JP2000174028A - Heat treatment equipment and method of taking out treated object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the processing time required for heat treatment without impairing safety. SOLUTION: Air in an N2 purge chamber 2 adjacent to a process tube 1 is replaced with N2, to reduce the concentration of oxygen to a specified low value. With a processing gas being supplied to the process tube 1, a work piece 10 after heat treatment is carried out of the process tube 1 into the N2 purge chamber 2, while being kept at a high temperature. At this time, the processing gas is diluted at a stroke with a constant quantity of N2 with which the N2 purge chamber 2 is filled, to a concentration just short of explosion limit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for performing a heat treatment on an object in a semiconductor manufacturing process or the like.

[0002]

2. Description of the Related Art In a heat treatment in a semiconductor manufacturing process, when an object to be processed is, for example, a GaAs wafer, a good heat treatment is not carried out while supplying a predetermined processing gas into a process tube accommodating the object to be processed. No processing result is obtained. In this case, since the process gas used is flammable, the process tube is sealed to prevent gas leakage. After performing the heat treatment for a predetermined time, the heater is stopped to reduce the temperature of the processing object while supplying the processing gas.
The reason why the processing gas is supplied at this time is that the processing result is deteriorated if the processing gas is removed from the processing target still in a high temperature state immediately after the heat treatment. Next, the supply of the processing gas is stopped, the processing gas in the process tube is sufficiently replaced with an inert gas, and then the object to be processed is taken out of the process tube. At this time, since the inside of the process tube is filled with the inert gas, there is no danger of explosion.

[0003]

In the conventional heat treatment apparatus as described above, it takes a certain time to lower the temperature of the object to be processed and to replace the gas in the process tube even after the heat treatment. Therefore, the object cannot be taken out of the process tube immediately after the heat treatment. This hinders the shortening of the heat treatment process time, and the number of objects to be heat treated in a predetermined time is limited. In view of the above-mentioned conventional problems, an object of the present invention is to reduce a process time required for heat treatment without impairing safety.

[0004]

According to the present invention, there is provided a method for removing an object to be processed by a heat treatment apparatus, wherein the object to be processed is heat-treated in a process tube of the heat treatment apparatus while supplying a processing gas, and the object is disposed adjacent to the process tube. The air in the purge chamber is replaced with an inert gas to reduce the oxygen concentration to a predetermined low concentration value, and while supplying the processing gas, the heat-treated object is kept in a high temperature state from the process tube to the purge chamber. The process gas is carried out, the process gas is diluted with an inert gas filled in the purge chamber, and the carried out work is taken out of the heat treatment apparatus (claim 1).

[0005] In the method for removing an object to be treated, the air in the purge chamber is replaced by an inert gas, and the oxygen concentration in the purge chamber becomes a predetermined low concentration value and is substantially filled with the inert gas. The heat-treated object is immediately carried out of the process tube to the purge chamber in a high temperature state. At this time, since the processing gas is continuously supplied, the high-temperature processing object is exposed to the processing gas even during unloading. Although the processing gas leaks into the purge chamber by carrying out, the concentration of the processing gas in the gas in the heat treatment apparatus is diluted by the inert gas filled in the purge chamber. Thereafter, the object is taken out of the heat treatment apparatus.

Further, the heat treatment apparatus of the present invention comprises a process tube into which a processing gas is continuously supplied and discharged, and a processing object to be subjected to a heat treatment is carried in; a heater for heating the processing object in the process tube; A purge chamber that is provided adjacent to the process tube and receives the object to be processed after the heat treatment in a state where the oxygen concentration has been reduced to a predetermined low concentration value by replacing the internal air with an inert gas in advance. And a loading device for loading and unloading the workpiece between the purge chamber and the inside of the process tube (claim 2).

[0007] In the above heat treatment apparatus, a processing gas is supplied to the process tube to heat-treat the object to be processed. On the other hand, the air in the purge chamber is replaced by the inert gas, and the oxygen concentration in the purge chamber becomes a predetermined low concentration value and is substantially filled with the inert gas. The heat-treated object is immediately carried out of the process tube to the purge chamber by the loading device in a high-temperature state, but the processing gas is still supplied at this time. It is taking gas. Although the processing gas leaks into the purge chamber by carrying out, the concentration of the processing gas in the gas in the heat treatment apparatus is diluted by the inert gas filled in the purge chamber. Thus, the object to be processed is ready to be taken out of the heat treatment apparatus.

[0008]

FIG. 1 is a diagram showing a configuration of a heat treatment apparatus according to an embodiment of the present invention. The heat treatment apparatus is a vertical furnace, and mainly includes an upper process tube 1.
, A lower N ₂ purge chamber 2, and a heater 3 provided to surround the process tube 1. A process exhaust pipe 4 is connected to an upper portion of the process tube 1. 9% H ₂ / N in process tube 1
A gas line 5 for supplying the _second processing gas (flammable) is connected. On the other hand, the N ₂ purge chamber 2 is connected with dilution N ₂ lines 6 and 7 divided into two systems from an N ₂ supply source. An oxygen concentration meter 9 is connected to the N ₂ purge chamber 2 via a pipe 8. The gas line 5, the diluent N ₂ line 6 and 7 and conduit 8 is equipment of the air valve and the like are connected, is omitted here.

The workpiece 10 is carried into the process tube 1 from the N ₂ purge chamber 2 by the lifting device L as a loading device, and is carried out from the process tube 1 to the N ₂ purge chamber 2. When the loading of the workpiece 10 is completed, the process tube 1 and the N ₂ purge chamber 2 are shielded from each other by the shielding unit 13 with the operation of the lifting / lowering device L. Further, at the time of unloading, the shielding is automatically released with the lowering operation of the lifting / lowering device L, and the process tube 1 and the N ₂ purge chamber 2 are in a state where they can communicate with each other.

FIG. 2 is an exhaust piping system (including a part of the intake piping) shown in a block diagram in accordance with the actual structure of the heat treatment apparatus. The process tube 1 and the heater 3
Are housed in an upper heater box 11, and an N ₂ purge chamber 2 is housed in a lower N ₂ purge box 12 with a shielding portion 13 therebetween when the transfer of the workpiece is completed. The exhaust pipe of the process tube 1 is connected to the above-described process exhaust pipe 4 via a manual valve 15 and an air valve 16 provided in the heater box 11. Also within the heater box 11, the exhaust from the _{N 2} purge chamber 2 valve 17, the air ballast 18 and an exhaust pipe leading to the exhaust stack 20 through the collecting exhaust pipe 19, _{N 2} purge chamber 2 from the needle valve 21, An exhaust pipe to the exhaust pipe 20 via the bypass valve 22 and the collective exhaust pipe 19 is provided. In addition, the exhaust in the heater box 11 is performed from the collective exhaust pipe 23. In addition, _{N 2} purge box 12
Intake valve 24 as N ₂ supply port is provided in the.

Next, the operation of the heat treatment apparatus will be described with reference to FIG.
This will be described with reference to FIG. First, the heater 3
The process tube 1 is heated. In addition, the workpiece 10 is lifted.
The process tube heated by the lowering device L and heated
And carried into the bus 1. At the rising end of the lifting device L,
The process tube 1 is N₂Purge chamber 2 and shield
Masked. In the process tube 1, the gas line 5
9% H₂/ N ₂Process gas is continuously supplied and exhausted
In this state, the heat treatment of the object 10 is performed for a predetermined time.
Done.

Meanwhile, while the heat treatment is taking place, the _{N 2} purge chamber 2 _{N 2} is supplied from the diluent _{N 2} line 6 and 7, the air _{N 2} purge chamber 2 is replaced by _{N 2} You. At this time, the air in the N ₂ purge chamber 2 is exhausted from the exhaust pipe 20 through the needle valve 21 and the bypass valve 22 in the open state. The N ₂ replacement is performed until the oxygen concentration measured by the oxygen concentration meter 9 reaches a predetermined low concentration value (several tens of PPM in this embodiment), and that state is maintained thereafter.

When the heat treatment is completed, the heater 3 is stopped, and after confirming that the oxygen concentration in the N ₂ purge chamber 2 is several tens of PPM, the workpiece 10 is immediately lowered by the lifting device L. In this way, if the carrying-out is performed immediately after the heat treatment, the process time is shortened as compared with the case where the cooling time or the gas replacement time is provided in the process tube 1. The lowering takes a predetermined time, during which the processing gas is being supplied. Therefore, the workpiece 10 still hot is lowered while being immersed in the processing gas. On the other hand, N ₂
N ₂ is also supplied to the purge chamber 2. At this time, the flow ratio between the processing gas and N ₂ is, for example, 1:20.

When the object 10 is carried out of the process tube 1 to the N ₂ purge chamber 2, the shielding portion 13
Move (open), the process tube 1 and the N ₂ purge chamber 2 communicate with each other, and the processing gas leaks into the N ₂ purge chamber 2. However, since the oxygen in the N ₂ purge chamber 2 is eliminated to a predetermined low concentration, there is no possibility of explosion. Since the N ₂ purge chamber 2 is filled with a certain amount of N ₂ , the processing gas (H ₂ / N ₂ ) is diluted from 9% to less than the explosion limit of 4% at a stretch. Next, N ₂
The purge chamber 2 is opened, and the object 10 is taken out into the air. At this time, since the concentration of the processing gas is diluted to less than 4%, there is no danger of explosion even if it touches the outside air, and it is safe. The gas in the N ₂ purge chamber 2 is exhausted via an exhaust valve 17 in an open state and an air ballast 18 adjusted so that the gas pressure in the N ₂ purge chamber is a positive pressure of several hundred Pa. I have. Therefore, when the N ₂ purge chamber 2 is opened, N _{2 and the} like may leak to the outside, but the external air does not enter the N ₂ purge chamber 2 and the process tube 1.

The heat treatment apparatus according to the above embodiment uses 9% H ₂ / N ₂ as a processing gas and N as a diluting gas.
₂ is used, but a similar configuration can be applied when other processing gas or diluent gas is used. For example, if the processing gas is a corrosive gas, when carrying out the workpiece,
With a certain amount of diluent gas, the process gas is diluted to a safe (no risk of corrosion around) gas.
Further, the heat treatment apparatus in the above embodiment is a vertical furnace, but the same configuration can be applied to heat treatment apparatuses of other forms.

[0016]

The present invention configured as described above has the following effects. According to the method for removing an object to be processed by the heat treatment apparatus according to the first aspect, the heat-treated object is immediately carried out from the process tube to the purge chamber in a high temperature state while the processing gas is supplied to prevent deterioration of the processing result. So
The cooling time and the gas replacement time in the process tube become unnecessary, and the process time is shortened accordingly. Although the processing gas leaks into the purge chamber by carrying out, the concentration of the processing gas in the gas in the heat treatment apparatus is diluted by the inert gas filled in the purge chamber, thereby avoiding the danger associated with the properties of the processing gas. The object to be processed can be taken out of the heat treatment apparatus while ensuring safety.

According to the heat treatment apparatus of the present invention, a process tube to which a processing gas is continuously supplied and a purge chamber filled with an inert gas are provided adjacent to the process tube.
Even if the heat-treated object is immediately carried out of the process tube to the purge chamber in a high temperature state, the concentration of the processing gas in the gas in the heat treatment apparatus is diluted by the inert gas filled in the purge chamber. Therefore, the object to be processed can be taken out of the heat treatment apparatus at an early stage while avoiding the danger associated with the properties of the processing gas, and the processing time can be reduced. Further, since the processing gas is continuously supplied, the high-temperature processing object is exposed to the processing gas even during unloading, so that the processing result does not deteriorate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is an exhaust piping system (including a part of intake piping) shown in a block diagram in accordance with the actual structure of the heat treatment apparatus.

[Explanation of symbols]

1 process tube 2 N ₂ purge chamber 3 heater 10 treatment object L lifting device

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F27D 11/02 F27D 11/02 B

Claims (2)

[Claims] 1. An object to be processed is heat-treated in a process tube of a heat treatment apparatus while supplying a processing gas, and an oxygen gas is replaced with an inert gas in a purge chamber adjacent to the process tube to reduce an oxygen concentration to a predetermined value. A low-concentration value, while supplying the processing gas, carrying out the heat-treated object to be processed from the process tube to the purge chamber in a high-temperature state, and filling the purge chamber with the processing gas. A method for removing an object to be processed by a heat treatment apparatus, wherein the object to be processed is diluted with a gas and taken out from the heat treatment apparatus. 2. A process tube to which a processing gas is continuously supplied and discharged and into which a processing object to be subjected to heat treatment is carried in; a heater for heating the processing object in the process tube; A purge chamber for receiving the object to be processed after the heat treatment in a state in which the oxygen concentration is a predetermined low concentration value by replacing the internal air with an inert gas in advance, the purge chamber, A heat treatment apparatus, comprising: a loading device for carrying in / out the object to / from a process tube.