Investigation of the Need for Alternative cleaning Chemistries for 30Å Gate Oxides

Abstract

A comparative study of pregate cleaning solution chemistries has been conducted, for 30Å furnace oxides, to investigate the feasibility of continuing to use current cleaning technologies in this thickness range. The experiment focused on correlating changes of device properties with changes in chemistry. Several options were investigated for growing or etching the surface passivation oxide. Chemistries studied included standard SC1 (with Megasonic)/SC2, final HF, as well as room temperature single bath HF based chemistries (HF only, HF+H2O2, HF+HCl, HF+H2O2+HCl, SPM+HF). These chemistries were evaluated in terms of oxidation rate, metallic contamination from solutions, capacitance-voltage (CV) characteristics, and gate oxide integrity. Data suggest that furnace oxides can be reliably grown using conventional cleaning technology. HF-based mixtures might be justified for even more aggressive gate oxide thicknesses.