Improvement of adhesion and interfacial diffusion behavior in Cu/glass structures using OsOx layers for microelectromechanical systems

• Thin OsO2 layer functioned as an effective adhesion layer between Cu and glass.
• Annealing Ni/OsO2/glass stack improved the adhesion in Cu/Ni/OsO2/glass structures.
• Intermixing layer formed at the metal/glass interface results in excellent adhesion.
• Intermixing layer consisted of Cu, Ni, Os, O, and Si.

We demonstrated that a Cu/Ni/OsOx/glass structure fabricated by using supercritical fluid chemical deposition has high adhesion strength. The adhesion strength was determined with a scratch tester, and the films and interfaces were characterized by transmission electron microscopy. Ni deposition resulted in the reduction of the pre-deposited OsO2 layer, and an OsOx layer formed again during the subsequent post-Ni-deposition annealing. We observed an extreme adhesion improvement. The high adhesion strength originated from the presence or re-formation of the OsOx layer and the diffusion of Cu, Ni, and Si into the OsOx layer.

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