Transversal range straggling of 40 keV-2 MeV tungsten ions implanted in SiO2

This paper presents an experimental investigation of transversal range straggling of tungsten ions implanted in SiO2 for a wide incident-ion-energy level of 40 keV-2 MeV. Tungsten ions were implanted into SiO2 films tilted by angles of 7 degrees and 55 degrees with respect to the axis normal to the specimen for each incident-ion energy. The depth profiles of implanted tungsten ions were measured and fitted by using secondary ion mass spectrometry (SIMS) and Gaussian distribution, respectively. The measured values of projected range (R-p), longitudinal range straggling (Delta R-p) and transversal range straggling (Delta R-t) were determined from the corresponding Gaussian-fitted distributions of 7 degrees and 55 degrees implants along with Furukawa and Matsumura's method. The calculated values of R-p, Delta R-p and Delta R-t yielded by the SRIM Monte-Carlo simulation code are also presented herein for comparison. It was found that the calculated values of R-p, Delta R-p and Delta R-t agreed to the corresponding measured values within (on average) 19%, 21% and 14%, respectively. The discrepancies between the calculated and measured values of both Delta R-p and Delta R-t become significant at rather low incident-ion energies. (C) 1999 Elsevier Science B.V. All rights reserved.