Calibration of the Au Labeling Technique to Measure Vacancy Defects in Si
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Calibration of the Au labeling technique to measure vacancy defects in Si R. Kalyanaraman and T. E. Haynes Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 V. C. Venezia, D. C. Jacobson, H.-J. Gossmann and C. S. Rafferty Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 ABSTRACT It has been shown recently that Au labeling can be used to profile vacancy-type defects located near half the projected range (½Rp) in MeV-implanted Si. In this work we have quantified the technique by determining the ratio of vacancies annihilated to decrease in the number of Au atoms trapped (calibration factor ’k’) for the Au labeling technique. The 3 step experiment involved: 1) a high-energy Si-self implant (HEI) followed by an anneal to form stable vacancy clusters, 2) a controlled removal of vacancies via a medium energy Si self implant and interstitial-cluster dissolution anneal, and finally 3) Au labeling to count the change in vacancy concentration in the near surface region (0.1-1.6µm). It is seen that the Au concentration decreases linearly with increasing interstitial injection and the slope of this decrease determined the number of vacancies per trapped Au atom. The value of k was determined to be 1.2±0.2 vacancies per trapped Au atom. INTRODUCTION Ion implantation as a processing step in Si device fabrication has resulted in extensive research into the study of defects in Si. This has mainly been due to the supersaturation of point defects invariably accompanying ion implantation and the subsequent defect evolution. In the past decade large advances have been made in correlating defect evolution with dopant diffusion and device behavior [1, 2]. For instance, the direct influence of the interstitial-type {311} rodlike defects [1] on the transient enhanced diffusion of B showed how critical it was to understand the evolution from point to extended defects and finally to dissolution of ion implanted defects. Recently, Holland and co-workers [3] showed from transmission electron microscopy (TEM) studies that extended vacancy-type defects form in the near-surface region for extremely highdose implants. Other groups have also observed vacancy-type defects under more moderate implantation doses by techniques like x-ray diffraction strain measurements [4], positron annihilation spectroscopy (PAS) S-parameter measurements [5] and x-ray diffuse scattering measurements [6]. While all these techniques are capable of detecting vacancy-type defects, considerable work needs to be done to use them to quantitatively measure the size and distribution of vacancy-type defects. In the past few years the process of metal gettering to vacancy-type defects has been studied by a number of authors [7,8]. In fact, Venezia and co-workers [9] have used Au to label the vacancy-type defects formed by high-energy Si self implants. In this work, we present experiments designed to obtain the relation between the true vacancy concentration and the Au concentration, given by the calibration factor “k”, using the Au labe
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