Determining contact angle and surface energy of Co 60Fe 20B 20 thin films by magnetron sputtering

Abstract

This study examined the deposition of CoFeB thin films on a glass substrate at room temperature (RT), as well as the effects of conducting postannealing at heat annealing T A = 150 ()C for 1h. The thickness (t f) of the CoFeB thin films ranged from 100 to 500. The microstructure, average contact angle, and surface energy properties were also investigated. X-ray diffraction (XRD) revealed that CoFeB films are nanocrystalline at RT and that post-annealing treatment increases in conjunction with the crystallinity. The surface energy of the CoFeB thin films is related to adhesive strength. The CoFeB films form a contact angle of larger than 90°with water as a test liquid. This finding demonstrates that the CoFeB film is hydrophobic. As t f increases from 100 to 500, the surface energy at RT decreases from 40mJ/mm2 to 32mJ/mm2. During post-annealing treatment, the surface energy increases from 32mJ/mm2 to 35mJ/mm2, as t f increases from 100 to 300; then it decreases to 31mJ/mm2, as t f increases from 300 to 500. The surface energy of the as-deposited CoFeB thin films exceeds that during post-annealing treatment at thicknesses of 100 and 200, suggesting that as-deposited CoFeB thin film increases the adhesion. Copyright © 2011 S. K. Wang et al.