| 摘要 |
PURPOSE:To establish the double diffusion type MOSFET with high output bidirectional protective diode, with low cost and high dielectric strength, by using the substrate material as it is. CONSTITUTION:The SiO2 mask is provided on the N type substrate material 31 4 to 7 mum thick, and the P type diffusion layers 32 and 33 are made, 5 mu in depth. In this case, the SiO2 film caused in the layers 32,33 is selectively opened 56 to 58. The hole 56 is formed with the difference of film thickness. Further, the N layers 41,34,37,38 about 1 mu in depth are selectively diffused to form the channel 35 about 1 mu long. On the channel, the gate oxide film 36, Mo electrode 39 are provided, hole is opened after coating with SiO2 and the Al electrodes 40 and 42 are attached. The electrode 39 is connected to the electrode via the layers 37-33-38, and bidirectional protective diode is inserted between the gate and source. Thus, since the diode 2 can be formed with the diffusion at double diffusion MOSFET formation, even if the inpurity concentration of the substrate is greatly decreased, no adverse effect on other elements is made and high dielectric strength and output can be obtained without using expensive epitaxial substrate. |
