| 摘要 |
PURPOSE:To improve the dielectric strength of high delectric strength elements by forming small signal elements and high dielectric strength elements on one substrate and eliminating the self- dosing action in double epitaxial layers. CONSTITUTION:An N<+> epitaxial layer 4 is made on a p type Si substrate 1 and is deposited with an (n) epitaxial layer 4. An N<+> buried layer 6 and a p<+> deposition layer 11 are made on the layer 4, and are deposited with an n- layer 7. Next, with the surface oxide film 8 as a mask, the layer 7 is etched and the layer 4 on the layer 3 is slightly scraped to selectively create recesses 9. An oxide film 10 is newly formed over the entire surface, and p<+> isolating layers 18 are made through stretching and diffusion from the P<+> layer 11, connecting to (p) layer 1. Next, a high dielectric strength element having p<+> base 12, n<+> emitter n<+> collector lead-out part 14 is provided in the layer 4 on the buried layer 3, and a small signal element having p<+> base 15, n<+> emitter 16, n<+> collector lead-out part 17 is created in the layer 7 on the buried layer 6 in an ordinary manner, after which Al wirings are formed to complete the device. In this method, the interfaces of the layers 4, 7 have been selectively removed and therefore the impurity layers by self-dosing may be removed, then uniform epitaxial layer formed and the high dielection strength element formed. |
