Thin film deposition method, thin film deposition apparatus, and semiconductor device.

Abstract

To suppress the occurrence of defects in a substrate in which a titanium ruthenium nitride film, a dielectric film, and a metal-containing film are stacked in that order. [Solution] The film formation method of the present disclosure comprises the steps of: forming a titanium ruthenium nitride film having a ruthenium content lower than 73 atomic percent on a substrate; forming a dielectric film to be laminated on the titanium ruthenium nitride film; and forming a metal-containing film to be laminated on the dielectric film.

Description

Technical Field

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

Background Art

[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 on the surface of the substrate so as to face each other through a dielectric film, and a metal oxide which is a High-K material having a relatively high dielectric constant may be used for the dielectric film. The first and second electrodes may be configured by laminating metal-containing films containing different metals.

[0003] Patent Document 1 describes forming a nitride alloy film as a barrier layer under a copper-containing plating film to prevent the 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.

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 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.

Means for Solving the Problems

[0006] The film-forming method of this disclosure comprises the steps of: forming a titanium ruthenium nitride film having a ruthenium content lower than 73 atomic percent on a substrate; forming a dielectric film to be laminated on the titanium ruthenium nitride film; and forming a metal-containing film to be laminated on the dielectric film. [Effects of the Invention]

[0007] This disclosure can suppress the occurrence of defects in a substrate in which a titanium ruthenium nitride film, a dielectric film, and a metal-containing film are stacked in that order. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing a substrate processing system according to an embodiment. [Figure 2] This is a plan view illustrating a substrate processing apparatus that constitutes the aforementioned substrate processing system. [Figure 3] This is a longitudinal cross-sectional side view showing a processing module provided in the aforementioned substrate processing apparatus. [Figure 4] A longitudinal cross-sectional side view showing other processing modules. [Figure 5] This is a longitudinal cross-sectional side view showing the surface changes of a substrate that has undergone processing according to the embodiment. [Figure 6] This is a longitudinal cross-sectional side view showing a TiRuN film formed by another manufacturing method. [Figure 7] This graph shows the results of Evaluation Test 1. [Figure 8] This table shows the results of Evaluation Test 1. [Figure 9A] This is the first image showing the results of evaluation test 2. [Figure 9B] This is the second image showing the results of evaluation test 2. [Figure 10] This is a schematic diagram of the image showing the results of evaluation test 4. [Figure 11] This is the first graph showing the results of evaluation test 5. [Figure 12] This is the second graph showing the results of evaluation test 5. [Figure 13] This graph shows the results of evaluation test 6.

Mode for Carrying Out the Invention

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

[0010] Although it will be specifically shown later with reference to FIG. 5, briefly explained here, as the films constituting the first electrode, a TiN film and a TiRuN (titanium ruthenium nitride) film are sequentially formed on the substrate W. Subsequently, ZrO2 (zirconium oxide) is formed as the dielectric film. Thereafter, an annealing process is performed, and a TiN (titanium nitride) film, which is a metal-containing film, is formed as the second electrode. Therefore, the TiN film, the TiRuN film, the ZrO2 film, and the TiN film are sequentially laminated. In this example, the TiRuN film and the TiN film are formed by PVD, more specifically, sputtering, and the ZrO2 film is formed by ALD.

[0011] As described above, since each film is laminated, the upper layer portion (surface portion) of the first electrode that contacts the ZrO2 film is composed of the TiRuN film. Stating the reason for constructing the first electrode in this way, when forming the dielectric film, O3 gas having a strong oxidizing power is supplied. As shown in the test examples described later, the TiRuN film 12 has high oxidation resistance and tends to block the permeation of oxygen, preventing the oxidation of the TiN film 11 below it. Thereby, the oxidation of the surface portion of the first electrode composed of the TiN film 11 and the TiRuN film 12 is suppressed, preventing the specific resistance of the surface portion from increasing and becoming dielectric. That is, by forming the TiRuN film as the first electrode, the decrease in the conductivity of the first electrode is prevented.

[0012] However, when forming the TiRuN film in this way, it was confirmed that the dielectric film (ZrO2 film) may peel off from the TiRuN film as shown in the evaluation test later. This is considered to be due to the fact that the oxidation resistance of the TiRuN film is too high, and after the formation of the dielectric film, the surface layer of the TiRuN film has a low oxygen content, resulting in 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, ensure the adhesion between the dielectric film and the TiRuN film, and prevent the above peeling. Specifically, in this example, film formation is performed so that the concentration of ruthenium in the TiRuN film is 10 atomic% by adjusting the ratio of metal elements contained in the target used in sputtering.

[0013] Hereinafter, the substrate processing system 1 shown in FIG. 1 will be described. The substrate processing system 1 includes a film forming apparatus 1a that forms a film by sputtering and a film forming apparatus 1b that performs ALD and annealing. Therefore, the first electrode and the second electrode are formed by the film forming apparatus 1a, and the dielectric film is formed by the film forming apparatus 1b. The substrate W is transported between the film forming apparatuses 1a and 1b in a state of being housed in the transport container C by a transport mechanism provided in the factory where the substrate processing system 1 is installed. The film forming apparatus 1a includes a processing module (TiNRu film forming section) 5a for forming a TiNRu film and a processing module (metal-containing film forming section) 5b for forming a TiN film. The film forming apparatus 1b includes a processing module (dielectric film forming section) 5c for forming a dielectric film and a processing module 5d for performing an annealing process.

[0014] Representing the film forming apparatuses 1a and 1b, the film forming apparatus 1a will be described with reference to the plan view of FIG. 2. The film forming apparatus 1a is configured by arranging an atmospheric transport module 2, two load lock modules 3, a vacuum transport module 4, and processing modules 5a and 5b from the front to the rear. The load lock module (Load Lock Module) may be described as LLM hereinafter.

[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 has, for example, three load ports 23 for transferring substrates W between the transport container C and LLM3, 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 LLM3.

[0017] 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, to which the LLM3, processing modules 5a and 5b are connected via gate valves G. The inside of the housing 41 is evacuated by an exhaust mechanism (not shown), maintaining a vacuum atmosphere at a predetermined pressure 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 LLM3.

[0019] The film deposition apparatus 1b has the same configuration as the film deposition apparatus 1a, except that the shape of the vacuum transfer module 4 and the number of processing modules connected to the vacuum transfer 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 × 10⁻⁶) 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 from the processing container 51 by including a valve and a vacuum pump, so that 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 transfer mechanism 43 of the vacuum transfer 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 a plan view, for example, four through holes are provided in the circumferential direction in this sloping section. 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 in a plan view. 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 to achieve a Ru concentration of 10 atomic percent in the TiRuN film, the proportion of Ru contained in the target 63 is adjusted 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%, so the Ru concentration of the TiRuN film may be set to a relatively high value within a range lower than 73 atomic%. 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 vessel 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] Furthermore, an air inlet 67 is opened inside the processing container 51, and gas is supplied into the processing container 51 from the gas supply mechanism 68 via the air inlet 67. This gas is a mixture of an inert gas for sputtering (for plasma formation by applying voltage from the power supply 64) and a nitriding gas for nitriding Ti and Ru. Specifically, for example, the inert gas is argon (Ar) gas, and the nitriding gas is for example, N2 (nitrogen) gas. The gas supply mechanism 68 is equipped with a source for supplying Ar gas, a source for supplying N2 gas, valves for switching between supplying and stopping the supply 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 N2 gas flow rate to the sum of the Ar gas flow rate and N2 gas flow rate supplied from the air inlet 67 is, for example, 10% to 50%. Since only Ar gas and N2 gas are supplied into the processing container 51 from the air inlet 67, setting the flow rates of each gas in this way means that the partial pressure of N2 gas relative to the total pressure in the processing container 51 is set to 10% to 50%. When depositing the TiRuN film 12, the partial pressure of N2 gas may be changed for each substrate W within this range so that the atomic percentage of nitrogen atoms in the TiRuN film 12 changes between substrates W, thereby obtaining the desired electrical characteristics of the TiRuN film. Instructions are sent to the control unit 10 from a host computer installed in the factory, which is a higher-level computer of the control unit 10 described later, and the operation of the valves and mass flow controller installed in the gas supply mechanism 68 is controlled by the control unit 10 to adjust the partial pressure as described above. The flow rate of Ar gas is, for example, 40 sccm to 800 sccm.

[0031] Next, the processing module 5c will be described using the longitudinal cross-sectional side view shown in Figure 4. The processing module 5c is configured to deposit a dielectric film, for example, ZrO2, using ALD. ZrO2 is a High-K material with a relatively high relative permittivity. For parts of the processing module 5c that are configured in the same way as the processing module 5a, the same reference numerals as those used for the processing module 5a are used, and their explanations are omitted. The different structures will be 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 a plurality of 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 is configured to supply organic Zr gas as a raw material gas and O3 (ozone) gas as an oxidizing gas. For example, the gas supply mechanism 68 is equipped with an oxygen (O2) gas supply source and an ozone generator, and generates and supplies O3 gas from O2 gas. In the processing module 5c, for example, by alternately supplying the raw material gas and the oxidizing gas, a ZrO2 film is formed on the surface of the substrate W as a dielectric film.

[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 is configured to supply, for example, N2 gas as an inert gas. In 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. Incidentally, the TiRuN film has relatively high heat resistance. Therefore, dissolution during annealing in processing module 5d is prevented. 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 LLM3, 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, the semiconductor device in question is, for example, the DRAM described above, which is installed in various types of equipment.

[0041] (modified version) 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 methods. As an 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 to the thickness of the Ru film 12b within the TiRuN film 12. For example, the TiN film 12a is formed by repeating a predetermined number of cycles in which TiCl4 (titanium tetrachloride) gas and NH3 (ammonia) gas are supplied alternately. For the Ru film 12b, Ru3 (CO3) 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 being 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 that TiCl4 gas and NH3 gas for Ti film deposition and Ru-containing gas for Ru film deposition may be supplied simultaneously by CVD. In this case, the ratio of 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 a ZrO2 film, but this is not a mandatory requirement; for example, it may be composed of other high-K materials, specifically Al2O3, HfO2, TiO2 x TaO x , STO(SrTiO3), BTO(BaTiO3), 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 used for example by CVD or PVD. 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 test) The following describes the evaluation tests performed on a series of processes related to the film deposition method described herein. <Evaluation Test 1> As part of Evaluation Test 1, the effect of heat treatment under an O3 gas atmosphere, which is performed during ZrO2 film deposition, on the electrical performance of the TiRuN film 12 was confirmed. In this evaluation test, in order to reproduce the ZrO2 film deposition process, an annealing treatment was performed by supplying O3 gas to a substrate on which the TiRuN film 12 had been formed on its surface, and the change in resistivity was confirmed as the 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 performed 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), as shown in Figures 7 and 8. Each TiN-containing film was formed by sputtering using targets containing each respective metal, similar to the TiRuN films.

[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 deposited using a target made only of Ti. Hereafter, for the sake of convenience in explanation, TiN films, TiRuN films, and other TiN alloy 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. 3The annealing process was carried out by supplying O3 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 treatment 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 resistivity of the TiN alloy films other than the TiRuN film was higher than that of the TiN film at each annealing time, including the case of 0 minutes. Note that 0 minutes of annealing time means before annealing treatment. The resistivity of the TiN-containing films other than the TiRuN film and the TiN film increased to varying degrees as the annealing time increased. In contrast, the resistivity of the TiRuN film was lower than that of 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 said to be almost zero.

[0051] The reason for the increase in resistivity due to annealing is the expansion of the oxide layer thickness in each TiN-containing film due to O3 gas, which was confirmed by measuring the thickness of each oxide layer separately using TEM (Transmission Electron Microscopy). The oxide layer thickness in the TiN film was 5.3 nm after 10 minutes of annealing, while the thickness of the oxide films such as the TiZrN film and TiHfN film, which have higher resistivity and a greater rate of change than the TiN film, increased to slightly less than 10 nm. Therefore, it was considered that the Zr, Hf, etc. contained in these films have low oxidation resistance to O3 gas. On the other hand, the oxide layer thickness of the TiRuN film, which has lower resistivity than TiN, was relatively thin, for example, 2.9 nm after 10 minutes of annealing, suggesting that Ru has high oxidation resistance to O3.

[0052] <Additional evaluation> However, the cause of the increased resistivity cannot be limited to the oxidation resistance of the contained metals, and since the O3 gas supplied during the annealing process 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 process (processing time 0 minutes) and on the TiRuN film after 10 minutes of annealing. In addition, an annealing test was also performed in which O2 gas was supplied for 10 minutes while the substrate on which the TiRuN film was formed was heated to 300°C. The TiRuN film annealed with O2 gas was also imaged and evaluated by TEM, similar to the TiRuN film annealed with O3 gas.

[0053] As a result, the thickness of the TiRuN film before annealing was 59.5 nm, the thickness of the TiRuN film after annealing with O2 gas was 62.9 nm, and the thickness of the TiRuN film after annealing with O3 gas was 62.5 nm. Thus, regardless of whether O2 gas or O3 gas was used for annealing, 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 oxidation and etching of the TiRuN film occurring simultaneously, but rather due to the high oxidation resistance of the TiRuN film.

[0054] <Evaluation Test 2> In evaluation test 2, multiple substrates with SiO2 (silicon oxide) films formed on their surfaces were prepared. A Ru film was formed on one substrate, and a TiRuN film on the other substrates, and then annealing was performed using O3 gas. The state of each substrate before and after annealing was confirmed using a 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 non-uniformly grown oxide layers, known as whiskers, were observed on the Ru film. Figure 9A shows a TEM image of the substrate after annealing where the Ru film was formed. The maximum thickness of the oxide layer was approximately 51 nm.

[0056] For the substrate with the TiRuN film formed on it before annealing, the thickness of the TiRuN film was 64.8 nm, and the thickness of the oxide layer on the TiRuN film was less than 1 nm. After annealing, the thickness of the TiRuN film was 62.4 nm, and the thickness of the oxide layer on the TiRuN 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 a TEM image of the substrate with the TiRuN film formed on it after annealing. From the results of evaluation test 2 above, it was confirmed that when annealing a substrate with a TiRuN film formed on it is performed with O3 gas, unlike when annealing a substrate with a Ru film formed on it with O3 gas, 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, unlike the embodiment, the dielectric film ZrO2 film was not deposited in this Evaluation Test 3-1. The thickness of the TiRuN film was 10 nm. In Evaluation Test 3-2, similar to the embodiment, TiN film 11, TiRuN film 12, dielectric film (ZrO2 film) 13, and TiN film 14 were sequentially deposited on a silicon wafer substrate W. The thickness of the ZrO2 film was 6 nm, and the thickness of the TiRuN film was smaller than that in Evaluation Test 3-1, at 3 nm. In Evaluation Test 3-3, similar to Evaluation Test 3-2, TiN film 11, TiRuN film 12, dielectric film (ZrO2 film) 13, and TiN film 14 were sequentially deposited on a silicon wafer substrate W. The thickness of the ZrO2 film was set to 6 nm, and the thickness of the TiRuN film 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, it was confirmed that oxygen did not permeate the TiRuN film 12 when forming the ZrO2 film, suppressing the oxidation of the TiN film 11, and that the TiRuN film 12 possessed high oxidation resistance.

[0059] <Evaluation Test 4> For evaluation test 4-1, TiN film 11, TiRuN film 12, dielectric film (ZrO2 film) 13, and TiN film 14 were sequentially deposited on a silicon wafer substrate. 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. For evaluation test 4-2, the same test as evaluation test 4-1 was performed except that the TiRuN film 12 was not deposited, and for evaluation test 4-3, the same test as evaluation test 4-1 was performed except that a TiWN film was deposited instead of a TiRuN film.

[0060] Regarding the K value, it was not possible to measure it in evaluation test 4-1, but it was possible to measure it in evaluation tests 4-2 and 4-3. When TEM images were acquired for each substrate in evaluation tests 4-1 to 4-3, it was confirmed that in the substrate of evaluation test 4-1, a cavity called a blister was formed due to the partial peeling of the dielectric film (ZrO2 film) 13 from the TiRuN film 12, and that the K value could not be measured due to this peeling of the dielectric film 13. Figure 10 is a schematic diagram of the acquired images.

[0061] In evaluation tests 4-2 and 4-3, no peeling of the ZrO2 film from the TiN film 11 or the TiWN film was observed in either substrate. Considering the results of evaluation test 4 and evaluation test 1 together, as mentioned in the embodiment, it is presumed that the peeling of the ZrO2 occurred because the TiRuN film has extremely high oxidation resistance and therefore poor adhesion to the ZrO2 film.

[0062] In this evaluation test 4, the TiRuN film 12 was formed using the same target 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 Ru concentration is estimated to be 73 atomic percent. Accordingly, in order to prevent peeling of the ZrO2 film, it is estimated that the Ru concentration in the TiRuN film 12 should be lower than 73 atomic percent.

[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 contained 73 atomic percent Ru, 12 atomic percent Ti, and 15 atomic percent N. 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 purposes, 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 leakage current and other parameters were evaluated. The structure of this capacitor will be described in more detail below. For some substrates W, a capacitor was formed by sequentially stacking a TiN film 11, a TiRuN film 12, a dielectric film 13 which is a ZrO2 film, and a TiN film 14, as explained in Figure 5. For other substrates W, a capacitor was formed by performing the same process as explained in Figure 5, except that a TiNiN film was deposited instead of the TiRuN film 12, or neither a TiRuN film nor a 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 film deposition was performed 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 stacked on the lower Al film, and the upper Al film is positioned to be stacked on the TiN film 14.

[0070] The film structure formed on the substrate W will be explained further. Two substrates were prepared with a TiRuN film 12, two substrates with a TiNiN film, and two substrates without either the TiRuN film 12 or the TiNiN film. The ZrO2 film was deposited on the two substrates with thicknesses of 4 nm and 6 nm, respectively. The thicknesses of the TiN films 11 and 14 were 15 nm, and the thickness of the Al film was 40 nm. A voltage of 1 V was applied between the Al films on each substrate W formed as described above, 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 or the TiNiN film will be referred to as the TiRuN capacitor, the TiNiN capacitor, and the TiN capacitor, respectively.

[0071] Figure 13 is a graph showing the performance of each capacitor equipped with a TiN-containing film and a ZrO2 film of a different thickness. In this figure, the horizontal axis represents the CET (capacitive equivalent thickness) [nm] of the SiO2 film corresponding to the capacitance of each capacitor, and the vertical axis represents the leakage current [A / cm²]. 2 The ] was taken. Then, the leakage current and CET measured for each substrate were plotted. In the graph, a straight line is drawn connecting each plot obtained from capacitors with the same structure as the ZrO2 film thickness. 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 the 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 the film constituting the lower electrode does not necessarily improve the capacitor characteristics, and 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 capacitor characteristics in this way.

[0074] Furthermore, regarding the TiRuN capacitor, the ability to measure its characteristics as shown in Figure 13 suggests that the peeling of the ZrO2 film shown in Figure 10 did not occur. Therefore, this evaluation test 6 also revealed that by keeping the Ru content in the TiRuN film 12 to 10 atomic percent or less, the peeling of the ZrO2 film due to the strong oxidation resistance unique to the TiRuN film can be suppressed. [Explanation of symbols]

[0075] W wafer 12 TiRuN film 13 Dielectric film 14 TiN film

Claims

1. A process of forming a titanium ruthenium nitride film on a substrate, in which the concentration of ruthenium contained is less than 73 atomic percent, A step of forming a dielectric film to be laminated on the titanium ruthenium nitride film, A step of forming a metal-containing film to be laminated on the dielectric film, A film deposition method comprising the following:

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 process of forming the titanium ruthenium nitride film is as follows: The method for forming a film according to claim 3, comprising the steps of sputtering a target which is an alloy of titanium and ruthenium, which is provided in a processing vessel supplied with a plasma generation gas and a gas containing nitrogen atoms, and forming a 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 titanium ruthenium nitride film deposition section deposits a titanium ruthenium nitride film with a ruthenium concentration lower than 73 atomic percent onto a substrate, A dielectric film deposition section for depositing a dielectric film to be laminated on the titanium ruthenium nitride film, A metal-containing film deposition unit for depositing a metal-containing film to be laminated on the dielectric film, A film deposition apparatus equipped with the following features.

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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