Polycrystalline Lpcvd 3c-Sic Thin Films on Sio2 Using Alternating Supply Deposition

Abstract

In this paper, we demonstrate the deposition of 3C-SiC thin films on SiO2 using the alternating supply deposition (ASD) technique in a low-pressure chemical vapor depositions (LPCVD) furnace. We provide data of the thin film properties showing strong dependencies on the process gas flow rates of silane, propane and hydrogen. For comparative reasons all gas flow compositions were performed on <100> silicon and SiO2. Hereby a decreased rate of growth per cycle of ~37 % was discovered on SiO2. X-ray photoelectron spectroscopy (XPS) depth profiling revealed an oxygen content of 7.5 % ±2.5 % throughout the entire thin film when grown on SiO2. High resolution transmission electron microscopy (HRTEM) showed a 15 nm amorphous carbon layer at the 3C-SiC/Si interface. Conversely, on SiO2 a 10 nm graphite layer was determined as intermediate layer leading to prominent <111> 3C-SiC X-ray diffraction (XRD) peaks. Independent of the substrate type a similar microstructure is observed in cross-sectional analyses. Atomic force microscopy (AFM) surface roughness measurements showed for all SiO2 thin films lower values with a minimum of 4.9 nm (RMS), compared to 7 nm on Si. The electrical film resistivity was determined on SiO2 with CTLM analysis, depending on the process gas composition. The gained knowledge is beneficial for MEMS applications, where tailored 3C-SiC-on-SiO2 structures are required.

Keywords: 3C-SiC, SiO2, Alternating Supply Deposition, LPCVD, Silicon Carbide