Universal Microscopy Standards

Summary

Microscopy methods for semiconductor manufacturing currently lack the traceability and absolute accuracy that is critical for characterizing future processes. Nanostructure arrays of several types—silicon frusta, metal apertures, polymeric pillars—and corresponding calibration software will improve traceability and absolute accuracy of scanning electron microscopy, atomic force microscopy, and super-resolution optical microscopy. Fabrication, characterization, and dissemination of these artifacts by NIST will advance metrology from lab to fab, extending from tool matching and hybrid metrology to adjacent topics of focused ion beam, photonic integration, and other advanced packaging technologies.

This project will develop microscopy standards that are more widely applicable than existing artifacts for semiconductor manufacturing. 

Grand Challenge 6: Standardizing New Materials, Processes, and Equipment for Microelectronics 

Description

Microscopy standard linking critical dimensions of line-space arrays and frustum arrays of varying pitch, for hybrid metrology by  optical microscopy, scanning electron microscopy, atomic force microscopy, and the NIST line-scale interferometer.

Credit: NIST

Microscopy standards that are available today have inadequate performance characteristics. 

As device linewidths decrease toward physical limits, the international roadmap of devices and systems (IRDS) has set uncertainty targets by the year 2025. This target is hard to hit, challenging the industry to reconcile results from different microscopy methods and tools that are inconsistent beyond this value.   

These inconsistencies indicate the presence of yet unrecognized sources of uncertainty. This significant problem limits not only tool matching but also hybrid metrology, which the IRDS promotes, requiring consistent and accurate results.  

Further, the IRDS has encouraged the development of unconventional imaging methods, such as super-resolution optical microscopy, to detect and characterize defects with high selectivity. 

Building on years of fundamental R&D to fabricate and characterize array standards, and to apply such standards to comprehensively calibrate microscope systems, NIST has set the stage to advance the state of the art in industry within a few years.

This project will deliver microscopy standards and calibration software that improve the traceability and absolute accuracy of scanning electron microscopy, atomic force microscopy, and super-resolution optical microscopy. This new capability is generally relevant to semiconductor manufacturing, will facilitate inter-method and inter-tool comparisons to identify dark uncertainty, will enable reduction of uncertainty by hybridization of consistent results, and will improve efficiency and reliability in adjacent topics of focused ion beam and photonic integration processes. 

The broad availability of NIST standards will improve traceability and absolute accuracy in microscopy throughout the semiconductor manufacturing ecosystem, from lab to fab, helping to address emerging issues of tool matching, and enabling hybrid metrology to hit target uncertainties set by the IRDS.