Measurement of static and dynamic mechanical behavior of micro and nano-scale thin metal films: using micro-cantilever beam deflection

Abstract

We present the results of a novel micro-beam deflection test used to investigate the static and dynamic mechanical behavior of submicron-thick metal films. The method demonstrated in this study allows researchers to observe the motion of micro and nano-scale thin films responding to electrostatic loads, by means of laser reflection measurements at frequency rates of up to 500 Hz. Researchers fabricated a supporting frame and a novel triangular shaped ‘‘paddle'' beam designed to provide uniform plane stress distribution while undergoing deflection. A simple geometric calculation, based on cantilever deflection, enabled the degree of strain to be determined, which in turn provided the Young's modus for aluminum film of a given thickness. We also studied the dynamic behavior using the dynamic frequency response of the beam, generated by electrostatic forces under various loads and vacuum pressure conditions. Our results showed that air damping has a significant influence on the free damping behavior of specimens, and only a minor influence on damping frequency. We determined the loss angle and frequency using sweep frequency and free damping methods, which were very consistent with paddle resonant frequencies. The loss angle obtained from a simple silicon micro-beam was 2.001 9 10-4_using the free damping method and 2.23 9 10-4_using the sweep frequency method. The dynamic response loss mechanism measured in this experiment provides incentive for the further study of grain boundary motion and dislocation motion in thin films

A Comparative Study on the Elastic Characteristics of an Aluminum Thin-Film Using Laser Optical Measurement Techniques

“…It was reported, however, that the elastic modulus measured by a cantilever microbeam test was close to that in the parallel direction to the film surface [23]. The bulk property of pure Al is 65-70 GPa in general [24], but the Young's moduli of Al in the form of a thin-film from literature [3,7,11,[24][25][26][27][28][29][30][31][32][33] lie mostly between 55 and 81 GPa, as shown in Figure 9. Outliers are observed such that the results reported by Reddy et al [7] using a lateral resonator show very large scatter from 33 to 102 GPa.…”

Measurement of the Young’s modulus using micro-cantilevered beam actuated by electrostatic force

“…After recording the beam deflection and the applied load, the Young's modulus can be derived from the function about the two parameters, which involves factors such as geometrical quantities, elastic properties, applied loads, and displacements. Loads can be applied by different means: AFM [4,5], a probe attached to a micro-force testing machine [6], or electrostatic actuation [7]. Furthermore, the Young's modulus can be measured through a tensile test, which uses a comb-drive electrostatic actuator to generate a uniaxial tensile force and two capacitive sensors to measure the tensile force and displacement, respectively [8].…”