New exposure tool management technology with quick focus measurement in half pitch 22nm generation

We have developed the new technology to measure focus variations in a field or over the wafer quickly for exposure tool management. With the new technology, 2-dimensional image(s) of the whole wafer are captured with diffraction optics, and by analyzing the image signal(s), we are able to get a focus map in an exposure field or over the entire wafer. Diffraction-focus curve is used instead of a CD-focus curve to get the focus value from the image signal(s). The measurements on the production patterns with the production illumination conditions are available. We can measure the field inclination and curvature from the focus map. The performance of the new method was confirmed with a test pattern and production patterns.