JPH01316461A - Reduced-pressure cvd device - Google Patents

Abstract

PURPOSE:To easily carry out the maintenance of the title device and reduce the amount of the particles in it by arranging an inner-wall protective pipe which has an inclined step part abutting the inclined step part reaching the small diameter part from the large diameter part and stretches to the upstream and downstream of the connection part of the small diameter part and an exhaust pipe, to the inside of the reaction pipe. CONSTITUTION:Wafers 32 are arranged in a reaction pipe 21 connected with a vacuum pump 23 and a gaseous raw material is introduced through a gas discharge port 30 and regulated at the prescribed temp. with a heater 19 and the deposited films are formed on the wafers 32. In the above reduced-pressure CVD device, an inner-wall protective pipe 27 is freely detachably arranged in the reaction pipe 21. The inclined step part 27c reaching the small diameter part 27b from the large diameter part 27a of the protective pipe 27 has the same inclination as the inclined step part 21c of the reaction pipe 21 and gas flow is not caused between the protective pipe and the reaction pipe by allowing both pipes to abut with each other. Furthermore the small diameter part 27b is lengthened until the upstream and downstream sides of the connection part 24 of both the small diameter part 21b of the reaction pipe 21 and an exhaust pipe 22. By the above-mentioned constitution, this protective pipe 27 can be easily exchanged by opening a gate valve 29. Further the particles of the connection part 24, etc., can be drastically reduced.

Description

[Detailed Description of the Invention] [Summary] Regarding a low-pressure CVD device that deposits a thin film on a wafer surface under reduced pressure, the purpose of this invention is to maintain ease of maintenance and reduce particles. It has a reaction tube with an end of the small diameter portion connected to an exhaust pipe, and an internal protection tube removably disposed inside the reaction tube, so that the gas can be In a reduced pressure CVD device in which flow flows from a large diameter portion to the exhaust pipe, the inner wall protection tube has a large diameter portion, a small diameter portion of a predetermined length, and an inclined step having an inclination corresponding to the inclination of the inclined step portion of the reaction tube. The inner wall protection tube has a shape in which the inclined stepped portion thereof is in contact with the inclined stepped portion of the reaction tube, and the small diameter portion of the inner wall protection tube is in a state where the gas is removed from the connecting portion between the reaction tube and the exhaust pipe. It is configured to extend in the flow direction up to the downstream side.

[Industrial application field]

The present invention relates to a low pressure CVD apparatus for depositing a 31 film on a wafer surface under reduced pressure.

2. Description of the Related Art Recently, as the miniaturization of semiconductor devices has progressed, reducing particles in each manufacturing process of semiconductor devices has become an important issue. The same is true for low-pressure CVD equipment, and maintenance such as replacing and cleaning the reaction tubes is carried out every time several growths are performed.

Replacing the reaction tube breaks the vacuum system, so a leak check is required again after replacement, and maintenance takes several hours.As a result, the operating rate of the low-pressure CVD equipment decreases, and throughput decreases. Resulting in.

Therefore, a reduced pressure CV with a structure that does not require time for maintenance.
The realization of D device is desired.

[Prior art] Figure 3 shows the reduced pressure C shown in Utility Model Publication No. 63-2435.
This is the VD device i1.

2 is a reaction tube, 3 is an exhaust pipe, 4 is a vacuum pump, 5 is a gas introduction pipe, and 6 is a wafer.

Reference numeral 7 denotes an inner wall protection tube, which is detachably arranged inside the reaction tube 2.

Maintenance can be performed by opening the gate valve 8 and replacing the inner wall protection tube 7 without replacing the reaction tube 2. Therefore, there is no need to perform a leak check when replacing the inner wall protection tube 7, and maintenance can be performed in a short time of about 5 minutes.

(Problems to be Solved by the Invention) The connecting portion 9 between the reaction!! 2 and the exhaust pipe 3 is generally water-cooled to protect the sealing member, and a film is likely to accumulate on this connecting portion 9.

The internal protection tube 7 extends to a connecting portion 9 between the reaction tube 2 and the exhaust pipe 3, and the inner peripheral portion of the connecting portion 9 is exposed to the gas flow.

For this reason, a film is formed at the connection portion 9 as shown by reference numeral 10.

In the low pressure CVD apparatus 1, each time the wafer 6 is put in and taken out,
The inside of the reaction tube 2 is returned to atmospheric pressure. At this point, lll5
The particles peel off and become particles, which enter the reaction chamber 11 and adhere to the wafer 6.

Therefore, although maintenance is easy, it is substantially difficult to reduce particles.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-pressure CVD system that can maintain ease of maintenance and reduce particle generation.

[Means to solve the problem]

The present invention provides a reaction tube consisting of a large diameter section, a small diameter section, and an inclined stepped section between them, and an end of the small diameter section connected to an exhaust pipe, and an internal protection removably disposed inside the reaction tube. a reduced pressure CVD pipe, wherein the gas flows from the large diameter portion to the exhaust pipe.
In the apparatus, the inner wall protection tube has a shape having a large diameter portion, a small diameter portion of a predetermined length, and an inclined step portion having an inclination corresponding to the slope of the inclined step portion of the reaction tube, However, the inclined stepped portion is in contact with the inclined stepped portion of the reaction tube, and the small diameter portion extends up to the downstream side in the flow direction of the gas from the connection portion between the reaction tube and the exhaust pipe. The configuration is such that the

[Effect]

Since the inclined step part of the inner wall protection tube is in contact with the inclined step part of the reaction tube, the gap between the inner wall protection tube and the reaction tube does not serve as a gas passage.

The small diameter part of the inner wall protection tube extends upstream and downstream from the connection between the reaction tube and the exhaust pipe in the gas flow direction, so the small diameter part covers the connection and prevents gas that has passed through the reaction chamber from reaching the connection. Touching is prevented.

As a result, no matter how many times the batch process is repeated, no film is formed inside the reaction tube, including the connection part, so that the initial state can be maintained and particles in the process chamber can be reduced.

(Example) Figure 1 shows a horizontal reduced pressure CVD l1 which is an example of the present invention.
! 20 is shown. In Fig. 2, the reference numeral 21 indicates a reaction tube, which is composed of a large diameter part 21a, a small diameter part 21b, and a conical inclined stepped part 2IC between them, and is set horizontally inside the heater 19. It is. 22 is an exhaust pipe, and the small diameter part 21
It is connected to the end of b. 23 is a vacuum pump.

24 is a connection part between the reaction tube 21 and the exhaust pipe 22. The connecting portion 24 is cooled by cooling water flowing in a water channel 25, and an O-ring 26, which is a sealing member, is protected.

27 is an inner wall protection tube, which has a large diameter part 27a and a small diameter part 27.
b, and a conical inclined step portion 27c therebetween.

The diameter of the large diameter portion 27a is slightly smaller than the large diameter portion 21a, and the length is approximately the same as that of the large diameter portion 21a.

The diameter of the small diameter portion 27b is slightly smaller than the small diameter portion 21b, and the length 2 is longer than the length 2 of the small diameter portion 21b.

The inclination angle of the inclined step portion 27c is equal to the inclination angle of the inclined step portion 2IC, which is α.

Reference numeral 28 denotes a drawer hook, which is provided near the end of the large diameter portion 27a.

The inner wall protection tube 27 is inserted into the reaction tube 21 as shown by the arrow X+ in FIG.
1 as shown in FIG.

That is, the inclined stepped portion 27G is in close contact with the inclined stepped portion 21C. 40 is a close contact portion.

The small diameter portion 27b enters the small diameter portion 2Ib and
In the direction of gas flow indicated by , it extends beyond the connecting portion 24 to the exhaust pipe 22 and covers the connecting portion 24 .

The large diameter portion 27a is fitted into the large diameter portion 2ia, and its end 27a-+ is the end 21a- of the large diameter portion 21a.
It almost coincides with +.

29 is a gate valve, and the large diameter portion 21a of the reaction tube 21
tiwU the opening of.

Reference numeral 30 denotes a group of gas discharge ports, which is provided at the center of the gate valve 29 and faces the inside of the large diameter portion 27a of the inner wall protection tube 27.

31 is a gas introduction pipe.

Next, the operation of the reduced pressure CVD apparatus 20 having the above configuration is performed at 5isN.
An example in which four films are grown will be explained.

Open the gate valve 29 and transfer the wafer 32 to the inner wall protection tube 27.
is placed inside the large diameter portion 27a of the reaction chamber 33, the gate valve 29 is closed, the vacuum pump 27 is operated to reduce the pressure inside the reaction chamber 33, and the inside of the reaction chamber 33 is heated to 825° C. by the heater 19. do.

In this state, 5iHa and NH3 are introduced from the gas introduction pipe 31 as source gases. The gas flows out from the gas outlet group 30 as shown by the arrow 34, flows inside the reaction v33 along the surface of the wafer 32, and forms Si3N4 on the surface of the wafer 32.
A film is formed.

This film is also formed on the inner wall of the inner wall protection tube 27.

The film is deposited on this part in layers each time the film grows.
After repeating the growth about four times, the film peels off from the inner wall protection tube 27 and becomes particles.

Therefore, the inner wall protection tube 27 is replaced with a new one before the film becomes thick enough to peel off, that is, every few times of growth.

As a result, film growth on the wafer surface is prevented by the inner wall protection tube 27.
The process is carried out in a clean atmosphere where no peeling of the film occurs.

Here, the inner wall protection tube 27 is replaced after opening the gate valve 29 and taking out the wafer 32.
This is completed by pulling out the inner wall protection tube in the direction of arrow x2 and inserting a new inner wall protection tube at once in its place.

During this replacement work, leave the connection part 24 as it is,
Since it is not separated, the vacuum system will not be compromised.

Therefore, there is no need to perform a leak check after replacing the inner wall protection tube, and it takes only about 5 minutes to restore the inner wall of the reaction chamber 33 to a clean state. Therefore, downtime of the low pressure CVD apparatus i20 can be reduced.

In addition, by using the hook 28, the inner wall protection tube 2
The replacement work No. 7 can be carried out safely and efficiently.

Here, gas flow and film formation in the state shown in FIG. 1 will be explained.

(2) It works because the inclined stepped portion 27c is pressed against the inclined stepped portion 21c.

Gas flows out from the gas discharge port group 30 into the large diameter portion 27a, and is originally difficult to enter into the gap 35 between the large diameter portion 27a and the large diameter portion 2IC.

Moreover, the inclined step portions 27G and 21C are pressed against each other,
The gap 35 and the gap 36 between the small diameter portion 27b and the small diameter portion 21b are blocked by a close contact portion 40 in the middle, and the gaps 35 and 36 constitute a gas suction passage and are not present. Therefore, gas is not sucked into the gap 35.

Therefore, a film is hardly formed on the inner circumferential surface of the large diameter portion 21a of the reaction tube 21.

■ The effect of the small diameter portion 27b covering the connecting portion 24.

The inclined stepped portion 27c is pressed against the inclined stepped portion 21c, and the gap 36 does not serve as a gas suction passage.
Gas does not flow inside 6.

Further, the gas that has passed through the processing chamber 33 flows within the small diameter portion 27b without touching the connecting portion 24.

Therefore, even though the connecting portion 24 is a site where a film is likely to be formed, even if batches are repeated, the connecting portion 24 maintains its original state in which no film is formed.

Therefore, no matter how many times the film is grown, the inner wall of the reaction tube 21, including the connection portion 24, maintains the initial state in which no film is formed.

In the low-pressure CVD apparatus 1, each time the gate valve 29 is opened or closed, the reaction chamber 33 is returned to atmospheric pressure, and if there is a film inside the reaction tube 21, it may peel off at this time and become particles. However, since no film is attached inside the reaction tube 21, no particles are generated even when the reaction chamber 33 is returned to atmospheric pressure.

Furthermore, particles are likely to be generated during the process of replacing the inner wall protection tube 27. However, since there is no film, no particles are generated in this case either.

Therefore, in addition to simplifying maintenance, it is possible to reduce particles compared to the conventional type.

Here, the inner wall protection tube 27 is made of a material compatible with the gas used, such as quartz or Si, so that the adhered film is difficult to peel off.
Made of C, Si, or glazed carbon coated graphite. In particular, if it is made of quartz, the surface should be sandblasted.

Note that no special member is required to prevent the gaps 35 and 36 from becoming a gas suction path, and the inner wall protection tube 27 can be inserted deep into the reaction tube 21 to a position where it cannot be inserted any further. It's good and easy to configure.

Furthermore, since the gaps 35 and 36 do not become gas passages, the flow of gas inside the inner wall protection tube 27 is not disturbed, and the flow of gas around the wafer 32 is exactly the same as when the inner protection tube 27 is not used. Therefore, the film pressure distribution on the surface of the sea urchin eight is good.

Further, the present invention is not limited to the horizontal type in the above embodiment, but can also be applied to a vertical type reduced pressure CVD apparatus.

〔Effect of the invention〕

As explained above, according to the present invention, no film is formed on the inner wall of the reaction tube or at the connection between the reaction tube and the exhaust pipe, even if the growth process is repeated many times.

Therefore, even when the reaction chamber is returned to atmospheric pressure and the inner wall protection tube is replaced, no particles are generated, and particles can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a low pressure CVD apparatus according to an embodiment of the present invention, FIG. 2 is a diagram explaining maintenance of the low pressure CVD apparatus shown in FIG. 1, and FIG. 3 is a diagram showing a conventional low pressure CVD apparatus. be. In the figure, 20 is a reduced pressure CVD device, 21 is a reaction tube, 21a is a large diameter part, 21b is a small diameter part, 21G is an inclined step part, 22 is an exhaust pipe, 24 is a connection part, 27 is an inner wall protection pipe, and 27a is a large diameter part. 27b is a small diameter portion, 27G is an inclined step portion, 28 is a hook, 29 is a gate valve, 30 is a group of gas discharge ports, 31 is a gas introduction pipe 32 is a wafer, 33 is a reaction chamber, 34 is a gas flow The arrows 35 and 36 indicate a gap, and 40 indicates a close contact portion. Patent applicant Fujitsu Ltd.

Claims (1)

[Claims] A reaction system consisting of a large diameter part (21a), a small diameter part (21b), and an inclined step part (21c) between them, the end of the small diameter part (21b) being connected to an exhaust pipe (22). It has a tube (21) and an internal protection tube (27) which is removably disposed inside the reaction tube, and the gas flows from the large diameter portion (21a) to the exhaust tube (21).
22), the inner wall protection tube (27) is divided into a large diameter portion (27a), a small diameter portion (27b) having a predetermined length (l_1), and an inclined stepped portion (21c) of the reaction tube. The slope (α) corresponding to the slope (α) of
The inner wall protection tube (27) has a sloped step (27c), and the sloped step (27c) is the sloped step (21c) of the reaction tube (21).
and its small diameter portion (27b) extends up and downstream in the gas flow direction (34) from the connection portion (24) between the reaction tube (21) and the exhaust pipe (22). A reduced pressure CVD characterized by having a configuration in which the
Device.