常压CVD法制备氮氧化硅薄膜沉积特性的研究

STUDY OF DEPOSITION CHARACTER OF SILICON OXYNITRIDE THIN FILMS PREPARED BY ATMOSPHERIC PRESSURE CVD

采用常压化学气相沉积方法(atmospheric pressure chemical vapor deposition,APCVD)制备了氮氧化硅(Si—O—N)薄膜,研究了影响其沉积速率和生长模式的因素。在φ(NH_3):φ(SiH_4)=20:1,基板温度为650℃的条件下,当混合气体流量小于720ml/min时,薄膜的形成主要受气体扩散过程控制;当混合气体流量大于720 ml/min时,则主要受表面气相反应过程控制;混合气体流量为720 ml/min的条件下,氮氧化硅薄膜的沉积过程主要受基板表面的气相反应过程控制,薄膜沉积厚度与沉积时间成线性关系,反应速率为常数1640 nm/min,表面活化能为283 kJ/mol。通过SEM分析发现:氮氧化硅薄膜的形成方式符合三维成核模型,即反应初期Si,N,O等原子在基板表面相遇结合在一起形成原子团,一定数量的原子团构成临界核;反应中期临界核长大为岛状结构,岛不断长大,岛与岛之间相互接合形成通道网络结构;反应后期,原子不断填补网络空洞,最后成为连续薄膜。

Silicon oxynitride thin films were prepared by atmospheric pressure Chemical vapor deposition. The factors controlling deposition rate and formation mode were studied. The results indicate that as the substrate temperature being 650℃ , p(NH3) : (?)(SiH4) ratio being 20, when the flow rate of the mixed gas is lower than and higher than 720 ml/min, the major factor controlling film formation is the gas diffusion process and surface gas reaction, respectively; when the flow rate of the mixed gas equaled to 720 ml/min, the surface reaction was mainly controlled by substrate surface reaction, the film thickness is linearly correlated to deposition time, the deposition rate is 1640 nm/min, and the surface-active energy is 283 kJ/mol. SEM analysis reveals that the formation of Si - O - N films is three-dimension nucleation. The nucleation process is composed of three stages. At the beginning, the Si, N and O atoms congregate into atom clusters, and subsequently, some clusters form critical cores. Secondly, the cores grow to be islands, and the islands extend to form tunnels and networks. Finally, more atoms fill in the holes on the networks to form continuous films.