기능성 나노 박막의 기계적 강도 평가법

Abstract

Coating deposition process is used to give functional properties to surfaces in various industries such as semiconductors, displays and batteries. Especially, semiconductor industries are studying thin film formation processes to improve high level of integration. Although the increasing use of thin films, reliability issues are increasing because of difficulties in determinate mechanical properties of thin films. Various studies have been conducted to determinate the properties of thin films, and most of them are made in a way that is not affected by the thickness of the specimen. However, there are limitations in determinate thin film properties due to difficulties in making specimens, material of the substrate, and local measure. In this paper, nano cutting methods and customized system are suggested to determinate the properties of thin films. Based on Merchant's metal cutting theory, the resistance generated by the material cutting is secured with shear strength and shear strain, and the adhesive force between film and substrate is measured. In the fracture mechanism of film, shear strength is expressed as crack, and adhesion is expressed as delamination of film. Bulk polycarbonate cutting was carried out for verification of nano cutting system and proceeded in horizontal and diagonal directions. 71MPa with horizontal cutting and 75MPa with diagonal cutting were measured, and the change in cutting direction does not affect the difference in strength. A specimen produced by three types of deposition processes was prepared for the application of nano cutting system. The first was an electroplating used to make copper wiring in the PCB, which was measured by making specimens with three thicknesses. The shear strengths were 300 MPa, similar to the yield strength of copper. The second was copper sputtering thin film with a thickness of 100 nm. The measurement results showed a 30% improvement in strength compared to electro-copper plating, and an improvement in strength due to differences in grain size. The third is a polymer organic thin film with a hydrophobic surface. We prepared p(PFDMA) thin film with hydrophobic characteristics and p(PFDMA-co-DVB) with higher durability. Cutting tests have been carried out to measure quantitative durability, and more durable p (PFDMA-co-DVB) has a threefold strength improvement. As a result, three types of thin films were measured, and the mechanical reliability of thin films was ensured through the newly proposed nano cutting system.