Surface active buffered hydrogen fluoride having excellentwettability for ULSI processing

By incorporating selected hydrocarbon surfactants, a surface-active BHF (buffered hydrogen fluoride) has been tailored to achieve the following requirements: (1) the same etch rate as that of conventional BHF; (2) low contact angle; (3) nonsegregation; (4) nonfoaming; (5) low particulate count; (6) few impurities (possibility of purification); (7) low particulate adhesion on the wafer surface; (8) no surface residues; (9) excellent surface smoothness; and (10) high SiO ₂/Si etching selectivity. In order to satisfy these requirements, surfactants must satisfy the following characteristics: (1) good solubility in BHF; (2) hydrophilic property at the wafer surface, (3) nondecomposition in BHF; (4) nonreaction with BHF; and (5) sufficient lowering of contact angle at the critical micelle concentration (CMC). Aliphatic amines satisfy these requirements but have foaming problems. The requirements have been achieved using a binary surfactant system consisting of a combination of aliphatic amine and aliphatic alcohol or aliphatic acid