Reduction of Short Channel Effects and Hot Carrier Induced Instability in Fully Self-Aligned Gate Overlapped Lightly Doped Drain Polysilicon TFTs

Electrical characteristics of fully self-aligned gate overlapped lightly doped drain (FSA-GOLDD) polysilicon thin-film transistors (TFTs), fabricated with a spacer technology and providing submicron (0.35 μm) LDD regions, have been analyzed. Device characteristics show negligible series resistance of the LDD region while effective drain field relief has been demonstrated by a reduced kink effect and off-current, if compared to conventional self-aligned (SA) devices. Short channel effects are also mitigated by the LDD region, while substantial reduction in the hot-carrier induced instability is found, when compared with conventional SA devices. Optimum doping dose of the LDD region has been identified to be 9 × 1012cm2.