Mask assembly and method for manufacturing the same
A mask assembly includes a frame including a frame opening, and a mask disposed on the frame. The mask includes a body portion including an upper surface and a lower surface opposing each other and deposition openings spaced apart from each other, protrusions protruding from the upper surface and surrounding the corresponding deposition openings, and at least one step formation pattern overlapping the protrusions in a plan view and disposed in the body portion.
1. A mask assembly comprising:
a frame including a frame opening; and
a mask disposed on the frame and including:
a body portion including:
an upper surface and a lower surface opposing each other;
deposition openings spaced apart from each other;
protrusions protruding from the upper surface and surrounding the corresponding deposition opening; and
at least one step formation pattern overlapping the protrusions in a plan view and disposed in the body portion.
2. The mask assembly of claim 1 , wherein an inner surface defining each of the deposition openings, of the body portion is inclined at an angle between the upper surface and the lower surface.
3. The mask assembly of claim 2 , wherein one of an angle between the upper surface and the inner surface, and an angle between the lower surface and the inner surface is in a range of about 30° to about 70°.
4. The mask assembly of claim 1 , wherein the at least one step formation pattern comprises one of CuW, AlSiC, and invar.
5. The mask assembly of claim 1 , wherein the at least one step formation pattern overlapping one of the protrusions in a plan view includes a plurality of step formation patterns.
6. The mask assembly of claim 5 , wherein a shape of each of the at least one step formation patterns is one of a circle, an ellipse, and a polygon.
7. The mask assembly of claim 6 , wherein an upper surface of each of the protrusions has a shape similar to the shape of each of the at least one step formation pattern.
8. The mask assembly of claim 1 , wherein the frame and the mask comprise invar.
9. The mask assembly of claim 1 , wherein the frame and the mask have a thermal expansion coefficient of about 6 ppm/° C. or less.
10. The mask assembly of claim 1 , wherein the mask has a crystal structure of BCC, or a crystal structure in which BCC and FCC are mixed.
11. The mask assembly of claim 1 , wherein the body portion has a thickness in a range of about 20 μm to about 200 μm.
12. The mask assembly of claim 1 , wherein the mask is formed by electroforming.
13. A method for manufacturing a mask, the method comprising:
disposing an insulating portion on a support substrate;
primarily growing a plating film on the support substrate by a first electroforming process to form a primarily grown plating film;
disposing an inclusion on an upper surface of the primarily grown plating film to surround the insulating portion;
secondarily growing the primarily grown plating film to cover the inclusion by a second electroforming process to form a secondarily grown plating film;
forming a deposition opening by removing the insulating portion from the secondarily grown plating film; and
forming a mask by removing the support substrate,
wherein a first region of an upper surface of the mask, overlapping the inclusion in a plan view has a greater thickness than a second region adjacent to the first region.
14. The method of claim 13 , wherein
the insulating portion comprises:
a lower surface contacting the support substrate;
an upper surface opposing the lower surface; and
a side surface between the lower surface and the upper surface, and
the second region is thinner than the insulating portion.
15. The method of claim 14 , wherein a first angle between the lower surface and the side surface is one of an acute angle, a right angle, and an obtuse angle.
16. The method of claim 15 , wherein
the mask comprises:
a lower surface contacting the support substrate;
an upper surface opposing the lower surface; and
an inner surface defining the deposition opening, and
the first angle and a second angle between the upper surface and the inner surface are equal to each other.
17. The method of claim 13 , wherein the inclusion comprises one of CuW, AlSiC, and invar.
18. The method of claim 13 , wherein the plating film comprises invar.
19. The method of claim 13 , further comprising:
heat-treating the mask.
20. The method of claim 13 , wherein the mask has a thermal expansion coefficient of about 6 ppm/° C. or less.