Search

Applications of thin films have been widely increased especially in microelectronics industry. In order to advance the development of thin film technology, measuring mechanical properties properly becomes important for the reliability of electronic devices because the difference of mechanical properties arises in small scale [1]. Existing tensile test methods have difficulties of making and handling free-standing specimens. In this paper, a novel methodology for thin films tensile testing by floating on water surface is presented. This method is capable of investigating intrinsic material properties of thin films floating on the water surface due to negligible adhesion of metal thin films with water surface which makes water surface very suitable to be used as underlying substrate for thin films tensile test. A dog-bone-shaped specimen which is E beam evaporated gold has been tested as a model material due to its inert nature and increasing demand in electronic devices. This method consists of fabricating gold thin films floating on water surface, attaching PDMS coated grips with the thin film specimen and applying tensile load through movement of linear DC motor. Accurate real time strain monitoring is ensured by digital image correlating (DIC) set up device as shown in Fig. 1. The validation of this proposed tensile method has been examined by first testing 500 nm gold films at a constant strain rate and then comparing the results with other studies [2-4]. After validating this methodology, 50 nm thin gold films were tested to study specimen thickness effects on mechanical behavior and apply for much thinner specimens. This new method can provide the direct way to measure the mechanical properties which is closer to its intrinsic properties with the convenient of handling the thin film specimens.

The surface of water provides an excellent environment for gliding movement, in both nature and modern technology, from surface living animals such as the water strider, to Langmuir–Blodgett films. The high surface tension of water keeps the contacting objects afloat, and its low viscosity enables almost frictionless sliding on the surface. Here we utilize the water surface as a nearly ideal underlying support for free-standing ultra-thin films and develop a novel tensile testing method for the precise measurement of mechanical properties of the films. In this method, namely, the pseudo free-standing tensile test, all specimen preparation and testing procedures are performed on the water surface, resulting in easy handling and almost frictionless sliding without specimen damage or substrate effects. We further utilize van der Waals adhesion for the damage-free gripping of an ultra-thin film specimen. Our approach can potentially be used to explore the mechanical properties of emerging two-dimensional materials. The mechanical testing of thin films is non-trivial, due to their very fine dimensions. Kim et al. use the inherent surface tension of water as a platform for the frictionless tensile testing of gold films, with a thickness as fine as 55 nm.

not Available.