Plasma-Enhanced Passivation of a Cu/Ti Bilayer Gate Electrode for an Amorphous Silicon Thin-Film Transistor

摘要

Self-passivated copper as a gate electrode in the form of TiO_xN_y/Cu/Ti/Si0_2 has been obtained by exposing Cu/Ti/Si0_2 to mixed of N_2/H_2 plasma at a low temperature of 300 °C. The use of the plasma provides an additional surface heating source, allowing the Ti atoms to outdiffuse to the Cu surface at 300 °C and to react to form a passivation layer on the surface. The H_2 plasma transforms the Ti layer into titanium hydride, which effectively inhibits the Cu-Ti reaction and serves as a diffusion barrier against Cu metallization. The TiN_x0_y/Cu/Ti/SiO_2 multilayer formed at the low temperature can be used as a gate electrode in thin-film transistor liquid crystal displays (TFT-LCDs) and exhibits a gate voltage swing of 0.943 V/decade, a threshold voltage of –1.07 V, a mobility of 0.669 cm~2/V-s and a I_(on)/I_(off) ratio of 8.18 x 10~6. Consequently, this low-temperature plasma processing will allow a reliable passivated gate electrode, which can be utilized in low-temperature amorphous Si thin-film transistor liquid crystal displays, to be formed.