Patent ID: 8134224

Claim:
A semiconductor device comprising: a silicon substrate; a silicon oxide film formed on the silicon substrate; a first pad provided on the silicon oxide film and inputting or outputting a radio frequency signal; a first interconnect provided on the silicon oxide film and connected to the first pad; a second pad provided on the silicon oxide film and placed at a fixed potential; a second interconnect provided on the silicon oxide film and connected to the second pad; and an acceptor-doped layer formed in a region of the silicon substrate, the region being in contact with the silicon oxide film, the acceptor-doped layer being doped with acceptors and located at a region immediately below a region between the first interconnect and the second interconnect, the acceptor-doped layer having a sheet concentration of acceptors greater than that of the silicon substrate and higher than a sheet concentration of interface carriers of the silicon substrate, and an acceptor concentration on an acceptor concentration profile along depth in the silicon substrate being maximized at a first position, decreasing with the depth from the first position to a second position deeper than the first position, and remaining larger than zero and substantially constant below the second position.