STUDY OF RAPID THERMAL PRECLEANING FOR SI EPITAXIAL-GROWTH

In this paper, in situ H-2 precleaning of bare and oxide patterned (100) Si substrates was studied at 800-1100-degrees-C and 5 Torr with base pressures of 1.5 x 10(-4) to 7 x 10(-4) Torr.The preclean can cause considerable surface damage due to enhanced etching, which strongly depends on process parameters such as base pressure and temperature. High preclean temperatures with low base pressures cause severe surface roughness, impacting subsequent film growth. Optimized preclean conditions produce damage-free surfaces. Preclean damage of oxide patterned substrates includes oxide consumption and surface pit formation. Surface morphology was characterized by Nomarski optical microscopy, electron microscopy, and optical reflectance. Our results and explanations suggest that under proper conditions, enhanced etching can be used to significantly lower preclean temperatures and times without observable etching damage. We demonstrate that an 800-degrees-C H-2 preclean for 15 and 60 s is sufficient for high quality Si epitaxial and selective epitaxial growth, respectively.