Optimum conditions for novel one-step cleaning method for pre-gate oxide cleaning using robust design methodology

A novel one-step cleaning method has been developed for pre-gate-oxide cleaning to replace the conventional RCA two-step cleaning process. Tetramethyl ammonium hydroxide (TMAH) and ethylenediamine tetraacetic acid (EDTA) are added into the RCA SC-1 cleaning solution to enhance cleaning efficiency. We adapt a robust design methodology (Genichi Taguchi method) to analyze the results of our experiments. Using this novel method, it is found that the optimum conditions are A₁B₂C₁D₁ (A₁: TMAH:NH₄OH = 1:50, B₂: EDTA concentration is 100 ppm, C₁: cleaning time is 5 min, and D₁: cleaning temperature is 60°C). This novel one-step cleaning method is very promising for future large-sized silicon wafer cleaning processes because it has the advantages of reduced processing time and temperature, cost reduction due to reduced chemical usage and improved performance.