TWI849237B - Sputtering target - Google Patents

Abstract

The present invention discloses a sputtering target provided with a structure in which target members having different thicknesses are adjacent with each other via a gap, and the sputtering target can prevent the constituent materials of the substrate from being mixed into the film.

The present invention proposes a sputtering target, which is provided with a plurality of target members, a substrate with a step and a protective member provided between the target member and the substrate, wherein the target members arranged at the step portion of the substrate with the step have different thicknesses from each other, and among the target member with different thickness an end of the target member with the smaller thickness has a part that is more protruding than the step portion of the substrate (this protruding part is called “protrusion”).

Description

Sputtering target

The present invention relates to a sputter plating target having a structure configured by providing a gap between adjacent target components.

Sputtering is a technique of thin film formation technology. As an example, the following method can be cited: an inert gas such as Ar (argon) is introduced into a vacuum, and a negative voltage is applied to the target component to generate a glow discharge, and the inert gas is plasmatized and ionized by the glow discharge to form gas ions, and the gas ions collide with the surface of the target component at high speed, so that particles of the film-forming material constituting the target component are ejected, and the particles are attached and accumulated on the surface of the substrate to form a thin film, thereby forming a dense and strong thin film on the surface of the substrate.

This sputtering method can form films on materials that are difficult to form films on, such as high-melting-point metals, alloys, and ceramics, using vacuum evaporation methods. It can also form large-area films with high precision, so it is widely used in the manufacture of various electronic parts such as information devices, AV devices, and home appliances. Among them, ITO, IZO, IGZO, and other thin films formed by sputtering are widely used as electrodes for display components centered on liquid crystal displays, touch panels, and EL displays.

In recent years, as display panels have become larger, there is a need to form thin films with large areas, and therefore target components also need to be larger. However, it is difficult to form a target component used for sputtering with a large-area target component. Therefore, a method is adopted in which a target component is divided into a plurality of target components and a plurality of target components are bonded on a substrate to form a large-area sputtering target (for example, refer to patent document 1).

In this way, in order to avoid collision of target components due to thermal expansion, a target divided into multiple target components (also called a "divided sputtering target") is generally arranged on a substrate so that a gap can be formed between adjacent target components, and the substrate is bonded to each target component using low-melting-point solder with good thermal conductivity such as In-based or Sn-based metals.

Furthermore, this split sputtering target is configured by setting a gap between adjacent target components, so the substrate is exposed in the gap. During sputtering, the substrate is also sputtered very slightly, and there is a concern that the components of the substrate are mixed into the thin film to be formed. Therefore, there is a proposal to set a protective component in the gap between adjacent target components to prevent the substrate from being exposed in the gap (for example, refer to patent documents 2 and 3).

[Prior patent literature]

[Patent Literature]

Patent document 1: Japanese Patent Publication No. 2005-232580

Patent document 2: International Publication No. 2012/063523 brochure

Patent document 3: International Publication No. 2012/063524

In the case of magnetron sputtering, the distribution of ion current density on the magnetron cathode is not uniform due to the influence of the non-uniform magnetic field strength. Therefore, the distribution of sputtering rate becomes non-uniform, and the consumption of the target component sometimes varies from place to place. Specifically, in the case of a flat target component, for example, the sputtering rate at the end tends to be higher, so sometimes the consumption of the end of the target component becomes particularly fast.

Therefore, in the past, as shown in Figures 6 and 7, the thickness of the target component 3 at the end is made larger than that of the target component 3 at the center, thereby extending the life of the target component at the end and reducing the replacement frequency of the target. In addition, in this case, in order to make the sputtering surface flat, the thickness of the substrate 2 arranged on the inner side of the target component 3 is generally different across the step portion 2C formed by the vertical surface.

However, in this case, the step portion 2C of the substrate 2 is exposed through the gap 4, so when the thin film is formed by sputtering, the step portion 2C of the substrate 2 is sputtered, so that the constituent material of the substrate 2 (such as Cu, etc.) is mixed into the formed thin film through the gap 4.

The present invention provides a new sputter plating target, which has target components adjacent to each other with a gap and different thicknesses, and can prevent the constituent material of the substrate from being mixed into the film.

The present invention proposes a sputtering target, which has a plurality of target components and a substrate with a step difference. The sputtering target has a protective component disposed between the target component and the substrate, and disposed at the step difference portion of the substrate with a step difference. The target components have different thicknesses, and among the target components with different thicknesses, the end of the target component with a smaller thickness has a portion protruding more than the step difference portion of the substrate (the protruding portion is referred to as a "protruding portion").

The sputter plating target proposed in the present invention is to make the target member with a smaller thickness, that is, the end of the target member on the step portion side of the substrate protrude more than the step portion of the substrate, thereby preventing the constituent material of the substrate (such as Cu, etc.) from being mixed into the thin film even if the step portion is not covered by the protective member.

1: Sputtering target

2,2A,2B: Base material

2C: Step difference

3,3A,3B: Target components

3Aa: protrusion

4: Gap

5: Protective components

6: Joining materials

7: Thermal conductive layer

FIG1 is a plan view showing an example of a sputter plating target of the present invention.

FIG2 is a partial cross-sectional oblique view schematically showing a configuration example of a sputter plating target of the present invention.

Figure 3 is a partial enlarged cross-sectional view showing a portion of Figure 2.

FIG4 is a partially enlarged cross-sectional view schematically showing a variation of the sputter plating target of the present invention.

FIG5 is an example of a sputtering target of the present invention, showing a sputtering target made in an embodiment, (A) is a plan view thereof, (B) is a cross-sectional view thereof, and (C) is an enlarged cross-sectional view of a portion thereof (the portion surrounded by the dotted line in (B)).

FIG6 is a partial cross-sectional oblique view schematically showing a configuration example of a known sputtering target.

Figure 7 is a partial enlarged cross-sectional view showing a portion of Figure 6.

Next, the present invention is described based on examples of implementation. However, the present invention is not limited to the implementation described below.

〈Original Splash Plated Target〉

A sputtering target (referred to as "the present sputtering target") 1 of one embodiment of the present invention is as shown in FIGS. 1 to 3. A plurality of target components 3, 3... are provided on the sputtering surface side (also referred to as "surface side") of a substrate 2, and a gap 4 is provided between adjacent target components 3, 3. The substrate 2 and the target component 3 are bonded by a bonding material.

Furthermore, a protective member 5 is provided between the target member 3 and the substrate 2 along the gap 4 between the target members 3 and 3.

Furthermore, the sputtering target 1 has: portions where target members adjacent to each other with a gap 4 are the same in thickness, such as target members 3 (3A) and 3 (3A); and portions where target members adjacent to each other with a gap 4 are different in thickness, such as target members 3 (3A) and 3 (3B).

The surfaces of the plurality of target components 3, 3... are arranged at the same height, that is, arranged in a flat state.

The sputtering target 1 is in the shape of a flat plate. However, the overall shape of the sputtering target of the present invention can be arbitrary, for example, it can be cylindrical.

In the case where the sputtering target of the present invention is cylindrical, for example, it is sufficient to penetrate multiple cylindrical target components 3, 3 on the surface side of the cylindrical substrate 2, and to set a gap 4 between adjacent target components 3, 3 and arrange them in multiple stages in the cylindrical axis direction. In addition, multiple curved target components 3 that are cut longitudinally in the cylindrical axis direction can be arranged in parallel in the circumferential direction toward the outer side of the cylindrical substrate 2. However, it is not limited to this structure.

(Structure of the portions of adjacent target components 3, 3 having the same thickness)

The adjacent target components 3, 3 have the same thickness. The adjacent target components 3 (3A), 3 (3A) are arranged with a gap 4 between them on the sputtering surface side of the uniform thickness portion of the substrate 2, and a protective component 5 is arranged between the target component 3 and the substrate 2 along the gap 4, and the target component 3 and the substrate 2 are bonded by a bonding material 6.

The width of the gap 4 between adjacent target components 3 (3A), 3 (3A), that is, the distance between the opposite front ends of adjacent target components 3A, 3A is preferably 0.1mm to 0.6mm.

If the width of the gap 4 is greater than 0.1 mm, it is ideal because it can prevent the target components 3 (3A), 3 (3A) from colliding and breaking due to thermal expansion. If the distance is greater than 0.6 mm, the target components cannot be fully sputtered, which will cause abnormalities in film properties, so it is better to be less than 0.6 mm.

From this point of view, the width of the gap 4 is preferably 0.1 mm or more, preferably 0.15 mm or more, and more preferably 0.2 mm or more. On the other hand, it is preferably 0.6 mm or less, preferably 0.5 mm or less, and more preferably 0.4 mm or less.

In addition, the sputtering target 1 is not necessarily required to have portions where the thicknesses of adjacent target components 3 (3A) and 3 (3B) are the same as each other, as long as the adjacent target components 3 (3A) and 3 (3A) have portions where the thicknesses are different from each other, as shown in FIG. 5, for example.

(Structure of the portion where the thickness of adjacent target components 3, 3 is different from each other)

On the other hand, in the portion where the thickness of the adjacent target components 3, 3 is different, as shown in FIG3, the thickness of the adjacent target components 3 (3A) and 3 (3B) separated by the gap 4 is different from each other, and the thickness of the substrate 2 on the inner side of these target components 3 (3A) and 3 (3B) is also different due to the step 2C. That is, the thickness of the substrate 2 is different due to the step 2C in such a way that the height of the sputtered surface of the adjacent target components 3A and 3B becomes the same. In addition, the target component 3A with a smaller thickness is configured to protrude further toward the other target component 3B side than the step 2C of the substrate 2 in the gap 4 (this portion is referred to as "protruding portion 3Aa").

The thicker portion of the substrate 2 is referred to as "substrate 2A", and the thinner portion separated by the step portion 2C is referred to as "substrate 2B".

That is, the sputtering target 1 has a substrate 2 with different thicknesses due to the step portion 2C, and a plurality of target components 3, 3... layered on the surface side of the substrate 2. The target component 3A is layered on the thicker substrate 2A, and the end of the target component 3A is arranged to protrude from the step portion 2C. The target component 3B arranged with the gap 4 between it and the target component 3A is arranged so that its surface forms the same height as the surface of the target component 3A.

Furthermore, a protective member 5 is arranged on the surface of the substrate 2A, starting from the rising surface of the step portion 2C, in a manner that spans a predetermined width from the edge of the inner surface side of the target member 3A, and is configured so that the surface of the substrate 2 is not exposed.

Although the rising surface of the step portion 2C is exposed, the protrusion 3Aa of the target member 3A will play the role of an eaves, so the magnetron or even gas ions that penetrate from the gap 4 are not easy to collide with the rising surface, and the rising surface of the step portion 2C is not easy to be sputtered.

The portion where the thickness of the adjacent target components 3, 3 is different is as shown in FIG2, and is usually provided at the end region of the sputtering target 1. Since the sputtering rate is higher in the end region of the target component and the target component tends to be consumed faster, by increasing the thickness of the target component in the end region, the target life can be extended and the replacement frequency of the sputtering target can be reduced.

However, the location where the portions of the adjacent target components 3, 3 with different thicknesses are provided may be any location.

The protrusion width x of the protrusion 3Aa, that is, the distance x between the step portion 2C of the substrate 2A and the front end of the protrusion 3Aa of the target component 3A, and that is, the distance x between the step portion 2C of the substrate 2A and the gap 4, is preferably 1 mm to 20 mm.

If the protrusion width x is greater than 1 mm, the position of the gap 4 will be far away from the step portion 2C of the substrate 2A, and the step portion 2C is not easily sputtered, which is preferred. On the other hand, if the protrusion width x is less than 20 mm, it is preferred to prevent the protrusion 3Aa from being locally heated by sputtering due to the reduced cooling efficiency of the protrusion 3Aa, and to prevent the occurrence of abnormalities such as cracks or arcs.

From this point of view, the protruding amplitude x is preferably 1 mm or more, preferably 3 mm or more, preferably 4 mm or more, and preferably 5 mm or more. On the other hand, it is preferably 20 mm or less, preferably 15 mm or less, and preferably 12 mm or less.

The width x of the protrusion 3Aa protruding more than the step portion 2C is smaller than the distance between the end 3Ba of the target member 3B with a larger thickness and the step portion 2C of the substrate 2A.

Furthermore, the protrusion width x of the protrusion 3Aa is preferably adjustable according to the height z of the step portion 2C in the substrate 2, and is preferably 30 to 500% of the height z of the step portion 2C, wherein 50% or more or 400% or less, and 100% or more or 300% or less is even more preferred.

The width y of the gap 4 between adjacent target components 3A and 3B, that is, the distance y between the end of the protrusion 3Aa in the target component 3A and the end 3Ba of the target component 3B, is preferably 0.1mm to 0.6mm.

If the width y of the gap 4 between the target components 3A and 3B is greater than 0.1 mm, it is better to prevent the target components 3A and 3B from colliding and breaking due to thermal expansion. If the distance is greater than 0.6 mm, the target components will not be fully sputtered, which will cause abnormalities in film properties, so it is better to be less than 0.6 mm.

From this point of view, the width y of the gap 4 between the target components 3A and 3B is preferably 0.1 mm or more, preferably 0.15 mm or more, and more preferably 0.2 mm or more. On the other hand, it is preferably 0.6 mm or less, preferably 0.5 mm or less, and more preferably 0.4 mm or less.

In addition, the structure of the portion where the thickness of the adjacent target components 3, 3 is different from each other is the same as the structure of the portion where the thickness of the adjacent target components 3, 3 is the same at points other than the above.

The thickness of the target component 3 (including target components 3A and 3B) is not particularly limited, but is usually 2 mm to 20 mm, preferably 4 mm or more or 14 mm or less.

(Thermal conductive layer 7)

Furthermore, it is preferred that at least a heat-conducting layer 7 made of a material having a higher thermal conductivity than the target member 3A is provided on the inner surface of the protruding portion 3Aa of the target member 3A. Furthermore, it is preferred that the heat-conducting layer 7 is formed only on the inner surface of the protruding portion 3Aa.

By providing a heat-conducting layer 7 made of a material with high thermal conductivity on the inner surface of the protrusion 3Aa, a cooling effect can be provided to suppress the temperature rise of the protrusion 3Aa during sputtering, and as a result, the occurrence of cracks or arcs can be suppressed, and the discoloration of the protrusion 3Aa can be suppressed. By the way, the protrusion 3Aa is considered to be the only part with the possibility of temperature rise.

At this time, when the target component 3A is made of ceramic, materials with higher thermal conductivity than the target component 3A include indium, various metals, alloys, etc. Among them, the bonding material 6 that bonds the substrate 2 to the target component 3 usually uses a material with high thermal conductivity such as indium, so it is better to also apply the bonding material 6 on the inner surface of the protrusion 3Aa to form a heat conductive layer 7 composed of the bonding material 6.

(Substrate 2)

The substrate 2 can be in a plate or cylindrical shape. However, it is not limited to these shapes.

As long as the substrate 2 has a thicker portion (substrate 2A) and a thinner portion (substrate 2B) separated by the step portion 2C, it can be a unitary body composed of one component in the thickness direction, or a plurality of components can be stacked in the thickness direction to form the step portion 2C.

For example, a portion of a component may be cut off, and a thicker portion (substrate 2A) and a thinner portion (substrate 2B) may be provided across the step portion 2C.

In addition, other components can be stacked on one component to provide a thicker portion (substrate 2A) and a thinner portion (substrate 2B) separated by a step 2C.

The thickness of the substrate 2 is not particularly limited.

On the other hand, the thickness of the thinner portion (substrate 2B) is preferably determined by the thickness of the target components 3A and 3B so that the sputtered surfaces of the target components 3A and 3B have the same height. In other words, it is preferable that the sum of the thickness of the target component 3A and the thickness of the substrate 2A is the same as the sum of the thickness of the target component 3B and the thickness of the substrate 2.

The material of the substrate 2 can be any single metal such as Ti, SUS or Cu or an alloy thereof. However, it is not limited to these.

〈Target component 3〉

The target member 3 may be in a plate or cylindrical shape. However, it is not limited to these shapes.

In addition, the difference in thickness between target components 3A and 3B is preferably determined according to the specifications of the sputtering equipment. It can be appropriately selected according to the difference in sputtering rate caused by the magnetic force distribution of the magnets installed on the inner surface of the target, but it is usually better to be 30% to 100% of the target component 3A. If the difference is too small relative to the difference in sputtering rate, the replacement frequency cannot be effectively reduced. If it is too large, the distance between the target and the substrate becomes smaller, and sometimes the desired film quality cannot be obtained.

The target component 3 is not particularly limited to the material. For example, it can include any one or more metals or oxides of Cu, Al, In, Sn, Ti, Ba, Ca, Zn, Mg, Ge, Y, La, Al, Si, Ga, and W (the oxide is also referred to as "ceramic").

Examples of the oxide include In-Sn-O, In-Ti-O, In-Ga-Zn-O, Ga-Zn-O, In-Zn-O, In-WO, and In-Zn-WO. , Zn-O, Sn-Ba-O, Sn-Zn-O, Sn-Ti-O, Sn-Ca-O, Sn-Mg-O, Zn-Mg-O, Zn-Ge-O, Zn-Ca -O, Zn-Sn-Ge-O, Cu ₂ O, CuAlO ₂ , CuGaO ₂ , CuInO ₂ , etc.

(Protective component 5)

The protective member 5 is arranged in the following manner: along the gap 4 between the adjacent target members 3, 3, between the target member 3 and the substrate 2, and covering the surface of the substrate 2 exposed in the gap 4.

Since the protective member 5 covers the exposed surface of the substrate 2, it can prevent the surface of the substrate 2 from being sputtered in the gap 4 during sputtering, so that the constituent material of the substrate 2 is mixed into the film to be formed.

As the top view shape of the protective member 5, for example, a rectangular shape, a strip shape, a cross strip shape, a lattice frame shape, etc. can be cited. However, it is not limited to these top view shapes.

Furthermore, the protective member 5 may also be L-shaped as a cross-sectional shape in order to cover the step portion 2C, as shown in FIG. 4 .

The thickness of the protective member 5 is not particularly limited. However, from the perspective of processing, it is preferably 100 μm or more, preferably 200 μm or more, and more preferably 300 μm or more. On the other hand, from the perspective of the thickness of the bonding layer, it is preferably 1000 μm or less, preferably 900 μm or less, and more preferably 800 μm or less.

The protective member 5 may be a single-layer structure or a multi-layer structure formed by stacking two or more layers in the thickness direction.

The material of the protective member 5 when it is a single-layer structure and the material of the surface layer when it is a multi-layer structure are preferably made of a material that will not cause adverse effects even if mixed into the thin film to be formed, or a material that can suppress spattering.

As a material that will not cause adverse effects even if mixed into the thin film to be formed, for example, all or part of the elements constituting the composition of the target member 3, an alloy or oxide containing these elements, etc. can be used.

On the other hand, as a material that can suppress the spattering phenomenon, for example, a material having a larger volume resistivity than the target component 3, that is, a high-resistance material can be used as a material for the gap configuration component. When using such a high-resistance material as a material for the gap configuration component, it is preferred that the volume resistivity (Ω‧cm) of the high-resistance material has a value of 10 times or more of the volume resistivity of the target component 3.

As specific examples of the material of the protective member 5 when it is a single-layer structure and the material of the surface layer when it is a multi-layer structure, the metal material constituting the target member 3, or the ceramic material, or the polymer material, or a composite material of two or more of these can be cited.

At this time, the ceramic material is preferably a ceramic material having the same composition as the target member 3, or a ceramic material partially composed of the same material as the target member 3, or a ceramic material having high volume resistance such as _ZrO2 , _{Al2O3 , etc.} If the ceramic material has high volume resistance, it is possible to suppress the plasma from entering the divided portion during sputtering, and the sputtering of Zr or Al can be effectively prevented.

Here, as for the metal material constituting the target component 3, for example, if the target component 3 is IGZO (In-Ga-Zn-O), any one or more metal materials of In, Zn and Ga can be used, and if the target component 3 is IZO (In-Zn-O), any metal material of In or Zn can be used.

Examples of the ceramic material include materials composed of oxides or nitrides of any one or more of In, Zn, Al, _Ga , Zr, Ti, Sn, and Mg. Specifically, examples include _In2O3 , ZnO, _Al2O3 , _ZrO2 , _TiO2 , _IZO , IGZO, or ZrN, TiN, AlN, GaN, ZnN, InN, and the like.

On the other hand, when the protective member 5 is a multi-layer structure, the material of the inner surface layer is preferably a material that has a small difference in linear expansion coefficient with the base material 2 and is not easy to react with the bonding material 6 (such as In solder).

From this point of view, metal materials or ceramic materials, or composite materials thereof can be cited. As metal materials, for example, single metals such as Cu, Al, Ti, Ni, Zn, Cr, and Fe, or alloys containing any of these can be cited.

Furthermore, when the protective member 5 is a multi-layer structure of three or more layers, it is preferably designed so that the bonding between the middle layer and the surface layer and the inner layer is good, and the linear expansion rate of the material constituting the middle layer becomes the median value of the linear expansion rate of the material constituting the surface layer and the inner layer.

(Joint material 6)

The substrate 2 and the target member 3, as well as the substrate 2 and the protective member 5 are bonded to each other via a bonding material 6.

The bonding material 6 is not particularly limited as long as it can be used to bond the target component 3 and the substrate 2. For example, tin metal or tin alloy such as In-plated, In-Sn-plated, or In-plated alloy with a trace amount of metal components added to In can be cited.

〈Purpose〉

This sputtering target can be used, for example, as a sputtering target when forming an oxide semiconductor thin film. However, it is not limited to this use.

〈Manufacturing of this sputtering target〉

A plurality of protective members 5 are arranged on the surface of the substrate 2 at predetermined intervals, and the two are bonded together by a bonding material 6.

Next, a bonding material 6 is applied to the inner surface of the target member 3 in advance, and a plurality of target members 3 are arranged on the surface of the protective member 5 with gaps between adjacent target members 3, 3. At this time, the protective member 5 is arranged along the gap 4 between the target member 3 and the substrate 2, and the protective member 5, the substrate 2, and the target member 3 are bonded by the bonding material 6.

At this time, as described above, it is preferable to also apply a bonding material 6 made of a material having a higher thermal conductivity than the target member 3A on the inner surface of the protruding portion 3Aa of the target member 3A.

As for the bonding material 6, by selecting a material with a higher thermal conductivity than the target member 3A and coating the bonding material 6 on the inner surface of the protrusion 3Aa to provide a heat conductive layer 7, a cooling effect can be provided to suppress the temperature rise of the protrusion 3Aa during sputtering, and as a result, the generation of arcs and discoloration of the protrusion 3Aa can be suppressed.

However, this method is only an example of the method for manufacturing the sputtering target 1 and is not limited to this method.

〈Explanation of Sentences〉

In this manual, when "X to Y" (X and Y are arbitrary numbers) is used, unless otherwise specified, it means "above X and below Y", and also includes the meaning of "preferably greater than X" or "preferably less than Y".

Furthermore, when expressed as "above X" (X is an arbitrary number) or "below Y" (Y is an arbitrary number), it also includes the intention of "preferably greater than X" or "preferably less than Y".

Furthermore, when expressed as "X≦" (X is an arbitrary number) or "Y≧" (Y is an arbitrary number), it also includes the intention of "preferably X<" or "preferably Y>".

[Implementation example]

The present invention is described below based on an embodiment. However, the present invention is not limited to the embodiment described here.

<Implementation Example 1>

As shown in FIG5 , the target components 3A and 3B adjacent to each other with a gap 4 have different thicknesses, and a disc-shaped sputtering target 1 with a diameter of 152.4 mm is manufactured using a substrate 2 with different thicknesses with a step portion 2C.

Target components 3A and 3B are manufactured as follows.

The raw material powders of In ₂ O ₃ , Ga ₂ O ₃ , and ZnO were weighed at a mol ratio of 1:1:2 and mixed for 20 hours using a ball mill. Then, a polyvinyl alcohol aqueous solution diluted to 4 mass % was added as a binder at 8 mass % relative to the total amount of the powder and mixed, and then formed into a disk shape at a pressure of 500 kgf/cm ^2. The molded body was sintered at 1400°C in the atmosphere to obtain a disk-shaped sintered body. Next, the sintered body was ground on both sides using a flat grinder to produce a disk-shaped body with a diameter of 152.4 mm × a thickness of 10 mm and a disk-shaped body with a diameter of 152.4 mm × a thickness of 5 mm. Then, the disc processed body is cut into halves respectively while aligning the division position, thereby manufacturing an IGZO target member 3A with a thickness of 5 mm and an IGZO target member 3B with a thickness of 10 mm.

Prepare a disc-shaped substrate with a diameter of 180 mm, which is made of oxygen-free copper (Cu), has a step portion 2C with a height of 5 mm at the center, a thick wall portion with a thickness of 10 mm, and a thin wall portion with a thickness of 5 mm, as substrate 2.

As the protective member 5, a layer composed of Al ₂ O ₃ with a thickness of 100 μm was formed by thermal spraying on a strip-shaped Cu metal foil with a thickness of 0.5 mm and a width of 20 mm.

The entire inner surface of the target component 3A is coated in advance with In, which is a low-melting-point solder and is made of the same material as the bonding material 6. That is, a heat-conducting layer 7 made of In is formed on the inner surface of the protruding portion 3Aa of the target component 3A.

Next, the target components 3A and 3B are arranged on the substrate 2 so that the sputtering surfaces of each other are formed at the same height and a gap 4 with a width (y) of 0.5 mm is set between the target components 3A and 3B, and the end of the target component 3A with a smaller thickness is arranged to protrude from the step portion 2C of the substrate 2. At this time, the amplitude x of the protruding portion 3Aa, that is, the distance x between the step portion 2C and the gap 4 is formed to be 5 mm. Next, the target components 3A and 3B are bonded to the substrate 2 using a bonding material 6 composed of In, which is a low-melting-point solder, to produce a sputtering target 1 (sample).

<Implementation Example 2>

A sputtering target 1 (sample) was prepared in the same manner as in Example 1, except that low-melting-point solder In was not coated on the inner surface of the protrusion 3Aa of the target member 3A in advance.

<Implementation Example 3>

A sputtering target 1 (sample) was produced in the same manner as in Example 1, except that the width x of the protrusion 3Aa of the target member 3A was formed to be 10 mm.

<Implementation Example 4>

A sputtering target 1 (sample) was prepared in the same manner as in Example 3, except that low-melting-point solder In was not applied in advance to the inner surface of the protrusion 3Aa of the target member 3A.

<Implementation Example 5>

A sputtering target 1 (sample) was produced in the same manner as in Example 1, except that the width x of the protrusion 3Aa of the target member 3A was formed to be 20 mm.

<Implementation Example 6>

A sputtering target 1 (sample) was prepared in the same manner as in Example 5, except that low-melting-point solder In was not applied in advance to the inner surface of the protrusion 3Aa of the target member 3A.

〈Comparison Example 1〉

A sputtering target (sample) was prepared in the same manner as in Example 1, except that the end of the target member 3A was configured so that it did not protrude from the step portion 2C of the substrate 2 and the distance x between the step portion 2C and the gap 4 was 0 mm.

=Evaluation of the produced sputtering targets=

The sputtering targets (samples) produced in the embodiments and comparative examples were evaluated as follows.

〈Splash plating evaluation test〉

(Cu mixing amount)

Using the sputtering targets (samples) prepared in the embodiments and comparative examples, sputtering was performed under the following conditions to form an IGZO thin film with a thickness of 14 μm on an alkali-free glass substrate (manufactured by Nippon Electric Glass Co., Ltd.), thereby obtaining a substrate with an IGZO thin film.

Next, the portion directly above the gap 4 of the sputtering target (sample) in the substrate with the IGZO thin film was cut out, and the content of Cu, a constituent raw material of the substrate, in the IGZO thin film (referred to as "Cu inclusion amount") was measured by atomic absorption spectrometry.

(Sputtering conditions)

Equipment: DC magnetron sputtering device, exhaust system low temperature pump, rotor pump

Reached vacuum degree: 3×10 ^-6 Pa

Sputtering pressure: 0.4Pa

Oxygen partial pressure: 1×10 ^-3 Pa

Power consumption time: 2W/ ^cm2

Time: 10 hours

(Arc Evaluation)

Furthermore, the number of arcs generated in 10 hours was measured using an arc counter (manufactured by LANDMARK TECHNOLOGY, model: μArc Moniter MAM Genesis MAM data collector Ver.2.02). The number of arcs generated was evaluated as "low" when it was less than 120% of the number of arcs in the undivided target, "medium" when it was between 120% and 150%, and "high" when it was more than 150%.

(Evaluation of color change of protrusions)

Furthermore, the appearance of the gap in the eroded part after sputtering was observed and evaluated to see whether it changed color to black. If it did not change color, it was evaluated as "no abnormality", and if it changed color, it was evaluated as "discoloration".

The discoloration is speculated to be caused by the slow cooling of the protrusions, which results in a local temperature rise, causing the target material to denature.

[Table 1]

From the above-mentioned embodiments, comparative examples and the test results conducted by the inventors so far, it can be seen that in a structure in which the thicknesses of the substrates on the inner sides of the adjacent target members are different across a gap and the heights of the sputtered surfaces of the adjacent target members are the same, by making the end of the target member with a smaller thickness protrude more than the step portion of the substrate, even if the step portion is not covered by the protective member, the constituent material of the substrate (such as Cu, etc.) can be prevented from being mixed into the film.

In addition, since the part of the target component with a smaller thickness that protrudes further than the step portion of the substrate, that is, the protrusion, has no bonding material in contact with its inner surface, it cannot obtain the cooling effect brought by the bonding material, and cracks or arcs may occur.

In this regard, it can be seen that, as in Examples 1, 3, and 5, by coating the inner surface of the protrusion with the same material as the bonding material to form a heat conductive layer, a cooling effect can be obtained and the generation of arcs can be suppressed.

In addition, it is also known that by coating the inner surface of the protrusion with the same material as the bonding material to form a heat conductive layer, a cooling effect can be obtained and discoloration can be prevented.

1: Sputtering target

2: Base material

3,3A,3B: Target components

4: Gap

5: Protective components

Claims (10)

A sputtering target comprises a plurality of target components and a substrate having a step. The sputtering target comprises a protective component disposed between the target components and the substrate and disposed at the step portion of the substrate having a step. The target components have different thicknesses. Among the target components having different thicknesses, the end of the target component with a smaller thickness has a portion protruding more than the step portion of the substrate. The protruding portion is called a protruding portion. The protrusion of the protruding portion more than the step portion is smaller than the distance between the end of the target component with a larger thickness and the step portion of the substrate. In the protruding portion, only the inner surface is formed with a layer made of a material having a higher thermal conductivity than the target component. The sputter plating target as described in claim 1, wherein the protrusion is more protruding than the step portion of the substrate by 1 mm to 20 mm. A sputtering target as described in claim 1 or 2, wherein the protrusion is more than 3 mm in extent than the step portion of the substrate. A sputter plating target as described in claim 1 or 2, wherein the protrusion has a protrusion width greater than the step width of the substrate of 4 mm or more. A sputtering target as described in claim 1 or 2, wherein the protrusion is more than 5 mm in extent than the step portion of the substrate. A sputter plating target as described in claim 1 or 2, wherein the protrusion is less than 15 mm in extent than the step portion of the substrate. The sputter plating target as described in claim 1 or 2, wherein the protrusion is less than 12 mm in extent than the step portion of the substrate. A sputtering target as described in claim 1 or 2, wherein the material with high thermal conductivity is the same material as the bonding material used to bond the target component and the substrate. A sputtering target as described in claim 1 or 2, wherein the target component is made of ceramic. The sputtering target described in claim 1 or 2 is used for forming oxide semiconductor thin films.

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