Determining Contact Angle and Surface Energy of Co_(60)Fe_(20)B_(20) Thin Films by Magnetron Sputtering

摘要

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℃ for 1 h. The thickness (t_f) of the CoFeB thin films ranged from 100 A to 500 A. 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 A to 500 A, the surface energy at RT decreases from 40 mJ/mm~2 to 32 mJ/mm~2. During post-annealing treatment, the surface energy increases from 32 mJ/mm~2 to 35 mJ/mm~2, as t_f increases from 100 A to 300 A; then it decreases to 31 mJ/mm~2, as t_f increases from 300 A to 500 A. The surface energy of the as-deposited CoFeB thin films exceeds that during post-annealing treatment at thicknesses of 100 A and 200 A, suggesting that as-deposited CoFeB thin film increases the adhesion.