TWI632248B - Aluminum alloy sputtering target, aluminum alloy film, display device and input device - Google Patents

Abstract

The present invention relates to an aluminum alloy sputtering target which contains more than 6 at% and less than 17 at% of Cu, and the balance contains Al and unavoidable impurities. According to the present invention, it is possible to provide an aluminum alloy sputtering target which contributes to an improvement in film formation rate and is excellent in manufacturability of a target.

Description

Aluminum alloy sputtering target, aluminum alloy film, display device and input device

The present invention relates to a sputtering target for forming an electrode or an insulating film or the like (hereinafter also referred to as "target"). In detail, the present invention relates to a liquid crystal display, organic electroluminescence. (OEL: Organic Electro-Luminescence) A sputtering target formed of an electrode used in an input device such as a display device or a touch panel.

Aluminum alloys are widely used in the field of display devices such as liquid crystal displays due to their low electrical resistivity and ease of processing, and are used in materials such as wiring films, electrode films, and reflective electrode films.

For example, an active matrix type liquid crystal display includes a thin film transistor (TFT: Thin Film Transistor) as a switching element, and various aluminum alloy thin films such as a pure Al thin film or an Al-Nd alloy are usually used for the wiring material.

A sputtering method using a sputtering target is usually employed in the formation of an aluminum alloy film.

Sputtering has the advantage of forming a film of the same composition as the target. In particular, the aluminum alloy film formed by the sputtering method can dissolve the alloy element which is not dissolved in an equilibrium state, thereby exhibiting excellent performance as a film, and therefore, the sputtering method is industrially effective film production. The method is progressing and developing a sputtering target as a raw material thereof.

In recent years, in order to improve the productivity of the aluminum alloy film, the film formation rate has been increased in comparison with the prior art. For example, the methods of Patent Document 1 and Patent Document 2 have been proposed. Patent Document 1 discloses a sputtering target material comprising aluminum or an aluminum alloy, and a (111) crystal orientation content ratio measured by an X-ray diffraction method on a sputtering surface thereof is 20% or more. In the example of the patent document 1, in the Al-Si-based alloy in which Si was added to Al, the film formation rate was improved by setting the crystal orientation to the (111) plane.

Further, Patent Document 2 discloses an aluminum-based alloy sputtering target characterized by containing Ta. In the examples of Patent Document 2, an Al-Ta alloy in which 1.5 atom% of Ta is added to Al and the film formation rate is 1.6 times or more with respect to pure Al is shown. [Prior Art Literature] [Special License Document]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 6-128737 (Patent Document 2) Japanese Patent Laid-Open Publication No. 2012-224942

However, in the method of setting the (111) crystal orientation content ratio to 20% or more in aluminum or aluminum alloy described in Patent Document 1, it is required to further improve the film formation rate from the viewpoint of productivity.

In addition, when the Ta-containing aluminum alloy sputtering target described in Patent Document 2 is added, when 1 atom% or more of Ta is added, the nozzle is clogged at the time of injection molding, and the target productivity is lowered. Therefore, considering the manufacturability of the target, it is difficult to further increase the film formation rate.

Accordingly, an object of the present invention is to provide an aluminum alloy sputtering target which contributes to an improvement in film formation rate and is excellent in manufacturability of a target.

Previously, the effect of increasing the film formation rate of Cu has not been paid attention to, but the inventors have found that the aluminum alloy sputtering target containing Ta is higher than 6 atom% and 17 atom% or less. The addition of an aluminum alloy sputtering target to which Cu is added has a higher film formation rate and at the same time has excellent manufacturability, thereby completing the present invention.

That is, the present invention is as described in the following [1] to [9].

[1] An aluminum alloy sputtering target material containing more than 6 at% and 17 at% or less of Cu, and the balance containing Al and unavoidable impurities.

[2] The aluminum alloy sputtering target according to [1], which further contains 0.1 atom% to 5.5 atom% of a rare earth element.

[3] The aluminum alloy sputtering target according to [2], wherein the rare earth element is selected from the group consisting of Nd, La, Y, Sc, Gd, Dy, Lu, Ce, Pr, and Tb. At least one of them.

[4] An aluminum alloy film formed by using the aluminum alloy sputtering target according to any one of [1] to [3].

[5] The aluminum alloy thin film according to [4], which is an aluminum nitride film or an aluminum oxide film formed by a reactive sputtering method.

[6] A display device comprising the aluminum alloy thin film according to [4].

[7] A display device comprising the aluminum alloy thin film according to [5].

[8] An input device comprising the aluminum alloy thin film according to [4].

[9] An input device comprising the aluminum alloy thin film according to [5].

Since the aluminum alloy sputtering target of the present invention contains Cu in an amount of more than 6 at% and not more than 17 at%, the film formation rate can be improved as compared with the Al-Ta alloy, and it is also excellent in manufacturability.

The present invention will be described in detail below, but the present invention is not limited to the embodiments described below, and may be arbitrarily modified without departing from the spirit and scope of the invention. In addition, "atomic%" has the same meaning as "at%".

The aluminum alloy sputtering target of the present invention is an aluminum alloy sputtering target for sputtering an aluminum alloy thin film, and is characterized in that it contains more than 6 atomic % and 17 atomic % or less of Cu, and the remainder contains Al and Inevitable impurities.

The aluminum alloy sputtering target refers to a sputtering target in which pure Al and Al containing an alloy element are mainly used. The content of Cu in the aluminum alloy sputtering target of the present invention exceeds 6 atom%, preferably 7 atom% or more. By setting the content of Cu to more than 6 at%, excellent manufacturability and high film formation rate can be obtained.

Further, the content of Cu is 17 atom% or less, and in order to further suppress the decrease in the critical reduction ratio of the fracture, it is preferably 12 atom% or less. By setting the content of Cu to 17 at% or less, it is possible to suppress a decrease in the yield in the SF (Spray Forming) step and the reduction in the critical reduction ratio in the forging step, and it is possible to prevent a sharp drop in the manufacturability of the target. .

As an unavoidable impurity, for example, an element which is inevitably mixed in a production process or the like, such as Fe, Si, or the like, is preferably contained in a total amount of 0.03 mass% or less, more preferably 0.03 mass% or less. It is 0.01% by mass or less.

The aluminum alloy sputtering target of the present invention further contains a rare earth element as a second additive element to form an Al-Cu-X alloy (X: rare earth element), thereby excellent in manufacturability and no addition of rare earth elements. The film formation rate can be further increased compared to when.

The content of the rare earth element is preferably 0.1 atom% or more, more preferably 2 atom% or more. By setting the content of the rare earth element to 0.1 atom% or more, the effect by the second additive element can be obtained. Further, the content of the rare earth element is preferably 5.5 atom% or less, more preferably 3.7 atom% or less. By setting the content of the rare earth element to 5.5 atom% or less, it is possible to suppress a decrease in the yield in the SF step and a decrease in the critical reduction ratio of the fracture, and it is possible to prevent deterioration in the manufacturability of the target.

The term "rare earth element" refers to an element in which a lanthanoid element (a total of 15 elements from the atomic number of 57 to a atomic number of 71 to the total of 15 elements) is added to the lanthanide element (the elemental periodic table is added with Sc (钪) and Y (钇)). Group. From the viewpoint of increasing the film formation rate, among the rare earth elements, Nd, La, Y, Sc, Gd, Dy, Lu, Ce, Pr, and Tb are preferable, and Nd is more preferable. One of these may be used or may be used arbitrarily in combination of two or more.

The aluminum alloy film of the present invention is preferably formed by sputtering using the sputtering target of the present invention. The reason is that, according to the sputtering method, a film having excellent in-plane uniformity of a component or a film thickness can be easily formed.

As a method of forming an aluminum alloy thin film by a sputtering method, for example, a method containing Cu of more than 6 at% and 17 at% or less and containing the Al and unavoidable impurities and having a desired alloy thin film is used. A method of forming an aluminum alloy sputtering target having the same composition by a magnetron sputtering method, a method of forming the target by a reactive sputtering method, and the like.

It is preferable to use a reactive sputtering method from the viewpoints of productivity and film quality control. Examples of the aluminum alloy film formed by the reactive sputtering method include an aluminum nitride film and an aluminum oxide film.

The conditions of the reactive sputtering method are, for example, appropriately controlled depending on the type of the aluminum alloy to be used, and it is preferred to carry out the following control.・Substrate temperature: room temperature to 400 °C ・Sputter power: 100 W to 500 W ・Ultimate vacuum: 1 ́10 ^-5 Torr or less

The shape of the target includes any shape (for example, a square plate shape, a circular plate shape, a circular plate shape, or the like) which is processed according to the shape or structure of the sputtering apparatus.

Examples of the method for producing the target include a dissolution casting method, a powder sintering method, a method of producing an ingot containing an aluminum-based alloy by a spray molding method, and a preform for producing an aluminum-based alloy ( A method obtained by densifying the preform by a densification means after obtaining the final intermediate before the dense body.

The present invention also includes a display device and an input device including the aluminum alloy film. As an aspect of the display device, for example, the aluminum alloy film is used for a source-drain electrode of a thin film transistor and a display device in which a drain electrode is directly connected to a transparent conductive film. Moreover, as an aspect of the input device, for example, an input device including an input unit in the display device such as a touch panel is exemplified. [Examples]

In the following, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the examples, and may be modified within the scope of the present invention, and the modifications are all included in the present invention. Technical scope.

(1) Preparation of Sputtering Target After injection molding, 110 kg of aluminum alloy as a raw material for dissolving was dissolved to obtain an aluminum alloy preform, and then the weight of the preform was measured by a weight meter to calculate the yield at the time of injection molding. (SF yield). The obtained preform was sealed to a capsule and degassed, and densified by a hot isostatic pressing (HIP) apparatus. Then, after heating at 450 ° C, the reduction ratio was calculated in the forging step using the following formula. Reduction rate: (L _{0 -} L ₁ ) / L ₀ ́100 (%) Initial sample length: L ₀ , sample length after pressing: L ₁ In addition, when the film is pressed, it is confirmed by visual inspection that the sample will be broken. It was confirmed that the reduction ratio before the rupture was set as the rupture critical reduction ratio.

Regarding the SF yield, the evaluation was performed by the following criteria. SF yield = preform weight / dissolved material (110 kg) ́100 (%) ○: 40% or more △: more than 30% to less than 40% ́: 30% or less

Regarding the critical reduction ratio of the fracture, the evaluation was performed by the following criteria. ○: 50% or more △: more than 30% to less than 50% ́: 30% or less

(2) Film formation using an alkali-free glass plate (plate thickness 0.7 mm, diameter 4 吋) as a transparent substrate, by direct current (DC) magnetron sputtering method, the surface shown in Table 1 The Al alloy is formed into a film. When the film is formed, the environment in the cavity before film formation is temporarily adjusted to the ultimate vacuum degree: 3 ́10 ^-6 Torr, and then a disk shape having a diameter of 4 组成 having the same composition as the metal film is used. The target was plated and sputtered under the following conditions.

(sputtering conditions) ・Argon gas pressure: 2 mTorr ・Argon gas flow rate: 19 sccm ・Sputtering power: 500 W ・Substrate temperature: room temperature ・Film formation temperature: room temperature ・ Film formation time: 10 minutes

(3) Calculation of film formation rate The thickness of the produced film was measured by a stylus type step meter (Alpha Step 250 manufactured by Nippon Tokushu Sokki, NTS). The thickness was measured by measuring three points from the center of the film in the radial direction, and the average value was defined as the film thickness (Å). The film thickness obtained in this manner was divided by the sputtering time (s) to calculate an average film formation rate (Å/s).

In Example 1 to be described later, the average film formation rate of the aluminum alloy was divided by the average Al film formation rate to determine the film formation rate ratio. Although not shown in Table 1, the film formation rate ratio (film formation rate: relative to pure Al) of Al-1 atom% Ta was 1.5 times. Therefore, the case where the film formation rate ratio exceeds the deposition rate ratio of Al-1 atom% Ta, that is, 1.50, is a range in which the effect of improving the film formation rate due to alloying is confirmed. Further, in Example 2, the average film formation rate of the Al-7 atom% Cu-rare earth alloy was divided by the aluminum alloy containing 7 atom% of Cu to determine the film formation rate ratio.

(4) Comprehensive judgment The comprehensive judgment is evaluated by the following criteria. ○: The film formation rate ratio was 1.50 or more, and at least one of the SF yield and the fracture critical reduction ratio was ○. △: The film formation rate ratio was 1.50 or more, and neither the SF yield nor the rupture critical reduction ratio was ○. ́: The film formation rate ratio is 1.50 or more, but at least one of the SF yield and the rupture critical reduction ratio is ́, or the film formation rate ratio is 1.50 or less.

<Example 1> An Al film having the composition shown in Table 1 was formed into a film, and the film formation rate and manufacturability were evaluated. The results are shown in Table 1. In Table 1, Examples 1 to 4 are Examples, and Examples 5 to 8 are Comparative Examples.

[Table 1]

As shown in Table 1, in the pure Al, Al-1 atom% Cu to Al-17 atom% Cu of Examples 1 to 7, the film formation rate was confirmed as the amount of Cu added increased. The Al-17 atomic % Cu of 4 was increased to 2.12 times relative to pure Al.

In the Al-6.1 at% Cu to Al-17 at% Cu of Examples 1 to 4, a film formation rate faster than Al-1 at% Ta (1.50 times) was observed, and the film formation rate was improved. On the other hand, the film formation rate ratio of pure Al, Al-1 atom% Cu, and Al-5 atom% Cu shown in Examples 5 to 8 is equal to or less than that of Al-1 atom% Ta, and the film formation rate is not improved. . From this result, it is understood that the film formation rate is improved by setting the content of Cu in the aluminum alloy sputtering target to more than 6 atom%.

In addition, as shown in the example 4, when the content of Cu exceeds 12 atom%, the critical reduction ratio of the fracture is lowered. Therefore, by setting the content of Cu to 12 atom% or less, the decrease in the critical reduction ratio of the fracture can be suppressed. . As a factor which causes a decrease in the critical reduction ratio of the fracture accompanying an increase in the content of Cu, it is considered that as the amount of the added element increases, the metal compound in the target increases, and thus the hardness of the target increases, and as a result, cracking occurs.

In addition, as shown in Example 8, in the range where the amount of addition of Cu is more than that of Al-17 at% Cu, cracking frequently occurs in the processing step at the time of production of the target, and productivity is deteriorated. From this result, it is understood that the productivity of the target can be improved by setting the content of Cu to 17 atom% or less.

<Example 2> A rare earth element in which an increase in the film formation rate was confirmed by adding a small amount to the Al-Cu alloy extracted in Example 1 was made into an Al-Cu-X alloy (X: rare earth element). Thereby, the effect of further film formation rate enhancement was confirmed. The results of evaluating the film formation rate and manufacturability are shown in Table 2. In Table 2, Examples 9 to 24 are examples, and Examples 25 and 26 are comparative examples.

[Table 2]

As shown in Table 2, in the Al-7 atom% Cu-rare earth alloy of Examples 9 to 24, the film formation rate ratio with respect to the Al-7 atom% Cu alloy was 1.01 to 1.78, and the film formation rate was confirmed. Improve the role. On the other hand, in the case of Example 25, the addition amount of the rare earth element was too small to be 0.05 atom%, and therefore, the effect of increasing the film formation rate by the second additive element was not confirmed. Further, in Example 26, the addition amount of the rare earth element was too large to be 6 atom%, and therefore, the fracture critical reduction ratio did not reach the standard.

According to the results, it is understood that by further adding a rare earth element of 0.1 at% to 5.5 at% as the second additive element, the deposition rate of the aluminum alloy sputtering target can be improved.

The present invention has been described in detail with reference to the specific embodiments thereof. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. In addition, the present application is based on a Japanese patent application (Japanese Patent Application No. Hei.

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Claims (8)

An aluminum alloy sputtering target material containing more than 6 atomic % and 17 atomic % or less of Cu, the remainder comprising Al and unavoidable impurities, and the aluminum alloy sputtering target further contains 2 atomic % or more and 5.5 atomic % The following rare earth elements. The aluminum alloy sputtering target according to claim 1, wherein the rare earth element is selected from the group consisting of Nd, La, Y, Sc, Gd, Dy, Lu, Ce, Pr, and Tb. At least one of them. An aluminum alloy film formed by using an aluminum alloy sputtering target material as described in claim 1 or 2. The aluminum alloy thin film according to claim 3, which is an aluminum nitride thin film or an aluminum oxide thin film formed by a reactive sputtering method. A display device comprising the aluminum alloy film according to item 3 of the patent application. A display device comprising the aluminum alloy film according to item 4 of the patent application. An input device comprising the aluminum alloy film according to item 3 of the patent application. An input device comprising the aluminum alloy film according to item 4 of the patent application.