PARIS The Electronics and Information Technology Laboratory of the CEA (CEA-Leti) of France claimed it has been able to reduce measurement uncertainty in the sub-28nm nodes.
As part of the Hybrid Metrology Project, CEA-Leti said it aims to help equipment companies develop a CD metrology production tool dedicated to hybrid metrology that will reduce R&D cycle time and improve production yield for manufacturers.
CEA-Leti noted that the Hybrid Metrology Project has demonstrated a way to reduce measurement uncertainty at sub-28nm nodes using an alternative 3D-AFM (atomic force microscope) mode for CD measurement, the Deep Trench Mode.
Project leader Johann Foucher explained that CD hybrid metrology potentially could be introduced in high-volume manufacturing for sub-28nm nodes. That would require hybrid metrology tools and software that simplify the communication and optimization of complementary techniques to obtain a relevant and low-cost CD metrology configuration.
This hybrid metrology platform, CEA-Leti researchers continued, would ease and optimize data exchange between reference and production techniques. It decreases the number of measurement iterations as a function of accuracy control since it prevents introduction of residual errors due to poor accuracy of the initial production CD metrology technique, they claimed.
CEA-Leti said it observed that by using a reference in-line CD technique such as CD-AFM, it is possible to replace most cross-section images now achieved by scanning electron microscopy or transmission electron microscopy. The result is faster R&D cycle time for any kind of process control lithography and etching.
For yield production, the accuracy lowers the total-measurement-uncertainty parameter and guarantees better CD uniformity and process window definition on a full wafer. "The fabricated devices would have fewer performance variations from die to die, wafer to wafer and lot to lot, which results in higher production yield," researchers claimed.