JP7244989B2 - Cylindrical sputtering target and manufacturing method thereof - Google Patents

Description

The present invention relates to a cylindrical sputtering target and a manufacturing method thereof. In particular, it relates to a method for manufacturing a cylindrical sintered body that constitutes a cylindrical sputtering target.

In recent years, the technology for manufacturing flat panel displays (FPDs) and solar cells has rapidly developed, and they are becoming larger in size. In addition, with the expansion of these markets, the demand for large glass substrates is increasing.

In particular, in a sputtering apparatus for forming a metal thin film or a metal oxide thin film on a large glass substrate, a cylindrical (also referred to as a rotary or rotating) sputtering target has been used in place of a conventional planar sputtering target. Cylindrical sputtering targets have advantages over flat sputtering targets, such as high target utilization efficiency, little occurrence of erosion, and little generation of particles due to exfoliation of deposits.

A cylindrical sputtering target used in a sputtering apparatus for forming a thin film on a large glass substrate as described above requires a length of 3000 mm or more. It is technically not realistic to manufacture a cylindrical sputtering target of such length by integral formation and grind it. Therefore, a divided sputtering target is usually constructed by connecting a plurality of cylindrical sintered bodies of several tens of millimeters to several hundreds of millimeters.

Here, not only the cylindrical sintered body but also general sintered body connection requires improvement in mechanical strength and improvement in film quality of the thin film using the sintered body. When joining a plurality of sintered bodies to a base material, the sintered bodies are arranged at regular intervals. This is because if the sintered bodies are arranged without gaps and joined to the base material, the sintered bodies may expand and contract due to the heat during sputtering, and the sintered bodies may collide with each other, resulting in cracks or chipping. On the other hand, the sintered bodies to be originally sputtered do not exist in the gaps between the sintered bodies. Therefore, there is a problem that the constituent material of the base material is sputtered, and a thin film having a desired composition cannot be formed. Furthermore, in a divided sputtering target in which a plurality of sintered bodies are connected, the difference in relative density between adjacent sintered bodies (that is, "variation between solid bodies" in the density of sintered bodies) affects the thin film using the divided sputtering target. affect quality. Thus, the shorter the connected sintered body, the more the sputtering target is divided, and the risk of affecting the sputtering characteristics increases.

In order to avoid the above problem as much as possible, a technique for manufacturing a longer cylindrical sintered body capable of coping with a smaller division of the sputtering target is required. Problems in the production of long cylindrical sintered bodies are the difference in relative density within the sintered body (that is, the "intra-solid variation" of the sintered body density) and the mechanical strength. For example, Patent Literature 1 discloses that the oxygen concentration in the atmosphere greatly affects quality stabilization (density and strength) in sintering an ITO target. A sintering furnace used for ITO is usually supplied with oxygen from the furnace wall side.

Japanese Patent Laid-Open No. 8-144056

However, in the case of a long cylindrical sintered body, insufficient gas convection in the cylinder during sintering causes oxygen deficiency in the cylinder. An object of the present invention is to cope with small divisions in a split sputtering target obtained by joining a plurality of sintered bodies to a base material, so that a cylindrical sintered body having a length of 470 mm or more in the cylindrical axis direction, a cylindrical It is an object of the present invention to provide sputtering targets and methods of making them. Another object of the present invention is to provide a cylindrical sintered body with high homogeneity within and between solids, a cylindrical sputtering target, and a method for producing them.

A method for manufacturing a cylindrical sputtering target according to an embodiment of the present invention is a method for manufacturing a cylindrical sputtering target having a cylindrical sintered body, wherein the stage is provided with an oxygen supply port connected to a pipe for supplying oxygen. A cylindrical molded body having a length of 600 mm or more in the axial direction of the cylinder is placed in the cylinder, and sintered while supplying oxygen in the direction of the cylindrical axis from an oxygen supply port smaller than the inner circumference of the cylinder provided inside the cylinder. do.

In another aspect, the stage may be arranged inside the chamber, and a pipe for supplying oxygen may be connected to the oxygen supply port from outside the chamber.

In another aspect, sintering may be performed while oxygen is supplied toward the inner hollow portion of the cylindrical compact.

In another embodiment, oxygen may be sintered while supplying oxygen upward in the axial direction of the cylindrical compact.

The cylindrical sintered body used for the cylindrical sputtering target according to one embodiment of the present invention is a cylindrical sintered body having a length of 470 mm or more in the cylindrical axis direction, and a relative density difference in the cylindrical axis direction of 0.1. %.

The cylindrical sintered body used for the cylindrical sputtering target according to one embodiment of the present invention is a cylindrical sintered body having a length of 470 mm or more in the axial direction of the cylinder, and the area of the holes observed on the inner side surface of the cylinder is The equivalent circle diameter is 1 μm or less on average.

The cylindrical sintered body used for the cylindrical sputtering target according to one embodiment of the present invention is a cylindrical sintered body having a length of 470 mm or more in the axial direction, and the number of holes observed on the inner surface of the cylinder is The average is 4.25×10 ⁻⁵ pieces/μm ² or less.

In another aspect, the holes observed on the inner side surface of the cylinder may be holes observed per visual field of 1.176 mm ² in at least five independent locations in the central portion in the axial direction of the cylinder.

According to the present invention, it is possible to provide a cylindrical sintered body having a length of 470 mm or more in the cylindrical axis direction, a cylindrical sputtering target, and a method for producing them. Alternatively, it is possible to provide a cylindrical sintered body with high homogeneity within and between solids, a cylindrical sputtering target, and methods for producing them.

1 is a perspective view showing an example of a cylindrical sintered body that constitutes a cylindrical sputtering target according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing an example of the configuration of an assembled cylindrical sputtering target according to an embodiment of the present invention; FIG. 1 is a process flow showing a method for manufacturing a cylindrical sintered body according to one embodiment of the present invention; 1 is a perspective view showing a step of sintering a cylindrical compact in a method for manufacturing a cylindrical sintered compact according to one embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing a step of sintering a cylindrical molded body in the method for manufacturing a cylindrical sintered body according to one embodiment of the present invention; FIG. 4 is a plan view showing a step of sintering a cylindrical molded body in the method for manufacturing a cylindrical sintered body according to one embodiment of the present invention; FIG. 5 is a plan view showing a step of sintering a cylindrical molded body in a method for manufacturing a cylindrical sintered body according to Modification 1 of one embodiment of the present invention. FIG. 10 is a cross-sectional view showing a step of sintering a cylindrical molded body in a method for manufacturing a cylindrical sintered body according to Modification 2 of one embodiment of the present invention. FIG. 4 is a diagram showing the positions of measuring samples taken in the direction of the cylinder axis in cylindrical sintered bodies according to examples and comparative examples of the present invention. 1 is a table showing densities, density differences in solids, relative densities, and maximum relative density differences in solids of cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. FIG. 5 is a diagram showing the relationship between the length of cylindrical sintered bodies and the minimum oxygen supply amount according to Examples and Comparative Examples of the present invention. 4 is a table showing the bulk resistance of cylindrical sintered bodies according to examples of the present invention and comparative examples, and bulk resistance value differences in solids. FIG. 10 is a diagram showing the positions at which measurement samples are taken on the inner side surface and the outer side surface of the cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. 1 is electron microscope (SEM, 1000x) photographs of cylindrical inner surfaces of cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. FIG. 2 is an electron microscope (SEM, 1000×) photograph of the cylindrical outer surface of cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. FIG. Fig. 2 is an electron microscope (SEM, 5000x or 2000x) photographs of cylindrical inner surfaces of cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. FIG. 2 is electron microscope (SEM, 5000×) photographs of cylindrical outer surfaces of cylindrical sintered bodies according to Examples and Comparative Examples of the present invention. FIG. FIG. 4 is a table showing the equivalent circle diameter of the areas of the holes on the cylindrical inner side surface of the cylindrical sintered bodies according to the examples and comparative examples of the present invention , and the average number thereof. FIG.

A cylindrical sputtering target and a method for manufacturing the same according to the present invention will be described below with reference to the drawings. However, the cylindrical sputtering target and the manufacturing method thereof of the present invention can be implemented in many different aspects, and should not be construed as being limited to the description of the embodiments shown below. In the drawings referred to in this embodiment, the same parts or parts having similar functions are denoted by the same reference numerals, and repeated description thereof will be omitted.

<Embodiment>
The configuration and structure of a cylindrical sputtering target and a cylindrical sintered body according to an embodiment of the present invention will be outlined with reference to FIGS. 1 and 2. FIG.

[Overview of Cylindrical Sputtering Target]
FIG. 1 is a perspective view showing an example of a cylindrical sintered body that constitutes a cylindrical sputtering target according to an embodiment of the present invention. As shown in FIG. 1, a cylindrical sputtering target 100 has a plurality of hollow cylindrical sintered bodies 110 . The plurality of cylindrical sintered bodies 110 are arranged adjacent to each other with a certain space therebetween. Here, in FIG. 1, for convenience of explanation, the space between adjacent cylindrical sintered bodies 110 is shown enlarged. As shown in detail in FIG. 2, a cylindrical substrate 130 for holding the cylindrical sintered body 110 is introduced into the cylindrical inner hollow portion of the cylindrical sintered body 110 .

Also, the thickness of the cylindrical sintered body 110 can be 6.0 mm or more and 20.0 mm or less. Also, the length of the cylindrical sintered body 110 in the direction of the cylindrical axis can be 470 mm or more and 1500 mm or less. Further, the outer diameter of the cylindrical sintered body 110 can be 147 mm or more and 175 mm or less. Also, the inner diameter of the cylindrical sintered body 110 can be set to 135 mm or less. Also, the space between adjacent cylindrical sintered bodies 110 in the axial direction of the cylinder can be 0.1 mm or more and 0.4 mm or less.

The material of the cylindrical sintered body 110 is, for example, an ITO sintered body (Indium Tin Oxide) made of indium, tin and oxygen, an IZO sintered body (Indium Zinc Oxide) made of indium, zinc and oxygen, indium, gallium, IGZO sintered bodies (Indium Gallium Zinc Oxide) made of zinc and oxygen, AZO sintered bodies (Aluminum Zinc Oxide) made of zinc, aluminum and oxygen, zinc oxide (ZnO), sintered bodies such as TiO ₂ . However, the cylindrical sintered body of the cylindrical sputtering target according to the present invention is not limited to the above composition as long as it is a ceramic sintered body containing oxygen.

Here, the density of the cylindrical sintered body 110 in this embodiment is preferably 99.5% or more. The density of the cylindrical sintered body 110 is more preferably 99.6% or more. Further, the difference in relative density in the solid of the cylindrical sintered body 110 in the direction of the cylinder axis is preferably 0.1% or less. The difference in relative density in the cylindrical axis direction of the cylindrical sintered body 110 is more preferably 0.05% or less, more preferably 0.03% or less. Also, the difference in relative density between the adjacent cylindrical sintered bodies 110a and 110b, that is, the difference in relative density between solid cylindrical sintered bodies is preferably 0.1% or less.

Incidentally, the density of the sintered body is indicated by relative density. The relative density is expressed by relative density = (measured density/theoretical density) x 100 (%), based on the measured density and theoretical density. The relative density difference is expressed by relative density difference=(measured density difference/theoretical density)×100 (%) by each measured density difference and theoretical density. The theoretical density is a density value calculated from the theoretical density of oxides of elements other than oxygen in each constituent element of the sintered body. For example, in the case of an ITO target, indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) are theoretically used as oxides of indium and tin excluding oxygen among the constituent elements of indium, tin, and oxygen. Used for density calculation. Here, the elemental analysis values (at % or mass %) of indium and tin in the sintered body are converted into mass ratios of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ). For example, as a result of conversion, in the case of an ITO target containing 90% by mass of indium oxide and 10% by mass of tin oxide, the theoretical density is (density of In ₂ O ₃ (g/cm ³ ) × 90 + density of SnO ₂ (g/ cm ³ )×10)/100 (g/cm ³ ). The theoretical density of In ₂ O ₃ is 7.18 g/cm ³ and the theoretical density of SnO ₂ is 6.95 g/cm ³ , and the theoretical density is calculated to be 7.157 (g/cm ³ ). Also, if each constituent element is Zn, it can be calculated as an oxide of ZnO, and if it is Ga, it can be calculated as an oxide of Ga ₂ O ₃ . The theoretical density of ZnO is 5.67 g/cm ³ and the theoretical density of Ga ₂ O ₃ is 5.95 g/cm ³ . Measured density, on the other hand, is weight divided by volume. In the case of a sintered body, the volume is calculated by the Archimedes method. The difference in the relative density in the solid of the cylindrical sintered body 110 in the cylindrical axis direction is obtained by cutting cylindrical measurement samples with a width of 40 to 50 mm at intervals of 150 mm in the cylindrical axis direction of the cylindrical sintered body 110, and measuring each sample. It can be evaluated by calculating the relative density.

As described above, by setting the length of the cylindrical sintered body and the relative density within the above range, the mechanical strength of the cylindrical sintered body can be improved and the nodule formation when using the cylindrical sintered body can be improved. It is possible to suppress the generation of particles accompanying generation and arcing, and obtain the effects of reducing impurities in the thin film and improving the film density. In addition, by setting the difference in the relative density in the solid of the cylindrical sintered body and between the solids in the above ranges, the distortion of the electric field can be suppressed in the split sputtering target having a plurality of cylindrical sintered bodies. . As a result, stable discharge characteristics can be obtained during sputtering, and a thin film with extremely high in-plane uniformity of film quality can be formed on a large substrate exceeding the size of one cylindrical sintered body.

The difference in the solid of the cylindrical sintered body 110 also includes the difference between the cylindrical inner surface and the outer surface of the cylindrical sintered body 110 . The state of the cylindrical inner side surface and the outer side surface of the cylindrical sintered body 110 can be evaluated by observation with an electron microscope (SEM). There is no significant difference in the holes observed on the inner side surface and the outer side surface of the cylindrical sintered body 110 in this embodiment at the central portion in the axial direction of the cylinder. The shape of the pores observed on the cylindrical inner and outer surfaces of the cylindrical sintered body 110 in this embodiment is an irregular grain shape, and is observed both at grain boundaries and within crystals. In other words, on the inner and outer surfaces of the cylindrical sintered body 110 of this embodiment, irregular bubble-like pores are observed both at the grain boundaries and within the crystals. On the other hand, the cylindrical inner side surface of the cylindrical sintered body in the comparative example whose length in the cylindrical axial direction is 470 mm or more includes the cylindrical outer side surface in the comparative example and the cylindrical inner side surface of the cylindrical sintered body 110 in the present embodiment. Larger, irregular grain-shaped pores are observed compared to the lateral and lateral surfaces. In other words, irregular crystal grain-like pores are observed on the inner side surface of the cylindrical sintered body of the comparative example having a length of 470 mm or more in the axial direction of the cylinder. The pores observed on the cylindrical inner side surface of the cylindrical sintered body in such a comparative example are mainly observed at grain boundaries. The cylindrical outer side surface of the cylindrical sintered body in the comparative example is not significantly different from the cylindrical inner side surface and the outer side surface of the cylindrical sintered body 110 in the present embodiment. The shape of the pores observed on the cylindrical outer surface of the cylindrical sintered body in the comparative example is smaller and irregular than the pores on the cylindrical inner surface, and is observed both at the grain boundary and within the crystal. be.

The shape of each hole observed on the cylindrical inner side surface and the cylindrical outer side surface of the cylindrical sintered bodies in this embodiment and the comparative example is irregular. For this reason, the size of a hole can be evaluated by calculating the area of one continuous hole in plan view and evaluating it by the diameter of a circle having the corresponding area (hereinafter referred to as the equivalent circle diameter of the area of the hole). good. The number of holes may be calculated assuming that one continuous hole on the surface to be observed is one. The average equivalent circle diameter of the area of the holes observed on the cylindrical inner side surface of the cylindrical sintered body 110 in this embodiment is preferably 1 μm or less. More preferably, the average equivalent circle diameter of the area of the pores observed on the cylindrical inner side surface of the cylindrical sintered body 110 is 0.5 μm or less. Further, the average number of holes observed on the cylindrical inner side surface of the cylindrical sintered body 110 in this embodiment is preferably 4.25×10 ⁻⁵ holes/μm ² or less. The average number of holes observed on the cylindrical inner side surface of the cylindrical sintered body 110 is more preferably 2.125×10 ⁻⁵ /μm ² or less. In this embodiment, the average equivalent circle diameter of the area of the holes observed on the cylindrical outer surface of the cylindrical sintered body 110 is preferably 1 μm or less. The average equivalent circle diameter of the area of the pores observed on the cylindrical outer surface of the cylindrical sintered body 110 is more preferably 0.5 μm or less. Further, the average number of holes observed on the cylindrical outer surface of the cylindrical sintered body 110 in this embodiment is preferably 4.25×10 ⁻⁵ holes/μm ² or less. The average number of holes observed on the cylindrical outer surface of the cylindrical sintered body 110 is more preferably 2.125×10 ⁻⁵ /μm ² or less.

The state of the inner and outer surfaces of the cylindrical sintered body 110 was evaluated by observing five fields of view of 980 μm×1200 μm in the central portion of each sample in the axial direction of the cylinder, and the number of holes and the area of the holes. Evaluate the average equivalent circle diameter. The equivalent circle diameter L of the area S of the hole can be obtained by first calculating the projected area S of one continuous hole and then calculating the diameter L of a circle having the corresponding area using the following formula.

There is no significant difference in the crystal grains observed on the inner side surface and the outer side surface of the cylindrical sintered body 110 in this embodiment at the central portion in the axial direction of the cylinder. The crystal grains observed on the cylindrical inner side surface and the outer side surface of the cylindrical sintered body 110 in this embodiment grow large. On the other hand, on the cylindrical inner surface of the cylindrical sintered body in the comparative example having a length of 957 mm or more in the cylindrical axial direction, the crystal grains are smaller than the outer surface, and crystal grains in the initial stage of growth are observed. be. The crystal grains on the cylindrical inner side surface of the cylindrical sintered body in such a comparative example are in the initial stage of growth, so they are small, non-uniform, and lack smoothness.

Although the details will be described in the manufacturing method, the cylindrical sintered body can be obtained by sintering the cylindrical molded body while supplying oxygen in the axial direction of the cylinder.

FIG. 2 is a cross-sectional view showing an example of the configuration of the assembled cylindrical sputtering target according to the embodiment of the present invention. As shown in FIG. 2, in the assembled cylindrical sputtering target 100, a cylindrical base material 130 is arranged in the cylindrical inner hollow portion of the cylindrical sintered body 110 shown in FIG. Cylindrical base material 130 and cylindrical sintered body 110 are brazed with brazing material 140 , and adjacent cylindrical sintered bodies 110 are arranged with space 120 interposed therebetween.

The material of the cylindrical substrate 130 has high thermal conductivity so that heat generated by collision of electrons and ions with the target during sputtering can be efficiently released, and is high enough to apply a bias voltage to the target. A metal material having electrical conductivity can be used. Specifically, copper (Cu), titanium (Ti) alloys containing these, and stainless steel (SUS) can be used.

The material of the brazing filler metal 140 has high thermal conductivity and electrical conductivity like the cylindrical base material 130, and has sufficient adhesion and strength for the cylindrical base material 130 to hold the cylindrical sintered body 110. material can be used. However, the thermal conductivity of the brazing material 140 may be lower than that of the cylindrical substrate 130 . Also, the brazing material 140 may be a material with a lower conductivity than the cylindrical substrate 130 . As the brazing material 140, for example, indium (In), tin (Sn), and alloys containing these can be used.

As described above, according to the sputtering target according to the present embodiment, the length of the cylindrical sintered body and the relative density are within the above ranges, thereby improving the mechanical strength of the cylindrical sintered body and improving the cylindrical sintered body. It is possible to obtain the effects of reducing impurities in the thin film using the mold sintered body and improving the film density. In addition, by setting the difference in the relative density in the solid of the cylindrical sintered body and between the solids in the above ranges, the distortion of the electric field can be suppressed in the split sputtering target having a plurality of cylindrical sintered bodies. . As a result, stable discharge characteristics can be obtained during sputtering, and a thin film with extremely high in-plane uniformity of film quality can be formed on a large substrate exceeding the size of one cylindrical sintered body. Furthermore, by setting the states of the cylindrical inner side surface and the cylindrical outer side surface of the cylindrical sintered body to the ranges described above, it is possible to maintain stable quality throughout the target life in the divided sputtering target having the cylindrical sintered body. . That is, the characteristics do not change during continuous use of the target, and the generation of nodules and particles due to poor density can be suppressed.

[Manufacturing method of cylindrical sintered body]
Next, a method for manufacturing a cylindrical sintered body of a cylindrical sputtering target according to the present invention will be described in detail with reference to FIG. FIG. 3 is a process flow showing a method for manufacturing a cylindrical sintered body according to an embodiment of the invention. FIG. 3 illustrates a method of manufacturing an ITO sintered body, but the material of the sintered body is not limited to ITO, and other metal oxide sintered bodies such as IGZO can also be used.

First, prepare the raw materials. The raw materials used for mixing are, for example, metal elements contained in oxides, alloys, and the like. A powdery raw material can be used as the raw material, and the raw material can be appropriately selected according to the composition of the intended sputtering target. For example, in the case of ITO, indium oxide powder and tin oxide powder are prepared (steps S301 and S302). The purity of these raw materials is generally 2N (99% by mass) or higher, preferably 3N (99.9% by mass) or higher, and more preferably 4N (99.99% by mass) or higher. If the purity is lower than 2N, many impurities are contained in the cylindrical sintered body, making it impossible to obtain the desired physical properties (for example, decrease in transmittance, increase in film resistance, local inclusion of foreign matter and generation of particles due to arcing).

Next, these raw material powders are pulverized and mixed (step S303). The raw material powder is pulverized and mixed by a dry method using balls or beads of zirconia, alumina, nylon resin, etc., a media agitating mill using the above balls or beads, a medialess container rotating type, a mechanical agitating type, An air flow wet method can be used. Here, since the wet method is generally superior to the dry method in pulverization and mixing ability, it is preferable to use the wet method for mixing.

The raw material composition is not particularly limited, but it is desirable to adjust it appropriately according to the composition ratio of the target sputtering target.

Here, if raw material powder with a small particle size is used, it becomes possible to increase the density of the sintered body. In addition, although it is possible to obtain a fine raw material powder by strengthening the grinding conditions, the amount of media (such as zirconia) used during grinding increases, increasing the concentration of impurities in the product. In this way, it is necessary to set an appropriate range for the grinding conditions while observing the balance between the densification of the sintered body and the concentration of impurities in the product.

Next, the raw material powder slurry is dried and granulated (step S304). Here, rapid dry granulation for rapid drying of the slurry may be performed. Rapid drying granulation may be performed by using a spray dryer and adjusting hot air temperature and air volume. By performing rapid dry granulation, it is possible to suppress separation of the indium oxide powder and the tin oxide powder due to the difference in sedimentation speed due to the difference in the specific gravity of the raw material powder. By granulating in this way, the ratio of the compounding ingredients is made uniform, and the handleability of the raw material powder is improved. In addition, calcination may be performed before and after granulation.

Next, the mixture obtained by the above-described mixing and granulation steps (which is calcined if a calcining step is provided) is pressure-molded to form a cylindrical compact (S305). Through this process, the target sputtering target is formed into a suitable shape. The length of the cylindrical molded body in the direction of the cylindrical axis can be 600 mm or more. Examples of the molding process include mold molding, cast molding, injection molding, etc. In order to obtain a complicated shape such as a cylindrical shape, molding by cold isostatic pressure (CIP) or the like is preferable. . In molding by CIP, raw material powder weighed to a predetermined weight is first filled into a rubber mold. At this time, by filling the rubber mold with rocking or tapping, it is possible to eliminate filling unevenness and gaps of the raw material powder in the mold. CIP molding pressure is preferably 100 MPa or more and 200 MPa or less. By adjusting the molding pressure as described above, in this embodiment, a cylindrical molded body having a relative density of 54.5% or more and 58.0% or less can be formed. More preferably, the CIP molding pressure is adjusted to 150 MPa or more and 180 MPa or less to obtain a cylindrical compact having a relative density of 55.0% or more and 57.5% or less.

Next, the cylindrical molded body obtained in the molding step is sintered (step S306). Here, a method for sintering the cylindrical compact will be described in detail with reference to FIGS. 4 to 6. FIG. FIG. 4 is a perspective view showing a step of sintering a cylindrical molded body in the method for manufacturing a cylindrical sintered body according to the embodiment of the present invention. FIG. 5 is a cross-sectional view showing a step of sintering a cylindrical molded body in a method for manufacturing a cylindrical sintered body according to an embodiment of the present invention. FIG. 6 is a plan view showing a step of sintering a cylindrical molded body in the method for manufacturing a cylindrical sintered body according to the embodiment of the present invention.

First, as shown in FIG. 4, the cylindrical molded body 111 obtained in the molding step of step S305 is placed on a flat plate-like sintering stage 200 such that the cylinder axis direction is substantially perpendicular to the sintering stage 200. placed in an upright position. However, as long as the cylindrical molded body 111 can be stably arranged on the sintering stage 200, it is not limited to this. For example, the cylindrical molded body 111 may be arranged in an inclined state with respect to the sintering stage 200 . Although omitted in FIG. 4, a spacer may be arranged between the cylindrical molded body 111 and the sintering stage 200 when the cylindrical molded body 111 is sintered. In this case, the spacer should be placed in contact with the bottom surface 150 of the cylindrical molded body 111 with an area smaller than that of the bottom surface 150 . By arranging the spacers, even if the volume of the cylindrical molded body 111 is reduced during the sintering process, it is possible to suppress the coefficient of friction caused by movement. Therefore, it is possible to suppress the occurrence of internal stress in the cylindrical sintered body after sintering.

As shown in FIGS. 5 and 6, the cylindrical molded body 111 obtained in the molding process of step S305 is placed on the sintering stage 200 provided in the chamber 300. As shown in FIGS. The cylindrical molded body 111 is sintered in a state in which the oxygen supply port 230 provided on the plate-like sintering stage 200 is arranged at the center of the cylinder. The oxygen supply port 230 is smaller than the inner circumference of the cylindrical compact 111 in consideration of shrinkage due to the sintering process, and enables oxygen to be supplied to the inner surface of the cylinder. In addition, the oxygen supply port 230 is arranged from the bottom to the top in the axial direction of the cylindrical molded body 111 . The oxygen supply port 230 may be the only opening provided in the sintering stage 200 . One oxygen supply port 230 is directly connected to one pipe 240 for supplying oxygen. The pipe 240 is connected to the oxygen supply port 230 from outside the chamber 300 via, for example, a controller, a valve, and the like. That is, the oxygen supplied from the pipe 240 selectively supplies oxygen to the inner side surface of the cylinder from the oxygen supply port 230 without leaking from other regions of the sintering stage 200 . By adopting such a configuration, the amount of oxygen supplied from the oxygen supply port 230 can be appropriately adjusted according to the length and thickness of the cylindrical compact 111 in the direction of the cylinder axis and the size of the inner space of the cylinder. can be done. For example, the longer the length in the axial direction of the cylinder, the larger the amount of oxygen supplied from the oxygen supply port 230 may be. However, the present invention is not limited to this. For example, when the thickness of the cylindrical compact 111 is large, the amount of oxygen supplied from the oxygen supply port 230 may be larger. Further, for example, when the inner diameter of the cylindrical sintered body is large and the internal space of the cylinder is large, the amount of oxygen supplied from the oxygen supply port 230 may be even greater.

The upper limit of the amount of oxygen supplied from the oxygen supply port 230 is not particularly limited, but may be 150 L/min or less. By supplying a large amount of oxygen from one oxygen supply port 230, the cooling effect of oxygen causes deformation and cracking of the cylindrical sintered body during sintering and a decrease in the density of the cylindrical sintered body after sintering. problems may occur. Therefore, a baffle plate or the like may be arranged in the direction in which oxygen flows from the oxygen supply port 230 . The oxygen supplied from the oxygen supply port 230 may collide with a baffle plate or the like to diffuse in the cylindrical inner space. Furthermore, the oxygen supplied from the oxygen supply port 230 may be supplied after preheating the piping or the like during circulation.

When oxygen is supplied to the inner hollow portion of the cylinder in an air atmosphere, the oxygen, which is heavier than nitrogen, is gradually filled from below in the axial direction of the cylinder. Therefore, oxygen can be evenly supplied to the inner surface of the cylinder during sintering. When the inner hollow portion of the cylindrical molded body is filled with oxygen, oxygen that is further supplied flows out from above the cylindrical molded body to the outer side of the cylinder through the inner hollow portion of the cylinder. The outflowing oxygen flows downward at the ceiling of the chamber 300 , creating a circulating oxygen flow within the chamber 300 . Therefore, the oxygen concentration in the chamber 300 may be made uniform. Separately, oxygen may be supplied from the wall of the chamber 300 to the outside of the cylinder. In this case, by adjusting the amount of oxygen supplied to the inner hollow portion of the cylinder and the amount of oxygen supplied to the outer side of the cylinder, the oxygen concentration of the inner surface and the outer surface of the cylindrical compact during sintering can also be made uniform.

Here, FIG. 4 exemplifies a method of supplying oxygen from below to the cylindrical inner hollow portion of the cylindrical molded body 111, but the method is not limited to this method. For example, oxygen may be supplied from below or above in the axial direction of the cylinder. By supplying oxygen in the cylindrical axial direction of the cylindrical compact 111, the oxygen concentration in the cylindrical axial direction during sintering can be kept uniform.

In addition, FIG. 4 exemplifies a method of supplying oxygen from one oxygen supply port 230 arranged at the center of the cylinder of the cylindrical compact 111, but the method is not limited to this method. The oxygen supply port 230 is not limited to the center of the cylinder as long as oxygen is uniformly supplied to the inner hollow portion of the cylinder. A plurality of oxygen supply ports 230 may be provided. Also, oxygen may be supplied not only to the inside of the cylinder but also to the outside of the cylinder. At this time, each oxygen supply port 230 is directly connected to a pipe 240 for supplying oxygen so that the oxygen supply amount can be independently controlled. As a result, the amount of oxygen supplied from each oxygen supply port 230 depends on the length and thickness of the cylindrical molded body 111 in the direction of the cylindrical axis, the size of the inner space of the cylinder, and the cylindrical molding with respect to the oxygen supply port 230. It can be appropriately adjusted according to the position of the body 111 and the like.

In general ITO sintering, sintering in an oxygen atmosphere is essential for increasing the density of the sintered body. Even in the sintering in an oxygen atmosphere, in the step of sintering the cylindrical molded body 111 having a length of 600 mm or more, the gas convection in the inner hollow part of the cylinder is insufficient, so oxygen is insufficient in the hollow inner part of the cylinder. occur. Deformation and cracking of the cylindrical sintered body during sintering, decrease in density of the cylindrical sintered body after sintering, and relative density of the cylindrical sintered body in the direction of the cylinder axis due to lack of oxygen in the inner hollow part of the cylinder A difference, an increase in the size of the pores or the number of pores observed on the inner cylindrical surface of the cylindrical sintered body, occurs. In order to prevent the influence of oxygen deficiency in the inner hollow portion, in the present embodiment, oxygen is supplied to the cylindrical inner hollow portion of the cylindrical molded body 111 when sintering the cylindrical molded body 111 as in the above configuration. By supplying oxygen from the port 230, it is possible to uniformly fill the cylindrical inner hollow portion of the cylindrical molded body 111 of 600 mm or more with oxygen. Furthermore, by combining the supply of oxygen to the inner hollow part of the cylinder and the supply of oxygen to the outer part of the cylinder, the oxygen concentration on the inner surface and the outer surface of the cylindrical compact 111 during sintering can be made uniform. can also As a result, deformation and cracking of the cylindrical sintered body during sintering can be prevented. Also, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the solid of the cylindrical sintered body in the direction of the cylindrical axis can be reduced. The size and number of holes on the inner surface of the cylinder can be reduced.

Returning to FIG. 3, the description of the manufacturing method of the cylindrical sintered body is continued. The sintering of step S306, detailed above, can use an electric furnace, hot isostatic pressure (HIP), or microwave firing. The sintering conditions can be appropriately selected according to the composition of the _sintered body. % of ITO can be sintered in an oxygen gas atmosphere at 1500° C. or higher and 1600° C. or lower for 10 hours or longer and 20 hours or shorter. If the sintering temperature is less than 1500°C, the density of the target will decrease. On the other hand, if the temperature exceeds 1600° C., damage to the electric furnace and the furnace materials is great, and timely maintenance is required, resulting in a significant decrease in work efficiency. Further, if the sintering time is less than 10 hours, the density of the target will be lowered, and if it is longer than 20 hours, the holding time in the sintering process will be long, resulting in deterioration of the operating rate of the electric furnace. Moreover, the consumption of oxygen gas used in the sintering process and the electric power for operating the electric furnace are increased. Moreover, the pressure during sintering may be atmospheric pressure, or may be a reduced or pressurized atmosphere.

Here, when sintering in an electric furnace, the occurrence of cracks can be suppressed by adjusting the temperature increase rate and temperature decrease rate during sintering. Specifically, the heating rate of the electric furnace during sintering is preferably 300° C./hour or less, more preferably 180° C./hour or less. Also, the temperature drop rate of the electric furnace during sintering is preferably 600° C./hour or less. Note that the temperature increase rate or temperature decrease rate may be adjusted so as to change stepwise.

Cylindrical compacts shrink during the sintering process, but before entering the temperature range where thermal contraction begins common to all materials, in order to equalize the temperature in the furnace, the temperature is maintained during the temperature rise. . As a result, temperature unevenness in the furnace is eliminated, and all the sintered bodies placed in the furnace shrink uniformly. In addition, by setting appropriate conditions for the attained temperature and holding time for each material, a stable sintered body density can be obtained. By sintering a cylindrical molded body having a length of 600 mm or more in the cylindrical axial direction, a cylindrical sintered body having a length of approximately 470 mm or more in the cylindrical axial direction is obtained.

Next, the formed cylindrical sintered body is machined into a desired cylindrical shape using a machining machine such as a surface grinder, cylindrical grinder, lathe, cutting machine, or machining center (step S307). . Machining is performed so as to form the cylindrical sintered body into a shape suitable for attachment to a sputtering apparatus, and to obtain a desired surface roughness. Here, the average surface roughness (Ra) of the cylindrical sintered body is preferably 0.5 μm or less in order to obtain flatness to the extent that abnormal discharge does not occur due to concentration of an electric field during sputtering. Through the above steps, a cylindrical sintered body with high density and high homogeneity can be obtained.

Next, the machined cylindrical sintered body is bonded to the substrate (step S308). Particularly in the case of a cylindrical sputtering target, a cylindrical sintered body is bonded to a cylindrical substrate called a backing tube using a brazing material as an adhesive. Through the steps described above, a cylindrical sputtering target using the cylindrical sintered body can be obtained.

As described above, according to the method for manufacturing a cylindrical sputtering target according to the embodiment, in the sintering step, oxygen is supplied to the cylindrical inner hollow portion of the cylindrical molded body, so that the cylindrical sintered body is being sintered. It can prevent deformation and cracking. Also, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the cylinder axis direction of the cylindrical sintered body after sintering can be reduced. It is possible to reduce the size of pores observed on the cylindrical inner surface of the cylindrical sintered body after sintering. Furthermore, the number of holes observed on the cylindrical inner surface of the cylindrical sintered body after sintering can be reduced. This makes it possible to provide a cylindrical sintered body and a cylindrical sputtering target with high homogeneity within and between solids.

<Modification 1>
A method for sintering a cylindrical sintered body according to Modification 1 of the embodiment of the present invention will be described with reference to FIG.

FIG. 7 is a plan view showing a step of sintering a cylindrical molded body in a method for manufacturing a cylindrical sintered body according to Modification 1 of the embodiment of the present invention. In FIG. 7, 16 oxygen supply ports 230 are arranged in the step of sintering the cylindrical compact 111 . At this time, each oxygen supply port 230 is directly connected to a pipe 240 for supplying oxygen so that the oxygen supply amount can be independently controlled. As a result, the amount of oxygen supplied from each oxygen supply port 230 depends on the length and thickness of the cylindrical molded body 111 in the direction of the cylinder axis, the size of the inner space of the cylinder, and the oxygen supply port for the cylindrical molded body 111. It can be appropriately adjusted according to the position of 230 or the like.

In FIG. 7, the eight pairs of oxygen supply ports 230 are evenly arranged through the wall of the cylindrical compact 111 . In other words, eight oxygen supply ports 230 are arranged along the cylindrical inner side surface and the outer side surface of the cylindrical molded body 111, respectively. In FIG. 7, the cylindrical molded body 111 is arranged so that the eight oxygen supply ports 230a are positioned inside the cylindrical molded body 111 and the eight oxygen supply ports 230b are positioned outside the cylindrical molded body 111. (hereinafter, the oxygen supply port 230a and the oxygen supply port 230b will be referred to as the oxygen supply port 230 when not distinguished). However, it is not limited to this, and the number, size, and arrangement of the oxygen supply ports 230 are not limited as long as the cylindrical compact 111 can be stably arranged on the sintering stage 200 . Further, the oxygen supply port 230 may be arranged not only inside the cylinder of the cylindrical molded body 111 but also outside the cylinder. In other words, oxygen may be supplied not only to the inner surface of the cylinder, but also to the outer surface of the cylinder.

For example, when the length of the cylindrical molded body 111 is long, the amount of oxygen supplied from the oxygen supply port 230a located inside the cylinder where convection is poor is made larger than the oxygen supply amount from the oxygen supply port 230b located outside the cylinder. , and finally, the oxygen concentration on the inner and outer surfaces of the cylinder may be adjusted to be uniform. Alternatively, oxygen may be supplied only from the oxygen supply port 230a located inside the cylinder. The amount of oxygen supplied by each oxygen supply port 230a may be, for example, ⅛ of the supply amount when oxygen is supplied from one oxygen supply port 230 in the embodiment of the present invention. Also, the amounts of oxygen supplied by the respective oxygen supply ports 230a may not be equal, and may differ. That is, the total amount of oxygen supplied from the plurality of oxygen supply ports 230a may be the supply amount when oxygen is supplied from one oxygen supply port 230 in the embodiment of the present invention. Also, the longer the length in the axial direction of the cylinder, the larger the total amount of oxygen supplied from the oxygen supply port 230a . However, the present invention is not limited to this. For example, when the thickness of the cylindrical molded body 111 is large, the total amount of oxygen supplied from the oxygen supply port 230a may be larger. Further, for example, when the inner diameter of the cylindrical sintered body is large and the inner space of the cylinder is large, the total amount of oxygen supplied from the oxygen supply port 230a may be larger.

The upper limit of the amount of oxygen supplied from the oxygen supply port 230 is not particularly limited, but may be 150 L/min or less. By supplying oxygen from the plurality of oxygen supply ports 230a, the supply amount of oxygen can be dispersed, and the gas convection in the cylindrical inner hollow portion can be controlled. In addition, problems such as deformation and cracking of the cylindrical sintered body during sintering due to the cooling effect of oxygen and reduction in density of the cylindrical sintered body after sintering can be suppressed. However, the oxygen supplied from the plurality of oxygen supply ports 230a may be further diffused in the cylindrical inner space via a baffle plate or the like. Furthermore, the oxygen supplied from the oxygen supply port 230 may be supplied after preheating the piping or the like during circulation.

In general ITO sintering, sintering in an oxygen atmosphere is essential for increasing the density of the sintered body. Even in sintering in an oxygen atmosphere, in the step of sintering the cylindrical molded body 111 having a length of 600 mm or more, insufficient gas convection in the inner hollow portion of the cylinder causes oxygen deficiency in the cylinder. Due to lack of oxygen in the cylinder, deformation and cracking of the cylindrical sintered body during sintering, decrease in density of the cylindrical sintered body after sintering, relative density difference in the cylinder axis direction of the cylindrical sintered body, An increase in the size or number of pores observed on the cylindrical inner surface of the cylindrical sintered body occurs. In order to prevent the influence of oxygen shortage in the cylinder, in this embodiment, the oxygen supply amount from the oxygen supply port 230a located inside the cylinder is made larger than the oxygen supply amount from the oxygen supply port 230b located outside the cylinder. Finally, the oxygen concentrations on the inner and outer surfaces of the cylinder may be adjusted to be uniform. By further increasing the amount of oxygen supplied from the oxygen supply port 230a located inside the cylinder, the oxygen concentration on the inner side surface of the cylinder may be finally adjusted to be higher than the oxygen concentration on the outer side surface of the cylinder. Furthermore, oxygen may be supplied only from the oxygen supply port 230a located inside the cylinder, and oxygen may not be supplied from the oxygen supply port 230b located outside the cylinder. Each oxygen supply port 230 is directly connected to a pipe 240 for supplying oxygen so that the oxygen supply amount can be independently controlled. By supplying oxygen from the plurality of oxygen supply ports 230a, oxygen can be supplied more uniformly on the inner surface of the cylinder. As a result, it is possible to adjust the oxygen concentration on the inner surface and the outer surface of the cylindrical compact during sintering, thereby preventing deformation and cracking of the cylindrical sintered compact during sintering. Also, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the cylinder axis direction of the cylindrical sintered body after sintering can be reduced. It is possible to reduce the equivalent circle diameter of the area of the pores observed on the cylindrical inner side surface of the cylindrical sintered body after sintering. Furthermore, the number of holes observed on the cylindrical inner surface of the cylindrical sintered body after sintering can be reduced.

<Modification 2>
A method for sintering a cylindrical sintered body according to Modification 2 of the embodiment of the present invention will be described with reference to FIG. Since this modification is the same as the embodiment of the present invention except for the baffle plate 260, detailed description thereof will be omitted.

FIG. 8 is a cross-sectional view showing a step of sintering a cylindrical molded body in a method for manufacturing a cylindrical sintered body according to Modification 2 of the embodiment of the present invention. In FIG. 8, one oxygen supply port 230 is arranged in the step of sintering the cylindrical compact 111 . The oxygen supply port 230 is directly connected to the oxygen supply pipe 240 so that the oxygen supply amount can be independently controlled. A baffle plate 260 is arranged in the direction in which oxygen flows from the oxygen supply port 230 . In this modification, baffle plate 260 has a cap-like shape to surround oxygen supply port 230 . The baffle plate 260 has a plurality of openings 280 in its cap-shaped side wall. Therefore, the oxygen supplied from the oxygen supply port 230 hits the inner ceiling portion of the baffle plate 260 and flows out from the plurality of openings 280 of the baffle plate 260 in a scattered state. Oxygen flowing out from the plurality of openings 280 of the baffle plate 260 gradually fills the inner hollow portion of the cylindrical compact from below in the axial direction of the cylinder and rises in the axial direction of the cylinder. However, the shape of the baffle plate 260 is not limited to this, and the baffle plate 260 may have any shape as long as it diffuses the oxygen supplied from the oxygen supply port 230 in the inner space of the cylinder. The baffle plate 260 may at least partially overlap the oxygen supply port 230, for example, when viewed from the direction in which oxygen travels. As a result, deformation and cracking of the cylindrical sintered body during sintering and reduction in the density of the cylindrical sintered body after sintering due to the cooling effect caused by supplying a large amount of oxygen from one oxygen supply port 230 are prevented. A decrease can be suppressed.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the scope of the invention.

[Production of Cylindrical Sintered Body]
[Example 1]
In Example 1, a method for producing a cylindrical ITO target material (cylindrical sintered body) will be described. First, as raw material powders, 4N indium oxide having a BET (Brunauer, Emmet and Teller's equation) specific surface area of 4.0 to 6.0 m ² /g and BET specific surface area of 4.0 to 5.7 m ² / g. of 4N tin oxide were prepared. Here, the BET specific surface area represents the surface area determined by the BET method. The BET method is a gas adsorption method in which gas molecules such as nitrogen, argon, krypton, and carbon oxide are adsorbed onto solid particles, and the specific surface area of the solid particles is measured from the amount of adsorbed gas molecules. Here, raw materials were weighed so that indium oxide was 90% by mass and tin oxide was 10% by mass. Next, these raw material powders were pulverized and mixed with a wet ball mill. Here, zirconia balls were used as grinding media. The mixed slurry was rapidly dried and granulated by a spray dryer.

Next, the mixture obtained by the above granulation process was formed into a cylindrical shape by CIP. The pressure during CIP molding was 176 MPa.

Each parameter of the cylindrical compact of Example 1 obtained by the above molding process is as follows.
・Cylinder outer diameter (diameter) = 194.0mm
・Cylindrical inner diameter (diameter) = 158.7mm
・Cylinder thickness = 17.65 mm
・Cylinder axial length = 600 mm

Next, the cylindrical compact obtained by CIP was sintered using an electric furnace. The sintering conditions are as follows.
・Temperature increase rate = 300°C/hour ・High temperature holding temperature = 1560°C
・High temperature holding time = 20 hr
・Atmosphere during sintering = oxygen atmosphere ・Pressure during sintering = atmospheric pressure ・Introduction of oxygen into hollow part inside cylinder = 50 L/min
・Introduction of oxygen to the outside of the cylinder = 0 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 155.2mm
・Cylindrical inner diameter (diameter) = 127.0 mm
・Cylinder thickness = 14.1mm
・Cylinder axial length = 478 mm
・Sintered body density = 7.134 g/cm ³
・ Relative density of sintered body = 99.68%
・Bulk resistance value of sintered body = 0.11 mΩ cm

[Example 2]
In Example 2, a cylindrical sintered body obtained by sintering a cylindrical shaped body longer in the cylindrical axis direction than in Example 1 will be described. Since the molding process of the cylindrical molded body is the same as that of Example 1, the explanation is omitted.

Each parameter of the cylindrical compact of Example 2 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 193.8mm
・Cylindrical inner diameter (diameter) = 158.2mm
・Cylinder thickness = 17.8mm
・Cylinder axial length = 1200mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Example 2 are the same as those of Example 1 except for the parameters for introducing oxygen into the inner hollow portion of the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 100 L/min
・Introduction of oxygen to the outside of the cylinder = 0 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 155.0mm
・Cylindrical inner diameter (diameter) = 126.6 mm
・Cylinder thickness = 14.2 mm
・Cylinder axial length = 948 mm
・Sintered body density = 7.132 g/cm ³
・ Relative density of sintered body = 99.65%
・Bulk resistance value of sintered body = 0.12 mΩ cm

[Example 3]
In Example 3, a cylindrical sintered body obtained by sintering a cylindrical compact longer in the cylindrical axis direction than in Examples 1 and 2 will be described. Since the molding process of the cylindrical molded body is the same as that of Example 1, the explanation is omitted.

Each parameter of the cylindrical compact of Example 3 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 194.2 mm
・Cylindrical inner diameter (diameter) = 158.5mm
・Cylinder thickness = 17.85 mm
・Cylinder axial length = 1755 mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Example 3 are the same as those of Example 1, except for the parameters for introducing oxygen into the inner hollow portion of the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 150 L/min
・Introduction of oxygen to the outside of the cylinder = 0 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 155.4mm
・Cylindrical inner diameter (diameter) = 126.8mm
・Cylinder thickness = 14.3mm
・Cylinder axial length = 1386 mm
・Sintered compact density = 7.130 g/cm ³
・ Relative density of sintered body = 99.62%
・Bulk resistance value of sintered body = 0.12 mΩ cm

Next, comparative examples for the cylindrical compacts and cylindrical sintered bodies shown in Examples 1 to 3 will be described below. In the following comparative example, unlike the example, a cylindrical sintered body sintered under conditions in which oxygen is not introduced into the inner hollow portion of the cylindrical compact will be described. In the comparative example, sintering was performed under the condition that oxygen was introduced from the chamber wall portion to the outside of the cylindrical molded body instead of introducing oxygen into the inner hollow portion of the cylindrical molded body. Since the molding process of the cylindrical molded body is the same as that of Example 1, the explanation is omitted.

[Comparative Example 1]
Each parameter of the cylindrical compact of Comparative Example 1 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 194.9mm
・Cylindrical inner diameter (diameter) = 159.0mm
・Cylinder thickness = 17.95mm
・Cylinder axial length = 480mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Comparative Example 1 are the same as those of Example 1, except for the parameters for introducing oxygen into the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 0 L/min
・Introduction of oxygen to the outside of the cylinder = 100 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 155.9mm
・Cylindrical inner diameter (diameter) = 127.2 mm
・Cylinder thickness = 14.35mm
・Cylinder axial length = 385mm
・Sintered body density = 7.133 g/cm ³
・ Relative density of sintered body = 99.66%
・Bulk resistance value of sintered body = 0.11 mΩ cm

[Comparative Example 2]
Each parameter of the cylindrical compact of Comparative Example 2 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 193.5mm
・Cylindrical inner diameter (diameter) = 158.2mm
・Cylinder thickness = 17.65mm
・Cylinder axial length = 600 mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Comparative Example 2 are the same as those of Example 1 except for the parameter of introducing oxygen into the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 0 L/min
・Introduction of oxygen to the outside of the cylinder = 100 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 156.7 mm
・Cylindrical inner diameter (diameter) = 128.1 mm
・Cylinder thickness = 14.3mm
・Cylinder axial length = 485mm
・Sintered body density = 7.041 g/cm ³
・ Relative density of sintered body = 98.38%
・Bulk resistance value of sintered body = 0.12 mΩ cm

[Comparative Example 3]
Each parameter of the cylindrical compact of Comparative Example 3 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 194.1mm
・Cylindrical inner diameter (diameter) = 158.2mm
・Cylinder thickness = 17.95mm
・Cylinder axial length = 1200mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Comparative Example 3 are the same as those of Example 1 except for the parameters for introducing oxygen into the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 0 L/min
・Introduction of oxygen to the outside of the cylinder = 100 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 157.2 mm
・Cylindrical inner diameter (diameter) = 128.1mm
・Cylinder thickness = 14.55 mm
・Cylinder axial length = 957mm
・Sintered compact density = 7.038 g/cm ³
・ Relative density of sintered body = 98.34%
・Bulk resistance value of sintered body = 0.12 mΩ cm
In Comparative Example 3, deformation due to sintering was confirmed.

[Comparative Example 4]
Each parameter of the cylindrical compact of Comparative Example 4 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 194.2 mm
・Cylindrical inner diameter (diameter) = 158.4 mm
・Cylinder thickness = 17.9mm
・Cylinder axial length = 1410 mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Comparative Example 4 are the same as those of Example 1 except for the parameters for introducing oxygen into the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 0 L/min
・Introduction of oxygen to the outside of the cylinder = 100 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 155.3 mm
・Cylindrical inner diameter (diameter) = 127.8mm
・Cylinder thickness = 13.75mm
・Cylinder axial length = 1145mm
・Sintered body density = 7.042 g/cm ³
・ Relative density of sintered body = 98.39%
・Bulk resistance value of sintered body = 0.12 mΩ cm

[Comparative Example 5]
Each parameter of the cylindrical compact of Comparative Example 5 obtained by the same molding process as in Example 1 is as follows.
・Cylinder outer diameter (diameter) = 193.6mm
・Cylindrical inner diameter (diameter) = 158.3 mm
・Cylinder thickness = 17.65mm
・Cylinder axial length = 1754mm

Next, the cylindrical compact was sintered using an electric furnace. The sintering conditions of Comparative Example 5 are the same as those of Example 1 except for the parameters for introducing oxygen into the cylindrical molded body, so the description is omitted.
・Introduction of oxygen into the inner hollow portion of the cylinder = 0 L/min
・Introduction of oxygen to the outside of the cylinder = 100 L/min

Each parameter of the cylindrical sintered body obtained by the above sintering process is as follows.
・Cylinder outer diameter (diameter) = 157.8 mm
・Cylindrical inner diameter (diameter) = 128.5 mm
・Cylinder thickness = 14.65mm
・Cylinder axial length = 1394 mm
・Sintered body density = 7.044 g/cm ³
・ Relative density of sintered body = 98.42%
・Bulk resistance value of sintered body = 0.12 mΩ cm

[Preparation of measurement sample]
For the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5 described above, measurement samples were prepared for evaluating intra-solid variations in density and bulk resistance. As shown in FIG. 9, the cylindrical sintered body 110 is divided by 150 mm from the bottom to the top in the axial direction of the cylinder during sintering. Furthermore, cylindrical measurement samples with a width of 40 to 50 mm are cut out from the central part in the axial direction of each cylinder, and measurement samples 110-1 (150 mm), 110-2 (300 mm), and 110-3 (450 mm) are obtained from the lower part in the axial direction of the cylinder. (Name in the table below).

[Evaluation of relative density]
The relative densities of the cylindrical sintered bodies and the measurement samples of Examples 1 to 3 and Comparative Examples 1 to 5 were evaluated. The densities of the cylindrical sintered body and each measurement sample were measured using the Archimedes method. The relative density and relative density difference of the cylindrical sintered body and each measurement sample were calculated based on the theoretical density. FIG. 10 shows the densities, relative densities, and maximum relative density differences in the cylindrical sintered bodies of the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5 and the measurement samples.

From the results of FIG. 10, in the cylindrical sintered bodies of Examples 1 to 3 in which oxygen was introduced into the inner hollow portion of the cylindrical molded body during sintering, oxygen The relative density was improved as compared with the cylindrical sintered bodies of Comparative Examples 2 to 5, which had no introduction. Comparative Example 1, in which the length in the axial direction of the cylinder is 470 mm or less, improved the relative density without introducing oxygen into the inner hollow portion of the cylindrical compact. In each of the measurement samples of Examples 1 to 3, the relative density difference was able to be reduced more than in each of the measurement samples of Comparative Examples 2 to 5. Comparative Example 1, in which the length in the axial direction of the cylinder is 470 mm or less, was able to reduce the relative density difference without introducing oxygen into the inner hollow portion of the cylindrical compact. In addition, by supplying oxygen to the inner surface of the cylindrical compact during the sintering process, it is possible to prevent deformation and cracking during sintering even for cylindrical compacts with a length of 1200 mm or more in the axial direction. did it.

[Evaluation of minimum oxygen supply]
The minimum oxygen supply amount for obtaining a cylindrical sintered body having a density of 7.130 g/cm ³ or more was determined by the method of sintering the cylindrical shaped body in the above-described Examples and Comparative Examples. Specifically, the amount of oxygen introduced into the inner hollow portion of the cylinder during sintering is changed stepwise, and a cylindrical sintered body having a length of 390, 480, 950, 1200 or 1400 mm in the axial direction of the cylinder is produced. Obtained. The density of each cylindrical sintered body was measured using the Archimedes method. Among cylindrical sintered bodies having a density of 7.130 g/cm ³ or more, the minimum amount of oxygen introduced during sintering is defined as the minimum oxygen supply amount for each length in the cylinder axis direction. FIG. 11 shows the relationship between the length of the cylindrical sintered body in the direction of the cylindrical axis and the minimum oxygen supply amount.

As shown in FIG. 11, a cylindrical sintered body with a density of 7.130 g/cm ³ or more was obtained up to a length of 390 mm in the cylindrical axial direction without oxygen introduction. . When forming a cylindrical sintered body of 480 mm, the minimum oxygen supply rate was 5 L/min or more. When forming a cylindrical sintered body of 950 mm, the minimum oxygen supply rate was 20 L/min or more. When forming a cylindrical sintered body of 1200 mm, the minimum oxygen supply rate was 30 L/min or more. When forming a cylindrical sintered body of 1400 mm, the minimum oxygen supply rate was 35 L/min or more. It can be seen from the results of FIG. 11 that the amount of oxygen required to obtain a cylindrical sintered body having a density of 7.130 g/cm ³ or more increases as the length in the axial direction of the cylinder increases. The axial length X (mm) of the cylindrical sintered body having a density of 7.130 g/cm ³ or more and the minimum oxygen supply amount Y (L/min) supplied from the oxygen supply port 230 are in a proportional relationship. can be expressed by the following formula.
Y=0.0345X-12.508

[Evaluation of bulk resistance]
Bulk resistance was evaluated for the cylindrical sintered bodies and the measurement samples of Examples 1 to 3 and Comparative Examples 1 to 5 described above. The bulk resistance value of the cylindrical sintered body and each measurement sample was measured using the four-probe method on the outer surface of the cylinder. FIG. 12 shows the bulk resistance values of the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5 and the measurement samples.

From the results of FIG. 12, the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5 and the respective measurement samples showed almost no change in the bulk resistance value on the cylindrical outer surface. Oxygen is sufficiently supplied to the outer surface of the cylinder. It is conceivable that the bulk resistance value on the side surface is hardly affected.

[Preparation of sample for electron microscope observation]
For the cylindrical sintered bodies of Examples 1 and 2 and Comparative Examples 2 and 3 described above, samples were prepared for observation with an electron microscope. As shown in FIG. 13, from the cylindrical sintered body 110, a cylindrical sample 110-4 with a width of 10 mm is cut out from the central part in the axial direction of the cylinder, and the inner surface 110-4a and the outer surface 110-4b of the cylinder are used for electron microscope observation. A sample was cut out, ground to 0.5 mm, and mirror-polished.

[Observation with an electron microscope]
Regarding the cylindrical sintered bodies of Examples 1 and 2 and Comparative Examples 2 and 3 described above, samples for electron microscopic observation of the cylindrical inner and outer surfaces of the cylindrical sintered bodies were observed with an electron microscope (SEM). Photographs of each sample observed with an electron microscope (SEM) at a magnification of 1000 are shown in FIG. 14 (inner cylinder) and FIG. 15 (outer cylinder). Photographs of each sample observed with an electron microscope (SEM) at a magnification of 2000 or 5000 are shown in FIG. 16 (inner cylinder) and FIG. 17 (outer cylinder). 14 to 17, electron microscope observation of the cylindrical inner and outer surfaces of the cylindrical sintered bodies of (a) Example 1, (b) Example 2, (c) Comparative Example 2, and (d) Comparative Example 3 The samples were observed with an electron microscope (SEM).

14(a) and (b) are electron micrographs of the side surfaces of the cylindrical sintered bodies in Examples 1 and 2. FIG. 15(a) and (b) are electron micrographs of the outer surface of the cylindrical sintered bodies in Examples 1 and 2. FIG. 14(c) and (d) are electron micrographs of side surfaces of cylindrical sintered bodies in Comparative Examples 2 and 3. FIG. 15(c) and (d) are electron micrographs of the outer surface of the cylindrical sintered bodies in Comparative Examples 2 and 3. FIG. As shown in FIGS. 14 and 15, in Examples 1 and 2 in which oxygen was introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering, the side surface of the cylindrical sintered body (FIG. 14(a) and (b)) and the lateral surface (FIGS. 15(a) and (b)) showed no significant difference in the electron micrographs. On the other hand, in Comparative Examples 2 and 3, in which oxygen was not introduced into the cylindrical inner hollow portion of the cylindrical compact during sintering, the outer surface of the cylindrical sintered compact (FIGS. 15(c) and (d)) was compared. Many large pores (black irregular morphology) were observed in electron micrographs of the side surface of the cylindrical sintered body (FIGS. 14(c) and (d)). On the cylindrical inner side surface of the cylindrical sintered bodies in Comparative Examples 2 and 3, many irregular grain-shaped (crystal grain-shaped) holes were observed. The pores observed on the cylindrical inner side surface of the cylindrical sintered bodies in Comparative Examples 2 and 3 were mainly observed at grain boundaries.

Next, in order to observe the state of the crystal grains, in the comparative example, in particular, the region without large holes observed in FIGS. 16(a) and (b) are electron micrographs of the side surfaces of the cylindrical sintered bodies in Examples 1 and 2. FIG. 17(a) and (b) are electron micrographs of the outer surface of the cylindrical sintered bodies in Examples 1 and 2. FIG. 16(c) and (d) are electron micrographs of the side surfaces of the cylindrical sintered bodies in Comparative Examples 2 and 3. FIG. 17(c) and (d) are electron micrographs of the outer surface of the cylindrical sintered bodies in Comparative Examples 2 and 3. FIG. As shown in FIGS. 16 and 17, in Examples 1 and 2 in which oxygen was introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering, the side surface of the cylindrical sintered body (FIG. 16(a) and (b)) and the outer surface (FIGS. 17(a) and (b)), no significant difference was observed, and the crystal grains had grown large. In Comparative Example 2, in which oxygen was not introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering and the length in the cylindrical axial direction was shorter than that of Comparative Example 3, the side surface of the cylindrical sintered body (Fig. 16(c) ) and the outer surface (FIG. 17(c)), no significant difference was observed, and the crystal grains were greatly grown. On the other hand, in Comparative Example 3 in which oxygen was not introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering and the length in the cylindrical axial direction was longer than in Comparative Example 2, the outer surface of the cylindrical sintered body (Fig. 17 In the electron micrograph of the side surface of the cylindrical sintered body (FIG. 16(d)) compared to (d)), small crystal grains in the initial stage of growth were observed. Since the crystal grains on the side surface of the cylindrical sintered body in Comparative Example 3 were in the initial stage of growth, they were small, uneven, and lacked smoothness.

On the cylindrical inner and outer surfaces of the cylindrical sintered bodies in Examples 1 and 2, small and irregular grain-shaped (bubble-like) holes were observed (for example, the upper left in FIG. 17(b) hole). Similar small, irregular grain-shaped (bubble-like) pores were observed on the cylindrical outer surface of the cylindrical sintered bodies in Comparative Examples 2 and 3 as well. Holes observed on the inner cylindrical surface of the cylindrical sintered bodies in Examples 1 and 2 and on the outer cylindrical surfaces of the cylindrical sintered bodies in Examples 1, 2, Comparative Examples 2 and 3 was observed both at grain boundaries and within crystals.

実施例１～実施例３及び比較例１～比較例５の円筒型焼結体の円筒内側面における、孔の数および孔における面積の円相当径の平均値を図１８に示す。 [Evaluation of holes on the side surface of a cylindrical sintered body]
Regarding the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5, the structures of the inner and outer surfaces of the cylindrical sintered bodies at the center in the axial direction of the cylinder were examined with an electron microscope (SEM) using the method described above. ), and the number of holes and the equivalent circle diameter of the area of the holes were measured. For each sample, five samples for electron microscope observation were cut out in the circumferential direction from the cylindrical inner surface 110-4a of the cylindrical sample 110-4. A field of view of 980 μm×1200 μm was observed from each sample for electron microscopic observation, and the average value of the number of holes and the equivalent circle diameter of the area of the holes was calculated. The equivalent circle diameter L of the area S in the hole of the cylindrical sintered body is calculated by the following formula.

FIG. 18 shows the average values of the number of holes and the average equivalent circle diameter of the area of the holes on the cylindrical inner surface of the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5.

From the results of FIG. 18, in the cylindrical sintered bodies of Examples 1 to 3 in which oxygen was introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering, oxygen was not introduced into the cylindrical inner hollow portion. The number of holes on the inner side surface of the cylinder was smaller than that of the cylindrical sintered bodies of Comparative Examples 2 to 5. Comparative Example 1, in which the length in the axial direction of the cylinder was 470 mm or less, had a small number of holes on the inner side surface of the cylinder even when oxygen was not introduced into the inner hollow portion of the cylindrical molded body. On the cylindrical inner side surface of the cylindrical sintered bodies of Examples 1 to 3, the average equivalent circle diameter of the area of the pores was 1 μm or less. On the other hand, on the cylindrical inner side surfaces of the cylindrical sintered bodies of Comparative Examples 2 to 5, the average equivalent circle diameter of the area of the pores was 4 μm or more. In Comparative Example 1, in which the length in the axial direction of the cylinder is 470 mm or less, the average equivalent circle diameter of the area of the holes on the inner side surface of the cylinder is 1 μm or less even if oxygen is not introduced into the inner hollow portion of the cylindrical molded body. rice field. As shown in FIG. 18, the number of holes on the cylindrical outer surface of the cylindrical sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 5 was 4.25×10 ⁻⁵ /μm ² or less. , the average equivalent circle diameter of the area of the pores was 1 μm or less.

In Examples 1 to 3, the results for ITO were shown. sintered using the method. In addition, the manufacturing conditions can be appropriately changed within the scope of the present invention for each composition. As a result, it was possible to prevent deformation and cracking of the cylindrical sintered body during sintering. In addition, the density of the cylindrical sintered body after sintering could be improved, and the relative density difference in the cylindrical axis direction of the cylindrical sintered body after sintering could be reduced. It is possible to reduce the equivalent circle diameter of the area of the holes observed on the cylindrical inner side surface of the cylindrical sintered body after sintering, and furthermore, it is observed on the cylindrical inner side surface of the cylindrical sintered body after sintering. It was possible to reduce the number of holes.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention.

100: Cylindrical sputtering target 110: Cylindrical sintered body 111: Cylindrical molded body 120: Space 130: Cylindrical base material 140: Brazing material 150: Bottom surface 200: Sintering stage 230: Oxygen supply port 240: Piping 260: Obstruction Plate 280: Opening 300: Chamber

Claims (2)

A cylindrical IGZO sintered body having a length in the axial direction of the cylinder of 948 mm or more,
The relative density difference in the axial direction of the cylinder is within 0.1%,
At least five fields of view of 1.176 mm ² are observed at the central portion of the inner side surface of the cylinder and the central portion of the outer side surface of the cylinder in the axial direction of the cylinder, and the average circle equivalent diameter of the observed hole area is 1 μm or less. Cylindrical IGZO sintered body. A sputtering target comprising the cylindrical IGZO sintered body according to claim 1 and a base material arranged in the inner hollow portion of the cylinder.

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