Sequential Lateral Solidification of PECVD and Sputter Deposited a-Si Films
- PDF / 7,389,399 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 56 Downloads / 188 Views
Sequential Lateral Solidification of PECVD and Sputter Deposited a-Si Films M. A. Crowder, Robert S. Sposili, A. B. Limanov, and James S. Im Division of Materials Science and Engineering, Department of Applied Physics and Applied Mathematics, School of Engineering and Applied Science, Columbia University, New York, New York 10027 Abstract We have investigated sequential lateral solidification (SLS) of amorphous Si films that have been prepared via PECVD and sputter deposition methods. The focus of the work was on identifying and analyzing the energy density and per-pulse translation distance parameter space that permits SLS of these films. Experimental details include the use of a two-axis projection irradiation system to image a straight-slit beamlet pattern onto the sample, and analyzing the resulting microstructures by SEM and optical microscopy of Secco-etched samples. High-temperature-deposited LPCVD films were also examined to enable further comparative analysis. We conclude from these results that there are no major differences in both the SLS process characteristics and the resulting microstructure among the investigated films (provided that the films are dehydrogenated in the case of PECVD a-Si). Based on the controlled superlateral growth (C-SLG) model of the SLS process, we attribute these findings to the fact that the SLS method involves—as one of its essential features—complete melting of the Si film at fluences that are sufficient to thoroughly melt crystalline Si films, during which all pre-irradiation phase and microstructural details are erased.
Background and Motivation Sequential lateral solidification (SLS) is a controlled super-lateral growth (C-SLG) [1] process that can be implemented in order to generate a variety of crystalline microstructures. Depending on the details of the process, such as the shape of the beamlets that are incident on the sample and the sequence of translation between the pulses, the method can produce crystalline Si films with grain-boundary controlled polycrystalline or directionally solidified microstructures, as well as location-controlled single-crystal Si regions [1–5]. An important and enabling characteristic of the SLS process is that the method is compatible with low-cost, low-temperature substrates such as glass or plastic. As such, it is of relevance to systematically evaluate the applicability of the SLS method to those films that are deposited using low-temperature techniques (e.g., PECVD or sputter-deposited films) that are compatible with such substrates. In general, as-deposited films prepared using different deposition methods can contain different concentrations of impurities, varying degrees of structural relaxation and medium range order, and different distributions of embedded microcrystals [6]. Given that the far-from-equilibrium first-order phase transformation sequence can often be critically affected by such details in general, it is conceivable to expect differences in the crystallization characteristics and resulting microstructures of the fil
Data Loading...
