Photomask, exposure apparatus, and method of fabricating three-dimensional semiconductor memory device using the same
Disclosed are a photomask, an exposure apparatus, and a method of fabricating a three-dimensional semiconductor memory device using the same. The photomask may include a mask substrate, a first mask pattern on the mask substrate, and an optical path modulation substrate. The optical path modulation substrate may include a first region on a portion of the first mask pattern, and a second region on another portion of the first mask pattern. The second region has a thickness that is less than a thickness of the first region.
1. A photomask, comprising:
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.
2. The photomask of claim 1 , wherein the second region comprises a recess in one of the first and second surfaces.
3. The photomask of claim 2 , wherein the recess has a curvature radius ranging from 160 cm to 1400 cm.
4. The photomask of claim 1 , further comprising a second mask pattern on the first region and the second region of the optical path modulation substrate.
5. The photomask of claim 4 , wherein the second mask pattern is aligned with the first mask pattern.
6. The photomask of claim 4 , wherein the first surface-comprises a trench, and
wherein the second mask pattern is disposed in the trench, and wherein the second surface comprises a recess in the second region of the optical path modulation substrate.
7. The photomask of claim 4 , wherein the second mask pattern has a triangular cross-section.
8. The photomask of claim 1 , further comprising a supporting portion disposed on an edge of the mask substrate, wherein the supporting portion supports the optical path modulation substrate.
9. The photomask of claim 8 , wherein the supporting portion comprises at least one of a sealant or an adhesive.
10. The photomask of claim 1 , wherein the mask substrate and the optical path modulation substrate comprise quartz.
11. 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.
12. The exposure apparatus of claim 11 , wherein the second region comprises a recess in one of the first and second surfaces, and wherein the recess has a curvature radius ranging from 160 cm to 1400 cm.
13. The exposure apparatus of claim 11 , wherein the photomask further comprises a second mask pattern on the first region and the second region of the optical path modulation substrate, wherein the second mask pattern is aligned with the first mask pattern.
14. The exposure apparatus of claim 13 , wherein the first mask pattern and the second mask pattern comprise chromium.
15. The exposure apparatus of claim 11 , wherein the mask substrate and the optical path modulation substrate comprise quartz.
16. 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.
17. The method of claim 16 , further comprising:
forming an interlayer insulating layer covering the dummy pad patterns and the dummy additional layers on the connection region and the layered structure on the cell array region; and
partially removing the interlayer insulating layer, the layered structure, the dummy pad patterns, and the dummy additional layers to form line-cut trenches.
18. The method of claim 17 , further comprising:
removing the horizontal layers, the dummy pad patterns, and the dummy additional layers exposed by the line-cut trenches; and
forming word lines and pad patterns in regions, which are formed by removing the horizontal layers, the dummy pad patterns, and the dummy additional layers.
19. The method of claim 18 , further comprising:
forming contact holes in the interlayer insulating layer to expose the pad patterns; and
forming contact plugs in the contact holes.
20. The method of claim 16 , wherein the second photoresist pattern is thinner than the first photoresist pattern.