Ellipsometry study of the adsorbed surfactant thickness on Si{110} and Si{100} and the effect of pre-adsorbed surfactant layer on etching characteristics in TMAH
Ellipsometry study of the adsorbed surfactant thickness on Si{110} and Si{100} and the effect of pre-adsorbed surfactant layer on etching characteristics in TMAH
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DOI：
10.1016/j.sna.2009.10.017
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发表时间：
2009-12
影响因子：
4.6
通讯作者：
B. Tang;P. Pal;M. Gosálvez;M. Shikida;Kazuo Sato;H. Amakawa;S. Itoh
中科院分区：
文献类型：
--
作者：
B. Tang;P. Pal;M. Gosálvez;M. Shikida;Kazuo Sato;H. Amakawa;S. Itoh
本文讨论了单晶硅在含有少量Triton X-100表面活性剂的四甲基氢氧化铵（TMAH）溶液中蚀刻性能与表面活性剂在不同表面取向上的优先吸附关系。为了评价表面活性剂分子在Si{110}和Si{100}上的取向依赖性吸附，我们首次使用了光谱椭偏仪（SE），发现表面活性剂优先吸附在{110}上。通过对凸角下切行为的研究，进一步证实了这一点。考虑了表面活性剂浸浴时间、温度和超声搅拌等条件对吸附表面活性剂厚度的影响。在TMAH中，蚀刻速率和表面粗糙度与层厚的关系表明，预吸附的表面活性剂层对蚀刻特性的影响与直接添加表面活性剂（TMAH+Triton）类似，间接表明表面活性剂在TMAH+Triton蚀刻过程中被吸附在界面上。预吸附表面活性剂层产生不同的蚀刻轮廓演变，在MEMS中显示出潜在的新结构。
This paper discusses the dependence of the etching properties of single-crystal silicon in tetramethyl ammonium hydroxide (TMAH) solutions containing small amounts of Triton X-100 surfactant on the preferential adsorption of the surfactant in relation to different surface orientations. In order to evaluate the orientation-dependent adsorption of the surfactant molecules on Si{110} and Si{100}, we use spectroscopic ellipsometry (SE) for the first time, finding that the surfactant is preferentially adsorbed on {110}. This is further confirmed by studying convex corner undercutting behavior. The dependence of the adsorbed surfactant thickness on various conditions, such as the surfactant bath time, temperature and ultrasonic agitation is considered. The dependence of the etch rate and the surface roughness in TMAH on the layer thickness shows that a pre-adsorbed surfactant layer affects these etching characteristics in a similar way as the direct addition of the surfactant to the etchant (TMAH+Triton), indirectly demonstrating that the surfactant is adsorbed at the interface during etching in TMAH+Triton. The pre-adsorbed surfactant layer produces a different evolution of the etching profile, showing potentially novel structures in MEMS.