METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

A semiconductor device having a high withstand voltage and a high reliability is provided by forming a gate insulating film having excellent film uniformity in a trench. An HTO is formed by low pressure CVD method on a trench inner wall of a Si substrate, and then a thermal oxide film is formed on an interface between the HTO and the Si substrate by thermal oxidation process (samples A and C). Thus, film thinning is locally suppressed, and a gate insulating film having excellent film uniformity and a low interface state density can be formed in the trench. A lifetime can be remarkably lengthened compared with a sample (sample B) wherein a gate insulating film is formed of only a thermal oxide film, and the trench gate structure semiconductor device having a high quality and a high reliability without withstand voltage deterioration can be provided.