JPH06216079A - Processing method and device by radical reaction - Google Patents

Abstract

PURPOSE:To enable a work to be automatically processed by a method wherein an electrode is formed into the shape opposite to that of a processed face of the work, and the electrode and the work are made to approach each other as close as a movement previously set basing on the shapes of the electrode and the processed surface of the work which is not processed yet. CONSTITUTION:A processing electrode 2 is worked into a shape correspondent to the targeted shape of the processed face of a work 5. The processing electrode 2 is of a board (blade), a pin, or a wire electrode. The dimension of the electrode 2 in the direction of Z to an XY plane is optionally set, whereby the electrode 2 is formed into the shape (reversed shape) corresponding to the targeted shape of the work 5. A power supply 3 is provided to supply a voltage to the processing electrode 2. The applied voltage is set corresponding to the work 5. When the work 5 is formed of conductor or semiconductor, a DC voltage is applied to the processing electrode 2, and the work 5 is grounded. On the other hand, when a work is formed of semiconductor or insulator, a reaction chamber 1 is grounded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method utilizing a radical (free radical) reaction and an apparatus used therefor.

[0002]

2. Description of the Related Art When processing a work piece, if a defect such as a crack or a thermally deteriorated layer is formed inside the work piece by a working operation, brittle fracture may occur on the worked surface. This causes a decrease in reliability. Therefore, it is necessary to further subject the processed object to lapping treatment to remove the defects and the thermally deteriorated layer, but the lapping process itself has a problem of forming defects and thermally deteriorated layers. In order to solve this problem, a strain-free precision processing method using a radical reaction has been proposed as a processing method without forming a defect or a thermally deteriorated layer inside the workpiece (Japanese Patent Laid-Open No. 1-125829). Gazette).

In this processing method, a work piece is placed in a gas atmosphere containing a reaction gas, the reaction gas molecules are excited near the work surface of the work piece to generate radicals, and the radicals and the work piece are processed. By radically reacting with the constituent atoms (or molecules) of the object, a compound that can be vaporized at low temperature is generated on the surface of the object to be processed. Then, by vaporizing this compound and removing it from the processing surface, cavities at the atomic or molecular level are sequentially formed on this surface, and finally cutting, perforating, cutting, polishing, etc. for the workpiece. It is for processing.

In the processing method using such a radical reaction, since the above-mentioned defects and the thermally deteriorated layer are not formed, the above-mentioned lapping treatment is unnecessary. Further, since the processing progresses at the atomic (or molecular) level, the shape roughness of the processed surface can be reduced. This processing method is not easily restricted by the material of the workpiece, and has been applied to semiconductors such as silicon single crystals or conductors or insulators such as glass and ceramics.

[0005]

By the way, when a plurality of workpieces are machined by the machining method using the radical reaction, the machining efficiency is improved by automating the machining.
As a means for that, a method of combining a processing method using a radical reaction with numerical control and automating can be considered.
In this case, it is possible to automatically control the machining by representing the shape of the work piece by the coordinate data of each of the shape before machining and the target shape, and controlling the machining time according to the coordinate difference obtained from this data. Moreover, the shape error with respect to the work piece is 0.01 μm
It can be a degree. However, the numerical control device for performing the numerical control requires complicated control of the coordinate axes in the XYZ directions, which complicates the configuration. Further, if the processed shape becomes complicated, finer control must be performed, and the processing takes a relatively long time. Further, since the control mechanism such as a computer is required, the device becomes expensive.

An object of the present invention is to solve such a problem.

[0007]

To achieve the above object, in the present invention, a voltage is applied to an electrode arranged in an atmosphere gas containing a reaction gas to generate a radical based on the reaction gas, In a processing method using a radical reaction, in which a product generated by a radical reaction with a constituent atom or a constituent molecule of a workpiece is vaporized and removed to perform processing, a shape of the electrode is changed to "the shape of the workpiece. Formed based on the inverted shape of "the target shape of the machined surface", and the electrode and the work piece are "amount of movement set based on the shape of the electrode and the shape of the machined surface before machining". By displacing the relative position of the electrode and the workpiece from one direction so as to approach each other, a shape corresponding to the shape of the electrode is formed on the processed surface. Therefore, for that purpose, a reaction container for introducing an atmospheric gas containing a reaction gas, an electrode installed in the reaction container and having a shape based on an inverted shape of "the target shape of the processed surface of the workpiece" , A power source for applying a voltage to the electrode, and the electrode and the work piece so that they are close to each other by "a movement amount set based on the shape of the electrode and the shape of the processed surface before processing". A processing device using a radical reaction is constituted by a moving means for displacing the relative position of the electrode and the workpiece from one direction.

[0008]

According to the present invention, the number of coordinate axes to be controlled is reduced by associating the "shape of the processed surface of the workpiece to be processed (hereinafter referred to as the target shape)" with the shape of the electrode. . Generally, in the processing for obtaining the target shape represented by the three XYZ coordinate axes, it is necessary to control these three axes. Therefore, in the present invention, the shape of the electrode for generating the radical reaction is formed in a shape that is the inverse of the target shape of the processing surface (hereinafter referred to as the inverted shape), and the object to be processed by the radical reaction is formed along this electrode shape. It is designed to generate a removal effect of the substance. The removing action by the radical reaction occurs when a distance between the electrode and the workpiece is close to a certain distance (this is called a machining gap). Further, the distance (referred to as an ideal gap) between the electrode and the workpiece when the removing action is most efficiently performed is a distance shorter than the processing gap. Therefore, when processing is performed with the electrode and the workpiece fixed at a position where the distance between them is within the processing gap (for example, the position where the ideal gap is obtained),
As the machining progresses and the workpiece is removed, the distance between the electrode and the workpiece gradually becomes wider. Then, when this interval is widened to be equal to the machining gap, the removing action on the workpiece is stopped and the machining cannot proceed any further. Therefore, in the present invention, when the workpiece having a predetermined shape is brought closer to the electrode having the inverted shape during machining, the machined surface of the workpiece can be automatically formed into the target shape. That is, by inverting the shape of the electrode, control of two coordinate axes (for example, XY axes) of the three coordinate axes to be controlled can be omitted, and the distance between the electrode and the workpiece is set 1 Only one axis needs to be controlled. The speed at which the electrode and the workpiece are brought close to each other is set to be slower than the processing speed by the radical reaction.
Due to the proximity of the electrode and the workpiece, the removal action by the radical reaction is sequentially started from the position where the intervals between the corresponding positions due to the shapes of the two become equal to the processing gap, and the processing is performed. After approaching by the predetermined amount, the positions of the electrode and the workpiece are fixed. At this point, if the gap between the two is wider than the machining gap, the removing action (machining) is automatically stopped, and the machined surface of the workpiece is formed into the target shape. On the other hand, if the processing is continued within the processing gap, the processing surface further recedes with respect to the electrode due to the removing action as the processing further progresses, so that the distance between the electrode and the processing surface becomes gradually wider. When the distance becomes wider than the processing gap, the processing does not proceed any further, and the processed surface of the workpiece is formed into the target shape. In actual machining, even if the target shape of the machined surface and the shape of the electrode are the same, the machined surface may not be formed according to the target shape due to radical reaction conditions such as non-uniform plasma density during machining. is there. Therefore, when setting the shape of the electrode, a certain processing condition (which is preferably equal to the actual processing condition) is set in advance, and the correlation between the electrode shape and the target shape under this condition is obtained. Then, the shape of the electrode with respect to the processed surface may be set based on this correlation. Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram of a processing apparatus showing an embodiment of the present invention. The processing apparatus of the present embodiment has a processing electrode 2, a moving means 4 on which a workpiece 5 is placed, a reaction container 1 accommodating the processing electrode 2 and the moving means 4, and a power source 3. There is. The reaction container 1 is configured so that a gas atmosphere containing a reaction gas and an inert gas used when generating a radical reaction can be sealed or flowed at a high pressure (about 1 atm or more). In the present embodiment, a reaction gas supply mechanism (not shown) is provided so that a 10
The reaction gas was supplied at a flow rate of liter / min. The reaction gas is set according to the material of the workpiece 5 and the desired processing speed. In this embodiment, the material of the workpiece 5 is synthetic quartz (quartz glass) and the reaction gas is SF6 (6).
Sulfur fluoride) was used. As reaction gas, in addition to SF6, fluorine-based gas such as F2 (fluorine), Cl2 (chlorine), CC
A chlorine-based gas such as l4 (carbon tetrachloride) can be used, but SF6 is suitable for the synthetic quartz. Although He (helium) is used as the inert gas, other inert gas such as Ar may be used.

The processing electrode 2 is set in a shape corresponding to the target shape of the processing surface of the workpiece 5, and FIG. 2 shows an example of a schematic plane of the shape. As shown in the figure, the processing electrode 2 is a plate (blade), pin or wire electrode 2a.
It is configured to have a shape (inverted shape) corresponding to the target shape of the workpiece 5 by appropriately setting the dimension of these electrodes 2a in the Z direction with respect to the XY plane. This processing electrode is configured so that it can be replaced,
It is also possible to appropriately select and replace a processing electrode having a shape corresponding to the target shape of the workpiece 5.

The power source 3 is for applying a voltage to the processing electrode 2. The applied voltage is set according to the workpiece 5. If the workpiece 5 is a conductor or semiconductor,
A DC voltage is applied to the processing electrode 2 to ground the workpiece 5. On the other hand, when the workpiece 5 is a semiconductor or an insulator,
A high frequency (RF) voltage is applied to the processing electrode 2 to ground the reaction vessel 1. The value of the applied voltage is set so that radicals based on the reaction gas are generated from the atmosphere gas at an appropriate scale. If the voltage value is excessively increased, charged particles of high energy may be generated and damage the work piece 5, which is not preferable. In this embodiment, a high frequency power source is used as the power source 3, and 100 to 1000 W is provided near the processing surface of the workpiece 5.
Processing electrode 2 so that a certain amount of power (plasma) is generated
Voltage is applied to.

The moving means 4 has a stage 4a on which the workpiece 5 is placed, and is provided with a feed mechanism for moving the stage 4a in the Z direction and a rotating mechanism for rotating it by θ (both not shown). . Further, the moving means 4 sets a moving amount in the Z direction in advance according to the shape of the processing surface of the workpiece 5 before processing and the shape of the processing electrode 2, and this setting is automatically set at the time of processing. The amount of movement is controlled so as to be given to the workpiece 5. Here, an example of a method of setting the movement amount will be described.

First, as shown in FIG. 3, the shape of the processed surface of the workpiece 5 before processing and the target shape are measured, and the obtained results are represented by g (x) and f (x), respectively. Note that these f
(X) and g (x) are reference planes (XY directions in the figure)
The height (Z direction) value from is shown. And FIG. 3 (a)
As shown in Fig. 7, the difference between the two shapes is obtained from the shape f (x) before processing and the target shape g (x) of the processing surface in a state where the reference surfaces are matched, and the maximum sag amount Smax is set. To do. This Zmax corresponds to the distance from the position where the machining electrode 2 and the workpiece 5 are in contact with each other until the target shape is obtained.
When generating a radical reaction during processing, the processing electrode 2
It is necessary to keep the distance between the work piece 5 and the work piece 5 within the work gap and prevent the work electrode 2 and the work piece 5 from coming into contact with each other. Therefore, the workpiece 5 should be moved by the moving means 4 by the amount Zmax from the position where the gap between the machining electrode 2 and the workpiece 5 coincides with the machining gap and the machining by the radical reaction is started. If
The target shape can be obtained by avoiding the contact.

On the other hand, in the processing apparatus, it is desirable to provide a certain amount of extra space between the processing electrode 2 and the stage 4 so that the work of attaching the workpiece 5 to the stage 4 can be easily carried out. Therefore, the amount of movement in the Z direction is
Zmax, the distance between the machining electrode 2 and the workpiece 5, and the sum of the margin space (Zmax + α) may be used. In this case, the gap between the machining electrode 2 and the workpiece 5 may be the machining gap or an ideal gap that allows the machining to proceed efficiently. The coordinate control in the Z direction when the moving means 4 is automatically fed is performed based on the fixed position of the machining electrode 2 fixed in the apparatus and the movement amount.

The processing process according to this embodiment will be described below. First, the workpiece 5 is placed on the stage 4a of the moving means 4, and the inside of the reaction container 1 is evacuated to a vacuum. Next, SF6 as a reaction gas and He as an inert gas are introduced into the container 1 so that the internal pressure in the container 1 becomes approximately 1 atm, and a voltage is applied to the processing electrode 2 by the power supply 3. As a result, plasma of the inert gas He is generated between the processing electrode 2 and the workpiece 5. Then, the reaction (collision) between the plasma and the reaction gas SF6 produces radicals of the reaction gas. In the processing apparatus of this embodiment, plasma and radicals are generated in the same region. However, plasma is first generated and this plasma is applied to the workpiece 5.
It may be configured so as to generate a radical by causing the radical to be generated by causing the radical to be generated in the vicinity of, and colliding with the reaction gas. During processing, the reaction gas supply mechanism causes 10 liters near the processing surface of the workpiece 5.
The reaction gas SF6 is supplied at a flow rate of / min. Further, the inert gas He is also supplied in the same manner so that plasma is constantly generated so that radicals are generated.

In such a state where radicals are generated,
While moving the stage 4a in the θ direction by the moving means 4, the stage 4a is moved toward the machining electrode 2 by (Zmax + α) (see FIG. 3B). When the stage 4a approaches the machining electrode 2 and the distance between the two becomes equal to the machining gap, the constituent atoms (or molecules) of the workpiece 5 react with radicals, whereby a compound (silicon fluoride) is generated. It Since this compound is vaporized under the influence of the temperature of the plasma, a void is gradually formed on the processed surface of the workpiece 5. Under the processing conditions (type of reaction gas, gas pressure, applied voltage, etc.) of this embodiment, the processing gap is about 600 μm, and the ideal gap is about 200 μm. The moving speed of the stage 4a is set to be slower than the processing speed so that the workpiece 5 and the processing electrode 2 do not come into contact with each other.

The moving means 4 moves the work piece 5 in the Z direction by a predetermined amount at the set moving speed, then stops the movement, and gives only the rotary motion to the work piece 5 (FIG. 3 (c)). reference). At this time, if the distance between the machining electrode 2 and the workpiece 5 is within the machining gap, the machining of the machining surface of the workpiece 5 continues, but as the machining progresses further, this distance becomes smaller than the machining gap. If the width becomes wider, the processing will stop automatically. As a result, the processed surface of the workpiece 5 is formed into the target shape (see FIG. 3D).

In this embodiment, the maximum sag amount Zma is
The smaller x is, the higher the machining accuracy is, and finally 0.1 μm.
It can be processed with the above shape accuracy. Normally, in machining by numerical control, it is necessary to increase the rigidity of the apparatus in order to secure machining accuracy when the workpiece becomes large, but this is not necessary in this embodiment because machining is performed only by driving the Z axis.

Since the processing speed and the moving speed of the workpiece 5 are determined according to the processing conditions, a predetermined time has elapsed after the start of the operation of the moving means 4 (when the moving means 4 stops moving and the workpiece 5 is processed). It is also possible to automatically stop the supply of the reaction gas and the inert gas and the application of the voltage at the time when the progress of (1) is stopped). Further, since the processing speed also depends on the shape of the processing electrode 2 (that is, the shape of the electrode 2a), the shape of the electrode 2a is appropriately set to increase the processing speed, thereby improving the processing efficiency. Is desirable. An example of a typical electrode shape for that purpose is shown in FIG.
Shown in. FIG. 2 shows the shape of the electrode 2a constituting the processing electrode 2 in the plane direction (XY direction), and the shape in the height direction (Z direction in FIG. 1) is the target shape of the workpiece 5 as described above. Set according to.

[0020]

According to the present invention, since the shape of the electrode used for processing using the radical reaction is processed in accordance with the target shape of the work piece, complicated control and configuration such as a numerical controller is required. Without this, automatic processing is possible. In addition, it can be processed with higher accuracy (shape accuracy of 0.1 μm or more) than before. Further, since the processing process is simplified and the processing time is shortened, the processing cost can be reduced. Furthermore, since it is not necessary to increase the rigidity of the processing equipment in order to increase the processing accuracy, it is possible to handle large workpieces (such as glass with a diameter of up to 500 mm).

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a processing apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic plan view showing an example of the shape of an electrode constituting a processing electrode, FIG. 2 (a) shows blades arranged radially, and FIG. 2 (b) shows blades arranged in parallel. Fig. 2 (c) shows blades and wires arranged in a grid pattern, Fig. 2 (d) shows pins arranged in a grid pattern, and Fig. 2 (e) shows blades and wires arranged in a windmill pattern. FIG. 2 (f) shows a blade and a wire arranged in a snail shape.

FIG. 3 is a schematic view for explaining a processing process of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Processing electrode 3 Power supply 4 Moving means 4a Stage 5 Workpiece

Claims (2)

[Claims] 1. A voltage is applied to an electrode arranged in an atmosphere gas containing a reaction gas to generate a radical based on the reaction gas, and the radical reacts with a constituent atom or a constituent molecule of a workpiece. In a processing method using a radical reaction that performs processing by vaporizing and removing the generated product, the shape of the electrode is based on an inverted shape of "the target shape of the processed surface of the workpiece". The electrode and the work piece are formed relative to each other so that the electrode and the work piece are close to each other by “a movement amount set based on the shape of the electrode and the shape of the work surface before processing”. A processing method using a radical reaction characterized by forming a shape corresponding to the shape of the electrode on the processing surface by displacing the position from one direction. 2. A reaction vessel for introducing an atmospheric gas containing a reaction gas, an electrode installed in the reaction vessel, the electrode having a shape based on an inverted shape of “a target shape of a processed surface of a workpiece”. , A power source for applying a voltage to the electrode, and the electrode and the workpiece are arranged so as to approach each other by "a movement amount set based on the shape of the electrode and the shape of the processed surface before processing". A processing apparatus using a radical reaction, comprising a moving means for displacing a relative position between an electrode and a workpiece from one direction.