Advanced laser micromachining techniques for a TFTLCD thin film transistorliquid crystal display module have been developed to repair various kinds of defects such as shorts, opens, and degraded TFTs. They have also been designed to analyse failures in the TFTLCD. The techniques are as follows i The technique of zapping the excess metal to repair short defects andor to isolate the TFT being tested from the adjacent TFTs. This uses a pulse Xe or a Qswitched YAG laser. ii Zapping, followed by the metal deposition technique to repair open defects andor to form electrical testing electrodes. This uses a Qswitched YLF and an Ar ion laser. iii The technique of microwelding two metal lines separated by an insulating layer to repair open defects. This uses a Qswitched YAG laser. iv A separation technique utilised on a TFTLCD panel adhered with epoxy resin. This uses a pulse Excimer laser. v A microannealing technique for a degraded TFT to recover the TFT characteristics. This uses a Qswitched YAG laser. Through the study described above, the authors have confirmed that these techniques are highly effective for obtaining TFTLCD modules without defects. The yield of TFTLCD modules may therefore be expected to improve.
Microelectronics International – Emerald Publishing
Published: Jan 1, 1992