Large Scale Anisotropic Etching Combined with Mechanical Machining

各向异性蚀刻产生规则的形状。由特定的晶面组成。因此，特别是在特定角度及其平行度方面，期望高精度。然而，由于蚀刻掩模的持续时间，尺寸被限制为几百μ m。本研究提出一种利用常规机械加工和蚀刻的复杂工艺，以获得由特定晶面组成的大规模精确规则几何形状。解理也是一种利用晶体规则性的工艺。四英寸（110）硅晶片通过解理而破裂。获得了侧壁由{11l}面组成的4cm × 1cm厚的薄膜。然而，顶点处的角度与理论上的70.5度不一致。通过各向异性蚀刻获得的尺寸精度也进行了评价。结果表明，在（100）基片上刻蚀出的V形槽的开口角与理论值接近70.5 °，且掩模与晶向的错位小于0.2 °时，容易获得Ra为0.02nm的光滑表面。采用磨削加工获得近净形，再用各向异性腐蚀加工提高精度。在10mm厚的（100）硅衬底上研磨出4mm深的V形槽，然后进行蚀刻。沉积厚度为50nm的钨薄膜并用作蚀刻掩模。不幸的是，掩模在蚀刻10分钟后溶解，并且没有进行充分的蚀刻。因此，无法评价尺寸准确度。通过表面轮廓仪和扫描电镜对加工后的表面形貌进行观察，验证了该原理，即通过刻蚀改善了磨削后的残余几何误差和表面粗糙度，最终形状收敛到由特定晶面组成的形状。

Anisotropic etching produces regular shapes that. consist of specific crystal planes. Thus, high accuracy is expected especially in specific angles and their parallelism. However, the size is limited to several 100mum due to the duration time of the etch-mask. This study proposes a complex process of conventional machining and etching to obtain large-scale precise regular geometrv that consist of specific crystal planes.Cleavage is also a process that utilizes the crystal regularity. A four-inch (110) silicon wafer was broken by cleavage. and 4cm*lcm parallelogram whose side-walls consist of {11l} planes was obtained. However, the angle at the vertex did not coincide with the theoretical one 70.5 degree. Dimensional accuracy obtained by anisotropic etching was also evaluated. It was found that the opening angle of V-grooves etched on (100) substrate are accurately 70.5 as the theory and smooth surface with 0.02nm Ra is easily obtained if the miss-alignment of the mask with crystal orientation is less than 0.2 degree.Then, a new process was proposed. Near-net-shape is obtained bv grinding and then processed by anisotropic etching to improve the accuracy. V-grooves with 4mm depth are ground on 10mm-thick (100) silicon substrate and then etched. Tungsten thin film with 5Onm thickness was deposited and used as etching mask. Unfortunately the mask was dissolved after ten minutes etching and sufficient etching was not carried out. As a result, dimensional accuracy could not be evaluated. However, the principle was verified through the finished surface observation by profilometer and SEM.That is, residual geometrical error and surface roughness after grinding was improved by etching, and the final shape converges to the one that consists of specific crystal planes.