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

Volume

36

Issue

2

fYear

1989

fDate

2/1/1989 12:00:00 AM

Firstpage

351

Lastpage

359

Abstract

High-performance poly-Si TFTs were fabricated by a low-temperature 600°C process utilizing hard glass substrates. To achieve low threshold voltage (V_TH) and high field-effect mobility (μ_FE), 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 V_TH and μ_FE 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 μ_FE 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;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/16.19936

Filename

19936