Design considerations for a test structure which can be used to determine the optimum focus

A test structure which can be used to optimize the focus of wafer steppers is described. Simulation is used to determine the optimum setting for some of the design parameters in order to ensure maximum sensitivity of the device. Preliminary results indicate that the resistance of the structure is sensitive to changes in both exposure and focus, but that the 'noise' on the measurement masks the true sensitivity.<
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