Method and system for depositing tungsten films

Abstract

To form a tungsten film while suppressing formation of a void in a recess.SOLUTION: A method of forming a tungsten film includes a step for forming a titanium nitride base film containing silicon and a step for forming a tungsten film on a recess on which the titanium nitride base film is formed. In the step for forming a titanium nitride base film, deposition of titanium nitride conducted by alternately repeating supply of a titanium-containing gas and supply of a nitriding gas to a substrate with a recess formed and deposition of silicon nitride conducted by alternately repeating supply of a silicon-containing gas and supply of a nitriding gas to the substrate are alternately repeated. In the step for forming a tungsten film on a recess, a raw material gas containing a tungsten raw material and a reactant gas to deposit tungsten by reacting with the raw material gas are alternately and repeatedly supplied to the substrate. The rate of supplying the silicon-containing gas is regulated so that the titanium nitride base film has a higher content of the silicon in the opening side than in the deep part side of the recess.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to methods and systems for depositing tungsten films. [Background technology]

[0002] In semiconductor devices, for example, in order to form wiring on a substrate, a structure in which a metal is embedded in a recess is often formed. For example, a tungsten film is known as such a metal film.

[0003] Patent Document 1 describes a technique in which a barrier film such as a TiN film or a TiSiN film is formed on the surface of an interlayer insulating film in which recesses such as trenches and holes are formed, and a tungsten film is formed on the surface of the barrier film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-145409 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides techniques for depositing tungsten films while reducing the formation of voids within recesses. [Means for solving the problem]

[0006] The method of forming a tungsten film on a substrate of the present disclosure includes the steps of: A lateral groove is formed so that an opening is opened on a side surface of the longitudinal groove formed on the surface of the substrate, and the width of the opening is 30 nm or less and the aspect ratio is within a range of 20 to 40. A recess was formed The abovea step of alternately repeating the supply of a titanium-containing gas, which is a metal source-containing gas containing a titanium source, and the supply of a nitriding gas to the substrate to deposit titanium nitride, and the supply of a silicon-containing gas, which is a metal source-containing gas containing a silicon source, and the supply of a nitriding gas to the substrate to deposit silicon nitride, thereby forming a titanium nitride underlayer containing silicon; subsequently, alternately and repeatedly supplying to the substrate a source gas containing a tungsten source and a reaction gas which reacts with the source gas to precipitate tungsten, thereby forming a tungsten film so that the tungsten is embedded in the recess in which the titanium nitride base film has been formed; The flow rate of the silicon-containing gas supplied is adjusted so that the titanium nitride undercoat film has a higher silicon content on the opening side of the recess than on the inner side. Effect of the Invention

[0007] According to the present disclosure, a tungsten film can be formed while suppressing the formation of voids in the recess. [Brief description of the drawings]

[0008] [Figure 1] 1 is an enlarged vertical cross-sectional view of a surface of a wafer to which a film forming method according to the present disclosure is applied; [Diagram 2] FIG. 2 is a first process chart showing the film forming method of the present disclosure. [Diagram 3] FIG. 2 is a second process diagram showing the film forming method of the present disclosure. [Figure 4] FIG. 4 is a third process diagram showing the film forming method of the present disclosure. [Diagram 5] FIG. 4 is a fourth process diagram showing the film forming method of the present disclosure. [Figure 6] FIG. 5 is a fifth process diagram showing the film forming method of the present disclosure. [Figure 7] FIG. 6 is a sixth process diagram showing the film forming method of the present disclosure. [Figure 8] 1 is a plan view of a film formation system for performing a film formation method according to the present disclosure. [Figure 9] 2 is a vertical sectional side view of a TiSiN film forming apparatus provided in the film forming system. FIG. [Figure 10] 1 is a graph showing the change in thickness of tungsten nuclei versus the number of supply cycles of source gas. [Figure 11] 1 is a graph showing a change in the thickness of a tungsten film versus the number of supply cycles of a source gas. [Figure 12] 1 is a graph showing the Si content in a TiSiN film versus the flow rate of a silicon-containing gas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present disclosure relates to a technique for forming a tungsten film on a semiconductor wafer as a substrate, thereby filling recesses formed on the surface of the wafer with tungsten. An example of a method for forming a tungsten film according to the present disclosure will be described. As shown in FIG. 1, a semiconductor wafer (hereinafter referred to as "wafer"), which is a substrate, has a silicon oxide layer 101 formed on its surface, on which a vertical groove 102 is formed. Furthermore, a plurality of lateral grooves 200 are formed in the vertical groove 102 so as to be aligned in the thickness direction of the wafer 100. These lateral grooves 200 have openings that open on the sidewall surfaces of the vertical groove 102, and are formed as recesses extending laterally from the openings. The width of the openings of the lateral grooves 200 is 30 nm or less, for example 20 nm. In the film forming method according to the present disclosure, a film is formed on the surface of the wafer 100, thereby filling tungsten into these lateral grooves 200.

[0010] Meanwhile, the structure of the wafer 100 is becoming finer. For this reason, even in the wafer 100 having the configuration illustrated in FIG. 1, it may be necessary to fill the lateral groove 200 with tungsten, which has a large aspect ratio and a depth longer than the width of the opening. However, when a film is formed so as to fill the lateral groove 200 with tungsten, which has a narrow opening, the opening may be blocked by the tungsten film being formed first on the opening side. As a result, a gap may remain in the lateral groove 200, which may cause an increase in wiring resistance. The film forming method according to the present disclosure aims to form a tungsten film while suppressing the formation of a gap in the lateral groove 200.

[0011] In the tungsten film forming method according to the present disclosure, before tungsten is filled into the lateral grooves 200, a base film of titanium nitride (TiN) film (TiSiN film) containing silicon (Si) is formed on the inner surface of the lateral grooves 200 by ALD (Atomic Layer Deposition).

[0012] First, the wafer 100 shown in FIG. 1 is heated to 350 to 750° C., and titanium tetrachloride (TiCl ), which is a titanium raw material, is applied to the wafer 100. 4 The titanium-containing gas (hereinafter referred to as "TiCl") is a metal raw material-containing gas. 4 As a result, TiCl 4 Gas is introduced to fill the lateral groove 200 with TiCl 4 Next, nitrogen (N 2 ) gas to remove remaining TiCl 4 The gas is then removed. The wafer 100 is then treated with ammonia (NH 3 ) gas was supplied to remove TiCl adsorbed on the lateral groove 200. 4 As a result, the TiCl 4 is nitrided and TiN precipitates on the surface of the lateral groove 200. 2 The NH remaining in the processing vessel 10 is purged with gas. 3The gas is removed. The above-described cycle of precipitating TiN is alternately repeated X times, for example, 1 to 100 times, to form a TiN layer 201 on the inner surface of the lateral groove 200 as shown in FIG. 2. In the present disclosure, for example, TiCl 4 Gas supply and NH 3 For convenience of expression, the term "alternately and repeatedly supplying" may also be used to refer to the case where the gases are supplied once each (the same applies to the supply of other gases).

[0013] Next, a silicon-containing gas (hereinafter referred to as "DCS gas"), which is a metal source-containing gas containing dichlorosilane (DCS) as a silicon source, is supplied to the wafer 100 to adsorb DCS to the TiN layer 201. 2 The remaining DCS gas is removed by purging with gas. In this DCS gas supply process, the amount of DCS molecules adsorbed can be adjusted by controlling the supply amount and supply time of DCS gas.

[0014] In the lateral groove 200 having the structure shown in Fig. 2, the DCS gas easily enters the opening, and the flow rate of DCS flowing through the opening tends to be large. On the other hand, the gas does not easily enter the inner part of the lateral groove 200, and the flow rate of DCS flowing through this region tends to be small. In this case, as shown in the evaluation test described later, there is a positive correlation between the flow rate of DCS gas and the amount of adsorption of DCS molecules (Fig. 12). By utilizing this characteristic, as shown in Fig. 3, it is possible to increase the adsorption density of DCS 202 molecules adsorbed on the TiN layer 201 near the opening of the lateral groove 200, while decreasing the adsorption density of DCS 202 on the inner side.

[0015] Next, the wafer 100 is subjected to nitriding gas, NH 3Gas is supplied to nitride the DCS 202 adsorbed to the TiN layer 201. This causes silicon nitride (SiN) to precipitate on the surface of the TiN layer 201. At this time, since the density of DCS 202 adsorbed on the opening side of the lateral groove 200 is high, a large amount of SiN is formed on the opening side of the lateral groove 200 and a small amount of SiN is formed on the inner side. The above-described cycle of forming SiN is repeated Y times, for example, 1 to 10 times, to form a desired amount of SiN on the surface of the TiN layer 201.

[0016] By alternately repeating the above-mentioned deposition of TiN and deposition of SiN, a titanium nitride undercoat film (TiSiN film) 203 containing Si can be formed. As described above, SiN is deposited so that there is more Si204 on the opening side of the lateral groove 200 and less Si on the inner side. As a result, as shown in FIG. 4, the TiSiN film 203 formed in the lateral groove 200 contains more Si204 on the opening side of the lateral groove 200 and less Si204 toward the inner side. That is, the opening side of the lateral groove 200 contains more Si204 than the inner side. In addition, in Figures 3 to 7, Si 204 is expressed in particle shape for the sake of convenience in order to show the concentration distribution of Si in the TiSiN film 203, but the size of Si 204 in these figures does not indicate the actual grain size of Si in the TiSiN film 203.

[0017] Next, a tungsten film is formed on the surface of the TiSiN film 203 formed in the lateral grooves 200. In the film forming method according to the present disclosure, a nucleation layer made of tungsten nuclei is first formed on the surface of the TiSiN film 203 by the ALD method. The wafer 100 with the TiSiN film 203 formed in the lateral grooves 200 shown in FIG. 4 is heated to 150 to 450° C., and tungsten hexafluoride (WF 6 ) containing raw gas (hereinafter referred to as "WF 6 As a result, WF 6 Next, the wafer 100 is subjected to a reducing gas B2 H 6 (diborane) gas is supplied. This causes the WF adsorbed on the surface of the TiSiN film 203 to 6 The above-mentioned WF on the wafer 100 is reduced to form a layer of tungsten in islands. 6 Adsorption of and B 2 H 6 The gas supply is alternately repeated for three cycles, for example, within a range of 1 to 5 cycles. In the above cycle, WF 6 The gas corresponds to the raw gas for nucleation, and B 2 H 6 The gas corresponds to a reactive gas for nucleation.

[0018] As a result, a tungsten nucleation layer 205 is formed on the surface of the TiSiN film 203 as shown in FIG. 5. As shown in the verification test described later, as the content of Si204 in the TiSiN film 203 increases, the thickness of the nucleation layer 205 formed on the TiSiN film 203 tends to become thinner, that is, the nucleation layer 205 tends to grow more difficultly. Therefore, as shown in FIG. 5, the amount of the nucleation layer 205 formed is small near the opening of the lateral groove 200 where the content of Si204 in the TiSiN film 203 is high. On the other hand, the amount of the nucleation layer 205 formed is large at the inner side of the lateral groove 200 where the content of Si204 in the TiSiN film 203 is high. Note that the island-like nucleation layer 205 shown in FIG. 5 is expressed in a particle shape for convenience in order to express the distribution of the amount of formation, but does not indicate the actual size of the island of the nucleation layer 205.

[0019] Next, a tungsten film 206 is formed by the ALD method. The wafer 100 is heated to 300 to 550° C., and a tungsten source, WF 6 Feed gas containing WF 6 This supplies WF gas to the inside of the horizontal groove 200. 6 The gas enters and WF 6 Next, hydrogen (H 2 ) gas is supplied to remove the WF adsorbed in the lateral groove 200. 6This causes tungsten to precipitate in the lateral grooves 200. 6 Adsorption of H 2 The gas supply is alternately repeated for 450 cycles within a range of 1 to 500 cycles, for example. As a result, the tungsten film 206 is formed so as to be laminated on the nucleation layer 205.

[0020] As shown in the verification test described later, when the content of Si 204 in the TiSiN film 203 is small, the amount of the nucleation layer 205 tends to increase and the film thickness tends to be thick. Furthermore, in the region where a large amount of the nucleation layer 205 is formed, the film formation speed of the tungsten film 206 becomes faster. Therefore, the tungsten film 206 grows easily on the inner side of the lateral groove 200, whereas the tungsten film 206 grows relatively less on the opening side.

[0021] Therefore, as shown in Fig. 6, the thickness of the tungsten film 206 increases first at the inner part of the lateral groove 200. As a result, the thickness of the film increases first at the opening side of the lateral groove 200, and the phenomenon that the opening side is blocked can be suppressed. Therefore, when the deposition of the tungsten film 206 is continued, tungsten can be filled so that voids are unlikely to remain in the lateral groove 200 as shown in Fig. 7. In the case of the wafer 100 having the configuration shown in Fig. 1, tungsten is also filled in the vertical groove 102 in conjunction with the filling of the lateral groove 200 with tungsten.

[0022] Furthermore, as shown in the verification test described later, by increasing the number of cycles of forming the nucleation layer 205 and increasing the thickness of the nucleation layer 205, the difference in the film formation speed of the tungsten film 206 becomes smaller regardless of the content of Si 204 in the TiSiN film 203. Therefore, the film thickness of the nucleation layer 205 is preferably 3 nm or less. To further reliably increase the difference in the film formation speed of the tungsten film 206, the film thickness of the nucleation layer 205 is preferably less than 1 nm.

[0023] As an example of the configuration of the lateral grooves 200, the aspect ratio (depth / opening diameter) can be in the range of 20 to 40. In this case, it is considered that a sufficient difference in the supply flow rate of DCS gas can be formed between the opening and the inner part of the lateral grooves 200 by supplying DCS gas at a flow rate in the range of 1 to 200 sccm, for example. As a result, the concentration distribution of Si in the TiSiN film 203 described with reference to Figs. 3 to 7 can be formed.

[0024] Here, the Ti-containing gas is titanium tetrabromide (TiBr 4 ) and titanium tetraiodide (TiI 4 ) may be used. Furthermore, an organic titanium source such as TDMAT (tetrakisdimethylaminotitanium) may be used. The nitriding gas may be monomethylhydrazine (MMH). The Si-containing gas may be, for example, HCD (disilicon hexachloride), SiH 4 (Monosilane) and the like can be used.

[0025] The source gas for the nucleation layer 205 containing tungsten and the tungsten film 206 is, for example, tungsten hexachloride (WCl 6 ) gas. Gases consisting of hydrogen and elements other than hydrogen include SiH 4 (silane), NH 3 It may be (ammonia) gas. The recess may be a vertical groove with an opening on the surface of the wafer 100, or a film formed by filling the vertical groove with tungsten.

[0026] Next, a configuration example of a substrate processing system for carrying out the above-mentioned method for forming a tungsten film will be described. The substrate processing system is configured as a vacuum processing apparatus, for example, a multi-chamber system. As shown in FIG. 8, the vacuum processing apparatus is, for example, a N 2The atmospheric pressure transfer chamber 62 is elongated and maintained at atmospheric pressure by gas. A load port 61 is provided in front of the atmospheric pressure transfer chamber 62 for transferring the wafer 100 to, for example, a transfer container C containing the wafer 100. Reference numeral 67 in FIG. 8 denotes an opening and closing door provided on the front wall of the atmospheric pressure transfer chamber 62. A transfer arm 65 for transferring the wafer 100 is provided inside the atmospheric pressure transfer chamber 62. An alignment chamber 66 for adjusting the orientation and eccentricity of the wafer 100 is provided on the left side wall of the atmospheric pressure transfer chamber 62 as viewed from the load port 61 side.

[0027] On the opposite side of the load port 61 in the normal pressure transfer chamber 62, for example, two load lock chambers 63 are arranged side by side, and switch the internal atmosphere between a normal pressure atmosphere and a vacuum atmosphere while the wafer 100 is waiting. A vacuum transfer chamber 64 is arranged on the inner side of the load lock chamber 63 as viewed from the normal pressure transfer chamber 62 side. The above-mentioned load lock chamber 63 is connected to the vacuum transfer chamber 64 via a gate valve 70.

[0028] The vacuum transfer chamber 64 is also provided with a TiSiN film forming device 7 that forms a TiSiN film 203 as a base film on the wafer 100. The vacuum transfer chamber 64 is further provided with a nucleation layer forming device 8 that forms a nucleation layer 205 on the surface of the TiSiN film 203, and a tungsten film forming device 9 that forms a tungsten film 206 and fills the lateral grooves 200 with tungsten. In this example, one TiSiN film forming device 7 and one nucleation layer forming device 8 are connected to the vacuum transfer chamber 64, and two tungsten film forming devices 9 are connected. The vacuum transfer chamber 64 is provided with a transfer arm 69, which transfers the wafer 100 between each of the load lock chambers 63, the TiSiN film forming device 7, the nucleation layer forming device 8, and the tungsten film forming device 9.

[0029] The vacuum processing apparatus is provided with a control unit 90, which is, for example, a computer. The control unit 90 includes a program, a memory, a data processing unit including a CPU, and the like. The program includes commands (each step) for sending control signals from the control unit 90 to each part of the vacuum processing apparatus and for progressing each step for forming, for example, the TiSiN film 203, the nucleation layer 205, and the tungsten film 206. The program is stored in a storage unit of a computer storage medium, for example, a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), and installed in the control unit 90.

[0030] Next, the TiSiN film forming apparatus 7 will be described with reference to FIG. 9. The TiSiN film forming apparatus 7 includes a processing vessel 10 for accommodating a wafer 100, and a sidewall of the processing vessel 10 has an inlet / outlet 11 for loading / unloading the wafer 100, which can be opened and closed by a gate valve 12. An annular exhaust duct 13 is disposed in the upper portion of the sidewall of the processing vessel 10, and has a slit 131 formed along the inner circumferential surface, for example, and an exhaust port 132 formed in the outer wall. 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 10. The processing vessel 10 is connected to a vacuum exhaust section 17, for example, a vacuum pump, by a vacuum exhaust path 16 via the exhaust port 132, and the pressure in the processing vessel 10 is controlled by a pressure adjustment section (not shown).

[0031] A mounting table 2 for supporting the wafer 100 horizontally is provided inside the processing vessel 10, and a heater 21 for heating the wafer 100 is embedded in the mounting table 2. The mounting table 2 is configured to be able to be raised and lowered by a lifting mechanism 24 via a support member 241 between a processing position (shown by a solid line in FIG. 9) and a transfer position for the wafer 100 therebelow (also shown by a two-dot chain line). Three support pins 25 (only two are shown) for transferring the wafer 100 are provided below the mounting table 2 inside the processing vessel 10. These support pins 25 are provided to be able to be raised and lowered by a lifting mechanism 26 so as to protrude and sink with respect to the upper surface of the mounting table 2 at the transfer position. In the figure, reference numeral 22 denotes a through hole for the support pin 25, and reference numerals 27 and 28 denote bellows which separate the atmosphere inside the processing vessel 10 from the outside air and expand and contract in accordance with the lifting and lowering movements of the mounting table 2 and the support pin 25, respectively.

[0032] A showerhead 3 for supplying a processing gas into the processing vessel 10 in a shower-like manner is provided in the processing vessel 10, facing the mounting table 2. The showerhead 3 includes a main body 31 fixed to the ceiling wall 14 of the processing vessel 10, and a shower plate 32 connected below the main body 31, and defines a gas diffusion space 33 inside. The shower plate 32 has gas discharge holes 34 formed therein, and a gas supply system 4 is connected to the gas diffusion space 33 via a gas introduction hole 35.

[0033] The gas supply system 4 is a titanium tetrachloride (TiCl 4 a first gas supply unit for supplying dichlorosilane (SiH 2 Cl 2 A second gas supply unit is provided to supply a nitriding gas (NH 3 ). A nitriding gas supply unit is also provided to supply a nitriding gas. In this example, ammonia (NH 4 ). 3 ) gas is used.

[0034] The first gas supply unit is TiCl 4 The supply source 41 and the supply path 411 are included. For example, TiCl 4A flow rate regulator 412, a storage tank 413, and a valve V1 are provided in the gas supply path 411 from the upstream side. The second gas supply part includes a DCS supply source 42 and a supply path 421. For example, a flow rate regulator 422, a storage tank 423, and a valve V2 are provided in the DCS gas supply path 421 from the upstream side. The nitriding gas supply unit is NH 3 The supply source 43 and the supply path 431 are included. For example, NH 3 In the gas supply path 431, from the upstream side, a flow rate regulator 432, a storage tank 433, and a valve V3 are provided.

[0035] These, TiCl 4 Gas, DCS gas, NH 3 The gases are temporarily stored in storage tanks 413, 423, and 433, respectively, and are then pressurized to a predetermined pressure in the storage tanks 413, 423, and 433 before being supplied into the processing vessel 10. The supply and stop of the gases from the storage tanks 413, 423, and 433 to the processing vessel 10 is controlled by opening and closing valves V1, V2, and V3.

[0036] Furthermore, the gas supply system 4 supplies an inert gas, such as nitrogen (N 2 In this example, N 2 is supplied from the supply 44. 2 The gas is TiCl 4 The purge gas source 44 supplies TiCl 4 The gas supply line 411 is connected to the downstream side of the valve V1. The N 2 The gas is a purge gas for DCS, and a supply source 45 is connected to the downstream side of the valve V2 in the gas supply path 421 of the DCS gas via a purge gas supply path 451. Further, N 2 Gas is NH 3 The purge gas is supplied via a purge gas supply line 461 as NH 3 The gas is connected to the downstream side of the valve V3 in the gas supply path 431. In addition, in Fig. 1, reference numerals 442, 452, and 462 respectively indicate flow rate adjustment units, and reference numerals V4, V5, and V6 respectively indicate valves.

[0037] The nucleation layer forming apparatus 8 and the tungsten film forming apparatus 9 are configured almost similarly to the TiSiN film forming apparatus 7, except that the gases supplied to the wafer 100 are different and the heating temperatures of the wafer 100 are different. The nucleation layer forming device 8 is configured to supply WF together with a purge gas into the processing vessel 10. 6 The gas supply system 4 supplies gas together with the purge gas. 2 H 6 The gas supply system 4 supplies gas. The mounting table 2 is further configured to heat the wafer 100.

[0038] In addition, the tungsten film forming apparatus 9 supplies WF together with the purge gas into the processing vessel 10. 6 The gas supply system 4 supplies gas, and H 2 The gas supply system 4 supplies gas. The mounting table 2 is further configured to heat the wafer 100.

[0039] In such a vacuum processing apparatus, for example, a transfer container C storing a wafer 100 having the surface structure shown in FIG. 1 is transferred into a load port 61 of the vacuum processing apparatus. The wafer 100 is then taken out of the transfer container C and transferred into an alignment chamber 66 via a normal pressure transfer chamber 62. After alignment is performed in the alignment chamber 66, the wafer W is transferred into a vacuum transfer chamber 64 via a load lock chamber 63. The wafer is then transferred by a transfer arm 69 to a TiSiN film forming apparatus 7, where a film formation process of a TiSiN film 203 is performed by the ALD method described above. The wafer 100 is then taken out by the transfer arm 69 and transferred to a nucleation layer forming apparatus 8, where a process of forming a nucleation layer 205 is performed by the ALD method. The wafer 100 is then taken out by the transfer arm 69 and transferred to a tungsten film forming apparatus 9, where a film formation process of a tungsten film 206 is performed by the ALD method.

[0040] The wafer 100 with the tungsten film 206 thus embedded in the lateral grooves 200 is transferred to the load lock chamber 63 in a vacuum atmosphere by the second transfer arm 69. Next, after the load lock chamber 63 is switched to an air atmosphere, the wafer 100 is returned, for example, to the original transfer container C by the transfer arm 65.

[0041] Here, the configuration of the vacuum processing apparatus is not limited to the example shown in FIG. 8. For example, the nucleation layer forming apparatus 8 and the tungsten film forming apparatus 9 may be a common apparatus. In this case, the wafer 100 on which the TiSiN film 203 has been formed is carried into the tungsten film forming apparatus, and the wafer 100 is heated to form the nucleation layer 205. Next, the temperature of the mounting table 2 is increased to heat the wafer 100 while forming the tungsten film on the wafer 100. However, as described above, the heating temperatures of the wafer 100 when the nucleation layer 205 and the tungsten film 206 are formed are different. Therefore, by forming the nucleation layer forming apparatus 8 and the tungsten film forming apparatus 9 as separate apparatuses, the time required for adjusting the temperature of the mounting table 2 can be reduced.

[0042] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0043] [Verification test 1] The following test was carried out to verify the effectiveness of the tungsten film forming method according to the present disclosure. [TiSiN film 1] 8, a TiSiN film 203, a nucleation layer 205, and a tungsten film 206 were laminated in this order on a test wafer 100 having no recesses formed thereon according to the tungsten film formation method shown in the embodiment. This was used as Test 1. In the formation of the TiSiN film 203, the ratio of the number of cycles X for forming the TiN layer 201 to the number of cycles Y for forming SiN was set to X:Y=1:1. [TiSiN film 2] An example of TiSiN film 2 was prepared by carrying out the same process as for TiSiN film 1, except that in the deposition of TiSiN film 203, X:Y=5:1 was used. [TiN film 3] A TiN film 3 was prepared by carrying out the same process as for the TiSiN film 2, except that no SiN was formed in the step of forming the TiSiN film, that is, only a TiN layer 201 was formed.

[0044] For each of the TiSiN films 1, 2, and TiN film 3, the number of cycles during the formation of the nucleation layer 205 was set to 5, 10, and 15, and the thickness of the formed nucleation layer 205 was measured. At this time, for Tests 1 to 3, the change in thickness of the nucleation layer 205 with respect to the number of cycles during the formation of the nucleation layer 205 is shown in FIG.

[0045] In addition, for the TiSiN films 1 and 2 and the TiN film 3, the number of cycles in forming the nucleation layer 205 was set to 2, 3, 4, 6, 8, and 10, and the thickness (total thickness) of the nucleation layer and the tungsten film was measured when the tungsten film 206 was formed in the same manner as in the embodiment. The change in the total thickness of the tungsten film versus the number of cycles in forming the nucleation layer 205 for the TiSiN films 1 and 2 and the TiN film 3 is shown in FIG.

[0046] 10, when the number of cycles in forming the nucleation layer 205 reaches about 15, there is almost no difference in the thickness of the nucleation layer 205 between the TiSiN films 1 and 2 and the TiN film 3. However, when the number of cycles is 5, it can be seen that the thickness of the nucleation layer 205 in Test 1 is thinner. Furthermore, as shown in FIG. 11, by setting the number of cycles during the formation of the nucleation layer 205 to 6 or less, the nucleation layer 205 of the TiSiN film 1 and the tungsten film 206 are hardly formed.

[0047] Therefore, it can be said that the deposition rate of the tungsten film 206 can be adjusted by forming an appropriate amount of the nucleation layer 205 while changing the Si content in the TiSiN film 203 that is the undercoat film.

[0048] [Verification test 2] In addition, when forming the TiSiN film 203, the film was formed on a test wafer 100 having no recesses formed thereon by setting the flow rate of DCS gas to 20, 30, 80, and 150 sccm, and the Si content in the TiSiN film 203 was measured. A graph of the Si content in the TiSiN film 203 versus the DCS flow rate is shown in FIG.

[0049] 12, it can be seen that the Si content increases as the flow rate of DCS gas increases. Therefore, it can be said that in a recess formed in wafer 100, by creating a difference in the supply flow rate of DCS gas between the opening and the back of the recess, a difference in the Si content in TiSiN film 203 can be created between the opening and the back of the recess. [Explanation of symbols]

[0050] 100 wafers 200 Yokomizo 201 TiN layer 203 TiSiN film 205 Nucleation layer 206 Tungsten Film

Claims

1. 1. A method for depositing a tungsten film on a substrate, comprising: a step of alternately repeating the steps of supplying a titanium-containing gas, which is a metal source containing gas containing a titanium source, and supplying a nitriding gas to the substrate, the metal source containing gas containing a silicon source, and supplying a silicon-containing gas, which is a metal source containing gas containing a silicon source, and supplying a nitriding gas to the substrate, the silicon nitride being deposited by alternately repeating the steps of supplying a silicon-containing gas, which is a metal source containing gas containing a silicon source, and supplying a nitriding gas to the substrate, the silicon nitride being deposited by alternately repeating the steps of supplying a silicon-containing gas, which is a metal source containing gas containing a silicon source, and supplying a nitriding gas to the substrate, the silicon nitride being deposited by alternately repeating the steps of supplying a silicon-containing gas, which is a metal source containing gas containing a silicon source, and supplying a silicon nitride ... subsequently, alternately and repeatedly supplying to the substrate a source gas containing a tungsten source and a reaction gas which reacts with the source gas to precipitate tungsten, thereby forming a tungsten film so that the tungsten is embedded in the recess in which the titanium nitride base film has been formed; a supply flow rate of the silicon-containing gas is adjusted so that the titanium nitride undercoat film has a higher silicon content on the opening side of the recess than on the inner side.

2. 2. The method according to claim 1, further comprising, between the step of forming the titanium nitride undercoat film and the step of forming the tungsten film, a step of alternately and repeatedly supplying to the substrate a nucleation source gas containing a tungsten source material and a nucleation reaction gas which reacts with the nucleation gas to precipitate tungsten which serves as a nucleus when forming the tungsten film, thereby forming a tungsten nucleation layer on a surface of the titanium nitride undercoat film.

3. The method of claim 2 , wherein the tungsten nuclei are formed to a thickness of 3 nm or less.

4. 4. The method of claim 1, wherein the silicon-containing gas is dichlorosilane.

5. In a system for depositing a tungsten film on a substrate, an apparatus for depositing a titanium nitride undercoat film containing silicon by alternately repeating the supply of a titanium-containing gas, which is a metal raw material containing gas containing a titanium raw material, and the supply of a nitriding gas to deposit titanium nitride, and the supply of a silicon-containing gas, which is a metal raw material containing gas containing a silicon raw material, and the supply of a nitriding gas to deposit silicon nitride, on the substrate, which has a recess formed thereon, the recess being a lateral groove formed so that an opening opens on a side of the longitudinal groove formed on the surface of the substrate, the opening having a width of 30 nm or less and an aspect ratio within a range of 20 to 40; and an apparatus for alternately and repeatedly supplying a source gas containing tungsten and a reaction gas which reacts with the source gas to precipitate tungsten to the substrate on which the titanium nitride base film has been formed, to form a tungsten film such that tungsten is embedded in recesses in which the titanium nitride base film has been formed; The apparatus for forming the titanium nitride base film is a system that performs control to adjust the supply flow rate of the silicon-containing gas so that the titanium nitride base film has a higher silicon content on the opening side of the recess than on the inner side.

6. 6. The system according to claim 5, further comprising an apparatus for alternately and repeatedly supplying a nucleation source gas containing a tungsten source and a nucleation reaction gas which reacts with the nucleation gas to precipitate tungsten that will become nuclei when forming the tungsten film to the substrate after the titanium nitride undercoat film is formed and before the tungsten film is formed, to form a tungsten nucleation layer on the surface of the titanium nitride undercoat film.

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