This report refers to a new series of turbo molecular pumps, of a magnetically levitated type, designed to evacuate chambers to the ultrahigh vacuum. In the recent semiconductor industry, it is necessary that turbo molecular pumps ensure high-throughput and high-speed evacuation capabilities, so that they can meet the requirements of the latest production process of semiconductors, which are more and more miniaturized in design rule and are more likely to use wafers of a larger diameter, 300 mm at the largest. Shimadzu has successfully developed four models of turbo molecular pumps that provide the required performances. The simulation technology for obtaining high pumping throughput, established prior to our prototype, has provided optimized design of the rotor blades of the pumps. It is necessary to keep rotor temperature as low as possible, because the rotor blades have very complicated designs and are made to rotate at a high speed during high-throughput operation, in which heat is emitted from the compression of the gas and the friction of the gas and the turbine blades. Also, it is necessary that the rotor blades are resistant against corrosive gases which are often used in production of wafers. Our newly developed coating method, named "Dispersion Plating," reduces the rotor blade temperature and enhances the corrosion resistance of the blade surfaces. The power supply has an additional function that it can change the rotation speed of the pump. In spite of high performances, such as high throughput, the pump and the power supply are both designed very compact.
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