JP2001015498A - Heat treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an unreacted alkoxysilane gas to reach a vacuum pump by providing a second trap equipped with a cooling means which cools the internal wall surface of a trap main body and a liquid storing section between a first trap and the vacuum pump. SOLUTION: An exhaust pipe 5 is airtightly connected to the periphery of the part of a manifold 4 higher than a supporting ring 41, and a second trap 6 which is a cooling trap is connected to the poststage of the pipe 5 through a first trap 51 and a valve V1. In addition, a vacuum pump 8 is connected to the exhaust side of the second trap 6 through another exhaust pipe 7. The second trap 6 is provided with a cylindrical container 61 constituting a trap main body, and a refrigerant flowing passage 64 is provided in the side wall of the container 61. In addition, a liquid storing section 65 is provided in the lower part of the container 61 by using the cooling water in the passage 64 so as to store the mist of a cooled unreacted process gas.

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 for treating an object using alkoxysilane as a treatment gas.

[0002]

2. Description of the Related Art One of the manufacturing processes of a semiconductor device is to form a film on an object to be processed by a method called a low pressure CVD (Chemical vapor deposition) process. As one of conventional apparatuses for performing such a film forming process, there is a vertical heat treatment apparatus as shown in a schematic diagram of FIG.

This vertical heat treatment apparatus performs heat treatment on an object to be processed in a batch system. A silicon oxide (SiO 2) film is formed using this apparatus as follows.
First, a holder 1 called a wafer boat is placed in a cylindrical reaction tube 1 composed of a double tube of an inner tube 11 and an outer tube 12 made of quartz.
3 holds a large number of wafers (objects to be processed) W in shelves,
This is carried in from below. Thereafter, the pressure in the reaction tube 1 is adjusted to about 0.1 Torr, a heating atmosphere of about 700 ° C. to 750 ° C. is set by the heater 14, and vapor of tetraethoxysilane (TEOS) is supplied from the gas introduction pipe 15 into the reaction tube 1. Then, a film forming process on the wafer W is performed.

The gas in the reaction tube 1 is supplied to an exhaust pipe 17 connected to the peripheral surface of the cylindrical manifold 16 below the reaction tube 1.
Is sucked by the vacuum pump 18 through Exhaust pipe 17
Is provided with a disc trap 19 and a valve 20, and the disc trap 19 removes reaction products contained in the exhaust gas.

[0005]

However, since the line width of the circuit pattern has been reduced in recent years, the pressure in the reaction tube 1 is reduced to, for example, 4 Torr in order to satisfactorily fill the recess without generating voids. It has been studied to set the process temperature to a low level and set the process temperature as low as, for example, 600 ° C. to 650 ° C.

[0006] However, when the above-mentioned film forming process in which the processing conditions are performed at high pressure and low temperature is performed, the amount of unreacted TEOS gas increases. Here, the disk trap 19 provided in the conventional apparatus can recover the reaction product of TEOS, but cannot sufficiently recover the TEOS gas itself.
8 is reached. Therefore, the maintenance work of the vacuum pump 18 needs to be frequently performed, and there is a concern that the operation efficiency is reduced.

The present invention has been made under the circumstances described above. For example, when heat treatment is performed using an alkoxysilane gas such as vapor of tetraethoxysilane,
The purpose is to suppress the amount of unreacted alkoxysilane gas reaching the vacuum pump.

[0008]

According to the present invention, an alkoxysilane gas is introduced as a processing gas into a processing vessel into which an object to be processed has been carried, and the processing vessel is evacuated through an exhaust path and heated under an atmosphere. In the heat treatment apparatus for performing heat treatment on the object to be processed, a vacuum pump connected to the exhaust path and a vacuum pump provided in the middle of the exhaust path to collect a reaction product of the processing gas by reducing the exhaust conductance. One trap and a second trap provided between the first trap and the vacuum pump in the exhaust path and cooling an unreacted process gas and collecting it as a mist. A trap body configured such that an inflow port and an exhaust port do not face each other; cooling means for cooling an inner wall surface of the trap body; and a trap body. Than said air outlet is formed on the lower side, characterized in that it and a reservoir for reserving the mist at.

Here, the exhaust path on the exhaust port side of the second trap preferably has a portion extending upward from the exhaust port.

[0010] When the heat treatment is performed in a vacuum atmosphere of a relatively high pressure, for example, 1 Torr to 10 Torr, the amount of unreacted alkoxysilane gas increases, which is particularly effective in this case.

[0011]

FIG. 1 is a schematic view showing an example of a vertical heat treatment apparatus according to the present invention. Reference numeral 3 denotes a reaction tube, which is, for example, a double tube including an inner tube 31 and an outer tube 32 each made of quartz. The outer tube 32 is provided concentrically with the inner tube 31 with its upper end closed, and the manifold 4 which is a metallic cylindrical body is hermetically connected to the lower side. The inner tube 31 is open at the upper side, is provided so as to form an appropriate interval with the outer tube 32, and is supported by a support ring 41 formed to protrude from the inner peripheral surface of the manifold 4. In this example, a processing vessel is constituted by the reaction tube 3 and the manifold 4.

The inner tube 31 forms a heat treatment atmosphere for a wafer W to be processed, which is placed in a shelf shape on a wafer boat (holding tool) 34 carried in from a lower opening of the manifold 4 by a boat elevator 33. A lid 35 is provided above the boat elevator 33 so as to close the lower opening of the manifold 4.

A heat insulator 36 is provided around the reaction tube 3 so as to surround it, and a heater 37 comprising, for example, a resistance heater is provided on the inner wall surface of the heat tube to constitute a heating furnace.

A hole 42 (only one is drawn for convenience of illustration) is formed on the peripheral surface of the manifold 4 below the support ring 41 so that a plurality of processing gas gas introduction pipes can enter therein. The gas introduction pipes 4 for supplying the processing gas to the inner side of the inner pipe 31 are provided in the respective holes 42.
3 is inserted, and the tip is bent upward. A vapor source of an alkoxysilane gas, for example, tetraethoxysilane (TEOS), is supplied from the gas source of the processing gas into the reaction tube 3 through the gas introduction tube 43.

On the other hand, the support ring 4 in the manifold 4
An exhaust pipe 5 is hermetically connected to a peripheral surface of a portion higher than the first pipe 1. A second trap, which is a cooling trap via a first trap 51 and a valve V1, is provided downstream (on the downstream side) of the exhaust pipe 5. 6 are connected. A vacuum pump 8 is connected to the exhaust side of the second trap 6 via an exhaust pipe 7.

The first trap 51 has a large number of disks 5 inside a cylindrical trap body 51a whose inner wall can be heated, for example.
1b is provided in a shelf shape, and the exhaust conductance is reduced by the disks 51b so that the reaction products in the exhaust gas collide with and adhere to the disks 51b.

FIG. 2 is a longitudinal sectional view schematically showing the second trap 6. The second trap 6 includes a cylindrical container 61 that forms a trap body having openings 62 and 63 that form an inlet and an outlet on an upper surface and a side surface, respectively. The opening 62 on the upper surface has a valve V1 on the upstream side. Exhaust pipe 50 connected to
The side opening 63 is airtightly connected to the exhaust pipe 7. In the side wall of the container 61, the refrigerant flow path 6
The coolant channel 64 is connected to a coolant supply source (not shown), and is configured to supply, for example, cooling water, and the container 61 is cooled by the cooling water. The lower portion of the container 61 is configured as a liquid reservoir 65 for storing unreacted TEOS mist cooled by the cooled container 61, and the opening 63 on the side surface is provided with a liquid reservoir 6.
It is formed at a position higher than 5. A valve V2 is provided on the bottom surface of the container 61 (the bottom surface of the liquid reservoir 65) to discharge a liquid formed by collecting mist from a pipe 66.

The exhaust pipe 7 extends upward from a connection portion with a second trap 6 described later, and is bent at a position higher than the connection portion so as to be connected to the vacuum pump 8 on the lower side. ing. The flow path from the exhaust pipe 5 to the vacuum pump 8 constitutes an exhaust path.

Next, the operation of the above-described apparatus will be described by taking a case of forming a silicon oxide film as an example. For example, a wafer boat 34 on which 100 wafers W
It is carried into the inner pipe 31 from the opening provided below the manifold 4 by the boat elevator 33, and this opening is hermetically sealed by the lid 35. Next, the inside of the reaction tube 3 is heated to about 600 ° C. to 650 ° C. by the heater 37. Under this heating atmosphere, a vapor of tetraethoxysilane (TEOS) supplied from a gas supply source (not shown) is supplied from the gas introduction pipe 43 at a flow rate of, for example, several tens sccm to 200 sccm, and the pressure is set to, for example, 2 Ton.
rr, the TEOS is decomposed in this process atmosphere and silicon oxide (SiO 2)
2) A film is formed. The gas exhausted from the reaction tube 3 at the time of the heat treatment contains a reaction product generated from the tetraethoxysilane gas by the film forming process, and includes, for example, silicon oxide as a main reaction product and hydrocarbon (CxHy) as a by-product. ) And water.

At this time, each disk 51b provided in the first trap 51 is heated to, for example, about 100 ° C. to 150 ° C., and the exhaust conductance inside the trap 51 is reduced, so that the exhaust is performed. The reaction product collides with and adheres to the disk 51b and is collected.

On the other hand, the unreacted portion of TEOS is partially removed in the first trap 51, but is passed therethrough and sent to the second trap. For example, cooling water is supplied to the coolant passage 64 in the second trap 6, and the temperature in the container 61 is reduced to a temperature at which the TEOS contained in the gas can be liquefied and collected as a mist by the cooling water, for example. 20 ° C
Adjusted to the extent. The gas flowing into the container 61 from the opening (inflow port) 62 on the upper surface to the lower side is changed in direction toward the opening (exhaust port) 63 on the side surface. At this time, since the inside of the container 61 is cooled, the unreacted TEOS contained in the gas is liquefied to become a mist, and the mist is moved straight by inertia force and stored directly in the lower liquid reservoir 65 or the container 61 is cooled. The liquid adheres to the inner wall, descends by its own weight, and is stored in the liquid reservoir 65. The unreacted TEOS recovered in the liquid reservoir 65 opens the valve V2, and the piping 66
Is discharged from The TEOS recovered from the pipe 66 may be reused as a processing gas source after performing a process of removing impurities. On the other hand, the gas from which the unreacted TEOS has been recovered is exhausted from the vacuum pump 8 through the exhaust pipe 7 through the side opening 63.

According to such an embodiment, the exhaust pipe 5
In addition, since the first trap 51 and the second trap 6 (cooling trap) for collecting unreacted TEOS are provided, both the reaction product of the processing gas (TEOS) and the unreacted TEOS are removed. It can be collected upstream of the vacuum pump 8, so that the frequency of maintenance of the vacuum pump 8 can be reduced. In particular, when film formation is performed under conditions of a process pressure of, for example, 1 Torr to 10 Torr and a process temperature of 600 ° C. to 650 ° C., which is higher and lower than before, in order to cope with pattern miniaturization, a lot of unreacted TEOS is exhausted. Therefore, it is effective to apply this method.

The opening 63 on the side of the second trap 6
Is set higher than the liquid reservoir 65, it is possible to suppress the collected liquid from flowing out to the vacuum pump 8 side. Note that higher than the liquid storage section 65 means higher than the liquid level of the liquid stored here.

In this embodiment, since the exhaust pipe 7 provided between the second trap 6 and the vacuum pump 8 extends upward from the connection portion with the second trap 6, TEOS mist passes through trap 6 and exhaust pipe 7
Even when TEOS enters the inside or when TEOS is liquefied in the middle of the gradient of the exhaust pipe 7, it flows down the inner wall gradient to the second trap 6 side and is prevented from reaching the vacuum pump 8.

Here, in the second trap 6, it is necessary that the inlet and the outlet do not face each other.
The configuration of the second trap 6 is not limited to the above example, and may be, for example, a configuration as shown in FIGS. 3 (a) and 3 (b). The embodiment shown in FIGS. 3A and 3B is the same as the embodiment shown in FIG.
As the main body, a cylindrical container 61 provided with a liquid reservoir 65 on the lower side is used. In FIG. 3A, the gas flowing through the opening 91 on the side surface is configured to be exhausted from the opening 92 on the upper surface, and in FIG. And two openings 9 serving as exhaust ports
3, 94 are provided.

Also in these embodiments, since the direction of the gas flowing into the second trap 6 can be changed, the unreacted TEOS can be reliably recovered in the second trap 6.

In the heat treatment apparatus according to the present embodiment, the processing gas used for forming the film of the wafer W is not limited to tetraethoxysilane (TEOS), but may be, for example, monomethoxytrichlorosilane or monophenyltriethoxysilane. Other alkoxysilanes may be used as the processing gas.

[0028]

As described above, according to the present invention, the amount of unreacted alkoxysilane gas reaching the vacuum pump can be suppressed, so that the frequency of maintenance of the heat treatment apparatus can be reduced and the operation efficiency of the semiconductor device can be increased. Can be.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view illustrating a second trap according to one embodiment.

FIG. 3 is an explanatory diagram showing a periphery of a second trap according to another embodiment.

FIG. 4 is a schematic view showing a conventional vertical heat treatment apparatus.

[Explanation of symbols]

 W Wafer 3 Reaction tube 31 Inner tube 32 Outer tube 34 Wafer boat 4 Manifold 5 Exhaust tube 51 First trap 6 Second trap 61 Container 62, 63 Opening 64 Refrigerant flow path 65 Liquid reservoir 66 Pipe 7 Exhaust pipe 8 Vacuum pump

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F045 AA06 AB32 AC09 AD10 AE21 AE23 BB08 DP19 EC02 EC07 EG03 EG08

Claims (3)

[Claims] An alkoxysilane gas is introduced as a processing gas into a processing vessel into which a processing object has been loaded, and the processing chamber is evacuated through an exhaust path and heated to a heating atmosphere to perform a heat treatment on the processing object. In the heat treatment apparatus to be performed, a vacuum pump connected to the exhaust path, a first trap provided in the middle of the exhaust path and collecting a reaction product of the processing gas by reducing exhaust conductance, and the exhaust path And a second trap provided between the first trap and the vacuum pump for cooling unreacted processing gas and collecting it as a mist. The second trap has an inflow port and an exhaust port. A trap body configured not to face each other, cooling means for cooling an inner wall surface of the trap body, Thermal processing apparatus characterized by being formed in a square side and a, a liquid reservoir for reserving the mist. 2. The exhaust path on the exhaust port side of the second trap,
The heat treatment apparatus according to claim 1, further comprising a portion extending upward from the exhaust port. 3. The process pressure in the processing vessel is 1 Torr.
The heat treatment apparatus according to claim 1, wherein the pressure is 10 to 10 Torr.