Patent ID: 6271105
Filing Date: 2001-08-07
Classification: H01L

Abstract:
A method for forming a multiple well of a semiconductor device, comprising:forming a first ion implantation mask over a semiconductor substrate of a first conductivity type to expose a first region of the semiconductor substrate;forming a pocket well region of the first conductivity type by ion-implanting an impurity of the first conductivity type into the first region of the semiconductor substrate;forming a first deep well region of a second conductivity type under the pocket well region and aligned with the pocket well region by ion-implanting an impurity of the second conductivity type into the first region of the semiconductor substrate;removing the first ion-implantation mask;forming a second ion-implantation mask exposing a second region of the semiconductor substrate apart from the pocket well region;forming a first peripheral well region of the first conductivity type by implanting an impurity of the first conductivity type into the second region of the semiconductor substrate;removing the second ion-implantation mask;forming a third ion-implantation mask covering the pocket well region and the peripheral well region;forming a second peripheral well region of the second conductivity type by implanting an impurity of the second conductivity type into portions of the semiconductor substrate exposed by the third ion-implantation mask; andforming a second deep well region of the second conductivity type under the peripheral well region of the second conductivity type by implanting an impurity of the second conductivity type into the portion of the semiconductor substrate exposed by the third ion-implantation mask.