Chemical effects in chemical mechanical planarization of TaN: investigation of surface reactions in a peroxide-based alkaline slurry using Fourier transform impedance spectroscopy

TaN and Ta are used as diffusion-barriers for Cu interconnects in semiconductor microchips, and both these materials are patterned using the technique of chemical mechanical planarization (CMP). In the present work, we find satisfactory polish rates (∼120 nm/min) for both Ta and TaN by employing an...

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Bibliographic Details
Published inMaterials letters Vol. 59; no. 6; pp. 690 - 693
Main Authors Gorantla, V.R.K., Emery, S.B., Pandija, S., Babu, S.V., Roy, D.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.03.2005
Subjects
CMP
Electronic materials
Impedance spectroscopy
Surfaces
Tantalum
Tantalum nitride
Surfaces
Electronic materials
Tantalum
Impedance spectroscopy
Tantalum nitride
CMP
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Summary:TaN and Ta are used as diffusion-barriers for Cu interconnects in semiconductor microchips, and both these materials are patterned using the technique of chemical mechanical planarization (CMP). In the present work, we find satisfactory polish rates (∼120 nm/min) for both Ta and TaN by employing an alkaline slurry containing H 2O 2 and mixed abrasive particles. By combining potentiodynamic measurements with Fourier transform electrochemical impedance spectroscopy (FT-EIS), we show that the chemical mechanism for CMP of TaN is essentially identical to that we recently reported for Ta. This mechanism is governed by catalytic decomposition of H 2O 2 at the TaN–slurry interface, which leads to a local increase in the interfacial pH, and consequently, leads to conversion of Ta-oxide surface sites into soluble hexatantalate anions.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0167-577X
1873-4979
DOI:10.1016/j.matlet.2004.11.010