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E7.8.1

CLUSTERING ANALYSIS IN BORON AND PHOSPHORUS IMPLANTED (100) GERMANIUM BY X-RAY ABSORPTION SPECTROSCOPY M. Alper Sahiner1, Parviz Ansari1, Malcolm S. Carroll2♦, C. A. King2*, Y. S. Suh3, R. A. Levy3, Temel Buyuklimanli4, Mark Croft5 1

Seton Hall University, Physics Department, South Orange, New Jersey 07079 Agere Systems, Allentown, Pennsylvania 18109 3 New Jersey Institute of Technology Newark, New Jersey 07102 4 Evans East, East Windsor, New Jersey 08520 5 Rutgers University, Physics Department, Piscataway, New Jersey 08855 2

ABSTRACT Recently, germanium based semiconductor device technology gained renewed interest due to new developments such as the use of high-k dielectrics for high mobility Ge MOSFETS. However, a systematic local structural investigation of clustering of dopants has been lacking in the literature. In this study, we present a detailed local structural analysis of boron and phosphorus implanted Ge wafers. We have used Ge K-edge x-ray absorption fine-structure spectroscopy (XAFS) in order to probe the local structural modifications around the Ge atom under various implantation parameters and postimplantation annealing treatments. The (100) Ge wafers were implanted and with 11B+ or 31 + P using energies ranging from 20 keV to 320 keV and doses of 5x1013 to 5x1016/cm2. Pieces of the implanted wafers were subjected to thermal annealing at 400oC or 600oC for three hours in high purity nitrogen. Secondary ion mass spectrometry (SIMS) measurements on these wafers were used to correlate the dopant concentration profiles with the local structural information obtained from XAFS. B and P implanted Ge exhibit distinct responses to annealing. For the P implanted Ge samples annealing leads to recrystallization of Ge with increasing annealing temperature, but also an increase in Ge Debye-Waller factors, whereas B implanted Ge samples exhibit recrystallization at 400oC annealing but more randomness after 600oC annealing. INTRODUCTION Germanium has attracted a lot of interest recently due to high carrier mobility and possible compatibility with the high-k dielectric materials in MOSFET technology [1,2]. Previously, dopant activation and diffusion in germanium have been studied in p-type and n-type implanted germanium wafers with various dose annealing techniques leading to contradicting results on electrically active dopant in germanium [3,4,5]. However, dopant related structural characterization of Ge has not been investigated yet. In order to understand the mechanisms that are important in dopant diffusion and activation in Ge the local structural information around germanium atoms is crucial. Such atomic scale

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Current address: Sandia National Laboratories, P.O. Box 5800 M.S. 1077, Albuquerque, New Mexico 87185 Current address: Noble Device Technologies, Newark, New Jersey 07103

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information will be guiding to post implantation treatments that are applied in order to increase doping activation and reduce dopant diffusion. Previously, it had been shown that specific quantitative informati