Method to monitor stepper lens quality in color filter process
Pigment-based resists tend to give off a certain amount of organic vapor during exposure. This brings about contamination of the projection lens surface as well as other parts of the system. A method to monitor this accumulation of solvent vapor on the lens surface is disclosed, based on a test matrix (in which exposure time and focal distance are systematically varied) through which a series of images are formed in the resist and then evaluated for quality. A key feature is the test patterns that are used for forming the images. Said patterns are designed so as to maximize the total amount of diffraction that occurs during image formation, thereby maximizing sensitivity to changes in lens quality. Several examples of the test patterns are provided.
Taiwan Semiconductor Manufacturing Company
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inventional inventional inventional
Kuo-Liang Chih-Kung Sheng-Liang Bii-Jung
Lu Chang Pang Chang