Improvement of TFT LCD Yield Loss due to AS-Residue Occurred During Process

• Main Authors: Lu,Jung-Shu, 呂榮書
• Other Authors: Huang, Man-Fang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/s8m6uf

碩士 === 國立彰化師範大學 === 光電科技研究所 === 106 === This thesis is to investigate the cause of residue left on the amorphous silicon (a-Si) layer during process procedures of thin film transistor (TFT) liquid crystal display (LCD). The residue could be left on the a-Si layer after dry etch process of the second procedure. There are some abnormal bright points (BPs) observed on the TFT-LCD during testing when lightening the module set and posteriors cell. First, chapter one introduces the basic operation theory and major components of TFT-LCD. In chapter two, the production processes of the TFT-LCD are briefly introduced. Then, the mechanisms for the formation of residues on the a-Si layer are explored in all possible respects. In chapter three, experimental conditions of four categories to verify the possible causes of abnormal a-Si residue formation are carefully designed and listed as follows. 1. Environmental micro (nano) particles inside both cassette and storage stock are measured. 2. The efficiency of dry cleaner to remove particles on the surface substrate before dry etching is measured to see if the flow speed of dry cleaner affects the formation of abnormal residues. 3. Particles in the load-lock closed chamber are measured to if the valve movement of load-lock chamber affects the formation of abnormal residues. 4. Particles in the dry etching process chamber are measured to see if particles formed during process cause the formation of abnormal a-Si residues. Based on the testing results, sudden particle increment in the dry etching process chamber is the main cause of a-Si residue. The strategy to solve residue problem is then provided and verified. From the test results, a-Si residue in TFT arrays is reduced form 2.3 ea down to 0.5 ea in average. BP leakage ratio caused by a-Si residue after etching was reduced from 3% to 1%. Finally, module failure ratio caused by a-Si residue after etching was also decreased from 11.11% to 2.38%. Therefore, the real problem to cause abnormal a-Si residues is solved. Finally, chapter four is the conclusion.