  Planar strip inductors consisting of two Fe-N films enclosing a conducting
film made of Cu, were fabricated on oxidized Si substrates. The inductors were
1mm long, 2 to 100 um wide, with layers of thickness ~0.1 um for the magnetic
films and ~0.5 um for the conductor. The soft (Hc=4-8 Oe) magnetic layers were
biased during impedance measurement by applying an external field along the
strip length thereby facilitating the transverse susceptibility configuration.
Biased strips exhibited 70 to 100% inductance enhancement at 1GHz with quality
factors Q=4.5 to 3, respectively. The magnetic contribution to the total flux
in the narrow devices was less than predicted theoretically, which was
attributed to hardening of the magnetic material at the edges of the strip,
where the deposition was close to 60 degree incidence. Test films were
fabricated on tilted substrates and found to develop a very high anisotropy (up
to 1 kOe) for deposition angles larger than 30 degrees. Optimizing the flux
closure at the strip edges and using thicker conductor layers is essential for
further improving the performance of sandwich strip inductors.
