WO2019054489A1

WO2019054489A1 - Sputtering target

Info

Publication number: WO2019054489A1
Application number: PCT/JP2018/034211
Authority: WO
Inventors: 香歩木内; 雄也陸田
Original assignee: 三菱マテリアル株式会社
Priority date: 2017-09-14
Filing date: 2018-09-14
Publication date: 2019-03-21
Also published as: JP2019052373A; KR20200053469A

Abstract

This sputtering target is characterized by: being mainly composed of Zn, Sn and O, and containing Zn and Sn in amounts such that the Zn/(Zn + Sn) atomic ratio is within the range of from 0.1 to 0.6 (inclusive); and comprising tin oxide phases and tin zinc complex oxide phases as main phases, while also comprising tin metal phases. This sputtering target is also characterized in that: the amount of Sn present as the tin metal phases is within the range of from 1.0 mol% to 8.0 mol% (inclusive); the average of the circle-equivalent diameters of the tin metal phases is 1 μm or less; and the relative density is 95% or more.

Description

Sputtering target

The present invention relates to a sputtering target used when forming an oxide film containing Zn, Sn and O as main components.
Priority is claimed on Japanese Patent Application No. 2017-176800, filed on Sep. 14, 2017, the content of which is incorporated herein by reference.

The oxide film mainly composed of Zn, Sn, and O described above is excellent in the transmittance in the visible light region and excellent in the infrared reflection characteristic, so a heat shielding film such as window glass, an infrared filter, etc. Is used for
Here, the above-described oxide film is formed, for example, by performing sputtering using a sputtering target made of an oxide, as shown in the following Patent Documents 1-5. In addition, as above-mentioned sputtering target, what makes flat form or cylindrical shape, for example is provided.

Patent Document 1 proposes a sputtering target consisting of an oxide sintered body mainly composed of a tin-zinc complex oxide phase and a metal tin phase.
Moreover, the sputtering target which consists of an oxide sinter of Zn and Sn is proposed by patent documents 2 and 3. FIG.
Further, Patent Document 4 proposes a sputtering target which is an oxide sintered body substantially consisting of tin, zinc and oxygen, and is mainly composed of a tin-zinc complex oxide phase and a tin oxide phase. There is.
Further, Patent Document 5 proposes a sputtering target in which a metal oxide of at least one of zinc oxide and tin oxide and a metal powder are sintered.

Japan JP 2013-177260 A (A) JP JP 2010-037161 A (A) Japan JP 2010-031364 (A) Japanese Patent Application Laid-Open No. 2007-314364 (A) Japanese Patent Application Laid-Open No. 2014-167162 (A)

By the way, in the sputtering target described in Patent Document 1, stannous oxide (SnO) is used as a raw material, and a metallic tin phase is formed by reducing the stannous oxide (SnO). The relative density is about 91.1 to 93.6%, and a sufficiently high density has not been obtained.
In addition, since the tin-zinc complex oxide phase and the metal tin phase are the main phases, and in the target sputtering surface, the specific resistance value is largely different between the area of the tin-zinc complex oxide phase and the area of the metal tin phase. There was a risk that the number of occurrences of abnormal discharge at the time would increase. Furthermore, since the thermal expansion coefficients of the tin-zinc complex oxide phase and the metal tin phase are largely different, when the temperature rises during sputtering, the target surface is cracked due to thermal expansion, and sputtering is stably performed. I could not do that.

In the sputtering targets described in Patent Documents 2 and 3, it is premised that RF (high frequency) sputtering is performed because the resistance of the target itself is very high and DC (direct current) sputtering is difficult. In this RF (high frequency) sputtering, there is a problem that the film forming speed is low and the productivity is lowered.
Furthermore, in the sputtering target described in Patent Document 4, although it is described that DC sputtering is possible, since the specific resistance value is relatively high, for example, several tens Ω · cm, DC (direct current) sputtering is stable. Was difficult to implement.

Further, in the sputtering target described in Patent Document 5, since the metal powder and the oxide are sintered, the conductivity of the target is improved by the metal powder being dispersed and being present as a metal phase, It is stated that DC sputtering is possible. However, in Patent Document 5, since the metal powder and the oxide are simply sintered, if the sintering temperature is set to the melting point or more of the metal powder, the metal powder is melted out, so the sintering temperature is high. It was difficult to set, and it was difficult to sufficiently improve the density. Furthermore, since the metal phase is constituted by the metal powder used at the time of sintering, the size of the metal phase depends on the particle size of the metal powder, so that the fine metal phase is not segregated and It was difficult to disperse uniformly.
As described above, in the sputtering target described in Patent Document 5, many voids exist and the metal phase is nonuniformly present, which may increase the number of occurrences of abnormal discharge at the time of sputtering. The In addition, cracking may occur during sputtering, which may make it impossible to stably perform sputtering.

The present invention has been made in view of the above-described circumstances, and it is possible to provide a sputtering target which can suppress the occurrence of abnormal discharge and can stably perform DC sputtering with a sufficiently low specific resistance value. With the goal.

In order to solve the above problems, a sputtering target of one embodiment of the present invention (hereinafter referred to as “the sputtering target of the present invention”) is mainly composed of Zn, Sn and O and Zn / Sn in atomic ratio Zn / Sn. (Zn + Sn) is contained in a range of 0.1 or more and 0.6 or less, and the tin oxide phase and the tin-zinc complex oxide phase are main phases, and a metal tin phase is included, The amount of Sn present as a metal tin phase is in the range of 1.0 mol% or more and 8.0 mol% or less, the average equivalent circle diameter of the metal tin phase is 1 μm or less, and the relative density is 95% or more It is characterized by being.

According to the sputtering target of the present invention, while having a tin oxide phase and a tin-zinc complex oxide phase as main phases, it has a metal tin phase, and the average equivalent circle diameter of the metal tin phase in the cross section of the sputtering target Since the value is 1 μm or less, the metal tin phase is uniformly present without segregation, and the occurrence of abnormal discharge at the time of sputtering can be suppressed. In addition, the relative density can be improved by finely depositing the metal Sn so as to fill the particles of the oxide phase that is to be the parent phase. Furthermore, even when the temperature rises at the time of sputtering, it is possible to suppress the occurrence of cracking of the target surface due to thermal expansion.
In addition, “the tin oxide phase and the tin-zinc complex oxide phase are the main phases” means that the respective proportions (mol%) of the tin oxide phase and the tin-zinc complex oxide phase in the phase constituting the sputtering target Means more than the other phases.
Moreover, "being mainly composed of Zn, Sn, and O" means that the atomic ratio (at%) of each of Zn, Sn, and O in the sputtering target composition is 10 at% or more.

Furthermore, in the sputtering target of the present invention, since the relative density is 95% or more, the number of voids is small, and the occurrence of abnormal discharge at the time of sputtering can be suppressed. In addition, the occurrence of cracking at the time of sputtering can be suppressed.
Further, in the sputtering target of the present invention, Zn and Sn are contained so that Zn / (Zn + Sn) is in the range of 0.1 or more and 0.6 or less in atomic ratio, so that the transparency and infrared reflection characteristics are obtained. Can form an excellent oxide film.

Further, in the sputtering target of the present invention, since the amount of Sn present as the metal tin phase is 1.0 mol% or more, the specific resistance value is sufficiently low, and an oxide film is stably formed by DC sputtering. It becomes possible to make a film.
On the other hand, since the amount of Sn present as the metal tin phase is 8.0 mol% or less, the metal tin phase is not present more than necessary, and it is possible to suppress melting of the metal when heated in the manufacturing process, A sputtering target can be manufactured stably. In addition, even when the temperature rises during sputtering, the occurrence of cracks on the surface of the target due to thermal expansion can be suppressed.

Here, the sputtering target of the present invention may further contain an oxide of one or two or more metal elements M selected from Cr, V, Si, Ti, Al, and Zr.
In this case, tin oxide can be reduced by one or more metal elements M selected from Cr, V, Si, Ti, Al, and Zr, and a metal tin phase can be formed in the sputtering target. . Accordingly, the specific resistance value is sufficiently lowered, and the oxide film can be stably formed by DC sputtering.

Further, in the sputtering target of the present invention, it is preferable that the metal element M be contained so that M / (Zn + Sn + M) is in the range of 0.001 or more and 0.05 or less in atomic ratio.
In this case, tin oxide can be reliably reduced by the metal element M to form a metal tin phase. Accordingly, the specific resistance value is sufficiently lowered, and the oxide film can be stably formed by DC sputtering. Furthermore, various characteristics of the formed oxide film can be maintained.

ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress generation | occurrence | production of abnormal discharge, it becomes possible to provide the sputtering target in which a specific resistance value is low enough and can perform DC sputtering stably.

It is a structure observation photograph (EPMA image) in the sputtering target which is embodiment of this invention. It is a flowchart which shows an example of the manufacturing method of the sputtering target which is embodiment of this invention.

Hereinafter, a sputtering target according to an embodiment of the present invention will be described with reference to the attached drawings.
The sputtering target according to this embodiment contains Zn, Sn, and O as main components, and Zn and Sn in an atomic ratio such that Zn / (Zn + Sn) is in the range of 0.1 or more and 0.6 or less. There is.

Moreover, in the sputtering target which is this embodiment, while having a tin oxide phase and a tin zinc complex oxide phase as a main phase, it has a metal tin phase. In the present embodiment, as a result of X-ray diffraction analysis, it is confirmed that the tin oxide phase is a stannic oxide phase (SnO ₂ phase) and the tin-zinc complex oxide phase is a Zn ₂ SnO ₄ phase. ing.
And in the sputtering target which is this embodiment, the average value of the circle equivalent diameter of the observed metal tin phase is made into 1 micrometer or less, and the above-mentioned metal tin phase does not have segregation, and is uniformly distributed. .
That is, in the sputtering target which is this embodiment, it is set as the structure which the metal tin phase disperse | distributed in the oxide phase (a tin oxide phase and a tin zinc complex oxide phase) used as a mother phase. As described later, this metal tin phase is formed by reduction of tin oxide.

Here, the amount of Sn present as the above-mentioned metal tin phase is in the range of 1.0 mol% or more and 8.0 mol% or less.
Moreover, in the sputtering target which is this embodiment, relative density is made into 95% or more.
Furthermore, in the sputtering target according to the present embodiment, the specific resistance value is set to 1 Ω · cm or less.

Here, the sputtering target according to the present embodiment may further contain an oxide of one or more metal elements M selected from Cr, V, Si, Ti, Al, and Zr.
In addition, in the sputtering target which is this embodiment, when it has an oxide phase of metallic element M, content of metallic element M is 0.001 / 0.05 or less in atomic ratio M / (Zn + Sn + M). It is preferable to set so as to be within the range.
That is, in the sputtering target according to the present embodiment, the composition contains Zn, Sn, O, and as necessary, the metal element M, and the other components are inevitable impurities.

Hereinafter, the atomic ratio in the sputtering target according to the present embodiment, the average value of the equivalent circle diameters of observed metal tin, the amount of Sn contained as a metal tin phase, the relative density, the specific resistance value, and the metal element M , The reasons defined as above will be described.

(Atom ratio Zn / (Zn + Sn): 0.1 or more and 0.6 or less)
In the sputtering target according to this embodiment, an oxide film to be a heat shielding film is formed, and it is necessary to satisfy the transmittance in the visible light region and the infrared reflection characteristic.
Here, an oxide film satisfying the various characteristics described above is formed by containing Zn and Sn in an atomic ratio such that Zn / (Zn + Sn) is in the range of 0.1 or more and 0.6 or less. be able to.
The lower limit of the atomic ratio Zn / (Zn + Sn) is preferably 0.2 or more, and more preferably 0.25 or more in order to reliably form an oxide film excellent in various characteristics. . Further, the upper limit of the atomic ratio Zn / (Zn + Sn) is preferably 0.5 or less, and more preferably 0.4 or less.

(The average equivalent circle diameter of the metal tin phase is 1 μm or less)
In the structure of the sputtering target, when the average equivalent circle diameter of the observed metal tin phase exceeds 1 μm, the number of occurrences of abnormal discharge increases, and it may not be possible to stably form a sputter film. . In addition, when the equivalent circle diameter of the metal tin phase is large, the precipitated metal tin phase can not fill the particles between the oxide phases, which may lower the relative density. Furthermore, due to the large difference between the thermal expansion coefficients of the metal tin phase and the oxide phase to be the matrix phase, when the temperature rises during sputtering, the difference is due to the difference between the thermal expansion coefficients of the metal tin phase and the oxide phase. Cracking may occur on the target surface.
From the above, in the present embodiment, the average value of the observed metal-tin phase equivalent circle diameters is limited to 1 μm or less.

In order to further suppress the occurrence of abnormal discharge and the occurrence of cracking at the time of sputtering and to sufficiently improve the relative density, the average equivalent circle diameter of the observed metal tin phase should be 0.65 μm or less. Is more preferable, and it is more preferable to set it to 0.60 μm or less.
Here, in the present embodiment, it is difficult to observe a metal tin phase having a circle equivalent diameter of less than 0.1 μm, so “the average of the circle equivalent diameter of the observed metal tin phase” is the circle equivalent diameter Is the average value of the circle equivalent diameter of the metal tin phase of 0.1 μm or more.

(The amount of Sn as a metal tin phase: 1.0 mol% or more and 8.0 mol% or less)
In the sputtering target according to the present embodiment, the above-described oxide film is formed by DC sputtering.
Here, when the amount of Sn present as a metal tin phase is less than 1.0 mol%, the specific resistance value becomes high, and there is a possibility that DC sputtering can not be stably performed. Moreover, there existed a possibility that density could not be improved enough.
On the other hand, when the amount of Sn present as a metal tin phase exceeds 8.0 mol%, melting of metal occurs during sintering, which may make it impossible to stably manufacture a sputtering target. In addition, a large amount of metal tin phase having a thermal expansion coefficient largely different from that of the matrix phase is present, and when the temperature rises during sputtering, there is a possibility that the surface of the target may be cracked due to thermal expansion.

For this reason, in the present embodiment, the amount of Sn present as the metal tin phase is set in the range of 1.0 mol% or more and 8.0 mol% or less.
Here, in order to lower the specific resistance value and carry out DC sputtering more stably, it is preferable to set the lower limit of the amount of Sn present as a metal tin phase to 3.0 mol% or more, and 4.5 mol% or more It is further preferred that In addition, in order to suppress dissolution of metal during sintering and stably manufacture a sputtering target, it is preferable to set the upper limit of the amount of Sn present as a metal tin phase to 7.5 mol% or less; It is more preferable to set it as 0 mol% or less.
In addition, about the amount of Sn which exists as a metal tin phase in the sputtering target which is this embodiment, a sample extract | collected from a sputtering target is crushed and it is set as powder, It measures by powder X-ray-diffraction method using this powder, Rietvelt It can be calculated by analyzing by the method.

(Relative density: 95% or more)
The relative density is the measured density divided by the theoretical density. In the present embodiment, the theoretical density is calculated by the following equation, assuming that the amount of Sn present as a metal tin phase is calculated by the Rietveld method, and the remaining Sn and Zn are respectively SnO ₂ and ZnO. did.
Theoretical density = 100 / {(Wa / Da) + (Wb / Db) + (Wc / Dc)}
Wa: SnO ₂ content (mass%)
Da: Theoretical density of SnO ₂ (6.95 g / cm ³ )
Wb: ZnO content (mass%)
Db: theoretical density of ZnO (5.61 g / cm ³ )
Wc: Content of metal Sn (mass%)
Dc: Theoretical density of metal Sn (7.30 g / cm ³ )

If the relative density of the sputtering target calculated by the above formula is less than 95%, a large number of voids will be present, and there is a possibility that abnormal discharge may easily occur at the time of sputtering. Moreover, there is a possibility that a crack may occur in the sputtering target after sputtering. So, in this embodiment, relative density is specified as 95% or more. Here, the density of the sputtering target may exceed the theoretical density calculated by the above equation due to the reaction of the raw material powder, etc., in which case the relative density will exceed 100%.
In order to further suppress the occurrence of abnormal discharge and the occurrence of cracking at the time of sputtering, the relative density of the sputtering target is preferably 96% or more, more preferably 98% or more. Further, the upper limit of the relative density is not particularly limited, but it is, for example, less than 105% because it is difficult to prepare a sintered body having a relative density of 105% or more.

(Specific resistance: 1 Ω · cm or less)
In order to stably perform DC sputtering, in the sputtering target according to the present embodiment, the specific resistance value is preferably 1 Ω · cm or less, and more preferably 0.1 Ω · cm or less. The lower limit of the specific resistance value is not particularly limited, and is, for example, 0.001 Ω · cm or more.

(Metal element M)
Since one or two or more metal elements M selected from Cr, V, Si, Ti, Al, and Zr are elements capable of reducing tin oxide to form a metal tin phase, these metal elements M may be contained. Since the metal element M reduces tin oxide as described above at the time of sintering, it is present as an oxide phase (MOX) in the sputtering target.

Here, in the case where the sputtering target according to the present embodiment contains the metal element M, tin oxide can be obtained by setting M / (Zn + Sn + M) at an atomic ratio of 0.001 or more as the content of the metal element M. It can be reduced to form a metal tin phase sufficiently. On the other hand, by setting M / (Zn + Sn + M) at 0.05 or less in atomic ratio, the influence on the characteristics of the film to be formed can be suppressed.
From the above, when the metal element M is contained in the present embodiment, M / (Zn + Sn + M) is preferably in the range of 0.001 or more and 0.05 or less in atomic ratio.
The lower limit of M / (Zn + Sn + M) is preferably 0.0015 or more, and more preferably 0.002 or more. On the other hand, the upper limit of M / (Zn + Sn + M) is preferably 0.01 or less, and more preferably 0.008 or less.

(Method of manufacturing sputtering target)
Next, a method of manufacturing the sputtering target according to the present embodiment will be described with reference to the flow chart of FIG.
First, raw material powder containing zinc oxide powder and tin oxide powder is prepared (raw material powder preparation step S01). In the present embodiment, stannic oxide (SnO ₂ ) powder is used as the tin oxide powder.
Here, as raw material powder, metal zinc powder or powder of metal element M is included to reduce tin oxide to form a metal tin phase. That is, as raw material powder, (1) zinc oxide powder + tin oxide powder + metallic zinc powder, (2) zinc oxide powder + tin oxide powder + powder of metal element M, (3) zinc oxide powder + tin oxide powder + It can be mixed in the pattern of metallic zinc powder + metallic element M powder. Then, the weighed raw material powders are mixed using a ball mill or the like.

The mixed raw material powder is filled in a forming die, heated while being pressurized to sinter and obtain a sintered body (sintering step S02).
The sintering temperature at this time is within the range of 950 ° C. to 1200 ° C., the holding time at the sintering temperature is within the range of 180 min to 300 min, and the pressurizing pressure is within the range of 20 MPa to 40 MPa. preferable. Further, the atmosphere is preferably a vacuum atmosphere (20 Pa or less).

In the sintering step S02, the metallic tin (or metallic element M) reduces tin oxide, whereby the metallic tin phase is uniformly formed without segregation. That is, in the present embodiment, the metal tin phase is formed by reactive sintering.
By reactive sintering in this manner, the average equivalent circle diameter of the observed metal tin phase becomes 1 μm or less. In addition, the relative density is improved by filling the metal tin phase between the oxide phases.
The sintering temperature is set to a temperature exceeding the melting point (419.5 ° C.) of zinc metal. However, zinc metal becomes zinc oxide in the process of sintering, so melting out of zinc metal is suppressed. In addition, although the sintering temperature is set to a temperature exceeding the melting point (231.9 ° C.) of metal tin, the melting of metal tin is suppressed because the metal tin phase is finely formed in the process of sintering. Be done.

Next, the obtained sintered body is machined (machining step S03). Thereby, the sputtering target which is this embodiment is manufactured.

In the sputtering target according to the present embodiment configured as described above, the main phase is a tin oxide phase and a tin-zinc complex oxide phase, and the metal tin phase is observed, which is observed. Since the average value of the equivalent circle diameter of the phase is 1 μm or less, the metal tin phase is uniformly present without segregation, and the occurrence of abnormal discharge at the time of sputtering can be suppressed. In addition, the metal tin phase is sufficiently filled between the oxide phases to be the matrix phase, and the relative density can be improved. Furthermore, even when the temperature rises at the time of sputtering, it is possible to suppress the occurrence of cracking of the target surface due to thermal expansion.

Further, in the sputtering target according to the present embodiment, the relative density is set to 95% or more, so that the number of voids is small, and the occurrence of abnormal discharge at the time of sputtering can be suppressed. In addition, the occurrence of cracking at the time of sputtering can be suppressed.
Furthermore, in the sputtering target according to the present embodiment, Zn and Sn are contained so that Zn / (Zn + Sn) in the atomic ratio is in the range of 0.1 or more and 0.6 or less. An oxide film excellent in reflection characteristics can be formed.

Further, in the sputtering target according to the present embodiment, since the amount of Sn present as the metal tin phase is 1.0 mol% or more, the specific resistance value is sufficiently low, and the oxide film is stabilized by DC sputtering. It becomes possible to form a film.
On the other hand, since the amount of Sn present as the metal tin phase is 8.0 mol% or less, the metal tin phase does not exist more than necessary, and it is possible to suppress melting of the metal when heated in the manufacturing process, which is stable The sputtering target can be manufactured. In addition, even when the temperature rises during sputtering, the occurrence of cracks on the surface of the target due to thermal expansion can be suppressed.

Further, in the case where the sputtering target according to the present embodiment further includes an oxide of one or more metal elements M selected from Cr, V, Si, Ti, Al, and Zr, the metal element M The metal tin phase described above can be formed by reducing tin oxide by Therefore, the specific resistance value is sufficiently low, and the oxide film can be stably formed by DC sputtering.

Further, in the sputtering target according to the present embodiment, the metal element M is oxidized by the metal element M by containing the metal element M so that M / (Zn + Sn + M) is in the range of 0.001 or more and 0.05 or less. Tin can be reliably reduced to form a metal tin phase, the specific resistance value is sufficiently low, an oxide film can be stably formed by DC sputtering, and the formed oxide is formed. It becomes possible to maintain various characteristics in the object film.

Further, in the present embodiment, as the raw material powder, zinc oxide powder and tin oxide powder (SnO ₂ powder) and / or metal zinc powder or metal element M powder are included, and in the sintering step S02 Since reaction sintering is performed to reduce tin oxide with metal zinc or metal element M to form a metal tin phase, the metal tin phase can be uniformly formed without segregation, and the sintering temperature Even if it is set high, melting of metal can be suppressed. Specifically, the sintering temperature in the sintering step S02 can be set to a relatively high temperature condition within the range of 950 ° C. or more and 1200 ° C. or less. This makes it possible to obtain a sputtering target with a high relative density.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, in the present embodiment, when the metal element M further includes one or two or more metal elements selected from Cr, V, Si, Ti, Al, and Zr, the content of the metal element M can be M / A in atomic ratio. Although (Zn + Sn + M) is described to be in the range of 0.001 or more and 0.05 or less, it is not limited to this, and in the case where the metal tin phase is sufficiently formed by metal zinc, the atomic ratio And M / (Zn + Sn + M) may be contained at a level of less than 0.001. In addition, M / (Zn + Sn + M) may exceed 0.05 in atomic ratio depending on the characteristics required for the film formed.

Below, the result of the confirmation experiment performed in order to confirm the effectiveness of this invention is demonstrated.

(Sputtering target)
As raw material powder, zinc oxide powder (ZnO powder: purity 99.9 mass% or more, average particle diameter 10.0 μm), tin oxide powder (SnO ₂ powder: purity 99.99 mass% or more, average particle diameter 25 μm), metal Zinc powder (metal Zn powder: purity of at least 99 mass%, average particle diameter 4.0 μm) was prepared. In addition, as metal element M, metal aluminum powder (metal Al powder: purity 99.9 mass% or more, average particle diameter 46.0 μm), and metal zirconium powder (metal Zr powder: purity 98 mass% or more, average particle diameter 10 μm) Prepared. Furthermore, metal tin powder (metal Sn powder: purity of 99 mass% or more, average particle diameter 15.0 μm) and tin oxide powder (SnO powder: purity of 99 mass% or more, average particle diameter 25 μm) used in the comparative example Got ready.

These raw materials were weighed so as to obtain the molar ratio described in Table 1, and the weighed raw materials and a zirconia ball (diameter: 3 times the weight of the raw materials were put into a polyethylene pot under an Ar gas atmosphere. 5 mm) was charged and dry mixed for 8 hours by a ball mill. After mixing, the mixture was sieved to separate zirconia balls and mixed powder.
The obtained mixed powder is charged into a mold made of carbon, and applied under the conditions of sintering temperature shown in Table 1, holding time at sintering temperature of 4 hours, and pressure of 35 MPa in a vacuum atmosphere. The pressure sintering was performed to obtain a sintered body.
The obtained sintered body was machined to produce a sputtering target (126 mm × 178 mm × 6 mm) for evaluation. And it evaluated about the following items.

(Melting of metal)
The presence or absence of dissolution of the metal (Sn or Zn) during sintering was confirmed by visual observation of the sputtering target after sintering. The evaluation results are shown in Table 1. In addition, when the melting out of metal was recognized, the sputter | spatter test mentioned later was not implemented.

(Composition of sputtering target)
A measurement sample was collected from the obtained sputtering target, and the collected measurement sample was crushed to obtain a powder for measurement. This powder for measurement is measured by a powder X-ray diffractometer (D8 ADVANCE manufactured by Bruker AXS) and analyzed by Rietveld method (analysis software: TOPAS (version 5) manufactured by Bruker AXS) The composition of the sputtering target was calculated. The measurement results are shown in Tables 2 and 3. The measurement conditions were as follows.
Source: Cu
Tube voltage: 40kV
Tube current: 40 mA
Scanning range: 15 to 128 deg
Step width: 0.01 deg

(Average value of equivalent circle diameter of metal tin phase)
An observation sample was taken from the sputtering target, and after cross-section polishing, EPMA observation (magnification: 1000) was performed to identify the metal tin phase from elemental mapping. And the equivalent circle diameter of the observed metal tin phase was calculated | required using image analysis software: Winroof, and the average value of the equivalent circle diameter was computed.
The measurement results are shown in Table 3.
Here, an example of the EPMA image is shown in FIG. In the EPMA image of FIG. 1, the white part is the metal tin phase, the gray part is the tin oxide phase (SnO ₂ ), and the black part is the tin-zinc complex oxide phase (Zn ₂ SnO ₄ ).
In the EPMA image shown in FIG. 1, since the gray part and the black part occupy the main part, in the sputtering target of the present invention, the tin oxide phase and the tin-zinc complex oxide phase exist as the main phase. I understand that Further, since the minute white parts smaller than the gray part and the black part are scattered and present, the sputtering target of the present invention has a metal tin phase, and the average equivalent circle diameter of the metal tin phase is 1 μm or less It turns out that it is an extent.

(Relative density)
"Theoretical density" was calculated by the method described in the column of the embodiment. Moreover, the value which divided the weight of the obtained sputtering target by the volume obtained from the dimension was made into "measurement density."
The theoretical density ratio was calculated by the following equation using this theoretical density and the measured density of the obtained sputtering target. The measurement results are shown in Table 3.
Relative density (%) = (measured density) / (theoretical density) x 100

(Resistance value)
The resistivity value of the sputtering target was measured by a resistance measuring device. It measured by the four-point probe method using the low resistivity meter (Loresta-GP) made from Mitsubishi Chemical Co., Ltd. as a resistance measurement apparatus. The temperature at the time of measurement was 23 ± 5 ° C., and the humidity was 50 ± 20%. The measurement results are shown in Table 3.

(Number of abnormal discharges)
After bonding the prepared sputtering target to a backing plate, film formation by sputtering is performed under the following conditions using the sputtering target, and the film is provided in a DC power supply (HPK06Z-SW6 manufactured by Kyosan Sangyo Co., Ltd.) The number of abnormal discharges was counted by the arc count function. The measurement results are shown in Table 3.
Power supply: DC
Power: 4.08 W / cm ²
Total pressure: 0.67 Pa
Gas atmosphere: Ar 90% + O 210%
Achieved vacuum degree: 7.0 × ^10-4 Pa
Board distance: 60 mm
Time: 20 minutes

In Comparative Example 1 in which the amount of Sn contained as the metal tin phase was 0.83 mol%, the specific resistance value was high and DC sputtering could not be performed. Also, the relative density was less than 95%.
In Comparative Example 2 in which the amount of Sn contained as the metal tin phase was 11.75 mol%, melting of the metal was observed at the time of sintering. For this reason, the sputter test was not performed. Also, the relative density was less than 95%.
In Comparative Example 3 containing no tin oxide phase and containing a large amount of metallic zinc phase, dissolution of metal was observed at the time of sintering. For this reason, the sputter test was not performed. Also, the relative density was less than 95%.

In Comparative Example 4 in which metal tin powder is used as a raw material and the amount of Sn contained as a metal tin phase is set to 10.58 mol%, the average equivalent circle diameter of the metal tin phase exceeds 1.32 μm and 1 μm. It was In addition, melting of metal was observed at the time of sintering. For this reason, the sputter test was not performed. Furthermore, the relative density was less than 95%.
In Comparative Example 5 in which metal tin powder is used as the raw material and the amount of Sn contained as the metal tin phase is 0.54 mol%, the average equivalent circle diameter of the metal tin phase exceeds 1.29 μm and 1 μm. It was In addition, the specific resistance value was high, and DC sputtering could not be performed. Furthermore, the relative density was less than 95%.

In Comparative Example 6 in which the sintering temperature was set to 400 ° C., the metal tin phase was not formed, and the metal zinc phase was formed. It is speculated that tin oxide could not be reduced by zinc metal. In addition, in Comparative Example 6, melting of metal was observed. For this reason, the sputter test was not performed. Furthermore, the relative density was less than 95%.
In Comparative Example 7 in which powder of stannous oxide (SnO) was used as tin oxide powder, a tin oxide phase (SnO ₂ phase) was not formed, and a large amount of metal tin phase was formed. Moreover, the average value of the circle equivalent diameter of the metal tin phase was over 3.55 μm and 1 μm. Furthermore, melting of metal (Sn) was observed at the time of sintering. For this reason, the sputter test was not performed. Also, the relative density was less than 95%.

On the other hand, although metal tin powder was not used as a raw material in the invention examples 1-10, a metal tin phase was formed in the structure after sintering. It is presumed that a metal tin phase is formed by reduction of part of tin oxide by the metal zinc powder used as a raw material and the metal powder of element M. For this reason, even if the sintering temperature is set high, melting out of the metal was not confirmed at the time of sintering.
Further, in the examples 1-10 of the invention, since the sintering temperature is sufficiently high, the relative density is also as high as 95% or more.

Furthermore, in Inventive Example 1-10, the average equivalent circle diameter of metal tin in the target is 1 μm or less, and the metal tin phase is uniformly dispersed without segregation, and the specific resistance value is Was low enough. As a result, the number of occurrences of abnormal discharge at the time of sputtering is also suppressed, and DC sputtering can be stably performed.

Moreover, in the invention examples 8 and 9, although Al is added as the metal element M, melting out of metal was not confirmed at the time of sintering even if the sintering temperature was set high. Furthermore, the average equivalent circle diameter of metal tin in the target was 1 μm or less, the metal tin phase did not segregate and was uniformly dispersed, and the specific resistance value was sufficiently low. Furthermore, the relative density also increased to 95% or more.
Furthermore, in the invention example 10, Zr is added as the metal element M, but the average value of the circle equivalent diameter of metal tin in the target is 1 μm or less, and the metal tin phase is not segregated and It was dispersed uniformly, and the specific resistance value was sufficiently low. Furthermore, the relative density also increased to 95% or more.

As described above, according to the example of the present invention, it is possible to provide a sputtering target which can suppress the occurrence of abnormal discharge and can stably perform DC sputtering with a low specific resistance value. confirmed.

It becomes possible to more efficiently form an oxide film mainly composed of Zn, Sn and O used for a heat shielding film such as window glass or an infrared filter.

Claims

Containing Zn, Sn, and O as main components and containing Zn and Sn in an atomic ratio such that Zn / (Zn + Sn) is in the range of 0.1 or more and 0.6 or less,
While having a tin oxide phase and a tin-zinc complex oxide phase as main phases, it has a metal tin phase,
The amount of Sn present as the metal tin phase is in the range of 1.0 mol% or more and 8.0 mol% or less,
The average value of the circle equivalent diameter of the metal tin phase is 1 μm or less,
A sputtering target characterized by having a relative density of 95% or more.
The sputtering target according to claim 1, further comprising an oxide of one or more metal elements M selected from Cr, V, Si, Ti, Al and Zr.
The sputtering target according to claim 2, wherein the metal element M is contained such that M / (Zn + Sn + M) is in the range of 0.001 or more and 0.05 or less in atomic ratio.