Method for forming platinum-ruthenium alloy thin films

Abstract

To provide a method for forming a platinum-ruthenium alloy thin film by which the composition of a multicomponent alloy can be precisely controlled at an atomic unit level.SOLUTION: The present invention relates to a method for forming a noble metal binary alloy thin film by atomic layer modulation (ALM). The Pt-Ru thin film according to the present invention is formed by completely mixing two elements, i.e., dimethyl (N, N-dimethyl-3-butan-1-amine-N) platinum (DDAP: C8H19NPt) as a platinum precursor and tricarbonyl (trimethylenemethane) ruthenium ([Ru (TMM) (CO) 3]) as a ruthenium precursor.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to a method for forming a noble metal alloy thin film, and more specifically, to a method for forming a platinum-ruthenium binary alloy thin film using atomic layer modulation (ALM). [Background technology]

[0002] Metals considered precious metals include gold (Au), platinum (Pt), silver (Ag), ruthenium (Ru), rhodium (Rh), iridium (Ir), and osmium (Os). These precious metals are extremely rare, but they possess high thermal and chemical stability, as well as properties such as low resistance, high corrosion resistance, and excellent catalytic activity. By using these precious metals as alloys, it is possible to adjust a wide range of physical, electrical, and chemical properties, thereby forming multifunctional materials with controlled and diverse properties. However, because precious metals are expensive and rare, it is preferable to use them under specific and controlled conditions at the atomic level.

[0003] Atomic layer deposition (ALD) is a deposition method that allows for precise thickness control in angstroms and satisfies the requirements for uniformity and coating properties of thin films with complex three-dimensional structures. In ALD, one or more reactants are sequentially injected into a reaction chamber to form a thin film, and the thin film is formed by the adsorption of each reactant. Specifically, the reactants are supplied by a pulsing method and chemically deposited onto a substrate in the chamber, and then physically bonded residual reactants are removed by a purging method. Because ALD utilizes self-limiting surface reactions, it is possible to form thin films with excellent step or garage (stepped coverage) even with nanostructures that have a high aspect ratio.

[0004] In atomic layer deposition (ADV), the method of forming an alloy thin film by sequentially implanting multiple precursors within a single cycle is called atomic layer modulation (ALM). Atomic layer modulation enables the formation of alloy thin films by predicting the size and reactivity of the vacant spaces that have not been adsorbed with the substrate after the pulsing stage of the first precursor, and adsorbing precursors with different properties. Atomic layer modulation enables the formation of multi-component thin films with a desired elemental ratio, even at the single-atom layer level, by uniformly mixing multiple precursors with different properties. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-139020 [Patent Document 2] Special Publication No. 2017-524729 [Patent Document 3] Special Publication No. 2010-525162 [Overview of the project] [Problems that the invention aims to solve]

[0006] The technical problem that this invention aims to solve is to provide a method for forming a noble metal binary alloy (platinum-ruthenium alloy thin film) that enables precise compositional control of a multi-component alloy at the atomic level. [Means for solving the problem]

[0007] To solve the above technical problems, the present invention provides a method for forming a platinum-ruthenium alloy thin film by atomic layer modulation, characterized by including the following steps. • A step of supplying a platinum precursor to the substrate in the chamber; • The step of purging the platinum precursor from the above chamber; • A step of supplying a ruthenium precursor to the substrate in the chamber; • The step of purging the ruthenium precursor from the above chamber; • The step of supplying the reaction gas to the above substrate; and • The step of purging the reaction gas from the above chamber.

[0008] In some embodiments of the present invention, the above-mentioned noble metal precursor is a platinum precursor having the structure shown in Chemical Formula 1 below (dimethyl(N,N-dimethyl-3-butane-1-amine-N)platinum(DDAP:C8H 19 The reaction gas is NPt)) and a ruthenium precursor having the structure shown in Chemical Formula 2 below (tricarbonyl(trimethylenemethane)ruthenium([Ru(TMM)(CO)3])), and the reaction gas may be oxygen.

[0009] [ka]

[0010] [ka]

[0011] In some embodiments of the present invention, the above steps may be carried out at a temperature in the range of 200°C to 300°C (preferably 200°C to 250°C). Furthermore, in some embodiments of the present invention, the thin film of the noble metal alloy can be formed at a pressure of 1 torr or less.

[0012] In some embodiments of the present invention, the impurity content of the noble metal alloy may be 1 atomic percent or less.

[0013] In some embodiments of the present invention, when the above steps are performed sequentially once each, one deposition cycle is defined as the deposition rate of the noble metal alloy thin film can be in the range of 1 Å / cycle to 2 Å / cycle.

[0014] In some embodiments of the present invention, the pulsing order of the precursor can be changed.

[0015] In some embodiments of the present invention, the temperature of the precursor can be changed.

[0016] In some embodiments of the present invention, the precursor can be supplied for 1 to 15 seconds, and the reaction gas can be supplied for 10 to 15 seconds.

[0017] One embodiment of the present invention provides a noble metal alloy thin film. This noble metal alloy thin film is formed using the method for forming the noble metal alloy thin film.

Advantages of the Invention

[0018] According to the atomic layer modulation (ALM) using the platinum precursor and ruthenium precursor of the present invention, a platinum-ruthenium alloy thin film with precise thickness control at the atomic unit level can be formed.

Brief Description of the Drawings

[0019] [Figure 1] Gas injection flow diagram of the atomic layer deposition method for explaining the method of forming platinum and ruthenium thin films. [Figure 2] Graph showing the change in the film thickness of the platinum thin film according to the supply time of the platinum precursor in Fig. 1. [Figure 3] Graph showing the change in the film thickness of the ruthenium thin film according to the supply time of the ruthenium precursor in Fig. 2. [Figure 4] Gas injection flow diagram of atomic layer modulation for explaining the first embodiment of forming a platinum-ruthenium alloy thin film using the platinum precursor of Fig. 1, the ruthenium precursor of Fig. 2, and oxygen gas. [Figure 5] Graph showing the results of X-ray diffraction analysis (XRD) of the platinum-ruthenium alloy thin film formed according to the first embodiment. [Figure 6] Graph showing the calculation results of the composition of the platinum-ruthenium alloy thin film formed according to the first embodiment. [Figure 7] Graph showing the results of time-of-flight elastic recoil detection (TOF-ERD) and Rutherford backscattering spectroscopy (RBS) of the platinum-ruthenium alloy thin film formed according to the first embodiment. [Figure 8] A graph showing the calculated composition of the platinum-ruthenium alloy thin film formed according to the first embodiment. [Figure 9] This graph shows the change in the thickness of the platinum thin film in the platinum precursor shown in Chemical Formula 1, depending on the temperature. [Figure 10] A gas injection flow diagram of atomic layer modulation illustrating a method for forming a platinum-ruthenium alloy thin film in a second embodiment. [Figure 11] A graph showing the results of X-ray diffraction analysis (XRD) of a platinum-ruthenium alloy thin film formed according to the second embodiment. [Figure 12] A graph showing the calculated composition of the platinum-ruthenium alloy thin film formed according to the second embodiment. [Figure 13] A graph showing the change in film thickness of a platinum-ruthenium alloy thin film formed according to the second embodiment. [Figure 14] A graph showing the results of energy-dispersive spectroscopy (TEM-EDS) analysis using a transmission electron microscope, indicating the composition of the platinum-ruthenium alloy thin film formed according to the second embodiment.

[0020] First Embodiment : Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments of the present invention can be modified into various different forms, and various embodiments can be combined. The scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to give a more complete explanation of the invention to those who are ordinaryly skilled in the art. Accordingly, embodiments of the present invention are not limited to the drawings presented herein and are not restricted by the relative sizes or spacing shown in the accompanying drawings.

[0021] In this embodiment, dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP:C8H) is a platinum precursor having the structure of Chemical Formula 1 described above. 19A platinum-ruthenium binary alloy thin film is formed by atomic layer modulation using NPt) and tricarbonyl(trimethylenemethane)ruthenium ([Ru(TMM)(CO)3]), a ruthenium precursor having the structure of the above-described chemical formula 2, and oxygen as the reaction gas.

[0022] Figure 1 is a gas injection flow diagram for atomic layer deposition illustrating a method for forming a platinum thin film using the platinum precursor and oxygen reaction gas shown in Chemical Formula 1. Referring to Figure 1, the method for forming a platinum thin film includes the steps of supplying the platinum precursor, purging the platinum precursor, supplying the reaction gas, and purging the reaction gas. Each of these steps can be performed on the object to be deposited, such as a substrate, within the chamber of the atomic layer deposition apparatus. Each of these steps is performed sequentially once to form one deposition cycle. The above deposition cycle can be repeated multiple times depending on the desired film thickness.

[0023] As shown in Figure 1, the method for forming a platinum thin film may first involve supplying a platinum precursor. This step involves injecting the platinum precursor into the chamber as a platinum source gas. Before supplying the platinum precursor onto the substrate, the temperature of the substrate in the chamber may be, for example, between 220°C and 250°C.

[0024] At this stage, as a platinum precursor, dimethyl(N,N-dimethyl-3-butane-1-amine-N)platinum (DDAP:C8H) is used as shown in Chemical Formula 1. 19 NPt can be used. If the platinum precursor is a gas, it can be supplied as a precursor. If the platinum precursor is a solid or liquid, an inert gas can be used as a carrier gas to supply it to the substrate in the chamber. The substrate may contain conductive material, semiconductor material, or insulating material on its upper surface.

[0025] Next, a step of purging the platinum precursor may be performed. Argon (Ar), nitrogen (N2), helium (He) gas, etc., can be used as the purging gas. The purging gas can remove any remaining by-products and unadsorbed platinum precursor.

[0026] Next, a step of injecting a reaction gas may be performed. The reaction gas is a reducing gas that reduces the platinum precursor adsorbed on the substrate to assist in nucleation, and oxygen can be used as the reaction gas.

[0027] Next, the reaction gas is purged. Argon (Ar), nitrogen (N2), helium (He) gas, etc., can be used as the purging gas.

[0028] Furthermore, the method for forming a ruthenium thin film using a ruthenium precursor having the structure of formula 2 (tricarbonyl(trimethylenemethane)ruthenium: [Ru(TMM)(CO)3]) and an oxygen reaction gas is the same as the method for forming a platinum thin film described above.

[0029] The steps of supplying the precursor, purging the precursor, supplying the reaction gas, and purging the reaction gas may be performed for 1st, 2nd, 3rd, and 4th hours, respectively. Each time may be the same or different from each other. For example, the 2nd and 4th hours may be the same, and may be different from the 1st and / or 3rd hours.

[0030] Figure 2 is a graph showing the thickness of a platinum thin film according to the supply time of the platinum precursor in a method for forming a platinum thin film. Referring to Figure 2, the first supply time of the platinum precursor is 1 to 15 seconds. The third supply time of the reaction gas was 10 seconds during deposition. The platinum thin film was deposited on a silicon oxide substrate (SiO2) at 225°C.

[0031] As shown in Figure 2, it can be seen that the thickness of the platinum thin film increases in proportion to the first time during the stage of supplying the platinum precursor. In the case of the platinum precursor, it can be seen that the film thickness reaches a saturation point in about 10 seconds or more.

[0032] Figure 3 is a graph showing the thickness of a ruthenium thin film according to the supply time of the ruthenium precursor in a method for forming a ruthenium thin film. Referring to Figure 3, the first supply time of the ruthenium precursor is 1 to 10 seconds. The third supply time of the reaction gas was set to 10 seconds during deposition. The ruthenium thin film was deposited on a silicon oxide substrate (SiO2) at 225°C.

[0033] As shown in Figure 3, it can be seen that the thickness of the ruthenium thin film increases with time during the stage of supplying the ruthenium precursor. In the case of the ruthenium precursor, it can be seen that the film thickness reaches a saturation state in about 3 seconds or more.

[0034] First Embodiment Figure 4 shows a gas injection flow diagram for atomic layer modulation to illustrate the method of forming a platinum-ruthenium alloy thin film using the platinum precursor in Chemical Formula 1, the ruthenium precursor in Chemical Formula 2, and the oxygen reaction gas.

[0035] Referring to Figure 4, the method for forming a platinum-ruthenium alloy thin film includes the steps of supplying a platinum precursor, purging the platinum precursor, supplying a ruthenium precursor, purging the ruthenium precursor, supplying a reaction gas, and purging the reaction gas. Each of these steps can be performed on an object to be deposited, such as a substrate, within the chamber of an atomic layer deposition apparatus. Each of these steps is performed sequentially once to constitute one deposition cycle. The deposition cycle can be repeated multiple times depending on the desired thickness of the thin film.

[0036] As shown in Figure 4, the method for forming a platinum-ruthenium alloy thin film may first involve supplying a platinum precursor. This step involves injecting the platinum precursor into the chamber as a platinum source gas. Before supplying the platinum precursor onto the substrate, the temperature of the substrate in the chamber may be set to, for example, 220°C to 250°C.

[0037] At this stage, as a platinum precursor, dimethyl(N,N-dimethyl-3-butane-1-amine-N)platinum (DDAP:C8H) is used as shown in Chemical Formula 1. 19 NPt can be used. If the platinum precursor is a gas, it can be supplied as a precursor. If the platinum precursor is a solid or liquid, it can be supplied to the substrate in the chamber using an inert gas as a carrier gas. The substrate may contain conductive material, semiconductor material, or insulating material on its upper surface.

[0038] Next, a step of purging the platinum precursor can be performed. Argon (Ar), nitrogen (N2), helium (He) gas, etc., can be used as the purging gas. The purging gas can remove any remaining by-products and unadsorbed platinum precursor.

[0039] Next, tricarbonyl(trimethylenemethane)ruthenium ([Ru(TMM)(CO)3]) from formula 2 can be used as the ruthenium precursor. If the above precursor is a gas, it can be supplied as is. If the ruthenium precursor is a solid or liquid, it can be supplied to the substrate in the chamber using an inert gas as a carrier gas.

[0040] Next, a step of purging the ruthenium precursor may be performed. Argon (Ar), nitrogen (N2), helium (He) gas, etc., can be used as the purging gas. The purging gas can remove any remaining by-products and ruthenium precursor that has not been adsorbed.

[0041] Next, a reaction gas is injected. The reaction gas is a reducing gas that assists in nucleation by reducing the platinum and ruthenium precursors adsorbed on the substrate, and oxygen can also be used as the reaction gas.

[0042] Next, the reaction gases are purged. Argon (Ar), nitrogen (N2), helium (He) gas, etc., can be used as the purging gas.

[0043] The steps of supplying the platinum precursor, purging the platinum precursor, supplying the ruthenium precursor, purging the ruthenium precursor, supplying the reaction gas, and purging the reaction gas may be performed for the first, second, third, fourth, fifth, and sixth hours, respectively. These times may be the same or different from each other. For example, the second, fourth, and sixth hours may be the same, and may be different from the first and / or third and / or fifth hours.

[0044] Figure 5 is a graph showing the results of analysis of the crystal structure of a platinum-ruthenium alloy thin film according to the supply time of the platinum precursor in the method for forming a platinum-ruthenium alloy thin film according to the first embodiment.

[0045] Referring to Figure 5, the results of X-ray diffraction analysis of the crystal structure of platinum-ruthenium alloy thin films are shown according to the supply time of the platinum precursor. The thin films in Figure 5, excluding the PtRu1 thin film, have a face-centered cubic (fcc) structure of platinum. Therefore, it can be seen that the peaks of the (111), (200), (220), and (311) crystal planes, which correspond to this structure, are dominant. Furthermore, it can be seen that as the supply time of platinum increases, the (001) peak of Ru shifts to the (002) peak of Pt.

[0046] Figure 6 is a graph showing the analysis results of the density, thickness, and surface roughness of the platinum-ruthenium alloy thin film according to the first embodiment of the method for forming a platinum-ruthenium alloy thin film, depending on the supply time of the platinum precursor.

[0047] Referring to Figure 6, the density of the platinum thin film is 20.77 g / cm³. 3 The roughness is 1.3 nm and the thickness is 24.6 nm. The density of the ruthenium thin film is 12.36 g / cm³. 3 The roughness is 2.4 nm and the thickness is 27.4 nm. The density of the platinum-ruthenium alloy thin film formed according to the first embodiment increases with increasing platinum supply time, ranging from 17.54 to 20.83 g / cm³. 3It falls within this range. It can be seen that all thin films formed except for the thin film with a platinum supply time of 1 second (PtRu1) have a density similar to that of platinum.

[0048] Figure 7 shows the results of compositional analysis for platinum-ruthenium alloy thin films (PtRu2, PtRu5) formed according to the first embodiment, where the platinum precursor supply time was 3 seconds and 10 seconds, respectively. The composition of the thin films was determined by RBS and TOF-ERD analysis.

[0049] As can be seen from Figure 7, ruthenium and platinum are contained together in the thin film, and the amount of platinum in the thin film increases with increasing supply time of the platinum precursor. Furthermore, the PtRu2 thin film in which the platinum precursor was injected for 3 seconds contains only trace amounts of carbon (0.015 atomic%) and oxygen (0.15 atomic%), which are less than 1 atomic percent. Therefore, it can be seen that a platinum-ruthenium alloy thin film with almost no impurities was formed in this embodiment. The PtRu5 thin film in which the platinum precursor was injected for 10 seconds contains only trace amounts of carbon (0.012 atomic%) and oxygen (0.188 atomic%), which are less than 1 atomic percent, indicating that a platinum-ruthenium alloy thin film with almost no impurities was formed.

[0050] Figure 8 shows the calculated platinum and ruthenium composition ratios of platinum-ruthenium alloy thin films according to the first embodiment. For the alloy thin films that underwent RBS analysis (PtRu2, PtRu5), the composition ratios were calculated using the atomic ratios of platinum and ruthenium obtained from the RBS analysis described above. For the alloy thin films PtRu1, PtRu3, PtRu4, and PtRu6 that were not subjected to RBS analysis, the platinum and ruthenium composition ratios were calculated using the densities shown in Figure 7. It can be seen that the composition ratios calculated using the atomic ratios from the RBS analysis and the composition of the thin films calculated using the densities shown in Figure 7 are very similar.

[0051] As shown in Figure 8, in the platinum-ruthenium alloy thin film according to the first embodiment, the Pt:Ru composition ratio is adjusted to be within the range of 62:38 to 97:3.

[0052] Second Embodiment Figure 9 shows the film thickness of platinum thin films deposited while varying the deposition temperature of the platinum precursor and keeping the platinum precursor injection time the same. Note that in the figure, X°C > Y°C.

[0053] As shown in Figure 9, it can be seen that as the deposition temperature of the platinum precursor decreases (X > Y), the growth rate of the platinum thin film decreases for the same supply time of platinum precursor.

[0054] Figure 10 is a gas injection flow diagram for atomic layer modulation illustrating the method for forming a platinum-ruthenium alloy thin film according to the second embodiment. The method for forming a platinum-ruthenium alloy thin film according to the second embodiment differs from the method for forming a platinum-ruthenium alloy thin film according to the first embodiment in that the temperature of the platinum precursor is set differently, while all other methods are the same.

[0055] Figure 11 is a graph showing the results of XRD analysis of the crystal structure of platinum-ruthenium alloy thin films according to the second embodiment of the method for forming platinum-ruthenium alloy thin films, depending on the supply time of the platinum precursor. In Figure 11, the first supply time of the platinum precursor is set to 1 second, 5 seconds, 10 seconds, 15 seconds, and 20 seconds, and the alloy thin films for each time are shown as PtRu7, PtRu8, PtRu9, PtRu10, and PtRu11.

[0056] Referring to Figure 11, the results of XRD analysis of the crystal structure of platinum-ruthenium alloy thin films are shown according to the supply time of the platinum precursor. The alloy thin films, excluding the PtRu7 thin film, have a platinum fcc structure. Therefore, it can be seen that the diffraction peaks of the corresponding crystal planes, (111), (200), (220), and (311), are dominant. Furthermore, it can be seen that as the supply time of platinum increases, the ruthenium (001) peak shifts towards the platinum (002) peak.

[0057] FIG. 12 is a graph showing the analysis results of the density, thickness, and surface roughness of a platinum-ruthenium alloy thin film according to the formation method of the platinum-ruthenium alloy thin film in the second embodiment, with respect to the supply time of the platinum precursor.

[0058] Referring to FIG. 12, the density of the platinum thin film is 20.55 g / cm 3 with a roughness of 1.26 nm and a thickness of 22.2 nm. The density of the ruthenium thin film is 12.36 g / cm 3 with a roughness of 2.4 nm and a thickness of 27.4 nm. The density of the platinum-ruthenium alloy thin film formed according to the second embodiment increases as the supply time of platinum increases, and has a range of 14.08 - 20.55 g / cm 3 It can be seen that alloy thin films other than the thin film (PtRu7) with a platinum supply time of 1 second are similar to the density of platinum.

[0059] FIG. 13 is a graph showing the composition ratio of the platinum-ruthenium alloy thin film according to the temperature of the platinum precursor. It can be seen that the amount of platinum in the alloy thin film decreases as the temperature of the platinum precursor decreases, and it can be said that an alloy thin film capable of adjusting the composition of alloy elements according to the temperature of the precursor can be obtained.

[0060] And referring to the analysis results of energy dispersive spectroscopy (TEM-EDS) by the transmission electron microscope in FIG. 14, it can be seen that the platinum-ruthenium alloy thin film deposited by the method presented in the present invention has a uniform composition.

Industrial Applicability

[0061] As described above, according to the atomic layer modulation (ALM) according to the present invention, by appropriately using a platinum precursor and a ruthenium precursor, a platinum-ruthenium alloy thin film with precise thickness control and composition control at the atomic unit level can be formed. The present invention is suitable for forming metal wirings of various semiconductor devices, and in particular, can also cope with the miniaturization of wirings of semiconductor devices that are miniaturized.

Claims

1. A method for forming a platinum-ruthenium alloy thin film by atomic layer modulation, wherein the following steps are performed sequentially to form one cycle, A step of supplying a platinum precursor to the substrate in the chamber; The step of purging the platinum precursor from the above chamber; The step of supplying a ruthenium precursor to the substrate in the chamber; The step of purging the ruthenium precursor from the above chamber; A step of supplying a reaction gas to the platinum precursor and the ruthenium precursor adsorbed on the above substrate; and The step of purging the reaction gas from the above chamber; A method for forming a platinum-ruthenium alloy thin film, characterized in that a platinum precursor having the structure shown in Chemical Formula 1 below is used as the platinum precursor. 【Chemistry 1】

2. As the ruthenium precursor, a ruthenium precursor having the structure shown in Chemical Formula 2 below is used. A method for forming a platinum-ruthenium alloy thin film according to claim 1, characterized in that a platinum-ruthenium alloy thin film is formed by atomic layer modulation. 【Chemistry 2】

3. A method for forming a platinum-ruthenium alloy thin film according to claim 1 or claim 2, wherein the reaction gas is oxygen.

4. A method for forming a platinum-ruthenium alloy thin film according to claim 1 or claim 2, wherein the platinum-ruthenium alloy thin film is formed at a temperature of 200°C to 300°C.

5. A method for forming a platinum-ruthenium alloy thin film according to claim 1 or claim 2, wherein a platinum-ruthenium alloy thin film is formed on a substrate by repeating a cycle consisting of each stage.

6. A method for forming a platinum-ruthenium alloy thin film according to claim 1 or claim 2, comprising supplying a platinum precursor and / or a ruthenium precursor for 1 to 15 seconds and supplying a reaction gas for 10 to 15 seconds.

Images