Al bonding wire or al bonding ribbon

Abstract

The present invention provides an Al bonding wire or an Al bonding ribbon, which exhibits good thermal cycling reliability that is required for a next-generation SiC power semiconductor device even in a high-temperature thermal cycling test, and which also exhibits good first bonding strength. The Al bonding wire or the Al bonding ribbon contains Si in an amount of 3.0 mass% to 20.0 mass% inclusive. When the Si concentration (atom%) in the depth direction from the surface of the Al bonding wire or the Al bonding ribbon is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average concentration Ca of the Si element in a region a that has a depth of 5 nm to 50 nm inclusive from the surface to the average concentration Cb of the Si element in a region b that has a depth of 800 nm to 1,200 nm inclusive from the surface is 0.03 to 0.5 inclusive.

Description

Al bonding wire or Al bonding ribbon

[0001] The present invention relates to an Al bonding wire or an Al bonding ribbon.

[0002] In semiconductor devices, electrodes formed on a semiconductor chip are connected to electrodes on a lead frame or substrate using bonding wires (wire material) or bonding ribbons (strip material). Power semiconductor devices primarily use bonding wires or bonding ribbons made of aluminum (Al). The wire diameter of Al bonding wires is typically in the range of 100 μm to 600 μm, while Al bonding ribbons typically have widths in the range of 100 μm to 3000 μm and thicknesses in the range of 50 μm to 600 μm. Here, Al bonding wires and Al bonding ribbons are collectively referred to as Al connecting materials.

[0003] In power semiconductor devices, silicon (Si) is often used as the material for the semiconductor chip, and Al-Si alloys or Al-Cu alloys are often used as the materials for the electrodes formed on the semiconductor chip. Furthermore, power semiconductor devices using Al bonding wire or Al bonding ribbon are often used in high-power equipment such as air conditioners and solar power generation systems, as well as in-vehicle semiconductor devices.

[0004] There are two methods for joining Al bonding wire or Al bonding ribbon: first, with an electrode on a semiconductor chip, and second, with an electrode on a lead frame or substrate. Both methods use wedge bonding. Wedge bonding is a method in which ultrasonic vibration and load are applied to the Al bonding wire or Al bonding ribbon via a metal jig (tool), destroying the surface oxide film between the Al bonding wire or Al bonding ribbon and the electrode material, exposing a new surface, and performing solid-state diffusion bonding. This connection method is characterized by connecting in a solid state without melting the connecting material, and is a joining technique that differs from welding techniques that melt the connecting material.

[0005] Next-generation power semiconductor devices are required to operate stably for longer periods of time than general-purpose power semiconductor devices. Power semiconductor devices operate by repeatedly turning current on and off. When current is supplied to a Si semiconductor chip through an Al bonding wire or Al bonding ribbon, the temperature of the first bonded portion rises. On the other hand, when the current supply is stopped, the temperature of the first bonded portion drops. Thus, the first bonded portion repeatedly rises and falls in temperature during power semiconductor operation. This repeatedly applies thermal stress to the first bonded portion due to the difference in thermal expansion between the Al bonding wire or Al bonding ribbon and the semiconductor chip. When using an Al bonding wire or Al bonding ribbon made solely of high-purity Al, the Al bonding wire or Al bonding ribbon breaks down due to thermal stress in a relatively short period of time, making it difficult to achieve the performance required for next-generation power semiconductor devices. Therefore, next-generation power semiconductor devices are required to improve the bonded portion's lifespan (hereinafter also referred to as "temperature cycle reliability") associated with temperature rise and fall of the first bonded portion.

[0006] In response to the demand for temperature cycle reliability, an Al bonding wire that focuses on improving mechanical strength has been proposed. As a method for improving the mechanical properties of the Al bonding wire, a method of adding a specific element to Al has been proposed.

[0007] Patent Document 1 discloses a bonding wire made of an Al alloy containing at least magnesium (Mg) and silicon (Si), and the total content of Mg and Si is 0.03 mass % or more and 0.3 mass % or less. This patent document describes the effect of increasing strength by solid solution strengthening of Mg and Si, and the effect of precipitated magnesium silicide (Mg ２ It is disclosed that the crack propagation suppression effect of Si) delays the decrease in the bond strength of the first bonded portion in a cold temperature cycle test in the temperature range of 70°C to 120°C.

[0008] Patent Document 2 discloses a bonding wire made of an alloy containing 0.01 to 0.2 mass% iron (Fe), 1 to 20 mass ppm silicon (Si), and the remainder being Al with a purity of 99.997 mass% or more, wherein the amount of Fe in solid solution is 0.01 to 0.06%, the amount of Fe precipitated is 7 times or less the amount of Fe in solid solution, and the bonding wire has a fine structure with an average crystal grain size of 6 to 12 μm. This patent document discloses that by uniformly dispersing intermetallic compound particles of Fe and Al in Al to improve the mechanical strength of the matrix and further refining the recrystallized grains, it is possible to suppress a decrease in the bonding strength of the first bonded portion in a thermal shock test in a temperature range of -50 ° C to 200 ° C.

[0009] Patent Document 3 discloses a bonding wire obtained by melting an Al-Si alloy containing 0.1 to 5 mass % silicon (Si) with the remainder being Al and impurities, and then forming the melted Al-Si alloy into a thin wire by rapid cooling. This patent document discloses that mechanical strength is improved by rapidly cooling the molten Al-Si alloy to finely and uniformly disperse the Si.

[0010] JP 2014-131010 A JP 2014-129578 A JP 59-57440 A

[0011] As described above, next-generation power semiconductor devices are required to withstand longer periods of use than general-purpose power semiconductor devices. During operation of a power semiconductor device, the temperature of the first bonded portion repeatedly rises and falls. As a result, because the Al bonding wire or Al bonding ribbon has a larger linear thermal expansion coefficient than the semiconductor chip, thermal stress occurs at the first bonded portion due to the difference in linear thermal expansion coefficients between the two (and ultimately the difference in linear thermal expansion between the two), which can ultimately lead to fatigue failure of the Al bonding wire or Al bonding ribbon. A temperature cycle test is one type of test for accelerating evaluation of the life (temperature cycle reliability) of such a first bonded portion as it rises and falls in temperature. The Al bonding wire or Al bonding ribbon used in next-generation power semiconductor devices is required to exhibit excellent temperature cycle reliability in a temperature cycle test.

[0012] It is predicted that the use of silicon carbide (SiC), which has high heat resistance, will increase in next-generation power semiconductor devices that will replace the silicon (Si) power semiconductor devices that have been mainstream until now. Connections for SiC power semiconductor devices will be required to have temperature cycle reliability under even stricter conditions than currently. For example, while Si power semiconductor devices are required to have temperature cycle reliability in the temperature range of -40°C to 150°C, SiC power semiconductor devices will be required to have temperature cycle reliability in the stricter temperature range of -40°C to 175°C.

[0013] Furthermore, next-generation SiC power semiconductor devices that utilize the heat resistance of SiC for use at high power output are required to exhibit good temperature cycle reliability even under severe test conditions in which the upper limit temperature of the temperature cycle test is increased to 185° C. If the upper limit temperature of the temperature cycle test is further increased from 175° C. to 185° C., the temperature difference in the temperature cycle increases by 10° C., and the linear thermal expansion difference at the bonded portion of the Al bonding wire or Al bonding ribbon increases, accelerating fatigue fracture, which becomes a problem.

[0014] Furthermore, if bonding defects, such as peeling of the Al bonding wire or Al bonding ribbon from the electrode, occur during bonding, this can lead to product defects and reduced manufacturing yields, so it is necessary to obtain good bonding strength at each bond. In this regard, applying strong ultrasonic vibrations or loads to the first bonded portion to obtain good bonding strength can damage the semiconductor chip. In particular, when using an Al bonding wire or Al bonding ribbon strengthened by the addition of Si or the like, the hardness of the wire or ribbon makes it easy to damage the semiconductor chip during the first bond. Adjusting the ultrasonic vibration or load to reduce such damage can result in insufficient bonding strength at the first bonded portion (hereinafter simply referred to as "first bond strength"). These problems during the initial bonding of the first bonded portion ultimately lead to reduced and unstable temperature cycle reliability, hindering the practical use of Al bonding wires or Al bonding ribbons strengthened by the addition of Si or the like.

[0015] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability even in high-temperature temperature cycle tests, which are required for next-generation SiC power semiconductor devices, and also exhibits good first bonding strength.

[0016] As a result of intensive research into the above-mentioned problems, the inventors have discovered that the above-mentioned problems can be solved by an Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, and when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average Si element concentration Ca in a region a from a depth of 5 nm to 50 nm from the surface to the average Si element concentration Cb in a region b from a depth of 800 nm to 1200 nm from the surface is 0.03 or more and 0.5 or less. Based on this knowledge, the inventors have conducted further research and have completed the present invention.

[0017] That is, the present invention includes the following: <1> An Al bonding wire or Al bonding ribbon containing 3.0 mass % or more and 20.0 mass % or less of Si, wherein, when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average Si element concentration Ca in a region a from 5 nm to 50 nm deep from the surface to the average Si element concentration Cb in a region b from 800 nm to 1200 nm deep from the surface is 0.03 to 0.5. <2> The Al bonding wire or Al bonding ribbon according to <1>, wherein the average diameter of the Si phase in an L cross section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is 0.8 μm to 4 μm. <3> An Al bonding wire or Al bonding ribbon according to <1> or <2>, wherein the average concentration Cf of Si element in a region f from 5 nm to 30 nm deep from the surface is 0.1 atomic % to 4 atomic %. <4> An Al bonding wire or Al bonding ribbon according to any one of <1> to <3>, wherein, when the crystal orientation of the Al phase in an L cross section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <100> crystal orientation, which has an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction), is 15% to 50%. <5> An Al bonding wire or Al bonding ribbon according to any one of <1> to <4>, further containing one or more of Sr, Na, P, and B in a total amount of 10 ppm to 800 ppm by mass. <6> The Al bonding wire or Al bonding ribbon according to any one of <1> to <5>, further containing one or more of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 ppm by mass to 2000 ppm by mass.<7> The Al bonding wire or Al bonding ribbon according to any one of <1> to <6>, wherein the total concentration of elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn, and Mg in the Al bonding wire or Al bonding ribbon is 0.5 mass% or less. <8> The Al bonding wire or Al bonding ribbon according to any one of <2> to <7>, wherein the average diameter of the Si phase is a value measured using a SEM-EDS-EBSD device. <9> The Al bonding wire or Al bonding ribbon according to any one of <4> to <8>, wherein the orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device. <10> The Al bonding wire or Al bonding ribbon according to any one of <1> to <9>, which is for a semiconductor device. <11> A semiconductor device comprising the Al bonding wire or Al bonding ribbon according to any one of <1> to <10>.

[0018] According to the present invention, it is possible to provide an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability even in high-temperature temperature cycle tests, which are required for next-generation SiC power semiconductor devices, and that also exhibits good first bonding strength.

[0019] FIG. 1 shows an example of a Si concentration profile when the Si concentration in the depth direction of an Al bonding wire or Al bonding wire of the present invention is measured and evaluated by XPS. This is a profile of the Si concentration in the depth direction when the total of metal Si and metal Al is 100 atomic %. FIG. 2 shows an example of a Si2p Si0 valence peak obtained by XPS for an Al bonding wire or Al bonding ribbon of the present invention. FIG. 2 is also a diagram for explaining the quantification of Si element based on the Si2p Si0 valence peak. FIG. 3 is a schematic diagram for explaining the measurement surface (inspection surface) when measuring the crystal orientation of the Al phase and the average diameter of the Si phase for an Al bonding wire. The measurement surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding wire. FIG. 4 is a schematic diagram for explaining the measurement surface (inspection surface) when measuring the crystal orientation of the Al phase and the average diameter of the Si phase for an Al bonding ribbon. The measurement surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding ribbon.

[0020] The present invention will be described in detail below with reference to preferred embodiments. While the description may refer to drawings, each drawing merely shows the shape, size, and arrangement of components to the extent that the invention can be understood. The present invention is not limited to the following embodiments and examples, and can be modified and implemented as desired within the scope of the claims of the present invention and their equivalents.

[0021] [Al bonding wire or Al bonding ribbon] The Al bonding wire or Al bonding ribbon of the present invention contains 3.0 mass% or more and 20.0 mass% or less of Si, and when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average concentration of Si element in a region a having a depth from the surface of 5 nm to 50 nm and the average concentration Cb of Si element in a region b having a depth from the surface of 800 nm to 1200 nm is 0.03 or more and 0.5 or less.

[0022] As mentioned above, in a temperature cycle test (hereinafter also referred to as a "TCT (Temperature Cycle Test)"), when an Al bonding wire or Al bonding ribbon made only of high-purity Al is used, cracks propagate relatively quickly inside the Al bonding wire or Al bonding ribbon, resulting in a problem of reduced temperature cycle reliability. It has been confirmed that the use of an Al alloy with a high concentration of Si added can reduce the thermal expansion of the Al bonding wire or Al bonding ribbon and improve temperature cycle reliability. On the other hand, even when an Al alloy with a high concentration of Si added is used, sufficient temperature cycle reliability may not be achieved in a high-temperature temperature cycle test (hereinafter also referred to as a "high-temperature temperature cycle test" or "high-temperature TCT") employing a considerably high upper limit temperature (e.g., 185°C). As mentioned above, next-generation power semiconductor devices with high heat resistance, such as SiC power semiconductor devices, are required to exhibit good temperature cycle reliability even in a high-temperature temperature cycle test employing such harsh test conditions, and further improvement in temperature cycle reliability is required.

[0023] In high-temperature temperature cycle tests, it was confirmed that defects are accelerated near the bonding interface at the initial stage of the first bonding of Al bonding wire or Al bonding ribbon. Regarding the bonding method of Al bonding wire or Al bonding ribbon, since bonding is usually performed at room temperature, diffusion at the bonding interface is suppressed, and the surface condition of the Al bonding wire or Al bonding ribbon has a strong effect on bondability. In high-temperature temperature cycle tests, the linear thermal expansion difference at the bonded portion is expanded due to the increase in the temperature difference during the temperature cycle, and thermal strain is concentrated near the bonding interface from an early stage. Therefore, the surface condition of the Al bonding wire or Al bonding ribbon can be a factor in accelerating crack propagation. Cracks grow at the bonding interface or propagate inside the Al bonding wire or Al bonding ribbon, accelerating the deterioration of temperature cycle reliability.

[0024] The present inventors have discovered that modifying the surface of an Al bonding wire or Al bonding ribbon is effective in preventing crack propagation at the bond interface, which can cause reliability degradation during high-temperature temperature cycle testing. For Al bonding wires or Al bonding ribbons made of an Al alloy with a high concentration of Si (hereinafter also referred to as a "high-concentration Al-Si alloy"), the surface condition has a greater effect on temperature cycle reliability. Specifically, for an Al bonding wire or Al bonding ribbon made of a high-concentration Al-Si alloy, by providing a predetermined gradient (gradient) in the Si concentration along the depth direction in a region from the surface to a certain depth, specifically, by providing a gradient in the Si concentration such that the ratio Ca / Cb of the average Si element concentration Ca in a region a from 5 nm to 50 nm deep from the surface to the average Si element concentration Cb in a region b from 800 nm to 1200 nm deep from the surface is 0.03 to 0.5, the inventors have discovered that crack propagation near the bond interface can be suppressed even during high-temperature temperature cycle testing, thereby achieving good temperature cycle reliability. We also discovered that by modifying the surface of an Al bonding wire or Al bonding ribbon made of a high-concentration Al-Si alloy to have the above-mentioned specified Si concentration gradient, problems that occur during the initial bonding of the first bonding portion can be solved and good first bonding strength can be achieved.

[0025] The reason why the Al bonding wire or Al bonding ribbon of the present invention exhibits good temperature cycle reliability even in high-temperature temperature cycle tests and also exhibits good first bonding strength is presumed to be as follows.

[0026] For Al bonding wires or Al bonding ribbons made of a high-concentration Al-Si alloy, in the region from the surface to a certain depth, a predetermined gradient in the Si concentration in the depth direction, i.e., a low Si concentration near the surface and a high Si concentration deep within, is provided. By providing a gradient in the Si concentration so as to satisfy the above-mentioned Ca / Cb ratio, it is believed that the surface deformability of the Al bonding wire or Al bonding ribbon when ultrasonic vibration or load is applied during bonding is improved, the destruction of the surface oxide film is promoted, and the diffusion of Al atoms at the bonding interface is promoted, resulting in increased bonding strength and stabilization of the deformed shape, and further contributing to maintaining a strong bond at the bonding interface during temperature cycle testing. It is believed that the factor that brings about these actions and effects is that the surface side is relatively softer and more purified (in terms of Al concentration) than the deeper portions in the region from the surface of the Al bonding wire or Al bonding ribbon to a certain depth. It is believed that the synergistic effects of the interface control effect due to the presence of a certain low concentration gradient of Si concentration on the surface side, the contribution of the internal Si phase, which will be described later, to the reduction in the difference in linear thermal expansion coefficients and the resulting effect of reducing thermal stress, can provide a remarkable effect of realizing good temperature cycle reliability even in a high-temperature temperature cycle test with an upper limit temperature of 185°C.

[0027] As described above, the Al bonding wire or Al bonding ribbon of the present invention has a surface modified to have a predetermined gradient in the Si concentration in the depth direction in the region from the surface to a certain depth. As a result, it is presumed that the Al bonding wire or Al bonding ribbon exhibits good temperature cycle reliability even in high-temperature temperature cycle tests as described above, as well as good first bonding strength.

[0028] The configuration of the Al bonding wire or Al bonding ribbon of the present invention will be described in detail below. Hereinafter, the Al bonding wire and Al bonding ribbon will be collectively referred to as "Al bonding wire, etc." or "wire, etc."

[0029] -Si Concentration- The Al bonding wire or Al bonding ribbon of the present invention contains 3.0 mass % or more and 20.0 mass % or less of Si.

[0030] The Si concentration in the range of 3.0% by mass or more and 20.0% by mass or less helps reduce thermal distortion at the joint and improve temperature cycle characteristics. Specifically, a Si concentration of 3.0% by mass or more can significantly improve temperature cycle reliability even in high-temperature temperature cycle tests. Furthermore, with advances and optimization of equipment and conditions used in the manufacture and bonding of wires, etc., higher Si concentration limits have become permissible while suppressing defects such as wire breakage during processing, deterioration of surface properties, reduction in initial bond strength due to hardening, and damage to semiconductor chips. However, a Si concentration of 20.0% by mass or less can effectively suppress these defects and achieve the desired temperature cycle reliability. From the viewpoint of obtaining good temperature cycle reliability even in high-temperature temperature cycle tests, the Si concentration in the Al bonding wire etc. of the present invention is 3.0% by mass or more, preferably 3.5% by mass or more, more preferably 4.0% by mass or more, and even more preferably 4.2% by mass or more, 4.4% by mass or more, 4.5% by mass or more, 4.6% by mass or more, 4.8% by mass or more, or 5.0% by mass or more. Further, from the viewpoint of achieving the desired temperature cycle reliability while effectively suppressing defects such as a decrease in initial bonding strength due to hardening and damage to the semiconductor chip, the Si concentration in the Al bonding wire etc. of the present invention is 20.0% by mass or less, preferably 19.0% by mass or less, 18.0% by mass or less, 17.0% by mass or less, 16.0% by mass or less, 15.0% by mass or less, 14.5% by mass or less, 14.0% by mass or less, 13.5% by mass or less, 13.0% by mass or less, or 12.5% ​​by mass or less. Furthermore, if the hardness of the Al bonding wire, etc. is high, damage to the semiconductor chip is likely to occur during the first bonding depending on the bonding conditions of ultrasonic vibration and load. From the viewpoint of obtaining good bonding strength under a wider range of bonding conditions, the Si concentration in the Al bonding wire, etc. of the present invention is more preferably 12.0 mass% or less, even more preferably 11.5 mass% or less or 11.0 mass% or less, and particularly preferably 10.8 mass% or less, 10.6 mass% or less, 10.5 mass% or less, 10.4 mass% or less, 10.2 mass% or less, or 10.0 mass% or less.

[0031] For example, an ICP (Inductively Coupled Plasma) optical emission spectrometer or an ICP mass spectrometer can be used to analyze the concentration of elements contained in the Al bonding wire of the present invention. When elements derived from atmospheric contaminants such as oxygen and carbon are adsorbed on the surface of the Al bonding wire, it is effective to clean the wire with an acid or alkali depending on the adsorbed substance before analysis.

[0032] The Al bonding wire of the present invention contains 3.0% by mass or more and 20.0% by mass or less of Si, and is composed of an Al phase in which Si is solid-solved in Al, and a Si phase formed by crystallization or precipitation of Si. Here, the Al phase may contain other additive elements in addition to Si as a solid solution. The Si phase is a general term for Si crystallized deposits and Si precipitates. The Si crystallized deposits are formed from the melt during solidification and are coarse, measuring approximately 1 to 25 μm in size, while the Si precipitates are formed from the solid state and are small, measuring approximately 0.1 to several μm in size. The Si phase has a smaller linear thermal expansion coefficient than Al, which contributes to reducing the difference in the linear thermal expansion coefficient between the Al bonding wire and the semiconductor chip, thereby reducing thermal stress and improving temperature cycle reliability.

[0033] -Si concentration gradient- When the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon of the present invention is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average Si element concentration Ca in a region a having a depth from the surface of 5 nm to 50 nm, to the average Si element concentration Cb in a region b having a depth from the surface of 800 nm to 1200 nm, is 0.03 or more and 0.5 or less.

[0034] In the present invention, the gradient of Si concentration in the depth direction is measured and evaluated by X-ray photoelectron spectroscopy (XPS). XPS allows for accurate quantitative analysis of Al bonding wires and other materials in the depth direction from their surface by utilizing the sputtering operation of the device. By using XPS, Si element concentrations as low as about 0.1 atomic % can be accurately measured.

[0035] In the present invention, when measuring and evaluating the gradient of the Si concentration in the depth direction by XPS, the Si concentration is determined when the total of metal Si and metal Al is taken as 100 atomic %.

[0036] 1 shows an example of a Si concentration profile obtained by measuring and evaluating the Si concentration in the depth direction of the Al bonding wire or Al bonding ribbon of the present invention using XPS. In the region from the surface to a certain depth, a predetermined gradient in the Si concentration in the depth direction is observed, i.e., the Si concentration on the surface side is low, the Si concentration in the depth portion is high, and the Si concentration gradually increases in the depth direction.

[0037] The form of Si detected by XPS includes dissolved Si in the Al phase, Si particles (precipitated / crystallized), and intermetallic compounds containing Si. The origin of the detected Si may vary as described above, but whether or not the predetermined Si concentration gradient (the above-mentioned ratio Ca / Cb) is met is determined based on the Si concentration detected by XPS without distinguishing between them. An important feature of the present invention is that the desired problems and effects can be solved and achieved by adjusting the Si concentration gradient in the depth direction measured by XPS in this way.

[0038] The Si concentration is measured by XPS and determined from the peak of detected metallic Si (Si with a valence of zero). Because the peaks of metallic Si and oxidized Si are detected at different energies, the concentration of metallic Si can be determined separately from the oxidized Si. The concentration of metallic Si in the surface region of the Al bonding wire or Al bonding ribbon affects the temperature cycle reliability and first bond strength. Si oxide rarely forms on the surface of the Al bonding wire or Al bonding ribbon or on the surface of Si particles, and even if it does form, the oxidized Si is quite thin. Therefore, it has been confirmed that it has almost no effect on the temperature cycle reliability and first bond strength, and is therefore excluded from the analysis target in determining the concentration gradient of the present invention.

[0039] In the present invention, when the Si concentration in the depth direction from the surface of an Al bonding wire or Al bonding ribbon is measured by XPS, the ratio Ca / Cb of the average Si element concentration Ca in a region a having a depth from the surface of 5 nm to 50 nm to the average Si element concentration Cb in a region b having a depth from the surface of 800 nm to 1200 nm is in the range of 0.03 to 0.5.

[0040] Here, the average concentration Ca of Si element in region a, which is 5 nm to 50 nm deep from the surface, was used because region a is deformed by ultrasonic vibration and load application during bonding, which has a significant impact on the performance of the bonding interface. The analysis of the outermost surface region, which is less than 5 nm deep from the surface, is easily affected by surface contamination and the Si concentration measured by XPS varies greatly, so it was excluded from the analysis range. Regions greater than 50 nm deep from the surface are excluded from the analysis range because they have little effect on the bonding interface. The average concentration Cb of Si element in region b, which is 800 nm to 1200 nm deep from the surface, was used because it is an appropriate depth range for determining the Si concentration representing the internal composition of the Al bonding wire or Al bonding ribbon, taking into account the fact that the Si concentration is almost stable and that the sputtering time during measurement can be avoided to be long, thereby ensuring analytical efficiency. The influence of variations in Si concentration is minimized by using the average Si element concentrations (Ca and Cb) for both the region a having a depth from the surface of 5 nm to 50 nm and the region b having a depth from the surface of 800 nm to 1200 nm, and then evaluating the Si concentration gradient using the ratio Ca / Cb. Furthermore, using the average Si element concentration Cb in the region b inside the sample measured by XPS and comparing it with the average Si element concentration Ca in the region a on the sample surface measured by the same method to calculate the ratio Ca / Cb is effective in accurately determining the gradient of the Si concentration in the depth direction. This makes it possible to accurately determine the success or failure of the gradient of the Si concentration in the depth direction, which is suitable for realizing an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability in high-temperature temperature cycle tests and good first bond strength.

[0041] By having the above ratio Ca / Cb, which is the relative ratio of the Si concentration near the surface to the deep portion, in the range of 0.03 to 0.5, it is possible to realize an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability even in a high-temperature temperature cycle test and exhibits good first bond strength, by improving the deformability of the surface of the Al bonding wire or Al bonding ribbon when ultrasonic vibration or load is applied during bonding, promoting the destruction of the surface oxide film, and promoting the diffusion of Al atoms at the bond interface. From the viewpoint of being able to realize an Al bonding wire or Al bonding ribbon that exhibits even better temperature cycle reliability even in a high-temperature temperature cycle test and exhibits even better first bond strength, such ratio Ca / Cb is preferably 0.48 or less, more preferably 0.46 or less, and even more preferably 0.45 or less, 0.44 or less, 0.42 or less, or 0.4 or less. The lower limit of the ratio Ca / Cb is 0.03 or more, which can solve or achieve the desired problems and effects, but may be, for example, 0.04 or more, 0.05 or more, 0.06 or more, 0.08 or more, or 0.1 or more. In particular, when the ratio Ca / Cb is 0.45 or less, it is possible to achieve particularly good temperature cycle reliability even in a high-temperature temperature cycle test, and it is also preferable because it is easy to achieve even better first bonding strength.

[0042] In the present invention, by controlling the above-mentioned ratio Ca / Cb, which is the relative ratio of the Si concentration near the surface to the deep portion, within a certain range of 0.03 or more and 0.5 or less, it has been possible to realize an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability even in high-temperature temperature cycle tests and also exhibits good first bonding strength, and it has been found that controlling such ratio Ca / Cb within a certain range is effective and important in solving the problem.

[0043] In the present invention, the Si concentration in the depth direction in a region from the surface of the Al bonding wire or Al bonding ribbon to a certain depth can be measured by performing composition analysis by XPS while digging down from the surface of the Al bonding wire or Al bonding ribbon in the depth direction (towards the center of the wire, etc.) by Ar sputtering. In detail, 1) sputtering with Ar and 2) composition analysis of the surface after sputtering are repeated, and the change in concentration of Si element in the depth (center) direction from the surface of the Al bonding wire or Al bonding ribbon (so-called concentration profile in the depth direction) can be obtained.

[0044] In one embodiment, the Si concentration in the depth direction in a region from the surface to a certain depth of the Al bonding wire or Al bonding ribbon of the present invention is measured by the following procedures (1) to (4).

[0045] (1) Preparation of Measurement Sample: The Al bonding wire or Al bonding ribbon sample to be measured is placed on the sample stage. At this time, the position is adjusted so that the longitudinal direction of the sample is horizontal on the operation screen of the XPS instrument. Note that if the sample is an Al bonding ribbon (with a rectangular or nearly rectangular cross-sectional shape with width W and thickness T), it is placed so that the width W direction is parallel to the surface of the sample stage and the thickness T direction is perpendicular to the surface of the sample stage.

[0046] (2) XPS Measurement In XPS measurement, the measurement area is selected so that the vicinity of the apex of the Al bonding wire or Al bonding ribbon sample is the measurement area while viewing the screen of the SXI (Scanning X-ray Image) of the device. Here, the apex of the Al bonding wire or Al bonding ribbon sample is the point directly above the central axis of the sample when observed from directly above. Then, under the following conditions, 1) sputtering with Ar and 2) composition analysis of the surface after sputtering were repeated, and measurements were performed in the depth direction from the surface of the sample to detect the Si2p and Al2p spectra. The peaks of the Si2p and Al2p spectra were detected at energy positions of approximately 98.5 to 99.5 eV and 71.5 to 73.0 eV, respectively. Measurement device: Versa Probe 3 manufactured by ULVAC-PHI. Ultimate vacuum: Approximately 1 x 10 －８ Torr X-ray source: Monochromated Al (1486.6 eV) Measurement area: 100 μm (longitudinal direction of sample) × 20 μm (circumferential direction of sample) square Photoelectron take-off angle: 45 degrees Detection depth: several nm Ar sputtering Acceleration voltage: 2 kV Sputtering area: 2 × 2 mm square Sputtering rate: 9.2 nm / min (SiO ２ Analysis pitch in the depth direction: 5 nm pitch (depth from the surface in the range of 0 to 50 nm), 10 nm pitch (depth from the surface in the range of 50 to 200 nm), 20 nm pitch (depth from the surface in the range of more than 200 nm)

[0047] As mentioned above, in the XPS measurement, the scale of sputtering rate and depth is the general SiO ２ The analysis pitch in the depth direction can be selected to be finer at the surface and coarser at the deeper portions, taking into consideration the accuracy of the analysis, the measurement time, the workability, etc. For example, as described above, the pitch can be set to 5 nm for a depth range of 0 to 50 nm from the surface, 10 nm for a depth range of 50 to 200 nm from the surface, and 200 nm for a depth range of more than 200 nm from the surface.

[0048] (3) Quantification of Si and Al Elements Based on the Si2p and Al2p detection spectra acquired at each depth position in the depth direction from the surface of the sample, the quantification of Si and Al elements is performed using the following procedure. Specifically, the quantification of Si element is performed within the energy quantification range (approximately 95.0 to 101.0 eV) that includes the peak of Si2p Si0 valence (metallic Si). Depending on the shape of the above peak, the energy values ​​of the low-energy end and high-energy end were adjusted within the above quantification range. The background of the quantification range is determined using the Shirley method, and the Si element is quantified using the peak area after subtracting the background.

[0049] 2 shows an example of the Si2p Si0 valence peak obtained by XPS for the Al bonding wire or Al bonding ribbon of the present invention. The Si2p Si0 valence peak is included in the quantitative range of about 95.0 to 101.0 eV, and the low-energy edge of the peak can be selected between 95 to 96.5 eV and the high-energy edge can be selected between 99.8 to 101.3 eV.

[0050] The quantitative analysis of Al element is carried out in the same procedure as the above-mentioned quantification of Si element, for the quantification range of energy (approximately 69.0 to 79.0 eV) including the peak of Al2p Al0 valence (metallic Al).

[0051] (4) Calculation of Si Concentration Using the quantitative values ​​of Si and Al elements at each depth position from the surface of the sample in the depth direction and the relative sensitivity coefficients of each element set in the XPS instrument, the Si concentration (atomic %) is calculated when the total of Si and Al at each depth position from the surface of the sample in the depth direction is taken as 100 atomic %. Note that the element C, which is affected by contaminants on the sample surface, is excluded from the analysis. The arithmetic mean value of the Si concentration in region a, which is 5 nm to 50 nm deep from the surface, is calculated as average concentration Ca; the arithmetic mean value of the Si concentration in region b, which is 800 nm to 1200 nm deep from the surface, is calculated as average concentration Cb; and the arithmetic mean value of the Si concentration in region f, which is 5 nm to 30 nm deep from the surface, is calculated as average concentration Cf.

[0052] In the present invention, the gradient of the Si concentration in the depth direction and the average concentration of Si element near the surface, which will be described later, are evaluated by the average (arithmetic mean) of the values ​​obtained by measuring two or more locations. From the viewpoint of ensuring the objectivity of the measurement data, it is preferable to measure two or more samples randomly selected from multiple samples obtained from the Al bonding wire or Al bonding ribbon to be measured at intervals of 50 cm or more in the central axis direction of the wire or ribbon. The average concentrations Ca, Cb, and Cf are the averages (arithmetic means) of the values ​​obtained for each sample by the above steps (1) to (4).

[0053] - Average concentration of Si element near the surface - When the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon of the present invention is measured by XPS, it is preferable that in addition to satisfying the specified Si concentration gradient (the above ratio Ca / Cb), the average concentration Cf of Si element in a region f from 5 nm to 30 nm deep from the surface is 0.1 atomic % to 4 atomic %.

[0054] In addition to satisfying the predetermined Si concentration gradient (the above ratio Ca / Cb), by controlling the average concentration Cf of Si elements in the near-surface region f within the above range, the life (number of cycles until a defect occurs) of the Al bonding wire or Al bonding ribbon can be further improved in high-temperature temperature cycle tests. By keeping the average concentration Cf low within the above range, it is possible to soften the surface of the Al bonding wire, etc., promote recrystallization, improve deformability during bonding, and form a flat bonding interface, and as a result, it is believed that the life of the Al bonding wire, etc. can be further improved in high-temperature temperature cycle tests. From the viewpoint of further improving the life of the Al bonding wire, etc. in high-temperature temperature cycle tests, the average concentration Cf of Si elements in the near-surface region f is more preferably 3.8 atomic % or less or 3.6 atomic % or less, and even more preferably 3.5 atomic % or less, 3.4 atomic % or less, 3.2 atomic % or less, or 3 atomic % or less. The lower limit of the average concentration Cf is preferably 0.1 atomic % or more, and may be, for example, 0.12 atomic % or more, 0.14 atomic % or more, 0.15 atomic % or more, 0.16 atomic % or more, 0.18 atomic % or more, or 0.2 atomic % or more. The reason why the average concentration Cf of Si element in the region f near the surface is used here is because the region f has a large effect on the temperature cycle reliability and life in a high-temperature temperature cycle test.

[0055] The above-mentioned life improvement effect can be further improved by controlling the average concentration Cf of Si elements near the surface to be lower than the Si concentration Ct throughout the Al bonding wire or Al bonding ribbon. In one embodiment, the ratio Cf / Ct of the surface concentration Cf of Si elements to the Si concentration Ct throughout the Al bonding wire or Al bonding ribbon is preferably in the range of 0.03 to 0.8. Here, the Si concentration Ct is based on the Si concentration throughout the Al bonding wire or Al bonding ribbon measured using an ICP optical emission spectrometer or an ICP mass spectrometer. From the viewpoint of achieving even better temperature cycle reliability even in high-temperature temperature cycle tests, the ratio Cf / Ct is more preferably 0.7 or less, even more preferably 0.6 or less, 0.55 or less, or 0.5 or less. Furthermore, the lower limit of the ratio Cf / Ct is preferably 0.03 or more, but may be, for example, 0.04 or more, 0.05 or more, 0.06 or more, 0.08 or more, or 0.1 or more. By controlling the ratio Cf / Ct within the above range, deformation near the surface of the Al bonding wire or Al bonding ribbon when ultrasonic vibration or load is applied during bonding can be promoted, and metal bonding at the bonding interface can be promoted, resulting in a high effect of improving the life of the Al bonding wire or Al bonding ribbon in high-temperature temperature cycle tests.

[0056] As described above, in the present invention, the gradient of the Si concentration in the depth direction and the concentration of Si element near the surface are measured and evaluated by XPS. By using XPS, it is possible to accurately measure a low concentration of Si element of about 0.1 atomic %, and it is possible to accurately measure and determine whether the conditions of the gradient of the Si concentration in the depth direction and the concentration of Si element near the surface are met, which are suitable for realizing an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability in a high-temperature temperature cycle test and good first bond strength.

[0057] -Average diameter of Si phase in L cross section- The Al bonding wire or Al bonding ribbon of the present invention preferably has an average diameter of Si phase in its L cross section (cross section in the central axis direction including the central axis) of 0.8 μm or more and 4 μm or less.

[0058] Here, in the present invention, the central axis of the Al bonding wire, the cross section in the central axis direction including the central axis (L cross section), and the direction parallel to the central axis (RD direction) described later are as shown in Figure 3. Figure 3 shows the case of an Al bonding wire having a circular cross section, but in the case of an Al bonding ribbon having a rectangular or approximately rectangular cross section with a width W and a thickness T, the central axis refers to the axis passing through the center of the width W and the center of the thickness T, and the L cross section refers to a cross section in the central axis direction including the central axis and in the direction of the thickness T (Figure 4). Here, when processing the cross section to expose the L cross section of the Al bonding wire, it may be shifted from the central axis of the Al bonding wire. In this case, if the length of the L cross section in the direction perpendicular to the central axis is 90% or more of the wire diameter of the Al bonding wire, it can be considered to be a cross section including the central axis.

[0059] In Al alloys containing Si at a high concentration of 3.0% by mass or more and 20.0% by mass or less, Si present beyond the solid solubility of Si exists as Si particles due to crystallization or precipitation. If the Si particles become coarse, cracks will occur at the ends of the Si particles during high-temperature temperature cycle tests, causing a decrease in the fatigue resistance of the surface region of the Al bonding wire or Al bonding ribbon. On the other hand, by controlling the average diameter of the Si phase in the L cross section to a relatively small particle size of 0.8 μm or more and 4 μm or less, the thermal fatigue resistance of the Si particles in the surface region can be improved.

[0060] The Si content is 3.0 mass % or more and 20.0 mass % or less, and when the Si concentration in the depth direction from the surface is measured by XPS, the ratio Ca / Cb of the average Si concentration Ca in a region a from 5 nm to 50 nm deep from the surface to the average Si concentration Cb in a region b from 800 nm to 1200 nm deep from the surface is in the range of 0.03 to 0.5. In addition to satisfying the above-mentioned characteristics, by having the average diameter of the Si phase in the L cross section be in the range of 0.8 μm to 4 μm, better temperature cycle reliability can be achieved in high-temperature temperature cycle tests. When the Si concentration gradient in the region from the surface to a certain depth and the small-grain Si phase are combined, a synergistic effect is obtained in terms of the control of the bonding interface and the reduction of thermal strain, which are the respective effects, and the improvement of temperature cycle reliability in high-temperature temperature cycle tests can be further enhanced. Furthermore, since the Si phase has a lower linear thermal expansion coefficient than Al, the Si phase present inside the surface region reduces the linear thermal expansion coefficient of the entire Al bonding wire or Al bonding ribbon, thereby improving temperature cycle reliability.

[0061] From the viewpoint of achieving better temperature cycle reliability in high-temperature temperature cycle tests, the average diameter of the Si phase in the L cross section of the Al bonding wire or Al bonding ribbon of the present invention is more preferably 3.8 μm or less or 3.5 μm or less, even more preferably 3.4 μm or less, 3.2 μm or less, or 3 μm or less, and the lower limit is more preferably 1 μm or more, even more preferably 1.1 μm or more, and even more preferably 1.2 μm or more or 1.5 μm or more.

[0062] A method for measuring the average diameter of the Si phase in the L cross section of an Al bonding wire or Al bonding ribbon will be described. The average diameter of the Si phase in the L cross section can be measured using an SEM-EDS-EBSD device. Specifically, a method can be used in which information on the Al concentration and Si concentration obtained by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) is combined with information on the crystal orientation obtained by electron backscatter diffraction (EBSD). More specifically, in a measurement area in which the L cross section of the Al bonding wire or Al bonding ribbon is used as the inspection surface, Al and Si concentration measurement using EDS and crystal orientation analysis using EBSD are simultaneously performed. Next, the Al phase and Si phase are separated and extracted from the EDS measurement results using the analysis software provided with the device. Specifically, it is preferable to use the Chi Scan function, which is a function of the OIM Data Collection or OIM Analysis (both manufactured by TSL Solutions) analysis software provided with the FE-SEM (Field Emission-Scanning Electron Microscope) device. The crystal orientation of the region identified as the Si phase can then be analyzed using the analysis software provided with the device. If the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the circle-equivalent diameter is calculated. The average circle-equivalent diameter of each Si phase is defined as the average diameter of the Si phase. In the process of determining the average diameter of the Si phase, areas where the crystal orientation cannot be measured or areas where the crystal orientation can be measured but the reliability of the orientation analysis is low are excluded from the calculation. Therefore, in one embodiment, the average diameter of the Si phase in the L-section of the Al bonding wire or Al bonding ribbon of the present invention is calculated by the following steps (1) to (3): (1) Using the L-section of the Al bonding wire or Al bonding ribbon as the inspection surface, the Al and Si concentrations are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are separated and extracted.Specifically, by setting a tolerance equivalent to the Si threshold value from the Si EDS measurement results, Al and Si can be separated and identified. The crystal orientation can be analyzed using the Al and Si crystal information in the material file. (3) For the region identified as the Si phase, the crystal orientation is analyzed. If the misorientation between measurement points is 15° or more, it is determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain is calculated. The circle-equivalent diameters of each crystal grain are then averaged to calculate the average diameter of the Si phase. Here, for the average calculation, the average value calculated by area averaging (area-weighted average), which can be selected in the software provided with the device, is used. By using the average value calculated by area averaging, it is possible to accurately measure and determine whether the conditions related to the average diameter of the Si phase are met, which is suitable for achieving even better temperature cycle reliability in high-temperature temperature cycle tests. The area average calculation is calculated by averaging the values ​​obtained by multiplying the proportion of each particle area to the total particle area, and this calculation is performed automatically by the software.

[0063] In the present invention, when calculating the average diameter of the Si phases in the L cross section, only Si phases having a diameter (equivalent circle diameter) of 0.5 μm or more are considered, which makes it possible to accurately determine whether the requirement for the average diameter of the Si phases in the L cross section, which is suitable for realizing better temperature cycle reliability in a high-temperature temperature cycle test, is met.

[0064] In the above procedure (2), the Tolerance (%) setting can be selected in the range of 20 to 40%, and in a standard analysis of the L cross section of an Al bonding wire or Al bonding ribbon, it is preferable to compare it at about 30%. The procedure for adjusting this Tolerance is explained below. It is preferable to select or confirm the Tolerance value so that the shape and size of the Si phase extracted and identified by the Chi Scan function are equivalent to those identified from the EDS map, which displays the Si element concentration in EDS analysis in two dimensions.

[0065] In the present invention, the average diameter of the Si phase in the L cross section is the average (arithmetic mean) of the values ​​obtained by measuring three or more locations. When selecting the measurement area, from the viewpoint of ensuring the objectivity of the measurement data, it is preferable to obtain measurement samples from the Al bonding wire or Al bonding ribbon to be measured at intervals of 50 cm or more in the central axis direction of the Al bonding wire or Al bonding ribbon, and provide them for measurement. Furthermore, in the present invention, the measurement area in the L cross section using the EBSD method has a length in the central axis direction of the Al bonding wire or Al bonding ribbon of 300 μm or more and less than 800 μm, and it is desirable that the entire Al bonding wire or Al bonding ribbon is included in the direction perpendicular to the central axis of the Al bonding wire or Al bonding ribbon. However, if the size is large and it is difficult to measure the entire Al bonding wire or Al bonding ribbon, it can be adjusted to a range of less than 600 μm.

[0066] In addition to the above, there are several other methods for measuring the average diameter of the Si phase, including binarization processing from an observed image of the L cross section. However, in the present invention, it is preferable to use the method of combining the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD, as described above, for reasons such as the fact that a number of measurement functions are provided and multiple characteristics such as the average diameter of the Si phase and the orientation ratio of the crystal orientation of the Al phase, which will be described later, can be obtained in a single measurement, automatic analysis is possible, and measurement is easy using widely used equipment and analysis techniques.

[0067] -Crystal orientation of the Al phase in the L cross section- When the crystal orientation of the Al bonding wire or Al bonding ribbon of the present invention is measured in its L cross section, the orientation ratio of the <100> crystal orientation, which has an angle difference of 15° or less with respect to the direction parallel to the central axis (RD direction) (hereinafter also referred to as the "orientation ratio of the <100> crystal orientation of the Al phase in the RD direction") is preferably 15% or more and 50% or less. When the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is within the above range, better initial bonding strength (first bonding strength) of the first bonded portion can be achieved. This is thought to be because when ultrasonic vibration is applied in the RD direction and the Al bonding wire or Al bonding ribbon is deformed, the <100> crystal orientation, which has low deformation resistance, is oriented in the RD direction, promoting deformation of the bonding interface and metal bonding.

[0068] That is, when the Si content in the depth direction from the surface is measured by XPS, the ratio Ca / Cb of the average Si concentration Ca in a region a from 5 nm to 50 nm deep from the surface to the average Si concentration Cb in a region b from 800 nm to 1200 nm deep from the surface is in the range of 0.03 to 0.5. In addition to satisfying the above-mentioned characteristics, an even better first bond strength can be achieved by having an orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L cross section in the range of 15% to 50%. The effect of controlling the bond interface by the gradient of the Si concentration in the region from the surface to a certain depth and the effect of the orientation of the <100> crystal orientation of the Al phase in the RD direction are obtained synergistically, which further enhances the effect of improving the first bond strength, and as a result, can contribute to improving temperature cycle reliability in high-temperature temperature cycle tests.

[0069] From the viewpoint of realizing even better first bond strength, the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L cross section of the Al bonding wire or Al bonding ribbon of the present invention is more preferably 20% or more, even more preferably 22% or more, 24% or more, 26% or more, or 28% or more, and even more preferably 30% or more, or 35% or more. From the viewpoint of realizing even better first bond strength, the upper limit of the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is more preferably 48% or less, even more preferably 45% or less, even more preferably 42% or less, and even more preferably 40% or less.

[0070] A method for measuring the orientation ratio of the Al phase crystal orientation in the L-section of an Al bonding wire or Al bonding ribbon is described below. The orientation ratio of the Al phase crystal orientation in the L-section can be measured using a SEM-EDS-EBSD device, similar to the measurement of the average diameter of the Si phase described above. Specifically, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. More detailed procedures can be similar to those described above in relation to the measurement of the average diameter of the Si phase. That is, for the region identified as Al phase, the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction can be calculated using analysis software provided with the device. To calculate the orientation ratio, a partial ratio is used, calculated as a population of the area of ​​only the crystal orientations that could be identified based on a certain reliability within the measurement area. The area ratio of the <100> crystal orientation in the RD direction with respect to the crystal orientation of the Al phase was defined as the orientation ratio of the <100> crystal orientation in the RD direction. Therefore, in one embodiment, the orientation ratio of the crystal orientation of the Al phase in the L-section of the Al bonding wire or Al bonding ribbon of the present invention is calculated by the following steps (1) to (3). (1) In a measurement area where the L-section of the Al bonding wire or Al bonding ribbon is used as the inspection surface, Al and Si concentration measurements are performed using EDS and crystal orientation measurements are performed using EBSD simultaneously. (2) Al and Si are separated and extracted using the Chi Scan function. Specifically, by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results, Al and Si can be separated and identified. The crystal orientation can be analyzed using the Al and Si crystal information in the material file. (3) For the area identified as the Al phase, the crystal orientation is analyzed and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is calculated.

[0071] When measuring the orientation ratio of the crystal orientation of the Al phase in the L cross section, the setting range of the tolerance in the procedure (2) above, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by the EBSD method are the same as those described above for the measurement of the average diameter of the Si phase.

[0072] -Addition of Sr, Na, P, B- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Sr, Na, P, and B (hereinafter also referred to as the "first element group"). The total concentration of the first element group may be 0 ppm by mass, preferably 1 ppm by mass or more, more preferably 3 ppm by mass or more, even more preferably 5 ppm by mass or more, and particularly preferably 8 ppm by mass or more or 10 ppm by mass or more. The upper limit of the total concentration of the first element group is preferably 10,000 ppm by mass or less or 8,000 ppm by mass or less, more preferably 5,000 ppm by mass or less or 3,000 ppm by mass or less, even more preferably 2,000 ppm by mass or less or 1,000 ppm by mass or less, and particularly preferably 900 ppm by mass or less or 800 ppm by mass or less. In one embodiment, the total concentration of the first element group is preferably 10 ppm by mass or more and 800 ppm by mass or less.

[0073] By further containing at least one of Sr, Na, P, and B in a total amount of 10 mass ppm to 800 mass ppm, the frequency of wire breakage during wiredrawing of the Al bonding wire or Al bonding ribbon can be reduced. Al alloys containing a high concentration of Si of 3.0 mass% to 20.0 mass% tend to have a higher frequency of wire breakage during wiredrawing. This is thought to be due in part to the fact that particles of the Si phase crystallized during solidification cause stress concentration during wiredrawing, inducing wire breakage. It is believed that the addition of the first element group can uniformly distribute the particulate Si phase and inhibit the growth and coarsening of the Si phase, thereby alleviating stress concentration during wiredrawing and reducing wire breakage.

[0074] From the viewpoint of reducing the frequency of wire breakage during wire drawing, the total concentration of the first element group in the Al bonding wire or Al bonding ribbon of the present invention is more preferably 20 ppm by mass or more, even more preferably 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more, and the upper limit is preferably 750 ppm by mass or less, more preferably 740 ppm by mass or less, 720 ppm by mass or less, or 700 ppm by mass or less, even more preferably 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, or 600 ppm by mass or less, particularly preferably 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0075] When the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the first element group, it may contain one element from the first element group, two elements from the first element group, three elements from the first element group, or all four elements from the first element group. Also, when the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the first element group, it may contain Sr, Na, P, or B.

[0076] When the Al bonding wire or Al bonding ribbon of the present invention contains Sr from the first element group, the Sr concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. In addition, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the Sr concentration is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the Sr concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the Sr concentration is more preferably 800 ppm by mass or less, even more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0077] When the Al bonding wire or Al bonding ribbon of the present invention contains Na in the first element group, the Na concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the Na concentration is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the Na concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the Na concentration is more preferably 800 ppm by mass or less, even more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0078] When the Al bonding wire or Al bonding ribbon of the present invention contains P from the first element group, the P concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the P concentration is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the P concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the P concentration is more preferably 800 ppm by mass or less, even more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0079] When the Al bonding wire or Al bonding ribbon of the present invention contains B from the first element group, the concentration of B may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of B is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the B concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the concentration of B is more preferably 800 ppm by mass or less, still more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0080] -Addition of Ni, Ti, Fe, Zn, Mg- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Ni, Ti, Fe, Zn, and Mg (hereinafter also referred to as the "second element group"). The total concentration of the second element group may be 0 mass ppm, preferably 1 mass ppm or more or 3 mass ppm or more, more preferably 5 mass ppm or more or 8 mass ppm or more, even more preferably 10 mass ppm or more or 30 mass ppm or more, particularly preferably 50 mass ppm or more, 80 mass ppm or more, or 100 mass ppm or more. The upper limit of the total concentration of the second element group is preferably 10,000 mass ppm or less, more preferably 8,000 mass ppm or less, even more preferably 5,000 mass ppm or less, particularly preferably 3,000 mass ppm or less or 2,000 mass ppm or less. In one embodiment, the total concentration of the second element group is preferably 100 ppm by mass or more and 2000 ppm by mass or less.

[0081] The Al bonding wire or Al bonding ribbon of the present invention further contains one or more of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 mass ppm to 2000 mass ppm, thereby suppressing scratches and abrasion on the surface of the Al bonding wire or Al bonding ribbon and forming a smooth surface. Al alloys containing Si at a high concentration of 3.0 mass% to 20.0 mass% may harden the surface and cause Si phases and Al oxides present on the surface to fall off, resulting in scratches and abrasion on the surface during wiredrawing, resulting in an Al bonding wire or Al bonding ribbon with large surface irregularities. It is presumed that the addition of the second element group stabilizes the Al oxide on the surface of the Al bonding wire or Al bonding ribbon, refines the structure of the Al crystal grains, and hardens them, thereby reducing scratches and abrasion during wiredrawing. By providing a predetermined gradient in the Si concentration in the region from the surface to a certain depth and adding the second element group, it is believed that the occurrence of scratches and abrasions on the surface of the Al bonding wire or Al bonding ribbon can be suppressed, thereby enhancing the effect of forming a smooth surface.

[0082] From the viewpoint of forming an Al bonding wire or Al bonding ribbon having a smooth surface by suppressing the occurrence of scratches and abrasions on the surface, the total concentration of the second element group in the Al bonding wire or Al bonding ribbon of the present invention is more preferably 150 mass ppm or more, even more preferably 200 mass ppm or more, 250 mass ppm or more, or 300 mass ppm or more, and the upper limit is preferably 1800 mass ppm or less, more preferably 1600 mass ppm or less, 1500 mass ppm or less, or 1200 mass ppm or less, even more preferably 1000 mass ppm or less, 900 mass ppm or less, or 800 mass ppm or less, and particularly preferably 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0083] When the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the second element group, it may contain one element from the second element group, two elements from the second element group, three elements from the second element group, four elements from the second element group, or all five elements from the second element group. Also, when the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the second element group, it may contain Ni, Ti, Fe, Zn, or Mg.

[0084] When the Al bonding wire or Al bonding ribbon of the present invention contains Ni from the second element group, the Ni concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. In addition, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Ni concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Mn concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Ni concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0085] When the Al bonding wire or Al bonding ribbon of the present invention contains Ti from the second element group, the Ti concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. In addition, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Ti concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Ti concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Ti concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0086] When the Al bonding wire or Al bonding ribbon of the present invention contains Fe from the second element group, the Fe concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasion on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Fe concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Fe concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Fe concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0087] When the Al bonding wire or Al bonding ribbon of the present invention contains Zn from the second element group, the Zn concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. In addition, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Zn concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Zn concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Zn concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0088] When the Al bonding wire or Al bonding ribbon of the present invention contains Mg from the second element group, the Mg concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasion on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Mg concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Mg concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Mg concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0089] As the aluminum raw material for manufacturing the Al bonding wire or Al bonding ribbon of the present invention, it is preferable to use Al with a purity of 4N (Al: 99.99% by mass or more), and it is more preferable to use Al with a lower impurity content of 5N (Al: 99.999% by mass or more). In one embodiment, Al with a purity of 3N (Al: 99.9% by mass or more) may be used.

[0090] The Al bonding wire or Al bonding ribbon of the present invention may further contain elements other than Al, Si, the first element group, and the second element group (hereinafter also referred to as "other elements"). That is, "other elements" are elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn, and Mg, and the Al bonding wire or Al bonding ribbon of the present invention may further contain elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn, and Mg. The total concentration of other elements in the Al bonding wire or Al bonding ribbon is not particularly limited as long as it does not impair the effects of the present invention. The total concentration of the other elements may be, for example, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.15% by mass or less, 0.1% by mass or less, 0.08% by mass or less, 0.06% by mass or less, 0.05% by mass or less, 0.04% by mass or less, 0.03% by mass or less, 0.025% by mass or less, 0.02% by mass or less, 0.018% by mass or less, 0.016% by mass or less, 0.015% by mass or less, 0.014% by mass or less, 0.012% by mass or less, or 0.01% by mass or less. The lower limit of the total concentration of the other elements is not particularly limited, and may be 0% by mass.

[0091] In one embodiment, the remainder of the Al bonding wire or Al bonding ribbon of the present invention consists of Al and other elements. Therefore, in a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, and other elements. In another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, and other elements. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the second element group, and other elements. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and other elements.

[0092] In one embodiment, the remainder of the Al bonding wire or Al bonding ribbon of the present invention consists of Al and inevitable impurities. Therefore, in a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, and inevitable impurities. In another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, and inevitable impurities. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the second element group, and inevitable impurities. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and inevitable impurities.

[0093] In a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention does not have a coating mainly composed of a metal other than Al on the outer periphery of the Al bonding wire or Al bonding ribbon. Here, the term "coating mainly composed of a metal other than Al" refers to a coating in which the content of a metal other than Al is 50 mass % or more.

[0094] The Al bonding wire or Al bonding ribbon of the present invention may be an Al bonding wire or an Al bonding ribbon. When the present invention is an Al bonding wire, its wire diameter is not particularly limited and may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 150 μm or more, 180 μm or more, or 200 μm or more. The upper limit of the wire diameter is not particularly limited and may be, for example, 600 μm or less, 550 μm or less, 500 μm or less, 450 μm or less, or 400 μm or less. In one embodiment, the wire diameter of the Al bonding wire of the present invention may be in the range of 100 to 600 μm, preferably 200 to 400 μm. When the present invention is an Al bonding ribbon, the dimensions of its rectangular or approximately rectangular cross section (width W x thickness T) are not particularly limited, and for example, W may be 100 to 3000 μm and T may be 50 to 600 μm.

[0095] The Al bonding wire or Al bonding ribbon of the present invention can provide excellent temperature cycle reliability even in high-temperature temperature cycle tests. Therefore, the Al bonding wire or Al bonding ribbon of the present invention can be suitably used as an Al bonding wire or Al bonding ribbon for semiconductor devices. The Al bonding wire or Al bonding ribbon of the present invention can be particularly suitably used as an Al bonding wire or Al bonding ribbon for power semiconductor devices, and more suitably used as an Al bonding wire or Al bonding ribbon for next-generation power semiconductor devices such as SiC power semiconductor devices.

[0096] -Method for manufacturing Al bonding wire or Al bonding ribbon- An example of a method for manufacturing an Al bonding wire or Al bonding ribbon of the present invention will be described below. Hereinafter, an example will be described in relation to the manufacture of an Al bonding wire.

[0097] The Al and alloying elements used as raw materials preferably have a high purity. Al preferably has a purity of 99.5% by mass or more, with the remainder consisting of inevitable impurities, more preferably a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and even more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Si, first element group, second element group, and other elements used as alloying elements preferably have a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for Al bonding wire can be produced by loading the Al raw material and the alloying element raw material into a graphite or alumina crucible processed to obtain a cylindrical ingot and melting it using an electric furnace or high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm, taking into account the workability in the subsequent processing steps. The atmosphere in the furnace during melting is preferably an inert atmosphere or a reducing atmosphere to prevent excessive oxidation of Al, Si, the first element group, the second element group, and other elements that constitute the wire. The maximum temperature that the molten metal reaches during melting is preferably in the range of 700°C or higher and lower than 1050°C, taking into consideration factors such as ensuring the fluidity of the molten metal and making it easier to control the size of the Si phase during solidification. Cooling methods that can be used during solidification include water cooling, furnace cooling, and air cooling.

[0098] The cylindrical ingot obtained by melting is subjected to a solution treatment in which it is heated at a high temperature, and then repeatedly subjected to wire drawing using a die to produce a wire of the desired wire diameter. The wire after wire drawing can be used as an Al bonding wire by performing a final heat treatment using an electric furnace.

[0099] <Control of Si concentration gradient> In order to control the gradient of Si concentration in the region from the surface to a certain depth, it is effective to control the wire feed speed (wiredrawing speed) in the wiredrawing process, the die area reduction rate, the lubricity at the contact interface between the wire and the die, and the atmosphere of the intermediate heat treatment. An example of manufacturing conditions for providing a predetermined gradient in the Si concentration in the depth direction in the region from the surface to a certain depth (i.e., for controlling the above ratio Ca / Cb to be in the range of 0.03 to 0.5) is shown below.

[0100] -Wire feed speed- Controlling the wire feed speed to a high speed according to the wire diameter used for wire drawing to assist deformation of the surface region is effective in promoting the concentration gradient. As a specific example, it is preferable to set the average wire drawing speed during wire drawing in the range from half the wire diameter at the start of wire drawing to the final wire diameter to be 20 m / min or more and less than 50 m / min.

[0101] - Die area reduction rate - Regarding the die area reduction rate in wire drawing, drawing a large diameter wire at a high area reduction rate and a small diameter wire at a low area reduction rate is effective in controlling the concentration gradient. As a specific example, it is preferable that the die area reduction rate from the wire diameter at the start of wire drawing to half of that diameter be in the range of 20% or more and less than 40%, and that from half the wire diameter to the final wire diameter be in the range of 10% or more and less than 25%. Here, if the wire area reduction rate per die is P1, P1 is expressed by the following formula. P1={(R ２ ２ -R １ ２ ) / R ２ ２}×100 where R ２ is the diameter of the wire before processing (mm), R １ represents the diameter (mm) of the wire after processing.

[0102] - Lubricity - By improving the lubricity at the contact interface between the wire and the die during wiredrawing and promoting deformation that elongates the surface in the wiredrawing direction, it is possible to assist the concentration gradient in the surface region. The lubricating liquid used in wiredrawing is preferably a water-based liquid containing a surfactant that reduces the coefficient of friction.

[0103] - Atmosphere of intermediate heat treatment - Adjusting the atmosphere of intermediate heat treatment is also effective in controlling the concentration gradient in the surface region. Intermediate heat treatment is a heat treatment carried out in the middle of the process of drawing wire from an ingot to the final wire diameter. ２ It is preferable to perform the drawing in an atmosphere of an inert gas such as a nitrogen gas, which can help prevent oxidation of Si in the Al during the wire drawing process and maintain a low concentration of Si near the surface.

[0104] <Control of the Average Diameter of the Si Phase> To adjust the average diameter of the Si phase in the L-section to a range of 0.8 μm or more and 4 μm or less, it is effective to adjust the melting temperature during ingot production to a range of 800°C or more and less than 1050°C, adjust the casting temperature to a range of 700°C or more and less than 780°C, and control the solution treatment temperature to a range of 450°C or more and less than 550°C and the solution treatment time to a range of 1 hour or more and less than 6 hours. The casting temperature is the temperature at which the molten liquid is cast into a mold or the like, and corresponds to the solidification start temperature. If the casting temperature is high, the Si phase crystallized during solidification tends to coarsen and become columnar, and the average diameter of the Si phase tends to increase. If the solution treatment temperature is high, the columnar Si phase tends to break down and become granular, thereby decreasing the average diameter of the Si phase. To further reduce the average diameter of the Si phase, it is effective to increase the cooling rate during solidification, and for example, water cooling is also effective.

[0105] <Controlling the Orientation Ratio of the <100> Crystal Orientation of the Al Phase in the RD Direction> Adjusting the conditions of the intermediate heat treatment is effective for adjusting the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L cross section to a range of 15% to 50%. A temperature range of 250°C to less than 400°C and a time range of 1 hour to less than 48 hours is effective. The number of intermediate heat treatments is preferably between two and four. It is preferable to perform intermediate heat treatment at least once in a range of 4.0 to 5.5 times the final wire diameter, and at least once in a wire diameter range of 2.0 to 3.5 times the final wire diameter. Performing intermediate heat treatment under these conditions reduces the processing strain of the Al phase and causes slight recrystallization, thereby reducing the processed structure of the Al phase at the final wire diameter and increasing the progress of recrystallization of the Al phase in subsequent heat treatments. It also promotes the rotation of the crystal orientation, making it easier to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction. On the other hand, if the intermediate heat treatment temperature is set to less than 250° C. or 400° C. or higher, there is a concern that the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction may become unstable.

[0106] Regarding the final heat treatment conditions, it is effective to adjust the temperature range to 200°C or higher and lower than 360°C, and the time range to 2 hours or higher and lower than 24 hours. The final heat treatment promotes recovery and recrystallization of the Al phase, and at the same time, the amount of Si dissolved in the Al phase changes depending on the heat treatment temperature, which changes the recrystallization temperature. Adjusting the progress of recrystallization by the final heat treatment makes it easy to control the orientation of the crystal orientation.

[0107] As mentioned above, the above is a typical example of the manufacturing of Al bonding wire, which is a wire material. The same procedure can also be used to manufacture Al bonding ribbon, which is a strip material. The temperature and time of the heat treatment can be approximately the same as those described above. Furthermore, when manufacturing Al bonding ribbon by rolling, the die area reduction rate can be adjusted by replacing it with the rolling reduction rate.

[0108] [Semiconductor Device] A semiconductor device can be manufactured by connecting electrodes on a semiconductor chip to external electrodes on a lead frame or substrate using the Al bonding wire or Al bonding ribbon of the present invention. That is, the semiconductor device of the present invention includes the Al bonding wire or Al bonding ribbon of the present invention. As mentioned above, wedge bonding is used for both the first bonding with the electrode on the semiconductor chip and the second bonding with the electrode on the lead frame or substrate.

[0109] In one embodiment, the semiconductor device of the present invention comprises a circuit board, a semiconductor chip, and an Al bonding wire or Al bonding ribbon for electrically connecting the circuit board and the semiconductor chip, and is characterized in that the Al bonding wire or Al bonding ribbon is the Al bonding wire or Al bonding ribbon of the present invention.

[0110] In the semiconductor device of the present invention, the circuit board and semiconductor chip are not particularly limited, and known circuit boards and semiconductor chips that can be used to configure a semiconductor device may be used. Alternatively, a lead frame may be used instead of the circuit board. For example, a semiconductor device may be configured including a lead frame and a semiconductor chip mounted on the lead frame, as in the semiconductor device described in JP 2020-150116 A.

[0111] Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, air conditioners, solar power generation systems, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.), and among these, power semiconductor devices are preferred.

[0112] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the examples shown below.

[0113] [Sample] The sample preparation method will be described. The raw material Al had a purity of 4N (99.99% by mass or more), with the remainder consisting of inevitable impurities. The alloying elements Si, the first element group (Sr, Na, P, B), the second element group (Ni, Ti, Fe, Zn, Mg), and other elements had a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for the Al bonding wire or Al bonding ribbon was produced by loading the Al raw material and the alloying element raw materials into an alumina crucible and melting them using a high-frequency heating furnace. The atmosphere in the furnace during melting was an Ar atmosphere, the maximum temperature of the molten metal during melting was 700°C or higher and lower than 1050°C, and the casting temperature was in the range of 700°C or higher and lower than 780°C. The cooling method during solidification was air cooling (cooling in air) or water cooling (cooling in water).

[0114] A cylindrical ingot with a diameter of 6 mm was obtained by melting, and the ingot was subjected to solution treatment and homogenization treatment. After that, wire drawing using a die and intermediate heat treatment were performed to produce an Al bonding wire with a diameter of 300 μm. Furthermore, using the Al bonding wire with a diameter of 300 μm as a starting material, an Al bonding ribbon with a thickness of 100 μm and a width of 600 μm was produced by two-stage rolling. The temperature range of the solution treatment was 450 ° C or higher and lower than 550 ° C, and the time was 1 hour or higher and lower than 6 hours. After the solution treatment, a homogenization treatment was performed continuously during cooling. The cooling method after the homogenization treatment was air cooling in the atmosphere.

[0115] The number of intermediate heat treatments ranged from two to four. The intermediate heat treatments were carried out at least once in the range of 4.0 to 5.5 times the final wire diameter, and at least once in the range of 2.0 to 3.5 times the final wire diameter. The temperature range of the intermediate heat treatments was 250°C or higher and lower than 400°C, and the time period was 1 hour or higher and lower than 48 hours. The intermediate heat treatments were carried out in N ２ The reaction was carried out under a gas atmosphere.

[0116] A commercially available lubricant (a water-based lubricant containing a surfactant to reduce the coefficient of friction) was used during wire drawing. The wire area reduction rate per die during wire drawing was in the range of 20% to less than 40% from the start of wire drawing to a wire diameter of 3 mm, and in the range of 10% to less than 25% from a wire diameter of 3 mm to the final wire diameter. The wire feed speed during wire drawing was in the range of 20 m / min to less than 50 m / min on average from a wire diameter of 3 mm to the final wire diameter.

[0117] The temperature range of the final heat treatment was 200° C. or more and less than 360° C., and the time period was 2 hours or more and less than 24 hours.

[0118] <Method for Measuring Si Concentration by X-ray Photoelectron Spectroscopy (XPS)> (1) Preparation of Measurement Sample The Al bonding wire or Al bonding ribbon sample to be measured was placed on the sample stage. At that time, the position of the Al bonding wire or Al bonding ribbon sample was adjusted so that the longitudinal direction was the horizontal direction on the operation screen of the XPS device. When the sample was an Al bonding ribbon (having a rectangular cross-sectional shape with a width W of 600 μm and a thickness T of 100 μm), it was placed so that the width W direction was parallel to the surface of the sample stage and the thickness T direction was perpendicular to the surface of the sample stage.

[0119] (2) Measurement by XPS In the XPS measurement, the measurement area was selected so that the vicinity of the apex of the Al bonding wire or Al bonding ribbon sample was the measurement area while looking at the screen of the SXI (Scanning X-ray Image) of the device. Then, measurements were performed in the depth direction from the surface of the Al bonding wire sample using XPS under the following conditions, and the Si2p and Al2p spectra were detected. The peak positions of the Si2p and Al2p spectra were detected at energy positions of approximately 98.5 to 99.5 eV and 71.5 to 73.0 eV, respectively. - Measurement device: Versa Probe 3 manufactured by ULVAC-PHI - Ultimate vacuum: approximately 1 x 10 －８Torr X-ray source: Monochromated Al (1486.6 eV) Measurement area: 100 μm (longitudinal direction of sample) × 20 μm (circumferential direction of sample) square Photoelectron take-off angle: 45 degrees Detection depth: several nm Ar sputtering Acceleration voltage: 2 kV Sputtering area: 2 × 2 mm square Sputtering rate: 9.2 nm / min (SiO ２ Analysis pitch in the depth direction: 5 nm pitch (depth from the surface in the range of 0 to 50 nm), 10 nm pitch (depth from the surface in the range of 50 to 200 nm), 20 nm pitch (depth from the surface in the range of more than 200 nm)

[0120] (3) Quantitative Analysis of Si and Al Elements Based on the Si2p and Al2p detection spectra acquired at each depth position in the depth direction from the surface of the sample, quantitative analysis of Si and Al elements was performed using the following procedure. Specifically, quantitative analysis of Si element was performed in the energy range (approximately 95.0 to 101.0 eV) that includes the peak of Si2p with a valence of Si0 (metallic Si). The energy values ​​of the low-energy end and high-energy end were adjusted within the above quantitative range depending on the shape of the peak. The background of the quantitative analysis range was determined using the Shirley method, and Si element was quantified using the peak area after subtracting the background. Quantitative analysis of Al element was performed using the same procedure as the quantitative analysis of Si element described above in the energy range (approximately 69.0 to 79.0 eV) that includes the peak of Al2p with a valence of Al0 (metallic Al).

[0121] (4) Calculation of Si Concentration Using the quantitative values ​​of Si and Al at each depth position from the surface of the sample in the depth direction and the relative sensitivity coefficients of each element set in the XPS device, the Si concentration was calculated when the total of metal Si and metal Al at each depth position from the surface of the sample in the depth direction was taken as 100 atomic %. The arithmetic mean value of the Si concentration in region a, which is 5 nm to 50 nm deep from the surface, was determined as average concentration Ca, the arithmetic mean value of the Si concentration in region b, which is 800 nm to 1200 nm deep from the surface, was determined as average concentration Cb, and the arithmetic mean value of the Si concentration in region f, which is 5 nm to 30 nm deep from the surface, was determined as average concentration Cf.

[0122] The Si concentration was measured using two samples randomly selected from multiple samples taken from the Al bonding wire or Al bonding ribbon at intervals of 50 cm or more along the central axis of the wire or ribbon. The average concentrations Ca, Cb, and Cf were calculated as the averages (arithmetic means) of the values ​​obtained for the two samples using the procedures (1) to (4) above.

[0123] <Method for measuring element content> The concentration analysis of elements contained in the Al bonding wire or Al bonding ribbon was carried out using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) ("PS3520UVDDII" manufactured by Hitachi High-Tech Science Corporation) or an ICP-MS (Inductively Coupled Plasma-Mass Spectrometer) ("Agilent 7700x ICP-MS" manufactured by Agilent Technologies, Inc.) as an analytical device. By such measurement, the concentration (ppm by mass) of each element in the entire Al bonding wire or Al bonding ribbon was determined.

[0124] <Method for measuring the orientation ratio of the crystal orientation of the Al phase> The L cross section (cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon was used as the inspection surface, and the crystal orientation of the Al phase was measured.

[0125] For the measurements, an FE-SEM (SU-70 manufactured by Hitachi High-Technologies Corporation) was used, and the analysis software used was APEX (for data collection), OIM Data Collection (for Chi Scan), and OIM Analysis (for data analysis) manufactured by TSL Solutions. Three measurement areas were randomly selected at intervals of 50 cm or more relative to the central axis of the Al bonding wire or Al bonding ribbon, and measurements were performed on the three areas. The measurement area was determined so that it was 300 μm or more and less than 800 μm in the central axis direction of the Al bonding wire or Al bonding ribbon, and the entire Al bonding wire or Al bonding ribbon was included in the direction perpendicular to the central axis. The main conditions for the EDS and EBSD measurements were an acceleration voltage of 15 kV, a measurement magnification of 350x, a scan speed of 30 to 120 points / second, and a measurement interval in the range of 0.1 to 0.3 μm. Here, if the scanning speed is fast, the measurement time can be shortened, but there is a concern that the measurement accuracy of the EDS may decrease. It is desirable to select an appropriate scanning speed within the above range.

[0126] A SEM-EDS-EBSD device was used to measure the orientation ratio of the Al phase crystal orientation in the L-section of the Al bonding wire or Al bonding ribbon. This method combined the Al concentration and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD. More specifically, the measurements were performed according to the following procedures (1) to (3). (1) In the measurement area where the L-section of the Al bonding wire or Al bonding ribbon was used as the inspection surface, Al and Si concentration measurements were performed using EDS and crystal orientation measurements were performed using EBSD simultaneously. (2) Al and Si were separated and extracted using the Chi Scan function, a function of the EBSD analysis software. Specifically, Al and Si were separated and identified by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results. The Al and Si crystal information in the material file was used for crystal orientation analysis. Here, the tolerance condition was mainly set to 30% and adjusted as necessary. (3) The crystal orientation of the region identified as Al phase was analyzed, and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction was calculated. The crystal orientations to be investigated were at least three types: <111>, <110>, and <100>, which are typical crystal orientations of Al metal, and, if necessary, a crystal orientation with a high ratio was selected. Here, the orientation ratio of the crystal orientations was calculated using the partial ratio.

[0127] The orientation ratio of the <100> crystal orientation of the Al phase in the RD direction was determined as the average value (arithmetic mean) of the values ​​obtained for the three measurement regions by the above steps (1) to (3).

[0128] <Method for Measuring the Average Diameter of Si Phase> To measure the average diameter of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the crystal orientation of the Al phase. The method combined the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD. Specifically, after performing the above procedures (1) and (2), the measurement was performed according to the following procedure (3). (3) For the region identified as the Si phase, the crystal orientation was analyzed, and if the orientation difference between the measurement points was 15° or more, it was determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain was calculated. The circle-equivalent diameters of each crystal grain were then averaged to calculate the average diameter of the Si phase. Here, the average calculated by area average (area-weighted average) was used in the average calculation. Furthermore, when calculating the average diameter of the Si phase in the L-section, only Si phases with a diameter (circle-equivalent diameter) of 0.5 μm or more were considered.

[0129] The average diameter of the Si phase was determined as the average (arithmetic mean) of the values ​​obtained for the three measurement regions according to the above procedures (1) to (3).

[0130] [Method for evaluating Al bonding wire or Al bonding ribbon] The evaluation method for Al bonding wire will be described. The wire diameter of the Al bonding wire used for evaluation was Φ300 μm. The semiconductor chip used was made of Si, and the electrodes on the semiconductor chip were made of a 4 μm thick film of an alloy with a composition of Al-0.5% Cu. The substrate used was an Al alloy with a 5 μm thick film of Ni. A commercially available wire bonder (manufactured by Ultrasonic Industries Co., Ltd.) was used to bond the Al bonding wire, and wedge bonding was used for both the first bonding (bonding to the electrode on the semiconductor chip) and the second bonding (bonding to the substrate). The Al bonding ribbon was bonded using a Hesse fully automatic bonder "BJ955" equipped with a ribbon bond head.

[0131] <Method for Evaluating High-Temperature Cycle Reliability> A commercially available thermal shock tester was used for the high-temperature temperature cycle test (high-temperature TCT). In the high-temperature TCT, the sample chamber was moved between a low-temperature chamber and a high-temperature chamber, repeatedly increasing and decreasing the temperature. The low-temperature chamber temperature was set to -40°C, and the high-temperature chamber temperature was set to 185°C. One cycle consisted of the sample chamber being placed in the high-temperature chamber, moving to the low-temperature chamber, and then returning to the high-temperature chamber. The sample chamber spent 20 minutes in each of the low-temperature and high-temperature chambers. The samples used for the high-temperature TCT had a structure in which a semiconductor chip was mounted on a substrate, and the electrodes on the semiconductor chip and the electrodes on the substrate were connected with Al bonding wire or Al bonding ribbon. After 1000 cycles, the samples were removed and subjected to a shear test on the first bond. The shear strength value of the first bond used to evaluate the temperature cycle reliability was the average shear strength of five randomly selected first bond locations. Evaluation was based on the strength ratio (F2 / F1) of the shear strength value F2 after the temperature cycle test to the shear strength value F1 before the temperature cycle test. A strength ratio of less than 50% was judged to be problematic in practical use and rated "0", a strength ratio of 50% or more but less than 70% was judged to require improvement and rated "1", a strength ratio of 70% or more but less than 75% was judged to be excellent and rated "2", and a strength ratio of 75% or more was judged to be particularly excellent and rated "3". "0" and "1" are failures, and "2" and "3" are passes. The evaluation results are shown in the "High-temperature temperature cycle reliability" column in the table.

[0132] <Evaluation of High-Temperature Cycle Reliability (After 1300 Cycles)> After 1300 cycles of the high-temperature TCT, samples were removed and subjected to a shear test on the first bond. The shear strength value of the first bond used to evaluate the temperature cycle reliability was calculated by averaging the shear strength values ​​of five randomly selected first bond locations. The shear strength value F2 after the high-temperature TCT (1300 cycles) to the shear strength value F1 before the high-temperature TCT (F2 / F1) was used for evaluation. A strength ratio of less than 50% was judged to be problematic for practical use and rated "0." A strength ratio of 50% to less than 60% was judged to be acceptable for practical use and rated "1." A strength ratio of 60% to less than 70% was judged to be excellent and rated "2." A strength ratio of 70% or greater was judged to be particularly excellent and rated "3." A "0" indicates failure, and "1," "2," and "3" indicate passing. The evaluation results are listed in the "High-Temperature Cycle Reliability (After 1300 Cycles)" column in the table.

[0133] <Method for Evaluating First Bond Strength> The method for evaluating the first bond strength will be described. The first bond strength was evaluated by a shear strength test. First bonding was performed at 10 locations under bonding conditions suitable for the reliability test, and the shear strength (shear strength) of the first bonded portion was measured. Under these bonding conditions, the ultrasonic output was set slightly higher to ensure a sufficient bonding area. A commercially available microshear strength tester (Nordson 4000-PLUS) was used to measure the shear strength. The shear rate was 200 μm / sec, and the height of the shear tool was 10 μm from the electrode surface. The shear strength was measured by fixing the substrate to which the Al bonding wire or Al bonding ribbon was bonded using a jig. If the average shear strength of the 10 first joints was 1500 gf or more, it was judged to be excellent and rated as "3", if it was 1300 gf or more but less than 1500 gf, it was judged to have no practical problem and rated as "2", if it was 1000 gf or more but less than 1300 gf, it was judged to need improvement and rated as "1", and if it was less than 1000 gf, it was judged to have a practical problem and rated as "0". The evaluation results are shown in the "1st joint strength" column in the table.

[0134] <Method for Evaluating Wire Breakage During Processing> The method for evaluating wire breakage during processing will be described below. Wire drawing was performed from a wire diameter of 6 mm to a wire diameter of 0.3 mm, and the number of wire breakages was confirmed. The wire drawing processing conditions, such as the feed rate and area reduction rate, were selected from the conditions described above, and the appropriate manufacturing conditions were adjusted and changed for each wire. The length of the drawn Al bonding wire ranged from 100 to 200 m, and the number of wire breakages was calculated by converting it to per 100 m. If the number of wire breakages was zero, it was judged to be good and rated "3." If it was one, it was judged that it could be addressed by improving the manufacturing conditions and rated "2." If it was two to four, it was judged that there was a decrease in productivity and rated "1." If it was five or more, it was judged that it was difficult to use in practice and rated "0." The evaluation results are shown in the "Wire Breakage During Processing" column in the table.

[0135] (Method for Evaluating Surface Scratches and Abrasions) The surface quality of the Al bonding wire or Al bonding ribbon was evaluated, focusing on scratches and abrasions. The wire diameter of the Al bonding wire was Φ300 μm. Three measurement areas were randomly selected for the Al bonding ribbon at intervals of 1 m or more along the central axis of the Al bonding wire, and three pieces of approximately 2 cm in length were taken from each of the three locations. A total of nine samples were observed. Specifically, the surface was observed using an SEM at magnifications ranging from 50 to 500 times. Scratches longer than 50 μm and abrasions longer than 30 μm were judged to be defective. The number of scratches and abrasions was counted, and a score of "3" was given for good and acceptable results; a score of "2" was given for one to two locations and no practical problems; a score of "1" was given for three to seven locations and poor surface quality; and a score of "0" was given for eight or more locations and difficult to use. The evaluation results are listed in the "Surface Quality" column in the table.

[0136] The evaluation results of the examples and comparative examples are shown in Tables 1 to 4. Examples 1 to 40 and comparative examples 1 to 7 in Tables 1 to 3 are results for Al bonding wires, and Examples B1 to B3 and comparative example B1 in Table 4 are results for Al bonding ribbons.

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[0140] Explanation of symbols

[0141] REFERENCE SIGNS LIST 1 Al bonding wire 10 Central axis 11 L-section 2 Al bonding ribbon 20 Central axis 21 L-section

Claims

1. An Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, wherein when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding wire or Al bonding ribbon is measured by X-ray photoelectron spectroscopy (XPS: X-ray photoelectron spectroscopy), the ratio Ca / Cb of the average concentration Ca of Si element in a region a having a depth from the surface of 5 nm or more and 50 nm or less to the average concentration Cb of Si element in a region b having a depth from the surface of 800 nm or more and 1200 nm or less is 0.03 or more and 0.5 or less.

2. An Al bonding wire or Al bonding ribbon as described in claim 1, wherein the average diameter of the Si phase in the L cross section (cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is 0.8 μm or more and 4 μm or less.

3. An Al bonding wire or Al bonding ribbon as described in claim 1 or 2, in which the average concentration Cf of Si elements in a region f having a depth from the surface of 5 nm or more to 30 nm or less is 0.1 atomic % or more and 4 atomic % or less.

4. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 3, wherein when the crystal orientation of the Al phase in an L-section (a section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <100> crystal orientation, which has an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction), is 15% or more and 50% or less.

5. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 4, further containing at least one of Sr, Na, P, and B in a total amount of 10 ppm by mass or more and 800 ppm by mass or less.

6. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 5, further containing at least one of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 ppm by mass or more and 2000 ppm by mass or less.

7. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 6, wherein the total concentration of elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn and Mg in the Al bonding wire or Al bonding ribbon is 0.5 mass% or less.

8. An Al bonding wire or Al bonding ribbon according to any one of claims 2 to 7, wherein the average diameter of the Si phase is a value measured using a SEM-EDS-EBSD device.

9. An Al bonding wire or Al bonding ribbon according to any one of claims 4 to 8, wherein the orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device.

10. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 9, which is for use in a semiconductor device.

11. A semiconductor device comprising an Al bonding wire or an Al bonding ribbon according to any one of claims 1 to 10.

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