Ion implantation dose high-resolution monitoring in Si wafers using laser infrared photothermal radiometry with lock-in common-mode-rejection demodulation

Frequency-scanned and lock-in common-mode-rejection demodulation schemes were used with laser infrared photothermal radiometric (PTR) detection of B+, P+, and As+ ion-implanted Si wafers, with or without surface-grown oxides. The implantation energy was 100 keV with doses in the range 1 × 1011-1 × 1013 ions/cm2. The lock-in common-mode-rejection demodulation (CMRD) scheme exhibited superior signal resolution in all cases where the conventional frequency-scan signals were essentially overlapped. These were B+-implants in the dose range 1 × 1012-1 × 1013 ions/cm2, and P+-implants in the 1012 ions/cm2 range.