Creation and Annealing out Mechanism of Defects in Ion-Implanted Si Crystals Investigated by Positron Annihilation
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ABATRACT Vacancy-type defects in Si crystaLs introduced by ion implantation have been investigated by an energy-variable positron beam The present paper describes the general feature of point defects induced by ion implantation from the point of view of their dependence on implanted ion species, ion dose, ion energy, implanted targets, thermal after implantation, the presence of oxide overlayers and so on. INTRODUCTION The field of low energy positron physics has been significantly expanded in recent years to include not only atomic physics but also solid state and surface physics or materials science. With the development of high current monoenergetic positron beamns(l, it is now possible to profile defects as a function of depth from the surface(2-8). Many technological processes for the production of advanced materials and devices ocaatinally induce lattice defects concentrated within a few Xrm region from the surface. These defects have a great influence on the electrical properties of materials and the performance of devices. Thus, in order to control the quality, it is very important to control the structure of materials at a microscopic level In the present brief list of process treatments, ion implantation deserves special attention for its importance in the modern semiconductor industry as a standard processing technique for producing structures with submicrometer geometrical dimension. Unfortunately, ion implantation always introduces sub-surface disorder. Characterization and control of the disorder is a problem whose importance is growing the more the design of integrated circuits is moving towards shallower devices. The present state of art of technique of slow/monoenergetic positrons can successfully determine the nature and depth distribution of point defects in sub-surface regions. In the present paper, the general features of point defects induced by ion implantation will be clarified from the point of view of their dependence on (a)implanted ion species, (b)ion dose, (c)ion energy, (d)implanted targets, (e)thermal treatment after implantation, (f)the presence of oxide overlayers and so on. In particular, the physical meaning of the rapid thermal annealing will be discussed on the basis of the recently observed properties of point defects through positron annihilation in Si crystals. 287 Mat. Res. Soc. Symp. Proc. Vol. 470 01997 Materials Research Society
Positron annihilation technique is very sensitive not only to vacancy-type defects but also to oxygen atoms in Si crystals.The nature of oxygen atoms in as-grown Si crystals and in them after a variety of rapid thermal and integrated processes will be discussed on the basis of recent results of positron annihilation measurements. BACKGROUND The positron annihilation technique has become an established tool in the study of defects in materials[9). Recently, monoenergetic positron beams were successfully used to probe near-surface defects, multilayers, surfaces and interfaces. The depth-resolved positron annihilation technique is based on the gene
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