Micro-pattern Corrosion Screening on Bimetallic Corrosion for Microelectronic Application Kyle Kai-Hung Yu a , Sirish Rimal a , Muthappan Asokan a , Praveen R. Nalla a , Simon Koskey a , Karthikeyan S.M. Pillai a , Oliver Chyan a, *, Kanwal Jit Singh b , Satyarth Suri b a Interfacial Electrochemistry and Materials Research lab, Department of Chemistry, University of North Texas, Denton, TX 76203, USA b Components Research, Intel Corporation, Hillsboro, OR 97124, USA A R T I C L E I N F O Article history: Received 1 March 2016 Received in revised form 27 May 2016 Accepted 28 May 2016 Available online 28 May 2016 Keywords: Microscopic corrosion Bimetallic corrosion Ammonium citrate Fluorocarbon residues Corrosion inhibitor A B S T R A C T The continued miniaturization of the integrated circuit, leading to minute dimensions (< 10 nm) in microelectronic architecture, can greatly accelerate the on chip corrosion into a severe reliability threat. Particularly, various interfaces between multilayered film stacks create dissimilar contacts with significant galvanic potential difference. This can promote on-chip corrosion under semiconductor processing conditions. In this paper, an efficient micro-pattern corrosion screening metrology combined with electrochemical and x-ray photoelectron scattering techniques, is utilized to study bimetallic corrosion and its inhibition in wafer cleaning solutions. Cu/Ru bimetallic contact was found to exhibit a higher corrosion rate than the Cu/Ta contact. In alkaline ammonium citrate solution, higher dissolved oxygen content significantly accelerated Cu corrosion. The increased alkalinity (pH > 12) at Cu/Ru interface, caused by enhanced oxygen reduction reaction on Ru, is proposed to generate more NH 3 for sustaining fast Cu corrosion. Effects of different plasma chemistries like CF 4 , CF 4 + O 2 , CH 2 F 2 , C 4 F 8 and SF 6 on the Cu corrosion in tetramethylammonium hydroxide (TMAH) were also investigated. Plasma treatments using higher fluorine content gases showed higher Cu corrosion rate in TMAH. Benzotriazole showed limited corrosion inhibition to plasma treated Cu/Ru micro-patterns in pH 14 TMAH solution. Contrastingly, pyrazole demonstrated as an effective corrosion inhibitor suppressing Cu corrosion rate down to the desirable < 1 A  /min level. ã 2016 Published by Elsevier Ltd. 1. Introduction In modern integrated circuit (IC) design, the copper inter- connects play a key role as the digital communication superhigh- way between nanometer size transistors (< 10 nm) on a silicon chip and the external analog functions like audio/visual displays and touch screens. Due to the inability to directly pattern Cu by reactive ion etching (RIE), the intricate Cu interconnects are fabricated indirectly using a damascene patterning process [1]. As highlighted in Fig. 1, the damascene patterning process involves creating a trench/via pattern into a porous low k dielectric film by plasma-assisted RIE, followed by bottom up Cu electrodeposition (ECD) on a barrier/liner/Cu seed over layer, and subsequent removal of the Cu overburden by chemical-mechanical planariza- tion (CMP) [1–4]. Finally, post-CMP cleans are needed to completely remove organic and inorganic contaminants left over after the CMP polishing process. As IC device structures scale down to <10 nm nodes, even a minute materials losses from wafer cleaning can readily impact the device performance through critical dimension (CD) changes and film modification [5]. In particular, exposure to corrosive CMP and cleaning chemicals cause microscopic Cu bimetallic corrosion defects across Cu/barrier/ULK interfaces, which can be highly detrimental to device reliability and production yield [6–8]. The decreasing dimension of copper interconnects can further exacer- bate the corrosion damage, as a 20  20  100 nm Cu line has a mass of 3.6  10 16 grams can be completely corroded with an oxidation charge of only 1 pC. Furthermore, the evolving complex microfabrication processes used for making next generation IC devices results in various dissimilar Cu contacts exposed to complex chemical environments, making identification and prevention of microscopic on-chip bimetallic corrosion a techno- logically challenging task. In this paper, a new micro-pattern corrosion screening metrology was developed to study Cu bimetallic corrosion in post * Corresponding author. E-mail address: Chyan@unt.edu (O. Chyan). http://dx.doi.org/10.1016/j.electacta.2016.05.189 0013-4686/ã 2016 Published by Elsevier Ltd. Electrochimica Acta 210 (2016) 512–519 Contents lists available at ScienceDirect Electrochimica Acta journal homepa ge: www.elsev ier.com/locate/electacta