DMOS controlled semiconductor power device - uses DMOS FET to drive thyristor with photodiodes deposited on insulating layer with power device using most of substrate area

摘要

The device uses a vertical double diffusion insulated gate field effect transistor (DMOS) as the control device leading to a good manufacturing yield and a device which can be optically controlled. It consists of a lightly doped N type silicon substrate (10) on which is formed the control layer and on top of that the principal layer of N type these together taking up most of one face. The remainder forms the DMOS device, the drain is formed by the substrate and the gate is formed of polysilicon. The intermediate layer of the transistor is continuous with the control layer but at a lower doping level. Optical control is obtained by photo diode formed of polycrystalline silicon on an insulating layer on one face of the device and connected in series by metallisations to the control layer and the transistor gate. The second face of the device is covered with a P type layer to produce a thyristor or with an N type layer to produce a transistor.