Simulation Analysis of Structure Design for Low Temperature Cu-Cu Direct Bonding in Heterogeneous Integration and Advanced Packaging Systems

In order to realize Cu-Cu bonding at low temperature, Cu pillar-concave structures on silicon substrate and on silicon substrate with another polymer layer, polyimide (PI), are both investigated through simulation. Height of Cu pillar, thickness of upper and lower silicon substrate, and thickness of Cu concave are simulated in this paper. The proposed structure could have great impacts on current semiconductor packaging technology, such as improvement of joint strength, enhancement of adhesive strength between various substrates, a Cu-Cu bonding process lower than 200 degrees C with simplified manufacturing process.