Film formation method, film formation device, and semiconductor device

Abstract

A film formation method according to the present disclosure comprises: a step for forming, on a substrate, a titanium ruthenium nitride film in which the concentration of ruthenium contained therein is less than 73 atom%; a step for forming a dielectric film laminated on the titanium ruthenium nitride film; and a step for forming a metal-containing film laminated on the dielectric film.

Description

Film Forming Method, Film Forming Apparatus, and Semiconductor Device

[0001] The present disclosure relates to a film forming method, a film forming apparatus, and a semiconductor device.

[0002] In manufacturing a semiconductor device, various metal films are formed on the surface of a semiconductor wafer (hereinafter referred to as a substrate) which is a substrate. For example, for a capacitor constituting a semiconductor device, first and second electrodes are formed to face each other on the surface of the substrate via a dielectric film, and a metal oxide which is a High-K material having a relatively high relative permittivity may be used for the dielectric film. The first and second electrodes may be configured by laminating metal-containing films containing different metals respectively.

[0003] Patent Document 1 describes forming a nitride alloy film as a barrier layer under a plating film containing copper to prevent diffusion of copper into an insulating film. A titanium nitride-ruthenium alloy film is disclosed as a nitride alloy film that improves the oxidation resistance of the interface between the plating film and the nitride alloy film.

[0004] Japanese Patent Application Laid-Open No. 2021-180281

[0005] The present disclosure provides a technique capable of suppressing the occurrence of defects in a substrate laminated in the order of a titanium nitride ruthenium film, a dielectric film, and a metal-containing film.

[0006] The film forming method of the present disclosure includes a step of forming a titanium nitride ruthenium film having a ruthenium concentration lower than 73 atomic% on a substrate, a step of forming a dielectric film laminated on the titanium nitride ruthenium film, and a step of forming a metal-containing film laminated on the dielectric film.

[0007] The present disclosure can suppress the occurrence of defects in a substrate laminated in the order of a titanium nitride ruthenium film, a dielectric film, and a metal-containing film.

[0008] It is a plan view showing a substrate processing system of an embodiment. It is a plan view exemplifying a substrate processing apparatus constituting the substrate processing system. It is a longitudinal sectional side view showing one processing module provided in the substrate processing apparatus. It is a longitudinal sectional side view showing another processing module. It is a longitudinal sectional side view showing a surface change of a substrate on which the processing of the embodiment is performed. It is a longitudinal sectional side view showing a TiRuN film formed by another manufacturing method. It is a graph showing the results of Evaluation Test 1. It is a table showing the results of Evaluation Test 1. It is a first image showing the results of Evaluation Test 2. It is a second image showing the results of Evaluation Test 2. It is a schematic diagram of an image showing the results of Evaluation Test 4. It is a first graph showing the results of Evaluation Test 5. It is a second graph showing the results of Evaluation Test 5. It is a graph showing the results of Evaluation Test 6.

[0009] (Embodiment) FIG. 1 shows a plan view of a substrate processing system 1 for executing a film forming method of the present disclosure. In this example, a capacitor of a DRAM is formed by providing a first electrode and a second electrode facing each other and a dielectric film sandwiched between these electrodes on a substrate W. The substrate W is a semiconductor wafer and is composed of, for example, silicon. The semiconductor wafer may be simply referred to as a wafer hereinafter. For convenience of explanation, the side where the first electrode is formed is the lower side, and the side where the second electrode is formed is the upper side.

[0010] It will be specifically shown later with reference to FIG. 5, so briefly explained here, as the film constituting the first electrode, a TiN film and a TiRuN (titanium ruthenium nitride) film are sequentially formed on the substrate W. Subsequently, ZrO ２ (zirconium oxide) is formed. Thereafter, annealing treatment is performed to form a TiN (titanium nitride) film which is a metal-containing film as the second electrode. Therefore, a TiN film, a TiRuN film, a ZrO ２ film, and a TiN film are laminated in this order. In this example, the TiRuN film and the TiN film are formed by PVD, more specifically, sputtering, and the ZrO ２ film is formed by ALD.

[0011] As described above, since each film is laminated, among the first electrodes, ZrO ２The upper layer (surface) in contact with the film is made of a TiRuN film. The reason for constructing the first electrode in this way is that when forming the dielectric film, O, which has strong oxidizing power, is used. ３ Gas is supplied. The TiRuN film 12 has high oxidation resistance and tends to block oxygen permeation, as shown in the test example described later, and prevents oxidation of the TiN film 11 below it. This suppresses oxidation of the surface of the first electrode composed of the TiN film 11 and the TiRuN film 12, and prevents the resistivity of the surface from increasing and becoming dielectric. In other words, by forming a TiRuN film as the first electrode, a decrease in the conductivity of the first electrode is prevented.

[0012] However, when forming a TiRun film in this way, a dielectric film (ZrO) is formed, as will be shown in the evaluation test later. ２ It was confirmed that the film may peel off from the TiRuN film. This is thought to be because the oxidation resistance of the TiRuN film is too high, resulting in a low oxygen level on the surface of the TiRuN film after the dielectric film is formed, leading to low affinity and adhesion between the dielectric film (which is an oxide film) and the TiRuN film. Therefore, in this example, the concentration of Ru (ruthenium) in the TiRuN film is made relatively low to prevent the oxidation resistance of the TiRuN film from becoming too high, thereby ensuring adhesion between the dielectric film and the TiRuN film and preventing the above-mentioned peeling. Specifically, in this example, the proportion of metal elements contained in the target used in sputtering is adjusted so that the ruthenium concentration in the TiRuN film is 10 atomic percent.

[0013] The substrate processing system 1 shown in Figure 1 will be described below. The substrate processing system 1 comprises a film deposition apparatus 1a that performs film deposition by sputtering, and a film deposition apparatus 1b that performs ALD and annealing. Therefore, the first electrode and the second electrode are formed in the film deposition apparatus 1a, and the dielectric film is formed in the film deposition apparatus 1b. The substrate W is transported between the film deposition apparatuses 1a and 1b in a transport container C by a transport mechanism provided in the factory where the substrate processing system 1 is installed. The film deposition apparatus 1a comprises a processing module (TiNRu film deposition section) 5a for depositing a TiNRu film and a processing module (metal-containing film deposition section) 5b for depositing a TiN film. The film deposition apparatus 1b comprises a processing module (dielectric film deposition section) 5c for depositing a dielectric film and a processing module 5d for performing annealing.

[0014] Representing the film deposition apparatuses 1a and 1b, film deposition apparatus 1a will be described with reference to the plan view in Figure 2. Film deposition apparatus 1a is configured with an atmospheric transport module 2, two load lock modules 3, a vacuum transport module 4, and processing modules 5a and 5b arranged from front to back. The load lock module may be referred to as LLM below.

[0015] The atmospheric transport module 2 comprises a housing 21, and the inside of the housing 21 is kept at atmospheric pressure. A transport mechanism 22 is provided inside the housing 21, and this transport mechanism 22 is configured, for example, as a multi-jointed arm that can move freely from side to side. The atmospheric transport module 2 also comprises, for example, three load ports 23 for transferring substrates W between the transport container C and the LLM 3, and these three load ports 23 are arranged side by side on the left and right.

[0016] Each load port 23 consists of a mounting platform 24 for a transport container C provided on the front side of the housing 21, a transport opening provided on the side wall of the housing 21 facing the transport container C on the mounting platform 24, and a door 25 for opening and closing the transport opening. The transport container C is configured to store a large number of substrates W and is called, for example, a FOUP (Front Opening Unified Pod), and the transport mechanism 22 transports the substrates W between this transport container C and the LLM 3.

[0017] The LLM3 comprises a housing 31, which is configured to appropriately change the pressure inside the housing 31 between atmospheric pressure and a predetermined vacuum pressure. The housing 31 is provided with two transport ports each for transporting substrates W into the atmospheric transport module 2 and the vacuum transport module 4, and each transport port is provided with a gate valve G. Inside the housing 31 is a stage 33 on which substrates W are placed, and substrates W are transferred between the transport mechanism 22 of the atmospheric transport module 2 and the transport mechanism 43 of the vacuum transport module 4 (described later) and the stage 33.

[0018] The vacuum transport module 4 comprises a housing 41, and the LLM 3, processing modules 5a and 5b are connected to the side of the housing 41 via gate valves G. The inside of the housing 41 is evacuated by an exhaust mechanism (not shown), so that a vacuum atmosphere at a predetermined pressure is maintained at all times while the substrate processing system 1 is in operation. A transport mechanism 43, which is a multi-jointed arm, is provided inside the housing 41. The transport mechanism 43 transports the substrate W between the processing modules 5a and 5b and the LLM 3.

[0019] The film deposition apparatus 1b has the same configuration as the film deposition apparatus 1a, except that the shape of the vacuum transport module 4 and the number of processing modules connected to the vacuum transport module are different.

[0020] In describing each processing module 5a to 5d, we will describe processing modules 5a and 5c, which deposit TiRuN films and dielectric films, as representative examples. Figure 3 is a longitudinal cross-sectional side view of processing module 5a. Processing module 5a is a module that deposits TiNRu films by sputtering, more specifically by magnetron sputtering. Processing module 5a is equipped with a metal processing container 51, and the processing container 51 is grounded.

[0021] An exhaust mechanism 52 is connected to the processing container 51, and exhaust is performed from an exhaust port 53 formed in the bottom wall of the processing container 51. As a result, the inside of the processing container 51 is maintained at a predetermined vacuum pressure. Specifically, for example, 0.8 Pa (6.0 × 10⁻¹⁰) during film formation. －３ The pressure is maintained at or below Torr. The exhaust mechanism 52, similar to the exhaust mechanism of LLM3, is configured to adjust the amount of exhaust into the processing container 51 by including a valve and a vacuum pump, so that the inside of the processing container 51 is a vacuum atmosphere at the desired pressure. The processing container 51 also has a transport port 54 for the substrate W which is opened and closed by the gate valve G.

[0022] Inside the processing container 51, there is a circular stage 55 in plan view on which the substrate W is placed, and the upper side of the stage 55 is configured as an electrostatic chuck 56. The upper surface of this electrostatic chuck 56 is configured as a mounting surface 55A on which the substrate W is placed horizontally, and the placed substrate W is attracted to the mounting surface 55A.

[0023] The lower side of the stage 55 is configured as a base body 57 and has a flow path (not shown) through which a fluid, whose temperature is controlled by a chiller, flows. Through heat exchange caused by the flow of this fluid, the temperature of the mounting surface 55A of the electrostatic chuck 56 is, for example, room temperature to 250°C. Similar to the stage 33 of the LLM3, the stage 55 is also provided with three retractable pins on its upper surface (i.e., the mounting surface 55A), and the substrate W can be transferred between the transport mechanism 43 of the vacuum transport module 4 and the electrostatic chuck 56 via these pins. The lower side of the stage 55 is connected to a drive mechanism 59 provided outside the processing container 51 via a support column 58. The drive mechanism 59 allows the stage 55 to rotate around a central axis along the vertical direction of the stage 55. In the figure, 50 is a sealing member provided between the processing container 51 and the support column 58, which keeps the inside of the processing container 51 airtight.

[0024] The ceiling of the processing container 51 has a sloping section that descends from the center of the stage 55 towards the periphery, and in this sloping section, for example, four through holes are provided in the circumferential direction in a plan view. A plate-shaped target holder 62 is provided, supported by an annular insulating member 61 provided along the edge of each through hole, and is configured to close the through hole, and this target holder 62 is configured as a cathode. Four rectangular plate-shaped targets 63 made of metal are supported and arranged in a stacked state below each target holder 62. In this example, there are four target holders 62 and four targets 63, but Figure 3 shows only two of them.

[0025] When these target holders 62 and the target 63 below them are considered as a set, the four sets are located at the same height and are arranged in a rotationally symmetrical positional relationship with respect to the rotation axis of the substrate W on the stage 55 when viewed from above. The main surface (bottom surface) of each target 63 is inclined with respect to the horizontal and vertical planes and is positioned facing the stage 55.

[0026] Each target 63 contains Ti and Ru, and the concentrations of each element in the target 63 are adjusted so that the Ti and Ru concentrations in the TiRuN film formed on the substrate W are the desired concentrations. Note that "containing Ti and Ru" here means they are included as constituent components, not as unavoidable impurities. Thus, in this example, a TiRu alloy target 63 is used, and in order to achieve a Ru concentration of 10 atomic percent in the TiRuN film, the proportion of Ru contained in the target 63 is set to 10 atomic percent. Therefore, if the Ru concentration in the TiRuN film is to be lower than 10 atomic percent, for example, the proportion of Ru contained in the target 63 should be lowered to less than 10 atomic percent.

[0027] As detailed in the evaluation tests, problems occurred when the Ru concentration in the TiRuN film was 73 atomic percent. Therefore, the Ru concentration of the TiRuN film may be set to a relatively high value within a range lower than 73 atomic percent. Depending on the desired Ru concentration in the TiRuN film, each target 63 is not limited to being an alloy of Ti and Ru; at least one of the multiple targets 63 may be made of Ti, and the other targets 63 may be made of Ru.

[0028] Each target holder 62 is connected to a power supply 64, and sputtering of the target 63 is performed by applying a negative DC voltage of, for example, 325W to 1300W from the power supply 64. A magnet unit 65 is provided on the upper side of each target holder 62, outside the processing container 51. The magnet unit 65 forms a leaking magnetic field on the lower side of the target 63 held by the lower target holder 62. To prevent localized erosion of the target 63, the magnet unit 65 moves back and forth linearly along the upper surface of the target holder 62 by a moving mechanism 66 during sputtering of the target 63.

[0029] In addition, an air supply port 67 is open in the processing container 51, and gas is supplied from the gas supply mechanism 68 into the processing container 51 through the air supply port 67. This gas is a mixed gas of an inert gas for sputtering (for plasma generation by voltage application from the power supply 64) and a nitriding gas (gas containing nitrogen atoms) for nitriding Ti and Ru. Specifically, for example, the inert gas is argon (Ar) gas, and the nitriding gas is, for example, N ２ (nitrogen) gas. The gas supply mechanism 68 includes a supply source of Ar gas, a supply source of N ２ gas, a valve for switching the supply and supply stop of each gas into the processing container 51, and a flow rate adjustment unit such as a mass flow controller for adjusting the supply flow rate of each gas to the downstream side of the flow path.

[0030] The ratio of the flow rate of N ２ gas to the total of the flow rate of Ar gas supplied from the air supply port 67 and the flow rate of N ２ gas is, for example, 10% to 50%. Since only Ar gas and N ２ gas are supplied into the processing container 51, the setting of the flow rate of each gas in this way means that the partial pressure of N ２ gas with respect to the total pressure in the processing container 51 is set to 10% to 50%. When forming the TiRuN film 12, within this range, the partial pressure of N ２ gas is changed for each substrate W, and the atomic% of nitrogen atoms in the TiRuN film 12 is changed between the substrates W so that desired electrical characteristics can be obtained for the TiRuN film. An instruction is transmitted from a host computer, which is a higher-level computer of the control unit 10 described later and is provided in the factory, to the control unit 10, and the operation of the valve and the mass flow controller provided in the gas supply mechanism 68 is controlled by the control unit 10, so that the adjustment of the partial pressure as described above is made. Incidentally, the flow rate of the above Ar gas is, for example, 40 sccm to 800 sccm.

[0031] Next, the processing module 5c will be described using the longitudinal side view shown in FIG. 4. The processing module 5c is configured to form, as a dielectric film, for example, ZrO ２ by ALD. ZrO ２This corresponds to a High-K material having a relatively high dielectric constant. Regarding the processing module 5c, parts configured similarly to processing module 5a are given the same reference numerals as those used for processing module 5a, and their explanations are omitted. Different structures are described below.

[0032] A portion of the side wall of the processing container 51 of the processing module 5c is formed by an annular duct 61c surrounding the stage 55, which will be described later, and a slit-shaped exhaust port 53 is provided along its inner circumferential surface. An exhaust mechanism 52 connected to the duct 61c maintains a vacuum atmosphere at a desired pressure inside the processing container 51.

[0033] The stage 55 inside the processing container 51 is provided to be vertically movable between a lower position for transferring the substrate W to and from the vacuum transfer mechanism 43 and an upper position for processing the substrate W. In the lower position, the substrate W is placed on the stage 55 via pins (not shown) on the stage 55. A heater 57c is embedded in the stage 55 to regulate the temperature of the substrate W placed on the stage 55.

[0034] A showerhead 62c, to which a gas supply mechanism 68 is connected, is provided on the ceiling of the processing container 51, facing the stage 55. The showerhead 62c has a gas diffusion space inside and multiple gas supply holes on its lower surface that communicate with the gas diffusion space, supplying various gases toward the stage 55. The gas supply mechanism 68 uses organic Zr gas as the raw material gas and O as the oxidizing gas. ３ It is configured to supply (ozone) gas. For example, the gas supply mechanism 68 supplies oxygen (O ２ ) Equipped with a gas supply source and an ozone generator, ２ From gas to O ３ Gas is generated and supplied. In the processing module 5c, for example, by alternately supplying a raw material gas and an oxidizing gas, a dielectric film of ZrO is formed on the surface of the substrate W. ２ A membrane is formed.

[0035] Next, we will briefly explain processing modules 5b and 5d, focusing on the differences from processing modules 5a and 5c. Processing module 5b, which deposits a TiN film, is configured similarly to processing module 5a, but the target 63 contains Ti as a component and does not contain Ru. Processing module 5d, which performs annealing, is configured similarly to processing module 5c, but the gas supply mechanism 68 uses, for example, N as the inert gas. ２ The system is configured to supply gas. In the processing module 5d, the substrate W is heated in an inert gas atmosphere at, for example, 250 to 600°C for 15 minutes or less. The TiRun film has relatively high heat resistance. Therefore, it is prevented from dissolving during annealing in the processing module 5d. Furthermore, even when high-temperature processing is performed on the substrate W after the capacitor has been formed, i.e., after the second electrode has been formed, the dissolution of the TiRun film is suppressed due to its relatively high heat resistance, so it is preferable to use the TiRun film as the first electrode.

[0036] Returning to Figure 1, the substrate processing system 1 includes a control unit 10, which is a computer. The control unit 10 includes a program, memory, and a CPU. The program contains instructions (each step) for processing and transporting the substrate W. This program is stored on a storage medium, such as a compact disk, hard disk, magneto-optical disk, DVD, etc., and installed in the control unit 10. The control unit 10 outputs control signals to each part of the substrate processing system 1 using this program, thereby controlling the operation of each part.

[0037] The operation of the above-mentioned substrate processing system 1, which is controlled by the control signal, includes the movement of each transport mechanism and the transport of substrates W between modules by raising and lowering the pins of the stage, the opening and closing of the gate valve G, the pressure change inside the housing 31 by supplying and exhausting gas in the LLM 3, the rotation of the stage 55 in each processing module 5a to 5d, the supply of gas from the air inlet 67, the pressure inside the processing container 51, and the switching of sputtering execution and stoppage by turning the power supply 64 on and off.

[0038] Next, the transport of the substrate W in the substrate processing system 1 and the processing performed by the film deposition method in this disclosure will be explained with reference to Figures 1 and 5. Figures 5(a) to 5(d) are longitudinal cross-sectional side views showing a substrate W whose surface is changed by processing, which is one embodiment of the film deposition method in this disclosure. First, the substrate W in the transport container C, which has been transported to the load port 23 of the film deposition apparatus 1a, is transported in the order of load lock module 3 → vacuum transport module 4 → processing module 5b, and a TiN film 11 is deposited on its surface (Figure 5(a)).

[0039] Next, the substrate W on which the TiN film 11 has been deposited is transported to the processing module 5a to deposit a TiRuN film 12 on the TiN film 11 (Figure 5(b)). The TiRuN film 12, together with the TiN film 11, constitutes the first electrode of the DRAM capacitor. Next, the substrate W on which the TiRuN film 12 has been deposited is transported to the LLM3 and returned to the transport container C in the load port 23, and the transport container C is transported to the load port 23 of the film deposition apparatus 1b. The substrate W in the transport container C that has been transported to the load port 23 of the film deposition apparatus 1b is transported from the LLM3 → vacuum transport module 4 → processing module 5c to deposit a dielectric film 13 on the TiRuN film 12 (Figure 5(c)).

[0040] Next, the substrate W on which the dielectric film 13 has been deposited is transported to the processing module 5d for annealing to stabilize the crystal structure of the dielectric film 13 and the first electrode. Then, the annealed substrate W is transported to the LLM3 and returned to the transport container C of the load port 23. The transport container C is then transported again to the load port 23 of the film deposition apparatus 1a, and the substrate W in the transport container C is transported to the processing module 5b in the same order as described above. Then, a TiN film 14 is deposited on the annealed dielectric film 13 (Figure 5(d)). As a result, the TiN film 14 constituting the second electrode of the capacitor is positioned opposite the TiN film 11 and TiRuN film 12 constituting the first electrode via the dielectric film 13. The substrate W on which the TiN film 14 has been deposited is returned to the transport container C of the load port 23 in the order described above. After that, various films are deposited on the substrate W and it is divided by dicing. Each divided piece is a semiconductor device equipped with the capacitor described above. Specifically, for example, the semiconductor device in question is the aforementioned DRAM, which is installed in various types of equipment.

[0041] (Modification) The TiRuN film 12 in this disclosure is formed by sputtering using a processing module 5a, but is not limited to this and can be formed by various manufacturing methods. As one example, as shown in Figure 6, the TiRuN film 12 can be formed by repeatedly and alternately depositing a TiN film 12a and a Ru film 12b using the ALD method. The concentration of Ru in the TiRuN film 12 is adjusted by adjusting the ratio of the thickness of the TiN film 12a and the thickness of the Ru film 12b within the TiRuN film 12. For example, the TiN film 12a can be made of TiCl ４ (Titanium tetrachloride) gas and NH ３ The film is formed by repeating a predetermined number of cycles in which (ammonia) gas is supplied alternately. For the formation of the Ru film 12b, Ru ３ (CO) １２ This is done by supplying a Ru-containing gas, such as a gas containing Ru, to the substrate W. Although Figure 6 shows the TiN film 12a and the Ru film 12b as clearly separated, the elements in the films are mixed by diffusion, so the boundaries between the films are not necessarily as clearly defined.

[0042] Another example is TiCl for Ti film deposition by CVD. ４ Gas, NH ３ The gas and the Ru-containing gas for Ru film deposition may be supplied simultaneously. In this case, the ratio of the elemental concentrations of Ti and Ru can be adjusted, for example, by adjusting the ratio of the supply flow rates and supply time of each deposition gas. Furthermore, in the sputter deposition example of this embodiment, a TiRuN film with an even Ru concentration distribution is deposited, but this is not limited to this, and for example, the concentration distribution may be varied downwards from the surface of the TiRuN film.

[0043] The first electrode in this embodiment is composed of a TiN film 11 and a TiRuN film 12, but is not limited to this, and the TiN film 11 may be replaced with another metal-containing film with relatively low resistivity. Alternatively, the first electrode may be composed only of the TiRuN film 12 without the TiN film 11. The dielectric film 13 in this embodiment is ZrO ２ Although it is a film, this is not an essential requirement; for example, it may be composed of other High-K materials, specifically Al２ O ３ , HfO ２ , TiO ｘ , TaO ｘ , STO(SrTiO ３ ), BTO (BaTiO ３ ), HfZrO ｘ Other metal oxides such as the above may also be used. The method for depositing the dielectric film 13 is not limited to ALD, and may be CVD or PVD, for example. The second electrode in this embodiment may be composed of another metal-containing film with relatively low resistivity instead of the TiN film 14. For example, the second electrode may also be composed of a TiRuN film. The method for depositing this second electrode is not limited to PVD and is arbitrary.

[0044] The apparatus configuration for the series of processes described in Figure 5 is also arbitrary. In the example above, the module for sputtering and the modules for ALD and annealing are mounted on separate devices, but the modules are not limited to being assigned to devices in this way. For example, the processing modules 5a to 5d may be connected to the vacuum transport module 4 of the film deposition apparatus 1a, so that the processes described in Figure 5 are performed only by the film deposition apparatus 1a.

[0045] (Evaluation Tests) The following describes the evaluation tests performed on a series of processes of the film deposition method in this disclosure. <Evaluation Test 1> As Evaluation Test 1, ZrO ２ O ３ The effect of heat treatment under a gas atmosphere on the electrical performance of the TiRuN film 12 was confirmed. In this evaluation test, ZrO ２ In order to reproduce the film deposition process, O is applied to a substrate on which a TiRun film 12 has been formed on its surface. ３ The TiRuN film 12 was subjected to an annealing process with a gas supply, and the change in resistivity was confirmed as an indicator of its electrical performance. To provide a comparison for the evaluation of this TiRuN film 12, various TiN-containing films, including TiN films and metals other than Ru, were formed on the surface of each substrate, and evaluation tests were conducted in the same manner.

[0046] The TiN-containing films used in this evaluation test were those containing W (tungsten), Mo (molybdenum), Al (aluminum), V (vanadium), Mn (manganese), Hf (hafnium), Zr (zirconium), and Nb (niobium), respectively, as shown in Figures 7 and 8. Each TiN-containing film was formed by sputtering using a target containing each respective metal, similar to the TiRuN film.

[0047] Incidentally, when forming alloy films such as the TiRuN film and TiWN film described above, which consist of Ti, a different type of metal than Ti, and N, the different type of metal may be described as an alloy constituent metal, and the alloy film may be described as a TiN alloy film. In evaluation test 1, a TiN film was also formed using a target made only of Ti. Hereafter, for the sake of explanation, TiN alloy films such as TiN films and TiRuN films will be collectively referred to as TiN-containing films.

[0048] In this evaluation test 1, the annealing treatment was performed by supplying 3750 sccm of oxygen gas to an ozone generator for each substrate equipped with the various TiN-containing films described above, to a concentration of 300 g / Nm³. ３ O ３ The annealing process was carried out by supplying gas and heating the substrate to 300°C under an atmosphere of 400 Pa (3 torr) pressure. The resistivity of each TiN-containing film was measured by varying the annealing time.

[0049] Figure 7 is a graph showing the results of Evaluation Test 1, illustrating the change in resistivity of each TiN-containing film with respect to annealing time. Figure 8 is a table showing the rate of change in resistivity for each TiN-containing film with respect to annealing time, where the rate of change in resistivity is the rate of change in resistivity at each treatment time relative to the resistivity before annealing. In Figure 7, the plot for the TiAlN film is omitted, and for the TiZrN film, only the result for an annealing time of 1 minute is shown because the resistivity value increased significantly as shown in Figure 8.

[0050] As shown in Figure 7, the TiN alloy films other than the TiRun film had higher resistivity than the TiN film at each annealing time, including the case of 0 minutes. Note that 0 minutes of annealing time means before annealing. The TiN-containing films other than the TiRun film and the TiN film all showed an increase in resistivity as the annealing time increased, to varying degrees. In contrast, the TiRun film had lower resistivity than the TiN film regardless of the annealing time, and the rate of change in resistivity was 4% at 1 minute, 2.4% at 3 minutes, and 0.6% at 10 minutes, which can be considered almost zero.

[0051] The reason for the increase in resistivity due to annealing is, ３ The expansion of the oxide layer thickness in each TiN-containing film due to gas was confirmed by separately measuring the thickness of each oxide layer using TEM (Transmission Electron Microscopy). The thickness of the oxide layer in the TiN film was 5.3 nm after 10 minutes of annealing, while the thickness of each oxide film, such as the TiZrN film and TiHfN film, which have greater resistivity and rate of change than the TiN film, increased to slightly less than 10 nm. Therefore, the Zr, Hf, etc. contained in these films are O ３ It was thought to have low oxidation resistance to gas. On the other hand, the oxide layer thickness of the TiRuN film, which has lower resistivity than TiN, is relatively thin, for example, 2.9 nm after 10 minutes of annealing, and Ru is O ３ It was considered to have high oxidation resistance.

[0052] <Additional Evaluation> However, the cause of the suppression of the increase in resistivity cannot be limited to the oxidation resistance of the contained metal, and the O supplied during the annealing process may also be a factor. ３ Since the gas also has etchant properties, there is a possibility that the oxide layer in the film was etched and thinned. Therefore, as an additional evaluation, the thickness of the TiRun film was measured by TEM. This measurement was performed on the TiRun film before the annealing treatment (treatment time 0 minutes) and on the TiRun film after 10 minutes of annealing treatment. In addition, the substrate on which the TiRun film was formed was heated to 300°C. ２ An annealing test is also being conducted, in which gas is supplied for 10 minutes. ２Regarding the TiRun film annealed with gas, O ３ Similar to the TiRun film annealed with gas, the film was evaluated by imaging using TEM.

[0053] As a result, the thickness of the TiRun film before annealing was 59.5 nm. ２ The thickness of the TiRun film after gas annealing is 62.9 nm. ３ The thickness of the TiRun film after gas annealing was 62.5 nm. Thus, the gas used for annealing was O ２ Gas, O ３ Regardless of which gas was used, the difference in the thickness of the TiRuN film before and after annealing was small. Therefore, it was revealed that the TiRuN film has high oxidation resistance, and it was confirmed that the suppression of the change in resistivity of the TiRuN film, as shown in Figures 7 and 8, was not due to the simultaneous oxidation and etching of the TiRuN film, but rather due to the high oxidation resistance of the TiRuN film.

[0054] <Evaluation Test 2> In Evaluation Test 2, SiO was found on the surface. ２ Multiple substrates with (silicon oxide) films formed on them were prepared. Then, a Ru film was formed on one substrate and a TiRuN film was formed on the other substrates. ３ Gas annealing was performed. The condition of each substrate before and after annealing was confirmed using TEM.

[0055] For the substrate before annealing, where the Ru film was formed, the Ru film thickness was 45.3 nm, and the thickness of the oxide layer on the Ru film was less than 1 nm. After annealing, the Ru film thickness was 40.5 nm, and an oxide layer, called a whisker, which grew unevenly in various parts, was observed on the Ru film. Figure 9A shows a TEM image of the substrate with the Ru film formed on it after annealing. The maximum thickness of the oxide layer was approximately 51 nm.

[0056] For the substrate with the TiRunN film formed on it before annealing, the thickness of the TiRunN film was 64.8 nm, and the thickness of the oxide layer on the TiRunN film was less than 1 nm. After annealing of this substrate, the thickness of the TiRunN film was 62.4 nm, and the thickness of the oxide layer on the TiRunN film was 2.9 nm. Therefore, the increase in the thickness of the oxide layer due to annealing was slight. Furthermore, no whiskers were observed in the oxide layer after annealing. Figure 9B shows the TEM image of the substrate with the TiRunN film formed on it after annealing. From the results of the above evaluation test 2, it can be concluded that for the substrate with the TiRunN film formed on it, O ３ When performing gas annealing, apply O to the substrate on which the Ru film has been formed. ３ Unlike gas annealing, it was confirmed that abnormal growth of the oxide layer is prevented, and the increase in the thickness of the oxide layer can be kept to a minimum.

[0057] <Evaluation Test 3> Evaluation Test 3 was conducted to verify the oxygen permeability and oxidation resistance of the TiRuN film. In Evaluation Test 3-1, TiN film 11, TiRuN film 12, and TiN film 14 were sequentially deposited on a silicon wafer substrate W. Therefore, in this Evaluation Test 3-1, unlike the embodiment, the dielectric film ZrO ２ No film was deposited. The thickness of the TiRun film was set to 10 nm. In evaluation test 3-2, as in the embodiment, a TiN film 11, a TiRun film 12, and a dielectric film (ZrO) were applied to a silicon wafer substrate W. ２ Film 13 and TiN film 14 were deposited in sequence. ２ The film thickness was set to 6 nm, and the thickness of the TiRuN film was set to 3 nm, which is smaller than the thickness used in evaluation test 3-1. In evaluation test 3-3, similar to evaluation test 3-2, a TiN film 11, a TiRuN film 12, and a dielectric film (ZrO) were applied to a silicon wafer substrate W. ２ Film 13 and TiN film 14 were deposited in sequence. ２ The film thickness was set to 6 nm, and the TiRun film thickness was set to 10 nm, the same as in evaluation test 3-1. Cross-sections of each substrate W on which the films were formed were imaged and processed to investigate the types of atoms present at and near the interface between the TiN film 11 and the TiRun film 12.

[0058] Observation of each image revealed no significant change in the distribution of oxygen atoms between evaluation tests 3-1 to 3-3. Therefore, in evaluation tests 3-2 and 3-3, ZrO ２ During the formation of the film, it was confirmed that oxygen does not permeate the TiRuN film 12, the oxidation of the TiN film 11 is suppressed, and the TiRuN film 12 has high oxidation resistance.

[0059] <Evaluation Test 4> As Evaluation Test 4-1, a TiN film 11, a TiRuN film 12, and a dielectric film (ZrO) were applied to a silicon wafer substrate. ２ Film 13 and TiN film 14 were deposited in sequence. Furthermore, Al films were deposited as electrode films on the front and back surfaces of this substrate, and the K value (dielectric constant) was measured by applying a voltage. Evaluation test 4-2 was conducted in the same manner as evaluation test 4-1, except that the TiRun film 12 was not deposited, and evaluation test 4-3 was conducted in the same manner as evaluation test 4-1, except that a TiWN film was deposited instead of the TiRun film.

[0060] The K value could not be measured in evaluation test 4-1, but it could be measured in evaluation tests 4-2 and 4-3. When TEM images were acquired for each substrate in evaluation tests 4-1 to 4-3, the dielectric film (ZrO) was found to have been removed from the TiRun film 12 in the substrate of evaluation test 4-1. ２ It was confirmed that the K value could not be measured due to the partial peeling of the film 13, which formed a cavity called a blister, and that this peeling of the dielectric film 13 was the cause. Figure 10 is a schematic diagram of the acquired image.

[0061] In evaluation tests 4-2 and 4-3, ZrO was released from the TiN film 11 on each substrate. ２ Film peeling, ZrO from TiWN film ２ No delamination of the film was observed in either case. Considering the results of this evaluation test 4 and evaluation test 1 together, as mentioned in the embodiment, the TiRun film has extremely high oxidation resistance, and ZrO ２ Because of its low adhesion to the film, the ZrO ２ It is presumed that peeling occurred.

[0062] The TiRuN film 12 in this evaluation test 4 was formed using a target with the same composition as in evaluation test 5-1 and under the same processing conditions as in evaluation test 5-1. Therefore, based on the verification performed in evaluation test 5-1, the concentration of Ru is estimated to be 73 atomic percent. ２ To prevent delamination of the film, it is estimated that the Ru concentration in the TiRuN film 12 should be lower than 73% of the atoms.

[0063] <Evaluation Test 5> In Evaluation Test 5, we will examine the change in resistivity when the Ru concentration in the TiRuN film is reduced from 73 atomic percent. In detail, in Evaluation Test 5-1, various TiN alloy films were deposited on a substrate by sputtering using the same target as in Evaluation Test 1. Of the TiN alloy films deposited on the substrate in this way, the composition ratio of the TiRuN film was analyzed, and it was confirmed that the alloy constituent metals Ru accounted for 73 atomic percent, Ti 12 atomic percent, and N 15 atomic percent, respectively, were contained in the film. In Evaluation Test 5-1, since each film was deposited under the same processing conditions except for the difference in the elements constituting the target, it is estimated that the content ratio of alloy constituent metals (such as W) in TiN alloy films other than the TiRuN film (such as the TiWN film) is also 73 atomic percent, the same as Ru.

[0064] Furthermore, in this evaluation test 5, as evaluation test 5-2, various TiN alloy films were deposited by using a target with a different composition ratio of Ti to alloy constituent metals than the target used in evaluation test 5-1. Among the deposited TiN alloy films, the composition ratio of the TiRuN film was analyzed, and it was confirmed that it contained 10 atomic percent Ru. In this evaluation test 5-2, as in evaluation test 5-1, each film was deposited under the same processing conditions, except for the difference in the elements constituting the target. Therefore, it is estimated that the content of alloy constituent metals in TiN alloy films other than the TiRuN film (such as the TiWN film) is also 10 atomic percent, the same as Ru.

[0065] In evaluation tests 5-1 and 5-2, TiN alloy films were deposited on each substrate with varying film thicknesses. The resistivity of each film was then measured for each film thickness. Incidentally, while evaluation test 5 has described the deposition of TiN alloy films, for comparison, TiN films and Ru films were also deposited with varying film thicknesses and their resistivity was measured.

[0066] Figures 11 and 12 are graphs showing the results of evaluation test 5, illustrating the relationship between film thickness and resistivity in each TiN-containing film and Ru film. Figure 11 shows the results for each TiN alloy film, TiN film, and Ru film containing each alloy constituent metal at a concentration of 73 atomic percent, while Figure 12 shows the results for each TiN alloy film and TiN film containing each alloy constituent metal at a concentration of 10 atomic percent.

[0067] As shown in Figure 11, when comparing the resistivity of each TiN alloy film and TiN film when the contained alloying metal is at a high concentration (73 atomic%), the resistivity of the TiRuN film is the lowest at each film thickness. Furthermore, as shown in Figures 11 and 12, the resistivity of the TiRuN film is higher when the Ru concentration is low (10 atomic%) than when it is high. On the other hand, as shown in Figure 12, when the contained Ru is at a low concentration, the resistivity of the TiRuN film is slightly higher than that of the TiN film in the range of relatively large film thicknesses. However, when the film thickness becomes thinner than approximately 5 nm, the resistivity of the TiRuN film is kept low compared to the TiN film, which shows a sharp increase in resistivity in this range. Moreover, in this film thickness range, the resistivity of the TiRuN film is kept relatively low among the various TiN alloy films, and there are no practical problems. From the results of the above evaluation test 5, it was confirmed that the resistivity of the TiRuN film can be sufficiently suppressed even when the Ru concentration is lower than 73 atomic%,.

[0068] <Evaluation Test 6> In Evaluation Test 6, a capacitor was formed on a substrate W, equipped with a first electrode made of various TiN-containing films such as a TiRun film, and the leakage current and other properties were evaluated. The structure of this capacitor will be described in more detail below. For some substrates W, as explained in Figure 5, a TiN film 11, a TiRun film 12, and a ZrO ２A capacitor was formed by sequentially stacking a dielectric film 13 and a TiN film 14. For the other substrates W, a capacitor was formed by performing the same process as described in Figure 5, except that a TiNiN film was deposited instead of the TiRuN film 12, or neither the TiRuN film nor the TiNiN film was deposited.

[0069] In depositing the TiRuN film 12 and the TiNiN film, the same composition ratio target as used in evaluation test 5-2 was used, and the same processing conditions as in evaluation test 5-2 were set. However, the film deposition time was set to achieve a film thickness of 10 nm. As the films were deposited in this manner, the concentrations of Ru and Ni in the TiRuN film 12 and the TiNiN film can be considered to be 10 atomic percent each, the same as the concentrations in evaluation test 5-2. Furthermore, an Al film was deposited as an electrode film on the back and front surfaces of each substrate W that formed the capacitor structure by depositing each film as described above. Therefore, the silicon layer constituting the substrate W is positioned to be laminated on the lower Al film, and the upper Al film is positioned to be laminated on the TiN film 14.

[0070] Further explanation will be given regarding the film structure formed on the substrate W. Two substrates each were prepared: one with a TiRuN film 12 formed on it, one with a TiNiN film formed on it, and one without either a TiRuN film 12 or a TiNiN film formed on it. ２ The films were deposited on two substrates with thicknesses of 4 nm and 6 nm, respectively. The thickness of the TiN films 11 and 14 was 15 nm, and the thickness of the Al film was 40 nm. On each substrate W formed as described above, a voltage of 1 V was applied between the Al films, and the capacitance and leakage current of each capacitor were measured. Hereafter, for the sake of explanation, the substrate W containing the TiRuN film 12, the substrate W containing the TiNiN film, and the substrate W without the TiRuN film 12 and the TiNiN film will be referred to as the TiRuN capacitor, the TiNiN capacitor, and the TiN capacitor, respectively.

[0071] Figure 13 shows each TiN-containing film and ZrO with different film thicknesses. ２ This graph shows the performance of each capacitor equipped with [a specific component]. In the same figure, the horizontal axis represents the SiO2 corresponding to the capacitance of each capacitor. ２The graph shows the film thickness, CET (capacitive equivalent thickness) [nm], with the vertical axis representing the leakage current [A / cm²]. ２ The settings were configured. Then, the leakage current and CET measured on each board were plotted. In the graph, ZrO ２ In addition to the film thickness, straight lines are drawn connecting the plots obtained from capacitors with the same structure. Note that the graph in Figure 13 is a semi-logarithmic graph, with the vertical axis on a logarithmic scale.

[0072] A smaller CET value and a smaller leakage current value are desirable characteristics for a capacitor, so the measurement result is preferable if it is located towards the lower left of the graph in Figure 13. As shown in the graph, the lines drawn from the plots of TiNiN capacitors and TiN capacitors intersect. Furthermore, the line drawn from the plot of TiRuN capacitors is located further to the lower left of the graph than the lines drawn from the plots of TiNiN capacitors and TiN capacitors.

[0073] Therefore, it was confirmed that the TiRuN capacitor exhibits better characteristics than the TiNiN capacitor and the TiN capacitor. Furthermore, regarding the results of this evaluation test 6, it can be seen that by depositing a TiRuN film 12 as a film constituting the lower electrode (first electrode) of the capacitor, better capacitor characteristics can be obtained than when the TiRuN film 12 is not deposited. It was also shown that depositing a TiN alloy film as a film constituting the lower electrode does not necessarily improve the characteristics of the capacitor, and that it is necessary to select a metal material to form the film together with Ti, and that the TiRuN film is effective as a TiN alloy film that improves the characteristics of the capacitor in this way.

[0074] Furthermore, regarding the TiRun capacitor, as shown in Figure 13, its characteristics can be measured, which is similar to the ZrO shown in Figure 10. ２ It is presumed that no delamination of the film occurred. Therefore, from this evaluation test 6, it can be concluded that by setting the Ru content in the TiRuN film 12 to 10 atomic percent or less, the strong oxidation resistance characteristic of the TiRuN film will be reduced. ２It was also found that this method can suppress film peeling.

[0075] W Wafer 12 TiRun film 13 Dielectric film 14 TiN film

Claims

1. A film formation method comprising: a step of forming a titanium ruthenium nitride film having a ruthenium content lower than 73 atomic percent on a substrate; a step of forming a dielectric film to be laminated on the titanium ruthenium nitride film; and a step of forming a metal-containing film to be laminated on the dielectric film.

2. The method for forming a film according to claim 1, wherein the concentration of ruthenium contained in the titanium ruthenium nitride film is 10 atomic percent or less.

3. The method for forming a film according to claim 2, wherein the step of forming the titanium ruthenium nitride film is a step of forming the film by sputtering.

4. The method for forming a titanium ruthenium nitride film according to claim 3, wherein the step of forming the titanium ruthenium nitride film is to perform sputtering on a target which is an alloy of titanium and ruthenium and is provided in a processing vessel to which a plasma generating gas and a gas containing nitrogen atoms are supplied, and to form the film on a substrate stored in the processing vessel.

5. The method for forming a film according to claim 1, wherein the dielectric film is a metal oxide film.

6. The method for forming a film according to claim 5, wherein the metal oxide is zirconium oxide.

7. The method for forming a film according to claim 1, wherein the metal-containing film is a film containing titanium nitride.

8. A film deposition apparatus comprising: a titanium ruthenium nitride film deposition unit for depositing a titanium ruthenium nitride film having a ruthenium concentration lower than 73 atomic percent onto a substrate; a dielectric film deposition unit for depositing a dielectric film to be laminated on the titanium ruthenium nitride film; and a metal-containing film deposition unit for depositing a metal-containing film to be laminated on the dielectric film.

9. A semiconductor device comprising a titanium ruthenium nitride film having a ruthenium concentration lower than 73 atomic percent, a dielectric film laminated on the titanium ruthenium nitride film, and a metal-containing film laminated on the dielectric film.

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