Selective deposition of a crystalline Si film by a chemical sputtering process in a high pressure hydrogen plasma

Abstract

The selective deposition of Si films was demonstrated using a chemical sputtering process induced by a high pressure hydrogen plasma at 52.6 kPa (400 Torr). In this chemical sputtering process, the initial deposition rate (Rd) is dependent upon the substrate type. At the initial stage of Si film formation, Rd on glass substrates increased with elapsed time and reached to a constant value. In contrast, Rd on Si substrates remained constant during the deposition. The selective deposition of Si films can be achieved by adjusting the substrate temperature (Tsub) and hydrogen concentration (CH2) in the process atmosphere. For any given deposition time, it was found that an optimum CH2 exists for a given Tsub to realize the selective deposition of a Si film, and the optimum Tsub value tends to increase with decreasing CH2. According to electron diffraction patterns obtained from the samples, the selectively prepared Si films showed epitaxial-like growth, although the Si films contained many defects. It was revealed by Raman scattering spectroscopy that some of the defects in the Si films were platelet defects induced by excess hydrogen incorporated during Si film formation. Raman spectrum also suggested that Si related radicals (SiH2, SiH, Si) with high reactivity contribute to the Si film formation. Simple model was derived as the guideline for achieving the selective growth.