JP3126487B2 - Oxidation treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation treatment apparatus, and more particularly to an oxidation treatment apparatus for oxidizing a semiconductor wafer.

[0002]

2. Description of the Related Art Generally, in the manufacture of semiconductor devices, an oxidation treatment step for forming an oxide film on the surface of a semiconductor wafer is required. One of the methods for carrying out this oxidation treatment is an oxidation treatment furnace. There is a method in which a semiconductor wafer is brought into contact with water vapor at a high temperature. And
For example, as disclosed in JP-A-56-62326, a method is known in which hydrogen gas and oxygen gas are directly supplied to an oxidation furnace and burned to generate steam in the oxidation furnace. I have.

However, in the method of burning hydrogen gas and oxygen gas in the oxidation furnace, the temperature in the oxidation furnace is greatly affected by the degree of combustion of the hydrogen gas and oxygen gas. It is difficult to sufficiently control the processing temperature, and there is a problem that the reliability, stability and reproducibility of the oxidation processing on the semiconductor wafer are low.

On the other hand, as disclosed in, for example, JP-B-63-60528 and JP-A-63-210501, a steam generator is provided as an external combustion device independently of an oxidation treatment furnace. There is also known a method in which hydrogen gas and oxygen gas are supplied to an apparatus and burned to generate steam, and the steam is supplied to an oxidation furnace through an appropriate steam supply pipe. According to such a method, the heating state in the oxidation treatment furnace can be controlled separately from the operation state of the steam generator.
It is possible to perform an oxidation treatment on a semiconductor wafer in an oxidation treatment furnace with high reliability, stability and reproducibility.

[0005] In an oxidation treatment apparatus using such an external combustion type steam generation device, a pipe member made of quartz is used to supply steam from the steam generation device to the oxidation treatment furnace. One end is connected to a quartz steam discharge pipe of the steam generator by a connector such as a ball joint by sliding, and the other end of the pipe member is connected to the quartz steam introduction pipe of the oxidation treatment furnace by a similar connector. Means have been known for some time.

However, in this connection means,
Quartz has little degree of freedom for deformation, and the allowable width for displacement of the connection position is extremely small, so that extremely high positional accuracy is required for connecting the steam supply pipe with the steam discharge pipe and the steam introduction pipe. As a result, it is practically extremely difficult to realize the connection with high sealing performance.

[0007]

In view of the circumstances described above, as a member constituting a pipe member and a connector for a steam supply pipe, the pipe itself has relatively large flexibility, and the connection is difficult. The use of a fluororesin such as Teflon, which is preferable because the allowable width of displacement is relatively large, has been studied. However, fluororesins such as Teflon generally have a heat resistance temperature of about 260 ° C. or lower and have relatively low heat resistance. Therefore, when high-temperature steam flows in, a deformation or the like occurs and the sealing property of the connection portion is lost. Therefore, there is a high possibility that leakage occurs.

More specifically, recently, the diameter of a semiconductor wafer to be oxidized has been increased to 6 inches or 8 inches. In order to perform the process with high efficiency, it is required to increase the amount of steam supplied to the oxidation treatment furnace, and it is necessary to generate a large amount of steam in the steam generator.

However, if a large amount of hydrogen gas and oxygen gas are supplied to the steam generator for combustion in order to generate a large amount of steam, the combustion temperature naturally rises to a high temperature far exceeding 300 ° C. Water vapor is discharged, and therefore, when a pipe member and a connector made of a fluororesin such as Teflon, which itself is suitable in terms of a large degree of freedom in connection, are used in the configuration of the water vapor supply pipe. Has a problem in that a large amount of water vapor cannot be supplied stably to the oxidation furnace.

The present invention solves the above-mentioned problems, and even when high-temperature steam is generated due to a high combustion temperature in a steam generator, low-temperature steam is discharged from a steam discharge pipe, and steam is supplied. It is an object of the present invention to provide an oxidation treatment apparatus capable of stably supplying a large amount of steam to an oxidation treatment furnace without causing a leak even when a pipeline is made of a fluorine resin such as Teflon.

[0011]

An oxidation treatment apparatus according to the present invention comprises an oxidation treatment furnace and a steam generation device connected to the oxidation treatment furnace via a steam supply pipe. The generator includes a combustion vessel, a hydrogen gas introduction pipe and an oxygen gas introduction pipe that open to the space inside the vessel at a lower portion of the combustion vessel, and a hydrogen gas and an oxygen gas so that the hydrogen gas is burned by the oxygen gas in the combustion vessel. a heater for heating at least one of gas, provided in the upper portion of the combustion chamber, cylindrical shape the steam supply Okukanro is connected
Inside the steam discharge section and the steam discharge section
Provided to close the space and formed through holes at displaced positions
And a cooling mechanism provided around the combustion vessel.

Further , the oxidation treatment apparatus according to the present invention provides an oxidation treatment apparatus.
Furnace and this oxidation treatment furnace via a steam feed line.
It and a steam generating device, the steam generating instrumentation
The combustion chamber and the lower part of the combustion vessel
Hydrogen gas introduction pipe and oxygen gas introduction pipe opening into space
And the hydrogen gas is converted into oxygen gas in the combustion vessel.
At least one of hydrogen gas and oxygen gas to combust
A heater for heating one side, and a heater provided at an upper part of the combustion vessel.
A steam discharge section to which the steam feed pipe is connected;
A heat radiating member provided in the water vapor discharging portion;
A cooling mechanism provided around the vessel , wherein an inner cylinder is provided within the combustion vessel to define a combustion space whose upper part is closed, and an outer peripheral surface of the inner cylinder and an inner circumference of the combustion vessel are provided. The cylindrical space between the upper surface and the lower surface communicates with the combustion space in the inner cylinder at the lower portion and communicates with the inner space of the steam discharge section at the upper portion to form a steam passage.
It is characterized by.

[0013]

According to the oxidation treatment apparatus of the present invention, in the steam generator, since the heat radiating member is provided at the steam discharge section in the upper part of the combustion vessel, even when the combustion temperature becomes high, the steam discharge section is provided. The steam is cooled by passing through the steam, and the steam flowing into the steam supply pipe becomes cold. Therefore, even when a steam supply pipe is formed using a fluorine resin such as Teflon which is preferable in that the degree of freedom in connection is large, no leak occurs.
A large amount of steam can be generated in the steam generator and can be stably fed to the oxidation furnace.

[0014]

Embodiments of the present invention will be described below. FIG. 1 is a longitudinal sectional view for explaining a steam generator 20 in an oxidation treatment apparatus according to one embodiment of the present invention. The steam generator 20 of this example includes a cylindrical combustion vessel 21 made of quartz provided with its axis extending vertically, and a hydrogen gas made of quartz extending upward is provided on the lower bottom of the combustion vessel 21.
Gas introduction pipe 22 and the hydrogen gas introduction pipe 22 and a double pipe structure.
An oxygen gas inlet pipe 23 extending upwardly is constructed.
Around the opening 22A of the hydrogen gas introduction pipe 22,
The annular opening 23A formed by the oxygen gas introduction pipe 23 is upward.
It is formed in a state facing the internal space of. Here, before
The enlarged diameter portion 23P of the oxygen gas introduction pipe 22 is
And are formed integrally.

Below the combustion vessel 21, a gas heating heater 33 is disposed around a portion where the hydrogen gas introduction pipe 22 and the oxygen gas introduction pipe 23 constitute a double pipe structure. The gas heating heater 33 heats the introduced hydrogen gas and oxygen gas to a temperature equal to or higher than the auto-ignition temperature. Thus, when released into the combustion vessel 21, the hydrogen gas is mixed with the oxygen gas and burned. F is a flame due to combustion.

In the combustion vessel 21, a cylindrical inner cylinder 40 made of quartz and defining a combustion space S is provided coaxially, and an outer peripheral surface of the inner cylinder 40 and an inner peripheral surface of the combustion vessel 21 are formed. A cylindrical space 41 is formed therebetween. This inner cylinder 40
Is integrally connected to the combustion vessel 21 with its upper part closed and its lower end open. And the inner cylinder 40
A through-hole 42 is formed at the lower end of the cylinder to communicate the combustion space S and the cylindrical space 41. A cooling mechanism 32 composed of, for example, a water-cooled jacket is provided around the combustion vessel 21.

The upper part of the combustion vessel 21 is provided with the combustion vessel 2
A cylindrical water vapor discharge section 25 having a diameter smaller than 1 is formed integrally with the combustion vessel 21 by quartz, and an internal space thereof is communicated with the cylindrical space 41. As shown in FIG. 2, the water vapor discharge portion 25 has two quartz internal heat radiating plates 45 and 46 extending in the horizontal direction from the inner peripheral wall thereof so as to close the internal space and to extend vertically from each other. The lower internal heat sink 4 is integrally provided in a separated state.
5, a through hole 48 is formed at a position displaced to one side (right side in the figure) from the center thereof, and the upper internal heat dissipation plate 46 is formed on the other side (left side in the figure) from the center. A through hole 49 is formed at the displaced position.

Further, on the outer peripheral wall of the water vapor discharge portion 25, two external heat radiating plates 52 made of quartz in this example are vertically spaced apart from each other, and each project outwardly in a flange shape in the horizontal direction. It is formed integrally.

The water vapor discharge section 25 is provided with a water vapor discharge pipe 26 projecting from the upper wall thereof, and one end of a water vapor supply pipe 30 is connected to an end of the water vapor discharge pipe 26. The steam supply line 30 is constituted by a connector including a tube 35 and a nut 36 formed of, for example, a fluororesin such as Teflon, and the other end is provided with a steam introduction pipe of an oxidation furnace 60 as shown in FIG. A nut 64 made of a similar material
Connected by a connector including Further, for example, a sheet heater 38 is provided on the outer periphery of the tube 35 of the steam supply line 30.

The oxidation furnace 60 in the illustrated example is a vertical furnace constituted by a cylindrical reaction tube 61 made of quartz. A steam introduction tube 63 is provided at a steam introduction port 62 above the reaction tube 61. I have. A lower end opening of the reaction tube 61 is openably and closably closed by a cap 65, and a wafer boat 68 is supported on the cap 65 via a heat retaining tube 66, and a large number of semiconductor wafers W extend horizontally on the wafer boat 68. And are supported so as to be separated from each other vertically. A heater 69 for heating the inside is provided around the reaction tube 61, and an exhaust pipe 70 is provided below the reaction tube 65.

On the other hand, as shown in FIG. 3, a hydrogen gas source 74 is connected to the hydrogen gas introducing pipe 22 of the steam generating device 20 via a flow rate control mechanism 73, and the oxygen gas introducing pipe 23 is connected to the oxygen gas introducing pipe 23. Switching valve 75 and flow control mechanism 76
The oxygen gas source 77 is connected via the. In addition, a nitrogen gas source 80 is provided via a flow rate control mechanism 83 in a nitrogen gas introduction pipe 81 branched from the switching valve 75.

Next, the operation of the oxidation treatment apparatus having the above configuration will be described. First, an initial purge is performed using nitrogen gas first and then using oxygen gas using the oxygen gas introduction pipe 23. That is, nitrogen gas is supplied from the nitrogen gas source 80 to the oxygen gas introduction pipe 23 via the nitrogen gas introduction pipe 81, and the inside of the steam generator 20, the steam supply pipe 30 and the oxidation treatment furnace 60 is replaced with nitrogen gas. You. The nitrogen gas is exhausted by the exhaust pipe 70 of the oxidation furnace 60.

In the state of being replaced by nitrogen gas, the cap 65 of the oxidation furnace 60 is opened,
A wafer boat 68 supported by a heat retaining cylinder 66 by an elevator (not shown) is loaded into the reaction tube 61, and thereby the semiconductor wafer W to be oxidized is supplied to the reaction tube 61.
1 at a predetermined position. After that, the switching valve 75 is switched to supply the oxygen gas from the oxygen gas source 77, whereby the inside of the steam generator 20, the steam supply line 30, and the oxidation furnace 60 are replaced with the oxygen gas.

In this state, the gas heater 33
Is maintained at a heating state of, for example, about 850 ° C., and a hydrogen gas source 7
4 through a hydrogen gas inlet pipe 22 to supply hydrogen gas to the steam generator 20 at a predetermined flow rate, for example, 4.8 liters per minute, and to supply oxygen gas at a predetermined flow rate, for example, 5.0 liters per minute. When these gases are supplied to the steam generator 20 at a flow rate of, these gases are heated by the gas heating heater 33 to ignite when released into the combustion space S and burn with a flame F. Generates steam. The gas heating heater 33 is maintained in its operating state even after the combustion in the combustion space S is started.

The ratio between the amount of hydrogen gas and the amount of oxygen gas supplied to the steam generator 20 does not need to be 2: 1 according to the stoichiometry, and the oxygen gas is usually supplied in a slightly excessive amount. Here, the excess oxygen gas acts as a carrier gas and contributes to the oxidation treatment in the oxidation treatment furnace 60. Oversupply of hydrogen gas should be avoided because of the danger of explosion. The supply amounts of the hydrogen gas and the oxygen gas are appropriately selected according to the intended degree of the oxidation treatment, and are controlled by the flow rate control mechanisms 73 and 76.

The water vapor generated in the combustion space S as described above passes through the through hole 42 at the lower end of the inner cylinder 40 and rises in the water vapor passage formed by the cylindrical space 41. Cooling mechanism 3 around combustion vessel 21
2, the high-temperature steam is first cooled while flowing through the steam passage formed by the cylindrical space 41.

The water vapor from the cylindrical space 41 reaches the water vapor discharge portion 25, passes through the through hole 48 of the lower internal heat radiation plate 45 provided in the water vapor discharge portion 25, and then passes through the upper internal heat radiation plate. Although high-pressure water vapor passes through the through holes 49 of the heat radiation plates 45 and 46, a high-temperature water vapor is heat-exchanged with the internal heat radiation plates 45 and 46 with high efficiency because the heat radiation plates 45 and 46 form a passage for water vapor having a large surface area. As a result, the steam is cooled to a low temperature.

The steam which has become low in temperature flows into the steam supply pipe 30 from the steam discharge pipe 26, and is supplied to the oxidation furnace 60 through the steam supply pipe 63 by the steam supply pipe 30. Sent.

In the oxidation treatment furnace 60, the steam introduction pipe 6
Although the water vapor from 3 flows downward in the reaction tube 61, the semiconductor wafer W in the reaction tube 61 is maintained at a high temperature of, for example, about 900 ° C. or more by the heater 70. As a result, the semiconductor wafer W The desired oxidation treatment is performed. The water vapor is then exhausted by the exhaust pipe 70.

After the intended oxidation treatment is performed on the semiconductor wafer W in the oxidation treatment furnace 60 in this manner,
The introduction of the hydrogen gas into the steam generator 20 is stopped, and the introduction of only the oxygen gas is continued. As a result, the steam generator 20, the steam supply line 30, and the oxidation furnace 6
The semiconductor wafer W is taken out of the oxidation processing furnace 60 in a state where the inside of O is replaced with oxygen gas and further replaced with nitrogen gas.

In the present invention, however, the water vapor from the combustion space S is cooled when flowing through the water vapor passage formed by the cylindrical space 41, and then, in the water vapor discharge section 25, the through holes 48 of the internal heat radiation plates 45 and 46. Cooling is achieved by passing through the passage formed by and.
When the external heat radiating plate 52 is provided in the water vapor discharging section 25, the cooling efficiency is further improved.
Therefore, even when the combustion temperature becomes high as a result of generating a large amount of water vapor in the water vapor generation device 20, the water vapor flowing into the water vapor supply line 30 from the water vapor discharge pipe 26 can be made low in temperature. Also, when the steam supply line 30 is made of a fluororesin such as Teflon, the deformation is not caused, and no leak is caused. For this reason, a large amount of steam is generated in the steam generator 20 and is stably
Can be sent to

When the steam in the steam supply line 30 is supercooled, the steam supply line 30
In this case, it is difficult to sufficiently control the amount of steam supplied to the oxidation treatment furnace 60 due to dew condensation, but the temperature of the steam in the supply pipe 30 is reduced by 1 by the sheet heater 38.
By maintaining the temperature at about 30 ° C., dew condensation can be prevented.

FIG. 4 is a sectional view of a gas introduction head 90 which can be suitably used in the steam generator of the present invention. The gas introduction head 90 is provided at the upper end of a double-layered structure formed by the hydrogen gas introduction pipe 22 and the oxygen gas introduction pipe 23. The opening 22A of the hydrogen gas introduction pipe 22 and the opening 23A of the oxygen gas introduction pipe 23 Gas introduction head 9
The two are formed at the ends of a hydrogen gas passage 22B and an oxygen gas passage 23B that extend obliquely upward while extending outward in the radial direction so as to vertically overlap each other at the outer periphery of 0. The hydrogen gas passage 22B and the oxygen gas passage 23B may be in a state of spirally extending while expanding outward.

When the gas introduction head 90 having such a configuration is used, the hydrogen gas passage 22B and the oxygen gas passage 23B
Due to the directionality of the hydrogen gas, the hydrogen gas is supplied to the combustion space S in a state of spreading outward in the radial direction. Therefore, even when a large amount of hydrogen gas and oxygen gas are supplied to generate a large amount of water vapor, the flame is F becomes thicker in the radial direction, but does not extend upward. Therefore, without increasing the height of the combustion vessel 21 and the inner cylinder 40, and thus the steam generator 20 so much, the inner surface of the combustion vessel 21 becomes larger. There is an advantage that it is possible to avoid direct contact of the flame F.

That is, in the present invention, the combustion vessel 2
1, inner cylinder 40, water vapor discharge section 25, water vapor discharge pipe 26,
It is preferable that all of the internal heat radiating plates 45 and 46 and the external heat radiating plate 52 are integrally formed of quartz. However, when the flame F directly contacts the quartz wall surface, the quartz crystallizes and becomes brittle, May be a source of impurities for However, if a large amount of hydrogen gas and oxygen gas are simply supplied directly upward into the combustion space S, the height of the formed flame F increases, and the wall surface forming the ceiling of the combustion space S, for example, the inner cylinder 40 Comes into contact with the upper wall of the car.

In order to avoid such a situation, of course, the height of the combustion space S may be made sufficiently large. In this case, however, the entire steam generator becomes large. However, if the gas introduction head 60 as described above is used, the height of the flame F does not increase, so that the flame F contacts the inner wall surface of the combustion space S without increasing the size of the steam generator. That can be avoided.

Although the embodiment of the present invention has been described above, various modifications can be made in the present invention. For example, in the water vapor discharge portion, the internal heat radiating plate is indispensable, but the external heat radiating plate on the outer peripheral wall is not necessarily indispensable, and the inner cylinder can be removed. Further, the shape and number of the internal heat sinks are not particularly limited. Furthermore, it is not essential that the hydrogen gas introduction pipe and the oxygen gas introduction pipe have a double pipe structure, and even if the gas heater is configured to heat either the hydrogen gas or the oxygen gas. Good. Although a vertical furnace is exemplified as the oxidation treatment furnace, a horizontal furnace may be used.

[0038]

As described above, according to the oxidation treatment apparatus of the present invention, since the heat radiating member is provided in the water vapor discharge portion in the upper part of the combustion vessel, the combustion temperature in the combustion space becomes high. In addition, the steam is cooled by passing through the steam outlet, and as a result, the temperature of the steam flowing from the steam outlet to the steam feed pipe becomes low. Therefore, even when the steam supply pipe is made of a fluororesin such as Teflon, there is no leak, and a large amount of steam is generated in the steam generator and is supplied to the oxidation furnace stably. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory vertical sectional front view showing a configuration of a steam generator in an oxidation treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a cross-sectional plan view for explaining a steam discharge section in the steam generator according to one embodiment of the present invention.

FIG. 3 is an explanatory view schematically showing an overall configuration of an oxidation treatment apparatus according to one embodiment of the present invention.

FIG. 4 is an explanatory longitudinal sectional view showing an example of a configuration of a gas introduction head suitably used in the present invention.

[Explanation of symbols]

Reference Signs List 20 steam generator 21 combustion vessel 22 hydrogen gas introduction pipe 22A opening of hydrogen gas introduction pipe 22B hydrogen gas passage 23A opening of oxygen gas introduction pipe 23B oxygen gas passage 22P enlarged diameter portion of hydrogen gas introduction pipe 23 oxygen gas introduction pipe 23A oxygen Gas inlet pipe opening 25 Water vapor discharge part 26 Water vapor discharge pipe 30 Water vapor supply pipe 32 Cooling mechanism 33 Gas heating heater 35 Tube 36, 64 Nut 38 Sheet heater 40 Inner cylinder 41 Cylindrical space 42 Through hole 45, 46 Internal heat radiating plate 48, 49 Through hole 52 External heat radiating plate 60 Oxidation treatment furnace 61 Reaction tube 62 Water vapor introduction port 63 Water vapor introduction tube 65 Cap 66 Heat retaining cylinder 68 Wafer boat 69 Heater 70 Exhaust tube 73, 76, 8
3 Flow control mechanism 74 Hydrogen gas source 75 Switching valve 77 Oxygen gas source 80 Nitrogen gas source 81 Nitrogen gas introduction pipe 90 Gas introduction head F Flame S Combustion space W Semiconductor wafer

Claims (2)

(57) [Claims] 1. An oxidizing furnace, and a steam generator connected to the oxidizing furnace via a steam supply pipe, wherein the steam generating device includes a combustion vessel and a lower part of the combustion vessel. A hydrogen gas introduction pipe and an oxygen gas introduction pipe that open to the space inside the vessel, a heater that heats at least one of hydrogen gas and oxygen gas so that the hydrogen gas is burned by oxygen gas in the combustion vessel, A cylinder provided at the upper part of the pipe and connected to the steam supply pipe
Inside of the steam outlet and the steam outlet
A through hole is formed at the displaced position.
An oxidation treatment apparatus comprising: a radiating member including a plurality of formed internal radiating plates; and a cooling mechanism provided around the combustion vessel. 2. An oxidation furnace and steam in the oxidation furnace.
With a steam generator connected via a feed line
The steam generator comprises a combustion vessel and a part below the combustion vessel.
Hydrogen gas inlet pipe opening into the space inside the container in the section
Oxygen gas inlet pipe and hydrogen gas in the combustion vessel
Hydrogen gas and oxygen gas to burn with oxygen gas
A heater for heating at least one of:
Water provided at the top and connected to the steam feed line
A steam discharge portion, and a heat radiating member provided in the steam discharge portion
And a cooling mechanism provided around the combustion vessel.
In the combustion vessel, an inner cylinder that defines a combustion space whose upper part is closed is provided, and a cylindrical space between an outer peripheral surface of the inner cylinder and an inner peripheral surface of the combustion vessel is provided at a lower part thereof. JP forming a steam passage communicating with the interior space of the steam discharge section at its upper portion communicates with the combustion space in the inner cylinder
Oxidation processing apparatus according to symptoms.