Method for improving write margins of SRAM cells

摘要

The present invention provides a method for improving the write margins of the SRAM cells. The method comprises: before etching a polysilicon layer to form the polysilicon gates, performing a pre-implantation process to the polysilicon layer; wherein the polysilicon layer defines SRAM NMOSFETs regions and SRAM PMOSFETs regions; wherein the pre-implantation process comprises pre-implanting the fifth-group elements to the SRAM NMOSFETs regions and the NMOSFETs regions except to the SRAM NMOSFETs regions in the polysilicon layer, and pre-implanting the third-group elements to the PMOSFETs regions excluding the SRAM PMOSFETs regions in the polysilicon layer; wherein the process of pre-implanting the third-group elements comprises forming a pre-implantation photo mask capable of covering the SRAM PMOSFETs regions and using the pre-implantation photo mask to pre-implanting the third-group elements.

主权项

1. A method for improving the write margins of the SRAM cells comprising:
before etching a polysilicon layer to form the polysilicon gates, performing a pre-implantation process to the polysilicon layer; wherein the polysilicon layer defines SRAM NMOSFETs regions, non-SRAM NMOSFETs regions, SRAM PMOSFETs regions and non-SRAM PMOSFETs regions; the pre-implantation process comprises pre-implanting the fifth-group elements to the SRAM NMOSFETs regions as well as the non-SRAM NMOSFETs regions in the polysilicon layer, and pre-implanting the third-group elements to the non-SRAM PMOSFETs regions in the polysilicon layer; wherein the process of pre-implanting the third-group elements comprises forming a pre-implantation photo mask capable of covering the SRAM PMOSFETs regions and using the pre-implantation photo mask to pre-implanting the third-group elements.