Photomask, exposure apparatus, and method of fabricating three-dimensional semiconductor memory device using the same

An exposure apparatus, comprising:

• a stage configured to receive a substrate thereon;
• a light source configured to generate light to be provided onto the substrate on the stage;
• an objective lens disposed between the light source and the stage and configured to concentrate the light onto the substrate;
• and
• a photomask disposed between the objective lens and the light source, wherein the photomask is configured to project a pattern onto the substrate,
• wherein the photomask comprises:
• a mask substrate;
• a first mask pattern on the mask substrate;
• and
• an optical path modulation substrate comprising a first region on a portion of the first mask pattern, and a second region on another portion of the first mask pattern, wherein the second region comprises opposite first and second surfaces that are not parallel to each other and has a thickness that is less than a thickness of the first region.

A method of fabricating a three-dimensional semiconductor memory device, the method comprising:

• forming a layered structure including insulating layers and horizontal layers, which are alternately stacked on a substrate having a cell array region and a connection region;
• forming a first photoresist pattern exposing a portion of the layered structure on the connection region;
• forming dummy pad patterns having a stepped shape on the connection region, using etching and trimming processes, in which the first photoresist pattern is used as an etch mask;
• forming a second photoresist pattern locally exposing the dummy pad patterns, using an exposure apparatus with a photomask;
• and
• forming dummy additional layers on the dummy pad patterns,
• wherein the photomask comprises:
• a mask substrate;
• a first mask pattern on the mask substrate;
• and
• an optical path modulation substrate comprising a first region on a portion of the first mask pattern, and a second region on another portion of the first mask pattern, wherein the second region comprises opposite first and second surfaces that are not parallel to each other and has a thickness that is less than a thickness of the first region.