| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent a change in parasitic capacitance value added to a metal layer region with the passage of time by lessening electric charges accumulated in a semiconductor layer immediately below the metal layer region in an oscillator circuit which is required to stably provide the very precise frequency of oscillation. <P>SOLUTION: A semiconductor device comprises a p-type semiconductor substrate 53 which is formed of p-type silicon and has its one end grounded, n-type semiconductor layer 51 formed by epitaxial growth on top of the p-type semiconductor substrate 53, element isolation layer 52 consisting of a p-type diffusion layer diffused from top and bottom faces of the n-type semiconductor layer 51 in order to electrically isolate the n-type semiconductor layer 51, metal layer 55 which forms an interconnection and bonding pads, insulation film 50 for insulating the metal layer 55 from the n-type semiconductor layer 51 wherein the diffusion layers, etc. are formed, n-type buried diffusion layer 54 having a dopant concentration higher than that of the n-type semiconductor layer 51, and p-type semiconductor layer 70 which is in contact with the bottom face of the insulation film 50 and is so formed by diffusion as to be spread over the n-type semiconductor layer 51 and the element isolation layer 52. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
