SiO_2牺牲层刻蚀实验的研究与分析

The Experimental Study and Analysis of the Etching for SiO_2 Sacrificial Layer

氢氟酸(HF)刻蚀SiO2牺牲层受多种因素影响,其中刻蚀液的温度、组分、浓度、被刻蚀结构的形式及结构内部的残余应力等是最主要的。样品设计了多种测试结构,深入研究这些因素对刻蚀速率及结果的影响,并进行了详细的讨论与分析。通过实验可观察到刻蚀过程中的反应限制阶段与扩散限制阶段,说明经长时间的刻蚀,HF的扩散效应将成为影响刻蚀速率的主导因素。对于实验过程中观察到的"凸"状的刻蚀前端和"晕纹"现象,分析认为结构中的应力梯度及材料间不同的亲水性质是产生这些现象的主要原因。

A variety of test structures are designed to investigate the SiO2 sacrificial layer etching process using hydrofluoric acid （ HF）, which is strongly influenced by some factors like temperature, composition and concentration of the etchant, the etching structure style, residual stresses etc. The effects of these factors on etching rate and etching results are discussed and analyzed in detail In the experiment, two phases of the reaction limitation phase and the diffusion limitation phase during the etching process are observed, which demonstrate that diffusion rate of the HF becomes the dominant factor for the etching rate after long-time etching. During the experiment, the phenomena of convex etching front and circular etching patterns accompanied have been observed. Stress profile and the different hydophilicity between materials might be the reasons that explain these phenomena. All the results and conlusions from our experiments can be valuable references for related applications.