3D integration technologies for IoT applications


© Fraunhofer EMFT
Chip stack on bottom wafer

The trend towards the Internet of Things (IoT) makes heterogeneous 3D integration a key technology but also involves challenges in terms of the relevant process technologies, such as wafer bonding: the enormous pressure of competition in the area of IoT applications means that the systems have to be increasingly smaller but at the same time more capable and robust, too. In order to meet these demands, Fraunhofer EMFT signed a license agreement with XPERI Corp. in September 2016 so as to be able to incorporate ZiBond® and DBI® (Direct Bond Interconnect) in its portfolio – two of the most cutting-edge 3D integration technologies.

Both processes can be carried out at relatively low temperatures of approx. 200 °C, which impacts positively on component reliability and durability. DBI® technology involves the components being both mechanically and electrically connected after special preparatory treatment of the copper and oxide surfaces used. Since this avoids the elaborate process of throughconnecting chips, the systems can be produced more cost-effectively – a basic requirement for access to mass markets such as consumer electronics. Another advantage: the pitches (structural width and spacing) between the connections are at best reduced to just 2 μm. This enables very highly integrated systems-on-chips with enormous performance capacity – which is of particular interest in connection with high-performance applications such as processors. So-called Hybrid Memory Cubes are a trend in this area, where the memory and processor are integrated in a single 3D stack.