JPH1148109A - Mirror polishing method and device for work edge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing means of small size excellent in working efficiency and allow efficient mirror polishing in a short time at plural points of a peripheral edge of a work. SOLUTION: Two cylindrical polishing drums 2, 2 provided with a working face 2a for polishing in its periphery are disposed keeping a smaller space than a diameter of a work 7, and mirror polishing of an edge is conducted in different two points by pressing simultaneously the peripheral chamfered edge of the work holded in a work holding means 3a to the both polishing drums 2, 2 while rotating the drums 2, 2 by a required speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for mirror-polishing a chamfered edge portion of an outer periphery of a substantially disk-shaped work such as a semiconductor wafer or a magnetic disk substrate. It is about.

[0002]

2. Description of the Related Art For example, a semiconductor wafer such as a silicon work is generally subjected to chamfering at a peripheral portion thereof in order to prevent edge chipping and prevent crown during epitaxial growth. This chamfering is performed by grinding with a diamond grindstone, but a work-strained layer tends to remain after the grinding, and if such a work-strained layer remains, crystal defects occur when heat treatment is repeated in the device process. Sometimes. For this reason, the work strain layer is usually removed by etching, but the etched surface is likely to have wavy or scaly irregularities and dirt is likely to remain. Is a major cause of deterioration.

Therefore, in recent years, a technique for smoothing a chamfered edge of a wafer by mirror polishing has been established as a technique completely different from polishing of the wafer surface. As disclosed in JP-A-71656, a technique for polishing an edge has already been proposed. In this polishing technique, while rotating a wafer having a chamfered edge on the outer periphery, the outer peripheral edge is pressed against the outer working surface of the rotating polishing drum to polish the wafer. Polishing can be performed simply and reliably, and all the problems caused by the chamfering as described above can be solved.

However, since this type of polishing apparatus performs polishing by bringing a wafer into contact with a polishing drum at a point, it cannot be said that the processing efficiency is always good, and the processing takes a considerable time. Therefore, at present, various measures have been taken to increase the diameter of the polishing drum so that the contact length with the wafer is made as long as possible, thereby shortening the processing time.

[0005] However, in the method of circumscribing a circular wafer to a cylindrical work surface, there is a limit in extending the contact length, and the processing time cannot be reduced so much. In addition, when the diameter of the polishing drum is increased, the installation space is correspondingly increased, so that the size of the apparatus cannot be avoided. In particular, in the future where the demand for large wafers having a diameter of 30 to 40 cm is expected, the space occupied by the wafers will further increase, and the polishing apparatus will become larger and larger.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized polishing means with excellent processing efficiency, capable of efficiently and mirror-polishing the outer peripheral edge of a work at a plurality of points in a short time. .

[0007]

In order to solve the above-mentioned problems, the present invention provides a plurality of cylindrical polishing drums each having an outer peripheral surface as a work surface for polishing, which are arranged at an interval smaller than the diameter of a work. While rotating the polishing drum at a required speed, a disk-shaped work having a chamfered outer edge is simultaneously brought into contact with the working surfaces of a plurality of polishing drums, thereby polishing the outer edges of the front and rear surfaces at different points. Like that.

According to the present invention, since the outer peripheral edge of the work is polished at a plurality of points, the polishing efficiency is improved and the polishing time is shortened. In addition, not only can a polishing drum having a much smaller diameter than in the past be used, but also polishing is performed with the tip of the work fitted into the space between adjacent polishing drums. The space occupied by the drum and the work is very small, and the device is very compact.

According to one specific embodiment of the present invention, two polishing drums, first and second work holding means, and means for turning the work upside down are provided. The side edge is pressed against the working surfaces of the two polishing drums on the first side of the two polishing drums by the first work holding means and polished, and the back side edge is formed by the second work holding means. The second side is pressed against the working surfaces of both polishing drums to be polished.

[0010] In the present invention, preferably, the two polishing drums are inclined so that their tip sides approach each other, so that both polishing drums are perpendicular to the conical edge. Can be contacted. In the present invention, it is preferable that the polishing drum and the work holding means are relatively movable in order to prevent the uneven wear of the work surface by changing the contact position of the work with the work surface.

In a further preferred embodiment of the present invention,
The work holding means is provided with a biasing means for bringing the work into contact with the work surface at a constant pressure during processing, and the work is uniformly contacted with the two polishing drums by correcting the positional deviation of the work with respect to the two polishing drums. And a centering means for performing the alignment.

[0012]

1 and 2 show a first embodiment of a polishing apparatus according to the present invention. This polishing apparatus comprises a machine body 1 and two machines provided on the machine body 1 side by side. Cylindrical polishing drums 2 and 2 and first and second 2 disposed opposite to the first side and the second side with the polishing drums 2 and 2 interposed therebetween.
One work holding means 3a, 3b, a loading section 4 provided on one side of the machine body 1 for carrying in unprocessed works, and a work section provided on the other side of the machine body 1 for carrying out processed works. It has an unloading section 5 and a work transfer means 6 for chucking and transferring the work.

The above-mentioned polishing drums 2, 2 have a work surface 2a for polishing by attaching a polishing pad to an outer surface of a base cylinder. However, they are arranged with their leading ends inclining in a direction approaching each other while maintaining an interval smaller than the diameter of the work 7 therebetween, and each is rotatable about its own axis L2. The drum shafts 10 of these polishing drums 2 and 2 are connected to a drive source such as a motor.
0 to 1000 r. p. m. They are driven at the same speed in the same or opposite directions at a constant speed or at different speeds. Each of the drum shafts 10 is supported by the body 1 so as to be reciprocally movable in the direction of its own axis L2, and is connected to a swinging means (not shown) including a ball screw and a nut member screwed thereto. , So that each polishing drum 2, 2
However, it can swing synchronously in the axial direction at a slow speed during machining. The swing directions at this time may be the same as each other, or may be opposite to each other, such as when one moves forward while the other moves backward.

As is clear from FIGS. 3 and 4, the inclination angle of the two polishing drums 2 is such that their axis L2 is the center axis L7 of the workpiece 7 to be polished in the forwardly inclined state.
, So that both polishing drums 2 and 2 come into contact with the conical edge 7a at right angles over the entire width. However, if the distance between the two polishing drums 2 is small and they can be brought into contact with the edge at an angle close to a right angle over the front width, the two polishing drums should be installed parallel to each other without tilting. May be. Reference numeral 11 in the drawing denotes a cover for preventing the cleaning liquid during processing from scattering.

The first and second work holding means 3a,
3b holds a disk-shaped work 7 (see FIG. 3) having outer peripheral edges 7a, 7a chamfered at an angle θ on the front and back sides, rotates around a shaft line L7, and any one of the edges of the work. 7a for simultaneously contacting the work surfaces 2a, 2a of the two polishing drums 2, 2 and have the same configuration.

That is, the work holding means 3a, 3b
A chuck head 14 for vacuum chucking the work 7, a first body 15 for rotatably holding the chuck head 14, and a second body for supporting the first body 15 so as to be tiltable about a support shaft 17. It has a body 16 and a support mechanism 13 for supporting the second body 16 so as to be linearly movable in a direction of coming into contact with and separating from the polishing drums 2. The support mechanism 13 has a slide table 18 on which a second body 16 is slidably mounted. The slide table 18 comes into contact with and separates from the polishing drums 2 along the rails 19 on the body 1. It is supported so that it can move linearly in the direction, and can be moved by driving means such as the cylinder 20.

The chuck head 14 has a plurality of suction holes 14a on the surface thereof.
Are connected to a vacuum source via ports and piping tubes provided in the first body 15 and the second body 16, but these are not shown. The chuck head 14 is connected to a motor provided in the first body 15 and is driven at a slow speed of about one rotation every 40 to 60 seconds during edge polishing.

The first body 15 is, as shown by a solid line in FIG. 2, a standby position in which the chuck head 14 is oriented horizontally and separates the work 7 from the polishing drums 2, 2, and is shown by a chain line in FIG. Thus, the chuck head 14 tilts and tilts between the processing position where the edge 7a of the work contacts the two polishing drums 2 and 2. Actually, the work holding means 3a, 3b are moved by the cylinder 20 to a position slightly further away from the polishing drums 2, 2 at the standby position.

On the other hand, on the second body 16, one end of a wire 24 wound around a pulley 23 on a slide table 18 is fixed to an arm 16a extending therefrom. The second body 16 is urged by a constant force toward the polishing drums 2 and 2 by the gravity of the weight 25. The weight 25 constitutes urging means for pressing the workpiece 7 against the polishing drums 2 and 2 at a constant contact pressure during polishing. In addition,
When the edge 7a is not polished, the second body 16 is engaged with the stopper 18a at the front end of the slide table 18, as shown in FIG.

The work transfer means 6 has a chuck head 30 for vacuum-chucking the work 7 at the tip of a chuck arm 29 which is rotatable and retractable about an axis L6 and which can be turned upside down. The operation of supplying an unprocessed work from the loading section 4 to the chuck head 14 of the first work holding means 3a by the head 30, and the work 7 whose front side edge 7a has been polished from the first work holding means 3a is turned over. Then, an operation of transferring the workpiece 7 to the second work holding means 3b and an operation of carrying out the work 7 whose back surface side edge 7a has been polished from the second work holding means 3b to the unloading section 5 are performed. In the figure, reference numeral 31 denotes a nozzle for supplying an abrasive slurry to a polishing portion.

In the polishing apparatus having the above configuration, when an unprocessed work is supplied from the loading section 4 to the chuck head 14 of the first work holding means 3a at the standby position by the work transfer means 6, the first body 15 is moved. , FIG. 2
As shown by the broken line, the edge 7a is inclined forward about the support shaft 17 by an angle determined by the chamfer angle θ of the edge 7a. The operation of the cylinder 20 causes the slide table 18 to advance in the direction of the polishing drums 2 and 2 along the rail 19, and the front-side edge 7 a of the workpiece 7 held and rotated by the chuck head 14 rotates 2 First of two polishing drums 2,2
The side is pressed against the outer working surfaces 2a, 2a and polished.

The contact pressure of the work 7 on the work surface 2a is obtained by the gravity of the weight 25. That is, before the slide table 18 moved by the cylinder 20 reaches the stroke end, the work 7 comes into contact with the polishing drums 2 and 2 and the second body 16 stops at that position. Is moved forward by a certain distance, the weight of the weight 25 acts on the work 7 via the second body 16, and the weight of the weight 25 constantly presses the two polishing drums 2 and 2 with a constant contact pressure during processing. Will be done.

At this time, the work holding means 3a, 3b
In order to prevent the work 7 from biasing toward one of the work surfaces 2a due to the bias of the work 7 toward one of the polishing drums 2, the misalignment is corrected and the work is moved to the two polishing drums 2. It is desirable to provide a centering means for evenly contacting the two. This alignment means only needs to be able to freely move at least the chuck head 14 in a direction parallel to the axis of the support shaft 17, that is, in a direction parallel to the line connecting the centers of the two polishing drums 2 and 2. For example, the first body 15 is moved relative to the second body 16 by a linear guide mechanism including a guide rail (not shown) and a slider that can slide linearly along the guide rail.
A configuration in which the polishing drums 2 and 2 are movably supported in the directions of the two polishing drums 2 and 2 may be used.

Thus, the edge 7a on the front side of the work 7
Are simultaneously mirror-polished at two different points by simultaneously contacting the working surfaces 2a, 2a of the two polishing drums 2, 2. During the polishing, the two polishing drums 2, 2 slowly reciprocate in the direction of their axis L2. Swing to change the contact position with the work.

When the polishing of the edge 7a on the front side of the work 7 is completed, the first work holding means 3a is
The work 7 moves away from the polishing drums 2 and 2 and the first body 15 returns to the standby position to
Orient horizontally.

Next, the work transfer means 6 receives the work 7 from the first work holding means 3a, inverts it and supplies it to the second work holding means 3b. Polishing of the edge 7a of
The polishing is performed in the same manner as in the case of polishing the edge on the front side on the second side of the two polishing drums 2 and 2.

Working surfaces 2a, 2a of the polishing drums 2, 2
It is desirable that the outer peripheral surface 7b of the workpiece should have such a flexibility that the outer peripheral surface 7b can bite into the inside of the edge 7a at least about half of its width when the edge 7a is polished. The outer peripheral surface 7b can also be polished.

When the polishing of the back side edge 7a is completed, the second work holding means moves to the standby position, and the work transfer means 6 receives the work 7 from the second work holding means 3b and transfers it to the unloading section. Take out to 4.

The polishing of the front side edge 7a by the first work holding means 3a and the polishing of the back side edge 7a by the second work holding means 3b are performed synchronously in an automatic process. The transfer of the work 7 by the work transfer means 6 is performed in an order and timing adapted thereto.

In the above embodiment, the urging means for setting the contact pressure of the workpiece 7 during the polishing process is constituted by the weight 25. Instead of this weight, the urging means is constituted by an air cylinder with pressure adjusting means. You may. In the illustrated polishing apparatus, only one set of polishing means including two polishing drums 2, 2 and two work holding means 3a, 3b is shown. It is desirable to provide a plurality of sets of polishing means, such as providing another set of polishing means on the opposite side of the means 6.

Furthermore, in the illustrated embodiment, the two polishing drums 2 and 2 and the chuck head 14 are installed with their axes vertical, but they can also be installed with their axes horizontal. . That is, as shown in FIG. 1 as a front view, the two polishing drums 2 and 2 are arranged side by side vertically and the chuck head 14 is also arranged horizontally and the work 7 is held vertically. Polishing may be performed.

FIG. 5 shows a different example of a support mechanism for movably supporting the work holding means 3a, 3b on the machine body 1. This support mechanism 13A slides the second body 16 directly on the rail 19. The pulley 23 is attached to the body 1 while being movably mounted, and the arm 16a of the second body 16 is
Is pushed directly by the rod 20a of the air cylinder 20 in a direction away from the polishing drums 2, 2. In the drawing, reference numeral 26 denotes a stopper for stopping the second body 16 at the standby position. In the support mechanism 13A, when the rod 20a of the air cylinder 20 is shortened from the standby position shown in the drawing during the edge polishing, the second body 16
Moves on the rail 19 in a direction approaching the polishing drums 2 and 2 by the gravity of the weight 25, and the polishing drums 2 and 2 move.
The workpiece 7 is stopped at a position where the workpiece 7 abuts, but thereafter the rod 20a is slightly shortened and separates from the arm 16a, so that the workpiece 7 is pressed against the polishing drums 2 by the gravity of the weight 25.

FIG. 6 shows a second embodiment of the present invention.
The polishing apparatus according to the second embodiment includes three polishing drums 32 arranged at the vertices of a triangle and two adjacent polishing drums 32.
Three work holding means 33 disposed between the two polishing drums 32, 32;
And a work transfer means 36 for feeding and discharging the work 7 to and from the front and back of the work 7, and the three work holding means 33 abut the front-side edge of the work 7 on two adjacent polishing drums 32, 32. After the polishing, the workpiece 7 is turned upside down, and the rear side edge is brought into contact with the two polishing drums 32, 32 for polishing.

Since the constructions of the work holding means 33 and the work transfer means 36 are substantially the same as those of the first embodiment, the necessary parts are given the same reference numerals as in the first embodiment. The detailed description is omitted. Also, the loading section and the unloading section are omitted.

In the second embodiment, the three polishing drums 32 allow the edges of the three workpieces 7 to be brought into contact with a plurality of points at the same time for polishing, so that the polishing efficiency is very good.

FIG. 7 shows a third embodiment of the present invention.
The polishing apparatus according to the third embodiment includes four polishing drums 42a to 42d disposed so as to be located at the vertices of a square,
Four work holding means 43a to 43d arranged so as to be located between two adjacent polishing drums, and two work transfer means 46a and 46b for feeding and discharging the work to these work holding means and reversing the front and back. And

The first and third two work holding means 43a and 43c among the four work holding means are provided with two polishing drums 42 adjacent to the surface side edge of the work 7.
The second and fourth work holding means 43b and 43d are used for polishing by contacting the first and third work holding means 43a and 43c with the first and third work holding means 43a and 43c. The edge on the back side of the work 7 whose front side edge has been polished is replaced with two polishing drums 42b and 42.
This is for polishing by abutting on c and 42c, 42d. Then, the first work holding means 43a and the second
The first work transfer means 46 between the work holding means 43b
a, and a second work transfer means 46b is provided between the third work holding means 43c and the fourth work holding means 43d.

The work holding means 42a-42
Since the constructions of d and each of the work transfer means 46a and 46b are substantially the same as those of the first embodiment, the necessary parts are denoted by the same reference numerals as those of the first embodiment, and their detailed description is omitted. I do. Also, the loading section and the unloading section are omitted.

In the illustrated embodiment, the first work holding means 43a and the third work holding means 43c for polishing the front side edge, and the second work holding means 43b and the second work holding means 43b for polishing the back side edge are provided. 4 work holding means 43d
Are provided at positions adjacent to each other, but they can also be provided at opposing positions.

Since the third embodiment is substantially the same as the case where two sets of polishing means are provided in the first embodiment, the edge of the work is polished twice as efficiently as in the first embodiment. It is possible to excel in polishing efficiency.

[0041]

As described above, according to the present invention, by simultaneously bringing the edge of a work into contact with a plurality of polishing drums, it is possible to simultaneously perform mirror polishing at a plurality of points, thereby improving the polishing efficiency and remarkably shortening the polishing time. Can be shortened. In addition, not only can a polishing drum having a much smaller diameter than in the past be used, but also the polishing can be performed with the tip of the work fitted between adjacent polishing drums. The space occupied by the polishing drum and the work is very small, and the apparatus is very small.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a polishing apparatus according to the present invention.

FIG. 2 is a partially broken front view of FIG.

FIG. 3 is an enlarged view of a main part in a polished state of a work edge in FIG. 2;

FIG. 4 is a view of FIG. 3 as viewed from an axial direction of a work.

FIG. 5 is a cross-sectional view of a main part showing an example of a different structure of a support mechanism that movably supports the work holding means.

FIG. 6 is a plan view showing a second embodiment of the polishing apparatus according to the present invention.

FIG. 7 is a plan view showing a third embodiment of the polishing apparatus according to the present invention.

[Explanation of symbols]

 2, 32, 42a to 42d Polishing drum 2a Work surface 3a, 3b, 33, 43a to 43d Work holding means 6, 36, 46a, 46b Work transfer means 7 Work 7a Edge 25 weight

Claims (8)

[Claims] 1. A step of rotating a plurality of cylindrical polishing drums located at intervals smaller than the diameter of a work at a required speed; rotating a disk-shaped work having chamfered outer edges on both sides thereof at a required speed. A step of simultaneously bringing the edge on the front side into contact with the outer working surface of a plurality of polishing drums for polishing; a step of inverting the work; a step of rotating the inverted work at a required speed to form an edge on the back side. Polishing the workpiece by simultaneously contacting the workpieces with the working surfaces of a plurality of polishing drums. 2. The polishing method according to claim 1, wherein two polishing drums are provided, and the step of polishing the edge on the front side of the work is performed on the first side of the two polishing drums, and the edge on the back side is polished. The step of performing is performed on the second side of the polishing drum. 3. The polishing method according to claim 1, further comprising a step of relatively moving the polishing drum and the work to change a contact position of the work with a work surface. 4. A plurality of workpieces, each of which is rotatably disposed with an interval smaller than the diameter of the work and has a working surface on each of its outer circumferences for mirror-polishing the outer peripheral edge of the work at a plurality of different points. Cylindrical polishing drum; means for rotating the polishing drum; holding and rotating a disk-shaped work having chamfered outer edges on the front and back surfaces, and simultaneously bringing the work edge into contact with the working surfaces of a plurality of polishing drums. A mirror polishing apparatus for a work edge, comprising: at least one work holding means; means for turning the work upside down. 5. The polishing apparatus according to claim 4, wherein two polishing drums, first work holding means for pressing a front side edge of the work against a work surface at a first side of the polishing drums, and the polishing drum. And a second work holding means for pressing the back side edge of the work on the work surface on the second side. 6. A polishing apparatus according to claim 5, wherein said two polishing drums are inclined in such a direction that their tip sides approach each other. 7. A polishing apparatus according to claim 4, wherein said polishing drum and said work holding means are relatively movable to change a contact position of said work with respect to a work surface. Features. 8. A polishing apparatus according to claim 4, wherein said work holding means comprises: an urging means for bringing said work into contact with a work surface at a constant pressure during machining.
And a centering means for correcting a positional shift of the work with respect to one of the polishing drums and bringing the work into contact with both polishing drums evenly.