Translator Disclaimer
16 July 2002 Advanced process control of overlay with optimal sampling
Author Affiliations +
This paper evaluates sampling plans for overlay metrology in the context of Advanced Process Control (APC). The relationship between APC opportunity (the maximum benefit achievable via APC) and correctable accuracy is investigated. The tradeoff between spatial and temporal sampling density is considered as well. This tradeoff expresses the relationship between temporal sampling needed to realize APC benefit and spatial sampling needed to achieve a level of total overlay error. We find that the spatial sampling plan impacts both the proportion of process disturbance in the measured variability and the frequency distribution of the disturbance. As a result of a smaller magnitude and lower frequency disturbance in the10-field plan, APC performance with this plan is substantially better than with the 4-field plan. Over a realistic range of temporal sampling, APC of correctables derived from the 10-field sample plan result in a 20 to 25 percent improvement over the baseline of no control on 4-field based correctables. When APC is applied to 4-field correctables, only about 8 to 10 percent improvement is achieved.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Craig Garvin, Xuemei Chen, and Matt Hankinson "Advanced process control of overlay with optimal sampling", Proc. SPIE 4689, Metrology, Inspection, and Process Control for Microlithography XVI, (16 July 2002);

Back to Top