KR20190079198A - Apparatus for processing mask and method of processing mask using the same - Google Patents

Abstract

The present invention relates to a mask processing apparatus, which checks whether foreign substances are attached to the mask before and after using the mask, and removes the foreign substances attached to the mask according to an inspection result. The mask processing apparatus comprises: a mask support unit for supporting a mask; an inspection unit for photographing a surface of the mask to check whether the foreign substances is attached to the mask; and a repair unit for removing the foreign substances attached to the mask according to the inspection result of the mask. Both an inspection process and a repair process of the mask in a single device are processed, thereby improving production efficiency and improving the reliability of the process using the processed mask.

Description

[0001] The present invention relates to a mask processing apparatus and a mask processing method using the same,

The present invention relates to a mask processing apparatus and a mask processing method using the mask processing apparatus. More particularly, the present invention relates to a mask processing apparatus for inspecting a mask used for forming a predetermined pattern on a substrate, And a mask processing method using the same.

The pattern forming process includes a photolithography process, and the photolithography process includes a series of processes such as a cleaning process, a surface treatment process, a photoresist film forming process, an alignment / exposure process, a development process, and an inspection process.

On the other hand, in order to form an accurate pattern in the pattern formation process, it is essential to use a mask corresponding to the pattern plate. During the patterning process, the mask is left with foreign materials (particles, organic matter, photoresist residues, etc.) for various reasons.

Particularly, since the devices and the wirings constituting the semiconductor and flat panel displays are extremely minute, if a pattern is formed in a state that a foreign substance is present on the mask, the formation of a normal device or wiring is hindered, , It is important that the foreign substance does not adhere to the mask.

Therefore, there is a need for a technique for inspecting whether or not the mask is adhered to foreign matter before and after use of the mask, and for removing the foreign matter detected according to the result of the inspection.

Korean Patent Publication No. 2017-0023327 (published on Mar. 03, 03, 2017)

An object of the present invention is to provide a mask processing apparatus which inspects whether or not a mask adheres to foreign matter before and after use of a mask, and removes foreign objects detected according to the inspection result, and a mask processing method using the same.

A mask processing apparatus according to the present invention includes a mask supporting unit for supporting a mask, an inspection unit for inspecting a surface of the mask to check whether the mask is adhered to foreign matter, and a foreign matter removing unit for removing the foreign matter adhered to the mask, Repair unit.

The mask support may include a first transfer unit for transferring the mask to the inspection unit in one direction.

Wherein the inspection unit includes a camera for photographing a surface of the mask and an illumination for emitting light toward the mask so that the camera can take a picture of the surface of the mask, Can be constructed.

The plurality of unit inspection groups may be arranged in a direction crossing the direction in which the mask is conveyed.

The inspection unit may include a second transfer unit for transferring the unit inspection tanks in a direction crossing the direction in which the mask is conveyed.

The second transfer unit may transfer the repair unit together with the unit inspection unit in a direction crossing the direction in which the mask is conveyed.

Wherein the mask support portion includes a stage provided with a flat surface and provided with a surface plate having a long side in a direction in which the mask is transported, wherein the stage includes a collecting groove for collecting foreign substances generated during the processing process of the mask, And a discharge port for discharging the foreign matter may be formed.

Wherein the mask supporting unit comprises: a support unit supported by the stage and conveyed by the first conveyance unit; a lift unit that is driven to move up and down toward the support unit and conveys the mask loaded from the outside to the support unit; And aligning the mask with the mask at a predetermined position.

The supporting unit may include a frame that supports the mask transferred from the elevating unit and prevents the alignment unit from directly contacting the mask to prevent damage to the mask.

Wherein the mask further comprises an alignment mark and the mask support further comprises a photographing unit for photographing the alignment mark, wherein the alignment unit roughly aligns the mask before the photographing of the alignment mark, The mask can be precisely aligned according to the result of photographing the alignment mark.

According to another aspect of the present invention, there is provided a mask processing method including: a mask holding step of holding a mask on a mask supporting part; an inspection step of inspecting a surface of the mask to check whether the mask adheres to the mask, And a repair step of removing the foreign matter adhered to the mask.

In the mask inspection step, the first transfer unit provided in the mask support unit may transfer the mask in one direction.

Wherein the inspection unit includes a camera for photographing a surface of the mask and an illumination for emitting light toward the mask so that the camera can take a picture of the surface of the mask, Can be constructed.

A plurality of the unit inspection tanks may be arranged in a direction crossing the direction in which the mask is conveyed.

The inspection step may transfer the unit inspection tanks in a direction crossing the direction in which the mask is transported by the second transfer unit provided in the inspection unit.

The repairing step may be such that the second transferring unit transfers the repair part together with the unit inspection assembly.

The repairing step may burn or crush the foreign matter by irradiating a laser beam toward the foreign matter.

The mask processing apparatus and the mask processing method using the same according to the present invention can improve both the production efficiency and the reliability of the process using the processed mask by enabling both the inspection process and the repair process of the mask to be performed in a single apparatus have.

1 is a perspective view showing a mask processing apparatus according to an embodiment of the present invention.
2 is a front view showing a mask processing apparatus according to an embodiment of the present invention.
3 is a side view schematically showing the elevating unit of the mask treating apparatus according to the present embodiment.
4 is a perspective view showing a support unit and alignment unit of the mask processing apparatus according to the present embodiment.
5 is a plan view showing an alignment unit and a frame of the mask processing apparatus according to the present embodiment.
6 is a perspective view illustrating an inspection unit and a repair unit of the mask inspection apparatus according to an embodiment of the present invention.
7 is a cross-sectional view showing a first illumination and a second illumination of the mask processing apparatus according to an embodiment of the present invention.
8 is a flowchart illustrating a mask processing method using a mask processing apparatus according to an embodiment of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only examples of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents and modifications may be made thereto .

Hereinafter, a mask processing apparatus according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a mask processing apparatus according to an embodiment of the present invention, and FIG. 2 is a front view showing a mask processing apparatus according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, a mask processing apparatus (hereinafter referred to as a 'mask processing apparatus') according to an embodiment of the present invention inspects a foreign substance of a mask 10 used for manufacturing an OLED, In order to remove foreign matter from the mask 10 in accordance with the present invention. The mask 10 is made of a rectangular plate, and a predetermined pattern hole can be formed. The mask processing apparatus for processing such a mask 10 may include a mask support 100, an inspection unit 200, and a repair unit 300.

The mask support 100 may include a stage 110, an elevation unit 120, a support unit 130, an aligning unit 140, a photographing unit 150 and a first conveying unit 160.

The stage 110 provides a flat surface for ensuring the reliability of the mask 10 inspection. The stage 110 may be provided with a rectangular platen having a long side and a short side so as to secure a distance at which the mask 10 can be linearly transferred during the inspection and repair of the mask 10.

A large number of driving systems are operated during the processing of the mask 10 for removing foreign substances from the mask 10 in accordance with the foreign matter inspection result of the mask 10 as described above. Accordingly, if the foreign substances separated from the mask 10 and the foreign substances generated by the operation of the driving system remain in the interior of the mask processing apparatus, it is difficult for the mask 10 to be inspected and repaired smoothly. Therefore, in order to discharge the foreign substances that may be generated during the processing of the mask 10 to the outside, the stage 110 disposed below the components of the mask processing apparatus includes a collecting groove 111 for collecting foreign substances, And an outlet 113 opened toward the outlet 111 may be formed. Of course, although not shown, a discharge pump 113 may be connected to the discharge port 113 to form a pressure necessary to discharge the foreign substance to the outside.

The lifting unit 120 transfers the mask 10 carried from the outside to the supporting unit 130.

3 is a side view schematically showing the elevating unit of the mask treating apparatus according to the present embodiment.

3, the elevating unit 120 may include a support 121, an elevating shaft 123, a power transmitting shaft 124, and a lifting motor 125. As shown in FIG. The support base 121 and the lift shaft 123 may be provided in plural to support the respective corners of the mask 10 together to support the mask 10 in a flat and stable manner. The support 121 is protruded toward the mask 10 to support the mask 10 loaded from the outside and after the mask 10 is lowered and transferred to the support unit 130 to be described later, As shown in Fig. The power transmission shaft 124 has a simple structure and connects the elevating motor 125 and the elevating shaft 123 so that the elevating shafts 123 have the same elevating distance and can be raised and lowered together. The lifting motor 125 provides power for lifting and lowering the mask 10. A dust cover 126 may be provided on the outer circumference of each lifting shaft 123 to prevent foreign matter from being scattered due to the lifting and lowering of the lifting shaft 123. The vibration damping cover 126 may be a bellows that surrounds the outer diameter portion of the lifting shaft 123 without interfering with the lifting and lowering of the lifting shaft 123. A power transmission element 127 such as a bevel gear for connecting two axes, horizontal and vertical, is provided between the elevation shaft 123 and the power transmission shaft 124. In the housing constituting the power transmission element 127, A plurality of suction openings 128 may be provided for sucking foreign substances scattered around and discharging the foreign substances to the outside.

The support unit 130 supports the mask 10 transferred from the lift unit 120.

FIG. 4 is a perspective view showing a support unit and alignment unit of the mask processing apparatus according to the present embodiment, and FIG. 5 is a plan view showing an alignment unit and a frame of the mask processing apparatus according to this embodiment.

4 and 5, the support unit 130 may include a base 131, a free shaft 132, and a frame 133.

The base 131 is supported on the stage 110. The base 131 may include a support plate 131a and a pair of side walls 131b. The support plate 131a may be provided in the form of a rectangular frame through which the central portion of the third illumination 240 penetrates so as to illuminate the mask 10 toward the mask. A pair of side walls 131b are formed on the support plate 131a so that the mask 10 can be transferred by the first transfer unit 160 to be described later and the third illumination 240 can be installed on the lower side of the support plate 131a. Is spaced apart from the stage 110.

The free shaft 132 is supported on the base 131. A plurality of free shafts 132 may be provided and the plurality of free shafts 132 may be dispersedly arranged at positions corresponding to the rim portions of the frame 133. The plurality of free shafts 132 uniformly disperses the load of the frame 133 on which the mask 10 is mounted. The free shaft 132 supporting the frame 133 may be constituted by a disk 132a and a housing 132b disposed below the disk 132a and constraining the disk 132a. The disk 132a can be restrained in the housing 132b so that the rod extending from the lower surface can be freely rotated in all directions in the planar direction and can be constrained to the housing 132b so as to be able to move up and down. A brake (not shown) may be installed inside the housing 132b to fix the position of the disk 132a as the air pressure is supplied.

The frame 133 supports the mask 10. The frame 133 may be provided in the form of a rectangular frame capable of supporting the edge portion of the mask 10 together so as to support the mask 10 in a flat and stable manner. The frame 133 is used to hold the mask 10 during alignment with components such as a free shaft 132, a roller 141a, a stopper 142, etc., So that the mask 10 can be prevented from being damaged by direct contact with the mask 10.

The alignment unit 140 aligns the mask 10 supported by the support unit 130 in a predetermined position. The aligning unit 140 is supported on the base 131. The alignment unit 140 may include an edge pusher 141. The edge presser 141 presses the edge of the frame 133 to align the mask 10 seated on the frame 133 at a predetermined position. That is, the corner presser 141 may include a roller 141a that comes into rolling contact with the edge of the frame 133, and a corner pressing cylinder 141b that presses the roller 141a. The corner pushers 141 may be arranged in two corresponding to one edge of the mask 10. [ That is, the corner presser 141 may be arranged to press the two adjacent sides of the neighboring frame 133, respectively.

Referring again to Figures 1 and 2, the photographing unit 150 photographs the alignment mark 11 provided on the mask 10. The photographing unit 150 may be disposed on the upper side of the stage 110. The aligning unit 140 roughly aligns the position of the mask 10 by pressing the four corners of the frame 133 according to a predetermined value, After the alignment mark 11 is picked up by the unit 150, the aligning unit 140 presses the four corners of the frame 133 one more time in accordance with the photographing result of the alignment mark 11, Can be precisely aligned.

As such, after alignment and alignment of the mask 10, alignment must be maintained. Accordingly, the alignment unit 140 may further include a stopper 142 as shown in FIGS. And can be disposed respectively on the outer sides of two opposing sides of the frame 133 so as to correspond to two mutually opposing sides of the mask 10. The stopper 142 may include a pressure plate 142a for pressing the outer wall of the frame 133 and a stopper cylinder 142b for pressing the pressure plate 142a.

The first transfer unit 160 transfers the support unit 130 in one direction. The first transfer unit 160 is a linear actuator that linearly feeds the support unit 130 using a rail 161 disposed in the longitudinal direction of the stage 110 (for example, a combination of a rack and pinion and a motor, A combination of a ball screw and a motor, or the like).

On the other hand, a gantry 115 may be disposed above the stage 110. The inspection unit 200 and the repair unit 300 are supported by the gantry 115.

FIG. 6 is a perspective view showing an inspection unit and a repair unit of a mask inspection apparatus according to an embodiment of the present invention, and FIG. 7 is a cross-sectional view illustrating a first illumination and a second illumination of the mask processing apparatus according to an embodiment of the present invention.

6 and 7, the inspection unit 200 inspects the mask 10 conveyed by the first conveyance unit 160. As shown in FIG. The inspection unit 200 may include a camera 210, a first illumination 220, a second illumination 230, a third illumination 240, and a second transfer unit 250.

The camera 210 captures the surface of the mask 10 to acquire an image of the surface of the mask 10. As the camera 210, a CCD (Charge Coupled Device) imaging device can be used.

The first illumination 220 may include a first light source 221 and a first mirror 212. The first mirror 212 may have a dome structure having a concave surface 212a concaved toward the mask 10. [ The first light source 221 is disposed at the rim of the first mirror 212 to emit the first light L1 toward the concave surface 212a. The first light L1 may be reflected by the concave surface 212a and incident on the mask 10. [ The first illumination 220 may condense a plurality of first lights L1 emitted by the plurality of first light sources 221 onto the mask 10. Accordingly, the first illumination 220 can be usefully used when it requires a relatively large amount of light, or a relatively large light intensity (for example, when the second illumination 220 is ambiguous in discrimination of foreign matter).

The second illumination (230) is disposed above the first illumination (220). The second illumination 230 may include a second light source 231 and a second mirror 232. The second light source 231 is disposed on one side of the second mirror 232. The second mirror 232 guides the second light L2 emitted from the second light source 231 to the mask 10 so as to be incident on the mask 10 coaxially with the first light L1.

Thus, the first and second lights L1 and L2 are reflected from the mask 10 and are incident on the camera 210. Accordingly, the first mirror 212 and the second mirror 232 reflect the first and second lights L1 and L2 emitted from the first light source 221 and the second light source 231, An optical mirror through which the reflected light RL reflected can be used.

One camera 210 and one second illumination 230 disposed below the camera 210 and one first illumination 220 disposed below the second illumination 230 are arranged in a unit inspection zone . A plurality of unit inspection tanks are provided, and a plurality of inspection tanks can be arranged in a direction crossing the direction in which the mask 10 is conveyed. The plurality of inspection tanks can photograph the area corresponding to the length in the direction crossing the direction in which the mask 10 is conveyed at a time to shorten the inspection time.

The third illumination 240 includes a linear third light source 241 having a length in a direction crossing the direction in which the mask 10 is conveyed. The third illumination unit 240 is disposed below the support unit 130 and irradiates the linear third light toward the mask 10 toward the mask 10 conveyed by the first transfer unit 160. The third light L3 passes through the open portion of the pattern of the mask 10 and may be incident on a plurality of cameras 210 arranged in a plurality of inspection tanks. The third illumination 240 may be useful when distinguishing a foreign substance from a pattern hole in a mask 10 having a pattern hole formed thereon. (See Fig. 2).

The second transfer unit 250 transfers the inspection unit 200 in a direction crossing the direction in which the mask 10 is conveyed in order to correspond to the sizes of the various masks 10. The second transfer unit 250 includes a horizontal frame of the gantry 115 serving as a rail and a linear block 251 which is provided so as to be movable along the horizontal frame. (E.g., a combination of a rack and pinion and a motor, a combination of a ball screw and a motor, or the like) that linearly feeds a line in a direction intersecting the feeding direction.

Since the inspection unit 200 includes the first, second, and third lights 220, 230, and 240, the mask 10 can be precisely inspected using light that is different depending on the type of the foreign matter of the mask 10 .

The repair unit 300 removes the foreign substance if the foreign substance exists on the surface of the mask 10 as a result of inspection of the mask 10 using the camera 210. The repair unit 300 may include a laser 310. The laser 310 is supported by the linear block 251 and can be transported in a direction crossing the direction in which the mask 10 is transported together with a plurality of inspection tanks. As a result of the inspection of the mask 10, the laser 310 is transferred to a position corresponding to the position of the foreign substance to emit a laser beam toward the foreign substance, and the foreign substance can be burnt by the laser beam or crushed and removed from the mask. Of course, the laser 310 can change the wavelength band of the laser beam depending on the kind of foreign matter. Further, although not shown, a nozzle or an intake port capable of blowing or sucking foreign matter removed by the laser 310 can be additionally disposed.

Hereinafter, a mask processing method using the mask processing apparatus according to the present invention will be described with reference to the accompanying drawings.

8 is a flowchart illustrating a mask processing method using a mask processing apparatus according to an embodiment of the present invention.

Referring to Fig. 8, the mask 10 may be supported by a robot arm (not shown) and loaded into the mask processing apparatus. The lifting unit 120 lifts the support 121 and receives the mask 10 from the robot arm (not shown). When the mask 10 is supported on the support base 121, the robot arm (not shown) escapes to the outside. The lifting unit 120 moves the support 121 downward. As the support table 121 is lowered, the mask 10 is supported on the frame 133.

At this time, since the frame 133 is supported on the free shaft 132, the mask 10 is freely rotatable in all directions in the planar direction and is in a state in which it can be raised and lowered. The aligning unit 140 drives the corner presser 141 and the corner presser 141 presses the edge of the frame 133 to align the mask 10 in a rough manner. The photographing unit 150 photographs the alignment mark 11 provided on the mask 10. [ The aligning unit 140 drives the corner presser 141 in accordance with the result of the photographing of the alignment mark 11 and the corner presser 141 presses the edge of the frame 133 once again, do. When the precise alignment of the mask 10 is performed in this way, the stopper 142 presses the mask 10 to maintain the state in which the mask 10 is firmly supported by the support unit 130. [ (Step S11)

The first transfer unit 160 transfers the mask 10 in one direction. As the first transfer unit 160 transfers the mask 10, the mask 10 passes under the inspection unit 200 and the inspection unit 200 takes a picture of the surface of the mask 10. That is, any one of the first illumination 220, the second illumination 230, and the third illumination 240 may be selected to irradiate light toward the mask 10, or a plurality of It is possible to irradiate the mask 10 with light. Thus, the light reflected from the mask 10 or transmitted through the mask 10 is incident on the camera 210, and the camera 210 can photograph the surface of the mask 10.

At this time, if it is possible to take an image of the entire surface of the mask 10 by only a plurality of inspection tanks arranged in a direction crossing the direction in which the mask 10 is conveyed, the second transfer unit 250 does not transfer a plurality of inspection tanks You do not need to. The first transfer unit 160 performs the transfer operation of the mask 10 intermittently and the second transfer unit 250 transfers the mask 10 to a plurality of It is possible to carry out photographing of the entire surface of the mask 10 while transferring the inspection trough of the mask 10 in the direction crossing the direction in which the mask is conveyed. (Step S13)

When the photographing of the entire surface of the mask 10 is completed and foreign matter is detected on the surface of the mask 10 as described above, the second transfer unit 250 transfers the linear block 251 to a position corresponding to the coordinates, The laser 310 irradiates the laser beam to the position. As the laser beam is incident on the foreign object, the foreign substance can be burnt or crushed and removed from the surface of the mask 10. [ (Step S15)

As described above, the mask processing apparatus and the mask processing method according to an embodiment of the present invention can improve both the inspection efficiency and the reliability of the process using the processed mask by performing both the mask inspection process and the repair process in a single apparatus. There is an effect that can be improved.

The embodiments of the present invention described above and shown in the drawings should not be construed as limiting the technical idea of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and those skilled in the art will be able to modify the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of the present invention as long as they are obvious to those skilled in the art.

10: mask 11: alignment mark
100: mask support 110: stage
111: collecting groove 113:
115: gantry 120: elevating unit
121: support member 123: lifting shaft
124: power transmission shaft 125: elevating motor
126: dust cover 127: power transmission element
128: Suction port 130: Supporting unit
131: Base 131a:
131b: side wall 132: free axis
132a: Disk 132b: Housing
133: frame 140: alignment unit
141: Edge presser 141a: Roller
141b: Cylinder for pressurizing corners 142: Stopper
142a: pressure plate 142a: 142b: cylinder for stopper
150: photographing unit 160: first conveying unit
161: Rail 200: Inspector
210: camera 220: first illumination
211: first light source 212: first mirror
212a: concave surface 230: second illumination
231: second light source 232: second mirror
240: third illumination 241: third light source
250: second transfer unit 251: linear block
300: Repair part 310: Laser
L1: first light L2: second light
L3: Third optical RL: Reflected light

Claims (17)

A mask support for supporting the mask;
An inspection unit for photographing a surface of the mask and inspecting whether or not the mask adheres to foreign matter; and
And a repair unit that removes the foreign substance adhered to the mask according to the inspection result of the mask. The method according to claim 1,
Wherein the mask support portion includes a first transfer unit that transfers the mask to the inspection portion in one direction. 3. The method of claim 2,
The inspection unit
A camera for photographing a surface of the mask;
And illumination for emitting light toward the mask so that the camera can take a picture of the surface of the mask,
Wherein the camera and the illumination are arranged on a coaxial line to constitute a unit inspection trough. The method of claim 3,
The plurality of unit test groups are provided,
Wherein the plurality of unit inspection groups are arranged in a direction crossing the direction in which the mask is conveyed. The method of claim 3,
The inspection unit
And a second transfer unit for transferring the unit inspection tanks in a direction crossing the direction in which the mask is conveyed. 6. The method of claim 5,
And the second transfer unit transfers the repair unit together with the unit inspection unit in a direction crossing the direction in which the mask is conveyed. 3. The method of claim 2,
Wherein the mask support portion includes a stage provided with a flat surface providing a flat surface and having a long side in a direction in which the mask is transported,
Wherein the stage is provided with a collecting groove for collecting foreign substances generated in the mask processing step and an outlet opening toward the collecting groove to form a discharge path for the foreign matter. 8. The method of claim 7,
The mask support
A support unit supported on the stage and conveyed by the first conveyance unit;
An elevating unit which is driven to move up and down toward the supporting unit and transfers the mask loaded from the outside to the supporting unit;
And an alignment unit for aligning the mask transferred to the support unit at a predetermined position. 9. The method of claim 8,
The support unit
And a frame for supporting the mask transferred from the lift unit and preventing the alignment unit from directly contacting the mask to prevent damage to the mask. 9. The method of claim 8,
Wherein the mask is provided with an alignment mark and the mask support further comprises a photographing unit for photographing the alignment mark,
Wherein the aligning unit roughly aligns the mask before photographing the alignment mark and then precisely aligns the mask according to a photographing result of the alignment mark after photographing the alignment mark. A mask supporting step in which the mask is supported on the mask supporting part;
Inspecting the surface of the mask by the inspection unit to inspect whether or not the mask adheres to the mask; and
And a repairing step of removing the foreign matter adhered to the mask by a repair part in accordance with the inspection result of the mask. 12. The method of claim 11,
The mask inspection step
Wherein the mask supporting portion transfers the mask in one direction by a first transfer unit provided in the mask supporting portion. 12. The method of claim 11,
The inspection unit
A camera for photographing a surface of the mask;
And illumination for emitting light toward the mask so that the camera can take a picture of the surface of the mask,
Wherein the camera and the illumination are arranged on a coaxial line to form a unit inspection trough. 14. The method of claim 13,
The checking step
Wherein the plurality of unit inspection tanks are arranged in a direction crossing a direction in which the mask is conveyed. 14. The method of claim 13,
The checking step
And the second transfer unit provided in the inspection unit transfers the unit inspection tanks in a direction crossing the direction in which the mask is conveyed. 16. The method of claim 15,
The repair step
And the second transfer unit transfers the repair part together with the unit inspection tanks. 12. The method of claim 11,
Wherein the repairing step comprises a step of irradiating a laser beam toward the foreign substance to burn or crush the foreign substance.

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