Polymer adhesives have emerged as a promising dielectric passivation layer in hybrid bonding for 3D integration, but they raise misalignment problems during curing. In this work, the synergistic effect of oxygen plasma surface activation and wetting is utilized to achieve bonding between completed cured polyimides. The optimized process achieves a void-less bonding with a maximum shear strength of 35.3 MPa at a low temperature of 250 °C in merely 2 min, significantly shortening the bonding period and decreasing thermal stress. It is found that the plasma activation generates hydrophilic groups on the polyimide surface, and the wetting process further introduces more −OH groups and water molecules on the activated polyimide surface. The synergistic process of plasma activation and wetting facilitates the bridging of polyimide interfaces to achieve bonding, providing an alternative path for adhesive bonding in 3D integration.

In this paper, new electrothermal characteristics degradation and failure mechanism of Silicon carbide junction barrier Schottky (SiC JBS) devices with different die attach materials under 300°C power cycle stress were investigated and found based on thermal structure function and failure analysis. The results showed that the electrothermal characteristics (thermal resistance, R _{th j-d} and on-resistance, R _on ) were consistent, which were different in that decreased firstly and then increased for nanosilver, but increased overall for alloy solders under 300°C PC, both strongly related to evolution of porosity, secondphase, interface cracks, grain size in the die attach layer. However, the electrothermal characteristics were affected by dieattach evolution to varying degrees due to different diffusion mechanisms, causing different failure phenomena (50, 1200 and 4000 failure cycles for high-lead, Au-Ge solder and nanosilver respectively). Meanwhile, the reverse leakage current ( I _R ) and breakdown voltage ( V _R ) variations mainly depended on chip interface states, including the Schottky barrier lowering effect (induced by AlW IMC and large cracks generated at the Schottky contact metal layer/chip interface) and electrons and holes trapped at the SiO ₂ /4H-SiC interface in the termination zone. Finally, this article discussed three failure mechanisms observed in devices employing three die attach materials under 300°C PC.