| 摘要 |
PURPOSE:To lessen leak and improve yield while maintaining high antipressure properties, by making the surface concentration of the outermost circuit part of the P<-> type high antipressure layer with the surface concentration less than 10<17>cm<-3> on an N type Si substrate more than 10<17>cm<-3>. CONSTITUTION:In case of B implantation to an N type Si, if the surface concentration is less than 10<17>cm<-3>, inversion is apt to occur, while the concentration is more than the said level, inversion is hard to occur resulting in reduction of leak. The thermal oxidation is applied to the N type Si substrate 1 and a P<-> low concentration high pressure region 2 (base layer) is formed. On the outer circuit thereof a window is opened on the thermally oxidized film to perform B diffusion and form a high concentration region 3. Because of a field plate 9' the electric field adjacent to the surface 5 is weakened and the device part is filled with the depletion layer. The electric field concentration is at its peak in the outermost 7 region and the antipressure properties is determined by the region 7. Therefore leak can be prevented without giving effects to the properties of the high antipressure region 2. And the N layer 6 acts as either a source or drain with the N type substrate 1 acts as the other, and are controlled by a gate electrode 8 resulting in a stable properties. |
