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基于应变硅以及绝缘体上超薄应变硅(SSOI)工艺,使用氢氟酸、硝酸和醋酸的混合溶液与质量分数为25%的四甲基氢氧化铵(TMAH)溶液选择性腐蚀Si1-xGex与Si以制备绝缘体上超薄应变硅。研究了质量分数为0.5%～5%的HF和Si1-xGex中Ge的含量对选择性腐蚀的腐蚀速度与选择比的影响,优化了选择性腐蚀工艺。采用氨水、过氧化氢和水的混合溶液处理选择性腐蚀后的Si1-xGex与Si表面,得到了高应变度、高晶体质量的超薄SSOI。采用原子力显微镜(AFM)测试腐蚀速度以及腐蚀后的表面粗糙度;使用喇曼光谱仪表征Si1-xGex以及应变硅的组分以及应变度;使用透射电子显微镜(TEM)对SSOI的晶体质量进行了表征。结果表明,超薄SSOI的表面粗糙度(RMS)为0.446 nm,顶层Si的应变度为0.91%,顶层应变硅层厚度为18 nm,且具有高的晶体质量。
Based on strained silicon and silicon on insulator (SSOI) process, Si1-xGex is selectively etched using a mixed solution of hydrofluoric acid, nitric acid and acetic acid with a 25 mass% tetramethylammonium hydroxide (TMAH) solution Si to prepare ultra-thin strained Si on insulator. The effect of the content of Ge in HF and Si1-xGex with mass fraction of 0.5% ~ 5% on the corrosion rate and selectivity of selective etching was studied, and the selective etching process was optimized. The Si1-xGex and Si surfaces after selective etching were treated with a mixture solution of ammonia, hydrogen peroxide and water to obtain ultra-thin SSOI with high strain and high crystal quality. The corrosion rate and the surface roughness after etching were measured with an atomic force microscope (AFM); the composition and strain of Si1-xGex and strained silicon were characterized by Raman spectroscopy; and the crystal quality of SSOI was characterized by transmission electron microscopy (TEM) . The results show that the surface roughness (RMS) of ultrathin SSOI is 0.446 nm, the top strain of Si is 0.91%, the thickness of the top strain silicon is 18 nm, and the crystal quality is high.