Ageing of Laser Crystallized and Unhydrogenated Polysilicon Thin Film Transistors

摘要

Ageing of low temperature polysilicon Thin Film Transistors (TFTs) is reported in this study. The active layer of these high performances transistors is amorphous deposited suing Low Pressure Chemicla Vapor Deposition (LPCVD) technique and then laser crystallized using a single shot ECL (SSECL of SOPRA) with very large excimeer laser. The drain and source regions are in-situ doped during the LPCVD deposition by using phosphine or diborane to fabricate n-type or p-type transistors respectively. These laser crystallized TFT's show poorer reliability poorer reliability properties than solid-phase crystallized TFT's This poor stability is explained to originate from the high surface roughness produced by the laser crystallization, which is highlighted form Atomic Force Microscopy obsrevations.