稀释气体对化学气相沉积SiC涂层生长行为的影响

EFFECT OF DILUENT GASES ON GROWTH BEHAVIOR OF CHEMICAL VAPOR DEPOSITED SiC COATINGS

以CH_3SiCl_3-H_2为反应气体，采用Ar和H_2作为稀释气体，在1100℃、负压条件下，由化学气相沉积制备了SiC涂层，研究了稀释气体对涂层沉积速率、形貌以及晶体结构的影响。以Ar为稀释气体时，随着稀释气体流量的增加沉积速率迅速减小；用Ar作稀释气体制备的SiC涂层相对粗糙，随着Ar流量的增加，晶粒簇之间的空隙较大，涂层变得疏松。XRD分析表明：当稀释气体Ar流量超过200 ml／min时，涂层中除了β-SiC外，还逐渐出现了少量的α-SiC。以H_2为稀释气体时，当H_2流量增加到400 ml／min时，涂层的沉积速率迅速增大；以H_2为稀释气体制备的SiC涂层致密、光滑，沉积的SiC涂层全部是β-SiC，且具有非常强的(111)晶面取向，涂层中无α-SiC出现。

CVD SiC coatings were prepared by chemical vapor deposition using CH_3 SICl_3-H_2 as reaction gases and Ar and H_2 as diluent gases at 1100℃ and low-pressure. Effect of diluent gas such as H_2 or Ar on the SiC coatings growth rate, microstructure and crystal structure was investigated. When using Ar as the diluent gas, the growth rate of the coatings decreases with the increase of the flow rate of Ar and the as-deposited coatings have a rough surface. XRD results show that a small quantity of α-SiC can appear except β-SiC when the flow rate of Ar exceeds 200 ml/min. When using H_2 as the diluent gas, the growth rate of SiC coatings increases quickly as the flow rate of H_2 increases from 200 ml/min to 400 ml/min. The coatings deposited by H_2 as diluent gas have a dense and smooth surface, and are of all β-SiC without α-SiC.