摘要
With the drastic reduction of the TSV diameter leading to a critical dimension comparable to the Cu-filled grain size,the grain condition strongly influences the thermo-mechanical behavior of the TSV.In this work,the TSV-Cu cross-section with different grain sizes is characterized by EBSD,confirming that the sidewall grain size(0.638–1.580μm)is smaller compared to other regions(1.022–2.134μm).A finite element model(FEM)considering copper grains is constructed by using Voronoi diagrams to investigate the effect of sidewall grain size as well as area on the thermo-mechanical behavior during annealing.The material parameters in the FEM are optimized through nanoindentation inversion and considering the mechanical property anisotropy of copper grains.The yield strengthσy and hardening exponent n of TSV-Cu are 74.6 MPa and 0.514.The simulation results indicate that the protrusion of TSV-Cu after annealing tends to increase initially and then decrease with smaller sidewall grain size and area.The maximum increase in protrusion caused by the two variables can reach 6.74%and 14.6%,respectively,relative to the average grain condition.Additionally,the simulation results were validated by quantifying grain boundaries in TSV-Cu samples with varying grain sizes.
基金
supported by the Major Program(JD)of Hubei Province(No.2023BAA008)
the National Key R&D Program of China(No.2022YFB3207100)
the Hubei Provincial Strategic Scientist Training Plan(No.2022EJD009)
the Fundamental Research Funds for the Central Universities(No.2042023kf1041).
