VLS同质外延6H-SiC薄膜生长的研究

Homoepitaxial 6H-SiC Thin Films by Vapor-Liquid-Solid Mechanism

碳化硅(SiC)是第三代宽禁带半导体材料,在高温、高频、高功率、光电子及抗辐射等方面具有巨大的应用潜力。以CH4、SiH4为反应气体,H2为载气,采用化学气相沉积法,利用气-液-固(VLS)生长机理,同质外延6H-SiC薄膜。结果表明,VLS机制能在外延薄膜的表面有效地封闭微管,但是由于n(C)/n(Si)较大,薄膜表面存在大量的台阶。为了进一步改善薄膜表面形貌,采用"两步法"工艺外延SiC薄膜,在封闭微管的同时提高了表面平整度,得到了质量较好的6H-SiC外延薄膜。

Silicon carbide（SiC） is a Ⅳ-Ⅳ compound semiconductor with a wide energy band gap. Because of its outstanding properties, SiC can be used in high-power, high-frequency, high-temperature devices with high radiation resistance. CH4-SiH4-H2 system is used to homoepitaxy 6H-SiC thin films by vapor-liquid-solid（VLS） mechanism Although there are lots of steps on the grown thin film surface, micro-pipes are closed by VLS mechanism. In order to improve morphology of the epilayers, a two-step method was proposed for homoepitaxial growth of high quali-ty 6H- SiC thin films, combining VLS growth and conventional CVD. The results show that the films grown by two-step method have better crystalline quality and smaller surface roughness than the conventional CVD and one-step VLS methods.