KR100267965B1 - How to make shadow mask - Google Patents

Abstract

PURPOSE: A manufacturing method of a shadow mask is provided to be capable of enhancing resolution by forming accurate shadow mask patterns through etching of a Si-substrate. CONSTITUTION: In manufacturing method of the shadow mask for pixelation of an EL(Electroluminescence) device including a plurality of pixels consisting a first electrode, an organic EL layer and a second electrode, a plurality of etch stop layers are first formed on both sides of a Si-substrate(110) with constant gaps. Then, the Si-substrate is dipped into etchant liquid and then is heated by a predetermined to be etched. In addition, the Si-substrate may be etched. Further, the etch stop layers are formed by patterning through a photolithography process after coating silicon nitride with a predetermined thickness using CVD or sputtering.

Description

How to make shadow mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electroluminescence (EL) devices, and more particularly to a method for manufacturing a shadow mask.

Recently, as the size of the display device increases, the demand for a flat display device having less space occupancy is increasing. As one of the flat display devices, an electroluminescent device is attracting attention.

The electroluminescent device is divided into inorganic EL device and organic EL device according to the material used. When the organic EL device is injected with an electric thin film layer formed between the electron injection electrode (cathode) and the hole injection electrode (anode), It is a device that emits light after disappearing after paired with electrons and holes, and has the advantage of being able to drive at a lower voltage (for example, 10V or less) than plasma display panel (PDP) or inorganic EL display. have.

In addition, the organic EL device has excellent characteristics such as wide viewing angle, high speed response and high contrast, and thus can be used as a pixel of a graphic display, a pixel of a television image display or a surface light source. They are thin, light, and have good color, making them suitable for next-generation flat panel displays. In addition, the device may be formed on a flexible transparent substrate such as plastic.

1 illustrates a structure of a simple matrix organic EL device having such a purpose, and includes a first electrode 12 and a first electrode 12 formed in a stripe shape on a transparent substrate 11. And an organic thin film layer 13 formed on the second thin film layer 13 and a second electrode 14 formed in a stripe shape on the organic thin film layer 13.

The organic thin film layer 13 may include a hole injecting layer (HIL) or a hole transporting layer (HTL) formed on the first electrode 12, and an organic light emitting layer formed on the hole injecting layer or the hole transporting layer. And an electron injecting layer (EIL) or an electron transporting layer (ETL) formed on the organic light emitting layer.

In this case, the hole injection layer and the hole transport layer may be continuously formed on the first electrode 12, and the electron transport layer and the electron injection layer may be continuously formed on the organic emission layer.

The second electrode 14 of the organic EL device formed as described above functions to inject electrons into the organic light emitting layer through the electron injection layer or the electron transport layer of the organic thin film layer 13, and the first electrode 12 is the hole injection layer. Alternatively, the hole may be injected into the organic light emitting layer through the hole transport layer.

These holes and electrons emit light as the electron-hole pairs in the organic emission layer and then disappears.

However, such an organic EL device has many difficulties in manufacturing, and the most difficult process among them has been a pixelation or patterning process.

That is, indium tin oxide (ITO), which is commonly used as the first electrode 12 band, may be easily patterned using a photolithography process which is generally used in a semiconductor manufacturing process. However, the patterning of the second electrode is not so simple. When the organic thin film layer 13 already formed under the second electrode 14 is exposed to water or a solvent during the photolithography process, its properties rapidly deteriorate, making it difficult to use a general photolithography process.

FIG. 2 is a cross-sectional view of one of the conventional organic EL devices to solve this problem, and a pattern is formed using a shadow mask.

However, the above-described method is possible in the case of manufacturing a monochromatic organic EL element, but other techniques are further required in order to produce a multicolor or full color organic EL element. One of them is shown in FIG.

Referring to the patterning process using the shadow mask illustrated in FIGS. 3A to 3C, first, the partition 36 is formed on the first electrode strip 32 formed on the transparent substrate 31, and then the organic thin film layer 33 is commonly used. The necessary buffer layer, hole transport layer, etc. are formed.

Next, shadow masks 35 respectively prepared for red, blue, and green colors are sequentially used to form organic light emitting layers emitting respective colors.

For example, during the formation of the green light emitting layer, red and blue strips are covered by the shadow mask 35 to prevent the green light emitting material from being applied to the portion. In some cases, after forming the light emitting layer, an electron transport layer may be separately coated thereon.

Then, a common material, that is, an electron injection layer, a second electrode 34, and the like are sequentially formed, and finally, a protective film is formed.

3A to 3C perform pixelation using side walls and shadow masks at the same time.

Figure 4 shows a part of the shadow mask used at this time, in order to simplify the driving, it is preferable to combine the three red, green, and blue pixels to form a square. That is, when the width of the second electrode is 'a', the spacing between the electrodes is 'b', and the width of the first electrode is 'a', the relationship as shown in Equation 1 below is To be established.

C = (3) + (2)

If the resolution is quarter VGA, the number of pixels is 320 × 240.

In this case, it is assumed that the diagonal length of the display is 5 inches.

3 inches = 240 × 3 (A + B)-(2 × B)

Namely, (ga + b) to 100 µm.

This (ga + b) approximately matches the width of the open (open) part of the shadow mask.

At this time, if the length of the diagonal of the display is reduced from 5 inches to 3 inches, (ga + na) is reduced to about 60 μm. Therefore, in order to produce a 3 to 5 inch display in which a full color organic EL display is expected to be applied primarily, it is necessary to be able to fit the minimum dimension of 'ga + b' to about 60 mu m. In addition, in order to align the shadow mask and the transparent substrate correctly, an alignment key must be created on the shadow mask, and the alignment key tolerance must be smaller than 'I'. For example, the tolerance should be 10 μm or less.

However, most of the shadow masks are made by corrosion of a suitable metal alloy by chemical etching, and in this case, it is difficult to meet the above-mentioned (ga + na) to 60 µm and the alignment error to 10 µm or less.

The present invention is to solve the above problems, an object of the present invention is to provide a shadow mask manufacturing method for increasing the resolution by etching the silicon substrate to create a sophisticated shadow mask pattern.

1 is a plan view of a monochromatic organic EL device according to a simple matrix method of the prior art

2 is a structural cross-sectional view of a monochrome organic EL device according to the prior art;

3 is an exemplary view showing a manufacturing process of a multicolor organic EL device according to the prior art;

4 is a plan view of a portion of the shadow mask of FIG.

5 is a view showing an etching state of the silicon (110) substrate in the shadow mask manufacturing method according to the present invention

FIG. 6 is a diagram illustrating an example of a shadow mask manufactured in FIG. 5. FIG.

FIG. 7 is a view illustrating an example in which the shadow mask manufactured in FIG. 5 is bonded onto a support substrate. FIG.

8 is a view showing an etching state of the silicon (100) substrate in the shadow mask manufacturing method according to the present invention

9 is a diagram illustrating a problem of the shadow mask fabricated in FIG. 8;

The shadow mask manufacturing method according to the present invention for achieving the above object, the first step of forming an etch stop layer on both sides of the silicon substrate at a predetermined interval, a predetermined temperature after immersing the silicon substrate in an etchant (etchent) solution It is characterized by consisting of a second step of heating to.

The silicon substrate is characterized in that the (110) surface is etched.

The shadow mask structure using such a silicon substrate can increase the resolution of the organic EL device.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 is a structural cross-sectional view of a shadow mask according to the present invention, in which a silicon mask is etched to form a shadow mask.

Therefore, referring to the shadow mask manufacturing process using the silicon (110) substrate, first, the silicon substrate is polished to an appropriate thickness. Although thinner is better, it is appropriate to set it to 100-500 micrometers in consideration of the possibility of breaking at the time of handling. Next, both surfaces of the silicon wafer are properly polished and then cleaned.

In order to precisely control the end point of etching, an etch stop layer is formed on the 'a' surface of the substrate. The forming method is one of the methods listed below, and the first method is a process. There are many advantages.

That is, one is coated with silicon nitride (Si ₃ N ₄ ) about 100 to 5000 nm by chemical vapor deposition (CVD) or sputtering, and then patterned by using a photolithography process. The other method is a method of forming a p-doped layer by injecting boron (B) or the like above a critical concentration. At this time, a window is formed by a photolithography process to allow selective boron doping, and then an appropriate amount of boron is injected. To do this, use a diffusion furnace or ion implanter.

Then, the substrate is inverted and the silicon nitride is coated on the opposite 'b' surface by about 100 to 5000 nm in this manner, and then the silicon nitride is patterned by using a double side mask aligner.

Subsequently, the silicon substrate is immersed in one of a solution such as ethylenediamine-pyrocatechol (EDP), hydrazine, KOH and isopropyl alcohol mixed solution, and then heated to an appropriate temperature (eg, 75 to 85 ° C.) to be etched.

FIG. 5 shows that the silicon substrate is etched perpendicularly to the substrate surface when the single crystal silicon 110 substrate is etched by immersing the silicon substrate in one of EDP, hydrazine and KOH mixed solutions. This etched surface is very smooth and has the advantage of very fine dimension control.

In this case, the etching may be started at one side or at the same time on both sides.

Figure 6 shows the shadow mask thus made, where 'A' is longer than 'B' may facilitate the formation of a stripe pattern by deposition. To this end, an etch stop layer may be formed on one side, and then the substrate may be inverted, and the silicon nitride layer may be patterned on the opposite side to pattern 'C' shorter than 'D'.

The shadow mask thus manufactured may be used by itself, or may be used to increase mechanical strength by bonding it onto a 'support substrate' made of a properly patterned metal or alloy, as shown in FIG.

Meanwhile, FIG. 8 shows that the silicon 100 substrate is etched at an inclination of 54.74 degrees when the substrate is immersed in one of ethylenediamine-pyrocatechol (EDP), hydrazine, KOH and isopropyl alcohol mixed solution. This is because the etching rate along the (100) plane is 100 times faster than that of the (111) plane. FIG. 9 illustrates a shadow mask etched after forming an etch stop layer using a boron doping method, and has the following problems by anisotropic etching.

For example, assuming that the thickness c of the silicon substrate is 500 μm, d (d = c / (tan 54.74)) is about 350 μm, and b (b = 2 × d + α) should be at least 700 μm. and a (a = b / 2) is 350 micrometers or more. However, as described above, the goal is to reduce a to 60 [mu] m, so there is a problem in using the silicon (100) substrate. If the thickness of the silicon substrate is reduced, a can be reduced. However, if the thickness is too low, the substrate becomes weak and difficult to handle.

Therefore, the solution of this problem is the method of FIG. 5 described above. When the single crystal silicon 110 surface is etched, it is etched perpendicularly to the substrate surface, so that d in FIG. 9 can be made 0 so that the above problem is eliminated. .

As described above, according to the shadow mask manufacturing method according to the present invention, an etch stop layer is formed on one surface of the silicon 110 substrate, and silicon nitride is coated on the opposite surface thereof, and then the silicon substrate is mixed with EDP, hydrazine, and KOH. By immersing in one of the solutions and etched perpendicular to the substrate surface, it is possible to produce a sophisticated shadow mask required for producing a high resolution display and to increase the productivity by precisely aligning the mask and the panel substrate. .

In addition, when the organic EL device is fabricated using the shadow mask thus produced, accurate pixelation is possible.

Claims (10)

In the shadow mask manufacturing method for the pixelation of the electroluminescent device comprising a plurality of pixels consisting of a first electrode, an organic electroluminescent layer, a second electrode, A first step of forming etch stop layers on both sides of the silicon substrate at predetermined intervals; And immersing the silicon substrate in an etching solution and then heating the substrate to a predetermined temperature to etch it. 2. The method of claim 1, wherein said silicon (110) substrate is etched. The method of claim 1, wherein the etch stop layer of the first step A method of manufacturing a shadow mask, characterized in that the silicon nitride is coated to a predetermined thickness by a method such as vapor deposition (CVD) or sputtering and then patterned by a photolithography process. 4. The method of claim 3, wherein the silicon nitride has a thickness of 100 to 5000 nm. The method of claim 1, wherein the etch stop layer of the first step Method of producing a shadow mask, characterized in that by injecting boron (B) above a critical concentration to form a p-doped layer. The method of claim 1, wherein the double-sided etch stop layer of the first step A method of making a shadow mask, characterized by using a double-sided mask aligner for mutual alignment. The method of claim 1, wherein the etching solution of the second step Method of producing a shadow mask, characterized in that any one of EDP, hydrazine, KOH and isopropyl alcohol mixed solution. The method of claim 1, wherein the spacing between the etch stop layers is Shadow mask manufacturing method characterized in that the adjustable. The method of claim 1, wherein the shadow mask formed in the second step is Shadow mask manufacturing method, characterized in that can be used by bonding on a supporting substrate. The method of claim 9, wherein the support substrate A method of making a shadow mask, characterized in that it is made of a patterned metal or alloy.