Automatic inspection of the width and gap of etching transistors in TFT-LCD panels using sub-pixel accuracy estimation

Abstract

In this paper, the width and gap of etching transistors in TFT-LCD panels were measured using sub-pixel accuracy estimation, and the accuracy was tested in a noisy environment. The concept of line width measurement was introduced in terms of line distance and defect measurement based on the low and high spatial frequency distribution change of TFT-LCD panel image. Some patterns do not need to have the line width and distance measured, while others have different measurement requirements. The conductor border of a pattern is normally an area with a flat change of grey scale, but we are still able to find an accurate measurement with the proposed method. In the TFT-LCD testing pattern, there are circular etching structures, and for measurement we focus on the position of the center of the circle and the size of the radius. This method can be used quickly and accurately for measuring the TFT short, ITO open, marking, spot particle or scratching on the panel caused by over etching.