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Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received November 12, 2010
Accepted January 28, 2011

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Investigation of cleaning solution composed of citric acid and 5-aminotetrazole

Oh Joong Kwon Jae Han Bae¹ Bum Koo Cho² Yung Jun Kim² Jae Jeong Kim^2†

Department of Energy and Chemical Engineering, University of Incheon, 12-1 Songdo-dong, Yeonsu-gu, Incheon 406-772, Korea ¹LG Display Co., Ltd., 1007, Deogeun-ri, Wollong-myeon, Paju-si, Gyeonggi-do 413-811, Korea ²School of Chemical and Biological Engineering, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-744, Korea

jjkimm@snu.ac.kr

Korean Journal of Chemical Engineering, July 2011, 28(7), 1619-1624(6), 10.1007/s11814-011-0023-7

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Abstract

In a damascene process for a copper metallization, the planarization method based on a chemical mechanical polishing (CMP) has been used for multilevel metallization. Although a buffing step was adopted in this CMP process, numerous residual abrasives, capable of increasing the resistance of copper lines, still existed after the second CMP step. For this reason, more research has focused on identification of an effective cleaning solution. We investigated a new cleaning solution consisting of citric acid and 5-aminotetrazole (ATRA) as a complexing agent and corrosion inhibitor, respectively. The citric acid was added to achieve a lift-off effect by removing the underlying copper oxide layer, whereas the ATRA was adopted to prevent abrasive re-adsorption by forming a passivation layer on the copper surface. The cleaning solution consisting of 0.006M citric acid and 0.006M ATRA displayed a particle density of 0.07 #/μm2 in an immersion test, and no particles were observed on a 4 cm2 coupon wafer in a real process test at pH 12.

Keywords

Cleaning Solution Citric Acid 5-Aminotetrazole Particle Density Etch Rate

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