Ion Implantation Defect Characterization by High-Resolution X-Ray Diffraction
- PDF / 968,993 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 75 Downloads / 277 Views
ION IMPLANTATION DEFECT CHARACTERIZATION BY HIGHRESOLUTION X-RAY DIFFRACTION Jos G.E. Klappe', Istvn Bdrsony2 and Tom W. Ryan 3 1,2University of Twente, MESA Research Institute,P.O.Box 217, 7500 AE Enschede, The Netherlands "2on leave from the Technical University ofBudapest, Budapest, Hungary 3 Philips Analytical, Lelyweg 1, 7602 EA Almelo, The Netherlands
ABSTRACT High-energy ion-implantation is one of the most critical processing steps regarding the formation of defects in mono-crystalline silicon. High- as well as low-doses implanted at various energies can result in relatively high residual defect concentrations after post-implantation annealing. Before annealing, the crystal lattice strain is mainly caused by the point defects. After annealing, the accommodation of substitutional impurities is the main origin of the residual lattice strain. High-Resolution X-ray Diffraction (HRXD) has been frequently used for the characterization of these structures. Dislocation loops formed during the high temperature step, however, cause enhanced diffuse X-ray scattering, which can dominate the measured X-ray intensity in conventional HRXD. Triple axis diffractometry is used in this study to analyze the size, type and location of defects in a boron implanted and rapid thermally annealed silicon sample. INTRODUCTION Ion implantation is the dominant method for introducing controlled amounts of dopant atoms in semiconductor devices. Advantages compared to dopant diffusion are the placing of the peak concentration of the doping profile at a desired depth, compared to a peak concentration which is always at the surface for dopant diffusion, and an accurate control of the total number of dopant atoms. The drawback is, however, the formation of individual point defects, like interstitials and vacancies during the implantation due to cascading implanted ions and knocked-off lattice atoms. The point defects cluster during the annealing to form secondary defects, like dislocation clusters or dislocation loops. The formation of secondary defects in the electrically active semiconductor region can be suppressed in several ways. Such a method is e.g. the recently suggested multiple-step implantation, for which the implantation is repetitively alternated with annealing'. A less complex technique is the use of Rapid Thermal Annealing (RTA). In the latter case, the anneal temperature is increased very rapidly to activate the defect annihilation mechanism before the highly diffusive point defects of much lower diffusion activation energy can cluster to form secondary defects. In this way, by RTA a lower defect concentration can be achieved, compared to conventional furnace annealing. For the analysis of the defects several techniques are being used, like X-TEM, SIMS, chemical etch analysis and electrical measurements. This paper describes the use of triple-axis diffractometry for the analysis of dislocation loops. Results are verified with X-TEM micrographs. EXPERIMENTAL High-resistivity 6-10 fl.cm (100) 3" silicon wafers have been used in
Data Loading...
