Deep etch-induced damage during ion-assisted chemical etching of sputtered indium–zinc–oxide films in Ar/CH 4 /H 2 plasmas L. Stafford a, ⁎ , W.T. Lim a , S.J. Pearton a , Ju-Il Song b , Jae-Soung Park b , Young-Woo Heo b , Joon-Hyung Lee b , Jeong-Joo Kim b , M. Chicoine c , F. Schiettekatte c a Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA b Department of Inorganic Materials Engineering, Kyungpook National University, Daegu, 702-701, Republic of Korea c Département de Physique, Université de Montréal, Montréal, Québec, Canada H3C 3J7 Received 14 January 2007; received in revised form 19 May 2007; accepted 24 May 2007 Available online 9 June 2007 Abstract Plasma etch damage to sputtered indium–zinc–oxide (IZO) layers in the form of changes in the film stoichiometry was investigated using Auger Electron Spectroscopy (AES). While damage resulting from pure chemical etching processes is usually constrained to the surface vicinity, ion-assisted chemical etching of IZO in Ar/CH 4 /H 2 plasmas produces a Zn-rich layer, whose thickness (∼ 50 nm) is well-above the expected stopping range of Ar ions in IZO (∼ 1.5 nm). Based on AES depth profiles as a function of plasma exposure time, it is concluded that the observed Zn enrichment and In depletion deep into the IZO film are driven by the implantation of hydrogen atoms. © 2007 Elsevier B.V. All rights reserved. Keywords: Plasma etching; Damage; Transparent conducting oxides; Implantation; Auger Electron Spectroscopy; Indium–zinc–oxide 1. Introduction The development of reliable pattern transfer processes is one of the critical issues for the integration of functional thin films relevant for applications in electronics, optoelectronics, and photonics. Among the various patterning techniques, plasma etching is preferred because it allows high resolution pattern transfer for device structures. One drawback of this method is the formation of damage upon plasma exposure that often degrades device performance. Depending on the material etched and the plasma chemistry used, the damage may take the form of point defects and their complexes, changes in near-surface stoichiom- etry, presence of residual etch products or deposition of polymers. A number of experiments have confirmed the presence of these various forms of etch-induced damage using electrical, optical, and structural characterization techniques [1–12]. For physical sputtering, depth profile measurements have indicated that the damage induced by low ion energy bombardment can extend deeper than the predicted ion stopping range because of both ion channeling and defect diffusion [9–13]. On the other hand, for pure chemical etching processes the damage is usually restrained to the surface vicinity due to the expected low diffusion coefficients under typical room-temperature etching conditions. In this work, we examine the mechanisms of plasma-induced damage to sputtered indium–zinc–oxide (IZO) films during ion-assisted chemical etching in reactive plasma chemistries. Because of their good electrical conductivity, wide transmit- tance window, large work function, excellent surface smooth- ness, and low deposition temperature, IZO films have recently emerged as a very promising material for transparent electrodes in optoelectronic devices such as liquid crystal displays, light- emitting diodes, and solar cells [14–17]. In contrast to pure chemical etching processes, it is shown that changes in the IZO film stoichiometry upon preferential desorption of group III etch products can extend much deeper than the surface vicinity. Possible mechanisms for the formation of such deep etch- induced damage are discussed. Available online at www.sciencedirect.com Thin Solid Films 516 (2008) 2869 – 2873 www.elsevier.com/locate/tsf ⁎ Corresponding author. E-mail address: sluc@mse.ufl.edu (L. Stafford). 0040-6090/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2007.05.071