RU2784174C2 - Method for production of gold film, using gold sprayed target - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for the production of gold film, using a gold sprayed target containing gold and unavoidable impurities. The gold sprayed target has an average value of Vickers hardness from 40 or more to 60 or less, an average value of a crystal grain size from 15 mcm or more to 200 mcm or less. Grains of a surface to be sprayed of the mentioned target mostly have a crystallographic orientation {110}. Gold film is formed on film-forming base material by spraying of the gold sprayed target.

EFFECT: gold film is provided with improved uniformity of thickness distribution and good reproducibility.

4 cl, 15 tbl, 33 ex

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method for producing a gold sputter target and a method for producing a gold film.

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 degree of target material at the time of 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. 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 tuning 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 more likely to vary. Also in this regard, it is required to reduce the variation in the thickness of the deposited Au film.

LIST OF CITATIONS

PATENT DOCUMENT

[0008] Patent Document 1: JP-T-2009-512779

Patent Document 2: JP 2013-204052A

Patent Document 3: WO 2015/111563

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide a method for producing a gold sputter target capable of improving the uniformity of gold film thickness distribution, and a method for producing a gold film capable of improving the uniformity of film thickness.

[0010] The method for producing a gold sputter target of the present invention includes the step of preparing a gold sputter target which is made of gold and unavoidable impurities, and in which the average Vickers hardness value is 40 or more and 60 or less, 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.

[0011] The method for producing a gold film according to the present invention includes the steps of: preparing a gold sputter target, which is made of gold and inevitable impurities, and in which the average Vickers hardness value is 40 or more and 60 or less, 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; and forming a film of gold on the film-forming base material by sputtering the gold sputter target.

EFFECT

[0012] According to the method for producing a gold sputter target of the present invention, a gold sputter target can be obtained with good reproducibility, allowing a gold film to be obtained with excellent film thickness distribution uniformity. This can improve the uniformity of gold film thickness distribution with good reproducibility. In addition, according to the gold film production method of the present invention, it is possible to provide a gold film with excellent film thickness distribution uniformity with good reproducibility.

DETAILED DESCRIPTION

[0013] Next, an embodiment of the present invention will be described. The sputtering target obtained by the method of this embodiment is made of gold (Au) and unavoidable impurities. Inevitable impurities (elements other than Au) contained in the Au of the sputtered target are not limited to specific elements. The purity of Au in the sputtered target is determined according to the application of the target or the application of the film formed using the target, and is, for example, 99.999% or more. The use of a sputtered target having an Au purity of 99.999% makes it possible to obtain a film from high-purity Au. In addition, the upper limit of the purity of the Au in the sputtering target is also not limited to a specific value, and is generally 99.999%, considering, for example, the production method and production costs of the Au sputtering target and the hardness of the Au sputtering target, and it is practically preferable to be 99.990% or more and 99.998% or less.

[0014] 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.

[0015] The Au sputter target according to this embodiment preferably has a Vickers hardness of 40 or more and 60 or less. When an Au sputter target having the above Vickers hardness is used to perform deposition, a high-purity Au film excellent in thickness distribution uniformity can be formed. That is, the fact that the Vickers hardness Au of the sputtered target is more than 60 TV means that the stress generated during production remains in the Au of the sputtered target. 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 55 TB or less. In addition, the application of heat during spraying changes the hardness or size of the crystal grains, which also degrades the uniformity of the flight properties of the particles. On the other hand, when the Vickers hardness Au of the sputtered target is less than 40 TV, the crystal orientation may disappear due to the growth of crystal grains, which deteriorates the film thickness distribution uniformity. The Vickers hardness Au of the sputtered target is preferably 45 TB or more.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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 30 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 sputtering target is more preferably 150 µm or less.

[0021] The average size of the Au crystal grains 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.

[0022] 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 (average crystal grain size) of the entire lamellar Au sputtered target.

[0023] In a lamellar Au sputtered target, the ratio (AD _av1 /AD _tav ) of the average size (AD _av1 ) of 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 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.

[0024] 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 values (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.

[0025] 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.

[0026] 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 crystal 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. The preferred orientation of the surface to be sprayed to the {110} plane refers to a state where 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 crystal 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 {110} Au plane orientation index is preferably 1.3 or more.

[0027] [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. (I/I _(hkl) ) is the sum of the ratios of the diffraction intensities of all crystallographic planes during X-ray diffraction, and (JСРDS*I/I _(hkl) ) is the sum of the ratios of the diffraction intensities of all crystallographic planes in the JСРDS card.

[0028] The Au sputtering target according to this embodiment can greatly improve the thickness distribution uniformity of the sputtered Au film by combining the above-described Vickers hardness of 40 or more and 60 or less, the average crystal grain size of 15 µm or more and 200 µm or less, and to be sputtered surface, 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, thereby improving the flying properties of the Au particles during spraying, the uniformity of the flying properties, and the stability of the flight direction of the Au particles. Thus, when the sputtered 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 an Au film characterized in that the film thickness variation and the mass variation resulting from the film thickness variation are reduced. , and that the uniformity of film thickness and weight distribution is improved.

[0029] The method for producing the above-described Au sputter target according to this embodiment comprises the step of obtaining a gold sputter target, which is made of gold and inevitable impurities, and in which the average Vickers hardness value is 40 or more and 60 or less, 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 to be sputtered. The method for producing an Au sputter target preferably includes the step of preparing a gold ingot having a gold purity of 99.99% or more; the first stage of processing a gold bar with the formation of 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.

[0030] 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, preferred crystallographic plane, and the like can be achieved.

[0031] 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. Then, defects on the outer peripheral surface of the cast Au ingot are removed by grinding. The purity of the Au ingot is preferably 99.99% or more (4N 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. Preferably, the upper limit is set to 99.999% considering the production method of the Au sputtering target or its hardness.

[0032] Then, the obtained 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.

[0033] The gold blank is then converted into the material of the desired plate or cylindrical target (second processing step). When a lamellar Au sputter target is produced, the lamellar Au blank is forged into the desired lamellar 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.

[0034] 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, the rolling method can be used as processing of the Au ingot. As with forging, the Au ingot is preferably hot rolled 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.

[0035] 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 tube are controlled by the shape (inner diameter) of the die and the shape (outer diameter, etc.) of the core. 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.

[0036] When drawing is used, the Au material pipe obtained by pressing or forming a cavity is preferably converted into a pipe of a 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.

[0037] When forging is used, the Au material pipe obtained by pressing or forming a cavity is preferably hot forged 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. 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.

[0038] 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 40 or more and 60 or less 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 and/or an Au sputter target in which the surface to be sputtered is predominantly oriented to the {110} plane can be obtained. The heat treatment can be performed multiple times. After heat treatment, the sputtered target can be given the desired shape, for example, by cutting.

[0039] 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 more than 60. In addition, a heat treatment temperature of less than 200°C prevents sufficient recrystallization of the metal structure of the target material, which may interfere with the preferred orientation of the surface to be sputtered to the {110} plane. On the other hand, when the heat treatment temperature exceeds 500° C., the Vickers hardness may become less than 40. In addition, the recrystallized structure grows excessively, which may cause the average crystal grain size to exceed 200 μm or cause the surface to be sprayed to preferentially orient to a different crystallographic plane. than the {110} plane. 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.

[0040] 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 40 or more and 60 or less can be obtained, and with slight 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 in which the surface to be sputtered is predominantly oriented to the plane { 110}. By forming an Au film using such an Au sputter target, an Au film can be obtained that achieves 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.

[0041] The following describes a method for producing a gold (Au) film according to this embodiment. The method for producing a gold (Au) film according to this embodiment includes the step of preparing a gold (Au) sputter target, which is made of gold and inevitable impurities, and in which the average Vickers hardness value is 40 or more and 60 or less, the average crystal size the grain size is 15 µm or more and 200 µm or less, and the {110} plane of gold is predominantly oriented toward the surface of the gold sputter target to be sputtered, and the step of forming a gold (Au) film on the film-forming base material by sputtering the gold sputter target. The preparation step of the gold (Au) sputter target includes the production method described above and its specific conditions as described above.

[0042] The Au film forming step forms an Au film on the film-forming base material by sputtering Au on the sputter target according to this embodiment. As described above in the process for producing an Au sputter target, the Au sputter target may be a plate target or a cylindrical target. In the present invention, various sputtering methods such as DC sputtering method (diode, triode and tetrode sputtering), RF sputtering method, magnetron sputtering method, ion beam sputtering method or ECR (electron cyclotron resonance) sputtering method can be applied.

[0043] In the Au film forming step (i.e., sputtering step), the Au sputter target according to this embodiment and the film-forming base material are in the vacuum chamber of the sputtering apparatus. The film-forming base material may include a substrate onto which an Au film of the Au sputter target according to this embodiment is deposited, such as a quartz substrate (quartz oscillator), a glass substrate, or a metal substrate, and a film such as a resin film, a metal film, or a resin. -metal composite film. Then, the vacuum chamber is evacuated to a predetermined vacuum level, and an atomizing gas such as Ar gas or nitrogen is introduced into the vacuum chamber. In this state, processing is carried out according to the applied spraying method. For example, in the DC sputtering method, the RF sputtering method, and the magnetron sputtering method, a DC voltage or RF voltage is supplied between the Au sputter target and the film-forming base material to generate a plasma in the vacuum chamber. In the Au ion beam sputtering method, the sputtered target is irradiated with an ion beam. Then, the sputtered particles (Au particles) which are emitted from the Au sputtering target by ionized sputtering gas molecules or by ion beam irradiation are deposited on the film-forming base material to form an Au film.

[0044] The sputtering conditions in the Au film forming step, such as the vacuum level, the pressure of the spraying gas, the power supplied between the sputtered target and the base material, and the distance between the target and the base material are not specifically limited, and are appropriately set according to, for example, the applied method. sputtering, the sputtering device used, the shape of the sputtered target Au, and the thickness and area of the formed Au film. In addition, the sputtering apparatus used in the formation of the Au film is also not limited to a specific type, and may be of various types, such as a single plate type, a batch type, a multi-chamber type, a locked load type, and an in-line type. The Au sputtering target may be a plate target or a cylindrical target as described above, and thus the sputtering device is selected according to the shape of the Au sputtering target.

[0045] The sputtering method and conditions used in the Au film formation step are not limited to those described in the following examples. For example, an Au film can be formed under the following conditions. The Au sputter target and the film-forming base material are placed in a DC sputtering device. The spray device is evacuated to a final vacuum of 8×10 ^-4 Pa or less. After the specified vacuum level is reached, Ar gas is introduced into the sputtering device and the film-forming base material is etched for, for example, 5 minutes at a vacuum level adjusted to, for example, about 0.4 Pa or more and about 0.53 Pa or less. After reaching a vacuum level of, for example, about 0.4 Pa or more and about 0.53 Pa or less, pre-spraying is performed with a DC power input of 500 W for 5 minutes. Then, after reaching a vacuum level of, for example, about 0.4 Pa or more and about 0.53 Pa or less, sputtering is performed with a DC input power of 500 W for 5 minutes to form an Au film. The formed film is cooled in the spray device for one hour.

[0046] According to the above-described method for producing the Au film of this embodiment, an Au film excellent in film thickness distribution uniformity based on the Vickers hardness and the average crystal grain size of Au of the sputtering target used to form the Au film and the plane ({110 plane) can be obtained. }), preferably oriented towards the surface to be sprayed. Thus, an Au film having high film thickness distribution uniformity and having high resistance uniformity achieved on the basis of high film thickness distribution uniformity can be provided for various devices such as crystal oscillators, semiconductor devices, LED devices, LCD devices, OLED devices. , magnetic devices, battery devices and optical devices, and for various materials such as electronic materials and functional materials. As a result, an increase in production yield, a reduction in size, an increase in productivity, and so on can be achieved. various devices and various functional materials.

[0047] As described above, it is important to reduce variations in the thickness of the Au film during the forming step, and in order to achieve this, optimizing the conditions for forming the Au film is critical. According to the gold film formation method of this embodiment, the film thickness variation can be reduced by widening the selection range of the film formation conditions and simplifying the conditions for film formation, which allows efficient formation of the Au film. In addition, a slight variation in the thickness of the Au film makes it possible to reduce the mass variation of the Au film, for example, in a crystal oscillator, so that the product yield can be improved.

EXAMPLES

[0048] The following describes specific examples of the present invention and the results of their evaluation.

(Example 1)

[0049] 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 billet (purity: 99.99%, analyzed by solid state emission spectrometry and ICP) 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.

[0050] The Vickers hardness of the obtained Au sputter target was measured according to the above-described plate sputter target measurement method (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 50.5, the average value (HV _av2 ) of the Vickers hardness in the first section was 52.1, the average value (HV _av3 ) of the Vickers hardness in the second cross-section was 51.6 and the average (Vickers hardness (HV _tav ) of the entire target) of HV _av1 , HV _av2 and HV _av3 was 51.4. The ratios _{of HV av1} , HV _av2 and HV _av3 to the Vickers hardness (HV _tav ) of the whole target were 0.98 (HV _av1 /HV _tav ), 1.01 (HV _av2 /HV _tav ) and 1.00 (HV _av3 /HV _tav ) respectively.

[0051] Then, the average crystal grain size Au of the sputtering target was measured according to the above-described plate sputtering target measurement method (device name: OLYMPUS DSX500). As a result, the average size (AD _tav ) of the crystal grains of the entire target was 34.2 µm. In addition, the sputtered target Au surface to be sputtered was subjected to X-ray diffraction, and the predominantly oriented crystallographic plane was evaluated according to the above-described method. As a result, the preferred 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 1.32. 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)

[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 degree of processing 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 plane of the sputtered target, and the orientation index N of the {110} plane orientation were measured and determined in the same manner as in Example 1. The measurement results are shown in Table 2. This Au sputtered target was subjected to the film formation method described below, and the characteristics of the resulting film were determined. Au. 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 blank (-)).

[0053]

[Table 1] Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 1 99.99 80 500 thirty Ex 2 99.99 80 500 60 Ex 3 99.99 80 500 90 Ex 4 99.99 80 400 thirty Ex 5 99.99 80 300 thirty Ex 6 99.99 80 400 60 Ex 7 99.99 80 300 60 Comp. pr.1 99.999 80 100 thirty Comp. project 2 99.999 80 600 thirty

[0054]

[Table 2] Vickers hardness 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 51.4 50.5 52.1 51.6 34.2 {110} 1.32 (0.98) (1.01) (1.00) Ex 2 49.3 49.1 48.6 50.1 35.0 {110} 1.44 (1.00) (0.99) (1.02) Ex 3 48.3 48.5 49.2 48.3 37.8 {110} 1.38 (1.00) (1.01) (1.02) Ex 4 53.6 52.3 55.2 53.2 38.2 {110} 1.45 (0.98) (1.03) (0.99) Ex 5 55.6 56.3 55.4 55.1 37.5 {110} 1.41 (1.01) (1.00) (0.99) Ex 6 47.9 48.6 47.2 47.8 35.2 {110} 1.12 (1.02) (0.99) (1.00) Ex 7 46.5 45.6 47.3 46.5 33.8 {110} 1.09 (0.98) (1.02) (1.00) Comp. pr.1 77.3 77.2 78.5 76.1 - {110} 4.25 (1.00) (1.02) (0.98) Comp. project 2 34.9 35.1 33.5 36.1 630.1 {100} 0.28 (1.01) (0.96) (1.03)

* 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.

[0055] The Au sputter targets from Examples 1-7 and Comparative Examples 1 and 2 were installed in a single plate sputtering apparatus (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; DC power input 100W; 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.

[0056]

[Table 3] Film Formation Evaluation Result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 1 8.2 5.2 Ex 2 7.9 4.6 Ex 3 8.9 5.9 Ex 4 9.1 6.1 Ex 5 8.6 6.9 Ex 6 8.6 6.5 Ex 7 8.9 6.1 Comp. pr.1 14.0 10.6 Comp. project 2 20.0 15.2

[0057] Table 2 and Table 3 show that in the Au sputter targets of Examples 1-7, Vickers hardness is 40 or more and 60 or less, 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 The sputtered 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)

[0058] 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 degree of processing 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.

[0059]

[Table 4] Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 8 99.99 80 500 twenty Ex 9 99.99 80 500 thirty Ex 10 99.99 80 500 120 Ex 11 99.99 80 400 twenty Ex 12 99.99 80 300 twenty

[0060] 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 plate sputtering target measurement method. 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 surface Au of the sputtering target to be sputtered was subjected to X-ray diffraction, and the preferred 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.

[0061]

[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 49.8 35.0 35.2 36.1 33.8 {110} 1.43 (1.00) (1.03) (0.96) Ex 9 47.5 36.8 36.2 37.1 36.8 {110} 1.60 (0.99) (1.01) (1.00) Ex 10 51.2 38.4 39.1 38.5 37.6 {110} 1.51 (1.02) (1.00) (0.98) Ex 11 50.2 34.9 35.2 36.3 33.3 {110} 1.33 (1.01) (1.04) (0.95) Ex 12 53.2 34.9 34.6 35.9 34.1 {110} 1.42 (0.99) (1.03) (0.98) Comp. pr.1 77.3 - - - - {110} 4.25 Comp. project 2 34.9 630.1 620.0 637.9 641.3 {100} 0.28 (0.98) (1.01) (1.00)

* 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.

[0062]

[Table 6] Film formation evaluation result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 8 8.6 5.6 Ex 9 8.1 4.2 Ex 10 8.5 4.6 Ex 11 9.3 5.9 Ex 12 8.2 6.1 Comp. pr.1 14.0 10.6 Comp. project 2 20.0 15.2

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

[0063] First, a certain mass of Au was placed in a graphite crucible and melted. The obtained 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: 99.99%) 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.

[0064]

[Table 7] Au purity
[%] Degree of processing
when rolling
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 13 99.99 80 500 twenty Ex 14 99.99 80 500 thirty Ex 15 99.99 80 500 60 Ex 16 99.99 80 500 90 Ex 17 99.99 80 500 120 Ex 18 99.99 80 400 twenty Ex 19 99.99 80 400 thirty Ex 20 99.99 80 300 twenty Ex 21 99.99 80 300 thirty Comp. project 3 99.99 80 100 thirty Comp. project 4 99.99 80 600 thirty

[0065] 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.

[0066]

[Table 8] Vickers hardness Average size of crystal grains
[µm] Predominant crystallographic plane Plane Orientation Index N
{110} HV _tav AD _tav Ex 13 42.0 102.0 {110} 1.44 Ex 14 41.8 101.4 {110} 1.46 Ex 15 43.1 109.9 {110} 1.52 Ex 16 42.5 105.4 {110} 1.36 Ex 17 43.8 103.2 {110} 1.41 Ex 18 45.0 103.9 {110} 1.54 Ex 19 44.2 105.3 {110} 1.35 Ex 20 41.0 103.1 {110} 1.48 Ex 21 42.5 104.0 {110} 1.31 Comp. project 3 62.8 - - - Comp. project 4 35.5 640.0 - -

[0067]

[Table 9] Film formation evaluation result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 13 6.5 4.2 Ex 14 6.1 5.2 Ex 15 5.8 6.2 Ex 16 5.5 6.1 Ex 17 5.1 5.2 Ex 18 5.9 4.8 Ex 19 6.8 5.8 Ex 20 7.1 6.2 Ex 21 6.2 5.1 Comp. project 3 20.5 13.2 Comp. project 4 28.6 16.5

(Example 22)

[0068] First, a certain mass of Au was placed in a graphite crucible and melted. The obtained molten Au was poured into a graphite mold to obtain an Au ingot. The surface of the Au ingot was ground and a hole was made with a diameter of 50 mm, whereby an Au billet (purity: 99.99%) 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 the core 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.

[0069] The Vickers hardness of the resulting Au sputter target was measured according to the above-described method for measuring 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 50.6, the average value (HV _av2 ) of the Vickers hardness in the second straight line in the surface to be sprayed was 50.4, the average value (HV _av3 ) cross-sectional Vickers hardness was 52.0 and the average (Vickers hardness (HV _tav ) of the whole target) of HV _av1 , HV _av2 and HV _av3 was 51.0. The ratios _{of HV av1} , HV _av2 and HV _av3 to the Vickers hardness (HV _tav ) of the whole target were 0.99 (HV _av1 /HV _tav ), 0.99 (HV _av2 /HV _tav ) and 1.02 (HV _av3 /HV _tav ), respectively.

[0070] Then, the average crystal grain size Au of the sputtering target was measured according to the above-described method for measuring a cylindrical sputtering target. As a result, the average size (AD _tav ) of the crystal grains of the entire target was 38.1 µm. In addition, the sputtered target Au surface to be sputtered was subjected to X-ray diffraction, and the predominantly oriented crystallographic plane was evaluated according to the above-described method. As a result, the preferred 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 1.31. 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)

[0071] 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.

[0072]

[Table 10] Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Ex 22 99.99 35 500 thirty Ex 23 99.99 35 500 60 Ex 24 99.99 35 500 90 Ex 25 99.99 35 400 thirty Ex 26 99.99 35 300 thirty Ex 27 99.99 35 400 60 Ex 28 99.99 35 300 60 Comp. project 5 99.99 35 100 thirty Comp. Project 6 99.99 35 600 thirty

[0073]

[Table 11] Vickers hardness 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 51.0 50.6 50.4 52.0 38.1 {110} 1.31 (0.99) (0.99) (1.02) Ex 23 51.5 50.6 51.3 52.6 41.2 {110} 1.52 (0.98) (1.00) (1.02) Ex 24 50.4 49.2 51.2 50.7 35.1 {110} 1.52 (0.98) (1.02) (1.01) Ex 25 53.7 53.1 54.1 54.0 38.6 {110} 1.43 (0.99) (1.01) (1.00) Ex 26 55.8 56.0 55.5 55.9 42.8 {110} 1.35 (1.00) (0.99) (1.00) Ex 27 49.2 49.8 48.6 49.2 39.8 {110} 1.18 (1.01) (0.99) (1.00) Ex 28 49.6 51.2 49.2 48.3 40.8 {110} 1.09 (1.03) (0.99) (0.97) Comp. project 5 78.1 78.1 77.1 75.0 - {110} 4.98 (1.00) (1.00) (0.98) Comp. Project 6 35.1 36.2 33.8 35.2 509.5 {100} 0.38 (1.03) (0.96) (1.00)

* 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.

[0074] The Au sputter targets from Examples 22-28 and Comparative Examples 5 and 6 were installed in a cylinder sputtering device. 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; DC power input 100W; 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.

[0075]

[Table 12] Film formation evaluation result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 22 8.1 4.6 Ex 23 8.6 5.1 Ex 24 7.5 5.9 Ex 25 8.5 4.8 Ex 26 9.1 4.8 Ex 27 8.6 5.2 Ex 28 8.9 5.6 Comp. project 5 20.1 16.4 Comp. Project 6 25.6 15.1

[0076] Table 11 and Table 12 show that in the Au sputter targets of Examples 22-28, Vickers hardness is 40 or more and 60 or less, 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 more than 1. The Au film formed by sputtering using the Au sputter A 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 29-33)

[0077] 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 processing rate 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.

[0078]

[Table 13] Au purity
[%] Degree of processing
forging
[%] Heat treatment conditions Temperature
[°C] Time
[min] Etc. 29 99.99 35 500 twenty Ex 30 99.99 35 500 thirty Project 31 99.99 35 500 120 Project 32 99.99 35 400 twenty Project 33 99.99 35 300 twenty

[0079] 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 method for measuring 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.

[0080]

[Table 14] Vickers hardness Average crystal grain size*
[µm] Predominant crystallographic plane Plane orientation index N {110} HV _tav AD _{tav ADav1 ADav2 ADav3} Ex 29 52.8 103.1 101.2 102.6 105.6 {110} 1.55 (0.98) (0.99) (1.02) Ex 30 51.2 108.1 105.3 104.6 108.1 {110} 1.35 (0.99) (0.99) (1.02) Project 31 49.3 109.8 109.2 110.2 110.1 {110} 1.42 (0.99) (1.00) (1.00) Project 32 54.6 106.1 102.2 104.1 106.1 {110} 1.51 (0.98) (1.00) (1.02) Project 33 55.5 103.2 103.2 105.2 101.1 {110} 1.48 (1.00) (1.02) (0.98) Comp. project 5 78.1 - - - - {110} 4.98 Comp. Project 6 35.1 509.5 510.2 506.2 512.0 {100} 0.38 (1.00) (0.99) (1.00)

* 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.

[0081]

[Table 15] Film formation evaluation result Standard deviation σ
film thickness Standard deviation σ
resistance values Ex 29 8.6 4.1 Ex 30 8.1 4.6 Project 31 8.5 4.0 Project 32 9.3 5.9 Etc. 33 8.2 5.7 Comp. project 5 20.1 16.4 Comp. Project 6 25.6 15.1

INDUSTRIAL APPLICABILITY

[0082] The method for producing an Au sputtering target according to the present invention is applicable to producing an Au sputtering target used to form an Au film used in various applications. In addition, the method for producing an Au film using an Au sputter target obtained by the method for producing an Au sputter target according to the present invention can produce an Au film excellent in film thickness distribution uniformity and resistance value. Thus, the characteristics of the Au film used in various applications can be improved.

Claims (4)

1. A gold film production method using a gold sputter target containing gold and unavoidable impurities, which has an average Vickers hardness of 40 or more to 60 or less, an average crystal grain size of 15 µm or more to 200 µm or less, and in which the grains of the surface to be sputtered predominantly have a crystallographic orientation {110}, the method comprising forming a gold film on a film-forming base material by sputtering a gold sputter target. 2. The method according to claim. 1, characterized in that the average value of the Vickers hardness of the gold sputtering target is from 45 or more to 55 or less, the average crystal grain size of the gold sputtering target is from 30 μm or more to 150 μm or less, and the index The N orientation of the crystallographic plane of gold {110} is 1.3 or more. 3. The method according to p. 1 or 2, characterized in that the variation of Vickers hardness over the entire sputtered target is within ±20%. 4. The method according to claim 1 or 2, characterized in that the variation in the average size of the crystal grains over the entire sputtered target is within ±20%.