Abstract: A method for making a MOSFET includes forming a gate oxide layer on a substrate; depositing and forming a polysilicon layer on the gate oxide layer; removing the polysilicon layer and the gate oxide layer in a target area by means of dry etching. The remaining gate oxide layer forms a gate oxide of the MOSFET. The remaining polysilicon layer forms a gate of the MOSFET. The method further includes performing LDD implantation on the substrate at both sides of the gate, to form a first LDD area and a second LDD area respectively; and performing SD implantation to form a source and a drain in the substrate at both sides of the gate respectively. Before one of the steps after the depositing and forming a polysilicon layer on the gate oxide layer, fluorine ion implantation is performed.

Abstract: A method for making an LDMOS device including forming a first ion doped region in an epitaxial layer of a first region and removing a first oxide layer of the first region, the first oxide layer being formed on the epitaxial layer; forming a second oxide layer on the epitaxial layer and the remaining first oxide layer; forming a second ion doped region in the epitaxial layer of a second region, the first region and the second region having no overlapped region; and forming a polysilicon layer on the second oxide layer; removing the polysilicon layer, the first oxide layer and the second oxide layer of a third region.

Abstract: A method for making a MOSFET includes forming a gate oxide layer on a substrate; depositing and forming a polysilicon layer on the gate oxide layer; removing the polysilicon layer and the gate oxide layer in a target area by means of dry etching. The remaining gate oxide layer forms a gate oxide of the MOSFET. The remaining polysilicon layer forms a gate of the MOSFET. The method further includes performing LDD implantation on the substrate at both sides of the gate, to form a first LDD area and a second LDD area respectively; and performing SD implantation to form a source and a drain in the substrate at both sides of the gate respectively. Before one of the steps after the depositing and forming a polysilicon layer on the gate oxide layer, fluorine ion implantation is performed.