Silicon epitaxial film growth on silicon substrate exposed to UV-excited NF3/H-2 gas for native oxide removal

Abstract

In situ UV-excited NF3/H-2 gas phase cleaning for native oxide removal and Si epitaxial him growth experiments were carried out in a load-locked reactor equipped with a UV lamp and PEN heater. The effect of composition of NF3/H-2 and UV exposure on the etching characteristics of native oxide and thermal oxide has been studied. Main etching species were identified as F, NFx and HF. Hydrogen added to NF3 gas alleviates silicon surface pitting to result in the very smooth surface. RMS surface roughness was as low as 0.5 Angstrom at the ratio of H-2/NF3 of 3. Analysis of silicon eptaxial film showed the effectiveness of NF3/H-2 gas phase cleaning as the pretreatment process prior to silicon eptaxial him growth. (C) 1999 Published by Elsevier Science B.V. All rights reserved.