V. Subramanian et al., IN-SITU MONITORING OF CRYSTALLINITY AND TEMPERATURE DURING RAPID THERMAL CRYSTALLIZATION OF SILICON ON GLASS, Journal of the Electrochemical Society, 144(6), 1997, pp. 2216-2221
A novel technique is presented for simultaneously measuring temperatur
e and crystallinity in situ during the rapid thermal annealing of thin
Si films on transparent substrates for active matrix liquid crystal d
isplay applications. This technique makes use of acoustic waves to mon
itor temperature by measuring changes in Lamb wave velocity with tempe
rature. Since this technique is independent of emissivity, it enables
accurate tracking of crystalline phase transitions along with temperat
ure, based on changes in the optical absorption properties of the film
. This provides a methodology for closed loop control and end-point de
tection. The experiments on thin amorphous Si on fused silica demonstr
ate temperature repeatability of 2%. Also, the technique proved sensit
ive enough to detect the onset of nucleation, as evidenced by transmis
sion electron microscopy.