| 摘要 |
PURPOSE:To change the horizontal width of impurity diffusion layer due to the change of manufacturing conditions by opening a window of oxide film at the surface of semiconductor substrate so that the internal circumference of window is formed as a tapered surface. CONSTITUTION:A PSG film 16 is formed on an oxide film 5 and a resist film 17 with aperture is formed thereon. The surface is then etched. Since the etching speed is high, a side edge is formed on the PSG film 16 and a window 15 having the tapered surface is formed. Here, impurity is deposited on a silicon oxide film 5 where a window 15 is formed. In this case, if the diffusion time is short, impurity is diffused only from the aperture of window 15 and when the diffusion time is long, impurity is diffused from the thinner part. Thereby, the impurity diffusion layer becomes thick and its horizontal width is widened. When the horizontal width is gradually widened, the interval between the impurity diffusion layer 11 of the collector region 8 and the impurity diffusion layer 10 of the emitter region 7 becomes short and thereby a current amplification factor of transistor becomes large. |
