WO2024075547A1

WO2024075547A1 - Ni alloy film and sputtering target material for formation of ni alloy film

Info

Publication number: WO2024075547A1
Application number: PCT/JP2023/034499
Authority: WO
Inventors: 英夫村田; 萌美多久和
Original assignee: 株式会社プロテリアル
Priority date: 2022-10-07
Filing date: 2023-09-22
Publication date: 2024-04-11

Abstract

Provided are: a Ni alloy film that has high oxidation resistance at high temperature even without containing Cr; and a sputtering target material for forming the Ni alloy film.　This Ni alloy film comprises 9.0-25.0 atom% of Al and 1.0-8.0 atom% of V, the balance being Ni and incidental impurities. The total contained amount of Al and V is preferably 11.0-30.0 atom%. The contained amount of Al is preferably 10.0-18.0 atom%. The Ni alloy film can be formed from a sputtering target material having the same composition and having a Curie point that is not higher than room temperature.

Description

Ni alloy film and sputtering target material for forming Ni alloy film

The present invention relates to Ni alloy films with high-temperature oxidation resistance that are used in applications where oxidation resistance at high temperatures is required, such as protective films for internal electrodes of electronic components and oxidation prevention films for equipment components used in semiconductor manufacturing equipment and baking furnaces, and to sputtering target materials for forming such films.

In recent years, Ni, Cu, and their alloys have been used in thin films used for internal electrodes of electronic components that require small size and weight reduction, and there is a demand for thin films that can maintain oxidation resistance even in a film formation process that involves high-temperature heating of 600°C or higher in the atmosphere. Conventionally, Cr films, Ni films, and Ni-Cr alloy films in which Cr is added to Ni have been known as thin films with high oxidation resistance. These thin films are formed by plating or PVD (Physical Vapor Deposition) methods such as vacuum deposition and sputtering.
Furthermore, in the manufacture of semiconductor elements, in order to obtain an insulating protective film made of an oxide, nitride, or the like formed by a CVD (Chemical Vapor Deposition) method, corrosive gases, etc., may be used as the raw material gas, and the components constituting the chamber and device in which the gas is decomposed and deposited in plasma are also required to have oxidation resistance at high temperatures.
Furthermore, oxidation resistance at high temperatures is also required for components such as chambers, adhesion protection plates, and trays in sintering furnaces used in sintering ionic active substances in an oxygen atmosphere, which affect the performance of large-capacity batteries that are essential for mobile products.

Currently, Ni-based alloys are used for equipment components used in CVD equipment and sintering furnaces because they have oxidation resistance at high temperatures and the necessary strength. For example, Patent Document 1 proposes a Ni-based alloy that contains, by mass%, 3.6-4.4% Al, 0.1-2.5% Si, 0.8-4.0% Cr, and one or more of 0.1-1.5% Mn, with the remainder being Ni and unavoidable impurities.

Patent Document 2 also proposes a Ni-based alloy that contains, by mass%, Al: 0.05-2.5%, Si: 0.3-2.5%, Cr: 0.5-3.0%, Mn: 0.5-1.8%, with Si/Cr < 1.1 or less, and the remainder being Ni and unavoidable impurities, and has excellent heat resistance and corrosion resistance.

Patent Document 3 also proposes a component in which a Ni-Al alloy layer is formed by calorizing the surface of a substrate made of pure Ni or a Ni-Cr-Fe alloy.

Patent No. 3814822 Japanese Patent Application Laid-Open No. 2-163336 JP 2012-219369 A

As described above, there is a movement to stop using Cr-containing thin films such as Cr films and Ni-Cr alloy films, which are representative of materials with excellent oxidation resistance, because of the possibility that ionized Cr becomes hexavalent Cr when photoetching electronic components and the environmental impact when discarding electronic components.
On the other hand, a thin film made of pure Ni has excellent moisture resistance, etc., but on the other hand, it has inferior oxidation resistance to a thin film containing Cr. At 400°C, an oxide layer forms on the surface, causing discoloration, and the oxide diffuses into the functional films of electronic components, degrading their characteristics.
Furthermore, since pure Ni is a magnetic material, when magnetron sputtering, a common thin film formation method, is applied, the thickness of the sputtering target material must be thin, which poses the problem that it is difficult to form thin films with high efficiency.

Moreover, in recent years, there has been a demand for improved characteristics of ionic active materials even in large-capacity batteries, and there is concern that Cr contained in the internal components of the CVD equipment and sintering furnaces used in the production of such batteries may be included in the active species, thereby degrading the characteristics.
Furthermore, the above-mentioned calorizing process requires heating the alloy powder and preparations in a sealed container at around 1000° C., which takes time. In addition, the thickness of the coating must be 10 μm or more, and in order to produce a highly accurate component, the surface must be polished or otherwise removed, which is problematic as it requires a large number of steps.

The object of the present invention is to provide a Ni alloy film that has high oxidation resistance at high temperatures even without containing Cr, and a sputtering target material for forming the film.

The inventors conducted extensive research into new alloys that would provide high oxidation resistance at high temperatures. As a result, they discovered that high oxidation resistance at high temperatures could be achieved by incorporating a specified amount of Al and V into Ni, and thus arrived at the present invention.

That is, the present invention relates to a Ni alloy film containing 9.0 to 25.0 atomic % of Al, 1.0 to 8.0 atomic % of V, and the remainder being Ni and unavoidable impurities.
The Ni alloy film of the present invention preferably contains Al and V in a total amount of 11.0 to 30.0 atomic %.
Moreover, the Ni alloy film of the present invention preferably contains 10.0 to 18.0 atomic % of Al.
More preferably, the Ni alloy film of the present invention contains 11.0 to 16.0 atomic % of Al and 2.5 to 3.5 atomic % of V.

The present invention also relates to a sputtering target material for forming a Ni alloy film having a Curie point at or below room temperature, the Ni alloy film containing 9.0 to 25.0 atomic % Al, 1.0 to 8.0 atomic % V, and the remainder being Ni and unavoidable impurities.
The sputtering target material for forming a Ni alloy film of the present invention preferably contains Al and V in a total amount of 11.0 to 30.0 atomic %.
Moreover, the sputtering target material for forming a Ni alloy film preferably contains 10.0 to 18.0 atomic % of Al.
Moreover, the sputtering target material for forming a Ni alloy film of the present invention more preferably contains 11.0 to 16.0 atomic % of Al and 2.5 to 3.5 atomic % of V.

The present invention can provide a Ni alloy film that suppresses surface and internal oxidation of the Ni alloy film itself and exhibits excellent oxidation resistance at high temperatures, even when it does not contain Cr and undergoes a high-temperature heating process of 600°C or more in air. Therefore, the present invention can contribute to the miniaturization and weight reduction of various electronic components, the high integration, and the large capacity of batteries, as well as reducing the environmental impact at the time of disposal.

1 is a schematic cross-sectional view of a Ni alloy film according to the present invention;

An example of a schematic cross-sectional view of the Ni alloy film of the present invention is shown in Fig. 1. The Ni alloy film 2 of the present invention is formed, for example, on the surface of a substrate 1. The Ni alloy film of the present invention is characterized in that it has a thin film thickness and achieves oxidation resistance at high temperatures without containing Cr, which has been an essential additive element in conventional oxidation-resistant alloys.
The "oxidation resistance" can be confirmed by the discoloration of the Ni alloy film caused by surface oxidation when heated in an oxygen-containing atmosphere, and can be quantitatively evaluated, for example, by reflectance. The "internal oxidation" means that oxidation progresses from the surface to the inside of the Ni alloy film.
When the oxidation of the Ni alloy film formed on the surface of the internal electrode of an electronic component or on the surface of a device member progresses and reaches the interface with the internal electrode of the electronic component or the device member, the electrical resistance value may increase in the case of the internal electrode, and the strength of the device member may decrease. In addition, the adhesion of the Ni alloy film may decrease and the film may fall off, resulting in the loss of the oxidation prevention function. For this reason, even if the Ni alloy film is thin, it is necessary to prevent oxidation from progressing to the interface with the internal electrode or the device member, i.e., to suppress internal oxidation.
Here, the "internal oxidation" of the Ni alloy film can be confirmed, for example, by forming a Ni alloy film on a transparent glass substrate and heating it in the atmosphere, and by observing discoloration or loss of metallic color when the Ni alloy film is viewed from the glass surface side, and can also be quantitatively evaluated by reflectance.

The Ni alloy film of the present invention contains 9.0 to 25.0 atomic % of Al, 1.0 to 8.0 atomic % of V, and the remainder being Ni and unavoidable impurities.
Both Al and V are elements that are more easily oxidized than Ni. Among the elements constituting the Ni alloy film of the present invention, Al is the element that is most easily oxidized and is most easily diffused in Ni. When heated in the air, Al diffuses into the surface layer of the thin film to form an oxide layer.
On the other hand, V is an element that is less susceptible to oxidation than Al and diffuses slower in Ni than Al. When V is added alone to Ni, it has the effect of improving the oxidation resistance more than Al at temperatures of 300° C. or less, but it causes internal oxidation to progress as the temperature rises.
When the Ni alloy film of the present invention is heated in the atmosphere, Al, which diffuses quickly and is easily oxidized, forms an oxide layer at the surface, and a V layer, which diffuses slowly and is less likely to oxidize than Al, is formed underneath the oxide layer, thereby suppressing the diffusion of oxygen from the surface.

In the Ni alloy film of the present invention, the Al content is set to 9.0 atomic % or more in order to stably generate an Al oxide layer on the surface layer and suppress internal oxidation. In addition, in order to ensure adhesion to the substrate glass, Si wafer, metal foil, and various metal members, the Al content must be 9.0 atomic % or more.
However, if the Al content exceeds 25.0 atomic %, the effect of suppressing internal oxidation decreases. Therefore, the Al content of the Ni alloy film of the present invention is set to 25.0 atomic % or less. For the same reason as above, the Al content of the Ni alloy film of the present invention is preferably set to 23.0 atomic % or less.

In the Ni alloy film of the present invention, the V content is set to 1.0 atomic % or more in order to obtain the effect of suppressing internal oxidation by generating V between the Al oxide layer and the Ni alloy matrix during heating.
However, if the V content exceeds 8.0 atomic %, the oxidation of V itself is promoted, and the oxidation resistance may decrease. For this reason, the V content of the Ni alloy film of the present invention is set to 8.0 atomic % or less.

The Ni alloy film according to the embodiment of the present invention can fully suppress internal oxidation by making the total content of Al and V 11.0 atomic % or more. On the other hand, by making the total content of Al and V 30.0 atomic %, oxidation resistance is ensured and the formed Ni alloy film can be prevented from becoming brittle. For this reason, it is preferable that the Ni alloy film of the present invention contains a total of 11.0 to 30.0 atomic % of Al and V. Also, for the same reasons as above, it is more preferable that the Ni alloy film of the present invention contains a total of 11.0 to 28.0 atomic % of Al and V.

In the Ni alloy film according to the embodiment of the present invention, the Al content is set to 10.0 atomic % or more or 18.0 atomic % or less, so that discoloration due to surface oxidation of the Ni alloy film itself can be suppressed. Therefore, the Ni alloy film of the present invention preferably contains Al at 10.0 to 18.0 atomic %.
In the Ni alloy film according to the embodiment of the present invention, in order to suppress the surface oxidation of the Ni alloy film itself at high temperatures, it is more preferable that the content of Al is 11.0 to 16.0 atomic % and the content of V is 2.5 to 3.5 atomic %. In order to obtain the above-mentioned oxidation resistance effect at high temperatures, the content of Al is preferably made larger than the content of V, and is preferably made 1.5 times or more the content of V.

In order to ensure the above-mentioned characteristics, the Ni alloy film of the present invention is composed of Ni and unavoidable impurities, with the remainder being other than Al and V. Here, it is preferable that the content of unavoidable impurities is small, and unavoidable impurities such as gas components oxygen, nitrogen and carbon, and transition metals Cr, Fe, Cu, etc. may be included within a range that does not impair the action of the present invention. For example, it is preferable that the gas components oxygen and nitrogen are each 1000 mass ppm or less, carbon is 200 mass ppm or less, and Cr, Fe, Cu are each 200 mass ppm or less, and the purity excluding gas components is 99.9 mass% or more.

In order to form the Ni alloy film of the present invention, a sputtering method using a sputtering target material is suitable. When forming the Ni alloy film, for example, a method of forming the film using a sputtering target having the same composition as the composition of the Ni alloy film, or a method of forming the film by co-sputtering using a sputtering target material consisting of a Ni-Al alloy and a Ni-V alloy can be applied. From the viewpoint of ease of setting sputtering conditions and ease of obtaining a Ni alloy film of a desired composition, it is optimal to form the film by sputtering using a sputtering target having the same composition as the composition of the Ni alloy film. For this reason, the sputtering target material of the present invention contains 9.0 to 25.0 atomic % Al, 1.0 to 8.0 atomic % V, and the remainder is composed of Ni and unavoidable impurities.
For the same reasons as above, the sputtering target material according to the embodiment of the present invention preferably contains Al and V in a total amount of 11.0 to 30.0 atomic %.
Furthermore, for the same reasons as above, the sputtering target material according to the embodiment of the present invention preferably contains 10.0 to 18.0 atomic % of Al.
Furthermore, for the same reasons as above, the sputtering target material according to the embodiment of the present invention more preferably contains 11.0 to 16.0 atomic % Al and 2.5 to 3.5 atomic % V.
In order to ensure the above-mentioned characteristics, the sputtering target material for forming a Ni alloy film of the present invention is composed of Ni and inevitable impurities, except for Al and V. Here, it is preferable that the content of inevitable impurities is small, and inevitable impurities such as oxygen, nitrogen, and carbon, which are gas components, and Cr, Fe, and Cu, which are transition metals, may be contained within a range that does not impair the action of the present invention. For example, it is preferable that the gas components oxygen and nitrogen are each 1000 mass ppm or less, carbon is 200 mass ppm or less, and Cr, Fe, and Cu are each 200 mass ppm or less, and the purity excluding gas components is 99.9 mass% or more.

The sputtering target material of the present invention has a Curie point below room temperature. In order to efficiently form a Ni alloy film in a magnetron sputtering method, the sputtering target material must be nonmagnetic at room temperature, that is, have a Curie point below room temperature. Note that "room temperature" here refers to the range of 5 to 35°C as specified in JIS Z 8703.
Ni, which is the main constituent element of the Ni alloy film of the present invention, is a magnetic material, and in order to set the Curie point below room temperature, it is important to alloy Ni with Al and V, which are non-magnetic elements that make up the composition of the Ni alloy film of the present invention.
This sputtering target material can be produced, for example, by a method of machining an ingot produced by melting raw materials adjusted to a predetermined composition, or by a powder sintering method. In the powder sintering method, it is possible to produce alloy powder by a gas atomizing method and use it as the raw material powder, or to use a mixed powder in which multiple alloy powders or pure metal powders are mixed to achieve the final composition of the present invention as the raw material powder.

In order to obtain a Ni alloy film, a sputtering target material was prepared.
After weighing the raw materials to obtain a non-magnetic binary composition of Ni-13.0 atomic % Al, Ni-7.0 atomic % V, Ni-10.0 atomic % V, Ni-10.0 atomic % Cr, and Ni-10.0 atomic % Si, and a ternary composition of Ni-14.0 atomic % Al-3.5 atomic % V, ingots were produced by melting and casting in a vacuum melting furnace. The sputtering target material of Ni-50.0 atomic % Al was obtained by producing an ingot by sintering alloy powder of the same composition.
Each of the above ingots was processed into a plate shape by hot plastic working, and after heat treatment for removing distortion, it was machined to produce a disk-shaped sputtering target material having a diameter of 100 mm and a thickness of 5 mm.
When a SmCo magnet was brought close to each of the sputtering target materials obtained above, the magnet was not attracted, and it was confirmed that the sputtering target materials were non-magnetic at room temperature.

Each sputtering target material was brazed to a copper backing plate with In, and then attached to a sputtering device (model number: CS-200) manufactured by ULVAC, Inc. A sputtering test was carried out under conditions of an Ar atmosphere, a pressure of 0.5 Pa, and a power of 500 W. It was found that all of the sputtering target materials were able to be sputtered.
The sputtering target materials obtained above were combined and various Ni alloy films were formed on a glass substrate (Corning Eagle-XG) with a thickness of 500 nm by a co-sputtering method for simultaneous film formation. The Ni alloy films formed on polyimide films under the same conditions as above were dissolved in a dissolving solution containing hydrofluoric acid, and the component composition was analyzed by ICP emission spectrometry.

The reflectance of each of the Ni alloy films prepared above was measured after heat treatment in the atmosphere at 600° C. and 700° C. The reflectance was measured using a spectrophotometric colorimeter CM-2500d manufactured by Konica Minolta.
The internal oxidation was evaluated by the reflectance and color when the Ni alloy film was viewed from the transparent glass side after heating at 700°C. If the film had a metallic color, the internal oxidation was suppressed, and if the film was discolored, the entire film was oxidized, and it was judged that internal oxidation had occurred. The measurement results are shown in Table 1.

The Ni alloy films of Samples No. 1 to No. 10, which are examples of the present invention and contain a predetermined amount of Al and V, were observed from the glass surface side after heating at 700°C. It was confirmed that the Ni alloy films maintained their metallic color, had a high reflectance of 50% or more, and had suppressed internal oxidation.
In addition, sample No. 11, which is a comparative example containing Cr, also had a metallic color on the glass surface side after heating at 700° C. In addition, the Ni alloy film on the glass surface side of sample No. 12, which does not contain Cr, sample No. 13, which has a low Al content, and sample No. 14, was discolored without a metallic color, and the reflectance was also greatly reduced, and it was confirmed that the entire film was oxidized due to internal oxidation.

The reflectance of the Ni alloy film surface side at the time of film formation was 54 to 58% in all cases. In addition, the Ni alloy film of sample No. 11 containing Cr as a comparative example had a reflectance lowered to less than 20% after heating at 600°C and 700°C, and it was confirmed that the oxidation resistance of the Ni alloy film surface was low.
In contrast, it was confirmed that Sample No. 1 to Sample No. 10, which contain Ni with Al and V within the range of the present invention, have a high reflectance exceeding 25% even after heating at 700°C, and that the oxidation resistance of the Ni alloy film surface is also high. Among them, it was confirmed that the Ni alloy films of Samples No. 3, 4, 6, 7, and 8, which are examples of the present invention, have a high reflectance of 55% or more even after heating at 700°C, and further have excellent high-temperature oxidation resistance.

Using the Ni-14.0 atomic % Al-3.5 atomic % V and Ni-10.0 atomic % Cr target materials prepared in Example 1, an Ni alloy film having a film thickness of 100 to 500 nm was formed on a glass substrate in an Ar atmosphere under a pressure of 0.5 Pa and a power of 500 W by adjusting the film formation time in the same manner as in Example 1. In addition, a pure Ni target material was prepared and formed on a glass substrate to obtain a pure Ni film as a comparative example.
Each of the Ni alloy films and the pure Ni film obtained above was subjected to a heat treatment at 700° C. in the atmosphere, and then the reflectance was measured in the same manner as in Example 1. The results are shown in Table 2.

As shown in Table 2, the reflectance of the pure Ni film, which is a comparative example, could not be measured because the entire film was oxidized and peeled off. Also, in the case of the Ni-10.0 atomic % Cr film containing Cr, which is a comparative example, the reflectance on the glass surface side was high at 50% or more when the film thickness was 150 nm or more, suppressing internal oxidation, but the reflectance on the Ni alloy film surface side dropped to 30% or less when the film thickness was in the range of 100 to 500 nm after heating at 700°C, confirming that the oxidation resistance was poor.
In contrast, the Ni-14.0 atomic % Al-3.5 atomic % V example of the present invention, like Ni-10.0 atomic % Cr, has a reflectance on the glass surface side that exceeds 50% at a film thickness of 150 nm or more, suppressing internal oxidation, while the reflectance on the Ni alloy film surface side exceeds 30% at a film thickness of 150 nm or more, with the reflectance increasing as the film thickness increases, and it has been confirmed that it has better oxidation resistance than Ni-10.0 atomic % Cr.
As described above, although the Ni alloy of the present invention does not contain Cr, it can suppress internal oxidation in the same manner as Ni-10 atomic % Cr, and has a high reflectance even on the Ni alloy film side, confirming that it is a Ni alloy film with high oxidation resistance.

1 Substrate 2 Ni alloy film

Claims

A Ni alloy film containing 9.0-25.0 atomic % Al, 1.0-8.0 atomic % V, and the remainder Ni and unavoidable impurities.
The Ni alloy film according to claim 1, containing a total of 11.0 to 30.0 atomic percent Al and V.
The Ni alloy film according to claim 1 or claim 2, containing 10.0 to 18.0 atomic percent Al.
The Ni alloy film according to claim 1, containing 11.0 to 16.0 atomic % Al and 2.5 to 3.5 atomic % V.
A sputtering target material for forming Ni alloy films that contains 9.0-25.0 atomic % Al, 1.0-8.0 atomic % V, with the remainder being Ni and unavoidable impurities, and has a Curie point below room temperature.
The sputtering target material for forming Ni alloy films according to claim 5, containing a total of 11.0 to 30.0 atomic % of Al and V.
The sputtering target material for forming Ni alloy films according to claim 5 or 6, containing 10.0 to 18.0 atomic % Al.
6. The sputtering target material for forming a Ni alloy film according to claim 5, containing 11.0 to 16.0 atomic % of Al and 2.5 to 3.5 atomic % of V.