| 摘要 |
PURPOSE:To prevent the lateral diffusion of phosphorous during emitter diffusion by a method wherein the emitter diffusion window-base electrode window poly Si is isolated by etching. CONSTITUTION:An epitaxial layer 12 is grown on a P type Si substrate 11 by forming an N<+> buried layer, and an isolating oxide film 13 is formed by thermal oxidation, using Si3N4 as a mask. After removal of the Si3N4, a thermal oxide film 14 is grown over the whole surface, and the base region is formed by B+ ion implantation; thereafter, a CVD-SiO2 film 15 and a CVD-Si3N4 film 16 are grown. An emitter diffusion window and a base electrode window are formed by dry-etching the films 14-16, and next a CVD-poly Si17 and a CVD-PSG18 are grown. The PSG on the base electrode is wet-etched by pattering the resist 19, and B<+> ions are implanted to the base electrode window. The emitter diffusion window-base electrode poly Si is isolated by wet etching. The emitter region is formed by heat treatment, and electrodes are evaporated after removal of the PSG. |
