We have developed new opto-electronic substrates, which are keycomponents for constructing opto-electronic multichip modules. Thesesubstrates consist of optical waveguides (for OEIC chip-to-chip opticalinterconnection) on copper-polyimide multilayers for high-speedelectrical transmission. Low-loss (0.4 dB/cm) fluorinated polyimideridge waveguides with nearly vertical and smooth sidewalls (<0.1 p m)on copper-polyimide multilayer substrates are achieved usingspincoating, photolithographic patterning, and highly selective dryetching. The low propagation loss is retained even after heat-treatmentat the soldering temperature of 300° C. The uniformity of thewaveguide film thickness is about ±2% and the uniformity of theetched depth in the ridge waveguides (including the fiber-guidinggroove) is about ±2% over the whole substrate (9×9 cm).This new substrate achieves self-aligned fiber-to-waveguide couplingwith a low coupling loss deviation (≃0.1 dB)
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