Photomask having line end phase anchors

US7018747B2 · kind B2 · utility

Assignee

• Freeescale Semiconductor, Inc. · US

Inventors

• Wei E. Wu · Austin, US
• Bernard J. Roman · Austin, US

Key dates

• Filing date: Oct 1, 2002
• Grant date: Mar 28, 2006
• Expiry date: Feb 24, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F1/26
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A photomask and a method for making the same in which an opaque feature (38) is formed on a transparent substrate (32) and a depression (44) is etched in the transparent substrate (32) adjacent to the opaque feature (38). The depression (44) is etched to a depth such that a phase difference between light passing through the substrate (32) outside the depression (44) and light passing through the depression is 180°. In one embodiment, the depression (44) is formed in the substrate directly adjacent to an edge of the opaque feature (38). In another embodiment, the depression (58) surrounds a mesa structure (59) formed in the substrate (50), and the opaque feature (62) resides on the mesa structure (59). The depression (58) may be laterally spaced from an edge of the opaque feature (62).