STUDY OF POINT-DEFECT CLUSTERS PRODUCED BY BF2+ IMPLANTATION IN SILICON SINGLE-CRYSTALS

High-resolution diffuse x-ray scattering (DXS) measurements made with a multicrystal x-ray diffractometer have been used to characterize point defect clusters produced by 90-keV and 135-keV BF2+ implantations (fluence = 1 x 10(15) cm-2). The specimens were 50-mm-diam (100) silicon single crystals (n type; 4-6 OMEGA cm resistivity). A highly monochromated and collimated K-alpha-1 is obtained by three-plane (111) silicon single crystals oriented in (+, -, -) setting. The DXS intensity around 400 reciprocal lattice point was measured along [+/- 100] directions. Implantation produced a slight broadening of diffraction curves from approximately 6 to approximately 7 arcsec. From unimplanted regions diffuse scattering was primarily due to isolated interstitial point defects in the investigated volume of reciprocal space. Implantation was found to produce interstitial point defect clusters. Experimental data has been analyzed by using a phenomenological model for dislocation loops by using a curve fitting method. The values of loop size R(cl), volume of the loops A(cl), and number of defects per loop N(cl) have been determined. For implantation energies of 90 and 135 keV, these are, respectively, R(cl) = 1.47 x 10(-4) and 1.29 x 10(-4) cm, A(cl) = 2.92 x 10(-16) and 2.27 x 10(-16) cm3, and N(cl) = 1.46 x 10(7) and 1.37 x 10(7).