To easily remove resist used as the ion implantation mask by implanting, after impurity ion is implanted to a semiconductor layer using a resist layer as a mask, the hydrogen ion to the interface between the semiconductor layer and resist layer before the resist layer is removed.

A fine crystal silicon layer is deposited as a semiconductor layer 20 on the upper surface of a substrate 1. Next, while masking the selected region 3 of the semiconductor layer 1 with the resist layer 4, impurity ion 6 is implanted to the semiconductor layer 20 using the resist layer 4 as the mask. Since this impurity ion 6 is also implanted also to the upper region of the resist layer 4, the surface of the resist layer 4 is changed in quality and is then hardened. Moreover, the resist layer 4 burns for the semiconductor layer 20. Therefore, before removing the resist layer 4, hydrogen ion 7 is implanted to the interface between the semiconductor layer 20 and resist layer 4. As a result, hydrogen supplied to the area where burning is generated functions to assure easy ashing and removal of the resist layer 4 by he oxygen plasma process.