Self-aligning silicon groove technology platform for the low cost optical module

The SASGT (Self-Aligning Silicon Groove Technology) platform has been developed for use as a real passive alignment. Key technologies of this platform are precise size control technology for optical active chips, three-step anisotropic etching technology for the silicon optical bench, and flux-and pressure-free die bonding technology. Precisely size controlled laser diode chip was fabricated by etching of V-grooves for cleaving along the [110] and [110] directions. We obtained the size controlled laser chips, which have a width of 298 μm and an active stripe in the center with the accuracy of ±0.5 μm, respectively. The silicon groove for positioning of laser diode, formed by three-step etching, has a width of 298 μm and a depth of 25 μm. By carefully controlling the orientation of the silicon wafer and the chemical etching environment, the size accuracy of laser diode site can be better than ±0.5 um. In addition, the flux and pressure-free bonding of laser diode chips on silicon groove was successfully accomplished by using the surface treated Au-Sn solder under the evacuated nitrogen gas flowing furnace. We achieved accurate positioning of the optical components without any auxiliary tools such as high resolution bonder, alignment mark, solder bump and guide shell. By using the SASGT platform, the coupling efficiency of the laser diode module was achieved of better than 8% and the responsivity of the photo diode module was estimated to be better than 0.85 A/W