TWI657159B - Oxide sputtering target and method of producing oxide sputtering target - Google Patents

Abstract

The present invention discloses an oxide sputtering target characterized in that an oxide sputtering target formed of an oxide containing a metal component of zirconium, hafnium and indium has a maximum and minimum oxygen concentration with respect to a target surface. In total, the ratio of the difference between the maximum value and the minimum value of the oxygen concentration is 15% or less.

Description

Oxide sputtering target and method for manufacturing oxide sputtering target

The present invention relates to an oxide sputtering target containing zirconia, ceria and indium oxide, and a method for producing an oxide sputtering target.

Known information recording media such as DVD, BD [Blu-ray (registered trademark) Disc] and the like. The phase change optical disc is generally a laminate of a plurality of layers such as a dielectric layer, a recording layer, a dielectric layer and a reflective layer laminated on a substrate. A sputtering method is widely used for the film formation method of each layer. The phase change optical disc records information by causing a phase change of the recording layer by irradiating the recording laser beam onto the optical recording medium.

The dielectric layer and the protective layer used for the phase change optical disc include an oxide film of zirconia and ceria and indium oxide (Patent Documents 1 and 2). Patent Document 2 discloses that a sputtering target for forming an optical recording medium protective film is composed of zirconia: nitrous oxide: 10 to 70%, cerium oxide: 50% or less (excluding 0%), and a residual portion having indium oxide. And an oxide sputtering target that is indispensable for the formation of impurities. Patent Document 2 describes that the oxide sputtering target is produced by weighing a predetermined amount of ZrO ₂ powder, amorphous SiO ₂ powder, and In ₂ O ₃ powder, and then uniformly mixing the mixture by a Hans mixer. The mixed powder is pressure-molded, and the obtained molded body is fired in an oxygen atmosphere to be sintered. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 4567750 (B) [Patent Document 2] Japanese Patent No. 5088464 (B)

[Problems to be solved by the invention]

As the phase change optical disc increases the recording density, the recording groove and the gauge are made finer, so the management of foreign matter mixing is more severe. Therefore, it is required that the oxide sputtering target used for manufacturing the phase change optical disc does not fly the microchip.

However, in the method for producing an oxide sputtering target described in Patent Document 2, oxygen in the baking environment is insufficient when the molded body is fired. When the molded body is fired in a state where oxygen is insufficient in the firing environment, the oxygen concentration in the obtained oxide sputtering target is not uniform. In addition, the deviation value of the oxygen concentration in the target surface of the oxide sputtering target is increased, and the specific resistance in the target surface is not uniform. As a result, the potential is concentrated in a specific portion, and abnormal discharge occurs in the sputtering target, so that it is determined. There will be problems with the scattering of microchips due to this abnormal discharge.

In view of the foregoing, it is an object of the present invention to provide an oxide sputtering target capable of suppressing occurrence of abnormal discharge and microchip scattering in a sputtering target, and a method of manufacturing the oxide sputtering target. [Method of solving the problem]

In order to solve the above problems, the oxide sputtering target of the present invention is characterized in that an oxide sputtering target formed of an oxide containing a metal component of zirconium, hafnium and indium has a maximum oxygen concentration with respect to a target surface. The ratio of the difference between the maximum value and the minimum value of the oxygen concentration is 15% or less in total with the minimum value.

Since the oxide sputtering target of the present invention thus constituted can satisfy the above relationship with the maximum value and the minimum value of the oxygen concentration in the target surface, the deviation value of the oxygen concentration in the target surface can be suppressed. Therefore, the uniformity of the oxygen concentration in the target surface can be improved, the specific resistance in the target surface can be made uniform, and the abnormal discharge in the sputtering and the occurrence of the scattering of the microchip can be suppressed.

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 is preferably 15% or less with respect to the total value and the minimum value of the specific resistance in the target surface.

Therefore, the deviation value of the specific resistance in the target surface is suppressed to the above range, so that abnormal discharge during sputtering can be further suppressed, and the occurrence of scattered microchip scattering can be surely suppressed.

The method for producing an oxide sputtering target according to the present invention is characterized in that the method for producing the above oxide sputtering target comprises mixing zirconia powder, cerium oxide powder and indium oxide powder to have a specific surface area of 11.5 m ² / a step of mixing the powder of g or more and 13.5 m ² /g or less, and a step of molding the mixed powder to obtain a molded body, and roasting the molded body at a temperature of 1300 ° C to 1600 ° C while circulating oxygen in the calcining apparatus. The step of forming a sintered body is a step of cooling to at least a temperature of 600 ° C or lower at a cooling rate of 200 ° C /hr or less while circulating oxygen in the calcining apparatus.

Therefore, the method for producing the oxide sputtering target can be such that the specific surface area of the mixed powder of the zirconia powder, the cerium oxide powder and the indium oxide powder of the mixed raw material is 11.5 m ² /g or more and 13.5 m ² /g or less. Highly reactive. Further, since the molded body is fired while the oxygen is passed through the calcining apparatus, there is no shortage of oxygen in the firing environment, and the molded body can be uniformly sintered to obtain a sintered body having a high density and high density. Further, since the sintered body is cooled at a cooling rate of 200 ° C / hour or less, it is difficult to drastically change the temperature, and the oxygen concentration of the sintered body can be stabilized. Therefore, it is possible to stably produce an oxide sputtering target having a small deviation value of the oxygen concentration in the target surface. [Effects of the Invention]

The present invention can provide an oxide sputtering target that suppresses abnormal discharge and microchip scattering during sputtering, and a method of manufacturing the oxide sputtering target.

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 of the present embodiment can be used, for example, when a dielectric film for a phase change optical disk such as a DVD or BD or an oxide film for a protective layer is formed by sputtering. Further, the oxide sputtering target of the present embodiment can also be used for forming an oxide film for a bottom layer and a protective layer of a magnetic recording medium such as an HDD (hard disk) by a sputtering method.

The oxide sputtering target of the present embodiment is formed of an oxide containing a metal component of zirconium, hafnium and indium. The content of zirconium, hafnium and indium is not particularly limited, and can be the same as the oxide used for the sputtering target for forming a protective film for an optical recording medium. In the present embodiment, when the total content of the metal components is 100% by mass, the content of zirconium is set to be in the range of 10% by mass or more and 75% by mass or less, and the content of cerium is set to be 35% by mass or less (but not including 0% by mass). ), the content of indium is set as a residue. One of zirconium, hafnium and indium may each form a composite oxide. The composite oxide is, for example, In ₂ Si ₂ O ₇ .

In the oxide sputtering target of the present embodiment, the ratio of the difference between the maximum value and the minimum value of the oxygen concentration in total of the maximum value and the minimum value of the oxygen concentration in the target surface is expressed by the following formula (1). The deviation of the oxygen concentration is 15% or less.

Formula (1): Deviation value (%) of oxygen concentration = [(maximum value of oxygen concentration) - (minimum value of oxygen concentration)] / [(maximum value of oxygen concentration) + (minimum value of oxygen concentration)] × 100

Further, in the oxide sputtering target of the present embodiment, the ratio of the difference between the maximum value and the minimum value of the specific resistance with respect to the maximum value and the minimum value of the specific resistance in the target surface is the following formula (2). The deviation value of the specific resistance is 15% or less.

Equation (2): Deviation value of specific resistance = [(maximum value of specific resistance) - (minimum value of specific resistance)] / [(maximum value of specific resistance) + (minimum value of specific resistance)] × 100

The reason why the oxygen concentration and the specific resistance deviation value of the oxide sputtering target of the present embodiment are defined as described above will be described below.

(Variation value of oxygen concentration) When the deviation value of the oxygen concentration of the oxide sputtering target is large, abnormal discharge and microchips are likely to occur during sputtering. Therefore, in the oxide sputtering target of the present embodiment, the deviation value of the target in-plane oxygen concentration represented by the above formula (1) is set to 15% or less. When the deviation value of the oxygen concentration exceeds 15%, abnormal discharge and microchips may occur, and foreign matter may adhere to the surface of the oxide film after film formation, and the in-plane deviation value of the film composition may increase. Further, the oxygen concentration of the oxide sputtering target varies depending on the contents of zirconium, hafnium and indium, and is preferably in the range of 15% by mass to 35% by mass. Oxygen concentration can be measured by EPMA and gas analysis.

Further, the deviation value of the oxygen concentration in the target surface can be obtained by measuring the oxygen concentration of the plurality of portions in the target surface, extracting the maximum value and the minimum value of the measured oxygen concentration, and calculating the above equation (1). The measurement site of the oxygen concentration is preferably 5 or more. Further, in the present embodiment, when the oxide sputtering target has a disk shape, as shown in FIG. 1, the center point (1) of the target surface (circle) is measured, and the two lines perpendicular to each other at the center point of the target surface are measured. From the outer edge, at the point of 20 mm, 4 points (2) to (5), the total oxygen concentration is 5 points, and the maximum and minimum values of the measured oxygen concentration are extracted, and the deviation value of the oxygen concentration is obtained. When the oxide sputtering target has a cylindrical shape, it is possible to measure an oxygen concentration of 5 points at a position equidistant from the circumferential direction at a position of 20 mm from the outer edge, and extract the maximum and minimum values of the measured oxygen concentration. Take the deviation of the oxygen concentration.

(Deviation value of specific resistance) When the deviation value of the specific resistance of the oxide sputtering target is large, abnormal discharge and microchips are likely to occur during sputtering. Therefore, in the oxide sputtering target of the present embodiment, the deviation value of the target in-plane specific resistance expressed by the above formula (2) is set to 15% or less. When the deviation value of the specific resistance exceeds 15%, abnormal discharge and microchips may occur, and foreign matter may adhere to the surface of the oxide film after film formation, and the in-plane deviation value of the film composition may be increased. Further, the specific resistance of the oxide sputtering target is preferably 0.1 Ω·cm or less.

Further, the deviation value of the specific resistance in the target surface is obtained by measuring the specific resistance of the plurality of portions in the target surface, and then extracting the maximum value and the minimum value of the measured specific resistance, and calculating the above equation (2). The portion where the specific resistance is measured is preferably five or more. Further, in the present embodiment, when the oxide sputtering target has a disk shape, as shown in FIG. 1, the center point (1) of the target surface (circle) is measured, and the two lines perpendicular to each other at the center point of the target surface are measured. From the outer edge, the specific resistance of 5 points (2) to (5) at a position of 20 mm is extracted, and the maximum and minimum values of the measured specific resistance are extracted, and the deviation value of the specific resistance is obtained. When the oxide sputtering target has a cylindrical shape, it is possible to measure a specific resistance of 5 points at a circumferentially equidistant position from a position of 20 mm from the outer edge, and extract the maximum and minimum values of the measured resistance to obtain a specific resistance. The deviation value.

Next, a method of manufacturing the oxide sputtering target of the present embodiment will be described with reference to a flowchart of Fig. 2 . As shown in FIG. 2, the method for producing an oxide sputtering target according to the present embodiment includes a pulverization mixing step S01 of pulverizing and mixing raw material powders, and a molding step S02 of forming a mixed powder obtained by pulverization and mixing into a constant shape, and The sintering step S03 of sintering the formed formed body, the cooling step S04 of cooling the obtained sintered body, and the processing step S05 of processing the sintered body after cooling.

ZrO ₂ powder, SiO ₂ powder, and In ₂ O ₃ powder as raw material powders were prepared. The ZrO ₂ powder preferably has a purity of 99.9% by mass or more and an average particle diameter of 0.2 μm or more and 20 μm or less. The SiO ₂ powder preferably has a purity of 99.8 mass% or more and an average particle diameter 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 diameter of 0.1 μm to 10 μm.

(pulverization and mixing step S01) When the total content of the metal components in the obtained mixed powder is 100% by mass, the raw material powder is weighed so that the zirconium content is in a range of 10% by mass or more and 75% by mass or less, and the cerium content is 35% by mass or less ( However, the content of the indium was not included in the range of 0% by mass, and the indium content was in the range of the residue. In the present embodiment, in the pulverization and mixing, hot-wet pulverization mixing was carried out using a bead mill apparatus using a zirconia ball having a diameter of 0.5 mm as a pulverization medium. In the pulverization mixing step S01, the obtained mixed powder is pulverized and mixed to have a specific surface area (BET specific surface area) of 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, the reactivity with the ambient oxygen and the sinterability in the sintering step described later can be improved, so that a sputtering target having a uniform oxygen concentration and specific resistance and having a high sintered density can be easily obtained. Further, when a mixed powder having a specific surface area of less than 11.5 m ² /g was used, a uniform reaction did not occur during firing, and the variation in the oxygen concentration of the sputtering target was increased. Further, the mixed powder is pulverized to have a specific surface area of more than 13.5 m ² /g, and it is disadvantageous for the economical surface to lengthen the pulverization and mixing time.

(Molding Step S02) Next, the mixed powder obtained by the pulverization mixing step S01 is molded into a predetermined shape to obtain a molded body. This embodiment is formed by press molding.

(Sintering Step S03) Next, the formed body obtained by the molding step S02 is sintered. In the sintering step S03, a calcining apparatus equipped with an oxygen introduction port is used, and oxygen is introduced into the interior while the molded body is fired and sintered. By injecting oxygen into the calcining apparatus while roasting the molded body, the sublimation of the In ₂ O ₃ powder in the mixed powder can be suppressed, so that a sputtering target having a uniform oxygen concentration and specific resistance and having a high sintered density can be easily obtained. The optimum flow rate of oxygen introduced into the calcining apparatus varies depending on the internal volume of the calcining apparatus and the size and number of the molded body for sintering, and therefore needs to be appropriately selected. For example, when six or less molded bodies having a diameter of 100 to 300 mm and a thickness of 15 mm or less are simultaneously fired in a calcining apparatus having an internal volume of 15,000 to 30,000 cm ³ , the required flow rate is in the range of 3 L/min or more and 10 L/min or less. Flows in excess of 10 L/min are generally not economically favorable. Further, it is preferable that the gas flowing through the calcining apparatus has a volume fraction of oxygen of 100%, that is, pure oxygen, but a gas having a volume ratio of oxygen of 80% or more and a mixture of other gases such as nitrogen or argon can be used.

The holding temperature at the time of baking is preferably in the range of 1300 ° C or more and 1600 ° C or less. When the temperature is less than 1300 ° C, it is difficult to obtain a fine sintered body, which may reduce the density. The use of temperatures in excess of 1600 ° C in normal production is generally not conducive to economic aspects. The rate of temperature rise during baking is preferably 200 ° C / hour or less, more preferably 10 ° C / hour or more and 200 ° C / hour. When it exceeds 200 ° C / hour, uneven reaction, sintering and shrinkage occur between the raw material powders, which may cause bending or cracking. Moreover, the failure to reach 10 ° C / hour is too long to reduce productivity.

(Cooling Step S04) Next, the sintered body obtained in the sintering step S03 is cooled. This cooling step S04 is to cool the sintered body to at least 600 ° C or lower while introducing oxygen into the calcining apparatus. By sintering the sintered body while introducing oxygen into the calcining apparatus, it is possible to suppress oxygen detachment in the sintered body during cooling, and it is easy to obtain a sputtering target having a uniform oxygen concentration and specific resistance. The flow rate of oxygen introduced into the calcining apparatus is preferably the same as the flow rate introduced into the calcining apparatus in the sintering step S03. The oxygen flow in the cooling step S04 is preferably carried out until the sintered body is taken out, but when the economical surface is considered, it can be suitably stopped at a temperature of up to 600 ° C or lower.

The cooling rate at the time of cooling to a temperature of 600 ° C or lower is preferably 200 ° C / hour or less, more preferably 1 ° C / hour or more and 200 ° C / hour or less. When the temperature exceeds 200 ° C / hour, it is difficult to uniformly cool the sintered body, which may impair the uniformity of the oxygen concentration, and the sintered body may be cracked by thermal stress. Moreover, when the temperature is less than 1 ° C / hour, the cooling time is too long and the productivity is lowered. The cooling rate is preferably maintained by the cooling step S04, but may be appropriately changed during cooling in the range of 200 ° C /hr or less. Further, after cooling to 600 ° C or lower, it may be cooled at a cooling rate exceeding 200 ° C / hour, but the operation of taking out the sintered body by the calcining apparatus is preferably carried out at a temperature of 100 ° C or lower.

(Processing Step S05) In the processing step S05, the sintered body cooled by the cooling step S05 is subjected to a cutting process or a grinding process to be processed into a sputtering target having a constant shape.

According to the oxide sputtering target of the present embodiment configured as described above, the deviation value of the oxidation concentration in the target surface can be 15% or less, so that the uniformity of the oxygen concentration in the target surface can be improved, and the specific resistance in the target surface can be improved. Evenly. Therefore, abnormal discharge during sputtering can be suppressed, and microchips can be suppressed.

Further, the specific surface area of the mixed powder obtained by pulverizing and mixing the raw material ZrO ₂ powder, the SiO ₂ powder and the In ₂ O ₃ powder in the pulverization mixing step S01 by the method for producing an oxide sputtering target according to the present embodiment may be 11.5. m ² / g or more 13.5m ² / g or less, thus having a high reactivity. Further, in the sintering step S03, since the molded body is fired while introducing oxygen into the calcining apparatus, the oxygen is not insufficient in the firing environment, so that the molded body can be uniformly sintered to obtain a fine and high-density sintered body. Further, in the cooling step S04, the cooling is performed at a cooling rate of 200 ° C /hr or less, so that a drastic temperature change is less likely to occur, and the oxygen concentration of the sintered body can be stabilized. Therefore, it is possible to stably produce an oxide sputtering target having a small deviation value of the oxygen concentration in the target surface.

The embodiments of the present invention have been described above, but the present invention is not limited thereto, and can be appropriately modified without departing from the scope of the technical idea of the invention. For example, in the present embodiment, the shape of the oxide sputtering target is a disk shape, but the shape of the oxide sputtering target is not particularly limited. The oxide sputtering target may be in the shape of a square plate. When the shape of the oxide sputtering target is a square plate shape, the oxygen concentration and the specific resistance measurement portion may be a total of five points in a point where the diagonal line intersects and four points in the vicinity of the corner portion on each diagonal line. Further, the oxide sputtering target may have a cylindrical shape. When the shape of the oxide sputtering target is a cylindrical shape, the oxygen concentration and the specific resistance measurement portion may be a total of five points in the circumferential direction.

Further, the oxide sputtering target of the present embodiment may contain an unavoidable impurity. Further, the unavoidable substance refers to an impurity which is inevitably contained in the raw material powder and an impurity which is inevitably mixed in the production process.

Further, in the method for producing an oxide sputtering target of the present embodiment, the pulverization and mixing step S01 is a step of pulverizing the ZrO ₂ powder, the SiO ₂ powder and the In ₂ O ₃ powder for mixing the raw materials, or simply mixing them. However, the mixed powder obtained by mixing preferably has a specific surface area of 11.5 m ² /g or more and 13.5 m ² /g or less. [Examples]

The evaluation test results for evaluating the effects of the oxide sputtering target of the present invention will be described below.

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

The raw material powder and the solvent were simultaneously introduced into a bead mill having a zirconia ball having a diameter of 0.5 mm as a pulverization medium, and pulverized and mixed. The solvent used was Somicu A-11 manufactured by Japan Ethanol Sales Co., Ltd. The time of pulverization and mixing was 1 hour. After the pulverization and mixing are completed, the zirconia balls are separated and recovered to obtain a slurry containing the raw material powder and the solvent. The resulting slurry was heated to remove the solvent to obtain a mixed powder.

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

Next, the obtained mixed powder was placed in a mold having a diameter of 200 mm, and a pressure of 150 kg/cm ² was applied to prepare two disk-shaped molded bodies having a diameter of 200 mm and a thickness of 10 mm. The obtained two molded bodies were placed in an electric furnace (inner furnace 27,000 cm ³ ), and oxygen was circulated in the electric furnace at a flow rate of 4 L per minute while being baked at the baking temperature shown in Table 1 for 7 hours. A sintered body is formed. Next, the sintered body was cooled to 600 ° C at the cooling rate shown in Table 1 while continuously flowing oxygen into the electric furnace, and then the oxygen flow was stopped, and the inside of the furnace was cooled to cool to room temperature, and then taken out from the electric furnace. Sintered body.

Mechanical processing was performed on the obtained sintered body 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 Inventive Example 1, except that the raw material powder was mixed by a Hans mixer.

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

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

[Comparative Example 4] Two sputtering targets were produced in the same manner as in Inventive Example 1, except that the baking temperature of the sintered body was 1,250 °C.

[Evaluation] The metal composition, relative density, oxygen content, and specific resistance of the sputtering target were measured. Further, a sputtering test of the sputtering target was performed. One of the two sputtering targets produced was used to measure the relative density, specific resistance, and oxygen content, and the other was used for the sputtering test. In the sputtering test, the number of abnormal discharges during sputtering is first determined. Next, after the oxide film was formed by sputtering, it was confirmed whether or not the target cracked. Further, the concentration of indium in the oxide film after film formation was measured. The evaluation methods are as follows.

(Metal composition of the sputtering target) A part of the end portion of the sintered body before the mechanical processing without the sputtering target was used as a sample. After the sample to be taken was dissolved in acid, the composition of the obtained solution was analyzed by a ICP-OES apparatus (Agilent 5100) by Agilent Technologies Co., Ltd. to analyze the composition of the metal components of Zr, Si, and In. The measurement results are shown in Table 2.

(Relative Density) The relative density is calculated from the ratio of the measured density relative to the theoretical density (measured density / theoretical density × 100). The measured density is determined by measuring the weight and size of the sputtering target. The theoretical density is calculated from the concentration and density of each oxide contained in the sputtering target. Specifically, the concentration of ZrO ₂ is C1 and the density is ρ1, the concentration of SiO ₂ is C2 and the density is ρ2, and the concentration of In ₂ O ₃ is C3 and the density is ρ3. The theoretical density ρ is calculated by the following formula. ρ = 1 / [C1/100ρ1 + C2 / 100ρ2 + C3 / 100ρ3] In this case, values of ρ1 = 5.60 g/cm ³ , ρ2 = 2.20 g / cm ³ , and ρ3 = 7.18 g / cm ^{3 were used} . Further, C1, C2, and C3 were calculated from the amount of the raw material powder added.

(Specific resistance) The specific resistance was measured by a four-probe method. In order to measure the deviation value of the specific resistance, as shown in Fig. 1, the center point (1) of the target surface (circle) is measured, and the two lines which are orthogonal to each other at the center point of the target surface are located at a position of 20 mm from the outer edge. Points (2) to (5) total 5 points. The maximum value and the minimum value of the measured specific resistances are extracted, and the deviation value of the specific resistance is calculated by the above formula (2). Table 2 shows the measured values and deviation values of the specific resistance of each measurement point.

(Oxygen concentration) As shown in Fig. 1, from the center point (1) from the target surface, and two lines perpendicular to each other at the center point of the target surface, from the outer edge at a position of 20 mm (4)~( 5) A small piece of a 10 mm angle was cut out at 5 points as a sample piece for measuring oxygen concentration, and the oxygen concentration on the surface (target surface) of the sample for measuring oxygen concentration was measured by the following method. First, the sample for measuring the oxygen concentration was embedded in the resin, and the surface (target surface) of the sample for measuring the oxygen concentration of the embedded resin was mirror-polished using a polishing apparatus. After the polishing, the oxygen concentration of the polished surface was quantitatively analyzed by EPMA (JXA-8500F, manufactured by JEOL Ltd.). The conditions for quantitative analysis of oxygen by EPMA are as follows. Acceleration voltage: 15kV Irradiation current: 5 × 10 ^-8 A Electron beam diameter: 100 μm Further, the spectroscopic crystal used for quantitative analysis of oxygen is LDE1. The measurement was carried out at 10 sites in the sample piece at an angle of 10 mm, and the average value thereof was used as the oxygen concentration measurement value of a portion shown in Fig. 1 . The maximum and minimum values of the oxygen concentrations of the five sites shown in Fig. 1 were extracted, and the deviation value of the oxygen concentration was calculated by the above formula (1). Table 2 shows the measured values and deviation values of the oxygen concentration of each sample for measuring the oxygen concentration.

(Testing test) The sputter target was soldered to an oxygen-free copper backing plate, and then mounted on a magnetron type plating apparatus (SIH-450H manufactured by ULVAC). Next, after evacuating the sputtering apparatus to 5 × 10 ^-5 Pa or less with a vacuum exhaust device, Ar gas and O ₂ gas were introduced, the sputtering gas pressure was adjusted to 0.67 Pa, and pre-sputtering was performed for 1 hour to remove The processing layer of the target surface. At this time, the flow ratio of the Ar gas to the O ₂ gas was 47 to 3, the electric power was a pulse of DC 1000 W, and the pulse condition was a cycle number of 50 kHz and a duty ratio of 0.08.

(Number of abnormal discharges) The sputtering was continuously performed for 1 hour under the same conditions as the above-described pressure sputtering. The arc-cutting machine provided with the DC power source of the sputtering apparatus used can measure the number of abnormal discharges occurring within one hour. The results are shown in Table 3.

(Formation of oxide film and analysis of composition of oxide film) After measuring the number of abnormal discharges described above, a polycarbonate substrate having a 20 mm-angle size was attached to a Si substrate having a diameter of 6 inches on the basis of 5 points shown in FIG. The object obtained from the center of the Si substrate at a point of 4 points from the center of the 60 mm radius is mounted in a sputtering apparatus, and the target is placed upwards, and then the inside of the sputtering apparatus is evacuated by a vacuum exhaust device to 5×. After 10 ^-5 Pa or less, sputtering was carried out under the same conditions as the above-described pre-sputtering to form an oxide film having a thickness of 200 nm on the substrate. At this time, the distance between the substrate and the target was 70 mm. The composition of the solution obtained by dissolving each oxide film in an acid was analyzed by an Agilent-produced combined plasma emission spectroscopic (ICP-OES) apparatus (Agilent 5100), and the In concentration in each oxide film was measured, and then the lower concentration was measured. Equation (3) calculates the deviation value. Table 3 shows the measured values and deviation values of the In concentration (% by mass when the total content of the metal elements is 100) in the oxide film.

Formula (3): Deviation value (%) of In concentration of oxide film = [(maximum value of In concentration) - (minimum value of In concentration)] / [(maximum value of In concentration) + (minimum concentration of In Value)]×100

(With or without cracking) After the oxide film is formed, the sputtering apparatus is opened to the atmosphere. Next, the sputtering target was taken out by a sputtering apparatus, and the appearance was visually observed to confirm whether or not cracking occurred. 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 the molded body in which the oxygen was not sintered in the calcining apparatus In Comparative Example 3, the sputtering target obtained in Comparative Example 4 in which the baking temperature of the molded body was less than 1300 ° C was such that the deviation value of the oxygen concentration in the target surface exceeded 15%.

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

The mixed powder of the raw material powder has a BET specific surface area of 11.5 m ² /g or more and 13.5 m ² /g or less, and a cooling rate of the sintered body to 600 ° C of 200 ° C / hour or less, and is distributed in the calcining apparatus. At the same time as oxygen, the sputtering target of Examples 1 to 7 of the present invention in which the molded body was fired at a temperature of 1300 ° C to 1600 ° C or lower was such that the deviation value of the oxygen concentration in the target surface was 15% or less.

In the sputtering targets of Inventive Examples 1 to 7 in which the deviation value of the oxygen concentration in the target surface is 15% or less, the deviation value of the specific resistance is 15% or less, and the number of abnormal discharges during sputtering can be remarkably reduced. Further, the thickness of the In concentration can be lowered by the oxide film formed by sputtering. In addition, cracking did not occur after sputtering.

As a result of the above evaluation test, it was confirmed that an oxide sputtering target capable of suppressing occurrence of abnormal discharge and microchip scattering during sputtering and a method of manufacturing the oxide sputtering target can be provided by the present invention.

FIG. 1 is an explanatory view showing measurement positions of oxygen concentration and specific resistance in an oxide sputtering target according to an embodiment of the present invention. Fig. 2 is a flow chart showing a method of manufacturing an oxide sputtering target according to an embodiment of the present invention. Fig. 3 is an explanatory view for explaining the position of the In concentration of the oxide film formed in the film in the measurement example.

Claims (3)

An oxide sputtering target characterized in that an oxide sputtering target formed of an oxide containing a metal component of zirconium, hafnium and indium is combined with a maximum value and a minimum value of an oxygen concentration in a target surface, The ratio of the difference between the maximum value and the minimum value of the oxygen concentration is 15% or less. The oxide sputtering target according to claim 1, wherein the ratio of the difference between the maximum value and the minimum value of the specific resistance is 15% or less with respect to the total value and the minimum value of the specific resistance in the target surface. A method for producing an oxide sputtering target, characterized in that a method for producing an oxide sputtering target according to claim 1 or 2 is provided with mixed zirconia powder, cerium oxide powder and indium oxide powder, and has a specific surface area of 11.5. step 13.5m ² / g or less of the mixed powder m ² / g or more, and the mixed powder so that the molded product obtained by molding step, and the firing device while the oxygen flow at a temperature of less than 1300 ℃ calcined 1600 ℃ The step of forming a sintered body by forming the sintered body, and circulating the oxygen at a cooling rate of 200 ° C /hr or less to a temperature of at least 600 ° C or lower at a cooling rate of 200 ° C /hr or less.