JPH11233505A - Exhaust apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system capable of controlling the pressure in a reaction tube with a high precision when a semiconductor wafer is subjected to oxidization in the reaction tube using water vapor. SOLUTION: A condenser 5 is provided in an exhaust pipe 3 to condense moisture in the exhaust gas, and the condensed water is accumulated in a sealed container 41 via a drain pipe 4 branched from the exhaust pipe 3. The drain pipe 4 and the exhaust pipe 42 are provided inside the sealed container 41 from above and below, respectively. The upper opening of the exhaust pipe 42 is positioned above the lower opening of the drain pipe 4 so that when wafer in the sealed container 41 is drained through the exhaust pipe 42, there may be a liquid phase between both openings to inhibit communication between those openings. Accordingly, inside the reaction tube 22 is hardly affected by the back pressure of the drain pipe 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust device connected to a reaction vessel for performing a heat treatment on an object using steam.

[0002]

2. Description of the Related Art For example, a vertical heat treatment apparatus is known as an apparatus for forming a silicon oxide film as an insulating film of a semiconductor device. A vertical heat treatment apparatus oxidizes silicon by carrying a wafer boat holding a large number of semiconductor wafers in a shelf into a quartz reaction tube surrounded by a heating furnace and introducing an oxidizing gas. is there. As a method of the oxidation treatment, there are a wet oxidation treatment using steam and a dry oxidation treatment using oxygen or ozone without using steam. In the case of performing the wet oxidation treatment, water is accumulated in an exhaust passage. As shown in FIG. 10, for example, a reaction tube 1
A drain pipe 12 is connected to the lowest position of an exhaust path 11 for exhausting the inside of the tube 0, and water flowing through the drain pipe 12 is stored in a container 13. The other end of the drainage pipe 14 whose one end is connected to the factory drainage side, for example, is connected to the bottom of the container 13. The end of the exhaust passage 11 is connected to an exhaust duct installed in a factory via a trap 15 for dew condensation of moisture in the exhaust gas and a butterfly valve 16 for adjusting the pressure in the reaction tube 10. The gas exhausted from the inside of the reaction tube 10 passes through the exhaust duct, and after being subjected to a predetermined process, is exhausted to the outside air.

[0003]

When the oxidation treatment is performed, the pressure in the reaction tube 10 is increased by the butterfly valve 14.
Is controlled so as to be maintained at a predetermined value, for example, −5 mmH ₂ O. However, as the pattern becomes thinner by miniaturization of the pattern, strict requirements are imposed on the film quality of the insulating film, and therefore the process pressure is also high. It is necessary to control with precision. However, in the above-described apparatus, since the water flowing from the drain tube 12 is stored in the open container 13, the processing gas in the reaction tube 10 leaks through the drain tube 12 into, for example, a factory. When the gas leaks as described above, there is a problem that it is not preferable in terms of environmental health.

On the other hand, when the vessel 13 is sealed, the drain pipe 12 and the drain pipe 14 communicate with each other via the space in the vessel 13, so that the inside of the reaction pipe 10 is back pressure of the drain pipe 12, that is, one end of the drain pipe 10. Affected by side pressure. When the valve V provided on the drain pipe 14 is closed, the reaction pipe 1
The pressure in 0 is affected by the pressure in the container 13 according to the amount of water in the container 13.

Further, in the above-described apparatus, since the moisture in the exhaust gas is condensed in the trap 15, the pressure fluctuates greatly at this point, and the pressure is detected by a pressure gauge (not shown) provided in the exhaust path 11 in terms of time. The butterfly valve 16 fluctuates in small increments because the value frequently appears to wave. For this reason, there is a problem that it is difficult to maintain the pressure in the reaction tube 10 at a predetermined value with high accuracy.

[0006] The present invention has been made under such circumstances, and an object of the present invention is to control the pressure in a reaction vessel with high accuracy when performing heat treatment, for example, oxidation treatment on an object using steam. An object of the present invention is to provide an exhaust device that can be controlled and can obtain a high-quality oxide film, for example.

[0007]

According to a first aspect of the present invention, there is provided an exhaust device connected to a reaction vessel for performing heat treatment on an object to be processed by using steam, wherein an exhaust path member connected to the reaction vessel is provided. A dew-condensing unit provided in the exhaust path member, for dew condensation of moisture in the exhaust gas, a pressure adjusting unit provided downstream of the dew-condensing unit in the exhaust path member, and an exhaust port of the reaction vessel. A first branch branched from the exhaust path member at a position lower than these with the dew condensation means.
, A closed container in which the lower end of the first drainage member is opened so as to collect water flowing through the first drainage member, and one end opened in the closed container. And a second drainage channel member, wherein one end of the second drainage channel member sucks water in the sealed container at a position above the lower end opening of the first drainage channel member. Opening to
The water level is located above the lower end opening of the first drainage channel member so that a liquid phase exists between the openings of the first drainage channel member and the second drainage channel member. It is characterized by having done. With this configuration, the influence of the back pressure of the first drainage channel member is eliminated when controlling the pressure in the reaction vessel. In this case, the water level in the closed container is the first
The liquid supply means for supplying the liquid into the closed container may be provided so as to be located above the opening of the drainage member (the invention of claim 2).

Further, the downstream side of the exhaust path member is connected to an exhaust duct provided in a factory, and the main branch path is provided from the downstream side of the pressure adjusting portion of the exhaust path member, and the level is higher than the branch point. A branch may be made so as to be connected to an airtight container via an airtight container, and a pressure monitoring unit that detects the pressure in the main branch and monitors the pressure in an exhaust duct installed in a factory, for example, may be provided. (Invention of claim 3). In this case, the auxiliary branch road is further branched from the main branch road,
It is preferable to provide a pressure monitoring unit in this auxiliary branch passage (the invention of claim 4).

According to a fifth aspect of the present invention, there is provided an exhaust device connected to a reaction vessel for performing a heat treatment on an object to be processed using steam, wherein an exhaust path member connected to the reaction vessel, and an exhaust path member connected to the reaction vessel. A dew-condensing unit for dew-condensing moisture in the exhaust gas, a pressure adjusting unit provided downstream of the dew-condensing unit in the exhaust-path member, and a dew-condensing unit between the exhaust port of the reaction vessel and the dew-condensing unit. A first drainage channel member branched from the exhaust channel member at a position lower than these,
A branch path provided from the downstream side of the dew condensation means in the exhaust path member, and a pressure fluctuation provided in the branch path for absorbing pressure fluctuation in the exhaust path member due to dew condensation of water in the dew condensation means. An opening portion formed in the branch passage so as to communicate with the outside, and the pressure fluctuation absorbing portion is suppressed so as to block the opening from the inside, and the pressure in the exhaust passage member is reduced. And a lid that is drawn inward against the restraining force to open the opening when is lowered.

With this configuration, the pressure fluctuation is reduced, and the operation of the pressure adjusting section is stabilized. In this case, when the pressure in the exhaust passage member becomes low, the lid of the pressure fluctuation absorbing portion is pulled inside against the suppressing force to open the opening and instead of opening the opening, the inside of the lid is kept closed. It may be formed of an elastic film so as to be attracted to the elastic film.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust system according to the present invention will be described below with reference to an embodiment applied to a vertical heat treatment apparatus. As shown in FIG.
In a reaction vessel surrounded by 1, for example, a reaction tube 22 made of quartz,
A large number of wafers W are held in a wafer boat 23 in a shelf shape and are carried in, for example, from below, and the lower end opening of the reaction tube 22 is closed with a cap 20 to perform a predetermined heat treatment. One of the heat treatments is an oxidation treatment for oxidizing a silicon film, and a mixed gas of water vapor (H ₂ O) and, for example, hydrogen chloride gas is used as a processing gas.

An exhaust system according to an embodiment of the present invention will be described with reference to FIG.
Exhaust pipe 3 forming an exhaust path member connected to the exhaust port 24
A drain pipe 4 serving as a first drainage channel member branched from the exhaust pipe 3; a cylindrical closed vessel 41 serving as a trap provided below the drain pipe 4; and a drain pipe in the exhaust pipe 3. 4 is provided with a cooler 5 serving as dew condensation means provided downstream of the branch point, and a butterfly valve 6 serving as a pressure adjusting unit provided downstream of the cooler 5 in the exhaust pipe 3.

FIG. 2 is a diagram schematically showing a state in which the exhaust device 100 is attached to the back of the vertical heat treatment device. In FIG. 2, reference numeral 25 denotes a substantially rectangular parallelepiped casing serving as an exterior body. A wafer cassette is taken in from a front face of the casing 25, and a furnace body 20 (a heat insulator, a heater 21, a reaction tube 22) ) Is carried in and heat-treated. In this example, the exhaust device 100 is configured as a unit having a vertical length of about 3 m, and the upper end 3a of the exhaust pipe 3 is connected to an exhaust duct in a factory via a pipe (not shown).

The exhaust system will be described below in detail.
As shown in FIGS. 1 to 3, the exhaust pipe 3 extends from the exhaust port 24 horizontally, for example, and then bends downward, almost right below, and further extends almost vertically upward. The lower end of the exhaust pipe 3 is bent substantially in a U shape, and the drain pipe 4 branches at the bent portion 31. The bent portion 31 is constituted by a ventilation path unit 33 in which a ventilation path 32 is formed. The ventilation path 32 forms a part of the exhaust pipe 3 and a branch point of the drain pipe 4. Further, a pressure monitoring unit 34 (see FIG. 1) for detecting the pressure in the exhaust pipe 3 and monitoring the pressure in the reaction pipe 22 and a valve 35 are provided between the exhaust port 24 and the bent portion 31.

As shown in FIG. 4, the cooler 5 has a tubular body 51 through which exhaust gas passes, a cooling water passage 52 formed vertically above and outside the tubular body 51, and a cooling water passage 52 inside the tubular body 51. A semicircular baffle plate 53 corresponding to the cross-sectional shape in the tubular body 51 is provided at predetermined intervals in the length direction and alternately arranged on the left and right sides. The moisture remaining in the exhaust gas is condensed by the collision with the baffle plate 53 and the cooling by the cooling water when passing through the cooler 5, and the condensed water is transmitted through the exhaust pipe 3 and the drain pipe 4 to form a sealed container. It falls into 41. The exhaust gas is cooled by the cooler 5.

The drain pipe 4 is inserted into the hermetic container 41 from above so that the opening at the lower end of the drain pipe 4 is located near the bottom of the hermetic container 41, and serves as a second drain passage member. A drain pipe 42 protrudes from below. The opening at one end (upper end) of the drain pipe 42 is the drain pipe 4
The lower end of the drain pipe 42 is located, for example, about 6 to 8 cm above, and the other end of the drain pipe 42 is connected to, for example, an external drain path side to drain dew water. 43 is a valve.

The water stored in the sealed container 41 is drained
During the oxidation process of the wafer, water vapor is condensed in the exhaust pipe 3 and the cooler 5 and water flows down, so that the water level in the sealed container 41 is maintained at the height of one end opening of the drain pipe 42. Is done. As a result, a liquid phase is interposed between the openings of the drain pipe 4 and the drain pipe 42, and communication between them is prevented, so that the pressure on the drain pipe 42 side, that is, the back pressure of the drain pipe 4 is generated in the reaction pipe 22. No effect. The drain pipe 42 may protrude horizontally from the side instead of protruding from the lower side of the sealed container 41, and may have one end opening sideways.

FIG. 5 is a comparative example of the above-described trap. When the one end (upper end) opening of the drain pipe 42 is located lower than the lower end opening of the drain pipe 4 as in this comparative example, the drain pipe is drained. 4 and the drain pipe 42 communicate with each other, and the fluctuation in the pressure inside the reaction tube 22 due to the fluctuation in the back pressure of the drain pipe 4 is large.

In this example, as shown in FIG. 1, when the lower end opening of the reaction tube 22 is sealed with the cap 20, the space between the flange at the lower end of the reaction tube 22 and the cap 20 is formed by the sealing exhaust pipe 26. The water in the exhaust gas is sucked and flows down into the closed container 41 through the drain pipe 27 branched from the sealing exhaust pipe 26.

In the case where dry oxidation is performed using, for example, oxygen gas or ozone gas without using water vapor, the water in the sealed container 41 evaporates and is exhausted through the exhaust pipe 3 as it is. Drain pipe 4 and drain pipe 42
Will communicate. Also, when the dry oxidation is switched to the wet oxidation using steam, the same occurs due to a shortage of water in the sealed container 41 at the initial stage. Therefore, in the present embodiment, a water supply pipe 71 for supplying a liquid, for example, water is connected in the middle of the ventilation path 32 of the ventilation path unit 33 as shown in FIGS. Is adjusted to a small flow rate (for example, a flow rate at which a thin stream is formed) by the flow rate adjusting unit 73, and the drain pipe 4 is adjusted.
, Water is always stored in the closed container 41.

At the downstream side of the cooler 5 in the reaction tube 3, a pressure sensor 54 and a pressure monitoring unit 55, which are pressure detecting units, are provided via branch paths as shown in FIG. The pressure sensor 54 controls the opening of the butterfly valve 6 based on the detected value to adjust the pressure in the reaction tube 22, and the pressure monitoring unit 55 controls the pressure in the exhaust pipe 3 downstream of the cooler 5. For monitoring the pressure of the air. Since the pressure sensor 54 and the pressure monitoring unit 55 measure the pressure of the exhaust gas after the water has been removed by the cooler 5, it is possible to prevent the water from entering the instrument.

Further, on the downstream side of the pressure monitoring unit 55 in the exhaust pipe 3, a pressure fluctuation absorbing unit 8 is provided via a branch passage 81 as shown in FIGS. The pressure fluctuation absorbing section 8 is connected to a branch 81 so as to communicate with the outside (atmospheric pressure).
The opening 82 is formed on a horizontal holding surface 83 formed on an inner peripheral portion of the opening 82.
And a lid 84 placed so as to close the cover. Describing the role of the pressure fluctuation absorbing section 8, since the water vapor in the exhaust gas is condensed in the cooler 5, the downstream pressure fluctuates finely and frequently as shown by the solid line (1) in FIG. For this reason, the detection value of the pressure sensor 54 fluctuates, so that the butterfly valve 6 slightly moves, and the pressure in the reaction tube 22 becomes unstable.
Therefore, if the pressure fluctuation absorbing portion 8 is provided, the lid 84 closes the opening 82 up to a certain pressure value as shown in FIG. 8A, but if the pressure becomes too low, the lid 84 becomes under its own weight. It is drawn inward against the inside, that is, it is lifted up to open the opening 82 and the pressure increases. As a result, the pressure on the downstream side of the cooler 5 fluctuates smoothly as shown by a dotted line (2) in FIG. 7, and the opening / closing operation of the butterfly valve 6 becomes stable.
Therefore, the pressure in the reaction tube 22 is stabilized.

In this example, the lid 84 uses its own weight as a suppressing force for closing the opening 82. For example, a combination of a spring and the lid 84 is suppressed so that the opening 84 always closes the opening 82. 9 or as shown in FIG.
As shown in FIG. 7, the opening 82 is closed by a lid 85 made of an elastic film, for example, a rubber film, and when the pressure in the exhaust pipe 3 is low, the lid 85 can be drawn inside with the opening 82 closed. Good.

When the exhaust of the exhaust duct in the factory is stopped due to, for example, a power failure, the exhaust gas may leak from the gap between the lid 84 and the inner surface of the branch passage 81. The valve 86 is closed when a power failure or the like occurs.

Further, as shown in FIG. 1 and FIG.
A ventilation path unit 92 is provided downstream of the butterfly valve 6 via a valve 91 in the exhaust pipe 3.
Extends upward through a horizontal air passage 93 in the air passage unit 92, and the end thereof is connected to an exhaust duct in a factory (not shown). The main branch pipe 61 branches from the horizontal ventilation path 93. The main branch pipe 61 once goes upward from the ventilation path 93, then bends in a U-shape and extends downward, so that the drain pipe 4 in the closed vessel 41 is formed.
It is open at a position lower than the lower end. An auxiliary branch pipe 62 branches from the middle of the main branch pipe 61, and a pressure monitoring unit 63 is provided at a distal end thereof. This pressure monitor 6
Reference numeral 3 is for monitoring the pressure in the exhaust duct in the factory and shutting off the valves 86 and 91 when the exhaust is stopped due to a power failure or the like.

The main branch pipe 61 branches from the exhaust pipe 3 and is routed through a position higher than the branch point, so that even if water flows from the exhaust duct side in the factory, the main branch pipe 61 is left inside. And the pressure monitoring section 63 is provided from the main branch pipe 61 via the auxiliary branch pipe 62, so that there is no risk of water entering the pressure monitoring section 63. When water enters the main branch pipe 61, it flows down and is stored in the closed container 41.

The operation of such an exhaust system will be described. The gas containing water vapor in the reaction tube 22 is exhausted into the exhaust pipe 31 by the suction force of the exhaust duct in the factory, and the pressure of the pressure sensor 54 is reduced. The opening of the butterfly valve 6 is adjusted based on the detected value, so that the pressure in the reaction tube 22 is adjusted. Part of the moisture in the gas is condensed when passing through the exhaust pipe 31.
Dew forms inside the container, and the condensed water flows down and is stored in the closed container 41.

The water in the closed vessel 41 is discharged by a drain pipe 42. Since the drain pipe 42 and the drain pipe 4 are prevented from communicating with each other by water, the pressure in the reaction pipe 22 is reduced by the drain pipe 4. Unaffected by back pressure. Cooler 5
However, the pressure in the downstream side tends to fluctuate little by little because moisture in the exhaust gas condenses, but the fluctuation of the butterfly valve is suppressed because the pressure fluctuation is absorbed and smoothed by the pressure fluctuation absorbing section 8. Therefore, the pressure in the reaction tube 22 can be controlled with high accuracy.

Further, since water is always stored in the sealed container 41 by the water supply pipe 71, even when performing dry oxidation without using steam, communication between the drain pipe 4 and the drain pipe 42 is prevented. Stable pressure control can be performed. In the present invention, water may be supplied from the water supply pipe into the closed container 41 only when dry oxidation is performed. However, if water is supplied only slightly as described above, the operator may forget to perform the water supply operation. Risk can be avoided.

[0030]

As described above, according to the present invention, when heat treatment is performed using steam, the pressure in the reaction vessel can be controlled with high precision, and for example, a high-quality oxide film can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which the exhaust device according to the embodiment of the present invention is attached to the back surface of the vertical heat treatment device.

FIG. 3 is a side view showing the exhaust device.

FIG. 4 is a partially cutaway side view showing an example of a cooler.

FIG. 5 is a cross-sectional view showing a comparative example of a structure inside a closed container forming a trap.

FIG. 6 is a sectional view showing a pressure fluctuation absorbing section.

FIG. 7 is a characteristic diagram schematically showing a state of pressure fluctuation on the downstream side of the cooler.

FIG. 8 is an explanatory diagram illustrating an operation of a pressure fluctuation absorbing unit.

FIG. 9 is an explanatory diagram showing another example of the pressure fluctuation absorbing unit.

FIG. 10 is a configuration diagram showing a conventional exhaust device.

[Explanation of symbols]

 Reference Signs List 22 Reaction pipe 24 Exhaust port 3 Exhaust pipe 4 Drain pipe 41 Closed vessel 42 Drain pipe 5 Cooler 6 Butterfly valve 61 Main branch pipe 62 Auxiliary branch pipe 63 Pressure sensor 71 Water supply pipe 8 Pressure fluctuation absorbing part 81 Branch pipe 82 Opening 84 Lid

Claims (6)

[Claims] An exhaust device connected to a reaction vessel that performs heat treatment on an object to be processed using steam, an exhaust path member connected to the reaction vessel, and an exhaust gas provided in the exhaust path member. Dew-condensing means for dew-condensing moisture therein; a pressure adjusting unit provided downstream of the dew-condensing means in the exhaust path member; and a lower position between the exhaust port of the reaction vessel and the dew-condensing means. A first drainage channel member branched from the exhaust channel member, and a seal in which a lower end of the first drainage channel member is opened so as to accumulate water flowing through the first drainage channel member. A container, a second drainage member having one end opened in the closed container,
And one end of the second drainage channel member is opened at a position above the lower end opening of the first drainage channel member so as to be able to suck water in a closed vessel, and the first drainage member is provided. The liquid level is located above the lower end opening of the channel member so that a liquid phase exists between the respective openings of the first drainage channel member and the second drainage channel member. Exhaust system. 2. A liquid supply means for supplying a liquid into the closed container such that a water level in the closed container is located above an opening of the first drainage channel member. Item 7. The exhaust device according to Item 1. 3. A downstream side of the exhaust path member is connected to an exhaust duct provided in a factory, and a main branch path is provided at a level higher than a branch point of the exhaust path member from a downstream side of the pressure adjusting section. And a pressure monitoring unit for detecting a pressure in the main branch path and monitoring a pressure in the exhaust duct by branching so as to be connected to the closed vessel via the airtight container. 2
The described exhaust device. 4. An auxiliary branch is further branched from the main branch.
The exhaust device according to claim 3, wherein a pressure monitoring unit is provided in the auxiliary branch passage. 5. An exhaust device connected to a reaction vessel for performing heat treatment on an object to be processed using steam, comprising: an exhaust path member connected to the reaction vessel; and an exhaust gas provided in the exhaust path member. Dew-condensing means for dew-condensing moisture therein; a pressure adjusting unit provided downstream of the dew-condensing means in the exhaust path member; and a lower position between the exhaust port of the reaction vessel and the dew-condensing means. A first drainage path member branched from the exhaust path member, and a branch path branching from the downstream side of the dew condensation means in the exhaust path member; A pressure fluctuation absorbing portion for absorbing pressure fluctuation in the exhaust path member due to condensation of the pressure fluctuation absorbing portion, wherein the pressure fluctuation absorbing portion has an opening formed in the branch passage so as to communicate with the outside, and the opening Department And a lid that opens toward the inside against the restraining force and opens the opening when the pressure in the exhaust path member is reduced. apparatus. 6. The lid of the pressure fluctuation absorbing section closes the opening when the pressure in the exhaust passage member decreases, instead of being drawn inward against the suppressing force and opening the opening. 6. The exhaust device according to claim 5, wherein the exhaust device is formed of an elastic film so as to be drawn inside while being held.