Room-Temperature Ultrasonic Bonding of Semiconductor Thin-Dies with Die Attach Films on Glass Substrates

Abstract

A novel ultrasonic bonding technique for semiconductor thin-dies laminated with die attach films (DAFs) is proposed to improve the process window and to increase the throughput limited intrinsically in the state-of-the-art thermocompression bonding technique. The proposed technique involves the introduction of ultrasonic vibration energy generated from an ultrasonic transducer to the DAFs underneath the thindies so as to adhere the thin-die-DAF laminates onto the substrates. In this paper, a 40 kHz piezoceramic ultrasonic transducer is developed and integrated with a mechatronic test bed to form an automated equipment model for the ultrasonic thin-die bonding. Process studies are conducted to bond 50 mm thick thin-dies with 10 mm thick DAFs on glass substrates using the ultrasonic and thermocompression techniques. The results show that the ultrasonic technique can effectively reduce the process temperature and time as required by the thermocompression technique. Ultrasonic bonding at room temperature (25 C) is achieved with a process time of 2 s and an ultrasonic power of 150 W. Comparable bondability can only be obtained using thermocompression bonding at temperatures in excess of 120 C.