Flash-Lamp-Induced Lateral Solidification of Thin Si Films
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Flash-Lamp-Induced Lateral Solidification of Thin Si Films K. Omori1,2, G.S. Ganot1, U.J. Chung1, A.M. Chitu1, A.B. Limanov1, and James S. Im1,3 1
Program in Materials Science and Engineering, Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
2
Technical Development Department, The Japan Steel Works, LTD., Yokohama, Japan
3
Department of Materials Science and Engineering, College of Engineering, Korea Advanced Institute of Science and Technology, Korea
ABSTRACT In this paper we show that a flash lamp can be employed to induce controlled lateral solidification of a-Si thin films. Specifically, a dual xenon-arc-lamp-based system was utilized to induce location-controlled complete melting by shaping the incident beam using a contact mask. The resulting laterally solidified microstructure consisted of exceptionally long grains (~10s to ~100s of μm) that were relatively free of intragrain-defects. With further development and optimization, the approach may lead to cost-effective/high-throughput processes and systems that can capture and enhance the advantages of laser-based/melt-mediated crystallization techniques. INTRODUCTION Using a flash lamp to heat and crystallize a-Si films can be recognized as an interesting and noteworthy technical procedure for a number of reasons: (1) it was demonstrated as a viable crystallization method nearly thirty years ago [1,2], (2) it is an extremely flexible technique capable of being used for solid-phase as well as melt-mediated crystallization of a-Si films [3-6], and (3) the irradiation-system-related components are well developed as a consequence of the "flash lamp annealing" method being evaluated and developed for the semiconductor manufacturing industry [7]. In this paper, we demonstrate the controlled lateral solidification (referred to as controlled super-lateral-growth (C-SLG)) of a-Si films using a flash-lamp as the source of crystallization, and we show that low-defect-density Si films are created in the process. Controlled super-lateral growth of a-Si films is a melt-mediated thin film crystallization approach using pulsed lasers which has been studied extensively in the past [e.g. 8,9]. By systematically manipulating and controlling the locations, shapes, and extent of melting induced by the incident beam, the C-SLG approach can generate grains with low structural defect densities. Specifically, the method takes advantage of the fact that when one controls the locations of the silicon film within which complete melting is induced, the resulting solidification will proceed via lateral growth to generate a polycrystalline material with large and elongated grains.
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EXPERIMENTAL DETAILS Our custom-built flash lamp irradiation system comprises two independently controllable xenon lamps (Figure 1). Each lamp is capable of delivering a pulse (~50μsec to 15msec pulse duration), with sufficient energy density to induce melting over the entire pulse duration range. A copper grid with periodically arranged square patterns (wit
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