Jiao Luo

The microstructure is an important key factor for the reliability of deep through silicon via (TSV) electroplated copper. In the present study, the influence of current density on the surface physical field and microstructure in the electroplated copper were discussed using a combined method of numerical simulation and experiment. The results showed that the optimal electroplated parameters with the defect-free filling were confirmed to be at 0.1-0.17 Ampere per Square Decimeter (ASD) with an accelerator-to-suppressor ratio of 1:10 when the size of deep TSV was Φ20 μm × 200 μm with an aspect ratio of 10:1. The microstructure of TSVs exhibited a distinct distribution feature: fine grains along sidewalls and at the mouth, large columnar grains in mid-regions, and equiaxed grains at the bottom. The grain size and the quantity of Σ3 twin boundaries first decreased and then increased with increasing current density due to the competing effect of nucleation rate and grain growth by governing the polarization and suppressor desorption. Moreover, the intermediate 9R structure between the matrix and the twin was first observed in the electroplated copper, which provided a new way for strain accommodation in deep TSV electroplated copper, and the matrix→9R→twin pathway was proposed through the slip of Shockley partial dislocations. These findings served as a valuable reference for modeling microstructure evolution and laid a foundation for both microstructure prediction and control in deep TSV electroplated copper.

In this paper, the hot tensile deformation of a GH3230 superalloy double-sheet was conducted under deformation temperatures ranging from 1123~1273 K and strain rates ranging from 0.001~0.2 s⁻¹. The flow behavior of the GH3230 superalloy double-sheet was analyzed in detail. The hot tensile deformation process of the GH3230 superalloy double-sheet includes four stages of elastic deformation, strain hardening, steady state and fracture. The true stress decreases with the increasing deformation temperature and decreasing strain rate. The variation of the strain rate sensitivity index and strain hardening index with processing parameters were discussed. The average apparent activation energy for hot tensile deformation is 408.53 ± 46.96 kJ·mol⁻¹. A combined Johnson-Cook and Hensel-Spittle model considering the couple effect of strain hardening, strain rate hardening and thermal softening was established to describe the hot tensile behavior of the GH3230 alloy double-sheet. Compared to Johnson-Cook model and Hensel-Spittle model, this model has the highest predicting accuracy. The average absolute relative error of true stress between the experimental and the predicted is only 2.35%.