Test Structure to Assess Bump Shape Influence on Hybrid Bonding

Bump bonding is widely used in CMOS-MEMS integration. As compared to the other technology (planar bonding), bump bonding is more interesting for its simplicity and applicability to wide range of device types. Towards higher density and reliability improvement, the authors have designed and fabricated a test structure. Our new contribution is to intentionally structuralize shapes of bumps to not only a flat head but concave as well as convex ones, expecting better occlusion and passive alignment. To experiment our new idea, the first test structure has been fabricated to assess alignment accuracy.