On Mechanism Of Nickel Diffusion During Metal Induced Lateral Crystallization Of Amorphous Silicon
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On Mechanism Of Nickel Diffusion During Metal Induced Lateral Crystallization Of Amorphous Silicon A.M.Myasnikov1,2, M.C.Poon2, P.C.Chan2, K.L.Ng2, M.S.Chan2, W.Y.Chan2, S.Singla2, C.Y.Yuen2 1 Institute of Semiconductors Physics, Novosibirsk, Russia 2 Hong Kong University of Science and Technology, Hong Kong ABSTRACT During metal induced lateral crystallization (MILC) of amorphous silicon (a-Si) the size and quality of obtained film depend on nickel penetration and it is very important to know about nickel diffusion at recrystallization process. The nickel has penetrated during annealing on surface of a-Si inducing the recrystallization process, which has changed the mechanism of diffusion on surface of a-Si to the mechanism of diffusion on surface of single crystal silicon and in single crystal silicon. Also the effect of thickness of nickel and a-Si film are discussed. INTRODUCTION Large grain poly-silicon film with high material quality and uniformity can have numerous novel applications such as providing a low cost alternative to form silicon-on-insulator (SOI) substrates and a breakthrough technology to ultra-dense 3-dimensional multi-layer devices. For reception of qualitative and homogeneous poly-silicon it is very important to know about its characteristics, which are critical for MILC [1]. In the previous MRS paper we had studied the effect of Ni concentration on MILC process [2]. In this paper, we try to discuss the nickel diffusion in amorphous silicon layer and to study the present the model of nickel penetration during MILC. EXPERIMENTAL RESULTS In our experiments the samples have been studied, having layers of a-Si with thickness 1000 - 3000 Å on oxidized silicon substrate. Nickel islands with thickness from 50 Å to 1000 Å were used as seeds. Temperature, T, and time, t, of recrystallization were varied from 500 °C to 640 °C and from minutes to 100 hours. The sizes of MILC regions, L, around of Ni seeds were in the range from some microns to 200 µm. Diffusion coefficient for different temperatures was defined by a ration of L2/t. The results of experimental measurement of diffusion coefficient were summarized in Figure 1. In the same figure there are presesented the reference data for Ni diffusion coefficient in single crystalline [3] and amorphous silicon [4,5] and on surface of silicon [6,7]. Also the data of Ni diffusion coefficient were shown that were obtained by TEM study of Ni recrystallization of amorphized layer [8,9]. Because the data for Ni diffusion on surface and Ni diffusion in amorphous silicon were envestigated at higher (more than 800 °C) and at lower (less than 350 °C) temperatures, respectively, these data were aproximated for all temperature range for comparison with our results. Practically all our data of Ni diffusion coefficient at MILC process are located in Figure A22.11.1 Downloaded from https://www.cambridge.org/core. Columbia University Libraries, on 16 Aug 2019 at 07:26:53, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https:
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