High-performance micromachined tapered spiral inductors with resonant frequency of 17 GHz

摘要

A 4.5-turn spiral inductor with tapered Cu metal width (ΔW = 3 μm) fabricated on normal silicon substrate (～750 μm) exhibited a high quality factor of 9.68 at 2.0 GHz, which is 18.8% higher than that (8.15) of a 4.5-turn spiral inductor with comparable outer dimension and equal Cu metal width fabricated on the same substrate. This phenomenon results from an effectively smaller series resistance of the tapered spiral inductor structure due to smaller eddy current effect. In addition, if the silicon substrate of the 4.5-turn tapered spiral inductor (ΔW = 3 μm) is thinned down to about 22 μm by micro-machined method, the quality factor and resonant frequency can be greatly improved to 15.6 and 17 GHz, respectively.