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Superconformal Copper Electrodeposition in Complexed Alkaline Electrolyte



Daniel Josell, Thomas P. Moffat


This paper examines superconformal filling of trenches during copper electrodeposition from alkaline cupric tartrate electrolyte. Extreme bottom-up filling of submicrometer damascene trenches with minimal deposition on the sidewalls and the field around them is observed in electrolyte containing the deposition rate suppressing additive bis-(3-sulfopropyl) disulfide (SPS) for applied potential near the critical potential associated with suppression breakdown. Deposits have rough surfaces and the resulting deposits contain large voids. In contrast, conformal filling of trenches is observed in electrolyte containing polyethyleneimine (PEI), the deposits exhibiting macroscopically specular, smoother surfaces, with finer scale embedded porosity revealed by scanning electron microscopy. Electrolytes containing both additives yield extreme bottom-up filling, in some cases with dense deposits at the bottoms of the features that transition to the porous structures observed for the PEI containing electrolyte. The feature filling and electrochemical measurements are discussed in the context of existing models for extreme bottom-up deposition. Evolution of suppressor breakdown coupled with the electrical response of the electrochemical cell is of central importance.
Journal of the Electrochemical Society


Josell, D. and Moffat, T. (2014), Superconformal Copper Electrodeposition in Complexed Alkaline Electrolyte, Journal of the Electrochemical Society (Accessed April 20, 2024)
Created April 3, 2014, Updated February 26, 2020