Lithography mask with a .pi.-phase shifting attenuator

  • US 4,890,309 A
  • Filed: 02/25/1987
  • Issued: 12/26/1989
  • Est. Priority Date: 02/25/1987
  • Status: Expired due to Term
First Claim
Patent Images

1. Lithography mask including open features and an attenuator whose material and thickness are selected to both pass a fraction of incident electromagnetic radiation and to phase shift the radiation relative to radiation passing through the open features of the mask by approximately an odd multiple of π

  • radians in order to reduce deleterious diffraction effects.

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