RU2785507C2 - Golden sprayed target and its production method - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to a golden sprayed target and its production method (options). The golden target has gold purity of 99.999% or more. An average value of Vickers hardness is 20 or more and less than 40, an average size of crystal grain is 15 mcm or more and 200 mcm or less, and golden plane {110} is mostly oriented to a surface to be sprayed of the golden sprayed target. The method for the production of the golden sprayed target, according to the first option, includes processing of a gold bar for formation of a plate golden billet, hot forging, or hot rolling of the golden billet, or cold rolling of the golden billet, and thermal processing of target material. The method for the production of the golden sprayed target, according to the second option, includes processing of a gold bar for formation of a cylindrical golden billet, cold pressing of the golden billet, multiple cold drawing of the golden billet, or hot forging of the golden billet, and thermal processing of the target.

EFFECT: obtainment of a golden sprayed target providing improvement of uniformity of distribution of a thickness of film of high-purity gold during spraying.

10 cl, 15 tbl, 33 ex

Description

FIELD OF THE INVENTION

[0001] The embodiments described herein generally relate to a gold sputter target and a method for producing the same.

BACKGROUND OF THE INVENTION

[0002] The gold (Au) film formed using the gold (Au) sputtering target has excellent chemical resistance and electrical characteristics of Au itself, and thus is applied in various fields. For example, a crystal oscillator uses an Au sputter film as, for example, an excitation electrode formed on both surfaces of a quartz crystal. In such a crystal oscillator, the oscillation frequency is controlled by the thickness of the Au film, and thus an Au sputter target is required to provide an Au film having a uniform thickness distribution formed during sputtering.

[0003] The sputtered target is usually in the form of a round or rectangular plate, which is used for planar magnetron sputtering. In addition, a cylindrical sputtering target is also known. The cylindrical sputter target has a higher utilization of the target material during sputtering than the lamellar sputter target, so the use of such a cylindrical sputter target began for ceramic materials and then for targets based on metals and alloys. In addition, the use of a cylindrical sputter target for noble metal targets such as a silver (Ag) target has been studied (see Patent Documents 1 and 2).

[0004] The use of a cylindrical target as well as a plate sputter target was also studied for an Au sputter target to form an Au film. However, for conventional Au sputter targets, it is difficult to achieve the high uniformity of film thickness distribution required for an Au film used as an electrode, for example, a crystal oscillator, regardless of whether they are of plate type or cylindrical type. In particular, the cylindrical Au sputtering target has great difficulty in improving the uniformity of the distribution of thickness of the Au film in terms of processing accuracy of the cylindrical shape.

[0005] The following describes crystal oscillators in more detail. Crystal oscillators are used, for example, for mobile devices and must be small, light weight and thin due to the need to reduce the size, weight and thickness of mobile devices. For example, the packing size of the crystal oscillator has decreased from 5.0mm×3.2mm (size 5032) to 3.2mm×2.5mm (size 3225), 2.5mm×2.0mm (size 2520), 2.0mm × 1.6mm (size 2016) and 1.6mm × 1.2mm (size 1612), and accordingly the crystal oscillator itself (quartz crystal) has decreased.

[0006] The crystal oscillator has an Au film on both surfaces of the quartz crystal (blank) as an electrode, as described above. The quartz crystal has an external shape with rounded corners, which can be obtained by etching or by machining after pressing so as to move the center of gravity closer to the center to stabilize the frequency. When the quartz crystal has a rough surface, its frequency response deteriorates, so the quartz crystal is required to have a high surface smoothness. Similarly, an electrode formed in a quartz crystal should have high smoothness, i.e. have a slight variation in film thickness. The electrode has a three-dimensional structure having a given thickness, so that in a miniature quartz crystal, variations in film thickness have a large effect on the three-dimensional structure. Thus, in order to comply with the miniaturization of a crystal oscillator and the like, the thickness variation of the Au film used as an electrode should be smaller.

[0007] In a 32 kHz crystal clock oscillator, variation in the mass of the Au film has a large effect on frequency response. The 32 kHz crystal oscillator includes a tuning fork type and a customizable tuning fork type in terms of shape. Tunable tuning fork crystal oscillator suitable for miniaturization; however, the weight variation of the Au film affects the frequency response, so that a reduction in the mass variation resulting from the variation in thickness of the Au film is required. The tuned tuning fork crystal oscillator has difficulty in adjusting the frequency, and thus various modifications have been made to overcome this shortcoming. For example, with regard to the method of forming the Au film, sputtering is now replaced by vapor deposition. In addition, a part of the Au film formed by sputtering is removed with a laser beam to adjust the mass, or the mass is adjusted during formation of the Au film by sputtering.

[0008] In such a situation where the mass variation resulting from the Au film thickness variation can be reduced, the time and cost required for frequency adjustment can be significantly reduced. In particular, the effect of film thickness variation becomes larger when the crystal oscillator is reduced in size, whereby the mass is likely to vary. In this regard, it is also required to reduce the variation in the thickness of the deposited Au film. In addition, a high purity Au film may be required depending on the purpose of the Au film. For example, when an Au film having an Au purity of 99.999% or more is formed by sputtering, a sputter target having an Au purity of 99.999% or more is used; in such a case, the thickness of the Au film probably varies. Thus, it is required to reduce the variation in the thickness of the Au sputtered film when a high purity Au sputter target is used.

LIST OF CITATIONS

Patent Documents

[0009] Patent Document 1: JP-T-2009-512779

Patent Document 2: JP 2013-204052A

Patent Document 3: WO 2015/111563

SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to provide a gold sputter target that improves the uniformity of high purity Au film thickness distribution and a method for producing such a gold sputter target.

[0011] The gold sputter target of the present invention contains gold of a purity of 99.999% or more, an average Vickers hardness value of 20 or more and less than 40, an average crystal grain size of 15 µm or more and 200 µm or less, and the {110} plane of gold is predominantly oriented towards the surface of the gold sputtering target to be sputtered.

[0012] The method for producing a gold sputter target according to the present invention includes: obtaining a gold sputter target containing gold of a purity of 99.999% or more, in which the average Vickers hardness value is 20 or more and less than 40, the average crystal grain size is 15 μm or more and 200 µm or less, and the {110} plane of gold is predominantly oriented towards the surface of the gold sputtering target to be sputtered.

EFFECT

[0013] By performing sputter film formation using the high reproducibility gold sputter target thus formed, a high-purity gold film excellent in film thickness distribution uniformity can be obtained.

DETAILED DESCRIPTION

[0014] Next, one embodiment of the present invention will be described. The sputtering target according to this embodiment is made of gold (Au) and unavoidable impurities. The purity of Au in the sputtered target is 99.999% or more. The use of a sputtering target having an Au purity of 99.999% or more makes it possible to obtain a high-purity Au film. Unavoidable impurities (elements other than Au) contained in the Au of the sputtered target are not limited to specific elements as long as the Au purity described above is achieved. The upper limit of the purity of Au in the Au of the sputtered target is also not limited to a particular value, and is set according to the purity required for the formed sputtered film of Au, is generally 99.9999% or less, considering, for example, the production method and production cost of the Au of the sputtered target, and it is practically preferable 99.9990% or more and 99.9998% or less.

[0015] The shape Au of the sputtering target according to this embodiment is not limited to a particular shape, and may be a plate shape or a cylindrical shape. The plate sputter target typically includes, for example, a polygonal (eg round or rectangular) plate sputter target. Such a polygonal plate sputtering target may have any structure; for example, it may have a hollow portion formed by removing a portion of a round plate or a polygonal plate, or may have an oblique, convex portion, or a concave portion on a surface portion of the round plate or polygonal plate. Similarly, the cylindrical sputtering target is not limited to specific sizes, and its size is selected according to the sputtering device. A typical cylindrical sputter target has, for example, an outer diameter of 50 mm or more and 170 mm or less, an inner diameter of 20 mm or more and 140 mm or less, and a length of 100 mm or more and 3000 mm or less. Such an Au sputter target has a surface to be sputtered. The surface of the plate serves as the surface to be sputtered in the plate sputter target, and the surface of the cylinder (cylindrical surface) serves as the surface to be sputtered in the cylindrical sputter target.

[0016] The Au sputter target according to this embodiment preferably has a Vickers hardness of 20 or more and less than 40. Au, excellent in thickness distribution uniformity. That is, a Vickers hardness of 40 TB or more of the sputter target Au means that the stress generated at the time of production remains in the sputter target Au having an Au purity of 99.999% or more. In such a case, the particles ejected from the target fly unevenly during sputtering, impairing the uniformity of the film thickness distribution. The Vickers hardness Au of the sputtered target is preferably 35 TB or less, and even more preferably 30 TB or less. On the other hand, when the Vickers hardness is less than 20 TB, it is difficult to obtain the Au sputter target itself. In addition, the orientation of the crystal can be disturbed during the growth of the crystal grain, which will worsen the uniformity of the film thickness distribution. The Vickers hardness Au of the sputtered target is preferably 23 TB or more, and even more preferably 26 TB or more.

[0017] The Vickers hardness Au of the sputtered target is measured as follows. In the case of a plate spray target, the following nine measurement points are set: three points are set at 10 mm intervals in a straight line on the surface to be sprayed, three points are selected respectively from three divided areas obtained by dividing by three the first section perpendicular to the surface to be sprayed in the direction thickness (in the following examples, three points at intervals of 1.5 mm on a straight line passing in the direction of the thickness of the sample having a thickness of 5 mm), and three points selected respectively from three areas obtained by dividing by three the second section perpendicular to the one to be sprayed surface and the first section in the thickness direction (in the following examples, three points are set at 1.5 mm intervals on a straight line passing in the thickness direction of the sample having a thickness of 5 mm). The Vickers hardness is then measured at the above nine measurement points with a test force of 200 gf (compressive load). The average value (HV _av1 ) of the Vickers hardness in the surface to be sprayed, the average value (HV _av2 ) of the Vickers hardness in the first section and the average value (HV _av3 ) of the Vickers hardness in the second section are determined. The average values (HV _av1 , HV _av2 and HV _av3 ) in the surface to be sputtered, the first section and the second section are additionally averaged, and the resulting average value is determined as the average value (HV _tav ) of the Vickers hardness of the entire lamellar Au sputtered target.

[0018] In a lamellar Au sputtered target, the ratio (HV _av1 /HV _tav ) of the average value (HV _av1 ) of the Vickers hardness of the surface to be sprayed to the Vickers hardness (HV _tav ) of the entire target, the ratio (HV _av2 /HV _tav ) of the average value (HV _av2 ) Vickers hardness in the first section to the Vickers hardness (HV _tav ) of the entire target and the ratio (HV _av3 /HV _tav ) of the average value (HV _av3 ) of the Vickers hardness in the second section to the Vickers hardness (HV _tav ) of the entire target targets preferably fall within the range of 0.8 to 1.2. That is, the change in Vickers hardness Au of the sputtered target is preferably ±20%. By reducing local variations in the Vickers hardness Au of the sputtered target, the direction of particle flight during sputtering is made uniform, which improves the film thickness distribution uniformity.

[0019] In the case of a cylindrical Au sputtering target, the following nine measurement points are set: three points are set at 10 mm intervals along the first straight line parallel to the cylindrical axis in the surface to be sputtered (cylindrical surface), three points are set at 10 mm intervals along the second straight line line obtained by rotating the first straight line by 90°, and three points are selected respectively from three areas obtained by dividing into three sections, perpendicular to the cylindrical axis in the thickness direction (in the following examples, three points are set at intervals of 1.5 mm on a straight line, passing in the direction of the thickness of the sample having a thickness of 5 mm). The Vickers hardness is then measured at the above nine measurement points with a test force of 200 gf (compressive load). Determine the average value (HV _av1 ) of the Vickers hardness on the first straight line in the surface to be sprayed, the average value (HV _av2 ) of the Vickers hardness on the second straight line and the average value (HV _av3 ) of the Vickers hardness in the section. The average values (HV _av1 , HV _av2 and HV _av3 ) in the surface to be sputtered and the cross section are further averaged, and the resulting average value is determined as the average value (HV _tav ) of the Vickers hardness of the entire cylindrical Au sputtered target.

[0020] In a cylindrical Au sputtered target, the ratio (HV _av1 /HV _tav ) of the average value (HV _av1 ) of the first Vickers hardness in the surface to be sprayed to the Vickers hardness (HV _tav ) of the entire target, the ratio (HV _av2 /HV _tav ) of the average the value (HV _av2 ) of the second Vickers hardness in the surface to be sprayed to the Vickers hardness (HV _tav ) of the entire target and the ratio (HV _av3 /HV _tav ) of the average value (HV _av3 ) of the Vickers hardness in cross section to the Vickers hardness (HV _tav ) of the entire target preferably fall in the range from 0.8 to 1.2. That is, the change in Vickers hardness Au of the sputtered target is preferably ±20%. By reducing local variations in the Vickers hardness Au of the sputtered target, the direction of particle flight during sputtering is made uniform, which improves the film thickness distribution uniformity. The cylindrical Au sputter target is rotated during sputtering, whereby the entire cylindrical surface is sputtered, so that reducing local variations in the Vickers hardness of the sputtered target (cylindrical surface) can improve film thickness distribution uniformity.

[0021] The Au sputter target according to this embodiment preferably has an average crystal grain size of 15 µm or more and 200 µm or less. By performing sputtering using an Au sputter target having such an average crystal grain size, the thickness distribution of the Au film can be further improved. When the average crystal grain size of Au of the sputtered target is less than 15 μm, particles ejected from the target fly unevenly during sputtering, which may degrade film thickness distribution uniformity. The average size of the Au crystal grains of the sputtered target is preferably 25 µm or more, even more preferably 30 µm or more, and most preferably 33 µm or more. When the average size of the Au crystal grains of the sputtered target exceeds 200 μm, the flying properties of the particles during sputtering are reduced, which may deteriorate the uniformity of the film thickness distribution. The average size of the Au crystal grains of the sputtered target is more preferably 150 µm or less, and even more preferably 100 µm or less.

[0022] The average crystal grain size of Au of the sputtered target is measured as follows. In the case of a lamellar Au sputter target, the following nine measurement points are set: three points are set at 10 mm intervals in a straight line on the surface to be sputtered, three points are selected respectively from three areas obtained by dividing by three the first section perpendicular to the surface to be sputtered in the direction thickness (in the following examples, three points at intervals of 1.5 mm on a straight line passing in the direction of the thickness of the sample having a thickness of 5 mm), and three points are selected respectively from three areas obtained by dividing by three the second section perpendicular to the surface to be sprayed and a first section in the thickness direction (in the following examples, three points are set at 1.5 mm intervals on a straight line passing in the thickness direction of a sample having a thickness of 5 mm). An enlarged image of each measurement point is then obtained using an optical microscope. The image is obtained at a magnification (eg x50 or x100) that allows easy measurement of the size of the crystal grains. Straight lines are drawn horizontally and vertically so as to pass through the center of the enlarged image, and the number of crystal grains cut by each line is counted. The crystal grain at the end of the line is counted as 0.5. The lengths of the respective horizontal and vertical lines are divided by their respective number of crystal grains to determine the average grain size for the horizontal line and for the vertical line. Then, the average of the determined average grain sizes for the horizontal and vertical lines is determined as the average grain size of one example.

[0023] Thus, the average crystal grain size (AD _av1 ) in the surface to be sprayed, the average crystal grain size (AD _av2 ) in the first section, and the average crystal grain size (AD _av3 ) in the second section are determined. The average sizes (AD _av1 , AD _av2 and AD _av3 ) of the crystal grains in the surface to be sprayed, in the first section and the second section are further averaged, and the resulting average value is determined as the average value of the size (AD _tav ) of the crystal grains (the average size of the crystal grains) of the entire lamellar Au sputtered target.

[0024] In a lamellar Au sputtered target, the ratio (AD _av1 /AD _tav ) of the average crystal grain size (AD _av1 ) in the surface to be sputtered to the average size (AD _tav ) of the crystal grains of the entire target, the ratio (AD _av2 /AD _tav ) of the average size (AD _av2 ) crystalline grains in the first section to the average size (AD _tav ) of crystalline grains of the entire target and the ratio (AD _av3 /AD _tav ) of the average size (AD _av3 ) of crystalline grains in the second section to the average size (AD _tav ) of crystalline grains of the entire target targets preferably fall within the range of 0.8 to 1.2. That is, the change in the average size of the Au crystal grains of the sputtered target is preferably ±20%. By reducing local variations in the average size of the Au crystal grains of the sputtered target, the direction of particle flight during sputtering is made uniform, which improves the film thickness distribution uniformity.

[0025] In the case of a cylindrical Au sputtering target, the following nine measurement points are set: three points are set at 10 mm intervals along the first straight line parallel to the cylindrical axis in the surface to be sputtered (cylindrical surface), three points are set at 10 mm intervals along the second straight line line obtained by rotating the first straight line by 90°, and three points are selected respectively from three areas obtained by dividing into three sections, perpendicular to the cylindrical axis in the thickness direction (in the following examples, three points are set at intervals of 1.5 mm on a straight line, passing in the direction of the thickness of the sample having a thickness of 5 mm). The average size (AD _av1 ) of crystal grains on the first straight line in the surface to be sprayed, the average size (AD _av2 ) of crystal grains on the second straight line and the average size (AD _av3 ) of crystal grains in the cross section are determined. The average sizes (AD _av1 , AD _av2 and AD _av3 ) in the surface to be sputtered and the cross section are further averaged, and the resulting average value is determined as the average size (AD _tav ) of the crystal grains of the entire cylindrical Au sputtered target.

[0026] In a cylindrical Au sputtered target, the ratio (AD _av1 /AD _tav ) of the first average size (AD _av1 ) of the crystal grains in the surface to be sputtered to the average size (AD _tav ) of the crystal grains of the entire target, the ratio (AD _av2 /AD _tav ) of the second the average size (AD _av2 ) of crystalline grains to the average size (AD _tav ) of crystalline grains of the entire target and the ratio (AD _av3 /AD _tav ) of the average size (AD _av3 ) of crystalline grains in cross section to the average size (AD _tav ) of crystalline grains of the entire target is preferably fall in the range from 0.8 to 1.2. That is, the change in the average size of the Au crystal grains of the sputtered target is preferably ±20%. By reducing the local variations in the average crystal grain size of the cylindrical Au sputter target in this way, the direction of particle flight during sputtering is made uniform, which improves the film thickness distribution uniformity. The cylindrical Au sputter target is rotated during sputtering, whereby the entire cylindrical surface is sputtered, so that reducing local variations in the average crystal grain size of the sputtered target (cylindrical surface) can improve film thickness distribution uniformity.

[0027] In the Au of the sputtered target according to this embodiment, the {110} Au plane is predominantly oriented toward the surface to be sputtered. Au has a face-centered cubic lattice structure, and the {110} plane is easier to sputter than other crystallographic planes constituting the face-centered cubic lattice structure. By preferentially orienting the surface to the {110} plane, the flight direction of the particles during sputtering is stabilized, whereby the evenness of the film thickness distribution can be further improved. Preferential orientation of the surface to be sprayed to the {110} plane refers to a state in which the orientation index N of the {110} plane is greater than 1 and is the largest among the orientation indices N of all crystallographic planes, where the orientation index N of each crystallographic plane is calculated according to the following Wilson equation (1) based on the ratio of the diffraction intensities of each crystallographic plane Au, which is obtained by X-ray diffraction for the surface of the Au of the sputtered target to be sputtered. The orientation index N of the {110} Au plane is preferably 1.3 or more.

[0028] [Equation 1]

In the above equation (1), I/I _(hkl) is the ratio of the intensities of the plane diffraction (hkl) in X-ray diffraction. JCPDS* I/I _(hkl) is the ratio of plane diffraction intensities (hkl) in the JCPDS (Joint Committee for Powder Diffraction Standards) card. Ʃ(I/I _(hkl) ) is the sum of the ratios of the diffraction intensities of all crystallographic planes during X-ray diffraction, and Ʃ(JСРDS*I/I _(hkl) ) is the sum of the ratios of the diffraction intensities of all crystallographic planes in the JСРDS card.

[0029] The Au sputtering target according to this embodiment can significantly improve the uniformity of the sputtered film thickness distribution of high-purity Au having an Au purity of 99.999% or more by combining the above-described Vickers hardness of 20 or more and less than 40, an average crystal grain size of 15 µm or greater than and 200 μm or less, and a surface to be sputtered to which the {110} Au plane is predominantly oriented. That is, the individual effects caused by the above Vickers hardness, the average crystal grain size, and the predominantly oriented Au surface act synergistically, whereby the flying properties of the Au particles that fly from the Au sputter target having Au purity of 99.999% or more are improved during sputtering. , the uniformity of the particles of Au and the stability of the direction of flight of the particles of Au. Thus, when a sputtered high-purity Au film is used, for example, as an electrode of an electronic device such as a crystal oscillator for which miniaturization is promoted, it is possible to provide a high-purity Au film characterized in that the film thickness variation and the mass variation resulting from the thickness variation films are reduced and that the uniformity of film thickness and weight distribution is improved.

[0030] The method for producing the above-described Au sputter target according to this embodiment is not limited. The method for producing an Au sputter target according to the present embodiment preferably includes: a step of preparing a gold ingot having a gold purity of 99.999% or more; the first stage of processing the gold bar to form the required lamellar or cylindrical workpiece; a second step of pressurizing the gold blank so as to reduce the thickness of its plate to form the material of the desired plate or cylindrical target; and a heat treatment step of applying heat treatment to the target material.

[0031] The method for producing the Au sputter target according to this embodiment will be described in detail. For example, a lamellar Au sputter target can be produced by a manufacturing method that combines casting, cutting, forging, and heat treatment of the original Au material. In addition, when obtaining a lamellar Au sputtering target, rolling can be used instead of forging the original Au material. Cylindrical Au sputtering target can be obtained by a manufacturing method that combines casting, cutting, pipe making, and heat treatment of Au material. Examples of pipe fabrication include Raflo extrusion, drawing and forging. By adjusting the operating mode or heat treatment temperature in each of the operating steps, the above-mentioned Vickers hardness, average crystal grain size, preferential crystallographic plane, and the like can be achieved.

[0032] The casting of the original Au material is preferably performed as follows. The original Au material is melted in a graphite crucible or a ceramic crucible in a vacuum or in an inert gas atmosphere; alternatively, the raw Au material is melted in a graphite crucible or a ceramic crucible by supplying an inert gas to the surface of the molten metal using an atmospheric melting furnace, or by coating the surface of the molten metal with a carbon hard sealing material. The obtained raw material is then poured into a graphite mold or cast iron mold. In the step of casting the original Au material, the purity of the Au ingot is adjusted to 99.999% or more (5N or more). The upper limit of the Au purity of the ingot is not limited to a particular value, and is set according to the degree of purity required for the formed Au sputter film. Generally, the upper limit is set to 99.9999% or less considering the production method of the Au ingot or the production cost of the Au sputtering target.

[0033] Then, the resulting Au ingot is converted into a gold blank having the desired plate shape or cylindrical shape (first processing step). When a lamellar Au sputter target is produced, defects on an outer peripheral surface of, for example, a lamellar Au ingot are removed by grinding, whereby a lamellar gold blank is obtained. When a cylindrical Au sputter target is obtained, defects on the outer peripheral surface of, for example, a cylindrical Au ingot are removed by grinding, and then a void is made to obtain a cylindrical gold blank.

[0034] The gold blank is then converted into the material of the desired plate or cylindrical target (second processing step). When an Au plate sputter target is produced, the Au plate blank is forged into the desired plate shape. The forging of the Au billet is preferably performed in a hot state at a temperature in the range of 200° C. or more to 800° C. or less and a processing degree (area reduction or thickness reduction) of 50% or more and 90% or less. Forging can be performed multiple times, and heat treatment can be applied during forging. When forging is performed a plurality of times, the total processing rate is adjusted to 50% or more and 90% or less.

[0035] By setting the forging processing rate to 50% or more, the cast structure is destroyed, and thus a uniform recrystallized structure is easily obtained. In addition, the controllability and uniformity of hardness or crystal grain size can be enhanced during subsequent heat treatment. The resulting Au forged material can be cold rolled as needed. The working degree in rolling is preferably 50% or more and 90% or less, although this depends on the degree of processing in the forging process. Instead of the forging method, it is possible to use the rolling method as processing of the Au workpiece. As with forging, the billet Au rolling is preferably performed in a hot state at a temperature in the range of 200° C. or more and 800° C. or less, and a treatment degree (area reduction or thickness reduction) of 50% or more and 90% or less.

[0036] When a cylindrical Au sputter target is produced, the columnar Au blank is formed into a tubular shape, for example by Raflo pressing, drawing or forging. When Raflo pressing is used, it is preferably performed cold. In addition, in Raflo pressing, the outer diameter and the diameter of the formed pipe are controlled by the shape (inner diameter) of the die and the shape (outer diameter, etc.) of the mandrel. In this case, the drawing ratio (external diameter of the billet/external diameter of the pipe) is preferably adjusted to 1.5 or more and 3.0 or less. When the draw ratio is 1.5 or more, the cast structure breaks down, and thus a uniform recrystallized structure is easily obtained. In addition, the controllability and uniformity of hardness can be enhanced by further heat treatment. However, when the draw ratio exceeds 3.0, the internal stress becomes too large and cracks, wrinkles, and other defects are more likely to occur.

[0037] When drawing is used, the Au material pipe obtained by pressing or forming a cavity is preferably converted into a pipe of the desired shape by cold drawing. In addition, during drawing, the outer diameter and thickness of the formed pipe are controlled by the shape of the die (inner diameter, etc.) and the shape of the insert (outer diameter, etc.). Meanwhile, the processing rate of each drawing method is preferably adjusted to 2% or more and 5% or less. The drawing is preferably performed a plurality of times, in which case the overall processing rate is preferably adjusted to 50% or more and 90% or less. When the total processing rate is 50% or more, the cast structure is destroyed, and thus a uniform recrystallized structure is easily obtained. In addition, the controllability and uniformity of hardness can be enhanced by further heat treatment. However, when the total processing rate exceeds 90%, the internal stress becomes too large and cracks, wrinkles, and other defects are more likely to occur.

[0038] When forging is used, the Au material pipe obtained by pressing or forming a cavity is preferably subjected to hot forging at a temperature in the range of 200°C or more and 800°C or less into a desired tubular shape. In addition, by adjusting the degree of processing during forging, the outer diameter and the thickness of the tube to be formed are controlled. When forging, the degree of processing is preferably adjusted to 30% or more and 80% or less. When the processing rate is 30% or more, the cast structure is destroyed, and thus a uniform recrystallized structure is easily obtained. In addition, the controllability and uniformity of hardness can be enhanced by further heat treatment. The forging processing rate is more preferably 50% or more. However, when the total processing rate exceeds 80%, the internal stress becomes too large and cracks, wrinkles and other defects are more likely to occur.

[0039] Then, the plate target material obtained by forging or rolling and the tubular target material obtained by tube production are heat treated at a temperature of 200°C or more and 500°C or less in an atmosphere of air or an inert gas, for example, to recrystallize the metallic structure of the target material. Through such heat treatment, an Au sputter target having a Vickers hardness of 20 or more and less than 40 can be obtained. In addition, an Au sputter target having an average crystal grain size of 15 µm or more and 200 µm or less can be obtained, and/or Au sputtered target, wherein the surface to be sputtered is predominantly oriented towards the {110} plane. The heat treatment can be performed multiple times. After heat treatment, the sputtered target can be given the desired shape, for example, by cutting.

[0040] When the heat treatment temperature is less than 200° C., internal stresses generated during manufacture cannot be sufficiently removed, which may increase the Vickers hardness to 40 or more, or may interfere with the preferential orientation of the surface to be sprayed to the {110 }. On the other hand, when the heat treatment temperature exceeds 500°C, the recrystallized structure grows excessively, which may cause the average crystal grain size to exceed 200 µm, or cause the surface to be sputtered to be oriented to a crystallographic plane other than {110}. Heat treatment temperature maintenance time, i.e. the heat treatment time is preferably, for example, 10 minutes or more and 120 minutes or less. An excessively short heat treatment time may prevent sufficient stress removal or sufficient recrystallization of the metal structure from being achieved. On the other hand, an excessively long heat treatment time can lead to an excessive decrease in Vickers hardness or an excessive increase in the average crystal grain size.

[0041] As described above, by adjusting the degree of processing when turning the Au ingot into a plate shape or a cylindrical shape and the heat treatment temperature for recrystallization, an Au sputter target having a Vickers hardness of 20 or more and less than 40 can be obtained, and small variations in Vickers hardness. In addition, an Au sputter target having an average crystal grain size of 15 µm or more and 200 µm or less and with slight variations in the average crystal grain size and/or an Au sputter target can be obtained, wherein the surface to be sputtered is predominantly oriented to the {110 }. By forming an Au film using such an Au sputter target, a high-purity Au film can be obtained achieving a high film thickness distribution uniformity required for an electrode such as a crystal oscillator. The Au sputtering target according to this embodiment can be used to form not only an electrode film (Au film) of a crystal oscillator, but also an Au film applied to various electronic components.

EXAMPLES

[0042] The following describes specific examples of the present invention and the results of their evaluation.

(Example 1)

[0043] First, a certain mass of Au was placed in a graphite crucible and melted. The resulting molten Au was poured into a graphite mold to obtain a lamellar Au ingot. The surface of the Au ingot was ground, whereby an Au blank (purity: 99.999%) having a width of 190 mm, a length of 270 mm, and a thickness of 50 mm was obtained. Then, the Au blank was forged at a temperature of 800°C to obtain an Au target material having a width of 70 mm, a length of 200 mm, and a thickness of 45 mm. The degree of processing during forging was up to 80% in all three directions. The target Au material after forging was subjected to heat treatment at a temperature of 500°C for 30 minutes. The Au target material after heat treatment was ground to obtain a round plate Au sputter target having a diameter of 152.4 mm and a thickness of 5 mm. To measure the characteristics of each part and measure the film thickness, two Au sputter targets were prepared. The same was applied for the following examples and comparative examples.

[0044] The Vickers hardness of the obtained Au sputter target was measured according to the above-described measurement method for plate sputter target (device name: mitsutoyo HM123). The Vickers hardness was measured at the above measurement points with a test force of 200 gf (compression load). The results were as follows: the average value (HV _av1 ) of the Vickers hardness in the surface to be sprayed was 25.6, the average value (HV _av2 ) of the Vickers hardness in the first section was 33.2, the average value (HV _av3 ) of the Vickers hardness in the second cross-section was 33.1 and the average (Vickers hardness (HV _tav ) of the entire target) of HV _av1 , HV _av2 and HV _av3 was 30.6. The ratios of HV _av1 , HV _av2 and HV _av3 to the Vickers hardness (HV _tav ) of the whole target were 0.84 (HV _av1 /HV _tav ), 1.08 (HV _av2 /HV _tav ) and 1.08 (HV _av3 /HV _tav ) respectively.

[0045] Then, the average crystal grain size Au of the sputtering target was measured according to the above-described measurement method for the plate sputtering target. As a result, the average size (AD _tav ) of the crystal grains of the entire target was 32.2 µm. In addition, the sputtering target surface Au to be sputtered was subjected to X-ray diffraction, and the preferred crystallographic plane was evaluated according to the above-described method. As a result, the predominant orientation of the {110} Au plane to the surface to be sputtered was established. In addition, the {110} plane orientation index N was determined according to the above method, and the result was 1.52. This Au sputter target was subjected to the film formation method described below, and the characteristics of the obtained Au film were determined.

(Examples 2-7, Comparative Examples 1 and 2)

[0046] The Au blank obtained in the same manner as in Example 1 was subjected to forging in the same manner as in Example 1 at the processing rate shown in Table 1 to obtain the Au target material. Then, the target material Au after forging was subjected to heat treatment under the conditions shown in Table 1. Thereafter, the target material Au after heat treatment was ground to obtain an Au sputter target having the same size as in Example 1. Vickers hardness, average crystal size grains, the predominantly oriented sputtering target plane, and the {110} plane orientation index N were measured and determined in the same manner as in Example 1. The measurement results are shown in Table 2. Au films. In the Au sputter target of Comparative Example 1, the crystal grain boundary could not be clearly identified, so the average crystal grain size could not be measured (corresponding area in Table 1 is empty (-)).

[0047] [Table 1]

Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 1 99.999 80 500 thirty Ex 2 99.999 80 500 60 Ex 3 99.999 80 500 90 Ex 4 99.999 80 400 thirty Ex 5 99.999 80 300 thirty Ex 6 99.999 80 400 60 Ex 7 99.999 80 300 60 Comp. pr.1 99.999 80 100 thirty Comp. project 2 99.999 80 600 thirty

[0048] [Table 2]

Vickers hardness⃰ Average size of crystal grains
[µm] Predominant crystallographic plane Plane Orientation Index N
{110} HV _tav HV _av1 HV _av2 HV _av3 AD _tav Ex 1 30.6 25.6 33.2 33.1 32.2 {110} 1.52 (0.84) (1.08) (1.08) Ex 2 26.4 22.6 28.6 28.1 31.2 {110} 1.23 (0.85) (1.08) (1.06) Ex 3 25.5 20.4 27.6 28.5 33.2 {110} 1.16 (0.80) (1.08) (1.12) Ex 4 25.7 21.0 28.0 25.2 36.2 {110} 1.25 (0.85) (1.13) (1.02) Ex 5 27.9 22.5 30.2 30.9 35.6 {110} 1.38 (0.81) (1.08) (1.11) Ex 6 29.7 24.1 32.6 32.3 35.6 {110} 1.08 (0.81) (1.10) (1.09) Ex 7 29.5 23.9 31.2 33.5 35.6 {110} 1.03 (0.81) (1.06) (1.13) Comp. pr.1 65.5 60.5 67.0 68.9 - {110} 5.57 (0.92) (1.02) (1.05) Comp. project 2 28.6 20.6 33.4 31.9 602.9 {100} 0.27 (0.72) (1.17) (1.11)

* Each value in brackets represents a relationship to HV _tav .

The symbol "-" in the field of the average size of crystal grains indicates the impossibility of performing measurements due to the difficulty in identifying the boundary of crystal grains.

[0049] The Au sputter targets from Examples 1 to 7 and Comparative Examples 1 and 2 were installed in a single plate sputtering device (device name: ANELVA SPF530H). After the device was evacuated to 1×10 ^-3 Pa or less, spraying was performed under the following conditions: Ar gas pressure 0.4 Pa; supplied power at direct current 100 W; target-substrate distance 40 mm; and a sputtering time of 5 minutes, whereby Au films were formed on 6-inch (15.24 cm) Si substrates (wafers), respectively. The thickness distribution of each of the resulting Au films was determined as follows. The substrate on which the Au film was formed was mounted in an X-ray fluorescent thickness gauge, and the thickness of the Au film was measured under the following conditions: measurement time 60 sec; number of repeated measurements 10; the starting point of measurement, the area of the end of the substrate; and an interval of measuring points of 5 mm. Four measurement axes were set to measure the film thickness: two horizontal and vertical axes passing through the center of the substrate, and two horizontal and vertical axes passing through the center of the substrate rotated by 45° from the initial position. After the measurement, the average film thickness over 10 points was determined at each measurement point. Then, the standard deviation of the measurement values obtained at one measurement location on each of the four axes was determined, and the average value of the standard deviation of the measurement values for all measurement points was determined. The results are shown in Table 3 as standard deviation σ of film thickness. Then, the resistance value of the Au film was measured using the four-sensor method, and the standard deviation σ of the resistance value was determined as in the case of the film thickness. The results are shown in Table 3 as the standard deviation σ of the resistance value.

[0050] [Table 3]

Film Formation Evaluation Result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 1 8.5 5.2 Ex 2 7.9 5.8 Ex 3 8.8 4.9 Ex 4 8.1 5.9 Ex 5 7.5 5.5 Ex 6 7.6 5.8 Ex 7 7.8 6.1 Comp. pr.1 16.2 12.2 Comp. project 2 21.3 23.1

[0051] Table 2 and Table 3 show that in the Au sputter targets of Examples 1-7, the Vickers hardness is 20 or more and less than 40, and local variations in Vickers hardness are small. In addition, the average crystal grain size is 15 µm or more and 200 µm or less, the {110} plane is predominantly oriented toward the surface to be sputtered, and the orientation index N of the {110} plane is greater than 1. Au film formed by sputtering using Au A sputter target having the above Vickers hardness, average crystal grain size, and predominantly oriented plane of the surface to be sputtered is excellent in film thickness distribution uniformity and resistance value uniformity.

(Examples 8-12)

[0052] The Au blank obtained in the same way as in Example 1 was subjected to forging in the same way as in Example 1 at the processing rate shown in Table 4 to obtain the Au target material. Then, the target material Au after forging was subjected to heat treatment under the conditions shown in Table 4. Thereafter, the target material Au after heat treatment was ground to obtain an Au sputter target having the same size as in Example 1.

[0053] [Table 4]

Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 8 99.999 80 500 twenty Ex 9 99.999 80 500 thirty Ex 10 99.999 80 500 120 Ex 11 99.999 80 400 twenty Ex 12 99.999 80 300 twenty

[0054] The Vickers hardness of the obtained Au sputtering target was measured in the same manner as in Example 1. In addition, the average crystal grain size of the obtained Au sputtering target was measured according to the above-described measurement method for plate sputtering target. With regard to the measurement results, the average sizes (AD _av1 , AD _av2 , AD _av3 ) of the crystal grains in the surface to be sputtered, the first section and the second section, the average value (the average size (AD _tav ) of the crystal grains of the entire target) of the above average crystal grain sizes and the ratios of the respective AD _av1 , AD _av2 , AD _av3 to AD _tav are shown in Table 5. In addition, the sputtered target surface Au to be sputtered was subjected to X-ray diffraction, and the orientation-dominant crystallographic plane was evaluated according to the above method. In addition, the orientation index N of the {110} plane was determined according to the method described above. The results are shown in Table 5. Such an Au sputter target was subjected to a film forming process in the same manner as in Example 1, and the standard deviation σ of the thickness of the obtained Au film and the standard deviation σ of the resistance value of the Au film were determined. The results are shown in Table 6.

[0055] [Table 5]

Vickers hardness Average crystal grain size*
[µm] Predominant crystallographic plane Plane Orientation Index N
{110} HV _tav AD _{tav ADav1 ADav2 ADav3} Ex 8 28.0 31.2 30.2 32.1 31.2 {110} 1.47 (0.97) (1.03) (1.00) Ex 9 26.3 33.5 33.2 34.1 33.1 {110} 1.32 (0.99) (1.02) (0.99) Ex 10 26.2 33.5 33.5 34.6 32.4 {110} 1.21 (1.00) (1.03) (0.97) Ex 11 28.1 31.6 30.8 32.6 31.5 {110} 1.28 (0.97) (1.03) (1.00) Ex 12 28.0 32.2 32.8 31.5 32.4 {110} 1.22 (1.02) (0.98) (1.01) Comp. pr.1 65.5 - - - - {110} 5.57 Comp. project 2 28.6 605.1 605.1 601.2 608.9 {100} 0.27 (1.00) (0.99) (1.01)

* Each value in brackets represents a relation to AD _tav .

The symbol "-" in the field of the average size of crystal grains indicates the impossibility of performing measurements due to the difficulty in identifying the boundary of crystal grains.

[0056] [Table 6]

Film Formation Evaluation Result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 8 8.1 5.9 Ex 9 7.3 5.2 Ex 10 8.5 4.2 Ex 11 8.6 6.0 Ex 12 8.0 5.1 Comp. pr.1 17.1 12.5 Comp. project 2 20.3 22.9

(Examples 13-21, Comparative Examples 3 and 4)

[0057] First, a certain mass of Au was placed in a graphite crucible and melted. The resulting molten Au was poured into a graphite mold to obtain an Au ingot. The surface of the Au ingot was ground, whereby an Au blank (purity: 99.999%) having a width of 200 mm, a length of 300 mm, and a thickness of 45 mm was obtained. Then, the Au blank was rolled at a temperature of 800°C to obtain an Au target material having a width of 70 mm, a length of 200 mm, and a thickness of 45 mm. The degree of processing during rolling was up to 80% in the form of reduction in thickness. The target material Au after rolling was subjected to heat treatment under the conditions shown in Table 7. The target material Au after heat treatment was ground to obtain a round plate Au sputter target having a diameter of 152.4 mm and a thickness of 5 mm.

[0058] [Table 7]

Au purity
[%] Degree of processing
when rolling
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 13 99.999 80 500 twenty Ex 14 99.999 80 500 thirty Ex 15 99.999 80 500 60 Ex 16 99.999 80 500 90 Ex 17 99.999 80 500 120 Ex 18 99.999 80 400 twenty Ex 19 99.999 80 400 thirty Ex 20 99.999 80 300 twenty Ex 21 99.999 80 300 thirty Comp. project 3 99.999 80 100 thirty Comp. project 4 99.999 80 600 thirty

[0059] The obtained Au sputtered target was measured by determining the average value (HV _tav ) of the Vickers hardness of the entire target and the average size (AD _tav ) of the crystal grains of the entire target in the same way as in example 1. In addition, the crystallographic plane, predominantly oriented to the subject surface sputtering of the Au sputtering target was evaluated in the same way as in Example 1, and the orientation index N of the {110} plane was measured and determined in the same way as in Example 1. The results are shown in Table 8. in the same manner as in Example 1, and the standard deviation σ of the thickness of the obtained Au film and the standard deviation σ of the resistance value of the Au film were determined. The results are shown in Table 9.

[0060] [Table 8]

Vickers hardness Average crystal grain size*
[µm] Predominant crystallographic plane Plane orientation index N {110} HV _tav AD _tav Ex 13 30.1 35.2 {110} 1.21 Ex 14 29.6 36.1 {110} 1.32 Ex 15 31.2 35.8 {110} 1.43 Ex 16 32.2 33.2 {110} 1.32 Ex 17 29.5 34.8 {110} 1.12 Ex 18 29.8 36.7 {110} 1.23 Ex 19 30.3 34.2 {110} 1.17 Ex 20 30.8 34.6 {110} 1.28 Ex 21 32.1 33.1 {110} 1.24 Comp. project 3 60.2 - - - Comp. project 4 25.1 608.1 - -

[0061] [Table 9]

Film Formation Evaluation Result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 13 8.3 6.1 Ex 14 8.0 5.4 Ex 15 7.6 4.6 Ex 16 7.1 6.1 Ex 17 8.3 6.9 Ex 18 8.9 6.2 Ex 19 8.1 5.6 Ex 20 7.2 6.3 Ex 21 7.8 5.4 Comp. project 3 13.6 11.3 Comp. project 4 23.1 19.8

(Example 22)

[0062] First, a certain mass of Au was placed in a graphite crucible and melted. The resulting molten Au was poured into a graphite mold to obtain a cylindrical Au ingot. The surface of the Au ingot was ground by removing and making a hole with a diameter of 50 mm, whereby an Au billet (purity: 99.999%) having an outer diameter of 100 mm, an inner diameter of 50 mm, and a length of 200 mm was obtained. Then, the cylindrical Au billet was forged at a temperature of 800°C with a mandrel inserted into its hollow portion to obtain a tubular-shaped Au target material having an outer diameter of 80 mm, an inner diameter of 50 mm, and a length of 400 mm. The forging treatment rate was 35% in terms of thickness reduction. The Au material of the tubular-shaped target after forging was subjected to heat treatment at a temperature of 500° C. for 30 minutes. The target Au material after heat treatment was ground to obtain a cylindrical Au sputter target having an outer diameter of 70 mm, an inner diameter of 65 mm, and a length of 350 mm.

[0063] The Vickers hardness of the resulting Au sputter target was measured according to the above-described measurement method for a cylindrical sputter target. The Vickers hardness was measured at the measurement points with a test force of 200 gf (compression load). The results were as follows: the average value (HV _av1 ) of the Vickers hardness in the first straight line in the surface to be sprayed was 24.0, the average value (HV _av2 ) of the Vickers hardness in the second straight line in the surface to be sprayed was 31.2, the average value (HV _av3 ) of the cross-sectional Vickers hardness was 33.6 and the average (Vickers hardness (HV _tav ) of the whole target) of HV _av1 , HV _av2 and HV _av3 was 29.6. The ratios of HV _av1 , HV _av2 and HV _av3 to the Vickers hardness (HV _tav ) of the whole target were 0.81 (HV _av1 /HV _tav ), 1.05 (HV _av2 /HV _tav ) and 1.14 (HV _av3 /HV _tav ) respectively.

[0064] Then, the average crystal grain size Au of the sputtering target was measured according to the above-described measuring method for a cylindrical sputtering target. As a result, the average size (AD _tav ) of the crystal grains of the entire target was 36.3 µm. In addition, the sputtering target surface Au to be sputtered was subjected to X-ray diffraction, and the preferred crystallographic plane was evaluated according to the above-described method. As a result, the predominant orientation of the {110} Au plane to the surface to be sputtered was established. In addition, the {110} plane orientation index N was determined according to the above method, and the result was 1.28. This Au sputter target was subjected to the film formation method described below, and the characteristics of the obtained Au film were determined.

(Examples 23-28, Comparative Examples 5 and 6)

[0065] The Au blank obtained in the same way as in Example 22 was subjected to forging in the same way as in Example 22 at the processing rate shown in Table 10 to obtain the Au target material. Then, the target material Au after forging was subjected to heat treatment under the conditions shown in Table 10. Thereafter, the target material Au after heat treatment was ground to obtain an Au sputter target having the same shape as in Example 22. Vickers hardness and average size ( AD _tav ) of the crystal grains Au of the sputtered target was measured in the same way as in Example 22. In addition, the crystallographic plane predominantly oriented toward the surface of the sputtered target to be sputtered Au was evaluated in the same way as in Example 22, and the orientation index N of the {110} plane was determined in the same way as in Example 22. The results are shown in Table 11. This cylindrical Au sputter target was subjected to the film forming method described below, and the characteristics of the resulting Au film were determined.

[0066] [Table 10]

Au purity
[%] Forging degree
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 22 99.999 35 500 thirty Ex 23 99.999 35 500 60 Ex 24 99.999 35 500 90 Ex 25 99.999 35 400 thirty Ex 26 99.999 35 300 thirty Ex 27 99.999 35 400 60 Ex 28 99.999 35 300 60 Comp. project 5 99.999 35 100 thirty Comp. Project 6 99.999 35 600 thirty

[0067] [Table 11]

Vickers hardness⃰ Average size of crystal grains
[µm] Predominant crystallographic plane Plane Orientation Index N
{110} HV _tav HV _av1 HV _av2 HV _av3 AD _tav Ex 22 29.6 24.0 31.2 33.6 36.3 {110} 1.28 (0.81) (1.05) (1.14) Ex 23 29.8 23.8 32.6 33.1 35.1 {110} 1.18 (0.80) (1.09) (1.11) Ex 24 29.3 24.1 31.5 32.3 33.2 {110} 1.20 (0.82) (1.08) (1.10) Ex 25 29.5 23.6 33.2 31.6 32.6 {110} 1.35 (0.80) (1.13) (1.07) Ex 26 29.5 21.2 32.6 31.6 35.6 {110} 1.23 (0.82) (1.11) (1.07) Ex 27 29.6 24.0 33.1 31.6 34.2 {110} 1.13 (0.81) (1.12) (1.07) Ex 28 30.0 23.9 32.5 33.6 33.8 {110} 1.05 (0.80) (1.08) (1.12) Comp. project 5 65.2 61.8 68.2 65.6 - {110} 4.23 (0.95) (1.05) (1.01) Comp. Project 6 27.5 21.9 29.8 30.8 605.3 {100} 0.35 (0.80) (1.08) (1.12)

* Each value in brackets represents a relationship to HV _tav .

The symbol "-" in the field of the average size of crystal grains indicates the impossibility of performing measurements due to the difficulty in identifying the boundary of crystal grains.

[0068] The Au sputter targets from Examples 22-28 and Comparative Examples 5 and 6 were installed in a single cylinder sputtering apparatus. After the device was evacuated to 1×10 ^-3 Pa or less, spraying was performed under the following conditions: Ar gas pressure 0.4 Pa; supplied power at direct current 100 W; target-substrate distance 40 mm; and a sputtering time of 5 minutes, whereby Au films were formed on 6-inch Si (15.24 cm) substrates (wafers), respectively. The film thickness distribution of each of the obtained Au films was measured according to the above method by determining the standard deviation σ of the thickness of the obtained Au film. In addition, the standard deviation σ of the resistance value was determined according to the above method. The results are shown in Table 12.

[0069] [Table 12]

Film Formation Evaluation Result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 22 8.1 5.2 Ex 23 8.2 5.9 Ex 24 7.6 4.9 Ex 25 8.8 5.8 Ex 26 8.2 5.7 Ex 27 8.1 6.1 Ex 28 8.5 5.9 Comp. project 5 15.6 11.9 Comp. Project 6 23.2 21.9

[0070] Table 11 and Table 12 show that in the Au sputter targets of Examples 22-24, the Vickers hardness is 20 or more and less than 40, and local variations in Vickers hardness are small. In addition, the average crystal grain size is 15 µm or more and 200 µm or less, the {110} plane is predominantly oriented toward the surface to be sputtered, and the orientation index N of the {110} plane is greater than 1. The Au film formed by sputtering using the Au sputter A target having the above Vickers hardness, average crystal grain size, and having a preferential orientation of the plane of the surface to be sputtered is excellent in uniformity of film thickness distribution and uniformity of resistance value.

(Examples 29-33)

[0071] The Au blank obtained in the same manner as in Example 22 was subjected to forging in the same manner as in Example 22 at the degree of processing shown in Table 13 to obtain an Au cylindrical target material. Then, the target material Au after forging was subjected to heat treatment under the conditions shown in Table 13. Thereafter, the target material Au after heat treatment was ground to obtain an Au sputter target having the same shape as in Example 22.

[0072] [Table 13]

Au purity
[%] Forging degree
[%] Heat treatment conditions Temperature
[°C] Time
[min] Etc. 29 99.999 35 500 twenty Ex 30 99.999 35 500 thirty Project 31 99.999 35 500 120 Project 32 99.999 35 400 twenty Project 33 99.999 35 300 twenty

[0073] The Vickers hardness of the obtained Au sputtering target was measured in the same manner as in Example 22. In addition, the average crystal grain size of the obtained Au sputtering target was measured according to the above-described measurement method for a cylindrical sputtering target. With regard to the measurement results, the average sizes (AD _av1 , AD _av2 , AD _av3 ) of the crystal grains in the first surface to be sputtered, the second surface to be sprayed and the cross section, the average value (average size (AD _tav ) of the crystal grains of the entire target) of the above average crystal grain sizes grains and the ratios of the respective AD _av1 , AD _av2 , AD _av3 to AD _tav are shown in Table 14. In addition, the sputtered target surface Au to be sputtered was subjected to X-ray diffraction, and the preferred orientation crystallographic plane was evaluated according to the above method. In addition, the index N of the {110} plane orientation was determined. The results are shown in Table 14. Such an Au sputter target was subjected to a film formation process in the same manner as in Example 22, and the standard deviation σ of the thickness of the obtained Au film and the standard deviation σ of the resistance value of the Au film were determined. The results are shown in Table 15.

[0074] [Table 14]

Vickers hardness Average crystal grain size*
[µm] Predominant crystallographic plane Plane Orientation Index
{110} HV _tav AD _{tav ADav1 ADav2 ADav3} Ex 29 29.6 34.0 36.3 32.6 33.1 {110} 1.25 (1.07) (0.96) (0.97) Ex 30 31.6 33.6 32.9 33.8 34.1 {110} 1.27 (0.98) (1.01) (1.01) Project 31 30.1 34.1 31.9 33.8 36.5 {110} 1.12 (0.94) (0.99) (1.07) Project 32 29.8 32.9 32.8 33.1 32.9 {110} 1.31 (1.00) (1.01) (1.00) Project 33 30.9 32.1 32.1 30.6 33.6 {110} 1.18 (1.00) (0.95) (1.05) Comp. project 5 65.2 - - - - {110} 4.23 Comp. Project 6 29.1 603.9 601.9 610.0 599.9 {100} 0.35 (1.00) (1.01) (0.99)

* Each value in brackets represents a relation to AD _tav .

The symbol "-" in the field of the average size of crystal grains indicates the impossibility of performing measurements due to the difficulty in identifying the boundary of crystal grains.

[0075] [Table 15]

Film formation evaluation result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 29 8.3 5.6 Ex 30 7.9 5.1 Project 31 7.6 5.3 Project 32 7.9 4.7 Etc. 33 8.9 5.2 Comp. project 5 14.2 11.9 Comp. Project 6 21.3 20.9

INDUSTRIAL APPLICABILITY

[0076] The Au sputter target according to the present invention is applicable to forming a high purity Au film used in various applications. By performing sputtering using the Au sputter target according to the present invention, a high-purity Au film excellent in film thickness distribution uniformity and resistance value can be obtained. Thus, the characteristics of the Au film used in various applications can be improved.

Claims (14)

1. A gold sputtering target made of gold with a purity of 99.999% or more and having an average Vickers hardness value of 20 or more and less than 40, an average crystal grain size of 15 µm or more and 200 µm or less, and an index N of crystallographic plane orientation {110} of gold greater than 1, this N index being the largest among the orientation N indices of all gold crystallographic planes based on the ratio of the diffraction intensities of each of the gold crystallographic planes obtained by X-ray diffraction for the surface to be sputtered. 2. The gold sputter target of claim 1, wherein the Vickers hardness variation throughout the sputter target is within ±20%. 3. A gold sputter target according to claim 1 or 2, wherein the average crystal grain size variation throughout the sputter target is within ±20%. 4. Gold spray target according to any one of paragraphs. 1-3, in which the sputtered target has the shape of a plate. 5. Gold spray target according to any one of paragraphs. 1-3, in which the sputtered target has a cylindrical shape. 6. A method for producing a gold sputter target according to claim 1, comprising preparing a gold ingot having a gold purity of 99.999% or more, and preparation of a gold blank from a gold ingot; processing the gold blank to obtain a plate gold sputter target by hot forging or hot rolling of the gold blank at a temperature of 200°C or more and 800°C or less, or cold rolling of the gold blank at a processing rate of 50% or more and 90% or less, and thermal processing the target material at a temperature of 200° C. or more and 500° C. or less while maintaining the temperature for 10 minutes or more and 120 minutes or less. 7. A method for producing a gold sputter target according to claim 1, comprising preparing a gold ingot having a gold purity of 99.999% or more, and preparation of a gold blank from a gold ingot; processing the gold blank to obtain a plate gold sputtering target by cold pressing the gold blank at a drawing ratio of 1.5 or more and 3.0 or less, repeatedly cold drawing the gold blank at a processing rate of 2% or more and 5% or less, or hot forging the gold workpiece at a temperature of 200°C or more and 800°C or less and at a degree of processing of 30% or more and 80% or less, and heat treatment of the target at a temperature of 200°C or more and 500°C or less while maintaining the temperature for 10 minutes or more and 120 minutes or less. 8. The method according to claim 6 or 7, wherein a target is obtained with an orientation index N of the gold {110} crystallographic planes greater than 1, which is the largest among the N orientation indices of all the gold crystallographic planes, based on the ratio of the diffraction intensities of each of the gold crystallographic planes obtained by X-ray diffraction for the surface to be sprayed. 9. The method according to any one of paragraphs. 6-8, in which a target is obtained with a variation in Vickers hardness over the entire sputtered target within ± 20%. 10. The method according to any one of paragraphs. 6-9, in which a target is obtained with a variation in the average size of crystalline grains over the entire sputtered target within ± 20%.