High quality factor copper inductors integrated in deep dry-etched quartz substrates

This paper reports on an inductor fabrication method capable to deliver high quality factor (Q) and high self-resonance frequency (SRF) devices using quartz insulating substrates and thick high-conductivity copper lines. Inductors are key devices in RF circuits that, when fabricated on traditional semiconductor substrates, suffer from poor RF performances due to thin metallization and substrate related losses. Many previous works revealed that RF performances are strongly dependent on the limited metallization thickness and on the conductivity of the substrate. In this paper we demonstrate a new fabrication process to improve the Q factor of spiral inductors by patterning thick high conductive metal layers directly in a dielectric substrate. Moreover, we develop and validate accurate equivalent circuit modeling and parameter extraction for the characterization of the fabricated devices.