(A) silicon flip-chip module with a self-aligned structure coupling to the fiber on oxidized porous silicon substrate

Abstract

We proposed a silicon flip-chip module with a self-aligned structure capable of the passive alignment for the optical coupling, and 3-D packaging integrated with through-wafer via interconnections and the buried structure of fiber and photo-detector. The fiber and the photo-detector are buried in the grooves of silicon substrate face-to-face through the wafer window. And the other chips are integrated on the surface of the substrate and the through-wafer via interconnection can be used as a short signal path and the platform for the flip-chip bonding. It can be extended to the 3-D packing of ICs easily. We presented detailed fabrication process of the through-wafer via interconnection and high frequency characerization of a low pass filter module flip chip bonded to the coplanar waveguide line with via interconnects. 25㎛ thick oxide layer on low resistivity-5 ohm·cm silicon wafer was fabricated by the silicon anodization and the thermal wet oxidation at 1060℃. and 240㎛ long through-hole vias are filled with the copper barrels electro-plated within the thick oxide side wall. A RF LPF chip was flip-chip bonded directly to the top side of vias. The evaluated cutoff frequency of this LPF module was 2.143GHz and other performance characteristics are discussed. An optical receiver module was fabricated with the through-wafer via interconnection. 3-dimensional packing of the fiber, photo-detector, and transimpedance amplifier(TIA) chips was assembled and we evaluate the performance of optical module. The modulated 167KHz 1300 nm light is detected and amplified. The optical loss was 0.5dB excluding fiber originated loss and the transimpedance gain of TIA was 1.44kohm with one output of open connection. It shows the good possibility of the 3-D packaging of opto-electronic interconnects. A V-grooved waveguide on the thick oxide (TO) layer with the polymer core structure is proposed and fabricated for the passive alignment of the assembly of the silicon optical b...