KR20180100485A - Glass substrate for display - Google Patents

Abstract

The present invention provides a glass substrate for display in which occurrence of rubbing non-uniformity is suppressed. A liquid crystal device (1) has a structure in which two glass substrates (2) including a silicate glass face each other and a liquid crystal (30) is sealed between facing surfaces. The glass substrates (2) supply a slurry of cerium oxide and the glass substrates (2) are manufactured through a polishing step S1 for polishing surfaces of the glass substrates (2) with a polishing pad, a first cleaning step S2 for brushing the surfaces of the glass substrates (2) with a disc brush while supplying the slurry, and a second cleaning step S3 for washing the surfaces of the glass substrates (2) using a detergent. By this process, the amount of Ce in first main faces (11, 21) of the glass substrates (2) can be suppressed to 0.1 atm% or less, and the rubbing non-uniformity and a bright defect can be suppressed.

Description

[0001] GLASS SUBSTRATE FOR DISPLAY [0002]

The present invention relates to a glass substrate for a display.

The liquid crystal device is manufactured by stacking two glass substrates and sealing the liquid crystal between the glass substrates. For example, a thin film transistor is arranged in a matrix on one of the glass substrates, a color filter is arranged on the other glass substrate, and optical characteristics of the liquid crystal layer sealed between the two glass substrates are changed in accordance with the image signal, Thereby enabling image display. It is known that rubbing rollers are rotated while rotating the rubbing rollers on the surfaces contacting with the liquid crystal layer on the opposite surfaces of the glass substrates produced in the respective steps, but rubbing unevenness occurs at that time (see Patent Document 1).

Japanese Patent Application Laid-Open No. H07-338990 (Patent Document 1) discloses an image forming apparatus in which a rubbing cloth, a rubbing roller wound around a rubbing cloth, driving means for driving the rubbing roller, and a contact surface of the rubbing cloth are rough, And a regenerating roller including a porous material such as ceramics. The rubbing device removes foreign matters adhering to the rubbing cloth, thereby reducing the frequency of cleaning and providing a long-lasting rubbing device.

Japanese Patent Application Laid-Open No. 2007-86669

Patent Document 1 focuses on a foreign substance attached to a rubbing cloth and removes foreign matter to remove rubbing unevenness. In the rubbing process, when the liquid crystal display is actually used for a certain reason, rubbing unevenness occurs in which irregularities such as stripe images of several millimeters are bright or dark. Patent Literature 1 is a reason for the reason that the reason for this is that the rubbing, the unevenness of strength, and the foreign matter become the main cause of rubbing. However, according to the study by the present inventors, it has been found that rusting unevenness can be suppressed by improving the surface property of the glass substrate.

The present invention provides a glass substrate for display in which occurrence of rubbing unevenness is suppressed.

A glass substrate for a display according to the present invention is a glass substrate for a display comprising a silicate glass and has a first main surface and a second main surface opposite to the first main surface, 0.1 atm% or less.

According to the present invention, it is possible to suppress the rubbing non-uniformity of the first main surface of the glass substrate for display and suppress the defective spots.

1 is a cross-sectional view showing an example of a liquid crystal device using a glass substrate for a display according to the present invention.
2 is a flowchart showing a manufacturing process of a glass substrate for a display according to the present invention.
Fig. 3 shows the XPS analysis results of the glass substrate for display according to the present invention. Fig. 3 (a) is a table of rubbing nonuniformity evaluation for the amount of Ce, Fig. 3 (b) -AT failure rate.
4 (a) is a table for evaluating rubbing nonuniformity with respect to the value of (Ce + La) / Si, and FIG. 4 (b) ) / Si and the incidence of defective spot defects.
5 is a graph showing the correlation between the O / Si value and the nanoindenter indentation hardness of the glass substrate for a display according to the present invention.
Fig. 6 is a table for evaluating the rubbing nonuniformity and the defective spot defect rate, the value of the O / Si value and the nanoindenter indentation hardness of the glass substrate for display according to the present invention.

Hereinafter, a specific embodiment of the glass substrate for display according to the present invention will be described in detail with reference to the drawings.

≪ Glass substrate for display >

1 is a cross-sectional view showing an example of a liquid crystal device using a display glass substrate (hereinafter, simply referred to as a glass substrate) according to the present embodiment. Also, the lower side of the paper is the front side of the display.

The liquid crystal device 1 has a structure in which two glass substrates 2 including silicate glass are faced and the liquid crystal 30 is sealed between facing surfaces. The two glass substrates 2 are defined as a first glass substrate 10 and a second glass substrate 20 and the facing surfaces are defined on the first main surfaces 11 and 21 and the first main surfaces 11 and 21 And the opposing surfaces are defined as the second main surfaces 12 and 22. [

A thin film transistor (hereinafter referred to as a TFT) 31 is arranged in a matrix on the first main surface 11 of the first glass substrate 10 and a thin film transistor On the first main surface 21, a color filter 32 is arranged. That is, each of the first main surfaces 11 and 21 is also a device formation surface for forming a wiring layer.

Then, an orientation film 33 is formed on each of the first main faces 11 and 21 to perform rubbing treatment for determining the arrangement of liquid crystal molecules when no voltage is applied. The rubbing treatment is to form a fine groove on the surface of the alignment film 33 to make the alignment anisotropic film, and the alignment of the liquid crystal molecules can be defined by rubbing the alignment film 33 in a predetermined direction.

Then, the first main faces 11 and 21 are bonded to each other by using a seal portion, and the liquid crystal 30 is sealed from the notched portion of the seal portion while performing alignment. A polarizing plate 34 is provided on each of the second main surfaces 12 and 22 to manufacture the liquid crystal device 1. [

The glass substrate 2 of the present embodiment is a silicate glass. In particular, since for the glass substrate 2 of this embodiment is TFT, an alkali oxide is more than 0.1% by mass percent representation of the oxide basis, of silicon dioxide (SiO _2), aluminum oxide (Al ₂ O _3), boron oxide It is preferably an alkali-free glass having as its main component an alkaline earth metal oxide such as BaO, CaO, or B ₂ O ₃ . The alkali-free glass is an example of a glass composition, and it is a glass as a percentage of mass expressed on an oxide basis. The glass contains 55 to 70% of SiO ₂ , 10 to 20% of Al ₂ O ₃ , 0 to 5% of B ₂ O ₃ , 0 to 5%, CaO: 3 to 15%, SrO: 0.5 to 7%, and BaO: 5 to 15%.

In the glass substrate 2 of the present embodiment, the amount of Ce is 0.1 atm% or less in the first main surface. Thereby, occurrence of rubbing unevenness can be suppressed. The reason for this is considered to be that the Ce-containing gelated silica layer and / or the slurry residue (Ce) at the time of polishing or cleaning, which may cause the rubbing unevenness, are small in the first main surface. The amount of Ce in the first main surface is obtained by XPS analysis.

Here, the "Ce-containing gelatinous silica layer" is generated when cerium oxide is used in the polishing process (S1 described later), which is a manufacturing process of the glass substrate 2, or the cleaning process (S2 or S3 described later). Ce is replaced with silica (Si) in the glass substrate 2, the silica is eluted from the glass substrate 2, and the eluted silica forms Si-O on the surface of the glass substrate 2, Refers to a layer leaving H ₂ O in the skeleton.

"Residue of slurry" is generated when cerium oxide is used in the polishing process or the cleaning process, which is a process of manufacturing the glass substrate 2. Cerium oxide may react with the glass component, and the particles remain on the surface as they are as particles.

Hereinafter, the Ce-containing gel-like silica layer may be referred to as an inorganic residue by incorporating the slurry residue at the time of polishing or washing. If inorganic residues are present on the glass surface, moisture in the air tends to collect in the air around the inorganic residues, resulting in confusion in the surface properties of the alignment layer, and rusting nonuniformity easily occurs.

In the glass substrate 2 of the present embodiment, the value of (Ce + La) / Si is preferably 0.10 or less on the first main surface. As a result, occurrence of rubbing unevenness can be further suppressed. This is considered to be because the Ce-containing gelatinous silica layer and / or the slurry residue (CeO ₂ and / or LaOF) at the time of polishing or washing, which may cause the rubbing unevenness, are small on the first glass surface. The value of (Ce + La) / Si in the first main surface is obtained by TXRF analysis.

In the glass substrate 2 of the present embodiment, the value of (Ce + La) / Si is preferably 0.04 or less. Thus, in addition to the suppression of the rubbing unevenness, the defective spot can also be suppressed.

Here, " defective spot defects " refers to defects that are likely to occur in the peripheral region of the glass substrate 2 and can not be controlled when the liquid crystal display device 1 is actually used. .

The reason for dividing by (Si + La) / Si, such as Si, is as follows. In other words, since TXRF is very sensitive, it is difficult to prepare a standard sample to be a quantitative reference and to specify concentration. Therefore, in glass surface analysis, semi-quantitative values standardized by Si, which is a main component of glass, are generally adopted, and this is also the case in the present invention.

It is preferable that the value of O / Si is 2.5 or less in the first main surface of the glass substrate 2 of the present embodiment. The formation of the silica-rich weak layer on the glass surface is suppressed, so that the rubbing non-uniformity and / or defective spot defects can be reduced.

Here, the "silica-rich weak layer" is formed by using cerium oxide or an acid detergent in the polishing process (S1 described later), which is a manufacturing process of the glass substrate 2, or the cleaning process (S2 or S3 described later). Since the surface layer of the glass plate is altered in the layer, the layer tends to be easily broken down. Therefore, formation of an orientation film, wiring, and the like is not appropriately performed due to partial desorption, and rubbing unevenness and / or defective spot are liable to be caused. When the value of O / Si is 2.5 or less, the degree of substitution of Ce and the silica (Si) in the glass substrate 2 is not excessive, and formation of the silica-rich weak layer is suppressed.

The glass substrate 2 of the present embodiment preferably has a nanoindenter indentation hardness of 4300 N / mm 2 or more on the first main surface. The formation of the Ce-containing gel-like silica layer and / or the silica-rich weak layer is suppressed, so that the rubbing nonuniformity and / or the bad spot defect can be reduced. If the indentation hardness of the nanoindenter is 4300 N / mm < 2 > or more, for example, even if a silica-rich weak layer is formed, a part thereof is preferable because desorption is difficult.

In the glass substrate 2 of the present embodiment, the value of C / Si is preferably 1.0 or less on the first main surface. In addition, it is possible to reduce defects derived from organic residues (ET-AT defects).

Here, the "defect from organic residue (ET-AT defect)" refers to other defects other than rubbing non-uniformity and defective spot defect. Specific examples thereof are performance defects such as sparks, shorts, interlayer leak, and the like.

Further, the glass substrate 2 of the present embodiment has Ce on the first main surface. The presence of Ce indicates that the Ce component is detected in the surface analysis of XPS and the like. This indicates that the glass substrate 2 is treated with cerium oxide in the polishing process (S1 described later) and the cleaning process (S2 or S3 described later). Even if the first main surface has Ce, if the value of Ce is 0.1 atm% or less, occurrence of rubbing unevenness can be suppressed.

<Manufacturing Method>

Hereinafter, an example of a manufacturing method for manufacturing the glass substrate 2 of the present embodiment will be described. In the present embodiment, the processes are largely divided into three processes: a polishing step S1, a cleaning step S2, and a cleaning step S2. The process flow diagram refers to FIG.

Polishing step S1: While supplying the slurry, the surface of the glass substrate 2 is polished with a polishing pad.

The slurry used in the polishing step S1 is a rare earth acid compound to a cerium oxide (CeO ₂₎ as the main component, may contain La (LaOF), etc. Pr, Nd. Among the abrasives, cerium oxide has the property that O as a glass component and Ce as a component of cerium oxide can chemically react with each other. In addition to physical polishing, chemical polishing is also carried out simultaneously (chemical mechanical polishing) The surface of the substrate 2 is efficiently smoothed. In addition, cerium oxide has the highest polishing efficiency among all abrasive grains, and is widely used in the field of electronics / optics.

Here, in the polishing step S1, it is preferable to perform polishing using calcium carbonate as a slurry after polishing using cerium oxide as a slurry. By the cerium oxide, the Ce-containing gelated silica layer formed on the surface of the glass substrate, the slurry-retained and silica-rich weakened layer can be scraped off. It is also possible to perform polishing or the like for directly contacting the polishing pad with the glass without using the slurry.

Cleaning 1 Step S2: Brush the surface of the glass substrate 2 with a disc brush while supplying the slurry.

The slurry used in the cleaning step 1 (also referred to as a slurry cleaning step) S2 is calcium carbonate. A Ce-containing gelated silica layer formed on the surface of the glass substrate, a slurry-retained, silica-rich weakened layer can be cut out. It is possible to appropriately remove the Ce-containing gelated silica layer, the residual slurry, and the weak silica-rich layer by appropriately adjusting the concentration of the calcium carbonate slurry, the slurry particle size, the pressing force of the disc brush, and the number of disc brushes.

At least one of polishing and polishing step S2 may be performed using the calcium carbonate slurry in the polishing step S1. It is possible to suppress occurrence of rubbing unevenness of the glass substrate 2. It is also possible to further solve the defective spot by the degree. Further, in the present embodiment, it is assumed that the cerium-containing gelated silica layer formed on the surface of the glass substrate, or the slurry-retaining or silica-rich weak layer, is a polishing slurry of cerium oxide, but the present invention is not limited thereto. For example, cerium oxide is used for cleaning the surface of a glass substrate.

Washing 2 Step S3: Wash using detergent such as acid.

An air knife (jet of air) is used to remove water from the detergent used during the cleaning step 2 or S3. It is possible to suppress the occurrence of defects (ET-AT defects) originating from organic residues rather than using a roll (sponge) such as a rotating rubber or resin as a member for removing moisture. This is considered to be because the components of the roll do not adhere to the glass and adhere to the glass. It is also possible to suppress the occurrence of defects originating from organic residues by changing the detergent concentration.

The glass substrate 2 of the present embodiment can suppress the defects in the inorganic residue, the silica-rich weak layer, and the organic residue, which are problems in the related art, by the above-described method.

[Example]

In order to demonstrate the effect of the present embodiment, the X-ray photoelectron spectrometer (XPS), the total reflection X-ray fluorescence spectrometer (TXRF), and the nanoindentation tester (XRF) Ultrafine indentation hardness tester) was used for the test with the sample. Based on the test results, an appropriate numerical range for the glass substrate 2 of the present embodiment will be described below with reference to Figs. 3 to 5. Fig.

In the example, polishing was performed using cerium oxide as a slurry in the polishing step S1, and then polishing step S3 was carried out through a polishing step 1 and a cleaning step 2 using calcium carbonate as a slurry. The concentration of the slurry, the particle size, the pressure of the disk brush, the number of disk brushes, and the like were appropriately adjusted to prepare a plurality of samples having different numerical values obtained from XPS or TXRF.

In the comparative example, polishing was performed using cerium oxide as a slurry in the polishing step S1, and polishing step 2 and step S3 were not performed without polishing and / or cleaning 1 step S2 using calcium carbonate as a slurry.

&Lt; X-ray photoelectron spectrometer (XPS)

The surface compositions of the glass substrates of the obtained examples and comparative examples were analyzed by XPS to obtain C / Si, O / Si ratio and Ce quantitative value (atm%) (hereinafter referred to as "Ce amount"). The denominator and molecular units of C / Si and O / Si ratios are mass%, respectively.

For the XPS analysis, an optoelectronic spectrometer JPS-9010MC manufactured by JEOL Ltd. was used. The analysis conditions are as follows.

X-ray source: Mg-K ?, acceleration voltage 12 kV-emission current 25 mA

(FLG (Flood Gun)): Acceleration voltage 4.0V-Emission current 8.0mA

Detection angle (angle between sample surface and detector): 15 °

Detection area: 6 mmΦ

Sample size: 10 x 10 mm

Analysis Software: SpecSurf

<The amount of Ce>

The table in FIG. 3 (a) shows the rubbing nonuniformity evaluation for the amount of Ce, 0.02 atm%, 0.07 atm% and 0.11 atm% obtained by XPS analysis based on the examples and the comparative examples. The positive value of Ce is an average value of measured values at three points in the vicinity of the diagonal corner portion and the central portion of the glass substrate 2 in each sample. The values of the tables and the graphs shown in Fig. 5 are also the average values of the measured values at three points in the vicinity of the diagonal corner portion and the central portion of the glass substrate 2.

When the amount of Ce is 0.07 atm%, the result of the rubbing nonuniformity evaluation shows that the amount of Ce is 0.02 atm% and the amount of Ce is 0.07 atm% In the case of 0.11 atm%, "non-uniformity is shown (evaluation ×)".

Based on the results of the table, it can be concluded that the rubbing unevenness can be suppressed if the amount of Ce is 0.1 atm% or less in the first main faces 11 and 21 of the glass substrate 2. The amount of Ce is preferably 0.08 atm% or less, more preferably 0.06 atm% or less, further preferably 0.04 atm% or less, and still more preferably 0.02 atm% or less. When the amount of Ce is 0.06 atm% or less, in addition to the suppression of the rubbing nonuniformity, the bad spot defect can also be suppressed.

The amount of Ce is 0.1 atm% or less. However, the lower limit is not 0, and Ce may remain in the first main surfaces 11 and 21 of the glass substrate 2, though slightly. This indicates that the glass substrate 2 is treated with cerium oxide in the polishing step (S1 described later) and the cleaning step (S2 or S3 described later).

<C / Si value>

FIG. 3 (b) is a graph showing the correlation between the C / Si value and the ET-AT failure rate. From this graph, it can be understood that if the value of C / Si is 1.0 or less on the first main surface 11, 21, the defect originating from the organic residue can be reduced.

&Lt; TXRF (total reflection X-ray fluorescence spectrometer)

The surface compositions of the glass substrates of the obtained Examples and Comparative Examples were analyzed by TXRF to determine the value of (Ce + La) / Si. The units of denominator and numerator of the formula are mass%, respectively.

TXRF was a NANOHUNTER (Rigaku Denki Kogyo Co., Ltd., tabletop type). The analysis conditions are as follows.

X-ray tube: target Cu-K ?, tube voltage / tube current: 50 kV / 0.8 mA

Excitation X-ray spectroscopy element: artificial accumulation film

Here, X-ray irradiation angle: 0.1 °, analysis atmosphere: atmosphere (He gas flow)

Detection area: 10 mmΦ

Sample size: 30 x 50 mm

&Lt; (Ce + La) / Si value >

The table of FIG. 4 (a) shows the rubbing nonuniformity evaluation for the value of (Ce + La) / Si, 0.03, 0.04 and 0.11 obtained by TXRF analysis based on the examples and the comparative examples.

When the value of (Ce + La) / Si is 0.04, "non-uniformity is not observed (evaluation ⊚)" and when the value of (Ce + La) / Si is 0.04, , And when the value of (Ce + La) / Si is 0.11, "non-uniformity is shown (evaluation ×)".

4 (b) is a graph showing the correlation between the (Ce + La) / Si value and the defective spot defect rate.

From the rubbing nonuniformity evaluation in FIG. 4A and the graph in FIG. 4B, if the value of (Ce + La) / Si is 0.10 or less on the first main surfaces 11 and 21 of the glass substrate 2, It is understood that the rubbing unevenness is suppressed and the inorganic residue and / or the silica-rich weak layer can be suppressed.

The above-described value, the cerium oxide as an abrasive (CeO _2), since there is a case containing LaOF, by tinge to the value of La, Ce-containing gel-like silica layer and / or the slurry during polishing or cleaning residue (Ce and / or LaOF) can be understood more accurately.

The (Ce + La) / Si value is preferably 0.08 or less, more preferably 0.06 or less, further preferably 0.04 or less, and further preferably 0.03 or less. If the value of (Ce + La) / Si is less than 0.04 as compared with that shown in Fig. 4 (b), it is possible to suppress the rubbing nonuniformity as well as greatly suppress the bad spot defect.

<Nanoindentation Tester (ultra-small indentation hardness tester)>

The surface flaws of the glass substrates of the obtained Examples and Comparative Examples were evaluated by a nanoindenter and the indentation hardness H _IT value (N / mm 2) was obtained. In Fig. 5, eight on the left side are examples, and one on the right side is a comparative example.

For evaluation of the nanoindenter, ESF-5000Plus manufactured by Elionix was used.

The test conditions are as follows.

Atmosphere: Vacuum (50 to 300 Pa), Indenter: Berko Beach Indenter

Setting load: 10μN, load / removal time: 10sec., Load holding time: 1sec.

Measurement point: 5 points 占 5 points, measurement interval: X10 占 퐉, Y10 占 퐉

Sample fixing method: Aaron alpha adhesive

Sample size: 10 x 10 mm

5 is a graph showing the correlation between indentation hardness H _IT of the nanoindenter and O / Si. If the nanoindenter indentation hardness is large, it is evidence that there is no (or small) Ce-containing gelated silica layer or silica-rich weakened layer. That is, since O / Si has a correlation with the nanoindenter indentation hardness, it indirectly indicates that the gel-like silica layer or silica-poor layer is absent (or less).

From Fig. 6, the defective ratio such as rubbing unevenness was high in the comparative example in which the nanoindenter indentation hardness was less than 4300 N / mm &lt; 2 &gt;

Also, when the indentation hardness of the nanoindenter was 4700 N / mm &lt; 2 &gt; or more, the defective spot defects could also be reduced. The improvement of the defective spot defects is particularly preferably at least 5500 N / mm 2.

5 and 6, when the nanoindenter indentation hardness is 4300 N / mm &lt; 2 &gt; or more on the first main surfaces 11 and 21 of the glass substrate 2, inorganic residues (including a gelated silica layer) and / It is understood that the layer is suppressed. The nanoindenter indentation hardness is preferably at least 4500 N / mm 2, more preferably at least 4700 N / mm 2, even more preferably at least 5000 N / mm 2, even more preferably at most 5200 N / mm 2, Lt; 2 &gt; / mm &lt; 2 &gt; The formation of the gel-like silica layer and / or the silica-rich weak layer is suppressed, thereby making it possible to reduce rubbing nonuniformity and defective spot defects.

<O / Si value>

5 and 6, when the value of O / Si is 2.5 or less in the first main surfaces 11 and 21, formation of inorganic residue (including gel-like silica layer) and / or silica- And the rubbing non-uniformity and defective spot defects can be reduced.

When the value of O / Si was less than 2.47, the defective spot defect rate could also be lowered. The improvement of the defective spot defects is particularly preferably 2.25 or less.

The value of O / Si may be 2.5 or less, preferably 2.47 or less, more preferably 2.4 or less, still more preferably 2.3 or less, and further preferably 2.25 or less.

The present invention is not limited to the above-described embodiments, but can be appropriately modified and improved. In addition, the material, shape, size, numerical value, shape, number, arrangement position, and the like of each component in the above-described embodiments are not limited as long as they can achieve the present invention.

The glass substrate for a display of the present invention is suitably used in fields such as a liquid crystal device requiring rubbing unevenness and defective spot defects.

Although the present invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

The present application is based on Japanese Patent Application No. 2017-038388 filed on March 1, 2017, the contents of which are incorporated herein by reference.

1: liquid crystal device
2: glass substrate
10: first glass substrate
11: First main surface
12: 2nd week
20: second glass substrate
21: First main surface
22: 2nd week
30: liquid crystal
31: Thin film transistor
32: Color filter
33: Orientation film
34: polarizer

Claims (7)

A glass substrate for display comprising a silicate glass,
A first main surface and a second major surface opposite to the first main surface,
And the amount of Ce is 0.1 atm% or less in the first main surface. The glass substrate for display according to claim 1, wherein a value of (Ce + La) / Si is 0.10 or less on the first main surface. The glass substrate for display according to claim 1 or 2, wherein the value of O / Si in the first main surface is 2.5 or less. The glass substrate for a display according to any one of claims 1 to 3, wherein the nanoindenter indentation hardness in the first main surface is 4300 N / mm 2 or more. The glass substrate for a display according to any one of claims 1 to 4, wherein a value of C / Si in the first main surface is 1.0 or less. The glass substrate for a display according to any one of claims 1 to 5, wherein the first main surface is a device formation surface. The glass substrate for a display according to any one of claims 1 to 6, wherein the glass substrate for display has Ce on the first main surface.

Images