JP2019085624A - Method for forming nitride film - Google Patents

Abstract

To provide a method for forming a nitride film, capable of forming a high quality nitride film having less impurities.SOLUTION: The method for forming a nitride film comprises: the first film deposition step of forming a first nitride film on a substrate by processing comprising a first supply step of supplying a raw material gas to the substrate and a first irradiation step of irradiating the substrate with neutral particle beams including nitrogen atoms without including hydrogen atoms; and the second film deposition step of forming a second nitride film on the first nitride film by processing comprising a second supply step of supplying the raw material gas to the substrate and a second irradiation step of irradiating the substrate with neutral particle beams including nitrogen atoms and hydrogen atoms.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of forming a nitride film.

  An InGaN film is known as a material such as a light emitting diode (LED: Light Emitting Diode), a high electron mobility transistor (HEMT: High Electron Mobility Transistor), and the like. The InGaN film is formed by a metal organic chemical vapor deposition (MOCVD) method, a plasma enhanced atomic layer deposition (PEALD) method, or the like.

  By the way, in the MOCVD method, it is difficult to form an InGaN film having an In / (In + Ga) ratio of 0.5 or more, since In removal from the InGaN film occurs due to high temperature film formation. In the PEALD method, since the InGaN film can be formed at a low temperature, generation of In loss can be suppressed, but problems such as deterioration of surface morphology due to plasma damage and increase of impurities in the film may occur.

  Also, an atomic layer deposition method using a neutral particle beam is known (see, for example, Patent Document 1).

Unexamined-Japanese-Patent No. 2006-265724

  However, in the above-described atomic layer deposition method using a neutral particle beam, an impurity may be mixed into the formed film due to the oxygen source generated from the substrate by the irradiation of the neutral particle beam.

  Therefore, in view of the above problems, it is an object of the present invention to provide a method of forming a nitride film capable of forming a high quality nitride film with few impurities.

  In order to achieve the above object, in the nitride film forming method according to one aspect of the present invention, there is provided a first supplying step of supplying a source gas to a substrate, and a neutral containing hydrogen atoms and containing nitrogen atoms in the substrate. A first film forming step of forming a first nitride film on the substrate by a process including a first irradiation step of irradiating a particle beam, and a second film supplying the source gas to the substrate And a second irradiation step of irradiating the substrate with a neutral particle beam containing nitrogen atoms and hydrogen atoms to form a second nitride on the first nitride film. And a second film forming step of forming a film.

  According to the disclosed nitride film forming method, it is possible to form a high quality nitride film with few impurities.

The schematic block diagram of the film-forming apparatus which concerns on embodiment of this invention Flowchart showing an example of a method of forming a nitride film according to an embodiment of the present invention Diagram showing characteristics of InGaN film Diagram showing the relationship between the TMG supply time and the impurity concentration in the film Diagram showing the relationship between the irradiation time of neutral particle beam and the impurity concentration in the film Diagram showing the relationship between nitrogen ratio and impurity concentration in film Diagram showing impurity concentration in InGaN film

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and the drawings, substantially the same configuration is given the same reference numeral to omit redundant description.

  A film forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a schematic view of a film forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the film forming apparatus 1 includes a processing container 12. The processing container 12 is a substantially cylindrical container extending in a direction in which the axis Z extends (hereinafter, referred to as “axis Z direction”), and forms a space inside. A space inside the processing container 12 is partitioned by a partition plate 40 into a plasma generation chamber S1 and a film formation chamber S2 provided below the plasma generation chamber S1.

  The processing container 12 has a first side wall 12a, a second side wall 12b, a bottom 12c, and a lid 12d. The first side wall 12a has a substantially cylindrical shape extending in the direction of the axis Z, and forms a plasma generation chamber S1. Gas lines P11 and P12 are formed on the first side wall 12a.

  The gas line P11 extends from the outer surface of the first side wall 12a and is connected to the gas line P12. The gas line P12 extends substantially annularly around the axis Z in the first side wall 12a. The gas line P12 is connected with a plurality of injection ports H1 for injecting a gas into the plasma generation chamber S1.

A gas supply source G1 is connected to the gas line P11 via a valve V11, a mass flow controller M1, and a valve V12. The gas supply source G1 is a supply source of a nitriding gas. As the nitriding gas, for example, nitrogen (N ₂ ) gas can be used. The gas supply source G1, the valve V11, the mass flow controller M1, the valve V12, the gas line P11, the gas line P12, and the injection port H1 constitute a nitriding gas supply unit. The nitriding gas supply unit controls the flow rate of the reaction gas from the gas supply source G1 in the mass flow controller M1, and supplies the flow-controlled N ₂ gas to the plasma generation chamber S1.

A gas supply source G2 is connected to the gas line P11 via a valve V21, a mass flow controller M2, and a valve V22. The gas supply source G2 is a supply source of hydrogen-containing gas. For example, hydrogen (H ₂ ) gas can be used as the hydrogen-containing gas. The gas supply source G2, the valve V21, the mass flow controller M1, the valve V22, the gas line P11, the gas line P12, and the injection port H1 constitute a hydrogen-containing gas supply unit. The hydrogen-containing gas supply unit controls the flow rate of the H ₂ gas from the gas supply source G 2 in the mass flow controller M 2, and supplies the flow-controlled H ₂ gas to the plasma generation chamber S 1.

  A lid 12d is provided at the upper end of the first side wall 12a. The lid 12 d is provided with an opening, and a plasma generation unit 20 for plasmatizing the reaction gas discharged into the plasma generation chamber S 1 is provided in the opening.

  The plasma generation unit 20 is configured by winding an antenna formed of a metal wire or the like around a vertical axis in a coil shape. The antenna is connected to the matching unit and the high frequency power supply via the ground electrode. Further, a substantially disk-shaped dielectric window 16 formed of quartz, alumina or the like is provided immediately below the plasma generation unit 20 so as to seal the plasma generation chamber S1. By applying a high frequency power of a predetermined output to the antenna by a high frequency power source, an electric field is generated immediately below the dielectric window 16 and a plasma is generated in the plasma generation chamber S1.

  A second side wall 12b extends below the first side wall 12a so as to be continuous with the first side wall 12a. The second side wall 12b has a substantially cylindrical shape extending in the direction of the axis Z, and forms a film forming chamber S2. In the film forming chamber S2, a mounting table 36 for mounting a substrate W to be film-formed is provided. The mounting table 36 is supported by a support 38 extending in the direction of the axis Z from the bottom 12 c of the processing container 12. The mounting table 36 includes a temperature control mechanism (not shown) such as a heater and a cooler. Further, the mounting table 36 is provided with a suction holding mechanism (not shown) such as an electrostatic chuck.

The second side wall 12 b is provided with a gas supply nozzle P 31 which penetrates the second side wall 12 b and penetrates from the outside to the inside of the processing container 12. A gas supply source G3 is connected to the gas supply nozzle P31 via a valve V31, a mass flow controller M3, and a valve V32. The gas supply source G3 is a gas supply source of a source gas used for the film forming process. The source gas includes a gallium (Ga) -containing gas such as trimethylgallium (TMG) and gallium chloride (GaCl ₃ ), and an indium (In) -containing gas such as trimethylindium (TMI). The gas supply source G3, the valve V31, the mass flow controller M3, the valve V32, and the gas supply nozzle P31 constitute a source gas supply unit. The source gas supply unit controls the flow rate of the source gas from the gas supply source G3 in the mass flow controller M3 and supplies the source gas whose flow rate is controlled to the film forming chamber S2.

  In the film forming apparatus 1, a partition plate 40 is provided between the plasma generation chamber S1 and the film formation chamber S2, and the plasma generation chamber S1 and the film formation chamber S2 are separated from each other by the partition plate 40. The partition plate 40 is supported by, for example, the first side wall 12a. The partition plate 40 is a substantially disk-shaped member. The partition plate 40 has a plurality of openings 40 h for communicating the plasma generation chamber S <b> 1 with the film formation chamber S <b> 2.

  The partition plate 40 has a shielding property against ultraviolet rays generated in the plasma generation chamber S1. That is, the partition plate 40 may be made of a material that does not transmit ultraviolet light. Further, the partition plate 40 donates electrons to the ions when the ions generated in the plasma generation chamber S1 pass through the opening 40h while being reflected by the inner wall surface defining the opening 40h. Thereby, the partition plate 40 neutralizes the ions, and releases the neutralized ions, that is, neutral particles to the film forming chamber S2. The partition plate 40 is formed of, for example, a member such as aluminum, stainless steel, graphite or the like.

  A bias power supply PG for applying bias power to the partition plate 40 may be connected to the partition plate 40. The bias power supply PG may be a high frequency power supply that generates high frequency bias power or may be a DC power supply. When power is supplied to the partition plate 40 by the bias power supply PG, ions generated in the plasma generation chamber S1 are accelerated toward the partition plate 40. As a result, the speed of particles passing through the partition plate 40 is increased.

Further, in the film forming apparatus 1, the pressure regulator 50 and the pressure reducing pump 52 are connected to the exhaust pipe 48 connected to the film forming chamber S2 at the bottom 12c. The pressure regulator 50 and the decompression pump 52 constitute an exhaust system. In the film forming apparatus 1, the flow rates of the N ₂ gas, the H ₂ gas, and the source gas can be adjusted by the mass flow controller M 1, the mass flow controller M 2, and the mass flow controller M 3, respectively, and the displacement can be adjusted by the pressure regulator 50. Thus, the film forming apparatus 1 can set the pressure of the plasma generation chamber S1 and the pressure of the film formation chamber S2 to an arbitrary pressure.

In addition, the film forming apparatus 1 is provided with a control unit 100 that controls the entire apparatus. The control unit 100 controls operations of various devices in the film forming apparatus 1 so as to execute a nitride film forming method described later under various processing conditions indicated in the recipe according to the recipe. For example, the control unit 100 sends a control signal to the valve V11, V12, controls the supply and stop of the supply of _{N 2} gas from the gas supply source G1, and sends a control signal to the mass flow controller M1, _{N 2} Control the gas flow rate. The control unit 100 sends a control signal to the valve V21, V22, it controls the supply and stop of the supply of _{H 2} gas from the gas supply source G2, and sends a control signal to the mass flow controller M2, _{H 2} Control the gas flow rate. The control unit 100 also sends control signals to the valves V31 and V32 to control the supply and stop of supply of the raw material from the gas supply source G3 and sends the control signal to the mass flow controller M3 to control the flow rate of the raw material gas. Control. Further, the control unit 100 sends a control signal to the pressure regulator 50 to control the displacement. Furthermore, the control unit 100 sends a control signal to the high frequency power supply of the plasma generation unit 20 to control the power of the high frequency power (RF power). Further, the control unit 100 sends a control signal to the bias power supply PG to supply and stop the supply of the bias power to the partition plate 40, and further adjusts the bias power. Furthermore, the control unit 100 sends a control signal to the temperature control mechanism of the mounting table 36 to control the temperature of the mounting table 36.

  The control unit 100 includes arithmetic means such as a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a storage means. The control unit 100 may be configured as a microcomputer that installs a program for processing a recipe from a storage medium in which the program is stored, and executes the processing of the recipe. Also, the control unit 100 may be configured as an electronic circuit such as an application specific integrated circuit (ASIC).

  Next, a method of forming a nitride film according to an embodiment of the present invention will be described by taking, as an example, a case where an InGaN film is formed using the film forming apparatus 1 described above. The method of forming a nitride film described below is performed by the control unit 100 controlling the operation of various devices in the film forming apparatus 1. FIG. 2 is a flow chart showing an example of a method of forming a nitride film according to an embodiment of the present invention.

  First, the substrate W is mounted on the mounting table 36 in the processing container 12, the substrate W is adjusted to a predetermined temperature (for example, 100 ° C. or less) by the temperature control mechanism, and the pressure regulator 50 inside the processing container 12. The pressure is adjusted to a predetermined pressure. The substrate W may be, for example, a sapphire substrate or a silicon substrate.

In step ST1, the first source gas is supplied into the film forming chamber S2 by the source gas supply unit. The first source gas may be, for example, a mixed gas containing Ga-containing gas such as TMG and GaCl ₃ and In-containing gas such as TMI. By the step ST1, a film containing Ga and In is formed on the substrate W.

In step ST2, the purge gas is supplied into the film forming chamber S2 by the source gas supply unit. The purge gas may be, for example, an inert gas such as N ₂ gas or Ar gas. In step ST2, the first source gas remaining in the film forming chamber S2 is purged. In step ST2, the first source gas remaining in the film forming chamber S2 may be purged, and a purge gas may be supplied from a gas supply unit different from the source gas supply unit.

In step ST3, the nitriding gas is supplied into the plasma generation chamber S1 by the nitriding gas supply unit, and high frequency power is applied to the antenna by the high frequency power supply of the plasma generation unit 20. Also, bias power is applied to the partition plate 40 by the bias power supply PG. The nitriding gas may be, for example, N ₂ gas. In step ST3, the substrate W is irradiated with a neutral particle beam containing nitrogen atoms and containing no hydrogen atoms, and a film containing Ga and In formed on the substrate W and neutral particles containing nitrogen atoms are formed. The reaction forms an InGaN film.

  In step ST4, the purge gas is supplied into the plasma generation chamber S1 by the nitriding gas supply unit. The purge gas may be, for example, the same as the gas used in step ST2. In step ST4, the nitriding gas remaining in the plasma generation chamber S1 is purged. In step ST4, the nitriding gas remaining in the plasma generation chamber S1 may be purged, and the purge gas may be supplied by a gas supply unit different from the nitriding gas supply unit.

  In step ST5, the control unit 100 determines whether or not the process from step ST1 to step ST4 (hereinafter referred to as "first ALD cycle") has been performed a predetermined number of times. The predetermined number of times is a number determined by a recipe or the like, and may be, for example, 100 to 200 times. In step ST5, when the control unit 100 determines that the first ALD cycle has not been performed a predetermined number of times, the process returns to step ST1, and the source gas supply unit supplies the source gas. On the other hand, when the control unit 100 determines that the first ALD cycle has been performed a predetermined number of times in step ST5, the process proceeds to step ST6.

In step ST6, the second source gas is supplied into the film forming chamber S2 by the source gas supply unit. The second source gas is, for example, a mixed gas containing Ga-containing gas such as TMG and GaCl ₃ and In-containing gas such as TMI. The second source gas may be the same gas as the first source gas, or may be a gas different from the first source gas. By step ST6, a film containing Ga and In is formed on the InGaN film formed on the substrate W by performing the first ALD cycle a predetermined number of times.

  In step ST7, the purge gas is supplied into the film forming chamber S2 by the source gas supply unit. The purge gas may be, for example, the same as the gas used in step ST2. In step ST7, the second source gas remaining in the film forming chamber S2 is purged. In step ST7, the second source gas remaining in the film forming chamber S2 may be purged, and the purge gas may be supplied from a gas supply unit different from the source gas supply unit.

In step ST8, the nitriding gas supply unit and the hydrogen containing gas supply unit respectively supply the nitriding gas and the hydrogen containing gas into the plasma generation chamber S1, and the high frequency power supply of the plasma generating unit 20 applies high frequency power to the antenna. . Also, bias power is applied to the partition plate 40 by the bias power supply PG. The nitriding gas may be, for example, N ₂ gas, and the hydrogen-containing gas may be, for example, H ₂ gas. In step ST8, the substrate W is irradiated with a neutral particle beam containing nitrogen atoms and hydrogen atoms, and a film containing Ga and In formed on the substrate W and neutral particles containing nitrogen atoms and hydrogen atoms are formed. React to form an InGaN film.

  In step ST9, the purge gas is supplied into the plasma generation chamber S1 by the nitriding gas supply unit and the hydrogen-containing gas supply unit. The purge gas may be, for example, the same as the gas used in step ST2. In step ST9, the nitriding gas and the hydrogen-containing gas remaining in the plasma generation chamber S1 are purged. In step ST9, the nitriding gas and the hydrogen-containing gas remaining in the plasma generation chamber S1 may be purged, and the purge gas may be supplied from either the nitriding gas supply unit or the hydrogen-containing gas supply unit. Further, the purge gas may be supplied by a gas supply unit different from the nitriding gas supply unit and the hydrogen-containing gas supply unit.

  In step ST10, the control unit 100 determines whether or not the process from step ST6 to step ST9 (hereinafter, referred to as "second ALD cycle") has been performed a predetermined number of times. The predetermined number of times is the number of times determined by a recipe or the like, and may be, for example, 1000 to 2000. In step ST10, when the control unit 100 determines that the second ALD cycle has not been performed a predetermined number of times, the process returns to step ST6, and the supply of the source gas by the source gas supply unit is performed. On the other hand, when the control unit 100 determines that the second ALD cycle has been performed a predetermined number of times in step ST10, the process proceeds to step ST11.

  In step ST11, the control unit 100 determines whether the stacking cycle including the first ALD cycle performed a predetermined number of times and the second ALD cycle performed a predetermined number of times has been performed a predetermined number of times. The predetermined number of times is the number of times determined by a recipe or the like, and may be one time or plural times. In step ST11, when the control unit 100 determines that the stacking cycle has not been performed a predetermined number of times, the process returns to step ST1, and the source gas supply unit supplies the source gas. On the other hand, when the control unit 100 determines that the stacking cycle has been performed a predetermined number of times in step ST11, the process ends. Thus, the InGaN film is formed on the substrate W.

  As described above, in the nitride film forming method according to the embodiment of the present invention, first, the substrate W is supplied with a source gas and irradiated with a neutral particle beam containing nitrogen atoms and containing no hydrogen atoms. Are alternately repeated to form an InGaN film on the substrate W. Thereafter, by alternately repeating the supply of the source gas and the irradiation of the neutral particle beam containing nitrogen atoms and hydrogen atoms, an InGaN film is further formed on the InGaN thin film. As described above, in the initial stage of film formation in which the surface of the substrate W is exposed, the neutral particle beam not containing hydrogen atoms is irradiated to the substrate W, so that desorption of oxygen from the surface of the substrate W can be suppressed. In addition, the incorporation of oxygen into the InGaN film can be suppressed. However, since no active hydrogen is present at the initial stage, impurities such as carbon resulting from the source gas and the like are easily mixed in the InGaN film. However, since the substrate W is irradiated with a neutral particle beam containing nitrogen atoms and hydrogen atoms after the initial stage of film formation, carbon contained in the InGaN film to be formed at this stage and formed in the initial stage Impurities such as carbon contained in the InGaN film are eliminated by active hydrogen. In this case, active hydrogen does not reach the substrate W, and no oxygen is generated from the substrate W side. As a result, the oxygen concentration and the carbon concentration in the finally formed InGaN film are low (there are few impurities), and a high quality InGaN film can be formed.

Example 1
In Example 1, the substrate temperature is set to 30 ° C., the supply of the mixed gas of TMG and TMI, and the irradiation of the neutral particle beam containing N and H are alternately repeated to form an InGaN film, and the InGaN film is formed. In / (In + Ga) and band gap energy (eV) were measured. In Example 1, the mixture ratio of TMG and TMI was changed to form a plurality of InGaN films.

  FIG. 3 is a diagram showing the characteristics of the InGaN film. In FIG. 3, the horizontal axis indicates In / (In + Ga) in the InGaN film, and the vertical axis indicates the band gap energy Eg (eV) of the InGaN film.

  As shown in FIG. 3, it can be seen that the In / (In + Ga) in the InGaN film can be adjusted by changing the mixing ratio of TMG and TMI. In particular, in Example 1, it has been confirmed that an InGaN film in which In / (In + Ga), which is difficult to form by high temperature film formation by the MOCVD method, is 0.5 or more can be formed. In addition, in the InGaN film where In / (In + Ga) is 0.5 or more, the root mean square roughness (RMS) of the surface is about 0.13 nm, the carbon impurity concentration is 0.07 at%, which is about 0 att considering the detection limit %Met. These values were better than those of the InGaN film formed by the PECVD method at a film formation temperature of 200 ° C.

  Further, as shown in FIG. 3, it can be seen that the band gap energy Eg decreases as In / (In + Ga) increases. From this, it is considered that Ga in the GaN crystal is replaced with In, and Ga and In are alloyed.

(Example 2)
In Example 2, supply of TMG and irradiation of neutral particle beam containing N and H are alternately repeated on a sapphire substrate whose substrate temperature is set to 30 ° C. to form an InGaN film, and oxygen in the InGaN film And the atomic concentration of carbon was measured. In Example 2, the evaluation was performed for the cases where the supply time of TMG is 0.5 seconds, 1 second, and 2 seconds. In addition, for the irradiation of neutral particle beam, the ratio of the flow rate of N ₂ gas to the total flow rate of N ₂ gas and H ₂ gas (hereinafter referred to as “N ₂ / (N ₂ + H ₂ )”) is 0.5. The irradiation time was 5 seconds.

  FIG. 4 is a view showing the relationship between the supply time of TMG and the impurity concentration in the film. In FIG. 4, the horizontal axis shows the supply time (seconds) of TMG, and the vertical axis shows the atomic concentration (%) of oxygen or carbon.

  As shown in FIG. 4, it can be seen that, by irradiating the neutral particle beam containing N and H, the contamination of carbon in the InGaN film can be suppressed to 1% or less. Further, as shown in FIG. 4, it can be seen that the mixing of oxygen into the InGaN film can be suppressed to 14% or less by setting the supply time of TMG to 2 seconds or less.

(Example 3)
In Example 3, supply of TMG and irradiation of neutral particle beam containing N and H are alternately repeated on a sapphire substrate whose substrate temperature is set to 30 ° C. to form an InGaN film, and oxygen in the InGaN film And the atomic concentration of carbon was measured. In Example 3, the evaluation was performed for the cases where the irradiation time of the neutral particle beam is 2.5 seconds, 5 seconds, 10 seconds, and 30 seconds. Further, the supply time of TMG is set to 1 second, and N ₂ / (N ₂ + H ₂ ) of the neutral particle beam is set to 0.5.

  FIG. 5 is a view showing the relationship between the irradiation time of the neutral particle beam and the impurity concentration in the film. In FIG. 5, the horizontal axis shows the irradiation time (seconds) of the neutral particle beam, and the vertical axis shows the atomic concentration (%) of oxygen or carbon.

  As shown in FIG. 5, when the irradiation time of the neutral particle beam is 5 seconds or less, it can be seen that the oxygen concentration in the InGaN film is low and 10% or less. Also, it can be seen that the carbon concentration in the InGaN film is relatively low when the neutral particle beam irradiation time is 2.5 seconds or more, and the carbon concentration in the InGaN film is almost 0% when the neutral particle beam irradiation time is 5 seconds or more. . Therefore, from the viewpoint of reducing the oxygen concentration and the carbon concentration, the irradiation time of the neutral particle beam is preferably 5 seconds or less, more preferably 2.5 seconds or more and 5 seconds or less, and 5 seconds Being particularly preferred.

(Example 4)
In Example 4, supply of TMG and irradiation of neutral particle beam containing N and H are alternately repeated on a sapphire substrate whose substrate temperature is set to 30 ° C. to form an InGaN film, and oxygen in the InGaN film And the atomic concentration of carbon was measured. In Example _{4, N 2 / (N 2} + H 2) is for the case of 0.3,0.4,0.5,0.8,0.9,1 was evaluated. Further, the supply time of TMG was 1 second, and the irradiation time of the neutral particle beam was 5 seconds.

FIG. 6 is a view showing the relationship between the nitrogen ratio and the impurity concentration in the film. In FIG. 6, the horizontal axis represents N ₂ / (N ₂ + H ₂ ), and the vertical axis represents the atomic concentration (%) of oxygen or carbon.

As shown in FIG. 6, when the value of N ₂ / (N ₂ + H ₂ ) is 1, ie, only N ₂ gas, the oxygen concentration is almost 0%, but it can be seen that the carbon concentration becomes high. It is considered that this is because carbon does not desorb from the InGaN film as CHx in the absence of active hydrogen. On the other hand, when H ₂ gas is added to N ₂ gas, the carbon concentration is almost 0%, but the oxygen concentration is high. It is considered that this is because carbon is desorbed from the InGaN film by active hydrogen, but oxygen is generated from the substrate surface by the active hydrogen and taken into the InGaN film. Therefore, from the viewpoint of reducing the oxygen concentration and the carbon concentration, N ₂ / (N ₂ + H ₂ ) is preferably 0.4 to 0.8, and particularly preferably 0.4. By setting N ₂ / (N ₂ + H ₂ ) to 0.4 to 0.8, an oxygen concentration of 10% or less and a carbon concentration of almost 0% can be realized. In addition, by setting N ₂ / (N ₂ + H ₂ ) to 0.4, a particularly low oxygen concentration and a carbon concentration of approximately 0% can be realized.

(Example 5)
In Example 5, an InGaN film was formed on a sapphire substrate under film forming conditions (A) to (C) described below, and the atomic concentrations of oxygen and carbon in the InGaN film were measured.

<Deposition condition (A) Only the first ALD cycle>
Substrate temperature: 30 ° C
Source gas: TMG
Feed time of raw material gas: 1 second N ₂ / (N ₂ + H ₂ ): 1
Irradiation time of neutral particle beam: 5 seconds <Deposition condition (B) Only the second ALD cycle>
Substrate temperature: 30 ° C
Source gas: TMG
Feed time of raw material gas: 1 second N ₂ / (N ₂ + H ₂ ): 0.4
Irradiation time of neutral particle beam: 5 seconds <Deposition condition (C) first ALD cycle + second ALD cycle>
After the first ALD cycle was performed under the same conditions as the film forming condition (A), the conditions for the second ALD cycle were performed under the same conditions as the film forming condition (B).

  FIG. 7 is a view showing the impurity concentration in the InGaN film. In FIG. 7, the vertical axis represents the element ratio (%) of oxygen or carbon.

  As shown in FIG. 7, by performing the second ALD cycle after performing the first ALD cycle, the oxygen concentration and the carbon concentration in the InGaN film are low (with few impurities), and high-quality InGaN is obtained. It has been confirmed that a film can be formed.

  As mentioned above, although the form for implementing this invention was demonstrated, the said content does not limit the content of invention, A various deformation | transformation and improvement are possible within the scope of the present invention.

  In the above embodiment, the InGaN film has been described as an example of the nitride film, but the present invention is not limited to this. The nitride film forming method according to the present invention may be, for example, another nitride film such as a SiN film or TiN film. It is applicable also when forming an object film.

DESCRIPTION OF SYMBOLS 1 film-forming apparatus 12 processing container 20 plasma generation part 40 partition plate S1 plasma generation chamber S2 film-forming chamber W board

Claims (9)

A first supply step of supplying a first source gas to the substrate;
A first irradiation step of irradiating the substrate with a neutral particle beam containing nitrogen atoms and not containing hydrogen atoms;
Forming a first nitride film on the substrate by a process including
Supplying a second source gas to the substrate;
A second irradiation step of irradiating the substrate with a neutral particle beam containing nitrogen atoms and hydrogen atoms;
Forming a second nitride film on the first nitride film by a process including
Have
Method of forming a nitride film. The first film forming step is a step of alternately repeating the first supply step and the first irradiation step.
The second film forming step is a step of alternately repeating the second supply step and the second irradiation step.
A method of forming a nitride film according to claim 1. The number of times of alternately repeating the first supply step and the first irradiation step is smaller than the number of times of alternately repeating the second supply step and the second irradiation step.
A method of forming a nitride film according to claim 2. The first film forming step includes a first purge step of purging the first source gas after the first supply step,
The second film formation step includes a second purge step of purging the second source gas after the second supply step.
A method of forming a nitride film according to any one of claims 1 to 3. Alternately repeating the first film forming process and the second film forming process;
A method of forming a nitride film according to any one of claims 1 to 4. The first source gas and the second source gas are gases containing a Ga-containing gas and an In-containing gas.
A method of forming a nitride film according to any one of claims 1 to 5. The Ga-containing gas is trimethylgallium (TMG) or gallium chloride (GaCl ₃ ),
The In-containing gas is trimethylindium (TMI),
A method of forming a nitride film according to claim 6. The second source gas is the same gas as the first source gas,
A method of forming a nitride film according to any one of claims 1 to 7. The substrate is a sapphire substrate,
A method of forming a nitride film according to any one of claims 1 to 8.

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