| 摘要 |
PURPOSE:To prevent narrowering of the space of the diffusion region to be formed in a substrate by a method wherein the unnecessary part of the poly Si containing no impurity is removed first, and then the impurity atoms contained in high density poly Si are diffused on the poly Si containing no impurities. CONSTITUTION:A poly Si layer 25 containing no impurity, excluding the deposition part located under an overhang, is removed by performing an etching. In this case, as the homogenous poly Si only is the objective substance of removal, the etching process can be progressed in a simple form, and the etching can be controlled easily. Subsequently, a diffusion region 16 is formed by performing a heat treatment. In this case, as the impurity diffusion through poly Si 15 does not spread in lateral direction, the distance between diffusion regions 16 and 16 is not narrowered. As a result, an estimation of the extent of narrowering of the space between the diffusion regions is unnecessitated, thereby enabling to improve the degree of integration. |
