Method for forming platinum-ruthenium alloy thin film

Abstract

The present invention relates to a method for forming a noble metal binary alloy thin film by atomic layer modulation (ALM). For the platinum-ruthenium alloy thin film according to the present invention, an alloy thin film is provided in which two elements are completely mixed by using dimethyl (N,N-dimethyl-3-butan-1-amine-N) platinum (DDAP: C8H19NPt) as a platinum precursor, tricarbonyl (trimethylene methane) ruthenium ([Ru(TMM) (CO)3]) as a ruthenium precursor, and oxygen as a reaction gas. The present invention makes it possible to form a platinum-ruthenium alloy thin film in which precise compositional control is achieved at the atomic level.

Description

Method for forming platinum-ruthenium alloy thin film

[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).

[0002] Metals considered to be noble metals include gold (Au), platinum (Pt), silver (Ag), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and the like. Although these noble metals are extremely rare, they possess high thermal and chemical stability, as well as properties such as low resistance, high corrosion resistance, and excellent catalytic activity. By using noble metals with such properties as alloys, it is possible to adjust various physical, electrical, and chemical properties, resulting in the formation of multifunctional materials with diverse controlled properties. However, due to the high cost and rarity of noble metals, it is preferable to use them while identifying and controlling them 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 a self-limiting surface reaction, 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. ALM enables the formation of alloy thin films by predicting the size and reactivity of vacant spaces remaining after the initial precursor pulsing step and adsorbing precursors with different properties. Atomic layer modulation allows multiple precursors with different properties to be uniformly mixed, even at monoatomic layer thicknesses, to form multi-component thin films with desired elemental ratios.

[0005] Japanese Patent Application Laid-Open No. 2023-139020 Special Publication No. 2017-524729 Special Publication No. 2010-525162

[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.

[0007] In order to solve the above technical problems, the present invention provides a method for forming a platinum-ruthenium alloy thin film by atomic layer modulation, comprising the following steps: supplying a platinum precursor to a substrate in a chamber; purging the platinum precursor from the chamber; supplying 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 reactive 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:C)) having the following structure: ８ H １９ NPt) and a ruthenium precursor (tricarbonyl(trimethylenemethane)ruthenium ([Ru(TMM)(CO) ３ ])) and the reactive gas may be oxygen.

[0009]

[0010]

[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 thin film of the noble metal alloy 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 range from 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.

[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.

[0019] 1 is a gas injection flow diagram of an atomic layer deposition method for explaining a method for forming platinum and ruthenium thin films. 2 is a graph showing the change in film thickness of a platinum thin film depending on the supply time of a platinum precursor of Chemical Formula 1. 3 is a graph showing the change in film thickness of a ruthenium thin film depending on the supply time of a ruthenium precursor of Chemical Formula 2. 4 is a gas injection flow diagram of atomic layer modulation for explaining a first embodiment for forming a platinum-ruthenium alloy thin film using a platinum precursor of Chemical Formula 1, a ruthenium precursor of Chemical Formula 2, and oxygen gas. 5 is a graph showing the results of X-ray diffraction analysis (XRD) of a platinum-ruthenium alloy thin film formed by the first embodiment. 6 is a graph showing the results of calculations of the composition of a platinum-ruthenium alloy thin film formed by the first embodiment. 7 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 by the first embodiment. 8 is a graph showing the results of calculations of the composition of a platinum-ruthenium alloy thin film formed by the first embodiment. 9 is a graph showing the change in film thickness of a platinum thin film depending on the temperature of the platinum precursor of Chemical Formula 1. A gas injection flow diagram for atomic layer modulation to explain a method for forming a platinum-ruthenium alloy thin film in the second embodiment. A graph showing the results of X-ray diffraction analysis (XRD) of a platinum-ruthenium alloy thin film formed by the second embodiment. A graph showing the results of calculation of the configuration of a platinum-ruthenium alloy thin film formed by the second embodiment. A graph showing the change in film thickness of a platinum-ruthenium alloy thin film formed by the second embodiment. 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 by 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, dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP:C), which is a platinum precursor having the structure of Chemical Formula 1 described above, is used. ８ H １９ NPt) and tricarbonyl(trimethylenemethane)ruthenium ([Ru(TMM)(CO) ３ ]) and oxygen as a reactive gas to form a platinum-ruthenium binary alloy thin film by atomic layer modulation.

[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, dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP:C) of formula 1 was used as the platinum precursor. ８ H 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 may include a conductive material, a semiconductive material, or an insulating material on its upper surface.

[0025] Next, a step of purging the platinum precursor can be performed. The purge gas can be argon (Ar), nitrogen (N ２ ), helium (He) gas, etc. 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 (N ２ ), helium (He) gas, etc. can be used.

[0028] Also, a ruthenium precursor having the structure of Chemical Formula 2 (tricarbonyl(trimethylenemethane)ruthenium: [Ru(TMM)(CO) ３ The method for forming a ruthenium thin film using ruthenium as a reactive 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 reactant gas, and purging the reactant gas may be performed for a first time, a second time, a third time, and a fourth time, respectively. Each time may be the same or different from each other. For example, the second time and the fourth time may be the same, which may be different from the first time and / or the third time.

[0030] FIG. 2 is a graph showing the thickness of a platinum thin film depending on the platinum precursor supply time in the platinum thin film formation method. Referring to FIG. 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, is 10 seconds. The platinum thin film was deposited on a silicon oxide substrate (SiO ２ ) was held.

[0031] 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] FIG. 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 FIG. 3, the first time, which is the supply time of the ruthenium precursor, is 1 to 10 seconds. The third time, which is the supply time of the reaction gas, is 10 seconds. The deposition was performed under the condition that the ruthenium thin film was deposited on a silicon oxide substrate (SiO ２ ) was held.

[0033] 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 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] 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, dimethyl(N,N-dimethyl-3-butan-1-amine-N)platinum (DDAP:C) of formula 1 was used as the platinum precursor. ８ H １９NPt) can be used. When the platinum precursor is a gas, it can be supplied as a precursor. When 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 can be performed. The purge gas can be argon (Ar), nitrogen (N ２ ), helium (He) gas, etc. The purge gas can remove remaining by-products and unadsorbed platinum precursor.

[0039] Next, tricarbonyl(trimethylenemethane)ruthenium ([Ru(TMM)(CO) ３ ]) can be used. When the precursor is gas, it can be supplied as a ruthenium precursor. When 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, a step of purging the ruthenium precursor can be performed. The purge gas can be argon (Ar), nitrogen (N ２ ), helium (He) gas, etc. The purge gas can remove 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. The purge gas is argon (Ar), nitrogen (N ２ ), helium (He) gas, etc. can be used.

[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 crystalline structure of the platinum-ruthenium alloy thin film as a function of the platinum precursor supply time in the method for forming the platinum-ruthenium alloy thin film according to the first embodiment.

[0045] Referring to Figure 5, the results of X-ray diffraction analysis of the crystalline structure of platinum-ruthenium alloy thin films are shown as a function of the platinum precursor supply time. All thin films except for the PtRu1 thin film in Figure 5 have a platinum face-centered cubic (fcc) structure. Therefore, peaks corresponding to the corresponding crystal planes (111), (200), (220), and (311) are dominant. It can also be seen that the longer the platinum supply time, the more the Ru (001) peak shifts to 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 the platinum-ruthenium alloy thin film according to the first embodiment.

[0047] Referring to FIG. 6, the density of the platinum thin film is 20.77 g / cm ３ , roughness 1.3 nm, thickness 24.6 nm. The density of the ruthenium thin film is 12.36 g / cm ３ , roughness 2.4 nm, thickness 27.4 nm. The density of the platinum-ruthenium alloy thin film formed by the first embodiment increases with increasing platinum supply time, ranging from 17.54 to 20.83 g / cm ３ It can be seen that all the films formed except for the film (PtRu1) in which the platinum supply time was 1 second have a density 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 supplying the platinum precursor for 3 seconds and 10 seconds, respectively, among the thin films formed by the first embodiment. 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 the platinum-ruthenium alloy thin films according to the first embodiment. For the 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 the 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, 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] 9 shows the thickness of the platinum thin film deposited by changing the deposition temperature of the platinum precursor while keeping the injection time of the platinum precursor 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 analyzing the crystal structure by XRD 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 set to 1 second, 5 seconds, 10 seconds, 15 seconds, and 20 seconds, and the alloy thin films obtained at each time are shown as PtRu7, PtRu8, PtRu9, PtRu10, and PtRu11.

[0056] 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 the (001) peak of ruthenium shifts toward the (002) peak of platinum as the platinum precursor supply time increases.

[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 the 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 ３The 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 alloy thin films, except for the thin film (PtRu7) in which the platinum supply time is 1 second, have densities 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 an alloy thin film can be obtained 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) shown 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.

[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. A method for forming a platinum-ruthenium alloy thin film by atomic layer modulation, comprising the steps of: supplying a platinum precursor to a substrate in a chamber; purging the platinum precursor from the chamber; supplying 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 reactive gas from the chamber.

2. The method for forming a platinum-ruthenium alloy thin film according to claim 1, characterized in that a platinum precursor having the structure of Chemical Formula 1 below and a ruthenium precursor having the structure of Chemical Formula 2 below are used to form a platinum-ruthenium alloy thin film by atomic layer modulation.

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

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

6. A method for forming a platinum-ruthenium alloy thin film according to claim 1 or 2, 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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