JPH08288232A - Gas control jig of semiconductor heat treatment furnace - Google Patents

Abstract

PURPOSE: To form a uniform gas flow over the whole inside-wall circumference of a core tube by a method wherein a gas control jig is arranged and installed to be freely detachable in such a way that it is concentric with the core tube and that a prescribed gap is formed between the outer circumference of the gas control jig and the inside wall of the core tube. CONSTITUTION: A boat 2 in which a plurality of semiconductor wafers 1 have been set is placed inside a core tube 3. A thick cylindrical-body gas control jig 4 is placed on the upper part of the boat 2 so as to be concentric with the core tube 3 and the wafers 1. In addition, a treatment-gas introduction port 5 is formed in the center at the upper part of the core tube 3 and a treatment-gas discharge port 6 is formed at the lower part. In this case, the diameter and the thickness of the gas control jig 4 are selected properly in such a way that the gas control jig 4 and the whole inside-wall face of the core tube 3 form a prescribed interval and that the upper-end plane of the gas control jig 4 and the lower-end part of the treatment-gas introduction port 5 become a prescribed distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment furnace gas control jig.
Controls the flow of processing gas when heat-treating a semiconductor substrate,
The present invention relates to a semiconductor heat treatment furnace gas control jig capable of efficiently and uniformly heat-treating a semiconductor substrate surface state.

[0002]

2. Description of the Related Art Conventionally, a method has been used in which a semiconductor substrate such as a silicon wafer is set in a boat or the like, charged into a core tube, and a processing gas is introduced and the temperature is raised to heat it. Conventionally, as a heat treatment furnace for these heat treatments,
Many horizontal heat treatment furnaces are used in which a plurality of semiconductor substrates are arranged vertically in the horizontal direction, and in order to increase the number of substrates that can be processed at one time, various ideas have been proposed to obtain a soaking zone length as long as possible in the furnace. ing. For example, Japanese Patent Laid-Open No. 54-
Japanese Patent Laid-Open No. 110458 discloses that in a horizontal heat treatment furnace, a buffer made of quartz glass or the like is provided on the gas inlet side to reduce the flow rate of the gas to be introduced so that the supply gas is warmed and supplied as a gentle flow into the furnace. A heat treatment furnace having a structure has been proposed. Further, Japanese Utility Model Application Laid-Open No. 62-134232 proposes a horizontal heat treatment furnace in which a buffer plate having a plurality of through holes is provided on the gas inlet side to control the gas flow. In recent years, in place of the conventional horizontal heat treatment furnace, one of the core tubes is surrounded by a heat insulating material, so there is an advantage that the soaking zone length can be lengthened compared to the size of the entire furnace,
A vertical heat treatment furnace in which a plurality of semiconductor substrates are arranged horizontally in a vertical direction is used for heat treatment of the semiconductor substrates.
In heat treatment using a vertical heat treatment furnace, conventionally, a plurality of dummy wafers are set in a boat and heat treated so that the introduced gas does not directly impinge on the substrate to be treated (see FIG. 2).

[0003]

However, in the conventional method of using the dummy wafer in the vertical heat treatment furnace, the flow thereof is not controlled until the introduced processing gas hits the top plate of the wafer boat or the dummy wafer. Even after hitting them, it became turbulent, and it was difficult to obtain a uniform flow such as forming a vortex at the corner of the core tube on the side where the gas introduction tube was connected. Therefore, there is a problem in that the wafers set on the upper portion of the boat and the wafers set on the lower portion have different surface states such as surface roughness and diffusion concentration, and the wafers cannot be uniformly obtained by heat treatment. Further, since the flow of the processing gas introduced into the furnace core tube is not uniform, even when the processing gas descends to the portion where the wafer to be processed is set, at the same height, for example, the flow velocity on the right side of the wafer, There is also a problem that a uniform wafer cannot be obtained because the surface condition is different even within the surface of one wafer, for example, the flow velocity on the left side is different.

Further, when the method of installing a buffer plate having a plurality of holes proposed in the above-mentioned Japanese Patent Laid-Open No. 54-110458 in a conventional horizontal heat treatment furnace is applied to a vertical heat treatment furnace, after all, a central portion is eventually obtained. In the vertical furnace, the gas emitted from the holes in the vicinity hits the top plate or the wafer of the boat and eventually forms a turbulent flow. Further, as in another embodiment of the above proposal, when the gas is uniformly discharged from the outer periphery of the buffer plate, the wafer is not installed concentrically with the core tube, and the heat from the heater in the furnace is not provided. Due to the convection, the uniform gas flow cannot be formed over the entire outer circumference of the wafer. Further, since the buffer plate is installed at a position apart from the boat, the gas passing through the buffer plate is
In the end, it is difficult to obtain a uniform gas flow by hitting the surface of the wafer arranged at the end and forming a turbulent flow. SUMMARY OF THE INVENTION The present invention has an object to uniformly heat the surface states of a plurality of wafers in the heat treatment of a semiconductor substrate as described above, in view of the current situation that the heat treatment of the substrate cannot be performed uniformly due to the problem of processing gas flow. To do. For the above-mentioned purpose, the inventors diligently studied the flow state of the heat treatment gas in both the horizontal and vertical heat treatment furnaces, and as a result, by disposing a predetermined gas control jig, a uniform gas flow in the furnace was achieved. The inventors have found that the following can be obtained and completed the present invention.

[0005]

According to the present invention, a processing gas introduction port side end of a furnace core tube is set in a furnace core tube of a heat treatment furnace in which a plurality of semiconductor substrates are set in a boat, charged and heat treated. Is disposed concentrically with the furnace core tube and has a predetermined gap with the inner wall of the furnace core tube in a detachable manner, has a larger diameter than the semiconductor substrate, and is introduced into the furnace core tube. There is provided a semiconductor heat treatment furnace gas control jig, characterized in that a uniform heat treatment is maintained to allow a flow and exhaust. In the semiconductor heat treatment furnace gas control jig of the present invention, the gap between the inner wall of the furnace core tube and the outer peripheral portion is 5 to 100 mm, and the gas introduction port of the furnace core tube and the tip portion closest to the gas introduction port are provided. Preferably has a distance of 5 to 100 mm. The shape of the gas control jig is preferably a disc, a cylinder or a dish, and the gas control jig is
It is preferably composed of a single member or a combination of two or more members. Furthermore, it is preferable that the member is formed of CVD-SiC-coated Si-SiC, Si, or quartz glass. In addition, in the present invention, the uniform flow in the furnace core tube means that a laminar flow is maintained and the fluid flows without generating turbulent flow or vortex.

[0006]

The present invention is configured as described above, and the gas control jig has a diameter larger than that of the semiconductor substrate set in the boat.
In the heat treatment furnace, it can be installed at the end of the process gas inlet side concentrically with the furnace core tube and detachably so that the gap between the outer periphery of the gas control jig and the inner wall of the furnace core tube is predetermined. Since it can be introduced through the gap, a uniform gas flow can be made over the entire circumference of the inner wall of the furnace core tube, that is, it can be guided to the furnace core tube outlet while maintaining a substantially laminar flow state, The semiconductor substrate surface can be uniformly heat-treated. Further, the gas control jig of the present invention can be arranged between the gas introduction port of the processing gas into the furnace core tube and the heat-treated semiconductor substrate, and has a larger diameter than the semiconductor substrate, so that the rectified gas flow It is possible to prevent a turbulent flow caused by re-joining with each other and hitting the semiconductor substrate to be processed, and it is possible to further improve the homogenization of the gas flow. The semiconductor substrate heat treatment gas control jig of the present invention may have a simple shape such as a disc, a cylinder, or a dish, and may be a single body or a combination of two or more members.
It can be easily arranged on the wafer boat in the conventionally used furnace core tube or on the end of the boat. Further, even if the substrate set at the end of the boat is heat-treated under substantially the same gas conditions as the substrate set at the center, it is possible to omit the conventionally required dummy wafer. The furnace can be used efficiently and productivity is improved.

In the present invention, the gas control jig arranged at the end of the furnace core tube on the gas inlet side has a diameter larger than that of the semiconductor substrate to be heat-treated set in the boat, and the entire circumference of the inner wall of the furnace core tube. It may be anything that can be arranged concentrically so as to have a predetermined gap. Usually, a disc, a cylindrical body, a columnar body, and a dish-like shape can be used according to the circular cross-sectional shape of a general furnace core tube, and a single body may be used, or two or more members depending on the arrangement conditions. Can be arranged in combination. The gap between the inner wall of the furnace core tube and the outer peripheral portion of the gas control jig is usually 5 to 10
It is 0 mm, preferably 20 to 80 mm. If the gap is within the above range, the introduced processing gas passes through the uniform gap over the entire circumference thereof and flows down along the inner wall of the furnace core tube, so that a uniform gas flow is formed over the entire circumference of the furnace core tube. Can be made. In this case, the gas control jig has a larger diameter than the semiconductor substrate, and the processing gas does not directly collide with the semiconductor substrate.
Further, the gas control jig of the present invention is disposed on the gas inlet side, and has a predetermined distance, preferably 5 to 100 mm, more preferably 20 to 80 mm, so that the processing gas flow does not drift in the distance from the gas inlet. By so doing, it is possible to evenly distribute the processing gas in the direction of the gap formed by the inner wall of the furnace core tube and the gas control jig without biasing the flow of the processing gas.

As described above, the gas control jig of the present invention, which is arranged in the furnace core tube of the heat treatment furnace for semiconductor substrates, basically does not release a substance or gas that contaminates the semiconductor, withstands high temperatures, and to some extent. There is no particular limitation as long as the material has the strength of. Preferably, silicon-impregnated SiC (CVD-SiC coating S
i-SiC), silicon (Si), quartz glass, or the like. In a heat treatment furnace for performing heat treatment in a reducing atmosphere such as hydrogen, the boat is made of Si,
It is preferable that the gas control jig is also made of Si because a high quality wafer can be manufactured. Also, use a gas control jig with 100 bubbles per cm ³ of bubbles with a diameter of 0.1 mm or more.
When quartz glass containing 0 or more or ceramics having a relative density of 30% or less and having open pores is used, a gas rectifying effect can be obtained, and a gas flow rate can be made substantially uniform over the whole, which is preferable.

The gas control jig of the present invention can be arranged in either a vertical type or a horizontal type of the heat treatment furnace. In a vertical heat treatment furnace, the furnace core tube is usually arranged concentrically with the peripheral portion projecting from the periphery of the boat top plate below the gas introduction port arranged in the upper part toward the inner wall of the furnace core tube. Further, in the horizontal heat treatment furnace, the inner wall of the furnace core tube has a predetermined distance, is larger than the diameter of the semiconductor substrate set in the boat, and is concentric with the diameter of the furnace core tube. It can be arranged by utilizing the end of the boat so that a uniform gap is formed with the entire circumference. In this case as well, the processing gas is evenly distributed in the lateral direction, the surface of each semiconductor substrate is processed with a uniform gas flow, and a uniformly heat-treated substrate can be obtained. Further, since the gas control jig of the present invention controls the introduced processing gas to guide it over the entire circumference of the furnace core tube and to distribute the gas in a uniform flow, uniform processing is performed regardless of the position in the furnace core tube. The gas circulates substantially uniformly from the outer peripheral portion of each semiconductor substrate to be processed, and it is possible to process the surface roughness of the semiconductor substrate in a uniform state. Further, since the impurities contained in the processing gas are trapped and accumulated in the gas control jig, there is also an effect of reducing the impurity contamination of the semiconductor substrate. Moreover, the gas control jig of the present invention can be replaced if necessary, and the best gas control jig can be appropriately selected and used according to the processing conditions.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. However, the present invention is not limited to the following examples. FIG. 1 is a sectional explanatory view (a) and a plan explanatory view (b) showing an example in which an embodiment of a semiconductor heat treatment furnace gas control jig of the present invention is arranged in a vertical heat treatment furnace. In FIG. 1, a boat 2 having a plurality of semiconductor wafers 1 set therein is loaded in a core tube 3. Boat 2
A thick cylindrical gas control jig 4 made of Si-SiC and coated with CVD-SiC is placed concentrically with the furnace tube 3 and the wafer 1 on the upper part of the. A processing gas inlet 5 is provided at the center of the upper part of the core tube 3 and a processing gas outlet 6 is provided at the bottom thereof. In this case, the gas control jig 4 and the entire inner wall surface of the core tube 3 form a predetermined space (d), and
The diameter and thickness of the gas control jig 4 can be appropriately selected and set so that the upper end plane of the gas control jig 4 and the lower end of the processing gas introduction port 5 have a predetermined distance (H).

Example 1 Eighty silicon wafers having a diameter of 150 mm were set in a Si boat having a total length of 800 mm, and the outer shape 22 was set on the top of the boat.
A cylindrical body made of Si having a diameter of 0 mm, an inner diameter of 180 mm and a height of 30 mm is arranged, and then the core tube made of quartz glass having an inner diameter of 250 mm and a height of 1000 mm and having a gas introduction port 5 in the upper central portion thereof is charged, A heat treatment furnace was constructed in the same manner as in No. 1.
In this case, the gap (d) had a width of 15 mm over the entire circumference, and the distance (H) was 25 mm. In this heat treatment, hydrogen gas was introduced as a treatment gas at a flow rate of 7.5 liter / min and heat treatment was performed at 1200 ° C. for 60 minutes.
The surface roughness state (haze level) of the processed wafer was measured using a light scattering measuring device. As a result, it was confirmed that the haze level was 0.6 to 0.8 ppm on average, and the surface condition was remarkably good as compared with 0.9 to 1.2 ppm in which the gas control jig was not arranged. .

[0012]

The gas control jig of the present invention is used by being installed in a heat treatment furnace for semiconductor substrates, and the entire outer peripheral portion and the inner wall of the core tube can be set to a predetermined size by appropriately selecting it according to the heat treatment conditions. In a gap, and can be maintained a predetermined distance from the gas inlet, the process gas is evenly guided to the entire circumference of the furnace core tube,
In addition, the wafer can be uniformly distributed from the gap along the inner wall, the surface of each of the plurality of semiconductor substrates to be processed arranged in the furnace core tube is uniformly processed, and a wafer having a uniform and good surface condition is obtained. In addition, the surface condition of one wafer can be made uniform. Further, since the dummy wafer can be omitted, the soaking length of the furnace can be effectively utilized, which contributes to the improvement of wafer productivity.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view (a) and a plan explanatory view (b) showing an example in which an embodiment of a semiconductor heat treatment furnace gas control jig of the present invention is arranged in a vertical heat treatment furnace.

FIG. 2 is a cross-sectional explanatory view of an example of a conventional heat treatment furnace.

[Explanation of symbols]

 d Gap between gas control jig and inner wall of furnace core tube H Distance between gas control jig and processing gas introduction port 1 Wafer 2 Boat 3 Reactor core tube 4 Gas control jig 5 Processing gas introduction port 6 Processing gas discharge port

Claims (5)

[Claims] 1. A furnace core tube of a heat treatment furnace in which a plurality of semiconductor substrates are set in a boat and loaded and heat-treated, and at the end of the furnace core tube on the side of the processing gas introduction port, which is concentric with the furnace core tube. It is detachably arranged with a predetermined gap with the inner wall of the furnace core tube, has a diameter larger than that of the semiconductor substrate, and controls the processing gas flow introduced into the furnace core tube to maintain a uniform flow. A semiconductor heat treatment furnace gas control jig characterized in that it can be circulated and exhausted. 2. The gap between the inner wall of the furnace core tube and the outer wall of the inner wall of the furnace core tube is 5 to 100 mm, and the gas introduction port and the gas introduction port of the furnace core tube are The distance from the closest tip to the tip is 5 to 100 mm.
The semiconductor heat treatment furnace gas control jig described. 3. The semiconductor heat treatment furnace gas control jig according to claim 1, wherein the shape is a disk, a cylinder or a dish. 4. The semiconductor heat treatment furnace gas control jig according to claim 1, 2 or 3, which is composed of a single member or a combination of two or more members. 5. The semiconductor heat treatment furnace gas control jig according to claim 1, wherein the member is formed of CVD-SiC coated Si-SiC, Si or quartz glass.