One-step cleaning solution to replace the conventional RCA two-step cleaning recipe for pregate oxide cleaning

Abstract

This work proposes an advanced wet chemical one-step cleaning process which omits the hydrochloric acid/hydrogen peroxide/water mixture (HPM) step in RCA. A novel one-step cleaning solution had been developed for pregate oxide cleaning to replace the conventional RCA two-step cleaning recipe, which used ammonia/hydrogen peroxide (or SC-1) and HPM (or SC-2) step. Tetramethylammonium hydroxide (TMAH) and ethylenediaminetetraacetic acid (EDTA) were added into the RCA SC-1 cleaning solution to enhance cleaning efficiency. From the experimental results, the particles and metallic contamination on the bare Si wafer surface could be removed significantly by applying this one-step cleaning solution. The effectiveness of various cleaning recipes and their interaction mechanism with silicon surfaces were studied. The surface adsorption and double layer models could explain the surface behavior of TMAH solutions. Based on the model, the particle, surface roughness and metallic contaminants can be realized. It was observed that the electrical properties of metal oxide semiconductor capacitors after cleaning with this novel solution were better than those after the conventional RCA cleaning. Besides, the cleaning method combining NH4OH, tetramethylammonium hydroxide, ethylenediaminetetraacetic acid, and H2O2, at 80 degreesC for 3 min showed high performance on particle removal, metal cleaning, surface smoothness, and electrical properties. Hence, this one-step cleaning process is very promising for future large sized silicon wafer cleaning due to the advantages of time-saving, low cost, and high performance. (C) 2001 The Electrochemical Society.