| 摘要 |
PROBLEM TO BE SOLVED: To elevate the breakdown voltage by providing a first region adjacent a junction of a varactor, second region adjacent to the first region, and third region adjacent to the second region, with the first and third regions having specified impurity doping concns. SOLUTION: A graph 20 of a doping profile 22 indicates a distance x from the junction 23 of a varactor diode on the abscissa and impurity doping concn. on the ordinate. Anode region 24 is formed at the left of the junction 23, and a first region 30 adjacent the junction 23 has an impurity doping concn. Nd1 of a width W1 with a second region 32 having a concn. Nd2 of a width W2 and third region 34 having a concn. Nd3 of a width W3 . The doping profiles of the regions 30, 32, 34 are low, high and low and the concns. Nd1 , Nd3 of the first and second regions 30, 34 are set to 1×10<16> cm<-3> or less.
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