Fabrication of thin film inductors using FeTaN soft magnetic films

Abstract

Planar-type thin film inductors were fabricated using FeTaN soft magnetic films. It was found that excellent soft magnetic properties (coercivity of 0.1-0.2 Oe, effective permeability of 4000, and saturation magnetization of 15 kG) could be obtained in the Fe78.8Ta8.5N12.7 films after anneals at 400-500 degrees C. The initial permeability of the films was constant up to 20 MHz. Internal-coil inductors, in which Cu coils were sandwiched by SiO2 insulator/FeTaN magnetic layers, were fabricated and their characteristics were compared with air-core inductors. The inductance was increased by a factor of 4 compared to air-core inductors. However, the high frequency characteristic was degraded due to a frequency-limited permeability of FeTaN magnetic layers. (C) 1999 American Institute of Physics. [S0021-8979(99)61508-0].