KR102260684B1 - CMP apparatus having uniformity improvement function of display substrate - Google Patents

Abstract

The present invention is provided with a thickness detection unit of the display substrate in order to polish the display substrate so that it has a uniform thickness regardless of the polishing position on the display substrate to detect the thickness in real time and thereby measure the height of the lower surface plate through the contact area adjusting unit. By allowing adjustment, the polishing pad prevents over-abrasion in specific areas of the display substrate and allows for uniform polishing throughout.

Description

CMP apparatus having uniformity improvement function of display substrate

This document relates to a CMP apparatus having a function of improving the thickness uniformity of a display substrate, and specifically relates to a technique for adjusting or controlling the pressing force of the lower platen in order to prevent the polishing pad from grinding the edge of the display substrate. do.

Recently, a display device using an organic light emitting diode (OLED) is attracting attention.

The organic light emitting diode display has a self-luminous property, and unlike a liquid crystal display device, it does not require a separate light source, so a thickness and weight can be reduced. The organic light emitting diode display exhibits high quality characteristics such as low power consumption, high luminance, and fast response speed. Currently, the resolution applied to small and medium-sized organic light emitting diode (OLED) panels is QHD (Quad High Definition, 2560 x 1440) level, but the next-generation display, VR (Virtual Reality) / AR (Augmented Reality) panel, has more clarity than QHD There is a demand for OLED products with superior ultra-high resolution UHD (Ultra High Definition, 3840 x 2160) or higher.

However, in order to develop UHD-class next-generation OLED panels, it is necessary to realize the miniaturization pattern of the photolithography process according to the increase in pixel density and to solve the afterimage problem of the panel Solving it is more important than anything else. In order to solve this problem, it is important to smooth the Poly_Si film constituting the display substrate of the OLED TFT (Thin Film Transistor) on which the transistor element will be formed, and this can be solved through the CMP (Chemical Mechanical Polishing) process. This CMP process may include a process of removing protrusions (Hillock) generated in the Poly-Si layer during crystallization (ELA) of the OLED TFT glass display substrate composed of the SiO 2 layer and the Poly-Si layer. Hillac also makes the formation of additional metal layers difficult.

1 is a view for explaining before and after a CMP process of an OLED TFT glass display substrate. As shown, in the OLED TFT glass display substrate before the CMP process, hillock occurred on the top of the Poly-Si layer (Fig. 1(a)), and the hillock was removed through the CMP process to realize planarization (Fig. 1(b)). )).

In general, the process using CMP equipment performs mechanical polishing by moving an upper platen with a polishing pad attached thereto or rolling a cylindrical polishing cylinder (roller), and at the same time applying a slurry to the display substrate to chemically A technique for performing polishing is disclosed. In addition, a chemical mechanical polishing technique has been disclosed in which a lower platen on which the display substrate is mounted is rotated and the upper platen is partially in contact with the display substrate.

However, when the upper surface plate to which the polishing pad is attached applies pressure to the display substrate to polish the display substrate, the edge portion of the large-area display substrate having a generally rectangular structure, particularly the long side center edge portion, is over-polished. The reason is first, since the long side edge area among the edge areas is longer and wider than the other portions, the long side center edge portion has a long contact time with the polishing pad. Second, when the upper surface plate is positioned at the edge portion of the large-area display substrate, the contact area between the upper surface plate and the display is reduced, so that the load of the upper surface plate is concentrated on the edge portion, thereby increasing the pressure per unit area.

Korean Patent Publication (Public Publication No.: 10-2018-0075155, "Large-area substrate polishing apparatus") discloses a cylindrical polishing cylinder having a polishing pad on its outer circumferential surface, and a substrate having a leveling device for adjusting the level of the polishing cylinder A technique for controlling the polishing uniformity and polishing rate of However, a technique for partially adjusting or controlling the polishing pressure of the display substrate and the polishing pad is not disclosed.

An object of the present invention is to increase polishing uniformity in a substrate by preventing over-polishing of an edge (corner) portion of a display substrate when a large-area display substrate is polished with a polishing pad.

CMP apparatus according to an aspect for achieving this object,

A lower platen on which the display substrate is seated and rotationally driven, and

An upper platen disposed on the upper side of the lower platen and provided with a circular polishing pad on the lower surface to polish the display substrate by frictional force caused by the rotation of the lower platen;

A swing arm with one end connected to the upper surface plate,

Upper platen driving means connected to the other end of the swing arm to drive the upper platen up and down and horizontally drive the upper platen through the swing arm;

A thickness detection unit for detecting the thickness of the display substrate in real time, and

A contact area control unit for controlling a contact area between the upper surface plate and the display substrate by adjusting a height of a portion of the upper surface plate may be included.

The present invention enables the polishing process to be performed while maintaining a uniform thickness of the display substrate regardless of the polishing position such as the corner area or the central portion on the display substrate, thereby preventing over-abrasion of the corner area and performing precise polishing. Therefore, it is possible to partially control the amount of polishing, and finally, a clear difference in the amount of polishing between the corner area and the center area of the display substrate is reduced.

In addition, it is possible to detect the thickness of each part of the display substrate in real time and to partially adjust the height of the lower surface plate accordingly, so that the optimized polishing pressure can be determined through repeated experiments. Due to this, it is possible to perform a polishing process while maintaining a uniform display substrate thickness.

1 is a view for explaining before and after a CMP process of an OLED TFT glass display substrate.
2 is a view for explaining a top surface of a CMP apparatus according to an embodiment.
3 is a view for explaining a conventional polishing amount for each portion of a substrate and an upper surface of a CMP apparatus for polishing an edge region according to an embodiment.
4 is a perspective view illustrating a CMP apparatus having a function of improving the uniformity of a display substrate using a magnetic force according to an embodiment.
5 is a view for explaining a side view of a CMP apparatus having a function of improving the uniformity of a display substrate using an optical thickness detector according to another embodiment.
6 is a view for explaining a side surface of a CMP apparatus further including a contact area control unit according to another embodiment.
7 is a view for explaining an improved polishing amount for each area of a substrate according to an exemplary embodiment.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily understand and reproduce it through preferred embodiments described with reference to the accompanying drawings. In describing the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the embodiments of the present invention, the detailed description thereof will be omitted. Terms used throughout the present specification are terms defined in consideration of functions in the embodiment of the present invention, and since they can be sufficiently modified according to the intention, custom, etc. of a user or operator, the definitions of these terms are defined throughout this specification. It should be made based on the contents of

Also, the above and further aspects of the invention will become apparent through the following embodiments. It is believed that the aspects or configurations of the optionally described embodiments herein can be freely combined with each other, even if shown as a single integrated configuration in the drawings, unless it is apparent to a person skilled in the art that there is a technical contradiction in the art, unless otherwise stated. It is understood.

Accordingly, the configuration shown in the embodiments and drawings described in the present specification is only the most preferred embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

2 is a view for explaining a top surface of a CMP apparatus according to an embodiment. As shown, the CMP apparatus 1000 includes a lower platen 100, an upper platen 200, a swing arm 300, an upper platen driving means 400, and a control unit 800. can be configured. The lower surface plate 100 is a plate on which the display substrate 10 can be mounted. The lower surface plate 100 may be rotationally driven in a clockwise or counterclockwise direction, and may have a shape corresponding to that of the display substrate 10 , that is, a rectangular shape.

The display substrate 10 may be an OLED TFT glass composed of an SiO2 layer and a Poly-Si layer, and any substrate that can be a display substrate may correspond to this. The display substrate 10 may also rotate in the same direction by the rotation of the lower surface plate 100 . As illustrated, as the lower surface plate rotates counterclockwise, the display substrate 10 also rotates counterclockwise. The display substrate may be a large-area substrate.

The upper surface plate 200 may be a circular plate as a plate for planarization or thickness uniformity of the substrate by causing friction with the display substrate 10 .

Since the upper surface plate 200 is a circular plate, it is easy to rotate and thus has excellent polishing performance. The upper platen 200 may polish the display substrate by frictional force generated by the rotation of the lower platen.

The upper surface plate 200 may be disposed on the upper side (Over) of the lower surface plate, and may be driven up and down by the upper surface plate driving means 400 . The upper platen 200 has an upper platen body thereon, and the upper platen body may be provided with a slurry hole 210 through which slurry is introduced and discharged. The slurry hole may be connected to a pipe (not shown) to receive the slurry from the outside.

The swing arm 300 connects the upper platen 200 and the upper platen driving means 400 and may be hinged.

The upper platen driving means 400 is connected to one end of the swing arm 300 to perform a function of raising and lowering the upper platen 200 so that the upper platen is in contact with the display substrate 10 and It can be made non-contact. In addition, the upper surface plate driving means 400 may generate a horizontal force at one end of the swing arm 300 , and thus the upper surface plate 200 may also be moved in the horizontal direction (horizontal swing motion). The upper platen driving means 400 is preferably a cylinder method, but a motor method may also be applied, and a method combining both, for example, lifting and lowering driving is applied in a cylinder method, and horizontal driving may be applied in a motor method.

The lower platen 100 and the upper platen driving means 400 may be electrically connected to the controller 800 to control driving operations (eg, rotational speed, rotational angle, etc.).

3 is a view for explaining a conventional polishing amount for each portion of a substrate and an upper surface of a CMP apparatus for polishing an edge region according to an embodiment. As shown in FIG. 3( a ), the upper surface plate 200 polishes a corner (edge) region of the display substrate 10 . As the center of the upper surface plate 200 is biased toward the edge (edge) region and the longer edge region, the amount of polishing increases, so that uniformity of the thickness of the substrate cannot be achieved.

The reason is, firstly, since the long side edge portion is wider than the other portions, the long side center edge portion has a long contact time with the polishing pad. Second, when the upper surface plate is located at the edge portion of the large-area display substrate, the contact area between the upper surface plate and the display is reduced, so that the load on the upper surface plate is concentrated on the edge portion and the upper surface plate is deflected to increase the pressure per unit area. because it becomes As a result, over-polishing occurs in the edge area (edge area).

As shown in Fig. 3(b), there is a significant difference between the polishing amount (median value: 192.24 Å) of the corner portion (edge portion) of the display substrate 10 and the polishing amount (median value: 125.931 Å) of the central portion of the display substrate 10 . did. This may cause a decrease in thickness uniformity, which may cause defects in the display panel.

In a rectangular substrate, the polishing amount increases as the edge area increases, and the polishing amount increases in the long side area rather than the short side area.

4 is a perspective view illustrating a CMP apparatus having a function of improving the uniformity of a display substrate using a magnetic force according to an embodiment. Fig. 4(a) is a view for explaining a CMP apparatus in which the second magnet 501 is raised and lowered, and Fig. 4(b) is a view for explaining a CMP apparatus in which the second magnet 501 is lowered.

As shown, the CMP apparatus 1000 having a polishing pressure control function includes a lower platen 100, an upper platen 200, an upper platen 200, a swing arm 300, and a polishing pressure controller ( 500, contact area controller).

The lower surface plate 100 has the display substrate 10 seated therein and can be rotationally driven. The display substrate may be an OLED TFT glass substrate, but a substrate for manufacturing a display panel is sufficient. The lower surface plate 100 may be horizontally rotated by a motor (not shown) attached thereto by rotation of the motor.

The upper surface plate 200 has a circular shape, is located on the upper surface of the lower surface plate, and can be driven up and down on the substrate. The elevating driving may be driven by the upper surface plate driving means 400 of FIG. 2 . Due to the circular shape of the upper platen, it is advantageous to apply precise partial pressure. The upper surface plate may be provided with a slurry hole 210 in a vertical direction.

The upper surface plate 200 is provided on the lower surface and in contact with the substrate, and a polishing pad (not shown) for polishing the substrate by frictional force caused by the rotation of the lower surface plate (not shown) and a first magnet 101 provided in the edge region of the upper surface; first magnet). As for the first magnet, a plurality of divided magnets may be arranged on the upper platen along the circumference. The first magnet may be a permanent magnet or an electromagnet, but a permanent magnet is preferred. The pressure may be adjusted by changing the quantity of the plurality of first magnets.

When the lower surface plate rotates, the seated substrate also rotates. As the polishing pad of the upper surface plate contacts and applies pressure to the display substrate, the upper surface plate also rotates and frictional force may be generated.

The polishing pressure control unit 500 is located on an upper side of the upper surface plate, and may apply partial pressure to the upper surface plate by magnetic force. The polishing pressure control unit 500 may be referred to as an MBA (Magnetic Balance Apparatus).

The polishing pressure control unit 500 is disposed close to the upper portion of the first magnet to generate an attractive or repulsive force with the first magnet 501, a second magnet (Second magnet), and a support frame for supporting the second magnet. (502, Supporting frame) and supported by the support frame, by elevating the support frame may be configured to include a driving motor (Driving motor) for adjusting the distance between the first magnet and the second magnet.

As shown in Figure 4 (a), when there is no need to apply a magnetic force to one side of the upper surface plate 200, the second magnet is raised and lowered so that the gap between the first magnet and the second magnet is widened. , as shown in Figure 4 (b), when it is necessary to apply a magnetic force to one side of the upper surface plate 200, the second magnet is lowered so that the gap between the first magnet and the second magnet is narrow. .

Accordingly, the thickness uniformity of the display substrate may be increased by partially adjusting and controlling the pressure between the polishing pad and the substrate.

5 is a view for explaining a side view of a CMP apparatus having a function of improving the uniformity of a display substrate using an optical thickness detector according to another embodiment. As shown, the CMP apparatus having the function of improving the uniformity of the display substrate includes a lower platen (100, Lower platen), an upper platen (200, Upper platen), a swing arm (300, Swing arm), a thickness detection unit 505, The contact area control unit 700 may be included.

The lower surface plate 100 has the display substrate 10 seated therein and can be rotationally driven. The display substrate may be an OLED TFT glass substrate, but a substrate for manufacturing a display panel is sufficient. The lower surface plate 100 may be horizontally rotated by a motor (not shown) attached thereto by rotation of the motor. The shape of the lower surface plate is preferably a rectangle (especially a rectangle) like a general display substrate, but the shape is not limited. The lower surface plate 100 may change the rotation angle and rotation speed according to the command of the controller.

When the lower surface plate rotates, the seated substrate also rotates. As the polishing pad of the upper surface plate contacts and applies pressure to the display substrate, the upper surface plate also rotates and frictional force may be generated.

The upper platen 200 is disposed on the upper side of the lower platen, and a circular polishing pad is provided on the lower surface to polish the display substrate by frictional force generated by the rotation of the lower platen. The upper surface plate preferably has a circular shape, which is advantageous for applying precise partial pressure. The upper surface plate may be provided with a slurry hole 210 in a vertical direction. The slurry hole may penetrate from the upper part of the upper platen to the polishing pad.

The swing arm may have one end connected to the upper surface plate and the other end connected to the upper surface plate driving means 400 .

The upper surface plate driving means 600 may be connected to the other end of the swing arm to vertically drive and horizontally drive the upper surface plate through the swing arm. The upper surface plate driving means 600 may change the rotation angle, rotation speed, and pressure according to the command of the control unit 800 .

The thickness detection unit 505 (a dotted line box portion) may detect the thickness of the display substrate in real time. Due to the thickness detection unit, it is possible to check the thickness of the display substrate during the polishing process and transmit data to the control unit 800 .

In addition, the thickness detection unit 505 may be fixedly disposed on the central region or one side region of the upper surface plate, and is fixedly disposed on the swing arm 300 to directly irradiate light (emission) to the upper surface of the display substrate 10 and can receive light.

A contact area control unit (not shown) is installed to extend to one side of the lower surface plate, and may control a contact area between the upper surface plate 200 and the display substrate 10 by adjusting a partial height of the upper surface plate.

6 is a view for explaining a side surface of a CMP apparatus further including a contact area control unit according to another embodiment. As shown, the contact area control unit 700 (a dotted line box area) is installed on one side of the lower surface plate, and controls the contact area between the upper surface plate 200 and the display substrate 10 by adjusting the height of a portion of the upper surface plate. can That is, when the upper surface plate 200 polishes the edge region of the display substrate 10 , over-polishing may occur in the edge region because the pressure per unit area is high in the edge region. In particular, the long edge area spends a lot more polishing time than the short edge area, so the sharpness becomes more pronounced. Accordingly, the contact area control unit 700 for controlling the contact area between the upper surface plate and the display substrate by adjusting the height of the part of the upper surface plate is provided. A contact area controller 700 extends to one side of the lower platen 100 and is coupled to the lower platen. The contact area control unit 700 may include a lift plate 701 in contact with the lower surface of the upper surface plate 200 , a support part 702 supporting the lift plate, and a driving part 703 for raising and lowering the support part. The driving unit may use a rotary motor or a pressure cylinder. The driving unit may be electrically connected to the control unit 800 and the operation may be controlled by the control unit. The lift plate does not need to be plate-shaped, and it is sufficient if it has an appropriate shape enough to be in contact with the lower part of the upper plate and to be pushed up.

As shown in FIG. 6 , the support part 702 is raised and lowered by the driving of the driving part 703 , and the lift plate 701 lifts the edge area of the upper platen 200 so that the upper platen is tilted from the horizontal line. to the slope (Slope). Due to this, the height of the upper surface plate can be partially adjusted. The contact area control unit 700 may adjust the lifting degree, ie, the operation of the driving unit, based on the thickness data value through the thickness detection unit 505 . Due to this, excessive abrasion is prevented in the edge region of the display substrate and ultimately, uniform polishing can be achieved. When the upper surface plate polishes the central region of the display substrate, the contact area control unit 700 may prevent the upper surface plate from being lifted, thereby controlling the contact area to be large. Similarly, when the upper surface plate polishes the edge region of the display substrate, it is possible to control the contact area between the upper surface plate and the display substrate to be small by pushing up the upper surface plate.

The contact area control unit 700 may be plural, and at least one may be provided on each side of the lower surface of the quadrangle.

The controller 800 may be electrically connected to the thickness detector, the lower platen, the contact area controller, and the upper platen driving means to receive data and control the driving operation.

7 is a view for explaining an improved polishing amount for each area of a substrate according to an exemplary embodiment. As shown, the difference between the polishing amount (median value: 103.625 Å) of the corner portion (edge portion) of the display substrate 10 and the polishing amount of the central portion (median value: 119.618 Å) is reduced. As a result, the thickness uniformity of the substrate was improved.

1000: CMP device
10: display board
100: lower surface plate
101: first magnet
200: upper surface plate
210: slurry hole
300: swing arm
400: upper surface plate driving means
500: polishing pressure control unit
501: second magnet
505: thickness detection unit
700: contact area control unit
701: lift plate
702: support
703: drive unit
800: control unit

Claims (4)

a lower surface plate on which a rectangular large-area display substrate is seated, a rectangular shape, and rotationally driven; and
an upper surface plate disposed on an upper side (Over) of the lower surface plate and provided with a circular polishing pad on the lower surface to polish a rectangular large-area display substrate by frictional force caused by rotation of the lower surface plate;
a swing arm having one end connected to the upper surface plate;
an upper surface plate driving means connected to the other end of the swing arm to vertically drive and horizontally drive the upper surface plate through the swing arm;
a thickness detection unit fixedly disposed on a swing arm, but detecting the thickness of the rectangular large-area display substrate in real time by irradiating and receiving light to the upper surface of the rectangular large-area display substrate; and;
A contact area control unit for controlling a contact area between the upper surface plate and the rectangular large-area display substrate by adjusting the height of a portion of the upper surface plate;
The contact area control unit,
A CMP device extending to one side of the lower surface plate and fastened to the lower surface plate. According to claim 1,
The contact area control unit,
A CMP device that controls the contact area between the upper surface plate and the display substrate to be small by pushing up the upper surface plate when the upper surface plate polishes the edge region of the display substrate. delete delete

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