摘要 |
A method for fabricating a flash memory forms a diffusion region in the substrate at one side of the first polysilicon layer. Formation of the diffusion region is preceded by a number of steps. First, the first polysilicon layer is patterned. Then, an implantation step is performed to self-align the polysilicon layer, thereby forming implantation regions in the substrate at both sides of the first polysilicon. One of these implantation region is used for a buried bit line. Subsequently, a dielectric layer is formed over the first polysilicon layer, and the second polysilicon layer is patterned to form a control gate and the first polysilicon layer is further patterned to form a floating gate.
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