Large Grain Growth of Silicon Films on Low Temperature Glass Substrates

Argon laser recrystallization of silicon films deposited on low temperature glass substrates offers the potential for development of large scale matrix addressable displays incorporating on-glass line drivers and logic circuitry. In order to achieve this promise, the challenge of containing molten silicon, at 1685 K, in close proximity to a glass substrate (Corning 7059) which has an annealing temperature of 914 K, must be met. We have successfully recrystallized areas of several squared millimeters of 500 nm thick silicon films without cracking on 7059 glass substrates. This was achieved by the incorporation of multiple film layers interposed between the silicon and the glass substrate, which serve to control the thermal gradients which occur during the recrystallization process. Grains in the recrystallized films are typically 10µm wide and several hundred µm long, achieved using a laser spot size of approximately 70 µm diameter and a scan rate of 15 cm/s. Comparable results were obtained for a wide range of laser powers, from 7.5 to 9.2 W.