基于LT/HT生长法的高质量Si基Ge外延的制备与表征

Fabrication and characterization of high quality Si-based Ge epitaxy based on LT/HT growth method

为制备高性能硅(Si)基锗(Ge)外延材料,采用基于减压化学气相淀积系统(reduced pressure chemical vapor deposition,RPCVD)工艺的低温/高温(low temperature/high temperature,LT/HT)生长技术制备了厚度为1μm的Ge外延材料样品1、2,其中,LT阶段的生长温度为400~450℃,HT阶段的生长温度为700℃。通过原子力显微镜(atomic force microscope,AFM)测试得到样品1、2的材料表面粗糙度均方根(root mean square,RMS)分别为0.66、0.86 nm,样品表面光滑程度较好。同时,根据X射线衍射(X-ray diffraction,XRD)的测试结果得到样品1、2的应变度分别为0.21%、0.23%,Ge的衍射峰对称较好,表明材料结晶质量较高。通过对样品Ⅰ~Ⅳ进行热稳定性试验发现,在700℃条件下对Ge外延材料进行循环热退火,材料可以获得最好的晶体质量。

In this paper,high quality Si-based Ge epitaxy is fabricated based on low temperature/high temperature(LT/HT)growth technology of reduced pressure chemical vapor deposition(RPCVD)system.The thicknesses of the prepared Ge epitaxial sample 1 and sample 2 are 1μm.The growth temperature of LT stage is in the range of 400~450℃,and that of HT stage is 700℃.Atomic force microscope(AFM)test results show that the surfaces of the samples are both smooth,and the root mean square(RMS)values of the surface roughness of sample 1 and sample 2 are 0.66 and 0.86 nm,respectively.Besides,according to the results of X-ray diffraction(XRD),the Ge diffraction peaks are symmetry and the strain degrees of sample 1 and 2 are 0.21%and0.23%,respectively,which indicates that the crystallization quality of Ge epitaxy is high.Finally,based on the experiment of thermal stability of samplesⅠ~Ⅳ,the results indicate that the best crystalline quality of Ge epitaxy is obtained by cyclic thermal annealing at 700℃.