【作者】 王艳艳；

【导师】 秦福文；

【作者基本信息】 大连理工大学 ， 凝聚态物理， 2007， 硕士

【摘要】 多晶硅薄膜以其优异的光电性能和较低的制备成本，在能源信息工业中，日益成为一种重要的电子材料，并被广泛应用于大规模集成电路和半导体分立器件。为降低多晶硅薄膜的生产成本，研究在廉价的玻璃衬底上低温制备多晶硅薄膜的技术成为当今国际的热门课题。等离子体增强化学气相沉积（PECVD）技术因具有沉积温度低，大面积均匀生长等优点，成为生长多晶硅薄膜的一种主要方法。本实验采用电子回旋共振ECR-PECVD方法，以SiH₄（掺95％的Ar气）和H₂为气源，在硅和普通玻璃为衬底上低温沉积了多晶硅（Poly-Si）薄膜。与传统的PECVD相比较，本设备有以下特点：（1）使用微波源，利用ECR在低气压下产生非平衡等离子体，使SiH₄易于分解沉积，大大降低了沉积温度。（2）利用具有较高蒸气压的SiH₄（掺95％的Ar气）为源，使其在氢气气氛中析出Si原子，直接在衬底上沉积薄膜，成膜中不含氯、氟等杂质。（3）Ar气稀释有利于微波放电，提高SiH₄离解率。以硅为衬底，通过改变SiH₄流量、H₂流量和衬底温度等工艺参数，沉积了品质较好的多晶硅膜。利用透射电镜（TEM）来表征晶体的微结构，利用原子力显微镜（AFM）来表征表面形貌，通过RHEED对实验结果进行分析比较，得出适宜低温生长多晶硅薄膜的工艺参数。研究结果表明：温度为350～500℃时，其它沉积参数不变，衬底温度越高沉积薄膜的晶化越好；在SiH₄流量稳定的情况下，适当增大H₂流量也有利于Poly-Si薄膜的形成。以玻璃为衬底，即使增大H₂流量或者提高衬底温度，也不能沉积晶质较好的Poly-Si薄膜。主要原因是硅为单晶同质衬底，而玻璃为非晶异质衬底，衬底结构对薄膜的沉积影响很大。为了解决这个问题，我们引入了缓冲层。利用RHEED，X射线衍射谱（XRD），拉曼（Raman）光谱研究了缓冲层对Poly-Si薄膜薄膜生长的影响，得出了低温沉积Poly-Si薄膜的最佳工艺参数。更多还原

【Abstract】 As an important electronic material in energy-information industry, Poly-Silicon thinfilms are widely used in large scale integration （LSI） and semiconductor discrete devicesbecause of its excellent photoelectric characteristics and low-cost of preparation. In order toreduce its cost, more and more researchers have devoted to the research of the method toprepare the Poly-Si film at low temperature using cheap glass as substrate. Plasma enhancedchemical vapor deposition （PECVD） is one of the main technique among the thin filmdeposition methods. It can be used to deposit large area high-uniformity film at lowtemperature.Poly-crystalline silicon thin films are deposited on silicon and glass substrates byelectron cyclotron resonance-PECVD （ECR-PECVD） at low temperature using SiH₄ and H₂plasma as hytrogen and Si sources, respectively. Compared with the conventional PECVD,the ECR semiconductor processing device （ESPD） has the following characteristics: （1） Thenon-equilibrium plasma induced by microwave source at low pressure is helpful for thedecomposition of SiH₄, thus greatly reducing the deposition temperature. （2） The precursor isSiH₄ （95% of the doped Ar gas） with higher vapor pressure, which results in the silicon atomsto separate out and deposit thin films composed of pure silicon without impurities such as Cl,F. （3） The Adding of Ar is beneficial for discharge, so the rate of dissociation of SiH₄ can beraised.On the substrate of Si, thin film of high quality is prepared by changing the parameterssuch as the deposition temperature, the ratio of H₂ and SiH₄. The film crystal structure andsurface morphology are observed by transmission electron microscopy （TEM） and atomicforce microscopy （AFM）, respectively. The growth parameters are optimized and the idealgrowth conditions have been obtained by comparing the results of reflect high electrondiffraction （RHEED）. The results indicate that: at the temperature of 350～500℃, the higherthe temperature is, the better crystalline quality of Poly-Si is; when the flow rate of SiH₄ isfixed, increasing the ratio of H₂ is favorable for the formation of Poly-Si film.Using glass as substrate, in spite of increasing the ratio of H₂ and the substratetemperature, the Poly-Si thin film of high quality can’t be prepared directly. The main reasonis that the silicon is homogenous substrate while the glass is not, which has great influence onthe deposition of the Poly-Si thin film. In order to resolve this problem, we have introduced the buffer layer. The effects of buffer layer are investigated by means of RHEED, X-raydiffraction （XRD） and Raman spectrum. By analyzing the images of Poly-Si thin film, thebest deposition conditions are obtained at low temperature.更多还原