铝诱导晶化制备多晶硅薄膜的研究

【作者】 刘伟；

【导师】 高斐； 高子伟；

【作者基本信息】 陕西师范大学 ， 材料学， 2008， 硕士

【摘要】 本论文研究在廉价的玻璃衬底上利用铝诱导晶化非晶硅(a-Si)薄膜制备多晶硅(poly-Si)薄膜。样品采用glass/Al/a-Si:H结构,研究了退火条件、铝膜厚度、铝膜的制备条件等因素对非晶硅薄膜晶化的影响。利用X射线衍射(XRD)光谱、拉曼(Raman)光谱、原子力显微镜(AFM)等测试手段研究了所制备的多晶硅薄膜的结构性质,得出主要结论如下:1.退火温度对非晶硅的晶化有着重要的影响,尽管有报道说铝诱导晶化非晶硅薄膜的最低温度可达到150℃,但是想快速制备高质量的多晶硅薄膜,必须适当提高退火温度,至少在300℃以上;同时,样品在高温500℃下会快速晶化,延长退火时间对样品的晶化效果影响不明显。2.非晶硅薄膜晶化为多晶硅薄膜后,出现Si(111)面的择优取向,而且退火处理时间越长,退火温度越高,择优取向越明显。3.在相同条件下,退火时间越长,样品的晶化程度越高,获得的多晶硅薄膜的晶粒越大,实验中得到的最大晶粒直径为156nm,但是薄膜表面的粗糙度增加。4.在相同条件下,退火温度越高,样品的晶化速度越快,成核密度越大,获得的多晶硅薄膜的晶粒越小,薄膜表面粗糙度越小。5.铝膜与非晶硅膜的厚度存在一个最佳的比例,当铝膜与非晶硅膜的厚度比约为1:1时,得到的多晶硅薄膜的晶化效果是最好的。6.沉积非晶硅薄膜之前,铝膜表面的氧化层对非晶硅薄膜的晶化有重要的影响。铝氧化层越厚,铝、硅原子的互扩散越难,非晶硅膜中的铝浓度及铝膜中的硅浓度越小,使硅的成核密度小,可得到尺寸大的硅晶粒;反之,铝氧化层越薄,硅的成核密度越大,会生成尺寸小的硅晶粒。更多还原

【Abstract】 In this thesis,we have studied the fabricating polycrystalline-silicon(poly-Si) thin films by aluminum-induced crystallization of amorphous silicon(a-Si) thin films on glass substrate.Some influential factors on the crystallization of a-Si thin films,which include annealing condition, thickness of Aluminum thin film,fabrication condition of aluminum thin film,and so on,are studied. The structure properties of the fabricated poly-Si thin films have been investigated by X-ray diffraction(XRD),Raman spectrum and Atomic Force Microscopy(AFM).The following conclusions have been achieved:1.Annealing temperature has an important influence on the crystalline of a-Si thin films.Although it is reported that aluminum-induced crystallization of a-Si thin films can take place at a temperature as low as 150℃,preparation of high-quality poly-si thin films must be appropriately raise the temperature,at least more than 300℃.At high temperature,for example at 500℃,samples crystallized rapidly,and extension of the annealing time did not significantly affect results of crystallization.2.After the a-Si transformed into the ploy-Si,preferred orientation of Si(111) appeared.The longer annealing time and higher annealing temperature,the preferred orientation is more obvious.3.Under the same conditions,both the crystalline volume fraction and size of crystalline grain increase with annealing time increasing,the diameter of the biggest grain achieved is 156nm. However,the roughness of the samples is also increased.4.Under the same conditions,for the higher annealing temperature,the crystallization of the samples is faster.For a greater nuclear density and smaller grains,the surface of the poly-Si thin film is smoother.5.There is an optimal thickness ratio for the aluminum film to the a-Si film.When the ratio is 1:1, the crystallization is the best.6.The surface of the aluminum film oxidized into alumina by air prior to a-Si:H film deposition. Alumina layer has an important influence on the crystallization of a-Si:H film.If the thicker alumina layer,the harder diffusion of aluminum atoms and silicon atoms,the smaller concentration of aluminum in a-Si:H film and of silicon in aluminum film,so it makes nucleation density of silicon smaller,that leads to the large-grained silicon growth.Otherwise,the thinner alumina is,the higher nucleation density of silicon,which results in the small-grained silicon.更多还原