Apparatus for forming a polishing pad having a reduced striations

• US 20060067160A1
• 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 7,275,856 B2
• Time in Patent Office: Days
• US Class Current: 366/102
• CPC Class Codes: B01F 33/40 Mixers using gas or liquid agitation, e.g. with air supply tubes
• CPC Class Codes: B24D 18/009 Tools 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 7/7457 Mixing heads without moving stirrer B29B7/7438, B29B7/76 take precedence
• CPC Class Codes: B29B 7/7471 Mixers in which the mixing takes place at the inlet of a mould, e.g. mixing chambers situated in the mould opening
• CPC Class Codes: B29B 7/748 Plants B29B7/7433, B29B7/7485, B29B7/7495 take precedence
• CPC Class Codes: B29B 7/7485 with consecutive mixers, e.g. with premixing some of the components
• CPC Class Codes: B29B 7/749 with stirring means for the individual components before they are mixed together
• CPC Class Codes: B29B 7/845 Venting, degassing or removing evaporated components in devices with rotary stirrers
• CPC Class Codes: B29B 7/90 Fillers or reinforcements , e.g. fibres

Abstract

The present invention provides an apparatus 20 for forming a striation-reduced chemical mechanical polishing pad 4. The polishing pad 4 comprises a first delivery line 66 for delivering a polymeric material 52 into a mixer 68 and a second delivery line 44 for delivering microspheres 48 into the mixer 68 with the polymeric material 52. The second delivery line 44 is connected to a bulk density control unit 21. The bulk density control unit 21 comprises a storage hopper 22 for storing the microspheres 48. The storage hopper 22 further comprises a porous membrane 24 provided over a plenum 26. A fluidizing gas source 23 is connected to the plenum 26 through a gas inlet line 27. Gas 28 fed into the plenum 26 from the fluidizing gas source 23 permeates through the porous membrane 24 and reduces the initial bulk density of the microspheres 48 in the storage hopper 22.

Claims

1. An apparatus for forming a striation-reduced chemical mechanical polishing pad, comprising:

a first delivery line for delivering a polymeric material into a mixer;

a second delivery line for delivering microspheres having an initial bulk density into the mixer with the polymeric material, the second delivery line being connected to a bulk density control unit, the bulk density control unit comprising;

a storage hopper for storing the microspheres, wherein the storage hopper further comprises a porous membrane provided over a plenum;

a fluidizing gas source connected to the plenum through a gas inlet line; and

wherein gas fed into the plenum from the fluidizing gas source permeates through the porous membrane and reduces the initial bulk density of the microspheres in the storage hopper.

2. The apparatus of claim 1 wherein the initial bulk density of the microspheres is reduced by at least 20 percent.

3. The apparatus 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 apparatus of claim 1 wherein the porous membrane has an angle of 0 degrees to 60 degrees sloping downward away from inner walls of the storage hopper.

5. The apparatus of claim 1 wherein the storage hopper further comprises an agitator to facilitate fluidization of the microspheres in the storage hopper.

6. The apparatus of claim 1 wherein the bulk density control unit further comprises a recirculation loop for recirculating the microspheres and controlling bulk density of the micro spheres.

7. The apparatus of claim 6 wherein the bulk density unit further comprises a mass flow sensor for measuring a continuous bulk density of the microspheres.

8. The method of claim 6 wherein the bulk density unit further comprises a secondary fluidizing gas source for further reducing the bulk density of the microspheres.

9. The apparatus 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 apparatus 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.