| 摘要 |
A flash memory structure and a method of fabricating the same are provided. The flash memory structure is formed with buried bit lines that are lower in resistance, are shallower in buried depth into the substrate, and have a larger punchthrough margin than the prior art. The flash memory structure is constructed on a semiconductor substrate. A tunneling oxide layer is formed over the substrate. A plurality of floating gates is formed at predefined locations over the tunneling oxide layer. A plurality of sidewall spacers is formed on the sidewalls of the floating gates. A plurality of selective polysilicon blocks is formed over the substrate, each being formed between one neighboring pair of the floating gates. An ion-implantation process is performed to dope an impurity element through these selective polysilicon blocks into the substrate to thereby form a plurality of impurity-doped regions in the substrate to serve as a plurality of buried bit line for the flash memory device. A plurality of insulating layers is formed respectively over the selective polysilicon blocks. A dielectric layer is formed to cover all of the floating gates and the insulating layers, and finally, a plurality of control gates are formed over the dielectric layer, each being located above one of the floating gates.
|
