Full spectral analysis of line width roughness

Various approaches can be used to quantify line width roughness (LWR). One of the most commonly used estimators of LWR is the standard deviation. However, this approach is incomplete and ignores a substantial amount of information. We propose here a full spectral analysis to investigate and monitor LWR. A variety of estimators, such as standard deviation, peak-to-valley, average, correlation length and Fourier analysis have been implemented on-line on CDSEM. The algorithms were successfully tested against e-beam written LWR patterns, both deterministic and random. This approach allows a fully automated investigation of LWR. This methodology was used to monitor LWR over a long period of time, benchmark new resists and to investigate the effect of LWR on device performance and yield.