| 摘要 |
Provided is a method of manufacturing a flash memory device. In accordance with the present invention, an undoped polysilicon layer is formed over a semiconductor substrate where a floating gate and a dielectric layer are formed. By performing N2 plasma process with respect to the undoped polysilicon layer, a heavily doped polysilicon layer is formed to form a control gate. Due to N2 plasma process, a nitrogen layer is formed at the interfaces between the dielectric layer and the undoped polysilicon layer. As a result, during a re-oxidization process, it is possible to prevent a thickness of the dielectric layer from being increased by reducing diffusion speed phosphorous and oxygen. Additionally, phosphorous of the heavily doped polysilicon layer is diffused into the undoped polysilicon layer in a subsequent process, thereby increasing a phosphorous concentration of the undoped polysilicon layer. Accordingly, it is possible to improve a program speed by increasing a doping concentration of the control gate without a variation of coupling ratio.
|
