Metal-Organic Chemical Vapor Deposition of Titanium Dioxide and Aluminum Titanate Thin Films

• Main Authors: CHENG-NAN HSUEH, 薛正男
• Other Authors: Dong-Hau Kuo
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/92011522089339141362

碩士 === 國立東華大學 === 材料科學與工程學系 === 90 === Abstract Thin film technology has been widely applied in semiconductor and electro-optic industries and on the fine machinery to have materials in a small size and/or in new functions with high pay-off. In this study, chemical vapor deposition (CVD) technique was used to deposit the dielectric Al2O3，TiO2，and Al2O3-TiO2 films on the silicon wafers and glass plates under the various coating conditions of low temperature and low pressure. This research was focused on the evaluations of films growth, crystalline structure, microstructure, scratch resistance, optical properties, and electrical properties by changing the experimental parameters including substrate temperature, the flow rate of CO2/H2, ATSB (aluminum tri sec-butoxide), and TiCl4 (titanium chloride). The results showed that growth rates of the Al2O3，TiO2，and Al2O3-TiO2 films decreased as the substrate temperature increased. The fastest growth rate was nearly 1.37mm/hr, and grain size decreased as the flow rate of VATSB decreased. The TiO2, and Al2O3 films were smoother and denser than the Al2O3-TiO2 films. TiO2 thin films showed the anatase phase at 350℃ and the rutile phase at 500℃. All Al2O3-TiO2 films were showed amorphous structure. Regarding to mechanical properties, there was a good adhesion to glass substrate, critical load was range 10~21 N. Residual stress was compressive for the TiO2 and Al2O3-TiO2 films. The residual stress was 1000-7000 MPa for TiO2 films and changed with temperature and VCO2/VH2, while 200-2000 MPa for Al2O3-TiO2 films and increased with temperarure. The residual stress of Al2O3 was tensile and ranged from 1000 to 7000 MPa. In respect of electrical properties, the dielectric constants of the Al2O3-TiO2 films reaching a highest value of 300 were related to the composition of the films. Under the processing condition of VTiCl4= VCO2= VH2= 50 sccm, VATSB= 75 sccm, and substrate temperature = 350℃, the electrical property was good, the value of dielectric constant was 232, and the loss tangent was 0.145. The resistivity of the Al2O3 films were higher than 1012 Ω-cm. After annealing, the resistivity of the TiO2 films increased from 108 to 1010 Ω-cm. The resistivity of the Al2O3- TiO2 films were in the range of 1010 ∼ 1011 Ω-cm, but decreased below 108 Ω-cm after annealing. For optical properties, transmittance of Al2O3 was superior to TiO2 which had higher refractive indices in the range of 2.2~2.7.