TSV MEOL (Mid-End-Of-Line) and its Assembly/Packaging Technology for 3D/2.5D Solutions

Increasing demand for new and more advanced electronic products with a smaller form factor, superior functionality and performance with a lower overall cost has driven semiconductor industry to develop more innovative and emerging advanced packaging technologies. One of the hottest topics in the semiconductor industry today is a 3D packaging using Through Silicon Via (TSV) technology. Driven by the need for improved electrical performance or the reduction of timing delays, methods to use short vertical interconnects have been developed to replace the long interconnects found in 2D packaging. The industry is gearing up to move from technology path finding phase for TSV into commercialization phase, where economic realities will determine the technologies that can be adopted. Choosing the right process equipment and materials, combined with innovative design solutions addressing thermal and electrical issues will be the key success factors. The synergies and intersections among three parallel developing areas of packaging technology i.e. traditional die and package stacking on substrates, fanin and fan-out wafer level packaging and 3D Si integration and the resulting future path for packaging technology is quite critical for future microelectronics packaging. This paper addresses TSV MEOL processes as well as TSV assembly/packaging process. The status of “bridge” technologies such as interposers and TSV substrates as an interim play prior to full productization of the active Si TSV approach is reviewed with specific examples of configurations approaching volume production in real products. Latest developments in the key elements of 2.5D/3D TSV integration such as TSV backside via revelation, CMP/planarization, wafer thinning, micro bumping. For TSV assembly/packaging, thin die handling, dicing and microbump bonding, underfill characterization will be discussed. TSV Packaging challenges and experimental results will be presented for thermocompression bonding with ultra fine pitch microbump interconnections in this paper. In addition, TSV business model/supply-chain challenges including logical hand off points among silicon fab foundries and OSAT (outsourced semiconductor assembly and test) are presented.