Wafer chuck
The influence of the slurry generated when polishing an orientation notch and the like is minimized. The holding members 10, 20 for holding the outer periphery of the wafer W and the driving mechanism 30 for driving the holding members 10, 20 all together in the closing direction are integrally combined.
1. Field of the Invention
The present invention relates to wafer chucks suitably used particularly when polishing an orientation notch and the like of the outer periphery part of the semiconductor wafer.
2. Description of the Related Art
The semiconductor wafer (hereinafter referred to simply as a wafer) has a V-shaped or a circular arc shaped orientation notch formed on the outer periphery. It is to be noted that the notch may be a linear orientation flat.
When forming the orientation notch in the wafer, the polishing pad contacts the outer periphery of the wafer along a predetermined trajectory so as to create a predetermined angle, which wafer is normally attracted to and fixed to the vacuum chuck that uses vacuum, (e.g., Japanese Laid-Open Patent Publication No. 2-180554 and Japanese Laid-Open Patent Publication No. 2002-28840.). That is, a concentric or a radial groove communicating to the vacuum source is formed on the upper surface of the vacuum chuck, and the wafer is attracted and held at the upper surface of the vacuum chuck by operating the vacuum pump.
On the other hand, after grinding, the orientation notch has the internal part polished to realize an accurate positioning of the wafer. Thus, a similar vacuum chuck is also normally used in polishing.
SUMMARY OF THE INVENTIONAccording to the conventional technique, when slurry (mixture of fluid polishing agent containing abrasive grain and powder polishing waste of the wafer) enters the lower surface side (attraction surface side) of the wafer, microscopic defects are unavoidably created at the wafer since the vacuum chuck attracts the wafer using vacuum.
The present invention, in view of the problem of the conventional art, aims to provide a wafer chuck that suppresses the influence of the slurry produced when polishing the orientation notch and the like of the outer periphery part to minimum by arranging holding members for mechanically holding the outer periphery part of the wafer.
The configuration of the present invention for achieving the above aim includes a plurality of holding members for pushing the outer periphery of the wafer in the radial direction and holding the wafer, and a driving mechanism for driving the holding members all together in the closing direction. It is to be noted that “closing direction” refers to the direction of moving each holding member forward towards the center of the wafer.
Each holding member is configured so as to hold the wafer by way of an elastic member.
Further, a V-shaped groove for sandwiching the outer peripheral part of the wafer in a snapping manner is formed in the elastic member, which V-shaped groove is further shaped into a circular arc shape so as to lie along the circumferential direction with respect to the outer peripheral edge of the wafer.
Moreover, the elastic member further includes a guide groove having an apex angle greater than the apex angle of the V-shaped groove on the opening direction side of the V-shaped groove.
The elastic member is configured from fluorocarbon resin or fluorocarbon rubber molded article.
When the holding members are arranged on both sides in the radial direction of the wafer with the wafer in between, a cylinder arranged in the radial direction of the wafer and connected to one of the holding members, and an interlocking mechanism for operating the other holding member in conjunction with the operation of the former holding member are arranged as the driving mechanism.
Further, as the driving mechanism, feed screws arranged in the radial direction of the wafer and having screw parts in the direction opposite to each other in order to screw each screw part to the holding member, and a motor for turning the feed screw may be arranged.
When a machining tool forward/backward path that approaches the wafer at a position orthogonal to the wafer and machines the outer peripheral edge of the wafer is formed in one of the holding members arranged on both sides in the radial direction of the wafer, the holding member is capable of holding the part near the machining portion of the wafer.
The present invention is suitable for polishing a V-notch or Orientation flat for defining the orientation of the wafer.
According to the configuration of the present invention, the holding member is driving all together in the closing direction towards the center of the wafer by way of the driving mechanism to push the outer periphery of the wafer in the radial direction and mechanically hold the wafer. That is, in such state, since the wafer is held with both surfaces floating in the air, even if slurry produced when polishing the orientation notch or orientation flat of the outer peripheral part is attached, the slurry can be easily removed in the post-process of washing and the like, and thus does not cause defects on the wafer. When a plurality of holding members are driven parallel to the wafer all together by the same stroke towards the center of the wafer by way of the driving mechanism, each holding member applies the same pushing force parallel to both surfaces of the wafer towards the central part of the wafer in the thickness direction, thereby preventing localized distortion or curve of the wafer.
Each holding member holds the wafer by way of the elastic member, and thus the pushing force is suitably dispersed and applied to the outer periphery of the wafer to minimize the localized distortion produced in the wafer. Further, the V-shaped groove formed in the elastic member sandwiches the outer peripheral part of wafer in a snapping manner and holds the wafer in a further stabilized manner. The guide groove formed in the opening direction of the V-shaped groove accurately guides the outer peripheral part of the wafer and allows the same to enter therein when the holding members are driven towards the center of the wafer.
The chuck according to the present invention does not require a vacuum chuck for fixing the wafer, and thus is configured to be light as a whole, and the V-notch or Orientation flat is particularly suitable in an application of polishing the notch. When polishing the internal part of the V-notch or Orientation flat, the wafer tends to perform a complex and precise movement by way of the chuck, and thus if the chuck is light weight, the driving mechanism for moving the chuck can be simplified.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
The embodiments of the present invention will now be described with reference to the drawings.
The wafer chuck is made by integrally assembling a pair of holding members 10, 20 and a driving mechanism 30 (
One of the holding members 10 is formed with a pair of left and right parallel fingers 12, 12 projecting horizontally from a distal end of the common base 11. The distal end of each finger 12 is bent upwards, and an elastic member 14 is attached in an exchangeable manner to the upper surface of each finger 12 by way of a press plate 13. V-shaped grooves 14a that conforms to the outer peripheral part of the wafer W is formed at each elastic member 14, 14, and the V-shaped grooves 14a, 14a, opening in the horizontal direction, are continued in a circular arc shape so as to lie along the outer periphery of the wafer W.
The other holding member 20 is configured with the elastic member 22 attached in an exchangeable manner to the upper surface of the block shaped base 21. The elastic member 22 is fixed by way of the press plate 23 screw-fitted to the distal end face of the base 21, and a pair of left and right V-shaped grooves 22a, 22a are formed on the upper surface of the elastic member 22 so as to face the V-shaped grooves 14a, 14a of the holding member 10.
The V-shaped groove 14a of each elastic member 14 is formed with a cross section symmetrical in the up-and-down direction (
The holding members 10, 20 are each connected to the distal end of the rod 31 and the guide rod 32 projecting out from both ends of the driving mechanism 30 (
The racks 34, 34 connected to the holding members 10, 20 and a pinion 35 commonly engaging with the racks 34, 34 are built in the driving mechanism 30 to align the stroke of the holding members 10, 20 so as to be the same. The rack 34 and the pinion 35 function as an interlocking mechanism.
In
Further, the arrangement relationship between the racks 34, 34 and the cylinder 33, 33 is not particularly limited, and the racks 34, 34 may be arranged in any direction of above, below, left or right of the cylinders 33, 33. It is to be noted that in
An attachment bracket 42 is screw fitted to the left and right of the driving mechanism 30 by way of the spacer bracket 41 (
The wafer chuck mechanically holds the wafer W by way of the elastic members 14, 14, 22 by driving the holding members 10, 20 in the closing direction (direction of arrow K1, K1 of
The wafer W on the chuck contacts the outer periphery of the polishing pad G and the internal part of the orientation notch N of the wafer W is polished (
The driving mechanism 30 may have ball screw shafts 36, 36 that are reverse-rotatably driven by the motor M as the main member (
According to the above description, the wafer chuck polishes the orientation flat W3 of the wafer by being suitably relatively moved with respect to the polishing pad G (
It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
Claims
1. A wafer chuck comprising a plurality of holding members for pushing an outer periphery of a wafer in a radial direction and holding the wafer, and a driving mechanism for driving the holding members all together in a closing direction.
2. The wafer chuck as claimed in claim 1, wherein each holding member is configured so as to hold the wafer by way of an elastic member.
3. The wafer chuck as claimed in claim 2, wherein the elastic member is formed with a V-shaped groove for sandwiching the outer peripheral part of the wafer in a snapping manner.
4. The wafer chuck as claimed in claim 3, wherein the V-shaped groove of the elastic member is formed into a circular arc shape so as to lie along the circumferential direction of the outer peripheral edge of the wafer.
5. The wafer chuck as claimed in claim 3, wherein the elastic member further includes a guide groove having an apex angle greater than the apex angle of the V-shaped groove on an opening direction side of the V-shaped groove.
6. The wafer chuck as claimed in claim 2, wherein the elastic member is made of fluorocarbon resin or fluorocarbon rubber molded article.
7. The wafer chuck as claimed in claim 1, wherein the holding member is arranged on both sides in the radial direction of the wafer with the wafer sandwiched in between; and
- the driving mechanism includes cylinders arranged in the radial direction of the wafer and connected to one of the holding members, and an interlocking mechanism for operating the other holding member in conjunction with the operation of the former holding means.
8. The wafer chuck as claimed in claim 1, wherein the holding member is arranged on both sides in the radial direction of the wafer with the wafer sandwiched in between; and
- the driving mechanism, feed screws arranged in the radial direction of the wafer and having screw parts in the direction opposite to each other in order to screw each screw part to the holding member, and a motor for rotating the feed screw may be arranged.
9. The wafer chuck as claimed in claim 7, wherein a machining tool forward/backward path for approaching the wafer at a position orthogonal to the wafer and machining the outer peripheral edge of the wafer is formed on one of the holding members arranged on both sides in the radial direction of the wafer.
10. The wafer chuck as claimed in claim 1, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
11. The wafer chuck as claimed in claim 8, wherein a machining tool forward/backward path for approaching the wafer at a position orthogonal to the wafer and machining the outer peripheral edge of the wafer is formed on one of the holding members arranged on both sides in the radial direction of the wafer.
12. The wafer chuck as claimed in claim 2, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
13. The wafer chuck as claimed in claim 3, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
14. The wafer chuck as claimed in claim 4, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
15. The wafer chuck as claimed in claim 5, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
16. The wafer chuck as claimed in claim 6, being used for polishing the V-notch or Orientation flat for determining the orientation of the wafer.
Type: Application
Filed: Oct 4, 2005
Publication Date: Apr 20, 2006
Inventors: Takashi Yoshida (Gunma-gun), Shinichi Murakami (Hakusan-shi), Hiroyuki Itou (Hakusan-shi)
Application Number: 11/241,928
International Classification: B24B 47/00 (20060101);