What are coater/developers?
In a process similar to creating photographic prints, a microscopic circuitry pattern is projected onto the wafer that has been coated with a light-sensitive chemical. Like camera film, the wafer is then developed, leaving behind a stenciled pattern of photoresist to define the areas on the wafer that will be affected by the remaining steps in the transistor cycle. The light-sensitive material, called resist, is deposited by coater/developers. This process is repeated-and a new circuitry pattern is used-each time another layer of the chip is built.
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