SURF-CAL PSL spheres simplify the job of preparing calibration wafers in your facility by providing pre-mixed PSL spheres in a 50ml bottle. Particle sizes correspond to the calibration point sizes required by instrument manufacturers. Particle concentrations are 1 x 10 e10 particles per mL. SEMI manufactures have demanded specific particle sizes to be used when calibrating Scanning Surface Inspection Systems, also referred to wafer inspection tools. Working with instrument manufacturers the SURF-CAL PSL spheres meet SEMI standard M52 (3) and M53 guidelines. Available sizes are critical sizing nodes as defined by the International Technology Roadmap for Semiconductors, ITRS (1).
By depositing SURF-CAL, NIST traceable PSL (polystyrene latex) spheres on bare silicon and pattern wafers, you can perform periodic size calibration checks on your KLA-Tencor, Hitachi, ADE, Topcon SSIS tools and compare your wafer inspection scanner with scanners at other locations. You can also assess the performance of your SSIS at critical stages in the manufacturing process.
All products are suspended in deionized, filtered water (DI water) in 50 mL bottles at a concentration of 3 x1010particles per mL. These PSL Spheres have been sized by Differential Mobility Analyzer (DMA) or other size exclusionary techniques.
To assure NIST traceability, the certified diameters of these products were transferred by transmission electron or optical microscopy from NIST standard reference materials (2). The uncertainty was calculated using NIST Technical Note 1297, 1994 Edition “Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results” (4). The uncertainty listed is the expanded uncertainty with a coverage factor of two (K=2). The peak diameter was calculated using approximately the ± 2s range of the particle size distribution. The size distribution was calculated as the standard deviation (SDS) of the whole peak. The Coefficient of Variation (CV) is one standard deviation expressed as a percentage of the peak diameter. The FWHM (full width at Half Maximum) distribution was calculated as the distribution at half of the peak height expressed as a percentage of the peak diameter.
1. “The National Technology Roadmap for Semiconductors”, Semiconductor Industry Association (1999)
2. S.D. Duke and E.B. Layendecker, “Internal Standard Method for Size Calibration of Sub-Micron Spherical Particles by Electron Microscopy”, Fine Particle Society (1988)
3. SEMI M52 — Guide for Specifying Surface Inspection Systems for Silicon Wafers the 130 nm Technology Generation.
4. Barry N. Taylor and Chris E. Kuyatt, “Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results”. NIST Technical Note 1297, 1994 edition, September 1994.