WO2019155577A1

WO2019155577A1 - Oxide sputtering target and method for producing oxide sputtering target

Info

Publication number: WO2019155577A1
Application number: PCT/JP2018/004430
Authority: WO
Inventors: 野中　荘平; 理恵森; 昌芳長尾
Original assignee: 三菱マテリアル株式会社
Priority date: 2018-02-08
Filing date: 2018-02-08
Publication date: 2019-08-15
Also published as: KR102115126B1; KR20190096974A; CN110352263A

Abstract

This oxide sputtering target is formed of an oxide containing zirconium, silicon, and indium as metal components, and is characterized in that, in a target plane, the difference between the maximum and minimum oxygen concentrations as a percentage of the total of the maximum and the minimum oxygen concentrations is 15% or less.

Description

Oxide sputtering target and manufacturing method of oxide sputtering target

The present invention relates to an oxide sputtering target containing zirconium oxide, silicon dioxide, and indium oxide, and a method for manufacturing the oxide sputtering target.

As the information recording medium, phase change optical discs such as DVD and BD [Blu-ray (registered trademark) Disc] are known. These phase change optical disks are generally a laminate in which a plurality of layers such as a dielectric layer, a recording layer, a dielectric layer, and a reflective layer are laminated on a substrate. A sputtering method is widely used as a method for forming each layer. A phase-change optical disc records information by irradiating a recording laser beam onto an optical recording medium to cause a phase change of a recording layer.

An oxide film containing zirconium oxide, silicon dioxide, and indium oxide is used as a dielectric layer and a protective layer of a phase change optical disk (Patent Documents 1 and 2).
Patent Document 2 contains, as a sputtering target for forming an optical recording medium protective film, mol%, zirconium oxide: 10 to 70%, silicon dioxide: 50% or less (not including 0%), and the balance: indium oxide. And an oxide sputtering target having a composition comprising inevitable impurities. In Patent Document 2, as a method for producing this oxide sputtering target, a predetermined amount of ZrO ₂ powder, amorphous SiO ₂ powder and In ₂ O ₃ powder are weighed and uniformly mixed with a Henschel mixer, and then this mixed powder is used. A method is described in which press molding is performed, and the obtained molded body is fired and sintered in an oxygen atmosphere.

Japanese Patent No. 4567750 (B) Japanese Patent No. 5088464 (B)

In phase change type optical discs, recording pits and track pitches are becoming finer as the recording density increases, and management of foreign matters is becoming stricter. Therefore, in an oxide sputtering target used for manufacturing a phase change optical disk, it is required that particles are not easily scattered.

However, in the method for producing an oxide sputtering target described in Patent Document 2, oxygen in the firing atmosphere may be insufficient during firing of the molded body. When the molded body is fired in a state where oxygen in the firing atmosphere is insufficient, the oxygen concentration in the resulting oxide sputtering target becomes non-uniform. And when the variation of oxygen concentration in the target plane of the oxide sputtering target becomes large, the specific resistance in the target plane becomes non-uniform and the potential concentrates on a specific location, causing abnormal discharge during sputtering. It has been found that the problem arises that particles are scattered by the abnormal discharge.

The present invention has been made in view of the above-described circumstances, and includes an oxide sputtering target that can suppress the occurrence of abnormal discharge during sputtering and particle scattering, and a method for manufacturing the oxide sputtering target. The purpose is to provide.

In order to solve the above problems, the oxide sputtering target of the present invention is an oxide sputtering target made of an oxide containing zirconium, silicon and indium as metal components, and has a maximum oxygen concentration in the target plane. The ratio of the difference between the maximum value and the minimum value of the oxygen concentration with respect to the sum of the value and the minimum value is 15% or less.

According to the oxide sputtering target of the present invention configured as described above, the maximum value and the minimum value of the oxygen concentration in the target surface satisfy the above-described relationship. The variation is suppressed. For this reason, since the uniformity of the oxygen concentration in the target surface is high and the specific resistance in the target surface becomes uniform, abnormal discharge during sputtering is suppressed, and generation of particles is suppressed accordingly.

Here, in the oxide sputtering target of the present invention, the ratio of the difference between the maximum value and the minimum value of the specific resistance to the sum of the maximum value and the minimum value of the specific resistance in the target surface is preferably 15% or less. .

In this case, since the variation in specific resistance within the target surface is suppressed within the above range, abnormal discharge during sputtering is further suppressed, and the generation of particles is reliably suppressed along with this.

The method for producing an oxide sputtering target according to the present invention is a method for producing the above-described oxide sputtering target, in which a zirconium oxide powder, a silicon dioxide powder, and an indium oxide powder are mixed to have a specific surface area of 11. A step of obtaining a mixed powder of 5 m ² / g or more and 13.5 m ² / g or less, a step of forming the mixed powder to obtain a molded body, and the molded body 1300 while circulating oxygen in a firing apparatus. A step of producing a sintered body by firing at a temperature of from 1 ° C. to 1600 ° C., and at least 600 ° C. at a cooling rate of 200 ° C./hour or less while circulating oxygen through the sintered body. And a step of cooling to the following temperature.

According to the manufacturing method of the oxide sputtering target having this configuration, the mixed powder obtained by mixing the zirconium oxide powder, the silicon dioxide powder, and the indium oxide powder as a raw material has a specific surface area of 11.5 m ² / g or more and 13.5 m ² / Since it is set to g or less, the reactivity is high. In addition, since the molded body is fired while oxygen is circulated in the firing apparatus, there is no shortage of oxygen in the firing atmosphere, so that the molded body is sintered uniformly, and the dense and high-density fire is obtained. A ligation can be obtained. And since the sintered compact is cooled at the cooling rate of 200 degrees C / hr or less, a rapid temperature change does not occur easily and the oxygen concentration of a sintered compact is stabilized. Therefore, an oxide sputtering target with small variation in oxygen concentration in the target surface can be stably manufactured.

According to the present invention, it is possible to provide an oxide sputtering target that can suppress the occurrence of abnormal discharge and the scattering of particles during sputtering, and a method for manufacturing the oxide sputtering target.

It is explanatory drawing which shows the measurement position of the oxygen concentration and specific resistance in the oxide sputtering target which concerns on one Embodiment of this invention. It is a flowchart which shows the manufacturing method of the oxide sputtering target which concerns on one Embodiment of this invention. It is explanatory drawing explaining the position which measured In density | concentration of the oxide film formed in the Example.

Hereinafter, an oxide sputtering target according to an embodiment of the present invention will be described with reference to the accompanying drawings.
The oxide sputtering target according to this embodiment can be used, for example, when an oxide film used as a dielectric layer and a protective layer of a phase change optical disk such as DVD or BD is formed by a sputtering method. The oxide sputtering target of this embodiment can also be used when an oxide film used as an underlayer and a protective layer of a magnetic recording medium such as an HDD (hard disk drive) is formed by a sputtering method.

The oxide sputtering target of this embodiment is made of an oxide containing zirconium, silicon, and indium as metal components. The contents of zirconium, silicon and indium are not particularly limited, and can be the same as the oxide used as a conventional sputtering target for forming an optical recording medium protective film. In this embodiment, the total content of the metal components is 100% by mass, the zirconium content is set in the range of 10% by mass to 75% by mass, and the silicon content is 35% by mass or less (however, 0% by mass). %), And the indium content is set as the balance. A part of zirconium, silicon and indium may each form a composite oxide. As an example of the composite oxide, In ₂ Si ₂ O ₇ can be given.

The oxide sputtering target of this embodiment is a ratio of the difference between the maximum value and the minimum value of the oxygen concentration with respect to the sum of the maximum value and the minimum value of the oxygen concentration in the target surface, that is, oxygen represented by the following formula (1). The density variation is 15% or less.

Formula (1):
Variation in oxygen concentration (%) = [(maximum value of oxygen concentration) − (minimum value of oxygen concentration)] / [(maximum value of oxygen concentration) + (minimum value of oxygen concentration)] × 100

Furthermore, the oxide sputtering target of this embodiment is represented by the ratio of the difference between the maximum value and the minimum value of the specific resistance with respect to the sum of the maximum value and the minimum value of the specific resistance in the target surface, that is, the following formula (2). The specific resistance variation is 15% or less.

Formula (2):
Variation in specific resistance = [(maximum specific resistance) − (minimum specific resistance)] / [(maximum specific resistance) + (minimum specific resistance)] × 100

Hereinafter, the reason why the variation in oxygen concentration and specific resistance of the oxide sputtering target of this embodiment is defined as described above will be described.

(Oxygen concentration variation)
When the variation in the oxygen concentration of the oxide sputtering target becomes large, abnormal discharge and particles are likely to occur during sputtering. For this reason, in the oxide sputtering target of this embodiment, the variation of the oxygen concentration in the target surface represented by the above formula (1) is set to 15% or less. If the variation in oxygen concentration exceeds 15%, abnormal discharge and particles are generated, and foreign matter may adhere to the surface of the deposited oxide film, and the in-plane variation of the film composition may increase. Note that the oxygen concentration of the oxide sputtering target varies depending on the contents of zirconium, silicon, and indium, but is preferably in the range of 15% by mass to 35% by mass. The oxygen concentration can be measured by EPMA or gas analysis.

Here, the variation of the oxygen concentration in the target surface is calculated by the above equation (1) by measuring the oxygen concentration at a plurality of locations in the target surface, extracting the maximum value and the minimum value of the measured oxygen concentration. To do. The number of oxygen concentration measurement points is preferably 5 or more. Here, in this embodiment, when the oxide sputtering target is disk-shaped, as shown in FIG. 1, at the center point (1) of the target surface (circle) and the center point of the target surface. Measure the oxygen concentration at 5 points in total (4 points (2) to (5)) on two straight lines perpendicular to each other and 20 mm from the outer edge, and the maximum and minimum values of the measured oxygen concentration To extract the variation in oxygen concentration.
When the oxide sputtering target has a cylindrical shape, the oxygen concentration is measured at a total of five points located 20 mm from the outer edge and at equal intervals in the circumferential direction, and the maximum and minimum values of the measured oxygen concentration are determined. Extraction can be performed to determine variation in oxygen concentration.

(Resistivity variation)
When the variation in specific resistance of the oxide sputtering target is increased, abnormal discharge and particles are likely to occur during sputtering. For this reason, in the oxide sputtering target of this embodiment, the variation of the specific resistance in the target surface represented by the above formula (2) is set to 15% or less. If the variation in specific resistance exceeds 15%, abnormal discharge and particles are generated, and foreign matter may adhere to the surface of the deposited oxide film, and the in-plane variation of the film composition may increase. Note that the specific resistance of the oxide sputtering target is preferably 0.1 Ω · cm or less.

Here, the variation of the specific resistance in the target surface is calculated by the above formula (2) by measuring the specific resistance at a plurality of locations in the target surface, extracting the maximum value and the minimum value of the measured specific resistance. To do. It is preferable that the specific resistance is measured at five or more locations. Here, in this embodiment, when the oxide sputtering target is disk-shaped, as shown in FIG. 1, at the center point (1) of the target surface (circle) and the center point of the target surface. The specific resistance is measured at a total of five points (4) (2) to (5) on two straight lines orthogonal to each other and 20 mm from the outer edge, and the maximum and minimum values of the measured specific resistance are measured. To extract the variation in specific resistance.
When the oxide sputtering target has a cylindrical shape, the specific resistance is measured at a total of five points located 20 mm from the outer edge and at equal intervals in the circumferential direction, and the maximum and minimum values of the measured specific resistance are measured. By extracting, it is possible to determine the variation in specific resistance.

Next, the manufacturing method of the oxide sputtering target which concerns on this embodiment is demonstrated with reference to the flowchart of FIG.
As shown in FIG. 2, the manufacturing method of the oxide sputtering target according to the present embodiment includes a pulverizing and mixing step S01 for pulverizing and mixing the raw material powder, and a forming step S02 for forming the pulverized and mixed mixed powder into a predetermined shape. It includes a sintering step S03 for sintering the molded body, a cooling step S04 for cooling the obtained sintered body, and a processing step S05 for processing the cooled sintered body.

As the raw material powder, ZrO ₂ powder, SiO ₂ powder, and In ₂ O ₃ powder are prepared. The ZrO ₂ powder preferably has a purity of 99.9% by mass or more and an average particle size of 0.2 μm or more and 20 μm or less. The SiO ₂ powder preferably has a purity of 99.8% by mass or more and an average particle size of 0.2 μm or more and 20 μm or less. The In ₂ O ₃ powder preferably has a purity of 99.9% by mass or more and an average particle size of 0.1 μm or more and 10 μm or less.

(Crushing and mixing step S01)
When the total content of the metal components in the obtained mixed powder is 100% by mass, the zirconium content is in the range of 10% to 75% by mass, and the silicon content is 35% by mass. Below (however, 0 mass% is not included), it is weighed so that the content of indium is the balance, and pulverized and mixed. In this embodiment, the pulverization and mixing are performed by wet pulverization and mixing using a bead mill apparatus using zirconia balls having a diameter of 0.5 mm as a pulverization medium.
In this pulverization and mixing step S01, the mixed powder obtained is pulverized and mixed so that the specific surface area (BET specific surface area) is 11.5 m ² / g or more and 13.5 m ² / g or less. By using a mixed powder having a specific surface area in the above range, in the sintering process described later, reactivity with atmospheric oxygen and sinterability are enhanced, and a uniform oxygen concentration, specific resistance, and high sintering density are obtained. It becomes easy to obtain a sputtering target. On the other hand, when a mixed powder having a specific surface area of less than 11.5 m ² / g is used, a uniform reaction does not occur at the time of firing, and there is a possibility that variation in the oxygen concentration of the sputtering target becomes large. Moreover, if the specific surface area of the mixed powder is pulverized so as to exceed 13.5 m ² / g, the pulverization and mixing time becomes longer, which may be disadvantageous economically.

(Molding step S02)
Next, the mixed powder obtained in the pulverization and mixing step S01 is molded into a predetermined shape to obtain a molded body. In this embodiment, it shape | molds using press molding.

(Sintering step S03)
Next, the molded body molded in the molding step S02 is sintered. In the sintering step S03, the molded body is fired and sintered while introducing oxygen into the inside using a firing device having an oxygen inlet. Since the sublimation of the In ₂ O ₃ powder in the mixed powder is suppressed by performing the firing of the molded body while introducing oxygen into the firing apparatus, it has a uniform oxygen concentration, a specific resistance, and a high sintering density. It becomes easy to obtain a sputtering target. The optimum flow rate of oxygen introduced into the firing apparatus varies depending on conditions such as the internal volume of the firing apparatus and the size and quantity of the compact to be sintered, so it is necessary to select appropriately. For example, as a guideline, the flow rate required for simultaneously firing 6 or less of a compact having a diameter of 100 to 300 mm and a thickness of 15 mm or less in a firing apparatus having an internal volume of 15000 to 30000 cm ³ is in the range of 3 L / min to 10 L / min. . A flow rate exceeding 10 L / min is generally not economically desirable. The gas to be circulated in the firing apparatus is preferably 100% oxygen, that is, pure oxygen. However, if the oxygen volume ratio is 80% or more, a gas mixed with other gas such as nitrogen or argon is used. Also good.

The holding temperature during firing is preferably in the range of 1300 ° C or higher and 1600 ° C or lower. When the temperature is lower than 1300 ° C., the sintered body is difficult to be dense and the density may be lowered. It is generally not economically preferable to use temperatures above 1600 ° C. for normal production. The heating rate during firing is preferably 200 ° C./hour or less, and more preferably in the range of 10 ° C./hour to 200 ° C./hour. If it exceeds 200 ° C./hour, uneven reaction, sintering and shrinkage between the raw material powders may occur, which may cause warping and cracking. On the other hand, if it is less than 10 ° C./hour, it takes too much time and the productivity may be lowered.

(Cooling step S04)
Next, the sintered body obtained in the sintering step S03 is cooled. In this cooling step S04, the sintered body is cooled while introducing oxygen into the firing apparatus until the temperature reaches at least 600 ° C. or less. By cooling the sintered body while introducing oxygen into the firing apparatus, the release of oxygen in the sintered body during cooling is suppressed, and a sputtering target having a uniform oxygen concentration and specific resistance is obtained. It becomes easy. The flow rate of oxygen introduced into the firing apparatus is preferably the same as the flow rate introduced into the firing apparatus in the sintering step S03. The circulation of oxygen in the cooling step S04 is preferably performed until the sintered body is taken out, but may be appropriately stopped when the temperature reaches 600 ° C. or less in consideration of economy.

The cooling rate when cooling to a temperature of 600 ° C. or lower is preferably 200 ° C./hour or less, and more preferably in the range of 1 ° C./hour to 200 ° C./hour. When it exceeds 200 ° C./hour, cooling of the sintered body is difficult to proceed uniformly, and the uniformity of the oxygen concentration is impaired, and the sintered body may be easily cracked by thermal stress. On the other hand, if it is less than 1 ° C./hour, it takes too much cooling time and the productivity may be lowered. The cooling rate is preferably constant throughout the cooling step S04, but may be appropriately changed during the cooling in the range of 200 ° C./hour or less. Further, after cooling to 600 ° C. or lower, cooling may be performed at a cooling rate exceeding 200 ° C./hour, but the operation of taking out the sintered body from the firing apparatus is preferably performed at a temperature of 100 ° C. or lower.

(Processing step S05)
In the processing step S05, the sintered body cooled in the cooling step S05 is processed into a predetermined shape sputtering target by cutting or grinding.

According to the oxide sputtering target according to the present embodiment configured as described above, the variation in the oxidation concentration in the target surface is 15% or less, so the uniformity of the oxygen concentration in the target surface is high. The specific resistance in the target plane becomes uniform. For this reason, abnormal discharge during sputtering is suppressed, and the generation of particles is suppressed accordingly.

Moreover, according to the manufacturing method of the oxide sputtering target of this embodiment, in the crushing and mixing step S01, the mixed powder obtained by crushing and mixing the ZrO ₂ powder, the SiO ₂ powder, and the In ₂ O ₃ powder, which are raw materials, Since the specific surface area is 11.5 m ² / g or more and 13.5 m ² / g or less, the reactivity is high. Further, in the sintering step S03, the molded body is fired while introducing oxygen into the firing apparatus, and oxygen in the firing atmosphere is not insufficient, so that the sintered body of the molded body becomes uniform, A dense and dense sintered body can be obtained. And in cooling process S04, since it cools with the cooling rate of 200 degrees C / hour or less, a rapid temperature change does not occur easily and the oxygen concentration of a sintered compact is stabilized. Therefore, an oxide sputtering target with small variation in oxygen concentration in the target surface can be stably manufactured.

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, the case where the shape of the oxide sputtering target is a disk shape has been described, but the shape of the oxide sputtering target is not particularly limited. The oxide sputtering target may be a square plate. When the shape of the oxide sputtering target is a square plate, the oxygen concentration and specific resistance measurement points should be a total of five points: the intersection where the diagonal lines intersect and the four points near the corners on each diagonal line. it can.
The oxide sputtering target may be cylindrical. When the shape of the oxide sputtering target is cylindrical, the oxygen concentration and specific resistance can be measured at a total of five points at equal intervals in the circumferential direction.

Moreover, the oxide sputtering target of this embodiment may contain inevitable impurities. Here, the inevitable impurities mean impurities inevitably contained in the raw material powder and impurities inevitably mixed in the manufacturing process.

Furthermore, according to the manufacturing method of the oxide sputtering target of this embodiment, in the crushing and mixing step S01, the raw material ZrO ₂ powder, the SiO ₂ powder, and the In ₂ O ₃ powder are pulverized and mixed. It is good. However, the mixed powder obtained by mixing needs to have a specific surface area of 11.5 m ² / g or more and 13.5 m ² / g or less.

Hereinafter, the results of an evaluation test for evaluating the function and effect of the oxide sputtering target according to the present invention will be described.

[Invention Examples 1 to 7]
As the raw material powder, a purity of 99.9% by mass or more and a ZrO ₂ powder having an average particle diameter of 2 μm, a purity of 99.8% by mass or more and a SiO ₂ powder having an average particle diameter of 2 μm, and a purity of 99. 9% by mass or more of In ₂ O ₃ powder having an average particle diameter of 1 μm was prepared. Each prepared raw material powder was weighed so as to have a molar ratio shown in Table 1.

The weighed raw material powder was put into a bead mill using zirconia balls having a diameter of 0.5 mm as a grinding medium together with a solvent, and pulverized and mixed. As a solvent, Solmix A-11 manufactured by Nippon Alcohol Sales Co., Ltd. was used. The grinding / mixing time was 1 hour. After completion of the pulverization / mixing, zirconia balls were separated and recovered to obtain a slurry containing raw material powder and a solvent. The obtained slurry was heated and the solvent was removed to obtain a mixed powder.

The BET specific surface area of the obtained mixed powder was measured with a specific surface area measuring device (Mounttech, Macsorb model 1201). The results are shown in Table 1.

Next, the obtained mixed powder was filled in a mold having a diameter of 200 mm and pressed at a pressure of 150 kg / cm ² to produce two disk-shaped molded bodies having a diameter of 200 mm and a thickness of 10 mm. .
The obtained two molded bodies are put into an electric furnace (furnace volume 27000 cm ³ ), and maintained at the firing temperature shown in Table 1 for 7 hours while flowing oxygen through the electric furnace at a flow rate of 4 L / min. Was fired to produce a sintered body. Next, the sintered body was cooled to 600 ° C. at a cooling rate shown in Table 1 while oxygen was continuously passed through the electric furnace, and then the oxygen flow was stopped and cooled to room temperature by cooling in the furnace. Thereafter, the sintered body was taken out from the electric furnace.

The obtained sintered body was machined to obtain two disk-shaped sputtering targets having a diameter of 152.4 mm and a thickness of 6 mm.

[Comparative Example 1]
Two sputtering targets were produced in the same manner as in Example 1 except that the weighed raw material powders were mixed with a Henschel mixer.

[Comparative Example 2]
Two sputtering targets were produced in the same manner as Example 1 except that the cooling rate of the sintered body up to 600 ° C. was 250 ° C./hour.

[Comparative Example 3]
Two sputtering targets were produced in the same manner as in Example 1 except that oxygen was not circulated in the electric furnace when the molded body was fired.

[Comparative Example 4]
Two sputtering targets were produced in the same manner as in Example 1 except that the sintering temperature of the sintered body was 1250 ° C.

[Evaluation]
The metal component composition, relative density, oxygen content and specific resistance of the sputtering target were measured. Moreover, the sputtering test of the sputtering target was conducted.
One of the two produced sputtering targets was used for measurement of relative density, specific resistance, and oxygen content, and the remaining one was used for the sputtering test. In the sputtering test, first, the number of occurrences of abnormal discharge during sputtering was measured. Next, after forming an oxide film by sputtering, the presence or absence of cracks in the target was confirmed. Further, the indium concentration in the formed oxide film was measured.
The method of each evaluation is as follows.

(Metal component composition of sputtering target)
A part of the end of the sintered body before being machined into the sputtering target was sampled. The collected sample was dissolved in acid, and the composition of the obtained solution was analyzed by an inductively coupled plasma emission spectroscopy (ICP-OES) apparatus (Agilent 5100) manufactured by Agilent Technologies, and the metal component composition of Zr, Si, and In Was analyzed. The measurement results are shown in Table 2.

(Relative density)
The relative density was calculated as a ratio of the actual density to the theoretical density (actual density / theoretical density × 100). The actually measured density was obtained by actually measuring the weight and dimensions of the sputtering target. The theoretical density was calculated from the concentration and density of each oxide contained in the sputtering target. Specifically, the mass% concentration of ZrO ₂ is C1, the density is ρ1, the mass% concentration of SiO ₂ is C2, the density is ρ2, the mass% concentration of In ₂ O ₃ is C3, and the density is ρ3. The density ρ was calculated by the following formula.
ρ = 1 / [C1 / 100ρ1 + C2 / 100ρ2 + C3 / 100ρ3]
^{Here, ρ1 = 5.60g / cm 3,} ρ2 = 2.20g / cm 3, it was used a value of ρ3 = 7.18g / cm ^3. C1, C2, and C3 were calculated from the blending amount of the raw material powder.

(Specific resistance)
The specific resistance was measured by the four probe method. In order to measure the variation in specific resistance, as shown in FIG. 1, the center point (1) of the target surface (circle) and two straight lines orthogonal to each other at the center point of the target surface and the outer edge Measured at a total of 5 points of 4 points (2) to (5) located 20 mm from the center. The maximum value and the minimum value of the measured specific resistance were extracted, and the variation in specific resistance was calculated by the above equation (2). Table 2 shows measured values and variations of specific resistance at each measurement point.

(Oxygen concentration)
As shown in FIG. 1, the center point (1) of the target surface (circle) and four points (2) on two straight lines orthogonal to each other at the center point of the target surface and at a position 20 mm from the outer edge. ) To (5), a 10 mm square piece was cut out as a sample piece for measuring oxygen concentration, and the oxygen concentration on the surface (target surface) of the sample piece for measuring oxygen concentration was measured as follows.
First, the oxygen concentration measurement sample was embedded in a resin, and the surface (target surface) of the oxygen concentration measurement sample piece embedded in the resin was mirror-polished with a polishing apparatus. After polishing, the oxygen concentration on the polished surface was quantitatively analyzed by EPMA (JXA-8500F, manufactured by JEOL Ltd.). The conditions for quantitative analysis of oxygen by EPMA were as follows.
Acceleration voltage: 15 kV
Irradiation current: 5 × 10 ⁻⁸ A
Beam diameter: 100 μm
The spectral crystal used for the quantitative analysis of oxygen is LDE1.
The measurement was carried out at 10 locations at random from within a 10 mm square sample piece, and the average value was taken as the measurement value of the oxygen concentration at one location shown in FIG.
The maximum value and the minimum value of the five oxygen concentrations measured in FIG. 1 were extracted, and the variation in the oxygen concentration was calculated by the above equation (1). Table 2 shows the measured values and variations of the oxygen concentration of each oxygen concentration measurement sample.

(Spatter test)
The sputtering target was soldered to a backing plate made of oxygen-free copper, and this was mounted in a magnetron type sputtering apparatus (ULVAC, SIH-450H). Next, after the inside of the sputtering apparatus is evacuated to 5 × 10 ⁻⁵ Pa or less with a vacuum evacuation apparatus, Ar gas and O ₂ gas are introduced, the sputtering gas pressure is adjusted to 0.67 Pa, and pre-sputtering for 1 hour is performed. As a result, the processed layer on the target surface was removed. At this time, the flow ratio of Ar gas to O ₂ gas was 47: 3, the power was pulsed DC 1000 W, the pulse condition was frequency 50 kHz, and the duty ratio was 0.08.

(Number of abnormal discharges)
Continuous sputtering for 1 hour was performed under the same conditions as the pre-sputtering. The number of abnormal discharges that occurred during this one hour was measured using an arcing count function provided in the DC power supply of the used sputtering apparatus. The results are shown in Table 3.

(Oxide film formation and oxide film composition analysis)
After measuring the number of abnormal discharges described above, a 20 mm square polycarbonate substrate was pasted on a 6 inch diameter Si substrate at 5 points shown in FIG. 3 (one Si substrate center and 4 points with a radius of 60 mm from the center). Prepare a sample, put it in the sputtering device, let it stand just above the target, evacuate the inside of the sputtering device to 5 × 10 ⁻⁵ Pa or less with a vacuum evacuation device, and then perform sputtering under the same conditions as the above pre-sputtering And an oxide film having a thickness of 200 nm was formed on the substrate. The distance between the substrate and the target at this time was 70 mm. The composition of the solution obtained by dissolving each obtained oxide film with an acid was analyzed by an inductively coupled plasma emission spectroscopy (ICP-OES) apparatus (Agilent 5100) manufactured by Agilent Technologies, and the In concentration in each oxide film was determined. The variation was calculated from the following equation (3). Table 3 shows measured values and variations in the In concentration in the oxide film (mass% when the total content of metal elements is 100).

Formula (3):
Variation in In concentration of oxide film (%) = [(maximum value of In concentration) − (minimum value of In concentration)] / [(maximum value of In concentration) + (minimum value of In concentration)] × 100

(Presence or absence of cracks)
After the oxide film was formed, the sputtering apparatus was opened to the atmosphere. Then, the sputtering target was taken out from the sputtering apparatus, and the appearance was visually observed to confirm the occurrence of cracks. The results are shown in Table 3.

Comparative Example 1 in which the BET specific surface area of the mixed powder of the raw material powder was less than 11.5 m ² / g, Comparative Example 2 in which the cooling rate of the sintered body to 600 ° C. exceeded 200 ° C./hour, and firing the molded body The sputtering target obtained for both Comparative Example 3 fired without circulating oxygen in the apparatus and Comparative Example 4 where the firing temperature of the molded body was less than 1300 ° C. had a variation in oxygen concentration in the target plane. It was over 15%.

In the sputtering targets of Comparative Examples 1 to 4 in which the variation in oxygen concentration in the target surface exceeded 15%, the variation in specific resistance increased to 15% or more, and the number of abnormal discharges during sputtering increased. In addition, the oxide film formed by sputtering has a large variation in In concentration. In particular, the sputtering targets of Comparative Examples 2 and 4 were cracked after sputtering.

On the other hand, the BET specific surface area of the mixed powder of the raw material powder is in the range of 11.5 m ² / g to 13.5 m ² / g, and the cooling rate of the sintered body to 600 ° C. is 200 ° C./hour or less. In the sputtering targets of Examples 1 to 7 of the present invention, in which the compact was fired at a temperature of 1300 ° C. or higher and 1600 ° C. or lower while oxygen was passed through the baking apparatus, the variation in oxygen concentration in the target surface was all 15 % Or less.

In all of the sputtering targets of Invention Examples 1 to 7 in which the variation in oxygen concentration in the target surface was 15% or less, the variation in specific resistance was as low as 15% or less, and the number of abnormal discharges during sputtering was significantly reduced. did. In addition, variation in In concentration of the oxide film formed by sputtering was reduced. Furthermore, no cracks occurred after sputtering.

From the results of the above evaluation tests, according to the example of the present invention, there are provided an oxide sputtering target capable of suppressing the occurrence of abnormal discharge and the scattering of particles during sputtering, and a method for producing the oxide sputtering target. It was confirmed that it would be possible.

Claims

An oxide sputtering target made of an oxide containing zirconium, silicon and indium as a metal component, the difference between the maximum value and the minimum value of the oxygen concentration relative to the sum of the maximum value and the minimum value of the oxygen concentration in the target surface The oxide sputtering target is characterized by having a ratio of 15% or less.
2. The oxide sputtering target according to claim 1, wherein a ratio of a difference between the maximum value and the minimum value of the specific resistance to a total of the maximum value and the minimum value of the specific resistance in the target plane is 15% or less.
A method for producing the oxide sputtering target according to claim 1, comprising:
A step of mixing a zirconium oxide powder, a silicon dioxide powder, and an indium oxide powder to obtain a mixed powder having a specific surface area of 11.5 m 2 / g or more and 13.5 m 2 / g or less;
Molding the mixed powder to obtain a molded body;
Firing the molded body at a temperature of 1300 ° C. or higher and 1600 ° C. or lower while allowing oxygen to flow through the firing apparatus;
Cooling the sintered body to a temperature of at least 600 ° C. at a cooling rate of 200 ° C./hour or less while circulating oxygen in the firing apparatus;
A method for producing an oxide sputtering target, comprising: