Photo-deposition of tantalum pentoxide film using 222 nm excimer lamps

In this paper, we report the growth of thin tantalum pentoxide films on Si (1 0 0) and quartz by photo-induced chemical vapour deposition (photo-CVD) using a 222 nm excimer lamp. The properties of the films formed have been s tudied using ellipsometry, UV spectrophotometry, Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). It was found that t he films can be deposited at substrate temperatures as low as 25 degreesC. The kinetic study of the reaction processing indicated that at low depositi on temperatures between 25 and 100 degreesC, the deposition process is a co ndensation-controlled mechanism whilst at high deposition temperatures betw een 100 and 400 degreesC a reaction-controlled mechanism is dominant during the growth with an activation energy of 0.08 eV, which is much lower than that of 2.2 eV for thermal-CVD processing. The influence of the deposition temperature on the film properties and its optimisation are discussed. At t emperatures above 100 degreesC the film thickness increased with temperatur e while it decreased as the temperature is below 100 degreesC. The refracti ve index and the optical band-gap of the films were found to be around 2.09 +/- 0.05 and 4.10 +/- 0.05 eV, respectively, while an optical transmittanc e between 85 and 98% in the visible region of the spectrum was obtained at different thicknesses. (C) 2000 Elsevier Science B.V. All rights reserved.