JPH088204A - Heat treating apparatus - Google Patents

Abstract

PURPOSE:To provide a heat treating apparatus, wherein the formation of an oxide film on a wafer is prevented, and the temperature distribution in a core tube is made uniform with the flow rate of gas flowing in the core tube being suppressed to the low value. CONSTITUTION:A heat treating apparatus 10 has a core tube part 12, a circulating line 14, an electric-furnace gas heater, a fan device 18, a water cooling type gas cooler 20 and gas introducing devices 22 and 23. The core tube part 12 comprises an inner tube 29 and an outer tube 35. The respective part is constituted of the main body having the opening part and the cap part, which is coupled with the opening part. The main bodies and the cap parts of the inner and outer tubes have the introducing pipes having the closing valves or exhuast pipes, respectively, and linked to the gas introducing system and the gas exhausting system of the circulating path having the closing valves. Many obstruction plates 40 are arranged on the inner wall of the inner tube separately in the longitudinal direction and the circumferential direction in the zig-zag pattern. After a wafer is contained, the gas is replaced with inert gas Linking with the core tube path is performed, and the inactive gas is circulated. The inactive gas is heated, and the wafer is heat-treated. The inactive gas is cooled, and the gas is changed into O2, and H2. Thus an oxidizing apparatus can be obtained.

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, and more particularly to heating a semiconductor device wafer to thermally diffuse impurities or form an oxide film on the wafer. The present invention relates to a heat treatment apparatus.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a heat treatment apparatus heats a wafer to thermally diffuse impurities,
Alternatively, it is used for performing annealing or forming an oxide film. Conventional heat treatment apparatus 80
As shown in FIG. 5, a core tube 84 having an opening with a shutter 82 at one end located at the position B, and a heater 86 provided on the outer periphery of the core tube 84 are provided. N ₂ gas, N ₂ provided on the other end of the core tube
The gas is introduced from the gas introduction port 88 and discharged from the discharge port near the shutter 82.

When the wafer S is subjected to the thermal diffusion processing, the wafers S are arranged on the wafer boat 90 and are made to stand by at the position A. On the other hand, when the furnace core tube 84 is heated by the heater 86 and reaches a predetermined temperature, the shutter 82 is opened, and the wafer boat 90 is fed into the core tube 84 by the boat loader 92 via the opening, and the predetermined temperature is reached. Place at position C. After a lapse of a predetermined time, the wafer boat 90 is taken out from the furnace core tube 84 in the reverse order and returned to the standby position A.

[0004]

However, the above-mentioned conventional heat treatment apparatus has the following problems.
First, the first problem is that an oxide film is formed on the surface of the wafer. When loading and unloading the wafer boat, the hot N ₂ gas is released in large quantities into the atmosphere from the opening through the furnace tube, near the opening of the outside air and the hot N ₂ gas are mixed together is
The atmosphere is such that high temperature oxygen is present. for that reason,
When the wafer S passes through the opening as the wafer boat is carried in and out, the wafer is oxidized by high-temperature oxygen and an oxide film is formed on the surface. In the manufacturing process of a semiconductor device, a step of removing this oxide film is performed after the heat treatment step, but before the removal, a phenomenon occurs in which impurities forming an oxide film cause abnormal diffusion of impurities in the semiconductor. . This phenomenon is
The finer and denser the semiconductor device is, the more it affects the characteristics of the semiconductor device, which is a problem in quality control of the semiconductor device.

As a second problem, the conventional heat treatment apparatus is
This means that it is necessary to flow a large amount of inert gas (mainly N ₂ gas) into the core tube in order to make the temperature distribution in the core tube uniform. This has contributed to the increased cost of the heat treatment process.

In view of the above problems, it is the first object of the present invention.
The second object is to provide an improved heat treatment apparatus so that an undesired oxide film is not formed on the wafer in the heat treatment step. Secondly, the temperature distribution in the core tube can be reduced while suppressing the flow rate of the gas flowing in the core tube to be low. The object is to provide a heat treatment apparatus that is made uniform.

[0007]

In order to achieve the above-mentioned first object, a heat treatment apparatus according to the present invention is provided with a core tube having an opening / closing opening, and an object to be carried in / out through the opening is provided. In a heat treatment apparatus for heat-treating an object to be processed in a core tube, a gas inlet port with an opening / closing valve and a gas outlet port with an opening / closing valve are provided in the core tube, and the gas inlet port and the gas outlet port of the core tube are detachably connected respectively. Yes, the first with an on-off valve
A circulation pipe line having a connection port and a second connection port and adapted to circulate gas through the core tube, and a gas heating device, a gas cooling device, and a blower provided in the circulation pipe line. Is characterized by.

The core tube used in the present invention is a core tube made of the same material as the conventional core tube, for example, quartz, and may be horizontal type or vertical type. The gas heating device is a known means for heating the gas by flowing the gas into the heating pipe and heating the heating pipe from outside the pipe, and for example, a pipe line through which the gas flows is provided in the electric furnace. There is an electric furnace type gas heating device. The gas cooling device is a known gas cooling device of air cooling type or water cooling type. Further, as the blower, a known hot gas fan can be used.

In a preferred embodiment of the present invention, the core tube is
An inner pipe for arranging the object to be treated, and a double pipe composed of an outer pipe surrounding the inner pipe from the outside thereof, each having an on-off valve-equipped gas inlet and an on-off valve-equipped gas outlet, and Circulation pipelines are provided in each of the inner pipe and the outer pipe so that the flow direction of the gas flowing in the inner pipe and the flow direction of the gas flowing in the annular flow passage between the outer pipe and the inner pipe are opposite to each other. It is characterized by that.

In order to achieve the second object, the preferred embodiment according to the present invention is such that the inner wall of the core tube on which the object to be treated is placed is a hindrance to the flow of gas in the core tube. It is characterized by the provision of a plate. Here, the baffle plate is a flow obstacle which has a surface intersecting with the gas flow and which disturbs the gas flow in a turbulent state in terms of hydrodynamics, and is orthogonal to the gas flow direction. It has a function of making the gas flow velocity uniform at each position of the cross section of the flow path. The shape of the baffle is not particularly limited as long as it serves its purpose.

[0011]

According to the invention of claim 1, a wafer boat on which a wafer is placed is housed inside, the air is replaced with an inert gas, and the core tube isolated from the outside is also replaced with the air by an inert gas. And is connected to a circulation line isolated from the outside, and an inert gas is circulated along the circulation line by a blower via the core tube. Next, the circulating inert gas is heated by a gas heating device, and the wafer in the core tube is heat-treated with the high temperature inert gas. After completion of the heat treatment step, the gas heating device is stopped and the circulating inert gas is cooled by the gas cooling device. After cooling, separate the core tube from the circulation line,
Further, the opening is opened and the cooled wafer boat is taken out. To replace the inside of the furnace core tube with an inert gas and isolate it from the outside air, introduce an inert gas from the gas inlet and discharge the inert gas from the gas outlet while removing the inert gas from the gas inlet and the gas outlet. Close the on-off valve. Similarly, in order to replace the inside of the circulation line with an inert gas and isolate it from the outside air, the gas lines of the circulation line and the gas heating device, the gas cooling device, and the blower connected to the circulation line should not be separated. The on-off valves of the first connection port and the second connection port are closed while introducing and discharging the active gas.

In the invention of claim 2, the core tube is composed of a double tube, and the flow direction of the gas in the inner tube is opposite to the flow direction of the gas flowing in the annular portion between the inner tube and the outer tube. because there is,
When heating the core tube, the temperature distribution inside the inner tube can be made uniform. In addition, since the outer tube surrounds the inner tube, there is no risk of undesired foreign matter such as metal entering the inner tube from the outside.

According to the third aspect of the present invention, the baffle plate is provided on the core tube containing the wafer, so that the gas flow becomes turbulent and the flow velocity at each position of the cross section in the flow direction becomes uniform. Therefore, the temperature distribution in the core tube becomes constant with a small flow rate.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings. FIG. 1 is a schematic flow sheet showing the configuration of an embodiment of a heat treatment apparatus according to the present invention, FIG.
Is a schematic cross-sectional view showing the structure of the core tube, and FIG. 3 is a cross-sectional view taken along the line I-I of FIG. The heat treatment apparatus 10 of the present embodiment is
As shown in FIG. 1, a core tube part 12, a circulation line 14, an electric furnace type gas heating device 16, a fan device 18, a water cooling type gas cooler 20, a gas introduction device 22 and H for N ₂ and O ₂ gas and the like. It is provided with a gas introduction device 23 for _two gases or the like.

As shown in FIG. 2, the core tube portion 12 has an inner tube body 26 having an opening 24 at one end, and an opening portion 2.
The inner tube lid portion 28 that fits the outer periphery of 4 to close the opening portion 24
An outer pipe main body 32 having an opening 30 at the end on the same side as the inner pipe body 26 and an outer periphery of the opening 30 of the outer pipe body 32. The outer tube 35 includes an outer tube lid 34 that fits and closes the opening 30.

A gas discharge pipe 38 having an opening / closing valve 36 and a gas introduction pipe 44 having an opening / closing valve 42 are provided at the end of the inner pipe main body 26 opposite to the opening 24 and the inner pipe lid 34, respectively. Gas flows in the inner tube 29 in the direction X of the arrow. Further, a gas introduction pipe 48 having an opening / closing valve 46 and a gas discharge pipe 52 having an opening / closing valve 50 are provided at the end of the outer pipe main body 32 opposite to the opening 30 and the outer pipe lid 34, respectively. . The gas discharge pipe 36 of the inner pipe body 26 and the gas introduction pipe 44 of the inner pipe lid portion 26 are respectively connected to the outer pipe body 32.
And penetrates the end wall and the outer tube lid 34 and projects outward. The penetrating portion may be such that the pipe is integrally joined to the end wall or the lid wall, and after the pipe is pierced through the through hole of the end wall or the lid, the pipe is sealed with a sealant. May be. With the above configuration, an annular gas passage 54 is formed between the inner pipe 29 and the outer pipe 35, and the gas flows in the annular passage 54 in the direction of the arrow Y.

A large number of baffle plates 40 are provided on the entire inner wall surface of the inner tube body 26. The baffle plate 40 is shown in FIG.
3, the block has a substantially trapezoidal cross-sectional shape when viewed in the longitudinal direction of the inner pipe body 26, and as shown in FIG.
Are arranged in a staggered manner in the circumferential direction and in the longitudinal direction, and when viewed in the longitudinal direction (the broken line in FIG. 3 is an example of the staggered arrangement behind the baffle plate 40 indicated by the solid line. is there). As shown in FIG. 2, in each baffle plate 40, the surface 56 on the downstream side of the flow of gas forms a plane orthogonal to the longitudinal direction of the inner pipe body 26, and the surface 58 on the upstream side of the inner pipe body 26. A curved surface is formed so as to be separated from the surface 56 on the downstream side as it goes toward the wall surface, and the height from the wall surface of the inner tube main body 26 is dimensioned so as not to collide with the wafer mounted on the wafer boat.

The baffle plate 40 may be formed integrally with the inner pipe body 26, and as shown in FIGS. 4A and 4B, the baffle plate 40 has an outer diameter substantially equal to the inner diameter of the inner pipe body 26. It is also possible to separately form a baffle tube 59 in which a block of the baffle plate 40 is provided on the body 57, insert the baffle tube 59 into the inner tube body 26 if necessary, and pull it out when it is no longer needed. 4A is a longitudinal sectional view of the baffle tube 59, and FIG. 4B is FIG. 4A.
FIG. 11 is a cross-sectional view taken along line II-II of FIG.

As shown in FIG. 1, the circulation pipeline 14 includes an inner pipe system of a gas introduction system 60 and a gas discharge system 62 connected to the inner pipe 29, and a gas introduction system 64 connected to the outer pipe 35. The gas exhaust system 66 is composed of two systems of an outer pipe system. The gas introduction systems 60, 64 and the gas discharge systems 62, 66 are connected to the respective gas introduction pipes and the gas discharge pipes of the core tube part 12 by the connection parts 61, 63, 65, 67, and opened and closed in the vicinity of the connection parts. Valves 68, 70, 72 and 74 are provided.
The connecting method of the connecting portions 61, 63, 65, 67 is a so-called quick coupling type or a fitting type, which allows easy and quick connection. Further, in order to adjust the pressure of N ₂ gas in the circulation line, a pressure adjusting valve 76
Is provided in the circulation line 14.

The electric furnace type gas heating device 16 is a known gas heating device comprising a heating tube through which a gas flows and an electric furnace for heating the heating tube. If necessary, a bypass line may be provided around the gas heating device 16 to bypass the gas heating device 16 in the cooling step described later. Further, the fan device 18 is a known blower fan for high temperature gas that can blow high temperature gas. Water-cooled gas cooler 20
Is a known double-tube type water-cooled cooler, in which cooling water is caused to flow through the inner pipe and cooling gas is caused to flow through the annular space between the inner pipe and the outer pipe. If necessary, a bypass line may be provided around the gas cooler 20 to bypass the gas cooler 20 during the heating process described above. The N ₂ gas introducing device 22 is a device including an N ₂ gas cylinder and a gas pressure adjusting valve, and is connected to the circulation pipeline 14 via an opening / closing valve 78.

A method of heat treatment using the apparatus of this embodiment will be described below. First, the core tube section 12 is removed from the heat treatment apparatus 10, the wafer boat W on which the wafer S is placed is introduced into the inner tube body 26, and the inner tube lid section 26 is placed after the wafer boat W is placed at a predetermined position, as shown in FIG. The outer pipe cover 34 and the outer pipe cover 34 are fitted and closed on the outer peripheries of the openings 24 and 30 of the inner pipe main body 26 and the outer pipe main body 32, respectively. Then, the on-off valves 36, 42,
46 and 50 are opened, and an inert gas (mainly N ₂ gas, hereinafter referred to as N ₂ gas) is introduced from the on-off valves 42 and 46,
The air in the inner pipe 29 and the annular space 54 between the outer pipe and the inner pipe is discharged from the open valves 36 and 50. After the air is completely replaced with N ₂ gas, the open valves 36 and 50 are first closed, and then the open valves 42 and 46 are closed. As a result, the core tube portion 12 is isolated from the outside while being replaced with the N ₂ gas.

On the other hand, in FIG. 1, the on-off valve 78 is opened and the N ₂ gas is introduced from the N ₂ gas introducing device 22 into the circulation line 14
Open / close valves 68, 70, 72 and 7 introduced into
4. Air is exhausted from the gas heating device 16 and the fan device 1
8 and the air in the circulation line 14 including the inside of the gas cooler 20 are replaced with N ₂ gas. After replacement is completed, open / close valves 68, 7
0, 72 and 74 are closed, and the apparatus 10 is isolated from the outside while being replaced with N ₂ gas.

Next, the core tube section 12 is connected to the circulation line 14 by predetermined connecting sections 61, 63, 65 and 67, and all the on-off valves are opened. As a result, the core tube portion 12 and the circulation passage 14 are communicated with each other, and the heat treatment apparatus 10 is ready to start operation. The fan device 18 is started, and N ₂ gas is circulated along the circulation conduit 14 passing through the core tube portion 12. As needed,
The pressure of the N ₂ gas in the circulation line 14 is adjusted by the pressure adjusting valve 76. Then, heating is started by the gas heating device 16. The heated N ₂ gas is introduced into the gas introduction system 6 on the inner pipe side.
After entering the inner tube 29 from 0, the flow is disturbed by the baffle plate 40 to flow in the inner tube 29 in a turbulent state, and after heating the wafer S, it is heated again by the gas heating device 16 via the gas discharge system 62. Circulate. On the outer pipe side, the N ₂ gas enters the outer pipe from the gas introduction system 64, heats the inner pipe 29 while flowing in the annular flow path 54, and circulates via the gas discharge system 66. As a result, the wafer S in the inner tube 29 is heat-treated.

After the heat treatment process is performed for a predetermined time, the operation of the gas heating device 60 is stopped, and instead, the gas cooler 20 is operated to cool the circulating N ₂ gas. As a result, the wafer in the inner tube is cooled. After cooling is completed, core tube 1
2 is removed from the heat treatment apparatus 10, and the wafer boat W on which the wafer S is placed is taken out from the inner tube 29.

In the present embodiment, the wafer is carried into the inner tube 29 at room temperature by the above operation, and is unloaded from the inner tube 29 in a state of being cooled to room temperature after heat treatment. There is no risk of oxidation due to hot air as it did. Further, the muffle tube 12, since the direction of the N ₂ gas flowing through the annular channel 54 of the inner and direction of the N ₂ gas flowing through the inner tube 29 tube and outer tube are reversed, the furnace tube portion 12
It is possible to maintain a uniform temperature distribution in the longitudinal direction.
Further, the outside of the inner tube 29 accommodating the wafer is N ₂
Since the gas is flowing, it is possible to prevent unwanted foreign matter such as metal from entering the inner tube 29 from the outside and contaminating the wafer S. Since the N ₂ gas is disturbed by the baffle plate 40 and flows in the inner tube in a turbulent state, the temperature distribution becomes uniform and the wafer can be efficiently heated at a low flow rate. When oxidizing, the procedure is according to N ₂ gas,
O ₂ gas is supplied from the gas introduction device 22 and again the gas introduction device 2
Introduce H ₂ gas from 3.

This example shows one embodiment of the present invention, and instead of the double tube type core tube of this example,
A core tube having only an inner tube may be used, and it is not always necessary to provide a baffle plate on the wall surface of the inner tube. Further, the shape of the baffle plate does not have to be the same as that of this embodiment, and the shape is not particularly limited as long as it has the function of the baffle plate.

[0027]

According to the first aspect of the present invention, the wafer is placed in the heat treatment apparatus for heat treatment while being maintained in an inert gas atmosphere isolated from the outside, and the wafer is already cooled at the time of unloading. Therefore, unlike the conventional device, there is no fear of being oxidized by oxygen in the outside air. Further, since the time during which the wafer is exposed to the outside air is short, the wafer contamination can be suppressed. This heat treatment apparatus can be used as an annealing apparatus, a heat diffusion apparatus or a thermal oxidation apparatus by changing the type of gas to be circulated. In the invention of claim 2, since the core tube is composed of a double tube and the flow direction of the gas in the inner tube is opposite to the flow direction of the gas flowing in the annular portion between the inner tube and the outer tube, When heating the core tube, the temperature distribution inside the inner tube can be made uniform. In addition, since the outer tube surrounds the inner tube and the gas flows in the annular flow path between the inner tube and the outer tube, undesired foreign matters such as metal are externally introduced into the inner tube in the heat treatment step. Can be prevented from invading into and contaminating the wafer. In the invention of claim 3, since the baffle plate is provided in the core tube containing the wafer, the gas flow becomes turbulent and the flow velocity at each position of the cross section in the flow direction is made uniform. The flow rate makes the temperature distribution in the core tube constant. Therefore, the required amount of inert gas is reduced.

[Brief description of drawings]

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

FIG. 2 is a schematic longitudinal sectional view showing the structure of a core tube.

3 is a cross-sectional view taken along the line I-I of FIG.

4 (a) is a longitudinal sectional view of the baffle plate tube 59, and FIG. 4 (b) is a transverse sectional view taken along the line II-II of FIG. 4 (a).

FIG. 5 is a schematic cross-sectional view showing the configuration of a conventional heat treatment apparatus.

[Explanation of symbols]

10 Example of heat treatment apparatus according to the present invention 12 Core tube section 14 Circulation pipeline 16 Electric furnace type gas heating apparatus 18 Fan apparatus 20 Water cooling type gas cooler 22 Gas introduction apparatus (N ₂ gas, O ₂ gas, etc.) 23 Gas introduction device (H ₂ gas or the like) 24 Opening 26 Inner tube body 28 Inner tube lid 29 Inner tube 30 Opening 32 Outer tube body 34 Outer tube lid 35 Outer tube 36, 42, 46, 50 Open / close valve 38, 52 gas discharge pipe 40 baffle plate 44, 48 gas introduction pipe 54 annular flow path 56, 58 baffle plate surface 57 tube body 59 baffle plate pipe 60, 64 gas introduction system 61, 63, 65, 67 connection part 62, 66 gas Discharge system 68, 70, 72, 74, 78, 79 Open / close valve 76 Pressure adjustment valve

Claims (3)

[Claims] 1. A heat treatment apparatus comprising a core tube having an openable and closable opening, wherein an object to be processed carried in and out through the opening is heat-treated in the core tube, wherein a gas inlet port with an open / close valve and an opening / closing valve are provided in the core tube. With a gas outlet, and further comprises a first connecting port with an opening / closing valve and a second connecting port which can be detachably connected to the gas inlet and the gas outlet of the core tube, respectively, and through the core tube. A heat treatment apparatus comprising: a circulation pipeline configured to circulate gas by means of a gas, a gas heating apparatus, a gas cooling apparatus, and a blower provided in the circulation pipeline. 2. The core tube is composed of a double tube consisting of an inner tube for arranging an object to be treated and an outer tube surrounding the inner tube from the outside thereof, and a gas introduction port with an on-off valve and an on-off valve, respectively. Of the inner pipe and the outer pipe so that the flow direction of the gas flowing in the inner pipe and the flow direction of the gas flowing in the annular flow path between the outer pipe and the inner pipe are opposite to each other. The heat treatment apparatus according to claim 1, wherein each of the heat treatment apparatuses is provided with a circulation line. 3. The inner wall of the core tube in which the object to be treated is placed,
The heat treatment apparatus according to claim 1 or 2, further comprising a baffle plate that makes a gas flow in the core tube turbulent.