Optical pattern recognition measurements of trench arrays with submicrometer dimensions

We describe two pattern recognition algorithms for measuring half-micrometer focus-exposure dense photoresist line structures by using optical microscopes, such as a confocal scanning microscope and an interference microscope. The first approach depends on a data-clustering technique that allows us to measure resist lines down to 0.3 µm. The second method is an improved calibration procedure that utilizes multiple regression and moments of a cloud plot. Linearity between optical and scanning electron microscopy measurements is achieved down to 0.3 µm for nested focus-exposure resist structures with a standard deviation of 10 nm.