Improvement of Repeatability on N-Type 4H-SiC Epitaxial Growth by High Speed Wafer Rotation Vertical CVD Tool

Abstract

N-type 4H-SiC homo-epitaxial films were grown on 150 mm diameter wafers by high speed wafer rotation vertical CVD tool, and effect of surface C/Si ratio on short-term and long-term repeatability of the SiC films was investigated. By tuning of growth condition, high uniform SiC film with in-wafer thickness uniformity of ±2.8 % (1.6 % σ/mean) and carrier concentration uniformity of ±3.1 % (1.9 % σ/mean) was successfully grown at higher introduced C/Si ratio of about 1.80, which corresponds to surface C/Si ratio higher than 1.0 on the whole wafer. This result was comparable to the film grown at lower introduced C/Si ratio of about 1.35, which corresponds to surface C/Si ratio lower than 1.0 on the whole wafer. On the other hand, the films on 13 wafers successively grown at higher introduced C/Si ratio indicated low fluctuation from 1.85 to 3.09 % (σ/mean), and the short-term repeatability of the in-wafer carrier concentration uniformity of the films grown at higher introduced C/Si ratio was improved compared with the films grown at lower introduced C/Si ratio. Additionally, in-wafer carrier concentration uniformity of the films on 171 wafers grown at higher introduced C/Si ratio showed 75 % quartile of 4.26 % (σ/mean), and this result was greatly superior to that of 8.21 % (σ/mean) for the films on 130 wafers grown at lower introduced C/Si ratio.