Al bonding wire or Al bonding ribbon

Abstract

The present invention provides an Al bonding wire or Al bonding ribbon that exhibits excellent high-speed temperature cycle reliability even in long-cycle high-speed temperature cycle tests required for next-generation SiC power semiconductors. The Al bonding wire or Al bonding ribbon contains 3.0 mass % to 20.0 mass % Si, and when the crystal orientation of the Al phase is measured in the L cross section (a 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, and when the number of Si phases having an equivalent circle diameter in the L cross section of 0.5 μm or more and 0.8 μm or less is Ns and the number of Si phases having an equivalent circle diameter in the L cross section of 0.5 μm or more is Nc, the ratio of Ns to Nc [Ns / Nc × 100 (%)] is 30% or more and 95% or less.

Description

[Technical Field]

[0001] The present invention relates to an Al bonding wire or an Al bonding ribbon, and further to a semiconductor device obtained using the Al bonding wire or the 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 a connecting material made solely of high-purity Al is used, 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 semiconductors 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 expansion coefficient than the semiconductor chip, thermal stress occurs at the first bonded portion due to the difference in linear expansion coefficients between the two, which can ultimately lead to fatigue failure of the Al bonding wire or Al bonding ribbon. A temperature cycle test is one type of accelerated evaluation test for the lifespan (temperature cycle reliability) of such a first bonded portion as it rises and falls in temperature. The Al bonding wire or Al bonding ribbon used in next-generation power semiconductors is required to exhibit excellent temperature cycle reliability in a temperature cycle test.

[0012] However, the inventors have confirmed that when using an Al bonding wire that has been strengthened by adding Si or the like as disclosed in Patent Documents 1 to 3, in temperature cycle tests intended for use in next-generation power semiconductor devices, cracks propagate at a relatively fast rate within the Al alloy electrode, which has lower strength than the Al bonding wire, making it difficult to consistently achieve good temperature cycle reliability.

[0013] On the other hand, conventional temperature cycle tests (hereinafter also referred to as "TCT (Temperature Cycle Test)") can be easily performed using commercially available test equipment. However, the temperature change rate in TCT is relatively slow, which raises concerns about discrepancies with the fast temperature change rate during operation of power semiconductor devices. Therefore, recently, high-speed temperature cycle tests (hereinafter also referred to as "high-speed TCT"), which increase the temperature change rate to more closely resemble actual usage conditions, have been considered. The temperature change rate in conventional TCT is, for example, about 10°C / min, while in high-speed TCT, the temperature changes at a high rate of, for example, about 200°C / min. Regarding reliability evaluation of Al bonding wire or Al bonding ribbon joints, the inventors have confirmed that even Al bonding wires or Al bonding ribbons that do not show a decrease in reliability when evaluated using conventional TCT may experience a decrease in bond strength and a shortened bond life when evaluated using high-speed TCT. Therefore, there is a demand for Al bonding wire or Al bonding ribbon that exhibits good joint reliability even in high-speed TCT, a more severe test that is closer to the conditions of actual use, and that provides excellent temperature cycle reliability. Hereinafter, the temperature cycle reliability in high-speed TCT may be referred to as "high-speed temperature cycle reliability."

[0014] Furthermore, it is predicted that the use of highly heat-resistant silicon carbide (SiC) will increase in next-generation power semiconductor elements, replacing the previously mainstream silicon (Si). Connections for SiC power semiconductors will require even stricter high-speed temperature cycle testing than currently available. For example, while the number of cycles in high-speed temperature cycle testing for Si semiconductors is approximately 10,000, for SiC semiconductors, this should be extended to approximately 20,000. Furthermore, while the upper temperature limit for Si semiconductors is approximately 150°C, which is a strict condition, for SiC semiconductors, excellent high-speed temperature cycle reliability is required under even harsher conditions, such as above 175°C. The inventors have discovered that even Al bonding wires or Al bonding ribbons that exhibit excellent high-speed temperature cycle reliability at approximately 10,000 cycles may experience a problem of deterioration in the strength of the Al bonding wire or Al bonding ribbon joint when tested for SiC semiconductors at 20,000 cycles. This may result in poor high-speed temperature cycle reliability. This is thought to be because the shape, location, and extension behavior of cracks that occur at the joint of the Al bonding wire or Al bonding ribbon change as the number of temperature cycles increases. Therefore, when the number of cycles increases from 10,000 to 20,000, the proportion of cracks that occur inside the Al bonding wire or Al bonding ribbon increases rapidly, which is thought to be a factor in accelerating the deterioration of reliability.

[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 excellent high-speed temperature cycle reliability even in high-speed temperature cycle tests with a long number of cycles, which is required for next-generation SiC power semiconductors. [Means for solving the problem]

[0016] As a result of intensive research into the above-mentioned problems, the inventors have found that in an Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, the Al phase in the RD direction 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 <100> We discovered that an Al bonding wire or Al bonding ribbon having a specific range of orientation ratio of the crystal orientation and the ratio of the number of Si phases having a circular equivalent diameter of 0.5 μm or more and 0.8 μm or less in the L cross section can solve the above problem, and by further research based on this finding, we completed the present invention.

[0017] That is, the present invention includes the following. <1> An Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, 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, An Al bonding wire or Al bonding ribbon in which the ratio of Ns to Nc [Ns / Nc × 100 (%)] is 30% or more and 95% or less, where Ns is the number of Si phases whose circle equivalent diameter in the L cross section is 0.5 μm or more and 0.8 μm or less, and Nc is the number of Si phases whose circle equivalent diameter in the L cross section is 0.5 μm or more. <2> The ratio of Ns to Nc [Ns / Nc × 100 (%)] is 40% or more. <1> The Al bonding wire or Al bonding ribbon according to claim 1. <3> When measuring the crystal orientation of the Si phase in the L cross section, the angle difference with respect to the direction perpendicular to the central axis (ND direction) is 15° or less. <100> Crystal orientation and <111> The total orientation ratio of the crystal orientation is 20% or more and 60% or less. <1> or <2> The Al bonding wire or Al bonding ribbon according to claim 1. <4> The average ratio (e / f) of the short side length e to the long side length f of the Si phase in the L cross section is 0.20 or more and 0.70 or less, <1> ~ <3> The Al bonding wire or Al bonding ribbon according to any one of the above. <5> Further, it contains one or more of Sr, Na, Fe, and P 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 Ti, Ni, Mg, and Cu 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, Fe, P, Ti, Ni, Mg, and Cu 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 orientation ratio of the crystal orientation, the circle equivalent diameter of the Si phase, and the number thereof are values ​​measured using a SEM-EDS-EBSD device. <1> ~ <7> The Al bonding wire or Al bonding ribbon according to any one of the above. <9> The average value of the ratio (e / f) of the short side length e to the long side length f of the Si phase 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 excellent high-speed temperature cycle reliability even in high-speed temperature cycle tests with long cycle numbers, which is required for next-generation SiC power semiconductors, and a semiconductor device obtained using the Al bonding wire or Al bonding ribbon. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram for explaining the measurement surface (inspection surface), RD direction, and ND direction when measuring the crystal orientation of the Al phase and Si phase, the small diameter ratio of the Si phase, and the shape of the Si phase for an Al bonding wire. The measurement surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding wire. [Figure 2] 2 is a schematic diagram illustrating the measurement surface (inspection surface), RD direction, and ND direction when measuring the crystal orientation of the Al and Si phases, the small diameter ratio of the Si phase, and the shape of the Si phase for an Al bonding ribbon. The measurement surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding ribbon. [Figure 3] FIG. 3 is a schematic diagram for explaining the short side length (e) and long side length (f) of the Si phase in the L cross section. [Figure 4] FIG. 4 is an example of a graph showing the number distribution of the circle-equivalent diameter of the Si phase in the L cross section. 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 is an Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, 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, Rolling Direction) is 15° or less. <100> The orientation ratio of the crystal orientation (hereinafter referred to as "RD direction Al phase <100> The crystal orientation ratio is 15% or more and 50% or less. When the number of Si phases having a circle-equivalent diameter of 0.5 μm or more and 0.8 μm or less in the L cross section is defined as Ns, and the number of Si phases having a circle-equivalent diameter of 0.5 μm or more in the L cross section is defined as Nc, the ratio of Ns to Nc [Ns / Nc×100(%)] is 30% or more and 95% or less.

[0022] As mentioned above, when a connecting material made solely of high-purity Al is used in a temperature cycle test, cracks propagate relatively rapidly within the connecting material, resulting in a decrease in temperature cycle reliability. It has been confirmed that Al alloys containing a high concentration of Si can reduce the thermal expansion of the wire and improve temperature cycle reliability. In a high-speed temperature cycle test (high-speed TCT), in which the temperature change rate is increased to approximate actual use conditions, it has been confirmed that even Al bonding wires or Al bonding ribbons that do not exhibit a decrease in reliability when evaluated using conventional TCT can experience a decrease in bond strength and a shortened bond life. Furthermore, Al bonding wires or Al bonding ribbons that have been strengthened by the addition of Si or other additives have sometimes experienced internal cracks during their manufacture. Furthermore, as the number of temperature cycles in the high-speed TCT increases significantly, bond strength is more likely to decrease. Therefore, further improvements in high-speed temperature cycle reliability are required to meet the high-speed temperature cycle reliability required for next-generation power semiconductor devices, such as SiC, which have high heat resistance.

[0023] The inventors have demonstrated that the mode and causes of defects in wire or ribbon joints change with increasing cycle counts in high-speed temperature cycle tests. Although this varies depending on the detailed conditions of the temperature history, cracks propagate primarily within the wire or ribbon up to approximately 10,000 cycles. However, beyond 15,000 cycles, the progression of cracks at the joint interface and within the electrode occurs in a combined manner, reducing reliability. Although it can be difficult to distinguish between cracks at the joint interface and those within the electrode by observing the joint cross section, we have found that it is effective to distinguish between the two types of cracks observed during high-cycle tests and to clarify their relationship with the wire or ribbon microstructure.

[0024] Because high-speed TCT tends to concentrate stress at the bond interface, it has been confirmed that the incidence of cracks at the bond interface is higher than with standard TCT. In addition to suppressing cracks inside the wire or ribbon that occur at low cycles, when the test progresses to 20,000 cycles, it becomes important to simultaneously suppress cracks at the bond interface and inside the electrode. The number of cycles mentioned above is an example of a guideline value under certain conditions of high-speed TCT, and the number of cycles required will vary depending on the high-speed TCT test conditions (temperature, time, heating and cooling rates) and the semiconductor device used.

[0025] As a result of intensive research to solve the above problems, the inventors have found that an Al bonding wire or an Al bonding ribbon containing 3.0 mass % or more and 20.0 mass % or less of Si has an Al phase in the direction parallel to the central axis (RD direction) of its L cross section. <100> It was clarified that by simultaneously adjusting the orientation ratio of the crystal orientation and the number distribution of the Si phase in the region with a relatively small circle-equivalent diameter in the L cross section (the ratio of the number of Si phases in a specific range of circle-equivalent diameter to the total number of Si phases), it is possible to improve reliability in high-speed TCT with a fairly long number of temperature cycles, contributing to a longer life. By mutually controlling the structure from different perspectives, namely the crystal orientation of the Al phase and the number distribution of the Si phase, it is possible to improve high-speed temperature cycle reliability even in severe high-speed TCT.

[0026] 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 has an Al phase in which Si is solid-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 particles and Si precipitates. Si crystallized particles are formed from the melt during solidification and are coarse with sizes of about 1 to 25 μm, while Si precipitates are formed from the solid state and are small with sizes of about 0.1 to several μm.

[0027] In the present invention, "wire" and "ribbon" are not classified by shape, but by their manufacturing method. That is, "wire" refers to a "connecting material manufactured by wire drawing using a die," and "ribbon" refers to a "connecting material manufactured by a rolling process." A "wire" typically has a circular cross-sectional shape, and a "ribbon" typically has a rectangular or nearly rectangular cross-sectional shape.

[0028] In this invention, "ND direction" refers to a direction that satisfies both "perpendicular to the central axis" and "perpendicular to the rolled surface." In the case of wire, since forces are applied from all directions during wire drawing using a die, there is flexibility in how the ND direction is taken, and there is also flexibility in how the L cross section (a cross section in the direction of the central axis including the central axis) is taken. However, it is common to take the L cross section so that it is perpendicular to the ND direction, and this approach is also adopted in this invention. In the case of ribbon, the "ND direction" is uniquely determined by the definition of "perpendicular to the rolled surface." On the other hand, there are two ways to take the L cross section in ribbon: "a cross section perpendicular to the width W direction" and "a cross section perpendicular to the thickness T direction." However, to emphasize the ease of cross-section polishing and EBSD analysis, we define the "cross section perpendicular to the width W direction" as the L cross section (Figure 2).

[0029] That is, the central axis of the Al bonding wire, the cross section (L cross section) in the central axis direction including the central axis, the RD direction, and the ND direction are as shown in Figure 1. Figure 1 shows the case of an Al bonding wire having a circular cross section, but in the case of an Al bonding ribbon having a rectangular or approximately rectangular cross section with width W and thickness T, the central axis refers to the axis passing through the center of width W and the center of thickness T, and the L cross section refers to a cross section in the central axis direction including the central axis and perpendicular to the width W direction (Figure 2). Specifically, the central axis of the Al bonding ribbon, the cross section (L cross section) in the central axis direction including the central axis, the RD direction, and the ND direction are as shown in Figure 2. When cross-section processing is performed to expose the L cross section of the Al bonding wire, there may be a deviation from the central axis of the Al bonding wire. In this case, if the length of the L cross section in the direction perpendicular to the central axis is 90% or more of the wire diameter of the Al bonding wire, it can be considered as a cross section including the central axis.

[0030] The reason why the Al bonding wire or Al bonding ribbon of the present invention can provide excellent reliability even in a high-speed temperature cycle test with a considerably large number of cycles is presumed to be as follows.

[0031] First, regarding high-speed temperature cycle reliability, the Si phase has a smaller linear expansion coefficient than Al, which contributes to reducing the difference in linear expansion coefficient between the Al bonding wire or ribbon and the semiconductor chip, thereby potentially reducing thermal stress. Furthermore, the particulate Si phase is thought to suppress the growth of cracks inside the Al bonding wire or ribbon. Up to about 10,000 cycles of high-speed TCT, the Si phase's effect of lowering the linear expansion coefficient is utilized, and adjusting the crystal orientation of the Al bonding wire or ribbon to enhance this effect is effective in improving reliability. However, as the number of temperature cycles increases beyond 15,000 cycles, the location and behavior affected by thermal strain accumulated inside the Al bonding wire or ribbon bonding interface and the electrode, which is the bonding partner, change. Therefore, in joints that can withstand 20,000 cycles, the effects of the Al phase's crystal orientation and the Si phase's particle size distribution, which affect the cracks at the Al bonding wire or ribbon bonding interface and the cracks inside the electrode, respectively, are thought to be stronger. Specifically, when measuring the crystal orientation of the Al phase in the L cross section, the angle difference with respect to the direction parallel to the central axis (RD direction) is 15° or less. <100> By having a crystal orientation ratio of 15% or more and 50% or less, the increase in stress within the Al bonding wire or Al bonding ribbon during high-speed TCT is alleviated, resulting in an enhanced effect of suppressing the propagation of cracks within the electrode. Furthermore, when the number of Si phases with a circular equivalent diameter of 0.5 μm or more and 0.8 μm or less in the L cross section is Ns, and the number of Si phases with a circular equivalent diameter of 0.5 μm or more in the L cross section is Nc, by having the ratio of Ns to Nc [Ns / Nc × 100 (%)] be 30% or more and 95% or less, the effect of suppressing the propagation of cracks at the wire or ribbon bonding interface is enhanced.

[0032] The present invention is characterized by the fact that the crystal orientation of the Al phase in the RD direction and the number distribution of the circle equivalent diameter of the Si phase interact with each other to enhance the effect, and these actions will be explained separately. <100> If the orientation ratio of the crystal orientation is in the range of 15% to 50%, the increase in stress in the wire or ribbon due to temperature rise and fall is alleviated, and the effect of this extends to the adjacent electrodes, suppressing the progression of cracks in the electrodes. In addition, by simultaneously satisfying the number distribution of Si phases with small circle equivalent diameters, it becomes possible to uniformize the distribution of thermal strain near the bonding interface, and the role of suppressing the progression of cracks at the bonding interface can be enhanced. In other words, the Al phase in the RD direction <100> By simultaneously combining the effect of reducing crack growth mainly inside the electrode by controlling the crystal orientation and the effect of reducing crack growth at the bonding interface by controlling the number distribution of Si phases with small circle equivalent diameters, it is possible to extend the time until failure occurs in the bonding part under the severe test conditions of about 20,000 temperature cycles in high-speed TCT. <100> Controlling the orientation alone is effective in suppressing cracks inside the wire or ribbon, and controlling the number distribution of Si phases with small equivalent circle diameters alone can suppress the progression of cracks inside the electrode, but controlling both of these simultaneously can enhance the synergistic effect.

[0033] Stress and strain may occur around Si phases with large equivalent circle diameters, and the Si phases themselves may become crack initiation sites. High-speed TCT involves more drastic temperature changes than standard TCT, which exacerbates the effects of these stress concentrations and strains. On the other hand, reducing the size of the Si phase grains is thought to reduce stress concentrations and strains relatively uniformly near the bond interface. Therefore, controlling the distribution of Si phases with small equivalent circle diameters relative to the total number of Si phases is effective for extending the life of high-speed temperature cycle tests. While the average equivalent circle diameter of Si phases has some effect under conditions that suppress crack propagation within the wire or ribbon during low-cycle tests, controlling the distribution of Si phases with small equivalent circle diameters relative to the total number of Si phases reduces test result variability and stably improves high-speed temperature cycle reliability during long-cycle tests, such as 20,000 cycles.

[0034] As described above, it is presumed that the Al bonding wire or Al bonding ribbon of the present invention can provide excellent high-speed temperature cycle reliability as described above, as a result of factors that contribute to improving temperature cycle reliability in high-speed temperature cycle tests being appropriately controlled over a wide range of cycle numbers.

[0035] -Si concentration- A Si concentration in the range of 3.0% by mass or more to 20.0% by mass or less helps reduce thermal distortion at the bonded portion and improve high-speed temperature cycle reliability. Specifically, a Si concentration of 3.0% by mass or more can significantly improve high-speed temperature cycle reliability. Furthermore, with advances and optimization of equipment and conditions used in the manufacture and bonding of wires, etc., higher Si concentrations have become tolerable while suppressing defects such as wire breakage during processing, deterioration of surface properties, reduction in initial bond strength due to hardening, and damage to semiconductor chips. A Si concentration of 20.0% by mass or less effectively suppresses these defects and achieves the desired high-speed temperature cycle reliability. From the perspective of achieving good high-speed temperature cycle reliability, the Si concentration in the Al bonding wire or Al bonding ribbon of the present invention is 3.0% by mass or more, preferably 3.5% by mass or more, more preferably 4.0% by mass or more, and even more preferably 4.2% by mass or more, 4.4% by mass or more, 4.5% by mass or more, 4.6% by mass or more, 4.8% by mass or more, or 5.0% by mass or more. Furthermore, from the viewpoint of realizing the desired high-speed 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 or Al bonding ribbon 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 or Al bonding ribbon is high, damage to the semiconductor chip is more 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 or Al bonding ribbon 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.

[0036] 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 or Al bonding ribbon 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 or Al bonding ribbon, it is effective to clean the surface with an acid or alkali depending on the adsorbed substance before analysis.

[0037] -Crystal orientation of Al phase in L cross section- From the viewpoint of obtaining excellent high-speed temperature cycle reliability even in high-speed TCT with a long number of cycles, when measuring the crystal orientation of the Al phase in the L cross section of the Al bonding wire or Al bonding ribbon, the angle difference with 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, preferably 20% or more, more preferably 22% or more, 24% or more, 26% or more, or 28% or more, further preferably 30% or more, and further more preferably 35% or more. <100> The upper limit of the orientation ratio of the crystal orientation is 50% or less, preferably 48% or less or 45% or less, more preferably 42% or less, and even more preferably 40% or less, from the viewpoint of obtaining excellent high-speed temperature cycle reliability even in high-speed TCT with a long number of cycles.

[0038] Here, the Al phase in the RD direction <100> By setting the crystal orientation ratio to 15% or more, the length of the crack inside the electrode is rapidly reduced during high-speed temperature cycle testing. <100> By keeping the orientation ratio of the crystal orientation below 50%, a good metal bond with the electrode can be obtained. <100> When the orientation ratio of the crystal orientation is set to 15% or more and 50% or less, the decrease in bonding strength after 20,000 cycles in a high-speed temperature cycle test is significantly suppressed.

[0039] -Measuring method for crystal orientation of Al phase- The orientation ratio of the Al phase crystal orientation in the L-section of an Al bonding wire or Al bonding ribbon can be measured using a SEM-EDS-EBSD instrument. Specifically, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) with information on the 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 phase and Si phase 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) that comes with the FE-SEM (Field Emission-Scanning Electron Microscope) device. Then, for the region identified as the Al phase, the analysis software that comes with the device is used to determine the Al phase in the RD direction. <100> The orientation ratio of the crystal orientation can be calculated. To calculate 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 in the RD direction <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 the Al phase was analyzed, and the RD direction <100> The orientation ratio of the crystal orientation is calculated.

[0040] 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.

[0041] In the present invention, the Al phase in the RD direction in the L cross section <110> The orientation ratio of the crystal orientation is the average (arithmetic mean) of the orientation ratio values ​​obtained by measuring at three or more locations. When selecting the measurement area, in order to ensure the objectivity of the measurement data, it is preferable to obtain measurement samples from the Al bonding wire or Al bonding ribbon to be measured at intervals of 50 cm or more along the central axis of the Al bonding wire or Al bonding ribbon and provide them for measurement. In the present invention, the measurement area for the crystal orientation 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 too large to measure the entire area, it can be adjusted to a range of less than 600 μm.

[0042] -Distribution of circle equivalent diameter of Si phase in L cross section- From the viewpoint of obtaining excellent high-speed temperature cycle reliability even in high-speed TCT with a long number of cycles, when the number of Si phases having a circle-equivalent diameter of 0.5 μm or more and 0.8 μm or less in the L cross section of the Al bonding wire or Al bonding ribbon is Ns, and the number of Si phases having a circle-equivalent diameter of 0.5 μm or more in the L cross section is Nc, the ratio of Ns to Nc [Ns / Nc × 100(%)] (hereinafter also referred to as the "small diameter ratio of Si phases") is 30% or more and 95% or less. The lower limit of the ratio [Ns / Nc × 100(%)] is preferably 32% or more, 35% or more, 38% or more, 40% or more, 42% or more, or 45% or more, more preferably 48% or more, even more preferably 50% or more or 52% or more, and particularly preferably 55% or more or 60% or more. The upper limit of the ratio [Ns / Nc × 100(%)] is preferably 92% or less, 90% or less, 88% or less, or 85% or less, more preferably 82% or less or 80% or less, even more preferably 78% or less or 75% or less, and particularly preferably 72% or less or 70% or less. In one embodiment, the ratio [Ns / Nc × 100(%)] is preferably 40% or more and 90% or less.

[0043] The reason why the proportion of Si phases with equivalent circle diameters of 0.5 μm to 0.8 μm is important is believed to be as follows: Si phases with equivalent circle diameters of 0.5 μm or more have a sufficiently large volume, which allows them to sufficiently reduce thermal expansion. Furthermore, from the perspective of the analytical accuracy of current EDS and EBSD analysis equipment, it is appropriate to target Si phases with equivalent circle diameters of 0.5 μm or more. On the other hand, Si phases with equivalent circle diameters of 0.8 μm or less sufficiently uniformize the stress and strain near the bonding interface due to the Si phase. Furthermore, the reason why a small diameter ratio of the Si phase [Ns / Nc × 100 (%)] in the range of 30% to 95% can achieve excellent high-speed temperature cycling reliability even in high-speed TCT with a long cycle count is believed to be as follows: When the small diameter ratio of the Si phase is 30% or more, there are sufficient Si phases with small equivalent circle diameters, which uniformly distributes thermal strain and stabilizes high-speed temperature cycling reliability. On the other hand, when the small diameter ratio of the Si phase is 95% or less, the total volume of the Si phase increases, and the effect of reducing the thermal expansion of the entire bonding region can be maintained at a high level, thereby sufficiently increasing the effect of improving the reliability of high-speed temperature cycles.

[0044] Here, each Si phase is formed in a particle shape, and it has been confirmed that the number of Si phase particles has a large effect on thermal distortion at the bonding interface. Therefore, the ratio of the number of Si phase particles can be used to determine high-speed temperature cycling reliability. However, because the effect of coarse particles is overestimated by particle area, it is difficult to accurately evaluate the correlation with high-speed temperature cycling reliability.

[0045] -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-section of 0.8 μm or more and 4.0 μm or less. The average diameter of the Si phase in the L-section of the Al bonding wire or Al bonding ribbon of the present invention is 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 3.0 μm or less, with the lower limit being more preferably 1.0 μm or more or 1.1 μm or more, even more preferably 1.2 μm or more or 1.5 μm or more.

[0046] -Method for measuring the circle equivalent diameter of the Si phase and calculating the small diameter ratio- This section describes a method for measuring the circle-equivalent diameter of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon. The circle-equivalent diameter of the Si phase in the L-section can be measured using a SEM-EDS-EBSD instrument. Specifically, similar to the measurement of the crystal orientation ratio of the Al phase described above, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. The detailed procedure is similar to that described above for measuring the crystal orientation ratio of the Al phase. That is, the crystal orientation of the region identified as the Si phase can be analyzed using the analysis software provided with the instrument. If the misorientation between measurement points is 15° or greater, it is considered 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 small diameter ratio and average diameter of the Si phase, areas where the crystal orientation cannot be measured or where the crystal orientation analysis is unreliable are excluded from the calculation. Therefore, in one embodiment, the small diameter ratio of the Si phase and 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 are 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) The crystal orientation of the region identified as Si phase is analyzed. If the misorientation between measurement points is 15° or greater, it is determined to be a grain boundary, and the circle-equivalent diameter of each grain is calculated. The number of grains identified as Si phase is tallied to determine the total number of Si phase particles, Nc. Here, Si phases with a circle-equivalent diameter of 0.5 μm or greater are considered. Considering the analytical accuracy of current ESD and EBSD analysis equipment, fine particles less than 0.5 μm are excluded. The number of Si phase particles, Ns, with a circle-equivalent diameter between 0.5 μm and 0.8 μm is also tallied. The ratio of Ns to Nc [Ns / Nc × 100 (%)] (the small diameter ratio of Si phase) is then calculated. The circle-equivalent diameters of each grain are then averaged to calculate the average diameter of the Si phase. For the average calculation, the average value obtained using the area average (area-weighted average) available in the software provided with the equipment is used.

[0047] An example of the measurement results is shown in Figure 4. The horizontal axis shows the circle equivalent diameter of the Si phase, with each interval having a width of 0.25 μm, and the vertical axis shows the number of particles. The range of 0.5 μm or more and less than 0.8 μm is shown with a double-headed arrow, and the particle number ratio in this interval [Ns / Nc × 100 (%)] is 50%. In a high-speed temperature cycle test of this Al bonding wire, strength degradation was kept low even after 20,000 cycles, confirming that it has good high-speed temperature cycle reliability.

[0048] -Crystal orientation of the Si phase in the L cross section- When evaluating the bond strength of multiple Al bonding wires or Al bonding ribbons during high-speed TCT, it was confirmed that multiple bond joints do not deteriorate simultaneously, but rather that the bond strength degradation varies. That is, even when the average bond strength is roughly maintained as the number of cycles of high-speed temperature cycling increases, the strength degradation begins at the joints of a few Al bonding wires or Al bonding ribbons, resulting in variability in bond strength degradation. If the bond strength degradation of even a few Al bonding wires or Al bonding ribbons progresses, there is a concern that high currents will increase the load on other Al bonding wires or Al bonding ribbons, leading to sudden failures. To achieve the reliability required for next-generation power semiconductor devices, it is necessary to not only manage the lifespan based on the average bond strength during high-speed TCT, but also to control the variability in bond strength.

[0049] From the viewpoint of obtaining better high-speed temperature cycle reliability in high-speed TCT with a long cycle number and suppressing the variation in bonding strength, when measuring the crystal orientation of the Si phase in the L cross section of the Al bonding wire or Al bonding ribbon, the angle difference with respect to the direction perpendicular to the central axis (ND direction, Normal Direction) is 15° or less. <100> Crystal orientation and <111> The total orientation ratio of the crystal orientation (hereinafter referred to as "ND direction Si phase") <100> + <111> The ratio of the Al phase in the RD direction is preferably in the range of 20% to 60%. <100> In addition to controlling the orientation ratio of the crystal orientation and the small diameter ratio of the Si phase, <100> + <111> By setting the total ratio within this range, local stress concentration is dispersed, and the propagation of cracks at the bonding interface is reduced, resulting in a reduction in the variation in shear strength after severe high-speed TCT at 20,000 cycles or more. <100> Crystal orientation and <111> Crystal orientation and RD direction of Al phase <100> It is thought that the alignment of the crystal orientations of the Si phases in the ND direction suppresses local delamination at the bonding interface even when the number of cycles increases during high-speed TCT, which involves rapid temperature change. <100> + <111> The total ratio is more preferably 25% or more, further preferably 26% or more, 28% or more, or 30% or more, from the viewpoint of obtaining better high-speed temperature cycle reliability in high-speed TCT with a long number of cycles and from the viewpoint of suppressing variations in bonding strength. <100> + <111> The total ratio is more preferably 58% or less, and even more preferably 55% or less, 52% or less, 50% or less, 48% or less, or 45% or less, from the viewpoint of obtaining better high-speed temperature cycle reliability in high-speed TCT with a long number of cycles and from the viewpoint of suppressing variations in bonding strength.

[0050] -Method for measuring the crystal orientation of the Si phase- The orientation ratio of the crystal orientation of the Si phase in the L cross section of an Al bonding wire or Al bonding ribbon can be measured using a SEM-EDS-EBSD device. Specifically, as with the measurement of the orientation ratio of the crystal orientation of the Al phase, 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. A more detailed procedure can be the same as that described above in relation to the measurement of the orientation ratio of the crystal orientation of the Al phase. That is, for the region identified as the Si phase, the orientation ratio of the Si phase in the ND direction can be determined by using the analysis software provided with the device. <100> Crystal orientation and <111> The orientation ratio of the crystal orientations and their total can be calculated. In calculating the orientation ratio, a partial ratio is used, which is calculated as a population of the area of ​​only the crystal orientations that can be identified based on a certain reliability within the measurement area. Therefore, in one embodiment, the orientation ratio of the crystal orientation 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) 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 analyzed using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are separated and analyzed. 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 is analyzed using the Al and Si crystal information in the material file. (3) The crystal orientation of the region identified as the Si phase was analyzed, and the Si phase in the ND direction was identified. <100> The orientation ratio of the crystal orientation and <111> The orientation ratio of the crystal orientation is calculated.

[0051] In the present invention, the Si phase in the ND direction in the L cross section <100> The orientation ratio of the crystal orientation and <111> The orientation ratio of the crystal orientation is the arithmetic mean value of the orientation ratio values ​​obtained by measuring at least three locations. The tolerance setting range in step (2) above, the method for obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by the EBSD method are as described above for the measurement of the orientation ratio of the crystal orientation of the Al phase.

[0052] -Shape of the Si phase in the L cross section- When bonding an Al bonding wire or Al bonding ribbon to an electrode on a conductor chip or an electrode on a lead frame or substrate, a bonding failure, such as peeling of the Al bonding wire or Al bonding ribbon from the electrode, can lead to product defects and reduced manufacturing yields. Therefore, it is necessary to obtain good bonding strength at each bond. In this regard, applying strong ultrasonic vibrations or loads to the first bonded portion to obtain good bonding strength can damage the semiconductor chip. In particular, when using Al bonding wire or Al bonding ribbon that has been strengthened by adding Si or other additives, its hardness can easily damage the semiconductor chip during the first bonded portion. Adjusting the ultrasonic vibrations 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") due to factors such as high deformation resistance and unstable deformation direction, making it difficult to stably secure the bonded area. These problems during the initial bonding of the first bond can ultimately lead to reduced reliability and instability in high-speed temperature cycles, so it is more desirable for Al bonding wire or Al bonding ribbon, which has been strengthened by adding Si or other elements, to exhibit excellent first bond strength.

[0053] The inventors have found that controlling the shape of the Si phase (the ratio (e / f) of the short side length e to the long side length f of the Si phase in the L cross section) improves the adhesion in the central axis direction of the interface between the Si phase and the Al phase, thereby controlling the interfacial slippage when ultrasonic vibration and load are applied, thereby increasing the initial shear strength immediately after joining (first bond strength). Furthermore, one of the effects of increasing the initial shear strength is the stabilization of the failure time (lifetime) in high-speed temperature cycle tests.

[0054] Specifically, the inventors have found that the Si content is 3.0 mass % or more and 20.0 mass % or less, and that the Al phase in the RD direction of the L cross section is <100> In the course of investigating Al bonding wires or Al bonding ribbons in which the ratio of the short side length e to the long side length f of the Si phase falls within a specific range, we discovered that the shape of the Si phase in the L-section influences the first bond strength. Specifically, we found that a ratio (e / f) of the short side length e to the long side length f of the Si phase in the L-section, which is between 0.20 and 0.70 on average, not only suppresses the deterioration of bond strength after high-speed TCT but also improves the first bond strength and reduces the variability of the bond strength. This ratio (e / f) is an index of flatness. Further explanation will be given with reference to Figure 3. Figure 3 is a schematic diagram of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon, with the central axis of the Al bonding wire or Al bonding ribbon corresponding to the horizontal direction (left-right direction) in Figure 3 and the direction perpendicular to the central axis corresponding to the vertical direction (up-down direction) in Figure 2. Regarding the Si phase in the L-section, the "short side length e" corresponds to the dimension indicated by the symbol e in Figure 3. Furthermore, for the Si phase in the L cross section, the above-mentioned "long side length f" corresponds to the dimension indicated by the symbol f in Figure 3. Hereinafter, the ratio (e / f) of the short side length e to the long side length f of the Si phase in the L cross section will also be referred to as the "Si phase shape ratio (e / f)." The value of the Si phase shape ratio (e / f) can be found using the Grain Shape Aspect Ratio in the analysis software provided with the device.

[0055] The reason why the first bond strength can be improved by controlling the average value of the shape ratio (e / f) of the Si phase in the Al bonding wire or Al bonding ribbon of the present invention is presumed to be as follows. The reason why the first bond strength decreases is because cracks propagate along the central axis of the Al bonding wire or Al bonding ribbon, or along a direction close to it, inside the Al bonding wire or Al bonding ribbon or at the bond interface. Here, due to plastic processing by wiredrawing, the Si phase tends to be aligned so that the direction of its long side length f is the central axis of the Al bonding wire or Al bonding ribbon, or a direction close to it. When the average value of the shape ratio (e / f) of the Si phase is in the range of 0.20 to 0.70, the Si phase takes on a shape such as an ellipse or column, which exerts the effect of alleviating thermal stress in the central axis direction of the Al bonding wire or Al bonding ribbon, and thus it is believed that crack propagation along the central axis direction of the Al bonding wire or Al bonding ribbon, or a direction close to it, can be suppressed. In order to improve the first bonding strength, it is sufficient that the average value of the shape ratio (e / f) of the Si phase in the L cross section is within the above-mentioned preferred range, and it is not necessary that the shape ratio (e / f) of all the Si phases be in the range of 0.20 or more and 0.70 or less. For example, the Si phase may contain an Si phase having an shape ratio (e / f) of less than 0.20, or may contain an Si phase having an shape ratio (e / f) of more than 0.70.

[0056] From the viewpoint of improving the first bond strength, thereby reducing the variation in bond strength in high-speed TCT, and further realizing the reliability required for next-generation power semiconductor devices, the average value of the shape ratio (e / f) 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 0.25 or more, even more preferably 0.30 or more, and particularly preferably 0.32 or more, 0.34 or more, or 0.35 or more. From the viewpoint of improving the first bond strength, the upper limit of the average value of the shape ratio (e / f) of the Si phase is more preferably 0.65 or less, or 0.60 or less, even more preferably 0.58 or less, 0.56 or less, or 0.55 or less.

[0057] -Measuring method for the shape ratio (e / f) of the Si phase- We will now describe a method for measuring the shape ratio (e / f) of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon. Similar to the crystal orientation measurement and the circle-equivalent diameter measurement of the Si phase, this measurement can be performed using an SEM-EDS-EBSD instrument. Specifically, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. The detailed procedure is similar to that described above for measuring the crystal orientation ratio. That is, the crystal orientation of the region identified as the Si phase can be analyzed using the analysis software provided with the instrument. If the misorientation between measurement points is 15° or greater, it is considered a grain boundary, and the shape ratio (e / f) is calculated. The average value of the shape ratios (e / f) of each Si phase is defined as the average shape ratio (e / f) of the Si phase. In the process of calculating the shape ratio (e / f) of the Si phase, areas where the crystal orientation cannot be measured or where the measurement can be performed but the reliability of the orientation analysis is low are excluded from the calculation. Therefore, in one embodiment, the average value of the shape ratio (e / f) 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 shape ratio (e / f) of each grain is calculated. The shape ratios (e / f) of each grain are then averaged to calculate the average shape ratio (e / f) of the Si phase. Here, the average value of the Si phase shape ratio (e / f) is the value of the Grain Shape Aspect Ratio (hereinafter referred to as the "grain shape aspect ratio") in the analysis software. This value is obtained by averaging the grain shape aspect ratios of each grain. The grain shape aspect ratio is calculated by calculating the ratio (e / f) of the short side length (e) (Grain Shape Minor Axis) to the long side length (f) (Grain Shape Major Axis) of one grain. For the average calculation, the average value obtained by the Area Average (area-weighted average) selectable in the software provided with the device is used. By adopting the average value obtained by area averaging, it is possible to reduce the variation in bonding strength in high-speed temperature cycle tests with a long number of cycles, and to accurately measure and judge whether the conditions related to the average value of the shape ratio (e / f) of the Si phase are met, which is suitable for achieving even better the high-speed temperature cycle reliability required for next-generation power semiconductor devices.

[0058] When measuring the average value of the shape ratio (e / f) of the Si phase in the L cross section, the tolerance setting range in the procedure (2) above and the measurement area of ​​the crystal orientation by the EBSD method are the same as those described above for measuring the orientation ratio of the crystal orientation of the Al phase.

[0059] In addition to the above, there are several other methods for measuring the circle-equivalent diameter and the shape ratio (e / f) of the Si phase, including binarization processing from an observed image of the L-section. However, in the present invention, it is preferable to use the method of combining the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD, as described above, for reasons such as the fact that multiple measurement functions are provided and multiple characteristics such as the above-mentioned crystal orientation, circle-equivalent diameter of the Si phase, and the shape ratio (e / f) of the Si phase can be obtained in a single measurement, automatic analysis is possible, and measurement is easy using widely available equipment and analysis techniques.

[0060] -Addition of Sr, Na, Fe, and P- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Sr, Na, Fe, and P (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.

[0061] The Al bonding wire or Al bonding ribbon of the present invention further contains one or more of Sr, Na, Fe, and P in a total amount of 10 mass ppm to 800 mass ppm, thereby reducing the frequency of wire breakage during wiredrawing of the Al bonding wire or Al bonding ribbon. 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 the wiredrawing process. This is thought to be due in part to the fact that Si phase particles 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 alleviating stress concentration during wiredrawing and reducing wire breakage. It is thought that the addition of the first element group, along with controlling the orientation ratio of the crystal orientation of the Al phase in the RD direction in the L cross section and the small diameter ratio of the Si phase, enhances the effect of alleviating stress concentration during wiredrawing.

[0062] 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.

[0063] 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, Fe, or P.

[0064] 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.

[0065] 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.

[0066] When the Al bonding wire or Al bonding ribbon of the present invention contains Fe in the first 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, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the Fe 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 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, 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 Fe 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.

[0067] 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.

[0068] -Addition of Ti, Ni, Mg, and Cu- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Ti, Ni, Mg, and Cu (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.

[0069] By further containing at least one of Ti, Ni, Mg, and Cu in a total amount of 100 ppm by mass to 2000 ppm by mass, the Al bonding wire or Al bonding ribbon of the present invention can suppress scratches and abrasions on the surface of the Al bonding wire or Al bonding ribbon, resulting in a smooth surface. Al alloys containing Si at a high concentration of 3.0% by mass to 20.0% by mass can 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 believed 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 controlling the orientation ratio of the Al phase crystal orientation in the RD direction in the L cross section and the small diameter ratio of the Si phase, as well as 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.

[0070] 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.

[0071] 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, or all four 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 Ti, Ni, Mg, or Cu.

[0072] 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.

[0073] 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. 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 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 Ni 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.

[0074] 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.

[0075] When the Al bonding wire or Al bonding ribbon of the present invention contains Cu from the second element group, the Cu concentration may be 0 mass ppm, preferably 1 mass ppm or more, 3 mass ppm or more, 5 mass ppm or more, 8 mass ppm or more, 10 mass ppm or more, 30 mass ppm or more, 50 mass ppm or more, or 80 mass ppm 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 Cu concentration is more preferably 100 mass ppm or more, even more preferably 150 mass ppm or more, 200 mass ppm or more, 250 mass ppm or more, or 300 mass ppm. The upper limit of the Cu concentration is preferably 10,000 mass ppm or less, 8,000 mass ppm or less, 5,000 mass ppm or less, or 3,000 mass ppm 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 Cu 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.

[0076] 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.

[0077] 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, Fe, P, Ti, Ni, Mg, and Cu, and the Al bonding wire or Al bonding ribbon of the present invention may further contain elements other than Al, Si, Sr, Na, Fe, P, Ti, Ni, Mg, and Cu. 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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 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.

[0082] The Al bonding wire or Al bonding ribbon of the present invention can provide excellent high-speed temperature cycle reliability even in high-speed temperature cycle tests with a long number of cycles. Therefore, the Al bonding wire or Al bonding ribbon of the present invention can be suitably used as an Al bonding wire or Al bonding ribbon for semiconductor devices. The Al bonding wire or Al bonding ribbon of the present invention can be particularly suitably used as an Al bonding wire or Al bonding ribbon for power semiconductor devices, and more suitably used as an Al bonding wire or Al bonding ribbon for SiC power semiconductor devices.

[0083] -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.

[0084] The Al and alloying elements used as raw materials preferably have a high purity. Al preferably has a purity of 99.5% by mass or more, with the remainder consisting of inevitable impurities, more preferably a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and even more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Si, first element group, second element group, and other elements used as alloying elements preferably have a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for Al bonding wire can be produced by loading the Al raw material and the alloying element raw materials into a graphite or alumina crucible processed to obtain a cylindrical ingot and melting them using an electric furnace or high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm, taking into account the workability in the subsequent processing steps. The atmosphere in the furnace during melting is preferably an inert or reducing atmosphere to prevent excessive oxidation of Al, Si, the first element group, the second element group, and other elements that make up the wire. The maximum temperature that the molten metal reaches during melting is preferably in the range of 800°C or higher and lower than 1050°C, taking into consideration factors such as ensuring the fluidity of the molten metal and making it easier to control the shape and size of the Si phase during solidification. Cooling methods after melting can include water cooling, furnace cooling, and air cooling.

[0085] The cylindrical ingot obtained by melting is subjected to solution treatment by heating at high temperature, and then repeatedly drawn using a die to produce wire of the desired diameter. After the drawing process, the wire is subjected to final heat treatment in an electric furnace and can be used as Al bonding wire.

[0086] In order to control the crystal orientation of the Al phase in the L cross section, the small diameter ratio of the Si phase, the average diameter of the Si phase, and the crystal orientation of the Si phase, it is effective to control the heat treatment conditions such as solution treatment, homogenization treatment, and final heat treatment, as well as the wire drawing conditions, etc. During the wire drawing process, it is effective to use a lubricant to ensure lubrication at the contact interface between the wire and the die.

[0087] An example of manufacturing conditions for controlling the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L cross-section to be in the range of 15% or more and 50% or less, and controlling the small diameter ratio of the Si phase to be in the range of 30% or more and 95% or less, is shown below.

[0088] <Control of the <100> Crystal Orientation of the Al Phase in the RD Direction> Regarding the wire drawing processing conditions, it is effective to set the wire area reduction rate per die used during wire drawing to be in the range of 10% or more and less than 20%. Here, if the wire area reduction rate per die is P1, P1 is expressed by the following formula.

[0089] 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.

[0090] By controlling the processing strain by adjusting the average value of the die area reduction rate to be in the range of 10% or more and less than 20%, it becomes possible to adjust the <100> crystal orientation of the Al phase in the RD direction. For example, increasing the area reduction rate and increasing the processing strain helps to control the ratio of the <100> crystal orientation of the Al phase in the RD direction, which is a recrystallized structure when heat treatment is applied.

[0091] By adjusting the conditions of the intermediate heat treatment, it becomes easier to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction. The intermediate heat treatment is a heat treatment performed during the process of machining from an ingot to the final wire diameter. The number of intermediate heat treatments is preferably in the range of 3 to 4 times, and the wire diameter for performing the intermediate heat treatment can be selected. Among them, an intermediate heat treatment (intermediate annealing) with a temperature range of 250°C or more and less than 400°C and a time of 1 hour or more and less than 48 hours is 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 wire diameter of the final wire diameter, which helps to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction at the final wire diameter to be in the range of 15% or more and 50% or less. By performing the intermediate heat treatment under these conditions, the processing strain of the Al phase is reduced, and mild recrystallization occurs, reducing the processed structure of the Al phase at the final wire diameter, increasing the progress of recrystallization of the Al phase in subsequent heat treatments, and promoting the rotation of the crystal orientation, making it easier to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction. On the other hand, if the intermediate heat treatment temperature is 400°C or more, there is a concern that the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction will become unstable.

[0092] <Control of the small-diameter ratio of the Si phase> Optimizing the intermediate heat treatment conditions and the final heat treatment conditions in a set is effective for controlling the small-diameter ratio of the Si phase. Specifically, when the temperature of the intermediate heat treatment of the wire diameter closest to the final wire diameter (final) is Tm (°C) and the temperature of the final heat treatment at the final wire diameter is Tc (°C), if the temperature Tm of the intermediate heat treatment is 50°C or more higher than the temperature Tc of the final heat treatment, it becomes easier to adjust the small-diameter ratio of the Si phase to be 30% or more and 95% or less. Specifically, by increasing the intermediate heat treatment temperature, the Si dissolved in the Al phase can be homogenized, and by lowering the temperature of the final heat treatment process, the solid solution concentration of Si in the Al phase can be reduced. By combining these temperatures, the number of minute Si phases can be increased, and the small-diameter ratio of the Si phase can be increased. Adjusting the temperature of the last intermediate heat treatment among multiple intermediate heat treatments is more effective, and it is considered that the increase in the number of minute Si phases can be promoted by utilizing the increased dislocations and the like in the subsequent processing steps.

[0093] Regarding the final heat treatment conditions, it is effective to adjust the temperature range within 200°C or higher and less than 360°C, and the time within 2 hours or longer and less than 20 hours. When the recovery and recrystallization of the Al phase proceed by the final heat treatment, simultaneously, the amount of Si dissolved in the Al phase changes depending on the heat treatment temperature, and the recrystallization temperature changes. By adjusting the progress of recrystallization by the final heat treatment, it becomes easy to control the small-diameter ratio of the Si phase. For example, by adjusting the final heat treatment to a low temperature or short time, the small-diameter ratio of the Si phase tends to increase. Also, by adjusting the final heat treatment conditions, it becomes easy to control the average value of the equivalent circle diameter of the Si phase (average diameter of the Si phase).

[0094] <Control of the shape ratio (e / f) of the Si phase> To adjust the shape ratio (e / f) of the Si phase in the L cross-section, it is effective to control the conditions of the above-described two-step heat treatment (solution treatment, homogenization treatment) and the final heat treatment.

[0095] The temperature range of the solution treatment of the ingot is preferably 400°C or higher and less than 550°C, and the time is 1 hour or longer and less than 6 hours, and the subsequent homogenization treatment is 250°C or higher and less than 350°C, and the time is 2 hours or longer and less than 6 hours. By the solution treatment, the segmentation and growth of the Si phase crystallized during the solidification process occur, and by the homogenization treatment, the solid solution and precipitation of Si occur at the interface of the Si phase, whereby the shape of the Si phase can be controlled. For example, when the solution treatment is performed at a high temperature, the shape ratio (e / f) of the Si phase tends to become small.

[0096] <Control of the crystal orientation of the Si phase in the ND direction> To adjust the crystal orientation of the Si phase in the ND direction, it is effective to perform a two-step heat treatment (solution treatment, homogenization treatment) on the ingot and control the area reduction ratio of the wire drawing process.

[0097] It is effective to set the temperature range of the solution treatment to 450°C or higher and lower than 550°C, and the time range to 1 hour or higher and lower than 6 hours. After this solution treatment, it is effective to perform homogenization treatment at 250°C or higher and lower than 350°C, and the time range to 2 hours or higher and lower than 6 hours. This can promote the division and growth of the Si phase that crystallizes during the solidification process, and the crystal orientation of the Si phase in the ND direction can be improved. <100> Crystal orientation and <111> The orientation of the crystal orientation can be adjusted.

[0098] It is also effective to incorporate wiredrawing in which the die area reduction rate is a high rate, in the range of more than 20% but less than 30%, into the wiredrawing process to increase the processing strain and control the orientation of the crystal orientation of the Si phase. When two or more wiredrawing processes are performed, the die area reduction rate should be more than 20% but less than 30% in at least one wiredrawing process. By adjusting the wire area reduction rate within the above range, the entire Al bonding wire or Al bonding ribbon can be significantly deformed during die processing, thereby increasing the processing strain even within the Al bonding wire or Al bonding ribbon. The Si phase is then aligned in the central axis direction of the Al bonding wire or Al bonding ribbon, and the processing strain within the Si phase is adjusted. Even if it is not easy to adjust the crystal orientation of the Si phase using only the two-stage heat treatment (solution treatment and homogenization treatment) for the ingot described above, by incorporating adjustment of the die area reduction rate within the above range, the Si phase in the ND direction can be aligned. <100> Crystal orientation and <111> It becomes possible to adjust the orientation ratio of the crystal orientations.

[0099] As mentioned above, the above is an example of the manufacture of Al bonding wire, which is a wire rod, as a representative example of Al bonding wire or Al bonding ribbon. The same procedure can also be used to manufacture Al bonding ribbon, which is a strip material. The temperature and time of the heat treatment can be approximately the same as those described above. Furthermore, when manufacturing Al bonding ribbon by rolling, the die area reduction rate can be adjusted by replacing it with the rolling reduction rate.

[0100] [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.

[0101] 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.

[0102] 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.

[0103] 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]

[0104] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the examples shown below.

[0105] (sample) The sample preparation method will be described. The raw material Al had a purity of 4N (99.99% by mass or more), with the remainder consisting of inevitable impurities. The alloying elements Si, the first element group (Sr, Na, Fe, P), the second element group (Ti, Ni, Mg, Cu), and other elements (Mn, Zn) 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, and the maximum temperature of the molten metal during melting was 800°C or higher but lower than 1050°C. The cooling method after melting was air cooling (cooling in the air) or water cooling (cooling in water).

[0106] 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 a Φ300 μm Al bonding wire. Furthermore, using the Φ300 μm Al bonding wire 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 500°C or higher but lower than 550°C, and the time was 2 hours or higher but lower than 4 hours. After the solution treatment, a homogenization treatment was performed continuously during cooling. The temperature range of the homogenization treatment was 250°C or higher but lower than 350°C, and the time was 2 hours or higher but lower than 5 hours. The cooling method after the homogenization treatment was air cooling in the atmosphere.

[0107] The number of intermediate heat treatments ranged from three to four. The wire diameter after intermediate heat treatment relative to the final wire diameter was 6.5 to 7.0 times for the first intermediate annealing, 4.0 to 5.0 times for the second, and 2.0 to 3.0 times for the third. When intermediate annealing was performed four times, the wire diameter was 7.5 to 8.5 times the final wire diameter. The temperature range for the first and second intermediate heat treatments was 300°C or higher but lower than 370°C, and the time was 1 hour or higher but lower than 3 hours, while the temperature range for the third and fourth intermediate heat treatments was 250°C or higher but lower than 400°C, and the time was 2 hours or higher but lower than 40 hours.

[0108] A commercially available lubricant was used during wire drawing, and the wire area reduction rate per die during wire drawing was 10.0% or more and less than 30.0%. The wire area reduction rate was adjusted according to the wire diameter of the die. The temperature range of the final heat treatment was 200°C or more and less than 350°C, and the time of the final heat treatment was 2 hours or more and less than 20 hours. The temperature of the final heat treatment (Tc) was selected in the temperature range 50 to 100°C lower than the temperature (Tm) of the third or fourth intermediate annealing described above.

[0109] In some examples, the wire was drawn using a die with a die angle of 14° or more and less than 18°.

[0110] (Method for measuring element content) The concentration analysis of elements contained in the Al bonding wire or Al bonding ribbon was performed using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) ("PS3520UVDDII" manufactured by Hitachi High-Tech Science Corporation) or an ICP-MS (Inductively Coupled Plasma-Mass Spectrometer) ("Agilent 7700x ICP-MS" manufactured by Agilent Technologies, Inc.).

[0111] (Method for measuring the orientation ratio of the crystal orientation of the Al phase and Si phase) The L-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 orientations of the Al phase and Si phase were measured.

[0112] 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 chiscan), and OIM Anaysis (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 the measurement area 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.

[0113] -Crystal orientation of Al phase- To measure the orientation ratio of the Al phase crystal orientation in the L-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. In detail, the measurement was 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) 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 was calculated. The crystal orientation to be investigated is the typical crystal orientation of Al metal. <111> , <110> , <100> At least three of these were selected, and if necessary, a crystal orientation with a high ratio was selected. Here, the partial ratio was used for the orientation ratio of the crystal orientation.

[0114] Al phase in RD direction <100> The orientation ratio of the crystal orientation was determined as the average value (arithmetic mean) of the values ​​obtained by the above steps (1) to (3) for the three measurement regions.

[0115] -Crystal orientation of the Si phase- To measure the orientation ratio of the Si phase crystal orientation in the L cross section of the Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the orientation ratio of the Al phase crystal orientation, 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. In detail, after carrying out the above steps (1) and (2), the measurement was carried out according to the following step (3). (3) The crystal orientation of the region identified as the Si phase was analyzed, and the Si phase in the ND direction was identified. <100> The orientation ratio of the crystal orientation and <111> The orientation ratio of the crystal orientation was calculated. The partial ratio was used for the orientation ratio of the crystal orientation.

[0116] ND direction of Si phase <100> The orientation ratio of the crystal orientation and <111> The orientation ratio of the crystal orientation was determined as the average value (arithmetic mean) of the values ​​obtained by the above steps (1) to (3) for the three measurement regions.

[0117] (Small diameter ratio of Si phase [Ns / Nc×100(%)]) To measure the small diameter ratio of the Si phase in the L cross section [Ns / Nc × 100 (%)], we used a SEM-EDS-EBSD device, similar to the measurement of the orientation ratio of the Al phase crystal orientation, and combined the information on the Al and Si concentrations obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD. In detail, after carrying out the above steps (1) and (2), we carried out the measurement according to the following step (3). (3) The crystal orientation of the region identified as Si phase was analyzed, and if the misorientation between measurement points was 15° or more, it was determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain was calculated. The number of crystal grains identified as Si phase was tallied to determine the total number of Si phase particles, Nc. Here, Si phases with a circle-equivalent diameter of 0.5 μm or more were targeted. Considering the analytical accuracy of current EDS and EBSD analysis equipment, fine particles less than 0.5 μm were excluded. Next, the number of Si phases, Ns, with a circle-equivalent diameter in the range of 0.5 μm to 0.8 μm was tallied. The ratio of Ns to Nc [Ns / Nc × 100 (%)] (the small diameter ratio of Si phases) was calculated.

[0118] The small diameter ratio of the Si phase was determined as the average value (arithmetic mean) of the values ​​obtained for the three measurement regions by the above procedures (1) to (3).

[0119] (Method for measuring the average diameter of the Si phase) To measure the average diameter of the Si phase in the L-section of the Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the crystal orientation of the Al phase, 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. In detail, after carrying out the above steps (1) and (2), the measurement was carried out according to the following step (3). (3) The crystal orientation of the region identified as the Si phase was analyzed, and if the misorientation between measurement points was 15° or more, it was determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain was calculated. The circle-equivalent diameters of each crystal grain were then averaged to calculate the average diameter of the Si phase. Here, the average value calculated by area averaging (area-weighted average) was used for the average calculation. In addition, when calculating the average diameter of the Si phase in the L cross section, only Si phases with a diameter (circle-equivalent diameter) of 0.5 μm or more were considered.

[0120] The average diameter of the Si phase was determined as the average (arithmetic mean) of the values ​​obtained for the three measurement regions according to the above procedures (1) to (3).

[0121] (Method for measuring the shape of the Si phase) To measure the shape ratio (e / f) of the Si phase in the L cross section of the Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the orientation ratio of the crystal orientation of the Al phase, 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. In detail, after carrying out the above steps (1) and (2), the measurement was carried out according to the following step (3). (3) The crystal orientation of the region identified as the Si phase was analyzed, and if the misorientation between measurement points was 15° or more, it was determined to be a grain boundary, and the shape ratio (e / f) of each grain was calculated. The shape ratios (e / f) of each grain were then averaged to calculate the average value of the Si phase shape ratio (e / f). Here, the average value of the Si phase shape ratio (e / f) was calculated using the Grain Shape Aspect Ratio value ("Grain Shape Aspect Ratio") from the analysis software. The software automatically calculated the ratio (e / f) of the short side length (e) (Grain Shape Minor Axis) to the long side length (f) (Grain Shape Major Axis) of one grain. Here, the average value calculated by area averaging (area-weighted average) was used for the average calculation.

[0122] The shape ratio (e / f) of the Si phase was determined as the average value (arithmetic mean) of the values ​​obtained for the three measurement regions by the above procedures (1) to (3).

[0123] (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.

[0124] (Method for evaluating reliability of high-speed temperature cycles) A commercially available high-speed thermal shock tester was used for the high-speed temperature cycle test (high-speed TCT). In the high-speed TCT, hot air is blown onto the sample to rapidly heat it. The sample used for the high-speed TCT had a semiconductor chip mounted on a substrate, and electrodes on the semiconductor chip and those on the substrate were connected with Al bonding wire or Al bonding ribbon. The sample placed in the sample chamber of the high-speed thermal shock tester was subjected to repeated thermal loads, consisting of heating and cooling cycles. The minimum temperature during cooling was -50°C, and the maximum temperature during heating was 175°C. The heating time, including the heating time, was 20 seconds, and the cooling time, including the cooling time, was 40 seconds. After 20,000 cycles, the sample was removed and the shear strength of the first joint was tested. The shear strength (shear strength) of the first joint used to evaluate the high-speed temperature cycle reliability was the average shear strength of 10 randomly selected first joints. The ratio (percentage) of the average shear strength after high-speed TCT to the average shear strength before the test was taken as the strength retention rate. The higher this strength retention rate, the better the reliability of the joint. A strength retention rate of 85% or higher was judged to be excellent and given a rating of "3," 75% or more but less than 85% was judged to be excellent and given a rating of "2," 70% or more but less than 75% was judged to require improvement and given a rating of "1," and less than 70% was judged to have practical problems and given a rating of "0." "3" and "2" were judged to be pass, while "1" and "0" were judged to be fail. The evaluation results are shown in the "High-speed temperature cycle reliability" column in the table. The high-speed temperature cycle reliability requirement for next-generation SiC semiconductors corresponds to 20,000 cycles.

[0125] (Method for evaluating the variation in bond strength in high-speed temperature cycle testing) In the high-speed TCT described above, the shear strength of 20 first-bonded sections was measured after 20,000 cycles. To evaluate the variability of bond strength during the high-speed TCT, the unbiased standard deviation (σ) of shear strength was calculated. Because the unbiased standard deviation of the shear strength of the first-bonded section is not significantly affected by the conditions of the first-bonding section, it is useful as an index for appropriately evaluating the characteristics of Al bonding wire or Al bonding ribbon. If σ is less than 30 gf, the variability of bond strength is particularly small, indicating excellent stability, and a rating of "3" is given. If σ is between 30 gf and 50 gf, the variability of bond strength is small, indicating excellent stability, and a rating of "2" is given. If σ is between 50 gf and 70 gf, the variability of bond strength is within the acceptable range, indicating good stability, and a rating of "1" is given. If σ is 70 gf or more, the variability of bond strength is large, indicating practical problems, and a rating of "0" is given. The evaluation results are shown in the column "Variation in high-speed TCT bonding strength" in the table.

[0126] (1st joint strength evaluation method) 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.

[0127] (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.

[0128] (Evaluation method for surface scratches and scrapes) The surface quality of the Al bonding wire or Al bonding ribbon was evaluated, focusing on scratches and abrasions. The Al bonding wire had a diameter of 300 μm. The Al bonding ribbon had a thickness of 100 μm and a width of 600 μm. Three measurement areas were randomly selected at intervals of at least 1 m along the central axis of the Al bonding wire or Al bonding ribbon. Three approximately 2 cm lengths were taken from each of the three areas, 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 or 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 for 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.

[0129] The evaluation results of the Examples and Comparative Examples are shown in Tables 1 to 4. Examples 1 to 44 and Comparative Examples 1 to 10 in Tables 1 to 3 are the results for Al bonding wires, and Examples B1 to B3 and Comparative Example B1 in Table 4 are the results for Al bonding ribbons.

[0130] [Table 1]

[0131] [Table 2]

[0132] [Table 3]

[0133] [Table 4] [Explanation of symbols]

[0134] 1. Al bonding wire 10 center axis 11 L cross section 2. Al bonding ribbon 20 center axis 21 L cross section 3. Al bonding wire or Al bonding ribbon 31 Si phase 32 Al bonding wire or Al bonding ribbon central axis direction

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 crystal orientation of the Al phase in the L cross section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <100> crystal orientation, which has an angle 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, An Al bonding wire or Al bonding ribbon, in which the ratio of Ns to Nc [Ns / Nc x 100 (%)] is 30% or more and 95% or less, where Ns is the number of Si phases having a circle equivalent diameter of 0.5 μm or more and 0.8 μm or less in the L cross section, and Nc is the number of Si phases having a circle equivalent diameter of 0.5 μm or more in the L cross section.

2. 2. The Al bonding wire or Al bonding ribbon according to claim 1, wherein the ratio of Ns to Nc [Ns / Nc x 100 (%)] is 40% or more.

3. An Al bonding wire or Al bonding ribbon as described in claim 1, wherein, when the crystal orientation of the Si phase in the L cross section is measured, the total orientation ratio of the <100> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction), is 20% or more and 60% or less.

4. 2. An Al bonding wire or Al bonding ribbon as described in claim 1, wherein the average ratio (e / f) of the short side length e to the long side length f of the Si phase in the L cross section is 0.20 or more and 0.70 or less.

5. The Al bonding wire or Al bonding ribbon according to claim 1, further containing one or more of Sr, Na, Fe, and P 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 Ti, Ni, Mg, and Cu 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 at least one of Ti, Ni, Mg, and Cu 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, Fe, P, Ti, Ni, Mg, and Cu 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 1, wherein the orientation ratio of the crystal orientation, the circle equivalent diameter of the Si phase, and the number thereof are values ​​measured using a SEM-EDS-EBSD device.

10. The Al bonding wire or Al bonding ribbon according to claim 4, wherein the average value of the ratio (e / f) of the short side length e to the long side length f of the Si phase 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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