MEMS中硅各向异性腐蚀特性研究

The Study of Anisotropic Etching Characteristics of Silicon in MEMS

在碱性溶液中硅单晶片因晶向不同其刻蚀速率出现差异,利用这一特点制作三维结构器件;刻蚀速率与三维结构的形状和精度相关,刻蚀的表面粗糙度与器件的性能有关;根据各向异性腐蚀机理可知,刻蚀速率强烈依赖单晶晶向,刻蚀温度和刻蚀液的组分也会对刻蚀速率产生显著影响;表面粗糙度主要是因为刻蚀时表面被反应生成的氢气泡覆盖,局部区域不能参加化学反应,导致这一区域出现凸起;在刻蚀液中加入添加剂使气泡迅速脱离反应表面能有效降低表面粗糙度,但刻蚀液不同所适用的添加剂不同。

Due to the crystal orientation,the silicon single crystal wafers has different etching rate inthe alkaline solution. This feature is using for producing three-dimensional structural devices. Theshape and accuracy of the three-dimensional structure is related to the etching rate. The performance ofthe device is related to the surface roughness of the etched. According to the principle of anisotropicetching,the etching rate strongly depends on the single crystal orientation,while the etchingtemperature and the composition of the etching solution also havea significant effect on the etchingrate. The partial area of the surface is covered by hydrogen bubbles generated from the reaction,whichprevent the chemical reactions. This results in local bulging then affecting the surface roughness. Theadditives added to the etchant contribute to the bubbles rapidly dissociated from the reaction surface,which can effectively reduce the surface roughness,but different additives used in the etching solutionare different.