衬底上立方氮化硼薄膜的大面积生长

Large Area Growth of Cubic Boron Nitride Thin Film on Nickel Substrates

采用热丝辅助射频等离子体化学气相沉积（ＣＶＤ）方法在较大面积（≥５ｃｍ２）镍衬底上生长立方氮化硼（ｃ－ＢＮ）薄膜．所用气体为硼烷、氨气和氢气的混合气体．实验发现，灯丝温度及其分布是影响ｃ－ＢＮ薄膜生长的主要因素．Ｘ射线衍射（ＸＲＤ）分析表明，样品中立方相的成分随温度的升高而增加，当温度达到２０００℃时，样品中主要为立方相成分，无六方相（ｈ－ＢＮ）或其它杂相形成．用扫描电镜（ＳＥＭ）对样品表面不同位置形貌观察发现，立方相晶粒大小均匀且分布致密．Ｘ光电子能谱（ＸＰＳ）测得样品中Ｂ原子与Ｎ原子的组分比大约为１１．当温度达到２０００℃以上时，样品中立方相成分减小，说明在合适的温度下，可制备具有理想化学配比的大面积ｃ－ＢＮ薄膜．

Cubic boron nitride(c BN) thin films with a large area(≥5 cm 2) were grown on nickel substrates by a hot filament assisted plasma chemical vapor deposition. The reactive gases were ammonia and diborane gaseous mixtures diluted to 1% with high purity hydrogen. The ratio of NH 3 to B 2H 6 was fixed at 3∶1 and the total gas flow rate was 210 cm 3/s. The substrate temperature during deposition was maintained at 800℃. It was shown that the temperature of the filament plays an important role in the large area growth of the c BN films. When the temperature was lower than 2 000℃, the diffraction peaks of both c BN and h BN were observed in the XRD patterns. When the temperature was over 2 000℃, no diffraction signals of hexagonal boron nitride(h BN) or amorphous phase can be observed in the XRD. Only the diffraction peaks of c BN appear in the XRD patterns at the 2θ values of 43.62°, 50.92° ,75.10°, 91.14° and 96.24°, corresponding to the (111), (200), (220),(311) and (222)plane of c BN. The surface morphology and the grain size of the films deposited at 2 000℃ were examined by scanning electron microscopy(SEM). Fairly uniform cubic grains were found to be well packed in the films, the grain size being as large as 8～10 μm. X ray photoelectron spectroscopy (XPS) was used to determine the composition of the films. Good chemical composition was confirmed, the B/N ratio was estimated to be approximately 1 from the integral areas calibrated by the sensitivity factors. This indicated that the film deposited under the optimum conditions had good stoichiometry. It was suggested that the high temperature contributed to the decomposition of the reaction gases, and the more precursor radicals were responsible for the film growth.