JPH07106255A - Vertical heat treatment equipment - Google Patents

Abstract

PURPOSE:To enable increasing the freedom of heat treatment by preventing the corrosion of a manifold. CONSTITUTION:A cover composed of quartz is installed so as to cover the inner peripheral surface of a metal manifold on the lower side of a reaction tube, and N2 gas is supplied for purging from a gas introducing tube 40 into a gap S between the cover and the manifold. The inner edge portions of gas supplying tubes 5, 7 and discharging tubes 6, 8 are constituted of quartz tubes 52, 62, 72, 82, and through holes are formed in the cover. Quartz boards 54, 64 74, 84 are engaged with the through holes and welded, and the quartz tubes 52, 62, 72, 82 are inserted into the holes of the quartz boards 54, 64, 74, 84. Cylindrical members having flanges are engaged with the parts between the quartz tubes 52, 62, 72, 82 and the quartz boards 54, 64, 74, 84.

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.

[0002]

2. Description of the Related Art Low pressure CVD (Chemical vapor deposition) is one of the heat treatment processes in the manufacturing process of semiconductor wafers.
There is a process called. This low pressure CVD is a method of forming film forming components in a processing gas on the surface of a semiconductor wafer (hereinafter referred to as “wafer”) by a gas phase reaction under a reduced pressure.
A vertical heat treatment apparatus, which is less involved in the atmosphere, is becoming the mainstream of the apparatus.

As shown in FIG. 5, a conventional vertical low pressure CVD apparatus has a double-tube structure reaction tube 1 composed of a quartz inner tube 1a and an outer tube 1b, and a reaction tube 1 surrounding the reaction tube 1. A heater 11 provided and a stainless steel manifold 12 provided on the lower side of the reaction tube 1 are provided, and a plurality of gas introduction pipes are provided around the manifold 12 so that a plurality of kinds of processing gases can be introduced. 13 (only one is shown in the figure) and the exhaust pipe 14 are connected. And CV
In carrying out D, a large number of wafers W are stacked on the wafer boat 15 and the boat elevator 16 is raised to load the wafers W to heat the inside of the reaction tube 1 to a predetermined temperature and maintain a predetermined vacuum degree. While processing gas into reaction tube 1
A thin film is formed on the surface of the wafer W by introducing it into the inside by CVD.

[0004]

By the way, in the case of performing low pressure CVD, since the manifold 12 made of stainless steel is used so as to be compatible with a plurality of types of processing, it has corrosion resistance, but if the processing temperature becomes considerably high, it will corrode. Corrosion is accelerated when a large gas is used. For this reason, there is a problem that the type of gas used is limited at high temperatures.

The present inventor has also found that the oxidation / diffusion treatment and the reduced pressure C
We are studying a vertical heat treatment apparatus that can perform VD in a common furnace.
(Hydrogen chloride) may be mixed in the process gas. This HCl has the advantage that impurities can be carried away to the outside and a good quality film can be obtained, but when H ₂ O is present, it exhibits extremely strong corrosiveness and corrodes the inner peripheral surface of the stainless steel manifold 12, resulting in particles and heavy metals. Will become a source of pollution.
If the manifold is made of quartz, the problem of corrosion can be solved, but it is difficult to manufacture and the cost is high, and it is difficult to join the external pipe and the intake / exhaust port.

The present invention has been made under such circumstances, and an object of the present invention is to provide a vertical heat treatment apparatus having a large degree of freedom in processing.

[0007]

According to a first aspect of the present invention, a metal manifold to which a gas supply pipe and an exhaust pipe are connected is provided on the lower side of a vertical reaction tube, and a large number of objects to be processed are provided. In a vertical heat treatment apparatus which is mounted on a holder and carried into a reaction tube through a lower end opening of a manifold, a cover made of a heat-resistant material is provided so as to cover an inner peripheral surface of the manifold, and an inner circumference of the cover and the manifold. It is characterized by comprising an inert gas introducing means for introducing an inert gas into the gap between the surfaces.

According to a second aspect of the present invention, in the first aspect of the present invention, the cover is made of quartz, and a pipe fitting hole is formed on a side peripheral surface of the cover, and the periphery of the pipe fitting hole is a flat surface. The inner end portion of the gas supply pipe and / or the exhaust pipe is made of quartz and fitted in the pipe fitting hole.

According to a third aspect of the present invention, in the second aspect of the present invention, a cylindrical body made of quartz having a collar portion is provided on the inner surface or the outer surface of the flat portion around the pipe fitting hole. It is characterized in that it is fitted into a pipe fitting hole so as to be in contact, and the inner end portion of the gas supply pipe and / or the exhaust pipe is inserted into the tubular body.

According to a fourth aspect of the present invention, in the second aspect of the present invention, a flange portion made of quartz is integrally formed at an inner end portion of the gas supply pipe and / or the exhaust pipe, and the flange portion is used for pipe fitting. It is characterized in that the inner end portion is inserted into a hole for fitting a pipe so as to come into surface contact with an inner surface or an outer surface of a flat portion around the hole.

[0011]

According to the first aspect of the present invention, since the cover made of the heat-resistant material is provided so as to cover the inner peripheral surface of the manifold and the inert gas is supplied to the gap between them, the manifold is purged by the inert gas. It is possible to avoid contact of the inner peripheral surface with the processing gas and prevent corrosion of the manifold.

According to the invention of claim 2 or 4,
Since a through hole is formed in the cover made of quartz and the periphery is made a flat surface and the quartz pipe on the inner end side of the gas pipe (gas supply pipe and exhaust pipe) is fitted to the flat surface, the gas pipe and the cover are The gap can be made small and the manufacturing is easy. In this case, if the gas pipe is inserted into the cylindrical body and the flange portion and the flat surface portion of the cylindrical body are brought into surface contact with each other as in the invention of claim 3, the diameter of the quartz tube and the through hole of the cover can be determined. , High position accuracy is not required.

[0013]

1 is a view showing a vertical heat treatment apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are a sectional view and an exploded perspective view showing the main part of the vertical heat treatment apparatus of FIG. 1, respectively. . Reaction tube 2
Is an inner tube 2a made of a heat-resistant material such as quartz, which is open at both ends and is arranged in the vertical direction, and a cylindrical bottomed tube, for example, quartz, which is concentrically arranged so as to surround the inner tube 2a. It is configured as a double tube structure including an outer tube 2b made of.

On the outside of the reaction tube 2, a heating furnace 23, which is constructed by attaching a heater 22 made of a resistance heating wire to the inside of a heat insulator 21, is arranged so as to surround the reaction tube 2. The reaction tube 2 is held by a manifold 3 fixed to a base plate 30.
Is made of, for example, stainless steel. A cap portion 31 made of, for example, stainless steel is openably and closably provided in the lower end opening of the manifold 3, and when closed, the opening is hermetically sealed via an O-ring (not shown).

The cap portion 31 is arranged on a boat elevator 24 which is raised and lowered by, for example, a ball screw, and a wafer boat 26 made of quartz, for example, is placed on the cap portion 31 via a heat retaining cylinder 25. . The wafer boat 26 is for holding and stacking a large number of wafers W in a horizontal state by vertically stacking them. However, in the example of FIG. 2, the boat elevator 24 is attached with the rotating mechanism 28 having the rotating shaft 27, and the heat insulating cylinder 25 is provided with the rotating shaft 2
It is mounted on a turntable 29 that rotates by 7.

Inside the manifold 3, a cover 4 made of a heat resistant material such as quartz is provided so as to cover the inner peripheral surface of the manifold 3. The cover 4 is made smaller in diameter on the lower side than the diameter on the upper side. A step portion in the middle of the cover 4 abuts on an annular protrusion 32 formed on the inner peripheral surface of the manifold 3, and The outer edge of the upper end is engaged with the inner edge of the upper end of the manifold 3.

A ring member 33 made of a heat resistant material such as quartz is provided on the upper surface of the cap portion 31.
Is concentrically embedded with respect to the ring member 3
The outer edge portion and the inner edge portion of 3 are raised pieces 34 and 35 (see FIG. 2) which are bent and raised upward. The lower end of the cover 4 has a standing piece 34 on the outer edge side of the ring member 33.
And is held in a state of maintaining a constant interval (0.05 to 0.7 cm). Further, a leg portion 25a is formed in an annular shape at the bottom of the heat insulating cylinder 25, and the heat insulating cylinder 25 has a leg portion 25a at a constant distance (0.05) from the outer side of the standing piece 35 on the inner edge side of the ring member 33. (-0.7 cm) is maintained.

An inner pipe 2a is provided on the side surface of the manifold 3 in the previous term.
A first gas supply pipe 5 for supplying the processing gas to the inner region of the chamber is connected to a first exhaust pipe 6 for exhausting the processing gas from the gap between the inner pipe 2a and the outer pipe 2b. Has been done. The gas supply pipe 5 and the exhaust pipe 6 are piping systems used for low pressure CVD, and a gas supply source and a vacuum pump (not shown) are connected to the outer ends of the gas supply pipe 5 and the exhaust pipe 6, respectively. .

In addition to the piping system for low pressure CVD, a second gas supply pipe 7 for supplying a processing gas to the gap between the inner pipe 2a and the outer pipe 2b is provided on the side surface of the manifold 3. And a second exhaust pipe 7 for exhausting the processing gas from the area inside the inner pipe 2a. The second gas supply pipe 7 and the exhaust pipe 8 are piping systems used for the oxidation treatment, and are the gas supply pipe 7 and the exhaust pipe 8.
A gas supply pipe and an exhaust pump (not shown) are connected to the outer end sides of the respective.

Here, the connection structure between these piping systems and the cover 4 will be described with reference to FIGS. For example, in the first gas supply pipe 5, an inner end portion extending from the intake port 51 to the inside of the manifold 3 is configured by a quartz pipe 52, and the inner end of the quartz pipe 52 is bent upward, 51 to the outside is a stainless tube 53
It is composed by.

On the other hand, a circular through hole 41 (see FIG. 3) corresponding to the first gas supply pipe 5 is formed on the side peripheral surface of the cover 4, and the through hole 41 has the through hole 41 therein. 41
A quartz plate (which is formed in a ring shape in this example, as can be seen from FIG. 3) having a shape conforming to the above and forming a flat surface having a sufficient thickness capable of closing the through hole 41. Fitted and welded. The quartz plate 54 is formed with a hole 55 (see FIG. 3) for fitting a pipe, a flange portion 56 is formed on the inner end side, and the inner diameter of the quartz tube 52 is 52.
A cylindrical body 57 made of quartz that fits the tube diameter is fitted in the hole 55 of the quartz plate, and the inner surface of the flange 56 is in surface contact with the inner surface of the quartz plate 54. The hole 55 is about 4 mm larger than the outer diameter of the tubular body 57, and
The structure is such that the axial deviation of the cover 4 can be absorbed. Further, a quartz tube 52 is inserted in the cylindrical body 57,
Thus, in this example, the quartz tube 52 is fitted into the pipe fitting hole 55 of the quartz plate 54 via the tubular body 57.

The second gas supply pipe 7 and the exhaust pipe 8 are also connected to the cover 4 in the same manner. However, in this example, the first exhaust pipe 6 does not use a cylindrical body. It is different from the pipe connection structure. That is, the tube wall of the inner end portion of the quartz pipe in the first exhaust pipe 6 is cut off from the outside to reduce the diameter, and the reduced diameter portion 6a fits into the through hole 65 of the quartz plate 64 and the pipe wall The step portion 6b is in contact with the inner peripheral surface of the quartz plate 64.

In FIGS. 2 and 3, 42 to 44 are through holes, 6
1, 81 are exhaust ports, 71 are intake ports, 62, 7
2, 82 are quartz tubes, 63, 73, 83 are stainless steel tubes,
64, 74, 84 are quartz plates welded to the cover 4, 6
5, 75 and 85 are holes for fitting pipes, 76 and 86 are flanges,
77 and 87 are cylindrical bodies made of quartz.

On the upper side and the lower side of the manifold 3, an inert gas such as N ₂ gas is introduced into the gap S between the inner peripheral surface of the manifold 3 and the cover 4 to prevent the processing gas from entering. Inert gas introducing means for this purpose, for example, gas supply pipes 40a and 40b are respectively connected.

The cap portion 31 has a cap portion 31.
A gas supply pipe 40c for introducing N ₂ gas is connected to a gap between the heat insulation cylinder 25 and the heat insulation cylinder 25.

Next, the operation of the above embodiment will be described.
First, the inside of the reaction tube 2 is heated by the heater 22 to, for example, a uniform temperature of 780 ° C., and the wafer W to be processed is heated to, for example, 50
The wafer boat 35 is held in a shelf shape and loaded into the reaction tube 2 by the boat elevator 33. Then, the inside of the reaction tube 2 is evacuated by a vacuum pump (not shown) through the first exhaust pipe 6 to a depressurized state of the order of, for example, 10 ⁻³ Torr, and then the processing gas such as ammonia ( NH ₃ ) gas and dichlorosilane (SiH
₂ Cl ₂ ) gas at a flow rate of 0.03 liters per minute and 0.03 liters per minute, respectively, and a mixed gas is supplied to the inner pipe 2a.
Supply to the area inside.

The inner tube 2a is controlled while controlling the pressure so that the pressure inside the reaction tube 2 is maintained at a reduced pressure of, for example, 1 Torr.
The gas is exhausted from the gap between the outer tube 2b and the outer tube 2b through the exhaust tube 6, and a Si ₃ N ₄ film is formed on the surface of the wafer W. At this time, N ₂ gas is supplied into the gap S between the cover 4 and the manifold 3 and the gap between the cap portion 31 and the heat insulating cylinder 25 by the gas supply pipes 40a to 40c to prevent the processing gas from entering the gap. To prevent. In this embodiment, the cover 4 is placed in the manifold 3, and the heat retaining cylinder 25 is only placed on the cap portion 31. Therefore, there is a gap between them and the N ₂ gas (nitrogen gas) is present. Part of the gas flows out of the cover 4 toward the inner side of the furnace than the cover 4, and the other part of the gas is sucked into the stainless steel pipe 63 through the space between the exhaust port 61 and the quartz pipe 62 in the exhaust pipe 6.

Thereafter, the atmosphere in the reaction tube 2 is changed to N ₂ for example.
The gas in the reaction tube 2 is replaced with a gas, and the temperature in the reaction tube 2 is raised to about 1000 ° C. at a heating rate of 50 ° C./min. The replacement with N ₂ gas is performed by the first exhaust pipe 6 while supplying N ₂ gas to the inside of the inner pipe 2a from a gas supply pipe (not shown) provided in the manifold 3 like the first gas supply pipe 4, for example. It is performed by evacuating.

After the evacuation is stopped, the second gas supply pipe 6 is used to connect, for example, H ₂ between the inner pipe 2a and the outer pipe 2b.
A mixed gas in which O and HCl were caused to flow at a rate of 10 liters per minute and a rate of 1 liter per minute, respectively, was supplied, and the inside of the inner tube 2a was exhausted through the second exhaust tube 8 to bring the inside of the reaction tube 2 to a normal pressure state. In this way, the surface of the Si ₃ N ₄ film is oxidized and S
An iO ₂ film is formed. Even during this oxidation process, N ₂ gas is purged into the gap S from the gas supply pipe 40.

According to the above-described embodiment, the inner peripheral surface of the manifold is covered with the cover 4 made of quartz, and N ₂ gas is supplied to the gap S between the cover 4 and the manifold 3 for purging. _The manifold 3 and the processing gas atmosphere are shut off by the _two gases, and the manifold 3 is prevented from being corroded even if a highly corrosive gas is used at a high temperature. Therefore, for example, by using an oxidizing gas containing HCl gas,
Corrosion of the manifold 3 does not proceed even if the oxidation treatment is performed at a temperature as high as 0 ° C. or more, so that it can be used as an apparatus that can be used for both CVD and oxidation treatment.

Then, through holes 41 to 4 are formed in the side peripheral surface of the cover 4.
4 into the quartz plates 54, 64, 74, 84.
And the gas pipe (5-8) connection structure described above is adopted, the gap between the gas pipe (5-8) and the cover 4 can be minimized and the through holes 41-44 can be formed. It is easy to manufacture because it requires only a low position accuracy. That is, when the quartz tubes 52, 62, 72, and 82 are integrated with the cover 4, since the height position and the circumferential position of each of the intake port and the exhaust port of the manifold 3 are different, the quartz tubes are correspondingly provided. It is extremely difficult to attach 52, 62, 72, and 82, but if the quartz tube 52 is inserted into this with a slight margin as described above, for example, by using the tubular body 57, the collar portion 56 and the quartz plate 74 are provided. The gap between the intake port or the exhaust port and the through hole is absorbed by the rubbing against each other and the flange portion 56 and the quartz plate 74 are in surface contact with each other, so that the gap can be reduced.

Further, when the step portion 6b is formed at the inner end of the quartz tube 62 and is inserted into the quartz plate 64 with a slight margin as in the case of the first exhaust pipe 6, the step portion 6b and the quartz plate 6 are also provided.
The amount of misalignment can be similarly absorbed by rubbing with No. 4. In this case, the quartz pipes 52, 62, 72, 82 are made slightly smaller than the diameter of the intake port (or the exhaust port), whereby the above-mentioned misalignment can be sufficiently absorbed. Further, also in the cap portion 31, since the space between the heat insulating cylinder 25 and the cover 4 is covered with the quartz ring member 33, corrosion due to the processing gas is suppressed.

Further, since the film forming process and the oxidization process are carried out by using the common reaction tube 2, the throughput is remarkably improved and the space occupied by the device is increased as compared with the case where the conventional process is carried out by separate devices. It can be made narrower, and there is no risk of the wafer W being damaged when the wafer W is transferred.
Further, since the SiO ₂ film is continuously formed without carrying out the wafer W from the reaction tube 2 after forming the Si ₃ N ₄ film, an unnecessary oxide film is not formed between these thin films. Also, impurities such as water will not be mixed.

In the above, the connection structure between the gas pipes (5 to 8) and the cover 4 may be a structure other than that of the above-mentioned embodiment. For example, as shown in FIG. 4, the inner end portion made of quartz in the gas supply pipe 9 is used. The flange portion 91 made of quartz is integrally formed on the inner surface of the manifold 4, and the periphery of the pipe fitting hole 45 of the manifold 4 is formed as a flat surface portion 46 so that the flange portion 91 is in surface contact with the inner surface or the outer surface of the flat surface portion 46. In addition, the inner end portion may be inserted into the hole 45. Such a structure may be applied when the exhaust pipe is attached to the manifold. The material of the cover 4 is not limited to quartz, and the gap S between the cover 4 and the manifold 3 is not limited to quartz.
The inert gas to be supplied to the gas may be a gas other than N ₂ gas.

Further, the present invention may have a structure dedicated to a CVD furnace, instead of the combination of the oxidation / diffusion furnace and the CVD furnace as described above.

[0036]

According to the first aspect of the present invention, since a cover made of a heat-resistant material is provided so as to cover the inner peripheral surface of the manifold and an inert gas is supplied to the gap between them, corrosion of the manifold is prevented. It is possible to relax the restrictions on the type of processing gas and the processing temperature.

According to the second and fourth aspects of the present invention, a pipe fitting hole is formed in the cover made of quartz, a flat surface is formed around the hole, and a gas pipe (gas supply pipe and exhaust pipe) is formed in the flat portion. Since the quartz tube on the inner end side of () is fitted, the gap between the gas pipe and the cover can be made small, and the production is easy. In this case, if the gas pipe is inserted into the cylindrical body and the flange portion of the cylindrical body and the quartz plate are brought into surface contact with each other as in the invention of claim 3, the diameter of the quartz pipe and the pipe fitting hole of the cover. It is easy to manufacture because it does not need to be so precise.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of an embodiment of the present invention.

FIG. 3 is an exploded perspective view showing a main part of the embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a part of another embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional vertical heat treatment apparatus.

[Explanation of symbols]

2 Reaction Tube 26 Wafer Boat 3 Manifold 31 Cap Part 4 Cover 5, 7 Gas Supply Pipe 6, 8 Exhaust Pipe 51, 61, 71, 81 Quartz Pipe 54, 64, 74, 84 Quartz Plate 57, 67, 87 Collar 40 Gas (N ₂ gas) inlet pipe S gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Yamaga 1-24-1 Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Prefecture Inside the Sagami Business Office, Tokyo Electron Tohoku Co., Ltd. Muko Toshiba-cho 1 Co., Ltd. Toshiba R & D Center (72) Inventor Akito Yamamoto 1 Komukai-Toshiba-cho 1, Kawasaki-shi, Kanagawa 1 Toshiba Corporation R & D Center

Claims (4)

[Claims] 1. A metal-made manifold, to which a gas supply pipe and an exhaust pipe are connected, is provided on the lower side of a vertical reaction tube, and a large number of objects to be processed are mounted on a holder to open the lower end of the manifold. In a vertical heat treatment apparatus for further loading into a reaction tube, a cover made of a heat-resistant material provided so as to cover the inner peripheral surface of the manifold, and an inert gas in a gap between the cover and the inner peripheral surface of the manifold. A vertical heat treatment apparatus comprising: an inert gas introduction unit for introducing the gas. 2. The cover is made of quartz, and a pipe fitting hole is formed on a side peripheral surface of the cover, and a periphery of the pipe fitting hole is a flat portion, and the inside of the gas supply pipe and / or the exhaust pipe is 2. The vertical heat treatment apparatus according to claim 1, wherein the end portion is made of quartz and is fitted in the pipe fitting hole. 3. A tubular body made of quartz having a flange is fitted into a pipe fitting hole so that the flange comes into surface contact with an inner surface or an outer surface of a flat portion around the hole for fitting the pipe. The vertical heat treatment apparatus according to claim 2, wherein the inner end portions of the gas supply pipe and / or the exhaust pipe are inserted into the cylindrical body while being combined. 4. A flange part made of quartz is integrally formed on an inner end portion of the gas supply pipe and / or the exhaust pipe, and the flange part is formed on an inner surface or an outer surface of a flat surface portion around a pipe fitting hole. The vertical heat treatment apparatus according to claim 2, wherein the inner end portion is inserted into a pipe fitting hole so as to be in contact with each other.