| 摘要 |
PURPOSE:To make the collector of a bipolar transistor sufficiently thick and reduce the collector resistance by a method wherein, after a buried layer is formed in a recessed part of a semiconductor substrate, an epitaxial layer is made to grow to form the transistor. CONSTITUTION:A resist film 2 is applied to the main surface of a P-type semiconductor substrate 1 by coating and an window 2a is formed and the semiconductor substrate 1 is selectively etched by using the resist film 2 with the window 2a as a mask and a recessed part 3 is formed at the position corresponding to the window 2a and anti mony of high concentration is diffused by heat to form an N-type buried layer 4. At that time, an N-type buried layer 5 is simultaneously formed in the region where an NPN transistor QNPN is to be formed. Further, P-type buried layers 6 for isolating the respective transistors and a P-type layer 7 are formed. An N-type epitaxial layer 8, the N-type buried layers 4 and 5, the P-type buried layers 6 and the P-type layer 7 are made to grow. Then P-type isolating layers 9 are selectively formed to form isolating regions and a P-type layer 10 is selectively formed also in the region where a PNP transistor QPNP is to be formed and a P-type collector 1 is composed. With this constitution, the N-type buried layer 4 is formed in the recessed part 3 only so that the P-type layer 7 with sufficient thickness can be obtained.
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