Active Contour Method Based Sub-pixel Critical Dimension Measurement of Thin Film Transistor Liquid Crystal Display (TFT-LCD) Patterns

A novel application-oriented sub-pixel measurement method utilizing an active contour model with image resampling is presented for a critical dimension (CD) measurement of pixel patterns of a flat-panel thin film transistor crystal display (TFT-LCD) and organic light-emitting diode display. In modern manufacturing of flat panel display, optical measurement of each dimension of pixel patterns has a critical role in the process control, and the resolution of a measurement system becomes a limitation of the manufacturing process. Several methods have been developed to overcome this limit at the image post processing stage, but as the level of pixel integration and manufacturing throughput are increasing rapidly, more robust and effective inspection approach is required. In this paper, a novel sub-pixel level edge detection algorithm with active contour method and fast pixel resampling is proposed for micron scale CD measurement, and its advantages on measurement repeatability and noise handling are presented, along with the results of various industrial sample measurements and comparison with conventional critical dimension measurement algorithms.