Method of creating local semi-insulating regions on silicon wafers for device isolation and realization of high-Q inductors

Penetrating proton beams from a compact ion cyclotron (diameter: 1.5 m, height: 2 m) were employed to create local semi-insulating regions within silicon substrates to facilitate device isolation in mixed-mode (analog-digital) integrated circuits (IC's) and realization of RF IC's with high-Q inductors. Experiments revealed that resistivity values of I M/spl Omega/-cm could be reached by practical proton fluences on silicon wafers of original resistivity of more than about 1 /spl Omega/-cm. Significant improvement was evidenced on Q values of irradiated inductors. Effect of reduced inductor metal conductivity from bombardment was over-shadowed by the more enhanced Q behavior, if the proton fluence is sufficiently large.