for example. The apparatus efficiently ionizes gas to generate plasma by interacting with a 875 G magnetic field. In this drawing, the same reference numerals as those in FIG. 1 denote the same members, and a description thereof will be omitted.

装置 In the apparatus shown in FIG. 15, a dielectric window 603 is installed and sealed on the upper part of the processing container 102 whose upper part is opened to form a processing chamber. A loop antenna 701 is provided above the dielectric window 603. The loop antenna 701 is connected to, for example, a 13.56 MHz antenna power supply 702. High-frequency power is supplied from a loop antenna 701 through a dielectric window 603 into a processing chamber to generate plasma. In this drawing, the same reference numerals as those in FIG. 1 denote the same members, and a description thereof will be omitted.

装置 The apparatus shown in FIG. 16 has a dielectric window 104 (for example, made of quartz) and an upper electrode 103 placed and sealed on the upper part of the processing container 102 whose upper part is sealed. The upper electrode 103 is connected to, for example, a high frequency power supply 801 of 27 MHz or 60 MHz. In this apparatus, plasma is generated by high-frequency power supplied from the upper electrode 103 into the processing chamber. In this drawing, the same reference numerals as those in FIG. 1 denote the same members, and a description thereof will be omitted.

A fourth embodiment of the present invention will be described with reference to FIG. In this figure, the same reference numerals as those in FIG. 1 denote the same members, and a description thereof will be omitted. The difference between this figure and FIG. 1 will be described below. The antenna bias power supply 114 and the substrate bias power supply 119 are connected to a phase controller 122 so that the phase of a high frequency output from the antenna bias power supply 114 and the substrate bias power supply 119 can be controlled. In this case, the frequencies of the antenna bias power supply 114 and the substrate bias power supply 119 are, for example, 800 kHz, which are the same.

The phase controller 122 takes in power signals from between the filter 112 and the matching unit 113 on the antenna bias power supply 114 side and between the filter 117 and the matching unit 118 on the substrate bias power supply 119 side, respectively. A small-amplitude signal whose phases are shifted to the antenna bias power supply 114 and the substrate bias power supply 119 is output so that the phases of the respective powers are opposite phases, in this case, a desired phase difference within 180 ° ± 45 °. . In this case, the antenna bias power supply 114 and the substrate bias power supply 119 need only have an amplifier function.

Further, the phase controller 122 takes in power signals from between the filter 112 and the matching unit 113 on the side of the antenna bias power supply 114 and between the filter 117 and the matching unit 118 on the side of the substrate bias power supply 119, respectively, and outputs the power output timing. In this case, the antenna bias power supply 114 and the substrate bias power supply 119 have an oscillator function.

When the high-frequency voltages applied to the antenna electrode 103 and the substrate electrode 115 are in opposite phases (preferably within the range of 180 ° ± 30 °), for example, when a positive voltage is applied to the substrate electrode 115, Since a negative voltage is applied to the antenna electrode, ions are incident on the antenna electrode 103 but electrons are not incident, and the vicinity of the antenna electrode 103 is in an electron-rich state, and the opposing electrode efficiently functions as a ground. Therefore, the plasma potential is fixed to a voltage value of about 20 to 30 V, which is almost 0 V, from the peak voltage value of the high-frequency voltage regardless of the high-frequency power, so that the matching unit 118 described in the first embodiment is used. Thereby, the ion energy control effect on the substrate electrode 115 side can be realized with higher accuracy. This also has the effect that charging damage can be reduced.

Further, by providing a clipping circuit similar to the clipping circuit 201 of the matching device 118 provided on the substrate electrode 115 side also on the matching device 113 provided on the antenna electrode 103 side, the voltage waveform of the bias voltage of the antenna electrode 103 is further reduced. Control allows the window for further processing to be widened.

As described above, according to the present invention, by adjusting the high-frequency voltage waveform applied to the substrate electrode, the energy potential and amount of ions in the ion energy distribution can be controlled, and highly accurate plasma processing and plasma processing with less charging damage can be performed. There is an effect that it becomes possible.

Although the etching apparatus has been described in the above embodiments, the present invention can be similarly applied to other plasma processing apparatuses that supply high-frequency power to the substrate electrode, such as an ashing apparatus and a plasma CVD apparatus.

FIG. 1 is a longitudinal sectional view showing a plasma processing apparatus according to a first embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a matching device of the device in FIG. 1. FIG. 3 is a diagram illustrating an example of a voltage waveform controlled using the matching device in FIG. 2. FIG. 4 is a diagram showing the relationship between the value of the DC voltage (Vb) in FIG. 3 and the ion energy distribution. FIG. 2 is a longitudinal sectional view showing an example of a workpiece to be etched using the apparatus shown in FIG. 1. FIG. 4 is a circuit diagram showing a second embodiment of the present invention and an example of a matching device of the apparatus shown in FIG. 1. FIG. 7 is a diagram illustrating an example of a voltage waveform controlled using the matching device of FIG. 6. The figure which shows the relationship between the value of the direct-current voltage (Vb) of FIG. 7, and ion energy distribution. FIG. 7 is a longitudinal sectional view showing an example of a workpiece to be etched by an apparatus using the matching device of FIG. 6. FIG. 6 is a circuit diagram showing a third embodiment of the present invention and an example of a matching device of the device shown in FIG. 1. FIG. 11 is a circuit diagram showing another example of the matching device in FIG. 10. FIG. 12 is a diagram illustrating an example of a voltage waveform controlled using the matching device of FIGS. 10 and 11. FIG. 9 is a longitudinal sectional view showing a plasma processing apparatus according to a fourth embodiment of the present invention. FIG. 13 is a vertical sectional view showing a plasma processing apparatus according to a fifth embodiment of the present invention. FIG. 13 is a longitudinal sectional view showing a plasma processing apparatus according to a sixth embodiment of the present invention. FIG. 13 is a vertical sectional view showing a plasma processing apparatus according to a seventh embodiment of the present invention. FIG. 14 is a vertical sectional view showing a plasma processing apparatus according to an eighth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... vacuum container, 102 ... processing container, 103 ... antenna electrode, 104 ... dielectric window, 105 ... magnetic field generating coil, 106 ... vacuum exhaust port, 107 ... gas supply device, 108 ... coaxial line, 109, 112, 117 , 120: filter, 110, 113, 118: matching unit, 111: high-frequency power supply, 114: antenna bias power supply, 115: substrate electrode, 116: material to be processed, 119: substrate bias power supply, 121: electrostatic chuck power supply, 122 ... Phase controller, 200, matching unit, 201, 201a, 201b, 201c, 201d, clipping circuit, 202, active line, 203, ground line.

Claims (19)

In the method of independently controlling the generation of a plasma and the application of a bias voltage to a sample, and applying a bias voltage to the sample as a high-frequency voltage, and flattening the voltage waveform of the high-frequency voltage at an arbitrary voltage in the method of plasma-treating the sample. A plasma processing method comprising: A plasma processing method according to claim 1, wherein the voltage waveform on the negative voltage side of the high-frequency voltage applied to the substrate electrode is flattened. A plasma processing method according to claim 1, wherein a voltage waveform on the positive voltage side of the high-frequency voltage applied to the substrate electrode is flattened. A plasma processing method according to claim 1, wherein a voltage waveform on both positive and negative sides of a high frequency voltage applied to the substrate electrode is flattened. The plasma processing method according to claim 1, wherein an electrode facing the substrate electrode is provided, a high-frequency voltage having the same frequency is applied to both electrodes, and a phase of the high-frequency voltage is controlled. A processing chamber to which a vacuum evacuation device is connected, the inside of which can be depressurized; a gas supply device for supplying gas into the processing chamber; a substrate electrode provided in the processing chamber and capable of mounting a material to be processed; A high-frequency power supply connected via a matching device, plasma generating means for generating plasma in the processing chamber, and a voltage for flattening a voltage waveform provided in the matching device or between the substrate electrode and the matching device. A plasma processing apparatus, comprising: a waveform control circuit. 7. The plasma processing apparatus according to claim 6, wherein the voltage waveform control circuit includes a circuit for flattening a negative voltage side of a high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage. 7. The plasma processing apparatus according to claim 6, wherein the voltage waveform control circuit includes a circuit for flattening a positive voltage side of a high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage. 7. The plasma processing apparatus according to claim 6, wherein the voltage waveform control circuit includes a circuit for flattening both positive and negative voltage sides of a high-frequency voltage waveform applied to the substrate electrode with an arbitrary voltage. 7. The plasma processing apparatus according to claim 6, wherein the voltage waveform control circuit includes a semiconductor element and a DC power supply. 7. The plasma processing apparatus according to claim 6, wherein an electrode facing the substrate electrode is provided, and a high-frequency power supply is connected to the electrode. The plasma processing apparatus according to claim 11, wherein a high-frequency voltage having the same frequency is applied to the two electrodes, and a phase controller that controls a phase difference between the high-frequency voltages is provided. The plasma processing method according to claim 5, wherein the phase of the high-frequency voltage has a phase difference within a range of 180 ° ± 30 °. 7. The plasma processing apparatus according to claim 6, wherein the voltage waveform control circuit includes a diode and a DC power supply. 13. The plasma processing apparatus according to claim 12, wherein the phase controller can control a phase difference within a range of 180 ° ± 30 °. In a method of performing plasma processing on a sample in a processing chamber in which plasma is generated, a high-frequency voltage is applied to a sample stage on which the sample is placed, and a voltage waveform of the high-frequency voltage is flattened by an arbitrary voltage. Plasma processing method. 17. The plasma processing method according to claim 16, wherein at least one of a positive and a negative voltage of a high frequency voltage applied to the substrate electrode is flattened. A processing chamber to which a vacuum evacuation device is connected, the inside of which can be depressurized; a gas supply device for supplying gas into the processing chamber; a substrate electrode provided in the processing chamber and capable of mounting a material to be processed; A plasma, comprising: a high-frequency power supply connected via a matching device; and a voltage waveform control circuit for flattening a voltage waveform provided in the matching device or between the substrate electrode and the matching device. Processing equipment. 19. The plasma processing apparatus according to claim 18, wherein the voltage waveform control circuit is capable of flattening at least one of a positive and a negative voltage of a high frequency voltage applied to the substrate electrode.

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