High-performance display technologies including liquid crystal displays (LCDs) and organic light emitting diode (OLED) based displays require high-performance thin-film transistor (TFT) arrays. This technology is a set of manufacturing techniques for producing polycrystalline thin films with uniform microstructure and crystallographic texture from amorphous or lower quality polycrystalline thin films. It does not require additional processing steps beyond the usual deposition and annealing already employed in TFT fabrication. This method can be used on any material that recrystallizes after melting, including but not limited to silicon. It can also be used in combination with many film deposition methods including ink-jet or shadow mask printing, as well as on patterned films. The films produced are suitable for the production of transistors that can be used in display technologies including active-matrix organic light emitting diode displays (AMOLED displays) and active matrix liquid crystal displays (AMLCD).
This technology takes advantage of existing laser annealing techniques including excimer laser annealing (ELA) and sequential lateral solidification (SLS) to produce highly uniform polycrystalline thin films. A key innovation is tilting the active channel regions of the TFT relative to the structure of the underlying film in order to control the number of grain boundaries comprised by the transistor. Other innovations include shaping of the laser beam used to anneal the film to better account for limitations of the optics used to focus the beam and minimizing the overlap between the regions annealed with successive pulses in order to avoid introducing grain irregularities by overexposing certain parts of the film. The technology is less complex and therefore less costly than current methods for producing uniform film microstructure, for example lithography.
Patent Issued (US8,415,670)
Tech Ventures Reference: IR M07-039