JP2000302484A - Heat-resistant surface plate and heat treatment of glass substrate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-resistant surface plate which hardly damages the surface of a glass substrate even if the glass substrate is placed on the plate and heat-treated, which readily separates the glass substrate without sliding of the glass substrate and can easily remove a stain by cleaning even if stained and to provide a method for treating the glass substrate by using the plate. SOLUTION: Since this heat-resistant surface plate is obtained by forming a silica film 11 on the surface of a laminar heat-resistant material 10, even if the surface of the heat-resistant material 10 is a ground face, namely a face on which a great number of fine recessed parts 10a and projected parts 10b are present, the recessed parts 10a are filled with the silica film 11. Consequently difference of height of the unevenness is reduced and a flaw hardly occurs on the glass substrate even if the glass substrate is rubbed on the plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant platen used for heat-treating a glass substrate which is mainly used as a substrate for electronic equipment, and a method for heat-treating a glass substrate.

[0002]

2. Description of the Related Art In recent years, with the development of the electronic equipment industry, various electronic equipments, especially liquid crystal, electroluminescence,
Display device such as plasma display or substrate glass for image sensor etc.
m of thin glass is being used in large quantities.

[0003] The glass substrate used for the above-mentioned applications is subjected to processes such as film formation heat treatment and patterning since a thin film or thick film electric circuit, an insulator layer and the like are formed thereon. In these treatments, the glass substrate may be exposed to a high temperature, so that the glass substrate is required to have good thermal dimensional stability.

For example, TN (Twisted Nemat)
ic) and STN (Super Twisted Ne)
material) mode, a transparent conductive film circuit in a liquid crystal display, α-SiTFT (Amorphous-S)
i Thin Film Transistor), p
-Si TFT (poly-Si Thin FilmT
In the manufacturing process of a thin film electric circuit of a liquid crystal display, a thin film and a thick film electric circuit of a plasma display, a thin film electric circuit of electroluminescence, etc. formed by a combination of various kinds of metal films, insulating films, etc. When the substrate is subjected to a high-temperature heat treatment, the dimensions of the glass substrate change and the predetermined dimensions cannot be maintained, or the circuit pattern deviates from the predetermined design. This circuit pattern shift is a fatal cause of failure to maintain electrical performance, and a dimensional change of 1 μm or less per 100 mm may not be allowed depending on the application.

On the other hand, a glass substrate for such an application is required to have a small warpage or undulation, that is, a good flatness of the glass surface. In other words, if the flatness of the glass substrate is poor, the exposure distance may not be as designed, or the gap between the two glass substrates of the liquid crystal may cause unevenness and display performance may be impaired. It causes various problems, including an ancillary problem of being incompatible with mechanical operations in the process, and a flatness of several μm to several tens μm is required over the entire surface of the glass substrate depending on the application.

However, a glass substrate having good thermal dimensional stability and flatness cannot be obtained only by forming a glass sheet by a known forming method such as a down-draw method or a float method. Is generally raised from a temperature near the strain point to a temperature near the softening point, kept for a certain time, and then gradually cooled.

[0007] The heat treatment causes the dimensional change of the glass substrate to advance to near the saturation value in advance, thereby improving the thermal dimensional stability of the glass substrate and improving the flatness by softening and deforming the surface of the sheet glass.

[0008] Specifically, this heat treatment step comprises, after forming a glass sheet and cutting the glass substrate into a predetermined size, placing the glass substrate on a heat-resistant platen.
It is common to charge the mixture in a batch furnace or a tunnel furnace and heat-treat it under predetermined conditions.

Also, when forming various thick films and thin films on the surface of a glass substrate, a method is adopted in which the glass substrate is placed on a heat-resistant platen and then heat-treated.

[0010]

However, as described above, when a glass substrate is placed on a heat-resistant platen and subjected to heat treatment, when the glass substrate is placed on the platen or after the heat treatment. When the glass substrate is taken out, there is a problem that the glass substrate rubs against the surface plate and a large number of fine scratches are easily generated on the surface of the glass substrate.

Particularly, in the case of a glass substrate for an electronic device such as a liquid crystal, the scratch on the surface is not only a problem that the transparency is impaired in appearance, but also the thin film electric circuit is not formed as designed due to the scratch. In addition, it causes fatal failures such as failure to obtain desired electrical characteristics and disconnection. In the case of a fine thin film electric circuit, even a scratch having a length of only a few μm becomes a problem.

The cause of the flaw on the surface of the glass substrate is that many fine irregularities are formed on the surface of the heat-resistant surface plate.

That is, this kind of surface plate is manufactured by grinding the surface of a low-expansion or negative-expansion heat-resistant ceramic plate or a crystallized glass plate.
It is difficult to completely smooth the surface, and fine irregularities remain.

Further, if fine irregularities are present on the surface of the surface plate as described above, when the surface plate is contaminated, even if it is washed, it is difficult to completely remove even the contamination that has entered the unevenness. In addition, when a glass substrate is placed on such a surface plate and heat-treated, there is also a problem that contamination of the surface plate is transferred to the glass substrate.

If the surface of a ceramic plate or a crystallized glass plate is polished, a surface having high smoothness can be obtained.
The processing cost becomes extremely high, and when the glass substrate is placed on the surface plate, the glass substrate slides and moves,
Further, there is a problem that the glass substrate is not easily separated from the surface plate even when trying to lift the glass substrate.

An object of the present invention is that even when a glass substrate is placed thereon and heat-treated, the surface of the glass substrate is not easily damaged, and the glass substrate does not slip and is easily separated.
In addition, it is an object of the present invention to provide a heat-resistant surface plate capable of easily removing contamination by washing, and a method of heat-treating a glass substrate using the same.

[0017]

The heat-resistant surface plate of the present invention comprises:
It is made of a plate-like heat-resistant material, and is characterized in that a silica film is formed on the surface, and is made of a plate-like heat-resistant material, the surface is ground, and a silica film is further formed. I do.

Further, the heat treatment method for a glass substrate according to the present invention is characterized in that the heat treatment is performed by placing the glass substrate on a heat-resistant platen, wherein the heat-resistant platen is made of a plate-shaped heat-resistant material. Is characterized in that a silica film is formed thereon.

[0019]

As shown in FIG. 1, the heat-resistant surface plate according to the present invention has a plate-shaped heat-resistant material 10 on which a silica film 11 is formed.
In other words, even on a surface where a large number of fine concave portions 10a and convex portions 10b exist, the concave portions 10a are filled with the silica film 11. For this reason, the difference in height of the unevenness becomes small, and even if the glass substrate is rubbed on the surface plate, the glass substrate is hardly damaged. Further, even if the surface of the heat resistant material is contaminated, the contamination can be easily removed by washing.
Further, since there are some irregularities as compared with the polished surface, the glass substrate can be easily lifted from the surface plate.
When grinding the heat-resistant surface plate of the present invention, only one surface may be ground, or both surfaces may be ground.

Such a heat resistant surface plate is suitably formed from a ceramic plate or a crystallized glass plate having low expansion or negative expansion because of its excellent heat resistance and dimensional stability. In particular _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass plate, can be manufactured at low cost, preferable because it is excellent in workability.

The silica film has an advantage that the concave portion can be appropriately filled by being formed on the ground surface of a plate-like heat-resistant material, and the raw material cost is low. The method of forming the silica film on the heat-resistant material is not particularly limited,
For example, silicon dioxide glass is prepared by sol-gel method, chemical vapor deposition method,
The film may be formed to have a thickness of preferably 200 to 30,000.

The conditions of the heat treatment in the present invention are in the range from about the strain point of the glass (the glass has a viscosity of 10 ^14.5 poise) to about the softening point (the temperature of the glass has a viscosity of ^107.6 poise). Usually, in the case of borosilicate alkali-free glass used as a liquid crystal glass substrate, the strain point is 600
680 ° C., and the softening point is 850-1000 ° C.

[0023]

The present invention will be described below in detail based on examples and comparative examples.

Example 1 First, in terms of weight percentage, SiO _{2
60%, B 2 O 3 10} %, Al 2 O 3 15%, RO
It has a composition of 15%, a strain point of 650 ° C. and a softening point of 950.
A glass substrate was obtained by cutting glass formed into a plate shape by the down-draw method at a temperature of 590 x 670 x 0.7 mm.

As a heat-resistant surface plate, 740 × 840 ×
A surface of a crystallized glass plate (Neoceram N-0 manufactured by NEC Corporation) having a size of 5.0 mm is subjected to # 200 diamond grinding wheel generation grinding, and then silicon dioxide glass is applied to the surface by a sol-gel method. Then, a silica film having a thickness of 1000 ° or less was formed.
The surface roughness of this silica film was Ra / σ of 0.407.
/0.01, Rmax / σ is 3.983 / 0.436,
Rz / σ was 3.009 / 0.318.

Next, after placing the glass substrate on a heat-resistant platen, the glass substrate is put into a batch-type furnace, heat-treated at 700 ° C. for 30 minutes, taken out of the furnace, and the glass substrate is placed on the platen. And observed the state of the contact surface with the surface plate.

Example 2 Example 1 was used as a heat-resistant surface plate.
After the # 200 diamond grinding wheel generation grinding is performed on the surface of the crystallized glass plate similar to that described above, the # 400 alumina free grinding wheel is further ground, and then silicon dioxide glass is coated on the surface by the sol-gel method. A silica film having a film thickness of was formed. The surface roughness of the silica film was Ra / σ of 0.24 / 0.0.
1, Rmax / σ was 2.15 / 0.18, and Rz / σ was 1.75 / 0.11.

Next, a glass substrate produced in the same manner as in Example 1 was placed on the heat-resistant platen, heat-treated in the same manner as in Example 1, and taken out of the furnace. It was lifted from the surface plate and the state of the contact surface with the surface plate was observed.

Example 3 Example 1 was used as a heat-resistant surface plate.
The same crystallized glass plate as above was subjected to # 200 diamond grinding wheel generation grinding, and then silicon dioxide glass was applied to the surface by a sol-gel method to form a silica film having a thickness of 10,000 or less. Got ready.
The surface roughness of this silica film was Ra / σ of 0.251.
/0.01, Rmax / σ is 2.248 / 0.208,
Rz / σ was 1.763 / 0.176.

Next, a glass substrate produced in the same manner as in Example 1 was placed on this heat-resistant platen, heat-treated in the same manner as in Example 1, and taken out of the furnace. It was lifted from the surface plate and the state of the contact surface with the surface plate was observed.

Example 4 Example 1 was used as a heat-resistant surface plate.
After the # 200 diamond grinding wheel generation grinding is performed on the surface of the crystallized glass plate similar to that described above, the # 400 alumina free grinding wheel is further ground, and then the surface is coated with silicon dioxide glass by a sol-gel method. A silica film having a film thickness of was formed. still,
The surface roughness of this silica film is such that Ra / σ is 0.22 / 0.
01, Rmax / σ was 1.24 / 0.11, and Rz / σ was 1.53 / 0.08.

Next, a glass substrate produced in the same manner as in Example 1 was placed on the heat-resistant platen, heat-treated in the same manner as in Example 1, and taken out of the furnace. It was lifted from the surface plate and the state of the contact surface with the surface plate was observed.

(Comparative Example 1) Example 1 was used as a heat-resistant surface plate.
The same crystallized glass plate as described above was prepared by subjecting a # 200 diamond grindstone generation grinding to the surface. The surface roughness of the heat-resistant surface plate after the grinding was Ra / σ of 0.4.
95 / 0.087, Rmax / σ is 6.745 / 1.8
11, Rz / σ was 4.336 / 0.874.

Next, a glass substrate produced in the same manner as in Example 1 was placed on this heat-resistant platen, heat-treated in the same manner as in Example 1, and taken out of the furnace. It was lifted from the surface plate and the state of the contact surface with the surface plate was observed.

Comparative Example 2 Example 1 was used as a heat-resistant surface plate.
The same crystallized glass plate as described above was subjected to # 200 diamond grinding wheel generation grinding, followed by # 400 alumina free grinding stone grinding. The surface roughness of the heat-resistant platen after the grinding was Ra / σ of 0.25 /
0.01, Rmax / σ is 2.64 / 0.46, Rz /
σ was 1.90 / 0.20.

Next, a glass substrate produced in the same manner as in Example 1 was placed on this heat-resistant platen, heat-treated in the same manner as in Example 1, and taken out of the furnace. It was lifted from the surface plate and the state of the contact surface with the surface plate was observed.

Table 1 shows the observation results of the above Examples and Comparative Examples. The cleaning properties of each heat resistant surface plate were also examined, and the results are also shown in Table 1.

Incidentally, regarding the scratches and contamination in the table, x is 1 mm.
Transfer of the above scratches and contamination, △ is up to 0.9m
m provided transfer of scratches or contamination, ○ indicates not transferred scratches or contamination of 0.5 mm or more, ◎ indicates 0.2 mm
This shows the case where the transfer of the above scratches and contamination was not given. Regarding the cleaning properties of the surface plate, after cleaning the heat-resistant surface plate using a single-wafer-type roll brush type washer, it was made easy to remove contamination and made difficult to remove contamination.

[0039]

[Table 1]

As is clear from the table, in the examples, the scratches and contamination generated on the surface of the glass substrate were smaller than those in the comparative examples, and the surface plate was also excellent in cleaning property.

[0041]

As described above, when a glass substrate is heat-treated using the heat-resistant surface plate of the present invention, even if the surface of the surface plate is a ground surface, a large problem may occur on the surface of the glass substrate. The glass substrate is hardly scratched, does not slip when the glass substrate is placed on the surface plate, is easily separated from the surface plate, and even if the surface plate is contaminated, the contamination can be easily removed by washing.

For this reason, this heat-resistant surface plate is particularly suitable as a lower surface plate for heat-treating a substrate for an electronic device used for a display device such as a liquid crystal, electroluminescence or plasma display, or an image sensor.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a heat-resistant surface plate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat resistant material 10a Concave part 10b Convex part 11 Silica film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 FA18 FA21 HA01 HA08 JA05 JA13 MA20 2H090 JB02 JC08 JC19 JD14 JD15 KA05 KA08 LA04 4G015 EA00 GA00 4G059 AA15 AB03 AC03 EA05 EB07 4G062 AA11 BB06 DA02 DC01 DC01 ED00 EE00 EF00 EG00 FA00 FA10 FB00 FC00 FD00 FE00 FF00 FG00 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 KK01 KK01 KK03 JJ03 KK03

Claims (4)

[Claims] 1. A heat-resistant surface plate comprising a plate-shaped heat-resistant material and having a silica film formed on a surface thereof. 2. A heat-resistant surface plate comprising a plate-shaped heat-resistant material, a surface of which is ground and a silica film formed thereon. 3. A method of placing a glass substrate on a heat-resistant surface plate and performing heat treatment, wherein the heat-resistant surface plate is made of a plate-like heat-resistant material and has a silica film formed on the surface. A method for heat-treating a glass substrate, the method comprising: 4. The heat treatment method for a glass substrate according to claim 3, wherein the heat-resistant platen is made of a plate-shaped heat-resistant material, the surface of which is ground and a silica film is further formed. .