JP4272646B2 - Etching device - Google Patents

Description

  The present invention relates to an etching apparatus, and more particularly to an etching apparatus having an inductively coupled plasma source used in a manufacturing process of a semiconductor, an electronic component, or the like.

  In an etching apparatus having a conventional inductively coupled plasma source, the introduced gas molecules are decomposed into plasma, and the decomposition products adhere to the inner wall of the chamber, and the etching products adhere to the inner wall. It was. For this reason, adhesion was prevented by controlling the whole chamber to high temperature, or providing a heat-proofing board on the wall surface.

  As an etching apparatus having an inductively coupled plasma source, for example, a magnetic neutral line discharge etching apparatus as described below has been proposed (see, for example, Patent Documents 1 and 2).

  FIG. 1 schematically shows a schematic configuration of a magnetic neutral wire discharge etching apparatus described in Patent Document 1. As shown in FIG. 1, this etching apparatus has a vacuum chamber 1, the upper part of which is a plasma generating part 2 formed by a dielectric cylindrical wall, and the lower part is a substrate electrode part 3. An annular magnetic neutral line 7 is formed in the plasma generating unit 2 by the three magnetic field coils 4, 5 and 6 provided outside the wall (dielectric side wall) of the plasma generating unit 2. A high frequency antenna coil 8 for plasma generation is disposed between the intermediate magnetic field coil 5 and the outside of the dielectric side wall. This high frequency antenna coil 8 is connected to a high frequency power source 9 and is connected to three magnetic field coils 4, 5, 6. An alternating electric field is applied along the magnetic neutral line 7 formed by the above to generate discharge plasma in the magnetic neutral line.

  A substrate electrode 10 is provided in the lower substrate electrode portion 3 through an insulator member 11 in parallel with the surface formed by the magnetic neutral wire 7. The substrate electrode 10 is connected to a high-frequency power source 13 that applies a high-frequency bias power via a blocking capacitor 12 and is a floating electrode in terms of potential by the blocking capacitor 12 and has a negative bias potential. The top plate 14 of the plasma generator 2 is hermetically fixed to the upper flange of the dielectric side wall to form a counter electrode. The plasma generation unit 2 is provided with a gas introduction port 15 for introducing a etching gas into the vacuum chamber 1, and this gas introduction port 15 is a gas that controls the flow rate of the gas supply path and the etching gas, although not shown. It is connected to an etching gas supply source via a flow rate control device. The substrate electrode portion 3 is provided with an exhaust port 16.

  The magnetic neutral line discharge etching apparatus described in Patent Document 2 has the structure of the etching apparatus shown in FIG. 1, and further, the top plate is hermetically fixed to the upper flange of the side wall (dielectric side wall) of the plasma generation unit via an insulator. The three-frequency discharge method is configured to be installed at a position facing the substrate electrode 10 and to connect a high-frequency bias power source to the top plate 14 via a capacitor so that a weak high-frequency bias can be applied to the top plate. It is related to. The top plate as the counter electrode functions as a floating electrode. In this way, high-frequency power is applied to the counter electrode, the substrate electrode, and the plasma generating antenna coil.

  FIG. 2 schematically shows a schematic configuration of a magnetic neutral wire discharge etching apparatus described in Japanese Patent Application No. 2001-149825 proposed by the same applicant as the present case. In the figure, elements having the same names as those of the conventional example of FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

The etching apparatus shown in FIG. 2 is a two-frequency discharge method that is an improved version of the three-frequency discharge method. In this etching apparatus, a ground electrode provided at a position facing the substrate electrode 10 is configured as a counter electrode that is floated in potential by a dielectric, and weak high-frequency bias power is applied to the counter electrode (top plate 14). It can be applied. A branch path is provided at an arbitrary position in the middle of the power supply path from the plasma generating high-frequency power source 9 to the high-frequency antenna coil 8 that generates the induction discharge, and a part of the induction discharge high-frequency power is passed through a capacitor provided in the branch path. Is applied to the counter electrode in a branched manner to generate a self-bias in the counter electrode. The top plate as the counter electrode functions as a floating electrode.
JP-A-7-263192 (Claims etc.) JP 10-317173 A (Claims etc.)

  In the case of the above prior art, the method of heating the whole vacuum chamber in an open manner and controlling the whole to a high temperature has a problem of large scale and large power consumption. In addition, the heat-prevention plate method is performed by attaching the adhesion-prevention plate to a place where film adhesion is relatively large, but the adhesion film on the adhesion-prevention plate becomes thick with time, and eventually peels off and causes dust. Therefore, it is necessary to periodically remove and wash the protective plate.

  In the case of the magnetic neutral wire discharge etching apparatus (FIG. 1) described in Patent Document 1 (Japanese Patent Laid-Open No. 7-263192), when applied to etching of a resist pattern having a fine structure using a halogen-based etching gas, Due to the time etching, the film adhering to the inner wall surface of the top plate is peeled off, and dust is generated.

  In the case of the magnetic neutral discharge etching apparatus described in Patent Document 2 (Japanese Patent Laid-Open No. 10-317173) proposed to solve the above problem, undesirable film adhesion to the inner wall of the vacuum chamber is minimized, and Dust generation from the inner wall of the plate is also suppressed, and the etching resistance of the mask is improved. However, three high frequency power supplies are required, which is not only expensive, but also because the counter electrode (floating electrode) and the induction coil are close to each other, the high frequency electric field applied to them interferes with each other. Arise. Also, a power supply path from a high-frequency power source connected to the high-frequency antenna coil is branched, and a Faraday shield-like floating electrode installed inside the top plate (floating electrode) or antenna coil via a capacitor provided in this branching path When high-frequency power is applied in a divided manner, the power supply depends on the capacity of the capacitor and the antenna coil power, but it cannot be sufficiently controlled.

  In the magnetic neutral discharge plasma etching apparatus (FIG. 2) described in Japanese Patent Application No. 2001-149825 proposed by the same applicant as the present case in order to solve these problems, the generation of dust is suppressed and the etching of the mask is performed. The resistance is also improved, and it becomes possible to etch deep grooves of quartz as long as 30 to 40 μm. However, when the antenna coil power is increased or decreased, the high-frequency power applied to the top plate (counter electrode) also increases or decreases. In order to remove the film adhering to the top plate by sputtering, it is necessary that a high frequency voltage of a certain value or more is applied. However, if this voltage is too high, the resistance of the mask will improve, but the sputtered effect will be too strong, and the sputtered material will also fly into the etched area, thus suppressing etching and reducing the etch rate. There is a problem of end.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and is an inexpensive two-frequency discharge type etching apparatus having a simple structure, which does not involve the problem that applied high-frequency electric fields interfere with each other. In addition, it is possible to form a high-efficiency plasma and to be able to apply a high-frequency voltage of a predetermined voltage value, thereby improving the resistance of the mask and achieving an excellent etching rate. To provide an apparatus.

The etching apparatus of the present invention is provided with a plasma generating part in the upper part of a vacuum chamber, a substrate electrode part in the lower part, and a plasma generating part connected to one high frequency power source outside the side wall of the plasma generating part made of a dielectric . An Faraday shield or electrostatic field shield-like floating electrode is installed in a vacuum chamber in an etching apparatus that has an antenna coil and a substrate electrode that is connected to another high-frequency power source and is applied with a high-frequency bias power. A branch path is provided in the middle of the feeding path between the antenna coil and one high frequency power source so that a part of the high frequency power is supplied to the floating electrode via a variable capacitor provided in the branch path. configured to be branched applied to monitor the high-frequency voltage applied to the floating electrode is provided with a control mechanism for controlling the high-frequency voltage constant This control mechanism is a high-frequency voltage measurement circuit that measures a voltage applied to a floating electrode from one high-frequency power supply, a detection circuit that converts this high-frequency to direct current, and a DC differential amplification circuit that detects a difference from a set voltage value, In addition, it has a motor drive circuit that moves the variable capacitor so that it becomes the set voltage value, a voltage measurement circuit is connected to the floating electrode, a detection / DC differential amplification circuit is connected to the voltage measurement circuit, and detection / DC differential amplification A motor drive circuit is connected to the circuit and incorporated in a variable capacitor, and the high frequency voltage is controlled to be constant by the variable capacitor. Electric power is applied to the floating electrode so that the surface potential of the floating electrode becomes −500V. It is configured to be configured as described above .

  A magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generating part by the magnetic field coil, and a discharge plasma is generated on the magnetic neutral line. May be.

Another etching apparatus according to the present invention has a plasma generation unit at the top in a vacuum chamber and a substrate electrode unit at the bottom, and plasma generation is connected to a single high frequency power source outside the side wall of the plasma generation unit made of a dielectric. Etching in which an antenna coil is provided, a substrate electrode connected to another high-frequency power source is applied to the substrate electrode portion, and a high-frequency bias power is applied to the substrate electrode portion, and a counter electrode is provided in the plasma generating portion facing the substrate electrode In the apparatus, the counter electrode is a floating electrode that is hermetically fixed to the upper flange of the side wall of the plasma generation unit via an insulator, and is configured to be in a floating state in terms of potential, and is a feeding path between the antenna coil and one high-frequency power source A part of the high-frequency power is applied to the floating electrode via a variable capacitor provided in the branch. A high frequency voltage to be pressurized and monitored, a control mechanism for controlling the high-frequency voltage constant provided, the control mechanism, the high-frequency voltage measuring circuit for measuring the voltage applied to the floating electrode from a high frequency power supply, the high-frequency It has a detector circuit that converts to DC, a DC differential amplifier circuit that detects the difference from the set voltage value, and a motor drive circuit that moves the variable capacitor so that it becomes the set voltage value. The voltage measurement circuit is connected to the floating electrode. The detection / DC differential amplifier circuit is connected to the voltage measurement circuit, the motor drive circuit is connected to the detection / DC differential amplifier circuit, and the high frequency voltage is controlled to be constant by the variable capacitor. When the frequency of one high-frequency power source connected to the counter electrode is 13.56 MHz, the DC voltage applied to this electrode is −500 V Characterized in that it is configured to be lower. In this case as well, a magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generating part by the magnetic field coil to generate discharge plasma on the magnetic neutral line. It is configured to allowed to have good.

  According to the etching apparatus configured as described above, it is not necessary to separately provide a high frequency power source for the counter electrode, the structure of the apparatus can be simplified and the cost is reduced, and the applied high frequency electric fields interfere with each other. Thus, it is possible to form a highly efficient plasma. In addition, since a high frequency having a predetermined voltage value can be applied to the floating electrode to the counter electrode, the resistance of the mask can be improved and a good etching rate can be achieved.

  In addition, the substance generated by the plasma decomposition of gas adheres to the wall surface and eventually peels off and falls as dust to the substrate surface, which has been a problem with ICP plasma sources and ECR plasma sources. By providing a counter electrode in a state and applying high-frequency power to the counter electrode, ions in the plasma constantly sputter the surface of the counter electrode, so that not only film adhesion can be suppressed and dust generation can be suppressed, but also the top plate That is, since the polymerized film adhering to the inner surface of the counter electrode is sputtered, a secondary effect of generating an etchant can be expected.

  As described above, since the high frequency power is applied to the counter electrode and a negative bias is generated in the counter electrode, the counter electrode is always struck by positive ions. As a result, film adhesion to the top plate is suppressed and dust generation from the top plate is suppressed as compared with the conventional configuration in which the top plate is set to the ground potential. Furthermore, by using a top plate made of a metal such as Si or WSi, substances such as SiFx and WFx can be generated, and these substances can be deposited on the mask to reduce the consumption of the mask. It becomes possible to etch deep grooves.

  According to the present invention, the ground electrode provided at a position facing the substrate electrode is configured as a counter electrode that is in a floating state in potential, and is disposed at an arbitrary position on the feeding path connected to the high-frequency antenna coil that generates inductive discharge. Since the branch path is provided, the high frequency power is branched, a part of the high frequency power for induction discharge is branched and applied to the counter electrode, and the counter electrode is self-biased via the capacitor. It is no longer necessary to provide a separate high frequency power supply for the purpose of use, and the structure of the apparatus can be simplified and not only inexpensive, but also the problem that the high frequency electric fields to be applied interfere with each other can be eliminated, and a highly efficient plasma can be formed. it can. In addition, since a high frequency of a predetermined voltage value can be applied to the counter electrode, the resistance of the mask can be improved and a good etching rate can be achieved.

  In addition, although the substance generated by the plasma decomposition of the gas adheres to the wall surface, a counter electrode is provided above the substrate, and by applying high frequency power to the counter electrode, ions in the plasma constantly sputter the surface of the counter electrode. Further, not only the film adhesion can be suppressed and the generation of dust can be suppressed, but also an etchant can be generated by sputtering the polymerized film adhered to the top plate, that is, the inner surface of the counter electrode.

Furthermore, according to the present invention, since high frequency power is applied to the counter electrode and a negative bias is generated in the counter electrode, the counter electrode is always struck by positive ions. As a result, film adhesion to the top plate is suppressed and dust generation from the top plate is suppressed as compared with the conventional configuration in which the top plate is set to the ground potential. Furthermore, by using a top plate made of a metal such as Si or WSi, it is possible to generate substances such as SiF _x and WF _x and deposit these substances on the mask, thereby suppressing the consumption of the mask. The deep groove can be etched.

  The present invention is applied to an inductively coupled discharge plasma etching apparatus. For convenience of explanation, the magnetic neutral line discharge etching apparatus schematically shown in FIGS. 3 and 4 is taken as an example. An embodiment of the present invention will be described. In the figure, the same reference numerals are given to the same elements as those of the conventional example of FIGS.

  As shown in FIG. 3, this etching apparatus branches a feeding path of a high-frequency power source connected to an antenna coil for inductively coupled discharge, and a top plate (counter electrode) that is floating in potential via a variable capacitor. This is a two-frequency discharge type device configured to be able to supply a part of the high-frequency power to. This etching apparatus has a vacuum chamber 1, the upper part of which is a plasma generating part 2 formed by a dielectric cylindrical wall, and the lower part is a substrate electrode part 3. Three magnetic field coils 4, 5 and 6 are provided outside the wall (dielectric side wall) of the plasma generation unit 2, and an annular magnetic neutral wire 7 is formed in the plasma generation unit 2 by the magnetic field coils. It has become. A high frequency antenna coil 8 for plasma generation is disposed between the intermediate magnetic field coil 5 and the outside of the dielectric side wall. This high frequency antenna coil 8 is connected to a high frequency power source 9 and is connected to three magnetic field coils 4, 5, 6. An alternating electric field is applied along the magnetic neutral line 7 formed by the above to generate discharge plasma in the magnetic neutral line.

  A substrate electrode 10 is provided in the lower substrate electrode portion 3 through an insulator member 11 in parallel with the surface formed by the magnetic neutral line 7, and this substrate electrode 10 is connected to a high frequency bias power via a blocking capacitor 12. Is connected to a high-frequency power source 13 for applying voltage, and is a floating electrode in terms of potential, resulting in a negative bias potential.

  The ground electrode provided at a position facing the substrate electrode 10 is configured as a top plate 14 that is a counter electrode that is floated in potential by a dielectric. The top plate 14 is hermetically fixed to the upper flange of the dielectric sidewall via an insulator 17. The top plate 14 may be configured using a carbon material, a silicon material, or a compound or mixture thereof as an inner wall material.

  Further, a branch path is provided at an arbitrary position in the middle of the feeding path between the plasma generating high-frequency power source 9 and the high-frequency antenna coil 8 for generating induction discharge, and the induction discharge high-frequency power is branched through a variable capacitor 18. Then, a part of the high-frequency power is applied to the top plate 14 which is a counter electrode, and a self-bias is generated in the counter electrode.

  The plasma generation unit 2 is provided with a gas introduction port 15 for introducing a etching gas into the vacuum chamber 1, and this gas introduction port 15 is a gas that controls the flow rate of the gas supply path and the etching gas, although not shown. It is connected to an etching gas supply source via a flow rate control device. The substrate electrode portion 3 is provided with an exhaust port 16.

  In the present embodiment, as shown in FIG. 3, high-frequency power is branched and applied to the counter electrode 14 configured as described above via a variable capacitor 18 incorporating the measurement circuit and control circuit shown in FIG. It is configured as follows. That is, a high-frequency voltage measurement circuit for measuring a voltage applied to the counter electrode from the high-frequency power source 9 via the branch path is connected to the counter electrode 14, and a detection circuit for converting high frequency to direct current and a set value are connected to the measurement circuit. A DC differential amplifier circuit for detecting a difference between the motor and a motor driving circuit for moving the variable capacitor 18 to a set voltage value is connected to the detection / differential amplifier circuit. .

  The etching apparatus of the present embodiment configured as described above has a simple structure, is inexpensive, and forms a high-efficiency plasma without the problem that applied high-frequency electric fields interfere with each other. be able to. In addition, a high frequency voltage within a predetermined range can be applied to the top plate, which is a counter electrode, so that the film attached to the top plate can be efficiently sputtered off, and the resistance of the mask is improved and etching is performed. A good etching rate can be achieved without suppressing the above.

  According to the experiments by the present inventors, in the case of the 13.56 MHz high-frequency power source 9, when Vdc applied to the top plate 14 is −500 V or less (absolute value is 500 V or more), no film adheres to the top plate. I know. If the value of Vdc is too large, the top plate will be sputtered excessively, so it is desirable to set this voltage in the vicinity of -500V. In addition, when the top plate material is attached to the substrate by sputter etching the top plate material to increase the etch resistance of the mask, the Vdc of the top plate is −500 V or less (in absolute value). 500V or higher). Even if film adheres to the top plate, it may be set to −500V or more (−500 to −50V) if it is not necessary to become a dust generation source.

  The power supply path of the high frequency power source 9 connected to the antenna coil is branched, the high frequency power is branched, and the variable capacitor 18 is passed through the Faraday shield (or electrostatic field shield) -like floating electrode installed inside the antenna coil 8. The method of branching and applying a part of the high-frequency power can be configured similarly to the method of using the top plate as a floating electrode as described above, and the same etching can be performed. This Faraday shield-like floating electrode or the like can be installed inside the high-frequency antenna coil. However, when the Faraday shield is installed outside the dielectric side wall, which is the side wall of the plasma generation part of the vacuum chamber, inside the high-frequency antenna coil, a dielectric is interposed between the plasma and the Faraday shield. Film adhesion cannot be prevented unless the potential on the side wall surface is set to −500 V or less. Therefore, when it is installed outside the dielectric sidewall, it is necessary to further lower the potential of the Faraday shield (increase the absolute value). In addition, when the Faraday shield is installed inside the vacuum chamber and is in contact with the plasma, when the potential of the Faraday shield surface is set to -500 V, film adhesion hardly occurs. This difference also depends on the thickness of the dielectric.

  The Faraday shield is a known Faraday shield, and is, for example, a metal plate in which a plurality of slits are provided in parallel and an antenna coil is provided in the middle of the slit in a direction perpendicular to the slits. At both ends in the longitudinal direction of the slit, metal edges that make the potential of the strip-shaped metal plate the same are provided. The electrostatic field of the antenna coil is shielded by the metal plate, but the induction magnetic field is not shielded. This induction magnetic field enters the plasma and forms an induction electric field. The width of the slit can be appropriately designed according to the purpose, and about 0.5 to 10 mm is used, but usually a slit of 1 to 2 mm is sufficient. If the width of the slit is too wide, the electrostatic field will penetrate, which is not preferable. The thickness of the slit is ˜2 mm.

  Next, an etching process was performed using an NLD etching apparatus configured as shown in FIGS.

The power of the plasma generating high frequency power source 9 (13.56 MHz) is 1.2 kW, the power of the substrate bias high frequency power source 13 (12.56 MHz) is 0.5 kW, the capacity of the variable capacitor 18 is 200 pF, Ar 90 sccm, C ₄ F ₈ When 10 scc (10%) is introduced and etching is performed under a pressure of 3 mTorr, the etching rate is 600 nm / min and the selectivity is 25 (poly-Si etching) with respect to the thermally oxidized SiO ₂ film using poly-Si as a mask. SiO ₂ etch rate versus rate) was obtained.

  Compared with the etching under the same conditions in the conventional apparatus configuration (FIG. 1), the selectivity improved by 2.5 times at almost the same etching speed, although there were some differences depending on the pattern width.

  As an etching apparatus related to the above-described etching apparatus, a plasma generating part is provided in the upper part of the vacuum chamber, a substrate electrode part is provided in the lower part, and connected to a high frequency power source outside the side wall of the plasma generating part made of a dielectric. A high frequency antenna coil for plasma generation is provided, and a substrate electrode connected to another high frequency power source to which a high frequency bias power is applied is provided in the substrate electrode portion, and a counter electrode is provided in the plasma generation portion so as to face the substrate electrode. In the etching apparatus provided, the counter electrode is a floating electrode that is hermetically fixed to the upper flange of the side wall of the plasma generation unit via an insulator and is configured to be in a floating state in terms of potential, the antenna coil and its high-frequency power source A branch path is provided in the middle of the power supply path between and a high frequency power is supplied to the floating electrode via a variable capacitor provided in the branch path. And a high frequency voltage measuring circuit for measuring a voltage applied to the floating electrode from the high frequency power source, a detection circuit for converting the high frequency to direct current, and a DC for detecting a difference between the set voltage values A differential amplifier circuit, and a motor drive circuit that moves a variable capacitor so as to be the set voltage value; the voltage measurement circuit is connected to the floating electrode; and the detection / DC differential amplifier circuit is connected to the voltage measurement circuit Is connected to the detection / DC differential amplifier circuit, and is incorporated in a variable capacitor, and is configured to control the high-frequency voltage to be constant by the variable capacitor. Some have provided a mechanism for monitoring a high-frequency voltage applied to the floating electrode and controlling the high-frequency voltage to be constant. In this case, a magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generating unit by the magnetic field coil so as to generate discharge plasma in the magnetic neutral line. It may be configured as follows.

  In addition, as an etching apparatus related to the above-described etching apparatus, a plasma generation unit is provided in the upper part of the vacuum chamber, a substrate electrode part is provided in the lower part, and connected to a high-frequency power source outside the side wall of the plasma generation unit made of a dielectric. In an etching apparatus provided with a high frequency antenna coil for plasma generation, and provided with a substrate electrode connected to another high frequency power source and applied with a high frequency bias power to the substrate electrode portion, a Faraday shield or static electricity is provided inside the antenna coil. An electric field shield-like floating electrode is installed, a branch path is provided in the middle of the feeding path between the antenna coil and the high-frequency power source, and a high-frequency power is supplied to the floating electrode via a variable capacitor provided in the branch path. The high frequency voltage measurement is configured to measure the voltage applied to the floating electrode from the high frequency power supply. Path, a detection circuit for converting the high frequency to direct current, a DC differential amplifier circuit for detecting a difference from a set voltage value, and a motor drive circuit for moving a variable capacitor so as to be the set voltage value, the floating electrode The voltage measurement circuit is connected to the voltage measurement circuit, the detection / DC differential amplification circuit is connected to the voltage measurement circuit, and the motor drive circuit is connected to the detection / DC differential amplification circuit and is incorporated in the variable capacitor. A control mechanism configured to control the high-frequency voltage to be constant by the variable capacitor, provided with a mechanism for monitoring the high-frequency voltage applied to the floating electrode and controlling the high-frequency voltage to be constant There is. In this case, a magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generating unit by the magnetic field coil so as to generate discharge plasma in the magnetic neutral line. It may be configured as follows.

The block diagram which shows typically the schematic structure of the conventional etching apparatus. The block diagram which shows typically the general | schematic structure of another conventional etching apparatus. BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows typically the schematic structure of the etching apparatus of one embodiment of this invention. The block diagram which shows the structure which incorporated the measurement circuit and control circuit which were provided in the etching apparatus of FIG. 3 in the variable capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Plasma generation part 3 Substrate electrode part 4, 5, 6 Magnetic coil 7 Magnetic neutral wire 8 High frequency antenna coil 9 High frequency power supply 10 Substrate electrode 11 Insulator member 12 Blocking capacitor 13 High frequency power supply 14 Top plate (counter electrode, Floating electrode)
15 Gas inlet 16 Exhaust port 17 Insulator 18 Variable condenser

Claims (4)

A plasma generation unit is provided in the upper part of the vacuum chamber, a substrate electrode unit is provided in the lower part, and an antenna coil for plasma generation connected to one high frequency power source is provided outside the side wall of the plasma generation unit made of a dielectric. In the etching apparatus in which the electrode portion is provided with a substrate electrode connected to another high-frequency power source and applied with a high-frequency bias power,
Faraday shield or electrostatic field shield-like floating electrode is installed in the vacuum chamber so as to come into contact with the plasma,
A branch path is provided in the middle of the feeding path between the antenna coil and the one high-frequency power source, and a part of the high-frequency power is branched and applied to the floating electrode via a variable capacitor provided in the branch path. To configure
A high-frequency voltage applied to the floating electrode is monitored, and a control mechanism for controlling the high-frequency voltage is provided.
The control mechanism measures a voltage applied to the floating electrode from the one high-frequency power supply, a high-frequency voltage measuring circuit, a detection circuit for converting the high-frequency to direct current, and a DC differential amplifier circuit for detecting a difference from a set voltage value And a motor drive circuit that moves a variable capacitor so as to be the set voltage value, the voltage measurement circuit is connected to the floating electrode, and the detection / DC differential amplification circuit is connected to the voltage measurement circuit, The motor drive circuit is connected to the detection / DC differential amplifier circuit and incorporated in a variable capacitor, and the high frequency voltage is controlled to be constant by the variable capacitor,
An etching apparatus characterized in that power is applied to a floating electrode so that the surface potential of the floating electrode is -500V.   A magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generation unit by the magnetic field coil so that a discharge plasma is generated in the magnetic neutral line. The etching apparatus according to claim 1, wherein A plasma generation unit is provided in the upper part of the vacuum chamber, a substrate electrode unit is provided in the lower part, and an antenna coil for plasma generation connected to one high frequency power source is provided outside the side wall of the plasma generation unit made of a dielectric. In the etching apparatus in which the electrode portion is provided with a substrate electrode connected to another high-frequency power source and to which a high-frequency bias power is applied, and the counter electrode is provided in the plasma generation portion so as to face the substrate electrode.
The counter electrode is a floating electrode that is hermetically fixed to an upper flange of a side wall of the plasma generation unit via an insulator, and is configured as a potential floating state.
A branch path is provided in the middle of the feeding path between the antenna coil and the high-frequency power source, and a part of the high-frequency power is applied to the floating electrode via a variable capacitor provided in the branch path. ,
A high-frequency voltage applied to the floating electrode is monitored, and a control mechanism for controlling the high-frequency voltage is provided.
The control mechanism measures a voltage applied to the floating electrode from the one high-frequency power supply, a high-frequency voltage measuring circuit, a detection circuit for converting the high-frequency to direct current, and a DC differential amplifier circuit for detecting a difference from a set voltage value And a motor drive circuit that moves a variable capacitor so as to be the set voltage value, the voltage measurement circuit is connected to the floating electrode, and the detection / DC differential amplification circuit is connected to the voltage measurement circuit, The motor drive circuit is connected to the detection / DC differential amplifier circuit and incorporated in a variable capacitor, and the high frequency voltage is controlled to be constant by the variable capacitor,
An etching apparatus characterized in that when a frequency of one high-frequency power source connected to the counter electrode is 13.56 MHz, a DC voltage applied to the electrode is -500 V or less. A magnetic field coil is provided outside the antenna coil, and an alternating electric field is applied along the annular magnetic neutral line formed in the plasma generation unit by the magnetic field coil so that a discharge plasma is generated in the magnetic neutral line. The etching apparatus according to claim 3 , wherein the etching apparatus is provided.

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