Measurement technologies can be broadly categorized into model-free and model-based techniques. Model-free metrology, such as conventional optical microscopy, can directly derive geometric dimensions of a specimen from acquired images through edge detection algorithms. While this "what-you-see-is-what-you-get" approach offers advantages of simplicity and intuitiveness, it often exhibits certain...

Traditional optical imaging systems operate on a direct physical mapping mechanism, in which lightis refracted by optical lenses, is focused onto the sensor plane, thereby establishing a “point-to-point” mapping relationship between the object and the image plane. This process provides a uniform sampling and reproduction of the object’s radiation intensity in real space, offering a “what yo...

The fabrication of a single advanced-node logic or memory chip typically involves thousands of steps, including wafer preparation, deposition, lithography, etching, polishing, cleaning, and metrology, many of which are repeated throughout the process. Lithography is the most critical step, using a scanner or stepper to transfer circuit patterns from a mask onto a photoresist-coated silicon wafe...