Study of Microhardness and Young's Modulus of Copper Thin Film by Tip-Grit AFM Scratch Technology in Various Environments

Abstract

This paper is devoted to investigate an estimation methodology of micro hardness and Young’s modulus of reacted passivation layer of deposited copper thin film in dry and wet environment based a tip-grit atomic force microscope (TGAFM) scratch on copper thin film of silicon wafer. The TGAFM is a modification or attachment of a nanoor micron grit on the tip apex or cantilever beam of a closed-loop control AFM instrument. In this study, a diameter 800 nm SiO2 grit glued on the apex of the tip of AFM is used for experiment. Tip force model has been developed based on Hertzian model and Tresca criterion for stress-strain relationship from the geometries of scratch groove, depth and width to evaluate about microhardness and Young's modulus of copper thin film in regular air and DI-water. Experimental results show that the microhardness (H) is 1.62GPa and the Young's modulus (E) is 160.52GPa of copper thin film in DI-water environment. These mechanical properties of copper thin film is larger than the H= 1.52GPa and E= 126.04GPa for dry environment. Results of this study can be further explored to the grit force reaction on the passivation layer of copper film of chemical mechanical planarization (CMP) process development for semiconductor industry.