Effects of Properties and Growth Parameters of Doped and Undoped Silicon Oxide Films on Wear Behavior During Chemical Me
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Ashok Kumara) Nanomaterials and Nanomanufacturing Research Center, and Department of Mechanical Engineering, University of South Florida, Tampa, Florida 33620
S. Thagella Nanomaterials and Nanomanufacturing Research Center, and Department of Industrial Engineering, University of South Florida, Tampa, Florida 33620
Jiro Yota Advanced Process Technology, Skyworks Solutions, Inc., Newbury Park, California 91320 (Received 25 August 2003; accepted 31 October 2003)
Understanding the tribological, mechanical, and structural properties of an inorganic and organic dielectric layer in the chemical mechanical planarization (CMP) process is crucial for successful evaluation and implementation of these materials with copper metallization. Polishing behaviors of different carbon- and fluorine-doped silicon dioxide (SiO2) low dielectric constant materials in CMP process are discussed in this paper. Films were deposited using both chemical vapor deposition and spin-on method. Carbon and fluorine incorporation in the Si–O network weaken the mechanical integrity of the structure and behave differently in slurry selective to SiO2 films. Mechanical properties of the films were measured using depth-sensing nanoindentation technique, and it was found that undoped SiO2 film has the highest and spin-on carbon-doped oxide films have the lowest hardness and modulus values. Wear behavior of the doped SiO2 is studied in a typical SiO2 CMP environment, and results are analyzed and compared with those of the undoped SiO2 films. Coefficient of friction and acoustic emission signals have significant effect on the polishing behavior. Surface of the films are investigated before and after polishing using atomic force microscopy. Roughness and section analysis of the films after polishing show the variation in wear mechanism. Validation of Preston’s equation is discussed in this study. Additionally, different wear mechanisms are presented, and a two body abrasion model is proposed for the softer films.
I. INTRODUCTION
In comparison to conventional planarization technologies such as bias sputtering, dry etching, and etch-back processes, chemical mechanical planarization (CMP), or, offers more versatility, simplicity, and better global planarization, and can be applied to all types of materials.1 The CMP process synergistically combines both tribological and chemical effects to planarize metal like copper, tungsten, and insulating materials such as silica and
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0130 996
http://journals.cambridge.org
J. Mater. Res., Vol. 19, No. 4, Apr 2004 Downloaded: 13 Mar 2015
polymers.2–5 In chemical mechanical planarization, very thin materials (艋5 m) have to be removed with high precision while maintaining precise control on the remaining thickness.1 CMP is a tribochemical process involving few basic components in which mechanical wear is accelerated by a chemical reaction and further induced by friction. Often, a change in slurry or operating conditions lead
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