Method for forming thin film and method for forming capping layer

Abstract

A method for forming a thin film according to an embodiment of the present invention includes forming a ruthenium electrode made of a ruthenium (Ru) metal film on one surface of a substrate, and forming a capping layer on the ruthenium electrode, and the step of forming the capping layer may include spraying a precursor containing ruthenium (Ru) toward the ruthenium electrode and spraying a reactant gas containing nitrogen (N) toward the ruthenium electrode. Therefore, according to an embodiment of the present invention, at least one of a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer is formed on the ruthenium (Ru) metal film, which can suppress or prevent the ruthenium (Ru) metal film from being oxidized, thereby suppressing or preventing the electrical properties of the ruthenium (Ru) metal film from being degraded due to oxidation.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a thin film and a method for forming a capping layer, and more particularly to a method for forming a thin film and a capping layer that can suppress or prevent oxidation of a ruthenium (Ru) metal film. [Background technology]

[0002] A capacitor includes a lower electrode formed on a substrate, a dielectric film formed on the lower electrode, and an upper electrode formed on the dielectric film, where the upper and lower electrodes may be formed of metal films.

[0003] However, metal films are easily oxidized, which causes a problem of deterioration in the electrical characteristics of the electrode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Korean Patent Registration No. 10-1060771 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method for forming a thin film and a method for forming a capping layer that can improve the electrical properties of a metal film.

[0006] The present invention provides a method for forming a thin film and a method for forming a capping layer that can suppress or prevent oxidation of a metal film. [Means for solving the problem]

[0007] A method for forming a thin film according to an embodiment of the present invention includes the steps of forming a ruthenium electrode made of a ruthenium (Ru) metal film on one surface of a substrate, and forming a capping layer on the ruthenium electrode, wherein the step of forming the capping layer may include the steps of spraying a precursor containing ruthenium (Ru) toward the ruthenium electrode, and spraying a reactant gas containing nitrogen (N) toward the ruthenium electrode.

[0008] A method for forming a thin film according to an embodiment of the present invention includes the steps of forming a ruthenium electrode made of a ruthenium (Ru) metal film on one surface of a substrate, and forming a capping layer on the ruthenium electrode, wherein the step of forming the capping layer may include the steps of spraying a precursor containing ruthenium (Ru) toward the ruthenium electrode, and spraying a reactant gas containing nitrogen (N) and oxygen (O) toward the ruthenium electrode.

[0009] The step of forming the ruthenium electrode may include the steps of injecting a precursor containing ruthenium and injecting a gas containing oxygen (O).

[0010] The method for forming a thin film may include, after completing the step of injecting the oxygen-containing gas, a step of injecting a gas containing at least one of hydrogen (H2), ammonia (NH3), and argon (Ar) to generate plasma.

[0011] The step of injecting the oxygen-containing gas may include the step of generating an oxygen plasma.

[0012] When forming the capping layer, the capping layer may be formed to have a thickness smaller than that of the ruthenium (Ru) metal film.

[0013] A method for forming a capping layer according to an embodiment of the present invention includes the steps of: preparing a substrate having a ruthenium (Ru) metal film formed on one surface thereof; and forming a capping layer on the ruthenium (Ru) metal film, wherein the step of forming the capping layer may include the steps of spraying a precursor containing ruthenium (Ru) toward the ruthenium (Ru) metal film; and spraying a reactant gas containing nitrogen (N) toward the ruthenium (Ru) metal film to form a ruthenium nitride (RuN) capping layer on the ruthenium (Ru) metal film.

[0014] A method for forming a capping layer according to an embodiment of the present invention includes the steps of: preparing a substrate having a ruthenium (Ru) metal film formed on one surface thereof; and forming a capping layer on the ruthenium (Ru) metal film, wherein the step of forming the capping layer may include the steps of spraying a precursor containing ruthenium (Ru) toward the ruthenium (Ru) metal film; and spraying a reactant gas containing nitrogen (N) and oxygen (O) toward the ruthenium (Ru) metal film to form a ruthenium oxynitride (RuON) capping layer on the ruthenium (Ru) metal film. [Effects of the Invention]

[0015] According to an embodiment of the present invention, at least one of a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer is formed on the ruthenium (Ru) metal film, which can suppress or prevent the ruthenium (Ru) metal film from being oxidized, thereby suppressing or preventing the electrical properties of the ruthenium (Ru) metal film from being degraded due to oxidation. [Brief explanation of the drawings]

[0016] [Figure 1]2A and 2B illustrate a ruthenium (Ru) metal film and a capping layer formed on a substrate by a method according to an embodiment of the present invention. [Figure 2] 1A and 1B are conceptual diagrams illustrating a method for forming a capping layer according to an embodiment of the present invention. [Figure 3] 1A to 1C are process diagrams conceptually showing a method for forming a capping layer on a ruthenium (Ru) metal film by a method according to an embodiment of the present invention. [Figure 4] 1 is a diagram showing a state in which a capping layer is formed on a ruthenium (Ru) metal film formed on a substrate having a trench by a method according to an embodiment of the present invention. [Figure 5] 1 is a conceptual diagram illustrating a capacitor having a capping layer formed by a method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided merely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art. Note that the drawings may be exaggerated to illustrate the embodiments of the present invention, and the same reference numerals in the drawings indicate the same components.

[0018] Embodiments of the present invention relate to a method for forming a ruthenium (Ru) metal film and a method for forming a thin film formed on the ruthenium (Ru) metal film. Here, the thin film formed on the ruthenium (Ru) metal film may be referred to as a "capping layer" or "capping film." That is, embodiments of the present invention relate to a method for forming a ruthenium (Ru) metal film and a method for forming a capping layer that can improve the electrical properties of the ruthenium (Ru) metal film. Furthermore, embodiments of the present invention relate to a method for forming a capping layer that can improve the electrical properties of an electrode including a ruthenium (Ru) metal film.

[0019] Here, the electrode including the ruthenium (Ru) metal film may be, for example, at least one of the upper electrode and the lower electrode of the capacitor. That is, at least one of the upper electrode and the lower electrode of the capacitor may be formed from the ruthenium (Ru) metal film formed by the method according to the embodiment of the present invention. Furthermore, the capacitor may include a capping layer formed to cover at least one of the upper electrode and the lower electrode.

[0020] FIG. 1 is a diagram illustrating a ruthenium (Ru) metal film and a capping layer formed on a substrate by a method according to an embodiment of the present invention.

[0021] Referring to FIG. 1, a ruthenium (Ru) metal film 100 may be formed on a substrate S, and a capping layer 200 may be formed on the ruthenium (Ru) metal film 100.

[0022] The substrate S may be a wafer, which may be any one of a Si wafer, a GaAs wafer, and a SiGe wafer. Needless to say, the substrate S may be made of any one of glass, metal, plastic, a polymer film, and a dielectric material.

[0023] The ruthenium (Ru) metal film 100 may be formed on one surface of the substrate S, for example, on the top surface of the substrate S. The ruthenium (Ru) metal film 100 may be an electrode of a semiconductor device such as a capacitor. For this reason, the ruthenium (Ru) metal film 100 is sometimes referred to as a "ruthenium electrode."

[0024] The ruthenium (Ru) metal film 100 may be formed by, for example, atomic layer deposition (ALD). A method for forming the ruthenium (Ru) metal film 100 by atomic layer deposition (ALD) will be briefly described below.

[0025] First, a precursor containing ruthenium (Ru) is injected. Here, as a precursor material containing Ru, for example, ethylcyclopentadienylruthenium ((EtCp)2Ru) (Bis(ethylcyclopentadienyl)ruthenium) can be used. When the precursor containing ruthenium (Ru) is injected in this manner, the precursor containing ruthenium (Ru) is deposited or adsorbed on one surface of the substrate S, forming a thin film containing ruthenium (hereinafter referred to as a ruthenium metal film).

[0026] After the precursor injection step is completed, a first purge is performed by injecting a purge gas into the chamber containing the substrate S. At this time, the purge gas may be, for example, argon (Ar) gas.

[0027] On the other hand, the ruthenium metal film 100 may contain impurities resulting from the precursors. More specifically, the ruthenium metal film 100 may contain ligands such as carbon (C), which may act as impurities that increase the resistivity of the ruthenium (Ru) metal film 100.

[0028] Therefore, after the first purge is completed, a gas containing oxygen (O) (hereinafter referred to as oxygen-containing gas) is injected into the chamber containing the substrate S to remove impurities. The oxygen-containing gas may be, for example, pure oxygen (O) gas. Needless to say, the present invention is not limited to this, and a wide variety of gases containing oxygen (O) can be used.

[0029] When an oxygen-containing gas is injected into the chamber, the ligands contained in the ruthenium metal film 100, for example, the C (carbon) ligands, react with oxygen. That is, a combustion reaction occurs between the oxygen (O) contained in the oxygen-containing gas and the C (carbon) ligands, causing C (carbon) to be desorbed from the ruthenium metal film 100. In other words, the C (carbon)-ligand bond contained in the precursor of the ruthenium metal film 100 is broken and desorbed out of the ruthenium metal film 100. This reduces the content of ligand impurities such as C (carbon) contained in the ruthenium metal film 100, or removes the ligand impurities from the ruthenium metal film 100.

[0030] As described above, in the step of injecting the oxygen-containing gas, the temperature inside the chamber is maintained at 200°C to 400°C, preferably 250°C to 300°C. This allows the combustion reaction between the oxygen (O) contained in the injected oxygen-containing gas and the ligand to occur smoothly. That is, the heat inside the chamber allows the combustion reaction between the oxygen (O) contained in the oxygen-containing gas and the ligand contained in the ruthenium metal film 100 to occur smoothly. Therefore, the combustion reaction between the oxygen (O) contained in the oxygen-containing gas and the ligand contained in the ruthenium (Ru) metal film 100 or precursor can be explained as a thermal reaction.

[0031] When injecting the oxygen-containing gas, the injection flow rate is appropriately adjusted. That is, the injection flow rate of the oxygen-containing gas is adjusted so as to remove impurities contained in the ruthenium (Ru) metal film 100 while preventing ruthenium oxide from being generated on the ruthenium (Ru) metal film 100. That is, if the injection flow rate of the oxygen gas is excessively low, there is a risk that the effect of removing impurities will not be obtained, and if the injection flow rate of the oxygen gas is excessively high, there is a risk that ruthenium oxide will be generated on the ruthenium (Ru) metal film 100. For this reason, the injection flow rate of the oxygen-containing gas is appropriately adjusted so as to remove impurities contained in the ruthenium (Ru) metal film 100 while preventing ruthenium oxide from being generated on the ruthenium (Ru) metal film 100.

[0032] After the step of injecting the oxygen-containing gas is completed, a purge gas is injected into the chamber to purge it (secondary purge step). At this time, the same gas as that used in the primary purge step can be used as the purge gas, for example, Ar gas.

[0033] Thus, the method for forming a ruthenium metal film may include a precursor injection step, a primary purge step, an oxygen-containing gas injection step, and a secondary purge step. The method for forming a ruthenium metal film may include a process cycle, and the process cycle may include "a precursor injection step, a primary purge step, an oxygen-containing gas injection step, and a secondary purge step." At least one of the primary purge step and the secondary purge step in the process cycle may be omitted.

[0034] The process cycle can be repeated multiple times to form the desired ruthenium (Ru) metal film 100. In this case, the ruthenium (Ru) metal film 100 may be formed to a thickness of, for example, 100 Å to 200 Å.

[0035] The method for forming a ruthenium (Ru) metal film may also include a step of forming oxygen plasma. That is, oxygen plasma may be formed when an oxygen-containing gas is injected after the precursor injection step or the primary purge step is completed. To this end, while injecting the oxygen-containing gas into the chamber, radio frequency (RF) power is supplied to at least one of a susceptor on which the substrate S is placed inside the chamber and an injection unit that injects gas into the chamber. This allows oxygen-containing plasma, i.e., oxygen plasma, to be generated inside the chamber. As a result, the substrate S on which the ruthenium (Ru) metal film 100 is formed is exposed to the oxygen plasma, causing impurities to react with oxygen. At this time, impurities such as C (carbon) contained in the ruthenium (Ru) metal film 100 react with oxygen to become gas and escape from the ruthenium (Ru) metal film. This reduces the content of impurities such as C (carbon) contained in the ruthenium (Ru) metal film, thereby reducing the resistivity of the ruthenium (Ru) metal film 100.

[0036] Furthermore, the method for forming a ruthenium metal film may further include forming a plasma, i.e., injecting an oxygen-containing gas, forming an oxygen plasma while injecting an oxygen-containing gas, or forming the plasma after the second purge step.

[0037] For this purpose, RF (Radio Frequency) power is supplied to at least one of a susceptor on which the substrate S is placed inside the chamber and an injection unit that injects gas into the chamber. Furthermore, a gas containing at least one of hydrogen (H), ammonia (NH), and argon (Ar) can be used as the plasma generating gas. As described above, supplying RF power and injecting the plasma generating gas makes it possible to generate plasma inside the chamber. Therefore, the substrate S on which the ruthenium (Ru) metal film 100 is formed is exposed to the plasma.

[0038] However, even after the oxygen-containing gas injection step or the oxygen plasma formation step while injecting an oxygen-containing gas is completed, impurities that were not completely removed may remain in the ruthenium metal film 100. Therefore, by forming an additional plasma after the oxygen-containing gas injection step, the oxygen plasma formation step while injecting an oxygen-containing gas, or the secondary purge step is completed, the remaining impurities can be further removed. At this time, impurities such as C (carbon) contained in the ruthenium (Ru) metal film 100 are gasified by the plasma and released from the ruthenium (Ru) metal film. Therefore, the content of impurities such as C (carbon) contained in the ruthenium (Ru) metal film is reduced, thereby lowering the resistivity of the ruthenium (Ru) metal film 100.

[0039] In this way, by further forming plasma after the step of injecting the oxygen-containing gas, the step of forming oxygen plasma while injecting the oxygen-containing gas, or the second purge step, the content of impurities contained in the ruthenium metal film 100 can be further reduced, and therefore the resistivity of the ruthenium metal film 100 can be further reduced.

[0040] The above-described "precursor injection step, first purge step, oxygen-containing gas injection step, second purge step, and plasma formation step" may be considered as one process cycle. As another example, "precursor injection step, first purge step, step of forming oxygen plasma while injecting oxygen-containing gas, second purge step, and plasma formation step" may be considered as one process cycle. At least one of the first purge step and the second purge step in the process cycle may be omitted. Furthermore, the process cycle may be repeated multiple times to form a desired ruthenium (Ru) metal film. In this case, the ruthenium (Ru) metal film 100 may be formed to a thickness of, for example, 100 Å to 200 Å.

[0041] The above description has been given of a case where a ruthenium (Ru) metal film is formed by atomic layer deposition (ALD). However, the present invention is not limited to this, and the ruthenium (Ru) metal film 100 can be formed by various methods. For example, the ruthenium (Ru) metal film 100 can be formed by any one of chemical vapor deposition (CVD), thermal evaporation deposition, and physical vapor deposition (PVD). When the ruthenium (Ru) metal film 100 is formed by physical vapor deposition (PVD), it can be formed by, for example, sputtering.

[0042] On the other hand, the ruthenium (Ru) metal film 100 may be oxidized, and if the ruthenium (Ru) metal film 100 is oxidized, its electrical characteristics may be degraded. For example, the resistivity of the ruthenium (Ru) metal film 100 may increase due to oxidation.

[0043] Therefore, in an embodiment of the present invention, after forming a ruthenium (Ru) metal film 100, a capping layer 200 is formed on the ruthenium (Ru) metal film 100. That is, the capping layer 200 is formed to cover at least a portion of the ruthenium (Ru) metal film 100. In this case, the capping layer 200 may be formed of either a nitride film containing ruthenium (Ru) or an oxynitride film containing ruthenium (Ru). That is, the capping layer 200 may include either a ruthenium nitride (RuN) capping layer made of ruthenium nitride (RuN) or a ruthenium oxynitride (RuON) capping layer made of ruthenium oxynitride (RuON). More specifically, the capping layer 200 may be either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer. The capping layer 200 is formed to cover at least a portion of the ruthenium (Ru) metal film 100 to inhibit or prevent oxidation of the ruthenium (Ru) metal film 100. In other words, the capping layer 200 protects the ruthenium (Ru) metal film 100 so that oxidation of the ruthenium (Ru) metal film 100 is inhibited or prevented. Therefore, the capping layer 200 may be referred to as a protection layer or a protection film. The capping layer 200 may also be referred to as a capping film.

[0044] A method for forming a ruthenium nitride (RuN) capping layer, which is the capping layer 200 according to the first embodiment of the present invention, on a ruthenium (Ru) metal film 100 will be described below with reference to FIGS.

[0045] Fig. 2 is a conceptual diagram for explaining a method for forming a capping layer by a method according to an embodiment of the present invention, and Fig. 3 is a process diagram conceptually showing a method for forming a capping layer on a ruthenium (Ru) metal film by a method according to an embodiment of the present invention.

[0046] In FIG. 2, "on" may mean injecting a raw material or gas for forming a thin film, and "off" may mean interrupting or terminating the injection of the raw material or gas.

[0047] 2 and 3, a method for forming a capping layer 200 on a ruthenium (Ru) metal film 100 may include a step of injecting a precursor containing ruthenium (Ru) (precursor injection step), and a step of injecting a reactant gas containing nitrogen (N) (reactant gas injection step) after the precursor injection step is completed.

[0048] The method for forming the capping layer 200 may further include at least one of a step of injecting a purge gas between the precursor injection step and the reactant injection step (a first purge step) and a step of injecting a purge gas after the reactant gas injection step (a second purge step). Here, Ar gas can be used as the purge gas.

[0049] Furthermore, a process cycle CY may be formed by "precursor injection step-primary purge step-reactant gas injection step-secondary purge step" to form the capping layer 200. In this case, at least one of the primary purge step and the secondary purge step in the process cycle CY may be omitted. The process cycle CY may be repeated one or more times to form the capping layer 200 on the ruthenium (Ru) metal film 100, as shown in FIG. 1.

[0050] The method for forming the capping layer 200 may further include generating hydrogen plasma after the injection of the reactant gas or after the second purge is completed. In this case, the "precursor injection step - first purge step - reactant gas injection step - second purge step - hydrogen plasma generation step" may be considered as one process cycle CY for forming the capping layer 200.

[0051] The number of times the process cycle CY is repeated can be adjusted depending on the target thickness to be formed. In this case, the thickness of the capping layer 200 may be formed to be thinner than the thickness of the ruthenium (Ru) metal film 100. The thickness of the capping layer 200 may be 5% to 15%, more preferably 8% to 12%, of the thickness of the ruthenium (Ru) metal film 100. More specifically, the thickness of the ruthenium (Ru) metal film 100 may be 100 Å to 200 Å. In this case, the capping layer 200 may be formed to a thickness of 5 Å to 30 Å, more preferably 8 Å to 24 Å.

[0052] Each step of the process cycle CY will be explained in more detail below.

[0053] In the precursor injection step, a precursor containing ruthenium (Ru) is injected toward the substrate S. That is, the precursor containing ruthenium (Ru) is injected into the chamber in which the substrate S is placed. Here, as the precursor material containing ruthenium (Ru), for example, ethylcyclopentadienylruthenium ((EtCp)Ru) (Bis(ethylcyclopentadienyl)ruthenium) can be used. By injecting the precursor containing ruthenium (Ru) in this manner, the precursor is deposited or adsorbed on one surface of the substrate S, and a thin film containing ruthenium (Ru) (hereinafter, referred to as a ruthenium (Ru)-containing layer 210) is formed, as shown in FIG. 3(a).

[0054] After the precursor injection step is completed, a first purge is performed by injecting a purge gas into the chamber containing the substrate S. At this time, the purge gas may be, for example, argon (Ar) gas.

[0055] After the first purge is completed, a reactant gas containing nitrogen (N) is injected into the chamber containing the substrate S. The reactant gas containing nitrogen (N) can be a gas containing at least one of ammonia (NH) gas and nitrogen (N). Needless to say, the reactant gas containing nitrogen (N) is not limited to the above example, and various gases containing nitrogen (N) can be used. When the reactant gas containing nitrogen (N) is injected, the ruthenium (Ru)-containing layer 210 is exposed to the reactant gas. As a result, the nitrogen (N) contained in the reactant gas reacts with the ruthenium (Ru)-containing layer 210, forming a ruthenium nitride (RuN) thin film, as shown in FIG. 3(b). That is, a capping layer 200 made of ruthenium nitride (RuN) is formed on the ruthenium (Ru) metal film 100.

[0056] After the step of injecting the reactant gas is completed, a second purge is performed by injecting a purge gas into the chamber containing the substrate S. At this time, the same gas as that used in the first purge step can be used as the purge gas, for example, argon (Ar).

[0057] Furthermore, after the second purge is completed, hydrogen plasma may be generated inside the chamber in which the substrate S is placed. To this end, a gas containing hydrogen (H2) is injected into the chamber or toward the substrate S, and power is supplied to generate the plasma. For example, RF (Radio Frequency) power is supplied to at least one of the chamber, the susceptor inside the chamber on which the substrate S is placed, and an injection unit that injects gas into the chamber. As described above, by supplying RF power and injecting gas containing hydrogen (H2), it is possible to generate hydrogen-containing plasma, i.e., hydrogen plasma, inside the chamber.

[0058] The process cycle CY, which includes the precursor injection step, the first purge step, the reactant gas injection step, and the second purge step as described above, may be repeated one or more times. That is, the process cycle CY may be repeated one or more times depending on the target thickness of the capping layer 200. Furthermore, the process cycle CY may further include a hydrogen plasma generation step as described above, and such a process cycle CY may be repeated one or more times.

[0059] As described above, in the embodiment, after forming the ruthenium (Ru) metal film 100, the ruthenium nitride (RuN) capping layer 200 is formed to cover the ruthenium (Ru) metal film 100. Therefore, the ruthenium nitride (RuN) capping layer 200 suppresses or prevents the ruthenium (Ru) metal film 100 from being exposed to the atmosphere. Therefore, the ruthenium nitride (RuN) capping layer 200 can suppress or prevent the ruthenium (Ru) metal film 100 from being oxidized.

[0060] The ruthenium (Ru) metal film 100 is formed thick, for example, to a thickness of 100 Å to 200 Å, and the ruthenium nitride (RuN) capping layer 200 is formed thin, with a thickness of 5% to 15% of the thickness of the ruthenium (Ru) metal film 100. Therefore, when the ruthenium (Ru) metal film 100 is used as an electrode, even if the ruthenium nitride (RuN) capping layer 200 is formed on the ruthenium (Ru) metal film 100, the ruthenium nitride (RuN) capping layer 200 has no or almost no insulating function. In other words, even if the ruthenium (Ru) metal film 100, the ruthenium nitride (RuN) capping layer 200, and a conductive film are stacked in this order, the ruthenium nitride (RuN) capping layer 200 does not insulate the ruthenium (Ru) metal film 100 from the conductive film. In other words, even if the ruthenium nitride (RuN) capping layer 200 is formed between the ruthenium (Ru) metal film 100 and the conductive film, the ruthenium (Ru) metal film 100 and the conductive film can be electrically conductive. Therefore, the ruthenium nitride (RuN) capping layer 200 formed on the ruthenium (Ru) metal film 100 can suppress or prevent oxidation of the ruthenium (Ru) metal film 100 while allowing the ruthenium (Ru) metal film 100 to be electrically conductive without insulating it from other films.

[0061] The above describes a method for forming a ruthenium nitride (RuN) capping layer 200 on a ruthenium (Ru) metal film 100. Below, a method for forming a ruthenium oxynitride (RuON) capping layer, which is a capping layer according to the second embodiment, on a ruthenium (Ru) metal film 100 will be described with reference to FIGS.

[0062] A method for forming a ruthenium oxynitride (RuON) capping layer 200 on a ruthenium (Ru) metal film 100 may include a precursor injection step of injecting a precursor containing ruthenium (Ru), and a reactant gas injection step of injecting a reactant gas containing oxygen (O) and nitrogen (N) after the precursor injection step is completed.

[0063] In addition, the method for forming the ruthenium oxynitride (RuON) capping layer 200 may further include at least one of a first purge step injecting a purge gas between the precursor injection step and the reactant injection step and a second purge step injecting a purge gas after the reactant gas injection step is completed.

[0064] The "precursor injection step-first purge step-reactant gas injection step-second purge step" may be considered as one process cycle CY for forming the capping layer 200. The process cycle CY may be repeated one or more times to form a ruthenium oxynitride (RuON) capping layer on the ruthenium (Ru) metal film, as shown in FIG. 1. The number of times the process cycle CY is repeated can be adjusted depending on the target thickness of the ruthenium oxynitride (RuON) capping layer to be formed.

[0065] The ruthenium oxynitride (RuON) capping layer 200 is formed to have a thickness thinner than that of the ruthenium (Ru) metal film 100. In this case, the thickness of the ruthenium oxynitride (RuON) capping layer 200 is formed to be 5% to 15%, more preferably 8% to 12%, of the thickness of the ruthenium (Ru) metal film 100. More specifically, the thickness of the ruthenium (Ru) metal film 100 may be 100 Å to 200 Å, and in this case, the thickness of the ruthenium oxynitride (RuON) capping layer 200 is formed to be 5 Å to 30 Å, more preferably 8 Å to 24 Å.

[0066] The method for forming a ruthenium oxynitride (RuON) capping layer (second embodiment) differs from the method for forming a ruthenium nitride (RuON) capping layer (first embodiment) only in the type of reactant gas used, and the other steps are performed in the same manner. Therefore, the following will only describe the reactant gas injection step, and will omit descriptions of the precursor injection step and the primary and secondary purge steps. In addition, when describing the reactant gas injection step, content that overlaps with the first embodiment will be omitted or briefly described.

[0067] The reactant gas injection step is performed after the precursor injection step is completed or after the primary purge is completed. That is, the reactant gas is injected into the chamber in which the substrate S is placed. At this time, a gas containing oxygen (O) and nitrogen (N) is used as the reactant gas. Here, for example, O2 gas can be used as the oxygen (O)-containing gas. Also, at least one of ammonia (NH3) gas and nitrogen (N2) can be used as the nitrogen (N)-containing gas. Needless to say, the oxygen (O)-containing gas and the nitrogen (N)-containing gas are not limited to the above-mentioned examples, and other gases containing oxygen (O) and other gases containing nitrogen (N) can be used as the reactant gas.

[0068] When a precursor containing ruthenium (Ru) is injected in the precursor injection step, the precursor is adsorbed or deposited on the ruthenium (Ru) metal film 100, forming a ruthenium (Ru)-containing layer 210. Then, when a reactant gas containing oxygen (O) and nitrogen (N) is injected toward the substrate S, the ruthenium (Ru)-containing layer 210 reacts with the reactant gas. That is, the ruthenium (Ru) contained in the ruthenium (Ru)-containing layer 210 reacts with the oxygen (O) and nitrogen (N) contained in the reactant gas. As a result, the ruthenium (Ru)-containing layer 210 is oxidized and nitrided, thereby converting into ruthenium oxynitride (RuON). In other words, a capping layer 200 made of ruthenium oxynitride (RuON) is formed on the ruthenium (Ru) metal film 100.

[0069] As described above, in the second embodiment, the ruthenium oxynitride (RuON) capping layer 200 is formed on the ruthenium (Ru) metal film 100. Therefore, the ruthenium (Ru) metal film 100 is covered with the ruthenium oxynitride (RuON) capping layer 200. Therefore, it is possible to suppress or prevent the ruthenium (Ru) metal film 100 from being exposed to light, and thereby it is possible to suppress or prevent the ruthenium (Ru) metal film 100 from being oxidized.

[0070] FIG. 4 is a diagram showing a state in which a capping layer is formed on a ruthenium (Ru) metal film formed on a substrate having a trench by a method according to an embodiment of the present invention.

[0071] 1 and 3, a capping layer is formed on a ruthenium (Ru) metal film formed on a planar substrate without a trench. However, the present invention is not limited to this. As shown in FIG. 4, a ruthenium (Ru) metal film 100 may be formed on a substrate S with a trench T, and a capping layer 200 may be formed on the ruthenium (Ru) metal film 100. This will be described in more detail below.

[0072] As shown in FIG. 4, the substrate S may have a groove, i.e., a trench T, formed vertically and partially penetrating the substrate S. A ruthenium (Ru) metal film 100 may be formed on the upper surface of the substrate S and on the peripheral wall surrounding the trench T. More specifically, the ruthenium (Ru) metal film 100 may be formed on the bottom surface and side surface of the trench T, and on the upper surface of the substrate S, which is the outer surface of the trench T. As shown in FIG. 4, either a ruthenium nitride capping layer 200 or a ruthenium oxynitride capping layer 200 may be formed on the ruthenium (Ru) metal film 100.

[0073] In the above description, when forming the capping layer 200 on the ruthenium (Ru) metal film 100, it has been described that either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer is formed. However, the present invention is not limited thereto, and the capping layer 200 may be formed by stacking a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer. That is, the capping layer 200 formed on the ruthenium (Ru) metal film 100 may include a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer. In this case, the ruthenium nitride (RuN) capping layer and the ruthenium oxynitride (RuON) capping layer may be alternately stacked.

[0074] FIG. 5 is a conceptual diagram of a capacitor having a capping layer formed by a method according to an embodiment of the present invention.

[0075] A capacitor including a capping layer 200 according to an embodiment of the present invention will be described below with reference to Fig. 5. Here, a case will be described in which the lower electrode of a capacitor 1000 is formed from a ruthenium (Ru) metal film, and the capping layer 200 according to the embodiment is formed on the upper part of the lower electrode 100. Therefore, for ease of explanation, the lower electrode will be denoted by the reference numeral "100" like the ruthenium (Ru) metal film.

[0076] 5, a capacitor 1000 may include a substrate S, a lower electrode 100 formed on the substrate S and made of a ruthenium (Ru) metal film, a capping layer 200 formed on the lower electrode 100, a dielectric film 300 formed on the capping layer 200, and an upper electrode 400 formed on the dielectric film 300. The capacitor 1000 may further include a contact layer (not shown) formed below the lower electrode 100.

[0077] Here, the substrate S may be a wafer, and the wafer may be any one of a Si wafer, a GaAs wafer, and a SiGe wafer. Needless to say, the substrate S may be made of any one of glass, metal, plastic, a polymer film, and a dielectric material.

[0078] The lower electrode 100 may be formed on one surface of the substrate, for example, the upper surface, and may be formed of a ruthenium (Ru) metal film as described above. A contact layer may be formed below the lower electrode 100, i.e., between the substrate S and the lower electrode 100. In this case, the contact layer may be formed of a metal oxide, for example, a SiO2 thin film or an Al2O3 thin film.

[0079] The capping layer 200 may be formed to cover at least a portion of the lower electrode 100 formed from a ruthenium (Ru) metal film, and may be formed from either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer.

[0080] The dielectric film 300 may be formed on the capping layer 200 and may be made of a dielectric material including a metal oxide. More specifically, the dielectric film 300 may be made of any one of ZrO2, Al2O3, TiO2, TaO2, and HfO2. The dielectric film 300 may be formed by an atomic layer deposition (ALD) method or a chemical vapor deposition (CVD) method.

[0081] The upper electrode 400 may be formed on the dielectric film 300 and may be made of a variety of conductive materials. In this case, the upper electrode 400 may be made of a ruthenium (Ru) metal film, or may be made of a metal film other than ruthenium (Ru).

[0082] A ruthenium nitride (RuN) capping layer 200 or a ruthenium oxynitride (RuON) capping layer 200 is formed on the lower electrode 100 of the capacitor 1000. Therefore, the ruthenium nitride (RuN) capping layer 200 or the ruthenium oxynitride (RuON) capping layer 200 can suppress or prevent the lower electrode 100 from being oxidized. Therefore, it can suppress or prevent the electrical characteristics of the lower electrode 100, such as the resistivity, from increasing due to oxidation.

[0083] Although not shown, a capping layer may be formed on the upper electrode 400, and the capping layer may be formed of either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer.

[0084] In the above description, the lower electrode 100 is formed of a ruthenium (Ru) metal film, and the capping layer 200 is formed on the lower electrode 100. However, the present invention is not limited to this. The upper electrode 400 may be formed of a ruthenium (Ru) metal film, and either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer may be formed on the upper electrode 400. In this case, the lower electrode 100 may be formed of a metal film other than ruthenium (Ru), and the capping layer 200 may not be formed between the lower electrode 100 and the dielectric film 300. Needless to say, the lower electrode 100 may be formed of a metal film other than ruthenium (Ru), and the capping layer 200 may be formed on such a lower electrode 100. Alternatively, each of the lower electrode 100 and the upper electrode 400 may be formed from a ruthenium (Ru) metal film, and the capping layer 200 may be formed between the lower electrode 100 and the dielectric film 300 and on the upper electrode 400 .

[0085] In the above, it has been described that the capping layer 200 is formed on at least one of the lower electrode 100 and the upper electrode 400 by using either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer. However, the present invention is not limited thereto, and the capping layer 200 may be formed by stacking a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer. That is, the capping layer 200 formed on at least one of the lower electrode 100 and the upper electrode 400 may include a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer. In this case, the ruthenium nitride (RuN) capping layer and the ruthenium oxynitride (RuON) capping layer may be alternately stacked.

[0086] In the above description, it has been described that either a ruthenium nitride (RuN) capping layer or a ruthenium oxynitride (RuON) capping layer is formed to cover at least one of the lower electrode 100 and the upper electrode 400 of the capacitor 1000. However, the capping layer 200 formed by the method according to the embodiment is not limited to the electrode of the capacitor 1000, and may be applied to a wide variety of semiconductor or electronic devices having electrodes. [Industrial Applicability]

[0087] According to an embodiment of the present invention, at least one of a ruthenium nitride (RuN) capping layer and a ruthenium oxynitride (RuON) capping layer is formed on the ruthenium (Ru) metal film, which can suppress or prevent the ruthenium (Ru) metal film from being oxidized, thereby suppressing or preventing the electrical properties of the ruthenium (Ru) metal film from being degraded due to oxidation.

Claims

1. forming a ruthenium electrode made of a ruthenium (Ru) metal film on one surface of the substrate; forming a capping layer on the ruthenium electrode; Including, The step of forming the capping layer includes: Injecting a precursor containing ruthenium (Ru) toward the ruthenium electrode; Injecting a reactant gas containing nitrogen (N) toward the ruthenium electrode; A method for forming a thin film, comprising:

2. forming a ruthenium electrode made of a ruthenium (Ru) metal film on one surface of the substrate; forming a capping layer on the ruthenium electrode; Including, The step of forming the capping layer includes: Injecting a precursor containing ruthenium (Ru) toward the ruthenium electrode; Injecting a reactant gas containing nitrogen (N) and oxygen (O) toward the ruthenium electrode; A method for forming a thin film, comprising:

3. The step of forming the ruthenium electrode comprises: injecting a precursor comprising ruthenium; Injecting a gas containing oxygen (O); The method for forming a thin film according to claim 1 or 2, comprising:

4. After the step of injecting the oxygen-containing gas is completed, Hydrogen (H ２ ), ammonia (NH ３ 4. The method for forming a thin film according to claim 3, further comprising the step of generating plasma by injecting a gas containing at least one of nitrogen (N) and argon (Ar).

5. 4. The method for forming a thin film according to claim 3, wherein the step of injecting a gas containing oxygen includes the step of generating an oxygen plasma.

6. When forming the capping layer, 3. The method for forming a thin film according to claim 1, wherein the capping layer is formed to have a thickness smaller than that of the ruthenium (Ru) metal film.

7. providing a substrate having a ruthenium (Ru) metal film formed on one surface; forming a capping layer on the ruthenium (Ru) metal film; Including, The step of forming the capping layer includes: Injecting a precursor containing ruthenium (Ru) toward the ruthenium (Ru) metal film; spraying a reactant gas containing nitrogen (N) toward the ruthenium (Ru) metal film to form a ruthenium nitride (RuN) capping layer on the ruthenium (Ru) metal film; A method for forming a capping layer, comprising:

8. providing a substrate having a ruthenium (Ru) metal film formed on one surface; forming a capping layer on the ruthenium (Ru) metal film; Including, The step of forming the capping layer includes: Injecting a precursor containing ruthenium (Ru) toward the ruthenium (Ru) metal film; spraying a reactant gas containing nitrogen (N) and oxygen (O) toward the ruthenium (Ru) metal film to form a ruthenium oxynitride (RuON) capping layer on the ruthenium (Ru) metal film; A method for forming a capping layer, comprising:

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