Low-temperature Growth of High Quality Poly-SiGe based on Nucleation Control Technique

1996年，为了提高薄膜的结晶度，我们在反应热CVD中研究了SiGe的成核和选择性生长。主要研究了气体流量比、生长温度、压力和薄膜成分。结果表明，无论薄膜成分如何，直接成核都发生在SiO_2衬底上：在375ﾟC的生长条件下，富Ge薄膜的成核密度控制在10^&lt；6-12&gt；cm^&lt；-2&gt；；在450ﾟC的条件下，富硅薄膜的成核密度控制在10-12&gt；通过调节生长压力，在保持其他生长参数不变的情况下，在SiO_2衬底上实现了SiGe薄膜SiO_2/Si衬底的选择性薄膜生长。1997年，在控制薄膜生长初期成核控制和晶核的连续选择性生长的基础上，进行了高结晶度多晶SiGe的制备。在较高的压力下形成晶核后，通过调节选择性生长的生长压力，很容易实现这一点。在375ﾟC和450ﾟC下成功制备了高结晶度的多晶硅薄膜，薄膜的结晶度大大提高，没有观察到结晶不均匀现象，X射线衍射、透射电子显微镜和霍尔测量结果表明薄膜质量有了明显的改善。

In 1996, we have investigated the nucleation of SiGe and selective growth of the films in a reactive thermal CVD with GeF4 and Si2H6 for improvement of film crystallinity The major attention was paid to the gas flow ratio, growth temperature, pressure, and film composition. It was found that the direct nucleation took place on SiO_2 substrates irrespective of film composition : in the growth condition for Ge-rich films at 375ﾟC,nucleation density was controlled in a range of 10^<6-12>cm^<-2> and in the condition for Si-rich films at 450ﾟC,the density in a range of 10^<9-12>. cm^<-2>The selective film growth of SiGe films SiO_2/Si substrates was well established on SiO_2 substrate by tuning the growth pressure while the other growth parameters were kept constant.In 1997, preparation of high crystallinity polycrystalline SiGe have been carried out, based on the previous results on the control of nucleation at the early stage of the film growth and successive selective growth of the resulting nuclei to the grains. This was easily achieved by tuning the growth pressure for the selective growth after forming the nuclei at a higher pressure. The high cyrstllinity poly-SiGe thin films were successfully prepared at 375ﾟC for Ge-rich films and 450ﾟC for Si-rich films, in which the crystallinity was very much improved and no inhomogeneity of crystallinity was observed.The significant improvement of the film quality was clearly confirmed by XRD,TEM,and Hall measurement studies.