| 摘要 |
PURPOSE:To make a gate length constant, prevent the dispersion of characteristics, and contrive to restrain a parasitic element effect by a method wherein a source and a drain are provided in self-alignment with one mask on a substrate having a buried earth layer under a source electrode. CONSTITUTION:An Si3N4 mask 11 is applied to an SiO2 film 10 of the p type Si substrate having the buried earth lead-out p<+> layer, the source part 13 is covered with a photo resist 12, and a window is opened through the film 10 at the drain part 14, resulting in the formation of the n<+> drain 2. Successively, the n<+> layer 2 is covered with the resist 12, and a window is opened through the source part 13. The combination of a negative and a positive resist sufficies a mask in a piece. After forming the buried earth 8 by B ion implantation and etching the SiO2 10 on the side surface, the n<+> source 1 is formed by removing the Si3N4 14 and performing ion implantation. This constitution makes the gate length uniform, thus making characteristics uniform, restrains parasitic element effect by means of the buried earth 8, and therefore to integrate two kinds of IGFET excellent in noise margin and secondary breakdown proof charateristic on the same substrate by the same process. |
