Design of sequential lateral solidification crystallization method for low temperature poly-Si thin film transistors

Sequential lateral solidification (SLS) is known as a promising method for making low-temperature poly-Si thin film transistors (LTPS TFT) with superior performance for the fabrication of highly circuit-integrated flat panel displays such as TFT liquid crystal display (LCD) and TFT organic light Emitting diode (OLED). In this work we studied the dependence of TFT characteristics on SLS poly-Si grain width and suggested the methods of designing SLS mask pattern to achieve uniform TFT performance. We varied the width of the poly-Si grain by employing the 2-shot SLS mask pattern with different overlaps between the 1st and 2nd laser pulses. The width of the poly-Si grain decreased with decreasing the overlap. However, the measured TFT characteristics revealed that the width of the poly-Si grain negligibly influences the device properties. We could achieve the TFT mobility of approximately 350cm(2)/V.S for the overlap of not less than I pin. We suggested that the SLS mask pattern (x, y) should be designed such that 2 + y less than or equal to x less than or equal to 2 (C-SLG distance) and y > (optical resolution), where x is the spacing of the laser-absorbed region and y is the spacing of the laser-nonabsorbed region on the substrate.