| 摘要 |
PURPOSE:To commonly perform processes of the steps of forming a Bi-MOS and an MOS by forming a P type buried diffused layer under an N type epitaxial layer. CONSTITUTION:An N type buried diffused film 12 and P type buried diffused films 10a, 10b are formed on a P type silicon substrate 11. A P-well is thinly formed in an N type epitaxial layer 13, thereby becoming the region of an N- channel MOS transistor 16, an element isolating region and the base 18 of an N-P-N bipolar transistor. In the element isolating region, there is formed a structure that a P-well 17 and the P type buried diffused film 10a are connected elevationally. As a result, in a Bi-MOS semiconductor device, a P-well which is shallower than the layer 13 can be formed. Accordingly, the same step conditions as the normal MOS semiconductor device can be used. |
