Complementary Adsorption of Binary Levelers for Highly Uniform Cu Micropillars

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• Fabrication of uniform copper (Cu) micropillars is crucial for microelectronics and advanced manufacturing.
• Controlling electrodeposition processes at the microscale presents significant challenges in achieving uniform growth.

Purpose of the Study:

• To investigate the adsorption behavior of binary levelers for highly uniform Cu micropillar electrodeposition.
• To elucidate the mechanism behind uniform Cu pillar formation influenced by leveler molecular structure and adsorption.

Main Methods:

• Electrochemical analysis including chronopotentiometry with sequential injection and linear sweep voltammetry with a rotating disk electrode.
• Microscopy, surface roughness analysis, and nitrogen concentration measurements to assess leveler adsorption and Cu pillar morphology.

Main Results:

• Pyridinium tribromide showed stronger adsorption on the Cu seed surface compared to 3-hydroxy-6-(tert-butyl)pyridine.
• Binary levelers exhibited preferential adsorption on the center and edge regions of the Cu seed.
• This selective adsorption led to the formation of highly uniform Cu micropillar profiles.

Conclusions:

• The molecular structure and adsorption behavior of binary levelers are critical for achieving uniform Cu micropillar electrodeposition.
• Preferential adsorption of levelers on specific surface regions effectively controls Cu growth, enabling precise fabrication.