Fabrication and electrical characterization of high performance copper/polyimide inductors

This paper presents fabrication and RF characterization results of spiral inductors fabricated using a developed damascene-like thick-copper / polyimide process module. This module has low thermal budget and is compatible with current IC interconnect architectures, making it suitable for CMOS above IC integration of high quality factor passive devices. Thick, high-conductive copper layers associated with low κ polymers and high resistivity substrates can provide RF performances that cannot be achieved using conventional thin aluminum films on low-resistivity substrates. Peak quality factors of about 20 and exceeding 10 over a wide frequency range (1-6 GHz) are demonstrated, with a self-resonant frequency of about 10 GHz. Measurements and equivalent circuit extraction results are also presented and discussed.