Kinetics of silicon amorphization by N + implantation: Dose rate and substrate temperature effects

Abstract

We have observed by cross-sectional electron microscopy the kinetics of silicon amorphization by nitrogen implantation as functions of the dose rate and substrate temperature for 40 keV and 20 keV beam energies. It is shown that amorphization occurs through the accumulation of point defects or complexes. The progression of the c-a interface for increasing dose can be accurately described by the critical damage energy density model (CDED) assuming a CDED value of 30 eV atom −1 for a 40 keV implantation at room temperature using a beam current density of 1.6 μA cm −2. When increasing the dose rate, the efficiency of the amorphization process is improved, suggesting that the generation rate of point defects is a crucial parameter in the case of light ion-induced amorphization. It is finally shown that higher dose rates and low substrate temperature are to be used to promote the complete amorphization of the substrate by light ion implantation.