Process for preparing flash memory

A process for preparing flash memory includes such steps as shallow doping the substrate with the mask which is a stack grid formed on the substrate to form a shallow doped area at both side of stackgrid on substrate, generating mask layer on substrate to cover the surface and both side walls of stack grid and expose the shallow doped area, deep doping to form deep doped areas at both sides of mask layer on substrate, removing mask layer and heat treating to form source/drain area with shallow and deep connecting areas of drain.