| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor device, suitable for capacitor microphone drive by a method, wherein one end of a parasitic capacity attributable to extended electrode requiring a large area, is set at high resistivity. SOLUTION: In this semiconductor device, there is formed on a semiconductor substrate 21, an epitaxial layer 23 of high resistivity in which the resistivity is 100 to 5,000Ωcm, and this is junctioned and isolated to form an island region 25. There are formed, in the island region 25, a NPN transistor, and a junction- type field effect transistor. There is formed an extended electrode 43, which is continuous to a gate electrode of the junction-type field effect transistor. The island region 25 in the lower part of the extended electrode 43 is set in the condition of high resistivity. The NPN transistor forms an N-type collector region 60 through diffusion in the island region 25, to form a collector layer. The spread of a depletion layer is enlarged to reduce the value of a parasitic capacitance C1, and flowing out of a signal out of the extended electrode 43 to a ground potential GND is prevented. |
