An investigation of laser annealed and metal-induced crystallized polycrystalline silicon thin-film transistors
| Autor: | Nigel D. Young, D. Murley, Michael J. Trainor, D.J. McCulloch |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Amorphous silicon
Electron mobility Materials science Silicon business.industry Doping chemistry.chemical_element engineering.material Laser Electronic Optical and Magnetic Materials law.invention Threshold voltage chemistry.chemical_compound Polycrystalline silicon chemistry Thin-film transistor law engineering Electronic engineering Optoelectronics Electrical and Electronic Engineering business |
| Zdroj: | IEEE Transactions on Electron Devices. 48:1145-1151 |
| ISSN: | 0018-9383 |
| Popis: | We report results on thin-film transistors (TFTs) made from a new hybrid process in which amorphous silicon (a-Si) is first converted to polycrystalline silicon (poly-Si) using Ni-metal-induced lateral crystallization (MILC), and then improved using excimer laser annealing (laser MILC or L-MILC). With only a very low shot laser process, we demonstrate that laser annealing of MILC material can improve the electron mobility from 80 to 170 cm/sup 2//Vs, and decrease the minimum leakage current by one to two orders of magnitude at a drain bias of 5 V. Similar trends occur for both p- and n-type material. A shift in threshold voltage upon laser annealing indicates the existence of a net positive charge in Ni-MILC material, which is neutralised upon laser exposure. The MILC material in particular exhibits a very high generation state density of /spl sim/10/sup 19/ cm/sup -3/ which is reduced by an order of magnitude in L-MILC material. The gate and drain field dependences of leakage current indicate that the leakage current in MILC transistors is related to this high defect level and the abruptness of the channel/drain junction. This can be improved with a lightly doped drain (LDD) implant, as in other poly-Si transistors. |
| Databáze: | OpenAIRE |
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