A study of the challenging issues in 3D-IC technologies

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Three-dimensional (3D) integration has emerged as a potential solution to overcome the obstacles on chip performance, power dissipation and packaging form factor. Silicon chips can be vertically stacked and interconnected with the use of through silicon vias (TSVs), which enables a new dimension for device integration and significantly increases device density. However, there are two major reliability concerns associated with the 3D IC technologies. One is caused by the coefficient of the thermal expansion (CTE) mismatch between the metal in TSV and surrounding Si, which will lead to connection failures. The other one is the performance degradation of high frequency signals in 3D ICs. The coupling among TSVs and interconnects in the substrate can significant affect the high frequency signal quality. Attempts have been made to study and characterize these effects. However, most of the simulation models developed in this field were focused on analyzing individual elements instead of full-chip/package, and were not validated with experimental measurements. In this research project, we propose to study the reliability issues in 3D full-chip/package using calibrated models and experimental approaches. 3D IC test chips will be prepared by the industrial partner and the applicants. Various dedicated test structures will be developed and placed in the test chip to study the strain and high frequency performance. The hard X-ray micro-diffraction (XRD) facility at the VEPERS beamline, Canadian Light Source (CLS) and the Raman micro-spectroscopy (µRS) equipment at the Saskatchewan Structural Science Centre (SSSC) will be used to experimentally study the strain in the test samples. The proposed project will enable Canadian companies fully take the advantages of the 3D IC technologies without sacrificing the reliability performance. At the same time, it will enhance the capability and expertise of the research group at the University of Saskatchewan. During the project period, two Ph.D. and one summer students will participate in the proposed collaborative research project, which will enable the trainees to develop both theoretical and experimental methods to solve the challenging problems from industry.