Patent ID: 7851306

Claim:
A method for forming a semiconductor memory device with an implanted source column in a silicon substrate comprising: forming a layer of tunnel oxide over a silicon substrate having shallow trench isolation (STI) regions filled with an oxide material; forming a first layer of polysilicon over the layer of tunnel oxide; forming a first mask over the first layer of polysilicon to isolate a column parallel to the STI regions in the silicon substrate; forming a source column by implanting dopants into the column in the silicon substrate through the first layer of polysilicon and the layer of tunnel oxide; forming a common source line in the silicon substrate, wherein the common source line is perpendicular to the implanted source column, the common source line is coupled to a source region in the silicon substrate, the source region is associated with a memory cell and the common source line is permanently coupled to the implanted source column; and forming a source contact along a row of drain contacts associated with a row of memory cells perpendicular to the implanted source column, wherein the source contact is coupled to the implanted source column.