Film deposition method and film deposition apparatus

Abstract

To provide a technique for reducing a content of a halogen element in a nitride film.SOLUTION: A film deposition method has (A) below. (A) a first nitride film is formed on a substrate by decomposing at least a part of a reaction product and depositing on the substrate in a state where a reaction product of a raw material gas containing an element to be nitrided and a halogen element and a nitriding gas is deposited on a member inside a treatment container. A decomposition of at least a part of the reaction product includes generating a plasma in the inside of the treatment container and making the plasma collide with the reaction product.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a film forming method and a film forming apparatus. [Background technology]

[0002] The film formation method described in Patent Document 1 forms a TiN film on a substrate by an ALD method. Specifically, for example, TiCl4 gas and NH3 gas are alternately supplied to the substrate to form the TiN film on the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-80349 A Summary of the Invention [Problem to be solved by the invention]

[0004] One aspect of the present disclosure provides a technique for reducing the content of halogen elements in a nitride film. [Means for solving the problem]

[0005] A film forming method according to one aspect of the present disclosure includes the following (A): (A) forming a first nitride film on a substrate without supplying the source gas to the substrate by decomposing at least a portion of a reaction product of a source gas containing an element to be nitrided and a halogen element and a nitriding gas, the reaction product being deposited on a member inside a processing vessel, and depositing the reaction product on a substrate. Decomposing at least a portion of the reaction product includes generating plasma inside the processing vessel and colliding the plasma with the reaction product. Effect of the Invention

[0006] According to one aspect of the present disclosure, the content of halogen elements in a nitride film can be reduced. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a film forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a flow chart showing an example of a method for forming the second nitride film. [Diagram 3] FIG. 3 is a timing chart showing an example of a method for forming the second nitride film. [Figure 4] FIG. 4 is a diagram showing an example of the film formation conditions for the second nitride film. [Diagram 5] FIG. 5 is a flow chart showing an example of a method for forming the first nitride film. [Figure 6] FIG. 6 is a timing chart showing an example of a method for forming the first nitride film. [Figure 7] FIG. 7 is a diagram showing an example of the film formation conditions for the first nitride film. [Figure 8] FIG. 8 shows an example of the chlorine content in the first nitride film and the chlorine content in the second nitride film. [Figure 9] FIG. 9 is a flowchart showing a film forming method according to an embodiment. [Figure 10] FIG. 10 is a diagram showing the chlorine content at the interface between the substrate and the nitride film according to the example and the comparative example. [Figure 11] FIG. 11 is a diagram showing the film formation conditions of S301 (formation of the first nitride film) in FIG. [Figure 12] FIG. 12 is a diagram showing the film formation conditions of S302 (formation of the second nitride film) in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted.

[0009] A film forming apparatus according to one embodiment will be described with reference to Fig. 1. The film forming apparatus includes a processing vessel 1, a holder 2, a shower head 3, a gas exhaust unit 4, a gas supply unit 5, a plasma generation unit 8, and a control unit 9.

[0010] The processing vessel 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing vessel 1 accommodates a substrate W. The substrate W has, for example, a semiconductor substrate. The semiconductor substrate is, for example, a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. The substrate W may have various functional films formed on the semiconductor substrate. The functional films include at least one of a conductive film and an insulating film.

[0011] A side wall of the processing vessel 1 is formed with a loading / unloading port 11 through which a transport device (not shown) loads or unloads the substrate W. The loading / unloading port 11 is opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing vessel 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed on the outer wall of the exhaust duct 13. A top wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the processing vessel 1 via an insulating member 16. A seal ring 15 hermetically seals the space between the exhaust duct 13 and the insulating member 16. The partition member 17 partitions the inside of the processing vessel 1 into upper and lower sections when the holder 2 (and the cover member 22) is elevated to a processing position described later.

[0012] The holder 2 holds the substrate W inside the processing vessel 1. The holder 2 is, for example, a stage, and holds the substrate W horizontally. The holder 2 is formed in a disk shape having a size corresponding to the substrate W, and is supported by a support member 23. The holder 2 is made of a ceramic material such as AlN, or a metal material such as an aluminum or nickel alloy, and has a heater 21 embedded therein for heating the substrate W. The heater 21 generates heat when power is supplied from a heater power source (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the upper surface of the holder 2, thereby controlling the substrate W to a predetermined temperature. The holder 2 is provided with a cover member 22 made of ceramics such as alumina so as to cover the outer peripheral region of the upper surface and the side surfaces.

[0013] A support member 23 for supporting the holding part 2 is provided on the bottom surface of the holding part 2. The support member 23 extends from the center of the bottom surface of the holding part 2 through a hole formed in the bottom wall of the processing vessel 1 to the bottom of the processing vessel 1, and its lower end is connected to a lifting mechanism 24. The lifting mechanism 24 raises and lowers the holding part 2 via the support member 23 between the processing position shown in FIG. 1 and a transfer position shown by a two-dot chain line below the processing position where the substrate W can be transferred. A flange 25 is attached to the bottom of the processing vessel 1 of the support member 23. A bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25. The bellows 26 separates the atmosphere inside the processing vessel 1 from the outside air, and expands and contracts with the lifting and lowering operation of the holding part 2.

[0014] Three wafer support pins 27 (only two shown) are provided near the bottom surface of the processing vessel 1 so as to protrude upward from a lift plate 27a. The wafer support pins 27 are raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the processing vessel 1. The wafer support pins 27 are inserted into through holes 2a provided in the holder 2 at the transfer position and can be protruded and retracted from the upper surface of the holder 2. The substrate W is transferred between the transfer mechanism (not shown) and the holder 2 by raising and lowering the wafer support pins 27.

[0015] The shower head 3 supplies various gases into the processing vessel 1 in a shower-like manner. The shower head 3 is made of metal, is provided to face the holding part 2, and has approximately the same diameter as the holding part 2. The shower head 3 has a main body part 31 and a shower plate 32. The main body part 31 is fixed to the ceiling wall 14 of the processing vessel 1. The shower plate 32 is connected below the main body part 31. A gas diffusion space 33 is formed between the main body part 31 and the shower plate 32. A gas introduction hole 36 is provided in the gas diffusion space 33 so as to penetrate the center of the ceiling wall 14 and the main body part 31 of the processing vessel 1. An annular protrusion part 34 protruding downward is formed on the periphery of the shower plate 32. A gas discharge hole 35 is formed on the inner flat part of the annular protrusion part 34. When the holding part 2 is in the processing position, a processing space 38 is formed between the holding part 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion part 34 are close to each other to form an annular gap 39.

[0016] The gas exhaust unit 4 exhausts gas from inside the processing vessel 1 to the outside. The gas exhaust unit 4 has an exhaust pipe 41 connected to the exhaust port 13b, and an exhaust mechanism 42 having a vacuum pump, a pressure control valve, and the like connected to the exhaust pipe 41. During processing, the gas inside the processing vessel 1 reaches the exhaust duct 13 through the slit 13a, and is exhausted by the exhaust mechanism 42 from the exhaust duct 13 through the exhaust pipe 41.

[0017] The gas supply unit 5 supplies various gases to the shower head 3, thereby supplying the various gases from the shower head 3 to the holding unit 2. The gas supply unit 5 includes a gas source 51 and a gas line 52. The gas source 51 includes, for example, various gas supply sources, a mass flow controller, and a valve (none of which are shown). The various gases are introduced from the gas source 51 through the gas line 52 and the gas introduction hole 36 into the gas diffusion space 33.

[0018] The film forming apparatus is, for example, a capacitively coupled plasma apparatus, in which the holding unit 2 functions as a lower electrode and the shower head 3 functions as an upper electrode. The holding unit 2 is grounded via a capacitor (not shown). However, the holding unit 2 may be grounded, for example, without a capacitor, or may be grounded via a circuit combining a capacitor and a coil. The shower head 3 is electrically connected to a plasma generating unit 8.

[0019] The plasma generating unit 8 generates plasma inside the processing vessel 1. The plasma generating unit 8 has an RF power supply 81, a matching box 82, and a power supply line 83. The RF power supply 81 is a power supply that generates high frequency power (hereinafter also referred to as "RF power"). The RF power has a frequency suitable for generating plasma. The frequency of the RF power is, for example, within a range from 450 KHz in the low frequency band to 2.45 GHz in the microwave band. The RF power supply 81 is electrically connected to the main body 31 of the showerhead 3 via the matching box 82 and the power supply line 83. The matching box 82 has a circuit for matching the load impedance to the internal impedance of the RF power supply 81. The power supply line 83 supplies the RF power to the showerhead 3.

[0020] Although the plasma generating unit 8 has been described as supplying RF power to the shower head 3 serving as the upper electrode, the present invention is not limited to this. It may be configured to supply RF power to the holder 2 serving as the lower electrode. The plasma generating unit 8 is not limited to capacitively coupled plasma, and may generate other types of plasma, such as inductively coupled plasma.

[0021] The control unit 9 is, for example, a computer, and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls the operation of the film forming apparatus.

[0022] Next, a method for forming a second nitride film will be described with reference to Fig. 2 and Fig. 3. When a transfer device (not shown) loads the substrate W from the outside to the inside of the processing chamber 1, the control unit 9 performs steps S101 to S109. In steps S101 to S108, the temperature of the holder 2, i.e., the temperature of the substrate W, is, for example, 300°C to 500°C, the temperature of the shower head 3 is, for example, 300°C to 500°C, and the pressure inside the processing chamber 1 is, for example, 100 Pa to 600 Pa. Note that the film forming method does not necessarily have to include all of steps S101 to S109. Furthermore, the film forming method may include steps other than steps S101 to S109.

[0023] Step S101 includes the gas supply unit 5 supplying a source gas to the substrate W through the shower head 3 while the gas exhaust unit 4 exhausts gas from inside to outside the processing chamber 1. The source gas contains an element X to be nitrided and a halogen element. The source gas is, for example, TiCl4 gas. By supplying the source gas to the substrate W, a source-containing layer containing the element X can be formed on the substrate W. The element X is, for example, Ti. The source-containing layer may contain a halogen element in addition to the element X. The halogen element is, for example, Cl. The source gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas or N2 gas.

[0024] The source gas is TiCl4 gas in this embodiment, but is not limited to TiCl4 gas. The source gas may be WCl6 gas, VCl4 gas, AlCl3 gas, MoCl5 gas, SnCl4 gas, HfCl4 gas, or the like. The element X may be a semiconductor element, for example, Si or Ge. That is, the source gas may be a silicon halide gas or a germanium halide gas. The silicon halide gas may be, for example, SiCl4 gas, SiHCl3 gas, SiH2Cl2 gas, SiH3Cl gas, or Si2Cl6 gas. 、 The gas may be, for example, Si2HCl5 gas, SiH2I2 gas, or SiCl3CH3 gas. The germanium halide gas may be, for example, GeCl4 gas.

[0025] Step S102 includes the gas exhaust unit 4 exhausting gas from inside the processing vessel 1 to the outside, while the gas supply unit 5 supplies a purge gas to the substrate W via the shower head 3. This allows the gas remaining inside the processing vessel 1 to be replaced with the purge gas. The purge gas is, for example, Ar gas or N2 gas.

[0026] Step S103 includes the gas supply unit 5 supplying the modifying gas to the substrate W through the shower head 3 while the gas exhaust unit 4 exhausts the gas from inside the processing chamber 1 to the outside. The modifying gas is, for example, H2 gas or N2 gas. The modifying gas may be a mixed gas of H2 gas and N2 gas. The modifying gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas. By supplying the modifying gas to the substrate W, the raw material containing layer can be modified. The modification of the raw material containing layer includes, for example, removing a halogen element contained in the raw material containing layer. By removing the halogen element, the raw material containing layer can be activated and the nitridation of the raw material containing layer can be promoted. Step S103 may include the plasma generation unit 8 generating the modifying gas into plasma to promote the modification of the raw material containing layer.

[0027] Step S104, like step S102, includes the gas exhaust unit 4 exhausting gas from inside the processing vessel 1 to the outside while the gas supply unit 5 supplies a purge gas to the substrate W via the shower head 3. This allows gas remaining inside the processing vessel 1 to be replaced with the purge gas. The purge gas is, for example, Ar gas or N2 gas.

[0028] Step S105 includes the gas supply unit 5 supplying nitriding gas to the substrate W via the shower head 3 while the gas exhaust unit 4 exhausts gas from inside the processing vessel 1 to the outside. The nitriding gas is, for example, NH3 gas or N2 gas. The nitriding gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas. By supplying the nitriding gas to the substrate W, the raw material-containing layer can be nitrided. Step S105 may include the plasma generation unit 8 generating the nitriding gas into plasma to promote nitridation of the raw material-containing layer.

[0029] Step S106, like step S102, includes the gas exhaust unit 4 exhausting gas from inside the processing vessel 1 to the outside while the gas supply unit 5 supplies a purge gas to the substrate W via the shower head 3. This allows gas remaining inside the processing vessel 1 to be replaced with the purge gas. The purge gas is, for example, Ar gas or N2 gas.

[0030] Like step S103, step S107 includes the gas supply unit 5 supplying the modifying gas to the substrate W through the shower head 3 while the gas exhaust unit 4 exhausts gas from the inside to the outside of the processing chamber 1. This allows the nitrided raw material-containing layer to be modified. The modification of the nitrided raw material-containing layer includes, for example, removing halogen elements contained in the raw material-containing layer. The modification of the nitrided raw material-containing layer also includes removing unnecessary reaction products (for example, NH4Cl) generated by the nitridation of the raw material-containing layer. The modifying gas may be supplied together with a dilution gas. Step S107 may include the plasma generation unit 8 generating the modifying gas into plasma to promote the modification of the nitrided raw material-containing layer.

[0031] The film forming method may include only one of steps S103 and S107.

[0032] Like step S102, step S108 includes the gas exhaust unit 4 exhausting gas from inside the processing vessel 1 to the outside while the gas supply unit 5 supplies a purge gas to the substrate W via the shower head 3. This allows gas remaining inside the processing vessel 1 to be replaced with the purge gas. The purge gas is, for example, Ar gas or N2 gas.

[0033] In step S109, the control unit 9 checks whether steps S101 to S108 have been performed a set number of times (K times), where K is an integer equal to or greater than 1. If the number of times has not reached K (step S109, NO), the control unit 9 performs the processes from step S101 onwards again. On the other hand, if the number of times has reached K (step S109, YES), the control unit 9 ends this process. Thereafter, a transport device (not shown) transports the substrate W from inside the processing vessel 1 to outside.

[0034] An example of the film forming conditions for the second nitride film is shown in Fig. 4. In Fig. 4, an RF power of 0 W means that the plasma generating unit 8 does not generate plasma from the gas inside the processing vessel 1, and an RF power of 500 W or 1000 W means that the plasma generating unit 8 generates plasma from the gas inside the processing vessel 1. In Fig. 4, TiCl4 is a source gas, H2 gas is a modifying gas, NH3 gas is a nitriding gas, and Ar gas is a purge gas or a dilution gas. In Fig. 4, T1 is the temperature of the holder 2, that is, the temperature of the substrate W, and T2 is the temperature of the showerhead 3.

[0035] Next, an example of a method for forming a first nitride film will be described with reference to Fig. 5 and Fig. 6. When a transfer device (not shown) carries the substrate W from the outside to the inside of the processing chamber 1, the control unit 9 performs steps S201 to S208. The method for forming a first nitride film is performed in the same manner as the method for forming a second nitride film, except that there is no step corresponding to step S101, that is, no raw material gas is supplied to the substrate W. Steps S201 to S207 are performed in the same manner as steps S102 to S108, and therefore detailed description thereof will be omitted. In steps S201 to S207, the temperature of the holder 2, i.e., the temperature of the substrate W, is, for example, 300°C to 500°C, the temperature of the shower head 3 is, for example, 300°C to 500°C, and the pressure inside the processing chamber 1 is, for example, 100 Pa to 600 Pa.

[0036] In step S208, the control unit 9 checks whether steps S201 to S207 have been performed a set number of times (M times). M is an integer equal to or greater than 1. If the number of times has not reached M (step S208, NO), the control unit 9 performs the processes from step S201 onwards again. On the other hand, if the number of times has reached M (step S208, YES), the control unit 9 ends this process. Thereafter, a transfer device (not shown) transfers the substrate W from inside the processing vessel 1 to outside. Note that the film forming method does not have to include all of steps S201 to S208. Furthermore, the film forming method may include steps other than steps S201 to S208.

[0037] The method for forming the first nitride film includes decomposing at least a part of a reaction product of a source gas and a nitriding gas, the reaction product being accumulated on a member inside a processing vessel 1, and depositing the reaction product on the substrate W, thereby forming a first nitride film on the substrate W without supplying a source gas to the substrate W. When forming the first nitride film, it is sufficient not to supply a source gas, and a nitriding gas may or may not be supplied.

[0038] Decomposing at least a part of the reaction product includes generating plasma inside the processing vessel 1 and colliding the generated plasma with the reaction product. That is, decomposing at least a part of the reaction product includes plasma sputtering. The member may be any member provided inside the processing vessel 1, and is not particularly limited, but is, for example, a shower head 3.

[0039] In the method for forming the first nitride film, the first nitride film is formed on the substrate W without supplying a source gas to the substrate W. The first nitride film does not use a source gas containing a halogen element, so the content of the halogen element can be reduced. According to this embodiment, even if the temperature of the substrate W during the formation of the first nitride film is 400° C. or less, the content of the halogen element in the first nitride film can be reduced to 1.0×10 19 atoms / cm 3The content of halogen elements is measured by secondary ion mass spectrometry (SIMS) at a position 5 nm deep from the surface of the first nitride film. The content of halogen elements in the first nitride film is preferably 2.0×10 18 atoms / cm 3 The lower the content of halogen elements, the better the film quality (for example, film density).

[0040] The reaction product is deposited on a member inside the processing vessel 1 by, for example, performing the film formation method shown in FIGS. 2 and 3 before the formation of the first nitride film. Alternatively, the reaction product may be deposited on a member inside the processing vessel 1 by performing the film formation method shown in FIGS. 2 and 3 before the formation of the first nitride film without the substrate W inside the processing vessel 1. After being deposited on the member inside the processing vessel 1, the reaction product is exposed to the gas inside the processing vessel 1 and releases the halogen element. As a result, the content of the halogen element in the reaction product can be reduced before the formation of the first nitride film.

[0041] The reaction product is preferably modified by exposing it to H2 gas while the shower head 3 is heated to 300°C to 500°C before the formation of the first nitride film. More preferably, the reaction product is modified by exposing it to plasma H2 gas while the shower head 3 is heated to 300°C to 500°C before the formation of the first nitride film. The content of halogen elements in the reaction product can be reduced before the formation of the first nitride film.

[0042] During deposition of the first nitride film, the plasma to be collided with the reaction products is preferably generated while supplying at least one of Ar gas, H2 gas, and NH3 gas to the substrate W under conditions in which the pressure inside the processing vessel 1 is 600 Pa or less and the radio frequency power (RF power) applied to the gas inside the processing vessel 1 is 500 W or more.

[0043] FIG. 7 shows an example of the deposition conditions for the first nitride film. In FIG. 7, an RF power of 0 W means that the plasma generating unit 8 does not generate plasma from the gas inside the processing vessel 1, and an RF power of 1000 W means that the plasma generating unit 8 generates plasma from the gas inside the processing vessel 1. In FIG. 7, TiCl4 is a source gas, H2 gas is a modifying gas, NH3 gas is a nitriding gas, and Ar gas is a purge gas or a dilution gas. In FIG. 7, T1 is the temperature of the holder 2, that is, the temperature of the substrate W, and T2 is the temperature of the showerhead 3.

[0044] Fig. 8 shows an example of the chlorine content of the second nitride film and the chlorine content of the first nitride film. The chlorine content was measured by secondary ion mass spectrometry (SIMS) at a position 5 nm deep from the surface of the second nitride film or at a position 5 nm deep from the surface of the first nitride film. As is clear from Fig. 8, the chlorine content of the first nitride film is smaller than the chlorine content of the second nitride film, at 1.0 x 10 19 atoms / cm 3 The results were as follows.

[0045] Next, a film forming method according to one embodiment will be described with reference to FIG. 9. When a transfer device (not shown) loads a substrate W from the outside to the inside of the processing chamber 1, a control unit 9 performs steps S301 to S303. Step S301 includes forming a first nitride film. The method of forming the first nitride film is as described above. Step S302 includes forming a second nitride film. The method of forming the second nitride film is as described above.

[0046] In step S303, the control unit 9 checks whether steps S301 to S303 have been performed a set number of times (N times), where N is an integer equal to or greater than 1. If the number of times has not reached N (step S303, NO), the control unit 9 performs the processes from step S301 onwards again. On the other hand, if the number of times has reached N (step S303, YES), the control unit 9 ends this process. Thereafter, a transport device (not shown) transports the substrate W from inside the processing vessel 1 to outside.

[0047] In this embodiment, step S301 is performed before step S302, but may be performed after step S302. When N is an integer equal to or greater than 2, the film forming method alternately repeats steps S301 and S302 multiple times. The ratio of the thickness of the first nitride film to the thickness of the second nitride film may be changed between performing steps S301 and S302 the mth time and performing steps S301 and S302 the nth time (n is an integer greater than m and equal to or less than N).

[0048] Next, the chlorine content at the interface between the substrate and the nitride film in the embodiment and the comparative example will be described with reference to Fig. 10. As shown in Fig. 10, in the embodiment, S301 and S302 were performed once each in this order, whereas in the comparative example, only S302 was performed. The film formation conditions for S301 are shown in Fig. 11, and the film formation conditions for S302 are shown in Fig. 12. As shown in Fig. 10, in the embodiment, unlike the comparative example, the first nitride film was formed before the second nitride film was formed, so that the chlorine content at the interface between the substrate and the nitride film could be reduced.

[0049] Although the embodiments of the film forming method and the film forming apparatus according to the present disclosure have been described above, the present disclosure is not limited to the above-mentioned embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. Naturally, these also fall within the technical scope of the present disclosure. [Explanation of symbols]

[0050] 1 Processing vessel 2 Holding part 3. Shower head 4 Gas exhaust section 5 Gas supply section 8 Plasma generating section 9. Control Unit W substrate

Claims

1. (A) forming a first nitride film on a substrate without supplying the source gas to the substrate, by decomposing at least a portion of a reaction product of a source gas containing an element to be nitrided and a halogen element and a nitriding gas, the reaction product being deposited on an internal member of a processing vessel, and depositing the reaction product on a substrate; The film forming method, wherein decomposing at least a portion of the reaction product includes generating plasma inside the processing chamber and colliding the plasma with the reaction product.

2. (B) supplying the source gas and a nitriding gas to the substrate to form a second nitride film on the substrate; The film forming method according to claim 1 , wherein the step (A) is performed before the step (B).

3. (B) supplying the source gas and a nitriding gas to the substrate to form a second nitride film on the substrate; The film forming method according to claim 1 , wherein the step (A) is performed after the step (B).

4. The film forming method according to claim 2 , wherein the steps (A) and (B) are alternately repeated a plurality of times.

5. 5. The film forming method according to claim 4, wherein a ratio of a thickness of the first nitride film to a thickness of the second nitride film is changed when performing (A) and (B) for an mth time and when performing (A) and (B) for an nth time (n is an integer greater than m).

6. The (B) is H ２ Gas and N ２ 4. The method of claim 2, further comprising modifying the second nitride film by supplying at least one gas to the substrate.

7. the member is a shower head that ejects the source gas, The reaction product is heated to 300° C. to 500° C. with the shower head heated to 300° C. to 500° C. before (A). ２ The method for forming a film according to any one of claims 1 to 3, wherein the film is modified by exposure to a gas.

8. The reaction product is H that has been converted into plasma in a state where the shower head is heated to 300° C. to 500° C. before the step (A). ２ The film forming method according to claim 7 , wherein the film is modified by exposure to a gas.

9. In the above (A), the plasma colliding with the reaction product is generated by mixing Ar gas, H under a condition that the pressure inside the processing vessel is 600 Pa or less and a high frequency power applied to the gas inside the processing vessel is 500 W or more. ２ Gas and NH ３ The film forming method according to any one of claims 1 to 3, wherein at least one of the gases is generated while being supplied to the substrate.

10. The processing vessel; a holder for holding the substrate inside the processing vessel; A shower head provided opposite the holding unit; a gas supply unit that supplies gas to the shower head, thereby supplying gas from the shower head toward the holding unit; a gas exhaust unit that exhausts gas from the inside of the processing vessel; a plasma generating unit that generates the plasma inside the processing vessel; a control unit that controls the gas supply unit, the gas exhaust unit, and the plasma generation unit to perform the film formation method according to any one of claims 1 to 3; A film forming apparatus comprising:

Images