| 摘要 |
PURPOSE:To prevent the threshold voltage, substrate effect constant from increasing by a method wherein the impurity concentration distribution in a well resin in provided with valley shape in the part deeper than the surface while the minimum point thereof with concentration not exceeding 5X10<15>cm<-3> is situated at the depth not exceeding 1.6mum from the surface of semiconductor substrate. CONSTITUTION:A P<-> type silicon substrate with 10OMEGA/square is provided and ion is implanted (boron, accelerating voltage of 50keV, implantation of 5X10<12>-2X10<13>cm<-2>) through the intermediary of SiO2 M1 and resistor M2 to form a high concentration layer 3 further forming an epitaxial layer 1a (0.8-1.7mum thick). Next, P well ion is implanted (BF2, accelerating voltage of 60keV, implantation of 2X10<12>cm<-2>) through the intermediary of SiO2 M3, Si3N4 M4 and resist M5 to form a field oxide film 20, a gate oxide film 5 and a gate electrode 6. Finally source.drain 4 is formed (As, acceleration voltage of 80keV, implantation of 3X10<16>cm<-2>) further forming an interlayer insulating film 7, interlayer electrodes 8 and a protective film.
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