JPH09102460A - Semiconductor manufacture device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a thin film of high quality by preventing production of a natural oxide film and reduce a cost and cut a time in natural oxide film production prevention in a semiconductor manufacturing device provided with a load lock chamber. SOLUTION: Reducing gas is introduced to at least one of an inside of a reaction furnace 1 and an inside of a load lock chamber 3 or reducing gas is introduced to a reaction furnace inside. Inert gas is introduced to a load lock chamber inside. A matter which is a cause of natural oxidation is changed to a matter which does not contribute to oxidation by reaction by introduction of reducing gas or an inside of a reaction furnace is made reducing gas atmosphere of high concentration and furthermore, diluted in a load lock chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a chemical vapor deposition method (Chemical Vapor Dep) on a silicon wafer.
The present invention relates to a semiconductor manufacturing method for forming a thin film by means of a position, and particularly to a load-lock type semiconductor manufacturing apparatus equipped with a load-lock chamber.

[0002]

2. Description of the Related Art A load-lock type semiconductor manufacturing apparatus will be described with reference to FIG.

A load lock chamber 3 is provided below the reaction furnace 1 via a gate valve 2, and a wafer transfer machine 4 is provided adjacent to the load lock chamber 3.

The reactor 1 has an outer tube 7 inside a heater 6,
A reaction tube 9 having a double tube structure of the inner tube 8 is provided,
The lower end of the cylindrical space 11 formed by the outer pipe 7 and the inner pipe 8 is closed. A gas introduction pipe 10 is provided at the inner lower end of the inner pipe 8.
The exhaust pipe 12 communicates with the lower end of the space 11.

A boat elevator 13 is provided inside the load lock chamber 3, and a boat 14 is erected on the boat elevator 13. The boat 14 is loaded into and unloaded from the reaction tube 9 by the boat elevator 13. It is supposed to be taken off. The wafer transfer machine 4 is installed in the load lock chamber 3
The wafer is loaded and unloaded through the gate valve 15 provided on the side surface. Further, the wafer transfer machine 4 transfers the wafers with respect to the boat 14. An exhaust line 16 and a purge gas supply pipe 17 are connected to the load lock chamber 3.

When wafers are loaded into the boat 14, the gate valve 15 is closed, the atmosphere in the load lock chamber 3 is evacuated to a vacuum, or the atmosphere is replaced with an inert gas to be an inert gas atmosphere. There is. Although the gate valve 2 is opened and the boat 14 is loaded into the reaction tube 9, since the load lock chamber 3 has a vacuum atmosphere and an inert gas atmosphere, the wafer is heated by the radiant heat from the furnace. In this case, generation of a natural oxide film is prevented. In the state where the wafer is loaded in the reaction tube 9 in the boat 14 and heated to the reaction temperature by the heater 6,
A reaction gas is introduced from the gas introduction pipe 10 to form a thin film on the wafer surface. When the film formation is completed, the boat 14 is pulled out, and the gate valve 2 closes the furnace opening of the reaction tube 9.

When the boat 14 is pulled out, as described above, the load lock chamber 3 is evacuated from the atmosphere to be a vacuum or an inert gas atmosphere to prevent natural oxidation of the high temperature wafer immediately after the reaction. doing. The load lock chamber 3 is sufficiently cooled so as not to be naturally oxidized in the atmosphere, the gate valve 15 is opened, and the wafer transfer machine 4 transfers the wafer to the outside of the apparatus.

In order to prevent the above natural oxidation in the load lock chamber 3, it is necessary to reduce the residual amount of oxygen, water, etc., which causes the oxidation, as much as possible. Evacuate to a high degree of vacuum, purge the load lock chamber 3 with an inert gas, further purify the gas to be purged and increase the flow rate, and further heat the load lock chamber 3 to eliminate water etc. adhering to the wall surface. The residual amount was reduced by doing so.

Before the wafer is loaded into the reaction furnace, the temperature inside the furnace is lowered, after which the wafer is loaded into the reaction tube 9 and the seal cap 19 closes the lower end of the reaction tube 9 before the reaction tube 9 is loaded. A reducing gas was flown inside to remove the oxide film formed on the wafer surface.

[0010]

In the above-mentioned conventional example, the method of exhausting the inside of the load lock chamber 3 to a high degree of vacuum to purify the purge gas to a high degree and increasing the flow rate thereof causes a large amount of expensive gas to be consumed, resulting in cost reduction. In addition, there is a problem that it takes a long time to replace the inert gas and evacuate, which increases the cost. Further, since the temperature of the reaction furnace 1 is lowered, it takes a long time to lower the temperature of the reaction furnace 1 and adhere to the reaction furnace. A stress is generated in the formed film to easily peel it off, and the film peels off to contaminate the wafer. Furthermore, in the method of charging the wafer into the reaction furnace 1 and flowing a reducing gas to remove the natural oxide film, the wafer is heated during the charging of the wafer to cause a reaction, and the oxide film thickness increases. There is a problem that the processing time becomes long and the surface condition of the substrate is deteriorated.

In view of the above situation, the present invention attempts to prevent the formation of a natural oxide film and to form a high quality thin film, and at the same time, to reduce the cost and time for preventing the formation of a natural oxide film. Is intended.

[0012]

According to the present invention, in a semiconductor manufacturing apparatus in which a load lock chamber is connected to a reaction furnace, a reducing gas is introduced into at least one of the inside of the reaction furnace and the inside of the load lock chamber. , Or introducing a reducing gas into the reactor,
It is configured to introduce an inert gas into the load lock chamber.

By introducing a reducing gas at the time of insertion or withdrawal or during insertion or withdrawal, a substance causing natural oxidation is reacted with the reducing gas and removed outside the reaction chamber to prevent formation of a natural oxide film. Alternatively, a reducing gas is introduced into the reaction furnace and an inert gas is introduced into the load lock chamber, so that a high concentration reducing gas atmosphere is created in the reaction furnace and further dilution is performed in the load lock chamber to ensure safety. be able to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

According to the present invention, in a semiconductor manufacturing apparatus having a load lock chamber 3 as shown in FIG. 2, a gas that reacts with oxygen is introduced into the load lock chamber 3 to remove an oxidation-causing substance. is there.

When the atmosphere in the load lock chamber 3 is evacuated from the atmosphere to a high vacuum, the gas that reacts with the residual gas of oxygen when the pressure drops to a predetermined pressure (for example, the pressure of oxygen is the lower limit of combustion of hydrogen) Introduce. The gas to be introduced may be hydrogen or ammonia, and 2 if the gas to be introduced is hydrogen.
The reaction of H ₂ + O ₂ → 2H ₂ O occurs, and in the case of ammonia gas, the reaction of 2NH ₃ + 3 / 2O ₂ → N ₂ + 3H ₂ O occurs. Oxygen has the property of reacting more easily with hydrogen than when comparing hydrogen with silicon. By introducing a large amount of this hydrogen, O ₂ is stabilized as H ₂ O and oxidation with the silicon wafer can be prevented. . Similarly, ammonia reacts with oxygen gas to be stabilized as nitrogen gas and H ₂ O, and the oxidation of the wafer can be prevented. The produced H ₂ O is removed by the reducing gas purging effect. The trace amount of H ₂ O that remains is also excluded.

Similarly, when the atmosphere in the load-lock chamber 3 is replaced with an inert gas, when the inert gas reaches a certain level, the purge gas is mixed with a gas that reacts with the residual oxygen gas, and the gas is left as it is. Eliminate outside the device.

Next, a second embodiment of the present invention will be described.

In the second embodiment, a reducing gas is introduced into the reaction tube 9, and N is introduced into the reaction tube 9.
Introduction of a reducing gas such as H ₃ , H ₂ or N ₂ H ₄ prevents oxidation due to residual oxygen.

FIG. 1 shows a schematic structure of a semiconductor manufacturing apparatus according to this embodiment. In FIG. 1, the same parts as those shown in FIG. Omitted.

A reducing gas introducing pipe 18 is connected to the lower end of the space 11 so that the reducing gas can flow into the space 11 from the lower end of the space 11.

From the start of charging the boat 14 into the reaction tube 9, the reducing gas is introduced through the reducing gas introduction tube 18. The reducing gas ascends in the space 11 and returns at the upper end of the inner pipe 8, and then descends and flows down into the load lock chamber 3 through the inner pipe 8 to fill the reaction pipe 9 with the reducing gas. When the reducing gas is supplied to the high temperature portion while the boat 14 is loaded in the reaction tube 9, the residual oxygen reducing gas in the high temperature portion reacts. Since the oxidation occurs in the high temperature part, the supply of the reducing gas in the high temperature part is particularly effective for preventing unnecessary oxidation of the wafer. Furthermore, since the reducing gas is heated by flowing through the reaction tube 9 kept at a high temperature, the reaction between the reducing gas and the residual oxygen is promoted, the cause of the oxidation can be effectively removed, and the use of the wafer becomes unnecessary. Oxidation can be prevented and the native oxide film already attached to the wafer can be removed.

If the reducing gas is supplied into the reaction tube 9 and the inert gas is supplied into the load lock chamber 3, the concentration of the reducing gas in the load lock chamber 3 is increased due to explosion proof and exhaust gas. Even if there is a situation that cannot be achieved, the inside of the processing reaction tube 9 can be made into a high-concentration reducing gas atmosphere, and the antioxidant effect is not affected.

For example, by flowing H ₂ in the reaction tube 9 at 4 l / min and N _{2 in the} load lock chamber at 100 l / min, a high-concentration reducing atmosphere is maintained in the reaction tube 9. The H _{2 that} has flown out is diluted with N _{2 in the} load lock chamber, and the hydrogen concentration becomes 4% or less, so that it can be safely processed.

It should be noted that oxidation may be prevented by introducing a reducing gas into both the reaction tube 9 and the load lock chamber 3, and in this case, the reducing gas has a strong influence on the wafer or the reducing gas treatment apparatus. If there is a problem with the processing capacity of the above, it may be diluted with an inert gas if necessary.

In the above embodiment, the vertical semiconductor manufacturing apparatus having the vertical furnace has been described. However, in the case of the vertical type, since the load lock chamber 3 is below the high temperature reaction tube 9, the convection should be prevented. Therefore, the concentration of the reducing gas in the reaction tube 9 and the load lock chamber 3 can be increased. Further, when a nitride film is formed, if NH ₃ is supplied as a reducing gas, nitriding can be performed simultaneously with the reduction, and a high quality CVD film can be obtained.

The present invention can be applied not only to the vertical type semiconductor manufacturing apparatus but also to the horizontal type semiconductor manufacturing apparatus.
Needless to say, the position where the reducing gas is introduced into the reaction tube 9 may be a position where the reducing gas flows out toward the furnace opening portion, and may be, for example, the upper end of the outer tube 7. Furthermore, the timing of purging the reducing gas differs depending on various processes. In other words, if you want to minimize the generation of natural oxide film on the wafer (including deposited film) before processing in this device, you want to minimize the generation of natural oxide film on the deposited film formed after processing in this device. In this case, either one or both may be required, and if necessary, the charging of the boat and the withdrawal of the boat are selected, and the reducing gas is supplied.

[0028]

As described above, according to the present invention, the formation of useless natural oxide film can be prevented, so that the film quality can be improved. Specifically, the natural oxide film is etched (heated in H ₂ at a high temperature). or, without flowing etching gas) can form an epitaxial film, and since there is no natural oxide film in the case of forming a nitride film without lowering the dielectric constant, since the base is nitrided by further NH ₃ treatment nucleation It exhibits excellent effects such as the formation of a flat and uniform high quality film without the need of.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional example.

[Explanation of Codes] 1 Reactor 3 Load lock chamber 6 Heater 7 Outer tube 8 Inner tube 9 Reaction tube 11 Space 14 Boat 18 Reducing gas introduction tube

Claims (4)

[Claims] 1. A semiconductor manufacturing apparatus in which a load lock chamber is connected to a reaction furnace, wherein a reducing gas is introduced into at least one of the inside of the reaction furnace and the inside of the load lock chamber. Semiconductor manufacturing equipment. 2. The semiconductor manufacturing apparatus according to claim 1, wherein the reducing gas is introduced into the reaction furnace and the inert gas is introduced into the load lock chamber. 3. The semiconductor manufacturing apparatus according to claim 1, wherein the reducing gas is H ₂ . 4. The semiconductor manufacturing apparatus according to claim 1, wherein the reducing gas is NH ₃ .