Principles of wet chemical processing in ULSI microfabrication

Fine patterning technology for integrated device manufacturing requires properties such as surface cleanliness, surface smoothness, complete uniformity, and complete etching linearity in wet chemical processing. An improved chemical composition for buffered hydrogen fluoride (BHF:NH/sub 4/F+HF+H/sub 2/O) is determined based on fundamental research into the chemical reaction mechanism of BHF and SiO/sub 2/. Advanced wet chemical processing based on investigation of chemical reaction mechanisms and properties of liquid chemicals, concentrating on the SiO/sub 2/ patterning process by BHF, is described. The principles of wet chemical processing in silicon technology are based on the following: the determination of the dominant reaction (etching) species, the influence of the solubility of the etching products in BHF on etching uniformity and linearity, stability of chemical composition without solid-phase segregation, and an improvement of the wettability of liquid chemicals on the wafer surface by the addition of a surfactant.<>