Apparatus for interlayer planarization of semiconductor material

• US 5,257,478 A
• Filed: 01/31/1992
• Issued: 11/02/1993
• Est. Priority Date: 03/22/1990
• Status: Expired due to Term

• Current Assignee: ROHM and HAAS Electronic Materials CMP Holdings Incorporated (DuPont de Nemours, Inc.)
• Original Assignee: Rodel Incorporated (Dow, Inc.), Westech Systems, Inc. (Speedfam Co., Ltd)
• Inventors: Hyde, Thomas C., Roberts, John V. H.
• Primary Examiner(s): Kisliuk, Bruce M.
• Assistant Examiner(s): Reichenbach, Bryan
• Application Number:
  US07/829,736
• Time in Patent Office: 641 Days
• Field of Search: 51/109 R, 51/125, 51/129, 51/131.1, 51/131.3, 51/131.4, 51/131.5, 51/394, 51/401, 51/397, 51/407, 51/293, 51/296, 51/297, 51/283 R
• US Class Current: 451/287
• CPC Class Codes: B24B 37/22 characterised by a multi-layered structure

Abstract

A pad for planarizing the surface of a semiconductor wafer. The pad includes at least two layers. One layer has a hydrostatic modulus which is different from the hydrostatic modulus of the other pad.

Claims

1. Apparatus for planarizing a piece of material including

a macroscopically flat subsurface,

at least a pair of features each connected to said subsurface, each having an outer surface spaced away from said subsurface, each extending a substantially equal distance away from said subsurface, being spaced apart a distance of less than five hundred microns,

a coating extending over and covering said features and said subsurface, the outer surface of said coating comprising a work surface which is macroscopically flat,

said apparatus including

(a) a planarizing pad including

(i) a base,

(ii) a first layer of resilient material connected to said base and having an outer surface spaced apart from said base and having a hydrostatic modulus which is less than 250 psi per psi of compressive pressure when a selected compressive pressure in the range of about four psi to twenty psi is applied to said first layer,

(iii) a second layer of resilient material connected to at least a portion of said outer surface, having a planarizing surface spaced apart from said outer surface to contact and abrade said coating to expose said outer surfaces of said feature, and having a hydrostatic modulus greater than the hydrostatic modulus of said first layer when said selected compressive pressure is applied to said second layer, and

(iv) a liquid slurry polishing media on said planarizing surface of said second layer;

(b) retaining means for holding said piece of material with said work surface disposed against and contacting said slurry media; and

,

(c) motive power means for moving at least one of said planarizing pad and said retaining means with respect to the other of said pad and said retaining means such that movement of said one of said pad and said retaining means causes said slurry and said planarizing surface to contact and abrade said work surface;

said planarizing surface microscopically planarizing at least said work surface to expose said outer surfaces of said features such that

said work surface and said outer surfaces are generally microscopically flat and co-planar, said outer surfaces each terminate at and abut said work surface.

2. A polishing pad for use with a planarization apparatus, said pad comprising

(a) a resilient base material having a hydrostatic modulus which is less than about 250 psi per psi of compressive pressure when a selected compressive pressure in the range of about four psi to twenty psi is applied to said base material;

and

(b) a second planarizing layer having a hydrostatic modulus greater than about 400 psi per psi of compressive pressure when said selected compressive pressure is applied to said second layer of material;

said pad being capable of being mounted on said planarizing apparatus to act in conjunction with a slurry to planarize the work surface of a workpiece.

3. The polishing pad of claim 2 wherein said second layer is comprised of a material having a planarizing surface which contacts said slurry.

4. Apparatus for planarizing a work surface of a piece of material, said work surface being macroscopically flat and microscopically flat such that said work surface deviates at all points from a median plane passing through said work surface by an amount less than about four microns, said apparatus including

(a) a planarizing pad including

(i) a base,

(ii) a first layer of resilient material connected to said base and having an outer surface spaced apart from said base and having a hydrostatic modulus which is less than 250 psi per psi of compressive pressure when a selected compressive pressure in excess of about four psi is applied to said first layer of material,

(iii) a second layer of resilient material connected to at least a portion of said outer surface, having a planarizing surface spaced apart from said outer surface, and having a hydrostatic modulus greater than the hydrostatic modulus of said first layer when said selected compressive pressure is applied to said second layer of material, and

(iv) a slurry media on said planarizing surface of said second layer;

(b) retaining means for holding said piece of material with said work surface disposed against and contacting said slurry media;

(c) motive power means for moving at least one of said pad and said retaining means with respect to the other such that movement of said one of said pad and said retaining causes said slurry and said planarizing surface to contact and abrade said work surface.

5. The apparatus of claim 4, wherein the area of said work surface is less than sixteen square millimeters.

6. A polishing pad for use with a planarization apparatus comprising

(a) a resilient base material being at least 0.015" thick and having at least 30% of its volume composed of voids such that the base material is volume compressible and will compress at least 5% under a load of 10 psi,

(b) an intermediate layer at least 0.003" thick which is essentially volume incompressible,

(c) a top planarizing layer at least 0.005" thick, having at least 25% of its volume composed of voids such that the planarizing layer is volume compressible and will compress at least 5% under a load of 100 psi.,

said polishing pad being capable of being mounted on a suitable apparatus for planarization and by acting in conjunction with a slurry to produce a planar surface on a workpiece.

7. The polishing pad of claim 6 wherein at least some of the voids in the top planarizing layer are formed by the incorporation of elastic bubbles containing gas.

8. The polishing pad of claim 6 wherein at least some of the voids in the resilient base layer are formed by the incorporation of elastic bubbles containing gas.

9. A polishing pad for use with a planarization apparatus comprising

(a) a resilient base material being at least 0.015" thick and having at least 30% of its volume composed of voids such that the base material is volume compressible and will compress at least 5% under a load of 10 psi;

and,

(b) a top planarizing layer at least 0.005" thick, having at least 25% of its volume composed of voids such that the planarizing layer is volume compressible and will compress at least 5% under a load of 100 psi.;

said polishing pad being capable of being mounted on a suitable apparatus for planarization and by acting in conjunction with a slurry to produce a planar surface on a workpiece.