Bond pad structure reliability

Bond pads typically have oxides below the metallization which act to insulate the pads from the substrate. These oxides are grown or deposited as part of the primary front-end process of the device. Different oxides are seen to have varying tolerance to the associated mechanical loading and ultrasonic scrubbing, resulting in bond pad cracking. The front-end process can thus influence bond quality. A study was done to characterize various oxides and also different metal systems consisting of aluminum and titanium tungsten alloy. The proper choice of metallization was found to give significant improvement in tolerance of bond-process-induced stresses