KR20110022108A - The method of spacer height measurement with parallel plate and apparatus of spacer height measurement with parallel plate - Google Patents

Abstract

PURPOSE: A spacer height measuring apparatus with a parallel plate and a spacer height measuring method using the same are provided to measure the deformation height of a spacer due to pushing power, thereby manufacturing a liquid crystal cell of accurate height. CONSTITUTION: A spacer height measuring apparatus with a parallel plate comprises a substrate portion(100) and a pressure portion(300). A spacer(101) is formed in the substrate portion. The pressure portion presses the substrate portion with fixed pressure. The height of the spacer is measured from physical properties between a parallel plate(302) of the pressure portion and a glass substrate(104) of the substrate portion.

Description

The Method of Spacer Height Measurement with Parallel Plate and Apparatus of Spacer Height Measurement with Parallel Plate}

The present invention relates to a method and an apparatus for inspecting the height of the gap agent attached to a glass substrate while pressing it at a constant pressure by using the original air.

The thickness (Cell Gap) of the liquid crystal layer is determined by the height of the gap agent. If the thickness of the liquid crystal layer is different, the chromaticity and response characteristics of the screen are different, so that the height of the gap agent must be made constant. In addition, since the amount of liquid crystal injection must be varied according to the height of the gap agent, the height of the gap agent must be precisely measured.

Conventionally, the height of the gap agent is measured by using the optical interference method. 1 is a diagram of a conventional measuring device. The gap agent is formed in the substrate portion 100. A red, green, and blue color filter layer 103 is formed on the glass substrate 104, and a black matrix (BM) 102 that absorbs light to prevent light leakage from the boundary of adjacent pixels is the same as the color filter layer. It is formed in the plane. Because of the shape of the gap agent around the gap agent, the liquid crystal alignment may vary and light may leak, and thus the gap agent is formed on the black matrix.

Light emitted from the light source 40 becomes parallel light through the lens 43 and is incident on the interferometric object 200. In the beam splitter 203 of the interferer, light is divided and partly reflected at the reference plane 202 whose surface is very flat, and part is reflected at the surface of the gap agent made in the substrate portion 100 through the beam splitter. Since the phase difference occurs according to the path of the two lights divided at 203, the interference pattern is displayed. This interference fringe is imaged by the CCD 41. When the interference is finely adjusted up and down, only the light passing through the beam splitter is changed in phase so that the shape of the interference fringe is changed. The interference fringe according to the amount of movement of the interferer is analyzed and converted into a three-dimensional image of the gap agent to determine the height of the gap agent. When the light of a light source uses white light mixed with several wavelengths, a more precise shape can be obtained. This method is called White Light Scanning Interfermetry. S & You Precision Co., Ltd. is currently commercially selling equipment for measuring gap height by using white light scanning interference method.

The gap agent is made of acrylic resin, which is cylindrical in shape and usually has a height of 3 μm, and the bottom diameter of the attachment surface is about 20 to 30 μm, and the upper diameter is about 3 to 8 μm smaller than the bottom in terms of exposure characteristics. The one in contact with the BM 102 portion has a larger diameter. In order to maintain the thickness of the liquid crystal layer precisely, there must be an elastic force that deforms according to the pressure of the spacer. In the TFT LCD process, the liquid crystal cell is bonded to the glass substrate of the liquid crystal cell by one touch. In this method, the liquid crystal injection and the two glass substrates are bonded at the same time. In the vacuum, the liquid crystal is dropped on the glass substrate, and the two glass substrates are pressed together by a constant force, and the bonding agent is deformed because of the force. Therefore, since the volume occupied by the entire liquid crystal of the liquid crystal cell depends on the bonding force, the change in the gap height according to the pressing force is an important test item. The pressing force is determined, the height of the gap agent is measured at this pressing force, and the amount of liquid crystal corresponding to the gap height is discharged. However, in the case of using the non-contact measuring method as shown in FIG. 1, since the force cannot be applied to the gap agent and is sensitive to the surrounding vibration, the interference device cannot be moved quickly because the vibration is installed and the price is high and the measurement must be performed without the vibration. This test takes about 10 seconds or more. In the case of inspecting a large substrate, such as a 7th generation or 8th generation TFT LCD production plant, an inspection apparatus is expensive because it requires reducing the overall time required by attaching several optical systems.

The fixing spacer (Column Spacer) is an acrylic resin that has a certain elastic force, and the height varies depending on the pressing pressure. Since a certain pressure is applied to the glass substrate in the process of bonding the liquid crystal cell, it is necessary to measure the height of the fixing type gap agent according to the pressing pressure. Conventionally, since the height of the gap agent is measured by the non-contact method using the optical interference method, the deformation due to the pressing force cannot be detected. In the present invention, by pressing the pressure on the glass substrate at a constant pressure, the distance between the original substrate and the glass substrate by the gap agent, and the electrical characteristics such as optical characteristics or capacitance due to interference and multiple interference between the original substrate and the glass substrate It was then possible to determine the height of the gap agent.

Since the inspection method embodying the present invention can measure the deformation height of the gap agent according to the pressing force, it is possible to precisely make the height of the liquid crystal cell. In addition, the capacitive method and multi-interference are not affected by the surface vibration, and can be quickly measured in less than 1 second, thereby reducing the device configuration ratio.

The present invention introduces a primitive 302 that presses the substrate portion 100 on which the gap agent 101 is formed at a constant pressure. The height of the gap agent is determined by measuring the optical dielectric properties at the air layer interface between the primitive 302 and the glass substrate 104 of the substrate portion.

The degree of primitive is 1λ, λ / 2, λ / 4, λ / 10, λ / 20, λ / 30, which indicates the degree of flatness deviation at a distance of 25.4 mm. The wavelength is 550 nm. The 1λ class is out of flatness by 0.5 μm, the λ / 2 class is about 1.0 μm in wavelength, and the λ / 10 class is 0.05 μm, which is about 10% of the wavelength at 25.4 mm. If the measurement accuracy is 0.01 µm and the measurement area is 10 × 10 mm, the base shall be used with a degree of λ / 20 or more.

2 applies the present invention to a conventional optical interference method. The pressurizing unit 300 has a structure in which the cylinder 302 and the pressurizer 301 are combined. The pressurizer is a part that exerts force on the energy, the simplest of which is a thick glass structure. Since the specific gravity of glass is 2.4, if it is 100mm in size, it receives a force of 24g per cm2. Using hydraulic or pneumatic pressure, you can easily adjust the magnitude of the force. Light emitted from the light source 40 becomes parallel light through the lens 43 and is incident on the interferometric object 200. In the beam splitter 203 of the interferer, the light is divided and partly reflected by the reference plane 202 having a very flat surface, and part of the gap is formed in the substrate part 100 through the beam splitter 203 and the pressing part 300. Reflected from the surface of the agent, since the two light divided by the beam splitter 203 has a phase difference according to the path that passes through, the interference fringes. In the structure shown in FIG. 2, since the three-dimensional shape of a clearance agent does not need to be found out, since it becomes the simple plate structure which the color filter surface 103 and the primitive surface 302 make, the height of this plate becomes the height of a clearance agent. Weighing the pressurizer or increasing the air pressure makes it easier to check the height change of the gap agent.

Using a parallel capacitor as a model, the thickness of the gap agent can be determined by measuring the capacitance. The capacitance C of a capacitor having an area A and a distance d of two electrodes is expressed by the following equation.

ε is the permittivity of the medium between the two electrodes. If the capacitance and the area are known, the distance d between the electrode and the electrode is as follows.

3 is an apparatus diagram of the present invention to which the capacitive method is applied. In FIG. 3, the primitive electrode 303 is formed in the primitive 302 of the pressing unit 300. The color filter electrode 105 is formed on the kali filter layer 103 of the substrate portion 100. The color filter electrode 105 is called a common electrode in the TFT LCD. The measurement accuracy is an important factor of the edge field generated at the edge of the primitive electrode. The range of the edge electric field is usually the separation distance (d) of the two electrodes. Therefore, in order to obtain an accuracy of about 0.1%, the length of the electrode must be about 1000 times larger than the thickness d of the gap agent, which is the distance between the electrodes. At present, the height of the gap agent of the 90-degree TN-type TFT LCD is about 3㎛. When measuring the height of the gap agent with capacitance, the electrode size is made 2 ~ 3mm with 0.1% resolution. The capacitance is measured by connecting the primary electrode and the color filter electrode to the LCD (50).

If the area occupied by the gap agent is usually less than 0.2%, it is ignored, and if it is larger than that, the height of the gap agent is determined by the parallel connection between the two parts of the gap agent and the air layer. If the ratio of the area occupied by the gap agent is x, the thickness d of the gap agent is obtained by the following equation. The area where the two electrodes overlap is A, ε 1 is the permittivity of air and ε 2 is the permittivity of the gap agent.

In the case of the 7th or 8th generation TFT LCDs, the size of the substrate is usually 2 m or more, so a mechanism is required to connect the color filter electrode to the LCD. However, as shown in FIG. 4, if two independent plurality of electrodes 303 and 304 having the same area are formed in the original state, and the two electrodes are capacitively measured by the LC meter 50, there is no need to contact the color filter electrodes. 5 is an equivalent circuit diagram of FIG. 4. 4 is a circuit in which the capacitance C1 of the color filter electrode and the plurality of electrodes 304 and the capacitance C2 of the color filter electrode and the plurality of electrodes 305 are connected in series. In the structure as shown in FIG. 4, it is not necessary to connect the color filter electrode 105. If the area of each of the plurality of electrodes is A, the dielectric constant of the air layer is? 1, and the capacitance measured at the plurality of electrodes is C, the height d of the gap agent is as follows.

The height of the gap agent of the 90 degree TN type TFT LCD is about 3 micrometers. When measuring the height of the gap agent with capacitance, the electrode size is made 2 ~ 3mm with 0.1% resolution.

The capacitive method can measure the gap height very precisely when the gap is formed on the electrode, but cannot be applied when there is no color filter electrode, such as TFT LCD in IPS (In Plane Switch) mode. In this case, the thickness of the boundary surface can be measured by using the interference of light having multiple wavelengths reflected by multiple reflections. 6 is an explanatory diagram showing multiple reflections. The light passing through the pressurizer 301 of the pressurization unit and the air has a large effect of multi-reflection at the interface having a large difference in refractive index. The primary reflection occurs in the air in contact with the air layer, and the first transmitted light is reflected at the interface between the air and the color filter of the substrate. The primary reflected light at each interface passes through multiple transmissions and reflections. The intensity of the reflected light is a function of the wavelength λ.

When the difference between the primary reflected light and the secondary reflected light is λ / 2, it is extinguished. If there is a difference by λ, it is reinforced. By measuring the spectral characteristics of the multi-reflected light, the value of the gap agent can be obtained by comparing the value with the theoretical formula. 7 is a device diagram for checking the height of the gap agent from the spectral characteristics of the multi-reflected light. Use a light source that emits all visible light (380 ~ 800nm). The optical fiber bundle 44 is composed of a plurality of optical fibers having two or more. Part of the optical fiber is used as the passage of incident light from the light source, and part is used as the passage into the spectrometer. In FIG. 7, one of the two optical fiber bundles was used as a passage of the light source and the other as a passage into the spectrometer. The light from the light source is incident on the lens 45 through the optical fiber, and the light is multi-reflected at the interface between the pressurizing portion and the substrate portion, and then passes through the lens to the spectrometer through the optical fiber bundle. 8 is an example of the 4.8 μm spectral characteristics of the height of the gap agent. The larger the wavelength range, the higher the measurement accuracy. It must be refreshed with materials that transmit light from ultraviolet rays, visible light and infrared light. When you make a quartz out of quartz, the wavelength range is wide. If the gap agent is high, the number of buds in FIG. 8 increases, and conversely, the number of buds decreases. In the structure shown in FIG. 7, the measurement is performed with a CCD spectrometer, which takes about several tens of ms. In addition, since the one-time measurement time is short, there is little effect on the vibration.

1 is a diagram of a conventional measuring device.

2 is an apparatus diagram of the present invention to which the phase method is applied.

3 is an apparatus diagram of the present invention to which the capacitive method is applied.

4 is an apparatus diagram of the present invention to which the capacitance method in which the electrode of the substrate portion is floated is applied.

5 is an equivalent circuit diagram of FIG. 4.

6 is an explanatory diagram showing multiple reflections in parallel planes.

7 is an apparatus diagram of the present invention to which spectroscopy is applied.

8 is an example of spectral characteristics.

<Brief description of the major symbols in the drawings>

100: substrate portion 101: gap agent 102: Black Matrix

103: color filter layer 104: glass substrate 105: color filter electrode

200: interferer 201: lens 202: reference plane

203: beam splitter 300: pressurizing unit 301: pressurizer 302: primitive

303: primitive electrode 304, 305: plural primitive electrode 40: light source

41 CCD 42 Lens 43 Lens 44 Optical fiber bundle

45 lens 46 reflector 50 LCR meter

Claims (12)

It is provided with the board | substrate part 100 in which the clearance agent 101 is formed, and the press part 300 which presses a board | substrate part by a constant pressure, and measures the physical characteristic between the base 302 of a press part and the glass substrate 104 of a board part. Test method to find the height of the gap agent. The inspection method according to claim 1, wherein the height of the gap agent is determined from the phase difference between the interface between the interferometric object and the primitive 302 and between the interface of the air layer between the interferometric object and the glass substrate. The inspection method according to claim 1, wherein the height of the gap agent is determined by measuring the capacitance between the primitive (302) and the glass substrate (104). The inspection method according to claim 1, wherein the height of the gap agent is determined from spectral characteristics due to multiple reflections occurring at the interface between the primitive (302) and the glass substrate (104). It is provided with the substrate part 100 in which the clearance agent 101 is formed, and the press part 300 which presses a board | substrate part by a constant pressure, and measures the physical characteristic between the base 302 of a press part and the glass substrate 104 of a board part. Inspection device to find out the height of the gap agent. 6. The inspection apparatus according to claim 5, wherein the height of the gap agent is determined from the phase difference between the interferometric object and the air interface boundary between the primitive 302 and the glass substrate. 6. An inspection apparatus according to claim 5, wherein the height of the gap agent is determined by measuring the capacitance between the primitive 302 and the glass substrate 104 of the substrate portion. 8. The inspection apparatus according to claim 7, wherein the electrode of the substrate portion is floated and the height of the gap agent is determined by measuring the capacitance between the two electrodes of the pressing portion. The inspection apparatus according to claim 8, wherein the length of the electrode is between 2 and 3 mm. 6. The inspection apparatus according to claim 5, wherein the height of the gap agent is determined from the spectroscopic characteristics due to multiple reflections occurring at the interface between the primitive (302) and the glass substrate (104). 11. The inspection apparatus according to claim 10, wherein the primitive is quartz. The inspection apparatus according to claim 10, comprising a plurality of optical fibers having two or more optical fibers, a portion of which is used as a passage of incident light from the light source and a portion of which is used as a passage of the light receiving portion.

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