An approach for fabricating high performance inductors on low resistivity substrates

Porous Si layers up to 250 /spl mu/m in thickness are used to isolate spiral inductors from low resistivity substrates. Wafer curvature and SIMS analysis are done to address the manufacturability issue of porous Si. Spiral inductors with a single level Al on 2-inch, p-type substrates of 0.008 /spl Omega/-cm resistivity are demonstrated with Q=5.0 at 1.8 GHz for an L of 9 nH. Large inductors with L/spl sim/150 nH have been shown with the first resonance frequency at 1 GHz. The expected performance potential as well as factors that could be limiting the Q are discussed.