Polishing pad and a method for manufacturing the same

1. A polishing pad comprising a polishing layer arranged on a base material layer, wherein the polishing layer comprising a thermosetting polyurethane foam having roughly spherical interconnected cells having an average cell diameter of 20 to 300 μm, the polyurethane foam comprises an isocyanate component and an active hydrogen-containing compound as starting components, and the active hydrogen-containing compound comprises 30 to 85% by weight of a high-molecular-weight polyol having 2 to 4 functional groups and a hydroxyl value of 20 to 100 mg KOH/g.

2. The polishing pad according to claim 1 , wherein the high-molecular-weight polyol comprises 20 to 100% by weight of a polymer polyol in which particles of at least one polymer selected from the group consisting of polystyrene, polyacrylonitrile and a styrene-acrylonitrile copolymer are dispersed.

3. The polishing pad according to claim 1 , wherein the active hydrogen-containing compound comprises 2 to 15% by weight of a low-molecular-weight polyol having a hydroxyl value of 400 to 1830 mg KOH/g and/or a low-molecular-weight polyamine having an amine value of 400 to 1870 mg KOH/g.

4. The polishing pad according to claim 1 , wherein the active hydrogen-containing compound comprises 5 to 60% by weight of a polyester polyol.

5. A polishing pad comprising a polishing layer arranged on a base material layer, wherein the polishing layer comprises a thermosetting polyurethane foam having roughly spherical interconnected cells having an average cell diameter of 20 to 300 μm, the polyurethane foam comprises an isocyanate component and an active hydrogen-containing compound as starting components, and the active hydrogen-containing compound comprises 1 to 20% by weight of a low-molecular-weight polyol having 3 to 8 functional groups and a hydroxyl value of 400 to 1830 mg KOH/g and/or a low-molecular-weight polyamine having 3 to 8 functional groups and an amine value of 400 to 1870 mg KOH/g.

6. The polishing pad according to claim 5 , wherein the low-molecular-weight polyol is at least one member selected from the group consisting of trimethylolpropane, glycerin, diglycerin, 1,2,6-hexanetriol, triethanolamine, pentaerythritol, tetramethylol cyclohexane, methylglucoside, and alkylene oxide adducts thereof, and the low-molecular-weight polyamine is at least one member selected from the group consisting of ethylene diamine, tolylene diamine, diphenylmethane diamine, and alkylene oxide adducts thereof.

7. The polishing pad according to claim 5 , wherein the active hydrogen-containing compound comprises 30 to 85% by weight of a high-molecular-weight polyol having 2 to 4 functional groups and a hydroxyl value of 20 to 150 mg KOH/g.

8. The polishing pad according to claim 5 , wherein the isocyanate component is carbodiimide-modified MDI.

9. A polishing pad comprising:

a base material layer; and

a polyurethane foam layer having roughly spherical interconnected cells and disposed on the base material layer,

wherein when three planes by which the polyurethane foam layer is divided in the thickness direction into quarters are designated a first plane, a second plane and a third plane in the direction of from a polishing surface of the polyurethane foam layer to the base material layer, a cell diameter distribution, which is defined as a maximum cell diameter/minimum cell diameter ratio, in the first plane is the smallest and the cell diameter distribution in the third plane is the largest.

10. The polishing pad according to claim 9 , wherein the cell diameter distribution in the first line is 3.5 or less.

11. The polishing pad according to claim 9 , wherein an average value of average cell diameters in the first to third lines is 35 to 300 μm.

12. A method for manufacturing a semiconductor device, which comprises a step of polishing the surface of a semiconductor wafer with the polishing pad of claim 1 or 5 .