JP4356882B2 - Method for forming atomic layer control thin film - Google Patents

Description

The present invention relates to a method for forming an atomic layer control thin film that can be used in a thin film growth process in semiconductor manufacturing.

  Along with the progress of high integration of semiconductor devices, design rules have been miniaturized, and thin films constituting semiconductor devices have been required to be sufficiently controlled to the molecular level or atomic level.

  The formation of this molecular layer or atomic layer control thin film is called ALD (atomic layer deposition), which is a method of forming a film by supplying raw materials to the surface of the substrate to be processed and laminating the raw materials in a monoatomic layer or monomolecular layer form. is there.

  Hereinafter, this process will be described with reference to FIG. That is, in the first step (S41), the first gas material as a raw material is supplied to the reaction furnace in which the substrate to be processed is arranged, and the gas raw material as the material is adsorbed on the surface of the substrate to be processed in a monomolecular layer or an atomic layer shape. It is a process to make. Next, in the second step (S42), among the first raw materials supplied to the reaction furnace in the above step, surplus raw materials remaining in the reaction furnace atmosphere including the vicinity of the surface of the substrate to be processed are not adsorbed. It is a process to do. Next, in the third step (S43), the second gas raw material serving as the raw material is supplied into the reaction furnace, and is further adsorbed in a monomolecular layer or an atomic layer, and the first gas raw material and the second gas are absorbed. This is a step of chemically reacting a raw material to form a reaction product to be formed on the surface of the substrate to be processed as a layer controlled at a molecular level. Next, in the fourth step (S44), among the second raw materials supplied to the reaction furnace in the step, surplus raw materials remaining in the reaction furnace atmosphere including the vicinity of the surface of the substrate to be processed without being adsorbed, This is a step of eliminating substances generated by the chemical reaction in the previous step. It is inspected whether or not the thickness of the thin film generated by the above steps is a required thickness (S45). If the thickness is insufficient, the process is repeated from the first step (S41). Repeat the process.

  The ALD method is a method of forming a thin film having a required film thickness controlled at a molecular level or an atomic level through the above steps.

  As described above, in the conventional ALD method, in order to obtain a desired film thickness, a plurality of different raw materials are alternately introduced into the reaction furnace, and the adsorption process and the reaction / growth process are repeated to obtain the desired film thickness. In order to enhance the effect of each process, a purge process using an inert gas such as nitrogen gas is provided between the adsorption process and the reaction / growth process (steps S42 and S44) (see Patent Document 1). ).

However, according to this method, a plurality of raw materials are likely to remain in the vicinity of the surface of the substrate to be processed, and if a sufficient amount of gas is not supplied as a purge gas, the raw materials cannot be completely wiped away, and different types of thin films are used. There is a tendency for atoms to be mixed and the atomic layer arrangement to be incomplete, or for the purging process to take a long time, which is a cause of deterioration in productivity. In other words, in the conventional ALD method, in order to increase the effect, generally, a method of lengthening the execution time of the purge process is taken, so that the productivity is remarkably lowered. As can be seen from these facts, the execution time of the purge process in ALD is in a trade-off relationship with the purity of the thin film to be improved by the ALD method, and the process cannot be simply shortened. there were.

JP 2003-318174 A

  The present invention has been made to solve the above-described problems in the ALD method, and can form a film having a uniform and well controlled atomic arrangement by a simple method and is required for the film formation. It is an object of the present invention to provide a method for forming a thin film that can shorten the time and can form an atomic layer control thin film excellent in productivity.

The present invention is a method of supplying a raw material to a semiconductor substrate disposed in a reaction furnace to form an atomic layer control thin film,
(1) A first raw material, which is a raw material for a thin film formed on the surface of the semiconductor substrate, is supplied to a reaction furnace, and the first raw material is adsorbed on a substrate surface that is placed in the reaction furnace and maintained at a reaction temperature. A first step of
(2) At least the semiconductor substrate by stopping the supply of the first raw material after the completion of the first step, and introducing an inert gas into the reaction furnace after reducing the pressure in the reaction furnace or simultaneously with the pressure reduction A second step of wiping off the first raw material remaining in the vicinity of the surface;
(3) After the supply of the inert gas in the second step is stopped, the second raw material that is a constituent raw material of the thin film is supplied to the reaction furnace through a flow rate control mechanism, and is disposed in the reaction furnace. A third step of growing a thin film by bringing the second raw material into contact with the surface of the semiconductor substrate and chemically reacting with the first raw material adsorbed in the first step;
(4) After completion of the thin film growth step in the third step, the supply of the second raw material is stopped, and an inert gas is introduced into the reaction furnace after depressurization or simultaneously with depressurization, so that at least the surface of the semiconductor substrate When the atomic layer control thin film is formed on the surface of the semiconductor substrate by repeating the fourth step of wiping away the second raw material remaining in the vicinity until reaching a desired film thickness,
In the second and fourth steps, as the inert gas, high-purity nitrogen heated to at least 100 ° C. or more by a heat exchanger using collision jet heat transfer is introduced into the reactor at least 100 cm ^{3 /} min. This is a method for forming an atomic layer control thin film.

In the present invention, the introduction of high-purity nitrogen into the reaction furnace is started after the first source gas is supplied and before the supply is stopped, and / or the supply of high-purity nitrogen is stopped in the third step. It is preferable to supply the second raw material before .

In the present invention, as the thin film, an insulator thin film such as a silicon oxide film or a silicon nitride film, a metal film such as tungsten or aluminum, a group III-V, a group II-VI, a group IV-IV compound semiconductor, and Any of metal oxide films such as HfO ₂ can be used.

  According to the present invention, compared to the conventional ALD method, the effect of the conventional purge process can be improved to a level equal to or higher than that of the conventional purge process in a short purge time, and thus a high-purity thin film can be obtained. Productivity is also improved by shortening the process time.

[Principle and operation of the present invention]
Hereinafter, the principle and operation of the present invention will be described.
In the ALD method, the present invention obtains the effect of the present invention by supplying high-purity nitrogen gas heated using a collision jet heat transfer heat exchanger as a purge gas to be supplied to a reaction furnace.

  The impinging jet heat transfer in the present invention is a phenomenon in which when a gas collides with a heat exchange target surface at a high speed, a gas layer that inhibits heat transfer on the target surface is thinned and the heat exchange efficiency is dramatically improved. The gas phase reaction suppression action of high purity nitrogen heated to at least 100 ° C. or higher by a heat exchanger using this impinging jet heat transfer is generally introduced into the exhaust pipe after leaving the reaction furnace. It is known for its effect of suppressing the accumulation of by-products. The principle of this by-product accumulation suppression is explained as follows. When high-purity nitrogen heated to 100 ° C. or higher by this method was introduced into the exhaust pipe where ammonium chloride might be deposited, an effect of suppressing byproduct deposition was observed. In this exhaust pipe, the heated nitrogen is reduced to 50 ° C. or less as soon as it leaves the heat exchanger as a heat source. Therefore, the ammonium chloride precipitation suppression effect is not obtained by raising the exhaust gas to a temperature higher than the precipitation temperature of the by-product, but the molecular arrangement in the precipitation gas changes by mixing heated nitrogen according to this method. It is thought that it was because. In order to precipitate a crystalline salt such as ammonium chloride, a certain amount of acid-alkali molecular bonds are required. However, if this method is not used, the molecular arrangement in the mixed gas existing in the piping is not uniform. It is considered that specific gas molecules are scattered and scattered within a certain region, and the scattered acid molecule aggregates and alkali molecule aggregates bind and react to form a salt crystal. It is thought that a thing precipitates. On the other hand, the nitrogen superheated by the heat exchanger using impinging jet heat transfer is heated in units of particles by the impinging jet motion in the heat exchange channel, so that it is heated and activated to a uniform temperature and has high kinetic energy. become. The exhaust gas = acid and alkali molecules mixed in the activated nitrogen atmosphere are completely and uniformly arranged by the high energy nitrogen gas, and the nitrogen dilution effect is maximized. As a result, it is considered that acid molecules and alkali molecules in the mixed gas are inhibited from interaction by high-energy nitrogen and chloride precipitation is suppressed. However, when a heat exchanger that does not rely on impinging jet heat transfer, such as a general coil heat exchanger or perforated plate heat exchanger, is used as a fluid heating source, the heat exchange efficiency is low, so nitrogen is heated and activated uniformly. If the heating temperature is set large to improve efficiency, the temperature gradient of the mixed gas in the exhaust pipe becomes large. As a result, the uniform arrangement effect of the mixed gas molecules is small and the crystal salt precipitation suppressing effect is also small. In the present invention, nitrogen heated by a heat exchanger using this impinging jet heat transfer is introduced into a reaction furnace to improve the purge effect by the inert gas of ALD.

[Film deposition system]
A film forming apparatus that can be used in the present invention will be described with reference to FIG.
As shown in FIG. 1, the film forming apparatus includes a reaction furnace 6 that houses a semiconductor substrate as a substrate to be processed and forms a film by a film forming reaction. The reaction furnace 6 includes the reaction furnace 6. 6, a gas supply device 5 for supplying a raw material gas and a purge gas as raw materials to the reaction furnace 6 at a predetermined pressure, maintaining the pressure in the reaction furnace 6 at a reduced pressure, and a reaction furnace A reactor pressure reducing pump 7 for discharging the gas in 6 is connected. The gas supply device 5 stores a raw material to be a first raw material, and stores a first raw material storage container 1 for supplying the raw material to the reaction furnace while controlling the flow rate thereof, and a raw material to be a second raw material. The second raw material storage container 2 for supplying the reactor with the flow rate being controlled and the impinging jet heat transfer heat exchanger 4 for heating the purge gas supplied to the reactor 6 are connected. The impinging jet heat transfer heat exchanger 4 is connected to a purge gas storage container 3 for controlling and supplying the flow rate of the high purity nitrogen gas that is a purge gas. Excess nitrogen gas is connected to the reactor pressure reducing pump 7. The discharge port of the decompression pump 7 is connected to an exhaust gas treatment system, and the exhaust gas discharged from the reaction furnace 6 is treated by the reaction furnace decompression pump 7 such as detoxification.

  Hereinafter, each mechanism constituting the film forming apparatus of the present invention will be described.

(Impact jet heat transfer heat exchanger)
In the present invention, it is necessary to uniformly heat the nitrogen gas used as the purge gas. For this purpose, a heat exchanger known as a collision jet heat transfer heat exchanger is used. This heat exchanger uses a metal plate as a heated heat supply medium, collides with the purge gas at high speed, and effectively exchanges heat using the kinetic energy at that time.

  As the metal plate which is a heat supply medium, a steel raw material plate such as stainless steel can be used. The metal plate needs to have a sufficient heat capacity, and is preferably a block or thick plate as large as possible. The surface preferably collides with the jetted purge gas with a large kinetic energy, and for this reason, it is desirable to have a plane perpendicular to the jetting direction of the purge gas.

  The flow rate of the purge gas supplied to the heat exchanger is preferably in the range of 3 to 80 m / min. When the flow rate is lower than the above range, the heat exchange efficiency of the heat supply medium and the purge gas is lowered, and the purge gas is uniformly heated. Cannot achieve the intended purpose. On the other hand, even if the flow rate exceeds the above range, an excessive facility is required for that purpose, and the improvement of the effect of uniform heating of the purge gas corresponding to that is not seen, which is uneconomical.

  As shown in FIG. 1, it is preferable that the purge gas heated in this heat exchanger is supplied into the reaction furnace as quickly as possible without causing a decrease in the temperature of the purge gas. Further, in this heat exchanger, the excessively supplied purge gas can be directly discharged to the exhaust gas treatment device for processing the excess portion.

(Gas supply device)
The gas supply device 5 is a device for receiving supply of a plurality of types of source gas and purge gas and supplying them to the reaction furnace 6 in a predetermined sequence, for controlling piping from the source gas and purge gas and these. And a control mechanism for controlling the opening and closing of the valve. The supply sequence of the source gas or the like can be realized by a control device such as a microcomputer built in the gas supply device 5.

(Raw material supply container and purge gas supply container)
As described above, the reaction furnace is supplied with a plurality of raw materials and a purge gas. The raw material supply container and the purge gas are supplied while accommodating these raw materials and controlling their flow rates. Supply container. These supply containers are composed of a container such as a cylinder for storing raw materials, a valve connected to a pipe led out from the container, and a control mechanism for controlling the valve. When the raw material to be used is liquid at normal temperature, the raw material can be heated and vaporized and supplied to the gas supply device 5.

(Other attached mechanisms)
The film forming apparatus of the present invention is mainly composed of the above mechanism, but in addition, a heating apparatus for heating the reaction furnace 6, a temperature sensor for measuring the temperature in the reaction furnace 6, and the pressure in the reaction furnace 6 A pressure sensor for detecting the substrate, a substrate holding device such as an electrostatic chuck for holding the substrate to be processed, a drive mechanism for rotating the substrate holding device, and for rectifying the source material and purge gas in the reaction furnace 6 A rectifying plate or the like can be arranged as necessary.
Further, when the reaction furnace 6 is a plasma film forming apparatus, a plasma generating apparatus is disposed.

[Film Formation Process: First Embodiment]
A first embodiment of an atomic layer control thin film forming method of the present invention will be described below. Hereinafter, this embodiment will be described with reference to FIG. 4 showing a flow of a film forming process.

  The method for forming an atomic layer control thin film of the present invention can be applied to a silicon wafer itself or a substrate whose surface is subjected to a base formation process such as formation of metal wiring or interlayer insulating film by various processes. Examples of the atomic layer control thin film formed on the surface include a silicon oxide film, a silicon nitride film, and a metal oxide film known as a high K film, but the present invention is not limited to this.

  First, a substrate to be processed is placed in a reaction furnace, and the inside of the reaction furnace is depressurized to a predetermined pressure by a reaction furnace decompression pump. Furthermore, the temperature in the reaction furnace is raised to a temperature necessary for the film formation reaction.

(First step)
The first step (S41) is a step of supplying a first gaseous material as a raw material to a reaction furnace in which the substrate to be processed is arranged, and adsorbing the gaseous raw material as a raw material on the surface of the processed substrate in a monomolecular layer or an atomic layer shape. It is.

  When the thin film formed on the substrate to be processed is a silicon oxide film, monosilane, TEOS, or the like can be used as the first raw material. When the thin film is a silicon nitride film, silane gas, HCD, or the like can be used as the first raw material. Further, when the thin film is a high-K raw material thin film, the first raw material may be an organometallic compound containing various metals such as aluminum, zirconium, and hafnium, for example, an organometallic compound such as trimethylaluminum. .

  The temperature of the first raw material in this step cannot be defined unconditionally because it varies greatly depending on the physical properties of each raw material, but generally speaking, a temperature that does not liquefy under the gas phase conveyance pressure is preferable. When the temperature of the raw material falls below a predetermined temperature, there is a problem of clogging due to liquefaction and solidification of the raw material gas. On the other hand, when the temperature exceeds the above range, the heating power is lost and, of course, pressure fluctuation is caused. There is a fear. The temperature of the raw material can be appropriately determined in consideration of these factors.

  In addition, the flow rate of the first raw material varies depending on the raw material type and cannot be generally defined, but generally speaking, the flow rate of the first raw material may be determined in consideration of factors such as density, vapor pressure, and activation energy. it can. When the flow rate of the raw material falls below a predetermined range, it causes a film formation failure or a decrease in the film formation speed, while supplying the raw material flow rate exceeding the predetermined range does not contribute to the adsorption of the raw material, It is unnecessary.

  Furthermore, since the time for supplying the first raw material varies depending on the raw material as described above, it cannot be defined unconditionally. However, if the supply time falls below a predetermined range, the first raw material is not sufficiently adsorbed. On the other hand, even if the raw material is supplied over a predetermined range, it does not contribute to the adsorption of the raw material and is unnecessary.

(Second step)
Next, in the second step (S42), among the first raw materials supplied to the reaction furnace in the above step, surplus raw materials remaining in the reaction furnace atmosphere including the vicinity of the surface of the substrate to be processed are not adsorbed. It is a process to do.

In this step, excess raw material can be removed by using high-purity nitrogen gas heated by the impinging jet heat transfer heat exchanger as a purge gas and supplying it into the reaction furnace 6. The temperature of the high purity nitrogen gas is preferably 100 ° C. or higher. When the temperature of the nitrogen gas is lower than 100 ° C., the activity of the heated nitrogen is also lowered, and there is a problem that the purge (ie, gas phase reaction suppression) efficiency is lowered, which is not preferable. The purge gas flow rate is preferably 100 cm ³ / min or more. When this flow rate is less than 100 cm ³ / min, there is a problem in that the heat exchange efficiency due to the impinging jet flow material is lowered and activation necessary for obtaining the purge effect does not occur, which is not preferable.

  In the present invention, by using high purity nitrogen gas as the purge gas, the molecular weight of the nitrogen gas is larger than when using an inert gas such as a rare gas, and the kinetic energy of the purge gas is obtained by uniform and efficient heating. This is advantageous in that effective purge can be realized. The high purity nitrogen gas is preferably a gas having a nitrogen content of at least 99.9999% by volume. When the purity is below this range, not only the purge efficiency is lowered, but also the reactor may be contaminated, which is not preferable.

(Third step)
A 3rd process (S43) supplies the 2nd gaseous raw material used as a raw material in a reaction furnace, and also makes it adsorb | suck to a monomolecular layer or an atomic layer form, The said 1st gaseous raw material, the said 2nd gaseous raw material, Is a step of forming a reaction product to be formed as a layer controlled on a molecular level on the surface of the substrate to be processed.
When the thin film formed on the substrate to be processed is a silicon oxide film, oxygen gas, water, hydrogen peroxide, ozone, or the like can be used as the second raw material. When the thin film is a silicon nitride film, as the second raw material, a hydrazine-based material such as ammonia or methylhydrazine, an amine-based material such as methylamine, or the like can be used. Further, when the thin film is a high K raw material thin film, oxygen, water, hydrogen peroxide, ozone, or the like can be used as the first raw material.

  The temperature of the second raw material in this step cannot be generally defined because it varies greatly depending on the physical properties of each raw material, but generally speaking, a temperature at which the liquid does not liquefy under the gas phase conveyance pressure is preferable. When the temperature of the raw material falls below a predetermined temperature, there is a problem of clogging due to liquefaction and solidification of the raw material gas. On the other hand, when the temperature exceeds the above range, the heating power is lost and, of course, pressure fluctuation is caused. There is a fear. The temperature of the raw material can be appropriately determined in consideration of these factors.

  In addition, the flow rate of the second raw material varies depending on the raw material type and cannot be generally defined, but generally speaking, the flow rate of the second raw material may be determined in consideration of factors such as density, vapor pressure, and activation energy. it can. If the flow rate of the raw material falls below a predetermined range, it causes a film formation failure or a decrease in the film formation speed, while supplying the raw material flow rate exceeding the predetermined range does not contribute to the adsorption of the raw material, It is unnecessary.

  Further, the time for supplying the second raw material cannot be generally defined because it varies depending on the raw material in the same manner as described above. However, if the supply time falls below a predetermined range, the first raw material is not sufficiently adsorbed. On the other hand, even if the raw material is supplied over a predetermined range, it does not contribute to the adsorption of the raw material and is unnecessary.

(Fourth process)
As in the second step, the fourth step (S44) is not adsorbed in the second raw material supplied to the reaction furnace in the step and remains in the reaction furnace atmosphere including the vicinity of the surface of the substrate to be processed. This is a step of removing surplus raw materials and substances generated by a chemical reaction in the previous step by supplying a purge gas.

(Film thickness determination process)
This step is a step of determining whether or not the thickness of the thin film generated by the above steps is a required thickness. The thin film formed on the substrate to be processed is measured, and the film thickness is a predetermined thickness. When it is less than the thickness, it may be determined to repeat the first step or to determine whether or not the repetition of the above step is within a preset range.

  The raw material supply timing chart of the above process is shown in FIG. In FIG. 2, the horizontal axis represents the elapsed time of the process, and (1), (2), (3), and (4) described in the upper part of FIG. 2 are the first step, the second step, and the second step, respectively. 3 steps and 4th steps are represented. In addition, the timing chart indicated by reference symbol A indicates the supply timing of the first raw material, the first raw material is supplied in the on time zone, and the first raw material is supplied in the off time zone. Indicates that it has stopped. Reference sign B represents the supply timing of the second raw material, and reference sign P represents the supply timing of the purge gas.

In the present embodiment, as apparent from FIG. 2, after the supply of the first raw material is stopped, the purge gas is supplied, and the supply of the second raw material is started after the supply of the purge gas is stopped. The supply of the purge gas is started after the supply of the second raw material is stopped. These four steps are repeated until the thickness of the thin film reaches a predetermined thickness.
According to this embodiment, it is possible to form a thin film controlled with high accuracy by relatively simple control.

[Film Formation Process: Second Embodiment]
In this embodiment, the supply of the first raw material, the purge gas, the second raw material, and the purge gas in the first embodiment is stopped after the gas supply in the previous process is stopped. Although the example of supplying was shown, the method of the present embodiment starts the supply of the gas in the next step before stopping the supply of the gas in the previous step. A timing chart of this process is shown in FIG. 3 are the same as those in FIG.
As shown in FIG. 3, the supply of the purge gas is started after the supply of the first material is started and before the supply of the first material is stopped. Further, before the supply of the purge gas is stopped, the supply of the second raw material is started. Similarly, according to this embodiment, there is a time zone in which two kinds of gases are supplied at the same time. Such a process can be realized because the purge effect becomes extremely high by using the high purity nitrogen gas heated by the impinging jet heat transfer as the purge gas.
According to this method, the purge time can be shortened, and the process efficiency can be greatly improved.

  Examples of the present invention will be specifically described below with reference to FIG. 1 showing an example of a film forming apparatus of the present invention.

(Example 1)
A semiconductor substrate as a substrate to be processed was placed in the reaction furnace 6, and the reaction furnace pressure-reducing pump 7 was driven to maintain the pressure in the reaction furnace 6 at a pressure of 133 Pa (1 Torr).
Next, HCD (Si ₂ Cl ₆ ) is adopted as the first raw material, and the flow rate is controlled to 15 sccm from the first raw material storage container 1 containing this, and the temperature is 450 ° C. according to the timing chart of FIG. The gaseous first raw material was supplied to the reaction furnace 6 for 10 seconds, and the first raw material was adsorbed on the substrate.

  Next, at the same time as the supply of the first raw material was stopped, the high-purity nitrogen gas was supplied as it was to the reaction furnace as the purge gas from the purge gas storage container. The purge gas flow rate was 0.5 l / min. At this time, the temperature and pressure in the reaction furnace were the same as those in the above process, and the purge time was 60 seconds.

Next, the second raw material container 2 is controlled to employ ammonia (NH ₃ ) as the second raw material in the reaction furnace 6, and this raw material is supplied to the reaction furnace 6 via the flow rate control supply mechanism 2. The flow rate was 450 sccm. According to the timing chart of FIG. 2, the second raw material was formed on the semiconductor substrate at a temperature of 450 ° C. for a reaction time of 20 seconds.

  Next, the supply of the purge gas was started simultaneously with stopping the supply of the second raw material. Nitrogen gas was supplied to the reactor as a purge gas as it was. The flow rate of this purge gas was 0.5 l / min. At this time, the temperature and pressure in the reaction furnace 6 were the same as those in the above process, and the purge time was 60 seconds.

  The above process was repeated 100 times to form a silicon nitride thin film having a thickness of 4.9 nm. This took a total of 250 minutes.

(Example 2)
A semiconductor substrate was placed in the reaction furnace 6, and the reaction furnace pressure-reducing pump 7 was driven to maintain the pressure in the reaction furnace 6 at a pressure of 133 Pa (1 Torr). HCD (Si ₂ Cl ₆ ) was adopted as the first raw material, and this raw material was supplied from the first raw material container 1 into the reaction furnace at a flow rate of 15 sccm. According to the timing chart of FIG. 2, the first raw material was formed on the semiconductor substrate at a temperature of 450 ° C. for 10 seconds.

  Next, at the same time as the supply of the first raw material was stopped, the supply of high-purity nitrogen gas was started from the purge gas container. The high-purity nitrogen gas was heated to 100 ° C. by passing through an impinging jet heat transfer heat exchanger, and supplied to the reactor through a gas supply device. The flow rate of this purge gas was 0.5 l / min. At this time, the temperature and pressure in the reaction furnace were the same as those in the above process, and the purge time was 40 seconds.

Next, ammonia (NH ₃ ) was adopted as the second raw material from the second raw material container 2 into the reaction furnace 6, and this raw material was supplied into the reaction furnace 6 at a flow rate of 450 sccm. According to the timing chart of FIG. 2, the second raw material was formed on the semiconductor substrate at a temperature of 450 ° C. for a reaction time of 20 seconds.

  Next, at the same time as the supply of the second raw material was stopped, supply of high-purity nitrogen gas was started from the purge gas container 3. The high purity nitrogen gas was heated to 100 ° C. by passing through an impinging jet heat transfer heat exchanger, and supplied to the reactor 6 through a gas supply device. The flow rate of this purge gas was 0.5 l / min. At this time, the temperature and pressure in the reaction furnace were the same as those in the above process, and the purge time was 40 seconds.

The above process was repeated 100 times to form a silicon nitride thin film with a thickness of 5.2 nm. This took a total of 183 minutes.

Gas flow system diagram of an apparatus for vapor phase thin film growth by ALD Feed timing chart of raw material and inert gas for purge in general ALD method Supply timing chart of raw material and heated purge nitrogen in ALD method when the present invention is applied Process flow diagram showing a typical ALD process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st raw material storage container 2 ... 2nd raw material storage container 3 ... Purge gas storage container 4 ... Heat exchanger by collision jet heat transfer 5 ... Gas supply device 6 ... Reactor 7 ... Reactor decompression pump 8 ... Exhaust gas Treatment system 9 ... Excess nitrogen discharge piping of heat exchanger

Claims (3)

A method of supplying a film forming raw material to a semiconductor substrate disposed in a reaction furnace to form an atomic layer control thin film,
(1) A first raw material, which is a raw material for a thin film formed on the surface of the semiconductor substrate, is supplied to a reaction furnace, and the first raw material is adsorbed on a substrate surface that is placed in the reaction furnace and maintained at a reaction temperature. A first step of
(2) At least the semiconductor substrate by stopping the supply of the first raw material after the completion of the first step, and introducing an inert gas into the reaction furnace after reducing the pressure in the reaction furnace or simultaneously with the pressure reduction A second step of wiping off the first raw material remaining in the vicinity of the surface;
(3) After the supply of the inert gas in the second step is stopped, the second raw material that is a constituent raw material of the thin film is supplied to the reaction furnace through a flow rate control mechanism, and is disposed in the reaction furnace. A third step of growing a thin film by bringing the second raw material into contact with the surface of the semiconductor substrate and chemically reacting with the first raw material adsorbed in the first step;
(4) After completion of the thin film growth step in the third step, the supply of the second raw material is stopped, and an inert gas is introduced into the reaction furnace after depressurization or simultaneously with depressurization, so that at least the surface of the semiconductor substrate When the atomic layer control thin film is formed on the surface of the semiconductor substrate by repeating the fourth step of wiping away the second raw material remaining in the vicinity until the desired film thickness is reached,
In the second and fourth steps, as the inert gas, high-purity nitrogen heated to at least 100 ° C. or more by a heat exchanger using collision jet heat transfer is introduced into the reactor at least 100 cm ^{3 /} min. A method for forming an atomic layer control thin film, comprising: Before the supply of the high-purity nitrogen is stopped in the third step, after the first raw material gas is supplied and before the supply is stopped, the high-purity nitrogen is introduced into the reactor. The method for forming an atomic layer control thin film according to claim 1, wherein the second raw material is supplied . The thin film is an insulator thin film such as a silicon oxide film or a silicon nitride film, a metal film such as tungsten or aluminum, a group III-V, a group II-VI, a group IV-IV compound semiconductor, or a metal oxide film such as HfO _2. The method for forming an atomic layer control thin film according to claim 1 or 2, wherein the film is any one of the following films.

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