We studied a new method of Ni-induced crystallization of amorphous silicon ͑a-Si͒ through a silicon-nitride (SiN x ) cap layer. A 0.5 nm of Ni layer was deposited on the SiN x /a-Si layers and then this was annealed in a rapid thermal annealing system. The Ni diffused through the cap layer and formed the NiSi 2 nuclei. Then, disk-shaped grains were grown from these nuclei. The grain size is between 20 and 90 m, and the surface roughness of the poly-Si is 0.76 nm, which is smoother than that ͑0.96 nm͒ of the poly-Si without a cap layer.Polycrystalline silicon ͑poly-Si͒ on glass is a promising material for large-area electronics such as active-matrix liquid crystal displays, active-matrix organic light emitting diodes, and solar cells.To improve the quality of the poly-Si on insulator, several approaches have been conducted on the crystallization of amorphous silicon ͑a-Si͒ including a capping layer on it. For example, in zonemelting recrystallization of Si with a strip heater, an encapsulation layer is necessary and appears to play three major roles: to achieve a smooth surface, to prevent agglomeration, and to induce preferred orientation ͑100͒ texture. 1 To control the lateral growth of excimer laser crystallization poly-Si through lateral thermal gradients, three different patterned capping layers have been used: antireflective (SiO 2 ), heat-sink ͑silicon nitride͒, and reflective ͑metal͒ capping layers. 2 On the other hand, Ni-induced crystallization using various Ni solutions 3,4 and an ultrathin Ni layer of ϳ10 13 cm Ϫ2 has been studied. 5,6 Recently, high quality poly-Si on insulator by metal-induced lateral crystallization ͑MILC͒ has been demonstrated. 6,7 However, the metal layer for the conventional metal induced crystallization ͑MIC͒, and/or MILC poly-Si, was deposited at least on a portion of the surface on the a-Si. In this case, the metal-contacted region on the a-Si for metal-induced crystallization is contaminated by metal impurities.To reduce metal contamination and to have uniform grain size with clean and smooth surface, we have studied Ni-induced crystallization of a-Si using a thin Ni layer on a SiN x /a-Si:H, where the capping layer (SiN x ) is a filter for metal diffusion.We deposited an a-Si:H layer first on glass and then SiN x by plasma-enhanced chemical vapor deposition ͑PECVD͒. The thicknesses of a-Si:H and SiN x are 100 and 150 nm, respectively. The 0.5 nm thick Ni layer was deposited using radio frequency sputtering with a very low power density and patterned to have a square of 360 ϫ 360 m. Figure 1 shows a schematic illustration of a Ni/SiN x /a-Si structure for Ni-induced crystallization. The samples were heated by using a rapid thermal annealing ͑RTA͒ system in N 2 ambient. The temperatures during the heating, cooling, and keeping the sample were controlled. The first step is to dehydrogenate the a-Si:H and SiN x at 430°C for 1 h. The hydrogen atoms in the a-Si:H and SiN x are effused out and the film is changed to a hydrogen-free amorphous silicon. The second step is a pulsed hea...

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An excimer-laser-based two-shot sequential lateral solidification (TS-SLS) process has been developed to fabricate 30" FHD (1920xRGBx1080) AMOLED TVs using both 2D projection and line-scan SLS systems. We have optimized (1) the microstructure of TS-SLS processed polycrystalline materials, (2) the geometry of driving TFTs to minimize non-uniformity of the pixel brightness and (3) the off-bias TFT aging process to reduce the leakage current. This result verifies that the TS-SLS process can be utilized to make large area AMOLED TVs without any laser related mura.

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