High-Q Inductors on Locally Semi-Insulated Si Substrate by Helium-3 Bombardment for RF CMOS Integrated Circuits.

A helium-3 ion bombardment technique is proposed to realize high- Q inductors by creating locally semi-insulating substrate areas. A dose of 1.0\times 10^{13} cm ^{-2} helium-3 increases a Si substrate resistivity from 4 \Omega \cdot cm to above 1 \text{k}\Omega \cdot cm, which improves the quality factor of a 2-nH inductor with a 140- \mu \text{m}$ diameter by 38% ( Q=16.3$ ). An aluminum mask is used for covering active areas, and at least 15- \mu \text{m} distance from the mask edge is required to avoid the p-n junction leakage. The proposed technique is applied to an 8-GHz oscillator, and an 8.5 dB improvement of the measured phase noise has been achieved. [ABSTRACT FROM AUTHOR]