Patent ID: 8093107
Filing Date: 2012-01-10
Classification: G11C,H01L

Abstract:
1. A method of semiconductor fabrication, comprising: forming a first well, a second well and a third well in a thyristor region within a semiconductor substrate; wherein the first well is formed above the second well; wherein the second well is formed above the third well; wherein the second well is a completely buried well; wherein the third well is located below the second well; wherein the first well and the third well have a first-type conductivity; wherein the second well has a second-type conductivity different from the first-type conductivity; forming a second dielectric layer conformally on the first dielectric layer over the control gate of the thyristor in the thyristor region and the gates of the MOSFETs in the MOSFET region; forming a third dielectric layer conformally on the second dielectric layer over the control gate of the thyristor in the thyristor region and the gates of the MOSFETs in the MOSFET region; depositing and patterning first photoresist to provide a first mask with a first window to etch exposed portions of the first dielectric layer in the MOSFET region; implanting first dopants for extension regions of the MOSFETs, the implanting to form the extension regions self-aligned with respect to the gates via the extension spacers; depositing and patterning second photoresist to provide a second mask over the thyristor region and the MOSFET region, the second mask having a second window over at least portions of the thyristor region; exposing the third dielectric layer through the second window of the second mask in the thyristor region while the second mask is not removed over the MOSFET region; anisotropically etching portions of the third dielectric layer in the thyristor region through the second window of the second mask so as to expose the second dielectric layer for implantation; implanting third dopants through the second window of the second mask for a first base region for the thyristor, the implanting of the third dopants being in self-aligned relationship via the second mask.