Self-assembly of three-dimensional Au inductors on silicon

Integration of inductors into high-frequency silicon circuits currently comes at the expense of a low-quality factor (Q), mainly because of electromagnetic interactions with the underlying substrate. Various fabrication methods for high Q inductors have been proposed, but poor compatibility with standard semiconductor process technology is a common problem. A promising technique involving in-plane fabrication and surface tension self-assembly to the vertical orientation has been previously reported for copper inductors. Here, a complementary metal-oxide-semiconductor (CMOS)-compatible and lead-free version of this process, with improved reproducibility, is reported, using Au as the inductor material. A 4 nH meander inductor is fabricated and tested as a demonstrator, showing significant increase of Q upon rotation.