TFT Annealing with Excimer Laser. Technology and Market Outlook

Abstract

TFT flat panel displays are rapidly increasing their share in the display market. This market experiences an annual growth of more than 20%. Making it one of the fastest growing markets in today's information technology. Polycrystalline-silicon TFT technology is opening the door to highly reliable, high-resolution, high-performance and large size Active Matrix Liquid Crystal Displays (AMLCD) that are inevitable for HDTV and advanced multi-media applications. For the formation of polycrystalline silicon, excimer laser annealing has shown itself to be superior to all other techniques as far as quality, reliability and economy is concerned. In excimer laser annealing, a high-power laser beam is scanned across the surface of the substrate coated with amorphous silicon. The amorphous silicon is heated up within a few nanoseconds, melts and crystallizes into polycrystalline silicon. The substrate remains hereby unaffected. The pronounced non-linearity of the annealing process, the high quality requirements and the high process speeds in the production lines put high demands on laser beam parameters such as energy stability, beam uniformity and stability of laser output power. During the last two years, excimer laser TFT annealing technology has moved out from the research and development laboratories to the production floors of all main display manufacturers throughout Japan, Korea and Europe. Currently, the first mass-produced displays of various sizes are available on the market.