Patent ID: 6348371
Filing Date: 2002-02-19
Classification: H01L

Abstract:
A method of forming self-aligned, twin well regions, in a semiconductor substrate, comprising the steps of:growing a first insulator layer on said semiconductor substrate; performing a first ion implantation procedure through said first insulator layer, into a first region of said semiconductor substrate, to form a first conductivity type ion layer; performing a thermal oxidation procedure to grow a second insulator layer on said first region of said semiconductor substrate, resulting in formation of an initial first conductivity type well region in said first region of said semiconductor substrate, directly underlying said second insulator layer, and growing a third insulator layer on second region of said semiconductor substrate, with said third insulator layer smaller in thickness than said second insulator layer; performing a second ion implantation procedure through said third insulator layer, into a second region of said semiconductor substrate, to form a second type conductivity ion layer; performing an anneal cycle to form a final first conductivity well region in said first region of said semiconductor substrate, directly underlying said second insulator layer, and forming a final second conductivity well region in said second region of said semiconductor substrate, directly underlying said third insulator layer, and with said final second conductivity well region self-aligned to said final first conductivity well region; and removing said second insulator layer, and said third insulator layer.