Microstructure of laser-crystallized silicon thin films on glass substrate

Abstract

We investigate the microstructure of polycrystalline silicon films (grain size, orientation distribution, and grain boundary population). These films are produced by laser crystallization of amorphous silicon on glass substrates by a frequency doubled Nd:YVO4 laser operating at a wavelength of 532 nm. Transmission electron microscopy reveals that the grains have an average width between 0.25 and 5 μm depending on the crystallization parameters and a length of several 10 μm. Electron backscattering diffraction experiments show that the grain orientation of the poly-Si films is textured. Type and extent of texture depend in a complex way on the thickness of the crystallized amorphous silicon layer, on the repetition rate of the laser pulses, and on whether or not an additional buffer layer is present on the glass substrate. In any case, the grain boundary population is dominated by first and second order twin boundaries.

Molecular Dynamics Studies of Surface Nucleation and Crystal Growth of Si on SiO2Substrates

“…However, the preferred orientation of the (111) plane has been reported by many researchers [6,10,11]. The values of surface energy for (100), (110) and (111) plane were calculated to be 2.27, 1.52, and 1.20 J/m 2 at 77 K, respectively.…”

Enlargement of grain in poly-Si by adding Au in Ni-mediated crystallization of amorphous Si using a SiNx cap layer

“…For example, the poly-Si by Al-induced crystallization is more preferentially oriented in the ͑100͒ direction to the surface normal and has large grains. 18 The laser crystallized poly-Si on quartz has a preferential ͑111͒ texture of the grains for the samples crystallized in the superlateral growth regime, 19 while, excimer-laser crystallized poly-Si exhibits͑111͒ preferred orientation to surface normal and ͑100͒ preferred orientation appears for rather thick ͑ϳ200 nm͒ poly-Si film crystallized by a frequency-doubled continuous wave Nd: YVO 4 laser. 20 Poly-Si thin films with more than 96% ͑100͒ texture can be produced when 200 shots are used for crystallization with an energy density of 450 mJ/ cm 2 .…”

<title>Electronic materials via laser radiation</title>

“…These sources have been also proposed for a more ambitious concept: the direct crystallization of silicon on areas as large as the displays, without beam scanning the plates (single-shot crystallization), Unfortunately, the long-pulse laser sources have also a lower repetition rate (<10 Hz), and the actual convenience of the process compared to the assessed short-pulse commercial sources has still to be fully demonstrated. Finally, there are the visible pulsed laser sources that have high repetition rate and low intensity, and can be used in the more traditional point-beam processing23 25 The relevant process features obtained with the various laser sources are listed in Table 1. As an exercise to make direct comparisons we have calculated for the different sources the time needed to process in single shot steps a mother board glass as large as AMG 30 cm x 30 cm.…”