JPH04365549A - Mirror finishing device for outer peripheral surface of work - Google Patents

Abstract

PURPOSE:To perform finish machining of the outer peripheral surface of a work made of a rigid brittle material with high precision using a buffing member and to provide an increased life of a buffing member. CONSTITUTION:A buffing machine bed 24 is reciprocative in the direction extending vertically to the rotary central axis of a work W. A rocking arm 32 is mounted on the buffing machine bed 24 rockably around a rocking shaft in parallel with the axis of the work W. A buffing member 34 for mirror finish rotatably mounted on the rocking arm 32. Mirror finish processing is applied to the outer peripheral surface of the work W in a position on a reference line for intercoupling the rotation center of the work W and the rotation center of the buffing member 34 by means of the buffing member 34. When a slide contact position between the buffing member 34 and the outer peripheral surface of the work W is displaced from the position of the reference line, the rocking arm 32 to hold the buffing member 34 is rocked. Based on a detecting result of a displacement amount owing to rocking, the buffing machine bed 24 is moved in a direction, in which the buffing machine bed approaches or parts from the work, for correction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a mirror finish to the outer periphery of a hard and brittle material such as a silicon wafer.

0002

2. Description of the Related Art The outer peripheral surfaces of silicon wafers and quartz photomasks used in the manufacture of VLSIs are ground with a diamond grindstone, and the outer peripheral edges are also ground and chamfered. Thereafter, the outer circumferential surface of the silicon wafer is chemically treated, and the outer circumferential surface of the quartz photomask is finished by hand as necessary to give a smooth surface. If dust remains on the surface of the silicon wafer and quartz photomask during such grinding and finishing processes, it may cause short circuits in the integrated circuit, so the outer peripheral surface of the silicon wafer, etc. must be cleaned afterwards to remove the dust. needs to be removed. In order to completely remove dust in this cleaning process, in order to mirror-finish the outer peripheral surface of hard and brittle materials such as silicon wafers in the finishing process,
A mirror finishing device disclosed in Japanese Patent No. 6459 has been conventionally used.

[0003] Conventional mirror finishing equipment has a rotating main shaft that rotates at low speed a workpiece made of hard brittle material and a cam formed with a cam surface of a shape corresponding to the outer peripheral surface of the workpiece, and a rotating main shaft parallel to this rotating main shaft. The buffing machine includes a buffing member having a rotation center and a buffing machine stand provided with a copying roller that contacts the cam. This buffing machine stand can be moved toward and away from the rotating main shaft. In such conventional mirror finishing devices, a copying mechanism having a cam and a copying roller or stylus in contact with the cam applies a constant pressure to the outer periphery of the workpiece to press the molding groove of the buffing member that rotates at high speed. ing.

0004

[Problem to be solved by the invention] However, the outer circumferential surface of a hard brittle material such as a silicon wafer may have a linear flat surface in part, and the outer circumferential surface of the workpiece may be circular. Therefore, as the workpiece rotates, the buffing member changes from finishing the circumferential surface of the workpiece to machining the flat surface, or when machining the flat surface. When changing from a state to a state in which a circumferential surface is processed, the contact position between the workpiece and the buffing member changes, and the pressing force of the buffing member against the outer peripheral surface of the workpiece also changes. In this way, when the contact position changes and the pressing force changes, the life of the buffing member may be shortened, and in extreme cases, the buff may be damaged, the workpiece may be displaced, and the workpiece may be broken.

[0005] The present invention is capable of mirror-finishing the entire outer periphery of a workpiece made of hard brittle material under optimal conditions so that the workpiece can be finished with a high yield, and the life of the buffing member can be extended. The purpose is to provide equipment.

[0006]

[Means for Solving the Problems] The interface finishing device for the outer peripheral surface of a workpiece according to the present invention has a workpiece rotation axis for rotating the workpiece around the axis, and a direction perpendicular to the rotation center axis of the workpiece rotation axis. A buffing machine stand is provided to be able to freely reciprocate, a reciprocating means for driving this buffing machine stand, and a rocker attached to the buffing machine stand to be able to swing freely around a rocking axis parallel to the axis of the workpiece. a movable arm; a buffing member rotatably attached to the movable arm and slidingly contacting the outer peripheral surface of the workpiece to give it a mirror finish;
It has a pressing means that applies a pressing force toward the buffing member toward the workpiece, and a displacement amount detection means that detects the amount of swinging displacement of the swinging arm and operates the reciprocating means, A feature is that the sliding contact portion between the workpiece and the buff member is located on a reference line connecting the rotation center of the member.

[0007]

[Operation] The outer peripheral surface of the workpiece is mirror-finished by the buffing member at a position on the reference line connecting the rotational center of the workpiece and the rotational center of the buffing member. When the sliding contact position between the buffing member and the outer circumferential surface of the workpiece deviates from the position of the reference line, the swinging arm that holds the buffing member swings, and the amount of displacement due to this swinging is detected by the displacement amount detection means. Based on this detection result, the buffing machine base moves toward or away from the workpiece for correction, thereby bringing the buffing member into a predetermined sliding contact position with respect to the workpiece, and mirror finishing processing is performed.

[0008]

EXAMPLES The present invention will be explained below with reference to illustrated examples. FIG. 1 is a side view of one embodiment of the present invention, and FIG. 2 is a plan view of FIG. In these figures, the support stand 10 includes:
A work rotation shaft 11 is provided for rotating a work W made of hard brittle material such as a silicon wafer around its axis, and the work W can be freely attached to and removed from a work table 12 provided at the tip of this rotation shaft 11. It becomes. Work rotation axis 1
1 is driven by a work shaft motor 13 provided within the support stand 10 at a rotational speed of, for example, about two revolutions per minute. The workpiece W consists of a circular arc portion P and a linear flat portion S, that is, it has a circular shape with a flat portion partially.

As shown in FIG. 2, the fixed base 14 attached to the support base 10 has a guide rail 15 in the horizontal direction.
A Y-axis guide 16 that slidably engages with the guide rail 15 is attached to a sliding base 17. In order to drive this sliding table 17 in the direction indicated by the symbol Y in FIG. A female screw portion 21 fixed to the moving base 17 is screwed together. Therefore, Y-axis motor 1
8 causes the slide table 17 to reciprocate in the direction shown by arrow Y, that is, in the direction perpendicular to the rotation center axis of the work rotation shaft 11.

A guide rail 22 extending vertically is installed on this sliding table 17.
A Z-axis guide 23 that slidably engages with the buffing machine 24 is attached to the buffing machine stand 24. In order to drive this buffing machine stand 24 in the direction indicated by the symbol Z in FIG.
A Z-axis ball screw 26 rotated by a Z-axis motor 25 attached to the buffing machine base 24 is screwed into a female screw portion (not shown) fixed to the buffing machine stand 24 . Therefore, the Z-axis motor 25 causes the buffing machine stand 24 to slide in the direction shown by arrow Z, that is, in a direction parallel to the rotation center axis of the workpiece W. Further, this buffing machine stand 24 is driven by the Y-axis motor 18 to move the slider stand 1
7, it also reciprocates in a direction perpendicular to the rotation center of the work rotation shaft 11, that is, in the Y-axis direction.

A negative pressure introduction passage (not shown) is formed in the center of the work rotation shaft 11, and this negative pressure introduction passage communicates with an opening formed in the work table 12. In addition, a negative pressure source 2 is connected to a negative pressure valve 27 provided on the work rotation shaft 11.
Negative pressure from 8 is supplied via hose 29. As a result, the work W placed on the work table 12 is moved by the negative pressure introduced from the opening.
It is removably fixed on top of 2.

A support bracket 30 fixed to the front surface of the buffing machine stand 24 is provided with a swinging shaft 31 which is parallel to the rotation center axis of the workpiece rotation shaft 11 so as to be swingable in the direction shown by arrow R. A moving arm 32 is attached. A buffing main shaft 33 is rotatably attached to the tip of the swinging arm 32, and a buffing member 34 is attached to this buffing main shaft 33 as shown. This buff member 34 has the following characteristics:
As shown in the figure, four finishing grooves G corresponding to the finished shape of the outer circumference of the workpiece W are formed. By driving the Y-axis motor 25 and changing the position of the buffing machine stand 24 in the Z-axis direction, any one of the four finishing grooves G is placed on the workpiece W.
is positioned at the position of In order to rotate this buffing member 34, a pulley 36 attached to the main shaft of a buffing drive motor 35 attached to the swinging arm 32 and a buffing main shaft 3
A belt 38 is stretched around a pulley 37 attached to the belt 3. Therefore, the buffing member 34 is rotated by the buffing motor 35 at, for example, 800 to 1500 rpm.
It rotates at a speed of about m.

An air cylinder 40 is provided between the buffing machine stand 24 and the swing arm 32, and the air cylinder 40 applies a pressing force toward the workpiece W to the buffing member 34. . Instead of the air cylinder 40 as the pressing means, a spring member such as a coil spring may be used.

A detection rod 41 is attached to the buffing machine stand 24 so as to be slidable in the Y-axis direction.
The joint part 42 provided at the tip of the swing arm 32
It is pin-coupled to a connecting part 43 fixed to the tip. Stopper portion 4 provided at the rear end of this detection rod 41
4 is in contact with a contact 47 of a displacement detection sensor 46 attached to the buffing machine stand 24 by a bracket 45. In this embodiment, the displacement detection sensor 46 is constituted by an actuating transformer, and a spring member for biasing the contact 47 toward the stopper portion 44 is incorporated therein.

The detection signal of this displacement detection sensor 46 is sent to a control unit 48 built into the device, and this control unit 48
A drive signal is fed back to the Y-axis motor 18 from the Y-axis motor 18.

FIG. 3A is a diagram showing a state in which the buffing member 34 is in sliding contact with the circular arc portion P of the workpiece W. The position in the Y-axis direction is set so that the sliding contact portion of the workpiece W and the buffing member 34 is located on a reference line T connecting the rotation center of the member 34. The buffing member 34 is pressed against the outer periphery of the work W by the pressing force of the air cylinder 40, and as the work W rotates, the flat part S of the work W
When the buff member 34 comes into contact with , the swing arm 32 swings as shown in FIG. 3(B). This swinging displacement amount is detected by the displacement detection sensor 46, and the Y-axis motor 18 is driven based on this detection result, so that the buffing machine The stand 24 is driven in the Y-axis direction. Therefore, Figure 3
As shown in (C), the contact 47 of the displacement detection sensor 46 returns to its original position, the swing arm 32 returns to the direction perpendicular to the reference line T, and the workpiece W is placed on the reference line T. and the buffing member 34 come into sliding contact.

As shown in FIGS. 1 and 2, an annular member 51 is rotatably fitted into a fixed cylinder 55 provided on the outer peripheral side of the work rotation shaft 11.
1 is provided with a protruding correction bit 52 for correcting the four finishing grooves G formed in the buff member 34. Furthermore, this annular member 51 is provided with a handle 53 for rotating the correction tool 52 to a predetermined position and for fastening the correction tool 52 at a predetermined rotational position. Therefore, when the finishing groove G of the buff member 34 is worn out by a predetermined amount or more, the finishing groove G can be corrected using the correction bit 52. At that time, the Y-axis motor 18 and the Z-axis motor 25 are driven so that the predetermined finishing groove G is located at the position of the correction tool 52.

The apparatus of this embodiment operates as follows to apply a mirror finish to the outer periphery of the workpiece W. The outer peripheral surface of the workpiece W is ground and formed into a predetermined shape before this mirror finishing step, and the outer peripheral edge is chamfered. Further, the work W is placed on the work table 12, and the negative pressure source 28
It is fixed in a predetermined position on the work table 12 by negative pressure supplied from the work table 12. The Z-axis motor 25 is moved so that one of the four finishing grooves of the buffing member 34 is at the position of the workpiece W.
The position of the buff member 34 in the Z-axis direction is set by this. In this state, the buffing member 34 is driven by the Y-axis motor 18.
approaches the workpiece W, one of the finishing grooves G of the buffing member 34 engages with the outer peripheral surface of the workpiece W, and mirror finishing is started. When bringing the buff member 34 close to the workpiece W,
Fast forward the buffing machine stand 24. During this finishing step, a polishing agent is supplied between the workpiece W and the buffing member 34, and the workpiece W is rotated by the workpiece shaft motor 13.

When mirror finishing is being performed, the swinging arm 32 is constantly receiving a turning force in the counterclockwise direction in FIG. Even if there is a misalignment between the rotation center of the workpiece W and the rotation center of the workpiece rotation shaft 11 during finishing, that is, a positioning error, the buffing member 3
The swing arm 32 absorbs the vibration of the outer periphery of the workpiece W, and no undue load is applied to the workpiece W. In addition, when the displacement detection sensor 46 detects the attitude of the swinging arm 32 with respect to this vibration and the swinging arm 32 swings, the Y-axis motor 18 moves the buffing machine stand 24 to the Y-axis to correct the swinging. Since the buffing member 34 moves in the axial direction, it comes into contact with the workpiece W on the reference line T, and mirror finishing is always performed under optimal conditions.

When the buff member 34 comes into sliding contact with the straight part S of the work W as the work W rotates, the swinging arm 32 is moved by the pressing force of the air cylinder 40 as shown in FIG. 3(B). will swing counterclockwise,
The contact 47 of the displacement detection sensor 46 moves forward. This amount of forward movement is detected by the displacement detection sensor 46, and in order to correct this amount of movement, the control unit 48 sends a signal to the Y-axis motor 18.
A feedback signal is sent to the motor 18, and the buffing machine stand 24 moves forward by driving the motor 18. As a result, as shown in FIG. 3(C), the swing arm 32 is aligned with the reference line T.
The buffing member 34 and the workpiece W come into sliding contact on the reference line T.

When the state changes from the state in which the buff member 34 is in sliding contact with the straight part S of the workpiece W to the state in which it is in sliding contact with the circular arc part P of the workpiece W, the swinging arm 32 first moves in the opposite direction to the above-mentioned direction. will oscillate, but Y-axis motor 1
As shown in FIG. 3(C), the buffing member 34 is immediately set to a proper finishing position by driving the buffing member 8. As shown in FIG. In the illustrated embodiment, the Y-axis motor 18 moves the buffing machine stand 24 to zero.
．． The swinging arm 32 moves forward and backward in 0.1mm increments.
is maintained perpendicular to the reference line T. As a result, the contact position of the buffing member 32 with respect to the outer peripheral surface of the workpiece becomes constant, and the contact area between the workpiece W and the buffing member 32 becomes almost constant, and a uniform mirror finish can be achieved without damaging the buffing member 32. This is achieved over the entire circumference of the area.

The workpiece is then mirror-finished using the buffing member 34, and the four finishing grooves G of the buffing member 34 are
If one of the grooves has a wear amount exceeding a predetermined value, the Z-axis motor 25 is started to position and move another groove to the position of the workpiece W. In this way, when all of the four grooves G have worn out to a predetermined value or more, each groove is corrected using the correction bit 52.

FIG. 4(A) is a diagram showing a part of the buffing member 34 in which the groove G is not worn and has a proper groove shape.
B) shows a state in which wear has progressed. When the wear has progressed to the extent shown in FIG. 4(B), the outer periphery of the buffing member 34 is removed by a dimension indicated by the symbol a in the figure using the correction tool 52, as shown by the broken line in FIG. 4(B). Correct the groove G into such a shape. When the groove G is corrected in this way, the outer shape of the buffing member 34 becomes smaller, but since a copying roller is not used as in the conventional case, the buffing member 34 is 34 can be used. Therefore, the same buffing member 34 can be used for a long period of time, extending the life of the buffing member.

[0024] In addition to the conventional copying roller, the cam with which the copying roller comes into contact is not used in this embodiment of the apparatus. Therefore, when finishing workpieces with different outer circumferential shapes and sizes are processed using the same device, there is no need to replace the cam, and it is no longer necessary to simultaneously control two axes of a single-shaped workpiece using NC. do not have. Further, although the workpiece W has a straight portion S in part, the shape of its outer circumferential surface is not limited to the type shown in the drawings, and may have various outer circumferential shapes having a plurality of straight portions, even if it is completely circular. It is possible to mirror finish any type of workpiece, even non-circular workpieces. Even when using a completely circular workpiece, if the center of the workpiece is misaligned with respect to the workpiece rotation axis, it has the advantage of being able to finish the workpiece while adjusting the misalignment, but this is especially true for non-circular workpieces. The illustrated equipment will be useful when finishing. Furthermore, the number of finishing grooves G provided in the buffing member 34 used is not limited to four as in the illustrated embodiment, but can be set to any number.

[0025]

[Effects of the Invention] As described above, according to the present invention, the outer circumferential surface of the workpiece can be finished under optimal finishing conditions without using a cam corresponding to the outer circumferential shape of the workpiece or a copying roller that comes into contact with the cam as in the past. This has the effect of improving the yield of mirror finishing and significantly extending the life of the buffing member.

[Brief explanation of drawings]

FIG. 1 is a side view showing one embodiment of the present invention.

FIG. 2 is a plan view of the embodiment device of FIG. 1;

FIG. 3 is a plan view showing the operating state of main parts of the embodiment device of FIG. 1;

FIG. 4 is a sectional view showing the state of wear of the buff member.

[Explanation of symbols]

11 Work rotation axis 18 Y-axis motor 24 Buffing machine stand 31 Swing axis 32 Swing arm 34 Buffing member 40 Air cylinder 46 Displacement detection sensor

Claims (1)

[Claims] Claim 1: A work rotation shaft that rotates the work around the axis, a buffing machine stand provided so as to be able to reciprocate in a direction perpendicular to the rotation center axis of the work rotation axis, and this buffing machine stand. a reciprocating means for driving, a swinging arm mounted on the buffing machine base so as to be swingable about a swinging axis parallel to the axis of the workpiece, and a swinging arm rotatably mounted on the swinging arm to move the workpiece. a buffing member that slides on the outer circumferential surface of the workpiece to give a mirror finish; a pressing means that applies a pressing force to the buffing member toward the workpiece; and a displacement detecting means for activating the means, and the sliding contact portion between the workpiece and the buffing member is located on a reference line connecting the axis of the workpiece and the rotation center of the buffing member. Mirror finishing device for the outer surface of the workpiece.