Development of a continuously variable energy radio frequency quadrupole accelerator for SiC power semiconductor device fabrication

High energy ion implantation is an important process for controlling deep junction conductivity of SiC semiconductor devices. An radio frequency quadraupole (RFQ) accelerator can accelerate high Current ions. but the conventional RFQ accelerator is unable to accelerate various ions with different energies. In order to form the box profile with a low number of defects. a high current MeV ion implanter was constructed using a newly designed continuously variable energy RFQ accelerator and high temperature ion implantation chamber. Results of the experiment showed that the resonance frequency varied from 11.7 to 29.3 MHz, so the output beam energy could be changed over a range of about 6.3 times. The results also showed a higher Q-value of over 5000 compared with that of a conventional machine of 1500. Beam acceleration tests were performed using Al ions, and beams were accelerated from 20 to 750 keV using an radio frequency power of 15 M. The ions were implanted into 4H-SiC. and the projected ranged was 0.76 mum measured by secondary ion mass spectroscopy. (C) 2002 Published by Elsevier Science B.V.