METHOD FOR CLEANING WAFER BEFORE THERMAL PROCESS BASED ON SC-2

PROBLEM TO BE SOLVED: To minimize presence of fine particles, organics, and metal contaminant material on a wafer surface which affects on minor-carrier re-coupling life, by growing a hydrophilic oxide layer on such wafer surface as an oxide containing contaminant metal is removed using a specific hydrogen peroxide solution with no ozone. SOLUTION: After fine particles and organic contaminant substance are removed from a wafer surface using an SC-1 solution, an oxide containing metal is removed using an HF/HCl water solution, then a hydrophilic oxide layer is grown on the wafer surface using a hydrogen peroxide solution and an SC-2 solution containing low-concentration HCl with metal removed. The HCl in the SC-2 solution works to reduce metal contamination during chemical growth of an oxide layer which is caused by H2 O2 in a solution of hydrogen peroxide containing low-concentration of hydrochloric acid with metal removed (SC-2). As a result, the hydrophilic oxide layer growing on the wafer surface comprises an appropriate metal concentration. Further, the diffusion distance of minor carrier increases than before in a heating process thereafter.