Substrate heating effects on ferromagnetic CoFeB thin films

摘要

Damping in ferromagnetic alloys such, as Co_(40)Fe_(40)B_(20) are very sensitive to thermal effects both during deposition and post deposition. Depositions using and alloyed Co_(40)Fe_(40)B_(20) target were done on si (100) and amorphous glass substrates at room temperature up to 500°C. The samples deposited onto si (100) at 500°C crystalized into face centered cubic (110) Co_7Fe_3 whereas the samples on glass remained amorphous. The gilbert damping parameter a was reduced from .0141 to .0095 when deposited on glass however increased from .0097 to .0131 on si (100) at temperatures from 20°C-400°C. At low deposition temperatures on glass large metallic grains of 50-75nm were found. The crystallization of Co_(40)Fe_(40)B_(20) to Co_7Fe_3 at 500°C resulted in broader ferromagnetic resonance peak-to-peak line widths of 1050 Oe and increased in plane coercivity values of 200 Oe compared to 35 Oe and 5 Oe for amorphous Co_(40)Fe_(40)B_(20). Post deposition annealing of Co_(40)Fe_(40)B_(20) on si (100) from 20-350°C showed reductions in damping from .0131 to .0076 and effective magnetization increased from 11.8 kOe to 13.3 kOe.