Grating Improves Overlay Metrology

摘要

Lithography is in constant transition. Currently, the major area of development is in subwavelength lithography, where device features considerably smaller than the tool's wavelength are printed. As design rules continue to shrink, so too are lithography process windows, which represent the amount of allowed CD and overlay variation during manufacturing. This affects the focus and exposure latitude within which a desired feature can be printed within specification. Resolution enhancement techniques such as optical proximity correction, phase-shift masks and double exposure are used to enable pattern printing in subwavelength lithography.