Method for forming a titanium nitride film and apparatus for forming a titanium nitride film

Abstract

To provide a technology capable of suppressing formation of a void in a titanium nitride film.SOLUTION: A method for forming a titanium nitride film includes steps of: performing a process for changing hydrophilicity of a base film, to such a substrate that the base film capable of changing hydrophilicity is formed on the surface; and forming a titanium nitride film by vapor phase growth, on an upper surface of the base film after the process for changing hydrophilicity is performed. Hereby, characteristics of the titanium nitride film formed on the base film capable of changing hydrophilicity can be controlled.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a method for forming a titanium nitride film and an apparatus for forming a titanium nitride film.

Background Art

[0002] In the manufacture of semiconductor devices, titanium nitride (TiN) films are used for various applications. This TiN film is formed, for example, using a source gas containing titanium (Ti) (e.g., titanium tetrachloride (TiCl 4 ) gas) as a film-forming gas and a reaction gas containing nitrogen (N) (e.g., ammonia (NH 3 ) gas).

[0003] Here, Patent Document 1 describes a technique for orienting a TiN film to (111) and (200) by adjusting a magnetic field to change the plasma density when forming a TiN film by magnetron sputtering.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique for controlling the characteristics of a titanium nitride film formed on a base film capable of changing hydrophilicity.

Means for Solving the Problems

[0006] In the method for forming a titanium nitride film on a substrate according to the present disclosure, a step of performing a treatment for changing the hydrophilicity of the base film on a substrate having a base film capable of changing hydrophilicity formed on its surface; A step of forming a titanium nitride film by vapor deposition on the upper surface of the base film after the treatment for changing the hydrophilicity is performed, and the method includes See The process of changing the hydrophilicity is a hydrophilization process for improving the hydrophilicity of the base film, The hydrophilization process is a process of terminating the elements on the surface of the base film with hydroxy groups, and is a liquid treatment of the surface of the substrate using an APM (Ammonia-Hydrogen Peroxide Mixture) solution. . Alternatively, the present disclosure is a method for forming a titanium nitride film on a substrate, a step of performing a process of changing the hydrophilicity of the base film on a substrate having a base film capable of changing hydrophilicity formed on its surface; a step of forming a titanium nitride film by vapor growth on the upper surface of the base film after the process of changing the hydrophilicity is performed, and includes: The process of changing the hydrophilicity is a hydrophilization process for improving the hydrophilicity of the base film, The hydrophilization process is a dry etching process of the surface of the substrate using a fluorine-containing gas or an etching gas containing hydrogen. Furthermore, the present disclosure is a method for forming a titanium nitride film on a substrate, a step of performing a process of changing the hydrophilicity of the base film on a substrate having a base film capable of changing hydrophilicity formed on its surface; a step of forming a titanium nitride film by vapor growth on the upper surface of the base film after the process of changing the hydrophilicity is performed, and includes: The process of changing the hydrophilicity is a hydrophobicization process for reducing the hydrophilicity of the base film.

Advantages of the Invention

[0007] According to the present disclosure, the characteristics of the titanium nitride film formed on the base film capable of changing the hydrophilicity can be controlled.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0009] Before explaining the specific technical content regarding the method for forming a titanium nitride (hereinafter also referred to as "TiN") film of the present disclosure, a configuration example of a device manufactured using the TiN film and its problems will be described. The TiN film formed by the method of the present disclosure forms, for example, a wiring layer that is a word line of a DRAM (Dynamic Random Access Memory). For example, as shown in FIG. 1(a), TiN 8 is embedded in a groove-shaped recess 82 formed in a silicon oxide (SiO) film 81 which is a base film formed on one surface side of a wafer. For example, the TiN film is formed by the ALD (Atomic Layer Deposition) method described later. Inside the recess 82, polycrystalline TiN grows while depositing on the bottom and the inner surface of the side wall of the recess 82 respectively, and the embedding into the recess 82 proceeds.

[0010] The SiO film 81 is used as an insulating film, and the recess 82 has a depth D of 80 to 200 nm and an opening width W of about 10 to 20 nm, and the ratio D / W of the depth D to the opening width W is formed to be about 5 to 20. Generally, the recess 82 of the word line has a smaller aspect ratio compared to the recess for forming a via hole, and the resistance value can be lowered by embedding TiN compared to tungsten which has been conventionally used as a wiring material.

[0011] In the manufacturing process of DRAM, after forming a TiN film embedded in the recess 82, an annealing process is carried out at a temperature of about 750 to 1000 °C in an inert gas atmosphere for the purpose of impurity diffusion and the like. On the other hand, small voids 83 may be formed in the TiN 8 embedded in the recess 82. It has also been found that this void 83 may be additionally formed by the annealing process carried out after film formation (Fig. 1(b)). When a large number of voids 83 are generated in the TiN film used as the wiring layer in this way, the current flow deteriorates, which becomes a factor for increasing the specific resistance of the TiN wiring layer, and there is a concern that it may have an adverse effect on device operation.

[0012] Here, it is speculated that the void 83 formed by the annealing process is generated when the grains (crystal grains) in the TiN 8 grow due to heating and minute gaps are generated between adjacent grains. Also, when forming a TiN film using a source gas containing impurities such as chlorine in TiCl 4 it is speculated that the formation of the void 83 may be promoted by the aggregation of impurities at the unstable interfaces between the grains. According to this model, it can be expected that if the ratio of grains having stable interfaces can be increased, the generation of the void 83 can be suppressed.

[0013] Regarding the stability of the interfaces between the grains, the inventors focused on the crystal structure of TiN. As shown in Fig. 2, the crystal 9 of TiN containing two types of atoms, titanium 91 and nitrogen 92, has a face-centered cubic lattice structure. This TiN has three types of crystal planes that grow in the (111) direction shown in Fig. 3, the (200) direction shown in Fig. 4, and the (220) direction shown in Fig. 5 when expressed using Miller indices. Note that the figures shown in Figs. 3 to 5 schematically show the crystal planes viewed from the directions facing the respective crystal directions. Also, for convenience, the crystal planes growing in the above-mentioned respective crystal directions are also described as "crystal planes of (111)", etc.

[0014] According to the molecular dynamics (MD) simulations conducted by the inventors, it was found that the interfaces of the grains in contact with the crystal planes in the (111) direction and (220) direction (hereinafter also referred to as the "(111) / (220) interface") have relatively few dangling bonds (unbonded hands) (relatively many atomic bonds between the interfaces). On the other hand, the interfaces of the grains in contact with the crystal planes in the (111) direction and (200) direction (hereinafter also referred to as the "(111) / (200) interface"), and the interfaces of the grains in contact with the crystal planes in the (220) direction and (200) direction (hereinafter also referred to as the "(220) / (200) interface") were found to have relatively many dangling bonds (relatively few atomic bonds between the interfaces).

[0015] According to the results of the above-mentioned preliminary simulations, it was found that the (111) / (200) interface and the (220) / (200) interface are more unstable compared to the (111) / (220) interface. And it is expected that impurities such as Cl tend to aggregate at the (111) / (200) interface and the (220) / (200) interface with many dangling bonds and being unstable, which may cause the formation of void 83. In other words, if the proportion of the (111) / (220) interface in TiN8 can be increased and the proportion of the (200) interface can be decreased, it is possible to suppress the formation of void 83. That is, the formation of void 83 can be suppressed by increasing the grains with (111) and (220) planes and decreasing the grains with (200) planes. This is also supported by the results of the preliminary experiment described later with reference to FIG. 11.

[0016] On the other hand, the inventors focused on the hydrophilicity of the underlying film (SiO film 81 in the example of FIG. 1) as a method for controlling the interfaces of the TiN grains in TiN8. That is, it was newly found that by changing the hydrophilicity of the underlying film, it is possible to control the crystal structure of the interfaces in TiN8. For example, the SiO film 81 can control its hydrophilicity by changing the chemical species bonded to the unbonded hands on the surface.

[0017] As shown in FIG. 6, the method for forming a TiN film according to the present disclosure includes performing a process of changing the hydrophilicity of a SiO film 81 as an underlying film (step P1), and then forming a TiN film on the upper surface of the SiO film 81 after the process is performed (step P2). The process of step P1 may be a hydrophilic treatment for improving the hydrophilicity of the SiO film 81, or a hydrophobic treatment for reducing the hydrophilicity of the SiO film 81.

[0018] At this time, as shown in the experimental results described later, it was found that when the SiO film 81 is subjected to a hydrophilic treatment, grains having a (200) plane, which are a factor in the formation of voids 83, can be reduced. Therefore, hereinafter, a method for suppressing the formation of voids in a TiN film by performing a hydrophilic treatment on an underlying film will be described with reference to FIGS. 7 to 9.

[0019] FIG. 7 shows a configuration example of a hydrophilicity adjusting device 3 that performs a hydrophilic treatment on a wafer W on which a SiO film 81 is formed. The hydrophilicity adjusting device 3 is configured as a single-wafer liquid treatment device that performs a hydrophilic treatment on a wafer W having a SiO film 81 formed on its surface by supplying a known APM (Ammonia-Hydrogen Peroxide Mixture) solution.

[0020] The hydrophilicity adjusting device 3 includes an outer chamber 31 that forms a sealed treatment space in which liquid treatment for supplying an APM solution to the wafer W, rinse cleaning with DIW (Deionized Water), and spin drying are performed, a wafer holding mechanism 33 provided in the outer chamber 31 and configured to rotate the wafer W while holding it substantially horizontally, a nozzle arm 34 that supplies a treatment liquid to the upper surface side of the wafer W held by the wafer holding mechanism 33, and an inner cup 32 provided in the outer chamber 31 so as to surround the wafer holding mechanism 33 and configured to receive the treatment liquid scattered from the rotating wafer W to the surroundings.

[0021] On the bottom surface of the outer chamber 31, a drain line 36 for discharging drainage such as DIW and an exhaust line 37 for exhausting the atmosphere inside the outer chamber 31 are connected. On the side wall surface of the outer chamber 31, there is provided an inlet / outlet (not shown) that is opened and closed by the aforementioned gate valve 29 and through which the wafer W is carried in and out. The wafer holding mechanism 33 includes a disk-shaped stage that horizontally holds the wafer W and a rotating shaft connected to the central portion on the lower surface side of the stage. At the lower end of the rotating shaft, a rotation drive unit 331 for rotating the wafer holding mechanism 33 is provided.

[0022] The nozzle arm 34 is provided with a nozzle for supplying a processing liquid at its tip, and the nozzle can be moved between a position above the central portion of the wafer W held by the wafer holding mechanism 33 and a standby position provided in a region outside the inner cup 32, for example, by a drive mechanism (not shown). The inner cup 32 is configured to move up and down between a processing position surrounding the wafer W held by the wafer holding mechanism 33 and a retracted position retracted below this processing position by a lifting mechanism (not shown). The inner cup 32 serves to receive the processing liquid scattered from the surface of the rotating wafer W at the processing position and discharge these processing liquids to the outside through a drain line 35 connected to the bottom surface side thereof.

[0023] Next, a mechanism for supplying a processing liquid to the nozzle arm 34 will be described. The nozzle provided on the nozzle arm 34 is connected to a processing liquid supply line 38, and this processing liquid supply line 38 branches into a DIW supply line 301a and an APM supply line 301b via a switching valve 392. An APM supply unit 302 is connected to the upstream side of the APM supply line 301b, and an APM liquid, which is a processing liquid for hydrophilizing the SiO film 81 on the surface of the wafer W and is a mixed liquid of ammonia and hydrogen peroxide water, is supplied from this APM supply unit 302.

[0024] The other DIW supply line 301a branched from the processing liquid supply line 38 is provided with a DIW supply unit 301 for supplying DIW, which is a processing liquid for rinsing and cleaning the APM liquid remaining on the wafer W after the hydrophilic treatment. A flow rate adjustment unit 391 is interposed in the processing liquid supply line 38, and the supply flow rates of the APM liquid supplied from the APM supply unit 302 and the DIW supplied from the DIW supply unit 301 can be adjusted.

[0025] Next, a configuration example of a film forming apparatus 4 for forming a TiN film by the ALD method, which is a vapor phase growth method, on the upper surface side of the SiO film 81 after the hydrophilic treatment will be described. The film forming apparatus 4 includes a processing container 40 for accommodating the wafer W and performing a film forming process in a vacuum atmosphere. An inlet / outlet 41 configured to be openable and closable by the aforementioned gate valve 29 is formed on the side surface of the processing container 40.

[0026] An annular exhaust duct 43 is disposed, for example, at the upper part of the side wall of the processing container 40. Further, a top plate 44 is provided on the upper surface of the exhaust duct 43 so as to close the upper opening of the processing container 40. The processing container 40 is connected to a vacuum exhaust unit 46 composed of, for example, a vacuum pump via a vacuum exhaust path 45 connected to the exhaust port 431 of the exhaust duct 43. An APC (Auto pressure Controller) valve 47 for adjusting the pressure inside the processing container 40 is interposed in the vacuum exhaust path 45.

[0027] Inside the processing container 40, a mounting table 5 for horizontally supporting the wafer W is provided. A heater 51 for heating the wafer W is embedded in the mounting table 5. The mounting table 5 is configured to be movable up and down by a lifting mechanism 54. In FIG. 8, the mounting table 5 moved to the transfer position of the wafer W is shown by a dashed line. In the same figure, reference numeral 55 indicates a support pin for transferring the wafer W, and the support pin is configured to be movable up and down by a lifting mechanism 56. Reference numeral 52 indicates a through hole for the support pin 55, and reference numerals 57 and 58 indicate bellows that expand and contract as the mounting table 5 and the support pin 55 move up and down, respectively.

[0028] In the processing container 40, a shower head 6 for supplying a processing gas into the processing container 40 is provided so as to face the mounting table 5. The shower head 6 has a gas diffusion space 61 inside thereof, and its lower surface is configured as a shower plate 62 in which a large number of gas discharge holes 63 are formed. A gas supply system 7 is connected to the gas diffusion space 61 via a gas introduction hole 64.

[0029] The gas supply system 7 includes a source gas supply section 71 for supplying a source gas to the processing container 40 and a reaction gas supply section 72 for supplying a reaction gas. The source gas is a gas containing a titanium compound containing chlorine (Cl) and titanium (Ti), and as the titanium compound, for example, titanium tetrachloride (TiCl 4 ) is used. The reaction gas contains nitrogen (N) and is a gas containing a nitrogen compound that reacts with the titanium compound to form titanium nitride (TiN). As the nitrogen compound, for example, ammonia (NH 3 ) is used.

[0030] The source gas supply section 71 includes a TiCl 4 gas supply source 74 and a TiCl 4 gas supply path 741. For example, in the TiCl 4 gas supply path 741, a flow rate adjustment section 742, a storage tank 743, and a valve V1 are provided in series from the upstream side. The reaction gas supply section 72 includes an NH 3 gas supply source 75 and an NH 3 gas supply path 751. For example, in the NH 3 gas supply path 751, a flow rate adjustment section 752, a storage tank 753, and a valve V2 are provided in series from the upstream side.

[0031] These TiCl 4 gas and NH 3The gases are each temporarily stored in storage tanks 743 and 753, pressurized to a predetermined pressure, and then supplied into the processing vessel 40. The supply and stop of each gas from the storage tanks 743 and 753 to the processing vessel 40 are performed by opening and closing valves V1 and V2. Furthermore, the gas supply system 7 includes an inert gas supply unit that supplies an inert gas to the processing vessel 40. As the inert gas, for example, nitrogen (N 2 ) gas is used. The inert gas supply unit in this example includes N 2 gas supply sources 77 and 78 and N 2 gas supply paths 771 and 781.

[0032] In this example, the N 2 gas supplied from the N 2 gas supply source 77 of the raw material gas supply unit 71 is a purge gas for TiCl 4 gas. This N 2 gas supply source 77 is connected to the downstream side of the valve V1 provided in the TiCl 2 gas supply path 741 via the N 4 gas supply path 771. Also, the N 2 gas supplied from the N 2 gas supply source 78 of the reaction gas supply unit 72 is a purge gas for NH 3 gas. This N 2 gas supply source 78 is connected to the downstream side of the valve V2 provided in the NH 2 gas supply path 751 via the N 3 gas supply path 781. In FIG. 8, reference numerals 772 and 782 each denote a flow rate adjustment unit, and reference numerals V3 and V4 each denote a valve.

[0033] The operation of processing the wafer W using the hydrophilicity adjusting apparatus 3 and the film forming apparatus 4 having the configuration described above will be described. First, the wafer W is transported to the hydrophilicity adjusting apparatus 3, and the hydrophilic treatment of the SiO film 81 is performed. That is, when the wafer W is transferred to the wafer holding mechanism 33, the nozzle of the nozzle arm 34 moves to a position above the central portion of the wafer W. Thereafter, the wafer W is rotated by the wafer holding mechanism 33, and the supply of the APM liquid from the nozzle is started. The APM liquid supplied to the wafer W spreads over the entire surface of the wafer W due to the influence of centrifugal force.

[0034] The APM liquid has the effect of terminating the dangling bonds on the surface of the SiO film 81 with hydroxy groups (OH groups). The hydroxy groups thus formed on the surface of the SiO film 81 (wafer W) improve the hydrophilicity of the wafer W (step P1). Note that the treatment liquid having the effect of hydrophilizing the SiO film 81 is not limited to the APM liquid, and HPM (Hydrochloric hydrogen Peroxide Mixture) can also be used. After supplying the APM liquid for a predetermined time, the treatment liquid supplied to the wafer W is switched to DIW for rinsing. Thereafter, while continuing the rotation of the wafer W, the supply of DIW is stopped, the remaining treatment liquid is shaken off, and the wafer W is dried to complete the hydrophilization treatment.

[0035] The wafer W after the hydrophilization treatment is taken out from the hydrophilicity adjusting apparatus 3 and carried into the film forming apparatus 4. In the film forming apparatus 4, the film formation of the TiN film by the ALD method is performed (step P2). The gas supply sequence shown in FIG. 9 shows the supply timing of the TiCl 4 gas, NH 3 gas, and N 2 gas to the processing container 40. In FIG. 9, the N 4 below TiCl 2 indicates the N 2 gas supplied from the N 2 gas supply source 77, and the N 3 below NH 2 indicates the N 2 gas supplied from the N 2 gas supply source 78.

[0036] The wafer W carried into the processing container 40 is placed on the mounting table 5, and heating of the wafer W by the heater 51 is started. At the same time, N is introduced into the processing container 40. 2 gases are supplied from the gas supply sources 77 and 78 at preset flow rates respectively. 2 Then, the inside of the processing container 40 is evacuated by the vacuum exhaust unit 46, and the opening degree of the APC valve 47 is adjusted so that the inside of the processing container 40 reaches the target pressure.

[0037] Subsequently, based on the gas supply sequence in FIG. 9, a step of forming a TiN film is performed. This step is composed of steps S1 to S4 shown in FIG. 9. First, the valve V1 is opened to supply TiCl as the source gas. 4 gas, and at the same time, N 2 gases are supplied from the gas supply sources 77 and 78 at preset flow rates respectively. 2 gas. By this treatment, TiCl which is a component containing Ti is adsorbed on the entire surface of the wafer W. 4 is adsorbed.

[0038] Next, the valve V1 is closed to stop the supply of TiCl. 4 gas, while the supply of N 2 gas from the gas supply sources 77 and 78 is continued. In this way, purging with N 2 gas is performed to remove the residual TiCl in the processing container 40. 2 gas. (Step S2) 4 gas.

[0039] Next, while the supply of N 2 gas from the gas supply sources 77 and 78 is continued, the valve V2 is opened to supply NH as the reaction gas. 2 gas. By this treatment, TiCl adsorbed on the wafer W reacts with NH 3 gas, and a thin film of TiN is formed. (Step S3) 4 and NH 3 and a thin film of TiN is formed. Subsequently, the valve V2 is closed to stop the supply of NH. 3 gas, while N2 N from gas supply sources 77 and 78 2 Continue to supply N gas, and 2 Perform purging with N gas to remove the NH gas remaining in the processing vessel 40. 3 (Step S4).

[0040] In this way, in the step of forming the TiN film, while supplying N gas, which is an inert gas, into the processing vessel 40, the raw material gas and the reaction gas are alternately supplied, and steps S1 to S4 are repeated the set number of times to form a TiN film with a desired thickness. 2 After forming the TiN film, the wafer W is unloaded from the film forming apparatus 4. The TiN film formed on the upper surface of the SiO film 81 has unnecessary portions removed by the subsequent etching process, and a structure in which the recess 82 is filled with TiN8 is obtained (Fig. 1(a)).

[0041] According to the film forming method of the present disclosure, after performing a hydrophilic treatment as an example of a treatment for changing the hydrophilicity of the SiO film 81 formed on the surface of the wafer W, the TiN film is formed. As a result, as shown in the experimental results described later, the formation of voids 83 in the TiN8 when the wafer W is annealed can be suppressed.

[0042] Here, the content of the hydrophilic treatment is not limited to the case of liquid treatment with the APM solution described with reference to Fig. 7. For example, as shown in the experimental results described later, the hydrophilic treatment of the base film of the TiN film may be performed by dry etching using an etching gas. Examples of the etching gas include a mixed gas of nitrogen trifluoride (NF

[0043] 3 ) gas, which is a fluorine-containing gas containing fluorine, and nitrogen gas, or a mixed gas of hydrogen gas and nitrogen gas.

[0044] ​When performing a hydrophilic treatment by dry etching, as an example, a case can be illustrated where, instead of the hydrophilic treatment apparatus 3 that performs the hydrophilic treatment by liquid treatment described with reference to FIG. 7, a hydrophilic treatment apparatus configured to perform dry etching using an etching gas that has been plasma-activated is provided.

[0045] In this case, for example, regarding the processing module (film forming apparatus 4) configured as shown in FIG. 8, instead of the source gas and reaction gas for forming TiN, a case can be illustrated where an etching apparatus is configured by supplying an etching gas from the gas supply system 7. Also, one side of the shower head 6 and the mounting table 5 disposed opposite to each other inside this etching apparatus may be grounded, and a high-frequency power source for plasma generation may be connected to the other side to configure a parallel plate type plasma module using capacitive coupling. As another method of plasma formation, a configuration that generates plasma using an inductively coupled antenna may be adopted, or a configuration that supplies microwaves from a microwave antenna to the processing gas to generate plasma may be adopted. The inductively coupled antenna and the microwave antenna are disposed, for example, on the upper surface side of the shower head 6.

[0046] Also, the processing modules that configure the above-described etching apparatus and film forming apparatus 4 all perform processing of the wafer W in a vacuum atmosphere. Therefore, by connecting these processing modules to a common vacuum transfer chamber, the series of steps P1 and P2 shown in FIG. 6 can be implemented within a common apparatus.

[0047] The film forming system 1 shown in FIG. 10 is configured as a multi-chamber system including the above-described etching apparatus 30 and film forming apparatus 4 as processing modules. In the film forming system 1 shown in FIG. 10, a carrier C containing a plurality of wafers W to be processed is transported to the load port 21 of the film forming apparatus 1. The wafer W is taken out from the carrier C by the transfer arm 25 and carried into the alignment chamber 26 via the atmospheric pressure transfer chamber 22. After alignment is performed on the wafer W in the alignment chamber 26, it is carried into the vacuum transfer chamber 24 via the load lock chamber 23.

[0048] Subsequently, the wafer W is subjected to a hydrophilic treatment of the underlying film by dry etching in the etching apparatus 30 by the transfer arm 28 (step P1), and then, a TiN film is formed on the upper surface side of the underlying film after the hydrophilic treatment in the film forming apparatus 4 (step P2). Figure 10 The film forming system 1 shown in corresponds to an apparatus for forming a titanium nitride film on a substrate of the present disclosure, the etching apparatus 30 corresponds to a hydrophilicity adjusting unit, and the film forming apparatus 4 corresponds to a film forming unit.

[0049] Further, when forming the TiN film, the source gas containing Ti supplied to the wafer W is not limited to TiCl 4 gas. For example, titanium tetrabromide (TiBr 4 ) or titanium tetraiodide (TiI 4 ) may be used. Furthermore, for example, an organic source gas such as TDMAT (tetrakis dimethylamino titanium) may be used. Also, in order to improve the film quality of the formed TiN film, SiH 4 , SiH 2 Cl 2 and other Si-containing gases may be added to the source gas. Furthermore, it is possible to improve the hydrophilicity by performing a hydrophilic treatment, and the underlying film (insulating film) formed on the lower surface side of the TiN film is not limited to the SiO film 81. For example, a SiN film, an alumina film, a polysilicon film, or an amorphous silicon film may be used.

[0050] Also, the vapor phase growth method of the TiN film to which the method of the present disclosure can be applied is not limited to the ALD method. CVD (Chemical Vapor Deposition) in which a source gas and a reaction gas are continuously supplied may be used. Also in this case, by performing a hydrophilic treatment on the underlying film and then forming the TiN film, a TiN film in which voids 83 are less likely to be formed can be obtained as compared with the case where the hydrophilic treatment is not performed.

[0051] Furthermore, regarding the configuration of the apparatus for performing liquid processing, in addition to the single-wafer type described with reference to FIG. 7, a batch-type liquid processing apparatus may be used in which a large number of wafers W are immersed in a water tank storing APM liquid to perform liquid processing. Also, regarding the configuration of the apparatus for forming a TiN film, a batch-type film forming apparatus may be used in which a boat holding a large number of wafers W is accommodated in a heating furnace to perform film forming processing. Alternatively, a semi-batch type film forming apparatus may be used in which a plurality of wafers W are arranged on a rotating table, the wafers W are revolved around the rotation axis, and the adsorption of the source gas and the formation of a thin film of TiN by the reaction gas are repeatedly performed by passing through a plurality of processing spaces partitioned from each other.

[0052] In each of the above-described embodiments, an application example of performing a hydrophilization treatment for improving the hydrophilicity of the base film has been described with respect to the treatment (step P1) of changing the hydrophilicity of the base film shown in FIG. 6. On the other hand, as described above, the treatment performed in step P1 may be a hydrophobization treatment for reducing hydrophilicity. The inventors have found that when a hydrophobization treatment is performed on a base film (for example, the SiO film 81 described above) as step P1 and then a TiN film is formed on the upper surface of the base film as step P2, the amount of impurities (such as chlorine, oxygen, and silicon) in the TiN film can be increased or the roughness can be decreased. A TiN film with small roughness can reduce the wiring resistance, for example, when used as a barrier film in a TiN / W laminated structure.

[0053] For example, when performing a hydrophobization treatment by liquid processing, the case of using TMSDMA (N-(Trimethylsilyl)dimethylamine) as the treatment liquid can be exemplified. TMSDMA is one of the silylating agents having an action of terminating the dangling bonds on the surface of the base film with a silyl group containing silicon and hydrocarbon.

[0054] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims.

Example

[0055] (Experiment 1) As a preliminary experiment, the change in the content of voids 83 in the TiN film was examined when the content ratio of crystal planes grown in each of the (111) and (200) directions was changed. A. Experimental conditions An SiO film 81 was formed on the surface of a flat wafer W, and the gas flow rate and gas supply time were changed when forming the TiN film thereon to form TiN films with different content ratios of the above-mentioned crystal planes. Then, after annealing this wafer W at 750 °C in an inert gas atmosphere, the content ratio (void ratio [vol%]) of voids 83 in the TiN film was determined. The content of each crystal plane was determined from the peak intensity of each crystal direction by X-ray diffraction method (XRD; X-ray Diffraction Method). Also, the void ratio was determined by image analysis of a transmission electron microscope (TEM) image.

[0056] B. Experimental results The results of the experiment are shown in Fig. 10. The horizontal axis in Fig. 10 shows the ratio of the peak intensities in the (111) and (200) directions in the results of XRD analysis. According to the results in Fig. 11, the smaller the ratio of the crystal plane growing in the (111) direction, the greater the tendency for the void ratio to increase. On the other hand, as the ratio of the same crystal plane increases, the void ratio decreases. Therefore, it can be said that in the grains constituting the TiN film, the formation of voids 83 can be suppressed by reducing the interface of the unstable (200) crystal plane and increasing the stable (111) interface.

[0057] (Experiment 2) The effect of the hydrophilic treatment on the crystal plane ratio of grains in the TiN film was examined. A. Experimental conditions (Example 1) For the wafer W with an underlying film of SiO film 81 formed on the surface, after performing a hydrophilic treatment using an APM solution, a TiN film was formed by the ALD method described with reference to Figs. 8 and 9. For the SiO film 81 after the hydrophilic treatment, the contact angle was measured using a contact angle meter. Also, XRD analysis was performed on the formed TiN film. (Example 2) NF3 gas and N 2 The SiO film 81 and the TiN film were analyzed in the same manner as in Example 1, except that a mixed gas of gas and N gas was used as the etching gas and hydrophilic treatment was performed by plasma etching. (Example 3) H 2 gas and N 2 The SiO film 81 and the TiN film were analyzed in the same manner as in Example 1, except that a mixed gas of gas and N gas was used as the etching gas and hydrophilic treatment was performed by plasma etching. (Example 4) The SiO film 81 and the TiN film were analyzed in the same manner as in Example 1, except that liquid treatment was performed using TMSDMA, which is a treatment liquid (silylating agent) for hydrophobizing the surface of the SiO film 81. (Reference Example) The SiO film 81 and the TiN film were analyzed in the same manner as in Example 1, except that the SiO film 81 was not hydrophilized.

[0058] B. Experimental Results The results of each example and reference example are shown in FIG. 12 and Table 1. Also, the XRD spectra according to Example 1, Example 4, and the reference example are shown in FIG. 13. The horizontal axis in FIG. 12 shows the contact angle of each SiO film 81, and the vertical axis shows the peak intensity ratios of (111) / (200) and (220) / (200) in the results of XRD analysis of each TiN film. Also, in addition to the peak intensity ratios and the contact angle values, Table 1 also shows the surface state (the termination state of dangling bonds) of the underlying film after hydrophilic treatment / hydrophobic treatment. Note that in Table 1, the examples and the like are arranged in ascending order of the contact angle from top to bottom. Further, the horizontal axis in FIG. 13 shows the diffraction angle 2θ, and the vertical axis shows the detected X-ray intensity.

[0059] (Table 1) TIFF0007683383000001.tif21197

[0060] According to the results shown in Fig. 12 and Table 1, as the contact angle of the SiO film 81 increases due to the hydrophilic treatment, the ratio of the crystal planes growing in the (111) and (220) directions increases with respect to the crystal plane growing in the (200) direction. As a result, it can be said that the interface of the unstable (200) crystal plane in the grains constituting the TiN film can be reduced. On the other hand, in Example 4 where the SiO film 81 was hydrophobized, the ratio of the crystal planes growing in the (111) and (220) directions decreased even compared to the reference example without the treatment. This indicates that, as described above, the amount of impurities in the TiN film can be increased or a TiN film with a small roughness can be formed, and it can be used for the purpose of reducing the wiring resistance in the TiN / W laminated structure.

[0061] The comparison between Example 1 and Example 4 described above is also clearly shown in the XRD spectrum of Fig. 13. The peak intensity in the (111) direction is greater in Example 1 than in Example 4. On the other hand, the peak intensity in the (200) direction is smaller in Example 1 than in Example 4. The reason why the ratio of the stable (111) crystal plane increases as the hydrophilicity of the SiO film 81 increases (the contact angle decreases) is unknown. On the other hand, it was confirmed that the hydrophilic treatment is an effective operation method for controlling the crystal structure of the TiN film formed on the underlying film (SiO film 81).

Explanation of symbols

[0062] W wafer 1 Film forming apparatus 3 Hydrophilic treatment section 4 Film forming section 8 TiN 81 SiO film 82 Concave portion 83 Void

Claims

1. In a method for forming a titanium nitride film on a substrate, a step of performing a treatment for changing the hydrophilicity of a base film formed on a substrate having a base film capable of changing hydrophilicity on its surface; a step of forming a titanium nitride film by vapor growth on the upper surface of the base film after the treatment for changing the hydrophilicity is performed, and includes: the treatment for changing the hydrophilicity is a hydrophilization treatment for improving the hydrophilicity of the base film; the hydrophilization treatment is a treatment for terminating elements on the surface of the base film with hydroxy groups, and is a liquid treatment of the substrate surface using an APM (Ammonia-Hydrogen Peroxide Mixture) solution.

2. In a method for forming a titanium nitride film on a substrate, a step of performing a treatment for changing the hydrophilicity of a base film formed on a substrate having a base film capable of changing hydrophilicity on its surface; a step of forming a titanium nitride film by vapor growth on the upper surface of the base film after the treatment for changing the hydrophilicity is performed, and includes: the treatment for changing the hydrophilicity is a hydrophilization treatment for improving the hydrophilicity of the base film; the hydrophilization treatment is a dry etching treatment of the substrate surface using a fluorine-containing gas or an etching gas containing hydrogen.

3. In a method for forming a titanium nitride film on a substrate, a step of performing a treatment for changing the hydrophilicity of a base film formed on a substrate having a base film capable of changing hydrophilicity on its surface; a step of forming a titanium nitride film by vapor growth on the upper surface of the base film after the treatment for changing the hydrophilicity is performed, and includes: the treatment for changing the hydrophilicity is a hydrophobicization treatment for reducing the hydrophilicity of the base film.

4. The method according to claim 3, wherein the hydrophobicization treatment is a treatment for terminating elements on the surface of the base film with silyl groups.

5. The method according to claim 4, wherein the hydrophobicization treatment is a liquid treatment of the substrate surface using TMSDMA (N-(Trimethylsilyl)dimethylamine).

6. In the step of forming the titanium nitride film, a raw material gas containing a titanium-containing component is supplied to the substrate to adsorb the component on the surface of the substrate, and then a reaction gas for nitriding the component is supplied to the substrate to form a thin film of titanium nitride on the surface of the substrate, and the above processes are repeatedly executed. The method according to any one of claims 1 to 5.

7. The method according to any one of claims 1 to 6, wherein the underlayer film is a silicon oxide film.

8. In an apparatus for forming a titanium nitride film on a substrate a hydrophilicity adjusting unit that performs a process of changing the hydrophilicity of an underlayer film formed on the surface of a substrate capable of changing the hydrophilicity; a film forming unit that forms a titanium nitride film by vapor phase growth on the upper surface of the underlayer film after the process of changing the hydrophilicity is performed; the process of changing the hydrophilicity is a hydrophilic treatment for improving the hydrophilicity of the underlayer film; The apparatus, wherein the hydrophilic treatment is a dry etching treatment of the substrate surface using a fluorine-containing gas or an etching gas containing hydrogen.

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