JP2000288885A - Edge grinding device for circular thin plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relatively move a grinding wheel and a wafer at least in a direction along a rotation axis of the waber without generation of vibration to improve machining accuracy of a grind face of the wafer. SOLUTION: This device is provided with disc-like grinding wheels 72, 73 each having a flat grind operation face on its periphery, rotatable around an axis perpendicular to the rotation axis of a wafer 25. By relatively moving the grinding wheels 72, 73 and the wafer 25 in directions X, Y in a plane including the rotation axis of the grinding wheels 72, 73 and in a direction Z along the rotation axis of the wafer 25, a peripheral edge of the wafer 25 is ground. Among moving structures for relatively moving the grinding wheels 72, 73 and the wafer 25 in the directions X, Y, Z, at least the moving structure for the direction Z is provided with a guide mechanism including hydrostatic bearings 42, 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge grinding device for grinding an outer peripheral edge of a circular thin plate such as a wafer.

[0002]

2. Description of the Related Art In a general processing apparatus, a guide mechanism using a rolling guide system is often used. For example, when grinding the edge of a wafer that is a circular thin plate, a disk-shaped rotary grindstone is used so that the disk-shaped rotary grindstone is moved between the front and back surfaces of the outer peripheral portion of the wafer. A configuration is conceivable in which relative movement is caused between the wafer and the wafer, and a rolling guide system is also used for a guide mechanism for guiding the relative movement.

However, as shown in FIG. 4A, in a general rolling guide unit 201, a discontinuous behavior when a ball or a roller, which is a rolling element 202, enters or exits a guide groove 203, As shown in FIG. 4B, there is a problem that extremely small vibration is generated in a direction perpendicular to the moving direction. The period of these vibrations is relatively long because it is determined by the continuous movement of the rolling elements.

[0004] When grinding the edge of a wafer that requires high precision, if vibration occurs in a mechanism that guides the grindstone or the wafer, the irregular movement is transferred to the processed surface of the wafer, and the grinding precision deteriorates. There is a possibility that.

When the edge of the wafer is ground for a short length, but the stroke of the relative movement of the grindstone or the wafer required for processing the edge is long, the amplitude of the unevenness is not reduced. The amplitude of the irregularities is aggregated in a narrow processing range. For this reason, large irregularities having a large difference in height are formed on the processed surface of the wafer, and the processing accuracy is significantly reduced.

An object of the present invention is to provide an edge grinding apparatus capable of performing edge grinding of a circular thin plate such as a wafer with high accuracy in view of the above problems.

[0007]

In order to achieve the above object, according to the present invention, a relative movement between a circular thin plate for processing and a disk-shaped rotary grindstone is guided. Only the guide mechanism described above is constituted by a static pressure bearing.

Accordingly, when the grindstone and the circular thin plate are relatively moved in, for example, the Z direction along the rotational axis of the circular thin plate and the Y direction perpendicular thereto, the guide mechanism including the hydrostatic bearing causes the grindstone and the circular thin plate to move. The relative movement with the thin plate is performed smoothly. Therefore, it is possible to prevent the occurrence of vibration during the relative movement between the grindstone and the circular thin plate, and it is possible to improve the processing accuracy of the grinding surface of the circular thin plate.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 and 2, in a wafer edge grinding apparatus as a wafer processing apparatus according to this embodiment, a pair of bases 2 are provided.
1 and 22 are combined. On the first base 21, a wafer suction rotation elevating mechanism 23 and an edge grinding mechanism 24 are disposed, and the outer peripheral edge of a wafer 25 as a circular thin plate sucked and held by the wafer suction rotation elevating mechanism 23 is an edge. The grinding is performed by the grinding mechanism 24.

On the second base 22, a wafer loading / unloading mechanism 29 is provided. Wafer loading / unloading mechanism 29
, A first moving table 33 is movably disposed between a processing position P3 corresponding to the wafer suction rotation elevating mechanism 23 and a retreat position P2 distant therefrom. Also,
On the first moving table 33, a second moving table 34 is supported so as to be integrally movable with the first moving table 33 and relatively movable. Then, the unprocessed wafer 25 is loaded into the wafer suction rotation elevating mechanism 23 by the first moving table 33, and the processed wafer 25 is unloaded from the wafer suction rotation elevating mechanism 23 by the second moving table 34. Done.

A cover 35 is mounted on the bases 21 and 22 so as to cover various mechanisms on the upper surfaces thereof, and a shutter 36 is provided at a substantially intermediate portion so as to be able to move up and down. During the grinding of the wafer 25, the shutter 36 is closed, and the portion on the first base 21 and the second
By keeping the portion on the base 22 isolated, the coolant and the like are prevented from scattering on the portion of the base 22. When the wafer loading / unloading mechanism unit 29 loads or unloads the wafer 25, the shutter 3
6 is opened.

Next, the wafer suction rotation elevating mechanism 2
The configuration of No. 3 will be described in detail. As shown in FIGS. 1 and 3, a frame 39 is provided on the first base 21, and a guide cylinder 40 is mounted on the first base 21 so as to extend in the vertical direction (Z direction). The support cylinder 4 is provided in the guide cylinder 40.
1 is supported via a hydrostatic bearing 42 so as to be movable in the Z direction, and a pair of bearing cylinders 43 and 44 are disposed therein. A support shaft 45 is provided on each of the two bearing cylinders 43 and 44 by a hydrostatic bearing 4.
6 and rotatably and vertically movable, and an air passage 45a is formed at the center thereof.
5a is connected to a vacuum pump (not shown) via a hose 45b.

A suction pad 47 is fixed to the lower end of the support shaft 45 by a bolt (not shown). An air passage 47a communicating with an air passage 45a of the support shaft 45 is formed at the center of the suction pad 47, and an air passage is formed on the lower surface. A plurality of air suction grooves 47b communicating with 47a are formed. Support tube 41
A rotation motor 48 is provided in the inside thereof, and its stator 48
a is fixed to the support cylinder 41, and the rotor 48b is fixed to the support shaft 45. Then, the suction pad 47 is rotated by the rotation motor 48 via the support shaft 45.

A moving motor 50 is provided on the frame 39.
Is provided, and a ball screw 51 is protruded from a lower portion thereof. A connecting arm 52 protrudes from an outer periphery of the support cylinder 41, and a nut 53 screwed to the ball screw 51 is attached to a tip of the connecting arm 52. When the ball screw 51 is rotated by the moving motor 50, the support cylinder 41 is moved up and down via the nut 53, and the suction pad 47 is moved up and down.

Next, the configuration of the edge grinding mechanism 24 will be described in detail. As shown in FIGS. 1 to 3 and 5, a shift support base 60 is disposed on the first base 21,
A pair of shift guide rails 61 are laid on the upper surface so as to extend in the oblique shift direction S from left front to right rear in a horizontal plane. Shift guide rail 61
A shift table 62 is supported so as to be shiftable on the upper side, and a pair of X-direction guide rails 63 extending in the left-right direction (X direction) in a horizontal plane is laid on the upper surface thereof.

A movable platform 64 is supported on the X-direction guide rail 63 via a pair of rolling units 79 (see FIG. 5) so as to be movable in the front-rear direction (Y direction) in a horizontal plane. A pair of extending Y-direction guide rods 65 are provided. Saddle 6 on Y-direction guide rod 65
6 is movably supported via a hydrostatic bearing 80, and a machining head 67 is mounted on the upper portion thereof via a support shaft 68 via a motor 76,
It is supported by a ball screw 83 so as to be pivotable about a vertical axis. A pair of rotating shafts 6 are provided on both sides of the processing head 67.
9 and 70 are protruded so as to extend in a horizontal direction orthogonal to the axis of the support shaft 68, and are rotated by a motor 71 housed in the processing head 67. In order to reduce the cost, only the Z- and Y-axes related to machining were used as hydrostatic bearings.

As shown in FIG. 1 to FIG.
Is provided with a rough grinding wheel 72 for rough grinding the outer peripheral edge of the wafer 25, and the other rotary shaft 70 is provided with a finish grinding wheel 73 for final grinding the outer peripheral edge of the wafer 25. . The grinding wheel 72 for rough grinding and the grinding wheel 73 for finish grinding are each formed of a disk-shaped grinding wheel having a planar grinding action surface on the outer periphery.

Here, the guide mechanism according to the embodiment of the present invention will be described in detail. FIG. 6 shows an example of a conventional method for grinding an edge of a wafer, and FIG. 7 is an explanatory view of an embodiment used in the present invention. 6 and 7, the elements to be moved are different from each other, but the disk 25 and the disk-shaped grindstone 72 or 73 having a grinding action surface on the outer periphery are combined with the wafer 25.
Is relatively moved between the front and back surfaces of the wafer 25 to grind the outer peripheral edge portion 90 of the wafer 25. That is, in FIG. 6, the wafer 25 is fixed, and the disk-shaped rotary grindstone 72 or 73 is moved in the vertical Z direction and the horizontal Y direction,
0 grinding is performed. In the case of the embodiment of the present invention, FIG.
And the wafer 25 fixed to the suction pad 47 as shown in FIG.
Is moved up and down in the Z-axis direction. On the other hand, the disc-shaped rotary grindstone 72 or 73 is moved by the machining head 67 supported by the saddle 66.
Of the guide rod 6 while being rotated by the motor 71 of FIG.
5 and is guided by the static pressure bearing 80 to move back and forth in the Y direction. By the combination of the movement in the X direction and the movement in the Y direction, the front and back of the edge portion 90 of the wafer 25 are ground.

Next, the effect when the hydrostatic bearing is used will be described. FIG. 8A is a schematic diagram showing a case where a rolling guide system conventionally used in the embodiment of the present invention is used. First, in the case of the Z axis, the wafer 25 is fixed to the suction pad 47, rotated by the wafer rotating mechanism 23b, and vertically moved on the guide rail 23d in the Z direction while being supported by the rolling guide unit 23c.

Next, in the case of the Y axis, the disc-shaped rotary grindstone 72 or 73 is supported by the rolling unit 66c while being rotated by the motor 71 accommodated in the processing head 67 supported by the saddle 66b, and moves on the guide rail 66d. It can be moved left and right in the Y direction.

As shown in FIG. 6 and FIG.
In order to machine the edge portion 90 of the wafer 5, the wafer 25 or the disk-shaped rotary grindstone 72 or 73 must be moved. The moving strokes S1 and S2 are the wafer 2 to be machined.
5 is much longer than the width W and thickness T of the edge portion, which are usually 1 mm or less.

Therefore, in the case of the Z-axis movement, when the rolling guide method is used as shown in FIG. 8B, as described above, the vibration of the amplitude a having a long cycle over the entire movement stroke S2 is caused in the Z direction. Occurs vertically. Moving stroke S2
Since the wafer 25 and the disk-shaped rotary grindstone 72 or 73 are always in contact during the machining, the vibration is generated by the wafer 25.
8 (c), the moving stroke S2 is condensed into the processing stroke T, and appears as the vibration of the wafer 25, and is transferred to the processing surface. Will be done.

In the case of Y-axis movement, the saddle 66b is guided by the rolling unit 66c as shown in FIG. 8 (d), so that the vibration of the amplitude b is long as shown in FIG. 9 (d). Is generated over the movement stroke S1, which is condensed to the width W of the edge portion 90 as in the case of the Z axis, and the stroke at the time of machining appears as shown in FIG.

This vibration does not vary in amplitude but has a very short cycle, and thus has a great influence on the surface roughness of the edge 90 of the wafer 25 to be processed. As described above, when the rolling guide method is used for the guide mechanism, a decrease that adversely affects the processing accuracy occurs as described above.However, by using the hydrostatic bearing, the adverse effect of the rolling guide method is eliminated, and good processing accuracy is achieved. Obtained, especially when grinding the edge of the wafer, it is possible to process the surface with high precision.

The effects that can be expected from the above embodiment will be described below. In the edge grinding apparatus for the wafer 25 of this embodiment, the disc-shaped rotary grindstones 72 and 73 having a flat grinding surface on the outer periphery are rotatably arranged around an axis orthogonal to the rotation axis of the wafer 25. Has been established. Then, the disk-shaped rotary grindstones 72 and 73 and the wafer 25 relatively move in the Y direction in a plane including the rotation axis of the disk-shaped rotary grindstones 72 and 73 and in the Z direction along the rotation axis of the wafer 25. Then, the outer peripheral edge of the wafer 25 is ground. Further, among the moving configurations for relatively moving the disk-shaped rotary grindstones 72 and 73 and the wafer 25 in the Y direction and the Z direction, a guide mechanism including the hydrostatic bearings 42 and 46 is provided in the moving configuration in the Z direction. Have been.

Therefore, when the wafer 25 is moved at least in the Z direction, the relative movement between the disc-shaped rotary grindstones 72B and 73 and the wafer 25 is smoothly performed by the guide mechanism including the hydrostatic bearings 42 and 46. Done. Therefore, unlike the conventional configuration including the guide mechanism including the rolling bearing, it is possible to prevent the occurrence of vibration during the relative movement between the disk-shaped rotary grindstones 72 and 73 and the wafer 25, and to prevent the wafer 25 from moving. The processing accuracy of the ground surface can be improved.

A guide mechanism including a hydrostatic bearing 80 is also provided in the moving configuration of the processing head 67 in the Y direction.
Therefore, even when the disc-shaped rotary grindstones 72 and 73 and the wafer 25 are relatively moved in the Y direction within a plane including the rotation axis of the disc-shaped rotary grindstones 72 and 73, the guide including the hydrostatic bearing 80 is also provided. By the mechanism, the relative movement between the disc-shaped rotary grindstones 72 and 73 and the wafer 25 is smoothly performed. Therefore, it is possible to prevent the occurrence of vibration even when the disc-shaped rotary grindstones 72 and 73 and the wafer 25 are relatively moved in the Y direction, and it is possible to further improve the processing accuracy of the ground surface of the wafer 25. .

A mechanism for supporting the rotation of the wafer 25 is also provided with a hydrostatic bearing 46. For this reason, the wafer 25 is supported so as to be smoothly rotated, and the wafer 2 is supported.
The processing accuracy of the ground surface of No. 5 can be further improved.

This embodiment can be modified and embodied as follows. In the above embodiment, in order to reduce the cost, the hydrostatic bearing is used only for the moving shaft related to the machining. Use bearings.

The present invention is embodied in a grinding apparatus for grinding the edge of a circular thin plate other than a wafer.

[0031]

As exemplified in the above embodiment,
In the present invention, the guide mechanism for guiding the relative movement between the circular thin plate and the disk-shaped rotary grindstone is constituted by the hydrostatic bearing, so that the relative movement between the grindstone and the wafer in the Z direction and the Y direction is achieved. Vibration can be prevented from occurring, and the processing accuracy of the ground surface can be improved.

[Brief description of the drawings]

FIG. 1 is a front view showing an edge grinding device embodying the present invention.

FIG. 2 is a plan view of the edge grinding device.

FIG. 3 is an enlarged cross-sectional view showing a main part of a wafer suction mechanism.

FIGS. 4A and 4B generally show a rolling unit, FIG. 4A is a side view thereof, and FIG. 4B is a diagram showing vibration.

FIG. 5 is a sectional view of a main part showing a bearing configuration in the X and Y directions of an edge grinding mechanism.

FIG. 6 is an explanatory view showing grinding by a rough grinding wheel and a finish grinding wheel.

FIG. 7 is a simplified sectional view showing grinding by a rough grinding wheel and a finish grinding wheel.

8A and 8B show the operation of the embodiment, FIG. 8A is a schematic diagram showing a processing portion, FIG. 8B is a diagram showing amplitude in Z-direction movement when a rolling guide system is used, and FIG. FIG. 4D is a condensed diagram, FIG. 4D is a diagram showing the amplitude in the Y-direction movement when the rolling guide system is used, and FIG.

[Explanation of symbols]

23: wafer suction mechanism, 24: edge grinding mechanism,
25: a wafer as a circular thin plate; 42, a static pressure bearing constituting a Z-direction guide mechanism; 46, a static pressure bearing constituting a Z-direction guide mechanism; 57, a static pressure bearing; 63, an X-direction guide rail; ... Moving table, 65... Y-direction guide rod, 67... Machining head, 81... Hydrostatic bearing constituting a guide mechanism in the X direction, 82.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Michihiro Takada 100 Fukuno-cho, Higashi-Tonami-gun, Toyama Prefecture F-term (reference) at Hiyama Toyama Toyama Plant (reference) 3C049 AA03 AA13 AA16 AA18 AB03 AB06 BB02 BB06 CA01 CB01

Claims (1)

[Claims] 1. A method in which a circular thin plate and a disk-shaped grindstone having a grinding surface on an outer periphery are relatively moved between the front and back surfaces of the circular thin plate while rotating the circular thin plate to grind an edge of the circular thin plate. An edge grinding apparatus for a circular thin plate, comprising only a guide mechanism configured to guide relative movement for performing the processing by a hydrostatic bearing.