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Optical Engineering

Characteristics of polycrystalline silicon thin-film transistors with thin oxide/nitride gate structures
Author(s): Huang-Chung Cheng; Ya-Hsiang Tai; Ming Shiann Feng; Jau-Jey Wang
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Paper Abstract

Polycrystalline silicon (poly-Si) thin-film transistors (TFTs) with thin oxide/nitride (O/N) structures as gate dielectrics are fabricated. Various gate dielectrics, i.e., high-temperature thermal oxides with different thicknesses, low-pressu re chemical-vapor-deposited silicon nitrides, and different combinations of O/N structures with various thicknesses, are performed to study their effects on poly-Si TFTs. The effective carrier mobility of devices with thin gate oxides is several times larger than of those with thick gate oxides. However, the breakdown voltages of thin gate oxides are too low to satisfy the requirements of TFT applications. Silicon nitrides can be substituted because of the high breakdown voltage and the smooth dielectric/poly-Si interfaces. A problem in adopting silicon nitride is the large interface stress between the silicon nitride and the poly-Si. A thin thermal pad oxide beneath the silicon nitride is therefore grown to reduce the high interface stress. Finally, the equivalent oxide thickness effect of the O/N gate structures on the electrical characteristics of TFTs is systematically investigated.

Paper Details

Date Published: 1 August 1993
PDF: 5 pages
Opt. Eng. 32(8) doi: 10.1117/12.143982
Published in: Optical Engineering Volume 32, Issue 8
Show Author Affiliations
Huang-Chung Cheng, National Chiao Tung Univ. (Taiwan)
Ya-Hsiang Tai, National Chiao Tung Univ. (Taiwan)
Ming Shiann Feng, National Chiao Tung Univ. (Taiwan)
Jau-Jey Wang, National Chiao Tung Univ. (Taiwan)

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