The Influence of Cleaning on SiO2 Growth

The oxidation rate of single crystalline silicon depends on the preoxidation cleaning procedure. Various cleaning procedures were compared using aqueous solutions of NH 4 OH-H 2 O 2 , HCl-H 2 O 2 and H 2 SO 4 ·H 2 O 2 · A dip in 10% HF was used either at the beginning or at the end of the cleaning procedure. Thermal oxidation was carried out at 885°C, 985°C and 1085°C in a conventional diffusion furnace. The oxidation rates are maximum for the samples treated with HF as a final step in the cleaning procedure whereas a final treatment with NH 4 OH leads to a minimum oxidation rate. ESCA measurements were performed to investigate the chemical state of the SiO 2 -Si interface. The oxide contains more silicon after HF etching than after NH 4 OH etching.