Real-time image analysis and control of the solid/liquid interface during zone-melting recrystallization of thin films

摘要

Thermal processing, a necessary step in the fabrication of most microelectronic devices, is used to improve the material quality of thin films. One example of thermal processing of thin films is Zone-Melting Recrystallization with a radiant line heat source. A line heater, situated above the film, heats a narrow region beyond its melt point creating a molten zone. As the line heater is moved slowly over the film, the material in the wake of the moving molten zone freezes in the form of a single crystal. The morphology of the solid/liquid interface strongly influences the resultant quality of the crystal. A planar morphology, in fact, produces a poor quality film which contains branching dislocations. A cellular morphology produces the highest quality films with limited point of line defects. In-situ observations of the crystalline quality can be made by examining the solid/liquid interface morphology. The real-time image analysis of the interface and the closed-loop control of the process are described in this paper.