RBS analysis of Si diffusion in photoresist during silylation

The diffusion of Si in thin films of photoresist during silylation was investigated using Rutherford backscattering spectroscopy (RBS) and the chemical reaction was studied by X-ray photoemission spectroscopy (XPS). Initially, Si diffuses very rapidly, then it slows down as the silylation time increases. Almost all the Si needed to form a stable cross-linked matrix is achieved within 5 min of silylation. With reactive ion etching (RIE) the etch rate of the silylated photoresist depends on the silylation time and whether the sample is blown dry, air-dried or rinsed immediately after the silylation process. A long silylation time results in the formation of a thin layer of SiO2 on the resist, which increases the RIE resistance. © 1990.