| 摘要 |
PURPOSE:To enable high reliability with high yield by implanting boron ions into an N type semiconductor layer to form a high-concentration P<+> type graft base region in the N type semiconductor layer while shaping a P type active base region in the N type semiconductor layer on second selective oxidation. CONSTITUTION:An N type semiconductor layer 3 is formed onto a P type Si substrate 1, and a field oxide film 4 is shaped by utilizing a selective oxidation method. One part is removed, second selective oxidation is conducted while using a residual Si3N4 film as a mask, a collector forming section 8 is coated with a photo-resist 9, and boron ions are implanted. a graft base region 12 as a high-concentration P<+> type impurity layer is shaped to the N type semiconductor layer just under a nitride film 5, there is the maximum value of the concentration distribution of boron in an oxide film in a section just under the oxide film on the second selective oxidation, and boron in low concentration is implanted to the N type semiconductor layer just under the oxide film 7, thus forming an active base region 10, concentration distribution thereof on an silicon surface is adjusted to one fifth from half of the maximum concentration value. The graft base region and a base region are formed through 1 time boron-ion implantation, thus simplifying a manufacturing process, then improving yield. |
