| 摘要 |
<p>A semiconductor device is provided with a bipolar element and MOSfield-effect transistors formed on one surface of a semiconductorsubstrate. A first buried layer of a first conductivity type is formed in a region of the semiconductor substrate in which the bipolar element and at least one of the MOS field-effect transistors are formed. A second buried layer of the first conductivity type is formed in a portion of the semiconductor substrate corresponding to at least the emitter of the bipolar element. The depth from the surface of the semiconductor substrate to the second buried layer is less than the depth from that surface to the first buried layer. This makes it possible to prevent any increase in the capacity of the MOS field-effect transistors, and increase the operating speed of the bipolar element. </p> |
