Film forming method and film forming apparatus

Abstract

To provide a technology capable of reducing the occurrence of seams when filling a recessed portion with a silicon nitride film.SOLUTION: A film formation method according to an embodiment of the present disclosure includes the steps of (a) preparing a substrate having a recess on its surface, (b) forming a silicon nitride film in the recess, (c) forming an amorphous silicon film in the recess, (d) removing the amorphous silicon film, and (e) filling the recess with a silicon nitride film after step (d), and the amorphous silicon film is formed to have a lower step coverage than the silicon nitride film, and step (c) is performed one or more times during step (b).SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] A technique has been disclosed in which a silicon nitride film is embedded in a trench formed in the surface of a substrate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-139306 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can reduce the occurrence of seams when filling a recess with a silicon nitride film. [Means for solving the problem]

[0005] A film formation method according to one embodiment of the present disclosure includes the steps of: (a) preparing a substrate having a recess on its surface; (b) forming a silicon nitride film in the recess; (c) forming an amorphous silicon film in the recess; (d) removing the amorphous silicon film; and (e) filling the recess with a silicon nitride film after step (d), wherein the amorphous silicon film is formed to have a lower step coverage than the silicon nitride film, and step (c) is performed one or more times during step (b). [Effects of the Invention]

[0006] According to the present disclosure, it is possible to reduce the occurrence of seams when filling recesses with a silicon nitride film. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view (1) showing a film forming method according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view (2) showing the film forming method according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view (3) showing the film forming method according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view (4) showing the film forming method according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view (5) showing the film forming method according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view (6) showing the film forming method according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view (7) showing the film forming method according to the embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing the film forming method according to the embodiment. [Figure 9] FIG. 1 is a diagram showing an example of the relationship between the number of ALD cycles and the thickness of a silicon nitride film. [Figure 10] 1 is a vertical cross-sectional view showing a film forming apparatus according to an embodiment. [Figure 11] 1 is a horizontal cross-sectional view showing a film forming apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding reference numerals are used to designate the same or corresponding members or components, and redundant descriptions will be omitted.

[0009] [Film formation method] A film forming method according to an embodiment will be described with reference to Figures 1 to 9. Figures 1 to 8 are cross-sectional views showing a film forming method according to an embodiment.

[0010] First, as shown in FIG. 1, a substrate 101 is prepared. The substrate 101 is, for example, a semiconductor substrate such as a silicon substrate. The substrate 101 has a recess 102 on its surface. The recess 102 includes a bottom surface 102a, an inner surface 102b, and an upper surface 102c. The recess 102 is, for example, a trench. The recess 102 may also be a hole. An insulating film 103 may be provided on the surface of the substrate 101. The insulating film 103 covers the bottom surface 102a, the inner surface 102b, and the upper surface 102c. The insulating film 103 is, for example, a silicon oxide film.

[0011] 2, a silicon nitride film 104 is formed in the recess 102. The silicon nitride film 104 is formed to cover the bottom surface 102a, the inner side surface 102b, and the upper surface 102c. The silicon nitride film 104 may be formed conformally along the bottom surface 102a, the inner side surface 102b, and the upper surface 102c.

[0012] The silicon nitride film 104 can be formed by atomic layer deposition (ALD), for example, by alternately supplying dichlorosilane (DCS) and ammonia (NH3) to the substrate 101 maintained at a first temperature. When the silicon nitride film 104 is formed by atomic layer deposition, the silicon nitride film 104 is likely to be formed conformally along the bottom surface 102a, the inner side surface 102b, and the top surface 102c. The first temperature may be 450°C or higher and 650°C or lower, for example, 550°C. In atomic layer deposition, thermal nitridation is preferably used. When thermal nitridation is used, nitridation of the amorphous silicon film 105, described below, by ammonia can be reduced compared to when plasma nitridation is used. In atomic layer deposition, purging may be performed between the supply of dichlorosilane and the supply of ammonia. Dichlorosilane is an example of a first silicon-containing gas, and ammonia is an example of a nitriding gas.

[0013] After a predetermined time has elapsed, the deposition of the silicon nitride film 104 is stopped. The predetermined time may be a time during which the silicon nitride film 104 does not close the opening of the recess 102.

[0014] Next, as shown in FIG. 3, an amorphous silicon film 105 is formed in the recess 102. The amorphous silicon film 105 is formed so as to have a lower step coverage than the silicon nitride film 104. The step coverage is defined as the value (percentage) obtained by dividing the thickness of the film formed on the inner side surface 102b at the middle position in the depth direction of the recess 102 by the thickness of the film formed on the inner side surface 102b at the upper end position in the depth direction of the recess 102. The amorphous silicon film 105 may be formed so as to cover the upper part of the inner side surface 102b and the upper surface 102c. In this case, when the silicon nitride film 104 is formed after the amorphous silicon film 105 is formed, the silicon nitride film is likely to be formed from above the bottom surface 102a. The amorphous silicon film 105 may contain oxygen as an impurity. When the amorphous silicon film 105 contains oxygen in the film, the number of ALD cycles X2, which will be described later, is greater than when the amorphous silicon film 105 does not contain oxygen in the film.

[0015] The amorphous silicon film 105 can be formed by chemical vapor deposition (CVD), for example, by simultaneously supplying disilane (SiH) and dinitrogen monoxide (NO) to the substrate 101 maintained at a first temperature. When the amorphous silicon film 105 is formed by chemical vapor deposition, the amorphous silicon film 105 is likely to be formed so as to cover the upper portion of the inner side surface 102b and the upper surface 102c. Maintaining the first temperature improves productivity because the silicon nitride film 104 and the amorphous silicon film 105 can be successively formed without changing the temperature. The chemical vapor deposition may include simultaneously supplying disilane and dinitrogen monoxide to the substrate 101, followed by supplying dinitrogen monoxide to the substrate 101 without supplying disilane. In this case, oxygen (O) is adsorbed on the surface of the amorphous silicon film 105, increasing the number of ALD cycles X2, which will be described later.

[0016] When a predetermined time elapses, the formation of the amorphous silicon film 105 is stopped. The predetermined time may be a time during which the amorphous silicon film 105 is not formed on the silicon nitride film 104 on the bottom surface 102a. Disilane is an example of the second silicon-containing gas, and nitrous oxide is an example of the impurity-containing gas.

[0017] Next, the formation of the silicon nitride film 104 in the recess 102 is resumed. FIG. 9 is a diagram showing an example of the relationship between the number of ALD cycles and the thickness of the silicon nitride film 104. In FIG. 9, the horizontal axis represents the number of ALD cycles, and the vertical axis represents the thickness of the silicon nitride film 104. In FIG. 9, the solid line indicates the case where the silicon nitride film 104 is formed on the silicon nitride film 104, and the broken line indicates the case where the silicon nitride film 104 is formed on the amorphous silicon film 105. Let X1 be the number of ALD cycles until the formation of the silicon nitride film 104 on the silicon nitride film 104 is started after the resumption of the formation of the silicon nitride film 104. Also, let X2 be the number of ALD cycles until the formation of the silicon nitride film 104 on the amorphous silicon film 105 is started after the resumption of the formation of the silicon nitride film 104. In this case, as shown in FIG. 9, the relationship of X1 < X2 is satisfied. For this reason, before the silicon nitride film 104 is formed on the amorphous silicon film 105, the silicon nitride film 104 is selectively formed on the silicon nitride film 104. As a result, as shown in FIG. 4, a silicon nitride film having a substantially V shape is formed in the recess 102. In particular, by setting the number of ALD cycles when forming the silicon nitride film 104 to X2 or less, the silicon nitride film 104 can be formed only on the silicon nitride film 104 without forming the silicon nitride film 104 on the amorphous silicon film 105.

[0018] When a predetermined time elapses, the formation of the silicon nitride film 104 is stopped. The predetermined time may be a time during which the silicon nitride film 104 is not formed on the amorphous silicon film 105. That is, the formation of the amorphous silicon film 105 may be started before the silicon nitride film 104 is formed on the amorphous silicon film 105.

[0019] 5, an amorphous silicon film 105 is formed in the recess 102. The amorphous silicon film 105 is formed in the same manner as in the case shown in FIG.

[0020] After a predetermined time has elapsed, the deposition of the amorphous silicon film 105 is stopped. The predetermined time may be a time during which the amorphous silicon film 105 is not deposited on the silicon nitride film 104 on the bottom surface 102a.

[0021] Next, the formation of the silicon nitride film 104 in the recess 102 is resumed. The silicon nitride film 104 is formed in the same manner as in the case shown in Fig. 4. As a result, as shown in Fig. 6, the silicon nitride film 104 is formed from a deep position to a shallow position in the recess 102, and the silicon nitride film 104 having a substantially V-shape is formed.

[0022] After a predetermined time has elapsed, the deposition of the silicon nitride film 104 is stopped. The predetermined time may be a time during which the silicon nitride film 104 is not deposited on the amorphous silicon film 105. In this manner, the deposition of the amorphous silicon film 105 is performed twice during the deposition of the silicon nitride film 104. For example, when the aspect ratio of the recess 102 is low, the deposition of the amorphous silicon film 105 may be performed only once during the deposition of the silicon nitride film 104. For example, when the aspect ratio of the recess 102 is high, the deposition of the amorphous silicon film 105 is preferably performed twice or more during the deposition of the silicon nitride film 104.

[0023] 7, the amorphous silicon film 105 is selectively etched and removed. For example, the amorphous silicon film 105 can be selectively etched and removed by supplying an etching gas, which etches the amorphous silicon film 105 at a rate faster than the rate at which it etches the silicon nitride film 104, to the substrate 101 maintained at the first temperature. By maintaining the substrate 101 at the first temperature, the amorphous silicon film 105 can be continuously removed after the formation of the silicon nitride film 104 without changing the temperature of the substrate 101, thereby improving productivity. The etching gas is, for example, chlorine (Cl2).

[0024] After a predetermined time has elapsed, etching of the amorphous silicon film 105 is stopped. The predetermined time may be longer than the time it takes for the amorphous silicon film 105 to be removed.

[0025] Next, as shown in FIG. 8, the recess 102 is filled with a silicon nitride film 104. The silicon nitride film 104 is formed in the same manner as in the case shown in FIG. 4. In this case, the silicon nitride film 104 can be filled on the silicon nitride film 104 having a substantially V-shape. This makes it possible to reduce the occurrence of voids and seams when filling the recess 102 with the silicon nitride film 104.

[0026] As described above, according to the film forming method of the embodiment, first, when filling the recess 102 with the silicon nitride film 104, the step of forming the amorphous silicon film 105 in the recess 102 is performed one or more times during the step of forming the silicon nitride film in the recess 102. The amorphous silicon film 105 is formed so as to have a lower step coverage than the silicon nitride film 104. In this case, the silicon nitride film 104 is formed from a deep position to a shallower position in the recess 102, and the silicon nitride film 104 having a substantially V-shape is formed.

[0027] Next, the amorphous silicon film 105 is removed, and the recess 102 is filled with the silicon nitride film 104. In this case, the silicon nitride film 104 can be filled on the silicon nitride film 104 having a substantially V-shape. Therefore, the occurrence of voids and seams when the recess 102 is filled with the silicon nitride film 104 can be reduced.

[0028] [Film forming equipment] The film forming apparatus 1 according to the embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a vertical cross-sectional view showing the film forming apparatus 1 according to the embodiment. Fig. 11 is a horizontal cross-sectional view showing the film forming apparatus 1 according to the embodiment.

[0029] The film forming apparatus 1 is a batch type apparatus that processes a plurality of substrates W at once. The substrates W are, for example, semiconductor wafers. The film forming apparatus 1 includes a processing chamber 10, a gas supply unit 30, an exhaust unit 40, a heating unit 50, and a control unit 90.

[0030] The processing vessel 10 can have its interior depressurized. The processing vessel 10 accommodates a substrate W. The processing vessel 10 has an inner tube 11 and an outer tube 12. The inner tube 11 has a cylindrical shape with a ceiling and an open lower end. The outer tube 12 has a cylindrical shape with a ceiling and an open lower end that covers the outside of the inner tube 11. The inner tube 11 and the outer tube 12 are made of a heat-resistant material such as quartz. The inner tube 11 and the outer tube 12 have a double-tube structure arranged coaxially.

[0031] A storage section 13 for storing a gas supply pipe is formed along the longitudinal direction (vertical direction) on the side wall of the inner pipe 11. For example, a part of the side wall of the inner pipe 11 is protruded outward to form a convex section 14, and the inside of the convex section 14 is formed as the storage section 13.

[0032] A rectangular opening 15 is formed along the longitudinal direction in the side wall of the inner tube 11. The opening 15 faces the storage portion 13.

[0033] The opening 15 is a gas exhaust port formed so as to be able to exhaust gas from the inner tube 11. The length of the opening 15 is the same as the length of the boat 16, or is formed so as to extend in the vertical direction and be longer than the length of the boat 16.

[0034] The lower end of the processing vessel 10 is supported by a cylindrical manifold 17. The manifold 17 is made of, for example, stainless steel. A flange 18 is formed at the upper end of the manifold 17. The flange 18 supports the lower end of the outer tube 12. A seal member 19, such as an O-ring, is provided between the flange 18 and the lower end of the outer tube 12. This keeps the inside of the outer tube 12 airtight.

[0035] An annular support member 20 is provided on the inner wall of the upper portion of the manifold 17. The support member 20 supports the lower end of the inner tube 11. A lid member 21 is airtightly attached to the opening at the lower end of the manifold 17 via a sealing member 22 such as an O-ring. This airtightly closes the opening at the lower end of the processing vessel 10, i.e., the opening of the manifold 17. The lid member 21 is made of, for example, stainless steel.

[0036] A rotating shaft 24 is provided in the center of the lid 21, penetrating through the lid 21 via a magnetic fluid seal 23. The lower part of the rotating shaft 24 is rotatably supported by an arm 25A of an elevation mechanism 25 made up of a boat elevator.

[0037] A rotating plate 26 is provided at the upper end of the rotating shaft 24. A boat 16 holding substrates W is placed on the rotating plate 26 via a quartz heat retention stand 27. The boat 16 rotates by rotating the rotating shaft 24. The boat 16 moves up and down integrally with the lid 21 by raising and lowering the lifting mechanism 25. This allows the boat 16 to be inserted into and removed from the processing vessel 10. The boat 16 can be accommodated within the processing vessel 10. The boat 16 holds multiple (e.g., 50 to 150) substrates W in a shelf-like manner. The boat 16 holds the multiple substrates W approximately horizontally with spacing between them in the vertical direction.

[0038] The gas supply unit 30 is configured to be able to introduce various process gases into the inner pipe 11. The gas supply unit 30 includes a DCS supply unit 31, a disilane supply unit 32, an ammonia supply unit 33, a nitrous oxide supply unit 34, and a chlorine supply unit 35.

[0039] The DCS supply unit 31 includes a gas supply pipe 31a inside the processing vessel 10 and a supply flow path 31b outside the processing vessel 10. A DCS source 31c, a mass flow controller 31d, and a valve 31e are installed in supply flow path 31b, in that order from upstream to downstream in the gas flow direction. The supply timing of dichlorosilane from the DCS source 31c is controlled by the valve 31e, and the flow rate is adjusted to a predetermined value by the mass flow controller 31d. Dichlorosilane flows from supply flow path 31b into the gas supply pipe 31a and is then discharged from the gas supply pipe 31a into the processing vessel 10.

[0040] The disilane supply unit 32 includes a gas supply pipe 32a inside the processing vessel 10 and a supply flow path 32b outside the processing vessel 10. A disilane source 32c, a mass flow controller 32d, and a valve 32e are installed in supply flow path 32b, in that order from upstream to downstream in the gas flow direction. The supply timing of disilane from the disilane source 32c is controlled by the valve 32e, and the flow rate is adjusted to a predetermined value by the mass flow controller 32d. Disilane flows from supply flow path 32b into the gas supply pipe 32a and is then discharged from the gas supply pipe 32a into the processing vessel 10.

[0041] The ammonia supply unit 33 includes a gas supply pipe 33a inside the processing vessel 10 and a supply flow path 33b outside the processing vessel 10. An ammonia source 33c, a mass flow controller 33d, and a valve 33e are installed in the supply flow path 33b, in this order from upstream to downstream in the gas flow direction. Thus, the supply timing of ammonia from the ammonia source 33c is controlled by the valve 33e, and the flow rate is adjusted to a predetermined value by the mass flow controller 33d. The ammonia flows from the supply flow path 33b into the gas supply pipe 33a and is discharged from the gas supply pipe 33a into the processing vessel 10.

[0042] The nitrous oxide supply unit 34 includes a gas supply pipe 34a inside the processing vessel 10 and a supply flow path 34b outside the processing vessel 10. A nitrous oxide source 34c, a mass flow controller 34d, and a valve 34e are installed in supply flow path 34b, in that order from upstream to downstream in the gas flow direction. The supply timing of the nitrous oxide from the nitrous oxide source 34c is controlled by the valve 34e, and the flow rate is adjusted to a predetermined value by the mass flow controller 34d. The nitrous oxide flows from supply flow path 34b into the gas supply pipe 34a and is then discharged from the gas supply pipe 34a into the processing vessel 10.

[0043] The chlorine supply unit 35 includes a gas supply pipe 35a inside the processing vessel 10 and a supply flow path 35b outside the processing vessel 10. A chlorine source 35c, a mass flow controller 35d, and a valve 35e are installed in supply flow path 35b, in this order from upstream to downstream in the gas flow direction. Thus, the supply timing of chlorine from the chlorine source 35c is controlled by the valve 35e, and the mass flow controller 35d adjusts the flow rate to a predetermined value. The chlorine flows from supply flow path 35b into the gas supply pipe 35a and is discharged from the gas supply pipe 35a into the processing vessel 10.

[0044] The gas supply pipes 31a, 32a, 33a, 34a, and 35a are fixed to the manifold 17. The gas supply pipes 31a, 32a, 33a, 34a, and 35a are made of, for example, quartz. The gas supply pipes 31a, 32a, 33a, 34a, and 35a extend linearly in the vertical direction near the inner pipe 11, and then bend in an L-shape within the manifold 17 and extend horizontally, thereby penetrating the manifold 17. The gas supply pipes 31a, 32a, 33a, 34a, and 35a are arranged side by side along the circumferential direction of the inner pipe 11 and are formed at the same height.

[0045] A plurality of discharge ports 31f, 32f, 33f, 34f, and 35f are provided in the gas supply pipes 31a, 32a, 33a, 34a, and 35a at portions located within the inner pipe 11. The discharge ports 31f, 32f, 33f, 34f, and 35f are formed at predetermined intervals along the extension direction of the gas supply pipes 31a, 32a, 33a, 34a, and 35a. The discharge ports 31f, 32f, 33f, 34f, and 35f discharge gas horizontally toward the substrate W from the radially outer side of the substrate W. The discharge ports 31f, 32f, 33f, 34f, and 35f discharge gas parallel to the main surface of the substrate W. The intervals between the discharge ports are set to be the same as the intervals between the substrates W held in the boat 16, for example. The height position of each discharge port is set to be, for example, the midpoint between two vertically adjacent substrates W. In this case, each outlet can efficiently supply gas to the opposing surfaces between adjacent substrates W.

[0046] The gas supply unit 30 may mix multiple types of gases and discharge the mixed gas from a single gas supply pipe. The gas supply pipes 31a, 32a, 33a, 34a, and 35a may have different shapes and arrangements. The gas supply unit 30 may further include a gas supply pipe that supplies another gas, such as an inert gas.

[0047] The exhaust unit 40 exhausts gas that is discharged from the inner tube 11 through the opening 15 and then discharged from a gas outlet 41 via a space P1 between the inner tube 11 and the outer tube 12. The gas outlet 41 is formed on the side wall of the upper part of the manifold 17, above the support unit 20. An exhaust flow path 42 is connected to the gas outlet 41. A pressure adjustment valve 43 and a vacuum pump 44 are sequentially disposed in the exhaust flow path 42, so that the inside of the processing chamber 10 can be exhausted.

[0048] The heating unit 50 is provided around the outer tube 12. The heating unit 50 is provided, for example, on the base plate 28. The heating unit 50 has a cylindrical shape so as to cover the outer tube 12. The heating unit 50 includes, for example, a heating element, and heats each substrate W in the processing vessel 10.

[0049] The control unit 90 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), etc. The control unit 90 executes various control operations described in this specification by executing instruction codes stored in a memory or by being a circuit designed for a specific application.

[0050] [Operation of the Film Forming Apparatus] The operation of the film forming apparatus 1 when carrying out the film forming method according to the embodiment will be described.

[0051] First, the control unit 90 controls the lifting mechanism 25 to load the boat 16 holding multiple substrates W into the processing vessel 10, and then airtightly closes the opening at the bottom of the processing vessel 10 with the lid 21. Next, the control unit 90 controls the exhaust unit 40 to reduce the pressure inside the processing vessel 10, and controls the heating unit 50 to adjust the temperature of the substrates W to a first temperature. Each substrate W may be the substrate 101 described above.

[0052] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to perform the film formation method according to the embodiment on each substrate W accommodated in the processing vessel 10. As a result, the recesses 102 of each substrate 101 are filled with the silicon nitride film 104.

[0053] Next, the control unit 90 increases the pressure inside the processing vessel 10 to atmospheric pressure and decreases the temperature inside the processing vessel 10 to the unloading temperature, and then controls the lifting mechanism 25 to unload the boat 16 from the processing vessel 10 .

[0054] As described above, the film formation method according to the embodiment can be carried out in the film formation apparatus 1. In the above example, the formation of the silicon nitride film 104, the formation of the amorphous silicon film 105, the removal of the amorphous silicon film 105, and the filling of the silicon nitride film 104 are performed within the same processing chamber 10 of the film formation apparatus 1, but some of these steps may be performed in separate apparatuses.

[0055] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0056] In the above embodiment, the first silicon-containing gas is dichlorosilane, but the present disclosure is not limited thereto. The first silicon-containing gas may be dichlorosilane, hexachlorodisilane, trichlorosilane, monochlorosilane, trisilylamine, diiodosilane, triiodosilane, or a combination thereof.

[0057] In the above embodiment, the second silicon-containing gas is disilane, but the present disclosure is not limited to this. The second silicon-containing gas may be disilane, trisilane, or a combination thereof.

[0058] In the above embodiment, the nitriding gas is ammonia, but the present disclosure is not limited to this. The nitriding gas may be ammonia, diazene (NH), hydrazine (NH), monomethylhydrazine (CH(NH)NH), triethylamine, diethylamine, trimethylamine, dimethylamine, or a combination thereof.

[0059] In the above embodiment, the impurity-containing gas is nitrous oxide, but the present disclosure is not limited thereto. The impurity-containing gas may be an oxygen-containing gas, a phosphorus-containing gas, or a combination thereof. Nitrous oxide is an example of an oxygen-containing gas. Phosphine (PH3) may be used as the phosphorus-containing gas.

[0060] In the above embodiment, the etching gas is chlorine, but the present disclosure is not limited to this. The etching gas may be chlorine, hydrogen chloride (HCl), bromine (Br), hydrogen bromide (HBr), iodine (I), hydrogen iodide (HI), or a combination thereof.

[0061] In the above embodiment, the processing vessel is a vessel with a double-pipe structure, but the present disclosure is not limited to this. For example, the processing vessel may be a vessel with a single-pipe structure.

[0062] In the above embodiment, the film formation apparatus is described as an apparatus that supplies gas from a gas supply pipe arranged along the longitudinal direction of the processing vessel and exhausts the gas from a slit arranged opposite the gas supply pipe, but the present disclosure is not limited to this. For example, the film formation apparatus may be an apparatus that supplies gas from a gas supply pipe arranged along the longitudinal direction of a boat and exhausts the gas from an exhaust port arranged above the boat. Also, for example, the film formation apparatus may be an apparatus that supplies processing gas from a gas supply pipe arranged below the processing vessel and exhausts the gas from an exhaust port arranged above the processing vessel.

[0063] In the above embodiment, a batch-type apparatus that processes multiple substrates at once has been described, but the present disclosure is not limited to this. For example, the film formation apparatus may be a single-wafer-type apparatus that processes substrates one by one. For example, the film formation apparatus may be a semi-batch-type apparatus that processes the substrates by rotating a turntable on which multiple substrates are placed, causing each substrate to revolve and repeatedly passing through a process gas supply region arranged along the radial direction of the turntable. [Explanation of symbols]

[0064] 101 Substrate 102 recess 104 Silicon nitride film 105 Amorphous silicon film

Claims

1. (a) providing a substrate having a recess on its surface; (b) forming a silicon nitride film in the recess; (c) forming an amorphous silicon film in the recess; (d) removing the amorphous silicon film; (e) after the step (d), filling the recess with a silicon nitride film; and the amorphous silicon film is formed to have a lower step coverage than the silicon nitride film; The step (c) is carried out one or more times during the step (b). Film formation method.

2. The step (c) is carried out two or more times during the step (b). The film forming method according to claim 1 .

3. The step (c) is initiated before the silicon nitride film is formed on the amorphous silicon film in the step (b). The film forming method according to claim 2 .

4. The step (b) includes alternately supplying a first silicon-containing gas and a nitriding gas to the substrate; The film forming method according to claim 1 .

5. the step (c) is stopped before the amorphous silicon film is formed on the silicon nitride film formed on the bottom surface of the recess; The film forming method according to claim 1 .

6. the step (c) includes simultaneously supplying a second silicon-containing gas and an impurity-containing gas to the substrate; The film forming method according to claim 1 .

7. the step (c) includes, after the simultaneous supplying, supplying the impurity-containing gas to the substrate without supplying the second silicon-containing gas; The film forming method according to claim 6.

8. The impurity-containing gas is a gas containing oxygen or phosphorus. The film forming method according to claim 7 .

9. The step (d) includes supplying an etching gas to the substrate; the etching gas is a gas that etches the amorphous silicon film at a rate higher than the rate at which it etches the silicon nitride film; The film forming method according to claim 1 .

10. The etching gas is chlorine (Cl ２ ) The film forming method according to claim 9 .

11. The steps (b) to (e) are performed in the same processing vessel. The film forming method according to claim 1 .

12. A processing vessel; a gas supply unit that supplies a processing gas into the processing vessel; A control unit; Equipped with The control unit (a) providing a substrate having a recess on its surface; (b) forming a silicon nitride film in the recess; (c) forming an amorphous silicon film in the recess; (d) removing the amorphous silicon film; (e) after the step (d), filling the recess with a silicon nitride film; Run the amorphous silicon film is formed to have a lower step coverage than the silicon nitride film; The step (c) is carried out one or more times during the step (b). Film deposition equipment.

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