JPH11354515A - Pressure type heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of a temperature in a pressure type heating furnace, and to accurately control a pressure. SOLUTION: This pressure type heating furnace is composed of a closed container 1, heater 2 arranged in the closed container 1, reaction container 3 to be heated by the heater 2, and evaporator 4 arranged at the lower part of the reaction container 3 for supplying steam evaporated inside to the reaction container. In this case, in a gas supplying tube 6 for supplying gas to the reaction container 3 and a gas ejecting tube 7 for ejecting gas from the reaction container, a part between a control valve 9 and the reaction container 3 is heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace used for heat treatment of semiconductors and the like, and more particularly to a heating furnace used for heat treatment of a thin film transistor formed on a glass substrate for producing a liquid crystal display, an image sensor and the like. About.

[0002]

2. Description of the Related Art Annealing furnaces, diffusion furnaces, oxidation furnaces, and the like for processing semiconductor films formed on silicon wafers and substrates.
Low pressure CVD (Chemical Vapor Deposit) for film formation
Heating furnaces such as ion) have been widely used. In recent years, the mainstream of these heating furnaces is 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 space in the apparatus. Has become. In the oxidation furnace, a high pressure-dependent rate can be obtained by increasing the gas atmosphere in the reaction tube to a high pressure (for example, disclosed in JP-A-53-112064 and JP-A-56-24938). It 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 instead of a conventional round silicon wafer is required.

Further, when processing a glass substrate, it is necessary to process at a temperature that does not affect the glass substrate. Usually, non-alkali 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 593 to
About 700 ° C, the actual usable temperature is 600 ° C
Therefore, processing at 600 ° C. or lower is required.

[0004]

In such a pressurized heating furnace, the gas to be introduced is usually supplied at room temperature, so that the temperature near the inlet decreases and the uniformity in the furnace deteriorates. . In addition, when introducing steam into the reaction vessel of the heating furnace, dew condensation is likely to occur in the vicinity of the supply / exhaust port or in the gas discharge pipe. For example, when the inside of the heating furnace is pressurized to 25 atm, the saturated steam temperature at that time is 223 ° C. Below this temperature, the steam condenses and forms dew. Resulting in. Then, when dew condensation occurs, the volume of the steam is rapidly reduced, so that no matter how much steam is supplied, the pressure cannot be increased, and the pressure cannot be controlled.

The present invention has been devised in view of the above-mentioned problems of the prior art. The present invention has been proposed to improve the uniformity of heat in a furnace of a pressurized heating furnace and to reduce the pressure in a heat treatment of a thin film transistor or the like using steam. It is an object of the present invention to provide a heating type heating furnace which can be controlled easily and accurately.

[0006]

In order to achieve the above object, a pressurized heating furnace according to the present invention comprises a closed vessel, a heater disposed in the closed vessel, a reaction vessel heated by the heater, A gas supply pipe and a gas exhaust pipe with a control valve for supplying and exhausting gas to and from the reaction vessel, an evaporator provided below the reaction vessel to supply water vapor evaporated inside into the reaction vessel, and pure water Pressurized heating furnace having a pure water supply pipe for supplying gas, wherein the gas supply pipe and the gas discharge pipe are heated between a control valve and a reaction vessel.

It is preferable that the pure water supply pipe for supplying pure water to the evaporator also heats the space between the control valve and the evaporator, since an abrupt temperature change in the evaporator can be avoided.

Since the reaction vessel is made of quartz or the like in order to maintain the internal cleanliness, the pressure in the closed vessel and the pressure in the reaction vessel are controlled so as to be substantially equal in order to eliminate the pressure difference between the inside and the outside. Pressure to increase the reaction rate
Adjust to 50 atm.

Next, the operation of the present invention will be described. By heating the gas supply pipe that supplies gas into the reaction vessel, the temperature of the gas to be introduced approaches the temperature inside the reaction vessel,
Good uniformity of temperature in the reaction vessel can be maintained.

[0010] Since the gas discharge pipe for discharging gas from the inside of the reaction vessel is heated, dew condensation in the gas discharge pipe is prevented and the volume due to condensation can be prevented, so that the pressure in the reaction vessel can be easily controlled. And accurately.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing the flow of the pressurized heating furnace of the present invention. In the figure,
Reference numeral 1 denotes an airtight container, which is made of stainless steel and comprises an upper container 1a and a lower container 1b, between which an airtight seal 5 is sandwiched. Reference numeral 2 denotes a cylindrical heater, which is disposed in the closed vessel 1 and has a heating element such as a Kanthal wire embedded in a refractory brick or the like. Reference numeral 3 denotes a reaction vessel, which is made of quartz or the like, is heated by the heater 2, is composed of an upper vessel 3a and a lower vessel 3b, and holds an airtight seal 5 therebetween. A substrate holder (not shown) that accommodates a glass substrate or the like is provided in the reaction container 3. Reference numeral 4 denotes an evaporator which is provided below the reaction vessel 3 and supplies the water vapor evaporated therein into the reaction vessel 3. The evaporator 4 is provided with an evaporator 4 a and a superheater tube 4 b disposed thereon and surrounding them. Heater 4c.

Reference numeral 6 denotes a gas supply pipe for supplying a gas into the reaction vessel 3. The gas supply pipe supplies a reaction gas via a pressure reducing valve 11, a flow meter 12 and a control valve 9 by a gas cylinder 10. Reference numeral 7 denotes a gas discharge pipe for discharging gas from the reaction vessel 3, and a control valve 9 is provided on the outlet side.

Reference numeral 8 denotes a pure water supply pipe for supplying pure water to the evaporator 4. The pure water is supplied by a pump 13 through a control valve 9.

Reference numeral 14 denotes a heater. The gas supply pipe 6 and the gas discharge pipe 7 are connected between the control valve 9 and the reaction vessel 3 by the heater 1.
The pure water supply pipe 8 is heated by the heater 14 between the control valve 9 and the evaporator 4.

Reference numeral 15 denotes an air supply pipe for supplying pressurized air to the closed vessel 1 in order to eliminate a pressure difference between the inside and outside of the reaction vessel 3. To supply pressurized air. 1
Reference numeral 6 denotes an air discharge pipe for discharging pressurized air from the closed container 1, and a control valve 9 is provided on the outlet side.

Next, the operation of the present embodiment will be described. In order to heat-treat a glass substrate or the like by the main heating furnace, the closed vessel 1 and the reaction vessel 3 are opened, and a substrate holder (not shown) is accommodated in the reaction vessel 3. When the glass substrate is oxidized by steam, pure water is supplied to the evaporator 4 a of the evaporator 4 by the pump 13 via the control valve 9 and the pure water supply pipe 8. The water vapor heated by the heater 4c and evaporated in the evaporator 4a becomes superheated steam by the superheat pipe 4b, and is supplied into the reaction vessel 3. The inside of the reaction vessel 3 is heated to 300 to 600 ° C. by the heater 2 and heat treatment of the glass substrate is performed. When a glass substrate is heat-treated in an inert gas atmosphere such as nitrogen, a pressure reducing valve 1
1. Nitrogen gas is supplied into the reaction vessel through the gas supply pipe 6 via the flow meter 12 and the control valve 9.

The reaction vessel 3 is made of quartz or the like in order to prevent contamination of the glass substrate, and cannot withstand high pressure. Therefore, the pressure in the closed vessel 1 is reduced to the same pressure of 1 to 50 atm as in the reaction vessel 3. Apply pressure. Therefore, pressurized air is supplied from the air cylinder 17 through the pressure reducing valve 11, the flow meter 12, and the control valve 9 through the air supply pipe 15.

When the heat treatment is completed, the pressure inside the reaction vessel 3 and the closed vessel 1 is reduced by exhausting the gas through the gas exhaust pipe 7 and the air exhaust pipe 16 while adjusting the pressure by the control valve 9.
After the pressure in the container reaches the atmospheric pressure, the container is opened and the substrate holder containing the glass substrate is taken out.

In the present invention, the gas supply pipe 6 for supplying gas into the reaction vessel 3 is heated to bring the temperature of the gas to be introduced close to the temperature inside the reaction vessel 3, so that the temperature uniformity within the reaction vessel 3 is improved. Can be kept good.

Since the gas discharge pipe 7 for discharging gas from the reaction vessel 3 is heated, dew condensation in the gas discharge pipe 7 can be prevented, thereby easily controlling the pressure in the reaction vessel.
And it can be performed accurately.

The present invention is not limited to the embodiment described above, and various changes can be made without departing from the gist of the invention.

[0022]

As described above, the pressurized heating furnace of the present invention heats the gas supply pipe for supplying gas to the reaction vessel, so that the temperature inside the reaction vessel can be kept uniform. Because the gas exhaust pipe that exhausts gas from the reaction vessel is heated, there is no condensation in the gas exhaust pipe, and excellent pressure control in the reaction vessel can be easily and accurately performed. Having.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the flow of a pressurized heating furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed container 2 Heater 3 Reaction container 4 Evaporator 6 Gas supply pipe 7 Gas discharge pipe 8 Pure water supply pipe 9 Control valve

Claims (3)

[Claims] 1. A closed vessel, a heater disposed in the closed vessel, a reaction vessel heated by the heater, a gas supply pipe with a control valve for supplying and exhausting gas to and from the reaction vessel, and a gas exhaust pipe. A pressurized heating furnace having an evaporator provided below the reaction vessel to supply water vapor evaporated inside into the reaction vessel, and a pure water supply pipe for supplying pure water to the evaporator. The pressurized heating furnace wherein the gas supply pipe and the gas discharge pipe are heated between the control valve and the reaction vessel. 2. The pressurized heating furnace according to claim 1, wherein the pure water supply pipe for supplying pure water to the evaporator is heated between a control valve and the evaporator. 3. The pressurized heating furnace according to claim 1, wherein the pressure in the closed vessel and the pressure in the reaction vessel are controlled to be substantially equal, and the pressure is 1 to 50 atm.