Effect of implant damage on the gate oxide thickness

Large area capacitors were fabricated with doping and oxide thickness repre sentative of an n-MOSFET channel region. Capacitance-voltage (C-V) measurem ents on these capacitors showed a systematic change in the accumulation cap acitance when additional implant damage is introduced by a 1x10(14) cm(-2) 40 keV silicon implant. The oxide thickness values extracted from the C-V d ata increase by 1-4 Angstrom with the additional implant damage. This trend is confirmed by additional high resolution TEM and X-ray reflectivity meas urements. We postulate that the implant damage increased the oxidation rate , due either to the interstitial flux during TED, or to an increase in surf ace roughness. For channels doped with boron implantation, the increase in thickness does not change with a 5x increase in the doping dose. In contras t, with BF2-implanted channels, the effects are smaller for higher doping d ose. (C) 1999 Elsevier Science Ltd. All rights reserved.