Scaling the manufacturing of soft magnetic inductor cores for power conversion applications from 8-inch to 12-inch wafers

On-chip voltage regulators employing high-frequency micro-machined power inductors based on integrated thin-film soft magnetic cores are a promising path for replacing the bulky, slow and inefficient off-chip voltage regulators. Yet, fabricating these inductors remains technologically and economically very challenging, since low-loss magnetic cores with thickness of at least several micrometers operating at very high frequencies (10-100 MHz) need to be integrated with a complementary metal-oxide-semiconductor (CMOS) compatible process for power conversion applications. Based on our production proven solution for cost-effective deposition of soft magnetic multilayered thin films with tunable properties on 8-inch wafers, which was previously used for manufacturing ultra-low-profile magnetic-core inductors with a record inductance density of ~3500 nH/mm
²
and peak quality factor of 26, we have made the transition from 8-inch to 12-inch wafers, and we are now ready to offer a cost-effective solution to manufacturers of on-chip voltage regulators. In this work, we investigate the magnetic properties of CoTaZr/Ta
2
O
5
, CoTaZr/CoTaZrO and CoTaZr/AlN soft magnetic multilayers fabricated by a physical vapor deposition (PVD) process on 12-inch Si and Si/500-nm-thermal-SiO
2
wafers in an industrial multi-chamber magnetron sputtering system.