Wafer pads for fixed-spindle floating-platen lapping

• US 8,647,172 B2
• Filed: 03/12/2012
• Issued: 02/11/2014
• Est. Priority Date: 03/12/2010
• Status: Expired due to Fees

• Current Assignee: Wayne O. Duescher
• Original Assignee: Wayne O. Duescher
• Inventors: Duescher, Wayne O.
• Primary Examiner(s): ROSE, ROBERT A
• Application Number:
  US13/417,485
• Publication Number:
  US 20120270478A1
• Time in Patent Office: 701 Days
• Field of Search: 451/5, 451/11, 451/28, 451/36, 451/37, 451/41, 451/59, 451/64, 451/259, 451/260, 451/270, 451/271, 451/280, 451/283, 451/285, 451/288, 451/287
• US Class Current: 451/11
• CPC Class Codes: B24B 37/107 in a rotary movement only, about an axis being stationary during lapping
• CPC Class Codes: B24B 37/245 Pads with fixed abrasives
• CPC Class Codes: B24B 37/26 characterised by the shape of the lapping pad surface, e.g. grooved
• CPC Class Codes: B24B 37/30 for single side lapping of plane surfaces
• CPC Class Codes: B24B 41/047 Grinding heads for working on plane surfaces
• CPC Class Codes: B24B 7/22 for grinding inorganic material, e.g. stone, ceramics, porcelain
• CPC Class Codes: B24B 7/228 for grinding thin, brittle parts, e.g. semiconductors, wafers grinding edges of thin, brittle parts B24B9/065

Abstract

Three rotary wafer abrasive lapping spindles having attached wafers are mounted on the flat surface of a granite lapping machine base. A flexible raised island abrasive disk is attached to the annular abrading surface of an abrading platen that is rotated at high speeds to flat lap, or polish, the exposed surfaces of the rotating wafers. Resilient wafer pads are used to minimize the effects of the abraded surfaces of the wafers not being precisely parallel to the platen abrading surface due to misalignment of the spindle tops. The resilient pads also compensate for two opposed flat surfaces of wafers not precisely parallel with each other. A mixture of the same types of chemicals that are used in the conventional CMP polishing of wafers with applied coolant water can be used with this abrasive lapping or polishing system to enhance abrading and to continually wash abrading debris from the wafers.

Claims

1. An at least three-point, fixed-spindle floating-platen abrading machine having resilient workpiece support pads comprising:

a) at least three rotary workpiece spindles having rotatable flat-surfaced spindle-tops, each of the rotary flat-surfaced spindle-tops having a respective rotary spindle-top axis of rotation at a center of a respective rotatable flat-surfaced rotary spindle-top for each respective rotary workpiece spindles;

b) the respective axis of rotation for each of the at least three workpiece rotary spindle-tops'"'"' is perpendicular to the respective rotary spindle-tops'"'"' flat surface;

c) an abrading machine base having a horizontal, nominally-flat top surface and a spindle-circle where the spindle-circle is coincident with the machine base nominally-flat top surface;

d) the at least three rotary workpiece spindles are located with near-equal spacing between the respective at least three rotary workpiece spindles and the respective at least three rotary spindle-tops'"'"' axes of rotation intersect the machine base spindle-circle and the respective at least three rotary workpiece spindles are mechanically attached to the machine base top surface;

e) the at least three workpiece rotary spindle-tops'"'"' flat surfaces are configured to be adjustably alignable to be co-planar with each other;

f) a floating, rotatable abrading platen having a flat annular abrading surface where the platen is supported by and rotationally driven about a platen rotation axis located at a rotational center of the platen by a spherical-action rotation device located at a rotational center of the platen, and the spherical-action rotation device restrains the platen in a radial direction relative to the platen axis of rotation, and the platen axis of rotation is concentric with the machine base spindle-circle;

g) the spherical-action rotation device is configured to cause spherical motion of the floating, rotatable platen about the rotational center of the floating, rotatable platen where the floating, rotatable platen abrading surface is nominally horizontal;

h) flexible abrasive disk components having annular bands of abrasive-coated flat surfaces and each flexible abrasive disk component is attached in flat conformal contact with a respective floating, rotatable platen abrading surface wherein the attached abrasive disk is concentric with the floating, rotatable platen abrading surface;

i) workpiece carriers having an impervious, compressible and resilient body having a thickness wherein each workpiece carrier'"'"'s compressible and resilient body has a top flat surface and a parallel opposed bottom flat surface, wherein each workpiece carrier'"'"'s body has a thickness between the carrier top flat surface and the carrier bottom flat surface;

j) wherein the workpiece carrier'"'"'s bottom flat surfaces are attached in full flat-surfaced contact with the flat surfaces of the respectable spindle-tops wherein the workpiece carrier'"'"'s top flat surfaces are compressible relative to the workpiece carrier'"'"'s opposed bottom flat surfaces and wherein the workpiece carrier'"'"'s top flat surfaces are resilient relative to the workpiece carrier'"'"'s opposed bottom flat surfaces;

k) equal-thickness workpieces having parallel opposed top and bottom flat surfaces are attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece carriers;

l) the floating rotatable abrading platen is vertically moveable to allow the abrasive surface of the abrasive disk that is attached to the floating rotatable platen abrading surface to contact the full top surfaces of the respective workpieces, wherein the respective workpiece carriers are compressed to provide uniform abrading pressure across the full top surfaces of the respective workpieces;

m) the at least three spindle-tops having attached workpieces are configured to be rotated about the respective spindle-tops'"'"' rotation axes, and the rotatable floating abrading platen having the attached flexible abrasive disk is configured to be rotated about the rotatable floating abrading platen cylindrical-rotation axis to single-side abrade the workpieces that are attached to the flat surfaces of the at least three spindle-tops while the moving abrasive surface of the flexible abrasive disk that is attached to the moving rotatable floating abrading platen flat annular abrading surface is in force-controlled abrading contact with the top surfaces of the workpieces that are attached to the respective at least three spindle-tops.

2. The apparatus of claim 1 wherein the machine base comprises a structural material selected from the group consisting of granite, epoxy-granite, and metal and wherein the machine base structural material is either a non-porous solid or is a solid material that is temperature controlled by a temperature-controlled fluid that circulates in fluid passageways internal to the machine base structural materials.

3. The apparatus of claim 1 wherein the at least three rotary workpiece spindles are air bearing rotary workpiece spindles.

4. The apparatus of claim 1 wherein each workpiece carrier'"'"'s compressible and resilient body is constructed from an open-celled polymer foam material wherein each workpiece carrier'"'"'s compressible and resilient body has a flexible impervious coating or is constructed from a impervious closed-celled polymer foam material.

5. The apparatus of claim 1 wherein each workpiece carrier top flat surface has a flat-surface size and a flat-surface shape and the respective workpiece carrier opposed bottom flat surface has a flat-surface size and a flat-surface shape, wherein the respective workpiece carriers'"'"' top flat-surface sizes and bottom flat-surface sizes are substantially equal and the respective workpiece carriers'"'"' top flat-surface shapes and bottom flat-surface shapes are substantially similar and each workpiece has a bottom flat-surface size and a bottom flat-surface shape, wherein the respective workpiece carriers'"'"' top flat-surface sizes are substantially equal to the respective workpiece bottom flat-surface sizes and the respective workpiece carriers'"'"' top flat-surface shapes are substantially similar to the shapes of the respective workpieces'"'"' bottom flat-surface.

6. The apparatus of claim 1 wherein workpieces are attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece carriers coated with an adhesive coating selected from the group consisting of an adhesive coating, a low-tack adhesive coating and a water film coating that creates surface tension workpiece adhesive-type attachment forces.

7. The apparatus of claim 1 wherein each workpiece carrier has a rigid workpiece mounting plate having parallel opposed top and bottom flat surfaces wherein the bottom flat surface of the rigid workpiece mounting plate is attached with full flat-surfaced contact with the top flat surface of the respective workpiece carrier and wherein equal-thickness workpieces are attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective rigid workpiece mounting plates having an adhesive coating selected from the group consisting of an adhesive coating, a low-tack adhesive coating, a wear-resistant coating and a water film coating that creates surface tension workpiece adhesive-type attachment forces.

8. The apparatus of claim 7 wherein each rigid workpiece mounting plate has a flat-surface size and a flat-surface shape and the respective rigid workpiece mounting plate opposed bottom flat surface has a flat-surface size and a flat-surface shape, wherein the respective rigid workpiece mounting plates'"'"' top flat-surface sizes and bottom flat-surface sizes are substantially equal and wherein the respective rigid workpiece mounting plates'"'"' top flat-surface shapes and bottom flat-surface shapes are substantially similar and each workpiece has a bottom flat-surface size and a bottom flat-surface shape, wherein the respective rigid workpiece mounting plates'"'"' top flat-surface sizes are substantially equal to the respective workpiece bottom flat-surface sizes and the respective rigid workpiece mounting plates'"'"' top flat-surface shapes are substantially similar to the shapes of the respective workpieces'"'"' bottom flat-surface.

9. The apparatus of claim 7 wherein each rigid workpiece mounting plate has internal fluid passageways that connect to a fluid valve located on the external surface of the workpiece mounting plate and connect to port holes that are located on the workpiece mounting plate top flat surface and wherein vacuum is applied at the fluid valve to the internal fluid passageways, wherein workpieces are attached by vacuum with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece mounting plate.

10. The apparatus of claim 8 wherein each rigid workpiece mounting plate has internal fluid passageways that connect to a fluid valve located on the external surface of the workpiece mounting plate and wherein the internal fluid passageways connect to port holes that are located on the workpiece mounting plate top flat surface and wherein pressurized air is applied at the fluid valve to the internal fluid passageways, wherein workpieces are separated by pressurized air from full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece mounting plate.

11. The apparatus of claim 1 wherein the workpiece carrier'"'"'s compressible and resilient body comprises a sealed air bag that expanded to a selected workpiece carrier body thickness by air and a seal securing the air in the workpiece carrier air bag.

12. The apparatus of claim 1 wherein the workpiece carrier'"'"'s compressible and resilient body is a sealed pleated air bags comprising:

a) annular bands of flexible polymer or metal material that are joined together at the peripheral edges of the individual annular bands to form flexible pleated annular peripheral walls of the workpiece carrier'"'"'s body;

b) circular disks of polymer or metal sheet material forming the workpiece carrier'"'"'s top flat surface and the workpiece carrier'"'"'s bottom flat surface;

c) wherein the pleated annular peripheral wall of the workpiece carrier'"'"'s body and the circular workpiece carrier'"'"'s top flat surface and the workpiece carrier'"'"'s bottom flat surface are joined together to form a sealed pleated workpiece carrier having a sealed interior;

d) wherein air introduced into the interior of the sealed pleated workpiece carrier inflates the workpiece carrier to provide a selected sealed pleated workpiece carrier thickness from the pleated workpiece carrier'"'"'s top flat surface and to the pleated workpiece carrier'"'"'s bottom flat surface;

e) wherein the pleated workpiece carrier has been sealed after being filled with air to retain the air that resides in the pleated workpiece carriers'"'"'sealed interior when the pleated workpiece carrier'"'"'s top flat surface is resiliently compressed relative to the pleated workpiece carrier'"'"'s opposed bottom flat surface.

13. A process of providing an at least three-point, fixed-spindle floating-platen abrading machine having resilient workpiece support pads comprising:

a) providing the machine having at least three rotary workpiece spindles having rotatable flat-surfaced spindle-tops, each of the rotary spindle-tops having a respective rotary spindle-top axis of rotation at the center of a respective rotatable flat-surfaced rotary spindle-top for each respective rotary workpiece spindles;

b) providing the respective axes of rotation for each of the at least three workpiece rotary spindle-tops'"'"' as perpendicular to respective rotary spindle-tops'"'"' flat surfaces;

c) providing the abrading machine base having a horizontal, nominally-flat top surface and a spindle-circle wherein the spindle-circle is coincident with the machine base nominally-flat top surface;

d) positioning the at least three rotary workpiece spindles in locations with near-equal spacing between the respective at least three of the rotary workpiece spindles wherein the respective at least three workpiece rotary spindle-tops'"'"' axes of rotation intersect the machine base spindle-circle and wherein the respective at least three rotary workpiece spindles are mechanically attached to the machine base top surface;

e) aligning the at least three workpiece spindles'"'"' rotary spindle-tops'"'"' flat surfaces to be co-planar with each other and locking the co-planar aligned at least three workpiece spindles in their co-planar aligned positions;

f) providing a floating, rotatable abrading platen having a flat annular abrading surface with the platen supported by and rotationally driven about a platen rotation axis located at a rotational center of the platen by a spherical-action rotation device located at a rotational center of the platen, the spherical-action rotation device restraining the platen in a radial direction relative to the platen axis of rotation and the platen axis of rotation is concentric with the machine base spindle-circle;

g) the spherical-action rotation device is configured to cause spherical motion of the floating, rotatable platen about the rotational center of the floating, rotatable platen where the floating, rotatable platen abrading surface is nominally horizontal;

h) providing flexible abrasive disk components having annular bands of abrasive coated flat surfaces wherein a flexible abrasive disk is attached in flat conformal contact with the platen abrading surface, the attached abrasive disk being concentric with the platen abrading surface;

i) providing workpiece carriers having an impervious, compressible and resilient body having a thickness wherein the workpiece carrier'"'"'s compressible and resilient body has a top flat surface and a parallel opposed bottom flat surface, wherein the workpiece carrier'"'"'s body thickness is between the carrier top flat surface and the carrier bottom flat surface;

j) providing the workpiece carrier'"'"'s bottom flat surfaces attached in full flat-surfaced contact with the flat surfaces of the respectable spindle-tops, wherein the workpiece carrier'"'"'s top flat surfaces are compressible relative to the workpiece carrier'"'"'s opposed bottom flat surfaces and the workpiece carrier'"'"'s top flat surfaces are resilient relative to the workpiece carrier'"'"'s opposed bottom flat surfaces;

k) providing equal-thickness workpieces having parallel opposed top and bottom flat surfaces attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece carriers;

l) moving the floating rotatable abrading platen vertically to allow the abrasive surface of the abrasive disk that is attached to the floating rotatable platen abrading surface to contact the full top surfaces of the respective workpieces, wherein the respective workpiece carriers are compressed to provide uniform abrading pressure across the full top surfaces of the respective workpieces;

m) rotating the at least three spindle-tops having attached workpieces about the respective spindle-tops'"'"' rotation axes, and rotating floating abrading platen having the attached flexible abrasive disk about the rotatable floating abrading platen cylindrical-rotation axis to single-side abrade the workpieces that are attached to the flat surfaces of the at least three spindle-tops while the moving abrasive surface of the flexible abrasive disk that is attached to the moving rotatable floating abrading platen flat annular abrading surface is in force-controlled abrading contact with the top surfaces of the workpieces that are attached to the respective at least three spindle-tops.

14. The process of claim 13 wherein the at least three rotary workpiece spindles are air bearing rotary workpiece spindles.

15. The process of claim 13 wherein each workpiece carrier'"'"'s compressible and resilient body is constructed from an open-celled polymer foam material wherein each workpiece carrier'"'"'s compressible and resilient body has a flexible impervious coating or is constructed from an impervious closed-celled polymer foam material.

16. The process of claim 13 wherein each workpiece carrier top flat surface has a flat-surface size and a flat-surface shape and the respective workpiece carrier opposed bottom flat surface has a flat-surface size and a flat-surface shape wherein the respective workpiece carriers'"'"' top flat-surface sizes and bottom flat-surface sizes are substantially equal and wherein the respective workpiece carriers'"'"' top flat-surface shapes and bottom flat-surface shapes are substantially similar and wherein each workpiece has a bottom flat-surface size and a bottom flat-surface shape, the respective workpiece carriers'"'"' top flat-surface sizes are substantially equal to the respective workpiece bottom flat-surface sizes and the respective workpiece carriers'"'"' top flat-surface shapes are substantially similar to the shapes of the respective workpieces'"'"' bottom flat-surface.

17. The process of claim 13 wherein workpieces are attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece carriers coated with an adhesive coating selected from the group consisting of an adhesive coating, a low-tack adhesive coating and a water film coating that creates surface tension workpiece adhesive-type attachment forces.

18. The process of claim 13 wherein each workpiece carrier has a rigid workpiece mounting plate having parallel opposed top and bottom flat surfaces where the bottom surface of the workpiece mounting plate is attached with full flat-surfaced contact of the respective workpiece mounting plate bottom surface with the top flat surface of the respective workpiece carrier and wherein equal-thickness workpieces are attached with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece mounting plate having an adhesive coating selected from the group consisting of an adhesive coating, a low-tack adhesive coating, wear-resistant coating and a water film coating that creates surface tension workpiece adhesive-type attachment forces.

19. The process of claim 18 wherein each rigid workpiece mounting plate has a flat-surface size and a flat-surface shape and the respective rigid workpiece mounting plate opposed bottom flat surface has a flat-surface size and a flat-surface shape, wherein the respective rigid workpiece mounting plates'"'"' top flat-surface sizes and bottom flat-surface sizes are substantially equal and wherein the respective rigid workpiece mounting plates'"'"' top flat-surface shapes and bottom flat-surface shapes are substantially similar and wherein each workpiece has a bottom flat-surface size and a bottom flat-surface shape wherein the respective rigid workpiece mounting plates'"'"' top flat-surface sizes are substantially equal to the respective workpiece bottom flat-surface sizes and the respective rigid workpiece mounting plates'"'"' top flat-surface shapes are substantially similar to the shape of the respective workpieces'"'"' bottom flat-surface.

20. The process of claim 18 wherein each rigid workpiece mounting plate has internal fluid passageways that connect to a fluid valve located on the external surface of the workpiece mounting plate and wherein the internal fluid passageways connect to port holes that are located on the workpiece mounting plate top flat surface and wherein vacuum is applied at the fluid valve to the internal fluid passageways, wherein workpieces are attached by vacuum with full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece mounting plate, and wherein pressurized air is applied at the fluid valve to the internal fluid passageways wherein workpieces are separated by pressurized air from full flat-surfaced contact of the respective workpieces'"'"' bottom surfaces with the top flat surfaces of the respective workpiece mounting plate.