TMAH+Triton中Si湿法腐蚀机理研究现状

Research Status of Si Wet Etched Mechanism in TMAH+Triton Solution

在微机电系统(MEMS)领域硅各向异性湿法腐蚀是制作许多元器件的一项重要技术,加入非离子型表面活性剂的腐蚀液可以在硅基片上制作出各种形状,但是对于真正的腐蚀机理还有待进一步研究。介绍了硅湿法腐蚀机理的研究现状,通过不同腐蚀条件下得出的不同腐蚀结果分析其腐蚀机理。介绍了当非离子型表面活性剂加入碱性溶液时固体表面的活性剂吸附层结构,重点介绍了表面活性剂Triton X-100加入各向异性碱性腐蚀剂四甲基氢氧化铵(TMAH)后对活性剂吸附状态和硅腐蚀速率产生影响的根本原因。不同晶向硅表面的H基和OH基数量会影响其表面活性剂的吸附能力,硅在纯TMAH腐蚀液和加入活性剂Triton后的TMAH腐蚀液中的腐蚀速率存在一定差异,高质量分数的TMAH下加入不同体积分数的Triton时,不同晶面在活性剂吸附和腐蚀速率上也存在不同,给出了出现这些现象的机理分析。研究硅腐蚀机理可以为器件设计提供有效的理论支持,有助于制作更多新的MEMS结构。

Silicon anisotropic wet etching is an very important technology to fabricate many com- ponents and devices in micro-electromechanical systems （MEMS）. The etchants with nonionic surfactant reveals various shapes on the silicon substrates, but the actual etching mechanism is still further researched. The research statuses in the wet etching mechanism of the silicon are introduced. The etching mechanism is analyzed through the different etching results under different conditions. The surfactant adsorbed layer structures of solid surfaces after the nonionic surfactant added in the alkaline solution are introduced. The root cause of the effects of surfactant Triton X- 100 with the anisotropic alkaline etchant tetramethylammonium hydroxide （TMAH） on the surfactant adsorption states and silicon etching rates is emphasisly introduced. The number of H and OH terminations for silicon surfaces of different crystal orientations can affect the adsorption ability of the surfactant. There are some differences in etching rates between in the TMAH solution with and without Triton. The surfactant adsorption and etching rates on different crystal faces also are different at different volume fractions of surfactants in high mass fraction of the TMAH. The mechanism analyses of these phenomena are presented. The study of the silicon etching mechanism provides effective theoretical support and contributes to fabricate more novel MEMS structures.