Scaling Cu/SiCN Wafer-to-Wafer Hybrid Bonding down to 400 nm interconnect pitch
Boyao Zhang, Soon-Aik Chew, Michele Stucchi, Sven Dewilde, Serena Iacovo, Liesbeth Witters, Tomas Webers, Koen Van Sever, Joeri De Vos, Andy Miller, Gerald Beyer, Eric Beyne
Abstract
This study presents groundbreaking outcomes of 400nm pitch wafer-to-wafer (W2W) hybrid bonding connections with a Cu/SiCN bonding interface. A new test vehicle is introduced and meticulously designed for the relevant process development and studies. To ensure a precise surface topography control after CMP, a hexagonal pad grid is adopted, with dummy pads strategically placed in the unused layout areas. The design contains a large range of pad pitches from 1000nm to 400nm, accommodating both equal and unequal pad size configurations. Improved underlayer topography control emerges as a significant factor in achieving void-free bonding. Furthermore, the measured electrical data demonstrates close alignment with simulated models, encompassing resistance and capacitance. The impact of local pad-to-pad overlay error on the electrical properties of hybrid bond pads are also explored in this paper. The findings confirm the necessity for a maximum vector overlay tolerance of 100nm for 400nm pitch connections.