Patent ID: 7098255
Filing Date: 2006-08-29
Classification: B24B,B24D,C08J

Abstract:
1. A polishing sheet configured to polish a semiconductor wafer and having a thickness of 0.8 mm to 2.0 mm, comprising a cellular polyurethane foam having an average cell diameter of 50 μm or less, a density of about 0.6 to about 0.95 g/cm 3 , and an Asker D hardness of 30 to 60, said foam being formed by preparing a first ingredient comprising an aliphatic isocyanate compound and a second ingredient comprising, as a compound containing an active hydrogen group, methylene bis-o-chloro aniline and/or dicyclohexyl methane-4,4′-diamine; adding a nonionic silicone surfactant containing no hydroxyl group to at least one of said first ingredient or said second ingredient in an amount of not less than 0.1 wt. % but less than 5 wt. %, relative to the total amount of said first ingredient and said second ingredient; agitating the ingredient(s) in which said surfactant has been added, together with an unreactive gas which has no reactivity to an isocyanate group or active hydrogen group, thereby dispersing said unreactive gas as fine bubbles into said ingredient(s) containing said surfactant to produce a bubble dispersion; mixing said bubble dispersion with the remaining ingredient if any; and curing the resultant mixture wherein said first ingredient and said second ingredient react.