Cross-evaluation of critical dimension measurement techniques

Abstract

Critical dimension control is essential in the semiconductor industry and becomes more challenging as photolithography limits keep getting pushed to reach technological nodes smaller than 10 nm. To ensure the quality and control of the processes, it becomes necessary to explore new metrology techniques. In this sense, critical dimension small-angle x-ray scattering (CDSAXS) has been identified as a potential candidate for determining the average shape of a line grating with a sub-nanometric precision. We benchmark the CDSAXS results obtained at the synchrotron to the optical critical dimension, critical dimension scanning electron microscopy, and transmission electron microscopy measurements collected from industrial metrology tools either at the manufacturing line or in the characterization laboratory. Emphasis is placed on the impact of the use of independent model for each technique and the benefits of unifying it in a unique model. We also discuss the differences between all of these multi-scale and multi-physics techniques, question our capacity to compare them, and eventually correlate the results obtained on several samples.