Micromachined Silicon Optical Bench for the Low Cost Optical Module

A novel self-aligning silicon optical bench for fully passive alignment of optical components and its fabrication method are presented. Key technologies developed in this work are multi-step silicon anisotropic etching for manufacturing SiOB, photolithography on three-dimensional surface, precise size control of optical active chip, and flux- and pressure-free die bonding technology. The measured size tolerance of silicon grooves for the active chip and the fiber reveals less than ±0.5µm. The photolithography process on three-dimensional surface of each site is investigated to get the patterns for deposition of electrodes, mirror, and solders, respectively. The precisely cleaved laser diode chip is obtained by V-groove etching to define the cleaving lane. This technique allows the chip to be defined with a dimensional accuracy of ±0.5µm. In addition, the pressure-free bonding technique using the electroplated Au-Sn solder makes it possible to reduce the production cost. The fabricated SiOB does not need any pre-alignment process of the optical chip and fiber to desired position such as index alignment method. On the basis of these technologies, it is shown that the fully passive alignment of optical component packaging is successfully preformed. The measured results reveal that the coupling efficiency of the laser diode module was achieved better than 8 % and the responsivity of the photo diode module was better than 0.85 A/W