IN-SITU MONITORING OF CRYSTALLINITY AND TEMPERATURE DURING RAPID THERMAL CRYSTALLIZATION OF SILICON ON GLASS

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.