Ultra-Low Profile Integrated Magnetic Inductors and Transformers for HF Applications

Ultra-low profile integrated magnetic solenoid inductors and transformers were fabricated on 200 mm wafers with back end of line (BEOL) techniques. The process uses thick copper metallization, polymer coating, and laminated amorphous Co-Zr-Ta magnetic material. The substrate was thinned to obtain an inductor thickness of 150 μm. By varying the core size and winding pitch, a large set of inductance values was obtained, from 20 to 500 nH in the 1 MHz to 3 GHz frequency range. We report a record inductance surface density of 3500 nH · mm
^-2
and quality factors up to 23, and transformers with high coupling factors (>0.95).