超薄全局应变硅薄膜的应变弛豫研究

Study on Strain Relaxation in Ultrathin Global-strained Si Thin Films

采用Ge浓缩法制备了高质量超薄绝缘体上锗硅(SiGe-on-insulator,SGOI)材料,然后在SGOI上通过超高真空化学气象沉积(UHVCVD)法外延了厚度为15 nm的超薄全局应变硅单晶薄膜,使用电子束光刻和反应离子刻蚀在样品上制备了一组纳米级尺寸不等的应变硅线条和应变硅岛,并利用TEM、SEM、Raman等分析手段表征样品。实验结果表明,本文制备的应变硅由于其直接衬底超薄SiGe层的低缺陷密度和应力牵制作用,纳米图形化的应变Si弛豫度远小于文献报道的无Ge应变硅或者具有Ge组分渐变层SiGe衬底的应变Si材料。

High quality SiGe-on-insulator （SGOI） was prepared by a Ge condensation method, and then a 15-nm-thick global-strained Si thin films were epitaxially grown on it. In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by electron-beam lithography （EBL） and reactive-ion etching （RIE）, and then the samples were characterized by transmission electron microscopy （TEM） , scanning electron microscopy （SEM）, Raman spectroscopy etc. The results indicated that in the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is smaller than Ge-free strained Si and strained Si on the graded SiGe layers reported in literatures, which is mainly attributed to the fully fabricated by modified Ge condensation.