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Nanoindentation and Microstructural Evolution Studies of DC Magnetron Sputtered Chromium Nitride Thin Films A.B. Agarwal1, B.A. Rainey2, S.M. Yalisove, J.C. Bilello Center for Nanomaterials Science, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109. 1 Now at Submicron Development Center in AMD, Sunnyvale, CA. 2 Now at IBM, Burlington, VT. ABSTRACT Nanoindentation experiments have been performed to assess the mechanical behavior of chromium nitride (CrxNy) thin films sputtered in different deposition geometries and with varying Ar and N2 pressures. The hardness and elastic modulus of chromium nitrides are of great interest with regard to their applications. In the present work, two different deposition geometries, i.e. multi-substrate and confocal, were used to sputter (DC magnetron) a CrxNy layer on Si (100) wafers at varying nitrogen flow rates. The results of the nanoindentation experiments indicate that, over a similar argon and nitrogen regime, the CrxNy films grown in a multisubstrate geometry exhibit higher hardness and elastic modulus on the average than those grown in the confocal geometry. Furthermore, it was found that in the multi-substrate geometry the hardness and elastic modulus of the films were significantly higher than those in the confocally deposited films for a specific regime of the nitrogen flow rate (10-14 sccm). Finally, observations of the mechanical properties trends could be correlated with a higher degree of anisotropic stress for films grown in the multi-substrate in comparison to the confocal geometry.

INTRODUCTION The successful performance and reliability of thin films is often limited by their hardness and elastic modulus . A practical process by which to evaluate and understand the hardness and elastic modulus in relation to the deposition conditions is to deposit a coating, in this case CrxNy, under different deposition conditions that influence the coating microstructure. CrxNy is a hard coating in which the addition of nitrogen has been shown to increase the hardness of Cr [1-4]. Studies have shown that chromium nitride thin films have demonstrated beneficial characteristics as a coating material, including improved thermal stability, corrosion resistance [5], and lower friction coefficient [6]. However, several factors such as process variables and deposition techniques may affect the mechanical and structural properties (hardness, elastic modulus, residual stress, texture, grain size, etc.) of these materials. Nanoindentation has become one of the most widely used and versatile techniques for studying the hardness and elastic modulus of thin films on substrates [7]. hardness and elastic modulus measurements using nanoindentation systems are very similar to conventional mechanical testing systems. Properties are derived from load, displacement and time. But contrary to conventional mechanical testing which can only measure the hardness of the film, nanoindentation techniques can measure both the elastic modulus and the hardness [8]. Th