Wet chemical cleaning of plasma oxide grown on heated (001)InP surfaces

摘要

Wet chemical. cleaning is performed prior to most semiconductor processing steps, including epitaxial growth, metal and dielectric film deposition, and diffusion, with the purpose of removing unwanted chemical species that reside on the wafer surface. In this article we report the results of our investigations of a specific type of residue that is formed from the interaction between CF4/O-2 plasmas and heated (001) InP surfaces. Our studies indicate that these residues are homogeneous oxides, about 10 nm thick, and that they impede wafer processing. In addition, these "plasma oxides" do not show significant growth after removal of the wafer from the plasma and storage in ambient. Moreover, we identify several aqueous solutions, such as HF and HNO3, that can be used to remove plasma residues at room temperature and likely induce regrowth of oxides similar to those found on "epi-ready"-like surfaces. In general, chemical cleaning in aqueous acidic solutions tends to stabilize the surface, with little further growth of oxide occurring in the hours following the wet chemical cleaning. (C) 2004 American Vacuum Society.