| 摘要 |
PURPOSE:To simultaneously obtain impurity regions having desired diffusion depths by selecting the hole of a diffusion mask in an expansion corresponding to an impurity forming region and the total area to a value smaller than the are a of the impurity forming region. CONSTITUTION:An Si oxidized film 2 is formed on a semiconductor layer 1, and diffusion holes 3, 4 are selectively opened. The hole 3 is formed to a value approximately equal to the area of the exposed surface on the layer 1 of a base region to be formed, and the hole 4 is formed to a value approximately equal to the exposed area on the layer 1 of the base region to be formed. A rectangular oxidized film 2a having narrow width is adjacently retained at the prescribed interval therein. Accordingly, the total area of the hole 4 becomes smaller than the exposed area on the layer 1 of the base forming region. With this film 2 as a mask an impurity is introduced into the surface of the layer, thereby obtaining the base regions 5, 6. In this manner, the base region having the desired diffusion depth can be simultaneously obtained without increasing the number of masks and steps. |
