Abstract: A method for fabricating a semiconductor device. Specifically, a method that includes forming a source and drain region in a periphery transistor, exhibiting a channel width between the source and drain regions suitable for operation at predetermined voltages. After forming the source and drain regions, to eliminate diffusion of lightly doped drain regions resulting from a later formation of the source and drain regions, forming the lightly doped drain regions adjacent to the source and drain regions of the periphery transistor. After forming the lightly doped drain regions in the periphery transistor, the method includes forming a source region and a drain region in a core memory cell, independent of forming the source and drain regions in the periphery transistor.