High-Performance Short-Channel Double-Gate Low-Temperature Polysilicon Thin-Film Transistors Using Excimer Laser Crystallization

• Published in: IEEE electron device letters Vol. 28; no. 11; pp. 1010 - 1013
• Main Authors: TSAI, Chun-Chien, WEI, Kai-Fang, LEE, Yao-Jen, CHEN, Hsu-Hsin, WANG, Jyh-Liang, LEE, I-Che, CHENG, Huang-Chung
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Annealing; Applied sciences; Channels; Conductivity; Crystallization; Double gate (DG); Electric variables; Electronics; Exact sciences and technology; excimer laser crystallization (ELC); Excimer lasers; Fabrication; Grain growth; lateral grain growth; MOSFETs; Optical control; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Solid lasers; Thin film transistors; thin-film transistor (TFT); Transistors; High performance; Voltage current curve; Grain growth; thin-film transistor (TFT); excimer laser crystallization (ELC); Polycrystal; Short channel; Excimer lasers; Thin film transistor; Double gate (DG); Lateral growth; lateral grain growth
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2007.908473

In this letter, high-performance low-temperature polysilicon thin-film transistors (TFTs) with double-gate (DG) structure and controlled lateral grain growth have been demonstrated by excimer laser crystallization. Via a proper excimer laser condition, along with the a-Si step height beside the bottom gate, a superlateral growth of Si was formed in the channel length plateau. Therefore, the DG TFTs with lateral silicon grains in the channel regions exhibited better current-voltage characteristics, as compared with the conventional top-gate ones. The proposed DG TFTs ( W / L = 1/1 mum) had the field-effect mobility exceeding 550 cm 2 /Vmiddots, an on/off current ratio that is higher than 10 8 , superior short-channel characteristics, and higher current drivability. In addition, the device-to-device uniformity could be improved since grain growth could be artificially controlled by the spatial plateau structure.