JP2003089869A - Sputtering target, and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target which is produced through a mechanical grinding process, and in which a sputtering stage is preliminarily performed to the sputtering face before shipping. SOLUTION: A sputtering target which has effectively reduced occurrence of an initial arc, and has high initial stability can be obtained, and, by using this sputtering process, the productivity improves, and thin film deposition can efficiently be performed. Further, a polishing stage can be eliminated, so that a grinding stage can be simplified, and the cost therefor can be reduced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sputtering target and a method for manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION A sputtering method has been conventionally known as one of thin film forming methods. The sputtering method is a method of forming a thin film on a substrate by causing an inert gas in a plasma state to collide with a target under reduced pressure and causing the energy and the molecules or atoms emitted from the target to adhere to the substrate. However, it is industrially used because a large area can be easily obtained and a high-performance film can be obtained.

In recent years, as a sputtering method,
A reactive sputtering method in which sputtering is performed in a reactive gas and a magnetron sputtering method in which a magnet is installed on the back surface of a target to accelerate the thin film formation are also known. Among thin films formed by using such a sputtering method, an oxide (hereinafter referred to as ITO) film containing at least one of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) is a visible light transmitting material. Since it has high properties and high conductivity, it is widely used as a transparent conductive film in liquid crystal display devices, heat generation films for preventing dew condensation on glass, infrared reflective films, and the like.

However, when forming such a high-performance thin film by the sputtering method, there were the following problems. That is, during sputtering, especially during the initial stage of sputtering, an abnormal discharge called arcing occurs, which impairs film forming stability, and causes particles to adhere to and deposit on a sputtering target (hereinafter, also simply referred to as a target). However, there is a problem that black deposits called nodules are generated and cause arcing, and that new particles are generated by this arcing. Further, if these particles adhere to the thin film, the performance of the thin film is deteriorated, and this is also a cause of thin film defects.

In particular, a new sputtering target must be set, and idle operation must be performed from the time immediately after the start of sputtering until arcing (hereinafter also referred to as the initial arc) does not occur and a product can be manufactured.
It was an obstacle to productivity improvement. Conventionally, it is said that the occurrence of such arcing and nodules is reduced as the target surface is polished and smoothed, and a surface-polished target having a smooth surface has been the mainstream so far. For example, an ITO sputtering target that aims to prevent the generation of arcing and nodules by controlling the surface roughness of the target within a predetermined range is disclosed in Patent No. 27.
It is described in Japanese Patent No. 50483, Japanese Patent No. 3152108, and the like. However, in order to achieve such a predetermined surface roughness, after creating a target, rough grinding is performed by mechanical grinding to adjust the thickness, and further finish grinding (polishing) is performed in stages to form the target surface. Since it is necessary to smooth the surface, there is a problem that manufacturing time and cost increase. Further, I having such a predetermined surface roughness
Even in the TO target, the initial arc cannot be prevented, and there has been a problem that a new sputtering target must be set and then idled for a relatively long time.

[0006] Incidentally, such a problem is caused by a ceramic-based target produced by a sintering method containing oxides, nitrides, carbides, borides, etc. other than ITO as a main component.
Alternatively, the same applies to a metal-based target. As a result of intensive studies in view of such a situation, the present inventors have found that there are initial particles caused by a grinding process or the like existing on the target surface, and the presence of sites that can be released from the surface layer due to thermal shock during sputtering to become particles. However, the main cause of arcing and nodules, prior to shipping, by performing a sputtering step on the sputter surface of the target, it is possible to prevent the generation of initial arc by removing these, to complete the present invention I arrived.

[0007]

OBJECT OF THE INVENTION The present invention prevents the occurrence of an initial arc,
An object of the present invention is to provide a sputtering target capable of improving initial stability and remarkably improving productivity, and a method for manufacturing the sputtering target.

[0008]

SUMMARY OF THE INVENTION A sputtering target according to the present invention is a sputtering target manufactured through a mechanical grinding process, and is characterized in that the sputtering surface of the target is subjected to the sputtering process before shipment. In the present invention, the cumulative amount of input electric power in the sputtering step applied to the sputtering surface of the sputtering target is preferably 0.005 Wh / cm ² or more, more preferably 0.01 Wh / cm ² or more, and further preferably 0.
It is desirable that it is 02 Wh / cm ² or more.

It is preferable that the sputtering target according to the present invention has a surface protective film attached to the sputtering surface of the sputtering target at the time of shipment. In the present invention, the sputtering target is preferably produced by a sintering method.

The sputtering target according to the present invention preferably contains indium oxide as a main component. Further, the sputtering target according to the present invention is preferably an oxide (ITO) containing at least one of indium oxide and tin oxide. The manufacturing method of the sputtering target according to the present invention, the target, preferably the surface of the target obtained by the sintering method is mechanically ground, then prior to shipping, at least the sputtering surface of this target is subjected to a sputtering step. It has a feature.

Further, in the method of manufacturing an ITO sputtering target according to the present invention, the surface of an ITO target obtained by sintering a raw material containing indium oxide and tin oxide as main components is mechanically ground, and then before shipment. It is characterized in that a sputtering step is performed on at least the sputtering surface of this ITO target in advance.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be specifically described below. <Sputtering target> The sputtering target according to the present invention is prepared by mechanically grinding the target material and then before shipment from the sputtering target manufacturer.
The sputtering process has already been performed on the sputtering surface.

Usually, there are initial particles due to the grinding process or the like on the surface of the target, and a portion that can be detached from the surface layer to become particles due to thermal shock during sputtering, and these particles adhere to the substrate during sputtering. By doing so, it is considered that while thin film defects occur, redeposition and deposition on the target cause black deposits called nodules, which causes arcing and new particles.

Therefore, if the particles which are likely to be detached by thermal shock during sputtering can be removed by previously sputtering the sputtering surface of the sputtering target, the initial arc can be effectively reduced. . In the present invention, the cumulative amount of input electric power in the sputtering step which is added to the sputtering surface in advance is preferably 0.005 Wh / cm ² or more, more preferably 0.01 Wh / cm ² or more, and further preferably 0.02 Wh / c 2.
m ² or more, particularly preferably 0.1 Wh / cm ² or more is desirable. When the cumulative amount of input electric power is 0.005 Wh / cm ² or more, the target subjected to the sputtering process in advance has excellent initial arc characteristics and can effectively prevent the generation of the initial arc. On the user side, sputtering can be performed without substantially running idle, productivity is improved, and thin film formation can be efficiently performed. In the present invention, the upper limit of the cumulative amount of input electric power is not particularly limited, but it is usually desirable to be 10 Wh / cm ² or less from the viewpoint of productivity such as time and cost required for manufacturing a sputtering target.

Here, the cumulative input electric energy (Wh / cm ² ) is
It refers to the integrated amount of electric power per unit area that is input in the sputtering process that is performed on the sputtering surface of the target before shipment. The initial arc characteristics of the target can be evaluated by the integrated input electric energy (Wh / cm ² ) that is input until the arcing interval becomes 10 seconds or more when sputtering is performed using a φ6 inch target. . Specifically, when performing sputtering, an arc counter (manufactured by Landmark Technology Co., Ltd.) is used as a measuring device to detect the arc, and until the initial arc of the φ6 inch target converges, that is, between the arcing and the next arcing. Evaluate by the accumulated input electric energy until the generation interval becomes 10 seconds or more. It can be said that the smaller the value of the cumulative amount of input electric power and the smaller the number of arcs generated, the better the initial arc characteristics of the target.

In the present invention, since the sputtering step is performed on the sputtering surface of the target in advance, the surface roughness Ra of the sputtering target according to the present invention is usually larger than the initial value immediately after mechanical grinding. Therefore, Ra of the sputtering target according to the present invention is
It may be larger than 0.5 μm, which has been conventionally considered preferable. On the other hand, it goes without saying that the present invention can be applied even when Ra of the target is 0.5 μm or less. In this specification, the surface roughness Ra is JIS B 0601 (19
1994) means the arithmetic mean roughness of the roughness curve measured in accordance with (1994).

The Ra value of the sputtering target according to the present invention converges to a substantially constant value regardless of the initial value when the sputtering is continued. However, from the viewpoint of productivity of the sputtering process, the Ra value of the sputtering target is increased. May be in the range of 0.1 to 5.0 μm,
It may be in the range of 0.1 to 3.0 μm. The sputtering target to which the present invention can be applied is not particularly limited as long as it undergoes a mechanical grinding step, and the target material is not particularly limited, and a ceramic target containing oxide, nitride, carbide, boride, etc. as a main component. Alternatively, it may be a target made of metal. As such a target material, for example, ITO (ITO may contain a small amount of other metal oxide components), In ₂ O ₃
-ZnO (IZO), ZnO-Al 2 O 3, In 2 O 3, Sn
O ₂ , ZnO, Al ₂ O ₃ , SiO ₂ , Ta ₂ O ₅ , MgO,
NiO, Si ₃ N ₄ , AlN, SiC, Mo, W, Ti,
Examples thereof include Zr, Hf, Nb, Ta and Al. Of these, the ITO sputtering target requires a high degree of initial stability in order to perform efficient sputtering, and thus the present invention can be applied particularly effectively.

It is preferable that the sputtering target according to the present invention has a surface protective film attached to the sputter surface immediately after the sputtering surface is sputtered. When such a surface protection film is attached to the sputter surface, adhesion of impurities to the target surface,
Gas adsorption can be prevented. The surface protective film may be attached to at least the sputter surface, and may be attached to the entire target. Examples of the method of attaching the surface protection film include a method of bringing a resin film into close contact with the sputter surface or a method of vacuum-packing the entire target with the resin film. Of these, a vacuum pack is desirable because bubbles hardly remain between the film and the target.
The resin film used for the surface protection film is not particularly limited, but a resin film containing no releasable particles is preferable in order to prevent transfer of particles to the sputter surface.

<Method of manufacturing sputtering target>
The method for manufacturing the sputtering target according to the present invention will be described below. As a method of manufacturing a sputtering target according to the present invention, a general method of manufacturing a sputtering target can be used except that a sputtering step is performed on the sputtering surface. For example, after the raw material powders are mixed at a predetermined mixing ratio, it is possible to use a sintering method in which the ceramic target is molded and fired (sintered) using various conventionally known dry methods or wet methods, and then mechanically ground. Yes, with metal targets, after vacuum melting, casting,
It is possible to use a powder metallurgy method in which a vacuum melting method of mechanically grinding after plastic working, a molding by a HIP (hot isostatic press) method or a CIP (cold isostatic press) method, followed by sintering and plastic working is performed.

An example of the manufacturing method will be described below by taking a ceramic target as an example. Examples of the above-mentioned dry method include CP (cold press) method, HP (hot press) method, HIP (hot isostatic press) method and the like. In the CP method, the mixed raw material powder is filled in a molding die to form a molded body, and the molded body is fired (sintered) in an air atmosphere or an oxygen atmosphere. In the HP method, the mixed raw material powders are put into a molding die inside an electric furnace, and molding and sintering are performed simultaneously while heating and pressing. In the HIP method, the mixed raw material powder or preform is enclosed in a bag such as rubber or a metal foil that forms a coating even at high temperature, degassed, and then inserted into a container and isotropically passed through an inert atmosphere medium. And pressurize while heating and sintering.

As the wet method, for example, Japanese Patent Laid-Open No. 11-286 is available.
The filtration type molding method described in Japanese Patent No. 002 can be mentioned. This filtration-type molding method uses a filtration-type molding die made of a water-insoluble material for draining water from a ceramic raw material slurry under reduced pressure to obtain a shaped body. A slurry made of water and an organic additive is injected, water in the slurry is drained under reduced pressure to form a molded body, and the molded body is dried and degreased and then fired (sintered).

In each of the above methods, it is desirable that the firing temperature be an appropriate temperature depending on the raw material used. Usually, the raw material is molded in this way in the mold and fired (sintered).
After that, the sintered body is mechanically ground to form a predetermined size, and then bonded to a backing plate to form a target.

Of these, generally, for mechanical grinding, methods such as surface grinding, rotary polishing and blasting are appropriately adopted as needed, and after the grinding for the forming process, the surface is roughly ground for the thickness adjustment. To further smooth the surface, make the grindstone finer in stages and finish grinding (hereinafter also referred to as polishing), or by blasting using glass beads, alumina beads, zirconia beads, etc. as a projection material. Grinding (hereinafter, also referred to as polishing together with finish grinding) is performed.

Further, in the present invention, a sputtering process is performed on the sputtering surface of the target manufactured as described above to form a sputtering target. This sputtering step may be performed after rough grinding, after finish grinding or grinding by blasting, or after bonding with a backing plate. By performing sputtering on the sputter surface of the target in this way, it is possible to remove burrs and grinding powder generated by grinding, as well as locations that are likely to be detached due to thermal shock during sputtering, resulting in effective reduction of the initial arc. It is thought that it can be done. Therefore, according to the present invention, the initial arc is reduced and efficient sputtering is performed without necessarily polishing the surface to a mirror-like smooth surface and without blasting with fine beads to suppress the surface roughness. It is possible to obtain a target capable of performing. That is, when the present invention is applied, a sputtering target can be obtained by omitting the polishing step and performing the sputtering step on the sputtering surface of the target.

Therefore, the Ra value of the sputtering target according to the present invention may be larger than 0.5 μm, which is conventionally preferable as described above. On the other hand, it goes without saying that the present invention can be applied even when Ra of the target is 0.5 μm or less. In the present invention, in order to perform the sputtering step in advance on the sputtering surface of the target,
Ra is usually larger than the initial value immediately after mechanical grinding.
The Ra value of the sputtering target according to the present invention converges to a substantially constant value irrespective of the initial value when the sputtering is continued, but from the viewpoint of the productivity of the above-described sputtering process, the Ra value of the sputtering target is increased.
The value may range from 0.1 to 5.0 μm,
It may be in the range of 1 to 3.0 μm.

Further, the sputtering conditions in the sputtering process are not particularly limited, and the sputtering may be performed under normal conditions until the above-mentioned integrated input electric energy is reached.

[0027]

According to the present invention, it is possible to obtain a sputtering target having a high initial stability in which the generation of an initial arc is effectively reduced, and by using this sputtering target, the productivity is improved. A high-performance thin film can be formed efficiently. Further, since the polishing step can be omitted, the grinding step can be simplified and the cost can be reduced.

[0028]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples.

[0029]

[Example 1] In ₂ O ₃ : Sn with In ₂ O ₃ powder and SnO ₂ powder
The mixture was mixed at a ratio of O ₂ = 90: 10 mass%, and an ITO sintered body was prepared according to a conventional method to prepare a target material. After cutting this target material into a size of φ6 inches, both the surface to be used for sputtering (sputtering surface) and the surface to be bonded (bonding surface) are ground with a surface grinder to adjust the thickness to 5 mm, and then the sputtering surface Targets Nos. 1 to 4 were prepared by grinding different numbers of diamond whetstones. Also, instead of grinding the sputtered surface with a diamond grindstone, blasting was performed using alundum as a shot material to create target No. 5.

Next, these targets were bonded to a copper backing plate, mounted on a sputtering apparatus, and sputtered under the following conditions. Sputtering conditions Sputtering method: DC magnetron sputtering, process gas: Ar, process pressure: 3 mTorr, oxygen partial pressure: 0.03 mTorr, input power: 1.64 W / cm ² As an arc counter during this sputtering, μ
Arc Monitor (MAM Genesis) (Landmark Technology Co., Ltd.) is used to detect the measurement conditions: detection mode: energy, arc detection voltage: 100 V, large-medium energy boundary: 50
mJ, hard arc minimum time: 100μs, arc detection, until the initial arc converges (arc interval is
After measuring the accumulated input electric energy for 10 seconds or more),
Sputtering was continued until the integrated input electric energy reached 0.1 Wh / cm ² . The results are shown in Table 1.

The surface roughness Ra of the sputtering surface of the target before sputtering was measured according to JIS B0601 (1994). The surface roughness is measured using SE1700 (made by Kosaka Laboratory) as a surface roughness meter.
Stylus radius: 2 μm, feed rate: 0.5 mm / sec, cutoff:
It was measured under the conditions of λc 0.8 mm and evaluation length: 4 mm.

[0032]

[Table 1]

[0033]

Example 2 The sample used in Example 1 was removed from the sputtering apparatus, vacuum-packed, and allowed to stand for 1 day. afterwards,
A sample was taken out from the vacuum pack, mounted on a sputtering apparatus, and sputtered under the same sputtering conditions as in Example 1 until the total amount of input electric power in Example 1 was 5 Wh / cm ² . The surface roughness Ra before the sputtering process was measured in the same manner as in Example 1. The results are shown in Table 2.

[0034]

[Table 2]

From Table 2, the results of the sputtering treatments are as follows:
It can be seen that the arc quickly converges immediately after sputtering and the number of arcs is reduced, and the initial arc characteristics are excellent.

[0036]

[Example 3] The sample used in Example 2 was removed from the sputtering apparatus and then mounted again, under the same conditions as the sputtering conditions of Example 1 and combined with the accumulated input electric energy of Examples 1 and 2. Sputtering was performed until it reached 6 Wh / cm ² . As a result, no arc having an arc interval of less than 10 seconds was generated for any of the targets. The surface roughness Ra before the sputtering process was measured in the same manner as in Example 1. The results are shown in Table 3.

[0037]

[Table 3]

Claims (11)

[Claims] 1. A sputtering target manufactured through a mechanical grinding step, wherein the sputtering surface of the target is subjected to a sputtering step before shipment. 2. The integrated input power amount of the sputtering process applied to the sputtering surface of the sputtering target is 0.005 Wh / cm ² or more.
The sputtering target according to 1. 3. The sputtering target according to claim 1, wherein an integrated amount of input electric power in the sputtering step applied to the sputtering surface of the sputtering target is 0.01 Wh / cm ² or more. 4. The sputtering target according to claim 1, wherein an integrated amount of electric power applied in the sputtering step applied to the sputtering surface of the sputtering target is 0.02 Wh / cm ² or more. 5. The sputtering target according to claim 1, wherein a surface protective film is attached to the sputtering surface of the sputtering target at the time of shipment. 6. The sputtering target according to claim 1, wherein the sputtering target is produced by a sintering method. 7. The sputtering target according to claim 1, wherein the sputtering target contains indium oxide as a main component. 8. The sputtering target according to claim 1, wherein the sputtering target is an oxide (ITO) containing at least one of indium oxide and tin oxide. 9. A method of manufacturing a sputtering target, which comprises mechanically grinding the surface of a target and then subjecting at least the sputtering surface of the target to a sputtering step before shipment. 10. The method of manufacturing a sputtering target according to claim 9, wherein the target is a target obtained by a sintering method. 11. A surface of an ITO target obtained by sintering a raw material containing indium oxide and tin oxide as main components is mechanically ground, and then sputtered on at least a sputtering surface of the ITO target before shipment. A method for manufacturing an ITO sputtering target, which comprises performing steps.