Ultralow energy boron implants in silicon characterization by nonoxidizing secondary ion mass spectrometry analysis and soft x-ray grazing incidence x-ray fluorescence techniques

摘要

Boron ultralow energy (0.2-3 keV) high dose (1 × 10~(15) cm~(-2)) implants in single crystalline Si (100) were characterized by secondary ion mass spectrometry using an ultralow energy (0.35-0.5 keV) O_2~+ ion primary beam and collecting positive secondary ions. In particular, the not fully oxidizing approaches (primary beam oblique incidence and ultrahigh vacuum analysis atmosphere) were investigated because they are expected to provide better accuracy on the profile shape, especially in the region between the surface and the native oxide/substrate interface. The main drawback represented by an early formation of roughness on the crater bottom has been overcome by combining the ion sputtering with the rotation of the sample during the analysis. The reduced formation of roughness ensures more stable sputtering conditions and a more stable erosion rate with a more accurate depth calibration. The measured dose values were then cross-checked comparing them with results of soft x-ray synchrotron radiation grazing incidence x-ray fluorescence.