JPS54150093A - Semiconductor device - Google Patents

Abstract

PURPOSE: To increase the curvature radius of the PN junction surface and thus to avoid the field concentration when the impurity is diffused within the semiconductor substrate by drilling the hole part for diffusion to the insulator layer to be used as the mask and at the same time providing the concavity to the substrate in correspondence to the hole part of the insulator layer.

CONSTITUTION: SiO₂ insulator film 5 is coated on N-type Si substrate 1, and the P-type impurity is diffused from the back surface. Thus, P-type anode region 2 is formed from the buttom surface to the side surface. Then hole part 10 is drilled to film 5 in order to form gate region 3 within substrate 1 surrounded by region 2, and furthermore concavity 11 is formed within substrate 1 via the mixed acid of HF and HNO₃ and in correspondence to part 10. After this, the P-type impurity is diffused concavity 11 for a long time at the high temperatures of 1000∼1200°C, and thus depth t1 of the horizontal diffusion is made identical to depth t2 of the vertical diffusion. In such way, the curvature radius is increased for junction surface 12, thus increasing the dielectric strength.

COPYRIGHT: (C)1979,JPO&Japio