| 摘要 |
PURPOSE:To perform auto-alignment with an exposure mask adequately, to obtain highly accurate machining precision and to improve mass productivity by including a diffusing step for forming a diffused region layer, and including an oxidation step for decreasing the temperature so that the diffusion in the diffused region layer does not progress and oxidation is made to advance after the diffusion step. CONSTITUTION:In a diffusing step for forming an embedded collector layer, the diffusion step is performed at the temperature of 1,200-1,250 deg.C. Thereafter, the temperature of a furnace is decreased to 900-1,150 deg.C where the diffusion of Sb does not progress and oxidation with dry O2 is made to advance at a suitable speed. Thus the oxidation is performed. In this way, an oxide film 8 at an embedded-layer forming part grows sufficiently faster than the lower part of an oxide film 6 for a diffusing mask. Therefore, the Si layer at the embedded-layer forming part has more quantity of SiO2 than in the Si layer at the lower part of the oxide film 6 for the diffusing mask. Thus the large pattern step (q) of the embedded layer is formed. Therefore, the auto-alignment for a deep collector or isolation at the next step can be effectively performed. |
