JP6884126B2 - Cylindrical ceramics-based sputtering target Consists of joining one or more cylindrical ceramics-based sputtering target materials and cylindrical ceramics-based sputtering target materials to a backing tube. - Google Patents

Description

The present invention relates to a cylindrical ceramic sputtering target composed of one or more cylindrical ceramic sputtering target materials and one or more cylindrical ceramic sputtering target materials bonded to a backing tube. In particular, a cylindrical sputtering target material (hereinafter, "cylindrical target material") of a sintered body of a transparent oxide semiconductor such as IGZO (indium gallium oxide zinc), IZO (indim zinc oxide), and ITO (indium tin oxide). ), And a cylindrical sputtering target (hereinafter, referred to as “cylindrical target”) in which one or more of these are joined to a backing tube.

In the cylindrical target material, it is desired to control various bulk characteristics (crystal grain size, relative density, conductivity, etc.) within a suitable range. However, many measurement items (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) are local measurements, and each measurement item is basically considered independently. In addition, when inspecting the performance of a cylindrical target material, it is not possible to inspect and evaluate the product itself with destruction. In addition, in the case of a cylindrical target material, there are some aspects that are more difficult to manufacture than the conventional flat plate type target material, and the composition of the target material, the way heat is transferred in the target material during sintering, and the location where heat is transferred are non-uniform. Due to the non-uniformity of properties and oxygen concentration, it is very difficult to produce a uniform target material as a whole bulk characteristic.

On the other hand, it is known that if there is an abnormal point even at one place on the usage surface of the cylindrical target, problems such as arcing, nodules, and cracks occur. In fact, cylindrical targets often cause anomalies such as arcing and nodules during sputtering. Even if each measurement item (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) related to the factors that affect the sputter is inspected for the target that has an abnormality during sputtering, each factor that affects the spatter is determined. In many cases, there were no abnormalities, and in such cases, the cause of abnormalities such as arcing and nodules during sputtering was unknown. Therefore, if there are no abnormalities in each measurement item (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) related to the factors that affect the sputtering of the cylindrical target, it is necessary to actually perform the sputtering. There was a problem that the problematic cylindrical target or cylindrical target material could not be detected. From this point of view, an index for comprehensively evaluating and managing the entire cylindrical target material is desired.

As a result of diligent studies, the present inventors have come to the conclusion that evaluation using macroscopic, that is, comprehensively observed results is important. Conventionally, in manufacturing a sintered body, the relative density and crystal grains have been controlled by changing the sintering conditions and the like to improve the characteristics at the time of sputtering. However, since the crystal grain evaluation generally uses an index of the average crystal grain size (measured by a coding method or the like with reference to an SEM photograph taken in an observation field of several hundred to several thousand times), it is a cylinder. It was limited to the evaluation of the local part of the shape target material.

However, the distribution of crystal grains in the cylindrical target material can be roughly divided into the following four patterns. The first pattern is a stepwise distribution from small particles to large particles, the second pattern is when there are large particles with abnormal grain growth among the small particles, and the third pattern has a bipolar particle size. The fourth pattern is when all the crystal grains are uniform.

Of the above four patterns, the problem is mainly the existence of patterns having different sizes between groups of crystal grains when the first pattern to the third pattern are viewed macroscopically. A pattern in which the size of the crystal grains differs between the group and the group of crystal grains (that is, when the region where crystal grains that are homogeneous to some extent are gathered is regarded as a group, not the difference between the individual crystal grains when viewed microscopically. , A plurality of groups exist, and each of the plurality of groups is composed of crystal grains having different diameters.) In many cases, cracks occur at the interface between the groups. Further, the strength is different for each region in the cylindrical target material according to the crystal particle size, and there arises a problem that the surface roughness also changes when the surface is cut. Therefore, it is important to comprehensively evaluate and manage the characteristics of the entire cylindrical target material.

In Patent Document 1, the average particle size of the compound contained in the sputtering target of the oxide semiconductor is set to 10 μm or less, preferably 6 μm or less, more preferably 4 μm or less, and the surface portion of the target after the baked surface is removed. By controlling the color difference ΔE of the portion ground by 2 mm from this surface portion with a surface grinding machine to a predetermined value or less and setting the specific resistance to a predetermined value or less, an oxide thin film such as an oxide semiconductor or a transparent conductive film can be obtained. It is described that it is not necessary to increase the oxygen partial pressure at the time of forming a film, and it is possible to obtain a sputtering target in which aggregates are less likely to be formed and the occurrence of abnormal discharge is suppressed. However, according to the experimental results described in Patent Document 1, it can be confirmed that the specific resistance is set to a predetermined value or less only in relation to the crystal grain size, and basically the control of the color difference has nothing to do with it.

Patent Document 2 discloses a target in which the generation of particles during sputtering is remarkably suppressed by controlling the stoichiometric deviation of the component composition of the sputtering target by controlling the color of the target. However, the color itself is a problem, not the color difference ΔE * ab. Further, the manufacturing method is a conventional manufacturing method for a flat plate target, and is not related to a cylindrical target. Patent Document 3 describes that the color unevenness of the sputtering target has a problem that the heat radiation from the target surface becomes non-uniform and a temperature difference is likely to occur when the sputtering heat is generated. Therefore, in order to suppress the color unevenness, an additive is added. Zinc oxide sintered bodies containing one or more of Zr, Si and Al have been proposed. However, the sputtering target described in Patent Document 3 relates to a conventional flat plate type target, and since color unevenness is prevented by a configuration in which an additive is contained in the target, the composition of the target is a thin film to be sputtered. It is not a fundamental solution as it will be different from the desired composition. In Patent Document 4, the difference in color (color unevenness) is merely a local evaluation of the target because the difference in color between the surface and the inside of the sintered body is a problem. Moreover, it relates to a conventional flat plate type target, and a specific method for eliminating the color difference between the surface and the inside is also the same as in Patent Document 3, which is an additive Al, Ga, B, Nb, In, Y, At least one element selected from Sc is contained. Therefore, in the invention described in Patent Document 4, even if the color difference between the surface and the inside of the target can be eliminated as in Patent Document 3, the composition of the target is different from the desired composition of the thin film to be sputtered. Therefore, it is not a fundamental solution.

WO2012-153522 Japanese Unexamined Patent Publication No. 2001-11614 JP-A-2010-202896 Japanese Unexamined Patent Publication No. 2010-150107

The object of the present invention is to set various bulk characteristics (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) to a suitable range locally individually, that is, to grasp a plurality of parameters basically independently. It is to provide a cylindrical target capable of suppressing the occurrence of arcing, nodules, and cracks that could not be prevented only by the evaluation. Specifically, the homogenization of the entire target material is ensured by taking into account not only the observation results of factors affecting individual sputters regarding the characteristics of the cylindrical target material but also the macroscopic observation results of the entire target material. It is an object of the present invention to provide a cylindrical target material capable of the above, and a cylindrical target in which one or more of these cylindrical target materials are joined to a backing tube.

In order to solve the above problems, the present inventors have focused on the color difference ΔE * ab of the cylindrical target material. That is, even if each measurement item (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) relating to the factors affecting the spatter is inspected, there is no abnormality in the factors affecting the spatter. Regardless of this, the cylindrical targets that caused abnormalities such as arcing and nodules when actually sputtered were targets in which the color difference ΔE * ab on the surface of the cylindrical target material was different depending on the region. On the other hand, in the case of a cylindrical target in which the color difference ΔE * ab on the entire surface of the cylindrical target material looks almost the same visually, there is a tendency that abnormalities such as arcing and nodules are less likely to occur when sputtered. As a result of diligent studies, the present inventors have found that the color difference ΔE * ab is effective as an index for evaluating and managing the entire individual sintered body. The color difference ΔE * ab can be regarded as the overall result of the bulk characteristics of each cylindrical target material, and making the color difference ΔE * ab as uniform as possible in the sintered body suppresses abnormalities in sputtering. I found out. As described above, the color difference ΔE * ab was found as an index for stabilizing the overall characteristics of the cylindrical target material, and the invention was completed.

In the present specification, the color difference ΔE * ab was measured by NF333 manufactured by Nippon Denshoku Kogyo Co., Ltd. The color difference can be expressed by the following equation 1.
ΔE * ab = ((ΔL *) ^ 2 + (Δa *) ^ 2 + (Δb *) ^ 2) ^ 0.5 (Equation 1)

The crystal grains represent the structure of the cylindrical target material and have a great influence on the conductivity and the like. The color difference ΔE * ab is affected by the structure and physical shape of the target such as relative density, crystal grain size, and surface roughness. In the present invention, the color difference Δ * affected by the structure and physical shape of the target material such as relative density, crystal grain and surface roughness is bulked by being aware of the overall color difference Δ * of the cylindrical target material. It makes it possible to provide an overall homogeneous sputtering target.

According to the present invention, the cylindrical target material is divided into four at equal intervals in the axial direction thereof, and the intervals of 0 °, 90 °, 180 ° and 270 ° in the circumferential direction are further divided into four regions. Provided is a cylindrical target material characterized in that the color difference ΔE * ab at two predetermined points in each measurement region is 1 or less when each of the 16 regions partitioned by is defined as a measurement region. To. Further, the cylindrical target is divided into four at equal intervals in the axial direction, and each of the four divided regions is divided into 0 °, 90 °, 180 °, and 270 ° in the circumferential direction. When each of the 16 partitioned regions is used as the measurement region, one or more sputtering targets characterized in that the color difference ΔE * ab at two predetermined points in each measurement region is 1 or less are prepared, and these are Ti. Cylindrical targets bonded to backing tubes made of alloys containing, Cu or these metals are provided.

The relative density of the cylindrical target material according to the present invention is preferably 99% or more.

According to the present invention, homogenization of the entire target is performed by taking into account not only the observation results of factors affecting individual sputters regarding the characteristics of the cylindrical target material but also the results of macroscopic and comprehensive observation of the entire target material. By securing, various bulk characteristics (crystal grain size, relative density, bulk resistance value, surface roughness, etc.) could not be prevented only by individually setting them in a suitable range. It is possible to provide a cylindrical target material capable of suppressing the above-mentioned conditions and a cylindrical target to which the material is joined to a backing tube.

Further, according to the present invention, by joining a plurality of cylindrical targets to the backing tube, a particularly advantageous effect can be obtained when a cylindrical sputtering target of an arbitrary length is formed as a result. That is, when joining a plurality of targets to the backing tube, if even one of the joined cylindrical target materials contains a target that generates arcing, the other non-problematic cylindrical target material is also wasted. There is a risk that it will end up. According to the present invention, it is possible to join to the backing tube except for the problematic cylindrical target material which cannot be detected by local and individual analysis, and the other non-problematic cylindrical target material is also wasted. It is possible to prevent the problem of spilling.

The figure which shows the region for measuring the crystal grain size, the color difference ΔE * ab, and the surface roughness of a cylindrical target. The figure which shows the region for measuring the crystal grain size, the color difference ΔE * ab, and the surface roughness of a cylindrical target. The figure which shows the region for measuring the crystal grain size, the color difference ΔE * ab, and the surface roughness of a cylindrical target as a development view of a target material.

Hereinafter, the cylindrical target material according to the present invention and a method for producing the same will be described with reference to the drawings. However, the cylindrical target material of the present invention and the method for producing the same can be carried out in many different modes, and are not construed as being limited to the contents of the embodiments shown below. In the drawings referred to in the present embodiment, the same parts or parts having the same functions are designated by the same reference numerals, and the repeated description thereof will be omitted.

The cylindrical target material of the present invention can be produced by processes such as mixing, pulverizing, and sintering various raw material powders. For example, the case of an IGZO sputtering target will be described as an example. As the raw material powder, indium oxide (In ₂ O ₃ ) powder, gallium oxide (Ga ₂ O ₃ ) powder, zinc oxide (ZnO) powder, and tin oxide (SnO ₂ ) powder are prepared.

The raw material powder is weighed so as to have a desired composition ratio, and then mixed. If the mixing is insufficient, each component segregates in the produced target, and a high resistivity region and a low resistivity region exist. Therefore, sufficient mixing is required. For example, in a super mixer, the mixture is mixed at a rotation speed of 2000 to 4000 rpm and a rotation time of 3 to 5 minutes. Alternatively, a method such as long-time mixing with a ball mill may be used, and other methods are not particularly limited as long as they can achieve uniform mixing of the raw materials.

Next, the mixed powder is calcined by holding the mixed powder in an electric furnace in an air atmosphere in a temperature range of 900 to 1100 ° C. for about 4 to 6 hours. However, depending on the optimization of the target manufacturing process conditions including the sintering conditions, it is not always necessary to perform calcining. When performing calcining, finely pulverize. If it is not sufficiently finely pulverized, raw material powder having a large particle size will be present, which will cause uneven composition in the plane of the sputtering target. The calcined powder is put into an attritor and finely pulverized at a rotation speed of 200 to 400 rpm and a rotation time of 2 to 4 hours.

Next, granulation is performed. This is to improve the fluidity of the raw material powder and to make the filling condition at the time of press molding sufficiently good. Granulation is performed by adjusting the water content of the finely pulverized raw material so as to form a slurry having a solid content of 40 to 60%.

Next, the granulated powder is molded by a hydrostatic pressure presser (CIP) under ^{the conditions of, for example, a surface pressure of 1700 to 1900 kgf / cm 2} and holding for 1 to 3 minutes.

A sintered body can be obtained by holding the molded cylindrical target in an oxygen atmosphere in an electric furnace in an oxygen atmosphere, for example, after raising the temperature to 1400 to 1500 ° C. for 10 to 30 hours.

Normally, in order to improve the relative density, it is desirable to sinter at as high a temperature as possible for a long time, but in order to control the value of crystal grains, it is necessary to avoid sintering at a high temperature and for a long time. It is possible to control the grain diameter and relative density to desired values by the sintering temperature and sintering time.

Finally, the surface of the sintered body is ground. By grinding, the flatness of the surface is ensured.

A cylindrical target is formed by joining one or more cylindrical target materials whose surface flatness is ensured by polishing to a backing tube via a bonding material containing In or In. The material of the backing tube is not particularly limited. The metal used for the backing tube is generally Ti, Cu or an alloy containing Ti and / or Cu.

In order to clarify the relationship between crystal grain size, surface roughness and color difference ΔE * ab, the cylindrical IZO target is manufactured by changing the sintering time and sintering temperature conditions by the method for manufacturing a cylindrical target represented by the above IGZO target. A plurality of materials, a cylindrical ITO target material, and a cylindrical IGZO target material were produced, and the crystal grain size, surface roughness, color difference ΔE * ab, and relative density were measured and used as samples for a discharge test.

As a means for producing a target material in which the color difference ΔE * ab does not vary in the entire surface region of the cylindrical target, the raw material powder particle size is 30 to 60 μm, and the tap density is 1.8 g / cm ³ or more. Is desirable. Further, it is also possible to perform sintering after machining so that the variation in the thickness of the CIP molded product is 0.1 mm or less.

Therefore, all of the cylindrical target materials according to the examples of the present invention were sintered after being machined so that the variation in the thickness of the CIP molded product was 0.1 mm or less. The shape of the target was unified to 153 mmφ in outer diameter, 135 mmφ in inner diameter, and 210 mm in length in both Examples and Comparative Examples.

The measurement points of the crystal grain size, surface roughness and color difference ΔE * ab are as follows. As shown in FIGS. 1, 2 and 3 (developed view of the target material), the target is divided into four at equal intervals in the axial direction of the target, and each of the four divided regions is 0 ° and 90 ° in the circumferential direction. , 180 ° and 270 ° were divided into 16 regions as measurement regions. The specific measurement point in each measurement area was the center of each measurement area (diagonal intersection). However, for the color difference ΔE * ab, the points (2 points, P1 and P2 in FIG. 2) that divide one diagonal line into three equal parts in each measurement area are set as the measurement points in each measurement area, and the color difference ΔE of these two points. * Ab. In this way, the reason why the color difference ΔE * ab on the surface of the target material was measured evenly is that when the target material is observed macroscopically, the color difference ΔE * ab of the cylindrical target material is the region at both ends in the axial direction of the target. This is because it is considered that there may be a large difference in the area between them, and that the present invention aims to comprehensively evaluate the entire target material. This is also because the color difference ΔE * ab may be significantly different in the circumferential direction of the cylindrical target material.

One factor that causes such a situation is that groups having different crystal grain sizes are formed as the distribution of crystals. This is because the cylindrical target material is different from the flat plate type target material, and at the time of sintering, the cylindrical target material is sintered in an axially vertical state, so that it depends on the axial region of the cylindrical target material. This is because the way heat is transferred is different. Another factor is the variation in the thickness of the CIP molded body of the cylindrical target material before sintering the cylindrical target material.

Therefore, the above-mentioned crystal grain size, surface roughness, and color difference ΔE * ab are measured to classify the regions where the difference in heat transfer during sintering and the thickness of the CIP molded product of the cylindrical target material are likely to vary. Defined as an area. When the axial length of the cylindrical target material exceeds 210 mm, it is desirable to additionally perform the same measurement every 50 mm.

The crystal grain size was measured by the following method. First, an observation sample was cut out from the target, and the surface of the cut out sample was mirror-polished. The surface of the mirror-polished sample was photographed with a scanning electron microscope (SEM), the crystal grain size of a plurality of fields (5 points) was measured by the evaluation method of the coding method, and the average value was evaluated.

^{The relative density was measured by cutting out a measurement sample of 20 cm 2} from the cylindrical target material and measuring the density of the cut out measurement sample by the Archimedes method. The relative density referred to in the present specification was calculated by (measured density / theoretical density) × 100 (%). Here, the "measured density" can be calculated by weight / volume from each measured value, but the Archimedes method is generally used, and the same method is also adopted in the present invention. The theoretical density is a density value calculated from the theoretical density of oxides of the elements 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 theorized as oxides of indium and tin excluding oxygen among the constituent elements indium, tin, and oxygen. Used to calculate density. Here, the elemental analysis value (at% or mass%) of indium and tin in the sintered body is converted into the mass ratio 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 in which indium oxide is 90% by mass and tin oxide is 10% by mass, the theoretical density is (In ₂ O ₃ density (g / cm ³ ) × 90 + SnO ₂ density (g / g /). Calculate as 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, 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 .

The conductivity (surface bulk resistance value) was measured using a four-probe type resistance measuring instrument. The surface roughness (arithmetic mean roughness, Ra) is measured by comparing a plurality of values measured in a range of 1 mm or less using a stylus type measuring device and using a representative value as the surface roughness (Ra) value. And said. The arithmetic mean roughness is based on JISB0601-2001, and examples of the measuring device include SJ-210 (manufactured by Mitutoyo).

The discharge test was carried out under the conditions that Ar was used as the sputtering gas, the sputtering pressure was 0.6 Pa, the sputtering gas flow rate was 300 sccm, and the sputtering power was 4.0 W / cm ^2.

The cylindrical target material made of ITO of Example 1 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. The measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance measured in each of the 16 regions partitioned by dividing by °, 180 ° and 270 ° are as follows. It became Table 1. In the table below, the four regions displaced by 90 ° in the circumferential direction are represented as A, BC, and D, respectively.

The cylindrical target material made of ITO of Example 2 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and each of the four divided regions is 0 ° and 90 in the circumferential direction. Table 2 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance in each of the 16 regions divided by the intervals of °, 180 ° and 270 °. It became.

The cylindrical target material made of ITO of Comparative Example 1 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. Table 3 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IGZO of Example 3 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. Table 4 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IGZO of Example 4 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and each of the four divided regions is 0 ° and 90 in the circumferential direction. Table 5 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IGZO of Comparative Example 2 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. Table 6 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IZO of Example 5 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and each of the four divided regions is 0 ° and 90 in the circumferential direction. Table 7 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IZO of Example 6 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. Table 8 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

The cylindrical target material made of IZO of Comparative Example 3 is divided into four at equal intervals in the axial direction, divided into four at equal intervals in the axial direction of the target, and further divided into four regions at 0 ° and 90 in the circumferential direction. Table 9 below shows the measurement results of crystal grain size, surface roughness and color difference ΔE * ab, relative density and bulk resistance within each of the 16 regions partitioned by dividing by °, 180 ° and 270 °. It became.

In Comparative Example 1, nodules were confirmed to occur in the first region and the fourth region in the discharge test. The color difference ΔE * ab in the C region of the first region was 1.097. In the fourth region, the color difference ΔE * ab in the C region was 1.162. It is presumed that if the color of the target material is different to the extent that the color difference ΔE * ab in each region exceeds 1.0, it causes nodules. On the other hand, in Examples 1 and 2, the color difference ΔE * ab in the adjacent region is less than 1.0.

In Comparative Example 2, in the discharge test, crack generation was confirmed around the first region and the fourth region. The color difference ΔE * ab in the D region of the first region was 1.364. The color difference ΔE * ab of D in the fourth region was 1.528. It is presumed that if the color of the target material is different so that the color difference ΔE * ab in each region exceeds 1.0, it may cause cracks. On the other hand, in Examples 3 and 4, the color difference ΔE * ab in each region is less than 1.0.

In Comparative Example 3, cracks were confirmed in the entire cylindrical target material in the discharge test. The color difference ΔE * ab in the D region of the first region was 2.150. The color difference ΔE * ab of D in the third region was 1.722. Further, the color difference ΔE * ab in the D region of the fourth region was 3.045. If the color of the target material is different to the extent that the color difference ΔE * ab in each region exceeds 1.0, it is presumed to be the cause of cracks. On the other hand, in Examples 5 and 6, the color difference ΔE * ab in each region is less than 1.0.

From the above, it can be said that if the color difference ΔE * ab in each region is set to at least 1.0, arcing, nodules, etc. do not occur during sputtering. On the other hand, when the color difference ΔE * ab becomes 1.0 or more, arcing or the like occurs. When the color difference ΔE * ab is about 1.0 to 3.0, the color difference is almost inconspicuous visually, but according to the experiment, even if there is such a color difference that cannot be visually distinguished, arcing or the like occurs. found. Looking at the relationship between the crystal grain size and the color difference Δ * ab, for example, looking at Table 6, which is the analysis result of Comparative Example 2 which is a comparison of the cylindrical target materials of IGZO, the size of the crystal grain size and the color difference It can be seen that there is a correlation with ΔE * ab. However, looking at Comparative Example 3, which is a comparative example of the cylindrical target of IZO, the color difference ΔE * ab is the same as the particle size of the example of the cylindrical target of IZO. The value of was variable and cracks occurred. On the other hand, in the embodiment in which the color difference ΔE * ab in each region is controlled to be less than 1.0, the color difference ΔE * ab in each region is less than 1.0 because no cracks or nodules are generated. It can be seen that cracks and nodules can be prevented as long as they are controlled.

The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit.

Claims (5)

A method for evaluating a cylindrical ceramic sputtering target material made of ITO, IGZO or IZO having an axial length of 210 mm or less.
The cylindrical ceramic sputtering target material is divided into four at equal intervals in the axial direction, and each of the four divided regions is divided at intervals of 0 °, 90 °, 180 °, and 270 ° in the circumferential direction. A method for evaluating whether or not the color difference ΔE * ab at two points in each of the measured regions is less than 1.0. A method for evaluating a cylindrical ceramic sputtering target material made of ITO, IGZO or IZO having an axial length of more than 210 mm.
From one end of the cylindrical ceramic sputtering target material to 210 mm, it is divided into four at equal intervals in the axial direction, and each of the four divided regions is 0 °, 90 °, 180 ° and 270 ° in the circumferential direction. The color difference ΔE * ab at two points in each measurement area divided by the interval is less than 1.0.
In a region exceeding 210 mm from one end of the cylindrical ceramic sputtering target material, it is divided into 50 mm intervals in the axial direction, and the intervals of 0 °, 90 °, 180 ° and 270 ° in the circumferential direction are further divided in each divided region. A method of evaluating whether or not the color difference ΔE * ab at two points in each measurement area divided by is less than 1.0. The method for evaluating a cylindrical ceramic sputtering target material according to claim 1 or 2, which comprises evaluating whether or not the relative densities measured in the measurement region are 99% or more. The cylindrical ceramics-based sputtering target material according to any one of claims 1 to 3, which includes evaluating whether or not the average crystal grain size measured in the measurement region is 10 μm or less. Method. The cylindrical ceramics-based sputtering target material according to any one of claims 1 to 4, which includes evaluating whether or not the surface roughness measured in the measurement region is 0.5 μm or less. how to.

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