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The SPI #02863-AB Tin-on-Carbon SEM performance test specimen consists of discrete tin particles actually uniformly round spheres on a roughened carbon background. It is intended for performance checking of the SEM at magnifications at or above 50,000X in environments such as semiconductor production where the SPI Gold-on-Carbon performance test specimen cannot be used.
The individual tin particles are typically about 30 nm in diameter and are spherical. Below about 50,000X, the particles cannot be imaged, but the surface roughness of the carbon substrate is suitable for rough focusing. Above 50,000X, the individual particles can be resolved, and the instrument can be focused and stigmated at the magnification of interest. Individual particles will range from about 10 nm to about 100 nm, and the distance between particles will vary in a similar manner. Since we "know" that the individual particles are spheres which are not fused together, the resolution of the instrument can be estimated from the minimum spacing at which the particles are clearly distinct from each other.
Both the lower atomic number of tin and the spherical nature of the individual particles make the SPI #02863-AB test specimen more difficult to use than the SPI Gold-on-Carbon SEM test specimen, so we suggest that the use of the 02863-AB specimen be restricted to those who cannot use the gold-on-carbon specimen.
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