Abstract
The liquid-solid interface motion and the temperature history of thin Si films during short pulse (< 30 ns) excimer laser annealing are observed by in-situ diagnostics. Substantial supercooling (> 200 K) followed by spontaneous nucleation into fine-grained material is observed. Lateral crystal growth is induced by fluence distribution leading to spatial control of partial/complete melting. However, growth length is limited by the triggering of spontaneous nucleation in supercooled liquid Si and lateral solidification velocity is measured to be about 7.0 m/s. To enhance the lateral growth, the pulse-duration-controlled solid-state laser is utilized. This sequential crystal growth is found to extend over 10 μm in the lateral direction. The validity of the method is confirmed by superior TFT characteristics of high field-effect mobility (n-ch μ > 460 cm2/Vs) with low threshold voltage deviation (Vth: σ < 0.07 V).
