JP2001332607A - Apparatus for heating wafer and soaking plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for heating a substrate with more uniform temperature distribution through a simple arrangement. SOLUTION: An apparatus for heating a substrate 1 in a vacuum container 5 comprises a soaking plate 8 having a substantially uniform temperature distribution on the surface upon heating, and means 10 for holding the substrate oppositely to the surface through a specified distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heating a substrate used for producing a flat panel display in a vacuum chamber, for example, for forming a substrate on a flat panel display in a vacuum chamber and for making the temperature of the substrate uniform. It relates to an apparatus and a soaking plate.

[0002]

2. Description of the Related Art In the manufacture of flat panel displays, a substrate, which is a member of a flat panel display, is often placed in a vacuum vessel and subjected to a process such as aging. In particular, Japanese Patent Application Laid-Open No. 6-20590 discloses a process of manufacturing a flat panel display using an electron-emitting device in a vacuum vessel.

[0003] In the production of such a flat panel display, setting the production conditions, particularly the temperature, to a desired value is an important problem because the performance of the produced flat panel display is affected. In a vacuum device for manufacturing a flat panel display, a plate incorporating a heater was installed in a vacuum vessel as a temperature control unit, and the plate was brought into contact with the plate by setting the temperature of the plate to a predetermined value. Generally, the substrate temperature of the flat panel display is set to a desired temperature.

[0004]

However, according to the conventional temperature control method in a vacuum vessel, a large temperature distribution is applied to a flat panel display substrate placed on a plate of a temperature control unit in the vacuum vessel. There is a problem that occurs. Further, it takes time until the temperature of the plate of the temperature control unit reaches a predetermined set temperature, causing a waste time before the start of the production process, and the control of the heater in the temperature control unit is performed for each block. There is a problem that is. These problems may be due to the following reasons.

[0005] In the manufacture of flat panel displays, the degree of temperature uniformity required in a vacuum vessel varies depending on the processing to be performed. JP-A-6-20
Taking the manufacture of a flat panel display described in Japanese Patent Application Laid-Open No. 590 as an example, it is empirically required in subsequent studies to keep the substrate temperature within a range of, for example, 10 ° C. with respect to a predetermined temperature. On the other hand, the actually obtained temperature distribution is slightly different depending on the substrate, but empirically, it is 250 ° C.
The maximum temperature is 30 ° C for a × 300 mm glass substrate. This temperature distribution is a major problem because it affects the quality of the manufactured flat panel display.

[0006] Such a problem of the temperature distribution of the substrate which occurs in the above-described conventional temperature control method in a vacuum vessel is caused by an attempt to control the temperature under vacuum or reduced pressure. Normally, heat is transmitted by heat conduction of members in contact, thermal convection of atmospheric gas, and thermal radiation. In flat-panel display substrates, the substrate has undulations and warpages in production. Its size is 250
According to an actual measurement of a × 300 mm glass substrate, it was 0.2 mm or less. In addition, the undulation cycle of the glass substrate was 100 mm or more in all the measurement evaluations of 10 samples. In the conventional temperature control in the vacuum vessel, a substrate is placed on a plate of a temperature control unit. However, as mentioned above,
Due to the undulation or warpage of the substrate, there are places where the substrate and the temperature control plate come into contact with each other and where they do not. That is, heat conduction occurs where the plates are in contact, and no heat transfer occurs where they are not. This is considered to cause a problem that the conventional temperature control method has a problem that a large temperature distribution is generated on a flat panel display substrate installed on a plate of a temperature control unit in a vacuum vessel.

In Japanese Patent Application Laid-Open No. Hei 10-116885, in order to solve these conventional problems, the heater is divided into several blocks and separately controlled, and the surface contact with the substrate is ensured by electrostatic attraction. A proposal has been made.
However, according to this proposal, an effective attraction force cannot be obtained even if static electricity is applied to some substrates, particularly to a glass substrate. Further, dividing the heater into several blocks inevitably leads to the complexity of the apparatus.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a substrate heating apparatus having a simple configuration capable of performing heating with a more uniform temperature distribution.

[0009]

In order to solve this problem, a first substrate heating apparatus according to the present invention is an apparatus for heating a substrate in a vacuum vessel, and has a surface having a substantially uniform temperature distribution by heating. And a substrate holding means for holding the substrate so as to face the surface at a predetermined distance.

The second substrate heating device is the first substrate heating device, wherein a first heat source for heating the heat equalizing plate from the back surface side and a portion other than the first heat source between the back surface side and the heat source. Wherein the substrate holding means is constituted by a member arranged on an outer peripheral portion of the heat equalizing plate, and has a second heat source therein.

In a third substrate heating apparatus, in the second substrate heating apparatus, the heat source surrounding means blocks leakage of radiant energy from the first heat source to a space where the substrate in the vacuum vessel is disposed. It is characterized by that.

A fourth substrate heating apparatus according to the second or third substrate heating apparatus is characterized in that the first heat source is an infrared lamp heater and the second heat source is a sheath heater.

A fifth substrate heating apparatus according to any one of the first to fourth substrate heating apparatuses, wherein the substrate holding means holds the substrate so as not to contact the soaking plate. Features.

A sixth substrate heating apparatus is characterized in that, in any one of the first to fifth substrate heating apparatuses, means for setting the inside of the vacuum vessel to a vacuum or a reduced-pressure atmosphere is provided.

A seventh substrate heating apparatus is the sixth substrate heating apparatus, wherein the reduced pressure atmosphere is 10 ^-3 Torr.
It is characterized in that the atmosphere is not less than the atmospheric pressure.

Further, the heat equalizing plate of the present invention is a heat equalizing plate whose back surface is heated by a heat source and which heats a substrate facing the front surface, wherein the heat equalizing plate is blackened. I do.

The second heat equalizing plate is a heat equalizing plate whose back surface is heated by the heat source and heats the substrate facing the front surface, and has a surface having irregularities.

The third heat equalizing plate is characterized in that the first or second heat equalizing plate is made of aluminum.

A seventh substrate heating apparatus according to any one of the first to seventh substrate heating apparatuses, wherein the heat equalizing plate is a first to third substrate heating apparatus.
Characterized in that it is any one of the soaking plates.

In the structure of the present invention, when heating the substrate, the substrate is held by the substrate holding means and the soaking plate is heated. Then, the surface of the soaking plate is heated with a uniform temperature distribution, and the heat uniformly heats the substrate. At this time, since the surface of the heat equalizing plate and the substrate face each other at a certain distance, heat is mainly transmitted from the heat equalizing plate to the substrate by heat radiation and thermal convection. Therefore, even under a reduced pressure in the vacuum vessel, heat conduction due to contact between the substrate and the temperature control plate is dominant, so that a large temperature distribution conventionally caused does not occur.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A substrate heating apparatus according to a preferred embodiment of the present invention comprises one or more first heat sources corresponding to the heating of a substrate placed horizontally in a vacuum vessel, and a horizontal heat source above the first heat source. A soaking plate, a shielding plate surrounding the first heat source,
It has a support frame that supports the substrate arranged around the heat equalizing plate, and a second heat source that heats the outer peripheral portion of the substrate installed inside the support frame, whereby the substrate can be uniformly heated. It has a configuration. The first heat source, the soaking plate, and the substrate are installed in a non-contact manner, and the heat transfer to the substrate is mainly performed by heat radiation and heat convection. In order to further improve the efficiency of heat radiation, the surface of the soaking plate is subjected to black alumite treatment (blackening).
Furthermore, in order to make the radiant heat radiant energy uniform, it is necessary to make the temperature distribution on the substrate side surface of the heat equalizing plate uniform. Therefore, even if a temperature distribution of ± 10 ° C occurs on the back surface of the soaking plate that directly receives the radiant heat from the first heat source, the soaking plate has a temperature distribution of ± 1 ° C or less on the surface of the soaking plate. It is made of aluminum to have a sufficient heat capacity, and the plate thickness is 5
mm. Since the convective heat conduction of the atmospheric gas also contributes to the temperature of the substrate to some extent, the surface of the soaking plate is roughened as a measure for improving the efficiency of the convective heat. The shielding plate blocks leakage energy from the first heat source to parts other than the soaking plate, so that heat radiation from other than the soaking plate to the substrate does not occur. In addition, the temperature of the peripheral portion of the substrate tends to be lower empirically and experimentally. The second heat source is disposed on the outer peripheral portion of the substrate so as to support the substrate in order to prevent the temperature from dropping.

According to this, as heat conduction to the substrate, heat radiation from the soaking plate and heat conduction by heat convection are dominant, and the surface of the soaking plate has a temperature distribution within ± 1 ° C. Since the radiation energy to the substrate is made uniform, the substrate can be uniformly heated, and the substrate temperature can be kept within ± 1 ° C. with respect to the predetermined temperature. In addition, by using an infrared lamp heater as a heat source for the soaking plate, the rate of temperature rise is twice as fast as that of the conventional temperature control plate method, and is significantly higher. Thereby, the takt time of the production process can be reduced.

[0023]

Next, an embodiment of the present invention will be described. Embodiment 1 FIG. 1 shows a prototype substrate heating mechanism according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a substrate to be heated, 8 denotes an aluminum soaking plate for uniformly heating the opposing substrate 1 at a certain distance, and 2 denotes a red heat source for heating the soaking plate 8. An outer lamp heater, 3 is a heater for the outer peripheral portion of the substrate provided on an outer peripheral portion of the substrate 1, 4 is a shielding plate for blocking light leaked from the infrared lamp heater 2, and 10 is a support for supporting the substrate 1. Body. The substrate outer peripheral heater 3 is incorporated in the support 10. Reference numeral 5 denotes a vacuum vessel for accommodating these components, 6 denotes an atmosphere gas exhaust pipe for exhausting gas in the vacuum vessel 5, and 7 denotes an atmosphere gas supply pipe for supplying an atmosphere gas into the vacuum vessel 5. .

As shown in FIG. 5, the surface of the heat equalizing plate 8 is subjected to unevenness processing and blackening treatment (black alumite) to improve the radiant heat efficiency and the heat convection efficiency due to the atmospheric gas. . The unevenness processing has a processing structure in which columns of 3 mm square are arranged uniformly at the center.

Using this substrate heating mechanism, the set temperature of the substrate 1 is set to 100 ° C., and the substrate 1 is heated for 100 T in an argon flow atmosphere.
An experiment of heating the substrate 1 under a reduced pressure of orr was performed. The substrate 1 is made of glass and has a size of 450 × 350.
X (thickness) 2.8 was used. At that time, the temperature was measured at the temperature measurement positions 1 to 9 of the substrate 1 as shown in FIG.

The temperature (unit: ° C.) of the measurement results is shown in Table 1 of FIG. As can be seen from Table 1, ± 1 at all positions for the set temperature of 100 ° C.
A temperature distribution within ° C was achieved. At this time, the set temperature of the infrared lamp heater 2 was 250 ° C., and the set temperature of the sheath heater as the substrate outer peripheral heater 3 was 80 ° C.

(Embodiment 2) Using the substrate heating mechanism shown in FIG. 1, the pressure in the vacuum vessel 5 was increased to atmospheric pressure, 1 × 10 ⁻³ Torr.
The same experiment was performed under the same conditions as in Example 1 except that the experiment was performed under each of the three types of reduced pressure of r and 1 × 10 ⁻⁴ Torr. The set temperature of the substrate 1 was 100 ° C. as described above. The results are shown in Table 2 of FIG.

As can be seen from Table 2, the atmospheric pressure and 1 × 10
Under a reduced pressure of ^-3 Torr, a temperature distribution within ± 1 ° C of the target was achieved. However, under 1 × 10 ⁻⁴ Torr, the temperature at the central portion of the substrate 1 became high, and a temperature distribution within ± 1 ° C. could not be achieved. It is considered that this is because the convective heat in the space confined between the heat equalizing plate 8 and the substrate 1 contributes to the uniform heat of the substrate 1. That is, when the degree of vacuum is 1 × 10 ⁻⁴ Torr or less, convection heat transfer does not act, and radiant heat transfer becomes dominant.

(Embodiment 3) Using the substrate heating mechanism shown in FIG. 1, three types of soaking plates 8 are used: a flat aluminum plate having no surface treatment, a blackened aluminum flat plate, and an aluminum flat plate subjected to uneven processing. An experiment was performed under the same conditions as in Example 1 except that the test was used. Table 3 shows the results. The substrate 1 at that time
FIG. 3 shows how the temperature rises. The experiment was performed at 100 Torr.
r Performed under reduced pressure. ± 1 of the target for any heat equalizing plate 8
Temperature distribution within ° C could not be achieved. However, the temperature distribution was the smallest in the case of the blackened aluminum plate, the smallest in the case of the unevenness-treated aluminum plate, and the largest in the case of the surface-untreated aluminum plate. Example 1
As described in the above, the heat equalizing plate 8 subjected to the unevenness processing and the blackening treatment
In the case of, a temperature distribution within ± 1 ° C is achieved.

As can be seen from FIG. 3, the structure of the heat equalizing plate 8 significantly contributes to the heating rate. Compared to the aluminum plate with no surface treatment, the aluminum plate that has been subjected to the unevenness processing and the blackening treatment reaches the target 100 ° C. at approximately twice the heating rate. The first cause is that the surface area of the heat equalizing plate 8 is increased by about 2.5 times due to the unevenness and the convective and radiant heat transfer efficiency is improved.
In addition, it is considered that the heat from the infrared lamp heater 2 is efficiently absorbed by the blackening process of the heat equalizing plate 8, and the temperature of the heat equalizing plate 8 itself is rapidly increased.

Example 4 A similar experiment was performed under the same conditions as in Example 1 except that the shielding plate 4 was removed using the substrate heating mechanism shown in FIG. The results are shown in Table 4 of FIG. From this table, it can be seen that the temperature distribution of ± 5 ° C. occurs when the shielding plate 4 is removed. This is because the space between the heat equalizing plate 8 and the substrate 1 is not a closed space, so that heat transfer due to convection is not uniform, and radiant heat from the infrared lamp heater 2 is It is considered that the radiant heat transmitted from the inner wall of the vacuum vessel 5 to the inner wall of the vacuum vessel 5 is reflected in all directions and uneven heat transfer to the substrate 1 is performed.

Example 5 Using the substrate heating mechanism shown in FIG. 1, a similar experiment was performed under the same conditions as in Example 1 except that the sheath heater 3 was turned off. The results are shown in Table 5 in FIG.
Shown in From this table, it can be seen that the temperature was low at the outer peripheral portion of the substrate 1 and a temperature distribution of ± 9 ° C. occurred. It is considered that the cause is the escape of heat from the support 10 at the outer peripheral portion of the substrate 1 and the heat radiation from the outer peripheral portion of the substrate 1 at which the heat can easily escape.

According to each of the above embodiments, the infrared lamp heater 2, which is the first heat source installed in the vacuum vessel 5, the heat equalizing plate 8, which has been subjected to the blackening process and the unevenness process receiving the heat, and the substrate The configuration including the heater 3 as the second heat source in the peripheral portion and the shielding plate 4 for confining the radiant heat from the infrared lamp heater 2 makes the heat transfer by heat radiation and heat convection dominant in the transfer of heat to and from the substrate 1. It can be seen that the temperature uniformity of the substrate 1 can be increased and the temperature distribution of the substrate 1 can be reduced.

This substrate heating mechanism is used to make the temperature of the substrate 1 uniform when performing film formation or other processing in the vacuum vessel 5, and is used particularly in the manufacture of flat panel displays. Such a substrate heating mechanism is intended for application not only to the manufacture of a flat panel display, but also to the processing of a silicon wafer for IC in a vacuum, the processing in a vacuum in the manufacturing process of a functional device, and the like.

[0035]

As described above, according to the present invention,
Since the opposing substrate is heated at a predetermined distance by the heat equalizing plate whose surface has a substantially uniform temperature distribution by heating, the substrate can be heated with a uniform temperature distribution. Further, a first heat source for heating the heat equalizing plate from the back surface, a heat source surrounding means for surrounding the heat source, and a substrate holding means having a second heat source therein and arranged on an outer peripheral portion of the heat equalizing plate The substrate can be heated with a more uniform temperature distribution.

[Brief description of the drawings]

FIG. 1 is a view showing a substrate heating mechanism according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a temperature measurement position of a substrate in each embodiment of the present invention.

FIG. 3 is a graph showing a temperature rising rate of a substrate with the structure of a heat equalizing plate as a parameter according to a third embodiment of the present invention.

FIG. 4 is a table showing the results of measuring the temperature of the substrate in each example.

FIGS. 5A and 5B are a plan view and a front view, respectively, showing a state in which the surface of the heat equalizing plate has been subjected to unevenness processing and blackening processing.

[Explanation of symbols]

1: substrate, 2: infrared lamp heater (first heat source), 3:
Sheath heater for substrate outer periphery (second heat source), 4: shield plate, 5: vacuum vessel, 6: atmosphere gas exhaust pipe, 7: atmosphere gas supply pipe, 8: heat equalizing plate, 10: support.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F031 CA05 HA09 HA37 5F045 AE15 AE17 AE19 AE21 AE23 AE25 BB01 EC05 EF01 EG01 EK07 EK13 EM01

Claims (11)

[Claims] An apparatus for heating a substrate in a vacuum vessel, wherein the substrate is heated so that the surface has a substantially uniform temperature distribution, and the substrate is opposed to the surface at a predetermined distance. A substrate holding device for holding the substrate. A first heat source for heating the heat equalizing plate from the back surface side; and a heat source surrounding unit for surrounding the heat source at a portion other than between the first heat source and the back surface. 2. The substrate heating apparatus according to claim 1, wherein the substrate heating apparatus is constituted by a member arranged on an outer peripheral portion of the heat equalizing plate, and has a second heat source inside. 3. The heat source surrounding means for blocking leakage of radiant energy from the first heat source to a space where a substrate in the vacuum vessel is arranged. Substrate heating equipment. 4. The substrate heating apparatus according to claim 2, wherein the first heat source is an infrared lamp heater, and the second heat source is a sheath heater. 5. The substrate heating apparatus according to claim 1, wherein the substrate holding unit holds the substrate so as not to contact the heat equalizing plate. 6. The substrate heating apparatus according to claim 1, further comprising means for setting a vacuum or reduced-pressure atmosphere in the vacuum vessel. 7. The substrate heating apparatus according to claim 6, wherein the reduced pressure atmosphere is an atmosphere of 10 ⁻³ Torr or more and an atmospheric pressure or less. 8. A soaking plate for heating a back surface thereof by a heat source and heating a substrate facing the front surface, wherein the soaking plate is subjected to a black body treatment. 9. A heat equalizing plate whose back surface is heated by a heat source and heats a substrate facing the front surface, wherein the surface has irregularities. 10. The heat equalizing plate according to claim 8, wherein the heat equalizing plate is made of aluminum. 11. The substrate heating apparatus according to claim 1, wherein the heat equalizing plate is the heat equalizing plate according to any one of claims 8 to 10.