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The replication process is a good method to fabricate passive optical devices. Silicon-based fabrication technology provides an efficient way to fabricate a replication master with an optically smooth surface roughness. As silicon-based technologies are often two-dimensional processes, the replication requires sophisticated fabrication steps for a master structure. For this, a vertically curved structure, which is essential for a passive optical device, is hard to fabricate. Special processes, such as x-ray lithography, laser ablation, and gray-scale lithography, can overcome the conventional two-dimensional fabrication process challenges. But these processes need additional steps, machines, and masks. This study demonstrates an easy way for fabricating a silicon master structure for vertically curved mirrors. This fabrication method is roughly divided into two steps. During the first step, a silicon wafer is etched using an inductively coupled plasma system to form optical waveguide structures in the mas...

We present the results of our development of a deep silicon etching technique, the modified Bosch-type process. Its feasibility was also investigated. This modified Bosch-type process is based on the well known Bosch-type process, but our modified Bosch-type process consists of the etching/passivating time, process transition step, and ion energy control. This modified Bosch-type process has been characterized with respect to ion energy, substrate temperature, and feature size. We found that the etching and deposition characteristics of passivating film were closely related to the resulting deep silicon etch profile. Up to a 40–50 μm deep silicon structure with vertical and positively sloped profiles was realized by the modified Bosch-type process, depending on a few parameters. In this work, this modified Bosch-type process was applied to silicon mold fabrication used for a structuring microarray and optical power splitter. Replication results confirm that this process is promising for achieving high-yie...

It is important for a micro-mirror surface to have high optical characteristics. As a conventional micro-mirror surface of a polySi structural layer has poor reflectivity, it needs a metal coating layer to improve it. However, as the metal layer sputtered on the poly-Si structural layer is often attacked by subsequent process steps, the adhesion of the metal layer needs to be improved. We report on the improvement of the adhesion and the final optical characteristics of a micro-mirror switch. The improved metal layer sputtered is strong enough to endure the rest of fabrication process. Various dry-etch chemistries for poly-Si structural layer and wet-etch chemistries for sacrificial layer are compared to preserve the metal surface quality along the fabrication process. Improved dry-etch rate of 800 nmymin with vertical etch profile was obtained from SF plasma gas. It is now possible to fabricate 6 a simple and efficient MEMS micro-mirror switch in a batch process. 2003 Elsevier Science B.V. All rights reserved.