Reduction projection printing

Even though projection optics embodies the inherent limitation of pattern transfer just mentioned, this technique has become a dominant approach in high-resolution work. A key reason for this success is the ability of projection printing to use reduction refraction optics with high numerical apertures. The resolving power of projection systems can be approximated by ... 

For reduction projection systems, dimensions on the reticle are printed with demagnihcation onto the wafer. The effective mask dimension error is expected to be reduced by the demagnihcation factor. For imaging large mask features, a unit of error on the mask corresponds to a unit change in printed size scaled hy the reduction ratio of the exposure system ... 

As mentioned above, the SCALPEL mask is uniformly illuminated hy a parallel beam of 100-keV electrons. In the SCALPEL exposure tool, a reduction-projection optic in a telecentric doublet arrangement produces a 4 1 demagnified image of the mask at the wafer plane. Given that the features to be printed are much larger than the wavelength of the electrons (X. 3.7 pm) used, the full benefits of the... 

Second, because contamination resulting from carbon deposition depends on the local intensity of the EUV radiation at the surface of the mirror, it is possible that certain parts of the mirror surface in the projection optics may experience a local reduction in reflectivity that is larger than that occurring at other locations. The result is apodization of the projection optics, which can cause CD variation across the chip that is printed with EUV lithography. ... 

Scale and Projection. All maps of the Earth s surface require some level of reduction. Map scale is an important concept to maps and mapping because it determines the level of map reduction necessary. Scale is the ratio of a distance measured on a map to the distance it represents in the real world, using the same units of measurement. For example, 1 inch measured on a map with a scale of 1 24,000 represents 24,000 inches (or 2,000 feet) in the real world. The scale used on any given map determines the size of the area that can be represented as well as the level of detail that can be depicted. In addition to the representative fraction (for example, 1 100,000), scale can be shown using a verbal statement such as 1 inch equals 1 mile or a graphic or bar scale printed directly on the map. 

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