Manufacture of semiconductor device

Abstract

Abstract PURPOSE:To prevent an electric field from locally concentrating and to improve the retaining characteristic of a stored charge by isotropically etching partly a conductive layer for storing the charge in an etching step of patterning the layer, and then anisotropically etching the residue. CONSTITUTION:With a resist 10 as a mask it is isotropically etched. The isotropic etching is so optimized at its etching time as to etch a polysilicon layer 5 by approx. half. As the isotropic etching, a wet etching is, for example, employed. As the etchant, a solution of HNO3:HF=50:1 is, for example, employed. Then, with the resist 10 as a mask anisotropic etching is conducted. As the anisotropic etching, a dry etching, for example, plasma etching for etching by turning SF6 gas plasmatic and reacting it with polysilicon is employed. Thereafter, a memory cell is formed by a normal EPROM process. Thus, the edge of a floating gate electrode 5 is rounded.

Inventors

• 👤 Kouichi Maari
• 👤 真有　浩一
• 👤 Toshihiko Taneda
• 👤 種田　敏彦

Bibliographic Details