화학공학소재연구정보센터
Journal of Vacuum Science & Technology A, Vol.23, No.6, 1638-1646, 2005
Thermal reaction of polycrystalline SiC with XeF2
Studies on the thermal reaction behavior of polycrystalline cubic silicon carbide (SiC) with effusive xenon difluoride (XeF2) have been carried out over the sample temperature (T-s) range from 300 to 900 K using molecular beam quadrupole mass spectrometry combined with a time-of-flight technique and ex situ surface analyses, i.e., x-ray photoelectron spectroscopy (XPS) and scanning Auger microscopy (SAM). Above T-s=700 K, the reaction product desorbed from the SiC surface was identified as SiF4. The flux intensity of SiF4 increases monotonically as a function of T-s above 700 K. The flux intensity of XeF2 desorbed from the SiC surface decreases above T-s=700 K, and at T-s=900 K, approximately 10% of the incident XeF2 Was found to be consumed by the thermal reaction. No ions at m/e=31 (CF+), 50 (CF2+), and 69 (CF3+) to be ascribed to carbon fluoride species were detected under the present experimental conditions, and thus C atoms in SiC were found to remain as residue. From the XPS and SAM observations of the SiC samples exposed to XeF2 vapor at 1.8 X 10(-4) Torr, we find that fluorination of a native oxide layer formed on the SiC surface takes place at T-s=300 K. At T-s=520 K, the native oxide layer was partially removed from the surface, and the presence of a reaction layer composed of partially fluorinated C atoms was observed. As T-s is increased above 520 K, the reaction layer becomes thicker. Above T-s=700 K, a thick reaction layer mainly composed of C atoms is formed, while only the near-surface reaction layer is fluorinated. The fast desorption of SiF4 products reduces the Si concentration in the SiC surface and the residual C atoms having comprised the SiC lattice are left as the reaction layer. (c) 2005 American Vacuum Society.