Nitric acid method for fabrication of gate oxides in TFT |
| |
Authors: | Shigeaki Mizushima Shigeki Imai Asuha Masato Tanaka Hikaru Kobayashi |
| |
Affiliation: | a Display Technology Development Group, Sharp Corporation, 2613-1, Ichinomoto-cho, Tenri, Nara 632-8567, Japan b Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan c CREST, Japan Science and Technology Agency, Japan |
| |
Abstract: | We have developed low temperature formation methods of SiO2 layers which are applicable to gate oxide layers in thin film transistors (TFT) by use of nitric acid (HNO3). Thick (>10 nm) SiO2 layers with good thickness uniformity (i.e., ±4%) can be formed on 32 cm × 40 cm substrates by the two-step nitric acid oxidation method in which initial and subsequent oxidation is performed using 40 and 68 wt% (azeotropic mixture) HNO3 aqueous solutions, respectively. The nitric acid oxidation of polycrystalline Si (poly-Si) thin films greatly decreases the height of ridge structure present on the poly-Si surfaces. When poly-Si thin films on 32 cm × 40 cm glass substrates are oxidized at azeotropic point (i.e., 68 wt% HNO3 aqueous solutions at 121 °C), ultrathin (i.e., 1.1 nm) SiO2 layers with a good thickness uniformity (±0.05 nm) are formed on the poly-Si surfaces. When SiO2/Si structure fabricated using plasma-enhanced chemical vapor deposition is immersed in 68 wt% HNO3, oxide fixed charge density is greatly decreased, and interface states are eliminated. The fixed charge density is further decreased by heat treatments at 200 °C, and consequently, capacitance-voltage characteristics which are as good as those of thermal SiO2/Si structure are achieved. |
| |
Keywords: | 81.40.Cp 73.61.Ng 85.40.Hp 73.40.Qv |
本文献已被 ScienceDirect 等数据库收录! |
|