Superparamagnetic, nanocrystalline cobalt ferrite thin films as magnetic core of integrated RF inductors

Using microwave-assisted synthesis in the solution medium, superparamagnetic, nanocrystalline cobalt ferrite thin films have been deposited on integrated inductors to increase inductance density. Cobalt ferrite thin films (CFTF), similar to 820 nm thick, can be deposited in 10 min at similar to 190 degrees C, making the process CMOS-compatible. The as-prepared CFTF has a saturation magnetization (M-S) of 238 emu/cc and coercivity (H-C) of 32 Oe at room temperature for a particle size of similar to 8 nm. The inductance of an on-chip inductor increased from 7.1 nH to 9.9 nH at 5 GHz when the CFTF was deposited on it, an enhancement of nearly 40%.