JP2022162663A - Sputtering target and production method of sputtering target - Google Patents

Abstract

To provide a sputtering target composed of a complex tissue of a metallic phase and an oxide phase and capable of suppressing occurrence of cracks in the sputtering target even when DC sputtering is performed with a high power flux density.SOLUTION: A sputtering target 10 is composed of a complex tissue of an oxide phase 11 and a metallic phase 12. The tissue is such that the metallic phase 12 is dispersed like islands within a parent phase comprising the oxide phase 11, where an outer circumferential length per unit area of the metallic phase 12 is 17 μm/μm2 or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a sputtering target used when forming a thin film containing an oxide, and a method for producing this sputtering target.

Oxide films made of metal oxides have a wide range of properties, and are widely used in various fields according to the properties of each oxide film.
For example, in Patent Document 1, as a metal element, one or two of Mo and In and one or two of Cu and Fe are used as main components, and a part of these metal elements or The use of an oxide film consisting entirely of oxide as a low-reflectance film with low visible light reflectance is described.

Here, when forming the oxide film described above, a sputtering method using a sputtering target made of oxide (hereinafter referred to as an oxide sputtering target) is widely used. Since an oxide sputtering target has a high resistance value and a low electrical conductivity, RF sputtering (high frequency sputtering) is usually used. However, RF sputtering has a problem that the sputtering rate is low and the film cannot be formed efficiently.

Therefore, Patent Document 1 proposes a sputtering target having a composite structure of a metal phase and an oxide phase.
In a sputtering target having a composite structure of a metal phase and an oxide phase, electrical conductivity is ensured and a DC sputtering method can be applied. This makes it possible to form an oxide film efficiently.

Patent Document 2 discloses a magnetic thin film having a CoPt-based alloy-oxide granular structure as an oxide-containing thin film. Patent Document 2 describes a sputtering target for forming this magnetic thin film, comprising at least one selected from Cu and Ni, Pt, and a metal phase consisting of the balance Co and inevitable impurities, and at least B ₂ O ₃ and an oxide phase containing

JP 2020-033583 A WO 2020/027235 pamphlet

By the way, recently, from the viewpoint of improving production efficiency, it is required to further improve the throughput of film formation by increasing the power density during sputtering film formation.
Here, when the power density is increased and DC sputtering is performed, the amount of heat generated on the sputtering surface increases, and the temperature on the backing member side becomes low. In a sputtering target composed of a composite structure of a metal phase and an oxide phase, the amount of heat generated in the oxide phase is large, so temperature differences are likely to occur within the sputtering target, and the sputtering target may crack due to thermal shock. was there.

The present invention has been made in view of the above-mentioned circumstances, and is composed of a composite structure of a metal phase and an oxide phase. It is an object of the present invention to provide a sputtering target capable of suppressing the generation of sputum, and a method for manufacturing this sputtering target.

In order to solve the above problems, the sputtering target of the present invention is a sputtering target comprising a composite structure of an oxide phase and a metal phase, wherein the metal phase is an island in the matrix phase comprising the oxide phase. It is characterized in that the metal phase has a structure dispersed in a shape, and the outer circumference per unit area of the metal phase is 17 μm/μm ² or more.

According to the sputtering target having the above-described configuration, the composite structure of the oxide phase and the metal phase ensures sufficient conductivity, and a thin film containing an oxide can be formed by DC sputtering. can.
Since the perimeter length per unit area of the metal phase is 17 μm/μm ² or more, the contact area between the oxide phase and the metal phase is ensured, and the heat of the oxide phase is transferred to the metal phase side. It can be efficiently transmitted, the temperature in the sputtering target is easily uniform, and even when DC sputtering is performed at a high power density, it is possible to suppress the occurrence of cracks in the sputtering target due to thermal shock. .

Here, in the sputtering target of the present invention, the average particle size of the metal phase is preferably 80 μm or less.
In this case, since the average particle size of the metal phase is set to 80 μm or less, it is possible to suppress the occurrence of abnormal discharge during DC sputtering, and more stably form a thin film containing an oxide. .

Moreover, the sputtering target of the present invention preferably has a specific resistance value of 0.01 Ω·cm or less.
In this case, since the specific resistance value is 0.01 Ω cm or less and the conductivity is ensured, the occurrence of abnormal discharge during DC sputtering can be suppressed, and the thin film containing the oxide can be stably formed. A film can be formed.

In the sputtering target of the present invention, the metal phase includes Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au, Ru , Rh, and Pd.
In this case, the metal phase is selected from Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au, Ru, Rh, Pd Since it is composed of a metal containing one or more metals, the metal phase has excellent thermal conductivity, and it is possible to efficiently transfer the heat of the oxide phase to the metal phase side, and the temperature inside the sputtering target is more likely to be uniform, and even when DC sputtering is performed at a high power density, cracking of the sputtering target due to thermal shock can be suppressed.

Further, in the sputtering target of the present invention, the oxide phase is an oxide containing one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn and Ba. may be composed of
In this case, the oxide phase is composed of an oxide containing one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn, and Ba. When the thermal conductivity of the material phase is secured, the heat of the oxide phase can be efficiently transferred to the metal phase side, the temperature in the sputtering target can be more uniform, and DC sputtering is performed at a high power density. Even so, it is possible to suppress the occurrence of cracks in the sputtering target due to thermal shock.

A sputtering target manufacturing method of the present invention is a sputtering target manufacturing method for manufacturing the sputtering target described above, wherein the surface area per unit volume is 1000000 m ² /m ³ or more and the average particle diameter is 75 μm or less. a metal powder producing step of obtaining a metal powder having the above-mentioned value; a mixing step of mixing the metal powder and the oxide powder to obtain a sintering raw material powder; and sintering the sintering raw material powder to obtain a sintered body. and a sintering step.

According to the method for producing a sputtering target having this configuration, a metal powder having a surface area per unit volume of 1000000 m ² /m ³ or more and an average particle diameter of 75 μm or less is produced, and the metal powder and the oxidized Since the sintering raw material powder obtained by mixing with the material powder is sintered, it has a structure in which the metal phase is dispersed in islands in the mother phase composed of the oxide phase, and the metal phase per unit area A sputtering target having an outer circumference of 17 μm/μm ² or more can be manufactured.

According to the present invention, a sputtering target composed of a composite structure of a metal phase and an oxide phase and capable of suppressing cracking of the sputtering target even when DC sputtering is performed at a high power density, And, it becomes possible to provide a method for manufacturing this sputtering target.

1 is a schematic diagram of a structure of a sputtering target according to an embodiment of the present invention; FIG. 1 is a schematic explanatory diagram of a sputtering target having a flat plate shape, which is a sputtering target according to an embodiment of the present invention; FIG. 1 is a schematic explanatory diagram of a disk-shaped sputtering target, which is a sputtering target according to an embodiment of the present invention. FIG. 1 is a schematic illustration of a cylindrical sputtering target, which is a sputtering target according to an embodiment of the present invention; FIG. It is a flow figure showing a manufacturing method of a sputtering target concerning one embodiment of the present invention. 1 is a structure observation photograph of Inventive Example 1. FIG.

A sputtering target and a method for manufacturing a sputtering target according to an embodiment of the present invention will be described below.
The sputtering target according to this embodiment is used when forming a thin film containing an oxide by DC sputtering.

As shown in FIG. 1, the sputtering target 10 according to the present embodiment has a composite structure of an oxide phase 11 and a metal phase 12, and the metal phase 12 is an island in the matrix phase composed of the oxide phase 11. It is considered to be a distributed organization.
In the sputtering target 10 according to this embodiment, the perimeter length per unit area of the metal phase 12 is 17 μm/μm ² or more.

Here, in the sputtering target 10 according to this embodiment, the average particle size of the metal phase 12 is preferably 80 μm or less.
Moreover, in the sputtering target 10 according to the present embodiment, the specific resistance value is preferably 0.01 Ω·cm or less.

Furthermore, in the sputtering target 10 according to the present embodiment, the oxide phase 11 is one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn, and Ba. It is preferably composed of an oxide containing
Moreover, in the sputtering target 10 according to the present embodiment, the metal phase 12 includes Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, It is preferably composed of a metal containing one or more selected from Au, Ru, Rh, and Pd.

The sputtering target 10 of the present embodiment may be a rectangular flat plate type sputtering target having a rectangular sputtering surface as shown in FIG.
Further, the sputtering target 10 of the present embodiment may be a disk-shaped sputtering target having a circular sputtering surface as shown in FIG.
Furthermore, as shown in FIG. 4, the sputtering target 10 of this embodiment may be a cylindrical sputtering target having a cylindrical sputtering surface.

Below, in the sputtering target 10 according to the present embodiment, the perimeter length per unit area of the metal phase 12, the average particle size of the metal phase 12, the specific resistance value, the composition of the metal phase, and the composition of the oxide phase, The reason for specifying as above is shown.

(peripheral length per unit area of metal phase)
In the sputtering target 10 according to the present embodiment, when observing its surface or cross section, the metal phase 12 is dispersed in islands in the mother phase of the oxide phase 11, and the outer circumference per unit area of the metal phase 12 As the length increases, the contact area between the oxide phase 11 and the metal phase 12 increases, the heat of the oxide phase 11 can be efficiently transferred to the metal phase 12 side, and the temperature of the sputtering target 10 can be made uniform. become possible. If the perimeter length can be set to 17 μm/μm ² or more, the area of the interface between the oxide phase 11 and the metal phase 12 can be increased, and heat transfer can be improved.
Therefore, in the sputtering target 10 of the present embodiment, the perimeter length per unit area of the metal phases 12 dispersed like islands in the mother phase of the oxide phase 11 is set to 17 μm/μm ² or more. .
In order to more efficiently transmit the heat of the oxide phase to the metal phase side, the perimeter length per unit area of the metal phase 12 is preferably 20 μm/μm ² or more, more preferably 25 μm/μm ² or more. It is more preferable that The upper limit of the perimeter length per unit area of the metal phase 12 is not particularly limited, but is preferably 45 μm/μm ² or less, more preferably 50 μm/μm ² or less.

(Average particle size of metal phase)
In the sputtering target 10 according to the present embodiment, when the average particle size of the metal phase 12 is suppressed to 80 μm or less, the concentration of electric charges during sputtering film formation is suppressed, and the occurrence of abnormal discharge during DC sputtering is suppressed. can be suppressed, and a thin film containing an oxide can be stably formed.
In order to further suppress the occurrence of abnormal discharge during sputtering film formation, the average particle size of the metal phase 12 is more preferably 75 μm or less, more preferably 70 μm or less. The lower limit of the average particle size of the metal phase 12 is not particularly limited, but it is more preferably 5 μm or more, more preferably 10 μm or more.

(Resistivity)
In the sputtering target 10 according to the present embodiment, when the specific resistance value is 0.01 Ω cm or less, the conductivity is ensured, the occurrence of abnormal discharge during DC sputtering can be suppressed, and oxides are removed. It is possible to stably deposit a thin film containing
In order to further suppress the occurrence of abnormal discharge during sputtering film formation, the specific resistance value of the sputtering target 10 according to the present embodiment is more preferably 0.005 Ω·cm or less, and more preferably 0.001 Ω·cm. More preferably:

(Composition of metal phase)
In the sputtering target 10 according to this embodiment, the metal phase 12 is Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au, Ru, When composed of a metal containing one or more selected from Rh and Pd, the metal phase 12 has excellent thermal conductivity, and the heat generated in the oxide phase 11 during sputtering is absorbed by the metal. It can be efficiently transmitted to the phase 12 side, and the temperature of the sputtering target 10 can be made more uniform.

(Composition of oxide phase)
In the sputtering target 10 according to the present embodiment, the oxide phase 11 is an oxide containing one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn and Ba. In this case, thermal conductivity is ensured in the oxide phase 11, heat generated in the oxide phase 11 can be efficiently transferred to the metal phase 12 side, and the temperature of the sputtering target 10 can be made more uniform. become possible.

Next, a method for manufacturing the sputtering target 10 according to this embodiment will be described with reference to FIG.

(Metal powder production step S01)
First, metal powder to be used as raw material powder is prepared.
In the metal powder production step S01, a metal raw material having a predetermined composition is prepared, crushed using a ball mill, and classified by sieving after crushing to obtain a surface area per unit volume of 1,000,000 m ² /m A metal powder having an average particle size of ³ or more and an average particle size of 75 μm or less is obtained. In addition, in this embodiment, the processing time for crushing the metal raw material using the ball mill is preferably 10 hours or longer. Further, the treatment time is more preferably 12 hours or longer, more preferably 30 hours or longer.
In this embodiment, the metal powder includes Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au, Ru, Rh, Pd. It is preferably composed of a metal containing one or more selected from.

(Mixing step S02)
Next, the metal powder and the oxide powder obtained as described above are mixed to obtain a raw material powder for sintering.
In this embodiment, the oxide powder is composed of an oxide containing one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn and Ba. preferably. Also, the average particle size of the oxide powder is preferably in the range of 5 μm or more and 40 μm or less.
Here, the mixing method is not particularly limited, and various methods such as a rocking mixer, a Henschel mixer, and a ball mill can be appropriately selected.

(Sintering step S03)
Next, the obtained sintering raw material powder is sintered to obtain a sintered body. The sintering method is not particularly limited, and is fired after molding by hot pressing (uniaxial pressing), HIP (hot isostatic pressing), or CIP (cold isostatic pressing). etc. can be applied.

(Machining step S04)
The sputtering target 10 of the present embodiment is obtained by machining the sintered body obtained as described above.

According to the sputtering target 10 according to the present embodiment configured as described above, since it is made of a composite structure of the oxide phase 11 and the metal phase 12, the conductivity is ensured, and the DC Thin films can be deposited by sputtering.
Since the perimeter length per unit area of the metal phase 12 is 17 μm/μm ² or more, the contact area between the oxide phase 11 and the metal phase 12 is secured, and the heat of the oxide phase 11 is dissipated. It can be efficiently transmitted to the metal phase side, the temperature in the sputtering target 10 can be easily uniformed, and cracking of the sputtering target 10 due to thermal shock is suppressed even when DC sputtering is performed at a high power density. It becomes possible to

In the sputtering target 10 of the present embodiment, when the average particle size of the metal phase 12 is 80 μm or less, the average particle size of the metal phase 12 is sufficiently small to suppress the occurrence of abnormal discharge during DC sputtering. It is possible to perform DC sputtering more stably.

In addition, in the sputtering target 10 of the present embodiment, when the specific resistance value is 0.01 Ω cm or less, the conductivity is sufficiently ensured, and the occurrence of abnormal discharge during DC sputtering can be suppressed. It is possible to perform DC sputtering more stably.

Furthermore, in the sputtering target 10 of the present embodiment, the metal phase 12 contains Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au , Ru, Rh, and Pd, the metal phase 12 has excellent thermal conductivity, and the heat of the oxide phase 11 is efficiently transferred to the metal phase. 12 side, the temperature in the sputtering target 10 is easily uniformized, and even when DC sputtering is performed at a high power density, cracking of the sputtering target 10 due to thermal shock is further suppressed. becomes possible.

Further, in the sputtering target 10 of the present embodiment, the oxide phase 11 contains one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn and Ba. When it is composed of an oxide, the thermal conductivity of the oxide phase 11 is ensured, the heat of the oxide phase 11 can be efficiently transferred to the metal phase 12 side, and the temperature in the sputtering target 10 can be reduced. is easily uniformized, and even when DC sputtering is performed at a high power density, cracking of the sputtering target 10 due to thermal shock can be further suppressed.

According to the sputtering target manufacturing method of the present embodiment, the metal powder production step S01 for obtaining metal powder having a surface area per unit volume of 1,000,000 m ² /m ³ or more and an average particle size of 75 μm or less. a mixing step S02 of mixing the metal powder and the oxide powder to obtain a sintering raw material powder; and a sintering step S03 of obtaining a sintered body by sintering the obtained sintering raw material powder. Therefore, the sputtering target 10 has a structure in which the metal phase 12 is dispersed in the form of islands in the matrix phase composed of the oxide phase 11, and the outer peripheral length per unit area of the metal phase 12 is 17 μm/μm ² or more. can be manufactured.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical idea of the invention.

Below, the results of the evaluation test that evaluated the sputtering target and the method for manufacturing the sputtering target of the present invention described above will be described.

Metal powders shown in Table 1 are prepared. Here, the metal powder was ball-milled under the conditions shown in Table 1, and the surface area per unit volume and the average particle size were shown in Table 1. The surface area and average particle size per unit volume of the metal powder were evaluated as follows.

(Surface area per unit volume of metal powder)
The specific surface area (cm ² /g) of the metal powder was measured according to JIS Z 8830:2013.
By multiplying the measured specific surface area by the specific gravity (g/cm ³ ) of the metal, the surface area per unit volume of the metal powder was calculated.

(Average particle size of metal powder)
Using SEM (JSM6460LV manufactured by JEOL Ltd.)-EDX (JED-2300 (III) energy dispersive X-ray spectrometer manufactured by JEOL Ltd.), SEM-EDX images of 600 μm × 475 μm are randomly observed in three fields of view of the sample. A photograph was taken, the diameter of a circle inscribed in the metal powder was measured, and the median value (D50) was determined using WinROOF.

The metal powder described above and the oxide powder shown in Table 1 were weighed so as to have the contents shown in Table 1, and mixed to obtain a raw material powder for sintering.
Then, the sintering raw material powder was sintered to obtain a sintered body.
By machining this sintered body, a rectangular flat sputtering target of 278 mm×126 mm×5 mmt was manufactured.

Regarding the obtained sputtering target, the specific resistance value, the outer circumference length per unit area of the metal phase, the average particle size of the metal phase, the maximum power density before cracking occurred during sputtering, and the number of abnormal discharge occurrences were determined as follows. evaluated.

(Resistivity)
The specific resistance value was measured by the four-probe method using a low resistivity meter (Loresta-GP) manufactured by Mitsubishi Chemical Corporation. Measurement was performed at a temperature of 23±5° C. and a humidity of 50±20%.
Specific resistance values were measured at four corner portions and five central portions of the sputtering surface, and the maximum values are listed in Table 2.

(peripheral length per unit area of metal phase)
An observation sample is collected from the sputtering target, and an SEM (JSM6460LV manufactured by JEOL Ltd.)-EDX (JED-2300 (III) energy dispersive X-ray analyzer manufactured by JEOL Ltd.) is used to obtain an SEM-EDX image of 600 μm × 475 μm. The observation sample was randomly photographed in three fields of view, and the total length of the outer circumference of the metallic phase (μm) and the total length of the area of the metallic phase (μm ² ) were measured. The perimeter length per unit area of the metal phase was calculated by dividing by the sum of . The total of each numerical value was calculated from the three images, and the outer circumference length was calculated using it.

(Average particle size of metal phase)
Using SEM (JSM6460LV manufactured by JEOL Ltd.)-EDX (JED-2300 (III) energy dispersive X-ray spectrometer manufactured by JEOL Ltd.), SEM-EDX images of 600 μm × 475 μm were randomly taken in three fields of view from the observation sample. Then, the diameter of the circle inscribed in the metal phase was measured, and the median value was obtained using WinROOF.

(Maximum power density before cracking occurs during sputtering)
Using a sputtering apparatus, the power density (W/cm ² ) was increased stepwise from 1 W/cm ² to 1 W/cm ² at an Ar pressure of 0.4 MPa, and sputtering was performed for 1 hour at each power density. did. After that, the presence or absence of cracks (cracks with a length of 2 mm or more) in the sputtering target was visually confirmed. The power density immediately before cracking of each sputtering target was confirmed is shown in Table 2 as the maximum power density.

(Number of abnormal discharge occurrences)
Sputter film formation was performed for 1 hour under the conditions shown below, and the number of abnormal discharges was counted using an arc counting function provided in a DC power supply (HPK06Z-SW6 manufactured by Kyosan Seisakusho).
Ar gas pressure: 0.4 Pa
Power density: maximum power density according to paragraph 0051

In Comparative Example 1-3, in which the perimeter length per unit area of the metal phase was less than 17 μm/μm ² , the maximum power density was 8 W/cm ² or less, and sputtering film formation could be performed at a high power density. could not.

On the other hand, in Inventive Example 1-7, in which the perimeter per unit area of the metal phase was 17 μm/μm ² or more, the maximum power density was 13 W/cm ² or more, which is a relatively high power density. We were able to perform sputtering film deposition. Here, FIG. 6 shows an example of the structure observation result of Example 1 of the present invention. It is confirmed that the metal phase composed of Cu is dispersed in the form of islands in the oxide phase composed of In oxide.

In addition, in Examples 3 and 6 of the present invention in which the average particle size of the metal phase exceeded 80 μm, the number of abnormal discharges increased.
Moreover, in Examples 4 and 7 of the present invention, in which the specific resistance exceeds 0.01 Ω·cm, the number of abnormal discharges increased.

From the above, according to the example of the present invention, it is possible to suppress the occurrence of cracks in the sputtering target, which is composed of a composite structure of a metal phase and an oxide phase, and even when DC sputtering is performed at a high power density. It was confirmed that it is possible to provide a sputtering target capable of

10 sputtering target 11 oxide phase 12 metal phase

Claims (6)

A sputtering target comprising a composite structure of an oxide phase and a metal phase,
The metal phase has a structure in which the metal phase is dispersed in the form of islands in the matrix phase composed of the oxide phase,
A sputtering target, wherein the perimeter length per unit area of the metal phase is 17 μm/μm ² or more. 2. The sputtering target according to claim 1, wherein the metal phase has an average particle size of 80 [mu]m or less. 3. The sputtering target according to claim 1, wherein a specific resistance value is 0.01 Ω·cm or less. The metal phase is one selected from Zn, Al, Sn, Fe, Cr, W, Cu, Ni, Pt, Mg, Mo, Be, Nb, Co, Ta, Hf, Au, Ru, Rh, Pd or 4. The sputtering target according to any one of claims 1 to 3, comprising a metal containing two or more kinds of metals. The oxide phase is composed of an oxide containing one or more selected from Zn, Y, Mo, In, Al, Cu, Mn, Gd, W, Sn and Ba. A sputtering target according to any one of claims 1 to 4. A sputtering target manufacturing method for manufacturing the sputtering target according to any one of claims 1 to 5,
obtaining a metal powder having a surface area per unit volume of 1000000 m ² /m ³ or more and an average particle size of 75 μm or less;
a step of mixing the metal powder and the oxide powder to obtain a raw material powder for sintering;
a step of sintering the sintering raw material powder to obtain a sintered body;
A method for manufacturing a sputtering target, comprising:

Images