The research on field emission display (FED) device has acquired further achievement for the sustaining attention of vacuum microelectronics. With the continuously improving manufacturing process and reduction of cost, FED panel display with carbon nanotube (eNT) has been the main trend in this field. To enhance brightness and realize the high gray level, it is necessary to develop triode structure FED. In the producing process of normal gate FED, it's hard to protect the emission source from the fabrication of gate electrode and dielectric layer. In addition, the cathode field emission is sensitive to gate aperture, thickness of dielectric layer and alignment accuracy [ll. For the