| 摘要 |
A method of fabricating a lightly-doped drain field effect transistor (LDDFET) with or without self-aligned silicide (salicide) on a substrate is disclosed. The initial steps include either (1) anisotropic silicon nitride and polysilicon etching steps, an isotropic photoresist erosion step, and a second anisotropic etching of part of the silicon nitride to obtain a ladder-shaped polysilicon gate having a silicon nitride thereon; or (2) an anisotropic polysilicon etch step, an isotropic photoresist erosion step to expose part of the unetched polysilicon, and a second anisotropic polysilicon etch step to remove completely the unmasked polysilicon to obtain the ladder-shaped polysilicon gate. The LDD structure is formed by the implantation of ions to form a heavily-doped source and drain regions and lightly-doped regions under the step of the ladder-shaped polysilicon gate layer. Thereafter, the thin polysilicon step is oxidized completely. After the silicon nitride and silicon dioxide layers are removed, the self-aligned silicide may be applied to form the LDD with salicide.
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