High-performance thick copper inductors in an RF technology

Kunal Vaed; William Graham; Michelle Steen; Jae-Eun Park; Robert Groves; Richard Volant; Ronald Nunes; James Vichiconti; Kenneth Stein; David Ahlgren

doi:10.1117/12.525823

30 December 2003 High-performance thick copper inductors in an RF technology

Kunal Vaed, William Graham, Michelle Steen, Jae-Eun Park, Robert Groves, Richard Volant, Ronald Nunes, James Vichiconti, Kenneth Stein, David Ahlgren

Author Affiliations +

Proceedings Volume 5342, Micromachining and Microfabrication Process Technology IX; (2003) https://doi.org/10.1117/12.525823
Event: Micromachining and Microfabrication, 2004, San Jose, California, United States

Abstract

With the emergence of wired and wireless communication technologies, on-chip inductors find applications in a variety of high performance radio frequency (RF) circuits. In this work, we present two approaches for high-performance copper inductors in an RF technology. In the first approach (Type I), we lower ohmic losses to realize a high Q-factor. This is achieved by using, for the first time in a manufacturable technology, 4 μm thick copper spirals along with a 4 μm thick copper underpass on high-resistivity substrates (75 Ω-cm). The underpass is connected to the spirals with a 4 μm tall copper via, which lowers spiral to underpass capacitance. For further lowering the capacitive losses, an additional 6.1 μm thick interlayer dielectric separates the underpass from the substrate. In the second approach (Type II), we utilize a novel one-mask CMOS-compatible micromachining scheme to eliminate substrate losses. This is achieved by completely removing the silicon substrate from directly below the inductors. For a 1.1nH inductor, peak-Q shows an impressive two-fold improvement from 26.6 at 3.8 GHz for Type I inductor to 52.8 at 8.2 GHz for Type II inductor after silicon micromachining. The resonant frequency increases from 18 GHz to 27 GHz after substrate micromachining.

Citation Download Citation

Kunal Vaed, William Graham, Michelle Steen, Jae-Eun Park, Robert Groves, Richard Volant, Ronald Nunes, James Vichiconti, Kenneth Stein, and David Ahlgren "High-performance thick copper inductors in an RF technology", Proc. SPIE 5342, Micromachining and Microfabrication Process Technology IX, (30 December 2003); https://doi.org/10.1117/12.525823

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