Glycolic acid in hydrogen peroxide-based slurry for enhancing copper chemical mechanical polishing Tzu-Hsuan Tsai a, * , Yung-Fu Wu b , Shi-Chern Yen b a Department of Chemical Engineering, Northern Taiwan Institute of Science and Technology, No. 2, Xueyuan Rd., Beitou, Taipei 112, Taiwan, R.O.C. b Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan Received 14 August 2004; accepted 30 October 2004 Available online 19 November 2004 Abstract The effects of glycolic acid (GCA) added into hydrogen peroxide (H 2 O 2 ) or urea-hydrogen peroxide (U-H 2 O 2 ) slurries on Cu-CMP performance were investigated. Experiments showed that GCA could prevent H 2 O 2 or U- H 2 O 2 from rapid decomposition and increase the active peroxide lifetime of the slurries. In addition, electrochemical studies from polarization and impedance experiments verified that copper removal efficiency could be enhanced by use of GCA. Meanwhile, a valid equivalent circuit for Cu-CMP system was proposed, and the fitting results provided a good index to surface planarization. Furthermore, GCA could shorten the range of isoelectric points between Cu film and a-Al 2 O 3 abrasives. After a post cleaning, the particle contamination thus could be reduced due to the elec- trostatic repulsion. Our study proved that adding GCA into the U-H 2 O 2 slurries with BTA could further improve the Cu-CMP performance. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Glycolic acid; Urea-hydrogen peroxide; Slurry; Copper; Chemical mechanical polishing 1. Introduction Chemical mechanical polishing (CMP) of metal is widely recognized as the key technique to obtain global planarization for copper multilevel inter- connection in IC manufacturing [1]. However, the planarization mechanisms of metal CMP in- volve complicated chemical reactions and physical actions. So it is difficult to control the CMP per- formance, especially for a high corrosion-sensitiv- ity metal like Cu. According to different slurry components, the planarization mechanisms of me- tal CMP can be summarized as the following two types. The first one is that the metal surface may be polished with a dissolution-type slurry in which no surface film forms. In this case, the CMP 0167-9317/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2004.10.008 * Corresponding author. Tel.: +886228927154x8041; fax: +886228960255. E-mail address: tzhtsai@ntu.edu.tw (T.-H. Tsai). Microelectronic Engineering 77 (2005) 193–203 www.elsevier.com/locate/mee