| 摘要 |
PROBLEM TO BE SOLVED: To improve the LF property of a variable capacitance diode while suppressing the increase of its high frequency resistance Rs. SOLUTION: In this semiconductor device, a semiconductor layer of the first conductivity type is formed on the primary surface of a semiconductor substrate of the first conductivity type, and a semiconductor layer of the second conductivity type is formed with its lower surface contacting with the semiconductor layer of the first conductivity type, and with its upper surface exposed out of the primary surface of the semiconductor substrate. The surface size of the semiconductor layer of the first conductivity type is made to be smaller than the surface size of the semiconductor layer of the second conductivity type, so that the edges of the semiconductor layer of the first conductivity type is positioned inside the edges of the semiconductor layer of the second conductivity type. By using this design, the variable capacitance diode LF property is improved because the pn junction area is reduced, and the increase of the variable capacitance diode high-frequency resistance Rs is suppressed because it is only the n-type semiconductor layer that is reduced in area. COPYRIGHT: (C)2005,JPO&NCIPI
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