Magnetic thin film inductors for integrated circuit applications

It is extremely difficult to fabricate small air-core inductors of sufficiently high inductance and Q for integrated-circuit applications due to the large number of turns required. Although the need for passive inductors can be circumvented by means of active filters at lower frequencies, such substitutes are difficult to realize at frequencies above 100 MHz. To drastically reduce the number of turns required thus rendering the fabrication of IC inductors feasible, we used anisotropic magnetic film cores of permeability as high as 10⁴. In this paper, the design and fabrication of such inductors are discussed along with experimental results on their inductance.