Al bonding wire or Al bonding ribbon

Abstract

The present invention provides an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability in high-temperature temperature cycle tests, as well as good first bond strength, which are required for next-generation SiC power semiconductor devices. The Al bonding wire or Al bonding ribbon contains 3.0 mass % to 20.0 mass % 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 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.

Description

[Technical Field]

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

[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 mainly use bonding wires or bonding ribbons made of aluminum (Al). The wire diameter of Al bonding wires is mainly in the range of 100 μm to 600 μm, while the width of Al bonding ribbons is mainly in the range of 100 μm to 3000 μm and the thickness is mainly 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. 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: the first bonding with an electrode on a semiconductor chip, and the second bonding with an electrode on a lead frame or substrate, both of which use wedge joining. Wedge joining 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 joining method is characterized by connecting in a solid state without melting the connecting material, and is different from welding techniques, which 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 junction rises. On the other hand, when the current supply is stopped, the temperature of the first junction drops. Thus, the first junction repeatedly rises and falls in temperature during power semiconductor operation. This repeatedly applies thermal stress to the first junction 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 junction life (hereinafter also referred to as "temperature cycle reliability") associated with temperature rise and fall of the first junction.

[0006] In response to the demand for temperature cycle reliability, Al bonding wires have been proposed that focus on improving mechanical strength. Adding specific elements to Al has been proposed as a method for improving the mechanical properties of Al bonding wires.

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

[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 wire has a fine structure with an average crystal grain size of 6 to 12 μm. This patent document also 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 the mechanical strength is improved by rapidly cooling the molten Al-Si alloy to finely and uniformly disperse the Si. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-131010 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-129578 [Patent Document 3] Japanese Patent Application Publication No. 59-57440 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned 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 the linear thermal expansion coefficients of the two (and ultimately the linear thermal expansion difference 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 of the tests for accelerating the lifespan (temperature cycle reliability) of the 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 require temperature cycle reliability under even stricter conditions than currently available. For example, while Si power semiconductor devices are required to have temperature cycle reliability in a temperature range of -40°C to 150°C, SiC power semiconductor devices will be required to have temperature cycle reliability in a 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 high-power applications 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, expanding the linear thermal expansion difference at the bonded portion of the Al bonding wire or Al bonding ribbon, accelerating fatigue fracture, which becomes a problem.

[0014] Furthermore, bonding defects, such as peeling of the Al bonding wire or Al bonding ribbon from the electrode during bonding, can lead to product defects and reduced manufacturing yields, so it is necessary to achieve good bonding strength at each bond. In this regard, applying strong ultrasonic vibrations or loads to the first bonded portion to achieve good bonding strength can damage the semiconductor chip. In particular, when using Al bonding wire or Al bonding ribbon strengthened by the addition of Si or other additives, the hardness of the bonding wire or Al bonding ribbon makes it easy for the semiconductor chip to be damaged during the first bonded portion. 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"). This can lead to reduced or unstable temperature cycle reliability, hindering the practical use of Al bonding wire or Al bonding ribbon strengthened by the addition of Si or other additives.

[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. [Means for solving the problem]

[0016] As a result of intensive research into the above-mentioned problems, the inventors 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 finding, the inventors conducted further research and 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% 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 finding, the inventors conducted further research and discovered that the present invention can be solved by an Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% 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

[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, An Al bonding wire or Al bonding ribbon, 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 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. <2> 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. <1> The Al bonding wire or Al bonding ribbon according to claim 1. <3> The average concentration Cf of Si element in a region f having a depth from the surface of 5 nm to 30 nm is 0.1 atomic % to 4 atomic %. <1> or <2> The Al bonding wire or Al bonding ribbon according to claim 1. <4> When measuring the crystal orientation of the Al 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, the angle difference with respect to the direction parallel to the central axis (RD direction) is 15° or less. <100> The orientation ratio of the crystal orientation is 15% or more and 50% or less. <1> ~ <3> The Al bonding wire or Al bonding ribbon according to any one of the above. <5> Furthermore, it contains one or more of Sr, Na, P, and B in a total amount of 10 mass ppm or more and 800 mass ppm or less. <1> ~ <4> The Al bonding wire or Al bonding ribbon according to any one of the above. <6> Further, it contains one or more of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 mass ppm or more and 2000 mass ppm or less. <1> ~ <5> The Al bonding wire or Al bonding ribbon according to any one of the above. <7> 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. <1> ~ <6> The Al bonding wire or Al bonding ribbon according to any one of the above. <8> The average diameter of the Si phase is a value measured using a SEM-EDS-EBSD device. <2> ~ <7> The Al bonding wire or Al bonding ribbon according to any one of the above. <9> The orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device. <4> ~ <8> The Al bonding wire or Al bonding ribbon according to any one of the above. <10> for semiconductor device, <1> ~ <9> The Al bonding wire or Al bonding ribbon according to any one of the above. <11> <1> ~ <10> A semiconductor device comprising the Al bonding wire or Al bonding ribbon according to any one of the above. [Effects of the Invention]

[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 also exhibits good first bonding strength. [Brief explanation of the drawings]

[0019] [Figure 1] 1 shows an example of a Si concentration profile when the Si concentration in the depth direction of the 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 %. [Figure 2] Figure 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. Figure 2 is also a diagram for explaining the quantification of Si element based on the Si2p Si0 valence peak. [Figure 3] 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 of 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. [Figure 4] 4 is a schematic diagram illustrating the measurement surface (inspection surface) when measuring the crystal orientation of the Al phase and the average diameter of the Si phase in 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. DETAILED DESCRIPTION OF THE INVENTION

[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 is characterized in that 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 Ca of Si element in a region a from 5 nm to 50 nm deep from the surface to the average concentration Cb of Si element in a region b from 800 nm to 1200 nm deep from the surface is 0.03 or more and 0.5 or less.

[0022] As mentioned above, when an Al bonding wire or Al bonding ribbon made solely of high-purity Al is used in a temperature cycle test (hereinafter also referred to as a "TCT (Temperature Cycle Test)"), cracks propagate relatively rapidly within the Al bonding wire or Al bonding ribbon, resulting in a decrease in 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, thereby improving 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 severe test conditions, and further improvement in temperature cycle reliability is necessary.

[0023] High-temperature temperature cycle testing confirmed that defects were accelerated near the bonding interface during the initial stage of the first bonding of Al bonding wire or Al bonding ribbon. The bonding method for Al bonding wire or Al bonding ribbon is typically performed at room temperature, suppressing diffusion at the bonding interface, and the surface condition of the Al bonding wire or Al bonding ribbon has a strong impact on bondability. In high-temperature temperature cycle testing, the linear thermal expansion difference at the bonded portion increases due to the increased temperature difference during the temperature cycle, causing thermal strain to concentrate near the bonding interface from an early stage. This can accelerate crack propagation, which can lead to the surface condition of the Al bonding wire or Al bonding ribbon. Cracks at the bonding interface grow or propagate within the Al bonding wire or Al bonding ribbon, accelerating the deterioration of temperature cycle reliability.

[0024] The present inventors have found that modifying the surface of an Al bonding wire or Al bonding ribbon is effective in preventing crack propagation at the bonding interface, which is a factor in 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 impact 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 found that crack propagation near the bonding 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 bond can be solved and good first bond 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 bond strength is presumed to be as follows.

[0026] For Al bonding wire or Al bonding ribbon made of a high-concentration Al-Si alloy, a specific gradient in the Si concentration depth from the surface to a certain depth—i.e., a low Si concentration near the surface and a high Si concentration deep within—is established. This gradient in Si concentration, satisfying the above-mentioned Ca / Cb ratio, is believed to improve the surface deformability of the Al bonding wire or Al bonding ribbon when ultrasonic vibration or load is applied during bonding, promote the destruction of the surface oxide film, and facilitate the diffusion of Al atoms at the bonding interface, thereby resulting in increased bond strength, stabilized deformation, and even contribute to maintaining a strong bond at the bonding interface during temperature cycle testing. These effects are believed to be due to the relatively softer and more highly purified (in terms of Al concentration) surface side compared to the deeper portion of the Al bonding wire or Al bonding ribbon in the region from the surface to a certain depth. We believe that the synergistic effects of the interface control effect due to the low Si concentration gradient on the surface side, the contribution to reducing the difference in linear thermal expansion coefficients due to the internal Si phase (described below), and the resulting thermal stress reduction effect, will produce a remarkable effect of achieving good temperature cycle reliability even in high-temperature temperature cycle tests 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 its surface modified so that the Si concentration in the depth direction has a predetermined gradient 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] A Si concentration between 3.0% and 20.0% by mass helps reduce thermal distortion at the joint and improve temperature cycle characteristics. Specifically, a Si concentration of 3.0% by mass or more significantly improves temperature cycle reliability, even in high-temperature temperature cycle tests. Furthermore, advances and optimization of the equipment and conditions used in wire manufacturing and bonding have led to higher Si concentration limits while minimizing defects such as wire breakage during processing, deterioration of surface properties, reduced initial bond strength due to hardening, and damage to semiconductor chips. However, a Si concentration of 20.0% by mass or less effectively suppresses these defects and achieves 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 mass% or more, preferably 3.5 mass% or more, more preferably 4.0 mass% or more, and even more preferably 4.2 mass% or more, 4.4 mass% or more, 4.5 mass% or more, 4.6 mass% or more, 4.8 mass% or more, or 5.0 mass% or more. In addition, 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 mass% or less, preferably 19.0 mass% or less, 18.0 mass% or less, 17.0 mass% or less, 16.0 mass% or less, 15.0 mass% or less, 14.5 mass% or less, 14.0 mass% or less, 13.5 mass% or less, 13.0 mass% or less, or 12.5 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. If elements derived from atmospheric contaminants such as oxygen or carbon are adsorbed on the surface of the Al bonding wire, it is effective to wash the wire with an acid or alkali depending on the adsorbed substance before analysis.

[0032] The Al bonding wire and the like of the present invention contain Si in an amount of 3.0 mass % to 20.0 mass % and are composed of an Al phase in which Si is dissolved 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, whereas 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 %) of the Al bonding wire or Al bonding ribbon of the present invention 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 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] 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 by XPS is shown in Figure 1. In the region from the surface to a certain depth, a predetermined gradient in the Si concentration in the depth direction is confirmed, i.e., the Si concentration is low on the surface side, high in the depth direction, and gradually increases in the depth direction.

[0037] The forms of Si detected by XPS include dissolved Si in the Al phase, Si particles (precipitation / crystallization), and intermetallic compounds containing Si. The origins of the detected Si may vary as described above, but regardless of these, a determination is made based on the Si concentration detected by XPS as to whether the specified Si concentration gradient (the above-mentioned ratio Ca / Cb) is met. In this way, adjusting the Si concentration gradient in the depth direction measured by XPS allows the desired problems and effects to be solved and achieved, which is an important feature of the present invention.

[0038] The Si concentration is measured by XPS and the concentration determined from the peak of detected metallic Si (Si with a valence of zero) is used. 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 Si oxide is quite thin. Therefore, it has been confirmed that it has almost no effect on the temperature cycle reliability or first bond strength, and is therefore excluded from the analysis target when determining the concentration gradient in this 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 Si element concentration Ca in region a, which is 5 nm to 50 nm deep from the surface, was used because this region a is deformed by ultrasonic vibration and load application during bonding, which has a significant impact on the performance of the bonded interface. Analysis of the outermost surface region, which is less than 5 nm deep from the surface, is easily affected by surface contamination and other factors, resulting in large variations in the Si concentration measured by XPS, so it was excluded from the analysis range. Regions greater than 50 nm deep from the surface were also excluded from the analysis range because they have little impact on the bonded interface. The average Si element concentration Cb in region b, which is 800 nm to 1200 nm deep from the surface, was used because this depth range is appropriate for determining the Si concentration, which represents the internal composition of the Al bonding wire or Al bonding ribbon, taking into account the fact that the Si concentration is nearly 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 from 5 nm to 50 nm deep from the surface and the region b from 800 nm to 1200 nm deep from the surface and then evaluating the Si concentration gradient using their ratio Ca / Cb. Furthermore, using the average Si element concentration Cb in region b inside the sample measured by XPS and comparing it with the average Si element concentration Ca in region a on the sample surface measured by the same method to calculate the ratio Ca / Cb is effective for accurately determining the Si concentration gradient in the depth direction. This allows for accurate determination of the success or failure of the Si concentration gradient in the depth direction, which is suitable for realizing an Al bonding wire or Al bonding ribbon that exhibits good temperature cycle reliability and good first bond strength in high-temperature temperature cycle tests.

[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 high-temperature temperature cycle tests and exhibits good first bond strength, by improving the surface deformability 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 high-temperature temperature cycle tests 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 bond strength.

[0042] In the present invention, by controlling the above-mentioned ratio Ca / Cb, which is the relative ratio of Si concentration near the surface to that deep inside, 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 bond strength, and it has been discovered 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 an Al bonding wire or Al bonding ribbon to a certain depth can be measured by performing composition analysis by XPS while digging in the depth direction (toward the center of the wire, etc.) from the surface of the Al bonding wire or Al bonding ribbon 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 direction (center) 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 samples The Al bonding wire or Al bonding ribbon sample to be measured is placed on the sample stage. At this time, the sample is positioned so that the longitudinal direction is horizontal on the XPS instrument operation screen. If the sample is an Al bonding ribbon (with a rectangular or nearly rectangular cross section of 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) Measurement by XPS In XPS measurements, the measurement area was selected near the apex of the Al bonding wire or Al bonding ribbon sample while viewing the SXI (Scanning X-ray Image) screen of the instrument. Here, the apex of the Al bonding wire or Al bonding ribbon sample refers to the point directly above the central axis of the sample when observed from directly above. Then, under the following conditions, 1) Ar sputtering and 2) composition analysis of the surface after sputtering were repeated, and measurements were taken in the depth direction from the surface of the sample to detect Si2p and Al2p spectra. The Si2p and Al2p spectral peaks were detected at energy positions of approximately 98.5-99.5 eV and 71.5-73.0 eV, respectively. Measurement equipment: ULVAC-PHI Versa Probe 3 ·Achieved vacuum level: approx. 1×10 -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 extraction angle: 45 degrees Detection depth: several nm Ar sputtering Acceleration voltage: 2 kV Sputtering area: 2 x 2 mm square Sputtering rate: 9.2 nm / min (SiO2 equivalent) Depth analysis pitch: 5 nm pitch (depth from the surface range of 0 to 50 nm), 10 nm pitch (depth from the surface range of 50 to 200 nm), 20 nm pitch (depth from the surface range of over 200 nm)

[0047] As mentioned above, in XPS measurements, the sputtering rate and depth scale can be calculated in standard SiO2 equivalents. Furthermore, taking into consideration analytical accuracy, measurement time, and workability, the analysis pitch in the depth direction can be selected to be finer at the surface and coarser at the deeper portions. For example, as mentioned above, the range of depths from the surface from 0 to 50 nm can be set to a 5 nm pitch, the range of depths from the surface from 50 to 200 nm can be set to a 10 nm pitch, and the range of depths from the surface from 200 nm can be set to a 200 nm pitch.

[0048] (3) Quantitative determination of Si and Al elements Based on the detected spectra of Si2p and Al2p obtained at each depth position from the surface of the sample, the amounts of Si and Al elements are quantified 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 (metallic Si). Depending on the shape of the peak, the energy values ​​of the low-energy edge and the high-energy edge were adjusted within the 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] An example of the Si2p Si0 valence peak obtained by XPS for the Al bonding wire or Al bonding ribbon of the present invention is shown in Figure 2. The Si2p Si0 valence peak is included in the quantitative range of approximately 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 quantitative analysis of Si element for the quantification range of energy (approximately 69.0 to 79.0 eV) that includes the peak of Al2p Al0 valence (metallic Al).

[0051] (4) Calculation of Si concentration The quantitative values ​​of Si and Al at each depth from the surface of the sample and the relative sensitivity coefficients for each element set in the XPS instrument are used to calculate the Si concentration (atomic %) when the total of Si and Al at each depth from the surface of the sample 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 of the Si concentration in region a, from 5 nm to 50 nm deep from the surface, is calculated as average concentration Ca; the arithmetic mean of the Si concentration in region b, from 800 nm to 1200 nm deep from the surface, is calculated as average concentration Cb; and the arithmetic mean of the Si concentration in region f, from 5 nm to 30 nm deep from the surface, is calculated as average concentration Cf.

[0052] In the present invention, the gradient of Si concentration in the depth direction and the average concentration of Si element near the surface, which will be described later, are evaluated by averaging (arithmetic mean) the values ​​obtained by measuring at least two 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 along the central axis of the wire or ribbon. The average concentrations Ca, Cb, and Cf are the averages (arithmetic mean) 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-mentioned ratio Ca / Cb), the average concentration Cf of Si elements in a region f from 5 nm to 30 nm deep from the surface is 0.1 atomic % or more and 4 atomic % or less.

[0054] In addition to satisfying the predetermined Si concentration gradient (the above ratio Ca / Cb), by controlling the average Si element concentration Cf in the near-surface region f within the above range, the life (number of cycles until failure 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, promote recrystallization, improve deformability during bonding, and form a flat bonding interface, which is believed to result in further improvement in the life of the Al bonding wire, etc. in high-temperature temperature cycle tests. From the perspective of further improving the life of the Al bonding wire, etc. in high-temperature temperature cycle tests, the average Si element concentration Cf 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 Si concentration Cf 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 Si concentration Cf 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 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, it is possible to promote deformation near the surface of the Al bonding wire or Al bonding ribbon when ultrasonic vibration or load is applied during bonding, and to promote metal bonding at the bonding interface, 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 judge whether the conditions for 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 the 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] In the present invention, the central axis of an Al bonding wire, a cross section (L cross section) in the direction of the central axis including the central axis, and a direction parallel to the central axis (RD direction) described later are as shown in FIG. 3. While FIG. 3 shows an Al bonding wire having a circular cross section, 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 direction of the central axis including the central axis, in the direction of the thickness T (FIG. 4). Here, when processing the cross section to expose the L cross section of the Al bonding wire, the central axis of the Al bonding wire may be shifted. 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 as a cross section including the central axis.

[0059] In Al alloys containing high concentrations of Si (3.0 mass% to 20.0 mass%), the Si present in excess of 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 to 4 μm, the thermal fatigue resistance of the Si particles in the surface region can be improved.

[0060] The Si content is 3.0% by mass to 20.0% by mass, 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 the region a from 5 nm to 50 nm deep from the surface to the average Si concentration Cb in the region b from 800 nm to 1200 nm deep from the surface is in the range of 0.03 to 0.5. In addition, the average diameter of the Si phase in the L-section is in the range of 0.8 μm to 4 μm, thereby achieving better temperature cycle reliability in high-temperature temperature cycle tests. The combination of a Si concentration gradient in the region from the surface to a certain depth and a small-grain Si phase provides a synergistic effect in terms of bonding interface control and thermal strain reduction, further improving temperature cycle reliability in high-temperature temperature cycle tests. Furthermore, because the Si phase has a lower linear thermal expansion coefficient than Al, the Si phase present below 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] This paper describes a method for measuring the average diameter of Si phases in the L-section of Al bonding wire or Al bonding ribbon. The average diameter of Si phases in the L-section can be measured using a SEM-EDS-EBSD instrument. Specifically, a method can be used that combines information on Al and Si concentrations obtained by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) with information on crystal orientation obtained by electron backscatter diffraction (EBSD). More specifically, in the 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 analysis is performed using EBSD simultaneously. Next, the Al and Si phases are separated and extracted from the EDS measurement results using the analysis software provided with the instrument. Specifically, it is preferable to use the Chi Scan function, which is a function of the analysis software OIM Data Collection or OIM Analysis (both manufactured by TSL Solutions) attached to an FE-SEM (Field Emission-Scanning Electron Microscope) device. Then, for the region identified as the Si phase, the crystal orientation can be analyzed by using the analysis software attached to 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 calculating the average diameter of the Si phase, parts where the crystal orientation cannot be measured or parts 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 cross section of the Al bonding wire or Al bonding ribbon of the present invention is calculated by the following steps (1) to (3). (1) The L-section of the Al bonding wire or Al bonding ribbon is used as the inspection surface, and the Al and Si concentrations are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) Use the Chi Scan function to separate and extract Al and Si. 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 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. For the average calculation, the average value obtained by area averaging (area-weighted average), which can be selected in the software provided with the device, is used. By using the average value obtained 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 is calculated automatically by the software, averaging the values ​​obtained by multiplying each particle area by its proportion of the total particle area.

[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 step (2) above, the Tolerance (%) setting can be selected in the range of 20 to 40%, and for standard analysis of the L cross section of Al bonding wire or Al bonding ribbon, it is preferable to compare at approximately 30%. Here is a supplementary explanation of the procedure for adjusting this Tolerance. 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 in 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 at three or more locations. When selecting the measurement area, 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 along the central axis of the Al bonding wire or Al bonding ribbon, and provide them for measurement, from the viewpoint of ensuring the objectivity of the measurement data. 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 but 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 observed images of the L-section. However, in the present invention, it is preferable to use the method of combining the information on the Al and Si concentrations obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD, as described above, for the following reasons: the method is equipped with many measurement functions and can determine multiple characteristics in a single measurement, 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; automatic analysis is possible; and the measurement is easy using widely available equipment and analysis techniques.

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

[0068] That is, 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 element concentration Ca in the region a from the surface to the depth of 5 nm or more and 50 nm or less to the average Si element concentration Cb in the region b from the surface to the depth of 800 nm or more and 1200 nm or less is in the range of 0.03 or more and 0.5 or less. In addition to satisfying the above characteristics, <100> By setting the orientation ratio of the crystal orientation in the range of 15% to 50%, it is possible to achieve better first bonding strength. The effect of controlling the bonding interface by the gradient of the Si concentration in the region from the surface to a certain depth and the effect of controlling the Al phase in the RD direction are the same. <100> The synergistic effect of the crystal orientation can be obtained, further enhancing the effect of improving the first bonding strength, which in turn can contribute to improving the temperature cycle reliability in high-temperature temperature cycle tests.

[0069] In order to achieve a better first bonding strength, 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 <100> The orientation ratio of the crystal orientation is more preferably 20% or more, further preferably 22% or more, 24% or more, 26% or more, or 28% or more, and further more preferably 30% or more, or 35% or more. <100> From the viewpoint of realizing even better first bonding strength, the upper limit of the orientation ratio of the crystal orientation is more preferably 48% or less or 45% or less, even more preferably 42% or less, and even more preferably 40% or less.

[0070] This section explains a method for measuring the orientation ratio of the crystal orientation of the Al phase in the L cross section of an Al bonding wire or Al bonding ribbon. The orientation ratio of the crystal orientation of the Al phase in the L cross section can be measured using an 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 the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD. More detailed procedures can be the same as those described above in relation to the measurement of the average diameter of the Si phase. That is, for the region identified as the Al phase, the ratio of the Al phase in the RD direction can be calculated using the analysis software provided with the device. <100> The orientation ratio of the crystal orientation can be calculated. When calculating the orientation ratio, the partial ratio is calculated as the population of the area of ​​only the crystal orientations that can be identified based on a certain reliability within the measurement area. <100> The area ratio of the crystal orientation is calculated as <100> Therefore, in one embodiment, the orientation ratio of the crystal orientation of the Al phase in the L cross 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 the measurement area where the L-section of the Al bonding wire or Al bonding ribbon is used as the inspection surface, the Al and Si concentrations are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) Use the Chi Scan function to separate and extract Al and Si. 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) The crystal orientation of the region identified as Al phase was analyzed, and the Al phase in the RD direction was <100> The orientation ratio of the crystal orientation is calculated.

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

[0072] -Addition of Sr, Na, P, and 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 at 3.0 mass% to 20.0 mass% tend to have a higher frequency of wire breakage during wiredrawing. One reason for this is thought to be that particles of the Si phase crystallized during solidification cause stress concentration during wiredrawing, inducing wire breakage. It is presumed 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 easing 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, and 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. Furthermore, 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, and 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 concentration of B 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, and 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 ppm by mass, preferably 1 ppm by mass or more or 3 ppm by mass or more, more preferably 5 ppm by mass or more or 8 ppm by mass or more, even more preferably 10 ppm by mass or more or 30 ppm by mass or more, particularly preferably 50 ppm by mass or more, 80 ppm by mass or more, or 100 ppm by mass or more. The upper limit of the total concentration of the second element group is preferably 10,000 ppm by mass or less, more preferably 8,000 ppm by mass or less, even more preferably 5,000 ppm by mass or less, particularly preferably 3,000 ppm by mass or less or 2,000 ppm by mass or less. In one embodiment, the total concentration of the second element group is preferably 100 ppm by mass or more and 2,000 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 ppm by mass to 2000 ppm by mass, thereby suppressing scratches and abrasions 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% by mass to 20.0% by mass may harden the surface and cause the Si phase and Al oxide present on the surface to fall off, resulting in scratches and abrasions on the surface during wiredrawing, resulting in an Al bonding wire or Al bonding ribbon with significant 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 abrasions 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 ppm by mass or more, even more preferably 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass or more, and the upper limit is preferably 1800 ppm by mass or less, more preferably 1600 ppm by mass or less, 1500 ppm by mass or less, or 1200 ppm by mass or less, even more preferably 1000 ppm by mass or less, 900 ppm by mass or less, or 800 ppm by mass or less, and particularly preferably 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass 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 with 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. Furthermore, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon with 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 scraping 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. Furthermore, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon with 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 scraping on the surface and forming an Al bonding wire or Al bonding ribbon with 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 even 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 unavoidable impurities. Thus, in a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, and unavoidable 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 unavoidable 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 unavoidable 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 unavoidable 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, "a 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 either 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, and preferably in the range of 200 to 400 μm. When the present invention is an Al bonding ribbon, the dimensions (width W x thickness T) of its rectangular or approximately rectangular cross section 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 can be 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 according to the present invention will be described below. Hereinafter, an example will be described in relation to the manufacture of an Al bonding wire.

[0097] It is preferable that the Al and alloying elements used as raw materials have high purity. Al is preferably one with a purity of 99.5% by mass or more and the balance being composed of inevitable impurities, more preferably one with a purity of 99.9% by mass or more and the balance being composed of inevitable impurities, and even more preferably one with a purity of 99.99% by mass or more and the balance being composed of inevitable impurities. Si, the first element group, the second element group, and other elements used as alloying elements are preferably ones with a purity of 99.9% by mass or more and the balance being composed of inevitable impurities, and more preferably ones with a purity of 99.99% by mass or more and the balance being composed of inevitable impurities. The Al alloy used for the Al bonding wire can be manufactured by loading raw materials of Al and alloying elements into a graphite or alumina crucible processed so as to obtain a cylindrical ingot, and melting using an electric furnace or a high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm in consideration of the workability in subsequent processing steps. The atmosphere in the furnace during melting is preferably an inert atmosphere or a reducing atmosphere in order to prevent excessive oxidation of Al, Si, the first element group, the second element group, and other elements constituting the wire. The maximum temperature reached by the molten metal during melting is preferably in the range of 700 °C or more and less than 1050 °C in consideration of ensuring the fluidity of the molten metal and making it easy to control the size of the Si phase during solidification. The cooling method during solidification can use water cooling, furnace cooling, air cooling, etc.

[0098] For the cylindrical ingot obtained by melting, after performing a solution treatment of heating at a high temperature, the wire with the target wire diameter can be manufactured by repeatedly performing wire drawing using a die. 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> To control the gradient of the 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 in 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 reduction rate- Regarding the die area reduction rate during wire drawing, drawing with a high area reduction rate for larger diameter wires and a lower area reduction rate for smaller diameter wires is effective for 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% to less than 40%, and that from half the wire diameter to the final wire diameter be in the range of 10% to less than 25%. Here, if the wire area reduction rate per die is P1, P1 can be expressed by the following formula. P1={(R2 2 -R1 2 ) / R2 2}×100 In the formula, R2 represents the diameter (mm) of the wire before processing, and R1 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 wire drawing and promoting deformation that causes the surface to expand in the wire drawing direction, it is possible to assist the concentration gradient in the surface region. The lubricating liquid used in wire drawing is preferably an aqueous liquid containing a surfactant or the like that reduces the friction coefficient.

[0103] -Atmosphere of intermediate heat treatment- Adjusting the atmosphere of the intermediate heat treatment is also effective for controlling the concentration gradient in the surface region. The intermediate heat treatment is a heat treatment performed during the wire drawing process from an ingot to the final wire diameter. It is preferable to perform the intermediate heat treatment in an atmosphere of an inert gas such as N2 gas. This can assist in controlling the oxidation of Si in Al during wire drawing and maintaining a low concentration of Si near the surface.

[0104] <Control of average diameter of Si phase> To adjust the average diameter of the Si phase in the L cross-section to be in the range of 0.8 μm or more and 4 μm or less, it is effective to adjust the temperature during melting in ingot manufacturing to be in the range of 800 °C or more and less than 1050 °C, adjust the casting temperature to be in the range of 700 °C or more and less than 780 °C, and control the temperature of the solution treatment to be in the range of 450 °C or more and less than 550 °C and the time of the solution treatment to be in the range of 1 hour or more and less than 6 hours. The casting temperature is the temperature when the molten metal is cast into a mold or the like and corresponds to the solidification start temperature. When the casting temperature is high, the Si phase crystallized during solidification tends to coarsen and columnarize, and the average diameter of the Si phase tends to increase. When the temperature of the solution treatment is high, the columnar Si phase tends to be segmented and granulated, resulting in a decrease in 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. For example, water cooling is also effective.

[0105] <Control of orientation ratio of <100> crystal orientation of Al phase in RD direction> Al phase in the RD direction on the L cross section <100> In order to adjust the orientation ratio of the crystal orientation to a range of 15% or more and 50% or less, it is effective to adjust the conditions of the intermediate heat treatment. The temperature range of the intermediate heat treatment is 250°C or more and less than 400°C, and the time is effective to be 1 hour or more and less than 48 hours. The number of intermediate heat treatments is preferably in the range of 2 to 4 times. It is preferable to perform intermediate heat treatment 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 wire diameter 2.0 to 3.5 times the final wire diameter. By performing intermediate heat treatment under these conditions, the processing strain of the Al phase is reduced, and slight recrystallization occurs, thereby reducing the processed structure of the Al phase at the final wire diameter, and in the subsequent heat treatment, the progress of recrystallization of the Al phase is increased, and the rotation of the crystal orientation is promoted to reduce the Al phase in the RD direction. <100> On the other hand, if the intermediate heat treatment temperature is set to less than 250°C or 400°C or higher, the orientation ratio of the Al phase in the RD direction becomes smaller. <100> There is a concern that the orientation ratio of the crystal orientations may become unstable.

[0106] Regarding the final heat treatment conditions, it is effective to adjust the temperature range to between 200°C and 360°C, and the time range to between 2 hours and 24 hours. The final heat treatment promotes the 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 in turn changes the recrystallization temperature. By adjusting the progress of recrystallization during the final heat treatment, it becomes easier to control the orientation of the crystal.

[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 roughly the same as those described above. Also, when manufacturing Al bonding ribbon by rolling, the reduction rate of the die can be adjusted by replacing it with the reduction rate.

[0108] [Semiconductor Devices] 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, as in the semiconductor device described in JP 2020-150116 A, the semiconductor device may be configured to include a lead frame and a semiconductor chip mounted on the lead frame.

[0111] Examples of semiconductor devices 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. [Example]

[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 used 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 raw materials of the alloying elements into an alumina crucible and melting them using a high-frequency heating furnace. The atmosphere inside 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. The ingot was then subjected to solution treatment and homogenization treatment, followed by wire drawing using a die and intermediate heat treatment 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 the 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. Intermediate heat treatments were performed 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 performed in a N2 gas atmosphere.

[0116] During wire drawing, a commercially available lubricant (a lubricant containing a surfactant that reduces the coefficient of friction in an aqueous system) was used. The wire reduction rate per die during wire drawing was set such that the die reduction rate from the start of wire drawing to a wire diameter of 3 mm was in the range of 20% or more and less than 40%, and the die reduction rate from a wire diameter of 3 mm to the final wire diameter was in the range of 10% or more and less than 25%. Also, the wire feeding speed during wire drawing was set to be in the range of an average of 20 m / min or more and less than 50 m / min in the range 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 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 A sample of an Al bonding wire or Al bonding ribbon to be used for measurement was placed on the sample stage. At that time, the position was adjusted on the operation screen of the XPS apparatus so that the longitudinal direction of the Al bonding wire or Al bonding ribbon sample was horizontal. 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. [[ID=]14]

[0119] (2) Measurement by XPS In the measurement by XPS, the measurement region was selected while looking at the SXI (Scanning X-ray Image) screen of the apparatus so that the vicinity of the apex of the Al bonding wire or Al bonding ribbon sample became the measurement region. Then, measurement in the depth direction from the surface of the Al bonding wire sample was performed by XPS under the following conditions, and the spectra of Si2p and Al2p were detected. The peak positions of the spectra of Si2p and Al2p were detected at positions where the energy was about 98.5 - 99.5 eV and 71.5 - 73.0 eV, respectively. · Measuring device: Versa Probe3 manufactured by ULVAC-PHI · Ultimate vacuum: about 1×10 -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 extraction angle: 45 degrees Detection depth: several nm Ar sputtering Acceleration voltage: 2 kV Sputtering area: 2 x 2 mm square Sputtering rate: 9.2 nm / min (SiO2 equivalent) Depth analysis pitch: 5 nm pitch (depth from the surface range of 0 to 50 nm), 10 nm pitch (depth from the surface range of 50 to 200 nm), 20 nm pitch (depth from the surface range of over 200 nm)

[0120] (3) Quantitative determination of Si and Al elements Based on the detected spectra of Si2p and Al2p obtained at each depth position from the surface of the sample, the amounts of Si and Al elements were quantified using the following procedure. Specifically, the quantification of Si element was performed within the energy range (approximately 95.0 to 101.0 eV) that includes the peak of Si2p Si0 (metallic Si). The energy values ​​of the low-energy edge and the high-energy edge were adjusted within the above quantification range depending on the shape of the peak. The background of the quantification range was determined using the Shirley method, and the Si element was quantified using the peak area after subtracting the background. The quantitative analysis of Al element was carried out in the same procedure as the above-mentioned quantitative analysis of Si element, in the energy quantification range (approximately 69.0 to 79.0 eV) including the peak of Al2p Al0 valence (metallic Al).

[0121] (4) Calculation of Si concentration Using the quantitative values of each element of Si and Al at each depth position in the depth direction from the surface of the sample and the relative sensitivity coefficients of each element set in the XPS apparatus, the Si concentration was calculated when the total of metallic Si and metallic Al at each depth position in the depth direction from the surface of the sample was 100 atomic %. Then, the arithmetic mean value of the Si concentration in region a where the depth from the surface is 5 nm or more and 50 nm or less was defined as the average concentration Ca, the arithmetic mean value of the Si concentration in region b where the depth from the surface is 800 nm or more and 1200 nm or less was defined as the average concentration Cb, and the arithmetic mean value of the Si concentration in region f where the depth from the surface is 5 nm or more and 30 nm or less was defined as the average concentration Cf.

[0122] For the measurement of the Si concentration, two samples randomly selected from a plurality of samples obtained at intervals of 50 cm or more in the central axis direction of the wire or ribbon were used from the Al bonding wire or Al bonding ribbon to be measured. And the average concentration Ca, the average concentration Cb, and the average concentration Cf were taken as the average values (arithmetic mean) of the values obtained by the above procedures (1) to (4) for the two samples.

[0123] <Method for Measuring Element Content> The concentration analysis of the elements contained in the Al bonding wire or Al bonding ribbon was carried out using, as the analyzer, ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) ("PS3520UVDDII" manufactured by Hitachi High-Technologies Corporation) or ICP-MS (Inductively Coupled Plasma-Mass Spectrometer) ("Agilent 7700x ICP-MS" manufactured by Agilent Technologies, Inc.). By such measurement, the concentration (mass ppm) 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] Measurements were performed using a FE-SEM (SU-70, manufactured by Hitachi High-Technologies Corporation) and analysis software, including 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 at least 50 cm along 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 along the central axis 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 EDS and EBSD measurements were an acceleration voltage of 15 kV, a measurement magnification of 350x, a scan speed of 30 to 120 points / s, and a measurement interval in the range of 0.1 to 0.3 μm. A faster scan speed can shorten the measurement time, but there is a concern that the EDS measurement accuracy may be reduced. It is desirable to select an appropriate scan speed within the above range.

[0126] To measure the orientation ratio of the Al phase crystal orientation in the L cross section of the Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, and a method was used in which the information on the Al concentration and Si concentration obtained by SEM-EDS was combined with the information on the crystal orientation obtained by EBSD. More specifically, the measurements were carried out according to the following steps (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, the Al and Si concentrations were measured using EDS and the crystal orientation was measured using EBSD simultaneously. (2) Using the Chi Scan function of the EBSD analysis software, Al and Si were separated and extracted. 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 was adjusted as necessary. (3) For the Al phase and the identified regions, the crystal orientation was analyzed, and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction was calculated. As the crystal orientations to be investigated, at least three types of typical crystal orientations of Al metal, namely <111>, <110>, and <100>, were selected, and the crystal orientations with high ratios were selected as needed. Here, the partial ratio was used for the orientation ratio of the crystal orientation.

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

[0128] <Method for Measuring the Average Diameter of the Si Phase> For the measurement of the average diameter of the Si phase in the L cross-section of the Al bonding wire or Al bonding ribbon, the same SEM-EDS-EBSD apparatus as used for the measurement of the crystal orientation of the Al phase was used, and a method that combines the information on the Al concentration and Si concentration obtained by SEM-EDS and the information on the crystal orientation obtained by EBSD was employed. Specifically, after performing the procedures (1) and (2) above, the measurement was carried out according to the following procedure (3). (3) For the regions identified as the Si phase, the crystal orientation was analyzed. If the orientation difference between the measurement points was 15° or more, it was judged as a grain boundary, and the equivalent circle diameter of each grain was determined. Then, the equivalent circle diameters of each grain were averaged to calculate the average diameter of the Si phase. Here, in the average calculation, the average value obtained by area averaging (area-weighted average) was used. Also, when calculating the average diameter of the Si phase in the L cross-section, only Si phases with a diameter (equivalent circle diameter) of 0.5 μm or more were targeted.

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

[0130] [Evaluation Method for Al Bonding Wire or Al Bonding Ribbon] The evaluation method for Al bonding wire is described below. The wire diameter of the Al bonding wire used for the 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 Ni film. 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 above electrodes on the semiconductor chip) and the second bonding (bonding to the above 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). 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 semiconductor chip mounted on a substrate, and the electrodes on the semiconductor chip were connected to the electrodes on the substrate with aluminum bonding wire or aluminum bonding ribbon. After 1000 cycles, the samples were removed and subjected to a shear test on the first joint. The shear strength of the first joint used to evaluate temperature cycle reliability was the average shear strength of five randomly selected first joints. The strength ratio (F2 / F1) of the shear strength (F2) after the temperature cycle test to the shear strength (F1) before the temperature cycle test was used to evaluate the reliability. If the strength ratio was less than 50%, it was judged to have practical problems and was given a rating of "0", if the strength ratio was between 50% and 70%, it was judged to need improvement and was given a rating of "1", if the strength ratio was between 70% and 75%, it was judged to be excellent and was given a rating of "2", and if the strength ratio was 75% or more, it was judged to be particularly excellent and was given a rating of "3". "0" and "1" are failures, while "2" and "3" are passing. The evaluation results are shown in the "High-temperature temperature cycle reliability" column in the table.

[0132] <Evaluation of high-temperature cycle reliability (after 1,300 cycles)> After 1,300 cycles of the high-temperature TCT, samples were removed and subjected to a shear test on the first joint. The shear strength of the first joint used to evaluate temperature cycle reliability was calculated by averaging the shear strength of five randomly selected first joints. The shear strength F2 after the high-temperature TCT (1,300 cycles) to the shear strength F1 before the high-temperature TCT (F2 / F1) was used to evaluate the reliability. A strength ratio of less than 50% was considered unsuitable for practical use and rated "0." A strength ratio of 50% to less than 60% was considered acceptable for practical use and rated "1." A strength ratio of 60% to less than 70% was considered excellent and rated "2." A strength ratio of 70% or greater was considered particularly excellent and rated "3." A "0" indicates failure, while "1," "2," and "3" indicate passing. The evaluation results are listed in the "High-Temperature Cycle Reliability (After 1,300 Cycles)" column in the table.

[0133] <Evaluation method for 1st bond strength> The evaluation method for the first bond strength is explained below. The first bond strength was evaluated by a shear strength test. First bond was performed at 10 locations under bonding conditions suitable for reliability testing, and the shear strength (shear strength) of the first bond was measured. Under these bonding conditions, the ultrasonic output was set slightly higher to ensure a sufficient bonding area. A commercially available micro-shear strength tester (Nordson 4000-PLUS) was used to measure the shear strength. The shear rate was 200 μm / s, 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 1500gf or more, it was judged to be excellent and rated as "3", if it was between 1300gf and 1500gf it was judged to be no problem in practical use and rated as "2", if it was between 1000gf and 1300gf it was judged to need improvement and rated as "1", and if it was less than 1000gf it was judged to have a problem in practical use 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 is explained below. Wire drawing was performed with diameters ranging from 6 mm to 0.3 mm, and the number of wire breakages was confirmed. The wire drawing conditions, such as feed speed and area reduction rate, were selected from the conditions described above, and the appropriate manufacturing conditions were adjusted and changed for each wire. The drawn Al bonding wire lengths ranged from 100 to 200 m, and the number of wire breakages was calculated per 100 m. If the number of breakages was zero, it was judged to be good and given a rating of "3." If it was one breakage, it was judged that it could be addressed by improving the manufacturing conditions and given a rating of "2." If it was two to four breakages, it was considered a problem of reduced productivity and given a rating of "1." If it was five or more breakages, it was judged that it was difficult to use in practice and given a rating of "0." The evaluation results are shown in the "Breakage during processing" column in the table.

[0135] (Evaluation method for surface scratches and scrapes) The surface quality of the Al bonding wire and Al bonding ribbon was evaluated, focusing on scratches and abrasions. The Al bonding wire diameter was 300 μm. Three measurement areas were randomly selected for the Al bonding ribbon, spaced at least 1 m apart along the central axis of the Al bonding wire. Three approximately 2 cm lengths were taken from each of the three locations, for a total of nine samples. Specifically, the surface was observed using an SEM at magnifications ranging from 50 to 500x. Scratches longer than 50 μm and abrasions longer than 30 μm were considered defective. The number of scratches and abrasions was counted, and a rating of "3" was given for a good pass; one to two were considered acceptable for practical use; three to seven were considered poor surface quality; and eight or more were considered unsuitable for practical use and rated "0." 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.

[0137] [Table 1]

[0138] [Table 2]

[0139] [Table 3]

[0140] [Table 4] Explanation of symbols

[0141] 1. Al bonding wire 10 Center axis 11 L cross section 2. Al bonding ribbon 20 center axis 21 L cross 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, 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 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.

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. 2. An Al bonding wire or Al bonding ribbon as described in claim 1, wherein the average concentration Cf of Si elements 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 as described in claim 1, wherein, when the crystal orientation of the Al phase in the L-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% or more and 50% or less.

5. The Al bonding wire or Al bonding ribbon according to claim 1, further containing one or more of Sr, Na, P, and B in a total amount of 10 mass ppm or more and 800 mass ppm or less.

6. The Al bonding wire or Al bonding ribbon according to claim 1, further containing one or more of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 mass ppm or more and 2000 mass ppm or less.

7. The Al bonding wire or Al bonding ribbon according to claim 5, further containing one or more of Ni, Ti, Fe, Zn, and Mg in a total amount of 100 mass ppm or more and 2000 mass ppm or less.

8. The Al bonding wire or Al bonding ribbon according to any one of claims 1 to 7, 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.

9. The Al bonding wire or Al bonding ribbon according to claim 2, wherein the average diameter of the Si phase is a value measured using a SEM-EDS-EBSD device.

10. The Al bonding wire or Al bonding ribbon according to claim 4, wherein the orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device.

11. 2. The Al bonding wire or Al bonding ribbon according to claim 1, which is for use in a semiconductor device.

12. A semiconductor device comprising the Al bonding wire or Al bonding ribbon according to claim 1.

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