Influence of boron-interstitials clusters on hole mobility degradation in high dose boron-implanted ultrashallow junctions

摘要

Hole mobility degradation has been studied in high-dose boron-implanted ultrashallow junctions containing high concentrations of boron-interstitial clusters (BICs), combining an empirical method based on the self-consistent interpretation of secondary-ion-mass spectrometry (SIMS) and Hall measurements and liquid-nitrogen (LN_2) to room temperature (RT) hole mobility measurements. It has been found that BICs act as independent scattering centers which have a strong impact on hole mobility in addition to the other scattering mechanisms such as lattice and impurities scattering. A mobility degradation coefficient a has been introduced, which gives information on the mobility degradation level in the analyzed junctions. In the case of very high concentrations of BICs (containing a boron density up to 8 × 10~(14) cm~(-2)), measured hole mobilities were found to be ～40% lower than corresponding theoretical values. BICs dissolution through multiple Flash anneals at high temperature (1300 ℃) reduces the observe mobility degradation.