(The) effect of input power conditions on the quality of the zone-melting recrystallized silicon film using radiative heat source

Abstract

Considerable efforts have been devoted to reveal the origin of defects generated during zone-melting recrystallization (ZMR) process. Several models have been proposed to explain the mechanism of defect generation, but no one has championed yet. Both faceted and cellular growth models have emphasized the importance of in-plane temperature gradient at the solidification interface while more recent research has insisted that radiative heating effect is reponsible for the non-planar interface morphologies. To find what plays the important role in determing the quality of the zone-melting recrystallized silicon film using radiative heat sources, the effect of input power conditions on the film quality has been investigated by using two different focusing mirrors. A simple method for obtaining the power distribution from a desired temperature distribution has been proposed. To meet the temperature gradient criterion at the solidification interface that it should be no more than 4 /mm, a piecewise-linear temperature distribution has been chosen as a desired one. The actual temperature distribution calculated by solving the heat flow equation two-dimensionally using the enthalpy method with the obtained power distribution as the input heat source shows very close agreement with the initially desired target. It also has been found that the temperature distribution is insensitive to some local changes in the input power distribution, so that we can modify the input power distribution to make the mechanical processing of the focusing mirror easier. The effect of input power conditions from the lower lamp array (preheating temperature) and the upper lamp (power distribution or inplane temperature gradient, power density and scan speed) on the quality of the zone-melting recrystallized silicon film has been investigated. The relationship between each process parameter and the quality of the recrystallized silicon film has been experimentally observed. It has been concluded...