| 摘要 |
PURPOSE:To increase the withstand voltage of a bipolar MOS device and to prevent the channel doping of the device by forming a passivation phosphorus-doped insulating film thinly on the gate region of an MOSFET and in low phosphorus density. CONSTITUTION:A high density PSG film 21 is accumulated in approx. 5000Angstrom on an oxidized film 15 at the stage that the steps of forming diffused layers, 19, 20 or the like completely in a bipolar element forming regionIand MOSFET froming region II and forming a thick thermally oxidized film 15 on the surface of the substrate. Then, a contacting region and a gate rgion are opened with holes, nondoped SiO2 film 22 is accumulated, holes are again opened so as not to expose the PSG film 21, and a gate film 25 is formed at the holes. Subsequently, it is treated with phosphorus to form a low density phosphorus-doped layer 26, a hole is opened newly at the contacting part, and aluminum electrodes 28, 29 are formed. In this manner, external diffusion is prevented from the film 21 to stabilize the threshold value of the MOS element and to enhance the withstand voltage with the gettering effect of the thick PSG film 21. |
