Metrology standards for semiconductor manufacturing

In semiconductor manufacturing, the performance of metrology equipment directly impacts yield. Fabs and equipment suppliers depend on calibration standards to ensure that their metrology results are within tolerances and to maintain their ISO and QS quality certifications. This task becomes more challenging as the device features shrink and tolerances become tighter, to the extent of their physical limits in many cases. As the industry keeps finding ways to meet the demanding metrology requirements, calibration standards have been developed and enhanced for all essential measurements, i.e. critical dimensions, thin films, surface topography, overlay, doping, and defect inspections. This paper provides an overview of such standards and demonstrates how they are certified and tested to be traceable to the International System (SI) unit of length in order to ensure reliable and transferable calibrations for fabs. The latest results on 50 nm critical dimension (CD) standards. 2 nm film thickness standards, and 50 nm particle sizing standards, along with their certification strategies, are also presented.