Evaluating Local Elasticity of the Metal Nano-films Quantitatively Based on Referencing Approach of Atomic Force Acoustic Microscopy

• Published in: Chinese journal of mechanical engineering Vol. 25; no. 6; pp. 1281 - 1286
• Main Authors: Zhang, Gaimei, He, Cunfu, Wu, Bin, Chen, Qiang
• Format: Journal Article
• Language: Chinese; English
• Published: Beijing Chinese Mechanical Engineering Society 01.11.2012; Springer Nature B.V; College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology,Beijing 100124, China; Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 102600, China%College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology,Beijing 100124, China%Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 102600, China
• Edition: English ed.
• Subjects: Acoustic microscopy; Atomic force microscopy; Bulk modulus; Copper; Elastic properties; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Engineering Thermodynamics; Glass; Heat and Mass Transfer; Indentation; Instrumentation; Machines; Manufacturing; Mathematical analysis; Mechanical Engineering; Microscopy; Modulus of elasticity; Nanoindenters; Power Electronics; Processes; Sensitivity analysis; Stiffness; Theoretical and Applied Mechanics; Thickness; Vibration measurement; Zinc; 光谱测量; 原子力; 声学显微镜; 定量评估; 弹性模量; 纳米压痕; 纳米薄膜; 金属; local elasticity; atomic force acoustic microscope(AFAM); contact stiffness; referencing approach
• ISSN: 1000-9345; 2192-8258
• DOI: 10.3901/CJME.2012.06.1281

Traditional technique such nanoindenter（NI） can＇t measure the local elastic modulus at nano-scale（lateral）. Atomic force acoustic microscopy （AFAM） is a dynamic method, which can quantitatively determine indentation modulus by measuring the contact resonance spectra for high order modes of the cantilever. But there are few reports on the effect of experimental factors, such length of cantilever, contact stiffness on measured value. For three different samples, including copper（Cu） film with 110 nm thickness, zinc（Zn） film of 90 nm thickness and glass slides, are prepared and tested, using referencing approach in which measurements are performed on the test and reference samples （it＇s elastic modulus is known）, and their contact resonance spectra are measured used the AFAM system experimentally. According to the vibration theory, from the lowest two contact resonance frequencies, the tip-sample contact stiffness is calculated, and then the values for the elastic properties of test sample, such as the indentation modulus, are determined. Using AFAM system, the measured indentation modulus of copper nano-film, zinc nano-film and glass slides are 113.53 GPa, 87.92 GPa and 57.04 GPa, which are agreement with literature values Mcu--105-130 GPa, Mzn = 88.44 GPa and Molass = 50-90 GPa. Furthermore, the sensitivity of contact resonance frequency to contact stiffness is analyzed theoretically. The results show that for the cantilevers with the length 160 pm, 225 μm and 520 μm respectively, when contact stiffness increases from 400 N/m to 600 N/m, the increments of first contact resonance frequency are 126 kHz, 93 kHz and 0.6 kHz, which show that the sensitivity of the contact resonance frequency to the contact stiffness reduces with the length of cantilever increasing. The novel method presented can characterize elastic modulus of near surface for nano-film and bulk material, and local elasticity of near surface can be evaluated by optimizing the experimental parameters using the AFAM system.