Advances in lithography create a unique challenge for process window control with defects inspection tools. As the
technology moves towards smaller line widths and more complicated structures, the sensitivity requirements for some
process defects become higher, such as defocus and dose defects at 50nm or lower technology nodes. Currently
automated macro inspection tools are used to detect a wide range of macro defects in the litho area, such as coating
defects, particles, scratches, as well as the process defects. Most tools, however, cannot satisfy the new sensitivity
requirements for the process defects while maintaining their current inspection capability for other defects. Rudolph
Technologies approaches this challenge by integrating a unique polarization-imaging configuration, which enhances
detection of defocus and dose defects without sacrificing the existing capability to detect other types of macro defects.
The improved inspection system has demonstrated high sensitivity for defocus and dose defects on production wafers at
multiple process nodes at high throughput.