Effect of Reflow Oxidation on Si Surface Roughness during High-Temperature Annealing

Abstract

It is well known that a smooth surface of silicon (Si) wafers can be obtained by Si surface reconstruction using high-temperature annealing. However, there is a possibility that smooth Si surfaces are deteriorated by oxidation (called reflow oxidation) during unloading after the high-temperature annealing. Therefore, it is important to investigate the effect of oxidation on the surface steps and terraces on Si wafers at the atomic level during unloading. We have examined the effect of unloading temperature after Ar annealing on oxide formation on the surfaces of Si(100) and Si(110) substrates. The change in the surface roughness was also measured. Our results indicate a significant improvement with rms values of 0.01 nm for both Si(100) and Si(110) wafer surfaces upon low-temperature unloading. A very flat surface with an rms value of 0.046 nm was achieved for a Si(100) wafer.