| 摘要 |
PROBLEM TO BE SOLVED: To provide an MOS (metal oxide semiconductor) type varactor in which the resistive component from under a gate electrode to a control voltage terminal can be decreased. SOLUTION: An N well 11 is formed on the upper layer of a P type Si substrate 10, P+ diffusion layers 13 and 14 becoming a pair of source-drain regions are formed in the N well 11, a gate oxide film is formed on the upper layer of the N well 11, and a gate electrode 15 is formed on the upper layer of the gate oxide film. In such an MOS type varactor, an N+ diffusion region 21 having an impurity concentration higher than that of the N well 11 is formed on the bottom of the N well 11. COPYRIGHT: (C)2005,JPO&NCIPI
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