DOSE AND DAMAGE MEASUREMENTS IN LOW-DOSE ION-IMPLANTATION IN SILICON BY PHOTOACOUSTIC DISPLACEMENT AND MINORITY-CARRIER LIFETIME

Photo-acoustic displacement (PAD) generated with a modulated laser beam pumping is studied for As+ or B+ implanted Si. At doses above 1 x 10(13) ions/cm2, the PAD has a close relationship to damage density. An ion implantation dose down to 2 x 10(9) ions/cm2 can be detected by the PAD measurement. Doses below 2 x 10(10) ions/cm2 can be monitored by minority carrier lifetime measurement. A non-destructive high-sensitive dose monitor can be achieved by the PAD and minority carrier lifetime measurements. This monitoring leads to tight control of the threshold voltage of a MOS transistor.