MANUFACTURE OF SEMICONDUCTOR DEVICE

摘要

PURPOSE:To prevent the occurrence of birdpeak by providing a thin film for buffer on the interference between a semiconductor substrate and an Si3N4 film wherein the thin film has a diffusion coefficient which is equivalent to or below that of an oxidizing agent for a substrate. CONSTITUTION:Poly Si 22 is placed on a p type Si substrate 21 in piles. B is doped by opening the poly Si 22 by an Si3N4 mask 23 to form isolation layers 25a, 25b by wet oxidation. Birdpeak is extremely small as the diffusion coefficient of O2 is same for Si and poly Si. The Si3N4 23 is removed and the poly Si 22 is convereted into SiO2. Then the poly Si 22 is removed by HF solution. SiO2 26 and poly Si 27 are placed on the p type Si substrate 21 in piles for selective opening 29. After forming n<+> layers 30, 31, the poly Si 27 is selectively left to cover with PSG 32. Electrodes 33 are provided by selectively opening the PSG 32 to cover with an oxide film 34. In this composition, high integration and the improvement of the reliability for element characteristics will be attained as the occurrence of birdpeak is extremely small.