Patent ID: 7759023

Claim:
A method of forming a photolithography mask, comprising: providing a transparent mask substrate; forming a first photoresist layer over the substrate; patterning the first photoresist layer; patterning the substrate so as to form first features in the substrate by using the first photoresist layer as a mask; forming a second photoresist layer over the patterned substrate; patterning the second photoresist layer; and patterning the substrate so as to form second features by using the second photoresist layer as a mask; wherein the first features comprise at least one primary pattern element comprising at least one sidewall extending from a light receiving surface portion of the substrate perpendicularly to a surface portion of the primary pattern element, and the second features comprise at least one secondary pattern element comprising at least one sidewall extending from the light receiving surface portion of the substrate non-perpendicularly to a surface portion of the secondary pattern element.