光モジュール実装基板における薄膜電極の付着力評価

抄録

We use scratch-tests to measure the adhesion force of gold/platinum/titanium thin-film electrodes patterned on planar-lightwave-circuit devices of optical modules. In the patterning process, a sacrificial copper layer is deposited by vacuum evaporation, and the thin-film electrodes are patterned both on SiO₂ over glass layers and on deep pits. A microscratch tester is used to measure the adhesion force between the SiO₂ over glass layer and the thin-film electrodes: the critical load is 157.7 mN (16.08 gf) and the shear stress is 1.36 GPa. Energy-dispersive X-ray spectroscopy (EDX) of the scratch surfaces of the thin-film electrodes reveals that the peeling interface of the thin-film electrodes is the interface between the gold layer and the platinum layer. Moreover, a depth profile of the thin-film electrodes by Auger electron spectroscopy (AES) shows that there is no carbon contamination in the thin-film electrodes, no oxide layer, and no copper contamination between the titanium layer and the SiO₂ over glass layer.