Abstract
For robustness improvement of inline metrology tools, we propose an inline reference metrology system, named verification metrology system (VMS). This system combines inline metrology and nondestructive reference metrology tools. VMS can detect the false alarm error and the nondetectable error caused by measurement robustness decay of inline metrology tools. Grazing-incidence small-angle x-ray scattering (GI-SAXS) was selected as the inline reference metrology tool. GI-SAXS has high robustness capability for under-layer structural changes. VMS with scatterometry and GI-SAXS was evaluated for measurement robustness. The potential to detect metrology system errors was confirmed using VMS. Cost reduction effect of VMS was estimated for the false alarm case. Total cost is obtained as a sum of the false alarm losses and the metrology costs. VMS is effective for total cost reduction with low sampling. Also, it is important that the sampling frequency of reference metrology is optimized based on process qualities.
Highlights
As the pattern size of semiconductor devices is shrinking, a higher level of measurement accuracy of inline metrology is required
verification metrology system (VMS) is effective for total cost reduction with low sampling
For robustness improvement of inline metrology tools, we propose an inline reference metrology system, named VMS
Summary
As the pattern size of semiconductor devices is shrinking, a higher level of measurement accuracy of inline metrology is required. Higher accuracy metrology technology for generation devices is required for the pattern size shrinkage, and for high-level process controls such as APC. In this case, the correlation only shows variation from the linear regression line. The correlation only shows variation from the linear regression line This variation is caused by random variation of the inline metrology tool. These process variations cause offset changes and correlation changes by measurement robustness decay.
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