JPH10249718A - Sheet lapping method using ring surface plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly lap a wafer at both sides under stable conditions by using the frictional force of ring surface plate for the self-rotation of a wafer to reduce load on a wafer rotation supporting mechanism. SOLUTION: Ring surface plate 13, 23 with lapping faces 14, 24 having outer diameters almost equal to the radius of a disc work W are opposed to the both sides of the work W and thrusted thereto to rotate the work W with a driving roller 31 contacting the edge of the work W, and the ring surface plate 13, 23 are reversely rotated at different rotating speeds to grant rotating torque resulting from a rotting speed difference to the work W for lapping the work W at both sides while supplying abrasive grain suspended slurry A to the work W via the cavities of the ring surface plate 13, 23. The ring surface plate 13, 23 may be rotated in the same direction at the same or different rotating speed(s). As rotating torque is given to the work W by the ring surface plate 13, 23, the load of the driving roller 31 is less required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of uniformly lapping a single wafer while applying a rotation force to a wafer by friction with a ring surface plate.

[0002]

2. Description of the Related Art Wafers obtained by slicing ingots vary in thickness, flatness, smoothness, and the like. Therefore, these variations are removed by lapping, and the product wafer is manufactured by polishing, mirror polishing, and finish polishing. Conventionally, an apparatus having a facility configuration shown in FIG. 1 has been frequently used for lapping a wafer on both sides. This lapping device includes a lower platen 1, an upper platen 2, a sun gear 3, and an internal gear 4, each of which is rotated by a dedicated drive motor 5, 5,. The wafer to be wrapped is accommodated in a carrier 7 as a plurality of works 6 as shown in FIG. The carrier 7 is arranged at predetermined intervals on the lower stool 1 by meshing teeth formed on the outer periphery with the sun gear 3 and the internal gear 4. And the lifting device 8
Then, the upper platen 2 is lowered, and the carrier 7 is sandwiched between the lower platen 1 and the upper platen 2. When the lower platen 1, upper platen 2, sun gear 3, and internal gear 4 are rotated in this state,
Carrier 7 revolves and rotates, lower surface plate 1, upper surface plate 2
Is rubbed and wrapped. When a plurality of wafers 7 are wrapped at the same time in this manner, the parallel balance of the platens 1 and 2 and the load pressure balance by the lap driving action are achieved, and uniform lapping can be performed.

[0003]

Since a large number of chips are required with the spread of semiconductor devices, large-diameter wafers have been desired. When wrapping a large-diameter wafer with an apparatus having the equipment configuration shown in FIGS. 1 and 2, a carrier having a size corresponding to the diameter of the wafer is required, and the equipment itself becomes large. As the size increases, the processing accuracy for the lower surface plate, upper surface plate, sun gear, internal gear, and the like becomes severe, and as a result, equipment costs increase. Therefore, the present inventors have proposed a single wafer lapping apparatus suitable for a large-diameter wafer in Japanese Patent Application No. Hei 8-205196. In this lapping device, a large-diameter wafer is sandwiched between two ring-shaped platens, and the ring-shaped platen is rotated while feeding the abrasive suspension slurry into the cavity of the ring-shaped platen. Both sides are wrapped. With this method, it is only necessary to use a ring-shaped surface plate corresponding to the diameter of the wafer to be processed, and there is no need to increase the size of the apparatus itself. The present invention is a further improvement of the previously proposed single-wafer wrapping apparatus, and reduces the load on the wafer rotation support mechanism by utilizing the frictional force with the ring-shaped platen for the rotation of the wafer, thereby stabilizing the wafer. The purpose is to lap the wafer uniformly on both sides under the conditions.

[0004]

In order to achieve the object, a single-wafer lapping method according to the present invention has a ring-shaped surface plate having a lap surface having an outer diameter substantially equal to the radius of a disk-shaped work opposed to both surfaces of the work. To press and rotate the work with a drive roller that abuts on the edge of the work, and to apply a rotational torque to the work due to a difference in rotation speed.
The method is characterized in that the ring-shaped surface plate is rotated in the opposite direction at different rotation speeds, and both surfaces of the work are wrapped while supplying the abrasive suspension slurry to the work through the cavity of the ring-shaped surface plate. The ring-shaped platen may be rotated in the same direction at the same or different rotation speed.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A single-wafer wrapping device according to the present invention comprises:
As shown in FIG. 3, the reference side wrap mechanism 10 and the moving side wrap mechanism 20 face each other in the horizontal direction or the vertical direction, and the work W to be wrapped is located between the two wrap mechanisms 10 and 20. The reference side lap mechanism 10 includes a reference shaft 11
A flexible disk 12 is attached to the end of the disk, and a ring-shaped surface plate 13 is fixed to the disk 12. Ring-shaped surface plate 13
Rotates in the direction of arrow a by the power transmitted to the reference shaft 11. The moving side lap mechanism 20 has a flexible disk 22 attached to an end of a moving shaft 21, and a ring-shaped surface plate 23 fixed to the disk 22. The ring-shaped platen 23 has the same area as the ring-shaped platen 13 on the moving side, and
1 is rotated in the direction of arrow b by the power transmitted to 1.

[0006] By reversing the rotation direction of the ring-shaped bases 13 and 23, the forces applied to the bases 13 and 23 become substantially equal, and substantially the same frictional force is generated on both surfaces of the work W. At this time, if a slight difference is made in the rotation speed between the ring-shaped surface plates 13 and 23, the work W
Is given a rotational torque. The direction of the rotation torque matches the rotation direction of the ring-shaped surface plate 13 or 23 having a high rotation speed. Alternatively, when the rotation directions of the ring-shaped surface plates 13 and 23 are made to coincide with each other, the forcible rotation torque is applied to the ring-shaped surface plate 1.
3 and 23 are provided to the work W. In any case, the workpiece W is placed on the lapping surfaces 14, 2 of the ring-shaped surface plates 13, 23.
The pressure is held at 4. 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). Thereby, the lap surface is moved in the direction of the arrow c in accordance with the wear, and the pressing force applied to the work W is kept constant by adjusting the amount of movement.

The drive rollers 31, 31,... Of the wafer rotation support mechanism 30 arranged on both front and back sides of the work W
The rotation in the direction is given to the workpiece W. The posture of the rotating workpiece W is stabilized by the guide roller 32 rotating in contact with the peripheral edge of the workpiece W. As a result, the work W is moved to the ring-shaped bases 13 and 23 in a preset positional relationship.
, And the work W is wrapped under constant conditions. In the prior application / Japanese Patent Application No. 8-205196, the work W is rotated exclusively by the drive rollers 31, 31,.
The drive roller 31 comes into contact with both sides of the work W from both sides 31 _l and 31 _r . The drive rollers 31 _l and 31 _r on both sides are
The configuration is such that only the rotational torque is applied to the surface of the work W, and the work W is arranged and rotated in a positional relationship where other forces are offset.
In this method, the work W can be ensured smoothly by adjusting the rotation condition of the platen surface. However, since the surface of the work W is rotated by the driving rollers 31, 31... Which rub against each other, when the load is large, the work W may slip, and a friction mark may be generated on the surface of the work W. In addition, since the torque is applied to the vicinity of the edge of the work W, there is a possibility that the work W may have a defect such as deformation, and the structure of the rotation support mechanism 30 tends to be complicated in order to obtain a large torque.

Therefore, in the present invention, a rotational torque is applied to the workpiece W by making a difference between the rotation speeds of the ring-shaped bases 13 and 23 rotating in opposite directions, or the ring-shaped bases 13 and 23 are moved in the same direction. , A torque for forcibly rotating the work W is obtained. Therefore, the load on the rotation support mechanism 30 for rotating the work W is reduced, and the rotation support mechanism 30 having a simple structure can be adopted. In addition, since the rotating torque is given by the ring-shaped surface plates 13 and 23 that come into contact with the surface of the central portion of the work W, the work W rotates in a stable posture. Ring-shaped surface plates 13, 23
In order to make the pressure uniform over the entire area of the lap surfaces 14 and 24, it is preferable to have an outer diameter substantially corresponding to the radius of the work W. The wrap surfaces 14 and 24 have a narrow shape, and the cavities 15 and 24 are provided inside the wrap surfaces 14 and 24.
25 are formed. Usually, the rotational peripheral speed increases in proportion to the radius toward the outer peripheral side, and the removal processing of the surface defect layer by lapping is proportional to the pressure and the peripheral speed. Therefore, wear is small in a portion where the peripheral speed is low, and flatness is impaired.
In this regard, in the present invention, since the wrap surfaces 14 and 24 having a small width are formed, the rotational peripheral speed is approximated, and the lapping action is uniformed on both the inside and the outside.

[0009] Grooves (not shown) of a predetermined pattern are engraved on the lap surfaces 14 and 24, and abrasive suspension slurry is formed through through holes 17 and 27 formed in the reference shaft 11 and the moving shaft 21. A is sent into the cavities 15, 25, and the work W
Used for wrapping. The abrasive suspension A is discharged to the outside through the grooves together with the processing waste generated by the lapping. Abrasive suspension slurry and processing waste are collected on a ring-shaped surface plate 1
The ring-shaped surface plates 13, 23 are formed by centrifugal force generated by the rotation of
Is discharged to the outside via a radial groove (not shown) formed in the fin. The wrap surfaces 14 and 24 can be appropriately coated as needed. For example,
The wrap surfaces 14 and 24 to which the cloth has been attached can also be used for mirror polishing. The lap finish of the work W is adjusted according to the type and particle size of the abrasive used.

[0010]

【Example】

Example 1: A work W having a diameter of 200 mm has an outer diameter of 10 on both sides.
The ring-shaped surface plates 13 and 23 having a diameter of 3 mm and an inner diameter of 83 mm were opposed to each other and pressed with a pressing force of 200 g / cm ² . As the abrasive grains, those obtained by suspending Al ₂ O ₃ having an average particle diameter of 13 μm in water at a rate of 400 g / l were used. While the abrasive suspension A is sent from the through holes 17 and 27 into the cavities 15 and 25 of the ring-shaped platen 13 and 23 at a flow rate of 0.005 m ³ / min, the ring-shaped platen 13 is moved at 500 rpm in the direction a.
The other ring-shaped surface plate 23 was rotated in the direction b at a speed of 450 rpm. The work W was rotated in the direction d at 20 rpm by adding the rotation torque resulting from the difference in rotation speed between the ring-shaped surface plates 13 and 23 to the rotation force by the rotation support mechanism 30. During the lapping, the pressing force of the ring-shaped surface plates 13 and 23 against the work W was detected, and the pressing force was adjusted according to a predetermined program sequence. Rotation support mechanism 3
0, the driving force applied to the work W is
50 compared to the case where there is no difference between the rotation speeds of 3, 23
% Could be reduced. After the lapping was continued for 3 minutes, the work W was taken out of the wrapping device and both surfaces of the work W were examined. As a result, the material TTV 30 μm was
It could be improved to 1 μm. Also, saw marks existing on the material wafer surface were completely removed.

Example 2 A work W was wrapped on both sides under the same conditions as in Example 1 except that the ring-shaped surface plates 13 and 23 were rotated in the same direction at a speed of 200 rpm and a pressing force of 50 g / cm ² . In this case, since a large rotational torque is applied to the work W by the ring-shaped bases 13 and 23 rotating in the same direction, the driving force applied to the work W by the rotation support mechanism 30 can be greatly reduced. In addition, the wrapped work W had a good surface as in Example 1.

[0012]

As described above, in the present invention, by adjusting the rotation speed or the rotating direction of the ring-shaped surface plate facing the work, the rotational torque is applied to the work by the rotation of the ring-shaped surface plate. Have given. Therefore, the load on the rotation support mechanism for rotating the work is reduced, and the work rotates in a stable posture, so that high-precision lapping can be performed and a high-quality wafer can be obtained.

[Brief description of the drawings]

FIG. 1 is an outline of a conventional double-sided lapping apparatus.

FIG. 2 A carrier arranged on a lower platen of a conventional double-sided lapping device

FIG. 3 is a sheet wrapping apparatus used in the present invention.

[Explanation of symbols]

10: Reference side wrap mechanism 20: Moving side wrap mechanism
11: Reference axis 21: Moving axis 12, 22: Flexible disk 13, 23: Ring-shaped surface plate 14, 24: Lapping surface 15, 25: Cavity 1
7, 27: through hole 30: wafer rotation support mechanism 31: drive roller
32: Guide roller W: Work A: Abrasive suspension slurry

Claims (2)

[Claims] 1. A ring-shaped surface plate having a wrap surface having an outer diameter substantially equal to the radius of a disk-shaped work is pressed against both surfaces of the work, and the work is rotated by a drive roller contacting an edge portion of the work. The ring-shaped platen is rotated in the opposite direction at a different rotation speed so that the rotation torque caused by the rotation speed difference is applied to the work, and the abrasive suspended slurry is worked through the cavity of the ring-shaped platen. A single wafer lapping method using a ring-shaped platen, wherein both sides of a work are wrapped while being supplied to a workpiece. 2. A ring-shaped surface plate having a lap surface having an outer diameter substantially equal to the radius of the disk-shaped work is pressed against both surfaces of the work, and the work is rotated by a driving roller contacting an edge portion of the work. By rotating the ring-shaped surface plate in the same direction at the same or different rotation speed so that the rotation torque caused by the rotation speed difference is applied to the work, the abrasive suspension slurry is passed through the cavity of the ring-shaped surface plate. Wrapping both sides of a work while supplying the work to the work.