KR20240152733A - Forming mehtod ruthenium oxide film and manufacture method of semiconductor device having the same - Google Patents

Abstract

A method for forming a ruthenium oxide film according to an embodiment of the present invention may include a step of forming a ruthenium film by spraying a precursor containing ruthenium (Ru) toward a substrate, a step of forming a ruthenium oxide film by spraying an oxygen-containing gas onto the ruthenium film, and a step of forming plasma and exposing the ruthenium oxide film to the plasma.
Therefore, according to the embodiments of the present invention, a ruthenium oxide film having a high oxygen content can be formed. Accordingly, the quality of the ruthenium oxide film can be improved, and thus the performance of the ruthenium oxide film included in a semiconductor device can be improved.

Description

{FORMING MEHTOD RUTHENIUM OXIDE FILM AND MANUFACTURE METHOD OF SEMICONDUCTOR DEVICE HAVING THE SAME}

The present invention relates to a method for forming a ruthenium oxide film and a method for manufacturing a semiconductor device including the same, and more particularly, to a method for forming a ruthenium oxide film capable of increasing the oxygen content and a method for manufacturing a semiconductor device including the same.

A capacitor includes a substrate, a diffusion barrier film formed on the substrate, a lower electrode formed on the diffusion barrier film, a dielectric film formed on the lower electrode, and an upper electrode formed on the dielectric film. The lower electrode may be formed of a ruthenium metal film, and the diffusion barrier film may be formed of a ruthenium oxide film. Here, the diffusion barrier film is a film formed to suppress or prevent ruthenium (Ru) contained in the lower electrode from moving or diffusing to the substrate.

In forming a ruthenium oxide film, a precursor containing ruthenium (Ru) is sprayed to form a ruthenium metal film on a substrate, and oxygen gas is sprayed toward the ruthenium metal film to form it. However, ruthenium (Ru) is a noble metal and does not oxidize easily. Therefore, there is a problem that the oxygen content of the ruthenium oxide film is low, and this causes a problem that the performance of the ruthenium oxide film is deteriorated. That is, there is a problem that the ruthenium oxide film cannot suppress or prevent ruthenium (Ru) of the lower electrode from moving to the substrate.

In order to solve the problem of low oxygen content in the ruthenium oxide film, the substrate is heated to a high temperature of 800°C or higher. However, since the ruthenium metal film is formed at a temperature of 500°C or lower, the ruthenium oxide film and the ruthenium metal film cannot be formed in situ. That is, after forming the ruthenium oxide film in one deposition device, the substrate on which the ruthenium oxide film is formed must be moved to another deposition device to form the ruthenium metal film. Therefore, there is a problem that the process becomes complicated.

Korean registered patent KR 0434489

The present invention provides a method for forming a ruthenium oxide film capable of increasing the oxygen content and a method for manufacturing a semiconductor device including the same.

The present invention provides a method for forming a ruthenium oxide film capable of effectively increasing the oxygen content to form a ruthenium oxide film, and a method for manufacturing a semiconductor device including the same.

A method for forming a ruthenium oxide film according to an embodiment of the present invention may include a step of forming a ruthenium film by spraying a precursor containing ruthenium (Ru) toward a substrate; a step of forming a ruthenium oxide film by spraying an oxygen-containing gas onto the ruthenium film; and a step of forming plasma and exposing the ruthenium oxide film to the plasma.

In forming the above plasma, plasma can be formed using an oxygen-containing gas.

The above oxygen-containing gas may include one or a combination of two or more of oxygen (O ₂ ), ozone (O ₃ ), and nitrous oxide (N ₂ O).

The step of forming the plasma includes a step of forming the plasma by additionally using an inert gas in addition to the oxygen-containing gas, and the inert gas may include one or a combination of two or more of argon (Ar) and helium (He).

The oxygen content of the ruthenium oxide film exposed to the above plasma may be higher than the oxygen content of the ruthenium oxide film before exposure to the above plasma.

The film formation cycle (CY _f ) including the step of forming the above ruthenium film and the step of forming the ruthenium oxide film may be performed multiple times, and the multiple film formation cycles (CY _f ) may be performed continuously.

The step of exposing the above ruthenium oxide film to plasma can be performed after the above film formation cycle (CY _f ) is performed multiple times in succession.

In the step of forming the plasma, the step of forming the plasma additionally using an inert gas in addition to the oxygen-containing gas includes the step of injecting the oxygen-containing gas and the inert gas toward the ruthenium oxide film; and the step of generating plasma using the injected oxygen-containing gas and the inert gas; and in injecting the oxygen-containing gas and the inert gas, the oxygen-containing gas can be injected at a greater flow rate than the inert gas.

In the above film formation cycle (CY _f ), when injecting an oxygen-containing gas, an inert gas may be injected together, and the inert gas may include one or a combination of two or more of argon (Ar) and helium (He).

In the above film formation cycle (CY _f ), when injecting oxygen-containing gas and inert gas, the flow rate of the oxygen-containing gas can be greater than that of the inert gas.

In the step of forming the ruthenium film, the step of forming the ruthenium oxide film, and the plasma exposure step, the temperature of the substrate can be controlled to 250°C to 450°C.

A method for manufacturing a semiconductor device according to an embodiment of the present invention includes the steps of forming a ruthenium metal film on a substrate inside a chamber; and the steps of forming a ruthenium oxide film in situ inside the chamber in which the ruthenium metal film was formed, before or after the step of forming the ruthenium metal film; wherein the step of forming the ruthenium oxide film may include the method for forming the ruthenium oxide film described above.

In the step of forming the ruthenium metal film and the step of forming the ruthenium oxide film, the temperature of the substrate can be controlled to 250°C to 450°C.

According to embodiments of the present invention, a ruthenium oxide film having a high oxygen content can be formed. Accordingly, the quality of the ruthenium oxide film can be improved, and thus the performance of the ruthenium oxide film included in a semiconductor device can be improved.

FIG. 1 is a conceptual diagram illustrating a semiconductor device including a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention.
FIG. 2 is a conceptual diagram for explaining a method for forming a ruthenium oxide film according to a first embodiment of the present invention.
Figures 3 (a) to (c) are process diagrams for explaining the deposition step (P _f ) according to the first embodiment of the present invention.
FIG. 4 is a process diagram for explaining a plasma exposure step (P _p ) according to the first embodiment of the present invention.
FIG. 5 is a conceptual diagram for explaining a method for forming a ruthenium oxide film according to a second embodiment of the present invention.
FIG. 6 is a drawing showing a case where a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention is formed on top of a ruthenium metal film.
FIG. 7 is a drawing showing a case where a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention is formed between a substrate and a ruthenium metal film, on top of the ruthenium metal film.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and these embodiments are provided only to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention. In order to explain the embodiments of the present invention, the drawings may be exaggerated, and the same reference numerals in the drawings represent the same components.

The present invention relates to a method for forming a ruthenium oxide film capable of improving the quality of a ruthenium oxide (RuO ₂ ) film. More specifically, the present invention relates to a method for forming a ruthenium oxide film capable of forming a ruthenium oxide film having an improved oxygen content.

FIG. 1 is a conceptual diagram illustrating a semiconductor device including a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention.

A semiconductor device including a ruthenium oxide (RuO ₂ ) film may be, for example, a capacitor. Referring to FIG. 1, the capacitor may include a substrate (S), a lower conductive film (10) formed on the substrate (S), a dielectric film (20) formed on the lower conductive film (10), and an upper conductive film (30) formed on the dielectric film (20).

The substrate (S) may be a semiconductor substrate. For a more specific example, the substrate (S) may be a wafer, and may be any one of a Si wafer, a GaAs wafer, and a SiGe wafer. Of course, the substrate (S) may be made of any one of glass, metal, plastic, polymer film, and dielectric material.

The dielectric film (20) may be formed of a dielectric material including a metal oxide. As a more specific example, the dielectric film (20) may be formed of any one of ZrO ₂ , Al ₂ O ₃ , TiO ₂ , TaO _{2 ,} and HfO ₂ .

The lower conductive film (10) and the upper conductive film (30) are formed of a conductive material. At this time, the lower conductive film (10) may be formed of a ruthenium (Ru) metal film, and the upper conductive film (30) may be formed of a conductive material other than ruthenium (Ru). Of course, the upper conductive film (30) may be formed of a ruthenium (Ru) metal film, and the lower conductive film (10) may be formed of a conductive material other than ruthenium (Ru). In addition, the lower conductive film (10) and the upper conductive film (30) may also be formed of a ruthenium metal film.

Hereinafter, it will be described that the lower conductive film (10) is formed of a ruthenium metal film. Accordingly, for convenience of explanation, the lower conductive film and the ruthenium metal film are described by referring to them with the same drawing reference numeral '10'.

Meanwhile, if a lower conductive film (10) made of a ruthenium metal film is directly formed on one side of a substrate (S), for example, a Si wafer, ruthenium (Ru) contained in the lower conductive film (10) may move or diffuse to the substrate (S). This may cause a decrease in the performance of the semiconductor device. Accordingly, as shown in Fig. 1, a ruthenium oxide film (100) is formed between the substrate (S) and the lower conductive film (10). At this time, the ruthenium oxide film (100) plays a role in suppressing or preventing ruthenium (Ru) contained in the lower conductive film (10) from moving to the substrate (S). That is, the ruthenium oxide film (100) formed between the substrate (S) and the lower conductive film (10) is a diffusion barrier film that suppresses or prevents the movement of ruthenium (Ru).

The ruthenium oxide film (100) formed by the method according to the embodiments may be a diffusion barrier film formed between the substrate (S) and the lower conductive film (10) as shown in FIG. 1.

Here, the ruthenium oxide film (100) and the lower conductive film (10) laminated on the substrate (S) may be a configuration of the lower electrode. That is, the lower electrode may include the ruthenium oxide film (100) formed on the substrate (S) and the lower conductive film (10) formed on the ruthenium oxide film (100). In addition, the upper conductive film (30) may be an upper electrode.

Hereinafter, a method for forming a ruthenium oxide film according to a first embodiment of the present invention will be described with reference to FIGS. 2 to 4. At this time, forming a ruthenium oxide film on one surface of a substrate (S) will be described as an example.

FIG. 2 is a conceptual diagram for explaining a method for forming a ruthenium oxide film according to a first embodiment of the present invention. FIGS. 3 (a) to 3 (c) are process diagrams for explaining a film forming step (P _f ) according to a first embodiment of the present invention. FIG. 4 is a process diagram for explaining a plasma exposure step (P _p ) according to a first embodiment of the present invention.

In Fig. 2, 'on' means injecting raw materials or gas for film formation or generating plasma, and 'off' may mean stopping or ending the injection of the raw materials or gas, or may mean not generating plasma.

Referring to FIG. 2, a method for forming a ruthenium oxide film may include a film forming step (P _f ) of forming a ruthenium oxide (RuO ₂ ) film and a plasma exposure step (P _p ) of exposing the ruthenium oxide (RuO ₂ ) film formed in the film forming step (P _f ) to plasma to increase the oxygen content of the ruthenium oxide (RuO ₂ ) film.

For convenience of explanation, below, the ruthenium oxide (RuO ₂ ) film formed in the film formation step (P _f ) is named as a 'primary ruthenium oxide film (110)', and the film formed by exposing the primary ruthenium oxide film (110) formed in the film formation step (P _f ) to plasma is named as a 'secondary ruthenium oxide film (100)'.

Reflecting this, the method for forming the ruthenium oxide film (100) is described again as follows. The method for forming the ruthenium oxide film (100) may include a film formation step (P _f ) of forming a primary ruthenium oxide film (110) and a plasma exposure step (P _{p )} of exposing the primary ruthenium oxide film (110) to plasma to form a secondary ruthenium oxide film (100) which is a ruthenium oxide film having an increased oxygen content compared to the primary ruthenium oxide film (110).

A process including a film formation step (P _f ) and a plasma exposure step (P _p ) can be defined as one process cycle (CY). In other words, a process that is performed in the order of 'film formation step (P _f ) - plasma exposure step (P _p )' can be defined as one process cycle (CY). In addition, the process cycle (CY) can be performed multiple times.

Here, the primary ruthenium oxide film (110) is a ruthenium oxide film formed by oxidizing ruthenium, and the secondary ruthenium oxide film (100) is a ruthenium oxide film formed after exposing the primary ruthenium oxide film (110) to plasma. Accordingly, both the primary ruthenium oxide film (110) and the secondary ruthenium oxide film (100) can be named ruthenium oxide (RuO ₂ ) films. However, the primary ruthenium oxide film (110) and the secondary ruthenium oxide film (100) formed by the method according to the embodiment have a difference in the oxygen content. That is, the primary ruthenium oxide film (100) has a higher oxygen content than the primary ruthenium oxide film (110).

In addition, the secondary ruthenium oxide film (100) is a ruthenium oxide film, which is a final product to be formed by the method according to the embodiment. Accordingly, the ruthenium oxide film, which is a final product to be formed by the method according to the embodiment, and the secondary ruthenium oxide film can be described with the same drawing reference numeral. That is, the drawing reference numeral '100' described below can mean both the secondary ruthenium oxide film and the ruthenium oxide film, which is a final product.

Below, the film formation step (P _f ) is first described with reference to FIGS. 2 and 3.

Referring to (a) to (c) of FIGS. 2 and 3, the film forming step (P _f ) includes a step of forming a ruthenium film (111) by spraying a precursor containing ruthenium (Ru) toward the substrate (S) (precursor spraying step) and a step of forming a primary ruthenium oxide film (110) by spraying an oxygen-containing gas toward the ruthenium film (111).

In addition, the film formation step (P _f ) may further include at least one of a step of injecting a purge gas between the precursor injection step and the oxygen-containing gas injection step (first purge step) and a step of injecting a purge gas after the end of the oxygen-containing gas injection step (second purge step). Here, argon (Ar) gas may be used as the purge gas.

In addition, 'precursor injection step - 1st purge step - oxygen-containing gas injection step - 2nd purge step' can be performed as one cycle (hereinafter, film formation cycle (CY _f )). That is, the film formation step (P _f ) can include a film formation cycle (CY _f ), and the film formation cycle (CY _f ) can include 'precursor injection step - 1st purge step - oxygen-containing gas injection step - 2nd purge step'. And, the film formation step (P _f ) can include a plurality of film formation cycles (CY _f ), and at this time, a plurality of film formation cycles (CY _f ) can be performed continuously. In addition, at least one of the 1st purge step and the 2nd purge step may be omitted in the film formation cycle (CY _f ).

Below, each step of the membrane formation cycle (CY _f ) is described in more detail.

In the step of spraying a precursor, a precursor containing or including ruthenium (Ru) is sprayed toward the substrate (S). That is, the precursor containing ruthenium (Ru) is sprayed into the interior of the chamber in which the substrate (S) is loaded. Here, as the precursor raw material containing ruthenium (Ru), for example, ethylcyclopentadienyl ruthenium ((EtCp) ₂ Ru) (Bis(ethylcyclopentadienyl)ruthenium) can be used. When the precursor containing ruthenium (Ru) is sprayed in this way, the precursor is deposited or adsorbed on one surface of the substrate (S), and a film containing ruthenium (Ru), that is, a ruthenium film (111), is formed as shown in (a) of FIG. 3.

When the step of injecting the precursor is completed, a purge gas is injected into the chamber where the substrate (S) is loaded to perform the first purge. At this time, the purge gas can be, for example, argon (Ar) gas.

When the first purge is completed, an oxygen-containing gas is injected into the chamber in which the substrate (S) is loaded, as shown in (b) of FIG. 3. Here, the oxygen-containing gas may include, for example, one or a combination of two or more gases from among oxygen (O ₂ ), ozone (O ₃ ), and nitrous oxide (N ₂ O). When the oxygen-containing gas is injected, oxygen (O) penetrates into the ruthenium film (111), and the ruthenium film (111) and oxygen (O) react. That is, the ruthenium film (111) may react with oxygen contained in the oxygen-containing gas and be oxidized. Accordingly, a first ruthenium oxide film (110), which is a ruthenium oxide (RuO ₂ ) film containing ruthenium (Ru) and oxygen, is formed.

The oxygen-containing gas injected in the film formation step (P _f ) is a gas injected to react with the ruthenium film (111), and therefore can be named a 'reactant gas'. Accordingly, the reactant gas can be explained as an oxygen-containing gas.

When the step of injecting oxygen-containing gas is completed, a second purge is performed by injecting purge gas into the chamber in which the substrate (S) is loaded. At this time, the purge gas can use the same gas as in the first purge step, and for example, argon (Ar) gas can be used.

When performing the precursor injection step, the first purge step, the oxygen-containing gas injection step, and the second purge step as described above, the steps can be performed while the temperature of the substrate (S) is controlled to 250°C to 450°C. That is, the film formation cycle (CY _f ) is performed while the temperature of the substrate (S) is controlled to 250°C to 450°C. More specifically, the temperature of the susceptor installed inside the chamber of the deposition device is controlled so that the temperature of the substrate (S) supported on the susceptor is controlled to 250°C to 450°C. Then, the film formation cycle (CY _f ) of injecting the precursor, the purge gas, and the oxygen-containing gas into the chamber is performed. As a result, the first ruthenium oxide film (110), which is a ruthenium oxide film, is formed on the substrate (S).

Thereafter, the film formation cycle (CY _f ) including the precursor injection step, the first purge step, the oxygen-containing gas injection step, and the second purge step as described above is repeated multiple times. Accordingly, multiple primary ruthenium oxide films (110) are laminated on the substrate (S) as shown in (c) of Fig. 3.

In (c) of FIG. 3, a plurality of primary ruthenium oxide films (110) are shown separately in order to distinguish the primary ruthenium oxide films (110) formed by a plurality of film formation cycles (CY _f ), but the plurality of stacked primary ruthenium oxide films (110) may be integral.

As described above, when an oxygen-containing gas is sprayed toward the ruthenium film (111), ruthenium (Ru) contained in the ruthenium film (111) reacts with oxygen to form a primary ruthenium oxide film (110), which is a ruthenium oxide film. However, the primary ruthenium oxide film (110) formed in this way has a low oxygen (O) content. To be more specific, the primary ruthenium oxide film (110) may have a low oxygen (O) content compared to the ruthenium (Ru) content, or the ruthenium (Ru) content may be the same as the oxygen (O). In other words, the ratio of the ruthenium (Ru) content and the oxygen (0) content contained in the primary ruthenium oxide film (110) may be 1:1 or less (ruthenium content: oxygen content = 1:1 or less). Here, a ratio of the content of ruthenium (Ru) to that of oxygen (O) of 1:1 may mean that the content of ruthenium (Ru) to that of oxygen (O) is the same, and a ratio of the content of ruthenium (Ru) to that of oxygen (O) of less than 1:1 may mean that the content of oxygen is lower than the content of ruthenium (Ru).

If the content of oxygen contained in the ruthenium oxide film is low, the function of the ruthenium oxide film may be deteriorated. To explain this more specifically, a case in which a ruthenium oxide film (100) is formed between the lower conductive film (10) and the substrate (S) as described in Fig. 1 will be described as an example. Here, the ruthenium oxide film (100) is a diffusion barrier film.

When the content of oxygen contained in the ruthenium oxide film (100) is low, the ruthenium oxide film (100) may not be able to suppress or prevent ruthenium (Ru) contained in the lower conductive film (10) from moving to the substrate (S). That is, the content of oxygen (O) contained in the ruthenium oxide film (100) is low, resulting in a deterioration in the quality as a diffusion barrier film.

Therefore, in the embodiment, the primary ruthenium oxide film (110) formed in the film formation step (P _f ) is exposed to plasma to increase the content of oxygen (O) contained in the primary ruthenium oxide film (110). In other words, the primary ruthenium oxide film (110) is exposed to plasma to form a secondary ruthenium oxide film (100) having an increased content of oxygen compared to the primary ruthenium oxide film (110). At this time, a plasma containing oxygen (oxygen plasma) is formed, and the primary ruthenium oxide film (110) is exposed to oxygen plasma to form a secondary ruthenium oxide film (100) having an increased content of oxygen.

Hereinafter, with reference to FIGS. 2 and 4, the plasma exposure step (P _p ) for forming a secondary ruthenium oxide film (100) will be described.

Referring to FIG. 2, the plasma exposure step (P _p ) includes a step of generating an oxygen-containing plasma by injecting an oxygen-containing gas. That is, the plasma exposure step (P _p ) includes a step of injecting an oxygen-containing gas into the interior of a chamber in which a substrate (S) is loaded or toward the substrate (S) and a step of generating oxygen plasma using the injected oxygen-containing gas. In addition, the step of generating the oxygen plasma may include a step of applying power for plasma generation. At this time, for example, RF (Radio Frequency) power may be applied to at least one of the chamber, the susceptor on which the substrate (S) is placed inside the chamber, and the injector that injects the oxygen-containing gas into the interior of the chamber. In addition, the oxygen-containing gas may include, for example, one or a combination of two or more of oxygen (O ₂ ), ozone (O ₃ ), and nitrous oxide (N ₂ O). In this way, when RF power is applied and the oxygen-containing gas is injected, an oxygen-containing plasma, that is, an oxygen plasma, may be generated inside the chamber. Accordingly, as shown in Fig. 4, the primary ruthenium oxide film (110) formed on the substrate (S) is exposed to oxygen plasma.

When the primary ruthenium oxide film (110) is exposed to oxygen plasma, oxygen (O) contained in the oxygen plasma penetrates into the primary ruthenium oxide film (110). That is, oxygen ions generated when the oxygen plasma is formed penetrate into the primary ruthenium oxide film (110). At this time, compared to not forming oxygen plasma and only spraying oxygen-containing gas, when oxygen plasma is formed, the amount of oxygen penetrating into the primary ruthenium oxide film (110) can be increased. This will be described in more detail as follows. The oxygen contained in the oxygen-containing gas is non-ionized oxygen. However, when the oxygen-containing gas is sprayed to generate plasma, oxygen ions are generated. In addition, the speed at which ionized oxygen (oxygen ions) moves toward the primary ruthenium oxide film (110) is greater than the speed at which non-ionized oxygen moves toward the primary ruthenium oxide film (110). Accordingly, by forming oxygen plasma after forming the primary ruthenium oxide film (110), the content of oxygen contained in the primary ruthenium oxide film (110) can be increased. In addition, compared to simply spraying oxygen-containing gas onto the primary ruthenium oxide film (without generating oxygen plasma) after forming the primary ruthenium oxide film (110), when forming oxygen plasma, the amount of oxygen penetrating into the primary ruthenium oxide film (110) can be effectively increased.

Accordingly, a secondary ruthenium oxide film (100), which is a ruthenium oxide film having an increased oxygen content compared to the primary ruthenium oxide film (110), can be formed. At this time, the secondary ruthenium oxide film (100) may have a higher oxygen (O) content than the ruthenium (Ru) content. In other words, the ratio of the ruthenium (Ru) content to the oxygen (0) content may exceed 1:1 (ruthenium content: oxygen content = exceeding 1:1). More specifically, the ratio of the ruthenium (Ru) content to the oxygen (0) content may be 1:2 or more (ruthenium content: oxygen content = 1:2 or more).

In this way, if the content of oxygen contained in the secondary ruthenium oxide film (100) is high, the function of the secondary ruthenium oxide film (100) can be improved. To explain this in more detail, a case in which a ruthenium oxide film is formed between the lower conductive film (10) and the substrate (S) as described in FIG. 1 will be explained as an example. Here, the ruthenium oxide film (100) is a diffusion barrier film, and is a secondary ruthenium oxide film formed through the processes of FIG. 3 (a) and (b) and FIG. 4. Accordingly, the drawing symbol '100' illustrated in FIG. 1 will be referred to as a 'ruthenium oxide film' and explained.

When the oxygen content of the ruthenium oxide film (100) formed between the lower conductive film (10) and the substrate (S) increases, the ruthenium oxide film (100) can effectively suppress or prevent ruthenium (Ru) contained in the lower conductive film (10) from moving to the substrate (S). That is, as the oxygen (O) content contained in the ruthenium oxide film (100) increases, the function of the ruthenium oxide film (100) as a diffusion barrier film is improved.

And when performing the plasma exposure step (P _p ), the temperature of the substrate (S) may be the same as the temperature in the film formation step (P _f ) described above. In addition, when performing the plasma exposure step (P _p ), the temperature of the substrate (S) may be controlled to have a difference of ±30° C. from the temperature in the film formation step (P _f ). As a more specific example, when performing the plasma exposure step (P _p ), the temperature of the substrate (S) may be controlled to 250° C. to 450° C. At this time, since the method of controlling the temperature of the substrate (S) is the same as the film formation step (P _f ) described above, a description thereof will be omitted.

In this way, even if the temperature of the substrate (S) is controlled to a low temperature of 250°C to 450°C, a ruthenium oxide film with an improved oxygen content can be formed. That is, in the past, the temperature of the substrate was controlled to a high temperature of about 800°C in order to increase the oxygen content of the ruthenium oxide film. On the other hand, in the embodiment, even if the substrate (S) is heated to a low temperature of 250°C to 450°C, a ruthenium oxide film (100) with an improved oxygen content can be formed. This is because, after the primary ruthenium oxide film (110) is formed, the primary ruthenium oxide film (110) is exposed to oxygen plasma. That is, even if the substrate (S) is not heated to a high temperature of about 800°C by exposing the primary ruthenium oxide film (110) to oxygen plasma, oxygen can sufficiently permeate into the primary ruthenium oxide film (110). Therefore, a ruthenium oxide film (100) containing sufficient oxygen can be formed at a low temperature of 250°C to 450°C.

In addition, the ruthenium metal film (10) formed on the lower or upper portion of the ruthenium oxide film (100) is formed at 250° C. to 450° C. Accordingly, the ruthenium oxide film (100) and the ruthenium metal film (10) can be formed in situ. That is, after the ruthenium oxide film (100) is formed inside the chamber of a deposition device, the ruthenium metal film (10) can be formed inside the chamber in which the ruthenium oxide film (100) was formed. Therefore, in laminating the ruthenium oxide film (100) and the ruthenium metal film (10), the process is simplified and there is an effect of saving time.

FIG. 5 is a conceptual diagram for explaining a method for forming a ruthenium oxide film according to a second embodiment of the present invention.

In Fig. 5, 'on' means injecting raw materials or gas for film formation or generating plasma, and 'off' may mean stopping or ending the injection of the raw materials or gas, or may mean not generating plasma.

In the first embodiment described in FIGS. 2 and 3, it was described that an oxygen-containing gas was injected in the film formation step (P _f ) and the plasma exposure step (P _p ). However, the present invention is not limited thereto, and an inert gas may be injected together with the oxygen-containing gas when it is injected in the film formation step (P _f ) and the plasma exposure step (P _p ).

Hereinafter, with reference to FIG. 5, a method for forming a ruthenium oxide film according to a second embodiment of the present invention will be described. At this time, any description overlapping with that of the first embodiment will be omitted or briefly described.

Referring to FIG. 5, a method for forming a ruthenium oxide film according to a second embodiment may include a film forming step (P _f ) of forming a primary ruthenium oxide film (110) and a plasma exposure step (P _p ) of exposing the primary ruthenium oxide film (110) to plasma containing oxygen to form a secondary ruthenium oxide film (100) with an increased oxygen content.

And, the film formation step (P _f ) includes a precursor injection step of forming a ruthenium film (111) by injecting a precursor containing ruthenium (Ru) toward the substrate (S) and a step of forming a primary ruthenium oxide film (110), which is an oxide ruthenium film, by injecting an oxygen-containing gas toward the ruthenium film (111).

In addition, the film formation step (P _f ) may further include at least one of a step of injecting a purge gas between the precursor injection step and the oxygen-containing gas injection step (first purge step) and a step of injecting a purge gas after the oxygen-containing gas injection step is terminated (second purge step). Here, argon (Ar) gas may be used as the purge gas.

In summary, the film formation step (P _f ) according to the second embodiment may include a precursor injection step, a first purge step, an oxygen-containing gas injection step, and a second purge step. In addition, 'precursor injection step - first purge step - oxygen-containing gas injection step - second purge step' may be made into one film formation cycle (CY _f ).

In the method according to the second embodiment, the precursor injection step, the first purge step, and the second purge step are performed in the same manner as in the method described in the first embodiment. Therefore, the description of these steps is omitted.

In the oxygen-containing gas injection step of the film formation step (P _f ) according to the second embodiment, an inert gas is injected together. That is, when the oxygen-containing gas is injected into the ruthenium film (111), an inert gas is injected together. At this time, the inert gas may include one or a combination of two or more gases from among argon (Ar) and helium (He). The reason for injecting the oxygen-containing gas and the inert gas together is that plasma is formed using the oxygen-containing gas and the inert gas in the plasma exposure step (P _p ) performed subsequently.

The specific reason for injecting oxygen-containing gas and inert gas together in the film formation step (P _f ) will be explained again after the plasma exposure step (P _p ) is first explained.

Referring to FIG. 5, the plasma exposure step (P _p ) includes a step of injecting an oxygen-containing gas and an inert gas, and a step of generating plasma using the injected oxygen-containing gas and inert gas. At this time, the inert gas may include one or a combination of two or more of argon (Ar) and helium (He). In this way, in the second embodiment, since plasma is generated by injecting an oxygen-containing gas and an inert gas, the plasma generated at this time is a plasma containing oxygen and an inert element (one or a combination of two or more of Ar and He). Accordingly, the plasma containing oxygen and an inert element may be called a mixed plasma.

The step of generating a mixed plasma using an oxygen-containing gas and an inert gas may be the same as in the first embodiment except that the inert gas is additionally supplied. That is, the step of generating the mixed plasma includes the step of injecting the oxygen-containing gas and the inert gas into the interior of a chamber in which a substrate (S) is loaded or toward the substrate (S), and the step of generating plasma using the injected oxygen-containing gas and inert gas. In addition, the step of generating the plasma may include the step of applying power for plasma generation. At this time, for example, RF (Radio Frequency) power may be applied to at least one of the chamber, the susceptor on which the substrate (S) is placed inside the chamber, and the injection unit that injects the oxygen-containing gas into the interior of the chamber. The oxygen-containing gas may include, for example, one or a combination of two or more of oxygen (O ₂ ), ozone (O ₃ ), and nitrous oxide (N ₂ O). The injection unit may inject a mixture of the oxygen-containing gas and the inert gas. Of course, the injection unit for injecting the oxygen-containing gas and the injection unit for injecting the inert gas may be provided separately, so that the oxygen-containing gas and the inert gas may be injected through separate injection units. When the oxygen-containing gas and the inert gas are injected in this way and RF power is applied, a plasma containing oxygen and an inert element, i.e., a mixed plasma, is generated inside the chamber. Accordingly, the primary ruthenium oxide film (110) formed on the substrate (S) is exposed to the mixed plasma.

When the primary ruthenium oxide film (110) is exposed to the mixed plasma, oxygen (O) penetrates into the primary ruthenium oxide film (110). That is, the oxygen ions generated when the mixed plasma is generated move to and penetrate the primary ruthenium oxide film (110). At this time, by injecting an inert gas together with an oxygen-containing gas to generate plasma, oxygen can be more effectively penetrated into the primary ruthenium oxide film (110). That is, the oxygen content can be more effectively increased to form the secondary ruthenium oxide film (100).

This is because the density of the mixed plasma formed by injecting the oxygen-containing gas and the inert gas together is higher than that of the plasma formed by injecting only the oxygen-containing gas. More specifically, inert elements such as argon (Ar) and helium (He) can be discharged at lower energy than oxygen. Therefore, the density of the mixed plasma formed by injecting the oxygen-containing gas and the inert gas (one or a combination of two or more of argon (Ar) and helium (He)) together is higher than that of the plasma formed by injecting only the oxygen-containing gas. That is, a high-density plasma can be formed by injecting and discharging the oxygen-containing gas and the inert gas. In addition, when the density of the plasma increases, the speed at which the oxygen ions move to the primary ruthenium oxide film (110) can increase, and thus the amount of oxygen ions penetrating into the primary ruthenium oxide film (110) during the same time can increase.

Accordingly, by exposing the primary ruthenium oxide film to the mixed plasma generated by injecting the oxygen-containing gas and the inert gas, the content of oxygen contained in the primary ruthenium oxide film (110) can be more effectively increased. That is, compared to when only the oxygen-containing gas is injected to form the oxygen plasma (the first embodiment), when the oxygen-containing gas and the inert gas are injected to form the mixed plasma (the second embodiment), the amount of oxygen penetrating into the primary ruthenium oxide film (110) can be effectively increased. Accordingly, the oxygen content can be more effectively increased in the second embodiment compared to the first embodiment, thereby forming the secondary ruthenium oxide film (100). In other words, the oxygen content of the ruthenium oxide film (100) can be more effectively increased in the second embodiment compared to the first embodiment.

In this way, in addition to the oxygen-containing gas, an inert gas is additionally injected to form plasma in the plasma exposure step (P _p ). Accordingly, in the second embodiment, when the oxygen-containing gas is injected in the film formation step (P _f ) performed before the plasma exposure step (P _p ), the inert gas is injected together. That is, in the oxygen-containing gas injection step of the film formation step (P _f ), the oxygen-containing gas and the inert gas are injected together. In addition, it is preferable to use the same type of inert gas as the inert gas injected in the film formation step (P _f ) and the plasma exposure step (P _p ). This is to form plasma stably when forming plasma by injecting the oxygen-containing gas and the inert gas in the plasma exposure step (P _p ). For example, in the oxygen-containing gas injection step of the film formation step (P _f ), the inert gas is not injected, but only the oxygen-containing gas is injected. In the plasma exposure step (P _p ) performed thereafter, the oxygen-containing gas and the inert gas are injected together to form plasma. In this case, there is a problem that the plasma energy rapidly increases due to the inert gas. That is, in the film formation stage (P _f ), the inside of the chamber is maintained in a state where there is no inert gas, and when the inside of the chamber is supplied with an inert gas to generate plasma in the plasma exposure stage (P _p ), the plasma energy rapidly increases due to the inert gas, which may generate an unstable plasma. This is because argon (Ar) and helium (He) are easily discharged at lower energies than oxygen.

Therefore, in the film formation step (P _f ) according to the second embodiment, the oxygen-containing gas and the inert gas are injected together in the oxygen-containing gas injection step. Accordingly, plasma can be stably formed in the plasma exposure step (P _p ).

FIG. 6 is a drawing showing a case where a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention is formed on top of a ruthenium metal film. FIG. 7 is a drawing showing a case where a ruthenium oxide (RuO ₂ ) film formed by a method according to embodiments of the present invention is formed between a substrate and a ruthenium metal film, on top of the ruthenium metal film.

In the above-described Fig. 1, the formation of a ruthenium oxide film (100) between a substrate (S) and a ruthenium metal film (10) is described. However, the present invention is not limited thereto, and a ruthenium oxide (RuO ₂ ) film formed by a method according to an embodiment may be formed at various locations.

For example, as illustrated in FIG. 6, a ruthenium oxide film (100) may be formed on top of a ruthenium metal film (10). Here, the ruthenium metal film (10) and the ruthenium oxide film (100) formed on top of the ruthenium metal film (10) may be components of an electrode. That is, the electrode may include the ruthenium metal film (10) and the ruthenium oxide film (100) formed on top of the ruthenium metal film (10).

The ruthenium oxide film (100) formed on the ruthenium metal film (10) increases the work function of the electrode. That is, the ruthenium metal film (10) has a low work function, and the ruthenium oxide film (100) has a higher work function than the ruthenium metal film (10). Accordingly, by forming the ruthenium oxide film (100) on the ruthenium metal film (10), the work function of the electrode can be improved. And as the work function of the electrode is improved, the leakage current can be reduced.

As another example, as illustrated in FIG. 7, a ruthenium oxide film (100) may be formed on each of the lower and upper portions of the ruthenium metal film (10). Here, the ruthenium metal film (10), the ruthenium oxide film (100) formed on the upper and lower portions of the ruthenium metal film (10), may be components of an electrode. That is, the electrode may include the ruthenium metal film (10), the ruthenium oxide film (100) formed on the lower portion of the ruthenium metal film (10), and the ruthenium oxide film (100) formed on the upper portion of the ruthenium metal film (10).

Here, the ruthenium oxide film (100) formed on the lower portion of the ruthenium metal film (10) acts as a diffusion barrier film that suppresses or prevents ruthenium (Ru) of the ruthenium metal film (10) from moving to the substrate (S). In addition, the ruthenium oxide film (100) formed on the upper portion of the ruthenium metal film (10) can improve the work function of the electrode.

According to the method for forming a ruthenium oxide film according to the embodiments, a ruthenium oxide film (100) having a high oxygen content can be formed. That is, after forming a primary ruthenium oxide film (110) by injecting an oxygen-containing gas into a ruthenium film (111) which is a precious metal, oxygen can be easily permeated into the primary ruthenium oxide film (110) by exposing the primary ruthenium oxide film (110) to plasma. That is, the amount of oxygen permeating into the primary ruthenium oxide film (110) can be increased. Accordingly, a secondary ruthenium oxide film (100) having an increased oxygen content compared to the primary ruthenium oxide film (110) can be formed. Accordingly, a ruthenium oxide film (RuO ₂ ) having a higher oxygen content compared to the prior art can be formed, and thereby the quality of the ruthenium oxide film (100) can be improved. That is, the performance of the ruthenium oxide film (100) included in the semiconductor device can be improved.

S: Substrate 111: Ruthenium film
110: Primary ruthenium oxide film 100: Secondary ruthenium oxide film

Claims (13)

A step of forming a ruthenium film by spraying a precursor containing ruthenium (Ru) toward a substrate;
A step of forming a ruthenium oxide film by spraying an oxygen-containing gas onto the ruthenium film; and
A method for forming a ruthenium oxide film, comprising the step of forming plasma and exposing the ruthenium oxide film to plasma. In claim 1,
In forming the above plasma,
A method for forming a ruthenium oxide film by forming plasma using an oxygen-containing gas. In claim 2,
The above oxygen-containing gas is,
A method for forming a ruthenium oxide film comprising one or more gases selected from the group consisting of oxygen (O ₂ ), ozone (O ₃ ), and nitrous oxide (N ₂ O). In claim 2,
The step of forming the plasma includes a step of forming the plasma by additionally using an inert gas in addition to the oxygen-containing gas,
A method for forming a ruthenium oxide film, wherein the above inert gas includes one or a combination of two or more gases, namely argon (Ar) and helium (He). In claim 1,
A method for forming a ruthenium oxide film, wherein the oxygen content of the ruthenium oxide film exposed to the plasma is higher than the oxygen content of the ruthenium oxide film before exposure to the plasma. In claim 1,
A method for forming a ruthenium oxide film, comprising performing a film formation cycle (CY _f ) including the step of forming the ruthenium film and the step of forming a ruthenium oxide film multiple times, and continuously performing the multiple film formation cycles (CY _f ). In claim 6,
A method for forming a ruthenium oxide film, wherein the step of exposing the above ruthenium oxide film to plasma is performed after performing the above film formation cycle (CY _f ) multiple times in succession. In claim 4,
In the step of forming the plasma, the step of forming the plasma by additionally using an inert gas in addition to the oxygen-containing gas is as follows:
A step of spraying an oxygen-containing gas and an inert gas toward the above ruthenium oxide film; and
A step of generating plasma using injected oxygen-containing gas and an inert gas; comprising:
A method for forming a ruthenium oxide film, wherein the oxygen-containing gas and the inert gas are injected so that the flow rate of the oxygen-containing gas is greater than that of the inert gas. In claim 6,
In the above film formation cycle (CY _f ), when injecting oxygen-containing gas, an inert gas is injected together,
A method for forming a ruthenium oxide film, wherein the above inert gas includes one or a combination of two or more gases, namely argon (Ar) and helium (He). In claim 9,
A method for forming a ruthenium oxide film, wherein in the film formation cycle (CY _f ), oxygen-containing gas and inert gas are injected so that the flow rate of the oxygen-containing gas is greater than that of the inert gas. In any one of claims 1 to 10,
A method for forming a ruthenium oxide film, wherein in the step of forming the ruthenium film, the step of forming the ruthenium oxide film, and the step of exposing the plasma, the temperature of the substrate is controlled to 250°C to 450°C. A step of forming a ruthenium metal film on a substrate inside a chamber; and
A step of forming a ruthenium oxide film in situ inside a chamber in which the ruthenium metal film is formed before or after the step of forming the ruthenium metal film;
A method for manufacturing a semiconductor device, wherein the step of forming the ruthenium oxide film is formed by a method for forming a ruthenium oxide film according to any one of claims 1 to 10. In claim 12,
A method for manufacturing a semiconductor device, wherein in the step of forming the ruthenium metal film and the step of forming the ruthenium oxide film, the temperature of the substrate is controlled to 250°C to 450°C.

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