KR20190008631A - Cleaning device and method for mask - Google Patents

Abstract

A cleaning device for a mask includes a process chamber, a mask-frame assembly, an electrode, and a high voltage power source. The process chamber includes an inlet port through which cleaning gas flows and an exhaust port connected with a vacuum pump. The mask-frame assembly includes a pattern mask as a cleaning target and a frame connected to the edge of the pattern mask, and is located inside the process chamber. The electrode faces the pattern mask inside the process chamber with a discharge space therebetween, and is surrounded by an insulator. The high voltage power source is connected to either the mask-frame assembly or the electrode to apply a driving voltage for plasma discharge. The other of the mask-frame assembly and the electrode is grounded. It is possible to prevent damage to the pattern mask during a cleaning process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cleaning apparatus,

The present invention relates to a mask cleaning technique, and more particularly, to a cleaning apparatus and a cleaning method of a pattern mask for producing a display.

Organic light emitting displays (OLEDs) are self-emitting displays that are thinner and easier to bend than liquid crystal displays (LCDs) that require backlights. A pixel of an organic light emitting display basically includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, and a driving circuit and an organic light emitting layer are disposed for each sub-pixel.

The organic light emitting layer may be formed by a chemical vapor deposition (CVD) process using a pattern mask. The pattern mask forms a plurality of openings corresponding to the organic light emitting layers of a specific color to be located on the substrate, and is located between the substrate and the evaporation source inside the evaporation chamber. The organic material of the specific color emitted from the evaporation source is deposited on the substrate through the opening of the pattern mask to form an organic light emitting layer.

The pattern mask used for forming the organic light emitting layer is washed and reused because the organic material is accumulated on one surface facing the evaporation source. The pattern mask cleaning process is generally a wet cleaning process in which a pattern mask is immersed in an acidic solution (nitric acid or hydrochloric acid) having a strong oxidizing power. However, the wet cleaning has a problem of generating a large amount of waste liquid that pollutes the environment, and the pattern mask may be damaged by the acidic solution.

An object of the present invention is to provide a mask cleaning apparatus and a mask cleaning method capable of cleaning a pattern mask without an acidic solution and without damaging a pattern mask in a cleaning process.

A mask cleaning apparatus according to an embodiment of the present invention includes a process chamber, a mask-frame assembly, an electrode, and a high voltage power source. The process chamber includes an inlet port through which the cleaning gas flows and an exhaust port connected with the vacuum pump. The mask-frame assembly includes a pattern mask to be cleaned and a frame connected to the edge of the pattern mask, and is located inside the process chamber. The electrode faces the pattern mask inside the process chamber with the discharge space therebetween, and is surrounded by the insulator. A high voltage power source is connected to either the mask-frame assembly or the electrode to apply a driving voltage for plasma discharge. The other of the mask-frame assembly and the electrode is grounded.

The mask-frame assembly may be disposed directly above the insulator, and a flange bent at the edge of the frame toward the insulator may be located. The discharge space may be surrounded by a pattern mask, a flange, and an insulator.

The mask-frame assembly may be grounded with the process chamber and a high voltage power supply may be connected to the electrode.

The mask cleaner may further include a diffusion plate and a support. The diffuser plate can be positioned between the top plate and the pattern mask of the process chamber and can diffuse the cleaning gas supplied to the inlet port to the entire surface of the pattern mask. The support may be connected to the edge of the diffuser plate and may be in close contact with the top plate and frame of the process chamber to energize the process chamber and the frame.

On the other hand, a high voltage power supply can be connected to the mask-frame assembly and the electrode can be grounded with the process chamber.

The insulator may be a second insulator, and the mask cleaner may further include a first insulator. The first insulator may surround the upper portion of the mask-frame assembly and the flange to insulate the process chamber and the mask-frame assembly.

The first insulator may include a horizontal portion and a vertical portion. The horizontal portion may be located between the top plate of the process chamber and the pattern-mask, and may include a cleaning gas channel that communicates the inlet port and the pattern mask. The vertical portion may be connected to the edge of the horizontal portion and may surround the flange.

The cleaning gas channel may include a first horizontal channel connected to the inlet port, a second horizontal channel facing the pattern mask, and a plurality of vertical channels connecting the first horizontal channel and the second horizontal channel.

The second insulator may include a lower insulator supporting the electrode, an upper insulator covering the electrode, and a pedestal positioned below the four corners of the lower insulator. The electrode may be energized with a lower plate of the process chamber by a connector located inside the pedestal.

A mask cleaning method according to an embodiment of the present invention includes the steps of: i) preparing a process chamber including an inlet port and an exhaust port and containing an electrode surrounded by an insulator, and a pattern mask and a pattern mask to be cleaned Frame; ii) exhausting the interior of the process chamber through the exhaust port and then supplying cleaning gas into the interior of the process chamber through the inlet port; and iii) And grounding one of the assembly and the electrode and connecting the other to a high voltage power source to generate a plasma in a discharge space between the pattern mask and the insulator.

The cleaning gas may contain pure oxygen or may comprise a mixed gas of oxygen and at least one of NF ₃ , CF ₄ and SF ₆ . The plasma can decompose the cleaning gas to generate oxygen radicals and fluorine radicals, and the organic matter in the pattern mask can be chemically reacted with oxygen radicals and fluorine radicals to be converted and removed into gaseous substances.

According to the mask cleaning apparatus and method of the embodiments, it is not necessary to provide a ground electrode or a high voltage electrode inside the process chamber, so that the device configuration can be simplified. In addition, since an expensive power source such as a high frequency power source and an impedance matching device is not used for plasma generation, the cost of the device can be reduced.

1 is a configuration diagram of a mask cleaning apparatus according to a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of the mask-frame assembly and the insulator in the mask cleaning apparatus shown in FIG. 1;
3 is a schematic view showing an operating state of the mask cleaning apparatus shown in Fig.
4 is a configuration diagram of a mask cleaning apparatus according to a second embodiment of the present invention.
5 is a schematic view showing an operating state of the mask cleaning apparatus shown in Fig.
6 is a flow chart showing a mask cleaning method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

FIG. 1 is a structural view of a mask cleaning apparatus according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of a mask-frame assembly and an insulator in the mask cleaning apparatus shown in FIG.

1 and 2, the mask cleaning apparatus 100 of the first embodiment includes a process chamber 10, a mask-frame assembly 20 located inside the process chamber 10, an insulator 30, Voltage electrode 40 and a high-voltage power supply 50 connected to the high-voltage electrode 40. The high- The mask-frame assembly 20 is grounded with the process chamber 10 and faces the insulator 30 with the discharge space 60 therebetween.

The process chamber 10 includes an inlet port P10 through which the cleaning gas flows and an exhaust port P20 connected with the vacuum pump. The process chamber 10 includes an upper plate 11 on which the inlet port P10 is located, a lower plate 12 on which the exhaust port P20 is located, a side wall 13 connecting the upper plate 11 and the lower plate 12, . ≪ / RTI > The process chamber 10 can be made of metal and can be grounded.

The cleaning gas may comprise pure oxygen or may comprise a mixed gas of oxygen and at least one of NF ₃ , CF ₄ , and SF ₆ . The inlet port P10 may be connected to a gas supply unit and a flow rate control unit (not shown), and may be provided at a distance from each other in the top plate 11 of the process chamber 10.

The mask-frame assembly 20 is composed of a pattern mask 21 to be cleaned and a frame 22 for supporting the pattern mask 21. The pattern mask 21 is a mask used in a deposition process for evaporating an organic substance to form a specific film. For example, the pattern mask 21 may be used to deposit an organic light emitting layer in the manufacturing process of the organic light emitting display (OLED).

The pattern mask 21 is made of a thin metal and forms a plurality of openings having the same pattern as the film to be deposited. The pattern mask 21 is located between the substrate and the evaporation source in a vaporization chamber (not shown), and organic matter is accumulated on one side of the pattern mask 21 facing the evaporation source in the evaporation process.

The frame 22 is made of a metal plate having a thickness larger than that of the pattern mask 21 as a support in the form of a hollow frame in the middle and has a stiffness higher than that of the pattern mask 21. [ The edge of the pattern mask 21 is fixed to the center of the frame 22 by welding or the like and the frame 22 may include a flange 23 bent perpendicularly along the edge.

The pattern mask 21 is used in a state of being fixed to the frame 22 because it is difficult to maintain the shape by itself due to its thin thickness. That is, after the mask-frame assembly 20 is mounted to the evaporation chamber and used for deposition, it is transferred from the evaporation chamber to the process chamber 10, and the pattern mask 21 is cleaned inside the process chamber 10.

The mask-frame assembly 20 may be located below the top plate 11 where the inlet port P10 is located. A diffusion plate 71 for uniformly diffusing the cleaning gas and a support 72 for supporting the diffusion plate 71 may be positioned between the upper plate 11 and the mask-frame assembly 20.

The diffuser plate 71 is a porous plate having a plurality of holes and may have an area equal to or larger than that of the pattern mask 21 and spaced apart from the pattern mask 21 by a predetermined distance. The cleaning gas introduced into the process chamber 10 through the inlet port P10 may be evenly diffused through the diffusion plate 71 and uniformly supplied to the entire surface of the pattern mask 21.

The support body 72 is made of a metal plate having a hollow frame shape like the frame 22 and the edge of the diffusion plate 71 can be fixed to the center of the support body 72 by welding or the like. Vertical portions 73 bent vertically toward the upper plate 11 may be positioned at the edges of the support body 72.

The support 72 is disposed directly above the frame 22 and contacts the frame 22 and the vertical portion 73 is in close contact with the top plate 11 of the process chamber 10. The distance between the diffuser plate 71 and the pattern mask 21 coincides with the thickness of the support body 72. The mask-frame assembly 20 is energized with the process chamber 10 through the support 72, which is a conductive layer, to remain grounded with the process chamber 10.

The insulator 30 is positioned between the mask-frame assembly 20 and the bottom plate 12 of the process chamber 10. The horizontal width of the insulator 30 may be greater than the horizontal width of the mask-frame assembly 20 where the mask-frame assembly 20 is disposed directly above the insulator 30 without a separate support, May serve as a support for the mask-frame assembly 20.

The high voltage electrode (40) is located inside the insulator (30). For example, the insulator 30 includes a lower insulator 31 for supporting the high voltage electrode 40, and a lower insulator 31 for covering the high voltage electrode 40 so that the high voltage electrode 40 is not exposed to the inner space of the process chamber 10. [ And an upper insulator 32.

The high voltage electrode 40 is a plate-like electrode having an area equal to or larger than that of the pattern mask 21, and is connected to the high voltage power source 50 to receive a drive voltage necessary for the plasma discharge therefrom.

The mask-frame assembly 20 is positioned such that the flange 23 located at the edge of the frame 22 faces the insulator 30. The pattern mask 21 faces the insulator 30 with the discharge space 60 surrounded by the flange 23 interposed therebetween and the width of the discharge space 60 along the vertical direction is equal to the height of the flange 23 . The surface of the pattern mask 21 facing the evaporation source and stacked with the organic material is positioned toward the discharge space 60.

The insulator 30 may be made of a dielectric material such as alumina (Al ₂ O ₃ ). The entire insulator 30 may be spaced apart from the side wall 13 of the process chamber 10 by a certain distance and the pedestal 33 may be positioned below the four corners of the lower insulator 31. [ The exhaust port P20 communicates with the inner space of the process chamber 10 through the space between the plurality of pedestals 33. [ At this time, in order to smoothly discharge the discharge space 60, at least one exhaust hole 24 passing through the flange 23 may be located on the flange 23 of the frame 22. [

In the mask cleaning apparatus 100 of the first embodiment described above, the pattern mask 21 serves as a ground electrode to be cleaned. 3 is a schematic view showing an operating state of the mask cleaning apparatus shown in Fig.

Referring to FIG. 3, the inside of the process chamber 10 is evacuated by the operation of a vacuum pump, and a purge gas is supplied into the process chamber 10 through the inlet port P10. At the same time, the high voltage electrode 40 receives the driving voltage Vs from the high voltage power source 50, and a plasma is generated in the discharge space.

The high voltage power supply 50 may be an AC power source having a driving frequency of 1 MHz or less (approximately several kHz to several hundred kHz). The operation voltage applied to the high voltage electrode 40 may be a form in which a positive value (1 / 2Vs) and a negative value (-1 / 2Vs) periodically change. For example, a square wave, a triangle wave, It can be implemented with any one of the waveforms.

When the drive voltage Vs described above is applied to the high voltage electrode 40, a plasma discharge is induced in the discharge space by the voltage difference between the grounded pattern mask 21 and the high voltage electrode 40. The discharge occurs when the operation voltage is higher than the breakdown voltage of the internal gas. Since the insulator 30 is a dielectric, the discharge current continuously increases with time. As the amount of wall charge accumulates on the surface, the discharge current decreases.

That is, as the discharge current increases after the discharge starts, the space charges inside the plasma accumulate on the surface of the insulator 30 to generate wall charges, and the discharge is weakened with time due to the wall voltage of the insulator 30. The plasma discharge repeats generation, maintenance, and extinction processes while the applied voltage is maintained. Therefore, the discharge does not transfer to the arc but remains in the glow region and maintains a stable discharge.

The plasma generated in the discharge space decomposes the cleaning gas to generate radicals, and the radicals generated from the plasma chemically react with the organic substances accumulated in the pattern mask 21 to remove the organic substances.

Specifically, when the cleaning gas contains pure oxygen, oxygen radicals are generated from the plasma, and when the cleaning gas includes at least one of NF ₃ , CF ₄ , and SF _{6 together with} oxygen, oxygen radicals and fluorine Radicals are generated.

The components of the polymer organic material accumulated in the pattern mask 21 are mainly carbon (C) and hydrogen (H). The carbon atoms of the organics react with oxygen radicals to convert to carbon monoxide or carbon dioxide (C + O → CO or CO ₂ ). The hydrogen atom of the organic material reacts with the oxygen radical to convert it to water vapor (2H + O → H ₂ O) or reacts with the fluorine radical to convert it to hydrogen fluoride (H + F → HF).

As described above, the polymer organic material accumulated in the pattern mask 21 is converted into and removed from the gaseous material by the cleaning gas and the plasma discharge. The above-described mask cleaning method is an environmentally-friendly dry cleaning method that does not use an acidic solution.

According to the mask cleaning apparatus and method of the first embodiment, it is not necessary to provide a ground electrode inside the process chamber 10, so that the device configuration can be simplified. In addition, since an expensive power source such as a high frequency power source and an impedance matching device is not used for plasma generation, the cost of the device can be reduced.

4 is a configuration diagram of a mask cleaning apparatus according to a second embodiment of the present invention.

4, the mask cleaning apparatus 200 of the second embodiment includes a process chamber 10, a first insulator 80 located inside the process chamber 10, a mask-frame assembly 20, 2 insulator 90 and a ground electrode 45 and a high voltage power supply 50 connected to the mask-frame assembly 20. The ground electrode (45) is grounded with the process chamber (10).

The structure of the process chamber 10 and the mask-frame assembly 20 are the same as those of the first embodiment described above, so duplicate descriptions are omitted.

The first insulator 80 surrounds the upper side of the mask-frame assembly 20 and the edge of the mask-frame assembly 20 and insulates the process chamber 10 and the mask-frame assembly 20. The first insulator 80 includes a horizontal portion 81 located between the top plate 11 of the process chamber 10 and the mask-frame assembly 20 along a vertical direction and a flange 81 of the mask- 23, which are not shown.

The horizontal portion 81 can be in close contact with the top plate 11 of the process chamber 10 and the vertical portion 82 is spaced a certain distance from the side wall 13 of the process chamber 10 along the horizontal direction. The horizontal portion 81 includes a cleaning gas channel 83 that communicates the patterned mask 21 with the inlet port P10 and supplies the cleaning gas to the pattern mask 21. [

The cleaning gas channel 83 includes a first horizontal channel 831 communicating with the plurality of inlet ports P10, a second horizontal channel 832 facing the pattern mask 21, a first horizontal channel 831, And a plurality of vertical channels 833 connecting the second horizontal channels 832. The cleaning gas channel 83 is not limited to the above-described example, and can be variously modified.

The second insulator 90 is located between the mask-frame assembly 20 and the bottom plate 12 of the process chamber 10. The horizontal width of the second insulator 90 may be equal to or greater than the horizontal width of the first insulator 80 and the mask-frame assembly 20 and the first insulator 80 may be formed directly above the second insulator 90 So that the second insulator 90 can function as a support for the mask-frame assembly 20.

The ground electrode (45) is located inside the second insulator (90). The second insulator 90 includes a lower insulator 91 for supporting the ground electrode 45 and a lower insulator 91 for covering the ground electrode 45 so that the ground electrode 45 is not exposed to the inner space of the process chamber 10. [ (92). The ground electrode 45 is a planar electrode having an area equal to or greater than the pattern mask 21 and is energized with the process chamber 10 through the connector 46 and grounded together with the process chamber 10.

The pattern mask 21 faces the second insulator 90 with the discharge space 60 surrounded by the flange 23 therebetween. The second insulator 90 is made of a dielectric material such as alumina and the entirety of the second insulator 90 is spaced apart from the side wall 13 of the process chamber 10 by a certain distance. A pedestal 93 may be positioned below the four corners of the lower insulator 91 and the exhaust port P20 communicates with the interior space of the process chamber 10 through a space between the plurality of pedestals 93.

The connector 46 of the ground electrode 45 may be located within the pedestal 93 and may be in contact with the process chamber 10 in contact with the bottom plate 12 of the process chamber 10. At this time, in the vertical portion 82 of the first insulator 80 surrounding the flange 23 of the frame 22 and the flange 23, at least one exhaust hole (not shown) (24) can be located.

In the mask cleaning apparatus 200 of the second embodiment described above, the pattern mask 21 functions as a high-voltage electrode while being cleaned. 5 is a schematic view showing an operating state of the mask cleaning apparatus shown in Fig.

Referring to FIG. 5, the inside of the process chamber 10 is evacuated by the operation of a vacuum pump, and a purge gas is supplied into the process chamber 10 through the inlet port P10. At the same time, the mask-frame assembly 20 receives the driving voltage from the high-voltage power source 50, and a plasma is generated in the discharge space.

The plasma decomposes the cleaning gas to generate radicals, and the radicals generated from the plasma chemically react with the organic substances accumulated in the pattern mask 21 to remove the organic substances. The mask cleaning method of the second embodiment is the same as the mask cleaning method of the first embodiment described above, except that a driving voltage is applied to the mask-frame assembly 20.

6 is a flow chart showing a mask cleaning method according to an embodiment of the present invention.

Referring to FIG. 6, a mask cleaning method includes a first step (S10) of placing a mask-frame assembly inside a process chamber, a second step of supplying a cleaning gas into the process chamber after exhausting the inside of the process chamber S20), and a third step (S30) of generating a plasma discharge in the discharge space adjacent to the pattern mask.

In the first step (S10), an insulator surrounding the electrodes is disposed in the process chamber, and the pattern mask faces the insulator with the discharge space interposed therebetween. In the second step S20, the cleaning gas may include pure oxygen, or may include a mixed gas in which oxygen is mixed with at least one of NF ₃ , CF ₄ , and SF ₆ .

In the third step S30, either one of the mask-frame assembly and the electrode is connected to the high-voltage power source to receive the driving voltage, and the other is grounded. Therefore, a plasma is generated in the discharge space by the voltage difference between the mask-frame assembly and the electrode, and organic matter in the pattern mask is removed by plasma ashing.

In the method of the first embodiment, the electrode is a high voltage electrode and the mask-frame assembly is grounded. In the method of the second embodiment, the electrode is a ground electrode and the mask-frame assembly receives a drive voltage from a high voltage power supply.

In the above-described mask cleaning method, the mask-frame assembly functions as a high-voltage electrode or a ground electrode while being cleaned. Therefore, it is not necessary to provide a ground electrode or a high voltage electrode in the process chamber, so that the device configuration can be simplified, and the cost of the device can be reduced because expensive power sources such as a high frequency power source and an impedance matching device are not used.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

100, 200: Mask cleaning device
10: process chamber 20: mask-frame assembly
21: pattern mask 22: frame
23: flange 30: insulator
40: high voltage electrode 50: high voltage power source
60: discharge space 71: diffusion plate
72: support 80: first insulator
90: second insulator 45: ground electrode

Claims (12)

A process chamber including an inlet port through which the cleaning gas flows and an exhaust port connected with the vacuum pump;
A mask-frame assembly disposed within the process chamber, the mask-frame assembly including a pattern mask to be cleaned and a frame coupled to an edge of the pattern mask;
An electrode facing the pattern mask with a discharge space interposed in the process chamber, the electrode being surrounded by an insulator; And
And a high-voltage power source connected to either one of the mask-frame assembly and the electrode for applying a driving voltage for plasma discharge,
Wherein the mask-frame assembly and the other of the electrodes are grounded. The method according to claim 1,
The mask-frame assembly being disposed directly over the insulator,
A flange bent toward the insulator is positioned at an edge of the frame,
Wherein the discharge space is surrounded by the pattern mask, the flange, and the insulator. 3. The method of claim 2,
The mask-frame assembly is grounded with the process chamber,
And the high-voltage power supply is connected to the electrode. The method of claim 3,
A diffusion plate positioned between the upper plate of the process chamber and the pattern mask and diffusing the cleaning gas supplied to the inlet port to the entire surface of the pattern mask; And
A support plate connected to an edge of the diffuser plate and closely contacted with the upper plate and the frame of the process chamber to energize the process chamber and the frame,
Further comprising: 3. The method of claim 2,
The high voltage power supply is connected to the mask-frame assembly,
Wherein the electrode is grounded with the process chamber. 6. The method of claim 5,
Wherein the insulator is a second insulator,
Further comprising a first insulator surrounding the upper portion of the mask-frame assembly and the flange, the first insulator insulating the process chamber and the mask-frame assembly. The method according to claim 6,
Wherein the first insulator comprises:
A horizontal portion positioned between the top plate of the process chamber and the pattern-mask, the cleaning gas channel communicating the inlet port and the pattern mask; And
A vertical portion connected to an edge of the horizontal portion and surrounding the flange,
. The method according to claim 6,
Wherein the cleaning gas channel comprises a first horizontal channel connected to the inlet port, a second horizontal channel facing the pattern mask, and a plurality of vertical channels connecting the first horizontal channel and the second horizontal channel, Mask cleaning device. The method according to claim 6,
Wherein the second insulator includes a lower insulator for supporting the electrode, an upper insulator for covering the electrode, and a pedestal below the four corners of the lower insulator,
Wherein said electrode is energized with a lower plate of said process chamber by a connector located within said pedestal. Providing a process chamber including an inlet port and an exhaust port and containing an electrode surrounded by an insulator, disposing a mask-frame assembly comprising a pattern mask to be cleaned and a frame for supporting a pattern mask inside the process chamber;
Exhausting the interior of the process chamber through the exhaust port and supplying a purge gas into the process chamber through the inlet port; And
Generating a plasma in a discharge space between the pattern mask and the insulator by grounding one of the mask-frame assembly and the electrode and connecting a high-voltage power source to the other,
. 11. The method of claim 10,
Wherein the cleaning gas comprises pure oxygen or a mixed gas in which oxygen is mixed with at least one of NF ₃ , CF ₄ , and SF ₆ . 12. The method of claim 11,
The plasma decomposes the cleaning gas to generate oxygen radicals and fluorine radicals,
Wherein the organic material of the pattern mask is chemically reacted with the oxygen radical and the fluorine radical to be converted into a gaseous substance and removed.

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