Cleaning of Silicon Wafer Surfaces with Reactive Gases

Abstract

The Reactive Gas / Wet Cleaning uses reactive gases together with deionized water instead of wet chemistry to produce the corresponding cleaning chemicals for RCA cleaning processes directly on the surface of silicon wafers in the cleaning tool. The fast and strong reactions of the hydrophilic reactants with water and the diffusion through the thin liquid layer covering the wafer surfaces on top and bottom of the wafer lead to process times of 10 seconds, comparable to the wetting of wafer surfaces with diluted liquid chemicals in standard cleaning processes. To reveal the potential of this cleaning approach intentionally with cations contaminated wafers were subjected to the cleaning with NH3(gas)/O3(gas)/H2O (SC1) and HCl(gas)/O3(gas)/H2O (SC2). Vapor phase decomposition atomic absorption spectroscopy showed that the surface contami¬nation of all used elements on the wafer surfaces could be reduced below the detection limits of about 1E+10to 1E+9 cm-2.