KR102076843B1 - Mask frame assembly for thin film evaporation - Google Patents

Abstract

The present invention relates to a mask frame assembly for thin film deposition capable of uniformly forming a thin film thickness, comprising: a mask including a plurality of mask pattern parts and a plurality of ribs separating the plurality of mask pattern parts; And a frame having an opening in the center and supporting the mask, wherein the mask pattern portion includes a plurality of shields, and a plurality of openings defined by the plurality of shields, and the plurality of shields each have an inclined surface. It is provided, and each inclined surface of the plurality of shielding parts has a different inclination angle.

Description

Mask frame assembly for thin film deposition {MASK FRAME ASSEMBLY FOR THIN FILM EVAPORATION}

The present invention relates to a mask frame assembly for thin film deposition, and more particularly, to a thin film deposition mask frame assembly capable of uniformly forming a thin film thickness during thin film deposition.

Recently, various flat panel display devices that can reduce weight and volume, which are disadvantages of a cathode ray tube, have been developed. Such flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and electroluminescence devices. have.

Among these flat panel display devices, the liquid crystal display device is the most widely used flat panel display device, but has a problem that the viewing angle is narrow and the response speed is low. The electroluminescent display device is classified into an inorganic light emitting diode display and an organic light emitting diode (OLED) display device according to the material of the light emitting layer, of which the OLED display has a wide viewing angle, excellent contrast and response Due to its high speed, it is drawing attention as a next-generation flat panel display.

The OLED display includes a first electrode and a light emitting layer disposed between the second electrode and the first and second electrodes, and the light emitting layer is patterned for each pixel. The light emitting layer may be formed of an inorganic material or an organic material, and the organic material may be a high molecular organic material or a low molecular organic material. As a method of forming such a light emitting layer, an ink jet method and a method using a fine metal mask (FMM) are known.

The inkjet spraying method can form a light-emitting layer in a selective region, and has little damage to a material, and thus has a large area, high definition, and high light-emitting efficiency. However, it is necessary to precisely control the amount of ink ejected from the nozzle, the speed, and the uniformity of the ejection angle, and it is necessary to develop an inkjet head that requires high-speed jetting and increase the number of heads for a large area at a low cost. In addition, the quality and thickness of the thin film must be uniformly formed in order to ensure uniform light emission within the pixel, but in the process of drying ink droplets, the peripheral part is thickened by the coffee stain effect, which makes the periphery of the thin film thicker. There is this.

In the FMM method, red, green, and blue pixels are formed by patterning organic materials that are red, green, and blue light-emitting materials using a fine metal mask (FMM). This method is widely used because it has excellent advantages in terms of device characteristics.

Hereinafter, a process of depositing the light emitting layer of the OLED using the FMM method will be described with reference to FIGS. 1 and 2. 1 is a conceptual diagram illustrating a process of forming an emission layer by depositing an organic material on a substrate in a rotary manner, and FIG. 2 is a conceptual diagram illustrating a process of forming an emission layer by depositing an organic material on a substrate in a scan type.

Referring to FIG. 1, a deposition source 30 capable of depositing an organic material in a vacuum chamber 10 is disposed, and a mask frame assembly 20 is disposed above the deposition source 30. The vacuum chamber 10 maintains a vacuum state so that foreign matter does not flow from the outside, and the inside is adjusted to a constant pressure.

The mask frame assembly 20 includes a pattern mask 21 having the same pattern as a thin film formed on a substrate 40 on which an organic material is to be deposited, and a frame 23 for supporting the pattern mask 21.

The substrate 40 on which the organic material is to be deposited is aligned with the pattern mask 21 on the mask frame assembly 20. After the substrate 40 is aligned on the mask frame assembly 20, the organic material sprayed from the deposition source 30 is deposited on the substrate 40 through the opening of the pattern 21 to form a light emitting layer of OLED.

The organic material is deposited to a uniform thickness to rotate the substrate 40 or reciprocate the deposition source 30 to form a light-emitting layer having a predetermined thickness. 1 is a view showing a rotating method of depositing an organic material by rotating the substrate 10 using one evaporation source 30, and FIG. 2 shows a substrate 10 using two evaporation sources 30. Is a diagram showing a scanning method of depositing an organic material on a substrate 10 by reciprocating two evaporation sources 30 while being fixed.

However, the rotating method of depositing the organic material on the substrate 10 by simply rotating the substrate 10 or the scanning method of depositing the organic material on the substrate 10 by reciprocating the evaporation source 30 is deposited during rotation and scanning. As the angle of incidence of the organic material evaporated from the evaporation port of the circle 30 is different from the central portion and the outer portion of the substrate 10, the deposition density of the thin film deposited on the substrate 10 becomes non-uniform. Particularly, since the deposition of the organic material is performed in a state in which a mask 21 having a predetermined pattern of openings or slots is in close contact with the substrate 10, a portion of the slot is covered by the incident angle at which the organic material enters the opening of the mask 21. The shadow effect occurs. Therefore, there is a problem that the non-uniformity of the thin film deposition density is intensified.

An object of the present invention is to provide a mask frame assembly for thin film deposition that can uniformly maintain the thickness of a thin film deposited during thin film deposition by solving the above-described problems.

In order to achieve the above object, a mask frame assembly for thin film deposition according to the present invention includes a mask including a plurality of mask pattern portions and a plurality of ribs separating the plurality of mask pattern portions; And a frame having an opening in the center and supporting the mask, wherein the mask pattern portion includes a plurality of shielding portions, and a plurality of openings defined by the plurality of shielding portions, and the plurality of shielding portions each have an inclined surface. It is provided, and each inclined surface of the plurality of shielding parts has a different inclination angle.

The mask is characterized in that it comprises a plurality of divided masks.

The inclined surfaces of the plurality of shielding portions of the mask pattern portion located in the center portion of the mask may be set such that the inclination angle thereof becomes smaller toward the outside from the center portion.

The inclined surfaces of the plurality of shielding portions of the mask pattern portion located on the left side from the center portion of the mask may be set such that the inclination angle becomes smaller toward the outside.

The inclined surfaces of the plurality of shielding portions of the mask pattern portion located on the right side from the center portion of the mask may be set such that the inclination angle becomes smaller toward the outside.

The central portion of the mask may be determined corresponding to the location of the evaporation source.

In the above configuration, the inclination angle formed by the one end of the opening formed by the adjacent shield and the extension line may be set larger than the inclination angle of the inclined surface of the shield defining the one end of the opening.

According to the mask frame assembly for thin film deposition according to the present invention, since the inclination angle of the shield of the mask pattern portion is formed in consideration of the geometric deposition angle of the evaporation source, not only the rigidity of the mask can be maintained, but also a uniform thin film thickness on the substrate. It is possible to obtain an effect that can form an organic material layer having a.

1 is a conceptual diagram illustrating a process of depositing an organic material on a substrate by rotation;
2 is a conceptual diagram illustrating a process of depositing an organic material on a substrate by a scan method,
Figure 3 is a perspective view showing a mask frame assembly for thin film deposition according to an embodiment of the present invention,
Figure 4 is a perspective view showing a mask frame assembly for thin film deposition according to another embodiment of the present invention,
5 is a cross-sectional view taken along the line I-I 'of the mask frame assembly for thin film deposition shown in FIGS. 3 and 4,
6 is a conceptual diagram for explaining that a central portion of a mask is determined according to a location of a deposition source.

Hereinafter, a mask frame assembly for thin film deposition according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, the same reference numerals denote the same components.

3 is a perspective view showing a mask frame assembly for thin film deposition according to an embodiment of the present invention.

Referring to FIG. 3, the mask frame assembly 100 for thin film deposition according to an embodiment of the present invention includes a mask 120 and a frame 110 supporting the mask.

The frame 110 is formed in a frame shape having an opening in the center to support the outer edge of the mask 120, and the two first support portions 110a formed to be balanced with each other in the first direction (x-axis direction in FIG. 3) And two second support parts 110b formed parallel to each other in a second direction perpendicular to the first direction (y-axis direction in FIG. 3).

The mask 120 is manufactured by processing the metal thin plate 121, and the plurality of mask pattern parts 130 and the plurality of mask pattern parts 130 having a shape corresponding to a pattern to be formed on the substrate are x-axis. And a plurality of ribs 125 separating in the y-axis direction.

Each mask pattern part 130 includes a plurality of openings (or slots) 130a and a shielding part 130b formed between the plurality of openings 130a. The plurality of openings 130a are formed to have the same pattern as the organic film to be deposited on the substrate, and are limited by the shield 130b.

4 is a perspective view showing a deposition mask according to another embodiment of the present invention.

Referring to FIG. 4, the mask frame assembly 200 for thin film deposition according to another embodiment of the present invention includes a plurality of split masks 220 and a frame 210 supporting the plurality of split masks 220. .

The frame 210 is formed in a frame shape having an opening in the center to support the ends of the plurality of split masks 220, and the two first support portions formed in equilibrium with each other in the first direction (x-axis direction in FIG. 4) ( 210a) and two second supports 210b formed in parallel to each other in the second direction (in the y-axis direction in FIG. 4).

Each split mask 220 is manufactured by processing a thin metal plate, and the plurality of mask pattern portions 230 and the plurality of mask pattern portions 230 having a shape corresponding to a pattern to be formed on the substrate are y-axis. It includes a plurality of ribs 225 to separate in the direction.

Each mask pattern part 230 includes a plurality of openings (or slots) 230a and a shielding part 230b formed between the plurality of openings 230a. The plurality of openings 230a is formed to have the same pattern as the organic film to be deposited on the substrate, and is limited by the shielding portion 230b.

When the mask is formed of a plurality of split masks 220 in a stripe shape as in the embodiment of FIG. 4, it is possible to prevent sagging due to its own weight or sagging due to thermal expansion. You can get the effect.

5 is a cross-sectional view of the mask pattern portion according to the embodiment of the present invention shown in FIGS. 3 and 4 taken along line I-I '.

Referring to FIG. 5, the mask pattern parts 130 and 230 include a plurality of openings (or slots) 130a and 230a and shields 130b and 230b formed between the plurality of openings 130a and 230a. do. In the present invention, the shielding portions 130b and 230b of the mask pattern portions 130 and 230 positioned at the central portion of the mask 120 or the central portion of the divided mask 220 are shielded portions toward the outside from the center portion, that is, to the left and right. It is formed so that the angle between the inclined surfaces 130b and 230b and the x-axis becomes small (for example, in FIG. 5, α <β <γ).

On the other hand, the shielding part 130b of the mask pattern part 130 located on the left side of the center part of the mask 120, or the shielding part of the mask pattern part 230 of the split mask 220 located on the left side of the centered split mask ( 230b) is formed such that the angle between the inclined surfaces of the shields 130b and 230b and the x-axis decreases toward the left. In addition, the shielding part 130b of the mask pattern part 130 located on the right side of the center part of the mask 120, or the shielding part of the mask pattern part 230 of the split mask located on the right side of the centered split mask 220 ( 230b) is formed such that the angle between the inclined surfaces of the shields 130b and 230b and the x-axis decreases toward the right.

In the above description, the central portion of the mask 120 and the central portion of the split mask 220 are determined according to the location of the deposition source.

6 is a conceptual diagram for explaining that the central portion of the mask is determined according to the location of the evaporation source 300.

Referring to FIG. 6, a substrate 140 for depositing an organic material is disposed on the masks 120 and 220, and a deposition source 300 for evaporating the organic material is spaced a predetermined distance from the mask. With respect to the evaporation source 300, the angle formed by the inclined surface and the x-axis of the shielding parts 130b and 230b of the mask pattern parts 130 and 230 disposed on the left side is formed to decrease toward the left, and the evaporation source 300 The angle through which the organic material from) passes through the openings 130a and 230a is also formed to become smaller toward the left or right (θa <θb <θc).

The angles α, β, γ formed by the inclined surfaces of the shields 130b and 230b and the x-axis, and the angle formed by the line connected to the openings 130a and 230a in the evaporation source 300 and the x-axis have the following relationship: do.

α <θa <β <θb <γ <θc

As described above, according to the mask frame assembly for thin film deposition according to an embodiment of the present invention, since the shielding portion of the mask pattern portion is formed in consideration of the geometric deposition angle of the evaporation source, the stiffness of the mask can be maintained as well as on the substrate. It is possible to obtain the effect of forming an organic layer having a uniform thin film thickness.

100, 200: mask frame assembly 110, 210: frame
120: mask 220: split mask
125, 225: ribs 130, 230: mask pattern portion
130a, 230a: opening 130b, 230b: shield

Claims (7)

A frame having an opening in the center; And
It includes a plurality of ribs separating the plurality of mask pattern portion and the plurality of mask pattern portion exposed through the opening, in contact with the frame, and includes a mask directly supported by the frame,
Each of the plurality of mask pattern portions includes a plurality of shielding portions and a plurality of openings defined by the plurality of shielding portions,
Each of the plurality of shields has an inclined surface, and the inclined surfaces of the plurality of shields have different inclination angles,
The mask frame assembly for thin film deposition, characterized in that the angle formed by the inclined surface and the x-axis of the shield portion of the mask pattern portion is always smaller than the angle formed by the line and the x-axis connected to the opening of the mask pattern portion in the evaporation source.
According to claim 1,
The mask frame assembly for thin film deposition, characterized in that it comprises a plurality of split masks.
According to claim 1,
The mask frame assembly for thin film deposition, characterized in that the inclined surfaces of the plurality of shielding portions of the mask pattern portion located at the center of the mask are set so that the inclination angle becomes smaller toward the outside from the center portion.
According to claim 1,
The mask frame assembly for thin film deposition, characterized in that the inclined surfaces of the plurality of shielding portions of the mask pattern portion located on the left side from the center portion of the mask are set so that the inclination angle becomes smaller toward the outside.
According to claim 1,
The mask frame assembly for thin film deposition, characterized in that the inclined surfaces of the plurality of shielding portions of the mask pattern portion located on the right side from the center portion of the mask are set so that the inclination angle becomes smaller toward the outside.
The method according to any one of claims 3 to 5,
The center portion of the mask is a mask frame assembly for thin film deposition, characterized in that is determined in correspondence with the position of the deposition source spaced a certain distance from the mask.


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