Method of fabricating high-Q silicon varactor diodes

A new processing technique has been developed for the fabrication of high-Q and high-voltage varactor diodes. The process utilises ion implantation and laser annealing for heavily-doped p++ and n++ layers and epitaxial growth for low impurity concentrations. The technique provides good yield and repeatability, and it has allowed fabrication of varactor diodes which have breakdown voltages of 120 V and a Q as high as 600 at ¿8 V bias and 50 MHz frequency.