Advanced laser micromachining techniques for a TFT‐LCD (thin film transistor‐liquid 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 TFT‐LCD. The techniques are as follows: (i) The technique of zapping the excess metal: to repair short defects and/or to isolate the TFT being tested from the adjacent TFTs. This uses a pulse Xe or a Q‐switched YAG laser. (ii) Zapping, followed by the metal deposition technique: to repair open defects and/or to form electrical testing electrodes. This uses a Q‐switched YLF and an Ar ion laser. (iii) The technique of micro‐welding two metal lines separated by an insulating layer: to repair open defects. This uses a Q‐switched YAG laser. (iv) A separation technique utilised on a TFT‐LCD panel adhered with epoxy resin. This uses a pulse Excimer laser. (v) A micro‐annealing technique for a degraded TFT: to recover the TFT characteristics. This uses a Q‐switched YAG laser. Through the study described above, the authors have confirmed that these techniques are highly effective for obtaining TFT‐LCD modules without defects. The yield of TFT‐LCD modules may therefore be expected to improve.
Tobita, T., Niki, K., Inouye, K. and Takasago, H. (1992), "Optimised Laser Micromachining Technology for TFT‐LCD Modules", Microelectronics International, Vol. 9 No. 1, pp. 17-20. https://doi.org/10.1108/eb044465Download as .RIS
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