Activation Energy and Blistering Rate in Hydrogen-implanted Semiconductors
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Activation Energy and Blistering Rate in Hydrogen-implanted Semiconductors Daniel J. Pyke1, Robert G. Elliman1 and Jeffrey C. McCallum2 Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia. 2 Microanalytical Research Centre, School of Physics, University of Melbourne, VIC 3010, Australia.
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ABSTRACT Hydrogen blister rates in Si (100), Si (111) and Ge (100) substrates are compared as a function of annealing temperature and time, for a range of implant energies and fluences. For each material, the rate of blister formation was found to exhibit Arrhenius behavior and to be characterised by a single activation energy over the temperature range examined. The extracted activation energies were 2.28±0.03 eV, 2.17±0.06 eV and 1.4±0.03 eV for (100) Si; (111) Si and (100) Ge, respectively. These results are compared with reported measurements and discussed in relation to proposed models of hydrogen blistering. INTRODUCTION Silicon-on-insulator (SOI) structures are routinely used for the fabrication of integrated electronic circuits, photonic devices and structures and micro-electro-mechanical systems (MEMS), and are most commonly fabricated by a hydrogen-induced cleavage technique in which ion-implanted hydrogen is employed to initiate and propagate cracks in a plane parallel to the silicon surface[7]. Considerable research effort, particularly at Los Alamos National Labs [4,8,9,11] has been devoted to understanding this cleavage technique in (100) silicon but several fundamental issues remain unclear, including the role of stress on hydrogen platelet alignment, and the details of the bond-breaking processes associated with crack propagation (i.e. stress induced or hydrogen-mediated)[2,7]. There is also keen interest in extending the technique to other silicon orientations (i.e. (110) and (111) orientations) and semiconductor materials (e.g. Ge, GaAs)[1,3,6,10]. To this end, the present work compares blister rates in Si (100), Si (111) and Ge (100) substrates as a function of annealing temperature and time, for a range of implant energies and fluences. These results are compared with reported measurements and discussed in relation to proposed models of hydrogen blistering. The roughness and depth of the blisters were also examined via ion beam analysis, optical profilometry and transmission electron microscopy. EXPERIMENT Three different materials were examined in the course of this study: p-type Bdoped silicon with ȡ = 10-20 .cm; B-doped p-type silicon with a ȡ = 7-15 .cm; and undoped germanium with a ȡ > 40 .cm. Each of these materials was implanted with 40keV H ions to a fluence of 6 x 1016 H/cm2 at room temperature. During implantation the ion beam current was kept between 1-3μA to minimise dynamic annealing effects.
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After implantation, the samples were cut into small pieces of between 3-5mm2, and annealed under atmospheric conditions at fixed temperatures in the range T=300oC-650oC while being monitored throug
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