High-quality 4H–SiC epitaxial layers grown on 200-mm substrates

A high-quality n-type 4H–SiC epitaxial layer was grown on a 200-mm, 4° off-axis 4H–SiC substrate using a horizontal hot-wall single-wafer chemical-vapor deposition reactor. The uniformity and defects of the epitaxial wafer were characterized using Fourier-transform infrared spectroscopy, the mercury-probe capacitance–voltage method, and a KLA-Tencor Candela tool. Through a combination of simulations and experiments, the effects of the hydrogen flow rate and the critical carbon-to-silicon ratio on the growth rate and defect formation were studied and optimized. As a result, high-quality 200-mm 4H–SiC epitaxial wafers were obtained, with a thickness uniformity of 0.86% and a doping-concentration uniformity of 1.38%. The useable-area yield reached 98.72% with a site size of 5 × 5 mm2. To assess production quality, data from more than 75 batches were analyzed statistically. The results showed average uniformities of 1.00% for thickness and 1.92% for doping concentration, with an average projected yield of 97.10% for 5 × 5-mm2 dies. Furthermore, 1200 V MOSFETs fabricated using these wafers exhibited an average device yield of 95.90%. Together, these multidimensional data demonstrate that the 200-mm 4H–SiC epitaxial wafer process has robust batch-production capabilities.