JP3753985B2 - Low pressure vapor phase growth equipment - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a reduced pressure vapor phase growth apparatus, and more particularly to a vertical reduced pressure vapor phase growth apparatus for manufacturing a semiconductor device.
[0002]
[Prior art]
A longitudinal sectional view of a conventional vertical vacuum vapor phase growth apparatus is shown in FIG. An outer tube 1 and an inner tube 2 as reaction tubes are provided on a manifold 4, and a heater 3 is provided around the reaction vessel in order to keep the inside of the reaction tube at a predetermined temperature.
[0003]
In the apparatus of FIG. 1, a large number of semiconductor wafers 9 (hereinafter referred to as wafers) are held in a shelf shape on a wafer boat 8 and carried into a reaction tube. The wafer boat 8 has a heat insulating cylinder 7 attached below it. The manifold 4 is generally fixed. The heat insulating cylinder 7 and the boat 8 are placed on the boat elevator 12, and the heat insulating cylinder 7 and the boat 8 are inserted into the reaction vessel from the boat hole provided at the center of the lower part of the manifold 4 by the boat elevator 12. .
[0004]
Then, the inside of the reaction tube is evacuated from between the outer tube 1 and the inner tube 2 by the exhaust tube 6 provided in the manifold 4 and maintained in a predetermined reduced pressure atmosphere, while the raw material gas introduction rod 5 provided in the inner tube 2 is maintained. The processing gas was introduced from the lower side of the inner tube 2 through the. Then, the wafer 9 is controlled to a predetermined processing temperature, for example, 600 ° C. by heating by the heater 3, and a thin film, for example, a polysilicon film is formed on the wafer 9 by chemical vapor reaction of the processing gas.
[0005]
[Problems to be solved by the invention]
In the conventional reduced pressure vapor phase growth apparatus described above, the tip of the source gas introduction pipe 5 comes close to the side surface of the heat insulation cylinder 7 in a state where the boat 8 and the heat insulation cylinder 7 are accommodated in the reaction tube. For this reason, the raw material gas flows directly or indirectly to the heat insulating cylinder 7, and a reaction product is formed on the surface of the heat insulating cylinder 7. When the boat elevator 12 is loaded (attached to the apparatus) and unloaded (removed from the apparatus) with the boat 8 attached with the thermal insulation cylinder 7, the thermal insulation cylinder 7 inevitably goes inside and outside the reaction tube. Therefore, the heat insulating cylinder receives a temperature difference between room temperature (about 20 to 30 ° C.) and the reaction processing temperature (about 500 to 800 ° C.). At this time, thermal stress is generated due to the difference in thermal expansion coefficient between the reaction product (Si ₃ N ₄ , PolySi, etc.) adhering to the surface of the heat insulation cylinder 7 and the material (quartz, SiC, etc.) of the heat insulation cylinder 7. There was a problem that the reaction product attached to the surface peeled off from the surface of the heat insulating cylinder 7 and caused particles (dust). The particles adhere to the surface of the wafer 9 and cause a patterning failure.
[0006]
[Means for Solving the Problems]
The present invention provides a vertical decompression vapor phase growth apparatus in which a cover is provided in a reaction tube between an outlet of a raw material gas introduction tube and a heat retaining tube so that the raw material gas is not directly injected into the heat retaining tube, and a boat is loaded and unloaded. It is characterized in that it is installed in a place where the cover is held in the reaction tube even when it is attached (detached).
[0007]
This configuration reduces the amount of product that adheres to the insulation tube, so that the amount of product that detaches from the insulation tube is reduced due to the stress caused by temperature fluctuations during loading and unloading. Can be suppressed. Thereby, the quality of the semiconductor device can be stabilized and the manufacturing yield can be improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.
[0009]
In FIG. 1, an outer tube 1 and an inner tube 2 constituting a reaction tank are respectively mounted on a manifold 4. A space is arranged between the inner tube 2 and the outer tube 1, and 1 and 2 are attached in an airtight manner. A boat 8 for placing a plurality of wafers 9 as semiconductor substrates on a shelf is placed almost at the center of the inner tube 2. The boat 8 is inserted into the reaction vessel from the outside of the reaction vessel through a hole provided in the center of the bottom of the manifold 4 by the boat elevator 12 via the heat insulating cylinder 7. The heat insulating cylinder 7 is made of quartz which is chemically stable and has a heat insulating effect. Moreover, the heat insulation cylinder 7 has a spacer effect.
[0010]
The wafer 9 placed on the boat 8 is heated to a predetermined temperature by the heater 3 disposed outside the reaction vessel. A raw material gas introduction rod 5 for introducing a gas for vapor phase growth on the surface of the wafer 8 into the reaction chamber is attached to the manifold 4. Furthermore, an exhaust pipe 6 for discharging the gas in the reaction tank is attached to the manifold 4. The source gas introduction rod 5 introduces the source gas directly into the inner tube 2, and the exhaust pipe 6 exhausts the exhaust gas from the space formed by the inner tube 2 and the outer tube 1. Each is attached.
[0011]
A heat insulating cylinder cover 10 is provided on the manifold 4 so as to block a space between the outlet of the raw material gas introduction pipe 5 and the heat insulating cylinder 7 so that the raw material gas is not directly jetted to the heat insulating cylinder 7 holding the boat 8. As shown in FIG. 2, the heat insulating cylinder cover 10 surrounds the heat insulating cylinder 7 so that the sprayed raw material gas does not directly contact the heat insulating cylinder 7 and prevents the raw material gas from entering the heat insulating cylinder 7 as much as possible. Is provided. Even during loading and unloading when the boat 8 is installed in the reaction vessel or removed from the reaction vessel by the boat elevator 12, the heat insulating cylinder cover 10 is installed on the manifold 4, so Will be retained. Further, the heat insulating cylinder cover 10 is installed at a position where the sprayed source gas does not directly contact the heat insulating cylinder 7.
[0012]
FIG. 3 is a view showing the heat insulating cover 10 of the second embodiment of the present invention, and is a cross-sectional view of the heat insulating cylinder 7 portion. In order to prevent the sprayed raw material gas from coming into direct contact with the heat retaining tube 7, the heat retaining tube cover 10 is provided only in the vicinity of the outlet of the raw material gas introduction pipe. Also in this case, the effect of the present invention can be sufficiently obtained.
[0013]
The leading end of the source gas introduction into the reaction vessel of the source gas introduction vessel 5 is directed upward so as to be parallel to the axis of the reaction vessel so as not to blow directly onto the heat insulating cylinder 10. The raw material gas is introduced from the lower part of the inner tube 2, flows upward in the inner tube 2, undergoes a gas phase reaction on the upper surface 9, and flows downward in the space between the inner tube 2 and the outer tube 2, As exhaust gas, it is exhausted from the exhaust pipe 6.
[0014]
When the wafer 9 is placed and heated in the reaction chamber and the source gas is introduced from the source gas introduction chamber 5 into the reaction chamber, the source gas may be exposed to the source gas by the thermal insulation tube cover 10. Less. And, almost no reaction product (vapor phase growth material) is generated on the surface of the heat insulating cylinder 7. In the conventional example, most of the reaction product generated in the heat insulating cylinder 7 is formed on the surface of the heat insulating cylinder cover 10 on the side of the raw material gas introduction rod 5. Even if the thermal insulation cylinder 7 is subjected to thermal shock and thermal stress due to loading and unloading of the boat 8, almost no vapor phase growth material is formed on the surface, so that the reaction product falls off the surface of the thermal insulation cylinder 7. Is reduced. Therefore, the generation of particles is reduced.
[0015]
Note that the vapor phase growth material formed on the surface of the heat insulation tube cover 10 on the side of the raw material gas introduction rod 5 has a large heat because the heat insulation tube cover is installed in the heat insulation rod during loading and unloading of the boat 8. No impact or thermal stress. For this reason, the reaction product does not fall off from the heat insulating cylinder cover 10.
[0016]
FIG. 4 is a longitudinal sectional view of a third embodiment of the present invention. There is a method in which a cleaning gas such as ClF ₃ gas is introduced into the reaction tube from the cleaning gas introduction rod 11 to remove a product adhering to the reaction tube. When the surface from which the raw material gas is ejected to the heat insulation tube cover 10 is the surface of the heat insulation tube cover 10, the surface from which the cleaning gas is ejected to the heat insulation tube cover 10 is ejected to the surface of the heat insulation tube cover 10. By installing the jet port of the cleaning gas introduction pipe 11 in the inner tube 2, it is possible to remove products mainly attached to the surface of the heat insulating cylinder cover 10, the inner tube 2, the outer tube 1, the boat 8, and the like. .
[0017]
FIG. 5 is a longitudinal sectional view of a fourth embodiment of the present invention. When the surface on which the source gas is ejected to the heat insulation cylinder cover 10 is the surface of the heat insulation cylinder cover 10, the surface on which the cleaning gas is ejected to the heat insulation cylinder cover 10 is ejected to the back surface of the heat insulation cylinder cover 10. By installing the ejection port of the cleaning gas introduction pipe 11, it is possible to mainly remove the products attached to the back surface of the heat insulation cylinder cover 10 and the heat insulation cylinder 7, the inner tube 2, the outer tube 1, the boat 8 and the like.
[0018]
【The invention's effect】
As described above, the present invention provides a cover in the space between the raw material gas introduction pipe and the thermal insulation cylinder so that the raw material gas does not directly contact the thermal insulation cylinder holding the boat, and when the boat is loaded and unloaded, Since the product that adheres to the heat insulation cylinder is reduced because the cover is held in the reaction tube, the product is detached from the heat insulation cylinder due to the stress caused by temperature fluctuations during loading and unloading (desorption) of the boat. Since the amount of objects is also reduced, the generation of particles can be suppressed. This has the effect of stabilizing the quality of the semiconductor device and improving the manufacturing yield.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a vertical reduced pressure vapor phase growth apparatus according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the first embodiment of FIG.
FIG. 3 is a cross-sectional view of a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a third embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a fourth embodiment of the present invention.
FIG. 6 is a longitudinal sectional view of a conventional vertical reduced pressure vapor phase growth apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Heater 4 Manifold 5 Raw material gas introduction pipe 6 Exhaust pipe 7 Thermal insulation cylinder 8 Boat 9 Wafer 10 Thermal insulation cylinder cover 11 Cleaning gas introduction pipe

Claims (1)

A vertical reaction tube consisting of an outer tube and an inner tube;
A manifold for holding the lower end of the reaction tube;
A boat housed in the reaction tube and on which a semiconductor wafer is placed;
A thermal insulation cylinder accommodated in the reaction tube and supporting the boat;
An exhaust pipe for exhausting from the space formed gas in said reaction tube in the inner tube and the outer tube,
A raw material gas introduction pipe disposed in the manifold, with a raw material gas introduction tip extending into the reaction tube, and directing the raw material gas into the reaction pipe ;
Arranged in the manifold, held in the reaction tube when the boat is loaded and unloaded, and blocks the space between the jet port of the source gas introduction pipe and the heat retaining tube when the boat is loaded, to the heat retaining tube A low pressure vapor phase growth apparatus comprising a heat insulating cylinder cover that surrounds the heat insulating cylinder so as to reduce the amount of the raw material gas flowing around and is opened only at the upper side so that the blown raw material gas flows above the reaction tube .

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