4 ecen 475 18 example o3ai sketch a stick diagram for

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Unformatted text preview: during focus and alignment and removed during wafer exposure Reticle (may contain one or more die in the reticle field) Projection lens (reduces the size of reticle field for presentation to the wafer surface) Single field exposure, includes: focus, align, expose, step, and repeat process Wafer stage controls position of wafer in X, Y, Z, θ ECEN 475 93.4 Stepper Exposure Field UV light Reticle field size 20 mm 15mm, 4 die per field 5:1 reduction lens Image exposure on wafer 1/5 of reticle field 4 mm 3 mm, 4 die per exposure Serpentine stepping pattern Wafer 04.4 ECEN 475 20 Photo-resist Negative Resist Wafer image is opposite of mask image Exposed resist hardens and is insoluble Developer removes unexposed resist Positive Resist Mask image is same as wafer image Exposed resist softens and is soluble Developer removes exposed resist ECEN 475 14.4 Negative Lithography Ultraviolet light Chrome island on glass mask Areas exposed to light become crosslinked and resist the developer chemical. Island Exposed area of photoresist Window Photoresist Shadow on photoresist Photoresist Oxide Oxide Silicon s...
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