JPH0261067A - Heat-treating device - Google Patents

Abstract

PURPOSE:To prevent the clogging of an exhaust gas pipe by collecting a reaction product remaining in the exhaust gas with plural cold traps at the time of forming the film of the reaction product of the gaseous reactant as the raw gas on a body to be treated in a reduced-pressure CVD device, etc. CONSTITUTION:Many materials 3 to be treated such as a semiconductor wafer are placed at regular intervals in the treating part 2, which is a gauge reaction tube consisting of an outer pipe 1 and an inner pipe 1a, and raised into the inner pipe 1a by a conveying mechanism 5. The inside of the treating part 2 is evacuated from the exhaust pipe 14, a gaseous reactant such as SiH4 is supplied from a gas inlet 11, and an Si film formed by the decomposition of SiH4 is formed on the surface of the semiconductor wafer 3 heated by a heater 18. Since Si as the reaction product remains in the exhaust gas, the exhaust gas is passed through plural cold traps connected to the exhaust pipe 14 and cooled to completely collect and remove the contained Si. Consequently, the clogging of the exhaust gas pipe with Si is prevented, the progress of the reduced-pressure CVD reaction is not disturbed, and the film forming reaction is stably carried out for a long period.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a heat treatment apparatus.

(Prior art) A heat treatment device, such as a low-pressure CVD device, involves inserting a boat carrying a plurality of wafers in an array into a quartz reaction tube surrounded by a resistance heater, etc. from the front end of the reaction tube. After setting the wafer at a predetermined position, the end of the weight is hermetically sealed with a lid, the exhaust is evacuated to a predetermined pressure, and the wafer is heated to a predetermined temperature by the heat generated by the heater. A reaction gas is introduced into the reaction tube and a heat treatment reaction is performed to grow a thin film on the surface of the wafer. and,
After the heat treatment reaction, unreacted gases, reaction products, etc. are discharged to the outside as exhaust gas through the exhaust passage. However, the reaction products contained in this exhaust gas may have a negative effect on the exhaust pipe walls that make up the exhaust path and the mechanical booster pump for vacuum evacuation, or may mix into the rotary pump oil of the rotary pump, causing the oil to become oily. This will cause the exhaust performance to deteriorate. As a countermeasure, a cold trap is installed in the exhaust path from the reaction tube to the vacuum pump to cool the exhaust gas and capture the reaction products. This reduced the contamination of reaction products and other adverse effects on the mechanical booster pump. Such technology is disclosed in Japanese Patent Application Laid-open No. 62-65414 and Japanese Patent Laid-open No. 6
It is disclosed in Japanese Patent No. 2-161971.

(Problem to be solved by the invention) However, with the diversification of processes, the larger diameter of semiconductor wafers, and the large-scale processing of 100 or more wafers, the flow rate of gas flowing at one time has also increased, and cold traps can be trapped in - processes. The amount of reaction products adhering to the surface will also increase. Furthermore, in order to flow a large amount of gas, it is also required to increase the exhaust conductance of the exhaust path. For this reason, the technology disclosed in the above publication is characterized by the use of a bypass exhaust path with significantly reduced exhaust conductance during film formation, and this low exhaust conductance makes it possible to use various filters that can be used. There is. For this reason, it is very difficult to increase the exhaust conductance during film formation and flow a large amount of processing gas.Furthermore, depending on the process, the reaction products are flocculent and extremely hard, making it difficult to process the double-sided rotor of a mechanical booster pump. There was also the problem that the rotor could get stuck in the gap and cause a locking phenomenon in which the rotor could no longer rotate.

As a countermeasure to this problem, if a mesh-type cold trap made of a mesh filter or the like is used as a cold trap, the exhaust conductance decreases and a large-capacity vacuum pump must be installed, leading to an increase in space and cost. Additionally, depending on the process, the mesh filter could become clogged during a single process, and the filter in the cold trap had to be replaced more frequently, leading to a decrease in work efficiency.

The present invention has been made to improve the above-mentioned problems, and aims to provide a heat treatment apparatus having an exhaust passage that can efficiently capture reaction products and the like while maintaining a high exhaust conductance of the exhaust passage.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides an apparatus for heat-treating an object to be processed while supplying a processing gas into a processing chamber and exhausting the gas in the processing chamber through an exhaust path. The present invention provides a heat treatment apparatus characterized in that a plurality of coal F') wraps are provided to capture processing products and the like.

(Operation and Effect) According to the present invention, in an apparatus for heat-treating an object to be processed while supplying a processing gas into a processing chamber and exhausting the gas in the processing chamber from an exhaust path, the exhaust path is provided with a process gas after the heat treatment. By providing a plurality of cold traps for capturing products and the like, it is possible to configure an exhaust path that can efficiently capture reaction products while keeping the exhaust conductance of the exhaust path high.

(Example) An example in which the heat treatment apparatus of the present invention is applied to a vertical CVD apparatus will be described below with reference to the drawings.

For example, as shown in FIG. 2, this device includes a processing vessel (1) with its axis vertical, such as a cylindrical reaction tube (1) made of quartz.
A processing section (2) consisting of a processing section (2), and a plurality of objects to be processed, such as semiconductor wafers (3), carried in and out of this processing section (2), for example, about 25 to 50 pieces in the above-mentioned vertical direction, at a predetermined interval, for example, about 3 mm. For example, a heat-resistant quartz boat (4), which can be placed on a support provided with a gearing of
4); and a conveyance mechanism (5) for funnel unloading into the reaction tube (1) from below the reaction tube (1).

The reaction tube (1) of the processing section (2) is made of, for example, quartz glass, which is heat resistant and hardly reacts with the processing gas. This reaction tube (1) has a double tube structure, and the cylindrical inner tube (1a), which is made of, for example, quartz glass and whose upper part is sealed in an arc shape, is connected to the reaction tube (1).
) in a non-contact manner. The above reaction tube (])
Inner and above reactions'! A gap (7) of a predetermined distance, for example, 15 mm, is provided between the outer surface of (la) and the outer surface of (la).
This gap (7) is removably sealed at its lower end by a tubular manifold (8) made of stainless steel, for example.

This manifold (8) has an upper manifold (8a) which holds the outer reaction tube (1) and an inner inner 'tf!
(1a), and a lower manifold I'' (8b) for easy attachment and removal of the inner tube (1a) during maintenance and assembly, and each joint is sealed with a sealing material such as The manifold (8b) is kept airtight by an O-ring (10).Furthermore, a plate-shaped lid body (9) made of stainless steel, for example, is attached to the lower end of the manifold (8b) and can be brought into contact with it by the lifting and lowering of the transport mechanism (5). A sealing member such as an O-ring (10) is provided at the contact portion of the lid (9) with the manifold (8b),
The interior of the inner tube (la) and the reaction tube (1) can be kept airtight. Further, an inlet pipe (11) for reactant gas and carrier gas is provided that extends through the manifold (8b) and into the inner pipe (1a). This gas introduction pipe (11) extends vertically along the inner surface of the inner pipe (1a), and its tip is disposed at approximately the same height as the top surface of the boat (4). And this reaction gas introduction pipe (11)
is provided with a gas blowout hole (12) having an opening of 1 g or i rIl at a position corresponding to each wafer placed on the boat (4).
) A plurality of gas exhaust pores (13) are formed over approximately half a circumference to 415 circumferences of the side wall of the inner tube (1a) of the (fffi), which faces the wafer (
3) allows a uniform reaction gas to flow in parallel to the reactor. The manifold (8b) has an exhaust pipe (14).
) is connected, so that the gas that has completed the surface treatment of the wafer (3) can be exhausted through the gap (7). A support (15) is provided approximately in the center of the lid (9) to which a rotation function can be added to allow rotation of the boat to improve uniformity of temperature and gas. The support body (15) is configured such that a heat-retaining receiver made of, for example, ceramic, provided on the lower surface of the heat-insulating cylinder (16) is connected to the stand (17) and supports the heat-insulating cylinder (16) and the boat (4). ing. The heat retaining tube (16) is a cylindrical body made of quartz glass, for example, and is arranged to prevent the heat inside the reaction tube (1) from escaping downward. This thermal cylinder (16)
The boat (4) is placed on top, and is structured to move simultaneously with the lifting and lowering movement of the lid (9) by the transport mechanism (5). Further, a cylindrical heating device, for example, a heater (1) wound in a coil shape, is provided so as to coaxially surround the reaction tube (1), and this heater (18) is used for placing the wafer (3). For example, the desired temperature within the range of 60
It is provided so as to uniformly heat the temperature to about 0 to 1200°C. Then, from the exhaust pipe (14), as shown in FIG. The length of the exhaust pipe (14) is made as short as possible. That is, the first cold trap (20) is connected as close as possible to the processing section (2). ) Two exhaust paths are provided from the wrap (20). That is, one 1'11'
The air passage is mainly responsible for vacuum displacement within the processing chamber (2).

This vacuum displacement exhaust path is, for example, an i2-inch pipe, and a main valve (21) that controls this exhaust path,
A sub valve (22) is connected in parallel to this main valve (21).
are connected by, for example, 378-inch piping. A rotary pump (23) for evacuation is connected to the other end of the main valve (21). The other exhaust path is mainly responsible for evacuation for film formation. This film-forming exhaust path is, for example, a 4-inch pipe, and a main valve (24) for controlling this film-forming exhaust path is connected to the cold trap (20). Then, from the main valve (24), a second cold trap, for example, a water-cooled trap (2
5> is connected. This second cold trap (
25) is connected to an automatic pressure control device (APC), such as a butterfly valve (26), which controls the exhaust pressure in the processing section (2) during film formation. And this APC (2
A vacuum pump consisting of a mechanical booster pump (27) serving as a pre-stage pump of the vacuum evacuation system and a rotary pump (28) performing main evacuation is connected in sequence from 6). On the other hand, the processing section (2) and the first cold trap (
20), for example, a Pirani gauge (29) is provided to measure the pressure near the exhaust gas inlet of the first cold trap (20). Then, the main valve (24) of the exhaust path during film formation and the second cold trap (25)
For example, a capacitance manometer (30) for measuring and controlling the exhaust pressure during film formation is provided between the APC (
26) to control the exhaust pressure during film formation. Further, a Villany gauge (31), for example, is provided between the upper APC (2B) and the mechanical booster pump (27) to measure the exhaust pressure therebetween.

As the diameter of wafers increases and large-scale processing takes place, the processing section (2) that performs the film has to be A vacuum pump (27) that performs evacuation, (
28) and (23) are physically placed in front of each other to some extent. Therefore, the first cold trap (20) is installed near the processing section (2) to capture the reaction products, etc. in the exhaust gas from the processing section (2), and to transfer the reaction products, etc. to the processing section (2). This prevents the particles from returning and becoming a source of particles in the processing chamber (2). Similarly, the second cold trap (25) is piped as close as possible to the mechanical booster pump (27) at the front stage of the vacuum pump via the APC (26).
) and the rotary pump (28), the pump is protected by immediately preventing reaction products from entering the rotary pump (28). In addition, the gas flow in the processing chamber (2) during film formation is made close to a uniform N flow with respect to the wafer (3), so that a large amount of processing gas can flow, that is, the exhaust conductance during film formation is In order to increase the exhaust conductance of the cold trap (20) and cold trap (25), instead of using a conventional mesh filter structure, a large number of partitioned rooms are used to allow the exhaust gas to come into contact with many surfaces. has a structure through which exhaust gas passes, a cold trap (20),
(25) Individual exhaust conductance is increased.

In other words, instead of capturing reaction products etc. in a concentrated manner in one cold trap as in the past, they are dispersed and captured in multiple cold traps, the exhaust conductance of each cold trap is increased, and the exhaust system It is constructed to maintain a high overall exhaust conductance. In this way, a vertical CVD apparatus is constructed.

Next, the operation of the above-mentioned vertical CVD apparatus will be explained.

First, the processing boat (4), in which the wafers (3) aligned by a wafer transfer device (not shown) are automatically loaded using robot technology, is automatically transferred by robot 1+12 onto the female hot cylinder (16). Place it. Then, the heat insulating cylinder (16) on which the boat (4) is placed is transferred to the transport mechanism (5).
), and transported to a predetermined position in the reaction tube (1) without contacting the inner wall of the inner tube (Ia). At this time, the wafer (3) is automatically positioned by bringing the manifold 1'' (8b) at the lower end of the reaction tube (1) into airtight contact with the lid (9).Next, the film forming system With the main valve (24) in the exhaust path closed, start the rotary pump (23) in the vacuum displacement exhaust path.To avoid rapid depressurization in the processing chamber (2) and particle contamination, Open the sub-valve 22) and then the main valve (21) to evacuate the processing chamber (2) in stages and perform vacuum displacement or purging with inert gas.Next, open the 17F air path for film formation. Start the rotary pump (28), which is the main pump of
After evacuation to ~30 Torr, start the mechanical booster pump (27). Then, the pressure being exhausted in the vacuum displacement exhaust path is measured with the Villany gauge (29) near the cold trap (20), and the pressure with the Villany gauge (31) between the mechanical booster pump (27) and APC (2B) is measured. When they are equal, close the valves (21) and (22) of the vacuum displacement exhaust path, and at the same time open the main valve (24) that controls the film deposition exhaust path. That is, the vacuum displacement exhaust path is closed, and the film formation exhaust path is activated. Then, the pressure in the film-forming exhaust passage is measured with a capacitance manometer (30) so that the inside of the reaction tube (1) is at a desired reduced pressure state, for example, 1 to 5 Torr.The result is fed back to the APC (26), and the pressure is Exhaust is controlled to a reduced pressure state. Then, the heater 18) is used to set a desired temperature, for example, about 600'C to 1200C.

After this setting, a reaction gas such as 5iHa (silane) or 5iH2C12 (dichlorosilane) is introduced into the reaction tube while controlling the exhaust gas and adjusting the flow rate to an appropriate flow rate range using a mass flow controller (not shown) from the gas supply source.
1) A flow rate of, for example, 500 from the reaction gas introduction pipe (11)
9CCM will be introduced. Then, the reaction gas introduced from the gas outlet (12) of the gas introduction pipe (11) creates a substantially uniform flow of reaction gas parallel to the surface of the wafer (3), while increasing the gas discharge value of the inner pipe (1a). The gas flows toward the hole (13), passes through the gas exhaust hole (13), flows through the exhaust path in the gap (7), and is exhausted from the gas exhaust pipe (14). During this time, on the surface of the wafer (3), for example, Si is formed due to the decomposition of the reaction gas.
A film is formed. All of these operation blocks are stored in the computer in advance and are automatically executed.

On the other hand, high-temperature exhaust gas exhausted from the exhaust pipe (14) is introduced into the first water-cooled trap (20) and rapidly cooled.
Reaction products and the like are captured in a water-cooled trap (20). The exhaust gas, whose temperature has decreased after passing through the first water-cooled trap (20), passes through a slightly longer pipe and enters the second water-cooled trap (20) connected near the mechanical booster pump (27).
5). Here the second water-cooled trap (25)
The exhaust gas is further cooled by the first water-cooled trap (
Capture the reaction products etc. that could not be captured in step 20).

In addition, the lower the temperature, the easier it is to capture reaction products, so since the temperature of the exhaust gas is lowered in the first water-cooled trap (20), the second water-cooled trap (25) can capture reaction products more effectively. etc. are captured. In this way C
After the VD treatment, the supply of the reaction gas is stopped, and after the reaction gas is replaced by exhaust, an inert gas such as N2 gas is introduced from the gas introduction pipe (11) to bring the inside of the reaction tube (1) to atmospheric pressure. I can return. Then, the lid (9) is opened and the boat (4) loaded with the wafers (3) after the above-mentioned processing is opened.
is taken out by the transport mechanism (6), and the process ends.

In the above embodiment, one cold trap was provided near the reaction tube (1) and one near the mechanical booster pump (27), and a total of two coal wraps (F') were provided in the exhaust path. Needless to say, various modifications can be made without departing from the spirit of the invention.

For example, as shown in Fig. 3, a plurality of cold traps may be installed in series in the exhaust passage (A), or a plurality of cold traps may be connected in parallel (B), or (C). It is also possible to use a valve in combination with a valve to selectively switch the cold trap, so that the cold trap can be easily replaced and cleaned without stopping the equipment.The above embodiments may also be combined. Needless to say, you can use it. Furthermore, in the above embodiment, vertical CVD
Although the description has been made regarding the apparatus, it is particularly effective for apparatuses that involve film formation, such as silicon epitaxial apparatuses, plasma CVD apparatuses, and photo-CVD apparatuses.

(Effects of the Invention) As described above, according to the present invention, reaction products can be efficiently captured while keeping the tJl:i conductance of the exhaust path high.

[Brief explanation of the drawing]

FIG. 1 is a vertical type C for explaining one embodiment of the device of the present invention.
A configuration diagram of the VD device, Figure 2 is a configuration diagram of the processing section in Figure 1,
FIG. 3 is an explanatory diagram of another embodiment of the cold trap shown in FIG. 1. 101 reaction tube 1a9. Inner tube 21. processing section
36. Wafer 200. First water-cooled trap 251. Second water-cooled trap 26, APC 270, mechanical booster pump 289. rotary pump

Claims (1)

[Claims] In an apparatus that heat-treats an object to be processed while supplying a processing gas into a processing chamber and exhausting the gas in the processing chamber through an exhaust path, a plurality of cold traps are provided in the exhaust path to capture processing products, etc. after the heat treatment. A heat treatment device characterized in that it is equipped with two heat treatment devices.