JP3874152B2 - Heating apparatus and heating method - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a heating device used for heat treatment of a semiconductor or the like, and more particularly to a heating device used for heat treatment of a thin film transistor formed on a glass substrate in order to manufacture a liquid crystal display, an image sensor, or the like.
[0002]
[Prior art]
Conventionally, heating furnaces such as annealing furnaces, diffusion furnaces, oxidation furnaces and low-pressure CVD (Chemical Vapor Deposition) for forming semiconductor films formed on silicon wafers and substrates have been used. . In recent years, these heating furnaces are mainly of a type in which a reaction tube is placed vertically instead of a type in which a reaction tube is placed horizontally (for example, disclosed in FIG. 3 of JP-A-8-8194) in order to save the space of the apparatus. It has become. Further, in an oxidation furnace, a high reaction rate depending on the pressure can be obtained by increasing the gas atmosphere in the reaction tube (for example, disclosed in JP-A-53-112064 and JP-A-56-24938). .) Is also known. In recent years, since a large-area square glass substrate is used for a liquid crystal display or the like, an apparatus for processing a large-area square glass substrate is required instead of the conventional round silicon wafer.
[0003]
Moreover, when processing a glass substrate, it is necessary to process at the temperature which does not affect a glass substrate. Usually, alkali-free glass is used in consideration of the influence of impurities on the semiconductor device. As the alkali-free glass, barium borosilicate glass, borosilicate glass, aluminoborosilicate glass, aluminosilicate glass, or the like is used. However, the strain point of such a glass substrate is about 593 to 700 ° C., and the actually usable temperature is 600 ° C. or less. In addition, the reactor body of the reaction vessel is made of quartz or the like to prevent internal contamination, and in order to increase the pressure in the reaction vessel, the reaction vessel is housed in a steel sealed vessel that can withstand high pressure, The pressure inside and outside the reaction vessel is made equal.
[0004]
FIG. 2 is a cross-sectional view of a conventional heating device. In the figure, reference numeral 1 denotes a reaction vessel having a closed bowl-shaped cylindrical shape that accommodates an object to be heated and whose bottom can be opened. As described above, the reaction vessel 1 is made of quartz or the like, and is composed of an upper structure 1a and a bottom structure 1b. A seal 1c is sandwiched between the upper structure 1a and the bottom structure 1b. The bottom structure 1b is opened during storage and removal. The upper structure 1a has a dish-shaped ceiling and has a fastening flange projecting outward in a cylindrical shape with an open lower end. The bottom structure 1b is dish-shaped at the top, has a cylindrical shape with an open lower end, and has a fastening flange projecting outward. The height is lower than that of the upper structure 1a, and the bottom structure 1b is replaced with the upper structure 1a. The reaction vessel 1 is configured by insertion. A multistage holder 4 is mounted on the bottom structure 1 b of the reaction vessel 1, and an object to be heated 5 such as a glass substrate is placed on the holder 4. 2 is a heater container. The heater container 2 surrounds the reaction container 1 so as to be covered from above, and has a vertical cylindrical shape with the lower part opened. The heater container 2 is made of a heat insulating material, and the heater 2a is attached to the inner wall and the ceiling on the inner surface. In addition to the heater vessel 2, the heater 2a is also provided inside the bottom structure 1b of the reaction vessel 1, and heats the reaction vessel 1 from the upper and lower surfaces and the peripheral surface.
[0005]
3 is an airtight container. The hermetic container 3 is a pressure vessel made of steel and includes an upper structure 3a and a bottom structure 3b, and can be opened by releasing the fastening. The upper structure 3a has a dish-shaped ceiling, has a lower end open, and has a fastening flange projecting outward. The bottom structure 3b is dish-shaped at the bottom, and has a fastening flange that is open at the top and projects outward. A steam generator 6 stores hot water therein and is heated by a heater 2a provided below to generate water vapor. Reference numeral 7 denotes a water introduction pipe for supplying water to the generator 6. 8a is a pressure-increasing air introduction pipe, and 8b is a pressure-lowering air discharge pipe. 9a is a gas introduction pipe for introducing a reaction gas such as oxygen into the reaction vessel 1, and 9b is a gas discharge pipe. Reference numeral 10 denotes a water jacket through which cooling water circulates.
[0006]
[Problems to be solved by the invention]
Since the seal 1c sandwiched between the flange of the upper structure 1a and the flange of the lower structure 1b of the reaction vessel 1 is made of rubber with an O-ring, it has only a heat resistance of about 200 ° C. at most. Therefore, as shown in the figure, a seal cooling jacket 12 is provided between a pair of upper and lower flanges to cool the seal 1c so that the temperature does not exceed 200 ° C. In addition, 12a is a cooling water introduction pipe, 12b is a cooling water discharge pipe.
[0007]
However, the cooling by the cooling jacket 12 has to improve heat transfer from the jacket 12 to the flange and the seal 1c, and thus the adhesion between the jacket 12 and the flange must be improved. Partially overheated and the seal 1c deteriorates. In addition, since the inside of the sealed container is set to a high pressure, the jacket 12 and the pipe 12a are provided with pressure resistance, which is expensive. Further, when a gas containing water vapor is introduced into the reaction vessel 1, a gap formed between the outer periphery of the bottom structure 1 b and the upper structure 1 a, and a portion inside the seal 1 c is cooled. For this reason, the water vapor in the reaction vessel 1 is condensed and drainage is accumulated, but once the drainage is accumulated, the gap is kept at a low temperature of 200 ° C. or less, and it is found that there is no need to introduce cold water into the jacket 12.
[0008]
The present invention has been devised in view of such problems of the prior art and based on the above knowledge, and provides a heating device that does not require the seal cooling jacket 12 and is excellent in the cooling performance of the seal 1c. With the goal.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the heating device of the present invention includes a sealed bowl-shaped cylindrical shape that accommodates an object to be heated, a bottom that can be opened and a gas containing water vapor introduced thereinto, and the reaction container from above. A heating apparatus comprising a vertical cylindrical heater container that is open at the bottom to be covered and a vertical cylindrical container that accommodates these containers and that can be opened at the bottom, The reaction vessel has a cylindrical structure with the upper part sealed and the lower part open and has a flange projecting outward at the lower end, and a cylindrical structure with the upper part sealed and the lower part opened, and a flange projecting outward at the lower end. A lower structure inserted from below into the upper structure, and a seal sandwiched between the flange of the upper structure and the flange of the lower structure, and the outer periphery of the bottom structure And the superstructure The seal inside the gap formed between the inner periphery which are connected Note, the discharge pipe.
[0010]
It is preferable that a gas of 1 to 50 atm is enclosed in the reaction vessel and the sealed vessel.
[0011]
Next, the operation of the present invention will be described.
An object to be heated is accommodated in a reaction vessel, and water is poured into a gap inside the seal formed between the outer periphery of the bottom structure and the inner periphery of the upper structure before heating by the heater is started. Although the inside of the reaction vessel is heated up to the heating temperature by heating with the heater, the gap portion is not heated by the heater, and only heat transfer from the wall surface of the reaction vessel makes the amount of heat input to the injected portion small. While the reaction vessel is kept at the heating temperature, the water accumulated in this gap evaporates, so water is replenished. Water vapor is introduced as an oxidizing gas into the reaction vessel, and the partial pressure of water vapor is high, so that the amount of water accumulated in the gap is small. Since latent heat is taken away by evaporation, the temperature of water does not become higher than the saturation temperature corresponding to the water vapor partial pressure in the reaction vessel, and is kept below the heat resistant temperature of the seal. Further, since water is accumulated in the gap, it is possible to reduce the amount of water vapor introduced into the reaction vessel at the low temperature portion.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the heating apparatus of the present invention. In this figure, parts common to those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted. The heating device of the present invention has a sealed bowl-shaped cylindrical shape that accommodates an object to be heated 5 therein, a reaction vessel 1 that can be opened at the bottom and introduced with a gas containing water vapor, and an enclosure that covers the reaction vessel 1 from above. A vertical cylindrical heater container 2 having an open bottom, and a pressure-resistant hermetic container 3 having a vertical cylindrical shape that accommodates these containers and having a bottom that can be opened. The reaction vessel 1 has an upper structure 1a having a cylindrical shape with an upper portion sealed in a dish shape and an open lower portion and a flange projecting outward at a lower end, and a cylindrical shape with an upper portion sealed in a dish shape and an open lower portion. A bottom structure 1b having a flange projecting outward at the lower end and having a height lower than that of the upper structure 1a and inserted into the upper structure from below; a flange of the upper structure 1a and a flange of the bottom structure 1b; A water supply pipe 13a and a drain pipe 13b are connected to a gap 15 inside the seal 1c formed between the outer periphery of the bottom structure 1b and the inner periphery of the upper structure 1a. It is. Reference numeral 14 denotes water accumulated in the gap 15, and reference numeral 16 denotes a heat dissipation lid. The heat dissipating cover 16 closes the hole 2b provided in the ceiling portion of the heater container 16, and is opened when the heating object 5 is naturally cooled to naturally cool the object 5 to be heated. It is provided to actively circulate and promote cooling of the object to be heated.
[0013]
Next, the operation of this embodiment will be described.
The object to be heated 5 is accommodated in the reaction vessel 1, and water is poured into a gap 15 inside the seal 1c formed between the outer periphery of the bottom structure 1b and the inner periphery of the upper structure 1a before heating by the heater 2a. Accumulate water 14. The inside of the reaction vessel 1 is heated up to a heating temperature of about 600 ° C. by heating with the heater 2a, but the gap 15 is not heated by the heater 2a, and only the heat transfer from the wall of the reaction vessel 1 is poured. The amount of heat input to the portion 14 is small. While the reaction vessel 1 is maintained at the heating temperature, the water 14 accumulated in the gap evaporates, so water is replenished through the water injection pipe 13a. Since water vapor is introduced into the reaction vessel 1 as an oxidizing gas and the water vapor partial pressure is high, the evaporation amount of the water 14 accumulated in the gap 15 is small. Since latent heat is removed by evaporation, the temperature of water does not become higher than the saturation temperature corresponding to the water vapor partial pressure in the reaction vessel, and is kept below the heat resistance temperature of the seal 1c. Further, since water is accumulated in the gap 15, the amount of water vapor introduced into the reaction vessel 1 in the low temperature portion can be reduced.
[0014]
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention.
[0015]
【The invention's effect】
As described above, the heating device of the present invention is poured into the gap formed between the outer periphery of the bottom structure of the reaction vessel and the inner periphery of the upper structure, connected to the drainage pipe, and during the heating of the reaction vessel, Since water is stored in the gap, the seal between the upper structure and the bottom structure of the reaction vessel is not overheated and deteriorated, and the reliability is improved. It has excellent effects such as being able to reduce the amount of condensation.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a heating apparatus according to the present invention.
FIG. 2 is a cross-sectional view of a conventional heating device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reaction container 1a Top structure 1b Bottom structure 1c Seal 2 Heater container 3 Sealed container 5 Heated object 13a Water injection pipe 13b Drain pipe 15 Crevice

Claims (5)

A closed bowl-shaped cylinder that contains an object to be heated inside, the bottom of which can be opened, and a reaction vessel into which a gas containing water vapor is introduced, and surrounding the reaction vessel so as to be covered from above through a required gap , A heating apparatus having a vertical cylindrical heater container opened at the bottom, and a pressure-tight sealed container having a vertical cylindrical shape capable of releasing these bottoms, which accommodates these containers. upper cylindrical lower portion is closed has been released by the swollen ceiling dished upwardly, an upper container having a flange that projects outwardly at the lower end, top the bottom is sealed by a ceiling of swollen dished upward has a lower end at a released cylindrical flanges outwardly flared lower than the above upper container height, and a bottom container to be inserted from below into the upper container, the flange and the bottom vessel of the upper container flange Sea sandwiched between Consists of a, the subjected between both flanges have a gap, outboard gap of the seal inside have been sealed by the sealing of both flanges from between the lower portion of the lower and the bottom vessel of the upper chamber The heating apparatus is characterized in that water can be stored in the water supply pipe, and a water injection pipe for injecting water into the gap and a drain pipe for draining water in the gap are connected .   The heating apparatus according to claim 1, wherein a gas of 1 to 50 atm is enclosed in the reaction container and the sealed container. A reaction vessel in which an object to be heated is accommodated and a gas containing water vapor is introduced, a heater vessel that surrounds the reaction vessel so as to be covered from above through a required gap, and a lower portion is opened, and the vessel In the heating apparatus having a pressure-tight airtight container that can release the bottom, the reaction container is composed of an upper container and a bottom container , each having a flange at the lower end, and the bottom container is in the upper container . It has adapted to be inserted from below into, with sandwiching the seal so as to form a gap between the flange of the flange and the bottom vessel of the upper container, between an inner periphery of the outer peripheral and upper container bottom container forming a gap communicating with the gap between the upper Symbol flanges, the device is water injection into the gap prior to heating by a heater, cooling the seal by the latent heat of evaporation of the water accumulated in the gap during heating apparatus Characterize Heat method.   The heating method according to claim 3, wherein moisture evaporated from the gap is replenished while the apparatus is maintained at a heating temperature.   The heating method according to claim 3 or 4, wherein a gas pressure in the reaction vessel and the sealed vessel is set to 1 to 50 atmospheres.

Images