JPH11140674A - High efficiency working device by high density radical reaction using rotary electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute working with high precision and high efficiency without introducing defects and thermally affected layers into the material to be worked by supporting the rotary shaft of a rotary electrode by gaseous bearings, as the gas to be fed to the bearings, using the one same as the atmospheric gas in a chamber, feeding the atmospheric gas fed to the bearings toward the rotary electrode along the rotary shaft. SOLUTION: Working gas fed from the feed port 21 of gaseous bearings 16 and 17 is jetted from a blow-off port 23 in the radial direction and a blow-off port 26 in the shaft direction to rotatably float the edge part 15A of the rotary shaft in a gaseous manner, and, furthermore, the movement thereof in the shaft direction is regulated. In this way, the rotary electrode 14 can be rotated at about 10000 rpm maximum rotational frequency and about 1 μm rotary precision. Then, the working gas (atmospheric gases) is fed toward the rotary electrode 14 along the shaft direction of the rotary shaft 15 from the space between a bearing hole 20 and the edge part 15A of the rotary shaft and is made a gas flow crossing the working gap between the concentrated part of the electric field on the outer circumferential part of the rotary electrode 14 and the material 8 to be worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing a semiconductor such as silicon single crystal or a conductor such as a metal or an insulator such as glass or ceramics with high precision and efficiency without introducing a defect or a thermally deteriorated layer. Related to high-efficiency processing equipment by high-density radical reaction using rotating electrodes
More specifically, the present invention relates to a high-efficiency processing apparatus by a high-density radical reaction using a rotating electrode particularly suitable for shape processing of an SR light X-ray mirror or a CO ₂ laser mirror which is a high output light mirror.

[0002]

2. Description of the Related Art Heretofore, the present applicant has disclosed Japanese Patent Application Laid-Open No. 1-1258.
As disclosed in Japanese Patent Publication No. 29, neutral radicals of a reaction gas by high-density plasma generated by an electrode to which a high frequency is applied are supplied to a processing surface of a workpiece to form a processing surface with the neutral radicals. Volatile substances generated by radical reactions with atoms or molecules are vaporized and removed, and high precision is achieved without introducing defects or thermally altered layers in semiconductors such as silicon single crystals or conductors or insulators such as glass or ceramics. There has already been proposed a distortion-free precision processing method (plasma CVM method) capable of processing into a uniform shape.

With this processing method, a maximum processing speed of several tens μm / min has been achieved. Although this processing speed is a value far exceeding the common sense of conventional plasma dry etching using a plasma process, it is necessary to numerically control an industrially large area or cut a thick workpiece. Is not enough. Here, the processing speed is largely related to the density of neutral radicals in the vicinity of the processing progress portion of the workpiece, that is, the concentration of the reactive gas for generating the neutral radicals and the input power. Conventionally, various mechanisms have been devised for the supply mechanism of the reactive gas, the exhaust mechanism for the used gas, and the electrode structure, but none of these methods has been able to significantly improve the processing speed. The reason for insufficient supply of reactive gas and exhaust of used gas is
In the plasma CVM, the pressure of the gas atmosphere is a high pressure (near atmospheric pressure) that cannot be considered in a normal plasma process, and the processing gap is usually 10 to 200.
It is considered that this is because the gas has a very small viscous resistance because it is very narrow at μm. Further, the reason why the limit value of the input power is low is that the electric field concentrated portion of the processing electrode is heated and is thermally damaged.

Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 9-3167.
As disclosed in Japanese Patent Publication No. 0, a rotating electrode is employed as a working electrode, and by rotating the rotating electrode at a high speed, a gas flow is formed that entrains the atmosphere gas on the rotating electrode surface and crosses the working gap, High-speed supply of the atmosphere gas and high-speed exhaustion of the used gas can be achieved at the same time, and a large amount of electric power can be supplied based on a sufficient cooling action of the rotating electrode. ~ 1
The present invention provides a high-efficiency processing method and a processing apparatus by a high-density radical reaction using a rotating electrode capable of realizing a large improvement of a processing speed of 00 times.

[0005]

Here, the above-mentioned plasma CVM using the rotating electrode rotating at a high speed rotates the atmosphere gas by rotation of the rotating electrode and supplies it to the processing gap. The gas must be ultra clean. If the atmosphere gas contains impurities such as particles, the impurities may damage the processed surface of the workpiece or hinder the progress of the processing, thereby deteriorating the surface roughness.

When rotating the rotating electrode at a high speed, a bearing and a drive unit for the rotating shaft are required. However, when a normal ball bearing or a roller bearing using a roller bearing is used, the contact portion or the sliding portion has a problem in that the contact member or the sliding portion is used. Particle generation is inevitable due to wear. Further, if a linear guide using a rolling bearing is used as a drive mechanism for relatively moving the rotary electrode and the workpiece to advance the processing, particles are generated as described above, which is problematic. In particular, the generation of particles from dry lubricated rolling bearings is extremely large,
By coating the sliding member with a fluororesin or by forming the sliding member itself with a fluororesin, dust generation to some extent can be suppressed, but is not sufficient. On the other hand, in an oil-lubricated rolling bearing, although generation of particles is small, it is inevitable that the lubricating oil volatilizes and mixes with the ambient gas. Therefore, it is conceivable to house the bearing and the drive unit in a sealed case and seal the rotating shaft with a mechanical seal. However, dust generation from the sliding portion of the mechanical seal also poses a problem. Further, if a rolling bearing is viewed from another viewpoint, it is not only a source of vibration, but also a medium for transmitting vibration from a fixed portion such as a chamber to the rotating electrode, which is not preferable for ultra-precision machining.

In view of the above situation, the present invention is to solve a problem in a plasma CVM of a type in which a rotating electrode is rotated at a high speed, from a bearing of the rotating electrode and other driving parts to a processing surface of a workpiece. Damage the
Using a rotating electrode that does not generate any particles or lubricating oil, etc., which may cause the processing to hinder the progress of the surface roughness and worsen the surface roughness, stabilizes the rotation of the rotating electrode, and simultaneously supplies the atmosphere gas. An object of the present invention is to provide a high-efficiency processing apparatus using a high-density radical reaction.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rotationally symmetric type with respect to a rotational axis in a gas atmosphere consisting of a reaction gas and an inert gas in a chamber near atmospheric pressure. A rotating electrode and a workpiece are disposed, and while maintaining a processing gap between the rotating electrode and a processing portion of the workpiece, the rotating electrode is rotated at a high speed to allow gas to flow on the surface of the rotating electrode. The entrainment forms a gas flow across the processing gap, supplies high-frequency power to the rotating electrode, generates plasma in the processing gap, generates neutral radicals based on the reaction gas, and generates A rotary electrode formed by evaporating and removing volatile substances generated by a radical reaction with atoms or molecules constituting a processing part of a workpiece, and moving the rotary electrode and the workpiece relatively to perform processing. A high-efficiency processing apparatus using a high-density radical reaction, wherein the rotating shaft of the rotary electrode is floated and supported by a gas bearing, and the same gas as the atmospheric gas in the chamber is supplied as a gas to be supplied to the gas bearing. A high-efficiency processing apparatus by a high-density radical reaction using a rotating electrode formed by supplying an atmosphere gas supplied to a gas bearing along a rotating shaft toward the rotating electrode was configured.

Further, the rotating electrode is provided at the center of the rotating shaft, and both ends or one end of the rotating shaft are supported by gas bearings, and an atmosphere gas in a chamber is supplied as gas to the gas bearings. It is preferable to use a constituent inert gas.

[0010] Further, between the insulating shaft portion having high-frequency insulation attached to one end of the rotary shaft and the drive shaft of the drive motor separated by an airtight case and a magnetic fluid seal having corrosion resistance to atmospheric gases. It is also preferable that a magnetic coupling is interposed in the motor shaft to transmit the rotational force of the drive shaft to the insulating shaft portion and the rotating shaft in a non-contact state.

The processing principle of a high-efficiency processing apparatus by a high-density radical reaction using a rotating electrode according to the present invention is based on the principle that a rotating electrode and a workpiece are interposed between a rotating gas and an inert gas in a gas atmosphere comprising a reactive gas and an inert gas. Forming and arranging the processing gap,
By supplying high frequency power to the rotating electrode while rotating the rotating electrode at a high speed to form a gas flow across the processing gap, a plasma is generated in the vicinity of the surface, and the reaction gas is excited in the plasma region. A neutral radical rich in reactivity is generated, and a volatile substance generated by a radical reaction between the neutral radical and an atom or a molecule constituting a workpiece is vaporized and removed from a processing progress portion,
While maintaining a predetermined processing gap, the rotating electrode and the workpiece are relatively displaced to perform the processing.
The reason why plasma is generated and maintained in the processing gap between the rotating electrode and the processing portion of the workpiece is due to electric field concentration.

Here, the effect of rotating the rotating electrode at a high speed is that the processing speed is greatly improved by supplying the reaction gas at a high speed and exhausting the used gas at a high speed, a highly accurate positioning of the rotating electrode surface, and a high accuracy. Significant improvement in gas use efficiency and processing accuracy by gap control, and significant improvement in processing efficiency by applying a large amount of power based on sufficient cooling effect of the rotating electrode. Can be increased 10 to 100 times as compared with the conventional method, and the processing accuracy, the dimensional accuracy and the surface roughness can be improved by an order of magnitude.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention generates a reactive radical (free radical) having an unpaired electron in the vicinity of a processing portion of a workpiece, thereby forming the neutral radical and the workpiece. Based on the principle of using a radical reaction (free radical reaction) with an atom or molecule to vaporize and remove the generated volatile substances, and moving the rotating electrode and the workpiece relatively to progress the processing. Depending on the shape of the rotating electrode, especially the shape of the electric field concentrating part that directly contributes to the processing, cutting work, polishing processing, numerical control processing of any shape, dicing processing, further shape transfer processing, and free curve cutting processing are performed. Is what you can do.

Here, as a method of generating radicals, plasma dry etching is conventionally performed by utilizing plasma which can be easily generated by electric discharge at a vacuum of about 1 Torr or less (10 ⁻³ to 1 Torr). I have. Since the purpose of plasma dry etching is to remove only the surface layer of the workpiece, the processing speed does not matter so much. However, the processing speed is very important in the processing intended for the present invention, and the neutral radical Low-density plasma such as the above-mentioned plasma dry etching with low density cannot be used. For this reason, in the present invention, high-frequency power (150
MHz) to generate high-density plasma and generate high-density neutral radicals.

Since the processing speed greatly depends on the type of neutral radical, ie, the type of reactive gas and the type of inert gas for diluting it, and the material of the workpiece, the optimum reactive gas is selected according to the workpiece. And an inert gas must be selected.
This reaction gas is excited in the plasma generated by the input of high-frequency power to generate neutral radicals.
More specifically, 0.1 g of a reaction gas and an inert gas
In a gas atmosphere of 10 to 10 atm, preferably 1 atm or more,
The rotating electrode and the workpiece are arranged with a predetermined processing gap, and high-frequency power is supplied to the rotating electrode to generate plasma, and neutral radicals based on the reaction gas are generated in the plasma. The generation efficiency of neutral radicals based on the reaction gas in the plasma also depends on the type of inert gas constituting the plasma. For example, when the workpiece is silicon single crystal or quartz glass, SF ₆ is suitable for the reactive gas, and He is suitable for the inert gas. Other reactive gases include fluorine-based CF _{4 and the} like, chlorine-based gases include Cl ₂ , CCl ₄ and PCl ₅ , and other inert gases include Ne and Ar. Each of these gases may be used alone or in combination.

Therefore, assuming that the optimum types of the reactive gas and the inert gas are selected in accordance with the material of the workpiece, in order to increase the processing speed, how the reactive gas should be introduced into the processing area. It is important as a practical matter how to efficiently supply and exhaust a large amount and how to efficiently supply energy to the reaction gas.

The processing amount (depth) is proportional to the processing time when the processing speed is constant, so that the desired processing amount can be obtained by controlling the processing time. The processing time is determined by the stop time or the average stay time of the rotating electrode with respect to the processing progress portion of the workpiece.

Therefore, the gist of the present invention is that a rotating electrode, which is rotationally symmetric with respect to a rotation axis, is placed in a gas atmosphere consisting of a reaction gas and an inert gas in a chamber near the atmospheric pressure. An object is disposed, and while maintaining a processing gap between the rotary electrode and a processing progress portion of the workpiece, the rotary electrode is rotated at a high speed to entrain gas on the surface of the rotary electrode, thereby forming the processing gap. While forming a gas flow that crosses, high frequency power is supplied to the rotating electrode, plasma is generated in the processing gap to generate neutral radicals based on the reaction gas, and the neutral radicals and the processing progress part of the workpiece are formed. Volatile substances generated by the radical reaction with the atoms or molecules to be removed are vaporized and removed, and the rotating electrode and the workpiece are relatively displaced and processing is performed. A high-efficiency processing apparatus based on a Zical reaction, wherein the rotating shaft of the rotating electrode is floated and supported by a gas bearing, and the same gas as the atmospheric gas in the chamber is used as a gas supplied to the gas bearing. Is supplied to the rotating electrode along the rotation axis.

Next, the details of the present invention will be further described based on embodiments shown in the accompanying drawings. 1 and 2 are schematic explanatory views showing the entire processing apparatus of the present invention, in which 1 is a chamber, 2 is a stone surface plate, 3 is a rotating electrode unit, and 4 is XY.
Axis drive mechanism, 5 is a Z axis drive mechanism, 6 is a θ axis drive mechanism, 7
Denotes a semi-coaxial cavity resonator, and 8 denotes a workpiece. The details of each unit will be described below.

The chamber 1 is made of an aluminum alloy with an internal mirror finish, and the outside is covered with a mirror plate made of SUS304.
It is 1950 mm in depth and 1750 mm in height. Aluminum, SUS, and the like are used as the corrosion-resistant metal against the fluorine-based gas used as the reaction gas. A5052, which is a corrosion-resistant aluminum alloy, is used for weight reduction. The chamber 1 of the present apparatus is a simple container separated from the drive system of the apparatus main body. An opening / closing door 1B is provided on the front side of the container main body 1A, and can be hermetically sealed. Has a strength that can withstand a pressure change due to vacuum evacuation. And the inner surface of the chamber 1
In order to improve the emission gas characteristics from the inner surface and to prevent the generation of particles in the evacuation work at the time of replacing the reaction gas, a mirror finish (surface roughness of about 0.2 μm) is performed by buffing. Further, a semi-coaxial cavity resonator 7 described later is attached to the center of the upper surface of the container body 1A.

The stone platen 2 is made of granite (Rustenburg, South Africa) which has no aging, has high hardness, is hard to be damaged, and has high dimensional accuracy with respect to temperature change.
m, in particular, the upper surface 9 is processed with high surface accuracy because it serves as a reference surface (slide surface) of the XY-axis driving mechanism 4 described later. An X-axis guide 10 made of granite (Rustenberg, South Africa) having a square cross section and a length of 2000 mm is fixed to the upper surface 9 of the stone platen 2 in the X-axis direction.
Both sides 11, 1 along the longitudinal direction of this X-axis guide 10
1 is processed with high dimensional accuracy because it serves as a reference surface for a stroke of an XY-axis driving mechanism 4 described later. The flatness of the upper surface 9 of the stone surface plate 2 measured by an autocollimator is 3.7 μm, and the straightness of the X-axis guide 10 is 2.
It was 3 μm.

In the present embodiment, all the drive units of the apparatus main body including the rotary electrode unit 3 are formed on the upper surface 9 of the stone platen 2 for maintenance / inspection of the apparatus main body, setting of the workpiece 8 and control of the drive system. At the time of adjustment, as shown in FIG.
Can be withdrawn from For this purpose, transport rails 12, 12 extending in the depth direction are provided on the bottom surface of the chamber 1, and the stone platen 2 is mounted on the transport rail 1
2 and 12, and can be transferred to a stone platen carrier 13 installed outside the chamber 1. In addition, since all the components of the apparatus main body are constructed on the upper surface 9 of the stone platen 2 supported at three points, it is possible to maintain accuracy without being affected by the deformation or rigidity of the chamber 1. it can.

As shown in FIG. 3, the rotary electrode unit 3 has a rotary electrode 14 which is rotationally symmetric with respect to the rotation axis.
Is provided at the center of the rotating shaft 15, and both ends of the rotating shaft 15 are supported by gas bearings 16 and 17.
17 are insulated against high frequency.
9 is attached to the upper surface 9 of the stone surface plate 2. Here, the bearing span is 500 mm, and the rotating electrode unit 3 has an arch shape straddling an XY axis driving mechanism 4 described later, and the direction of the rotating shaft 15 is arranged so as to be orthogonal to the X axis. I have.

The rotary electrode 14 is made of an aluminum alloy (A5052) as shown in FIGS. 3 and 4 and has a diameter of 300 mm. In order to make it smaller than the curvature of the machined surface, it has a curvature with a radius of 25 mm.
μm is sprayed and the surface is polished to a surface roughness of about 1 μm with Ra. The rotation shaft 15 is made of SUS304.

The gas bearings 16 and 17 are manufactured by combining a plurality of blocks, and the end 15 A of the rotary shaft 15 is formed.
And a complicated flow path 22 is formed inside the block and between the blocks from the supply port 21 for the working gas, and the inner peripheral surface of the bearing hole 20 is separated from the working gas supply port 21 in the axial direction. At two locations, annular air outlets 23 for ejecting gas toward the circumferential surface of the end 15A are formed to form a radial bearing. Also, one of the gas bearings 16 has a rotating shaft 1.
5 is formed with an annular recess 25 for receiving the disk 24 fixed to the end portion 15A, and air outlets 26, 26 for discharging gas toward the disk 24 are formed on both radial sides of the annular recess 25, thereby forming a thrust. Make up the bearing.

As the working gas to be supplied to the gas bearings 16 and 17, an inert gas (He) constituting the atmospheric gas in the chamber 1 is selected. Further, a gap between the end 15A of the rotary shaft 15 and the bearing hole 20 at which the bearing rigidity is maximized was found by numerical calculation in the specific specifications of the present embodiment, and the value was set to 10 μm. If the supply pressure of the working gas He is 5.033 kg / cm ² ,
A total weight of about 24 kg of the rotating electrode 14 and the rotating shaft 15 can be supported in a floating state at a predetermined eccentricity. here,
Double gas bearing 1 when 5 kg / cm ² He is supplied
Bearing stiffness (static stiffness) according to 6, 17 is 1.7 kg / μ
m. The working gas supplied to the gas bearings 16 and 17 is not limited to the inert gas, but may be the same as the reaction gas forming the atmosphere gas or the atmosphere gas in the chamber 1. .

As shown in FIG. 3, a driving part for rotating the rotary electrode 14 includes an insulating shaft part 27 having high-frequency insulation attached to one end of the rotary shaft 15, an airtight case 28 and an atmosphere gas. Drive shaft 30 of drive motor 29 isolated by a magnetic fluid seal having corrosion resistance to
A magnet coupling 31 is interposed between the drive shaft and the drive shaft 30, and the rotational force of the drive shaft 30 is transmitted to the insulating shaft 27 and the rotary shaft 15 in a non-contact state. Here, the drive motor 29 is covered with an airtight case 28, and more preferably, the inside of the airtight case 28 is evacuated so that even if particles are generated in the sliding portion, they do not enter the chamber 1. Each of the motors described later is similarly covered with an airtight case, and preferably the inside is exhausted.

The working gas supplied from the supply ports 21 of the gas bearings 16 and 17 is ejected from radial outlets 23 and 23 and axial outlets 26 and 26, and ends 15A and 15A of the rotary shaft 15 are provided. Is rotatably levitated and restricts axial movement. This gas bearing 16,
17 makes it possible to rotate the rotating electrode 14 with a maximum rotation speed of 10,000 rpm and a rotation accuracy of 1 μm. The aforementioned working gas (inert gas, reaction gas or atmospheric gas) is supplied to the rotating electrode 14 from the gap between the bearing hole 20 and the end 15A of the rotating shaft 15 along the axial direction of the rotating shaft 15. Then, the gas is caught by the high-speed rotation of the rotary electrode 14 and becomes a gas flow that crosses a processing gap between the electric field concentration portion on the outer peripheral portion of the rotary electrode 14 and the workpiece 8.

As shown in detail in FIGS. 6 to 8, the XY-axis driving mechanism 4 is mounted on the upper surface 9 of the stone surface plate 2 along the X-axis guide 10 provided on the upper surface 9 of the stone surface plate 2. An X table 32 composed of a rectangular frame placed, a Y table 33 placed in the frame of the X table 32 and placed on the stone platen 2, an X-axis motor 34 as a driving mechanism and a SUS belt 35, a Y-axis motor 36 and a belt 37 made of SUS. The X table 32 floats on the upper surface 9 of the stone platen 2 by a plurality of gas bearing type static pressure pads 38,. The Y table 33 is similarly floated on the upper surface 9 of the stone platen 2 by a plurality of static pressure pads 38,... And is movable in the Y axis direction within the frame of the X table 32. ing. Here, the X
The table 32 and the Y table 33 are moved by a traction system using SUS belts 35 and 37 driven by an X-axis motor 34 and a Y-axis motor 36, respectively. This method has little disturbance to the movement of the table, is advantageous for long distance movement, and can achieve a long stroke with high accuracy.

More specifically, the XY-axis driving mechanism 4
Both the X table 32 and the Y table 33 have a structure in which the upper surface 9 of the stone surface plate 2 serving as the same reference surface is slid. The X table 32 floats, and the X-axis guide 10 has both side surfaces 11 and 11 as the X-axis guide surfaces, and the Y table 33 is a quartz glass 39 attached to the inner surface of the frame-shaped X table 32. , 39 as a Y-axis guide surface. In the constraint type of each table guide, the external force is determined by the weight of the table and the load (θ
A weight balance constraint type that is given by the weight of the shaft drive mechanism 6, the work table, and the workpiece 8) is employed. This type has an advantage that a large area of the table can be taken, and since the shape is simple, the accuracy of parts can be easily obtained.

As shown in detail in FIG. 8, the static pressure pad 38 is constituted by combining a plurality of blocks, and one side of the long side and one side of the short side are supplied with working gas, respectively. The openings 40, 40 are formed, and the outlets 41,... Having a gap of 10 μm are formed in four places on a smooth surface, and the supply port 40 and the outlet 41 are formed by a complicated flow path 42 formed inside. The air pocket 43 is formed around each of the air outlets 41. The surface having the outlet 41 has a size of 120 mm × 150 mm.
Depending on the position and the direction in which the static pressure pad 38 is to be mounted, one of the two supply ports 40, 40 which is easy to pipe is used, and the other is closed. As the working gas supplied to the static pressure pad 38, a gas of the same type as the atmosphere gas in the chamber 1, that is, an inert gas, a reaction gas, or an atmosphere gas itself is used.

The static pressure pad 38 is provided at the lower corner of the X table 32 for floating the X table 32.
A total of four pairs at a position sandwiching both sides of one X-axis guide 10 for the X-axis guide,
Six pieces were used on the lower surface of the table 33, and two pieces were used on both sides of the Y table 33 facing the quartz glass 39 for the Y-axis guide, for a total of four pieces. In a state where a total weight of 280 kg including the θ-axis drive mechanism 6 is loaded on the Y table 33,
When He of 5 kg / cm ² (absolute pressure) was supplied to each static pressure pad 38 as a working gas, a flying height of about 20 μm was obtained.

The stroke of the XY-axis driving mechanism 4 is X
± 275 mm for the axis, ± 100 m for the Y axis
m, over the entire length of the stroke as shown in FIG.
Despite the large stroke, straightness of 1 μm or less was obtained. Here, in FIG. 9, the row of C is the data at the center position of the stroke in the Y table 33, and the row of R and L is −10 from the center of the Y table 33, respectively.
0mm, + 100mm data at the position deviated,
The columns of 0 °, -30 °, and + 30 ° of the θ-axis rotation angle are as follows:
The rotation angles of the θ-axis drive mechanism 6 described later are 0 ° and −3, respectively.
This is data when the angle is changed to 0 ° and + 30 °.

The Z-axis drive mechanism 5 is a strictly Z
Although it is not an axial drive mechanism, it can adjust the processing gap between the electric field concentrated portion of the rotating electrode 14 and the processing surface of the workpiece 8 to such an extent that there is no practical problem. Specifically, FIG. Are incorporated into the support legs 18 and 19 as described above.
That is, the fixed portion 18A of the one support leg 18 on the drive motor 29 side and the orthogonal corner portion of the movable portion 18B are connected by the cross spring 44, and the fixed portion 19A of the other support leg 19 is connected.
, A movable portion 19B of the support leg 19 is connected to a Z drive shaft 47 which is suspended from a ball screw mechanism 46 connected to a lower portion of the Z-axis motor 45, and silicon nitride is connected to the movable portion 18B. The gas bearing 16 is mounted and fixed via an insulator 48 made of
This is a structure in which the gas bearing 17 is mounted and fixed on B via an insulator 49 made of silicon nitride. Therefore, when the Z-axis motor 45 is driven, the Z drive shaft 47 is moved up and down by the ball screw mechanism 46, and the entire electrode is moved up and down with the cross spring 44 as a fulcrum. Here, the ball screw mechanism 46 is hermetically sealed, preferably exhausting the inside, and the Z drive shaft 47 is covered with a bellows. Reference numeral 50 in the figure denotes an electromagnetic shield cover provided so as to surround the rotating electrode 14, the rotating shaft 15, and the gas bearings 16 and 17 above the insulators 48 and 49.

As shown in FIG. 1, the θ-axis drive mechanism 6 is constructed on the upper surface of a Y table 33, holds the workpiece 8, and holds the workpiece 8 against the electric field concentrated portion of the rotary electrode 14.
Is rotated around the θ axis to process a cylindrical mirror or the like 8 to be processed. Specifically, the support table 5 is provided at both ends in the X-axis direction of the Y table 33.
1 and 51 are fixed upright, mounted on the upper part of one support base 51 by penetrating the drive shaft part of the θ-axis motor 52, and provided on the upper part of the other support base 51 by penetrating the driven shaft part. A work holding portion 53 composed of a hanging plate and a connecting plate provided between the lower ends of both hanging plates is attached to the portion, and the workpiece 8 is fixed to the work holding portion 53 via a spacer 54 having an appropriate thickness. It is supposed to. Reference numeral 55 in the figure denotes a counterweight provided to eliminate the moment of the work holding unit 53 with respect to a change in the rotational position of the θ-axis motor 52.

The semi-coaxial cavity resonator 7 is used for impedance matching between the power supply side and the load side in order to efficiently supply the high frequency power supplied from the high frequency power supply to the plasma near the electric field concentrated portion of the rotating electrode 14. Things.
In a high-frequency band such as 150 MHz used in the present embodiment, the stray capacitance and small inductance of each part caused by electrodes and other internal structures of the chamber cannot be ignored. That is, the higher the frequency, the more frequently the direction of movement of charges changes, so that a large high-frequency current flows even with a small capacitance, and it becomes difficult for a high frequency to flow even with a small inductance. Therefore, in order to efficiently transmit the high-frequency power to the plasma, the impedance of every cross section must be matched in the circuit for introducing the power to the plasma. In this apparatus, the impedance inside the chamber including the plasma and the impedance of the power supply (50Ω) are matched using the semi-coaxial cavity resonator 7.

Also, the stray capacitance (100 to several hundred pF) inside the chamber changes due to the displacement of the XY-axis driving mechanism 4, the Z-axis driving mechanism 5, and the θ-axis driving mechanism 6 during the processing. However, the semi-coaxial cavity resonator 7 has a large capacity (10
00 pF). The semi-coaxial cavity resonator 7 is configured to controlly inject silicon oil into the capacitance portion so that the resonance frequency can be adjusted.

As shown in FIG. 3, the semi-coaxial cavity resonator 7 includes a high-frequency power introducing section 56 and a capacitive coupling section 57.
The high-frequency power is supplied to the rotating electrode 14 via the rotary shaft 15, or the high-frequency power is supplied to the rotary shaft 15 from both the gas bearings 16 and 17 via the conductive plate 58 directly connected to the capacitive coupling portion 57.

In the present working apparatus in the present embodiment, the bearing portion of the rotary electrode unit 3, the XY-axis driving mechanism 4, and other mechanism parts damage the working surface of the workpiece 8 or control the progress of the working. Since it does not generate any particles or lubricating oil that may hinder the surface roughness, and each motor of the drive unit is completely covered with an airtight case, and more preferably, the inside is exhausted,
Particles and lubricating oil from the driving unit do not enter the chamber 1. In addition, since the gas bearing system is adopted for the mechanism, the frictional resistance is extremely small, so that accurate positioning accuracy is possible. In the XY axis drive mechanism 4, the X table 32 and the Y table 33 are directly Since the mechanism slides on the upper surface 9 of the surface plate 2, there is no deterioration in accuracy due to the stacking of the shafts as in the related art, and a high-precision moving stage can be realized, so that high-precision processing can be performed.

[0040]

As described above, the high-efficiency processing apparatus by the high-density radical reaction using the rotating electrode according to the present invention can damage the processing surface of the workpiece from the bearing and other driving parts of the rotating electrode, Since it does not generate any particles or lubricating oil that causes the surface roughness to worsen by hindering the progress of processing, stabilizes the rotation of the rotating electrode, and can simultaneously supply the atmosphere gas. The workpiece can be processed with high accuracy and high efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view for general description in which a processing apparatus of the present invention is partially omitted.

FIG. 2 is a perspective view showing a state where the processing apparatus is drawn out of a chamber.

FIG. 3 is a sectional view showing a rotary electrode unit and a Z-axis drive mechanism.

FIG. 4 is a sectional view showing a main part of the rotating electrode unit.

FIG. 5 is a perspective view showing the gas bearing in a quarter section.

FIG. 6 is a perspective view showing an XY-axis driving mechanism.

FIG. 7 is a plan view of the XY-axis driving mechanism with a part thereof omitted.

FIG. 8 is a perspective view showing a static pressure pad in a partial cross section.

FIG. 9 is a graph showing a measurement result of straightness of the XY-axis driving mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 2 Stone surface plate 3 Rotating electrode unit 4 XY-axis drive mechanism 5 Z-axis drive mechanism 6 θ-axis drive mechanism 7 Semi-coaxial cavity resonator 8 Workpiece 9 Top surface 10 X-axis guide 11 Side surface 12 Transport rail 13 Stone Plate carrier 14 Rotating electrode 15 Rotating shaft 16 Gas bearing 17 Gas bearing 18 Support leg 19 Support leg 20 Bearing hole 21 Supply port 22 Flow path 23 Outlet 24 Disk 25 Annular recess 26 Outlet 27 Insulating shaft 28 Airtight case 29 Driving motor 30 Drive shaft 31 Magnet coupling 32 X table 33 Y table 34 X axis motor 35 Belt 36 Y axis motor 37 Belt 38 Static pressure pad 39 Quartz glass 40 Supply port 41 Air outlet 42 Flow path 43 Air pocket 44 Cross Spring 45 Z-axis motor 46 Ball screw mechanism 47 Z drive shaft 48 Insulator 9 insulator 50 electromagnetic shield cover 51 support stand 52 theta spacer-axis motor 53 work holder 54 55 counterweight 56 high-frequency power supply unit 57 capacitive coupling portion 58 conducting plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 10/00 504 H01L 21/302 B

Claims (4)

[Claims] 1. A rotating electrode and a workpiece, which are rotationally symmetric with respect to a rotation axis, are disposed in a gas atmosphere near the atmospheric pressure comprising a reaction gas and an inert gas in a chamber. While maintaining a processing gap between the workpiece and the processing progress portion of the workpiece, the rotating electrode is rotated at a high speed to entrain gas on the rotating electrode surface, thereby forming a gas flow crossing the processing gap, and rotating the rotating electrode. A high-frequency power is supplied to the electrode, a plasma is generated in the processing gap to generate neutral radicals based on the reaction gas, and a radical reaction between the neutral radicals and atoms or molecules constituting the processing progress portion of the workpiece is performed. This is a high-efficiency processing apparatus by a high-density radical reaction using a rotating electrode formed by vaporizing and removing generated volatile substances and relatively rotating a rotating electrode and a workpiece to perform processing. Thus, the rotating shaft of the rotating electrode is floated and supported by a gas bearing, and the same gas as the atmosphere gas in the chamber is used as the gas supplied to the gas bearing. A high-efficiency processing apparatus by a high-density radical reaction using a rotating electrode, which is supplied to the rotating electrode along the axis. 2. A high-density radical reaction using a rotary electrode according to claim 1, wherein said rotary electrode is provided at a central portion of said rotary shaft, and both ends or one end of said rotary shaft are supported by gas bearings. High efficiency processing equipment. 3. The high-efficiency processing apparatus by a high-density radical reaction using a rotary electrode according to claim 1, wherein an inert gas constituting an atmospheric gas in a chamber is used as a gas supplied to the gas bearing. 4. An insulating shaft portion having high-frequency insulation attached to one end of the rotary shaft, and a drive shaft of a drive motor separated by a hermetic case and a magnetic fluid seal having corrosion resistance to atmospheric gases. 3. A high efficiency by high-density radical reaction using a rotary electrode according to claim 1 or 2, wherein a magnetic coupling is interposed between the rotary shaft and the rotary shaft to transmit the rotational force of the drive shaft to the insulating shaft portion and the rotary shaft in a non-contact state. Processing equipment.