SiC沉积的机理研究

INVESTIGATION FOR A POSSIBLE MECHANISM OF SiC DEPOSITION UNDER LOW-PRESSURE CHEMICAL VAPOR DEPOSITION

在石墨基底上采用低压化学气相沉积法沉积SiC,沉积室是热壁。H2载气通过鼓泡法将三氯甲基硅烷(methyltrichlorosilane,MTS)送入沉积室,沉积基底的面积和沉积室的体积比为1×10-2mm-1。沉积参数为:压力5kPa,温度1100℃,H2的流量为150mL/min,气相成分中H2和MTS的流量比为10。结果表明:较大的液态聚基体表面能低,小液滴在大液滴表面沉积。H2流量小时,小液滴沿大液滴的生长锥顶部环状沉积,各生长锥间有间隙。H2流量增加时,小液滴无序的分散在大液滴的表面上。据此提出了一种可能的SiC的沉积和生长机理。

SiC was deposited by low-pressure chemical vapor deposition on the surface of a graphite substrate,which was situated in a hot wall reactor.The methyltrichlorosilane（MTS） vapor in the reactor chamber was obtained with H2 carrier gas going through a bubbler maintained at 22 ℃,using the substrate surface area/reactor volume ratio of 1 × 10-2 mm-1,under condition of reduced pressure P〈5 kPa and at 1 100 ℃.The flow rate of H2 was 150 mL/min,and the gas phase composition H2 to MTS is 10.The results indicate that the surface energy of a larger droplet is lower than that of a small one,and the larger droplets coalesce with the small ones.The small droplets are deposited along the top ring of larger droplets,and a the gap exists between larger droplets.When the flow rate of H2 increases,small droplets are deposited on the surface of larger droplets in a disordered manner.According to the results,a possible mechanism of SiC deposition was proposed.