Microlithography 1994
Conference paper

Quantitative stepper metrology using the focus monitor test mask

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A new lithographic test pattern, the focus monitor, is introduced. Through the use of phase shift techniques, focus errors translate into easily measurable overlay shifts in the printed pattern. Each individual focus monitor pattern can be directly read for the sign and magnitude of the focus error. This paper will present a detailed verification of the validity of this approach, along with several preliminary applications.