Multi-exposure semiconductor fabrication mask sets and methods of fabricating such multi-exposure mask sets

A mask set for defining a pattern that includes a first pattern region having a first pitch pattern and a second pattern region having a second pitch pattern on a semiconductor device during the fabrication of the semiconductor device, the mask set comprising:

• a first mask, the first mask comprising:
• a first exposure region that includes a first halftone pattern that defines the first pattern region;
• and
• a first screen region that includes a first shield layer that covers at least some of the second pattern region;
• and a second mask, the second mask comprising:
• a second exposure region that includes a second halftone pattern that defines the second pattern region;
• and
• a second screen region that includes a second shield layer that covers at least some of the first pattern region,
• wherein the second shield layer also extends from the second screen region to cover a portion of the second halftone pattern.

A method of fabricating a mask set for defining a pattern that includes a first pattern region and a second pattern region, the method comprising:

• forming a first halftone layer on a first mask substrate;
• forming a first shield layer on the first halftone layer;
• patterning the first halftone layer and the first shield layer to form a first mask, wherein the first mask includes a first exposure region where the first pattern region is defined and a first screen region that covers the second pattern region, and
• forming a second halftone layer on a second mask substrate;
• forming a second shield layer on the second halftone layer;
• patterning the second halftone layer and the second shield layer to form a second mask, wherein the second mask includes a second exposure region where the second pattern region is defined and a second screen region that covers the first pattern region,
• removing the first shield layer in the first exposure region;
• and
• removing the second shield layer in only a portion of the second exposure region so that the second shield layer extends from the second screen region into a portion of the second exposure region.