JP4620288B2 - Batch heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a batch-type heat treatment apparatus for use in film formation of an object to be processed such as a semiconductor substrate such as a silicon wafer or a glass substrate for LCD, and more particularly to in-plane uniformity of the film thickness on the surface of the object to be processed. The present invention relates to an excellent batch heat treatment apparatus.
[0002]
[Prior art]
In general, in the manufacturing process of semiconductor devices, it is already known that silicon-based thin films such as silicon nitride and silicon oxide films are formed many times on an object to be processed such as a semiconductor substrate because many fine elements need to be formed. Yes. In this case, it is a matter of course that requires some more production efficiency, stabilization of a semiconductor device of the properties of the final product, i.e. in order to obtain the desired electrical properties, the Oite thickness in the film-forming process In-plane uniformity must be improved. This film forming process is performed by a heat treatment apparatus such as a low pressure CVD apparatus. As a processing gas, for example, when forming a silicon nitride film, dichlorosilane and ammonia are used, and when forming a silicon oxide film, TEOS (tetraethoxyorthosilane) or the like is used.
[0003]
Conventionally, for example, a semiconductor processing apparatus as shown in FIG. 5 is used for film formation on the surface of the semiconductor substrate. That is, the semiconductor processing apparatus shown in FIG. 5 includes a heating furnace body 501, a heating apparatus 505 disposed inside the heating furnace body 501, and a semiconductor substrate that is disposed inside the heating apparatus 505 and is a target object. A reaction vessel 502 including a reaction vessel outer tube 503 and a reaction vessel inner tube 504 that can accommodate a wafer boat 506 in which W is aligned and mounted; a manifold 510 that is disposed below the reaction vessel 502 and supports the reaction vessel; and a source gas An exhaust port 515 provided in a gap between the introduction nozzle 513, the reaction vessel outer tube 503 and the reaction vessel inner tube 504 for discharging unreacted residual gas of the raw material gas and generated exhaust gas; A lower lid 511 for sealing the lower opening to keep the inside of the reaction vessel airtight, and a wafer boat 506 fixed to the lower lid 511 And a lifting device 512 and the like for lifting and.
In this semiconductor processing apparatus, the source gas is supplied from the nozzle 513, rises from the bottom to the top inside the reaction vessel 502, reacts on the surface of the semiconductor substrate W, forms a film, and the generated exhaust gas is in the reaction vessel. The gas is exhausted from the system via the exhaust port 515 through the gap between the tube 504 and the reaction vessel outer tube 503.
[0004]
In such a semiconductor processing apparatus, since the source gas passes at a relatively fast flow rate in the periphery of the semiconductor substrate that is the object to be processed, the supply of new source gas is performed quickly and the source gas concentration is high. The deposition rate is relatively fast. On the other hand, in the central portion of the semiconductor substrate, the flow of the raw material gas is relatively stagnation, and the concentration of the raw material gas is lower than that in the peripheral portion. As a result, in the same semiconductor substrate, the film thickness of the film formation in the peripheral portion becomes thicker than that in the central portion, and the in-plane uniformity is impaired.
[0005]
In order to solve such a problem of the semiconductor processing apparatus, the in-plane uniformity of the thin film is improved by passing the flow path of the source gas along the surface of the semiconductor substrate in the vapor phase silicon epitaxial growth apparatus. Has been attempted (see JP-A-4-163912). That is, as can be seen in FIG. 6, a nozzle tube 607 in which a large number of source gas supply ports are formed is arranged in the reaction vessels 601 and 602, and a large number of gas discharge ports 608 are formed on the side surface of the reaction vessel inner tube 602. Thus, the source gas is disposed so as to pass horizontally from the nozzle pipe 607 to the gas outlet 608.
By the way, in this apparatus, many gas exhaust ports 608 must be formed on the side surface of a highly brittle reaction vessel such as quartz glass, and it is difficult to manufacture such a semiconductor processing apparatus.
Further, in this apparatus, a film also grows in the raw material gas supply hole of the nozzle tube 607, and the raw material gas supply hole of the nozzle tube 607 is blocked or causes generation of particles. As a countermeasure, in the above cited example, it is necessary to dispose the nozzle tube 611 exclusively for etching in the vicinity of the nozzle tube 602 to prevent the clogging of the source gas supply holes and the generation of particles, and the apparatus is complicated.
[0006]
[Problems to be solved by the invention]
The present invention realizes a batch-type heat treatment apparatus that can easily improve the in-plane uniformity of the film thickness on the surface of the substrate to be processed without significantly changing the batch-type heat treatment apparatus used conventionally. It is for the purpose.
It is another object of the present invention to realize a batch type heat treatment apparatus that can form a uniform film without blocking the source gas supply holes and without the possibility of generating particles.
[0007]
The present invention of claim 1 includes a heating furnace main body, heating means disposed in the heating furnace main body, a wafer boat accommodated in the heating furnace main body, and an object to be processed placed therein. In a batch-type heat treatment apparatus comprising at least a reaction vessel containing a gas, a nozzle for supplying a raw material gas into the reaction vessel, and an exhaust port for discharging the exhaust gas in the reaction vessel, a film is formed in the reaction vessel. A reaction inhibiting gas supply nozzle having a plurality of holes for supplying a gas that inhibits the reaction is disposed, and in the batch heat treatment apparatus, the ejection direction of the reaction inhibiting gas from the reaction inhibiting gas supply nozzle is to be processed. A batch type heat treatment apparatus characterized by being in a tangential direction of a peripheral part of the body .
[0009]
The present invention of claim 2 is a batch type heat treatment apparatus characterized in that at least two reaction-inhibiting gas supply nozzles are disposed in the reaction vessel.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The batch type heat treatment apparatus of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a batch heat treatment apparatus that can be used in the present invention. That is, the batch-type heat treatment apparatus of the present invention includes a heating furnace body 1 having a ceiling and an opening at the bottom, a heating apparatus 5 such as a resistance heater disposed inside the heating furnace body 1, A reaction vessel 2 is provided inside the heating device 5. The reaction vessel 2 is made of a high-purity heat-resistant material such as quartz glass that is sealed at the top and opened at the bottom, and is composed of a reaction vessel inner tube 4 and a reaction vessel outer tube 3. A manifold 10 is disposed in the lower opening of the reaction vessel 2 to support the reaction vessel 2 and to be sealed using an O-ring or the like. The lower end of the manifold 10 is open, and the lower lid 11 can be sealed in the opening. The reaction chamber 2, the manifold 10, and the lower lid 11 form a reaction chamber that can be kept airtight using an O-ring or the like.
[0011]
In the reaction chamber, a wafer boat 6 on which a plurality of objects to be processed W are arranged and mounted is accommodated. The wafer boat 6 is pivotally supported on the lower lid 11 by a rotary bearing 9 and a rotary shaft 8 using a magnetic fluid or the like, but the heat of the workpiece W heated by the heating device is transferred to the rotary shaft 8. A temperature drop is prevented by the heat insulating cylinder 7 so as not to dissipate via the like.
[0012]
Further, an elevating device 12 is fixed to the lower lid body 11, and the wafer boat 6 can be moved up and down so that the workpieces W can be accommodated and taken out from the batch heat treatment apparatus.
[0013]
In the batch heat treatment apparatus, during processing of the object to be processed W, the rotating shaft 8, the heat insulating cylinder 7 and the wafer boat 6 are rotated by a driving device (not shown) to equalize the temperature of the object to be processed W, and W and the source gas are in uniform contact.
[0014]
A source gas supply nozzle 13 is provided on the side surface of the manifold 10. A plurality of source gas supply nozzles 13 may be arranged when a plurality of source gases are used. The source gas supply nozzle 13 is connected to a source gas cylinder for supplying source materials (not shown), a source gas supply control device, and the like, and source gas is supplied into the reaction chamber from the source gas supply nozzle arranged at the lower part of the reaction chamber. It has come to be.
Further, an exhaust port 15 is provided in the gap between the reaction vessel outer tube 3 and the reaction vessel inner tube 4 for discharging unreacted residual gas of the source gas and exhaust gas generated by the film formation reaction.
The source gas flows in from the lower part of the reaction chamber, flows upward along the wafer boat 6, and passes through the space formed by the opposing surface of the object to be processed placed on the wafer boat. The exhaust gas and the unreacted raw material gas generated as a result of the reaction are brought into contact with the processing body to form a film, and the exhaust pump (not shown) passes through the gap between the reaction vessel inner tube 4 and the reaction vessel outer tube 3. Thus, the gas is discharged from the exhaust port 15 to the outside of the system and processed.
[0015]
In the batch-type heat treatment apparatus, a high concentration of source gas is always supplied in the periphery of the object to be processed, and the reaction is performed, so the film growth rate is fast, but in the center of the object to be processed, Since the supply of the source gas is slow compared to the peripheral portion, the film forming speed is also low, so that the generated film tends to have a thick peripheral portion and a thin central portion.
[0016]
Therefore, in order to prevent such film thickness non-uniformity in the film formation, in the present invention, a reaction inhibiting gas is used to improve the film thickness uniformity. That is, a reaction inhibition gas supply nozzle 14 having a large number of holes for supplying the inhibition gas is disposed in the reaction vessel 2. This reaction-inhibiting gas supply nozzle 14 is inserted into the interior from the manifold 10 and extends along the wafer boat to near the top of the wafer boat 6. The plurality of nozzle holes 14a of the inhibition gas supply nozzle 14 are formed so that the reaction inhibition gas is uniformly supplied to the target object mounted on the wafer boat 6, and the opening direction of the nozzle holes 14a is as follows. It is desirable that the tangential direction of the peripheral portion of the semiconductor substrate that is the object to be processed.
[0017]
As the reaction inhibiting gas used in the present invention, any gas can be used as long as it has an action of suppressing the progress of the film forming reaction. For example, hydrogen chloride gas, chlorine fluoride gas, or the like is used in forming a Si film. be able to. This reaction inhibiting gas can be used without being diluted, or can be diluted with an inert gas such as N ₂ or a rare gas such as argon gas.
[0018]
In the present invention, if the pressure at the time of ejection of the reaction-inhibiting gas is excessive, the reaction-inhibiting gas is diffused as a whole on the surface of the object to be processed, and the film forming reaction only in the periphery of the object to be processed is suppressed. It becomes difficult to realize the action. Therefore, it is preferable that the ejection pressure is low so that a high-concentration reaction-inhibiting gas is unevenly distributed only in the periphery of the object to be processed.
[0019]
And as FIG. 2 which is a principal part schematic perspective view which shows the supply form of the raw material gas to the to-be-processed object surface in this batch type heat processing apparatus, raw material gas supplies raw material gas from the downward direction of the to-be-processed object W. It is supplied via the nozzle 13 and circulates from the lower side to the upper side of the object to be processed. On the other hand, in the vicinity of the object to be processed, the reaction inhibiting gas supply nozzle 14 extends from the lower part of the reaction vessel 2 to the vicinity of the top of the wafer boat 6, and a plurality of nozzle holes 14a are formed in the reaction inhibiting gas supply nozzle. Has been. This nozzle hole 14a is preferably formed so that the reaction-inhibiting gas can be uniformly supplied to the object to be processed mounted on the wafer boat 6.
Further, the reaction-inhibiting gas is ejected from the nozzle hole 14a toward the tangential direction of the periphery of the workpiece W. As a result, the film formation reaction rate at the periphery of the object to be processed is lower than that at the center of the object to be processed, and as a result, the generated film thickness at the periphery of the object to be processed is reduced. The difference is reduced, and the film thickness in the surface of the object to be processed can be made uniform.
In the present invention, the ejection direction of the reaction inhibiting gas is the tangential direction of the periphery of the object to be treated. However, if the ejection direction of the reaction inhibiting gas is set in the direction toward the center of the object to be treated, Since it becomes impossible to suppress the film formation reaction only at the peripheral part, it is not possible to expect the effect of in-plane uniformization of the film thickness of the object to be processed.
[0020]
Further, even if one reaction-inhibiting gas supply nozzle is provided in the reaction vessel, the effect is recognized. However, if two nozzles are provided, the effect of improving the uniformity in the film thickness can be expected. If one reaction inhibition gas nozzle is used to strongly suppress the growth of the film thickness at the periphery of the workpiece, the flow rate or flow rate of the reaction inhibition gas can be increased. As a result, the reaction-inhibiting gas is eventually uniformly dispersed in the reaction chamber, making it difficult to locally increase the concentration of the inhibiting gas in the periphery of the object to be processed. Therefore, in such a case, it is preferable that the number of reaction inhibiting gas nozzles is increased so that the flow rate and flow rate of the reaction inhibiting gas ejected from each reaction inhibiting gas nozzle are not excessively increased.
Further, when two reaction-inhibiting gas supply nozzles are disposed, it is desirable that they be disposed at positions facing each other as viewed from the center of the semiconductor substrate, as seen in FIG. Further, it is desirable that the reaction-inhibiting gas injection directions from the plurality of reaction-inhibiting gas supply nozzles 14 and 14 ′ are arranged so that the injection directions are opposite to each other. Here, the injection direction of the reaction inhibiting gas may be the same as or reverse to the rotation direction of the object to be processed, but the reaction inhibiting gas is uniformly dispersed in the reaction chamber, and the reaction inhibiting gas is locally distributed. Therefore, the ejection direction of the reaction inhibiting gas preferably coincides with the rotation direction of the object to be processed.
[0021]
Furthermore, although three reaction inhibiting gas supply nozzles can be disposed, the reaction inhibiting gas supplied into the reaction vessel is uniformly dispersed in the reaction vessel, and the concentration is averaged. The effect of improving the in-plane uniformity of the film thickness is reduced, which is not preferable.
[0022]
The batch-type heat treatment apparatus of the present invention described above can be applied to heat treatment that forms a film on the surface of a heat-resistant plate using a thermal decomposition reaction of a chemical substance. The present invention can be applied to a film or a film formation on the surface of a glass substrate for LCD, but is not limited thereto, and can be applied to a film formation on various substrate surfaces.
[0023]
【Example】
A test for forming a polysilicon film on the surface of a 200 mm (8 inch) silicon wafer was performed using a low pressure CVD apparatus equivalent to that shown in FIG. 1 except that two source gas introduction nozzles were provided.
That is, first, as a reaction inhibition gas nozzle, a semiconductor processing apparatus was prepared in which one reaction inhibition gas nozzle having 30 nozzle holes having a nozzle hole pitch of 4 cm and a hole diameter of 0.2 mm was disposed in the reaction chamber.
Next, 30 silicon wafers of 200 mm (8 inches) were aligned and mounted on a wafer boat and accommodated in a reaction chamber in the main body of the heating furnace. The mounting pitch of silicon wafers in the wafer boat was set to 4 cm, which is equal to the nozzle hole pitch of the reaction inhibition gas nozzle. Hydrogen chloride gas was supplied from the reaction inhibition gas nozzle at a flow rate of 150 to 600 sccm.
Next, while the wafer boat is rotated in the same direction as the reaction-inhibiting gas supply direction at a speed of 0.5 rpm, the temperature in the reaction chamber is raised to 900 ° C., and then a raw material gas at a pressure of 133.3 Pa (1 Torr). Dichlorosilane and hydrogen gas were supplied to the reaction chamber so that the flow rate of dichlorosilane was 500 to 1000 sccm and hydrogen gas was 1600 sccm, and heating was continued for a required time to form a polysilicon thin film on the silicon wafer surface. Filmed.
[0024]
On the other hand, as a comparative example, using the conventional semiconductor processing apparatus of FIG. 5, a polysilicon film is formed on the surface of a 200 mm (8 inch) silicon wafer under the same conditions as in the above example except that no reaction inhibiting gas is used. did.
After film formation in the above-described embodiment of the present invention and the comparative example, the silicon wafer located at the center of the silicon boat is taken out, and the film thickness of the polysilicon film on the surface is measured to make the film formation in-plane uniform. Sex was evaluated. The result is shown in FIG.
[0025]
As is clear from the results of FIG. 4, when the reaction inhibiting gas of the present invention is used, the film forming speed at the periphery of the 200 mm (8 inch) silicon wafer is lower than when the conventional reaction inhibiting gas is not used. Was reduced by approximately 20%, and it became clear that the difference in film thickness from the central portion of the silicon wafer was reduced.
[0026]
【The invention's effect】
According to the present invention, it is possible to realize a processing apparatus capable of manufacturing a processing substrate excellent in in-plane semiconductor uniformity with a simple configuration without significantly changing the semiconductor processing apparatus.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a semiconductor processing apparatus of the present invention.
FIG. 2 is an enlarged perspective view of a main part showing an example of a semiconductor processing apparatus of the present invention.
FIG. 3 is an enlarged perspective view of a main part showing another example of the semiconductor processing apparatus of the present invention.
FIG. 4 is a graph showing the effect of the first embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a conventional semiconductor processing apparatus.
FIG. 6 is a cross-sectional view showing another example of a conventional semiconductor processing apparatus.
[Explanation of symbols]
W ... Semiconductor substrate 1, 501 ... Heating furnace body 2, 502 ... Reaction vessel 3, 503 ... Reaction vessel outer tube 4, 504 ... Reaction vessel inner tube 5, 505 ... Heating Apparatus 6,506 ... Wafer boat 7,507 ... Insulating cylinder 8,508 ... Rotating shaft 9,509 ... Rotating bearing 10,510 ... Manifold 11,511 ... Lower lid 12 , 512... Elevator 13, 513... Source gas supply nozzle 14, 14 ′ Reaction inhibition gas supply nozzle 15, 515... Exhaust port 601. ... Still 604 ... Substrate holder 605 ... Single crystal substrate 606 ... Resistance heating furnace 607 ... Nozzle tube 608 ... Gas outlet 609 ... Exhaust hole 611 ... Nozzle for etching tube

Claims (2)

A heating furnace main body, heating means disposed in the heating furnace main body, a reaction vessel accommodated in the heating furnace main body and containing a wafer boat on which an object to be processed is placed; In a batch type heat treatment apparatus comprising at least a nozzle for supplying a raw material gas into a reaction vessel and an exhaust port for discharging exhaust gas in the reaction vessel,
A reaction-inhibiting gas supply nozzle having a plurality of holes for supplying a gas that inhibits a film-forming reaction in the reaction vessel ;
In the batch heat treatment apparatus, the jet direction of the reaction inhibiting gas from the reaction inhibiting gas supply nozzle is a tangential direction of the peripheral portion of the object to be treated. The batch heat treatment apparatus according to claim 1, wherein at least two reaction-inhibiting gas supply nozzles are disposed in the reaction vessel.

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