Contact hole application for lithography process development using the Opti-Probe three-dimensional RT/CD technology

This paper presents measurement results of the 3-D contact hole profiles using RT/CD technology for various diameter-to-space (D/S) ratios and film stacks. The key controlling parameters (hole depth, diameter, sidewall angle, and hole openness, etc.) for lithography processing of contacts and vias were studied in terms of measurement sensitivity on samples with different pitches and D/S ratios and film stacks. Good correlation (R2 ~ 0.99) between CD-SEM and RT/CD was obtained for the sample structures. The static and dynamic measurement stability of contact diameter and contact depth was better than 1 nm using simple profile modeling.