Thin film devices for flat panel displays and methods for forming the same

A method for forming a thin film device for a flat panel display, comprising:

• providing a substrate comprising a driving circuit region and a pixel region;
• forming a first polysilicon pattern layer on the driving circuit region of the substrate and simultaneously forming a second polysilicon pattern layer on the pixel region of the substrate;
• ion implantation of the first and second polysilicon pattern layers with a first conductivity type;
• forming a masking layer over the pixel region of the substrate to cover the second polysilicon pattern layer and expose the first polysilicon layer;
• ion implantation of the exposed first polysilicon pattern layer with a second conductivity type opposite to the first conductivity type, using the masking layer as an implant mask, such that the first polysilicon pattern layer has an impurity concentration different from the second polysilicon pattern layer;
• removing the masking layer;
• forming a gate dielectric layer and an overlying gate on the first and second polysilicon pattern layers, respectively;
• and
• ion implantation of the first and second polysilicon pattern layers using each gate as an implant mask, to respectively form a source/drain region therein and respectively define a channel region.