JP3474991B2 - Oxidation treatment apparatus and oxidation treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an oxidation processing apparatus which applies a steam to a semiconductor wafer to perform oxidation processing.
And an oxidation treatment method .

[0002]

2. Description of the Related Art Generally, in the manufacture of a semiconductor integrated circuit, there is an oxidation treatment step for forming an oxide film on the surface of a semiconductor wafer in order to form a gate oxide film and various insulating films in elements. As one of the methods, there is a method in which a semiconductor wafer is brought into contact with water vapor at high temperature in a processing furnace to be oxidized (wet oxidation). In order to carry out such an oxidation treatment, for example, Japanese Patent Publication No. 63-60.
As disclosed in Japanese Patent Application Laid-Open No. 528, JP-A-63-210501, etc., a combustion device for combusting hydrogen gas and oxygen gas to generate water vapor is independently provided outside the processing furnace. There is known a method of supplying steam generated by the above method to a processing furnace through a steam supply pipe line.

According to this method, unlike the method in which hydrogen gas and oxygen gas are burned in the processing furnace to generate steam, the heating state in the processing furnace can be controlled separately from the operating state of the combustion apparatus. Therefore, it becomes possible to perform the oxidation treatment on the semiconductor wafer in the treatment furnace with high reliability, safety and reproducibility. In such an oxidation treatment, how to improve the film quality of the oxide film is an important issue in order to improve the characteristics of the semiconductor integrated circuit. Since most of it is composed of metal, various metals contained in stainless steel are dissolved out in the steam generated by combustion, but this causes metal contamination to the wafer. There was a problem of tightening.

This metal contamination was not a serious problem in the conventional semiconductor device having a high degree of integration, but recently, fine integration such that the line width is in the order of submicron due to further integration has been achieved. It can no longer be ignored in the process. Then, in order to solve this metal contamination, the steam generator 2 as shown in FIG. 7 is proposed. This steam generator 2 uses a heat-resistant member that is not a metal and has no risk of methane contamination, for example, a cylindrical container 4 made of quartz, and a filter 6 formed by collecting and sintering a large number of quartz beads therein. Are housed. Then, for example, a resistance heating heater 8 is provided on the outer circumference of the cylindrical container 4 so as to cover the entire circumference,
A carrier gas composed of pure water and an inert gas such as N ₂ is introduced from one end of the container 4, and the pure water is heated and vaporized by heat conduction from the resistance heating element 8 and supplied to the film formation processing furnace. It is supposed to do.

[0005]

According to the steam generator 2 having such a structure, since the metal material such as stainless steel is not used, it is possible to solve the problem of metal contamination. However,
Unlike the above-described stainless steel steam generator, the quartz-cylindrical container 4 has considerably poor thermal conductivity. Therefore, the Joule heat generated by the resistance heating heater 8 is efficiently purified water in the container. However, there was a new problem in that the thermal efficiency was poor and a sufficient amount of water vapor could not be secured. In this case, a large-capacity resistance heating element must be used in order to secure a sufficient amount of water vapor, which is not realistic. In particular, when the wafer size becomes large and becomes 8 inches or 12 inches in size, a large amount of water vapor is required during the oxidation batch processing, and an early solution is desired.
The present invention has been made to pay attention to the above problems and to solve them effectively. It is an object of the present invention to provide an oxidation treatment apparatus and an oxidation treatment method capable of increasing thermal efficiency and increasing the amount of steam generated without causing metal contamination.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a processing furnace for oxidizing an object to be processed at a high temperature, a heat-resistant container including an infrared transmitting member, and a lamp for generating infrared rays. A steam generating unit that has a heater unit and vaporizes pure water introduced by radiant heat from the lamp heater unit, and a steam supply passage that supplies the steam generated here to the processing furnace It was done.

With this structure, the pure water introduced into the heat-resistant container made of the infrared transmitting member is heated by the infrared radiation heat from the lamp heater provided to cover the container to be vaporized. Then, the generated steam flows through the steam supply passage and is supplied into the processing furnace. In this case, the light from the lamp heater,
The infrared rays easily pass through the container without being absorbed and heat the pure water inside. Therefore, the amount of heat absorbed by the container is extremely small, and it becomes possible to efficiently heat and vaporize pure water, and a large amount of vapor can be generated. As the material of the heat-resistant container, for example, quartz can be used, and this container is formed as a hollow cylindrical body having a ring-shaped cross section with a heater accommodating hole in the center, and the lamp heater part is inserted into this heater accommodating hole. Heat pure water from the center. Also, if a reflector is provided on the outer periphery of the container, infrared rays emitted from the center and transmitted through the container are reflected by the reflector,
Again, it contributes to the heating of pure water, and the thermal efficiency can be further improved.

Further, instead of forming the heat-resistant container as a hollow cylinder as described above, it may be formed into a cylindrical shape, for example, and the lamp heater portion may be arranged around it. In this case, a reflector may be provided outside the lamp heater section.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an oxidation treatment apparatus and an oxidation treatment method according to the present invention will be described in detail below with reference to the accompanying drawings. 1 is an overall configuration diagram showing an oxidation treatment apparatus according to the present invention, FIG. 2 is a cross-sectional view showing a steam generating section used in the apparatus shown in FIG. 1, FIG. 3 is a side view of the steam generating section shown in FIG. 2, and FIG. FIG. 3 is a plan view showing a lamp heater unit used in the device shown in FIG. 2.

As shown in the figure, this oxidation treatment apparatus 10
Is a semiconductor wafer W to be processed, for example, at 850 ° C.
It has a vertical processing furnace 12 which performs an oxidation process at a high temperature of about a certain degree, and this processing furnace 12 is provided with a vertically long cylindrical quartz reaction tube 14 having an open lower end. A lid 16 that opens and closes the lower end opening is arranged below the reaction tube 14 so as to hermetically seal it, and a large number of semiconductor wafers W are horizontally placed on the lid 16 in the vertical direction. The wafer boat 18 made of quartz, which is supported in multiple stages at a predetermined pitch, is used as the heat insulation tube 2.
Supported through 0.

The lid 16 is connected to an elevating mechanism 22 such as a boat elevator that carries the wafer boat 18 into and out of the reaction tube 14 and opens and closes the lid 16. In addition, the inside of the reaction tube 14 is 800
A heater 24 for heating to a desired temperature of about 1000 ° C. is arranged in a coil shape, and an outer shell 28 is provided on the outer periphery of the heater 24 so as to cover the whole with a heat insulating material 26 interposed therebetween. A water vapor introducing pipe 30 is integrally formed on one side of a lower portion of the reaction pipe 14, and a base portion side of the water vapor introducing pipe 30 is integrated with a pipe wall of the reaction pipe 14 and then guided upward. It is opened so as to face a water vapor introduction port 32 formed in a concave shape at the upper end of the pipe 14. Further, an exhaust pipe 34 is integrally formed on the other side of the reaction tube 14, and a double decompression pipe 38 having a decompression pump 36 as a decompression means for decompressing the inside of the reaction pipe 14 is formed in the exhaust pipe 34. O-ring 4
They are airtightly connected via a flange joint 42 provided with 0.

An opening / closing valve 44 is interposed in the pressure reducing pipe 38, and a bypass pipe 46 bypassing the opening / closing valve 44.
The bypass pipe 46 is provided with an opening / closing valve 48 such as an air-operated valve and a pressure control valve 50 such as a piezo valve. When decompressing the inside of the reaction tube 14 to a predetermined pressure of about 300 to 500 Torr, first the opening / closing valve 44 of the decompression tube 38 is opened while detecting the pressure with the pressure sensor 52 provided in the decompression tube 38. The controller 54 controls the pressure control valve 50 to maintain a predetermined pressure by closing the opening / closing valve 44 of the pressure reducing pipe 38 and opening the opening / closing valve 48 of the bypass pipe 46. There is. The downstream side of the decompression pipe 38 is connected to a factory exhaust duct (not shown).

In order to supply steam into the reaction tube 14 of the processing furnace 12, steam is generated by the steam generating section 54, which is a feature of the present invention, in which pure water is boiled to generate steam. A steam supply passage 56, which is made of, for example, Teflon or stainless steel which has been subjected to surface treatment such as inner surface polishing, is provided to supply the steam to the reaction tube 14. The steam supply passage 56 is provided with the steam supply passage 56.
Is airtightly connected via a flange joint 58 provided with a double O-ring. A pure water introducing pipe 60 for introducing pure water into the steam generating unit 23 is connected to the side of the steam generating unit 23, and the pure water introducing pipe 60 is provided with an opening / closing valve 62 and a flow rate control mechanism 64 such as a mass flow controller. A pure water source 66 for supplying pure water is connected. Further, a carrier gas introducing pipe 68 is connected to one end of the vapor generating unit 54, and an inert gas such as N is supplied to the introducing pipe 68 via an opening / closing valve 70 and a flow rate control mechanism 72 such as a mass flow controller.
N ₂ gas source 74 that stores the carrier gas consisting of ₂ gas
Are connected. This N ₂ gas is also used as an inert gas for gas purging.

Further, the carrier gas introducing pipe 68 is provided with
A gas heating unit 76 for heating the N ₂ gas to a predetermined temperature, for example, about 200 ° C. is provided so as to preheat the carrier gas. The gas heating unit 76 is configured such that a filter is housed in a container 76A made of stainless steel or quartz whose surface is treated so that impurities do not leak out, and a heating unit 76B is provided around the container 76A. As described above, the carrier gas introduced into the steam generating section 54 is preheated. Further, an opening / closing valve 78 is provided in the water vapor supply passage 56, and a discharge pipe 82 having an opening / closing valve 80 in the middle is branched at a position in the vicinity of the upstream side of the opening / closing valve 78. The water in the steam generating part 54 can be replaced with nitrogen gas.

Next, the steam generating section 54, which is a feature of the present invention,
This will be described in detail with reference to FIGS. 2 to 4. First, the steam generating portion 54 has a heat-resistant container 84 having a so-called double-tube structure, which is formed into a hollow cylindrical body having a ring-shaped cross section, and is closed at both ends to form an annular flow path. ing. The hollow portion at the center of the container 84 is configured as a heater housing hole 88 for housing the lamp heater portion 86 as shown in FIG. Then, a long, cylindrical lamp heater portion 86 as shown in FIG. 4 is inserted and installed in the heater accommodating hole 88. In this embodiment, the lamp heater portion 86 has a diameter of 10 mm and a length of 2 mm.
A halogen lamp of about 50 mm is used and its output is about 1000 watts. As the material of the heat resistant container 84, a material that is an infrared transparent material and has high heat resistance as described above, for example, high-purity quartz is used.

Inside the heat-resistant container 84 is housed a hollow cylindrical filter 92 formed by collecting and sintering a large number of quartz beads 90 having a diameter of about 2 mm, and the filter 92 is provided on the front end side thereof. Is formed with a hollow ring-shaped introduction header 94 that efficiently diffuses the introduced carrier gas, and a hollow ring-shaped discharge header 96 that efficiently collects generated vapor is formed on the rear end side. Is formed. On one end wall of the heat-resistant container 84 on the introduction header 94 side,
A carrier gas introducing port 98 is formed, and the carrier gas introducing pipe 68 (see FIG. 1) is connected to the introducing port 98 to introduce the carrier gas into the inside.
Further, a steam discharge port 100 for discharging the steam generated inside is formed on the other end wall of the discharge side header 96 of the container 84, and the steam supply passage 56 is connected to the discharge port 100. Further, a pure water introduction port 102 is formed on the side wall of the container on the side of the carrier gas introduction port 98, and the pure water introduction pipe 64 is connected to this so that pure water can be supplied into the container. . Further, the filter 92 facing the pure water introducing port 102 is provided with an introducing header 104 in a concave shape so as to promote introduction and diffusion of pure water.

On the outer side of the heat-resistant container 84, a reflector 106 formed by coating the outer peripheral surface of the container with gold plating, silver plating, aluminum plating or the like is formed, and has passed through the container 84. Infrared again,
It is designed to reflect heat to the inside of the container to improve thermal efficiency. The reflector 106 is not limited to such a metal coating film, and may be any material or shape as long as it can reflect infrared rays. Further, instead of such a coating film as the reflector, a cylindrical reflector may be provided as a separate body. And
A cylindrical heat insulating layer 108 is arranged on the outer periphery of the heat-resistant container 84 so as to cover the entire heat-resistant container 84, so that the inside of the container 84 is kept warm and does not adversely affect the outside. .

The length of the steam generating portion 54 thus constructed is set to about 210 mm and the diameter thereof is set to about 44 mm, and the diameter of the heater housing hole 88 is set to about 14 mm. As described above, the lamp heater portion 86 having a diameter of about 10 mm is inserted and housed therein. Electric power is supplied to the lamp heater unit 86 from the heater power supply unit 114. And
A thermocouple 110 for detecting the temperature of the heat resistant container 84 is arranged in the heater housing hole 88, and the detected value is input to the temperature control unit 112 including, for example, a microcomputer. Further, the flow rate control mechanism 60 provided in the pure water introduction pipe 60 changes the flow rate of pure water as needed in accordance with a control command from a host computer (not shown), but the temperature control unit 112 uses the thermocouple 110. The electric power supplied to the lamp heater unit 86 is constantly controlled via the heater power supply unit 114 so that the container detection temperature becomes, for example, 250 ° C. at the maximum.

Next, the operation of the oxidation treatment apparatus constructed as above will be described. First, the opening / closing valve 44 of the pressure reducing pipe 38,
Opening valves 70, 7 for the gas introducing pipe 68 and the steam supply passage 56
8 is open and the other on-off valves 48, 62 and 80 are closed, and the reaction is performed while supplying nitrogen gas from the nitrogen gas source 74 into the reaction tube 14 of the processing furnace 12 through the carrier gas introduction tube 68. The inside of the reaction tube 14 is replaced with nitrogen gas by exhausting the inside of the tube 14 through the decompression tube 38 and the decompression pump 36. After replacement, the lid 16 is opened to open the semiconductor wafer W.
The wafer boat 18 supporting the above is inserted into the reaction tube 14 together with the heat insulation cylinder 20. Next, the pressure in the reaction tube 14 is controlled by the controller 54 while continuing to supply the nitrogen gas.
After decompressing the inside to a predetermined pressure, for example 400 Torr,
While maintaining this pressure, the on-off valve 62 is opened and pure water is supplied to the steam generating portion 54 to vaporize it, and the generated steam is supplied into the reaction tube 14 to perform the oxidation treatment.

When the opening / closing valve 62 is opened, pure water is introduced from the pure water source 66 into the heat resistant container 84 of the steam generating section 54 through the flow rate control mechanism 64 and the pure water introducing pipe 60, and at the same time, the carrier The carrier gas is introduced from the gas introduction pipe 68 through the introduction port 98 from one end side of the container. The pure water introduced into the container 84 is heated and boiled into steam by the radiant heat of infrared rays from the lamp heater 86 arranged in the center of the container in the process of passing through the filter 92 together with the carrier gas, and the steam becomes the carrier. The steam supply passage 56 and the steam introducing pipe 30 are accompanied by the nitrogen gas which is a gas.
Is supplied to the inside of the reaction tube 14 via, and contributes to the oxidation process of the semiconductor wafer W in the reaction tube 14. The amount of water vapor supplied into the reaction tube 14 is determined by the pure water source 66 and the N ₂ gas source 74.
It is controlled by the flow rate control mechanisms 64 and 72.

When steam is generated in the steam generator 54, infrared rays from the lamp heater 86 are transmitted through the inner wall of the heat-resistant container 86 made of quartz and are radiated to the pure water flowing between the filters 92. Pure water is heated and vaporized. Therefore, unlike the heating by heat conduction of the resistance heater of the conventional device, the amount of heat absorbed in the quartz container is very small, the amount of heat absorbed in the quartz container is very small, and steam can be efficiently generated. Yes, and thus a large amount of water vapor can be obtained. Moreover, since this container is made of high-purity quartz, it is possible to suppress the occurrence of metal contamination unlike the conventional apparatus made of stainless steel, for example.

In addition, the infrared rays which have passed through the inside of the container from the center of the container to the outside in the radial direction are heat-resistant containers 84.
It is reflected by the reflector 106 formed on the outer wall surface of, for example, silver coating, and returns to the inside of the container again to contribute to the heating and vaporization of pure water. Therefore, in combination with the above reason, the heating efficiency of pure water can be significantly improved, and more steam can be obtained. The amount of water vapor to be supplied also differs depending on the number of processed semiconductor wafers W or processing conditions, and the supply amount of pure water at that time is controlled by the flow rate control mechanism 64. The temperature of the lamp heater portion 86 or the heat resistant container 84 is constantly kept at the thermocouple 11
The temperature control unit 112 controls the electric power supplied to the lamp heater unit 86 via the heater power supply unit 114 so that the temperature is constantly maintained at 250 ° C., for example. As a result, the amount of steam generated can be stabilized and supplied.

Here, the lamp heater 86 is not limited to a halogen lamp, and any lamp can be used as long as it generates a large amount of infrared rays, for example, a xenon lamp or the like can be used. In this way
When the oxidation process is completed, the supply of pure water is stopped in order to stop the supply of water vapor, and the supply of nitrogen gas is continued, and the inside of the steam generation part 54 and the reaction tube 14 are
Alternatively, the pure water and water vapor remaining in the piping system are purged, and the inside of the reaction tube 14 is replaced with nitrogen gas. Next, vacuum pump 3
6 is stopped, the inside of the reaction tube 14 is returned to normal pressure, and the processed wafer W is carried out from this.

In the above embodiment, the lamp heater portion 86 is arranged at the center of the heat resistant container 84 along the axis thereof, but the present invention is not limited to this, and is shown in, for example, FIGS. 5 and 6. As described above, the lamp heater portion 86 may be provided along the outer peripheral wall of the heat resistant container 84. That is, in this embodiment, as the heat-resistant container 54, a cylindrical cylindrical container made of, for example, an infrared transmitting material, such as quartz, having the same structure as described in FIG. 7 is used. In addition, a large number of ring-shaped lamp heaters 86 made of, for example, halogen lamps are arranged at equal pitches. In this case,
Since the reflector cannot be provided on the outer peripheral surface of the container 54, the cylindrical heat insulating layer 10 covering the outside of the container 54.
A reflector 106 made of a coating film of gold, silver, aluminum, or the like may be provided along the inner wall surface of 8, or a cylindrical reflector 106 may be provided separately from the heat insulating layer 108.

Even in the case of such a structure, as in the previous embodiment, since the pure water is heated by the radiant heat from the lamp heater portion 86, a large amount of water vapor can be efficiently generated. It is possible, and the problem of metal contamination does not occur. In addition, in the embodiment described above, the case where N ₂ gas is used as the carrier gas has been described as an example, but the present invention is not limited to this.
Other inert gases such as r and He or O ₂ gas can also be used, and particularly when O ₂ gas is used, the oxidation treatment can be promoted. Further, the present invention can be applied not only to the case where the oxidation treatment is performed under the reduced pressure state but also to the case where the oxidation treatment is performed under the normal pressure state. Further, the object to be processed is not limited to the semiconductor wafer, and an LCD substrate or the like can be used. Further, the processing furnace is not limited to the vertical furnace as shown in the drawing, but may be applied to a horizontal furnace.

[0026]

As described above, according to the oxidation treatment apparatus and the oxidation treatment method of the present invention, the following excellent operational effects can be exhibited. Since pure water is heated by radiant heat using a heat-resistant container made of an infrared-transparent material and a lamp heater part, the thermal efficiency can be improved without causing the problem of metal contamination, and therefore a large amount of water vapor can be obtained. be able to. This enables efficient oxidation treatment. Also, by providing a reflector that reflects infrared rays, the reflected light can again contribute to heating and vaporization of pure water, and thermal efficiency can be greatly improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an oxidation treatment apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing a steam generator used in the device shown in FIG.

FIG. 3 is a side view of the steam generating unit shown in FIG.

FIG. 4 is a plan view showing a lamp heater unit used in the apparatus shown in FIG.

FIG. 5 is a cross-sectional view showing a steam generating part according to another embodiment of the present invention.

6 is a side view of the steam generating unit shown in FIG.

FIG. 7 is a cross-sectional view showing a conventional steam generating part of an oxidation treatment device.

[Explanation of symbols]

10 Oxidation Treatment Device 12 Processing Furnace 14 Reaction Tube 30 Steam Inlet Tube 54 Steam Generation Section 56 Steam Supply Passage 60 Water Pure Water Inlet Tube 66 Pure Water Source 68 Carrier Gas Inlet Tube 74 N ₂ Gas Source 84 Heat Resistant Container 86 Lamp Heater 88 Heater Storage hole 92 Filter 98 Carrier gas inlet 100 Vapor outlet 102 Pure water inlet 106 Reflector 108 Heat insulating layer 112 Temperature controller 114 Heater power supply W Semiconductor wafer (processing target)

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenji Honma 1-241 Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Tokyo Electron Tohoku Co., Ltd. Sagami Plant (72) Inventor Koichi Orii 1-chome, Marunouchi, Chiyoda-ku, Tokyo No. 1 Nitto Chemical Industry Co., Ltd. (72) Inventor Masahiko Katsura 1-5-1, Marunouchi, Chiyoda-ku, Tokyo Nitto Chemical Industry Co., Ltd. (56) Reference JP-A-7-147276 (JP, A) Kaihei 3-55843 (JP, A) JP 60-154627 (JP, A) JP 6-181177 (JP, A) JP 8-78404 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) H01L 21/31 H01L 21/26 H01L 21/316

Claims (6)

(57) [Claims] 1. A lamp heater part for introducing pure water having a treatment furnace for oxidizing an object to be treated at a high temperature, a heat-resistant container made of an infrared ray transmitting member, and a lamp heater part for generating infrared rays. An oxidation treatment apparatus, comprising: a steam generation section which is turned into steam by radiant heat from the steam generator; and a steam supply passage for supplying the steam generated here to the processing furnace. 2. The heat resistant container houses a filter formed by assembling and sintering heat resistant particles inside, and a wall thereof has a pure water inlet for introducing pure water and a carrier gas. The oxidation treatment apparatus according to claim 1, wherein a carrier gas introduction port for introducing is formed. 3. The heat resistant container is formed as a hollow cylindrical body having a ring-shaped cross section having a heater housing hole for housing the lamp heater portion in a central portion thereof, and infrared rays are provided outside the heat resistant container. The oxidation treatment device according to claim 1 or 2, wherein the oxidation treatment device is configured to be provided with a reflector. 4. The heat-resistant container is formed in a tubular shape, and the lamp heater portion is arranged on the outer periphery of the heat-resistant container, and the outside of the lamp heater portion is covered with a reflector. The oxidation treatment device according to claim 1 or 2. 5. An object to be processed contained in a processing furnace.
In the oxidation treatment method for applying the oxidation treatment, The pure water introduced into the heat resistant container is heated by infrared rays.
And vaporize it, The treatment by introducing the generated steam into the treatment container
To oxidize the object in the furnace at high temperature
An oxidation treatment method characterized by: 6. The pure water flowing in the heat resistant container is
By a filter made by gathering and sintering heat-resistant granules
The oxidation treatment method according to claim 5, wherein the oxidation treatment is performed.
Law.