Wafer Bonding for the Next Generation of Applications

(27:08 + Q&A) Dr. Viorel Dragoi, EV Group E. Thallner GmbH
From the First IEEE Hybrid Bonding Symposium 
Summary: Hybrid wafer-to-wafer bonding gained over the past decade a significant interest as it can provide major advantages in fabrication of wafer-level interconnects. The process is extremely challenging in terms of surface preparation, as substrates must accommodate two types of bonding processes simultaneously (dielectric-dielectric low temperature fusion bonding and Cu-Cu thermo-compression bonding localized at bonding pad level). The fabrication of the bonding surfaces has to consider a specific topography (metal recess with respect to dielectric surface within single digit nanometers, dielectric surface with very low microroughnes – less than 0.5 nm, etc,) with very high uniformity across 300 mm diameter wafers. The bonding process must ensure a high alignment accuracy (sub-micrometer) across the entire wafer and low temperature processing, within the CMOS thermal budget (<400°C). After the bonding process one of the two bonding partners has to be thinned down: in case the substrates preparation was not performed according to specifications or the bonding process was not properly performed, the structures on the wafer will be distorted, making further processing more difficult, time consuming and adding costs. Thus, substrates quality and accurate bonding process control are of a very high importance
An overview of the main aspects related to hybrid bonding will be presented. The main specifications and some of the main challenges of this technology will be reviewed with respect to their impact on process results. The importance of new metrology and investigation methods adoption will be emphasized.
Bio: Viorel Dragoi graduated in the Faculty of Physics at University of Bucharest in 1995 and received his PhD from the Institute of Atomic Physics Bucharest, Romania, in 2000, with a thesis on low temperature wafer bonding. He was working in National Institute of Materials Physics, Bucharest, as process technician and later as junior scientist. In 1998 he joined Max Planck of Microstructure Physics, starting his work on wafer bonding in the group of professor Ulrich Gösele. After finishing his PhD he joined EV Group in 2001 as a wafer bonding technology process engineer and product manager for fusion wafer bonding equipment. His activities were focusing since then on process development based on wafer bonding with applications in MEMS and 3D integration. He is currently Chief Scientist for permanent wafer bonding and the manager of the Technology Development team at EV Group headquarters in Austria. He is author and co-author of over 150 papers published in scientific journals, proceedings volumes, magazines and book chapter contributions.

For other edited  videos from this symposium, visit  https://attend.ieee.org/hbs/?page_id=456