JP2005275345A - Liquid crystal substrate holding disk and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal substrate holding disk which less reflects regularly reflected light on its surface and has high precision even when made large sized. <P>SOLUTION: The liquid crystal substrate holding disk which has a support surface holding a translucent or translucent liquid crystal substrate on the top surface of a base body and a non-support surface lowered below the support surface is formed of black ceramics of ≥80 GPa cm<SP>3</SP>/g in specific rigidity as the base body and the arithmetic mean roughness of the support surface is 0.3 to 1.2 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal substrate holder such as an exposure apparatus for manufacturing a liquid crystal display, and in particular, a liquid crystal that does not impair the accuracy of exposure, alignment, or focus adjustment due to reflection of illumination light transmitted through a transparent or translucent liquid crystal substrate. The present invention relates to a substrate holder and a method for manufacturing the same.

  Conventionally, a liquid crystal substrate holding disk used in an exposure apparatus for manufacturing a liquid crystal display has a base material made of an aluminum-based metal anodized, a base material made of stainless steel, anodized ceramic, or an anodized ceramic. A material in which a material such as TiC was coated was used.

  FIG. 6A is a perspective view showing a schematic view of a chuck which is an example of a conventional liquid crystal substrate holding disk.

  Conventionally, as shown in FIG. 6A, the liquid crystal substrate holder 11 has a support surface 12 for holding the transparent or translucent liquid crystal substrate 6 on the upper surface of the base 14 and an unsupported lower than the support surface 12. The liquid crystal substrate 6 is held, and illumination light for exposure or illumination light is applied for alignment or focus adjustment. And since a part of illumination light irradiated to the liquid crystal substrate 6 permeate | transmits the liquid crystal substrate 6, and reaches | attains the liquid crystal substrate holding | maintenance board 11, in order to suppress reflection of irradiation light as much as possible, the support surface 12 is formed. As a result, the area of the liquid crystal substrate holding plate 11 in contact with the liquid crystal substrate 6 is reduced, and most of the irradiation light is reflected by the surface of the non-supporting surface 12 of the liquid crystal substrate holding plate 11.

  Since these liquid crystal substrate holders 11 are required to be held with high accuracy over time, generally, ceramics having high rigidity are frequently used. In particular, black ceramics have been used for the liquid crystal substrate holding plate 11 mounted on an exposure apparatus for manufacturing a liquid crystal display.

An example is shown in FIG. FIG. 6B is an enlarged cross-sectional view of a part of the liquid crystal substrate holding disk of FIG. As shown in the figure, a coating layer 17 made of ceramic is formed on the surfaces of the support surface 12 and the non-support surface 13, and more specifically, the reflectance of the substrate 14 having a roughened surface. A first coating layer (not shown) made of low SiC and a second coating layer (not shown) made of a transparent material Al ₂ O ₃ having a smooth surface on the first coating layer. (See Patent Document 1).

  By the way, as a method for lowering the reflectance described above, generally, the color of the ceramic forming the liquid crystal substrate holding plate 11 is black, which absorbs light more easily than white or milky white ceramics that easily reflect light. Although it is known that the ceramics to be exhibited are suitable, alumina that is particularly inexpensive and low in processing cost has been desired.

As an example of alumina exhibiting black color, Patent Document 2 discloses a black alumina sintered body containing Al ₂ O ₃ as a main component and components of Mn ₂ O ₃ , Fe ₂ O ₃ , CoO, and Cr ₂ O _3. Proposed. Patent Document 3 proposes a black low thermal expansion ceramic sintered body containing 0 to 2.5% by weight of Li ₂ O. Furthermore, Patent Document 4 proposes a colored ceramic containing Al ₂ O ₃ as a main component and containing Fe ₂ O ₃ , Co ₂ O ₃ , and CuO components.
Japanese Patent Laid-Open No. 5-205997 JP-A-5-238810 JP 2001-19540 A JP-A-5-254922

  However, if a part of the illumination light incident on the liquid crystal substrate 6 is reflected by the surface of the liquid crystal substrate holding plate 11 and enters the specific portion of the liquid crystal substrate 6 again, an unnecessary portion of the resist that is not etched is exposed. Then, the accuracy of alignment and focus adjustment is lowered, or the irradiated light is transmitted through the liquid crystal substrate 6 and reflected by the surface of the liquid crystal substrate holding plate 11, and the same image as the exposed image is seen from the lower surface of the liquid crystal substrate 6. There has been a problem that adverse effects such as double exposure occur due to the irradiation. In particular, since the liquid crystal substrate 6 is transparent or translucent glass, incident light is easily transmitted.

  Therefore, there has been a demand for a liquid crystal substrate holding plate 11 having a low reflectance that does not expose unnecessary portions of the resist due to reflection of illumination light transmitted through the liquid crystal substrate 6.

  Here, reflection of light refers to a phenomenon in which a traveling wave of light changes its direction on a medium different from the ongoing medium or a boundary surface with a discontinuous change, and proceeds in a new direction in the original medium. Reflection with the same angle and reflection angle is called regular reflection (or specular reflection). Further, if the unevenness of the boundary surface is about the same as or larger than the wavelength, the reflected wave travels in various directions. Such reflection is called diffuse reflection (or irregular reflection). The percentage of the intensity of the reflected wave at the boundary with respect to the incident wave intensity is called reflectance (regular reflectance, diffuse reflectance), and the value obtained by combining the regular reflectance and diffuse reflectance is called reflectance.

  By the way, Patent Documents 2 and 4 using black alumina do not refer to the low reflectance as described above, and even if black alumina is simply adopted, with the recent increase in size of liquid crystal displays, Depending on the surface condition, there is a problem that the reflection is not sufficiently low and double exposure cannot be prevented.

  This is probably due to the following reasons. That is, with the recent increase in size of the liquid crystal display, the liquid crystal substrate 16 is increased in size, and the region of the non-support surface 13 is larger than the support surface 12 in the manufacturing process using the liquid crystal substrate holder 11. Therefore, diffuse reflection is a major part of the reflection. Here, it is conceivable to reduce the reflectance by reducing the diffuse reflection, which occupies most of the reflection by using the surface of the liquid crystal substrate holding plate 11 as a mirror surface to make the reflection low, but the diffuse reflection is lowered in this way. However, since the irradiation light transmitted through the liquid crystal substrate 6 is close to the support surface 12 of the liquid crystal substrate holding plate 11 which is a mirror surface, it becomes easy to irradiate the lower surface of the liquid crystal substrate 6 with light by regular reflection. Thus, even if the diffuse reflection is lowered than before, double exposure is likely to occur. In other words, it is the specular reflection light that overlaps the same image that has the most influence on double exposure, and the problem is what surface state should be selected to reduce this specular reflection light. It was.

On the other hand, the material properties of the ceramics of Patent Document 3 are Young's modulus of 165 GPa or less and specific rigidity of 68.5 GPa · cm ³ / g or less. The substrate 14 used for the liquid crystal substrate holding plate 11 of the exposure apparatus includes: In many cases, complicated processing such as mounting holes and grooves in other members is performed, and it is necessary to support the liquid crystal substrate 6 for the purpose of preventing deformation of the material when performing machining processing or the like. When the specific rigidity is low, there is a problem that high-precision machining is difficult.

  Further, in Patent Document 1 in which the coating layer 17 is formed on the surface, the support surface 12 is difficult to flatten and cannot be finished with high precision, and internal stress is generated due to heat at the time of coating, causing peeling. There was a problem to do. Furthermore, the apparatus for coating the peritoneum 17 is also large, and there is a problem that there are restrictions on facilities.

  Therefore, the present invention has been made in view of the problems to be solved by the above-described technology. Unnecessary portions of the resist are exposed by the reflection of the illumination light transmitted through the liquid crystal substrate 6 to perform alignment and focus adjustment. An object of the present invention is to provide an inexpensive and large-sized liquid crystal substrate holding plate capable of high-accuracy processing capable of preventing double exposure without reducing accuracy.

In order to solve the above-mentioned problems, a liquid crystal substrate holding disk according to the present invention has a support surface for holding a transparent or translucent liquid crystal substrate on the upper surface of the substrate and a non-support surface that is lower than the support surface. The board is characterized in that the substrate is made of black ceramics having a specific rigidity of 80 GPa · cm ³ / g or more, and the arithmetic average roughness of the support surface is in the range of 0.3 to 1.2 μm.

Further, the substrate is formed of alumina containing any one or more of TiO ₂ , CoO, MnO ₂ , and Fe ₂ O ₃ .

  Furthermore, the liquid crystal substrate holding disk of the present invention is characterized in that the arithmetic average roughness of the non-supporting surface is in the range of 1.0 to 2.0 μm.

  Furthermore, the liquid crystal substrate holding disk of the present invention is characterized in that the alumina has a purity of 90% or more.

  Next, according to the method for manufacturing a liquid crystal substrate holding disk of the present invention, a base made of black ceramics is prepared, and the upper surface of the base is finished so that the arithmetic average roughness is in the range of 0.6 to 1.2 μm. A feature is that a supporting surface and a non-supporting surface for holding a transparent or translucent liquid crystal substrate are formed by processing.

According to the configuration of the present invention, since the specific rigidity of the substrate is formed of black ceramics having 80 GPa · cm ³ / g or more and the arithmetic average roughness of the support surface is in the range of 0.3 to 1.2 μm. Even a large LCD substrate holder can be processed with high accuracy by preventing deformation of the material during processing, and also effectively prevents regular reflection of irradiation light transmitted through the liquid crystal substrate and lowers reflectivity. Therefore, it is possible to prevent double exposure in which irradiation light is generated on the liquid crystal substrate.

Further, the substrate by forming alumina which contains _TiO 2, CoO, MnO _2, or any one or more of _Fe 2 _{O 3,} it is possible to obtain a substrate of a black regular reflectance is low irradiation light . In order to realize a low reflectance, a black substrate can be used to absorb light as much as possible.

  Furthermore, since the arithmetic average roughness (Ra) of the non-support surface is in the range of 1.0 to 2.0 μm, not only the contact surface of the liquid crystal substrate but also the other surface has a low regular reflectance. A board can be provided.

  Furthermore, when the alumina has a purity of 90% or more, a substrate having high strength and high specific rigidity can be obtained, and high-precision processing can be performed.

  Next, a substrate made of black ceramics is prepared, and the upper surface of the substrate is finished so that the arithmetic average roughness is in the range of 0.3 to 1.2 μm, and then a transparent or translucent liquid crystal substrate is held by blasting. By providing a manufacturing method of a liquid crystal substrate holding disk characterized by forming a supporting surface and a non-supporting surface, a liquid crystal substrate holding disk having a low regular reflectance, high accuracy and capable of accommodating a large-sized product is provided. be able to.

  Hereinafter, the best mode for carrying out the present invention will be described.

  1A and 1B are schematic views of a chuck which is an example of a liquid crystal substrate holding plate according to the present invention. FIG. 1A is a perspective view thereof, and FIG. 1B is an enlarged cross-sectional view of a part of the liquid crystal substrate holding plate. Each figure is shown. FIG. 2 is an enlarged perspective view showing a part of the support portion of the liquid crystal substrate holding disk according to the present invention.

The liquid crystal substrate holding disk 1 of the present invention comprises a flat substrate 4 made of black ceramics having a specific rigidity of 80 GPa · cm ³ / g or more, and a plurality of protrusions 200 are formed on the surface thereof. Reference numeral 200 denotes a support surface 2 that contacts and supports the liquid crystal substrate 6, and a non-support surface 3 that is lower than the support surface 2.

  By the way, in the liquid crystal substrate holding plate 1 of the present invention, when the liquid crystal substrate 6 is supported on the surface and the exposure is performed from the upper side, the reflectance is lowered without reducing the accuracy of alignment or focus adjustment. It is also considered preferable in terms of preventing double exposure. Accordingly, it is known that the reflectance of the liquid crystal substrate holding plate 1 should be reduced by using a black surface, but double exposure is performed in the manufacturing process of the liquid crystal substrate 6 simply by reducing the reflectance. It is difficult to prevent. On the other hand, in this invention, double exposure can be prevented by making arithmetic mean roughness (Ra) of the surface of the support surface 2 into the range of 0.3-1.2 micrometers.

  The reason for reaching the present invention will be described below.

  Here, according to the liquid crystal substrate holding disk 1 of the present invention, since the area of the non-supporting surface 3 is larger than the support surface 2 of the surface supporting the liquid crystal substrate 6, the light irradiated from above the liquid crystal substrate 6 is used. When the diffuse reflectance and the regular reflectance on the surface of 1 are compared, the ratio of the diffuse reflectance is higher than that of the regular reflectance, and most of the reflection is diffuse reflection. Therefore, the diffuse reflectance accounts for the majority of the reflectance. It will be. Therefore, at first glance, it seems that the reflectance can be reduced by suppressing the reflectivity by making the surface difficult to cause irregular reflection.

  However, as a result of earnest examination of the problem of double exposure in the manufacturing process of the liquid crystal substrate 6 using the liquid crystal substrate holding plate 1, the present inventors have dominantly reflected light as the cause of double exposure. On the contrary, the diffuse reflection light attenuates while passing through the liquid crystal substrate 6 and the image is blurred even if it is reflected, and it is found for the first time that it does not become an abnormal light that exposes the resist. The arithmetic mean roughness (Ra) of the surface 2 is set in the range of 0.3 to 1.2 μm, and the present invention has been achieved to suppress double reflection by suppressing regular reflection light.

  Therefore, when the arithmetic average roughness (Ra) is a value smaller than 0.3 μm, the regular reflectance at which the irradiated light returns vertically becomes high, which causes double exposure to the liquid crystal substrate 6. On the contrary, when the arithmetic average roughness is larger than 1.2 μm, the surface of the liquid crystal substrate 6 in contact with the support surface 2 may be damaged, and the value of the liquid crystal substrate 6 as a product is impaired. End up. Therefore, the arithmetic average roughness (Ra) of the support surface 2 needs to be in the range of 0.3 to 1.2 μm, and preferably in the range of 0.6 to 1.0 μm.

  As the irradiation light used for the exposure to the liquid crystal substrate 6, irradiation light in the ultraviolet region is often used, and in general, it may be considered in the wavelength region of the ultraviolet region of 400 nm or less. Irradiation light in the wavelength range up to 4 nm may be included, and it is desired that the regular reflectance is 1% or less with irradiation light of 450 nm or less, and double exposure does not occur in the liquid crystal substrate 6.

  And the formation method of the support surface 2 and the non-support surface 3 should just be formed by grinding processing or blast processing, and finishes the arithmetic mean roughness (Ra) in the range of 1-2 micrometers by making the surface into a rough state. The surface can be used. Within this range, even if the reflected light is reversely applied to the back surface of the liquid crystal substrate, the resist film on the wafer surface is exposed and does not hinder alignment or focus adjustment.

  By the way, when the arithmetic average roughness (Ra) is a value larger than 2 μm, it is necessary to make the abrasive grains coarse and large, but in this case, the mask pattern at the time of blasting cannot be made fine. And the pattern was broken. On the other hand, when the arithmetic average roughness (Ra) is smaller than 1 μm, it is necessary to make the abrasive grains of the blast fine, so that there is a problem that it takes a long time to process, or the surface is too good. Since the reflectance of the reflected light increases, there is a concern about double exposure. Therefore, the abrasive grains used for blasting may be in the range of # 200 to # 1000, and the surface of the non-supporting surface 3 obtained as a result is 1.0 to 2.0 μm in terms of arithmetic average roughness (Ra). It is preferable that the surface is not subjected to polishing with loose abrasive grains.

  As described above, when the arithmetic average roughness (Ra) is low, the regular reflectance is high, but the diffuse reflectance can be lowered, but most of the total reflection is diffuse reflection, and the diffuse reflectance is reflected. The rate will be decided. Therefore, it does not concentrate on a specific part, but the reflection is blurred overall.

  As a result, it is not necessary to cover the surface of the liquid crystal substrate holding disk 1 including the support surface 2 processed with high accuracy, so that the accuracy of the coating film is deteriorated, and the defect due to the peeling of the coating film is caused. Thus, the flatness of the liquid crystal substrate 6 adsorbed on the liquid crystal substrate holding plate 1 can be held while being supported with high accuracy.

  By the way, the substrate 4 forming the liquid crystal substrate holding disk 1 of the present invention is required to be black ceramics. The black type of black ceramics indicates a dark color close to black, brown or brown. , Reddish brown, green brown, ultramarine blue, red bean color, etc. may be used. The thing of the color tone which exhibits black is preferable.

As the black system, the L ^* a ^* b ^* color system that is most widely used for color difference measurement in color management in the Japanese industrial field may be used. Here, it is preferable to use the color tone of the black ceramic used in the present invention having a lightness index in the above L ^* a ^* b ^* color system in the range of L ^* <60. If the lightness index is in a range where L ^* is larger than 60, the reflectivity is high, and even in the configuration of the present invention, it is affected by the reflection from the non-supporting surface 3 and is totally blurred. Become a statue. Therefore, more preferably, the brightness index is in the range of L ^* <40.

In the L ^* a ^* b ^* color system, L ^* indicates a lightness index, that is, the degree of brightness perception, and a ^* and b ^* are perceptual chromaticity indices, that is, two attributes of hue and saturation. It shows the attributes of visual perception that are considered together. Hue a ^* and b ^* not very relevant to the factors influencing the reflectance, it is known that it affects the most a lightness index L ^*, what is the lightness index L ^* It is sufficient to pay attention to whether the value is a value, and since the dependence of the perceptual chromaticity index of a ^* b ^{* in} that case is low, it can be understood that the color tone may be close to that of black.

In the present invention, tristimulus values are measured according to JIS K 5600-4-5 using a color difference gloss meter (Σ90) manufactured by Nippon Denshoku Co., Ltd., and CIE 1976 (L ^* , a ^* , b ^* ) color. Calculate the color coordinates of the space.

  In addition, since there is no material to compare this time, it conformed to the following JIS K 5600-4-5.

L ^* : Index representing lightness (0 to 100). 0 is the darkest value and 100 is the brightest value a ^* : red is on the + side, green is on the-side, 0 is an achromatic color, and the saturation is higher as the absolute value is larger b ^* : yellow is on the + side The minus side represents blue, 0 represents an achromatic color, and the greater the absolute value, the higher the saturation. The liquid crystal substrate holding disk 1 of the present invention preferably has an alumina purity of 90% or more. If the alumina purity is less than 90%, the rigidity is impaired. In order to achieve a specific rigidity of 80 GPa · cm ³ / g or more, the Young's modulus is preferably 310 GPa or more, and in order to achieve these, the alumina purity is preferably 90% or more.

  Note that the liquid crystal substrate 6 supported by the liquid crystal substrate holding plate 1 is adsorbed thereto by a known adsorbing means. For example, when used in the atmosphere, the liquid crystal substrate 6 can be sucked by vacuum suction. Alternatively, it may be simply placed and the liquid crystal substrate is mechanically attached and held.

  Next, the manufacturing method of this invention is demonstrated.

First, SiO ₂ , MgO or the like conventionally used as a sintering aid is added to 90% by weight or more of Al ₂ O ₃ , and in order to further blacken, Fe ₂ O ₃ , MnO ₂ , CoO, TiO ₂ are added. After mixing and pulverizing in a wet manner, spray drying and granulation are performed using a spray dryer to produce a secondary material. The obtained secondary raw material is molded into a desired shape at a pressure in the range of 80 to 200 MPa by CIP molding or mechanical press molding.

  Next, alumina ceramics are obtained by firing in an oxidizing atmosphere so that the maximum temperature is in the range of 1400 to 1700 ° C. Then, after forming the plate-like body of the base body 4, the upper surface is finished to an arithmetic average roughness in the range of 0.3 to 1.2 μm, and then a supporting surface for holding the transparent or translucent liquid crystal substrate 6 by blasting. 2 and the non-supporting surface 3 are formed.

  Each support surface 2 that is a surface that reflects illumination light is processed with high accuracy by grinding or lapping polishing, and the non-support surface 3 other than the support surface 2 can be roughened by grinding or blasting.

By the way, the black ceramics forming the substrate 4 is preferably formed from alumina containing TiO ₂ , CoO, MnO ₂ , and Fe ₂ O ₃ , and the alumina purity is 90% or more. It is formed by adding known SiO ₂ , MgO or the like conventionally used as a sintering aid. As preferable ranges, Fe ₂ O ₃ is 0.5 to 1.0% by weight, MnO ₂ is 4.0 to 5.5% by weight, CoO is 1.0 to 2.0% by weight, and TiO ₂ is 0.0% by weight. What is necessary is just to mix 5 to 1.0 weight%.

  As a result, the obtained alumina becomes black ceramics, and much of the illumination light transmitted through the liquid crystal substrate can be absorbed by the black surface with low reflectivity.

  Furthermore, the purity of alumina is desirably 90% or more. If the purity is less than 90%, the Young's modulus is lowered, and the surface accuracy as the liquid crystal substrate holding disk 1 cannot be maintained. In particular, the specific rigidity (Young's modulus / specific gravity) is an important factor in the liquid crystal substrate holder 1, and the specific rigidity becomes a value smaller than 80 GPa · cm 3 / g, and the design is increased as the liquid crystal substrate holder 1 becomes larger. It is not preferable. Since the alumina purity is 90% or higher and the material has a high specific rigidity, even if the support surface 1 is a liquid crystal substrate holding plate 11 having a size of □ 600 mm or more, for example, the flatness thereof is highly accurate to 10 μm or less. It can be finished.

  By the way, according to the material having the above composition, a material having a high mechanical strength such as a Young's modulus of 300 to 350 GPa, a Vickers hardness (HV1) of 12 to 14 GPa, and a three-point bending strength of 300 to 350 MPa can be obtained.

  Further, a dense alumina having a void occupancy of 4% or less, an average void diameter of 4 μm, and an apparent density of 3.8 to 3.9 g / cm 3 can be obtained. Here, if the void occupancy is 4% or less, the probability that the light wave incident by the void is reflected in various directions becomes low, and the diffuse reflectance can be reduced. Moreover, the same thing becomes possible, so that an average void diameter becomes small. Furthermore, it is preferable that the apparent density falls within the above range. If the apparent density is larger than the above range, the specific rigidity is lowered. If the apparent density is smaller, the Young's modulus is lowered, and the specific rigidity is similarly reduced.

  Further, the liquid crystal substrate holding disk 1 of the present invention may have any shape as long as it is suitable for holding the liquid crystal substrate 6 regardless of the shape of a disc or a square plate.

  Examples of the present invention will be described below.

(Experimental example 1)
In order to make the 91% by weight Al ₂ O ₃ powder black, Fe ₂ O ₃ : 0.7% by weight, MnO ₂ : 4.7% by weight, CoO: 1.6% by weight, TiO ₂ : 0.8 Weight percent of each powder was added as a sintering aid, and SiO ₂ and MgO were further added and mixed in a wet manner, followed by spray drying using a spray dryer. Then, after mixing and pulverizing in a wet state, spray drying and granulation are performed using a spray dryer to produce a secondary raw material. The obtained secondary raw material was molded into a plate-like body at a pressure of 80 MPa by CIP molding.

Next, after firing in an oxidizing atmosphere at 1430 ° C. to obtain an alumina sintered body, a φ30 mm × 8 mm disk is manufactured. The surface of the disk was finished into four types of arithmetic average roughness (Ra) of 0.12 μm, 0.33 μm, 0.63 μm, and 1.30 μm to form a liquid crystal substrate holding disk. The finished liquid crystal holding plate had a lightness index L ^* of 45.86, a ^* of −0.61, and b ^* −0.64 in the L ^* a ^* b ^* color system.

  And each was irradiated with the light of 360 nm-740 nm, and the reflectance and diffuse reflectance were measured. A numerical value obtained by subtracting the diffuse reflectance from the reflectance was calculated as the regular reflectance.

  The results are shown in FIGS. FIG. 3 shows reflectance data for various arithmetic average roughnesses (Ra), FIG. 4 shows diffuse reflectance data, and FIG. 5 shows regular reflectance data.

  Arithmetic average roughness (Ra) 0.12 μm, 0.33 μm, and 0.63 μm were finished by lapping and 1.30 μm was finished by blasting, respectively.

  By the way, these reflectances may be measured in a wavelength range of 360 nm to 740 nm by using a spectrocolorimeter CM-3700d apparatus manufactured by Minolta.

  From the above results, it was found that the regular reflectance can be reduced to 1% or less in the wavelength region of 450 nm on the surface having an arithmetic average roughness (Ra) of 0.4 μm or less.

Further, if the alumina is manufactured by the same manufacturing method as this Lot, the material has a Young's modulus of 314 GPa, a three-point bending strength of 324 MPa, a Vickers hardness (Hv1) of 12.7 GPa, and an apparent density of 3.86 g / cm ³ . The characteristics were obtained, and the specific rigidity was 81.3 GPa · cm ³ / g, and a material capable of high-precision machining could be obtained.

1A and 1B are schematic views of a chuck which is an example of a liquid crystal substrate holding plate according to the present invention, in which FIG. 1A is a perspective view and FIG. 2B is an enlarged cross-sectional view of a part of the liquid crystal substrate holding plate. ing. It is a perspective view which expands and shows a part of support part of the liquid crystal substrate holding | maintenance board based on this invention. It is a graph which shows the measurement data of the reflectance by the base | substrate of this invention. It is a graph which shows the measurement data of the diffuse reflectance by the base | substrate of this invention. It is a graph which shows the measurement data of the regular reflectance by the base | substrate of this invention. It is a figure which shows the schematic of the chuck | zipper which is an example of the conventional liquid crystal substrate holding | maintenance board, (a) is the perspective view, (b) has shown sectional drawing to which a part of said liquid crystal substrate holding board was expanded, respectively. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 ... Liquid crystal substrate holding disk 2, 12 ... Support surface 3, 13 ... Non-support surface 4, 14 ... Base | substrate 5 ... Liquid crystal substrate holding device 6 ... Liquid crystal substrate 17 ... Coating layer

Claims (5)

In a liquid crystal substrate holder having a support surface for holding a transparent or translucent liquid crystal substrate on the upper surface of the substrate and a non-support surface that is lower than the support surface, the specific rigidity of the substrate is 80 GPa · cm ³ / g or more. A liquid crystal substrate holding plate formed of black ceramics and having an arithmetic average roughness of the support surface in a range of 0.3 to 1.2 μm. _2. The liquid crystal substrate holding disk according to claim 1, wherein the substrate is made of alumina containing at least one of TiO ₂ , CoO, MnO ₂ , and Fe ₂ O ₃ . 3. The liquid crystal substrate holding disk according to claim 1, wherein the arithmetic average roughness (Ra) of the non-supporting surface is in a range of 1.0 to 2.0 μm. The liquid crystal substrate holder according to any one of claims 1 to 3, wherein the alumina has a purity of 90% or more. A base made of a black ceramic is prepared, and the upper surface of the base is finished to have an arithmetic average roughness in the range of 0.3 to 1.2 μm, and then a supporting surface for holding a transparent or translucent liquid crystal substrate by blasting; A method of manufacturing a liquid crystal substrate holding disk, wherein a non-supporting surface is formed.

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