Purge method and film formation device

Abstract

This purge method is for a film formation device comprising: a substrate support portion that includes a stage supporting a substrate to be processed and an outer ring provided around the stage; and a gas supply portion that includes a shower head provided facing the substrate to be processed and supplies a processing gas and a purge gas. In the method, when purge is performed while supplying a gas mixed with hydrogen from the gas supply portion as the purge gas, the interval between the outer ring and an outer edge part of the shower head is 1 millimeter or less.

Description

Purging method and film forming apparatus

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

[0002] In Patent Document 1, H is supplied when purging a reaction gas. ２ It is disclosed that the gas has the function of lowering the resistivity of the TiN film.

[0003] Patent No. 7033882

[0004] The present disclosure provides a technique for improving the effect of reducing the electrical resistivity of a film formed by hydrogen gas and reducing the surface roughness.

[0005] According to one aspect of the present disclosure, there is provided a purging method for a film formation apparatus including a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage, and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas, wherein when purging by supplying a gas mixed with hydrogen from the gas supply unit as the purge gas, the distance between the outer ring and the outer edge of the shower head is 1 millimeter or less.

[0006] The present disclosure provides a technique for improving the effect of reducing the electrical resistivity of a film formed by hydrogen gas and reducing the surface roughness.

[0007] Fig. 1 is a diagram showing the overall configuration of a film forming apparatus in which a purging method according to this embodiment is used. Fig. 2 is a flow diagram illustrating the purging method according to the first embodiment. Fig. 3 is a diagram illustrating the relationship between spacing and electrical resistivity in the purging method according to the first embodiment. Fig. 4 is a diagram illustrating gas pressure. Fig. 5 is a diagram illustrating the relationship between spacing and surface roughness in the purging method according to the first embodiment. Fig. 6 is a diagram illustrating spacing in the purging method according to the first embodiment. Fig. 7 is a flow diagram illustrating the purging method according to the second embodiment.

[0008] Hereinafter, embodiments will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0009] In addition, with regard to the description of the specification and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be designated by the same or corresponding reference numerals to avoid redundant explanation. In addition, the scale of each part in the drawings may differ from the actual scale to facilitate understanding.

[0010] Purging Method According to First Embodiment The purging method according to the first embodiment is a purging method for a film forming apparatus including a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage, and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas. In addition, the purging method according to the first embodiment is a purging method in which a distance between the outer ring and an outer edge of the shower head is 1 millimeter or less when purging by supplying a gas mixed with hydrogen from the gas supply unit as a purge gas.

[0011] First, a film forming apparatus using the purging method according to the present embodiment will be described. Fig. 1 is a diagram showing the overall configuration of a film forming apparatus 1, which is an example of a film forming apparatus using the purging method according to the present embodiment.

[0012] The film formation apparatus 1 is a film formation apparatus that employs the so-called atomic layer deposition (ALD) method. For example, the film formation apparatus 1 supplies a source gas to a processing chamber under a vacuum atmosphere. The film formation apparatus 1 then adsorbs the source gas onto the surface of a processing substrate such as a semiconductor wafer. Next, the film formation apparatus 1 supplies a reactive gas. The film formation apparatus 1 then reacts the source gas with the reactive gas to form one or a few atomic layers. The film formation apparatus 1 repeats the above-described cycle to deposit atomic layers and form a film on the processing substrate. The source gas and reactive gas are collectively referred to as processing gas.

[0013] The film forming apparatus 1 includes a substrate support unit 10 , a gas supply unit 20 , a processing vessel unit 30 , and a gas storage unit 40 .

[0014] [Substrate Supporting Section 10 ] The substrate supporting section 10 includes a stage 11 , an outer ring 12 , lifting pins 13 , lifting members 14 , a support member 15 , a lifting plate 16 , a bellows 17 , and a lifting mechanism 18 .

[0015] (Stage 11) The stage 11 carries a wafer W, which is an example of a substrate to be processed. The wafer W is, for example, a semiconductor wafer. The stage 11 is made of, for example, aluminum nitride or quartz. The stage 11 has a flat, disk-like shape.

[0016] The stage 11 includes a heater 11a therein. The heater 11a is supplied with power from a power supply 11b. The heater 11a is capable of heating the wafer W to a temperature of, for example, 430°C by receiving power from the power supply 11b.

[0017] The stage 11 may include an internal electrostatic chuck, which electrostatically attracts and fixes the wafer W placed on the stage 11.

[0018] (Outer Ring 12) The outer ring 12 is provided around the stage 11. The outer ring 12 is made of, for example, aluminum nitride or quartz.

[0019] (Lifting pins 13) The lifting pins 13 lift the wafer W from the mounting surface of the stage 11 when the wafer W is loaded or unloaded. The substrate support part 10 includes, for example, three lifting pins 13. The number of lifting pins 13 is not limited to three and may be determined as appropriate.

[0020] The lift pins 13 have flat heads and rod-like portions provided below the heads. When a wafer W is placed on the heads of the lift pins 13, the heads come into contact with the upper surface of the stage 11 and are stopped there. The rod-like portions of the lift pins 13 are provided so as to penetrate the stage 11 and protrude from the bottom surface of the stage 11. The lift pins 13 are raised and lowered by the lift members 14 (described later) which raise and lower the lower ends of the lift pins 13.

[0021] (Lifting member 14) The lifting member 14 raises and lowers the lifting pins 13. The lifting member 14 is provided below the lifting pins 13. When the lifting member 14 rises, it comes into contact with the lower ends of the lifting pins 13. When the lifting member 14 rises further while in contact with the lower ends of the lifting pins 13, the lifting pins 13 rise, and the heads of the lifting pins 13 protrude from the mounting surface of the stage 11. Then, when the lifting member 14 descends while the heads of the lifting pins 13 protrude, the lower ends of the lifting pins 13 descend. Then, when the lower ends of the lifting pins 13 descend, the lifting pins 13 descend, and the heads of the lifting pins 13 come into contact with the mounting surface of the stage 11.

[0022] (Supporting Member 15) The supporting member 15 connects the stage 11 and the lifting plate 16. The supporting member 15 penetrates the bottom of the processing vessel part 30, more specifically, the bottom of a lower vessel 31, which will be described later. The supporting member 15 is connected to the lifting plate 16.

[0023] (Lift Plate 16) The lift plate 16 is raised and lowered by the lift mechanism 18. The lift plate 16 raises and lowers the support member 15. When the lift plate 16 raises and lowers the support member 15, the stage 11 rises and lowers.

[0024] (Bellows 17) The bellows 17 connects the bottom of the processing vessel part 30, more specifically, the bottom of a lower vessel 31 (described later), to the lift plate 16. The bellows 17 ensures airtightness inside the processing vessel part 30.

[0025] (Elevating Mechanism 18) The elevating mechanism 18 elevates the elevating plate 16. When the elevating mechanism 18 elevates the elevating plate 16, the stage 11 elevates.

[0026] [Gas Supply Unit 20] The gas supply unit 20 supplies gas to the processing space. The gas supply unit 20 includes a support member 21 and a shower head 22.

[0027] (Supporting Member 21) The supporting member 21 holds the shower head 22. The supporting member 21 also covers and closes the upper side of the processing vessel part 30.

[0028] (Shower Head 22) The shower head 22 supplies a source gas, a reaction gas, and a purge gas into the processing space SP. The shower head 22 supplies the source gas, the reaction gas, and the purge gas introduced from the gas storage unit 40 to the processing space SP via the gas supply port 20a in the gas supply unit 20.

[0029] The shower head 22 has a gas diffusion chamber 22 a and a plurality of gas inlets 22 b. The source gas, reaction gas, and purge gas supplied from the gas supply port 20 a pass through the gas diffusion chamber 22 a and are supplied to the processing space SP from the plurality of gas inlets 22 b, respectively. The plurality of gas inlets 22 b are provided in a central portion 22 C near the center of the shower head 22.

[0030] The shower head 22 has an outer edge portion 22P that protrudes downward from a central portion 22C where a plurality of gas inlets 22b are provided. The outer edge portion 22P is provided opposite the outer ring 12 of the substrate support 10.

[0031] A processing space SP is formed between the shower head 22 and the stage 11. Specifically, the processing space SP is a space surrounded by the lower surface of the central portion 22C, the inner surface of the outer edge portion 22P, and the upper surface of the stage 11.

[0032] [Processing Container Section 30] The processing container section 30 includes the substrate support section 10 therein. The processing container section 30 includes a lower container 31, an upper container 32, and a connecting member 33.

[0033] (Lower Container 31) The lower container 31 holds the substrate support 10. The lower container 31 has a cylindrical shape with a bottom surface portion that serves as a bottom plate. The bottom surface portion of the lower container 31 has a through-hole through which the support member 15 passes. The lift plate 16 is attached to the bottom plate of the lower container 31 via a bellows 17.

[0034] A purge gas supply port 35a is provided on the bottom plate of the lower vessel 31. A purge gas such as nitrogen gas is supplied from a purge gas supply unit 35 through the purge gas supply port 35a.

[0035] (Upper Vessel 32) The upper vessel 32 is provided above the lower vessel 31. An exhaust space SPe is formed between the upper vessel 32 and the outer side surface of the shower head 22. The exhaust mechanism 34 exhausts each of the source gas, reaction gas, and purge gas in the processing space SP through the exhaust space SPe.

[0036] (Connecting Member 33) The connecting member 33 mounts the support member 21 of the gas supply unit 20. By mounting the support member 21 on the connecting member 33, a sealed space is formed between the gas supply unit 20 and the processing vessel 30.

[0037] [Gas Storage Unit 40] The gas storage unit 40 stores the source gas, the reactive gas, and the purge gas, and supplies the stored source gas, reactive gas, and purge gas to the gas supply unit 20.

[0038] The gas storage unit 40 includes a raw material gas storage unit 41A that stores a raw material gas, and a control valve 42A that controls the supply of the raw material gas from the raw material gas storage unit 41A to the gas supply unit 20. The gas storage unit 40 also includes a reactive gas storage unit 41B that stores a reactive gas, and a control valve 42B that controls the supply of the reactive gas from the reactive gas storage unit 41B to the gas supply unit 20. The gas storage unit 40 also includes a purge gas storage unit 41C that stores a purge gas, and a control valve 42C that controls the supply of the purge gas from the purge gas storage unit 41C to the gas supply unit 20.

[0039] The gas storage unit 40 supplies the source gas, the reaction gas, and the purge gas to the gas supply unit 20 via the pipes 43 .

[0040] Here, as an example, a case where a titanium nitride (TiN) film layer is formed on a processing substrate will be described. When forming a titanium nitride film on a processing substrate, titanium chloride (TiCl ４ ) gas is used. The source gas storage unit 41A may store and supply a carrier gas for carrying the source gas, such as nitrogen gas or argon gas, together with the source gas. When forming a titanium nitride film on a processing substrate, titanium chloride (TiCl ４), ammonia (NH ３ ) gas is used. The reactive gas storage unit 41B may store and supply a carrier gas for transporting the reactive gas, such as nitrogen gas or argon gas, together with the reactive gas. Furthermore, when a titanium nitride film is formed on the processing substrate, hydrogen (H ２ The purge gas storage unit 41C stores and supplies nitrogen gas mixed with hydrogen, that is, gas mixed with hydrogen, as the purge gas.

[0041] Next, the purging method according to the first embodiment will be specifically described using the film forming apparatus 1. Fig. 2 is a flow chart illustrating the purging method according to the first embodiment.

[0042] (Step S10) First, as a pre-processing step, the film forming apparatus 1 carries in a wafer W, which is an example of a processing substrate, and places it on the stage 11. Then, the film forming apparatus 1 reduces the pressure in the processing space SP to a vacuum atmosphere.

[0043] Furthermore, the film forming apparatus 1 adjusts the distance between the stage 11 and the shower head 22 to a predetermined distance. Specifically, the film forming apparatus 1 adjusts the distance H1 between the outer ring 12 and the outer edge 22P of the shower head 22 to 1 millimeter or less.

[0044] The gap H1 is preferably 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.25 mm or less. The gap H1 is desirably at least 0.1 mm or more in order to exhaust gas from the processing space SP.

[0045] (Step S20) Next, the film forming apparatus 1 supplies a source gas into the processing space SP. The film forming apparatus 1 supplies, as the source gas, titanium chloride (TiCl ４ ) gas is supplied to the processing space SP.

[0046] (Step S30) Next, the film forming apparatus 1 supplies a purge gas into the processing space SP to purge the source gas. The film forming apparatus 1 supplies, for example, a gas mixed with hydrogen as the purge gas into the processing space SP.

[0047] (Step S40) Next, the film forming apparatus 1 supplies a reactive gas into the processing space SP. The film forming apparatus 1 supplies, for example, ammonia (NH ３ ) gas is supplied to the processing space SP.

[0048] (Step S50) Next, the film forming apparatus 1 supplies a purge gas into the processing space SP in order to purge the reactive gas. The film forming apparatus 1 supplies, for example, a gas mixed with hydrogen as the purge gas into the processing space SP.

[0049] (Step S60) Next, the film forming apparatus 1 determines whether the process has been repeated a predetermined number of times. If the process has been repeated a predetermined number of times (YES in step S60), the film forming apparatus 1 proceeds to step S70. If the process has not been repeated a predetermined number of times (NO in step S60), the film forming apparatus 1 returns to step S20 and repeats the process.

[0050] (Step S70) Next, as a post-processing step, the film forming apparatus 1 returns the pressure in the processing space SP to atmospheric pressure, and then unloads the processed wafer W placed on the stage 11.

[0051] Using the case of forming a titanium nitride film layer as an example, the electrical resistivity when the purging method according to the first embodiment is used in the film forming apparatus 1 will be described. FIG. 3 is a diagram illustrating the relationship between the distance and the electrical resistivity in the purging method according to the first embodiment. The horizontal axis of FIG. 3 represents the distance between the stage 11 and the shower head 22. Specifically, the horizontal axis of FIG. 3 represents the distance H1 (unit: millimeters (mm)) between the outer ring 12 of the stage 11 and the outer edge 22P of the shower head 22. The vertical axis of FIG. 3 represents the electrical resistivity (unit: microohm-centimeters (μΩcm)) of the formed titanium nitride film. Line L11 represents the results when a mixed gas of hydrogen gas and nitrogen gas is used as the purge gas, and line L12 represents the results when nitrogen gas is used as the purge gas.

[0052] As shown in Figure 3, in the purging method according to this embodiment, by using a gas mixed with hydrogen as the purge gas, the electrical resistivity of the formed titanium nitride film can be reduced. Furthermore, in the purging method according to this embodiment, by narrowing the gap H1, the electrical resistivity of the formed titanium nitride film can be reduced. In particular, as shown in Figure 3, in the purging method according to this embodiment, the gap H1 is preferably 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.25 mm or less.

[0053] The inventors have found that when purging with hydrogen, simply increasing the amount of hydrogen only reduces the degree to which electrical resistivity can be reduced. Figure 4 is a diagram illustrating the gas pressure when purging gas. Figure 4 is a diagram showing the pressure of hydrogen gas and nitrogen gas when purging is repeated. The horizontal axis represents time (unit: arbitrary unit), and the vertical axis represents pressure (unit: arbitrary unit). In Figure 4, line L21 represents the hydrogen gas pressure, and line L22 represents the nitrogen gas pressure.

[0054] As shown in FIG. 4, the pressure fluctuation of hydrogen gas (line L21) is larger than the pressure fluctuation of nitrogen gas (line L22). More specifically, the pressure of hydrogen gas decreases faster than that of nitrogen gas. In other words, hydrogen gas is exhausted quickly. Since hydrogen gas is exhausted quickly, it is thought that the time hydrogen remains on the processed substrate is short. Therefore, in order to reduce the electrical resistivity of a titanium nitride film formed using hydrogen gas, it is necessary to suppress the exhaust of hydrogen gas and increase the time hydrogen remains on the processed substrate.

[0055] Therefore, the inventors discovered that when purging with a gas mixed with hydrogen, the electrical resistivity can be reduced by narrowing the gap between the stage 11 and the shower head 22 to suppress the exhaust of hydrogen gas and allow hydrogen to remain near the processing substrate for a long period of time.

[0056] According to the purging method of the first embodiment, the electrical resistivity of the film to be formed can be reduced by narrowing the gap between the stage and the shower head.

[0057] Furthermore, according to the purging method of the first embodiment, the surface roughness of the formed film can be reduced by narrowing the gap between the stage and the shower head. Figure 5 is a diagram illustrating the relationship between the gap and the surface roughness in the purging method of the first embodiment.

[0058] 5, the haze of a titanium nitride (TiN) film having a thickness of 10 nanometers is used as an index of surface roughness, and the vertical axis of FIG. 5 represents the haze (unit: ppm).

[0059] Ex1 on the horizontal axis of Fig. 5 indicates the results when a mixed gas of hydrogen gas and nitrogen gas was used as the purge gas and the distance H1 between the outer ring 12 and the outer edge 22P of the showerhead 22 was set to 0.4 millimeters. Ex2 on the horizontal axis of Fig. 5 indicates the results when a mixed gas of hydrogen gas and nitrogen gas was used as the purge gas and the distance H1 was set to 3 millimeters. Also, as reference examples, Ref1 on the horizontal axis of Fig. 5 indicates the results when a mixed gas of nitrogen gas was used as the purge gas and the distance H1 was set to 0.4 millimeters, and Ref2 indicates the results when the distance H1 was set to 3 millimeters.

[0060] 5, in the purging method according to the first embodiment, the surface roughness can be reduced by using a mixed gas of oxygen gas and nitrogen gas as the purge gas. Furthermore, in the purging method according to the first embodiment, the surface roughness can be further reduced by narrowing the gap between the stage and the shower head.

[0061] In the above example, the distance between the stage 11 and the shower head 22 is specified by the distance H1 between the outer ring 12 and the outer edge 22P. However, the distance between the stage 11 and the central portion 22C of the shower head 22 may be adjusted to a predetermined distance. FIG. 6 is a diagram illustrating the distance in the purging method according to the first embodiment. In the table in FIG. 6, the first column shows the distance H1 between the outer ring 12 and the outer edge 22P. In the table in FIG. 6, the second column shows the distance H2 between the stage 11 and the central portion 22C of the shower head 22. In the table in FIG. 6, the third column shows the ratio of the volume of the processing space SP to a value of 100% when the distance H1 is 3 millimeters.

[0062] 6, the film forming apparatus 1 may be specified by the distance H2 between the stage 11 and the center 22C of the shower head 22, instead of the distance H1 between the outer ring 12 and the outer edge 22P. For example, the film forming apparatus 1 may be configured so that the distance H2 between the stage 11 and the center 22C of the shower head 22 is 8.6 millimeters or less. The distance H2 is preferably 8.6 millimeters or less, more preferably 8.1 millimeters or less, and even more preferably 7.85 millimeters or less. The distance H2 is preferably at least 0.1 millimeters or more in order to process the wafer W in the processing space SP.

[0063] <<Purge Method According to Second Embodiment>> A purge method according to a second embodiment will be described. In the purge method according to the second embodiment, the distance between the stage and the shower head is changed when purging is performed. The purge method according to the second embodiment is a purge method for a film formation apparatus including a substrate support unit including a stage that supports a processing substrate and an outer ring provided around the stage, and a gas supply unit that includes a shower head that is provided facing the processing substrate and that supplies a processing gas and a purge gas. In the purge method according to the second embodiment, a first distance between the outer ring and the outer edge of the shower head when purging is performed by supplying a gas mixed with hydrogen from the gas supply unit as a purge gas is narrower than a second distance between the outer ring and the outer edge of the shower head when film formation is performed by supplying a source gas from the gas supply unit.

[0064] The purging method according to the second embodiment will be described using the film forming apparatus 1. Fig. 7 is a flow chart illustrating the purging method according to the second embodiment.

[0065] Note that for steps S20, S30, S40, S50, S60 and S70, the description of the purging method according to the first embodiment can be referred to, and detailed description thereof will be omitted here.

[0066] (Step S10) First, as a pre-processing step, the film forming apparatus 1 carries in a wafer W, which is an example of a processing substrate, and places it on the stage 11. Then, the film forming apparatus 1 reduces the pressure in the processing space SP to a vacuum atmosphere.

[0067] Furthermore, the film forming apparatus 1 adjusts the distance between the stage 11 and the shower head 22 to a predetermined distance. Specifically, the film forming apparatus 1 adjusts the distance H1 between the outer ring 12 and the outer edge 22P of the shower head 22 to 3 millimeters.

[0068] (Step S45) After step S40, the film forming apparatus 1 narrows the gap between the stage 11 and the shower head 22. That is, the gap (first gap) between the stage 11 and the shower head 22 when the purge gas is being supplied is narrower than the gap (second gap) between the stage 11 and the shower head 22 when the source gas and the reactive gas are being supplied, respectively. Specifically, the film forming apparatus 1 sets the gap H1 between the outer ring 12 and the outer edge 22P of the shower head 22 to 1 millimeter or less. The gap when purging is performed is the same as that in the purge method according to the first embodiment.

[0069] (Step S55) After step S50, the film formation apparatus 1 widens the gap between the stage 11 and the shower head 22. The film formation apparatus 1 adjusts the gap between the stage 11 and the shower head 22 to a predetermined gap. Specifically, the film formation apparatus 1 adjusts the gap H1 between the outer ring 12 and the outer edge 22P of the shower head 22 to 3 millimeters.

[0070] According to the purging method of the second embodiment, the electrical resistivity of the formed film can be reduced by narrowing the gap between the stage and the shower head when purging. Furthermore, according to the purging method of the second embodiment, the surface roughness of the formed film can be reduced by narrowing the gap between the stage and the shower head. Furthermore, according to the purging method of the second embodiment, the formation of the film can be promoted by widening the gap between the stage and the shower head when supplying the processing gas, thereby reducing the variation in film thickness.

[0071] In the above example, the gap between the stage and the shower head is narrowed in the reaction gas purging step of step S50, but the gap between the stage and the shower head may also be narrowed in the source gas purging step.

[0072] The purging method and film forming apparatus according to the present disclosure should be considered to be illustrative in all respects and not restrictive. The above-described embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above-described embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0073] This application claims priority from basic patent application No. 2023-136064, filed with the Japan Patent Office on August 24, 2023, the entire contents of which are incorporated herein by reference.

[0074] REFERENCE SIGNS LIST 1 Film forming apparatus 10 Substrate support 11 Stage 12 Outer ring 20 Gas supply section 22 Shower head 22C Center section 22P Outer edge section 40 Gas storage section 41A Source gas storage section 41B Reaction gas storage section 41C Purge gas storage section H1, H2 Spacing SP Processing space W Wafer

Claims

1. A purging method for a film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided facing the processing substrate and supplying a processing gas and a purge gas, wherein when a gas mixed with hydrogen is supplied from the gas supply unit as the purge gas for purging, the distance between the outer ring and the outer edge of the shower head is 1 millimeter or less.

2. The purging method according to claim 1, wherein the distance is 0.5 millimeters or less.

3. The purging method according to claim 2, wherein the interval is 0.25 millimeters or less.

4. A purging method for a film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided facing the processing substrate and supplying a processing gas and a purge gas, wherein when a gas mixed with hydrogen is supplied from the gas supply unit as the purge gas for purging, the distance between the stage and the center of the shower head is 8.6 millimeters or less.

5. The purging method according to claim 4, wherein the distance is 8.1 millimeters or less.

6. The purging method according to claim 5, wherein said interval is 7.85 millimeters or less.

7. The purging method according to any one of claims 1 to 6, wherein the interval is an interval when purging is performed after ammonia gas is supplied as the processing gas.

8. The purging method according to any one of claims 1 to 6, wherein the processing gas includes a raw material gas containing titanium chloride gas and a reaction gas containing ammonia gas.

9. A purging method for a film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas, wherein a first distance between the outer ring and an outer edge of the shower head when purging by supplying a gas mixed with hydrogen from the gas supply unit as the purge gas is narrower than a second distance between the outer ring and the outer edge when processing gas is supplied from the gas supply unit.

10. The purging method according to claim 9, wherein the first distance is 1 millimeter or less.

11. The method of claim 10, wherein the first distance is 0.5 millimeters or less.

12. The method of claim 11, wherein the first distance is 0.25 millimeters or less.

13. The purging method according to any one of claims 9 to 12, wherein the first interval is an interval during purging after ammonia gas is supplied as the processing gas.

14. The purging method according to any one of claims 9 to 12, wherein the processing gas includes a source gas containing titanium chloride gas and a reaction gas containing ammonia gas.

15. A film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas, wherein when a gas mixed with hydrogen is supplied from the gas supply unit as the purge gas for purging, the distance between the outer ring and the outer edge of the shower head is 1 millimeter or less.

16. A film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas, wherein when a gas mixed with hydrogen is supplied from the gas supply unit as the purge gas for purging, the distance between the stage and the center of the shower head is 8.6 millimeters or less.

17. A film formation apparatus comprising: a substrate support unit including a stage for supporting a processing substrate and an outer ring provided around the stage; and a gas supply unit including a shower head provided opposite the processing substrate and supplying a processing gas and a purge gas, wherein a first distance between the outer ring and an outer edge of the shower head when a gas mixed with hydrogen is supplied from the gas supply unit as the purge gas for purging is narrower than a second distance between the outer ring and the outer edge when a raw material gas is supplied from the gas supply unit.

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