Hybrid mask and method of making same
View Patent ↗A hybrid topography mask is designed for facilitating the fabrication of a semiconductor wafer. The hybrid mask includes a substrate having a light receiving surface. The light receiving surface defines a plane. Pluralities of pattern elements are etched into and out of the light receiving surface. Each of the plurality of pattern elements defines a pattern surface that is parallel to the light receiving surface. Pattern sides extend between the pattern elements and the light receiving surface. Each of the pattern sides extends perpendicularly between the light receiving surface and the pattern elements. The hybrid mask also includes a tapered sub-resolution assist element etched out of the light receiving surface to position the mask with respect to the semiconductor wafer. The tapered sub-resolution assist element is fabricated to avoid affecting any photoresist residue from the sub-resolution assist element's presence on the semiconductor wafer disposed adjacent the hybrid mask.
1. 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.
2. The method of claim 1 , wherein the at least one primary pattern element comprises a plurality of OPC edge pedestal-type elements formed at the edge portions of the mask, and the at least one secondary pattern element comprises a plurality of center pedestal-type elements and are formed at the center portions of the mask; and
wherein critical dimensions of the OPC edge pedestal-type elements are substantially larger than critical dimensions of the center pedestal-type elements.