JP2868853B2 - Heat treatment equipment - Google Patents

Description

The present invention relates to a heat treatment apparatus.

2. Description of the Related Art Conventionally, in a reaction apparatus for a film forming reaction performed under a constant pressure with gas in a semiconductor manufacturing process, a flow control valve provided in an exhaust pipe is adjusted to maintain the inside of the apparatus at a constant pressure. As described above, Japanese Patent Application Laid-Open Nos.
3-238281 and JP-A-63-304620.

However, in a film forming apparatus such as a heat treatment apparatus of a semiconductor manufacturing apparatus, if a reaction performed in the apparatus is not performed under a certain condition, a formed film thickness becomes non-uniform, and a yield of semiconductor elements is reduced. Would. Therefore, even in the exhaust device connected to the heat treatment device, the pressure in the exhaust pipe must be delicately controlled to maintain the inside of the heat treatment device at a constant pressure.

By the way, a plurality of heat treatment apparatuses are usually installed, and the exhaust device is connected to the exhaust system of the entire factory and exhausted by a powerful fan. Therefore, when only a part of the heat treatment apparatus is driven, the exhaust system is too strong, and the negative pressure in the exhaust pipe increases, which greatly affects the pressure in the heat treatment apparatus.

Therefore, a branch pipe is provided in the exhaust pipe of the exhaust device, and a valve arranged perpendicular to the direction of gravity is provided in the branch pipe. When the pressure difference between the atmospheric pressure and the pressure in the exhaust pipe reaches a predetermined value or more (exhaust pipe). If the pressure in the pipe is too low) A valve is pushed up by the atmospheric pressure, the atmosphere enters the exhaust pipe, and an exhaust pressure adjusting device that can be automatically opened and closed automatically in advance so that the pressure of the exhaust pipe rises. It has been developed.

[Problem to be Solved by the Invention] However, even with such an exhaust device, for example, −1 mmH ₂ O is used to open and close the valve weight in response to the difference between the exhaust pipe internal pressure and the atmospheric pressure. It is difficult to make it work, and if the factory exhaust system becomes significantly negative pressure, the valve will be completely open and it will not be possible to maintain the desired constant pressure in the exhaust pipe, and the heat treatment equipment Pressure fluctuates, and the film thickness becomes uneven.

The present invention has been made in order to solve the above-described drawbacks, and keeps the exhaust pipe internal pressure of an exhaust device constant, and the pressure is excessively reduced even when connected to an exhaust system such as a factory exhaust system. Without pressure, the pressure in the exhaust pipe can be kept constant with respect to fluctuations in the factory exhaust system. Therefore, an object of the present invention is to provide a heat treatment apparatus capable of improving the quality of a product because the pressure in the reaction apparatus is kept constant and the reaction is performed under constant conditions.

[Means for Solving the Problems] In order to achieve the above object, in a heat treatment apparatus provided with a reactor for performing a process at a high temperature and an exhaust device for exhausting gas discharged from the reactor, the exhaust device comprises: A branch pipe provided with a movable valve that is provided in an exhaust pipe connected to the reaction device and that is opened by the external pressure when the pressure difference between the outside air pressure and the inside of the exhaust pipe becomes a predetermined value or more and allows the air to flow into the exhaust pipe; And a second pressure regulating valve provided downstream of the branch pipe, wherein the first pressure regulating valve regulates the internal pressure of the exhaust pipe upstream thereof to a predetermined pressure. The second pressure regulating valve is set at a predetermined difference from the pressure regulated by the first pressure regulating valve, and regulates the pressure in the branch pipe to a pressure at which the movable valve operates normally.

[Operation] When the difference between the pressure in the exhaust pipe and the outside air pressure exceeds a predetermined value (when the inside of the exhaust pipe is excessively depressurized), the outside air is opened by being pushed by the outside air pressure against its own weight. A tributary pipe provided with an automatic opening / closing valve capable of inflowing and increasing the internal pressure of the exhaust pipe to a predetermined value is provided in the exhaust pipe of the exhaust device. By providing pressure regulating valves upstream and downstream of the branch pipe and adjusting the gas flow rate in the exhaust pipe, the valve provided in the branch pipe can be operated under the best conditions, and the difference between the reaction pipe and the outside air pressure To a desired constant pressure.

Embodiment An embodiment in which the heat treatment apparatus of the present invention is applied to a heat treatment apparatus in a semiconductor manufacturing process will be described below with reference to the drawings.

The reaction apparatus 1 shown in FIG. 1 includes a cylindrical process tube 5, and a mounting table 4 on which a quartz boat 3 supporting a semiconductor wafer 2 to be processed is mounted. The process tube 5 is surrounded by, for example, a cylindrical resistance heating coil heater 6,
The opening is closed by the lid 7 so that the inside of the process tube 5 can be appropriately heated to 500 to 1200 ° C. A reaction gas supply port 10 connected to a reaction gas supply system 9 via a flow meter 8 is provided at an upper portion of the process tube 5, and a reaction gas exhaust port 12 connected to an exhaust device 11 is provided at a lower portion of the process tube 5. The surplus reaction gas or the mixed gas G of the reaction product gas, which has been subjected to a process such as film formation on the semiconductor wafer 2, flows into the exhaust device 11 from the exhaust port 12. The exhaust device 11 includes an exhaust pipe 13 connected to the exhaust port 12 of the heat treatment apparatus 1 and a branch pipe 14 provided in the exhaust pipe 13.
And first and second provided upstream and downstream of the branch pipe 14.
Pressure regulating valves 15-1 and 15-2 are provided. Each of the pressure regulating valves 15-1 and 15-2 is provided with a differential pressure gauge 16-1 or 16-2 such as a manometer. The branch pipe 14 has one end connected to the exhaust pipe 13 as shown in FIG.
The other end is bent so that the axis is vertical. A large-diameter portion 18 is provided in the vertical portion 17, and the large-diameter portion 18
The ring 19 is attached, and the movable valve 20 is arranged on the O-ring 19. The movable valve 20 has, for example, a pressure difference between the outside air pressure and the exhaust pipe 13 −
If 10 mmH ₂ O is desired, 1 atmosphere = 10000 mmH ₂ O = 1 kg / cm ²
Therefore, the weight may be 1 g / cm2. The weight of the movable valve 20 is adjusted depending on the material and the thickness.

A large number of heat treatment apparatuses 1 having such an exhaust device 11 are usually installed in a factory, and the exhaust pipes 13 of these exhaust devices 11 are respectively connected to an exhaust system fan 21 having a large exhaust capacity such as a factory exhaust system. Connected via 22.

The operation of the exhaust device of the heat treatment apparatus having such a configuration will be described.

A case will be described in which only one of the plurality of heat treatment apparatuses 1 is operating and the others are stopped. A predetermined amount of the reaction gas supplied from the reaction gas supply system 9 is measured by the flow meter 8 and a predetermined amount of the reaction gas is supplied to the reaction gas supply port of the process tube 5.
Supplied from 10. The semiconductor wafer 2 is processed in the process tube 5 heated to, for example, 1000 ° C. by the coil heater 6. After the treatment, the excess mixed gas G of the reaction gas and the generated gas flows from the exhaust port 12 into the exhaust pipe 13. At this time,
The other heat treatment apparatus 1 is not operated, so that the mixed gas G does not flow to the other exhaust device, so that the ratio of the flow rate of the mixed gas G to the exhaust capacity of the exhaust fan 21 decreases. Branch pipe 14
If it is the action of only the movable valve 20 of, even desired differential pressure of the exhaust pipe pressure, for example -1~0mmH ₂ O or less, not moving to the negative pressure in the exhaust pipe 13 becomes very large. For example -10mmH ₂
When the pressure becomes O or less, the movable valve 20 provided in the branch pipe 14 is pushed by the outside air pressure and floats from the O-ring 19. Then, the outside air flows into the exhaust pipe 13, and the exhaust pipe 13 is
It is kept at 10mmH ₂ O. At this time, the pressure regulating valve 15-1 provided upstream of the branch pipe 14 of the exhaust pipe 13 is adjusted to adjust the mixed gas G
And the detected value of the differential pressure gauge 16-1 is the desired -1 to 0 m
to be mH ₂ O. The pressure regulating valve 15-2 downstream of the branch pipe 14 is connected to the exhaust pipe with the opening of the branch pipe 14 closed.
13 is to show the desired differential pressure for example -15~-20mmH ₂ O, adjusted while detecting the detection value of the differential pressure gauge 16-2. By adjusting the pressure adjusting valves 15-1 and 15-2 as described above, the pressure adjustment performed in the branch pipe 14 can be performed under optimal pressure conditions.

Therefore, the movable valve 20 of the branch pipe 14 always operates at the optimum pressure condition of about −10 mmH ₂ O, and by adjusting the pressure regulating valve 15-1, the upstream part of the pressure regulating valve 15-1 is brought to a desired pressure. Can be held. By appropriately adjusting the pressure control valve 15-2 in relation to the factory exhaust system and the device to be operated, heat treatment is also performed under a constant condition regardless of the pressure variation caused by the variation of the suction force by the factory exhaust system. be able to.

As another embodiment, as shown in FIG.
The pressure control valves 150-1 and 150-1 are output by the outputs of 0-1 and 160-2.
50-2 may be automatically driven to perform feedback control.

The present invention is not limited to the above embodiment, and is applicable to a single device without being connected to a factory exhaust system. Further, the present invention is not limited to a heat treatment apparatus, and can be suitably used for an apparatus for performing processing while maintaining a constant reaction pressure, such as a CVD apparatus or a spin coater apparatus for applying a processing liquid such as a resist.

[Effects of the Invention] As is clear from the above description, the heat treatment apparatus of the present invention can be used for the upstream and downstream of the branch pipe having a movable valve that operates when the differential pressure between the outside air pressure and the exhaust pipe increases. The pressure adjustment valve provided at the outlet allows the pressure adjustment performed in the branch pipe to be performed under the optimal pressure condition, thereby maintaining the pressure inside the exhaust pipe with high accuracy and uniformity, and thus maintaining the pressure inside the reactor at a desired constant pressure. it can. Therefore, uniform processing of the semiconductor wafer can be performed, and high-quality products can be manufactured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
It is a figure showing an important section of one example shown in a figure. DESCRIPTION OF SYMBOLS 1 ... Reactor 11 ... Exhaust device 13 ... Exhaust pipe 14 ... Branch pipe 15-1, 15-2, 150-1, 150-2 ... Pressure regulating valve

Claims (1)

(57) [Claims] 1. A heat treatment apparatus comprising: a reactor for performing a process at a high temperature; and an exhaust device for exhausting gas discharged from the reactor, wherein the exhaust device is connected to an exhaust pipe connected to the reactor. A tributary pipe provided with a movable valve which is opened by the external pressure and allows the air to flow into the exhaust pipe, and a first tributary pipe provided upstream of the tributary pipe when the pressure difference between the external pressure and the exhaust pipe becomes equal to or more than a predetermined value. A pressure regulating valve and a second pressure regulating valve provided downstream of the branch pipe,
The first pressure regulating valve regulates the internal pressure of the exhaust pipe upstream thereof to a predetermined pressure, and the second pressure regulating valve is set to a prescribed difference from the pressure regulated by the first pressure regulating valve. The pressure in the tributary pipe is adjusted to a pressure at which the movable valve operates normally.