Thermal evaluation of zone-melting recrystallization of thin-film structures over a wide range of melting points

Abstract

Zone-melting recrystallization (ZMR) is a lateral epitaxy technique used to recrystallize polycrystalline thin films on substrates. Large-area multilayer structures of thin films processed with ZMR are usable in microelectronics applications. During the processing, slight variations in thermal gradients can lead to different crystalline qualities. Thus, processing uniformity over the wafer is strongly affected by the sensitivity of both the melt width and the solid/liquid interface to changes in the thermal environment. Processing control must either be set initially in a stable operating range or adjusted dynamically to variations in processing. Numerical simulations of the ZMR process were conducted to evaluate the sensitivity of the process over a wide range of temperatures and materials. Results indicate that material with melting points below 900 °C are very sensitive to temperature disturbances. This is due to the increased influence of conductive heating and decreased influence of radiative heating. The increased reflectivity during phase change curbs the amount of absorbed radiation. As the absorbed radiation becomes less influential, the sensitivity of the slush width decreases. Conductive effects should be considered when processing materials with melting points at or below 900 °C.