KR102257002B1 - CMP apparatus having polishing pressure control function - Google Patents

Abstract

The present invention has a circular shape, is located on the upper surface of the lower platen, is provided with a polishing pressure control device that applies a partial pressure to the upper platen by magnetic force on the upper one side of the upper platen that drives up and down on the substrate, and is provided on the upper platen The flatness of the substrate may be improved by partially controlling the pressure of the upper platen by using non-contact attraction or repulsive force between the first magnet and the second magnet provided in the polishing pressure control device.

Description

CMP apparatus having polishing pressure control function TECHNICAL FIELD

This document relates to a CMP apparatus, and specifically, relates to a technique of adjusting a polishing pressure on a partial region of a substrate when a substrate of an organic light emitting diode (OLED) is subjected to chemical mechanical polishing (CMP).

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

The organic light-emitting display device has a self-emission characteristic, and unlike a liquid crystal display device, it does not require a separate light source, so that the 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 reaction speed. Currently, the resolution applied to small and medium-sized organic light-emitting diode (OLED) panels is QHD (Quad High Definition, 2560 x 1440), but the next-generation display, VR (Virtual Reality)/AR (Augmented Reality), has more clarity than QHD. There is a demand for OLED products with excellent ultra-high resolution UHD (Ultra High Definition, 3840 x 2160) or higher.

However, in order to develop a UHD-class next-generation OLED panel, a finer pattern of the photolithography process according to the increase in pixel density is realized and the afterimage problem of the panel is solved. Solving is more important than anything else. In order to solve this problem, it is important to smooth the Poly_Si film constituting the substrate of the OLED TFT (Thin Film Transistor) on which the transistor element will be formed, and this can be solved through a chemical mechanical polishing (CMP) 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 substrate composed of the SiO2 layer and the Poly-Si layer. Hillac also makes the formation of additional metal layers difficult.

1 is a diagram explaining before and after a CMP process of an OLED TFT glass substrate. As shown, in the OLED TFT glass 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 translating the upper plate with a polishing pad or by rolling a cylindrical polishing cylinder (roller), and at the same time applying a slurry to the substrate to perform chemical polishing. Carry out. However, it is difficult to apply a uniform pressure to the substrate so that the polishing pad has a uniform thickness. The reason is that the frictional force is different for each part within the polishing pad. This is noticeable when polishing a large area substrate.

When polishing is performed by applying pressure to the display substrate by a polishing pad with an upper surface plate attached thereto, over-polishing occurs in an edge portion of a large-area display substrate having a generally rectangular structure, particularly a center edge portion of the long side. The reason is: First, the long-side edge area of the edge area is longer and wider than the other areas, so the long-side center edge area has a long contact time with the polishing pad. Second, when the upper platen is located at the edge portion of the large-area display substrate, the contact area between the upper platen and the display decreases, so that the load of the upper platen is concentrated on the edge portion, thereby increasing the pressure per unit area.

Therefore, there is a need for an additional function of increasing or lowering the polishing pressure by controlling the level of the polishing pad and adjusting or controlling the partial contact pressure.

Korean Patent Publication (Publication Publication No.: 10-2018-0075155, "Large Area Substrate Polishing Device") is a substrate having a cylindrical polishing cylinder equipped with a polishing pad on an outer circumferential surface and a horizontality adjusting device that adjusts the level of the polishing cylinder. Disclosed is a technique for controlling the polishing uniformity and polishing rate. However, a technique for adjusting or controlling a partial contact pressure of a polishing pad using a non-contact magnetic force is not disclosed.

An object of the present invention is to increase the thickness uniformity of a display substrate by adjusting the horizontality of an upper half equipped with a polishing pad and partially adjusting and controlling the pressure between the polishing pad and the substrate.

CMP apparatus according to an aspect for achieving this purpose,

A lower platen on which the substrate is seated and driven to rotate,

An upper platen having a circular shape, located above the lower platen, and driving up and down on the substrate, and

It is located on one side of the upper surface of the upper surface, and includes a polishing pressure control apparatus for applying a partial pressure to the upper surface by magnetic force,

The upper platen,

A polishing pad provided on the lower surface to contact the substrate and for polishing the substrate by frictional force caused by the rotation of the lower platen, and

Including a first magnet (First magnet) provided in the edge region of the upper surface,

The polishing pressure control device,

A second magnet disposed close to the top of the first magnet to generate attractive force or repulsive force with the first permanent magnet, and

A supporting frame for supporting a second magnet,

It is supported by the support frame, it may be configured to include a driving motor (driving motor) for adjusting the distance between the first magnet and the second magnet by raising and lowering the support frame.

In the present invention, it is possible to precisely adjust the horizontality of the upper half equipped with the polishing pad, and to partially control the contact pressure between the polishing pad and the substrate, thereby enabling the polishing of a uniform and flat substrate. By applying and controlling dust (Particle) due to contact and friction of the upper half Can be prevented. In addition, the cost can be reduced due to the precise and rapid polishing.

1 is a diagram explaining before and after a CMP process of an OLED TFT glass substrate.
2 is a diagram illustrating a top surface of a CMP device according to an embodiment.
3 is a diagram illustrating a conventional polishing amount for each portion of a top surface and a substrate of a CMP apparatus for polishing an edge region according to an exemplary embodiment.
4 is a diagram illustrating a CMP apparatus having a polishing pressure control function according to an exemplary embodiment.
5 is a diagram illustrating an apparatus for controlling a polishing pressure according to an exemplary embodiment.
6 is a diagram illustrating an apparatus for controlling a polishing pressure according to another exemplary embodiment.
7 is a diagram illustrating an improved polishing amount for each portion 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 the present invention through preferred embodiments described with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the embodiments of the present invention, the detailed description thereof will be omitted. Terms used throughout the specification of the present invention are terms defined in consideration of functions in the embodiments of the present invention, and can be sufficiently modified according to the intention and custom of a user or operator, so the definitions of these terms are defined throughout the present specification. It will have to be made based on the contents of

In addition, the above-described and additional aspects of the invention will become apparent through the following embodiments. Aspects or configurations of the embodiments that are selectively described in the present specification may be freely combined with each other, unless otherwise indicated, unless otherwise indicated, unless otherwise indicated, even if they are shown as a single integrated configuration, they may be freely combined with each other unless it is apparent to those skilled in the art. I understand.

Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention. It should be understood that there may be equivalents and variations.

2 is a diagram illustrating a top surface of a CMP device according to an embodiment. As shown, the CMP device 1000 is configured to include a lower platen (Lower platen, 100), an upper platen (Upper platen, 200), arm 300, pressure driving means 400, the control unit 800. I can. The lower platen 100 is a plate on which the display substrate 10 can be mounted. The lower platen 100 may be driven to rotate in a clockwise or counterclockwise direction, and may have a shape corresponding to the display substrate 10, that is, a quadrangular shape.

The display substrate 10 may be an OLED TFT glass composed of a 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 platen 100. As shown, as the lower platen rotates in a counterclockwise direction, the display substrate 10 also rotates in a counterclockwise direction.

The upper platen 200 may be a circular plate as a plate for causing friction with the display substrate 10 to planarize the substrate or uniformize the thickness.

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

The upper platen 200 may be disposed on the upper side (Over) of the lower platen, and may be driven up and down by the pressure driving means 400. The upper platen 200 may have an upper platen cover thereon, and the upper platen cover 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 slurry from the outside.

The arm 300 connects the upper surface plate 200 and the pressure driving means 400 and may be hinged.

The pressure 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 contacts and non-contacts the display substrate 10. can do. In addition, the pressure driving means 400 may generate a force in the horizontal direction at one end of the arm 300, and thus the upper platen 200 may also be moved in the horizontal direction. The pressure driving means 400 is preferably a cylinder method, but a motor method may also be applied, and a method in which both are combined, for example, a lifting drive may be applied as a cylinder method and a horizontal drive may be applied as a motor method. The pressure driving means 400 may be electrically connected to the controller 800 to control the operation.

3 is a diagram illustrating a conventional polishing amount for each portion of a top surface and a substrate of a CMP apparatus for polishing an edge region according to an exemplary embodiment. As shown in FIG. 3A, the upper surface plate 200 polishes the edge (edge) region of the display substrate 10. As the center of the upper platen 200 is skewed toward the edge (edge) region and the longer the edge region is, the polishing amount increases, resulting in a problem that the thickness uniformity of the substrate cannot be achieved.

The reason is, first, 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 platen is located at the edge of the large-area display substrate, the contact area between the upper platen and the display decreases, so that the load of the upper platen is concentrated on the edge portion and sagging of the upper platen occurs, thereby increasing the pressure per unit area. Because it becomes. As a result, over-polishing occurs in the edge area (corner area).

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

4 is a diagram illustrating a CMP apparatus having a polishing pressure control function according to an exemplary embodiment. FIG. 4A is a diagram illustrating a CMP apparatus in which the second magnet 501 is raised and lowered, and FIG. 4B is a diagram illustrating a CMP apparatus in which the second magnet 501 descends.

As shown, the CMP device 1000 having a polishing pressure control function includes a lower platen 100, an upper platen 200, a swing arm 300, and a polishing pressure control device (500, Polishing pressure control device) may be included.

The display substrate 10 is mounted on the lower platen 100 and may be rotated. The display substrate may be an OLED TFT glass substrate, but a substrate for manufacturing a display panel is sufficient. The lower platen 100 is attached with a motor (not shown) and may rotate horizontally by rotation of the motor.

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

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

When the lower platen rotates, the seated substrate also rotates. As the polishing pad of the upper platen contacts and applies pressure to the display substrate, the upper platen also rotates, resulting in frictional force.

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

The polishing pressure control device includes a second magnet 501 (second magnet) that is disposed close to an upper portion of the first magnet to generate attractive or repulsive force with the first magnet, and a support frame 502 that supports the second magnet. , Supporting frame) and a driving motor that is supported on the support frame and adjusts the distance between the first magnet and the second magnet by raising and lowering the support frame. As shown in Fig. 4(a), when there is no need to apply a magnetic force to one side of the upper platen 200, the second magnet is raised and lowered so that the distance between the first magnet and the second magnet is far apart. , As shown in FIG. 4(b), when there is a need to apply a magnetic force to one side of the upper platen 200, the second magnet is lowered so that the distance between the first magnet and the second magnet is narrow. .

5 is a diagram illustrating an apparatus for controlling a polishing pressure according to an exemplary embodiment. As shown, the polishing pressure control device 500 includes a second magnet 501, a support frame 502, a drive motor 503, a sensor 504, a gear 506, and an LM guide 507. It can be configured. The polishing pressure control device 500 may be fixed to the swing arm 300.

The second magnet 501 may be a permanent magnet or an electromagnet, but a permanent magnet is preferred. The second magnet is disposed close enough to the first magnet 101 to generate magnetic force. The second magnet may have a different radius from the first magnet 101 to control its influence. The second magnet 501 and the first magnet 101 are disposed to face each other with the same polarity (N pole-N pole or S pole-S pole) to generate a repulsive force, and also, the same polarity (N pole- S-pole or S-N-pole) may be arranged to face each other to generate attractive force. As a result, pressure regulation can be performed partially by applying more or less pressure to a partial region of the upper platen, particularly a partial edge region.

For example, when over-polishing is in progress in the edge (edge) area of the display substrate, a partial area of the upper platen in contact with the edge (edge) area of the display substrate can be controlled to reduce the amount of polishing by depressurizing control. . If the central portion of the display substrate is undergoing insufficient polishing, a partial area of the upper surface that is in contact with the central area of the display substrate may be pressurized. This is advantageous in controlling uniform thickness.

The area in which the polishing pressure is controlled is the area where the second magnet 501 and the magnetic force of attraction or repulsion force are applied among the areas of the upper platen, and the largest in the first magnet 101 closest to the second magnet 501 Magnetic force will go crazy.

The support frame 502 may fixedly support the second magnet. The support frame 502 may support the second magnet 501. The number of gears 506 may be one, and may be three or more. The gear may be of a ball screw type.

The drive motor 503 may be connected to the gear 506 to move the support frame 502 up and down. The drive motor may be a servo motor and may be supported by a support frame. As a result, the second magnet 501 fixedly supported on the support frame 502 is also raised and lowered, so that the distance between the first magnet 101 and the first magnet 101 may be changed. Accordingly, the strength of the magnetic force is changed so that the strength of the pressure in the upper surface area can be partially adjusted, so that the contact pressure between the polishing pad and the display substrate can be adjusted, and the friction force can be adjusted. The driving motor 503 may be electrically connected to the controller 800 of FIG. 2 to control the operation.

The gear 506 is connected to the drive motor, and converts the rotational motion of the drive motor into a translational motion to move the support frame up and down. As a result, the second magnet is also raised and lowered.

The polishing pressure control device 500 may further include an LM guide 507.

In the CMP apparatus according to another embodiment, the polishing pressure control apparatus 500 may further include a sensor 504 for sensing a gap between the first magnet and the second magnet. The sensor 504 may detect and adjust the position to protect the motor and prevent collisions between magnets. The sensor 504 may be composed of a gap sensor and includes all other sensors for detecting a gap. The sensor 504 may be used for storing the initial position of the polishing pressure control device 500, and may also be used for the purpose of limiting a movement distance when the polishing pressure control device 500 is raised or lowered. Accordingly, a total of three sensors can be applied for the purpose of detecting an upper limit distance, detecting a home position, and detecting a lower limit position.

In the CMP apparatus according to another embodiment, the control unit 800 may further include a control unit 800 that receives space data between the first magnet and the second magnet generated by the sensor and controls the operation of the driving motor accordingly. .

In the CMP apparatus according to another exemplary embodiment, a thickness detection unit 505 installed on one side of a lower platen may further include a thickness detection unit 505 that detects a thickness of a display substrate in real time. Due to the thickness detection unit, the thickness of the display substrate can be checked during the polishing process and data can be transmitted to the control unit.

The thickness detection unit 505 includes a light emitting unit and a light receiving unit, and may detect the thickness of the display substrate based on the refractive index of the display substrate. In addition, the thickness detection unit 505 may be fixed and disposed at the center or one side of the upper platen, or may be fixedly disposed on the swing arm 300 to directly irradiate and receive light onto the display substrate. The thickness detection unit 505 may be electrically connected to the control unit 800 of FIG. 2 to provide measurement data. The controller 800 is electrically connected to the thickness detection unit 505, the polishing pressure control device 500, the pressure driving means 400, and the lower platen 100 to receive data and control the operation.

6 is a diagram illustrating an apparatus for controlling a polishing pressure according to another exemplary embodiment. 6(a) and 6(b) are views of the side of the polishing pressure control device 500, and FIG. 6(c) is a view of the rear side.

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

1000: CMP device
10: display substrate
100: lower platen
101: first magnet
200: upper platen
210: slurry hole
300: swing arm
400: pressure drive means
500: polishing pressure control device
501: second magnet
502: support frame
503: drive motor
504: sensor
505: thickness detection unit
506: gear
507: LM Guide
800: control unit

Claims (6)

A lower surface on which a rectangular large-area display substrate is mounted and is driven to rotate;
An upper platen which has a circular shape, is located above the lower platen, and drives up and down on the substrate; And
It is located on one side of the upper surface of the upper surface, and a polishing pressure control device for applying pressure to a partial area of the upper surface by magnetic force; includes,
The upper platen,
A polishing pad provided on a lower surface to contact the substrate and for polishing the substrate by frictional force caused by rotation of the lower platen; And
Including; a first permanent magnet provided in the edge region of the upper surface,
The polishing pressure control device,
A second permanent magnet disposed close to an upper portion of the first permanent magnet to generate a repulsive force with the first permanent magnet and having an arcuate shape;
A sensor for sensing a gap between the first permanent magnet and the second permanent magnet;
A support frame for supporting a second permanent magnet; And
A drive motor that is supported by the support frame and adjusts a distance between the first permanent magnet and the second permanent magnet by raising and lowering the support frame; And
A CMP apparatus comprising a; a control unit for receiving the distance data between the first permanent magnet and the second permanent magnet generated by the sensor and controlling the operation of the driving motor accordingly. The method of claim 1,
A CMP apparatus further comprising a; thickness detection unit installed on one side of the lower platen and detecting a thickness of the display substrate in real time. The method of claim 2,
The thickness detection unit,
A CMP device comprising a light emitting unit and a light receiving unit to detect the thickness of a display substrate based on the refractive index of the display substrate. The method of claim 1,
The polishing pressure control device,
A gear connected to the drive motor to convert the rotational motion of the drive motor into a translational motion to raise and lower the support frame; CMP device further comprising. delete delete

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