Manufacture of semiconductor device

Abstract

Abstract PURPOSE:To lessen the non-uniformity of the depth of the island region at the end parts thereof by a method wherein the side face and bottom surface of the island region are oxidized using an insulator. CONSTITUTION:An etching is performed on parts of both of an Si3N4 film 23 and a thermal oxide film 22, which are respectively to become an isolated region, and after that, an etching is performed on a silicon substrate 21 in a reversely tapered form to form opening parts 24. After that, a thermal oxide film 25 is formed on the surfaces of the opening parts 24 and an Si3N4 film 26 is formed on the whole surface. The Si3N4 film 26 and the thermal oxide film 25, which are formed on the bottom surface of each opening part 24, are removed by a dry etching method of a strong anisotropy. Provided that, the Si3N4 film 26 at the prescribed region 27 of the bottom surface is left intact. After that, an etching is performed on the silicon substrate 21 in the lateral direction by an isotropic etching method to form opening parts 28 and an island region 30 is formed in such a way that oxide films 29 and 29' mutually stick by performing a selective oxidation. At this time, the oxidation at the oxide film forming time almost progresses to the lateral direction, because the Si3N4 film 24 is being left at the respective prescribed region 27 of the bottom surfaces of the opening parts 24, and the lifting-up of the Si3N4 film 26 to the upper direction due to the volumetric expansion is never generated. As a result, the uniformity of the depth of the island regions 30 is significantly improved.

Inventors

• 👤 Hiroyuki Sakai
• 👤 坂井　弘之
• 👤 Kenji Kawakita
• 👤 川北　憲司
• 👤 Toyoki Takemoto
• 👤 竹本　豊樹
• 👤 Tsutomu Fujita
• 👤 勉 藤田

Bibliographic Details