JP2555380B2 - Heat treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a heat treatment method for heat treating an object to be processed in a gas atmosphere.

(Prior Art) As an example of this type of heat treatment furnace, for example, a diffusion furnace that heat-treats a semiconductor wafer in a nitrogen gas atmosphere can be mentioned.

In this type of heat treatment furnace, a plurality of semiconductor wafers are arranged and supported on a quartz boat, the quartz boat is placed on a transfer fork, and the transfer fork is moved into the heat treatment furnace to heat treat the semiconductor wafer. It is supposed to do.

Here, the inside of the heat treatment furnace is kept in a nitrogen gas atmosphere, and if air or the like is brought into the furnace when the transfer fork is carried in, an undesired oxide film or the like is formed on the semiconductor wafer. It will be.

By the way, as a drive of the transfer fork, a cantilever system that supports and stops the quartz boat during the heat treatment while keeping the quartz boat mounted on the fork in a non-contact state in the heat treatment furnace without contact, and in the heat treatment furnace For example, a soft landing method is adopted in which after the quartz boat is loaded, the quartz boat is placed in the furnace and the transfer fork is carried out of the furnace.

In either method, there is no change in carrying the quartz boat into the heat treatment furnace by using the transfer fork, and there is a risk that air will be brought into the heat treatment furnace at this time.

Here, a conventional heat treatment apparatus will be described with reference to FIG.

This heat treatment device is roughly classified into a carry-in / out device 50, a heat treatment furnace 6
0 and a heat exhaust chamber 70.

The loading / unloading device 50 includes a soft landing mechanism section 51.
And a transfer fork 52 driven by the soft landing mechanism section 51, and a quartz boat 53 on which a semiconductor wafer 54 is mounted is placed on the transfer fork 52 and placed in the heat treatment furnace 60. It is possible to carry in and out.

The heat treatment furnace 60 is configured by providing a heater 62 around the process tube 61, and is configured such that nitrogen gas can be introduced from the end of the process tube 61.

The heat exhaust chamber 70 has an elephant tube 71 fixedly connected to the process tube 61, a shutter 72 that can open and close an opening of the elephant tube 71, and an opening on the upper surface of the elephant tube 71 near the shutter 72. And a nitrogen gas supply port 73 formed as described above.

Then, before the quartz boat 53 and the semiconductor wafer 54 are loaded into the process tube 61 by the transporting fork 52, the quartz boat 53 and the semiconductor wafer 54 are placed in or passed through the elephant tube 71, and nitrogen gas is supplied. It was supplied and was replaced with nitrogen in a nitrogen atmosphere before being carried into the heat treatment furnace 60, and then was carried into the heat treatment furnace 60.

(Problems to be Solved by the Invention) In the conventional configuration described above, the elephant tube is used.
The air could not be reliably removed within 71. That is, the thermal exhaust chamber 70 is originally for exhausting hot gas and the like in the process tube 61 (an exhaust tube (not shown) is connected), and has a function of creating a nitrogen atmosphere in the elephant tube 71. Even if there was, it was not used with the intention of actively removing air.

Such a problem also occurs when the boat 53 is discharged from the heat treatment furnace 60, and if the boat carried out from the process tube 61 is placed in an area where air exists, an oxide film may be formed by residual heat. was there. There is a fixed type outside air entrapment prevention device disclosed in Japanese Patent Laid-Open No. 61-190929, but this is not sufficient.

Therefore, the object of the present invention is to solve the above-mentioned conventional problems, and while utilizing the characteristics of the cantilever method, positively move the object to be processed before carrying the transfer fork into the heat treatment furnace. To provide a space-saving heat treatment method by purging to remove air originally attached to the surface of the object to be treated and the like, thereby reliably preventing formation of an undesired oxide film and the like. is there.

[Structure of the Invention] (Means for Solving the Problems) In the heat treatment method according to the invention described in claim 1, a boat in which a plurality of objects to be processed are arranged is placed on a carrying fork. A heat treatment method in which the transfer fork is transferred into a heat treatment furnace for heat-treating the object, and the object is heat-treated while the transfer fork is kept in non-contact with the inner wall of the heat treatment furnace. And independently moving the purge tube in one direction with respect to the transport fork to surround the boat mounted on the transport fork with the purge tube, and the purge tube surrounding the boat. A step of supplying the same atmospheric gas as that used in the heat treatment furnace, and the transfer fork and the purge tube are simultaneously moved in the one direction, so that the opening end of the purge tube and the front end A step of installing in a communication state in which the open end of the heat treatment furnace is opposed, a step of supplying the same atmosphere gas into the purge tube and the heat treatment furnace in the communication state, and thereafter, the transfer fork Independently moving in the one direction with respect to the purge tube,
A step of setting the object to be processed at a processing position in the heat treatment furnace.

The heat treatment method according to the invention as set forth in claim 2 is such that at least the open end of the heat treatment furnace is set until the open end of the purge tube and the open end of the heat treatment furnace are set facing each other. A step of closing the shutter with a shutter, and a step of opening the shutter at least before the transfer fork is carried into the heat treatment furnace,
The heat treatment method according to claim 1, further comprising:

The heat treatment method according to the invention described in claim 3 includes a step of supplying the atmospheric gas to a region where the shutter is opened and closed.
The heat treatment method according to the item.

The heat treatment method according to the invention as set forth in claim 4 is a heat treatment in which a boat in which a plurality of objects to be processed are arranged is placed on a transfer fork, and the transfer fork heat-treats the object to be processed. A heat treatment method of heat-treating an object to be processed in a state where the transfer fork is maintained in non-contact with the inner wall of the heat treatment furnace, wherein a notch portion in which the transfer fork is inserted into a purge tube. Is formed and has the heat treatment method according to claim 1,
When the object to be processed is set to the processing position, the notch of the purge tube is closed by a shutter formed on the transfer fork.

(Operation) According to each of the inventions described in claims 1 to 4, the following operations and effects are provided.

(A) By allowing the purge tube and the transfer fork to move independently and simultaneously, the transfer fork maintains a configuration equivalent to that of a conventional cantilever while adding a purge tube. Before carrying into the heat treatment furnace, the ambient atmosphere of the object to be processed can be purged independently of the heat treatment furnace.

For example, in order to transfer the boat to the transfer fork, the purge tube can be retracted from the boat mounting position of the transfer fork as in step 1 of FIG. Boats can be transferred.

There is no change in the moving stroke of the transfer fork, and it is sufficient that the transfer fork can reciprocate between the boat transfer position in step 1 of FIG. 3A and the processing position of steps 5 and 6 in FIG.

Even though the purging function is added in this way, the length and weight of the transfer fork can be maintained in a non-contact state with the inner wall of the heat treatment furnace during the heat treatment, without increasing the length and weight.

(B) The purge tube makes it possible to purge the atmosphere around the object to be processed before the opening end communicates with the opening end of the heat treatment furnace, and cleans the atmosphere around the object to be processed before setting the communication state. it can. Thereby, entrapment of air or the like in the heat treatment furnace can be reduced.

(C) By making the direction of movement for achieving each step the same uniaxial direction, the drive mechanism required for each movement can be made compact, and therefore, the space saving of the heat treatment apparatus can also be achieved.

(Example) Hereinafter, one example in which the present invention is applied to a heat treatment of a semiconductor wafer will be specifically described with reference to the drawings.

First, the heat treatment apparatus will be described with reference to FIGS. 1 and 2.

This heat treatment apparatus includes a boat loading / unloading apparatus 10, a heat treatment furnace 30, and a heat exhaust chamber 40.

The loading / unloading device 10 supports a carrying fork 11 made of quartz on one end of which is mounted a quartz boat 2 having a plurality of semiconductor wafers 1 mounted thereon, and supports the other end of the carrying fork 11. The quartz fork 2 can be carried in and out of the heat treatment furnace 30 by having the cantilever portion 13 that moves the carrying fork 11 along the longitudinal direction thereof.

The cantilever portion 13 is, as shown in detail in FIG.
Placed and fixed on the movable base 14, this movable base 14
It is movable along the two guide rails 15, 15. The movable base 14 is configured to move along the guide rails 15 and 15 by driving the motor 16.

Further, as a characteristic configuration of the apparatus of the present embodiment, it is formed in a cylindrical shape capable of enclosing the boat 2 and the semiconductor wafer 1 on the transfer fork 11, and is independent of the transfer fork 11 and the transfer fork 11. It can move in the same direction,
In addition, a purge tube 20 capable of supplying the same atmospheric gas as the heat treatment furnace is provided inside.

The purge tube 20 has an open end 21 at one end facing the heat treatment furnace 30, and has a notch 22 into and out of the transfer fork 11 on the opposite end face. Further, the end face having the cutout portion 22 is provided with a nitrogen supply port 23 capable of supplying the same gas as the atmospheric gas in the heat treatment 30, for example, nitrogen (N2).

The purge tube 20 is mounted and fixed on a movable base 25, and the movable base 25 is configured to be movable along the guide rails 15, 15. In addition, the movable base 25
Are driven by a motor 26, for example, by a rack and pinion.

A shutter 27 that closes the notch 22 of the purge tube 20 is fixed on the transfer fork 11.

As shown in FIG. 2, the heat treatment furnace 30 includes a process tube 31, a nitrogen supply port 32 for supplying nitrogen gas into the process tube 31, and a process tube 31 wound around the process tube 31. And a coiled heater 33.

 Next, the heat exhaust chamber 40 will be described.

In this embodiment, the heat exhaust chamber 40 is composed of a shutter 41 that can open and close the open end of the process tube 31, a guide member 42 of the shutter 41, and a drive mechanism 43 of the shutter 41.

The guide member 42 is a passage hole of the transfer fork 11 that communicates with the guide hole 42a of the shutter 41 and the heat treatment furnace 30.
Gas supply ports 44, 4 which are provided with 42b and communicate with the guide hole 42a and the passage hole 42b to supply the N2 gas from the upper end.
Have four.

The drive mechanism 43 includes four rollers 45 that movably support the driven plate 41a of the shutter 41 and the driven plate 41.
The rack 46 formed in a, a pinion 47 that meshes with the rack 46, and a motor 48 that drives the pinion 47.

The operation of the heat treatment apparatus configured as described above and the heat treatment method using this heat treatment apparatus will be described with reference to FIG.
The description will be made with reference to FIG.

First, in step 1, with the purge tube 20 removed from the mounting position of the quartz boat 2 of the transfer fork 1,
The quartz boat 2 is mounted on the mounting surface described above. At this time, the shutter 41 is closed. The flow rate of N2 gas from the gas supply port 22 of the purge tube 20 is "small".

Next, in step 2, a motor for driving the purge tube 20
Drive the 26 and move the movable base 25 to move the purge tube.
20 is moved to a position surrounding the quartz boat 2 and the wafer 1 on the transfer fork 11. At this time, by switching the N2 supply flow rate from the supply port 22 of the purge tube 20 to “large” and discharging the N2 gas supplied from one end of the purge tube 20 from the opening end 21 at the other end,
Gases such as air other than N2 gas in the purge tube 20 are discharged.

Next, in step 3, the transfer fork 11 and the purge tube 20 are moved together to open the purge tube 20 at the open end.
21 is brought into contact with the wall surface of the guide member 42 of the shutter 41.
Also here, as described above, by setting the flow rate of the N2 gas from the supply port 23 to "large", the N2 gas supplied from the supply port 23 is increased.
The gas carries air etc. in the purge tube 20 and the shutter
It is transported to the wall surface of 41, and is discharged from the guide hole 42b of the shutter 41 or the gap between the contact portion between the purge tube 20 and the guide member 42.

As described above, by performing N2 purging in the purge tube 20 with the shutter 41 closed, the inflow of air from the opening end 21 and the inflow of air into the process tube 31 are prevented. While purging with N2 in the purge tube 20
Purging can be performed.

Next, in step 4, the shutter 41 is driven to open by the action of the pinion 47 and the rack 46 based on the drive of the motor 47, and the purge tube 20 and the process tube are driven.
Communication with the inside of 31.

At this time, the supply of the N2 gas from the supply port 23 of the purge tube 20 is continued, and the N2 gas is also supplied into the process tube 31 from the supply port 32 at one end thereof at a high flow rate.

In this way, by supplying the N2 gas at a large flow rate from both ends of the purge tube 20 and the process tube 31 which are in communication with each other by opening the shutter 41, the N2 gas transferred from both ends and other gases such as air are removed. , Collected in the heat exhaust chamber 40, from the gap of this portion, that is, the guide hole of the guide member 42 or the gap of the contact surface between the opening end 21 of the purge tube 20 and the guide member 42, N2 gas and other The air and other gases will be exhausted.

Here, by supplying the N2 gas from the supply port 44 provided at the upper end of the guide member 42 as well, the N2 gas or the like can be surely discharged from the gap without staying in the thermal exhaust chamber 40.

In this way, the purge tube 20 and process tube 31
By carrying out N2 purge with and in communication with each other, the inside of both tubes 20, 31 can be set to the same gas atmosphere. As a result, the wafer 1 on the quartz boat 2 is removed from the heat treatment furnace.
Before being loaded into 30, it is possible to set an N2 gas atmosphere in which air and the like are not mixed.

Then, in step 5, the transfer fork 11 is moved further forward to transfer the wafer 1 on the boat 2 to the core of the process tube 31. At this time, the flow rate of N2 gas from the N2 supply port 23 of the purge tube 20 is set to "small".
Switch to.

At this time, the purge tube 20 is kept in contact with the wall surface of the guide member 42.

As described above, by disposing the purge tube 20 at the furnace opening of the heat treatment furnace 30, it is possible to prevent the entrainment of air into the heat treatment furnace 30 and the release of heat.

Further, in this embodiment, since the cantilever system is adopted, the heat treatment of the wafer 1 is executed while the transfer fork 11 is held in the process tube 31 (step 6).

At this time, since the wafer 1 is set in advance in an N2 gas atmosphere and is set in an environment in which other gas such as air is sufficiently discharged, an undesired oxide film or the like is not formed.

When this reaction process is completed, the carrying fork 11 is driven in step 7, and the boat 2 is returned and carried into the purge tube 20.

After this, in step, the supply port of the purge tube 20
The flow rate of N2 gas from 23 is switched to "high", and N2 purge is executed as in the case of loading into the heat treatment 30.

The reason why the N2 purge is carried out after being carried out from the heat treatment furnace 30 is that the residual heat is high enough to form a film on the wafer 1 even if the N2 purge is removed from the process tube 31. This is because an undesired oxide film or the like will be formed if the wafer 1 contacts the air or the like in this state.

Next, in step 9, the shutter 41 is closed and driven,
At this time, the flow rate of N2 from the supply port 23 of the purge tube 20 is set to "small". Then, the N 2 purge is executed with the shutter 41 closed in this way.

Then, in step 10, the transfer fork 11 and the purge tube 20 are retracted so as to move away from the heat treatment furnace 30, and are moved to the home position of the transfer fork 11.

Then, after setting the home position,
At 11 the purge tube 20 is driven to a position where it does not surround the quartz boat 2 and the wafer 1 to complete the one cycle heat treatment process.

After that, the boat on the carrying fork 11 may be moved and the above-described processing may be repeated.

As described above, according to this embodiment, N 2 purge is performed with the wafer 1 placed in the process tube 20 to remove air and the like, and the open end 21 of the purge tube 20 is closed with the shutter 41. Since N2 purging is performed and finally N2 purging is performed with the purge tube 20 and the process tube 31 communicating with each other, other gases such as air are surely passed through both tubes 20, 31, especially the wafer 1. It can be removed from the region, and the insides of both tubes 20 and 31 can be set to the same atmosphere. Therefore, it is possible to reliably prevent formation of an undesired oxide film or the like on the wafer 1.

Further, since the open end of the heat treatment furnace 30 is always closed by the shutter 41 or the purge tube 20, there is an effect of suppressing the entrainment of air or the like into the furnace and the release of heat from the furnace.

The present invention is not limited to the above embodiment,
Various modifications can be made within the scope of the present invention.

For example, in the first invention, before or after the heat treatment,
With the purge tube 20 and process tube 31 in communication with each other, supply N2 gas from both tubes, and
It suffices to include the step of making the inside of the atmosphere the same, and the N 2 purge with the shutter 41 closed as in the above embodiment is not always necessary. By performing the N2 step in step 3 as in the above embodiment, it is possible to more reliably discharge air and the like, and it is possible to prevent air and the like from flowing into the heat treatment furnace 30.

Further, the above steps do not necessarily have to be performed before and after the heat treatment of the object to be processed, and even if either of them is effective, it is preferable to carry out the steps before carrying them into the heat treatment furnace. The effect of preventing the formation of an oxide film or the like is increased.

In addition, although an example in which the boat 2 is carried into the heat treatment furnace 30 by the cantilever system has been described, the boat 2 is not necessarily limited to this system and can be applied to a heat treatment apparatus employing a soft landing system, for example.

In this case, the transfer fork 11 not only moves in the front-rear direction but also moves up and down to softly land the boat 2 in the heat treatment 30, so that the clearance hole of the transfer fork 11 formed in the purge tube 20 is formed. It is necessary to increase the size of the notch 22 as described above. Except for this point, the driving can be performed in the same manner as in the above-described embodiment except for driving the transport fork 11. Further, in this case, it is possible to sufficiently cope with the problem by adding a shutter or the like for covering the cutout portion 22.

The gas to be supplied into the purge tube 20 may be the same as the atmospheric gas in the heat treatment furnace 30, and is not necessarily limited to N2 gas.

Further, the present invention is not necessarily limited to the heat treatment of semiconductor wafers, and is applied to various heat treatments carried into the heat treatment furnace 30 by the transfer fork 11 and performing the heat treatment using the atmosphere gas in the furnace. It is possible.

[Effects of the Invention] According to each of the inventions described in claims 1 to 4, the purge tube and the transport fork can be moved independently and simultaneously, so that the transport fork is While maintaining the same structure as a conventional cantilever,
By adding the purge tube, the ambient atmosphere of the object to be processed can be purged independently of the heat processing furnace before the object to be processed is carried into the heat processing furnace.

[Brief description of drawings]

FIG. 1 is a schematic perspective view for explaining an example of the present invention, FIG. 2 is a schematic explanatory view showing the configuration of a purge tube and a heat treatment furnace of the heat treatment apparatus of FIG. 1, and FIG. 3 is a heat treatment apparatus of FIG. FIG. 4 is a schematic explanatory view showing the purge flow rate and the shutter opening / closing timing corresponding to the process and each step in FIG. 4, and FIG. 4 is a schematic explanatory view for explaining the conventional heat treatment apparatus. 1 ... Object, 2 ... Boat, 11 ... Transport fork, 20 ... Purge tube, 22 ... Gas supply port, 30 ... Heat treatment furnace, 31 ... Process tube, 32 ... Gas supply port , 41 ... Shutter, 42 ... Shutter guide member, 42a ... Guide hole, 42b ... Passage hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Tasetsu, 3210-1 Hongo, Kawajiri, Shiroyama-cho, Tsukui-gun, Kanagawa Teru Thermco Co., Ltd. (56) Reference JP 62-98624 (JP, A) JP 61-2330 (JP, A) JP 57-46647 (JP, B2) JP 62-21005 (JP, Y2)

Claims (4)

(57) [Claims] 1. A boat in which a plurality of objects to be processed are arranged is placed on a fork for transfer, and the fork for transfer is transferred into a heat treatment furnace for heat-treating the object to be processed. A heat treatment method for heat-treating an object in a state of being kept in non-contact with an inner wall of a heat treatment furnace, wherein a purge tube is independently moved in one direction with respect to the transfer fork, and the purge tube is moved onto the transfer fork. A step of enclosing the mounted boat with the purge tube; a step of supplying the same atmosphere gas as the heat treatment furnace into the purge tube enclosing the boat; Moving in one direction at the same time to set the open end of the purge tube and the open end of the heat treatment furnace in a communicating state in which they face each other; A step of supplying the same atmosphere gas into the heat treatment furnace and the ditube, and thereafter, the transfer fork is independently moved in the one direction with respect to the purge tube to treat the object to be treated in the heat treatment furnace. A heat treatment method comprising: a step of setting the position. 2. A step of closing the open end of the heat treatment furnace with a shutter until at least the open end of the purge tube and the open end of the heat treatment furnace are set to face each other and communicate with each other; The heat treatment method according to claim 1, further comprising: a step of opening the shutter before the transfer fork is carried into the heat treatment furnace. 3. The heat treatment method according to claim 2, further comprising the step of supplying the atmospheric gas to a region where the shutter is opened and closed. 4. A boat on which a plurality of objects to be processed are arranged is placed on a fork for transfer, and the fork for transfer is transferred into a processing furnace for heat-treating the object to be processed, and the fork for transfer is A heat treatment method for heat-treating an object in a state of being kept in non-contact with an inner wall of a heat treatment furnace, wherein a purge tube having a notch portion into which the transport fork is inserted is provided with respect to the transport fork. Moving independently in one direction, surrounding the boat mounted on the transfer fork with the purge tube, and in the purge tube surrounding the boat, the same atmosphere gas as the heat treatment furnace The step of supplying, the transfer fork and the purge tube are simultaneously moved in the one direction, and the open end of the purge tube and the open end of the heat treatment furnace are opposed to each other so that they communicate with each other. And a step of supplying the same atmospheric gas into the purge tube and the heat treatment furnace in the communication state, and then, the transfer fork is independently with respect to the purge tube in the one direction. And moving the object to be processed to a processing position in the heat treatment furnace, wherein when the object to be processed is set to the processing position, the cutout portion of the purge tube is moved to the transfer position. A heat treatment method characterized by closing with a shutter formed on a fork for use.