Methods of fabricating a semiconductor device including dual transistors

A method of fabricating a semiconductor device, comprising:

• providing a polysilicon layer over a substrate having at least two active regions;
• providing a first mask over a first active region of the at least two active regions and exposing a second active region of the at least two active regions;
• forming a first polysilicon region from the exposed second active region, wherein the first polysilicon region has a conductivity type the same as a conductivity type of the first active region;
• introducing nitrogen into the first polysilicon region;
• providing a second mask over the first polysilicon region with the nitrogen, wherein the first active region is exposed by the second mask;
• and
• forming a second polysilicon region from the exposed first active region, wherein the second polysilicon region has a conductivity type the same as a conductivity type of the second active region.