Large Scale Anisotropic Etching Combined with Mechanical Machining

各向异性蚀刻产生规则的形状。由特定的晶体平面组成。因此，要求高精度，特别是在特定的角度和它们的平行度。然而，由于蚀刻掩模的持续时间，尺寸限制在几个100mum。本研究提出了一种复杂的常规加工和蚀刻工艺，以获得由特定晶体平面组成的大规模精确规则几何。解理也是一种利用晶体规律性的过程。一块四英寸（110英寸）的硅片因解理而破裂。得到了边墙由{11l}个平面组成的4cm*lcm平行四边形。然而，顶点的角度与理论的70.5度不一致。并对各向异性刻蚀所获得的尺寸精度进行了评价。研究发现，在（100）衬底上刻蚀的v型槽开口角精确为70.5，当掩模与晶体取向的偏差小于0.2度时，易于获得具有0.02nm Ra的光滑表面。然后，提出了一种新的工艺。通过磨削获得近净形状，再进行各向异性刻蚀加工，提高精度。深度为4mm的v型槽在10mm厚（100）硅衬底上研磨，然后蚀刻。制备了厚度为5Onm的钨薄膜作为蚀刻掩膜。不幸的是，掩模在蚀刻十分钟后就溶解了，没有进行充分的蚀刻。因此，无法评估尺寸精度。然而，通过轮廓仪和扫描电镜对成品表面的观察，验证了该原理。即通过蚀刻改善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.