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The Impact of Organic Additives On Copper Trench Microstructure

Published

Author(s)

James B. Marro, Chukwudi A. Okoro, Yaw S. Obeng, Kathleen C. Richardson

Abstract

Organic additives are typically used in the pulse electrodeposition of copper (Cu) to prevent void formation during the filling of high aspect ratio features. In this work, the role of bath chemistry as modified by organic additives was investigated for its effects on Cu trench microstructure. Polyethylene glycol (PEG), bis(3-sulfopropyl) disulfide (SPS), and Janus green b (JGB) concentrations were varied during the Cu deposition. Results indicated a correlation between the JGB/SPS ratio and the surface roughness and residual stresses in the Cu. Electron backscattering diffraction (EBSD) and transmission Kikuchi diffraction (TKD) were used to study the cross-sectional microstructure in the trenches. Finer grain morphologies appeared in trenches filled with organic additives as compared to additive-free structures. Cu trench (111) texture also decreased with increasing organic additive concentrations due to more pronounced influence of sidewall seed layers on trench features. Twin density in the microstructure closely tracked calculated stresses in the Cu trenches. A comprehensive microstructural analysis was conducted in this study, on an area of focus that has garnered little attention from the literature, yet can have a major impact on microelectronic reliability.
Citation
Microelectronics Reliability
Volume
164
Issue
9

Keywords

Copper, Trenches, Microstructure, Electrodeposition, Twins, Stress, Organic Additives

Citation

Marro, J. , Okoro, C. , Obeng, Y. and Richardson, K. (2017), The Impact of Organic Additives On Copper Trench Microstructure, Microelectronics Reliability, [online], https://doi.org/10.1149/2.1131707jes (Accessed April 23, 2024)
Created June 27, 2017, Updated October 12, 2021