Method for forming platinum-ruthenium alloy thin film

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] The present invention relates to a method for forming a precious metal alloy thin film, and more particularly to a method for forming a platinum-ruthenium binary alloy thin film using atomic layer modulation (ALM). [Background technology]

[0002] Metals considered to be noble include gold (Au), platinum (Pt), silver (Ag), ruthenium (Ru), rhodium (Rh), iridium (Ir), and osmium (Os). Although these noble metals are extremely rare, they possess high thermal and chemical stability, as well as properties such as low electrical resistance, high corrosion resistance, and excellent catalytic activity. By using these noble metals as alloys, it is possible to tailor various physical, electrical, and chemical properties, forming multifunctional materials with controlled properties. However, due to their high cost and rarity, it is preferable to use noble metals in a way that allows them to be specified and controlled at the atomic level.

[0003] Atomic layer deposition (ALD) is a deposition method that allows precise thickness control down to the angstrom level and achieves thin film uniformity and coatability for complex three-dimensional structures. ALD involves sequentially injecting one or more reactants into a reaction chamber to form a thin film through the adsorption of each reactant. The reactants are supplied in a pulsing manner to chemically deposit on the substrate in the chamber, and then any remaining reactants that are physically bound are removed using a purging method. Because ALD utilizes self-limiting surface reactions, it is possible to form thin films with excellent step coverage even on nanostructures with high aspect ratios.

[0004] Atomic Layer Modulation (ALM) is a method of forming alloy thin films by sequentially injecting multiple precursors within a single cycle in atomic layer deposition. Atomic Layer Modulation predicts the size and reactivity of the vacant spaces that remain unadsorbed on the substrate after the initial precursor pulsing step, allowing precursors with different properties to be adsorbed, thereby enabling the formation of alloy thin films. Atomic Layer Modulation allows multiple precursors with different properties to be uniformly mixed, even at the monoatomic layer level, making it possible to form multi-component thin films with the desired elemental ratios. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-139020 [Patent Document 2] Special Publication No. 2017-524729 [Patent Document 3] Special Publication No. 2010-525162 Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a method for forming a binary precious metal alloy (platinum-ruthenium alloy thin film) that allows precise composition control of the multi-component alloy at the atomic level. [Means for solving the problem]

[0007] In order to solve the above technical problems, the method for forming a platinum-ruthenium alloy thin film according to the present invention is a method for forming a platinum-ruthenium alloy thin film by atomic layer modulation, which comprises the following steps: providing a platinum precursor to the substrate in the chamber; purging the platinum precursor from the chamber; providing a ruthenium precursor to the substrate in the chamber; purging the ruthenium precursor from the chamber; supplying a reactive gas to the substrate; and purging the reaction gas from the chamber.

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

[0009] [ka]

[0010] [ka]

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

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

[0013] In some embodiments of the present invention, when the above steps are performed one by one in sequence to form one deposition cycle, the deposition rate of the noble metal alloy thin film may be in the range of 1 Å / cycle to 2 Å / cycle.

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

[0015] In some embodiments of the present invention, the temperature of the precursor may be varied.

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

[0017] One embodiment of the present invention provides a noble metal alloy thin film, which is formed using the method for forming a noble metal alloy thin film described above. [Effects of the Invention]

[0018] According to the atomic layer modulation (ALM) using the platinum precursor and the ruthenium precursor of the present invention, it is possible to form a platinum-ruthenium alloy thin film whose thickness is precisely controlled at the atomic level. [Brief explanation of the drawings]

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

[0020] First embodiment : Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention may be modified into various different forms, and various embodiments may be combined. The scope of the present invention is not limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art. Therefore, the embodiments of the present invention are not limited to the drawings presented in this specification, and are not limited by the relative sizes and spacings shown in the accompanying drawings.

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

[0022] FIG. 1 is a gas injection flow diagram of an atomic layer deposition method for explaining a method for forming a platinum thin film using a platinum precursor of Chemical Formula 1 and an oxygen reactant gas. Referring to FIG. 1, the method for forming a platinum thin film includes a step of supplying a platinum precursor, a step of purging the platinum precursor, a step of supplying a reactant gas, and a step of purging the reactant gas. Each of these steps can be performed on a deposition target, e.g., a substrate, in a chamber of an atomic layer deposition apparatus. Each of these steps can be performed sequentially once to form one deposition cycle. The deposition cycle can be repeated multiple times depending on the desired film thickness.

[0023] 1, a method for forming a platinum thin film may first include supplying a platinum precursor. The platinum precursor is injected into a chamber as a platinum source gas. At this time, the temperature of the substrate in the chamber may be, for example, 220° C. to 250° C. before supplying the platinum precursor onto the substrate.

[0024] At this stage, the platinum precursor was dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP: CH 19 NPt) can be used. When the platinum precursor is gaseous, it can be supplied as is. When the platinum precursor is solid or liquid, it can be supplied to the substrate in the chamber using an inert gas as a carrier gas. The substrate can include a conductive material, a semiconductive material, or an insulating material on its upper surface.

[0025] Next, a step of purging the platinum precursor may be performed. Examples of purge gases that can be used include argon (Ar), nitrogen (N), and helium (He) gas. The purge gas can remove remaining by-products and unadsorbed platinum precursor.

[0026] Next, a step of injecting a reactive gas may be performed, where the reactive gas is a reducing gas that reduces the platinum precursor adsorbed on the substrate to assist nucleation, and the reactive gas may be oxygen.

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

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

[0029] The steps of supplying the precursor, purging the precursor, supplying the reactant gas, and purging the reactant gas may be performed for a first, second, third, and fourth time, respectively. Each time may be the same or different from each other. For example, the second and fourth times may be the same, which may be different from the first and / or third times.

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

[0031] As shown in Figure 2, in the step of supplying the platinum precursor, the thickness of the platinum thin film increases with time. In the case of the platinum precursor, the thickness reaches a saturated state after about 10 seconds or more.

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

[0033] As shown in Figure 3, in the step of supplying the ruthenium precursor, the thickness of the ruthenium thin film increases with time. In the case of the ruthenium precursor, the film thickness reaches a saturated state after about 3 seconds or more.

[0034] First embodiment FIG. 4 is a gas injection flow diagram for atomic layer modulation to explain a method for forming a platinum-ruthenium alloy thin film using a platinum precursor of Chemical Formula 1, a ruthenium precursor of Chemical Formula 2, and an oxygen reactant gas.

[0035] Referring to FIG. 4, a method for forming a platinum-ruthenium alloy thin film includes 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 may be performed on a deposition target, e.g., a substrate, in a chamber of an atomic layer deposition apparatus. Each of these steps may be performed sequentially once to form one deposition cycle. The deposition cycle may be repeated multiple times depending on the desired film thickness.

[0036] 4, the method for forming a platinum-ruthenium alloy thin film may first include a step of supplying a platinum precursor. The step of supplying the platinum precursor is a step of injecting the platinum precursor into a chamber as a platinum source gas. At this time, before supplying the platinum precursor onto the substrate, the temperature of the substrate in the chamber may be, for example, 220°C or higher and 250°C or lower.

[0037] At this stage, the platinum precursor was dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP: CH 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 can include a conductive material, a semiconductive material, or an insulating material on its upper surface.

[0038] Next, a step of purging the platinum precursor may be performed. The purge gas may be argon (Ar), nitrogen (N), helium (He), etc. The purge gas may remove remaining by-products and unadsorbed platinum precursor.

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

[0040] Next, the ruthenium precursor may be purged using a purge gas such as argon (Ar), nitrogen (N), or helium (He). The purge gas may remove any remaining by-products and unadsorbed ruthenium precursor.

[0041] Next, a step of injecting a reactive gas is performed, which is a reducing gas that reduces the platinum and ruthenium precursors adsorbed on the substrate to assist nucleation, and the reactive gas may be oxygen.

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

[0043] 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 may be performed for a first, second, third, fourth, fifth, and sixth time, respectively. These times may be the same or different from one another. For example, the second, fourth, and sixth times may be the same, but may be different from the first, third, and / or fifth times.

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

[0045] Figure 5 shows the results of X-ray diffraction analysis of the crystalline structure of platinum-ruthenium alloy thin films as a function of the platinum precursor supply time. All thin films except the PtRu thin film in Figure 5 have a platinum face-centered cubic (fcc) structure. Therefore, peaks from the corresponding crystal planes (111), (200), (220), and (311) are dominant. It can also be seen that as the platinum supply time increases, the Ru (001) peak shifts toward the Pt (002) peak.

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

[0047] Referring to Figure 6, the density of the platinum thin film is 20.77 g / cm 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 / cm 3 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 / cm. 3It can be seen that all the thin films formed except for the thin film (PtRu1) with a platinum supply time of 1 second have densities similar to that of platinum.

[0048] 7 shows the results of analyzing the compositions of the platinum-ruthenium alloy thin films (PtRu2 and PtRu5) formed by the first embodiment, in which the platinum precursor was supplied for 3 seconds and 10 seconds, respectively. The compositions of the thin films were analyzed by RBS and TOF-ERD.

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

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

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

[0052] Second embodiment Figure 9 shows the thickness of platinum thin films deposited by changing the platinum precursor deposition temperature while keeping the platinum precursor injection time constant. Note that X°C and Y°C in the figure are such that X>Y.

[0053] As shown in FIG. 9, as the film formation temperature of the platinum precursor decreases (X>Y), the growth rate of the platinum thin film decreases for the same platinum precursor supply time.

[0054] 10 is a gas injection flow diagram for atomic layer modulation to explain 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 is the same as the method for forming a platinum-ruthenium alloy thin film according to the first embodiment, except that the temperature of the platinum precursor is set differently.

[0055] 11 is a graph showing the results of XRD analysis of the crystal structure of a platinum-ruthenium alloy thin film as a function of the platinum precursor supply time in the method for forming a platinum-ruthenium alloy thin film according to the second embodiment. In FIG. 11, the first time, which is the platinum precursor supply time, is 1 second, 5 seconds, 10 seconds, 15 seconds, and 20 seconds, and the alloy thin films obtained at each time are indicated as PtRu7, PtRu8, PtRu9, PtRu10, and PtRu11.

[0056] Figure 11 shows the results of XRD analysis of the crystalline structure of platinum-ruthenium alloy thin films as a function of the platinum precursor supply time. All alloy thin films, except for the PtRu7 thin film, have the fcc structure of platinum. Therefore, it can be seen that the diffraction peaks of the corresponding crystal planes (111), (200), (220), and (311) planes are dominant. It can also be seen that as the platinum supply time increases, the ruthenium (001) peak shifts toward the platinum (002) peak.

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

[0058] Referring to FIG. 12, the density of the platinum thin film is 20.55 g / cm 3 The roughness is 1.26 nm and the thickness is 22.2 nm. The density of the ruthenium thin film is 12.36 g / cm 3 The density of the platinum-ruthenium alloy thin film formed by the second embodiment increases with increasing platinum supply time, ranging from 14.08 to 20.55 g / cm. 3 It can be seen that the densities of the alloy thin films, except for the thin film (PtRu7) in which the platinum supply time was 1 second, are similar to that of platinum.

[0059] 13 is a graph showing the composition ratio of a platinum-ruthenium alloy thin film as a function of 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, indicating that it is possible to obtain an alloy thin film in which the composition of alloying elements can be adjusted depending on the temperature of the precursor.

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

[0061] As described above, the atomic layer modulation (ALM) according to the present invention makes it possible to form a platinum-ruthenium alloy thin film whose thickness and composition can be precisely controlled at the atomic level by appropriately using a platinum precursor and a ruthenium precursor. The present invention is suitable for forming metal wiring for various semiconductor devices, and is particularly applicable to miniaturization of wiring in ultra-miniaturized semiconductor devices.

Claims

1. providing a platinum precursor to a substrate in a chamber; purging the platinum precursor from the chamber; providing a ruthenium precursor to a substrate in a chamber; purging the ruthenium precursor from the chamber; supplying a reactive gas to the substrate; and purging the reaction gas from the chamber.

2. A platinum precursor having the structure of the following chemical formula 1 and a ruthenium precursor having the structure of the following chemical formula 2 are used, 2. The method for forming a platinum-ruthenium alloy thin film according to claim 1, wherein the platinum-ruthenium alloy thin film is formed by atomic layer modulation. 【Chemistry 1】 【Chemistry 2】

3. 3. The method for forming a platinum-ruthenium alloy thin film according to claim 1, wherein the reactive gas is oxygen.

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

5. 3. The method for forming a platinum-ruthenium alloy thin film according to claim 1, wherein the platinum-ruthenium alloy thin film is formed on the substrate by repeating a cycle consisting of each step.

6. 3. The method for forming a platinum-ruthenium alloy thin film according to claim 1, wherein the platinum precursor and / or the ruthenium precursor is supplied for 1 to 15 seconds, and the reaction gas is supplied for 10 to 15 seconds.

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