Method of forming a polishing pad having reduced striations

• US 20060066001A1
• Filed: 09/30/2004
• Published: 03/30/2006
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Rohm and Haas Electronic Materials CMP Holdings, Inc.
• Original Assignee: Rohm and Haas Electronic Materials CMP Holdings, Inc.
• Inventors: November, Samuel J., Koetas, Joseph P., Saikin, Alan H., Leviton, Alan E., Norton, Kari-Ell, Robertson, Malcolm W.
• Granted Patent: US 7,396,497 B2
• Time in Patent Office: Days
• US Class Current: 264/161
• CPC Class Codes: B24B 37/205 provided with a window for inspecting the surface of the work being lapped
• CPC Class Codes: B24D 18/00 Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
• CPC Class Codes: B29B 7/726 Measuring properties of mixture, e.g. temperature or density B29B7/724 takes precedence
• CPC Class Codes: B29B 7/748 Plants B29B7/7433, B29B7/7485, B29B7/7495 take precedence
• CPC Class Codes: B29C 39/006 Monomers or prepolymers by reaction injection moulding B29C67/246

Abstract

The present invention provides a method of forming a chemical mechanical polishing pad, comprising providing a tank with polymeric materials and providing a storage hopper with microspheres having an initial bulk density, wherein the storage hopper further comprises a porous membrane provided over a plenum. The method further provides the steps of connecting a fluidizing gas source to the plenum through a gas inlet line and fluidizing the microspheres and reducing the initial bulk density by feeding gas into the plenum. In addition, the method further provides the steps of providing a delivery system for delivering the polymeric materials and the microspheres to a mixer, forming a mixture of the polymeric materials and the microspheres, pouring the mixture into a mold to form a molded product and cutting the molded product into the polishing pad.

Claims

1. A method of forming a chemical mechanical polishing pad, comprising:

providing a tank with polymeric materials;

providing a storage hopper with microspheres having an initial bulk density, wherein the storage hopper further comprises a porous membrane provided over a plenum;

connecting a fluidizing gas source to the plenum through a gas inlet line;

fluidizing the microspheres and reducing the initial bulk density by feeding gas into the plenum;

providing a delivery system for delivering the polymeric materials and the microspheres to a mixer;

forming a mixture of the polymeric materials and the microspheres;

pouring the mixture into a mold to a form a molded product; and

cutting the molded product into the polishing pad.

2. The method of claim 1 wherein the step of fluidizing the microspheres reduces the initial bulk density by at least 20 percent.

3. The method of claim 1 wherein the porous membrane achieves permeability with a pressure drop of 0.498 to 13.780 kPa at a 0.152 m/sec normal gas velocity.

4. The method of claim 1 further comprising the step of providing a recirculation loop for recirculating the microspheres back to the storage hopper before delivering the microspheres to the mixer.

5. The method of claim 4 further comprising the step of providing a mass flow sensor for measuring a continuous bulk density of the microspheres.

6. The method of claim 4 further comprising the step of providing a secondary fluidizing gas source for further reducing the bulk density of the microspheres.

7. The method of claim 1 further comprising the step of providing an agitator in the storage hopper to facilitate fluidization of the microspheres.

8. The method of claim 1 further comprising the step of venting the mixer before pouring the mixture.

9. The method of claim 1 wherein the microsphere comprises polyvinyl alcohols, pectin, polyvinyl pyrrolidone, hydroxyethylcellulose, methylcellulose, hydropropylmethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, polyacrylic acids, polyacrylamides, polyethylene glycols, polyhydroxyetheracrylites, starches, maleic acid copolymers, polyethylene oxide, polyurethanes, cyclodextrin, copolymers of acrylonitrile and vinylidene chloride and combinations thereof.

10. The method of claim 1 wherein the polymeric material comprises, polyurethanes, polycarbonates, polyesters, silicones, polyimides, polysulfone, polyvinyl chloride, polyacrylonitrile, polymethylmethacrylate, polyvinylidene fluoride, polyethylene terephthalate, polyetheretherketone, polyetherketone, polyetherimide, ethylvinyl acetate, polyvinyl butyrate, polyvinyl acetate, acrylonitrile butadiene styrene, fluorinated ethylene propylene and perfluoralkoxy polymers, and combinations thereof.