OPTICAL SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide a semiconductor device, where a photodiode (PD) of high speed and high photosensitivity and a transistor of high speed and high breakdown voltage are loaded together, on the same semiconductor substrate. SOLUTION: In OEIC where the transistor and a light receiving element are loaded together on the same semiconductor substrate, an n-type epitaxial layer 20 is selectively formed on a silicon substrate 1. Since film thickness of an epitaxial layer is realized which is optimum for high performance of a vertical pnp transistor 3 and the photodiode 4, a structure for showing improvement of characteristics of respective elements to the maximum is realized and the characteristic can be improved as OEIC. COPYRIGHT: (C)2006,JPO&NCIPI