Removal of metal residues from semiconductor surfaces - using aq. cleaning compsn. treated with carbon di:oxide and/or oxalic acid

摘要

The ability of aq. cleaning compsns. to remove metal-contg. residues from semiconductor surfaces, esp. Si wafers, is improved by treating the compsn. with CO2 and/or oxalic acid. The cleaning compsn. is pref. water or an aq. nonionic surfactant soln. CO2 is added in an amt. corresp. to 10-100% satn. at normal pressure and 10-50 deg.C. Oxalic acid is added in an amt. of 0.1-1 wt.% at 10-50 deg.C. ADVANTAGE - The ability of existing cleaning processes to remove metal (e.g. Fe, Zn and Cu) residues can be improved without great cost. In an example, Si wafers were washed with 'SCl' NH4OH-contg. cleaning soln. (RCA Review 31, 187, 1970) in a 'Megasonic' unit at 50 deg.C for 5 min. The wafers were rinsed with (a) high-purity water or (b) high-purity water satd. with CO2 at 25 deg.C for 5 min. in a 'Quick Dump Rinser'. VPD/AAS analysis indicated contaminant levels (10 power 10 atom/cm2) for Fe, Zn and Cu of (a) 16, 52 and 10 and (b) 0.6, 0.9 and 2 respectively