Zone-Based Inspection and Defect Classification for LCD Manufacturing: Trivial Defect Free Procedure for TFT Glass Inspection

Abstract

Inspection of thin film transistor (TFT)-patterned glass is one of the important processes for TFT-LCD panel manufacturing. Minute pattern defects and particles coexist on the glass and a few defects can cause serious quality problems. If there was a way to classify the defects by its potential fatality, it would be useful to control the product quality and loss of inspection time. This article introduces a rule-based approach of zone-based inspection and defect classification. For the zone-based processing, a defect classifier and its decision boundary were also proposed to differentiate non-fatal defects. An experimental result showed that the defect classifier was useful to select non-fatal defects and over 70% of the trivial defects could be selected with little risk of quality problems. This article also presents an application result to utilize the method in a plant. Since prejudged trivial defects have little influence on panel quality, they could be eliminated without interfering with the factor effecting overall final quality. This enables to save post-inspection time. The application results are sufficiently promising to save over 30% in inspection time and, furthermore, only 0.02% of fatal defects are not detectable. The proposed method also brings about an additional return of yield improvement because operator-error is found to be decreased as the defect candidates decrease because of the application of the proposed method.