The National Institute of Standards and Technology (NIST), Advanced Surface Microscopy (ASM), and the National Metrology Centre (NMC) of the Agency for Science, Technology, and Research (A*STAR) in Singapore have undertaken a three-way interlaboratory comparison of traceable pitch measurements using atomic force microscopy (AFM). The specimen being used for this comparison is provided by ASM and consists of SiO2 lines having a 70 nm pitch patterned on a silicon substrate. NIST has a multifaceted program in atomic force microscope (AFM) dimensional metrology. One component of this effort is a custom in-house metrology AFM, called the calibrated AFM (C-AFM). The NIST C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the iodine-stabilized He-Ne laser. NIST is using the C-AFM to participate in this comparison. NMC/A*STAR is using a large scanning range metrological atomic force microscope (LRM-AFM). The LRM-AFM integrates an AFM scanning head into a nano-stage equipped with three built-in He-Ne laser interferometers so that its measurement related to the motion on all three axes is directly traceable to the SI unit for length. ASM is using a commercially available AFM with an open-loop scanner, calibrated by a 144-nm pitch transfer standard. In a prior collaboration with Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, ASMs transfer standard was calibrated using PTBs traceable optical diffractometry instrument. Thus, ASMs measurements are also traceable to the SI meter. The measurements for this interlaboratory comparison have been completed and the results are in agreement within their expanded uncertainties and at the level of a few parts in 104.
Proceedings Title: 2010 SCANNING/SPIE Proceedings
Conference Dates: May 17-20, 2010
Conference Location: Monterey, CA
Conference Title: 2010 SCANNING/SPIE
Pub Type: Conferences
AFM, metrology, pitch, standards, calibration, traceability