Title :
High performance low-temperature poly-Si n-channel TFTs for LCD
Author :
Mimura, Akio ; Konishi, Nobutake ; Ono, Kikuo ; Ohwada, Jun-ichi ; Hosokawa, Yoshikazu ; Ono, Yoshimasa A. ; Suzuki, Takaya ; Miyata, Kenji ; Kawakami, Hideaki
Author_Institution :
Hitachi Ltd., Ibaraki, Japan
fDate :
2/1/1989 12:00:00 AM
Abstract :
High-performance poly-Si TFTs were fabricated by a low-temperature 600°C process utilizing hard glass substrates. To achieve low threshold voltage (VTH) and high field-effect mobility (μFE), the conditions for low-pressure chemical vapor deposition of the active layer poly-Si were optimized. Effective hydrogenation was studied using a multigate (maximum ten divisions) and thin-poly-Si-gate TFTs. The crystallinity of poly-Si after thermal annealing at 600°C depended strongly on the poly-Si deposition temperature and was maximum at 550-560°C. The VTH and μFE showed a minimum and a maximum, respectively, at that poly-Si deposition temperature. The TFTs with poly-Si deposited at 500°C and a 1000-Å gate had a V TH of 6.2 V and μFE of 37 cm2/V-s. The high-speed operation of an enhancement-enhancement type ring oscillator showed its applicability to logic circuits. The TFTs were successfully applied to 3.3-in.-diagonal LCDs with integration of scan and data drive circuits
Keywords :
elemental semiconductors; field effect integrated circuits; glass; integrated logic circuits; liquid crystal displays; silicon; substrates; thin film circuits; thin film transistors; 1000 A; 3.3 inch; 500 to 600 C; 6.2 V; LCD driving circuits; Si gate TFT; TFTs; crystallinity; data drive circuits; deposition temperature; enhancement-enhancement type ring oscillator; glass substrates; high field-effect mobility; hydrogenation; integrated drive circuits; logic circuits; low threshold voltage; multigate TFT; polycrystalline Si; scan drive circuits; thermal annealing; Annealing; Atomic layer deposition; Circuits; Crystallization; Glass; Grain boundaries; Hydrogen; Plasma temperature; Substrates; Thin film transistors;
Journal_Title :
Electron Devices, IEEE Transactions on
