Determination of the depth profiles of ion-implanted impurities by electron probe x-ray microanalysis

The aim of this paper is to demonstrate the suitability of electron probe x-ray microanalysis (EPMA) for nondestructive determination of the depth profiles of ion-implanted impurities. The intensities of the characteristic x-ray emission of impurity atoms (P and As) were measured (on a WDX spectrometer) on the implanted specimens and references (GaP and GaAs) at three values of primary electron energy E_P. The range distribution of the implanted impurity as a first approximation is given by a Gaussian distribution. A two-parameter fitting has been developed for the determination of Gaussian parameters R_P and ΔR_P of the profiles, which give a minimal difference between the experimental and calculated x-ray intensities at different E_P. The dose of the implanted impurity is a third parameter that can be obtained here. The results were compared with those of depth profiles from AES (for P) and SIMS (for As) and good agreement is observed. A new method for the determination of the depth distribution of x-ray production for the characteristic x-rays of impurity atoms is also presented.