JP2002208622A - Vertical heat treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide vertical heat treatment equipment, wherein occurrence of accidents can be prevented and maintenance of the equipment can be made safely. SOLUTION: This vertical heat treatment equipment is provided with a carrying mechanism which moves an accommodating vessel in the horizontal direction and the vertical directions, a transfer mechanism which reciprocates a member to be treated between a holding tool for holding a plurality of the members to be treated and the accommodating vessel, and an elevating mechanism which is driven in the vertical directions and carries the holding tool in and from a heat treatment furnace. A lower moving space of at least one elevating body in the carrying mechanism, the transfer mechanism and the elevating mechanism is made a space for working in which maintenance is performed. In the lower part of the elevating body, a safety device is arranged which has a detecting means for detecting an interfering object present in the lower moving space of the elevating body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical heat treatment apparatus used for performing a process such as oxidation, diffusion, annealing or CVD on a semiconductor wafer.

[0002]

2. Description of the Related Art In the manufacture of a semiconductor device, for example, oxidation, diffusion, CV,
Various processes such as D are performed, and as a device for performing such a process, a so-called vertical heat treatment device is widely used. As a vertical heat treatment apparatus, for example, a reaction tube (process tube) is placed in a heat treatment furnace in which a heater is disposed around.
There is known a configuration in which a wafer boat in which semiconductor wafers are horizontally and horizontally held at appropriate intervals is loaded into the reaction tube, and a plurality of semiconductor wafers are simultaneously heat-treated. From the perspective of improving
A configuration in which two wafer boats are used and semiconductor wafer transfer is performed in parallel on one wafer boat while heat treatment is performed on the other wafer boat is used.

[0003] Specifically, a conventional vertical heat treatment apparatus forms, for example, a carrier transfer area divided forward and backward by a partition wall, and a loading area provided with a vertical heat treatment furnace having an opening below. An outer casing is provided, and a carrier transfer mechanism for transferring a carrier containing a semiconductor wafer, which is movable up and down and rotatable in a horizontal plane, is arranged in the carrier transport area, In the loading area, a boat elevator mechanism driven up and down to load and unload a wafer boat into and out of the heat treatment furnace, and two boat mounting sections arranged side by side on one side of the outer casing; A boat transfer mechanism for transferring a wafer boat between the mounting part and the boat elevator mechanism, and a vertically movable and rotatable horizontal plane, A wafer transfer mechanism for transferring the semiconductor wafer is placed on the placed wafer boat over preparative mounting portion.

In such a vertical heat treatment apparatus, a moving space below a lifting / lowering device such as a carrier transfer mechanism, a boat elevator mechanism, and a wafer transfer mechanism is a working space for performing maintenance and the like. It is required that a worker enters the inside of the apparatus periodically or as needed, and performs maintenance such as cleaning and replacement of a reaction tube in a heat treatment furnace or setting for automatic control.

[0005]

However, in the above vertical heat treatment apparatus, the maintenance work is performed, for example, after switching to manual operation, in order to prevent an accident from occurring, a person operating outside the apparatus is required. It is carried out separately from those who work inside the device, but even if extreme care is taken, the carrier transfer mechanism etc. may drop unexpectedly due to some cause such as equipment malfunction or human error. This may cause an accident in which the worker is pinched.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vertical heat treatment apparatus capable of safely performing maintenance of the apparatus without causing an accident. Is to do.

[0007]

According to the vertical heat treatment apparatus of the present invention, a transport area for transporting a storage container storing an object to be processed and a loading area for transferring an object to be processed are partitioned by a partition wall. In the transport area, a transport mechanism for moving the storage container in the horizontal and vertical directions is arranged, and in the loading area, a plurality of workpieces are held between the holding tool for holding the plurality of workpieces and the storage container. A transfer mechanism that performs transfer, and an elevating mechanism that is driven in the vertical direction to carry the holder in and out of the heat treatment furnace are arranged, and at least one of the elevating members in the transport mechanism, the transfer mechanism, and the elevating mechanism is disposed. In a vertical heat treatment apparatus in which a lower moving space is a working space for performing maintenance, a detecting means for detecting an interference object in a lower moving space of the elevating body below the elevating body. Wherein the safety device is provided with.

In the vertical heat treatment apparatus according to the present invention, the detecting means detects the plate-shaped member provided so as to be vertically displaceable while covering the lower surface of the elevating body, and detects that the plate-shaped member is displaced upward. It is preferable that the switch is constituted by a switch that performs the operation.

Further, in the vertical heat treatment apparatus of the present invention, the detecting means includes a plurality of switches, and when any of the positions of the plate member is locally displaced, one of the switches is activated. It is preferable that they are charged.

Further, in the vertical heat treatment apparatus according to the present invention, in addition to the detection means described above, the safety device further includes an optical sensor for detecting an interference object in a moving space below the elevating body by an optical sensor. It is possible to adopt a configuration including means.

[0011]

According to the vertical heat treatment apparatus of the present invention, if there is an obstacle in the moving space below the lifting / lowering body, this is detected by the detecting means and the safety device is activated, so that the lifting / lowering body is immediately stopped. Therefore, occurrence of an accident can be reliably prevented beforehand, and maintenance of the device can be performed safely. Here, the term "interfering object" means something other than constituting the lifting / lowering device, and also includes a worker who performs maintenance work on the device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an example of a schematic configuration of a vertical heat treatment apparatus of the present invention, FIG. 2 is a plan view of the vertical heat treatment apparatus shown in FIG. 1, and FIG. 3 is a vertical heat treatment apparatus shown in FIG. It is a longitudinal section of a device. This heat treatment apparatus 10
A carrier transport area Sa, which is divided into front and rear by a partition wall 12 and in which a carrier (cassette), which is a storage container for accommodating a semiconductor wafer as an object to be processed, is loaded, unloaded, and stored, etc .; And a loading area Sb in which a carrier 20 is loaded and unloaded at the front portion of the outer casing 11. A loading / unloading stage 14 serving as an entry / exit port is provided. The carrier transport area Sa is maintained in an air atmosphere, and the loading area Sb is maintained in an air atmosphere or an inert gas atmosphere such as a nitrogen gas. 1 and 3, reference numeral 15 denotes a sensor mechanism for opening the cover 20A of the carrier 20 and detecting the position and the number of semiconductor wafers;
Is a shelf-shaped carrier storage unit for storing a plurality of carriers 20, and 17 aligns notches (notches) provided in a peripheral portion of a semiconductor wafer in one direction to align crystal directions. Notch alignment mechanism for

The carrier 20 has a predetermined diameter, for example, a diameter 3
A plastic container capable of accommodating a plurality of, for example, about 13 to 25, semiconductor wafers of 00 mm in a horizontal direction at predetermined intervals in a vertical direction, is formed of a plastic container, and has a wafer outlet (not shown) opened at the rear surface thereof. ) Is removably provided with a lid 20A for hermetically closing the cover.

In the carrier transport area Sa, a carrier mounting portion 21 for mounting the carrier 20 is provided close to the partition wall 12, and as shown in FIG. In order to improve the processing capacity (throughput), a plurality of, for example, two, are provided in the vertical direction. The carrier 20 can be exchanged at the carrier mounting portion 21B.

A carrier 2 is provided in the carrier transport area Sa.
0 is moved in the horizontal plane and in the vertical direction, and the carrier transport is a transport mechanism for transferring the carrier 20 among the three members of the loading / unloading stage 14, the carrier storage sections 16, 16 and the carrier mounting section 21. A mechanism 25 is provided, and a moving space below the carrier transport mechanism 25 is a working space for performing maintenance.

The carrier transport mechanism 25 includes an elevating guide 25A provided on one side surface of the outer casing 11, an elongated rectangular elevating arm 25B as an elevating body which is vertically moved by the elevating guide 25A, and an elevating arm 25B. A transfer arm 25 rotatably provided in the horizontal plane on the arm 25B
C, the transfer arm 25C includes a first arm 251 and the first arm 25, as shown in FIG.
And a second arm 252 provided at the front end of the first arm 252 so as to be rotatable in a horizontal plane.

Each carrier mounting portion 21 is provided on the partition 12.
Corresponding to the height position, an opening 22 for communicating the carrier transport area Sa with the loading area Sb is formed. The opening 22 has substantially the same diameter as the wafer outlet of the carrier 20. In addition, the partition 12 has:
A door (23 in FIG. 2) for closing the opening 22 from the loading area Sb side is provided.
Is opened and closed by a door opening and closing mechanism (not shown) provided in the loading area Sb. Further, a lid opening / closing mechanism (not shown) for opening / closing the lid 20A of the carrier 20 is provided, whereby the door 23 and the lid 2 of the carrier 20 are provided.
After 0A is moved to the loading area Sb side, it is retracted upward or downward so as not to hinder transfer of the semiconductor wafer.

At the rear of the loading area Sb (the lower part in FIG. 2), a heat treatment furnace 28 is provided above and is driven up and down to provide a large number of sheets, for example, 100 pieces.
A wafer boat 3 made of, for example, quartz, which is a holder for holding up to about 150 semiconductor wafers in predetermined stages at predetermined intervals.
A boat elevator mechanism 30, which is an elevating mechanism for loading and unloading 1 </ b> A and 31 </ b> B into and out of the heat treatment furnace 28, is provided to face the carrier mounting portion 21. The boat elevator mechanism 30 includes a lifting guide 32A, a wafer boat 31A,
1B is mounted on the mounting table 32B, which is an elevating body that is vertically moved by an elevating guide 32A. It functions as a lid closing the lower end opening 28A of the furnace 28. Also,
It is also used for exchanging a reaction tube (not shown) provided in the heat treatment furnace 28.

In the vicinity of the lower end opening 28A of the heat treatment furnace 28, a shutter 33 for shielding the lower end opening 28A when the wafer boat after the heat treatment is carried out of the heat treatment furnace 28 is provided. The drive mechanism 34 is configured to open and close by being rotated around an axis extending vertically.

Outer casing 11 in loading area Sb
On one side surface portion, a boat mounting portion 3 on which wafer boats 31A and 31B are mounted for transferring a semiconductor wafer or the like.
5 is provided, and the boat mounting portion 35 has a first mounting portion 35A and a second mounting portion 35B arranged in front and rear.

The loading area Sb is provided between the first mounting portion 35A or the second mounting portion 35B of the boat mounting portion 35 and the mounting table 32B of the boat elevator mechanism 30, and between the first mounting portion 35A and the first mounting portion 35A. A boat transfer mechanism 36 for transferring the wafer boats 31A and 31B to and from the two mounting portions 35B is provided.

The boat transfer mechanism 36 has a first arm 36 rotatable in a horizontal plane and vertically movable up and down.
A and a support arm 36B provided at the distal end of the first arm 36A so as to be rotatable in a horizontal plane and having a substantially C-shaped opening 36C capable of vertically supporting the wafer boats 31A and 31B. ing. Support arm 36B
Is the locus drawn by the center of the opening 36C when driven,
The first arm 36A and the support arm 36B are arranged in a state including the center of rotation of the first arm 36A.
A and 31B are transferred.

The boat transfer mechanism 36 at the lowest position
At an upper level, an operation space area overlapping with the operation space area of the boat transfer mechanism 36 is provided.
The wafer transfer mechanism 40 is a transfer mechanism for transferring semiconductor wafers between the carrier 20 on the carrier 1 and the wafer boat 31B on the boat mounting portion 35. The moving space below is a working space.

As shown in FIG. 2, the wafer transfer mechanism 40 is provided with a lift guide 41 provided on a side surface of the boat transfer mechanism 36 opposite to the boat mounting portion 35 through a part of the operation space area of the boat transfer mechanism 36. And a pivoting arm 42 which is a lifting and lowering body which is vertically movable by the lifting and lowering guide 41 and is rotatable around a pivoting center axis 421 extending vertically, and pivots at the tip of the pivoting arm 42. An elongated rectangular transfer head 43 provided rotatably in a horizontal plane in synchronization with the rotational movement of the arm 42, and a transfer head 43 provided on the transfer head 43 so as to be able to advance and retreat in its length direction. When the transfer of the wafer boat is performed by the wafer boat transfer mechanism 36, the other side surface of the outer casing 11 is used to prevent the wafer boat from being interfered with each other. And it is retractable to the retracted position in the.

An extension mechanism 45, for example, an air cylinder, is connected to the pivot arm 42 at one end to a rotation center axis 451 different from the rotation center axis 421 of the pivot arm 42.
The other end is the connecting portion 46 at the tip side portion of the swing arm 42.
And the extending / contracting direction is obliquely intersected with the length direction of the turning arm 42, and the turning arm 42 is rotated by the expansion / contraction of the extending / contracting mechanism 45. The extension mechanism 45 is adjusted to extend and contract, for example, in the range of 195 to 250 mm, thereby setting the operation space area of the wafer transfer mechanism 40 to a predetermined range, and controlling the direction or the angle of the rotation arm 42. State control can be performed reliably.

The operation of the above vertical heat treatment apparatus 10 is as follows. First, when the carrier 20 is placed on the loading / unloading stage 14 from outside by an automatic transfer robot or an operator (not shown), the carrier 20 is moved into and out of the loading / unloading port 1.
3, the carrier 20 is opened by the sensor mechanism 15, and the position and the number of semiconductor wafers in the carrier 20 are detected. After that, the carrier 20 is moved by the carrier transport mechanism 25 with the lid 20A closed. The semiconductor wafer is transferred to the notch alignment mechanism, and the notch (notch) provided on the peripheral edge of the semiconductor wafer is aligned in one direction and transferred to the carrier mounting unit 21. Also, depending on the progress of the heat treatment,
After the carrier 20 is once stored in the carrier storage unit 16, it is transported to the carrier mounting unit 21.

When the lid 20A of the carrier 20 on the carrier mounting part 21 and the door 23 of the opening 22 of the partition 12 are opened, the wafer transfer mechanism 40, specifically, the turning operation of the turning arm 42 The semiconductor wafer is taken out of the carrier 20 by performing the rotation operation of the transfer head 43 and the advance / retreat operation of the support arm 44 in a controlled manner, and the semiconductor wafer is taken out on the first mounting portion 35A of the boat mounting portion 35. The wafers are sequentially transferred to the waiting wafer boat 31B. During this time, since the boat transfer mechanism 36 is lowered to the position below the operation space area and retracted, the wafer transfer mechanism 40 does not interfere with the boat transfer mechanism 36.

When the transfer of the semiconductor wafer from the carrier 20 on the carrier receiver 21 to the wafer boat 31B on the first receiver 35A is completed, the wafer transfer mechanism 40 moves the outer casing 11 from its operation space area. To the retreat position on the other side.

In this state, the wafer boat holding the semiconductor wafer on the first mounting portion 35A of the boat mounting portion 35 is
The boat is transferred onto the mounting table 32B of the boat elevator mechanism 30 by the boat transfer mechanism 36, and is introduced into the heat treatment furnace 28 together with the mounting table 32B by the boat elevator mechanism 30. Then, the boat transfer mechanism 36 is moved to the retreat position below the operation space area, and at the same time when one of the wafer boats is subjected to the heat treatment, the semiconductor wafer is transferred to the wafer boat on the first mounting portion 35A. Are performed in parallel. After the heat treatment, the wafer boat after the heat treatment is carried out from the inside of the heat treatment furnace 28 to the loading area Sb by lowering the mounting table 32B, and the lower end opening 28A of the heat treatment furnace 28 is
It is immediately shielded by the shutter 33.

When the wafer boat after the heat treatment is carried out,
First, the wafer boat 31B before the heat treatment waiting on the first mounting portion 35A is transferred to the second mounting portion 35B by the boat transfer mechanism 36, and then the wafer boat 31A after the heat treatment.
Is transferred from the mounting table 32B to the first mounting section 35A, and finally, the wafer boat 31B on the second mounting section 35B is transferred to the mounting table 32B. Then, the semiconductor wafer is taken out from the wafer boat 31A after the heat treatment by the wafer transfer mechanism 40, is loaded on the carrier 20 on the carrier mounting portion 21, is carried by the carrier carrying mechanism 25, and is carried out from the carry-in / out port 13.

In the vertical heat treatment apparatus 10 of the present invention, at least one elevating member in the carrier transport mechanism 25, the elevator mechanism 30, and the wafer transfer mechanism 40 is provided with a safety device. Transport mechanism 25, elevator mechanism 30, and wafer transfer mechanism 4
Preferably, a safety device is provided for each of the zeros.
In the carrier transport mechanism 25, as shown in FIG.
A plate-like member (safety arm) 51 provided below the lifting arm 25B so as to be vertically displaceable so as to cover the entire lower surface thereof, and a switch 52 which is turned on when the plate-like member 51 is displaced upward. And a safety device 50 having detection means constituted by the following.

More specifically, in the plate member 51 of the safety device, the elongated holes 53 formed at both ends of the rising portions 51A on both side edges thereof are formed in the width direction of the lifting arm 25B (perpendicular to the paper surface). The pin 54 has a diameter slightly smaller than the elongated hole 53 and extends in the vertical direction in a loose state in which the displacement is not restricted in directions other than the vertical direction. The plate member 51 is provided with a pressing means 55 extending upward toward the switch 52, whereby the switch 52 is turned on when the plate member 51 is displaced upward.

A plurality of switches 52 in the detecting means are provided, and when any position of the plate member 51 is locally displaced, one of the switches 52 is turned on. Specifically, the lifting arm 25
A total of two switches 52 are provided, one at the base end and one at the tip in the length direction of B. The switch 52 is turned on when the plate member 51 is displaced by, for example, about 2 mm.

The safety device 50 has a light irradiating section 57 and a light receiving section 58 on the lower surface of the plate member 51, in addition to detecting means for detecting the displacement of the plate member 51 and operating the safety device 50. And an optical detecting means including an optical sensor configured to be opposed to each other.
An interference object in the moving space below 5B is detected, and the safety device 50 is thereby operated.

As shown in FIG. 5, the boat elevator mechanism 30 is preferably provided with a safety device 50 below the mounting table 32B. The basic configuration of the safety device 50 is the same as that provided under the lifting arm 25B of the carrier transport mechanism 25. For example, one at the base end and one at the tip end of the lifting guide 32A. A total of two switches 52 are provided. In the drawing, reference numeral 51B denotes a support portion supported by the pin 54. Also in the wafer transfer mechanism 40, as shown in FIG. 6, it is preferable that a safety device 50 is provided below the turning arm 42, for example, a base end on one side and a tip on the other side. And a total of two switches 52 are provided, one for each.

According to the vertical heat treatment apparatus 10 as described above, during maintenance of the apparatus, the worker may not be able to enter the working space due to some cause such as malfunction of the apparatus or occurrence of human error. Despite this, the vertically movable body such as the lifting arm 25B in the carrier transport mechanism 25, the mounting table 32B in the boat elevator mechanism 30, or the turning arm 42 in the wafer transfer mechanism 40 is lowered. Even in the case of a failure, a part of the body of the worker comes in contact from below and the plate-shaped member 51 is displaced upward, whereby the safety device 50 is operated and the elevating body is immediately stopped. Specifically, the switch 52 is turned on when the plate member 51 is displaced upward, and the power of the apparatus is cut off by an appropriate cutoff switch, or the switch of the lift motor is turned off, so that The body is stopped. as a result,
It is possible to reliably prevent the occurrence of an accident such as a worker being pinched by these elevating bodies, and to perform maintenance of the apparatus safely.

The detecting means in the safety device 50 is as follows:
Since the plate-shaped member 51 is constituted by the switch 52 and the whole of the plate-shaped member 51 becomes an area that can be detected by the switch 52, the lower surface area of the elevating body that can come into contact with the worker is detected over a wide range. It is possible to reliably prevent the occurrence of an accident. Plate member 51
Is supported by a pin having a diameter slightly smaller than the elongated hole 53 in the plate-shaped member 51, so that even when the interfering object is not in contact with the entire surface of the plate-shaped member 51 but is locally contacted, the plate-shaped member 51 It can be displaced upward in a tilted state,
The safety device 50 can be operated reliably.

When any position of the plate member 51 is locally displaced, the switch 52
By providing a plurality in parallel in a state where any one of them operates, it is possible to more reliably prevent the occurrence of an accident.

Further, the detecting means for detecting the displacement of the plate-like member 51 and the optical detecting means can perform double detection of the interference in the moving space below the elevating body, so that the detection can be performed more reliably. Accidents can be prevented.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
For example, various changes as described below can be made. (1) The number and arrangement positions of the start switches in the safety device are particularly limited as long as any one of the start switches is configured to be operated regardless of which position of the plate-shaped member is pressed. Not something. (2) The mounting method (supporting method) of the plate-shaped member in the safety device is not particularly limited as long as the plate-shaped member is provided so as to be vertically displaceable. For example, in a state where the plate-shaped member is suspended. It may be provided. (3) The plate-shaped member may be provided in a state of being divided (for example, a sea-island structure) below the elevating body, or may be provided in a part thereof. It is preferably provided so as to cover the entire lower surface of the body. (4) The safety devices provided in the boat elevator mechanism and the wafer transfer mechanism can also be provided with optical detection means.

[0041]

According to the vertical heat treatment apparatus of the present invention, the safety device is actuated and stopped immediately because the elevating body comes into contact with the obstacle in the lower space and is pressed from below. An accident can be reliably prevented, and the maintenance of the device can be performed safely.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a schematic configuration of a vertical heat treatment apparatus of the present invention.

FIG. 2 is a plan view of the vertical heat treatment apparatus shown in FIG.

FIG. 3 is a vertical sectional view of the vertical heat treatment apparatus shown in FIG.

FIG. 4 is a longitudinal sectional view illustrating an example of a schematic configuration of a lifting arm in the carrier transport mechanism.

FIG. 5 is a longitudinal sectional view showing an example of a schematic configuration of a mounting table in the boat elevator mechanism.

FIG. 6 is a longitudinal sectional view showing an example of a schematic configuration of a turning arm in the wafer transfer mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat treatment apparatus 11 Outer casing 12 Partition wall 13 Loading / unloading 14 Loading / unloading stage 15 Sensor mechanism 16 Carrier storage part 17 Notch alignment mechanism Sa Carrier transport area Sb Loading area 20 Carrier 20A Cover 21 Carrier mounting part 22 Opening 23 Door 25 Carrier transport Mechanism 25A Lifting guide 25B Lifting arm 25C Transfer arm 251 First arm 252 Second arm 28 Heat treatment furnace 28A Lower end opening 30 Boat elevator mechanism 31A, 31B Wafer boat 32A Lifting guide 32B Mounting table 33 Shutter 34 Shutter drive mechanism 35 Boat mounting section 35A first mounting portion 35B second mounting portion 36 boat transfer mechanism 36A first arm 36C opening 36B support arm 40 wafer transfer mechanism 41 elevating guide 42 swivel arm 421 swivel arm Rotation axis of the arm 43 transfer head 431 rotation axis of the transfer head 44 support arm 45 extension mechanism 46 connecting part 50 safety device 51 plate member (safety arm) 51A folded part 51B support part 52 switch 53 length Hole 54 Pin 55 Pressing means 57 Light irradiation part 58 Light receiving part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F031 CA02 DA17 FA01 FA03 FA11 FA15 GA36 GA43 GA48 HA67 JA05 JA08 JA17 JA22 KA14 MA02 MA28 MA30 NA04 NA10 PA06 PA30 5F045 AA20 AB32 BB20 DP19 EB09 EM10 EN04 EN05 GB15

Claims (4)

[Claims] 1. A transport area for transporting a storage container storing an object to be processed and a loading area for transferring the object to be processed are partitioned by a partition wall. A transfer mechanism for moving the workpieces between a holder for holding a plurality of workpieces and a storage container is provided in the loading area. A lifting / lowering mechanism for loading / unloading the holding tool into / from the heat treatment furnace, and a moving space below at least one lifting / lowering body in the transfer mechanism, the transfer mechanism, and the lifting / lowering mechanism is a working space for performing maintenance. In the vertical heat treatment apparatus, a safety device having detection means for detecting an interfering object in a moving space below the elevating body is provided below the elevating body. Vertical heat treatment apparatus to be. 2. The detecting means includes a plate-shaped member provided to be vertically displaceable while covering the lower surface of the elevating body, and a switch for detecting that the plate-shaped member has been displaced upward. The vertical heat treatment apparatus according to claim 1, wherein: 3. The detecting means includes a plurality of switches, and when any one of the plate members is locally displaced, any one of the switches is turned on. The vertical heat treatment apparatus according to claim 1 or 2, wherein 4. The safety device further comprises, in addition to the detecting means according to claim 2 or 3, an optical detecting means for detecting an obstacle in a moving space below the elevating body by an optical sensor. The vertical heat treatment apparatus according to any one of claims 1 to 3, wherein the apparatus is a vertical heat treatment apparatus.