JP5044265B2 - Heat treatment apparatus, heat treatment method, and program for heat treatment apparatus - Google Patents

Description

  The present invention relates to a heat treatment apparatus, a heat treatment method, and a heat treatment apparatus program for performing heat treatment on a workpiece.

  A process tube used in a heat treatment apparatus is required to have high airtightness. The reason is that dangerous gas may be sealed in the process tube, and if the atmosphere is mixed in the process tube, the work may be adversely affected.

Therefore, conventionally, a technique has been proposed in which a process tube is connected to a vacuum evacuation unit and a leak detection unit to perform vacuum evacuation, and then a gas leak inspection of the process tube is performed by blowing gas from the outside (for example, patent Reference 1). According to this technique, it is said that stable heat treatment can be performed by using a process tube determined to have no gas leak.
JP 2005-327764 A

  However, gas leaks in the heat treatment apparatus may also occur due to deterioration over time of the seal part of the furnace port seal part, the piping system around the process tube (from the open / close valve to the open / close valve), each member, and poor assembly during maintenance. Examples of measures for preventing such a gas leak include installing a gas leak detector and periodically providing maintenance time. However, these measures have the following disadvantages. For example, even if a gas leak detector can detect the occurrence of a gas leak, it cannot prevent the gas leak. Further, in order to perform maintenance periodically, it is necessary to periodically stop the heat treatment apparatus.

  The object of the present invention is to easily prevent gas leaks caused by aging of each member used in the furnace port seal part and other piping systems around the process tube and poor assembly during maintenance without stopping the heat treatment apparatus. It is to provide a heat treatment apparatus, a heat treatment method, and a program for the heat treatment apparatus that can be prevented with a simple configuration.

  The heat treatment apparatus according to the present invention includes a process tube having an opening at one end and a sealing means configured to selectively seal the opening, and performs heat treatment on the workpiece enclosed in the process tube. The heat treatment apparatus includes a gas supply unit, a gas discharge unit, a pressure measurement unit, and a control unit.

  The gas supply means is configured to supply atmospheric gas into the process tube via the gas introduction path. The gas discharge means is configured to discharge the gas in the process tube via the gas discharge path. The gas discharge path is preferably provided with a valve that can be opened and closed by a control means. The pressure measuring means is configured to be able to measure the pressure in the process tube. It is preferable to provide two pressure measuring means, one for negative pressure measurement during normal heat treatment and one for fine pressure measurement during gas leak inspection.

  The control means is configured to control operations of the gas supply means and the gas discharge means based on the measurement result of the pressure measurement means. The control means introduces an inert gas into the process tube after the work is sealed in the process tube by the sealing means and before the heat treatment for the work is started, and the process tube exceeds the pressure resistance of the system. It is determined whether or not the pressure drop rate in a predetermined period after reaching a predetermined pressure in a non-existing range is greater than or equal to a predetermined value. If the pressure drop rate is greater than or equal to a predetermined value, the occurrence of leak is notified without performing heat treatment. Here, as the standard of the pressure resistance of the system, the cracking pressure of the furnace port seal surface in the sealing means and the pressure resistance of the process tube can be mentioned.

  In this configuration, an inert gas is pressurized and sealed in the process tube, and the heat treatment is not performed unless it is confirmed that there is no leakage due to aging deterioration of the seal portion or the like or poor assembly during maintenance. For this reason, it is prevented that dangerous gas leaks from the closed system including the process tube during the heat treatment.

  In addition, since the gas leak inspection is automatically performed in a series of heat treatment flows, it is not necessary to stop the heat treatment apparatus during the gas leak inspection. For this reason, it is not necessary to lower the furnace temperature to room temperature, and the processing efficiency is improved.

  Further, since the process tube is pressurized and sealed with an inert gas to a fine pressure within the pressure resistance, the inside of the process tube is not contaminated by air or particles entering from outside during the gas leak inspection. Further, the time required for the gas leak inspection is shortened as compared with the case where the process tube is evacuated and the gas leak inspection is performed.

  According to the present invention, it is possible to prevent a gas leak caused by aged deterioration of a furnace port seal portion or the like or poor assembly at the time of maintenance with a simple configuration without stopping the heat treatment apparatus.

  An outline of a vertical heat treatment apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. The heat treatment apparatus 100 is configured to perform heat treatment on a semiconductor substrate such as a Si substrate or a workpiece such as a glass substrate. Examples of the heat treatment include an oxide film forming process, a diffusion process, and an annealing process. The heat treatment apparatus 100 includes a furnace body 10, a gas supply unit 50, a gas selection unit 60, a display device 70, and a control unit 20.

  The furnace body 10 includes a quartz process tube 12, a quartz floor plate 22, a heater 14, a stainless steel introduction pipe 40, and a quartz exhaust pipe 42. The process tube 12 has an opening on its bottom surface and defines a processing chamber in which heat treatment is performed. The floor plate 22 is supported by an elevator device (not shown) so as to be movable up and down, and is configured to selectively seal the opening of the process tube 12. A Viton seal member (face seal in this embodiment) is provided between the process tube 12 and the floor plate 22. In addition to viton, silicon or Kalrez (trademark) can be used as a material for the seal member in the heat treatment apparatus 100. The heater 14 is disposed around the process tube 12 and is configured to heat the workpiece in the process tube 12. The introduction pipe 40 communicates the gas selection unit 60 and the process tube 12.

  The exhaust pipe 42 is connected to the process tube 12 via a seal member (O-ring in this embodiment). The exhaust pipe 42 communicates the process tube 12 and the exhaust unit 28. The exhaust pipe 42 is provided with an air valve 34 and a manual valve 32. On the other hand, the connection portion between the process tube 12 and the exhaust pipe 42 is connected to the drain portion 30 via the water trap 36 and the air valve 38.

  The furnace body 10 further includes a first pressure sensor 24 and a second pressure sensor 26. The first pressure sensor 24 detects a negative pressure in the process tube 12 during the heat treatment. On the other hand, the second pressure sensor 26 detects the pressure in the process tube 12 during a fine pressurizing process described later.

The gas supply unit 50 includes a plurality of gas supply units that respectively supply gases to be supplied to the process tube 12. In this embodiment, the gas supply unit 50 includes an HCl supply unit 52, an H ₂ supply unit 54, an O ₂ supply unit 56, and an N ₂ supply unit 58. The configuration of the gas supply unit 50 is not limited to this, but it is preferable that at least one kind of inert gas can be supplied.

The gas selection unit 60 is configured to relay the gas supply unit 50 and the process tube 12. Based on the control signal supplied from the control unit 20, the gas selection unit 60 supplies the gas supplied from each of the HCl supply unit 52, the H ₂ supply unit 54, the O ₂ supply unit 56, and the N ₂ supply unit 58. Optionally, it is introduced into the process tube 12.

  The display device 70 is configured to display information to be notified to the worker based on a control signal from the control unit 20. In this embodiment, the display device 70 is mainly used to notify an operator that a leak has occurred.

  The control unit 20 includes a recording unit 25 in which a plurality of programs are recorded, and comprehensively controls the operation of the heat treatment apparatus 100 based on the program recorded in the recording unit 25.

  The heat treatment apparatus 100 is characterized in that a gas leak inspection of a closed system including the furnace port seal portion of the process tube 12 and the exhaust pipe 42 is easily performed between processes. Hereinafter, the operation procedure of the control unit 20 during the gas leak inspection will be described with reference to the flowchart of FIG.

  First, the control unit 20 introduces a workpiece into the process tube 12 and closes the opening of the process tube 12 by the floor plate 22 (S1).

Subsequently, the control unit 20 proceeds to a fine pressurizing step. Specifically, the process tube 12 is pressurized by introducing N ₂ into the process tube 12 by controlling the gas supply unit 50 and the gas selection unit 60 (S2). At this time, the controller 20 changes the flow rate of the N ₂ gas in consideration of the volume of the process tube 12 and the volume expansion due to the internal temperature so as not to pressurize the system suddenly.

Here, the outline of the connection state between the gas supply unit 50 and the furnace body 10 during the execution of step S2 will be briefly described with reference to FIG. During the execution of step S2, the N ₂ supply unit 58 is connected to the process tube 12, and in the meantime, the manual valve 602, the filter 604, the regulator 620, the air valve 622, the mass flow controller 624, the check valve 626, the filter 628, and the pyrolyzer are connected. A device 630 is interposed. On the other hand, a connection is provided between the filter 604 and the regulator 620. This connecting portion is connected to the process tube 12 via a regulator 606, a mass flow meter 610, a needle valve 612, an air valve 614, and a filter 618. A pressure sensor 610 is provided between the regulator 606 and the mass flow meter 610. In step S2, the control unit 20 opens the air valve 622 and closes the air valve 614, the air valve 34, and the air valve 38.

  Following the fine pressurization step of S2, the control unit 20 waits until the inside of the process tube 12 reaches a predetermined pressure while monitoring the detection value of the second pressure sensor 26 (S3). Here, the predetermined pressure means a fine pressure in a range not exceeding the pressure resistance of the system. In this embodiment, 2 kPa is adopted as a fine pressure within a range not exceeding the withstand voltage of the system. This is because in this embodiment, the cracking pressure of the sealing surface between the process tube 12 and the floor plate 22 is designed to be 2.5 to 3.0 kPa. The pressure value at the time of the slight pressurization step is not limited to 2 kPa, and an arbitrary value can be adopted as long as the pressure resistance of the system is not exceeded.

  In the waiting step of S3, when the inside of the process tube 12 reaches 2 kPa, the control unit 20 starts a timer to measure the pressure drop rate in a predetermined period (S4).

  Subsequently, the control unit 20 waits until a predetermined period elapses (S5). Here, the length of the predetermined period is set to about 5 minutes. The reason is that if the period is too short, the pressure drop cannot be measured appropriately, while if the period is too long, the time required for the heat treatment is extended and the working efficiency is lowered.

When a predetermined period has elapsed in the standby step of S5, the control unit 20 acquires the detection value of the second pressure sensor 26 (S6). Furthermore, the control unit 20 determines whether or not the pressure drop rate is appropriate (S7). In the determination step of S7, the control unit 20 determines that the pressure drop rate is appropriate if the average leak rate in the predetermined period is less than the threshold value, while pressure drop if the average leak rate in the predetermined period is equal to or greater than the threshold value. Judge that the rate is not appropriate. In this embodiment, the leak rate threshold value is set to an average of 1.0 × 10 ⁻² Pa · m ³ / s, but the leak rate threshold value is not limited to this value.

  FIG. 4 is a diagram illustrating an example of a pressure drop in the process tube 12. In the figure, L1 indicates a leak rate threshold. If the pressure drops at a leak rate exceeding the threshold as indicated by L3, there is a high possibility that a gas leak has occurred in the closed system including the process tube 12. On the other hand, as indicated by L2, when the pressure drops at a leak rate less than the threshold value, the possibility that a gas leak has occurred in the closed system including the process tube 12 is low.

  If it is determined in step S7 that the pressure drop rate is appropriate, the process proceeds to heat treatment (S8). At this time, since it has been confirmed that there is no gas leak in the closed system including the process tube 12 in a slightly pressurized state, it is first likely that a gas leak occurs during the heat treatment in which the closed system including the process tube 12 is in a negative pressure state. I can say no.

On the other hand, if it is determined that the pressure drop rate is not appropriate, the process does not proceed to the heat treatment, and the display device 70 is notified of a warning indicating the occurrence of a leak (S9). In this embodiment, since the leak inspection is performed with a safe N ₂ gas, there is no problem in terms of safety even if a closed system gas leak including the process tube 12 occurs. Further, since HCl gas is not supplied if a gas leak in a closed system including the process tube 12 has occurred, there is no inconvenience that the HCl gas leaks while the heat treatment apparatus 100 is in use.

  In the above-described embodiment, only the air valve 34 and the second pressure sensor 26 are provided in the heat treatment apparatus 100 in order to inspect the gas leak exclusively, so that the gas leak inspection can be performed with a simple configuration. Yes. Since the system is pressurized during the gas leak inspection, air, particles, and the like enter from the outside during the gas leak inspection, and the process tube 12 is not contaminated. Furthermore, since it becomes possible to automatically and easily perform a gas leak inspection in a series of heat treatment flows, it is not necessary to periodically stop the heat treatment apparatus 100.

  In the above-described embodiment, the gas leak inspection is always performed before the start of the heat treatment. However, the gas leak inspection may be performed every time the heat treatment is performed several times.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is a figure which shows the outline of a heat processing apparatus. It is a flowchart which shows the operation | movement procedure of the control part at the time of a gas leak test | inspection. It is a figure which shows the outline of the connection state of the gas supply part and furnace body at the time of a micro pressurization process. It is a figure which shows the example of the pressure drop rate in a process tube.

Explanation of symbols

10-furnace body 12-process tube 20-control unit 22-floor plate 34-air valve 40-introduction pipe 42-exhaust pipe

Claims (3)

A heat treatment apparatus comprising: a process tube having an opening at one end; and a sealing means configured to selectively seal the opening, and performing a heat treatment on a workpiece enclosed in the process tube,
Gas supply means configured to supply atmospheric gas into the process tube via a gas introduction path;
A gas discharge means configured to discharge the gas in the process tube via a gas discharge path;
Pressure measuring means capable of measuring the pressure in the process tube;
Control means configured to control operations of the gas supply means and the gas discharge means based on the measurement result of the pressure measurement means;
With
The control means introduces an inert gas into the process tube after the work is sealed in the process tube by the sealing means and before the heat treatment for the work is started. It is determined whether the pressure drop rate in a predetermined period after reaching a predetermined pressure in a range that does not exceed the pressure resistance of the system is greater than or equal to a predetermined value. A heat treatment device that notifies the occurrence. A heat treatment method that is applied to a heat treatment apparatus that includes a process tube having an opening at one end and a sealing means configured to selectively seal the opening, and that performs heat treatment on a workpiece enclosed in the process tube. There,
Enclosing a workpiece in the process tube by the sealing means;
Pressurizing the process tube into a predetermined pressure in a range not exceeding the pressure resistance of the system by introducing an inert gas into the process tube;
Determining whether the pressure drop rate during a predetermined period after the inside of the process tube reaches the predetermined pressure is greater than or equal to a predetermined value;
When the pressure drop rate is less than a predetermined value, the process proceeds to heat treatment, and when the pressure drop rate is equal to or greater than the predetermined value, a step of notifying the occurrence of leakage without performing heat treatment;
A heat treatment method comprising:   A heat treatment apparatus program for causing a heat treatment apparatus to execute the heat treatment method according to claim 2.

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