US-12624437-B2 - Mask assembly and deposition apparatus of the same

US12624437B2US 12624437 B2US12624437 B2US 12624437B2US-12624437-B2

Abstract

A mask assembly includes a first mask having a first opening and at least one second mask disposed on the first mask, each at least one second mask including a deposition area having second openings, an inner area surrounding the deposition area, and an outer area having third openings which surround the margin area. A line defining the outer boundary of an inner surface which defines the first opening overlaps the inner area when viewed in plan.

Inventors

Sangshin Lee
Sanghoon Kim
Jongsung Park
Sang Min Yi
Seungjin LEE
Eunjoung Jung

Assignees

SAMSUNG DISPLAY CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20221011
Priority Date: 20211015

Claims (14)

1 . A mask assembly comprising: a first mask having a first opening; and at least one second mask disposed on the first mask, each of the at least one second mask comprising a deposition area having second openings, an inner area surrounding the deposition area, and an outer area having third openings which surround the inner area, wherein a line defining an outer boundary of an inner surface which defines the first opening overlaps the inner area when viewed in plan, wherein the at least one second mask defines a thickness direction, wherein the inner area is solid with no openings formed therein, and wherein a minimum width of the inner area in a direction orthogonal to the thickness direction is greater than a maximum separation distance between adjacent second openings of the seconds openings.
2 . The mask assembly of claim 1 , wherein the inner area has a closed-line shape when viewed in plan.
3 . The mask assembly of claim 1 , wherein the third openings are covered by the first mask when viewed from a rear side of the first mask.
4 . The mask assembly of claim 1 , wherein the inner area has a width between about 200 micrometers and about 500 micrometers when viewed in plan.
5 . The mask assembly of claim 1 , wherein each of the second openings has a size different from a size of each of the third openings.
6 . The mask assembly of claim 1 , wherein a separation distance between the second openings adjacent to each other among the second openings is different from a separation distance between the third openings adjacent to each other among the third openings.
7 . The mask assembly of claim 1 , wherein the second openings have a shape different from a shape of the third openings.
8 . The mask assembly of claim 1 , wherein each of the second mask further comprises a welding area attached to the first mask and surrounding the outer area.
9 . The mask assembly of claim 1 , wherein a boundary between the deposition area and the inner area is defined as a first boundary line, a boundary between the inner area and the outer area is defined as a second boundary line when viewed in plan, and the first boundary line comprises a portion projecting toward the deposition area.
10 . The mask assembly of claim 9 , wherein the second boundary line comprises a portion projecting toward the deposition area to correspond to the projecting portion of the first boundary line.
11 . The mask assembly of claim 1 , further comprising a module area surrounded by the deposition area and provided with module openings formed therein, wherein the module openings have a shape different from a shape of the second openings.
12 . The mask assembly of claim 1 , further comprising a non-deposition area surrounded by the deposition area.
13 . The mask assembly of claim 1 , wherein the second mask has a thickness in at least a portion of the inner area smaller than a thickness of the second mask in the deposition area.
14 . The mask assembly of claim 1 , wherein the second mask comprises at least one of stainless steel, Invar, nickel, cobalt, nickel alloy, and nickel-cobalt alloy.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims from and the benefit of Korean Patent Application No. 10-2021-0137926, filed on Oct. 15, 2021, which is hereby incorporated by reference for all purposes as if fully set forth herein. BACKGROUND Field Embodiments of the invention relate generally to a mask assembly used for manufacturing display devices and more specifically, to a mask assembly with improved deposition precision and a deposition apparatus including the mask assembly. Discussion of the Background In general, a light emitting display device includes pixels and light emitting elements respectively disposed in the pixels. Each light emitting element includes a light emitting layer disposed between two electrodes. The light emitting layers included in the pixels are grouped in a plurality of groups. A mask assembly is used to deposit the light emitting layers on a work piece that will become a substrate of the light emitting display device. The mask assembly includes a frame, an open mask, and a mask provided in the unit of a cell. Patterned light emitting layers are formed by placing the work piece on the mask and depositing a light emitting material on the work piece. The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art. SUMMARY Mask assemblies and deposition apparatus for manufacturing display panels including the same constructed according to the principles and illustrative embodiments of the invention are capable of reducing deposition defects in, and dead spaces of, the display panel. For example, such a mask assembly includes a first mask having first openings and at least one second mask including a deposition area having second openings and an inner area surrounding the deposition area, the inner area overlapping boundary lines defining the first openings when viewed in plan. Thus, the deposition precision is improved, and a dead space of the display panel is reduced. The at least one second mask included in the mask assembly may further include an outer area surrounding the inner area with third openings, and thus adhesion between a substrate to be deposited and the mask is improved. Accordingly, the deposition precision is enhanced, and the display quality of the display panel is improved. Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts. According to an aspect of the invention, a mask assembly includes a first mask having a first opening and at least one second mask disposed on the first mask including a deposition area having second openings, an inner area surrounding the deposition area, and an outer area having third openings which surround the inner area, wherein a line defining the outer boundary of an inner surface which defines the first opening overlaps the inner area when viewed in plan. The inner area may have a closed-line shape when viewed in plan. The third openings may be covered by the first mask when viewed from a rear side of the first mask. The inner area may have a width between about 200 micrometers and about 500 micrometers when viewed in plan. Each of the second openings may have a size different from a size of each of the peripheral openings. A separation distance between the second openings adjacent to each other among the second openings may be different from a separation distance between the third openings adjacent to each other among the third openings. The second openings may have a shape different from a shape of the third openings. Each second mask may further include a welding area attached to the first mask and surrounding the outer area. A boundary between the deposition area and the inner area may be defined as a first boundary line, a boundary between the inner area and the outer area may be defined as a second boundary line when viewed in plan, and the first boundary line includes a portion projecting toward the deposition area. The second boundary line may include a portion projecting toward the deposition area to correspond to the projecting portion of the first boundary line. The mask assembly may further include a module area surrounded by the deposition area and provided with module openings formed therein, and the module openings have a shape different from a shape of the second openings. The mask assembly may further include a non-deposition area surrounded by the deposition area. The second mask may have a thickness in at least a portion of the inner area smaller than a thickness of the second mask in the deposition area. The second mask may include at least one of stainless steel, Invar, nickel, cobalt, nickel alloy, and nickel-cobalt alloy. According to another aspect of the invention, a deposition apparatus includes a ch