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Title: An atomistic study of copper extrusion in through-silicon-via using phase field crystal models
Authors: Huang, Zhiheng
Liu, Jinxin
Conway, Paul P.
Hu, Zhuojun
Liu, Yang
Issue Date: 2016
Publisher: © IEEE
Citation: HUANG, Z. ... et al, 2016. An atomistic study of copper extrusion in through-silicon-via using phase field crystal models. Presented at the 2016 6th Electronic System-Integration Technology Conference (ESTC), Grenoble, France, 13-15 Sept. 2016.
Abstract: Three-dimensional system integration using Cu through-silicon-via (TSV) technology enables vertical interconnection of stacked dies. However, the large statistical distribution of plastic Cu extrusion, also known as Cu pumping, presents a serious reliability concern. Traditional finite element method (FEM) based thermo-mechanical modeling that neglects microstructure has been extensively attempted in order to identify the root cause of the extrusion, which yet remains unknown. This study utilizes recently developed phase field crystal (PFC) models, which resolve systems on atomic length scales and diffusive timescales, to capture the creation, destruction, and interaction of defects in polycrystalline Cu TSV structures and thereby elucidate the atomistic mechanisms of the Cu extrusion. The governing kinetic equation of the PFC model is first solved using FEM to generate Cu grains with an atomic resolution in TSVs by referring to experimental EBSD images. A shearing term is then added to the governing equation to simulate TSV deformation under shear strain. The solidification process at the atomistic scale is simulated to prepare polycrystalline TSV samples. Rotation and coalescence of grains with low mis-orientations are observed in solidification. The application of shear strain to the polycrystalline TSVs reveals the movement of defects at the atomistic scale. The defects diffuse through grain boundaries and aggregate at the edges of TSVs, where the defects become immobile. The process of rotation and coalescence of grains is found to be accelerated under the shear strain. The simulation results also suggest that the geometry of the TSVs is an important factor controlling the behavior of defect diffusion and microstructures in TSVs, and thus the mechanical behavior of TSVs.
Description: This paper is closed access. © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Sponsor: The authors acknowledge financial support from the Pearl River Science and Technology Nova Program of Guangzhou under grant no. 2012J2200074, the National Natural Science Foundation of China (NSFC) under grant no. 51004118, and Guangdong Natural Science Foundation under grant no. 20 15A0303120 II.
Version: Accepted for publication
DOI: 10.1109/ESTC.2016.7764700
URI: https://dspace.lboro.ac.uk/2134/26836
Publisher Link: https://doi.org/10.1109/ESTC.2016.7764700
ISBN: 9781509014026
Appears in Collections:Closed Access (Mechanical, Electrical and Manufacturing Engineering)

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