Mark, overlay target, and methods of alignment and overlay

• Main Authors: LALBAHADOERSING, SANJAYSINGH, WANG, JIA, SCIACCA, BENIAMINO
• Format: Patent
• Language: Chinese; English
• Published: 16.06.2019
• Subjects: APPARATUS SPECIALLY ADAPTED THEREFOR; BASIC ELECTRIC ELEMENTS; CINEMATOGRAPHY; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; ELECTROGRAPHY; HOLOGRAPHY; MATERIALS THEREFOR; ORIGINALS THEREFOR; PHOTOGRAPHY; PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES,e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTORDEVICES; PHYSICS; SEMICONDUCTOR DEVICES

A mark comprising a periodic structure configured to scatter incident radiation, wherein the periodic structure has a repeated unit cell divided into adjacent first and second portions along a direction of periodicity, the first portion having a first effective refractive index and a first length along the direction of periodicity, the second portion having a second effective refractive index, which is lower over its optical path compared to the first effective refractive index, and a second length along the direction of periodicity, wherein the effective refractive indexes and lengths of the portions are configured to provide: an optical path length of the unit cell in the direction of periodicity that equals an integer multiple of a wavelength present in the spectrum of the incident radiation; and an optical path length of the second portion in the direction of periodicity equal to half of an integer multiple of the wavelength.