Recent Advances on Qualification and Reliability of Cu/SiO2 to Cu/SiO2 Hybrid Bonds for 3D ICs

International audienc

Review—Hybrid Bonding-Based Interconnects: A Status on the Last Robustness and Reliability Achievements

International audienceAbstract This paper reviews the most significant qualification and reliability achievements obtained, over the last 6 years, by the scientific community for hybrid bonding-based interconnects (HB) also called Cu-Cu or Cu/SiO2 bonding. First, the definition of words qualification, robustness and reliability are given to avoid misunderstanding about the published results. Second, the five potential threats (moisture ingress, thermomechanical stresses,electromigration, Cu diffusion, dielectric breakdown) are presented. Finally, the publications of six industrials or research and technology organizations are summarized and discussed. Most of the published data are related to qualification results (pass or fail). Few studies published in-depth studies, mainly on electromigration (Black’s parameters extraction and failure analysis) and copper diffusion (electrical and analytical characterizations). To conclude, once the manufacturing issues (surface preparation, alignment…) have been solved, this technology is robust and reliable at pitches > 1 μm as it reacts, roughly, like a conventional back-end of line (BEoL) interconnect

First in Operando SEM Observation of Electromigration-Induced Voids in TSV Structures

International audienceSince the early beginning of the integrated circuits, electromigration is a reliability issue of first interest. In 3-dimensionnal structures, electromigration is responsible for the formation of voids in lines connected to the Through Silicon Via (TSV). To our knowledge, this paper presents the first in operando electromigration experiment in a Scanning Electron Microscope (SEM) performed for 3D integration. The experimental protocol, including sample preparation and temperature regulation, is detailed. A current of 25 mA is injected in a structure heated at 350 °C for about 900 h. The evolution of voids is monitored and explained. Void growth occurs step by step, so that the microstructure may be assumed to play a major role in the depletion mechanism. The behavior of the electrical resistance is analyzed using the SEM micrograph

(Invited) Hybrid Bonding-Based Interconnects: A Status on the Last Robustness and Reliability Achievements

International audienc

Correlation Between Electromigration-Related Void Volumes and Time-to-Failure by High Resolution X-Ray Tomography and Modeling

International audienceHigh resolution synchrotron tomography has demonstrated a proportionality between electromigration induced void volume and time-to-failure in hybrid bonding based test structures. A conventional failure by voiding in long feed lines was observed. Process induced bonding voids do not affect reliability of the analyzed samples. Index Terms-Hybrid bonding-based integration, interconnect , electromigration (EM), void volume, time-to-failure, reliability, failure analysis, synchrotron, X-ray nano-tomography, finite element modeling (FEM)