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Microstructure and Texture in Copper Filled Millimeter Scale Through Silicon Vias

Published

Author(s)

Daniel Josell, Trevor Braun, Thomas P. Moffat

Abstract

The microstructure and crystallographic texture of copper electrodeposits in millimeter scale through silicon vias (mm-TSV) is characterized using electron backscatter diffraction (EBSD). The Cu deposits obtained from additive-containing CuSO4-H2SO4 electrolytes are found to be characteristic of the superconformal deposition process, with growth textures and columnar grains consistent with previous findings in smaller TSV. The microstructure, like the filling evolution it records, changes substantially with chloride concentration for the concentrations of polymer suppressor used. With chloride concentrations of 80 μmol∙L-1 and less, elongated columnar grains of Cu capture the linear motion of the local growth front during filling with a strong <110> orientation aligned with the elongated grain axes typical of deposition in chloride-containing Cu electrolytes. In the mid- and upper- via locations these columnar grains are angled upward from the sidewalls toward the center of the v-shaped growth front. In a limited region adjacent to the via bottom they extend vertically from the bottom surface. With millimolar chloride concentration, deposition also exhibits columnar grains with preferred <110> growth orientation in the lower region of the via and adjacent to the sidewalls. However, separation of the central deposit from the sidewalls results in an evolving convex geometry of the growth front and spatially varying texture in most of the deposit.
Citation
Journal of the Electrochemical Society
Volume
169

Keywords

copper, interconnect, though silicon via, superfill, electron backscatter diffraction, microstructure

Citation

Josell, D. , Braun, T. and Moffat, T. (2022), Microstructure and Texture in Copper Filled Millimeter Scale Through Silicon Vias, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/1945-7111/ac5ad8, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934099 (Accessed April 14, 2024)
Created March 17, 2022, Updated January 25, 2023