Room-temperature high-density interconnection using ultrasonic bonding of cone bump for heterogeneous integration

We show that room temperature bonding of a 332 × 268 bump array can be realized by using ultrasonic bonding of cone-shaped bump. 25 μm-pitch area array of cone-shaped Au bump was fabricated on a Si wafer by using a photolithography and electroplating. A conventional planar electrode made of electroplated Au was used as the counter electrode. Ultrasonic bonding was carried out at room temperature in ambient air. Electrical connection test shows all bump connections with low resistance have been achieved. Heterogeneous integration of a photodiode array on InP and Si CMOS readout IC is demonstrated.