JP6397869B2 - Cylindrical sputtering target and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cylindrical sputtering target and a method for manufacturing the same. In particular, the present invention relates to a method for manufacturing a cylindrical sintered body constituting a cylindrical sputtering target.

  In recent years, manufacturing technology for flat panel displays (FPDs) and solar cells has been rapidly developed, and the size is increasing. With the expansion of these markets, 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 type or rotary type) sputtering target has been used instead of a conventional flat plate type sputtering target. Cylindrical sputtering targets have advantages in that the use efficiency of the target is high, erosion is less generated, and particles are not generated due to peeling of deposits, compared to flat plate sputtering targets.

  As described above, the cylindrical sputtering target used in the sputtering apparatus for forming a thin film on a large glass substrate needs to have a length of 3000 mm or more. It is technically impractical to manufacture and grind a cylindrical sputtering target having such a length by integral formation. Therefore, a divided sputtering target in which a plurality of cylindrical sintered bodies having a size of several tens to several hundreds of millimeters are connected is generally configured.

  Here, not only the cylindrical sintered body described above but also a general sintered body connection is required to improve mechanical strength and improve the quality of a thin film using the sintered body. When joining a several sintered compact to a base material, it arrange | positions with a fixed space | interval between sintered compacts. This is because if the sintered bodies are arranged without gaps and bonded to the base material, the sintered bodies may expand and contract due to heat during sputtering, and the sintered bodies may collide with each other, thereby causing cracks and chipping. On the other hand, there is no sintered body to be sputtered in the gap 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 split sputtering target in which a plurality of sintered bodies are connected, the difference in relative density between adjacent sintered bodies (that is, the “sinter density of the sintered bodies”) Affects quality. Thus, the shorter the sintered bodies to be connected, 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 longer cylindrical sintered body manufacturing technique that can cope with the smaller division of the sputtering target is required. Problems in the production of a long cylindrical sintered body are a difference in relative density within the sintered body (that is, “in-solid variation” of the sintered body density) and mechanical strength. For example, Patent Document 1 discloses that in the sintering of an ITO target, the oxygen concentration in the atmosphere greatly affects the quality stabilization (density and strength). Usually, the sintering furnace used for ITO is supplied with oxygen from the furnace wall side.

JP-A-8-144056

  However, in the case of a long cylindrical sintered body, oxygen shortage occurs in the cylinder because gas convection in the cylinder during sintering is not sufficient. The subject of the present invention is a cylindrical sintered body having a length in the cylindrical axis direction of 470 mm or more, cylindrical type in order to cope with the small division in a divided sputtering target obtained by joining a plurality of sintered bodies to a substrate. It aims at providing a sputtering target and those manufacturing methods. Alternatively, an object of the present invention is to provide a cylindrical sintered body, a cylindrical sputtering target, and a method for producing the same, which are highly homogenous in a solid and between solids.

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

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

  Moreover, in another aspect, you may sinter while supplying oxygen toward the cylindrical inside hollow part of a cylindrical molded object.

  Moreover, in another aspect, you may sinter while supplying oxygen toward the upper direction from the downward direction of the cylindrical axis direction of a cylindrical molded object.

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

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

The cylindrical sintered body used for the cylindrical sputtering target according to an embodiment of the present invention is a cylindrical sintered body having a length in the cylindrical axis direction of 470 mm or more, 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 hole observed on the inner surface of the cylinder may be a hole observed per field of 1.176 mm ² in at least five independent areas in the central portion in the cylinder axis direction.

  According to the present invention, it is possible to provide a cylindrical sintered body having a length in the cylindrical axis direction of 470 mm or more, a cylindrical sputtering target, and a manufacturing method thereof. Alternatively, it is possible to provide a cylindrical sintered body, a cylindrical sputtering target, and a manufacturing method thereof having high homogeneity within a solid and between individuals.

It is a perspective view which shows an example of the cylindrical sintered compact which comprises the cylindrical sputtering target which concerns on one Embodiment of this invention. It is sectional drawing which shows an example of a structure of the cylindrical sputtering target after the assembly which concerns on one Embodiment of this invention. It is a process flow which shows the manufacturing method of the cylindrical sintered compact which concerns on one Embodiment of this invention. It is a perspective view which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact which concerns on one Embodiment of this invention. It is sectional drawing which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact which concerns on one Embodiment of this invention. It is a top view which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact which concerns on one Embodiment of this invention. It is a top view which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact which concerns on the modification 1 of one Embodiment of this invention. It is sectional drawing which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact which concerns on the modification 2 of one Embodiment of this invention. It is a figure which shows the collection position of the measurement sample in a cylindrical-axis direction in the cylindrical sintered compact which concerns on the Example and comparative example of this invention. It is a table | surface which shows the density of the cylindrical sintered compact which concerns on the Example of this invention, and a density difference in a solid, a relative density, and the largest relative density difference in a solid. It is a figure which shows the relationship between the length of the cylindrical sintered compact concerning the Example and comparative example of this invention, and the minimum oxygen supply amount. It is a table | surface which shows the bulk resistance of the cylindrical sintered compact concerning the Example of this invention, and a bulk resistance value difference in a solid. It is a figure which shows the collection position of the measurement sample in a cylindrical inner surface and an outer surface in the cylindrical sintered compact which concerns on the Example and comparative example of this invention. It is an electron microscope (SEM, 1000 times) photograph in the cylindrical inner surface of the cylindrical sintered compact which concerns on the Example and comparative example of this invention. It is an electron microscope (SEM, 1000 times) photograph in the cylindrical outer surface of the cylindrical sintered compact which concerns on the Example and comparative example of this invention. It is an electron microscope (SEM, 5000 times or 2000 times) photograph in the cylindrical inner surface of the cylindrical sintered compact which concerns on the Example and comparative example of this invention. It is an electron microscope (SEM, 5000 times) photograph in the cylindrical outer surface of the cylindrical sintered compact which concerns on the Example and comparative example of this invention. Is a table showing the average actual施例and equivalent circle diameter of the area of holes in the cylindrical inner surface of the cylindrical sintered body according to the comparative example, and the number of the present invention.

  Hereinafter, a cylindrical sputtering target and a manufacturing method thereof according to the present invention will be described with reference to the drawings. However, the cylindrical sputtering target and the manufacturing method thereof according to the present invention can be implemented in many different modes, and are not construed as being limited to the description of the embodiments described below. Note that in the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

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

[Outline of cylindrical sputtering target]
FIG. 1 is a perspective view showing an example of a cylindrical sintered body constituting a cylindrical sputtering target according to an embodiment of the present invention. As shown in FIG. 1, the cylindrical sputtering target 100 includes a plurality of cylindrical sintered bodies 110 having a hollow structure. The plurality of cylindrical sintered bodies 110 are disposed adjacent to each other through a certain space. Here, in FIG. 1, for convenience of explanation, the space between the adjacent cylindrical sintered bodies 110 is shown enlarged. As shown in detail in FIG. 2, a cylindrical base material 130 for holding the cylindrical sintered body 110 is introduced into the hollow portion inside the cylindrical sintered body 110.

  The thickness of the cylindrical sintered body 110 can be 6.0 mm or more and 20.0 mm or less. The length of the cylindrical sintered body 110 in the cylindrical axis direction can be set to 470 mm or more and 1500 mm or less. Moreover, the outer diameter of the cylindrical sintered body 110 can be set to 147 mm or more and 175 mm or less. The inner diameter of the cylindrical sintered body 110 can be set to 135 mm or less. Further, the space in the cylindrical axis direction between adjacent cylindrical sintered bodies 110 can be set to 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, An IGZO sintered body made of zinc and oxygen (Indium Gallium Zinc Oxide), an AZO sintered body made of zinc, aluminum and oxygen (Aluminum Zinc Oxide), a sintered body made of zinc oxide (ZnO), TiO ₂ or the like. 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 the present embodiment is preferably 99.5% or more. The density of the cylindrical sintered body 110 is more preferably 99.6% or more. The difference in relative density in the cylindrical axis direction in the solid of the cylindrical sintered body 110 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, and further preferably 0.03% or less. Further, the relative density difference between the adjacent cylindrical sintered bodies 110a and 110b, that is, the relative density difference between the solid bodies of the cylindrical sintered bodies is preferably 0.1% or less.

In addition, the density of a sintered compact is shown by a relative density. The relative density is expressed by relative density = (measured density / theoretical density) × 100 (%) according to the measured density and the theoretical density. The relative density difference is represented by the relative density difference = (measured density difference / theoretical density) × 100 (%) by the difference in the measured density and the theoretical density. The theoretical density is a density value calculated from the theoretical density of an oxide of an element excluding 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 considered as oxides of indium and tin excluding oxygen among indium, tin, and oxygen as constituent elements Used for density calculation. Here, indium and elemental analysis values of the tin in the sintered body (at%, or mass%) from converted to mass ratio of indium oxide (In ₂ O ₃₎ and tin oxide (SnO _2). For example, in the case of an ITO target with 90% by mass of indium oxide and 10% by mass of tin oxide as a result of conversion, the theoretical density is (density of In ₂ O ₃ (g / cm ³ ) × 90 + SnO ₂ (g / cm ³ ) × 10) / 100 (g / cm ³ ) The theoretical density of In ₂ O ₃ is calculated as 7.18 g / cm ³ , the theoretical density of SnO ₂ is calculated as 6.95 g / cm ³ , and the theoretical density is calculated as 7.157 (g / cm ³ ). Further, when each constituent element is Zn, it can be calculated as ZnO, and when it is Ga, it can be calculated as a Ga ₂ O ₃ oxide. The calculation is performed assuming that 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 . On the other hand, the measured density is a value obtained by dividing weight by volume. In the case of a sintered body, the volume is calculated by the Archimedes method. The difference in relative density in the cylindrical axis direction in the solid of the cylindrical sintered body 110 is determined by cutting out a cylindrical measurement sample having a width of 40 to 50 mm every 150 mm in the cylindrical axis direction of the cylindrical sintered body 110. It can be evaluated by calculating the relative density.

  As described above, by making the length and relative density of the cylindrical sintered body within the above range, the mechanical strength of the cylindrical sintered body is improved and nodules are improved when the cylindrical sintered body is used. Generation of particles due to generation and arcing can be suppressed, and the effect of reducing impurities in the thin film and improving the film density can be obtained. Further, by setting the difference in relative density within and between the solid bodies of the cylindrical sintered body within the above ranges, the electric field distortion 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 very 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 includes the difference between the cylindrical inner surface and the outer surface of the cylindrical sintered body 110. The state of the cylindrical inner surface and the outer 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 and outer surfaces of the cylindrical sintered body 110 in the cylindrical axial direction in the present embodiment. The shape of the holes observed in the cylindrical inner surface and the outer surface of the cylindrical sintered body 110 in this embodiment is an irregular grain shape, and is observed both in the crystal grain boundary and in the crystal. In other words, irregular bubble-like holes are observed in both the crystal grain boundary and the crystal on the inner surface and the outer surface of the cylindrical sintered body 110 in the present embodiment. On the other hand, the cylindrical inner surface of the cylindrical sintered body in the comparative example having a length in the cylindrical axis direction of 470 mm or more includes the cylindrical outer surface in the comparative example and the cylindrical inner surface of the cylindrical sintered body 110 in the present embodiment. Larger irregularly shaped pores are observed compared to the lateral and lateral surfaces. In other words, irregular crystal grain holes are observed on the inner surface of the cylindrical sintered body in the comparative example having a length in the cylindrical axis direction of 470 mm or more. The holes observed on the cylindrical inner surface of the cylindrical sintered body in such a comparative example are mainly observed at the grain boundaries. The cylindrical outer surface of the cylindrical sintered body in the comparative example is not significantly different from the inner and outer surfaces of the cylindrical sintered body 110 in the present embodiment. The shape of the holes observed on the cylindrical outer surface of the cylindrical sintered body in the comparative example is a small and irregular grain shape as compared with the holes on the inner surface of the cylinder, and is observed at both the grain boundary and the crystal. The

The shape of each hole observed in the cylindrical inner surface and the cylindrical outer surface of the cylindrical sintered body in this embodiment and the comparative example is irregular. For this reason, the size of the hole can be evaluated by calculating the area when one continuous hole is viewed in plan and evaluating the diameter of a circle having a 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 1. The average of the equivalent circle diameters of the areas in the holes observed on the cylindrical inner surface of the cylindrical sintered body 110 in this embodiment is preferably 1 μm or less. The average of the equivalent circle diameters of the areas in the holes observed on the cylindrical inner surface of the cylindrical sintered body 110 is more preferably 0.5 μm or less. In addition, the average number of holes observed on the cylindrical inner surface of the cylindrical sintered body 110 in this embodiment is preferably 4.25 × 10 ⁻⁵ holes / μm ² or less. The average of the number of holes observed on the inner surface of the cylindrical sintered body 110 is more preferably 2.125 × 10 ⁻⁵ / μm ² or less. In addition, the average of the equivalent circle diameter of the area in the hole observed on the cylindrical outer surface of the cylindrical sintered body 110 in this embodiment is preferably 1 μm or less. The average of the equivalent circle diameters of the areas in the holes observed on the cylindrical outer surface of the cylindrical sintered body 110 is more preferably 0.5 μm or less. Moreover, the average of the 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 holes / μm ² or less.

The cylindrical inner surface 110 and the outer surface of the cylindrical sintered body 110 are evaluated by observing five fields of view of 980 μm × 1200 μm at the center in the cylindrical axis direction of each sample, and determining 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 in the hole can be obtained by first calculating the projected area S of one continuous hole and calculating the diameter L of the circle having the corresponding area by the following formula.

There is no significant difference in crystal grains observed on the inner and outer surfaces of the cylindrical sintered body 110 in the cylindrical axial direction in the present embodiment. Crystal grains observed on the inner and outer cylindrical surfaces of the cylindrical sintered body 110 in the present embodiment are greatly grown. On the other hand, on the cylindrical inner surface of the cylindrical sintered body in the comparative example having a length in the cylindrical axis direction of 957 mm or more, the crystal particles are smaller than the outer surface, and crystal grains in the initial stage of growth are observed. The Since the crystal particles on the inner surface of the cylindrical sintered body in the comparative example are in the initial stage of growth, they are small, non-uniform, and lack smoothness.

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

  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 disposed in the hollow portion inside the cylindrical sintered body 110 shown in FIG. The cylindrical base material 130 and the cylindrical sintered body 110 are brazed by the brazing material 140, and the adjacent cylindrical sintered bodies 110 are arranged via the space 120.

  The material of the cylindrical base material 130 has a high thermal conductivity so that electrons and ions collide with the target when the target is sputtered can be efficiently released, and a bias voltage can be applied to the target. A conductive metal material can be used. Specifically, copper (Cu), titanium (Ti), an alloy containing these, and stainless steel (SUS) can be used.

  The material of the brazing filler metal 140 has high thermal conductivity and conductivity as in the cylindrical base material 130, and the cylindrical base material 130 has sufficient adhesion and strength to hold the cylindrical sintered body 110. Material can be used. However, the heat conductivity of the brazing material 140 may be a material lower than the heat conductivity of the cylindrical base material 130. Further, the conductivity of the brazing material 140 may be a material lower than the conductivity of the cylindrical base material 130. As the brazing material 140, for example, indium (In), tin (Sn), and an alloy containing these can be used.

  As described above, according to the sputtering target according to the present embodiment, the length and relative density of the cylindrical sintered body are within the above ranges, thereby improving the mechanical strength of the cylindrical sintered body and its cylinder. The effect of reducing impurities and improving the film density of the thin film using the mold sintered body can be obtained. Further, by setting the difference in relative density within and between the solid bodies of the cylindrical sintered body within the above ranges, the electric field distortion 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 very 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 state of the cylindrical inner surface and the outer surface of the cylindrical sintered body within the above ranges, stable quality can be maintained throughout the target life in the split sputtering target having the cylindrical sintered body. . That is, characteristic changes do not occur during continuous use of the target, and generation of nodules and particles due to poor density can be suppressed.

[Manufacturing method of cylindrical sintered body]
Next, the manufacturing method of the cylindrical sintered compact of the cylindrical sputtering target which concerns on this invention is demonstrated in detail using FIG. FIG. 3 is a process flow showing a method for manufacturing a cylindrical sintered body according to an embodiment of the present invention. In FIG. 3, the manufacturing method of an ITO sintered body is illustrated, but the material of the sintered body is not limited to ITO, and can be used for other metal oxide sintered bodies such as IGZO.

  First, prepare the raw materials. As a raw material used for mixing, for example, a metal element contained in an oxide or an alloy is used. The raw material can be used in powder form and can be appropriately selected depending on the composition of the target 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 usually 2N (99% by mass) or more, preferably 3N (99.9% by mass) or more, more preferably 4N (99.99% by mass) or more. If the purity is lower than 2N, the cylindrical sintered body contains a large amount of impurities, so that desired physical properties cannot be obtained (for example, a decrease in transmittance, an increase in the resistance value of the film, and a foreign matter is included locally). 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 and beads such as zirconia, alumina, and nylon resin, a media stirring mill using the above balls and beads, a medialess container rotating type, a mechanical stirring type, An air flow type wet method can be used. Here, since the wet method is generally superior in pulverization and mixing ability compared to the dry method, it is preferable to perform the mixing using the wet method.

  Although there is no restriction | limiting in particular about a raw material composition, It is desirable to adjust suitably according to the composition ratio of the target sputtering target.

  Here, if the raw material powder having a fine particle diameter is used, the sintered body can be densified. Although it is possible to obtain fine raw material powder by strengthening the pulverization conditions, the amount of media (such as zirconia) used during pulverization increases and the impurity concentration in the product increases. As described above, it is necessary to set an appropriate range for the pulverization conditions while observing the balance between the density of the sintered body and the impurity concentration in the product.

  Next, the raw material powder slurry is dried and granulated (step S304). Here, rapid drying granulation for rapidly drying the slurry may be performed. The rapid drying granulation may be performed by using a spray dryer and adjusting the hot air temperature and the air volume. By performing rapid drying 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 specific gravity of the raw material powder. By granulating in this way, the ratio of the blending components is made uniform, and the handling property of the raw material powder is improved. Moreover, you may perform temporary baking before and after granulation.

  Next, the mixture obtained by the above-described mixing and granulating steps (the one that has been pre-baked when the pre-baking step is provided) is pressure-molded to form a cylindrical molded body (S305). By this step, the material is formed into a shape suitable for the target sputtering target. The length of the cylindrical molded body in the cylindrical axis direction can be 600 mm or more. Examples of the molding process include mold molding, cast molding, injection molding, and the like, but in order to obtain a complicated shape such as a cylindrical mold, it is preferable to mold by cold isostatic pressure (CIP) or the like. . In molding by CIP, first, a raw material powder weighed to a predetermined weight is filled into a rubber mold. At this time, by filling the rubber mold while swinging or tapping, filling irregularities and voids of the raw material powder in the mold can be eliminated. The molding pressure by CIP is preferably 100 MPa or more and 200 MPa or less. By adjusting the molding pressure as described above, a cylindrical molded body having a relative density of 54.5% or more and 58.0% or less can be formed in this embodiment. More preferably, a CIP molding pressure is adjusted to 150 MPa or more and 180 MPa or less to obtain a cylindrical molded body having a relative density of 55.0% or more and 57.5% or less.

  Next, the cylindrical molded body obtained in the molding process is sintered (step S306). Here, a method of sintering the cylindrical molded body will be described in detail with reference to FIGS. 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 the method for manufacturing a cylindrical sintered body according to the embodiment of the present invention. Moreover, FIG. 6 is a top view which shows the process of sintering a cylindrical molded object in the manufacturing method of the cylindrical sintered compact concerning embodiment of this invention.

  First, as shown in FIG. 4, the cylindrical molded body 111 obtained in the molding process of step S <b> 305 has a cylindrical axis direction substantially perpendicular to the sintering stage 200 on the flat plate-shaped sintering stage 200. Arranged upright. However, the present invention is not limited to this as long as the cylindrical molded body 111 can be stably disposed on the sintering stage 200. For example, the cylindrical molded body 111 may be disposed in an inclined state with respect to the sintering stage 200. Although omitted in FIG. 4, a spacer may be disposed between the cylindrical molded body 111 and the sintering stage 200 when the cylindrical molded body 111 is sintered. In this case, the spacer may be disposed so as to be in contact with the bottom surface 150 with an area smaller than the bottom surface 150 of the cylindrical molded body 111. By disposing the spacer, the friction coefficient generated by the movement can be suppressed even if the volume of the cylindrical molded body 111 is reduced in the sintering process. Therefore, it is possible to suppress the generation of internal stress generated in the sintered cylindrical sintered body.

  As shown in FIGS. 5 and 6, the cylindrical molded body 111 obtained in the molding process of step S <b> 305 is disposed on the sintering stage 200 provided in the chamber 300. The cylindrical molded body 111 is sintered in a state where the oxygen supply port 230 provided in the plate-like sintering stage 200 is arranged at the center of the cylinder. The oxygen supply port 230 is smaller than the inner periphery of the cylindrical molded body 111 in consideration of reduction due to the sintering process, and can supply oxygen to the inner surface of the cylinder. The oxygen supply port 230 is arranged from the lower side to the upper side in the cylindrical axis direction of the cylindrical molded body 111. The opening provided in the sintering stage 200 may be only the oxygen supply port 230. One oxygen supply port 230 is directly connected to one pipe 240 that supplies oxygen. The piping 240 is connected to the oxygen supply port 230 from the outside of the chamber 300 via, for example, a controller, a valve, or the like. That is, oxygen supplied from the pipe 240 selectively supplies oxygen from the oxygen supply port 230 to the inner surface of the cylinder 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 is appropriately adjusted according to the length and thickness of the cylindrical molded body 111 in the cylindrical axis direction and the size of the cylindrical internal space. Can do. For example, as the length in the cylindrical axis direction is longer, the amount of oxygen supplied from the oxygen supply port 230 may be larger. However, the present invention is not limited to this. For example, when the cylindrical molded body 111 is thick, the amount of oxygen supplied from the oxygen supply port 230 may be larger. Further, for example, when the cylindrical sintered body has a large inner diameter and a large cylindrical internal space, the amount of oxygen supplied from the oxygen supply port 230 may be further increased.

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, due to the cooling effect of oxygen, the cylindrical sintered body is deformed and cracked during sintering, and the density of the cylindrical sintered body after sintering is reduced. Such problems may occur. For this reason, a baffle plate or the like may be arranged in the traveling direction of oxygen from the oxygen supply port 230. Oxygen supplied from the oxygen supply port 230 may collide with a baffle plate or the like and diffuse in the cylindrical internal space. Further, 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 hollow portion inside the cylinder under an air atmosphere, oxygen heavier than nitrogen is gradually filled from below in the cylinder axis direction. Therefore, oxygen can be supplied evenly to the cylindrical inner surface of the cylindrical molded body being sintered. When the cylindrical inner hollow portion of the cylindrical molded body is filled with oxygen, further oxygen supplied flows out in a cylindrical outer side from the top of the cylindrical molded body via a cylindrical inner hollow portion. The outflowing oxygen flows downward in the ceiling portion of the chamber 300, and an oxygen flow circulating in the chamber 300 is generated. For this reason, the oxygen concentration in the chamber 300 may be made uniform. Separately, oxygen may be supplied from the wall portion of the chamber 300 to the outside of the cylinder. In this case, the oxygen concentration of the cylindrical inner surface and outer surface of the cylindrical molded body during sintering is adjusted by adjusting the amount of oxygen supplied to the hollow portion inside the cylinder and the amount of oxygen supplied to the outside of the cylinder, respectively. Can be made uniform.

Here, although FIG. 4 illustrates a method of supplying oxygen from below into the cylindrical hollow portion of the cylindrical molded body 111, the method is not limited to this method. For example, oxygen may be supplied from below or above in the cylindrical axis direction. By supplying oxygen to the cylindrical axis of the cylindrical shaped body 111, it can be kept uniform oxygen concentration in the cylinder axis direction during the sintering.

  4 illustrates a method of supplying oxygen from one oxygen supply port 230 arranged at the center of the cylinder of the cylindrical molded body 111, the present invention is not limited to this method. As long as oxygen is uniformly supplied in the hollow portion inside the cylinder, the oxygen supply port 230 is not limited to the center of the cylinder. There may be a plurality of oxygen supply ports 230. Moreover, oxygen may be supplied not only inside the cylinder but also outside the cylinder. At this time, each oxygen supply port 230 is directly connected to the oxygen supply pipe 240 so that the oxygen supply amount can be controlled independently. Thereby, the amount of oxygen supplied from each oxygen supply port 230 is determined by the length and thickness of the cylindrical molded body 111 in the cylindrical axis direction, the size of the cylindrical internal space, and the cylindrical molding for 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 under an oxygen atmosphere, in the step of sintering the cylindrical molded body 111 having a length of 600 mm or more, gas convection in the hollow portion inside the cylinder is not sufficient, so that there is insufficient oxygen in the hollow portion inside the cylinder. Arise. Oxygen deficiency in the hollow part inside the cylinder causes deformation and cracking of the cylindrical sintered body during sintering, a decrease in the density of the cylindrical sintered body after sintering, and the relative density in the axial direction of the cylindrical sintered body The difference, the size of the holes observed on the cylindrical inner surface of the cylindrical sintered body, or the increase in the number of holes occurs. In order to prevent the influence of oxygen deficiency in the inner hollow part, in the present embodiment, when the cylindrical molded body 111 is sintered as described above, oxygen is supplied to the cylindrical inner hollow part of the cylindrical molded body 111. By supplying oxygen from the opening 230, the hollow portion inside the cylindrical molded body 111 of 600 mm or more can be uniformly filled with oxygen. Further, by combining the supply of oxygen to the hollow portion inside the cylinder and the supply of oxygen to the outside of the cylinder, the oxygen concentration on the cylindrical inner surface and outer surface of the cylindrical molded body 111 during sintering is made uniform. You can also. As a result, deformation and cracking of the cylindrical sintered body during sintering can be prevented. Moreover, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the cylindrical axis direction in the solid of the cylindrical sintered body can be reduced. The size and number of holes in the inner surface of the cylinder can be reduced.

Returning to FIG. 3, the description of the manufacturing method of the cylindrical sintered body will be continued. For the sintering in step S306 described in detail above, an electric furnace, hot isostatic pressure (HIP), or microwave firing can be used. The sintering conditions can be appropriately selected depending on the composition of the sintered body. For example, SnO ₂ is 10 wt. If it is contained, it can be sintered under the conditions of oxygen gas atmosphere, 1500 ° C. or higher and 1600 ° C. or lower and 10 hours or longer and 20 hours or shorter. When the sintering temperature is less than 1500 ° C., the density of the target is lowered. On the other hand, when the temperature exceeds 1600 ° C., damage to the electric furnace and the furnace material is great, and timely maintenance is required, so that work efficiency is remarkably lowered. Moreover, if the sintering time is less than 10 hours, the density of the target will decrease, and if it is longer than 20 hours, the holding time in the sintering process will become longer, and the operating rate of the electric furnace will deteriorate. In addition, the consumption of oxygen gas used in the sintering process and the electric power for operating the electric furnace increase. Further, the pressure during sintering may be atmospheric pressure, or a reduced pressure or pressurized atmosphere.

  Here, when sintering by an electric furnace, generation | occurrence | production of a crack can be suppressed by adjusting the temperature increase rate and temperature decrease rate of sintering. Specifically, the heating rate of the electric furnace during sintering is preferably 300 ° C./hour or less, and more preferably 180 ° C./hour or less. Moreover, the temperature lowering rate of the electric furnace during sintering is preferably 600 ° C./hour or less. Note that the rate of temperature increase or the rate of temperature decrease may be adjusted to change stepwise.

  The cylindrical molded body shrinks during the sintering process, but before entering the temperature range where thermal shrinkage starts in common with all materials, the temperature is maintained during the temperature rise in order to make the temperature inside the furnace uniform. . This eliminates temperature unevenness in the furnace, and all the sintered bodies installed in the furnace shrink uniformly. Moreover, the stable sintered body density can be obtained by setting appropriate conditions for the temperature and holding time for each material. By sintering a cylindrical molded body having a length in the cylindrical axis direction of 600 mm or more, a cylindrical sintered body having a length in the cylindrical axis direction of approximately 470 mm or more is obtained.

  Next, the formed cylindrical sintered body is machined into a cylindrical desired shape by using a machining machine such as a surface grinding machine, a cylindrical grinding machine, a lathe, a cutting machine, or a machining center (step S307). . The machining is performed so that the cylindrical sintered body has a shape suitable for mounting on a sputtering apparatus, and a desired surface roughness is obtained. Here, it is preferable that the average surface roughness (Ra) of the cylindrical sintered body be 0.5 μm or less in order to obtain flatness that does not cause abnormal discharge due to concentration of 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 base material (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 above steps, a cylindrical sputtering target using the above cylindrical sintered body can be obtained.

  As described above, according to the manufacturing method of the cylindrical sputtering target according to the embodiment, by supplying oxygen to the cylindrical inner hollow portion of the cylindrical molded body in the sintering process, Deformation and cracking can be prevented. Moreover, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the cylindrical axis direction of the cylindrical sintered body after sintering can be reduced. It is possible to reduce the size of the holes observed on the 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. Thereby, it is possible to provide a cylindrical sintered body and a cylindrical sputtering target with high homogeneity within a solid and between solid bodies.

<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 the cylindrical molded body in the 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 molded body 111. At this time, each oxygen supply port 230 is directly connected to the oxygen supply pipe 240 so that the oxygen supply amount can be controlled independently. 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 cylindrical axis direction, the size of the cylindrical inner space, and the oxygen supply port for the cylindrical molded body 111. The position can be appropriately adjusted according to the position of 230.

  In FIG. 7, the eight pairs of oxygen supply ports 230 are evenly arranged through the wall of the cylindrical molded body 111. In other words, eight oxygen supply ports 230 are arranged along the cylindrical inner surface and outer surface of the cylindrical molded body 111, respectively. In FIG. 7, the cylindrical molded body 111 has eight oxygen supply ports 230 a positioned on the inner side of the cylindrical molded body 111 and eight oxygen supply ports 230 b positioned on the outer side of the cylindrical molded body 111. (Hereinafter, when the oxygen supply port 230a and the oxygen supply port 230b are not distinguished, they are referred to as the oxygen supply port 230). However, the present invention 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 molded body 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 oxygen supply amount from the oxygen supply port 230a located inside the cylinder with poor convection is made larger than the oxygen supply amount from the oxygen supply port 230b outside the cylinder. Finally, the oxygen concentration on the inner and outer surfaces of the cylinder may be adjusted to be uniform. Further, oxygen may be supplied only from the oxygen supply port 230a located inside the cylinder. The amount of oxygen supplied from each oxygen supply port 230a may be, for example, 1/8 of the supply amount when oxygen is supplied from one oxygen supply port 230 in the embodiment of the present invention. Further, the amount of oxygen supplied by each oxygen supply port 230a may not be equal and may be different. That is, the sum of the oxygen supply amounts 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, as the length of the cylindrical axis direction is long, the amount of total oxygen supplied from the oxygen supply port 230 a may be greater. However, the present invention is not limited to this. For example, when the cylindrical molded body 111 is thick, the total amount of oxygen supplied from the oxygen supply port 230a may be larger. For example, when the cylindrical sintered body has a large inner diameter and a large cylindrical internal space, the total amount of oxygen supplied from the oxygen supply port 230a may be further increased.

  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 gas convection in the hollow portion inside the cylinder can be controlled. In addition, it is possible to suppress problems such as deformation and cracking of the cylindrical sintered body during sintering due to a cooling effect by oxygen, and a decrease in density of the cylindrical sintered body after sintering. However, the oxygen supplied from the plurality of oxygen supply ports 230a may be further diffused in the cylindrical internal space via a baffle plate or the like. Further, 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 the sintering under 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 hollow portion inside the cylinder is not sufficient, resulting in insufficient oxygen 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 cylindrical axis direction of the cylindrical sintered body, There is an increase in the size of the holes or the number of holes observed on the inner surface of the cylindrical sintered body. 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 outside the cylinder. Thus, the oxygen concentration on the inner and outer surfaces of the cylinder may be finally 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 surface of the cylinder may finally be adjusted to be higher than the oxygen concentration on the outer surface of the cylinder. Further, it may be adjusted so that oxygen is supplied only from the oxygen supply port 230a located inside the cylinder and is not supplied from the oxygen supply port 230b outside the cylinder. Each oxygen supply port 230 is directly connected to an oxygen supply pipe 240 so that the oxygen supply amount can be controlled independently. 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, the oxygen concentration of the cylindrical inner surface and the outer surface of the cylindrical molded body during sintering can be adjusted, and deformation and cracking of the cylindrical sintered body during sintering can be prevented. Moreover, the density of the cylindrical sintered body after sintering can be improved. Furthermore, the relative density difference in the cylindrical 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 hole observed on the 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.

<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 the 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 disposed in the step of sintering the cylindrical molded body 111. The oxygen supply port 230 is directly connected to the piping 240 for supplying oxygen so that the oxygen supply amount can be controlled independently. A baffle plate 260 is disposed in the direction of oxygen travel from the oxygen supply port 230. In this modification, the baffle plate 260 has a cap shape so as to surround the oxygen supply port 230. The baffle plate 260 has a plurality of openings 280 in a cap-shaped side wall. Therefore, 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. The oxygen flowing out from the plurality of openings 280 of the baffle plate 260 gradually fills from below in the cylindrical axis direction and rises in the cylindrical axis direction in the hollow portion inside the cylindrical molded body. However, the shape of the baffle plate 260 is not limited to this, and the baffle plate 260 may have any shape that diffuses oxygen supplied from the oxygen supply port 230 in the cylindrical internal space. For example, the baffle plate 260 may be at least partially overlapped with the oxygen supply port 230 when viewed from the oxygen traveling direction side. As a result, the deformation of the cylindrical sintered body during sintering due to the cooling effect, cracking, and the density of the cylindrical sintered body after sintering caused by supplying a large amount of oxygen from one oxygen supply port 230 A decrease or the like can be suppressed.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

[Manufacture 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, 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 a BET specific surface area of 4.0 to 5.7 m ² / g as raw material powders. Of 4N tin oxide. Here, the BET specific surface area represents the surface area obtained 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 on solid particles, and the specific surface area of the solid particles is measured from the amount of adsorbed gas molecules. Here, the 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 the grinding media. The mixed slurry was rapidly dried and granulated by a spray dryer.

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

Each parameter of the cylindrical molded body of Example 1 obtained by the above molding process is as follows.
・ Cylinder outer diameter (diameter) = 194.0 mm
・ Cylinder inner diameter (diameter) = 158.7 mm
・ Cylinder thickness = 17.65 mm
・ Length in cylindrical axis direction = 600 mm

Next, the cylindrical molded body 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 at sintering = Atmospheric pressure-Oxygen introduction into the hollow part inside the cylinder = 50 L / min
・ Oxygen introduction to the outside of the cylinder = 0 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 155.2mm
・ Cylinder inner diameter (diameter) = 127.0 mm
・ Cylinder thickness = 14.1 mm
・ Cylinder axis length = 478mm
・ 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 molded body that is longer in the cylindrical axis direction than Example 1 will be described. Since the molding process of the cylindrical molded body is the same as that in Example 1, the description thereof is omitted.

The parameters of the cylindrical molded body of Example 2 obtained by the same molding process as in Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 193.8 mm
・ Cylinder inner diameter (diameter) = 158.2 mm
・ Cylinder thickness = 17.8mm
・ Length in cylindrical axis direction = 1200mm

Next, the cylindrical molded body was sintered using an electric furnace. Since the sintering conditions of Example 2 are the same as those of Example 1 except for the parameters for introducing oxygen into the hollow portion inside the cylindrical molded body, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 100 L / min
・ Oxygen introduction to the outside of the cylinder = 0 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 155.0mm
・ Cylinder inner diameter (diameter) = 126.6 mm
・ Cylinder thickness = 14.2 mm
・ Length in cylindrical axis direction = 948mm
・ 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 molded body that is longer in the cylindrical axis direction than in Example 1 and Example 2 will be described. Since the molding process of the cylindrical molded body is the same as that in Example 1, the description thereof is omitted.

The parameters of the cylindrical molded body of Example 3 obtained by the same molding process as Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 194.2 mm
・ Cylinder inner diameter (diameter) = 158.5 mm
・ Cylinder thickness = 17.85 mm
・ Cylinder axis length = 1755mm

Next, the cylindrical molded body was sintered using an electric furnace. Since the sintering conditions of Example 3 are the same as those of Example 1 except for the parameters for introducing oxygen into the hollow portion inside the cylindrical molded body, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 150 L / min
・ Oxygen introduction to the outside of the cylinder = 0 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 155.4mm
・ Cylinder inner diameter (diameter) = 126.8 mm
・ Cylinder thickness = 14.3 mm
・ Length in cylindrical axis direction = 1386mm
・ Sintered body 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 molded body and the cylindrical sintered body shown in Examples 1 to 3 will be described below. In the following comparative example, unlike the example, a cylindrical sintered body that is sintered under the condition that no oxygen is introduced into the hollow portion inside the cylindrical molded body will be described. In the comparative example, instead of introducing oxygen into the hollow portion inside the cylindrical molded body, sintering was performed under the condition of introducing oxygen from the chamber wall portion to the outside of the cylindrical molded body. Since the molding process of the cylindrical molded body is the same as that in Example 1, the description thereof is omitted.

[Comparative Example 1]
The parameters of the cylindrical molded body of Comparative Example 1 obtained by the same molding process as in Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 194.9 mm
・ Cylinder inner diameter (diameter) = 159.0 mm
・ Cylinder thickness = 17.95 mm
・ Length in cylindrical axis direction = 480 mm

Next, the cylindrical molded body was sintered using an electric furnace. Since 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, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 0 L / min
・ Oxygen introduction to the outside of the cylinder = 100 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 155.9mm
・ Cylinder inner diameter (diameter) = 127.2 mm
・ Cylinder thickness = 14.35 mm
・ Length in cylindrical axis direction = 385 mm
・ 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 molded body of Comparative Example 2 obtained by the same molding process as in Example 1 is as follows.
・ Cylinder outer diameter (diameter) = 193.5mm
・ Cylinder inner diameter (diameter) = 158.2 mm
・ Cylinder thickness = 17.65 mm
・ Length in cylindrical axis direction = 600 mm

Next, the cylindrical molded body was sintered using an electric furnace. Since the sintering conditions of Comparative Example 2 are the same as those of Example 1 except for the parameters for introducing oxygen into the cylindrical molded body, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 0 L / min
・ Oxygen introduction to the outside of the cylinder = 100 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 156.7 mm
・ Cylinder inner diameter (diameter) = 128.1 mm
・ Cylinder thickness = 14.3 mm
・ Length in cylindrical axis direction = 485 mm
・ 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]
The parameters of the cylindrical molded body of Comparative Example 3 obtained by the same molding process as in Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 194.1 mm
・ Cylinder inner diameter (diameter) = 158.2 mm
・ Cylinder thickness = 17.95 mm
・ Length in cylindrical axis direction = 1200mm

Next, the cylindrical molded body was sintered using an electric furnace. Since 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, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 0 L / min
・ Oxygen introduction to the outside of the cylinder = 100 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 157.2 mm
・ Cylinder inner diameter (diameter) = 128.1 mm
・ Cylinder thickness = 14.55mm
・ Length in cylindrical axis direction = 957 mm
・ Sintered body 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]
The parameters of the cylindrical molded body of Comparative Example 4 obtained by the same molding process as in Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 194.2 mm
・ Cylinder inner diameter (diameter) = 158.4 mm
・ Cylinder thickness = 17.9mm
・ Length in cylindrical axis direction = 1410 mm

Next, the cylindrical molded body was sintered using an electric furnace. Since 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, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 0 L / min
・ Oxygen introduction to the outside of the cylinder = 100 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 155.3mm
・ Cylinder inner diameter (diameter) = 127.8 mm
・ Cylinder thickness = 13.75 mm
・ Cylinder axis 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]
The parameters of the cylindrical molded body of Comparative Example 5 obtained by the same molding process as in Example 1 are as follows.
・ Cylinder outer diameter (diameter) = 193.6 mm
・ Cylinder inner diameter (diameter) = 158.3 mm
・ Cylinder thickness = 17.65 mm
・ Length in cylindrical axis direction = 1754mm

Next, the cylindrical molded body was sintered using an electric furnace. Since 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, description thereof will be omitted.
・ Introduction of oxygen into the hollow part inside the cylinder = 0 L / min
・ Oxygen introduction to the outside of the cylinder = 100 L / min

Each parameter of the cylindrical sintered body obtained by the above-described sintering process is as follows.
・ Cylinder outer diameter (diameter) = 157.8 mm
・ Cylinder inner diameter (diameter) = 128.5mm
・ Cylinder thickness = 14.65 mm
・ Length in cylindrical axis direction = 1394mm
・ 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 for evaluating the in-solid variation in density and bulk resistance were prepared. As shown in FIG. 9, the cylindrical sintered body 110 is divided by 150 mm from the lower side to the upper side in the cylindrical axis direction during sintering. Furthermore, a cylindrical measurement sample having a width of 40 to 50 mm in each central portion in the cylindrical axis direction is cut out, and measured samples 110-1 (150 mm), 110-2 (300 mm), and 110-3 (450 mm) from below in the cylindrical axis direction. (Name in the table below).

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

  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 part of the cylindrical molded body during sintering, oxygen to the inner hollow part of the cylindrical molded body was obtained. The relative density was improved from the cylindrical sintered bodies of Comparative Examples 2 to 5 without introduction. In Comparative Example 1 in which the length in the cylindrical axis direction is 470 mm or less, the relative density was improved even if oxygen was not introduced into the inner hollow portion of the cylindrical molded body. In each measurement sample of Examples 1 to 3, the relative density difference could be reduced as compared with each measurement sample of Comparative Examples 2 to 5. In Comparative Example 1 in which the length in the cylindrical axis direction was 470 mm or less, the relative density difference could be reduced without introducing oxygen into the inner hollow portion of the cylindrical molded body. In addition, by supplying oxygen to the cylindrical inner surface of the cylindrical molded body in the sintering process, the cylindrical molded body having a length in the cylindrical axis direction of 1200 mm or more can also be prevented from being deformed or cracked during sintering. 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 for sintering cylindrical molded bodies in the above-described Examples and Comparative Examples. Specifically, the amount of oxygen introduced into the hollow portion inside the cylinder at the time of sintering is changed stepwise to obtain a cylindrical sintered body having a length in the cylindrical axis direction of 390, 480, 950, 1200, or 1400 mm. Obtained. The density of each cylindrical sintered body was measured using Archimedes method. Of the cylindrical sintered bodies having a density of 7.130 g / cm ³ or more, the smallest oxygen supply amount is set to the smallest amount of oxygen introduced during sintering for each length in the cylindrical axis direction. FIG. 11 shows the relationship between the minimum oxygen supply amount and the length in the cylindrical axis direction of the cylindrical sintered body.

As shown in FIG. 11, a cylindrical sintered body having a density of 7.130 g / cm ³ or more was obtained even when oxygen was not introduced up to a length of 390 mm in the cylindrical axis direction of the cylindrical sintered body. . In the case of forming a 480 mm cylindrical sintered body, the minimum oxygen supply amount was 5 L / min or more. When forming a cylindrical sintered body of 950 mm, the minimum oxygen supply amount was 20 L / min or more. When a 1200 mm cylindrical sintered body was formed, the minimum oxygen supply amount was 30 L / min or more. In the case of forming a 1400 mm cylindrical sintered body, the minimum oxygen supply amount was 35 L / min or more. From the result of FIG. 11, it can be seen that as the length in the cylinder axis direction is longer, the amount of oxygen necessary to obtain a cylindrical sintered body having a density of 7.130 g / cm ³ or more 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. It can be shown by the following formula.
Y = 0.0345X-12.508

[Evaluation of bulk resistance]
Bulk resistance was evaluated for the cylindrical sintered bodies and the respective 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 on the outer surface of the cylinder using the four-probe method. The bulk resistance values in the cylindrical sintered bodies and the measurement samples of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in FIG.

  From the results of FIG. 12, in the cylindrical sintered bodies and the measurement samples of Examples 1 to 3 and Comparative Examples 1 to 5, the bulk resistance value on the outer surface of the cylinder hardly changed. Since oxygen is sufficiently supplied from the outer surface of the cylinder, even in the examples in which oxygen was introduced into the hollow part inside the cylinder of the cylindrical molded body, the comparative example in which no oxygen was introduced into the hollow part inside the cylinder was out of the cylinder. It is considered that the bulk resistance value on the side surface is hardly affected.

[Preparation of sample for electron microscope observation]
About the cylindrical sintered compact of Examples 1 and 2 and Comparative Examples 2 and 3 mentioned above, the sample for observing with an electron microscope was prepared. As shown in FIG. 13, the cylindrical sintered body 110 cuts out a cylindrical sample 110-4 having a width of 10 mm in the center in the cylindrical axial direction, and is used for electron microscope observation from the cylindrical inner side surface 110-4 a and the cylindrical outer side surface 110-4 b. A sample was cut out and mirror-polished in a state of 0.5 mm grinding.

[Observation with electron microscope]
For cylindrical sintered body of the above-mentioned Examples 1 and 2 and Comparative Examples 2 and 3 were observed electron microscopy sample cylindrical inner surface and an outer surface of the cylindrical sintered body with an electron microscope (SEM). In each sample, photographs taken with a 1000 × field of view using an electron microscope (SEM) are shown in FIG. 14 (cylindrical inside) and FIG. 15 (cylindrical outside). In addition, in each sample, photographs observed with a 2000 × or 5000 × field of view using an electron microscope (SEM) are shown in FIG. 16 (cylindrical inside) and FIG. 17 (cylindrical outside). 17 from FIG. 14 (a) Example 1, (b) Example 2, (c) Comparative Example 2, (d) electron microscopy of the cylindrical inner surface and an outer surface of the cylindrical sintered body of Comparative Example 3 Samples were observed with an electron microscope (SEM).

  14A and 14B are electron micrographs of the side surfaces of the cylindrical sintered body in Example 1 and Example 2. FIG. 15 (a) and 15 (b) are electron micrographs of the outer surface of the cylindrical sintered body in Example 1 and Example 2. FIG. 14C and 14D are electron micrographs of the side surfaces of the cylindrical sintered bodies in Comparative Example 2 and Comparative Example 3. FIG. FIGS. 15C and 15D are electron micrographs of the outer surface of the cylindrical sintered body in Comparative Example 2 and Comparative Example 3. FIG. As shown in FIGS. 14 and 15, in Example 1 and Example 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. 14A) And (b)) and the electron micrographs on the outer surface (FIGS. 15 (a) and (b)), no significant difference was observed. On the other hand, in Comparative Example 2 and Comparative Example 3 in which no oxygen is introduced into the cylindrical inner hollow portion of the cylindrical molded body during sintering, compared with the outer surface of the cylindrical sintered body (FIGS. 15 (c) and (d)). Many large pores (photographs, black irregular shapes) were observed in the electron micrographs of the side surfaces of the cylindrical sintered body (FIGS. 14C and 14D). Many irregular grain-shaped (crystal grain) holes were observed on the inner surface of the cylindrical sintered body in Comparative Examples 2 and 3. The holes observed on the cylindrical inner surface of the cylindrical sintered bodies in Comparative Example 2 and Comparative Example 3 were mainly observed at the grain boundaries.

  Next, in order to observe the state of the crystal particles, in the comparative example, in particular, the region having no large pores observed in FIGS. 14C and 14D was observed with a 2000 × or 5000 × visual field. FIGS. 16A and 16B are electron micrographs of the side surfaces of the cylindrical sintered body in Example 1 and Example 2. FIG. FIGS. 17A and 17B are electron micrographs of the outer surface of the cylindrical sintered body in Example 1 and Example 2. FIG. FIGS. 16C and 16D are electron micrographs of the side surfaces of the cylindrical sintered bodies in Comparative Example 2 and Comparative Example 3. FIG. FIGS. 17C and 17D are electron micrographs of the outer surface of the cylindrical sintered body in Comparative Example 2 and Comparative Example 3. FIG. As shown in FIGS. 16 and 17, in Example 1 and Example 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. 16A). And (b)) and the electron micrographs on the outer surface (FIGS. 17A and 17B), no significant difference was observed, and the crystal grains grew greatly. In the comparative example 2 in which no oxygen is introduced into the hollow portion inside the cylinder of the cylindrical molded body during sintering and the length in the cylindrical axial direction is shorter than that in the comparative example 3, the side surface of the cylindrical sintered body (FIG. 16C). ) And the outer side surface (FIG. 17 (c)), a large difference was not observed, and crystal grains grew greatly. On the other hand, in the comparative example 3 in which no oxygen is introduced into the hollow portion inside the cylindrical molded body during sintering and the length in the cylindrical axis direction is longer than that in the comparative example 2, the outer surface of the cylindrical sintered body (FIG. 17). Compared with (d)), in the electron micrograph of the side surface of the cylindrical sintered body (FIG. 16 (d)), small crystal grains at the initial stage of growth were observed. Since the crystal particles on the side surface of the cylindrical sintered body in Comparative Example 3 were in the initial stage of growth, they were small, non-uniform, and lacked smoothness.

  In the cylindrical inner surface and the outer surface of the cylindrical sintered body in Example 1 and Example 2, small irregular-shaped (bubble-shaped) holes were observed (for example, upper left in FIG. 17B). Hole). Similar small and irregular pores (bubbles) were also observed on the cylindrical outer surface of the cylindrical sintered bodies in Comparative Examples 2 and 3. Holes observed on the cylindrical inner surface of the cylindrical sintered body in Example 1 and Example 2 and on the cylindrical outer surface of the cylindrical sintered body in Example 1, Example 2, Comparative Example 2, and Comparative Example 3 Was observed both at the grain boundaries and within the crystals.

[Evaluation of cylindrical sintered body side surface of the hole]
For cylindrical sintered body of Examples 1-3 and Comparative Examples 1-5, the tissues electron microscope of the cylindrical inner surface and an outer surface in the cylindrical axial direction central portion of the cylindrical sintered body using the method described above (SEM The number of holes and the equivalent circle diameter of the area of the holes were measured. In each sample, five samples for electron microscope observation were cut out in the circumferential direction on the cylindrical inner surface 110-4a of the cylindrical sample 110-4. From each electron microscope observation sample, a field of view of 980 μm × 1200 μm was observed, 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 equation.
FIG. 18 shows the average number of equivalent circle diameters of the number of holes and the area of the holes in 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, there was no oxygen introduction into the cylindrical inner hollow portion. The number of holes on the inner surface of the cylinder was smaller than those of the cylindrical sintered bodies of Comparative Examples 2 to 5. In Comparative Example 1 in which the length in the cylindrical axis direction was 470 mm or less, the number of holes on the inner surface of the cylinder was small even without introducing oxygen into the inner hollow part of the cylindrical molded body. On the cylindrical inner surface of the cylindrical sintered bodies of Examples 1 to 3, the average of the equivalent circle diameters of the areas in the holes was 1 μm or less. On the other hand, on the cylindrical inner surface of the cylindrical sintered bodies of Comparative Examples 2 to 5, the average of the equivalent circle diameters of the areas in the holes was 4 μm or more. In Comparative Example 1 in which the length in the cylinder axis direction is 470 mm or less, the average equivalent circle diameter of the area in the hole on the inner surface of the cylinder is 1 μm or less even without oxygen introduction into the inner hollow part of the cylindrical molded body. It was. 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 are all 4.25 × 10 ⁻⁵ holes / μm ² or less. The average equivalent circle diameter of the area in the hole was 1 μm or less.

  In Examples 1 to 3, the result of ITO was shown. Similarly, in the case of a cylindrical molded body having a length in the cylindrical axis direction of 600 mm or more constituted by each composition of IZO, IGZO, and AZO, the production of the present invention Sintered using the method. In addition, manufacturing conditions can be suitably changed for every composition within the scope of the present invention. As a result, deformation and cracking of the cylindrical sintered body during sintering could be prevented. Moreover, the density of the cylindrical sintered body after sintering could be improved, and further, 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 hole observed on the cylindrical inner surface of the sintered cylindrical body after sintering, and to be observed on the inner cylinder surface of the sintered cylindrical body after sintering. The number of holes could be reduced.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present 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: Pipe 260: Disturbance Plate 280: Opening 300: Chamber

Claims (4)

A cylindrical ITO sintered body having a length in the cylindrical axis direction of 948 mm or more,
The relative density difference in the cylindrical axis direction is within 0.1%;
The average equivalent circle diameter of the holes observed per field of view of 1.176 mm ² in at least five independent areas at the center of the cylinder inner surface and the center of the cylinder outer surface in the cylinder axis direction is 1 μm or less on average. A cylindrical ITO sintered body. A cylindrical ITO sintered body having a length in the cylindrical axis direction of 948 mm or more,
The relative density difference in the cylindrical axis direction is within 0.1%;
The cylindrical ITO sintered body characterized in that the average number of holes observed in the central portion of the inner surface of the cylinder and the central portion of the outer surface of the cylinder in the axial direction is 4.25 × 10 ⁻⁵ holes / μm ² or less. . Holes observed in the cylindrical inner surface and said cylindrical inner and outer sides, cylindrical according to claim 2, characterized in that the holes observed in five fields of view 1.176Mm ² per independent even without least Type ITO sintered body. A sputtering target comprising: the cylindrical ITO sintered body according to any one of claims 1 to 3; and a base material disposed in a hollow portion inside the cylinder.