Patent ID: 7494765

Claim:
A method for patterning pillars, the method comprising: a) projecting light onto photoresist using a photomask, the photoresist being a positive resist, the photomask comprising: a plurality of transmitting nonprinting windows transmitting light in a first phase and having a shortest linear dimension D 1 parallel to the photomask surface between about 50 nm×S and about 160 nm×S where S is a projection scaling factor; a transmitting area transmitting light in a second phase, each of the plurality of transmitting nonprinting windows being substantially entirely surrounded by and in contact with the transmitting area along a perimeter, but without intervening blocking material; wherein a plurality of borders is formed where light in the first phase meets light in the second phase; wherein light in the first phase is canceled at least in part by the light in the second phase; wherein a first width D 2 of unbroken transmitting area surrounds each of the plurality of transmitting nonprinting windows on all sides, the first width D 2 being sufficient for the unbroken transmitting area to print when the photomask is used to expose the photoresist and is between about 100 nm×S and 210 nm×S; and b) developing the photoresist to form a plurality of photoresist features, wherein the plurality of photoresist features are photoresist pillars; wherein the light projected onto the photoresist has an intensity specific to each point on the photoresist, each perimeter corresponds to a plurality of perimeter points on the photoresist, and at least a portion of the plurality of perimeter points has an intensity of zero; wherein each of the plurality of the borders corresponds to one of the plurality of photoresist features; and wherein the plurality of transmitting nonprinting windows is configured to form a nonprinting pattern that corresponds to a feature pattern formed by at least a portion of the photoresist features.