| 摘要 |
PURPOSE:For facilitating the design of the peripheral circuit elements to be provided on one substrate, to ensure carrier supply of a floating gate even when the voltage to be impressed on a drain range is low, by providing a large depth from the surface of an Si substrate for a source range than that of said drain range. CONSTITUTION:Thick field SiO2 film 9 is formed at the periphery of an N-type Si substrate 1, thin gate SiO2 film 4 is provided at the portion surrounded with said film 9 of said substrate 1, and polycrystalline Si layer 5 is deposited over the whole surface of said substrate 1 to serve as gate electrode. Next, the laminate of said film 4 and layer 5 is left by selective etching, and deep P<+>-type source range 2a is formed by diffusion Al with a large diffusion coefficient for example in the portion exposed on either of said film 4 and layer 5 of said substrate 1. A shallow P<+>- type drain range is diffusedly formed on the other by using B with a small diffusion coefficient. Thereafter, the whole surface of said substrate 1 is covered with oxidized insulating film 6, an opening is provided, and electrodes 7 and 8 are fitted to contact with said ranges 2a and 3a. |
