| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor device which is suitable for driving an electret capacitor microphone by a method wherein one end of a parasitic capacitance caused by an expansion electrode requiring a large area is set at a high resistivity. SOLUTION: A semiconductor substrate 21 whose resistivity is at 100 to 5000Ω.cm is prepared. A P-type well region 22 is formed on the substrate 21. A gate electrode 28, a source region 26 and a drain region 27 are formed on its surface. As a result, an analog MOSFET element (an input transistor) 29 is formed. Respective circuit elements are connected by electrode interconnections 39. An expansion electrode 40 is formed on an insulating film 38. The expansion electrode 40 is connected to the gate electrode 28 of the input transistor 29. |
