Fabrication and characterization of a planar interleaved micro-transformer with magnetic core

• We describe the process fabrication of a planar interleaved micro-transformer.
• Use of a magnetic material as core.
• Substitution of the classical wire bonding by a bridge.
• Low and high frequency characterization of the planar interleaved micro-transformer.

This paper presents the design, the fabrication and the characterization of a planar interleaved micro-transformer with an Yttrium Iron Garnet (YIG) core. The design of this micro-transformer and the manufacturing steps are presented. HFSS software is used for the conception and the simulation of the interleaved magnetic micro-transformer. It is composed of two identical windings. A bottom magnetic core is used to improve the integrated transformer performances. To form the windings, we have used a surface micromachining process. We have also used a negative photoresist (SU-8) as an insulating layer and as support for the fabrication of a bridge to connect the central end of the coils to the ground shield. The micro-transformer have been characterized with impedance meter up to 100 MHz, and completed to 1 GHz using vector network analyzer.