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YoHan Kim 0540541

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Thin Film Layer of material ranging from fractions of nanometer to several micro meters in thickness Thin Film Process Process to make thin film on a substrate

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Thermal oxidation Physical Vapor Deposition Vaporized material bombards onto substrate, i.e. Si wafer. Chemical Vapor Deposition Gaseous material reacts on substrate to form thin film

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Vacuum deposition Evaporation of material required More expensive, but high quality Sputtering is widely used Aluminum, Titanium, Titanium nitrate, Tungsten silicide

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Gas form of material goes under chemical reaction with substrate to form thin film Remnant gas remains after reaction Fast, cheap, but poor quality Forms variety of thin film

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Process to make patterns on a wafer Removes unwanted area of thin film deposited in previous stage

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Key of Photolithography, called PR Type of organic material Very sensitive to UV

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Two types of photoresist Positive: Exposed PR is removed Negative: Exposed PR remains

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Wet Etching uses chemicals Dry Etching uses plasma

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Photoresist is organic material Must be stripped off after etching

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Sometimes the surface has to be flattened after removing PR Mechanically polished

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Fabricating nanoscale device is repetition of thin film process and photolithography Up to 20~30 cycles are repeated Each layer of semiconductor requires at least 2 photolithography masks

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Extreme UV lithography X-Ray Lithography LIGA(x-ray lithographie galvanoformung abformtechnik), German acronym which means x-ray lithography electro- deposition moding LIGA is good in 3D fabrication Photolithography will not be abandoned

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