| 摘要 |
PURPOSE:To prevent impurity in a mask from diffusing into a semiconductor substrate in a thermal diffusion process, by covering the end surface of a selective pattern of a selective diffusion mask with a dielectric thin film containing no impurity. CONSTITUTION:An SiO2 film 2, a PSG film 3 and an SiO2 film 4 are formed on a substrate 1. After a desired selective pattern is obtained by a photolithography process and an etching process, an SiO2 film 5 containing no impurity is formed thereon. In the case where thermal diffusion of Zn is performed applying this mask, generation of phosphorus in the mask is restrained. Thus the density of phosphorus in semiconductor is small, so the influence on element characteristics can be neglected.
|
