Papers by Author: Chang Wook Baek

Abstract: We have designed and fabricated diamond-shaped AFM cantilevers capable of performing multi-functioning tasks by using single crystal silicon (SCS) micromachining techniques. Structural improvement of the cantilever has clearly solved the crucial problems resulted from using conventional simple beam-AFM cantilever for mechanical testing. After forcecalibration of the cantilever, indentation tests are performed to determine the mechanical behaviors in micro/nano-scale as well as topographic imaging. A diamond Berkovich tip of which radius at the apex is approximately 20 nm is attached on the cantilever for the indentation test and 3D topography measurement. The indentation load-depth curves of nano-scale polymeric pattern (PAK01-UV curable blended resin) are measured and surface topography right after indenting is also obtained. Development of this novel cantilever will extend the AFM functionality into the highly sensitive mechanical testing devices in nano/pico scale.

Abstract: In this study, we use the strip-bending test to measure the residual stress of a thin film structure. The principle of the strip bending test and the test procedures are described and the analysis of the strip deformation is presented. The explicit formula for estimating the residual stress is given, which requires the initial stress as an input. As an example, the E-beam evaporated Au thin film is chosen, and the residual stress is measured by the present method. The Au thin film structure has a tensile or compressive residual stress depending on the film thickness. The tensile and the compressive residual stresses of Au thin film are successfully measured by the present method.

Abstract: Atomic force microscope (AFM) is a powerful tool for exploring a nano-scale world. It can measure a nano-scale surface topography with very high resolution and detect a very small force. In this paper, we propose a novel AFM cantilever and its calibration scheme to utilize AFM as a mechanical testing machine. We call this AFM with a new cantilever as a force-calibrated AFM. The feasibility of the AFM cantilever is validated through measurement of mechanical properties of freestanding Au thin films.