Patent ID: 6230720
Filing Date: 2001-05-15
Classification: H01L,Y10S

Abstract:
A process for cleaning a semiconductor wafer after it is polished, the polished semiconductor wafer having a surface roughness less than about 0.5 nm, a total thickness variation less than about 3 .mu.m, a surface concentration of contaminant particles (exceeding about 0.2 mm in diameter adsorbed to the wafer surface) greater than about 15 particles/cm.sup.2, said contaminant particles being greater than about 0.2 .mu.m in diameter, a surface concentration of foreign metals greater than about 1.times.10.sup.15 atoms/cm.sup.2, a surface concentration of organic compounds greater than about 1.times.10.sup.14 carbon atoms/cm.sup.2, the process comprising:(a) contacting the polished semiconductor wafer with an aqueous solution comprising an oxidizing agent to oxidize organic carbon on the surface of the semiconductor wafer,(b) after step (a), immersing the polished semiconductor wafer in an alkaline cleaning solution in the presence of a megasonic field to reduce the surface concentration of said contaminant particles exceeding 0.2 .mu.m in diameter,(c) withdrawing the polished semiconductor wafer from the alkaline cleaning solution and rinsing it with deionized water,(d) after step (c), immersing the polished semiconductor wafer in an acidic cleaning solution to reduce the surface concentration of said foreign metals,(e) withdrawing the polished semiconductor wafer from the acidic cleaning solution and immersing it in an aqueous bath comprising ozone, and(f) after step (e), drying the polished semiconductor wafer, the dried polished semiconductor wafer having a surface roughness less than about 0.5 nm, a total thickness variation less than about 2 .mu.m, a surface concentration of contaminant particles less than about 0.06 to about 0.16 particles/cm.sup.2, said contaminant particles being greater than about 0.2 .mu.m in diameter, a surface concentration of foreign metals less than about 1.times.10.sup.10 atoms/cm.sup.2, and a surface concentration of organic compounds less than about 1.times.10.sup.14 carbon atoms/cm.sup.2, the process being further characterized by the absence of a step in which the surface of the polished semiconductor wafer is dried between steps (a) and (e).