JPH11254313A - Wafer's both face grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a wafer with a smooth surface by one-way deflection angle motion of a grinding face of a surface plate. SOLUTION: This device comprises a fixed lapping mechanism equipped with a rotary ring-shaped surface plate 13 at a tip of a fixed rotary shaft 11 having a through hole to feed abrasive slurry, and a movable lapping mechanism equipped with a rotary ring-shaped surface plate 23 at a tip of a movable rotary shaft 21 having a through hole to feed abrasive slurry. The movable rotary shaft 21 is revolvably supported by a deflection angle bearing 40 furnished with a deflection angle shaft 41 that extends in the direction parallel to a wafer 1's face. The fixed rotary shaft 11 is revolvably supported by a rotary bearing 50 that regulates movement in the directions of its longitudinal and transverse axes. Accordingly, since the rotary ring-shaped surface plate 23 is not deflected in the circumferential direction of the wafer 1, a recess portion corresponding to an outline thereof can be prevented from being imprinted onto the wafer 1 as a track.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided lapping method and apparatus for lapping a wafer cut from an ingot to produce a wafer having excellent surface properties.

[0002]

2. Description of the Related Art Wafers obtained by slicing ingots have variations in thickness, flatness, smoothness, and the like.
Wafers are commercialized through processes such as lapping, polishing, and finish polishing in order to remove variations and bring the surface into a state suitable for fabrication of semiconductor devices. In typical lapping and surface polishing, a method is adopted in which multiple wafers held by a carrier are placed on a lower platen, the wafer is sandwiched between the upper and lower platens, and both sides of the wafer are processed simultaneously. Have been. In this method, the wafer is processed while revolving and rotating around a sun gear located at the center of the lower platen, so that a uniform surface finish can be obtained.
However, as the diameter of the wafer to be processed increases, an extremely large-scale apparatus is required, and the burden on equipment and the burden on maintenance increase. Further, it is necessary to make the thicknesses of the wafers to be processed uniform, but only the average control can be performed because the quality of the plurality of wafers is different.

On the other hand, considering the number of semiconductor chips cut out from one wafer, it can be said that a wafer having a larger diameter is more advantageous in terms of productivity. Therefore, the present inventors have developed an apparatus capable of processing a large-diameter wafer without increasing the size of the equipment, and have filed an application as Japanese Patent Application No. Hei 9-180881. In the apparatus proposed in the prior application, as shown in FIG. 1, the reference side wrapping mechanism 10 and the moving side wrapping mechanism 20 are opposed to each other in the horizontal or vertical direction, and the wafer 1 to be wrapped is It is located between.
The reference side lap mechanism 10 has a disk 12 attached to an end of a reference rotation shaft 11, and a ring-shaped surface plate 13 fixed to the disk 12. The ring-shaped surface plate 13 rotates in the direction of arrow a by the power transmitted to the reference rotation shaft 11. The moving side lap mechanism 20 attaches a disk 22 to an end of a moving rotary shaft 21,
A ring-shaped surface plate 23 is fixed to the disk 22. The ring-shaped surface plate 23 has the same area as the ring surface surface plate 13 on the reference side, and rotates in the direction of the arrow b by the power transmitted to the moving rotary shaft 21.

By reversing the rotation direction of the ring-shaped bases 13 and 23, the forces applied to the bases 13 and 23 are made equal, and the same frictional force is generated on both surfaces of the wafer 1. Further, the rotational torque applied to the wafer 1 is offset between the front and back of the wafer 1, and as a result, the processing surface 1 of the
At 4 and 24, the wafer 1 is held under pressure. Machining surface 14,
24 can be appropriately coated as needed. For example, the processing surface 14,
24 can also be used for mirror polishing. The ring-shaped surface plate 23 of the moving-side lap mechanism 20 is movable in the direction of arrow c by a pressure mechanism (not shown). As a result, the processed surface is moved in the direction of arrow c in accordance with the wear, and the pressure applied to the wafer 1 is kept constant regardless of the amount of movement. The wafer 1 is rotated in the direction of arrow d by the drive rollers 31, 31,... Of the wafer rotation support mechanism 30 arranged on both the front and back surfaces.

The attitude of the rotating wafer 1 is stabilized by a guide roller 32 which rotates in contact with the edge of the wafer 1. As a result, the wafer 1 is pressed against the ring-shaped surface plates 13 and 23 in a predetermined positional relationship, and the wafer 1 is wrapped on the processing surfaces 14 and 24 under the set conditions. The reference rotation axis 11
And through holes 16, 26 formed in the moving rotary shaft 21
Is supplied through the cavities 15, 25 and used for surface processing such as lapping and polishing. The abrasive suspension A is discharged to the outside together with the processing waste generated by the surface processing from the grooves (not shown) provided on the ring-shaped surface plates 13 and 23 and the gap between the ring-shaped surface plates 13 and 23 and the wafer 1. Is done.

[0006]

The lapping apparatus shown in FIG. 1 processes the wafer 1 by using the ring-shaped surface plates 13 and 23 having a diameter substantially equal to the half of the diameter of the wafer 1. Therefore, the lapping apparatus shown in FIG. As compared with the conventional lapping apparatus, the size of the equipment can be greatly suppressed without requiring the large surface plates 13 and 23 for the one. Also,
Since the wafer 1 is processed one by one, it is not necessary to make the thicknesses of the wafers uniform in the conventional method of processing a plurality of wafers at the same time, and it is possible to perform control according to the condition of each individual wafer. The present invention is a further improvement of the lapping device proposed in the prior application, and allows the processing surface of the surface plate to be deflected in one direction, so that the processing surface of the surface plate is always fitted to the wafer surface, An object of the present invention is to remove a saw mark and irregular minute undulations on a wafer surface and to manufacture a wafer having a smooth surface.

[0007]

In order to achieve the object, a double-sided single-wafer processing apparatus of the present invention has a wafer radius at a tip of a reference rotating shaft having a through-hole for supplying an abrasive suspension slurry. The reference side lap mechanism with a ring-shaped surface plate having an outer diameter almost equal to the above, and the same shape as the reference-side ring-shaped surface plate at the tip of the moving rotary shaft having a through hole for supplying the abrasive suspension slurry A movable side lap mechanism with a ring-shaped surface plate, a movable bearing that rotatably supports the movable rotary shaft, and a deflected bearing with a deflected axis extending in a direction parallel to the wafer surface, and a reference rotary shaft rotatable. And a rotating bearing to support the
The ring-shaped surface plate is pressed against both surfaces in a range from the center to the edge of the wafer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A lapping apparatus according to the present invention is the same as the apparatus shown in FIG. 1 except that the movable platen 23 can swing, so that FIG. 1 will be appropriately referred to in the following description. . In the single-wafer processing apparatus shown in FIG.
The wafer 1 larger than 23 rotates. In order to press the polished surface against the wafer 1 with uniform pressure under these conditions,
It is necessary to attach the ring-shaped surface plate 23 on the moving side via a universal joint. However, in a universal joint employing a ball joint, the ring-shaped surface plate 23 can swing in any direction, and the contact of the ring-shaped surface plate 23 tends to adversely affect the surface shape of the wafer 1. Therefore, in the present invention,
As shown in FIG. 2, the movable rotary shaft 21 on the movable side is supported by the deflected bearing 40 so as to be able to be deflected, and the movable-side ring-shaped surface plate 23 is arranged to face the wafer 1. The deflection bearing 40 has a deflection shaft 41 extending in a direction perpendicular to the plane of FIG. The tilt of the moving rotary shaft 21 in the direction orthogonal to the paper surface is restricted by the declination axis 41, and the direction of the rotation is changed only in the radial direction of the wafer 1 (the direction parallel to the paper surface indicated by the arrow) about the deflected axis 41. The fixed-side reference rotation shaft 11 is supported by a normal rotation bearing 50, and maintains the reference-side ring-shaped surface plate 13 in a predetermined positional relationship with the wafer 1.

The direction in which the inclination is regulated by the deflection axis 41 is the direction in which the processing surface 24 of the ring-shaped surface plate 23 rubs against the surface of the wafer 1. Therefore, the ring-shaped surface plate 23
It does not swing in the left-right direction (the direction perpendicular to the paper surface in FIG. 2) due to the frictional force, and can be deviated in a direction intersecting a straight line on the radius of the wafer 1 at a portion in contact with the wafer 1. In the drawings, the thickness fluctuation of the wafer 1 is exaggerated in order to clarify the operation and effect of the present invention. For this reason, the lower sides of the ring-shaped bases 13 and 23 are drawn longer than the upper sides, but actually have the same axial length. Ring surface plate 23
In the method, the processing surface 24 is secured in a state where the deflection due to the friction in the circumferential direction of the rotation of the wafer 1 is prevented and the wafer 1 is fitted to the surface of the wafer 1. As a result, the wafer 1 is not partially subjected to large processing, and is processed into a convex, concave, or flat plane curved with a uniform curvature from the center to the edge as shown in FIG. The angle θ in FIG. 2 indicates a tilt angle when the moving-side rotation shaft 21 is tilted so that the polished surface follows the surface shape of the wafer 1.

The effect of the regulation of the swing of the ring-shaped surface plate 23 due to the friction in the circumferential direction of the wafer 1 becomes clear even in comparison with the following example using a normal universal joint. That is, as shown in FIG. 4, when the movable side ring-shaped surface plate 23 is supported by a typical ball joint 49 as a joint that supports the member so as to be able to swing, the ring-shaped surface plate 23
Can swing in any direction. However, when processing the wafer 1, the ring-shaped platen 23 rotates with the processing surface 24 rubbing against the surface of the wafer 1. The ring-shaped surface plate 23 swings in a circumferential direction (a direction perpendicular to the paper surface in FIG. 4) due to a frictional force generated between the processing surface 24 and the wafer 1, and the pressure on one side of the ring-shaped surface plate 23 is reduced. Increases and the pressure on the opposite side decreases. As a result, the processing of the wafer 1 progresses quickly at an intermediate portion of the radius of the wafer 1. On the surface of the wafer 1 thus processed,
As shown in FIG. 5, a depression corresponding to the arc-shaped outer peripheral shape of the ring-shaped surface plate 23 is formed as a track. On the other hand, in the ring-shaped surface plate 23 according to the present invention, since the contact in the circumferential direction of the wafer 1 is regulated, the outer peripheral shape is not transferred to the surface of the processed wafer 1. Also,
Even if the relative speed with respect to the wafer 1 changes, the load distribution does not change, so that the flatness can be controlled during the processing and the wafer having the target shape can be processed accurately.

[0011]

As described above, in the single-wafer processing apparatus according to the present invention, the processing surface of the movable side ring-shaped surface plate is crossed in a direction intersecting a straight line in the radial direction of the wafer to be processed. It is made swingable and restricts the processing surface from oscillating in the circumferential direction of the wafer. Therefore, the ring-shaped surface plate does not swing in the circumferential direction of the wafer due to friction between the wafer surface and the processing surface, and the outer peripheral shape of the ring-shaped surface plate is not transferred to the wafer surface as a track. Therefore,
The surface-processed wafer becomes a high-quality product having a convex, concave, or flat surface curved with a uniform curvature from the center to the edge.

[Brief description of the drawings]

FIG. 1 shows a single-wafer processing apparatus for double-sided wafers proposed by the present inventors.

FIG. 2 shows a state in which a moving-side ring-shaped surface plate supported by a deflection bearing and a reference-side ring-shaped surface plate supported by a rotary bearing are in contact with both surfaces of a wafer according to the present invention.

FIG. 3 is a sectional view of a wafer surface-processed by a single-wafer processing apparatus according to the present invention.

FIG. 4 shows a state in which a moving side ring-shaped surface plate supported by a ball joint and a reference side ring-shaped surface plate supported by a rotary bearing are in contact with both surfaces of a wafer for comparison.

FIG. 5 is a sectional view of a wafer surface-processed by a single-wafer processing apparatus incorporating a ball joint.

[Explanation of symbols]

1: Wafer 10: Reference side lap mechanism 20: Moving side lap mechanism
11: Reference rotation axis 21: Moving rotation axis 12, 22: Disk 13,2
3: ring-shaped surface plate 14, 24: machined surface 15, 25: cavity 16,
26: Through-hole 40: Deflection bearing on the moving side 41: Deflection axis 49:
Ball joint 50: Reference side rotating bearing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuji Osaka 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyota Machine Works Co., Ltd. (72) Inventor Hiroshi Ishigure 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyoda Machine Incorporated (72) Inventor Yutaka Inada 1-1-1, Asahi-machi, Kariya-shi, Aichi Prefecture Inside Toyota Machine Works Co., Ltd. (72) Inventor Hideki Iwai 1-1-1, Asahi-machi, Kariya City, Aichi Prefecture Toyoda Machine Works Co., Ltd.

Claims (1)

[Claims] A reference-side lap mechanism having a ring-shaped surface plate having an outer diameter substantially equal to the radius of a wafer provided at a tip of a reference rotation shaft having a through-hole for supplying an abrasive suspension slurry; A moving-side lap mechanism in which a ring-shaped surface plate having the same shape as the reference-side ring-shaped surface plate is provided at the tip of a moving rotation shaft having a through-hole for supplying the particle suspension slurry, and the moving rotation shaft can be rotated. It supports and has a deflection bearing with a deflection axis extending in a direction parallel to the surface of the wafer, and a rotation bearing that rotatably supports a reference rotation axis, and has both surfaces in a range from the center to the edge of the wafer. A double-sided single-wafer processing device for wafers against which a ring-shaped surface plate is pressed.