JP2020107651A - Gas supply mechanism, gas supply method and deposition device - Google Patents

Abstract

To provide a technique capable of supplying reduction gas which has desired nitriding capability and stability and can deposit a good nitride film in depositing a nitride film.SOLUTION: The gas supply mechanism, supplying reduction gas for depositing a nitriding film, includes: an accumulation container for accumulating liquid hydrazine; an ammonia gas supply pipe for supplying ammonia gas as carrier gas in the accumulation container; and a delivery pipe for delivering, to a processing container for nitriding film deposition, hydrazine gas vaporized in the accumulation container as reduction gas together with the ammonia gas.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a gas supply mechanism, a gas supply method, and a film forming apparatus.

In semiconductor devices, a nitride film such as aluminum nitride (AlN) is often used as a functional film having a function as an antioxidant film. Further, a nitride film of AlN or the like has been attracting attention as a III-V group nitride compound semiconductor.

In Patent Document 1, when forming a nitride-based compound semiconductor, for example, trimethylaluminum (TMA) or the like is used as a source gas, and ammonia (NH ₃ ) or alkylamines is used as a reducing gas (nitriding gas). , The use of hydrazine is described.

JP 2012-59866 A

The present disclosure provides a technique capable of supplying a reducing gas having desired nitriding ability and stability and capable of forming a good nitride film when forming a nitride film.

A gas supply mechanism according to an aspect of the present disclosure is a gas supply mechanism that supplies a reducing gas for forming a nitride film, and a storage container that stores liquid hydrazines, and a storage container that conveys the hydrazine to the storage container. It has an ammonia gas supply pipe for supplying ammonia gas as a gas, and a delivery pipe for sending out the hydrazines gas vaporized in the storage container together with the ammonia gas as a reducing gas to a processing container for forming a nitride film.

According to the present disclosure, when forming a nitride film, it is possible to supply a reducing gas having a desired reducing power and capable of forming a nitride film of good film quality.

It is sectional drawing which shows roughly the film-forming apparatus which has a gas supply mechanism of one Embodiment. It is a figure which shows the detail of an example of a 1st gas supply mechanism with the reaction which arises in a storage container, when hydrazine is used as hydrazines. It is a figure which shows the detail of the other example of a 1st gas supply mechanism with the reaction which arises in a storage container, when hydrazine is used as hydrazines.

Embodiments will be described below with reference to the accompanying drawings.

<Background and overview>
First, the background and outline of the gas supply mechanism according to the embodiment of the present disclosure will be described.
As the nitride film, for example, an AlN film is used to suppress the oxidation of Cu wiring, but a nitride film having high film quality is required as the nitride film becomes thinner due to the miniaturization of semiconductor devices.

Conventionally, NH ₃ gas is often used as a reducing gas (nitriding gas) for forming a nitride film. However, NH ₃ gas does not have sufficient nitriding ability, and oxidation may occur preferentially over nitriding to hinder nitriding. In addition, the oxygen-containing substance contained as an impurity in the NH ₃ gas may cause oxidation. Therefore, nitriding may be incomplete, and electrical characteristics such as current leakage may be poor.

In contrast, hydrazines are reducing gases with high reducing power and high nitriding ability. However, since hydrazines are liquid at room temperature, it is necessary to supply them with a carrier gas (carrier gas), and they may be diluted with the carrier gas, so that the desired nitriding ability may not be obtained. In addition, hydrazines have high reducing power, but are unstable and dangerous.

Therefore, in one embodiment, a hydrazine gas and an NH ₃ gas are used together as a reducing gas (nitriding gas) for forming a nitride film. More specifically, the hydrazines are liquid, supplying the NH ₃ gas as a carrier gas, supplying the NH ₃ gas with hydrazines gas as a reducing gas. By using NH ₃ gas as the carrier gas, reduction of the nitriding ability of hydrazines can be suppressed, and hydrazines having a high reducing power can be stably used as the reducing gas for nitriding.

Trap Also, by a hydrazine is added to the NH ₃ gas, it is possible to suppress the oxidation of inhibiting nitridation by NH ₃ gas and an oxygen-containing material to reduce the nitriding ability contained in the NH ₃ gas hydrazines Can be made.

As described above, a reducing gas having a desired nitriding ability and stability can be supplied to form a good nitride film.

<Nitride film forming apparatus>
Next, a film forming apparatus having a gas supply mechanism of one embodiment will be described.
FIG. 1 is a sectional view schematically showing a film forming apparatus having a gas supply mechanism of one embodiment.

The film forming apparatus 100 forms a nitride film on the substrate S, which is an object to be processed, by CVD or ALD. As the nitride film, various films such as AlN, gallium nitride (GaN), indium nitride (InN), and titanium nitride (TiN) can be cited. The substrate S is not particularly limited, and various types such as a semiconductor wafer, a flat panel display substrate, and a ceramics substrate can be applied.

The film forming apparatus has a substantially cylindrical processing container 1 that is airtight. A stage 3 that horizontally supports a substrate S that is an object to be processed is arranged in the processing container 1. The stage 3 is supported by a cylindrical support member 5. A heater 6 for heating the substrate S is embedded in the stage 3. The heater 6 generates heat by being supplied with power from a heater power supply (not shown).

A shower head 11 is provided on the top plate 1 a of the processing container 1. The shower head 11 is provided with gas diffusion spaces 11a and 11b inside. A large number of gas discharge holes 13 a and 13 b are formed on the lower surface of the shower head 11. The gas diffusion space 11a communicates with the gas ejection hole 13a, and the gas diffusion space 11b communicates with the gas ejection hole 13b. At the center of the upper portion of the shower head 11, gas introduction paths 14a and 14b are formed, which are connected to the gas diffusion spaces 11a and 11b, respectively. The pipe of the first gas supply mechanism 20 of the present embodiment that supplies the reducing gas (nitriding gas) is connected to the gas introduction passage 14a, and the second gas that supplies the raw material gas to the gas introduction passage 14b. The piping of the supply mechanism 30 is connected. The first gas supply mechanism 20 and the second gas supply mechanism 30 will be described later.

An exhaust port 41 is formed in the bottom wall 1c of the processing container 1. An exhaust device 43 is connected to the exhaust port 41 via an exhaust pipe 42. The exhaust device 43 includes a pressure control valve, a vacuum pump, and the like, and is configured to exhaust the inside of the processing container 1 to evacuate the inside of the processing container 1 and control it to a predetermined pressure.

On the side wall of the processing container 1, a loading/unloading port 44 for loading/unloading the substrate S and a gate valve 45 for opening/closing the loading/unloading port 44 are provided.

The film forming apparatus 100 has a control unit 50. The control unit 50 is composed of a computer, and has a main control unit having a CPU that controls each component of the film forming apparatus 100. In addition, the control unit 50 also has an input device, an output device, a display device, and a storage device (storage medium). The respective components to be controlled are, for example, the heater power supply, the exhaust device 43, the first gas supply mechanism 20, the second gas supply mechanism 30, and the like. The main control unit of the control unit 50 causes the film forming apparatus 100 to perform a predetermined operation, for example, based on the processing recipe stored in the storage medium of the storage device.

Note that the shower head 11 or the like may be provided with a mechanism for applying high-frequency power to form the nitride film by plasma CVD or plasma ALD.

Next, the first gas supply mechanism 20 and the second gas supply mechanism 30, which are gas supply mechanisms according to the present embodiment, will be described.

The first gas supply mechanism 20 which is the gas supply mechanism of the present embodiment is for supplying a reducing gas for forming a nitride film into the processing container 1 via the shower head 11. Further, the second gas supply mechanism 30 is for supplying the film-forming source gas into the processing container via the shower head 11. For example, when the film to be formed is AlN, alkyl aluminum such as TMA, triethyl aluminum, and tertiary butyl aluminum is used as the source gas. A nitride film is formed by the reaction between the film-forming source gas from the second gas supply mechanism 30 and the reducing gas from the first gas supply mechanism 20.

The first gas supply mechanism 20 has a storage container 21 that stores hydrazines (hydrazine in this example). The hydrazines are stored in the storage container 21 as a liquid. A heater may be provided around the storage container 21 for heating.

Examples of hydrazines include hydrazine (N ₂ H ₄ ), and hydrazine compounds in which a part of H of hydrazine is substituted with a substituent such as an alkyl group (for example, monomethylhydrazine, 1,1-dimethylhydrazine, 1,2- Examples thereof include dimethylhydrazine, 1,1,2-trimethylhydrazine, tetramethylhydrazine), diazene, and solutions of these amines. However, hydrates are excluded because they may be oxidized.

An NH ₃ gas supply pipe 22 for supplying an NH ₃ gas from above is inserted into the storage container 21. In this example, the gas discharge port of the NH ₃ gas supply pipe 22 is located above the liquid surface of hydrazines in the storage container 21. NH ₃ gas supply source 24 is connected to the NH ₃ gas supply line 22. The NH ₃ gas supply pipe 22 is provided with a mass flow controller 25 as a flow rate controller and opening/closing valves 26a and 26b before and after the mass flow controller 25. A gas delivery pipe 23 for delivering gasified hydrazines (hydrazine gas) is also inserted into the storage container 21. The gas delivery pipe 23 is connected to the gas introduction passage 14 a of the shower head 11. The gas delivery pipe 23 is provided with an opening/closing valve 27 on the storage container 21 side, and a high-speed valve 28 for ALD near the showerhead 11. A bypass valve 29 is provided between the position on the upstream side of the opening/closing valve 26b of the NH ₃ gas supply pipe 22 and the position on the downstream side of the opening/closing valve 27 of the gas delivery pipe 23. As a result, only the NH ₃ gas can be supplied to the shower head 11 by closing the opening/closing valves 26b and 27 and opening the bypass valve 29.

NH ₃ NH ₃ gas supplied to the storage container 21 from the gas supply source 24 through the NH ₃ gas supply pipe 22 functions as a carrier gas, and associated vaporized hydrazines in the storage container 21, the gas delivery pipe 23. As a result, the NH ₃ gas and the hydrazine gas as the reducing gas are delivered from the gas delivery pipe 23 to the shower head 11 and discharged from the shower head 11 into the processing container 1.

The second gas supply mechanism 30 has a raw material gas supply pipe 31 and a raw material gas supply source 32 that supplies the raw material gas to the raw material gas supply pipe 31. The raw material gas supply pipe 31 is connected to the gas introduction passage 14b of the shower head 11. The raw material gas supply pipe 31 is provided with a mass flow controller 33 as a flow rate controller and opening/closing valves 34a and 34b before and after the mass flow controller 33. Further, a high-speed valve 35 for ALD is provided near the shower head 11 of the source gas supply pipe 31.

Although not shown, a purge gas for supplying a purge gas such as Ar gas or N ₂ gas is supplied to the gas delivery pipe of the first gas supply mechanism 20 and the source gas supply pipe 31 of the second gas supply mechanism 30. The pipe is connected. When performing ALD film formation, a high-speed valve for ALD is provided in the purge gas pipe.

<Film forming process>
Next, a film forming process performed by the above film forming apparatus 100 will be described.
First, the gate valve 45 is opened, the substrate S is loaded into the processing container 1 through the loading/unloading port 44 from the vacuum transfer chamber adjacent to the processing container 1 by a transfer device (neither is shown), and the stage 3 Place on top. Then, the inside of the processing container 1 is maintained in a vacuum state of a predetermined pressure by the exhaust device 43, and the substrate S is heated to a predetermined temperature by the heater 6.

In this state, a raw material gas such as TMA from the second gas supply mechanism 30 and a reducing gas (nitriding gas) for nitriding from the first gas supply mechanism 20 are introduced into the processing container 1 through the shower head 11. It is supplied and a nitride film, for example, an AlN film is formed.

In this case, the CVD may be one in which the source gas and the reducing gas are simultaneously supplied into the processing container 1 to form a film, or the ALD may be one in which the source gas and the reducing gas are alternately supplied. In the case of ALD, the supply of the source gas and the supply of the reducing gas are switched by opening/closing the high speed valves 28 and 35. Further, between the supply of the source gas and the supply of the reducing gas, the high-speed valves 28 and 35 are closed, the high-speed valve of the purge gas pipe is opened, and the purge gas purges the inside of the processing container 1.

At the time of supplying the reducing gas for nitriding by the first gas supply mechanism 20, with the valves 26a, 26b, 27 and 28 opened, the NH ₃ gas supply source is stored in the storage container 21 storing the liquid hydrazine. supplying NH ₃ gas through the NH ₃ gas supply line 22 from.

NH ₃ gas functions as a carrier gas for hydrazines (carrier gas). That is, the NH ₃ gas supplied into the storage container 21 is supplied to the gas delivery pipe 23 in a state of being accompanied by the hydrazine-type gas vaporized in the storage container 21. As a result, the NH ₃ gas and the hydrazine gas as the reducing gas are delivered from the gas delivery pipe 23 to the shower head 11 and discharged from the shower head 11 into the processing container 1.

FIG. 2 shows details of an example of the first gas supply mechanism together with a reaction that occurs in the storage container 21 when hydrazine (N ₂ H ₄ ) is used as the hydrazine.

As the reducing gas for nitriding, a hydrazine gas having a high reducing power and a high nitriding ability is used. However, hydrazines have high reducing power, but since they are liquid at room temperature, they need to be carried by a carrier gas, and they may be diluted with a carrier gas, so that a desired nitriding ability may not be obtained. In addition, hydrazines are unstable and highly dangerous substances.

In contrast, in this embodiment, the hydrazines are liquid, supplying the NH ₃ gas as a carrier gas, and associated to the NH ₃ gas is supplied hydrazines gas, NH ₃ with hydrazines gas as a reducing gas Gas can be supplied. As described above, by using the NH ₃ gas that is the reducing gas having the nitriding ability as the carrier gas, it is possible to suppress the reduction of the nitriding ability of the hydrazines. In addition, by adding NH ₃ gas to hydrazines, hydrogen bonds are also formed with NH ₃ , which stabilizes the hydrazines compared to pure hydrazines and can reduce the risk.

Also, when the hydrazine is added to the NH ₃ gas, as shown in FIG. 2, can be converted oxygen molecule _{(O 2)} and to water _(H 2 O) nitrogen molecules _{(N 2),} according to the NH ₃ gas Oxidation that inhibits nitriding can be suppressed. Further, when NH ₃ gas is passed through hydrazines, oxygen-containing substances such as O ₂ contained in NH ₃ gas are reduced to water, and hydrazines and water cause an azeotropic mixture having a higher boiling point than hydrazines (hydrazine hydrate). ) Is formed. As a result, oxygen-containing substances such as O ₂ that reduce the nitriding ability contained in the NH ₃ gas can be reduced and removed by hydrazines.

As described above, according to the present embodiment, it is possible to supply a reducing gas having a desired nitriding ability and stability to form a good nitride film.

In FIGS. 1 and 2, but the NH ₃ gas supply pipe 22 is not immersed in hydrazine, as shown in FIG. 3, the NH ₃ gas supply pipe 22 may be immersed in hydrazine. As described above, when the NH ₃ gas supply pipe 22 is immersed in hydrazines, the reaction that occurs is the same, but there is an advantage that the reaction between the NH ₃ gas and hydrazines is promoted. However, in the case of FIG. 3, mist is likely to occur, which may cause particles.

<Other applications>
Although the embodiments have been described above, it should be considered that the embodiments disclosed this time are illustrative in all points and not restrictive. The above-described embodiments may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.

For example, in the above-described embodiment, the case where AlN is mainly used as the nitride film and GaN, InN, and TiN are shown as the other nitride films, but the present invention is not limited to these, and various nitride films can be formed. You can

Further, the film forming apparatus is merely an example, and the film forming apparatus is not particularly limited. For example, although the single-wafer type apparatus is shown in the above embodiment, the present invention is not limited to this, and a batch type apparatus or a semi-batch type apparatus that processes a plurality of substrates at once may be used.

1; processing container 3; stage 11; shower head 20; first gas supply mechanism 21; storage container 22; NH ₃ gas supply pipe 23; gas delivery pipe 24; NH ₃ gas supply source 30; second gas supply mechanism 50; control unit 100; film forming apparatus S; substrate (object to be processed)

Claims (10)

A gas supply mechanism for supplying a reducing gas for forming a nitride film,
A storage container for storing liquid hydrazines,
An ammonia gas supply pipe for supplying ammonia gas as a carrier gas into the storage container,
A delivery pipe for delivering the hydrazine gas vaporized in the storage container to the processing container for forming a nitride film as a reducing gas together with the ammonia gas,
And a gas supply mechanism. The gas supply mechanism according to claim 1, wherein the hydrazine is selected from hydrazine, a hydrazine compound in which a part of H of hydrazine is substituted with a substituent, diazene, and a solution of these amines. .. The gas supply mechanism according to claim 1 or 2, wherein the discharge port of the ammonia gas supply pipe is located above the liquid hydrazines in the storage container. The gas supply mechanism according to claim 1 or 2, wherein the ammonia gas supply pipe is immersed in the liquid hydrazines in the storage container. A gas supply method for supplying a reducing gas for forming a nitride film, comprising:
A step of supplying ammonia gas as a carrier gas into a storage container for storing liquid hydrazines,
Sending a hydrazine gas vaporized in the storage container to the processing container for forming a nitride film together with the ammonia,
And a gas supply method. The gas supply method according to claim 5, wherein the hydrazine is selected from hydrazine, a hydrazine compound in which a part of H of hydrazine is substituted with a substituent, diazene, and a solution of these amines. .. A film forming apparatus for forming a nitride film,
A processing container in which the object to be processed is placed,
A first gas supply mechanism for supplying a reducing gas for forming a nitride film into the processing container;
A second gas supply mechanism for supplying a raw material gas for forming a nitride film into the processing container;
Have
A film forming apparatus, wherein the first gas supply mechanism is the gas supply mechanism according to any one of claims 1 to 4. The film forming apparatus according to claim 7, wherein the nitride film is formed by CVD or ALD. The film forming apparatus according to claim 7, wherein aluminum nitride is formed as the nitride film. The film forming apparatus according to claim 9, wherein the source gas is alkylaluminum.

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