KR102661470B1 - Deposition mask and manufacturing method thereof - Google Patents

Abstract

One embodiment of the present invention includes forming a plating layer on the entire surface of the base layer, heat treating to increase the crystal grains of the plating layer, and irradiating a laser onto the plating layer to drill a pattern hole penetrating the base layer. A method for manufacturing a deposition mask is disclosed.

Description

Deposition mask and manufacturing method thereof}

The present invention relates to a deposition mask used in deposition operations and a method of manufacturing the same.

In general, an organic light emitting display device is capable of realizing color on the principle that holes and electrons injected from the anode and cathode recombine in the light emitting layer to emit light. It has a stacked structure in which a light emitting layer is inserted between the pixel electrode, which is the anode, and the counter electrode, which is the cathode. It is made up of pixels.

Each of the pixels can be a sub-pixel of, for example, a red pixel, a green pixel, or a blue pixel, and a desired color can be expressed by combining the colors of these three color sub-pixels. That is, each sub-pixel has a structure in which a light-emitting layer that emits light of any one of red, green, and blue is interposed between two electrodes, and the color of one unit pixel is expressed by an appropriate combination of these three colors of light.

Meanwhile, the electrodes and light emitting layer of the organic light emitting display device as described above may be formed through deposition. That is, a mask having pattern holes identical to the pattern of the thin film layer to be formed is aligned on a substrate, and thin film raw materials are deposited on the substrate through the pattern holes of the mask to form a thin film with a desired pattern.

The mask is often used in the form of a mask frame assembly with a frame supporting its ends, and the pattern hole can be formed through laser processing by irradiating a laser to the mask body to create a hole.

However, when drilling a pattern hole with the laser, a problem occurs frequently in which protrusions are formed around the pattern hole and the exact shape of the pattern hole is not obtained, so a method to suppress this problem is required. Normally, masks are made of a hard metal material that has been rolled, and it is known that these protrusions are formed in the early stages of drilling this hard metal material with a laser. However, if the mask is made of a material that is too soft, it is not only prone to sagging due to its own weight, but also prone to torsional deformation due to heat, which causes another problem.

Accordingly, embodiments of the present invention provide an improved deposition mask and method for manufacturing the same, which can reduce the risk of unprocessed holes due to protrusions during pattern hole processing with a laser, while preventing deformation due to self-weight or heat. .

An embodiment of the present invention includes a mask body including a base layer and a plating layer that covers the entire surface of the base layer, and the mask body includes a pattern portion having a plurality of pattern holes penetrating the plating layer and the base layer. , providing a deposition mask including a support portion outside the pattern portion.

The base layer may have a thickness of the pattern portion that is thinner than the thickness of the support portion.

The thickness of the pattern portion may be in the range of 10 to 15 μm, including the base layer and the plating layer.

The thickness of the support portion may be in the range of 20 to 50 μm, including the base layer and the plating layer.

Both the base layer and the plating layer may include INVAR material.

The plating layer may include an electro plating layer.

The base layer and the plating layer may have overlapping thermal expansion coefficients.

The base layer and the plating layer may both have a grain size in the range of 1 to 10㎛.

The support may be welded to the frame.

Additionally, an embodiment of the present invention includes forming a plating layer on one entire surface of the base layer; heat treating the plating layer to increase crystal grains; and irradiating a laser onto the plating layer to create a pattern hole penetrating the base layer.

A step forming step of forming a relatively thin pattern portion and a relatively thick support portion on one surface of the base layer may be further included, and the pattern hole may be formed in the pattern portion.

The step forming step may be performed by wet etching.

The thickness of the pattern portion may be in the range of 10 to 15 ㎛, including the base layer and the plating layer.

The thickness of the support portion may be in the range of 20 to 50 μm, including the base layer and the plating layer.

A correction step of reducing the thickness of the plating layer of the pattern portion may be further included.

The correction step may include one of a polishing process and a rolling process for the plating layer of the pattern portion.

Both the base layer and the plating layer may include INVAR material.

The plating layer forming step may be performed through an electro plating process.

After the heat treatment step, the base layer and the plating layer may have a range in which thermal expansion coefficients overlap with each other.

After the heat treatment step, the base layer and the plating layer may both have a grain size in the range of 1 to 10 μm.

Other aspects, features and advantages in addition to those described above will become apparent from the following drawings, claims and detailed description of the invention.

According to the deposition mask and its manufacturing method according to an embodiment of the present invention, pattern holes are formed with a laser through a plating layer with good processability, thereby significantly reducing the risk of unprocessed holes due to protrusions, and also improving the rigidity of the deposition mask. can be properly maintained, so concerns about deformation can be resolved. Therefore, it is possible to ensure stable quality of the product.

1 is a diagram showing a deposition process using a deposition mask manufactured according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a mask frame assembly including the deposition mask of FIG. 1.
Figure 3 is a cross-sectional view taken along line III-III in Figure 2.
FIGS. 4A to 4F are cross-sectional views sequentially showing the deposition mask manufacturing process according to an embodiment of the present invention (FIG. 4C is a plan view of FIG. 4B).
Figure 5 is a flowchart showing the deposition mask manufacturing process according to an embodiment of the present invention.
FIG. 6 is a cross-sectional view showing the detailed structure of the target substrate shown in FIG. 1.
Figure 7 is a flowchart showing a deposition mask manufacturing process according to another embodiment of the present invention.
Figure 8 is a flowchart showing a deposition mask manufacturing process according to another embodiment of the present invention.

Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. When describing with reference to the drawings, identical or corresponding components will be assigned the same reference numerals and redundant description thereof will be omitted. .

In the following examples, singular terms include plural terms unless the context clearly dictates otherwise.

In the following embodiments, terms such as include or have mean the presence of features or components described in the specification, and do not exclude in advance the possibility of adding one or more other features or components.

In the drawings, the sizes of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are shown arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is shown.

In cases where an embodiment can be implemented differently, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially at the same time, or may be performed in an order opposite to that in which they are described.

Figure 1 schematically shows the structure of a thin film deposition apparatus employing a deposition mask 120 according to an embodiment of the present invention.

As shown, the thin film deposition apparatus includes a deposition mask 120 for forming a desired pattern on a target substrate 300, and a deposition source that ejects deposition gas toward the target substrate 300 within a chamber 400. (200) etc. are provided.

Therefore, when the deposition source 200 ejects deposition gas within the chamber 400, the deposition gas passes through the pattern hole 121a (see FIG. 2) of the deposition mask 120 and adheres to the substrate 300, forming a predetermined amount. A patterned thin film is formed.

Here, the deposition mask 120 includes a frame 130 supporting both ends of the deposition mask 120, as shown in FIG. 2, and a long side stick supported on the frame 130 while crossing the deposition mask 120. It is used in the form of a mask frame assembly 100 including (110).

That is, the mask frame assembly 100 includes a frame 130, a plurality of long side sticks 110 whose both ends are fixed to the frame 130, and the long side sticks 110 that intersect perpendicularly to the frame 130. It is provided with a plurality of deposition masks 120 whose both ends are fixed.

The frame 130 forms the outer frame of the mask frame assembly 100 and has a square shape with an opening 132 at the center. Both ends of the long side stick 110 are fixed to a pair of opposing sides of the frame 130 by welding, and both ends of the deposition mask 100 are a pair perpendicular to the sides to which the long side stick 110 is welded. It is fixed to the side by welding.

The deposition mask 120 is an elongated stick-shaped member, and a plurality of pattern holes 121a are formed in the pattern portion 121 located within the opening 132, and both ends of the frame 300 are formed as described above. ) is welded to. Reference numeral 122 denotes a support portion, and when welding the deposition mask 120 to the frame 130, the support portion 122 is held and stretched in the longitudinal direction, and after welding, the portion protrudes out of the frame 300. Remove by cutting. This deposition mask 120 can be made as one large member, but in that case, sagging due to its own weight may become severe, so it is made by dividing it into multiple stick shapes as shown in the drawing. INVAR, an iron-nickel alloy, etc. may be used as a material for the deposition mask 120, the detailed structure of which will be described later.

The pattern hole 121a is a hole through which deposition vapor passes during the deposition process. The deposition vapor passing through the pattern hole 121a adheres to the target substrate 300 (see FIG. 1) and forms a thin film layer.

Here, the pattern portion 121 is not divided into cells of a certain standard but is long connected as one, and the long side stick 110 divides it into cells. That is, as shown in the drawing, the deposition mask 120 and the long side stick 110 are installed in close contact with each other while crossing perpendicularly to the frame 130. Accordingly, the pattern portion 121 of each deposition mask 120 is connected to the long side stick ( 110) passes across it and divides it into cells. So, the long side stick 110 draws the boundary between unit cells.

Meanwhile, the deposition mask 120 has a two-layer structure as shown in FIG. 3. That is, the main body is composed of a two-layer structure in which a plating layer 120b formed through an electro plating process covers a base layer 120a manufactured through a forging process such as rolling, and the plating layer 120b is a pattern portion ( It covers the entire surface of the base layer 120a, including 121) and the support portion 122. And, the pattern hole 121a of the pattern portion 121 is formed penetrating the plating layer 120b and the base layer 120a.

The reason why the deposition mask 120 has a two-layer structure of the base layer 120a and the plating layer 120b is that the pattern hole 120a can be smoothly opened by a laser and that deformation due to its own weight or heat does not occur easily. This is because all the necessary rigidity can be secured. In other words, the basic rigidity is mainly provided by the base layer 120a manufactured by rolling, and the processability by laser is mainly provided by the plating layer 120b formed by electroforming, so that both characteristics are combined. That is, when forming the pattern hole 121a with a laser, the laser is irradiated to the plating layer 120b, which has good processability, so that the perforation proceeds smoothly and maintains appropriate rigidity, thereby eliminating concerns about deformation.

In addition, the thickness D2 of the pattern portion 121 is formed to be thinner than the thickness D1 of the support portion 122, and the reason why the step is created between both sides is to reduce the generation of dust when forming the pattern hole 121a. . That is, if the thickness of the pattern part 121 is thick, the amount of dust scattered when drilling the pattern hole 121a increases accordingly, and the dust may prevent the laser from being irradiated to the correct location. Therefore, the thickness of the pattern part 121 is relative. It is reduced to generate a little dust.

In addition, although the base layer 120a and the plating layer 120b have differences in rigidity and processability, physical properties such as grain size and thermal expansion coefficient are almost similar. This is implemented by growing crystal grains of the plating layer 120b through high-temperature heat treatment after electroplating.

The detailed manufacturing process of the deposition mask 120, including such step formation, electroplating, and heat treatment, will be described later. Before that, an example of a target substrate 300 that can be deposited with the deposition mask 120 is shown in FIG. 6. It will be briefly introduced with reference to .

The deposition mask 120 can be used for various thin film deposition purposes, for example, to form a light emitting layer pattern of an organic light emitting display device.

FIG. 6 is a diagram illustrating the structure of the organic light emitting display device as an example of a target substrate 300 on which a thin film can be deposited using the deposition mask 120 of the present invention.

Referring to FIG. 6, a buffer layer 330 is formed on the base plate 320, and a thin film transistor (TFT) is provided on the buffer layer 330.

A thin film transistor (TFT) has an active layer 331, a gate insulating film 332 formed to cover the active layer 331, and a gate electrode 333 on the gate insulating film 332.

An interlayer insulating film 334 is formed to cover the gate electrode 333, and a source electrode 335a and a drain electrode 335b are formed on top of the interlayer insulating film 334.

The source electrode 335a and the drain electrode 335b are respectively in contact with the source region and drain region of the active layer 331 through contact holes formed in the gate insulating film 332 and the interlayer insulating film 334.

And, the pixel electrode 321 of the organic light emitting device (OLED) is connected to the drain electrode 335b. The pixel electrode 321 is formed on the planarization film 337, and a pixel defining layer (338) is formed on the pixel electrode 321 to partition the sub-pixel area. Reference numeral 339 denotes a spacer for maintaining the gap with the mask 100 during deposition to prevent damage to members on the substrate 300 side due to contact with the mask 100, and the spacer 339 is a part of the pixel defining film 338. may be formed in a protruding form. Then, a light-emitting layer 326 of an organic light-emitting device (OLED) is formed in the opening of the pixel definition film 338, and a counter electrode 327 is deposited on top of the organic light-emitting device (OLED). That is, the opening surrounded by the pixel defining film 338 becomes the area of one sub-pixel, such as the red pixel (R), green pixel (G), and blue pixel (B), and the light emitting layer 326 of the corresponding color is therein. It is formed.

Therefore, for example, if the deposition mask 120 is prepared so that the pattern holes 121 correspond to the light emitting layer 326, the light emitting layer 326 of a desired pattern can be formed through the deposition process as described in FIG. 1. Additionally, the above unit cell may correspond to the display area of one organic light emitting display device.

Now, the formation process of the deposition mask 120, which can make such an organic light emitting display device, will be described with reference to FIGS. 4A to 4D.

First, as shown in FIG. 4A, a hard base layer 120a manufactured by rolling is prepared and placed on the work table 10. The material of the base layer 120a is INVAR, a Fe-Ni alloy, the thermal expansion coefficient is -3.0 ~ -0.1ppm/℃, and the grain size is about 1~10㎛.

Next, wet etching is performed as shown in FIGS. 4B and 4C to make the pattern portion 121 thinner than the support portion 122. This process will be referred to as the step formation step. As described above, this is a process performed to reduce the amount of dust generated when forming the pattern hole 121a.

Next, a plating layer 120b is formed to cover the entire surface of the base layer 120a where the step is formed, as shown in FIG. 4D. This plating layer (120b) is also made of INVAR material and is formed by electroplating. That is, when the INVAR material is installed on the anode in the electrolyte solution and the base layer (120a) is installed so that one side is exposed to the cathode and then energized, the INVAR material adheres to one side of the base layer (120a) and the pattern portion 121 A plating layer 120b is formed that covers both the and the support portion 122. The plating layer 120b is formed to a thickness of about 5 to 10 ㎛, and after the two layers are formed, the thickness (D1) of the support part 122 is 20 to 50 ㎛, and the thickness (D2) of the pattern part 121 is 10 to 15 ㎛. It is about ㎛. In addition, the plating layer 120b formed at this time has a crystal grain size of several tens of nm and a thermal expansion coefficient of 5.0 to 7.0 ppm/℃, making it very sensitive to heat. Therefore, if the mask body with a two-layer structure formed of the base layer 120a and the plating layer 120b is used as is, the processability against laser irradiation is good, but the deformation due to heat is too easy, so severe damage is caused during welding work for assembly or actual deposition work. Deformation is easy to occur.

Therefore, to prevent this, the heat treatment step as shown in Figure 4e is subsequently performed. Heat treatment is performed by inserting the deposition mask 120 on which the base layer 120a and the plating layer 120b are formed into a heating furnace in a hydrogen and nitrogen gas atmosphere and heating it to about 550°C for about 1 hour. In this way, there is no significant difference in the crystal grains of the base layer (120a), but the crystal grains grow rapidly in the plating layer (120b) to almost the same level as the base layer (120a). That is, after heat treatment, the crystal grain size of both the base layer 120a and the plating layer 120b becomes about 1 to 10 μm. If the grain size becomes similar, the range of thermal expansion coefficient also becomes similar. The thermal expansion coefficient of the base layer (120a) is -3.0 to -0.1 ppm/℃, with little change even after heat treatment, but the plating layer (120b) is at the level of 5.0 to 7.0 ppm/℃ before heat treatment, and -1.0 to 1.0 ppm/℃ after heat treatment. It drops to ℃ level. That is, the thermal expansion coefficient ranges of the base layer 120a and the plating layer 120b are completely separate from each other before heat treatment, but after heat treatment, they become similar enough to have overlapping ranges. In this case, not only does the sensitivity of the plating layer 120b itself to heat decrease, but the difference with the base layer 120a also decreases, so that deformation does not occur easily even when high heat is applied during welding or deposition.

Thereafter, as shown in FIG. 4F, the laser irradiator 20 is operated to irradiate a laser in the 400 to 600 nm wavelength range through the plating layer 120b at the desired location to drill a pattern hole 121a. At this time, the plating layer 120b and the base layer 120a are removed together from the area irradiated with the laser, forming a pattern hole 121a, and the dust that was originally in the place of the pattern hole 121 and scattered when removed by the laser is removed. It is inhaled by an inhaler (not shown) and discharged to the outside. Since the thickness D2 of the pattern portion 121 was previously reduced, the amount of dust generated is relatively reduced, and thus the phenomenon of laser patterning being interrupted by dust rarely occurs. In addition, since the laser is irradiated to the plating layer 120b, which has good laser processability, to start drilling the pattern hole 121a, the formation of protrusions around the pattern hole 121a rarely occurs. In other words, if a pattern hole (121a) is drilled by irradiating a laser to the base layer (120a), which has relatively poor processability, a phenomenon in which jagged protrusions are formed along the perimeter of the pattern hole (121a) on the surface to which the laser is irradiated occurs. It happens frequently. This makes it difficult to form a precise pattern hole 121a. However, in this embodiment, the pattern hole 121a is started by irradiating the laser to the plating layer 120b, which has good laser processability, so the protrusions that were easily formed on the laser irradiation surface are rarely generated, and thus a precise pattern hole is formed. (121a) formation becomes possible.

When the deposition mask 120 formed in this way is welded and fixed to the frame 130 as shown in FIG. 2, the mask frame assembly 100 is completed. At this time, the base layer 120a of the support portion 122 is welded to the frame 130, and has already been heat treated to withstand deformation due to heat and its own weight, so the actual deposition process may be performed during this welding process or later after assembly is completed. The problem of deformation when used can be sufficiently suppressed.

FIG. 5 is a flowchart summarizing the manufacturing process of the deposition mask 120 described above.

Referring to FIG. 5, the manufacturing process is summarized again. First, a base layer 120a made of INVAR material manufactured by rolling is prepared (S1).

Then, a thickness difference, that is, a step, is formed between the pattern portion 121 and the support portion 122 through wet etching (S2).

Next, a plating layer 120b of the same INVAR material is formed on one side of the base layer 120a by electroplating (S3).

Next, the deposition mask 120 on which the base layer 120a and the plating layer 120b are formed is charged into a heating furnace and heat treated so that the grain size and thermal expansion coefficient range of the plating layer 120b are similar to those of the base layer 120a ( S4).

Then, a pattern hole 121a is formed in the pattern portion 121 with a laser (S5), and the deposition mask 120 formed up to the pattern hole 121a is welded to the frame 130 to assemble the mask frame assembly 100. Do it (S6).

Therefore, if the deposition mask 120 is manufactured in this way, the pattern hole 121a is formed with a laser through the plating layer 120b, which has good processability, and the risk of unprocessed holes due to protrusions can be greatly reduced. Additionally, the rigidity of the deposition mask 120 can be appropriately maintained, thereby eliminating concerns about deformation.

Meanwhile, FIGS. 7 and 8 illustrate possible variations in the above-described deposition mask 120 manufacturing method.

First, Figure 7 omits the step forming step (S2) in the above-described embodiment. In other words, the step formation is to reduce the amount of dust generated when drilling the pattern hole 121a with a laser, as described above. If the performance of the aspirator (not shown) that suctions and removes this dust can be sufficiently increased, this The step forming step (S2) may be omitted. Then, the manufacturing process can be simplified, and the pattern portion 121 and the support portion 122 have the same thickness.

Conversely, if the thickness of the pattern portion 121 is to be made thinner than the above-described embodiment, a thickness correction step (S4-1) of the pattern portion 121 may be added as shown in FIG. 8. That is, after heat treatment, the plating layer 120b of the pattern portion 121 is made thinner by wet polishing or rolling. This can be used when trying to further reduce dust generation by making the thickness of the plating layer 120b thinner, or when trying to more precisely match the thickness deviation between several deposition masks 120 within a certain standard.

In addition, in the above-described embodiment, the case of forming the pattern hole 121a in the deposition mask 120 divided into a plurality of stick-shaped pieces was exemplified, and the integrated mask covers the entire opening 132 of the frame 130 with one member. It can also be applied to manufacturing a mask in which pattern holes 121a are divided into cells in the deposition mask 120 itself without the long side stick 110. That is, of course, if the pattern hole 121a is formed by directly irradiating a laser, the manufacturing method of this embodiment can be applied regardless of the type of mask frame assembly.

Therefore, according to the deposition mask and manufacturing method described above, pattern holes are formed with a laser through a plating layer with good processability, thereby significantly reducing the risk of unprocessed holes due to protrusions, and also improving the rigidity of the deposition mask. Since it can be properly maintained, concerns about deformation can be resolved. Therefore, it is possible to ensure stable quality of the product.

As such, the present invention has been described with reference to an embodiment shown in the drawings, but this is merely an example, and those skilled in the art will understand that various modifications and variations of the embodiment are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the attached patent claims.

10: Workbench 20: Laser irradiator
100: Mask frame assembly 110: Long side stick
120: deposition mask 120a: base layer
120b: Plating layer 121: Pattern part
121a: pattern hole 122: support portion
130: frame

Claims (20)

A mask body comprising a base layer manufactured through a rolling process and a plating layer covering the entire surface of the base layer,
The mask body includes a pattern portion in which a plurality of pattern holes penetrating the plating layer and the base layer are formed, and a support portion outside the pattern portion,
The base layer is a deposition mask in which the thickness of the pattern portion is thinner than the thickness of the support portion.
delete According to claim 1,
A deposition mask in which the thickness of the pattern portion is in the range of 10 to 15 μm, including the base layer and the plating layer.
According to claim 1,
A deposition mask in which the thickness of the support portion is in the range of 20 to 50 μm, including the base layer and the plating layer.
According to claim 1,
A deposition mask in which both the base layer and the plating layer include INVAR material.
According to claim 1,
A deposition mask wherein the plating layer includes an electro plating layer.
According to claim 1,
A deposition mask in which the base layer and the plating layer have overlapping thermal expansion coefficients.
According to claim 1,
A deposition mask in which the base layer and the plating layer both have crystal grain sizes in the range of 1 to 10㎛.
According to claim 1,
A deposition mask wherein the support portion is welded to a frame.
Forming a plating layer on the entire surface of the base layer manufactured through a rolling process;
heat treating the plating layer to increase crystal grains; and
Irradiating a laser onto the plating layer to drill a pattern hole penetrating the plating layer and the base layer;
It further includes a step forming step of forming a pattern portion having different thicknesses on one surface of the base layer and a support portion outside the pattern portion,
The thickness of the pattern portion is thinner than the thickness of the support portion,
A method of manufacturing a deposition mask wherein the pattern hole is formed in the pattern portion.
delete According to claim 10,
A method of manufacturing a deposition mask in which the step forming step is performed by wet etching.
According to claim 10,
A method of manufacturing a deposition mask in which the thickness of the pattern portion, including the base layer and the plating layer, is in the range of 10 to 15㎛.
According to claim 10,
A method of manufacturing a deposition mask in which the thickness of the support portion, including the base layer and the plating layer, is in the range of 20 to 50㎛.
According to claim 10,
A method of manufacturing a deposition mask further comprising a correction step of reducing the thickness of the plating layer of the pattern portion.
According to claim 15,
The correction step is a method of manufacturing a deposition mask including one of a polishing process and a rolling process for the plating layer of the pattern portion.
According to claim 10,
A method of manufacturing a deposition mask wherein both the base layer and the plating layer include INVAR material.
According to claim 10,
A method of manufacturing a deposition mask in which the plating layer forming step is performed by an electro plating process.
According to claim 10,
A method of manufacturing a deposition mask in which the base layer and the plating layer have overlapping thermal expansion coefficients after the heat treatment step.
According to claim 10,
A method of manufacturing a deposition mask in which, after the heat treatment step, the base layer and the plating layer both have crystal grain sizes in the range of 1 to 10 μm.