Penta-di-methyl-amino-tantalum (Ta[N(CH3)2]5), a new source chemical of Ta in TaO chemical vapor deposition (CVD), has been studied. TG and DTA measurements show that Ta[N(CH3)2]5 is chemically stable up to about 150°C and vaporizes at a temperature of 80°C. TaO films were deposited by LP-CVD at temperatures of 380∼520°C, by using the new chemical Ta[N(CH3)2]5 and O2. The deposition rate of TaO with Ta[N(CH3)2]5 is higher than that with Ta(OC2H5)5, a conventional Ta source. The TaO CVD using Ta[N(CH3)2]5 and O2 yields a good step coverage. Although the as-deposited TaO films are oxygen poor in film composition, annealing in an oxidizing ambient improves the stoichiometry and reduces the leakage current.
In this chapter, growth mechanism of GaN and AlGaN by MOVPE is described in detail. The parasitic reaction that generates particulates in vapor phase is the most probable limiting factor of maximum growth rate of GaN and AlGaN. Both experimental and quantum chemical study of vapor phase reaction between organo-metals and ammonia is described. From the close insight of vapor phase reaction, high flow speed three layered gas injection has been developed. By employing this three-layer gas-injection, GaN was grown with growth rate as high as 28m/h at atmospheric pressure. As long as the present growth conditions are concerned, SIMS and XRD results suggested that the growth rate of 12m/h would be a practical limitation of good quality material in terms of electrical and structural properties.
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