Patent ID: 8506827

Claim:
A method, comprising: providing a first grating including a plurality of grating lines formed from a dielectric material, each grating having a pair of sidewalls, facing sidewalls of adjacent grating lines being separated by corresponding trenches, the grating lines and trenches forming a grating surface; forming a layer of a metal on the grating surface, where the metal layer has a constant thickness and conforms to the grating surface; and removing portions of the metal layer between sidewalls of adjacent grating lines of the first grating to form a metal grating having grating lines formed from the metal, the grating lines of the metal grating corresponding to the portions of the metal layer adjacent the sidewalls of the grating lines of the first grating, wherein the metal grating has a pitch of 200 nm or less, a depth of 50 nm or more, and the grating lines of the metal grating have an aspect ratio of 10-to-1 or more.