Temperature effect on structural properties of boron oxide thin films deposited by MOCVD method

Boron oxide (B2O3) thin films were deposited on Si (100) substrates using a single source precursor by thermal MOCVD method under a pressure of 150 mTorr and the temperature range of 500-650 degreesC. Tri-isopropyl borate ([(CH3)(2)CHO](3)B) was used as a precursor without carrier and bubbler gases. In this study, the structural properties of boron oxide thin films with various deposition temperatures were mainly investigated. A highly oriented cubic B2O3 thin film in the [310] direction was grown on Si (100) substrate at 600-650 degreesC. XPS analysis shows that the chemical compositions of as-grown film at 500-600 degreesC have a non-stoichiometric value as B2O3+x, while those of films grown at above 600 degreesC have a stoichiometric value as B2O3 film. From FT-IR and contact angle analysis, we realized that crystallinity of the deposited films was decreased by B-O-H bond formation. We also observed the surface morphology, grain size, and film thickness of the as-grown films by SEM. The average grain sizes and film thickness are varied, in the range of 10-40 and 200-500 nm, depending on deposition temperature. With increasing deposition temperature, the grain size as well as film thickness are also increased. In conclusion, the structural properties of the as-grown boron oxide thin films are strongly dependent upon deposition temperature. Therefore, as mentioned, more stoichiometric films are produced in the surrounding of high temperature (above 600 degreesC). In addition, we formed that the film crystallinity is also improved with increasing deposition temperature. (C) 2004 Elsevier B.V. All rights reserved.