Al bonding wire or al bonding ribbon

Abstract

The purpose of the present invention is to provide an Al bonding wire or an Al bonding ribbon exhibiting excellent temperature cycle reliability even in a temperature cycle test requiring a long cycle number required for a next-generation SiC power semiconductor. The Al bonding wire or the Al bonding ribbon contains 3.0-20.0 mass% of Si. When the crystal orientation of the Al phase in an L cross section (cross section in the central axis direction including the central axis) of the Al bonding wire or the Al bonding ribbon is measured, the orientation ratio of the 110 crystal orientation in which the angle difference is 15° or less with respect to the vertical direction (ND direction) of the central axis is 10-40%, and the orientation ratio of the 100 crystal orientation in which the angle difference is 15° or less with respect to the direction parallel to the central axis (RD direction) is 15-50%.

Description

Al bonding wire or Al bonding ribbon

[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.

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

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

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

[0005] Next-generation power semiconductor devices are required to operate stably for longer periods of time than general-purpose power semiconductor devices. Power semiconductor devices operate by repeatedly turning current on and off. When current is supplied to a Si semiconductor chip through an Al bonding wire or Al bonding ribbon, the temperature of the first junction rises. On the other hand, when the current supply is stopped, the temperature of the first junction drops. Thus, the first junction repeatedly rises and falls in temperature during power semiconductor operation. This repeatedly applies thermal stress to the first junction due to the difference in thermal expansion between the Al bonding wire or Al bonding ribbon and the semiconductor chip. When using a connecting material made solely of high-purity Al, the Al bonding wire or Al bonding ribbon breaks due to thermal stress in a relatively short period of time, making it difficult to meet the performance requirements of 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, an Al bonding wire that focuses on improving mechanical strength has been proposed. As a method for improving the mechanical properties of the Al bonding wire, a method of adding a specific element to Al has been proposed.

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

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

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

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

[0011] As described above, next-generation power semiconductor devices are required to withstand longer periods of use than general-purpose power semiconductor devices. During operation of a power semiconductor device, the temperature of the first bonded portion repeatedly rises and falls. As a result, because the Al bonding wire or Al bonding ribbon has a larger linear 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 ultimately leads 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 life (temperature cycle reliability) of the first bonded portion as it rises and falls in temperature. The Al bonding wire or Al bonding ribbon used in next-generation power semiconductors is required to exhibit excellent temperature cycle reliability in a temperature cycle test.

[0012] 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 more stringent temperature cycle testing than currently available. For example, while the temperature cycle test for Si semiconductors is limited to approximately 1,000 cycles, it is required to extend this to approximately 2,000 cycles for SiC semiconductors. Furthermore, while the upper temperature limit for Si semiconductors is approximately 150°C, which is a strict condition, for SiC semiconductors, excellent temperature cycle reliability is required under even more severe conditions, such as above 175°C. The inventors have discovered that even Al bonding wires or Al bonding ribbons that exhibit excellent temperature cycle reliability after approximately 1,000 cycles may experience a problem of deterioration in the strength of the Al bonding wire or Al bonding ribbon joint when subjected to a temperature cycle test for SiC semiconductors of 2,000 cycles. This may result in poor temperature cycle reliability. This is thought to be because the shape, location, and extension behavior of cracks occurring at the bonded portion 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 1000 to 2000, the proportion of cracks occurring inside the Al bonding wire or Al bonding ribbon increases rapidly, which is thought to be a factor in accelerating the deterioration of reliability.

[0013] 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 temperature cycle reliability even in temperature cycle tests with a long number of cycles, which is required for next-generation SiC power semiconductors.

[0014] As a result of intensive research into the above-mentioned problems, the inventors have discovered that the above-mentioned problems can be solved by an Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, and when the crystal orientation of the Al phase in the L-section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction), is 10% or more and 40% or less, and the orientation ratio of the <100> crystal orientation, which has an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction), is 15% or more and 50% or less.Based on this knowledge, the inventors have conducted further research and have completed the present invention.

[0015] That is, the present invention includes the following: <1> An Al bonding wire or Al bonding ribbon containing 3.0 mass% or more and 20.0 mass% or less of Si, wherein, when the crystal orientation of the Al phase in an L-section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction), is 10% or more and 40% or less, and the orientation ratio of the <100> crystal orientation, which has an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction), is 15% or more and 50% or less. <2> An Al bonding wire or Al bonding ribbon according to <1>, wherein the average diameter of the Al phase in the L-section is 5.0 μm or more and 40.0 μm or less. <3> The Al bonding wire or Al bonding ribbon according to <1> or <2>, wherein the average diameter of the Si phase in the L cross section is 0.8 μm or more and 4.0 μm or less. <4> The Al bonding wire or Al bonding ribbon according to any one of <1> to <3>, further containing one or more of Sr, Na, Ni, and B in a total amount of 10 mass ppm to 800 mass ppm. <5> The Al bonding wire or Al bonding ribbon according to any one of <1> to <4>, further containing one or more of Mn, Ti, Fe, Cu, and Mg in a total amount of 100 mass ppm to 2000 mass ppm. <6> The Al bonding wire or Al bonding ribbon according to any one of <1> to <5>, wherein the total concentration of elements other than Al, Si, Sr, Na, Ni, B, Mn, Ti, Fe, Cu, and Mg in the Al bonding wire or Al bonding ribbon is 0.5 mass% or less. <7> The Al bonding wire or Al bonding ribbon according to any one of <1> to <6>, wherein the orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device. <8> The Al bonding wire or Al bonding ribbon according to any one of <2> to <7>, wherein the average diameter is a value measured using a SEM-EDS-EBSD device. <9> The Al bonding wire or Al bonding ribbon according to any one of <1> to <8>, which is for use in a semiconductor device.<10> A semiconductor device including the Al bonding wire or Al bonding ribbon according to any one of <1> to <9>.

[0016] According to the present invention, it is possible to provide an Al bonding wire or Al bonding ribbon that exhibits excellent temperature cycle reliability even in temperature cycle tests with a long number of cycles, which is required for next-generation SiC power semiconductors, and a semiconductor device obtained using the Al bonding wire or Al bonding ribbon.

[0017] Fig. 1 is a schematic diagram for explaining the measurement target surface (inspection surface), RD direction, and ND direction when measuring the crystal orientation of the Al phase, the average diameter of the Al phase, and the average diameter of the Si phase for an Al bonding wire. The measurement target surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding wire. Fig. 2 is a schematic diagram for explaining the measurement target surface (inspection surface), RD direction, and ND direction when measuring the crystal orientation of the Al phase, the average diameter of the Al phase, and the average diameter of the Si phase for an Al bonding ribbon. The measurement target surface is a cross section (L cross section) in the central axis direction including the central axis of the Al bonding ribbon. Fig. 3 is a schematic diagram for explaining a hollow defect in the 1st bonded portion for an Al bonding wire.

[0018] 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.

[0019] [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, characterized in that, when the crystal orientation of the Al phase in an L-section (a cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <110> crystal orientation having an angular difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction, Normal Direction) (hereinafter also referred to as the "orientation ratio of the <110> crystal orientation of the Al phase in the ND direction") is 10% or more and 40% or less, and the orientation ratio of the <100> crystal orientation having an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction, Rolling Direction) (hereinafter also referred to as the "orientation ratio of the <100> crystal orientation of the Al phase in the RD direction") is 15% or more and 50% or less.

[0020] As mentioned above, when a connecting material made only of high-purity Al is used in a temperature cycle test, cracks propagate relatively quickly within the connecting material, resulting in a decrease in temperature cycle reliability. It has been confirmed that Al alloys with high concentrations of Si can reduce the thermal expansion of the connecting material and improve temperature cycle reliability. However, even when using Al alloys with high concentrations of Si, the bonding strength may decrease if the number of cycles in the temperature cycle test increases significantly. Therefore, further improvement in temperature cycle reliability is required to meet the temperature cycle reliability required for next-generation power semiconductor devices, such as SiC, which have high heat resistance.

[0021] The inventors have clarified that the form and causes of defects at wire or ribbon joints change as the number of cycles in a temperature cycle test increases. Although this varies depending on the detailed conditions of the temperature history, cracks predominantly propagate within the wire or ribbon up to about 1,000 temperature cycles. However, after 1,500 cycles, cracks propagate in two locations, within the wire or ribbon and within the electrode, which reduces temperature cycle reliability. When the number of temperature cycles reaches 2,000 cycles, it is insufficient to simply reduce cracks in one location; therefore, it is effective to simultaneously suppress cracks within the Al bonding wire or Al bonding ribbon and within the electrode.

[0022] As a result of intensive research to solve the above problems, the inventors have discovered that by simultaneously adjusting the orientation ratio of the <110> crystal orientation of the Al phase in the direction perpendicular to the central axis (ND direction) of the L-section and the orientation ratio of the <100> crystal orientation of the Al phase in the direction parallel to the central axis (RD direction) of the L-section of an Al bonding wire or Al bonding ribbon containing 3.0 mass% to 20.0 mass% Si, it is possible to improve the temperature cycle reliability even in temperature cycle tests with a fairly long number of temperature cycles, thereby contributing to a longer life of the Al bonding wire or Al bonding ribbon. In other words, by mutually controlling the crystal orientations of the different Al phases with respect to the structure in different directions of the Al bonding wire or Al bonding ribbon, it is possible to improve the temperature cycle reliability even in severe temperature cycle tests.

[0023] 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-solved in Al, and a Si phase formed by crystallization or precipitation of Si. Here, the Al phase may contain other additive elements in addition to Si as a solid solution. The Si phase is a general term for Si crystallized particles and Si precipitates. Si crystallized particles are formed from the melt during solidification and are coarse, measuring approximately 1 to 25 μm in size, while Si precipitates are formed from the solid state and are small, measuring approximately 0.1 to several μm in size.

[0024] 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.

[0025] In the present invention, the "ND direction" refers to a direction that satisfies both "a direction perpendicular to the central axis" and "a direction 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 central axis direction including the central axis) is taken, but 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 the present invention. In the case of ribbon, the "ND direction" is uniquely determined by the definition of "a direction 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, in order to emphasize ease of cross-section polishing and EBSD analysis, the "cross section perpendicular to the width W direction" is defined as the L cross section (Figure 2).

[0026] 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 FIG. 1. FIG. 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 a width W and a thickness T, the central axis refers to the axis passing through the center of the width W and the center of the thickness T, and the L cross section refers to a cross section in the central axis direction including the central axis and perpendicular to the width W direction (FIG. 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 FIG. 2. Here, when processing the cross section 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 to be a cross section including the central axis.

[0027] The reason why the Al bonding wire or Al bonding ribbon of the present invention can provide excellent temperature cycle reliability even in a temperature cycle test with a long number of cycles is presumed to be as follows.

[0028] 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 Al bonding ribbon and the semiconductor chip, and is therefore thought to be able to reduce the thermal stress that occurs. It is also thought that the particulate Si phase can suppress the growth of cracks that occur at the bonding interface into the Al bonding wire or Al bonding ribbon material.

[0029] Up to about 1000 cycles of temperature cycle testing, it is effective to utilize the effect of the Si phase in lowering the linear expansion coefficient and adjust the crystal orientation of the Al bonding wire or Al bonding ribbon to enhance this effect. On the other hand, when the number of temperature cycles increases beyond 1500 cycles, the recovery and recrystallization of the Al phase progresses in both the Al bonding wire or Al bonding ribbon itself and the electrode to which it is joined, changing the effect of thermal strain on cracks. Therefore, it is thought that in joints that can withstand 2000 cycles, the appropriate conditions for the crystal orientation of the Al phase that affect cracks inside the Al bonding wire or Al bonding ribbon and cracks inside the electrode change.

[0030] Although the present invention is characterized by the mutual correlation between the ND and RD crystal orientations, which enhances their effects, we will explain these actions separately. When the <110> crystal orientation of the ND Al phase is in the range of 10% to 40%, it enhances the role of suppressing the propagation and branching and expansion of cracks inside the wire or ribbon. Furthermore, when the orientation ratio of the <100> crystal orientation of the RD Al phase is in the range of 15% to 50%, it is possible to mitigate the increase in stress inside the Al bonding wire or Al bonding ribbon during temperature cycle tests, and it is thought to have the effect of suppressing the propagation of cracks inside the electrode.

[0031] In other words, by combining the effect of reducing cracks in the wire interior by controlling the <110> crystal orientation of the Al phase in the ND direction and the effect of reducing crack growth primarily within the electrode by controlling the <100> crystal orientation of the Al phase in the RD direction, it is possible to extend the time until joint failure occurs, even in a rigorous temperature cycle test with 2,000 cycles. This can be explained by the vector direction of thermal strain. The effect of the <110> crystal orientation of the Al phase in the ND direction reduces the component of force in the radial direction (toward the center) from the joint interface, while the effect of the <100> crystal orientation of the Al phase in the RD direction acts on the component of force in the longitudinal direction of the wire. While controlling the <110> crystal orientation of the Al phase in the ND direction alone can suppress the propagation of cracks within the electrode, and controlling the <100> crystal orientation of the Al phase in the RD direction alone can suppress cracks within the wire or ribbon, simultaneously controlling these two crystal orientations can enhance the synergistic effect.

[0032] As described above, it is presumed that the Al bonding wire or Al bonding ribbon of the present invention can provide excellent temperature cycle reliability as described above as a result of appropriately controlling factors that contribute to improving temperature cycle reliability in a fairly long temperature cycle test of approximately 2000 cycles.

[0033] -Si Concentration- A Si concentration in the range of 3.0% by mass or more and 20.0% by mass or less helps reduce thermal distortion at the bonded portion and improve temperature cycle reliability. Specifically, a Si concentration of 3.0% by mass or more can significantly improve temperature cycle reliability. Furthermore, with advances and optimization of the equipment and conditions used in the manufacture and bonding of wires, etc., higher upper limits for the Si concentration have become permissible while suppressing defects such as wire breakage during processing, deterioration of surface properties, reduction in initial bond strength due to hardening, and damage to semiconductor chips. However, a Si concentration of 20.0% by mass or less effectively suppresses these defects and achieves the desired temperature cycle reliability. From the viewpoint of obtaining good temperature cycle reliability, the Si concentration in the Al bonding wire or Al bonding ribbon of the present invention is 3.0 mass% or more, preferably 3.5 mass% or more, more preferably 4.0 mass% or more, and even more preferably 4.2 mass% or more, 4.4 mass% or more, 4.5 mass% or more, 4.6 mass% or more, 4.8 mass% or more, or 5.0 mass% or more. In addition, from the viewpoint of achieving the desired temperature cycle reliability while effectively suppressing defects such as a decrease in initial bond 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.

[0034] 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.

[0035] -Crystal orientation of the Al phase in the L cross section- From the viewpoint of obtaining excellent temperature cycle reliability even in a temperature cycle test with a long number of cycles, when the crystal orientation of the Al phase in the L cross section 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, preferably 20% or more, more preferably 22% or more, 24% or more, 26% or more, or 28% or more, even more preferably 30% or more, and even more preferably 35% or more. From the viewpoint of obtaining excellent temperature cycle reliability even in a temperature cycle test with a long number of cycles, the upper limit of the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is 50% or less, preferably 48% or less or 45% or less, more preferably 42% or less, and even more preferably 40% or less.

[0036] From the viewpoint of obtaining excellent temperature cycle reliability even in a temperature cycle test with a long number of cycles, when the crystal orientation of the Al phase in the L cross section of the Al bonding wire or Al bonding ribbon is measured, the orientation ratio of the <110> crystal orientation, which has an angle difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction), is 10% or more, preferably 15% or more, more preferably 18% or more, and even more preferably 20% or more. From the viewpoint of obtaining excellent temperature cycle reliability even in a temperature cycle test with a long number of cycles, the upper limit of the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction is 40% or less, preferably 38% or less or 36% or less, more preferably 34% or less or 32% or less, and even more preferably 30% or less.

[0037] Here, by setting the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction to 15% or more, the length of cracks inside the electrode rapidly decreases during a temperature cycle test with a long cycle count. Furthermore, by setting the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction to 50% or less, a very good metal bond with the electrode can be obtained during bonding. Due to the influence of these two factors, when the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is set to 15% or more and 50% or less, the decrease in bond strength after 2000 cycles in a temperature cycle test is significantly suppressed.

[0038] On the other hand, by setting the orientation ratio of the <110> crystal orientation of the ND-oriented Al phase to 10% or more, the effect of suppressing crack propagation inside the wire during a temperature cycle test with a long cycle number is significantly improved. Furthermore, by setting the orientation ratio of the <110> crystal orientation of the ND-oriented Al phase to 40% or less, the variation in the deformation shape of the wire or ribbon can be significantly suppressed, resulting in stable ultrasonic bonding. As a result, when the orientation ratio of the <110> crystal orientation of the ND-oriented Al phase is set to 10% or more and 40% or less, the decrease in bond strength after 2000 cycles in a temperature cycle test is significantly suppressed.

[0039] The orientation ratio of the crystal orientation of the Al phase in the L cross section of an Al bonding wire or Al bonding ribbon can be measured using an SEM-EDS-EBSD device. Specifically, a method can be used in which information on the Al concentration and Si concentration obtained by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) is combined with information on the crystal orientation obtained by electron backscatter diffraction (EBSD). More specifically, in a measurement area in which the L cross section of the Al bonding wire or Al bonding ribbon is used as the inspection surface, Al and Si concentration measurement using EDS and crystal orientation analysis using EBSD are simultaneously performed. Next, the Al phase and Si phase are separated and extracted from the EDS measurement results using the analysis software provided with the device. Specifically, it is preferable to use the Chi Scan function, which is a function of the analysis software OIM Data Collection or OIM Analysis (both manufactured by TSL Solutions) provided with the FE-SEM (Field Emission-Scanning Electron Microscope) device. Then, for the region identified as Al phase, the orientation ratios of the <100> crystal orientation of the Al phase in the RD direction and the <110> crystal orientation of the Al phase in the ND direction can be calculated using the analysis software provided with the device. To calculate the orientation ratios, a partial ratio is used, calculated as a population of the area of ​​only the crystal orientations that could be identified based on a certain reliability within the measurement area. Regarding the crystal orientation of the Al phase, the area ratios of the <100> crystal orientation in the RD direction and the <110> crystal orientation in the ND direction were defined as the orientation ratio of the <100> crystal orientation in the RD direction and the orientation ratio of the <110> crystal orientation in the ND direction, respectively. 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 procedures (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) The Chi Scan function is used 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 area identified as Al phase, the crystal orientation is analyzed and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction and the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction are calculated.

[0040] In the above procedure (2), the Tolerance (%) setting can be selected in the range of 20 to 40%, and in a standard analysis of the L cross section of an Al bonding wire or Al bonding ribbon, it is preferable to compare it at about 30%. The procedure for adjusting this Tolerance is explained below. It is preferable to select or confirm the Tolerance value so that the shape and size of the Si phase extracted and identified by the Chi Scan function are equivalent to those identified from the EDS map, which displays the Si element concentration in EDS analysis in two dimensions.

[0041] In the present invention, the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L cross section and the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction are the average (arithmetic mean) of the orientation ratios obtained by measuring 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. Furthermore, in the present invention, the measurement area for the crystal orientation in the L cross section using the EBSD method has a length in the central axis direction of the Al bonding wire or Al bonding ribbon of 300 μm or more and less than 800 μm. It is desirable that the entire Al bonding wire or Al bonding ribbon is included in the direction perpendicular to the central axis of the Al bonding wire or Al bonding ribbon. However, if the size is large and it is difficult to measure the entire area, it can be adjusted to a range of less than 600 μm.

[0042] - Average Diameter of Al Phase in L Cross Section - The Al bonding wire or Al bonding ribbon of the present invention preferably has an average diameter of the Al phase in its L cross section of 5.0 μm or more and 40.0 μm or less.

[0043] The inventors have found that having an average diameter of the Al phase in the L cross section in the range of 5.0 μm to 40.0 μm has the effect of maintaining a stable high shear strength of the joint after 2000 cycles in a temperature cycle test. This is thought to be due to the synergistic effects of the thermal distortion reduction effect of containing a predetermined concentration of Si and controlling the orientation ratio of the crystal orientation of the Al phase within a predetermined range, and the structure in which the average diameter of the Al phase is adjusted to 5.0 μm to 40.0 μm. To illustrate this effect, the shear strength of the joint after 2000 cycles can be increased by 10% or more. Regarding the specific effects of the average diameter of the Al phase, in ultrasonic bonding (wedge bonding) of an Al bonding wire or Al bonding ribbon containing a large amount of Si phase, it is believed that the Al bonding wire or Al bonding ribbon and the electrode can easily deform relative to each other to obtain a good metal bond, and that the growth of recrystallized grains during the temperature cycle test can be stabilized to alleviate thermal stress at the bonding interface, thereby efficiently improving temperature cycle reliability.

[0044] From the viewpoint of suppressing the variation in bonding strength in a temperature cycle test with a long number of cycles, the average diameter of the Al phase in the L cross section is preferably 5.0 μm or more, more preferably 8.0 μm or more, even more preferably 10.0 μm or more, particularly preferably 12.0 μm or more or 15.0 μm or more. From the viewpoint of suppressing the variation in bonding strength in a temperature cycle test with a long number of cycles, the upper limit of the average diameter of the Al phase in the L cross section is preferably 40.0 μm or less, more preferably 38.0 μm or less or 35.0 μm or less, even more preferably 32.0 μm or less or 30.0 μm or less, particularly preferably 28.0 μm or less or 25.0 μm or less.

[0045] By setting the average diameter of the Al phase in the L cross section to 5.0 μm or more, it is possible to significantly suppress deformation of the electrode during ultrasonic bonding. Furthermore, by setting the average diameter of the Al phase to 40.0 μm or less, it is possible to significantly stabilize the bonded shape of the wire or ribbon. Due to these factors, it is believed that by setting the average diameter of the Al phase in the L cross section to 5.0 μm or more and 40.0 μm or less, it is possible to significantly reduce the variation in the shear strength of the bonded portion after a temperature cycle test with a long number of cycles.

[0046] This section describes a method for measuring the average diameter of the Al phase in the L-section of an Al bonding wire or Al bonding ribbon. The average diameter of the Al phase in the L-section can be measured using a SEM-EDS-EBSD instrument, similar to the measurement of the orientation ratio of the crystal orientation described above. Specifically, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. More detailed procedures can be similar to those described above in relation to the measurement of the orientation ratio of the crystal orientation. That is, the crystal orientation of the region identified as Al phase can be analyzed using the analysis software provided with the instrument. If the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the circle-equivalent diameter is calculated. The average circle-equivalent diameter of each Al phase is defined as the average diameter of the Al phase. In the process of determining the average diameter of the Al phase, areas where the crystal orientation cannot be measured or where the reliability of the orientation analysis is low are excluded from the calculation. Therefore, in one embodiment, the average diameter of the Al phase in the L-section of the Al bonding wire or Al bonding ribbon of the present invention is calculated by the following steps (1) to (3). (1) Using the L-section of the Al bonding wire or Al bonding ribbon as the inspection surface, Al and Si concentrations are measured using EDS and crystal orientation is measured using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are separated and extracted. Specifically, by setting a tolerance equivalent to the Si threshold 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 Al phase, the crystal orientation is analyzed, and if the orientation difference between the measurement points is 15° or more, it is determined to be a grain boundary and the circle-equivalent diameter of each crystal grain is calculated. The circle-equivalent diameters of each crystal grain are then averaged to calculate the average diameter of the Al phase. Here, for the average calculation, the average value obtained by area averaging (area weighted average), which can be selected in the software provided with the device, is used. By using the average value obtained by area averaging, it is possible to accurately measure and judge whether or not the conditions related to the average diameter of the Al phase are met, which is suitable for suppressing variations in bonding strength in a temperature cycle test with a long number of cycles.The average area is calculated by averaging the values ​​obtained by multiplying the ratio of each particle area to the total particle area, and is calculated automatically by the software.

[0047] In the present invention, when calculating the average diameter of the Al phases in the L cross section, only Al phases having a diameter (equivalent circle diameter) of 0.5 μm or more are considered, which makes it possible to accurately determine whether the requirement for the average diameter of the Al phases in the L cross section, which is suitable for stably maintaining a high shear strength of the joint after 2000 cycles in a temperature cycle test, is met.

[0048] When measuring the average diameter of the Al phase in the L cross section, the setting range of the tolerance in the procedure (2) above, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by the EBSD method are as described above in relation to the measurement of the orientation ratio of the crystal orientation of the Al phase.

[0049] - Average Diameter of Si Phase in L Cross Section - In the Al bonding wire or Al bonding ribbon of the present invention, the average diameter of the Si phase in the L cross section is preferably 0.8 μm or more and 4.0 μm or less.

[0050] With regard to Al bonding wires or Al bonding ribbons that have been strengthened by adding Si or the like, they are prone to damaging semiconductor chips during the first bonding stage, and adjusting the ultrasonic vibration or load to reduce such damage can result in a phenomenon in which a spot with insufficient metal bonding is formed near the center of the bonding area between the Al bonding wire or Al bonding ribbon and the electrode (hereinafter also referred to as "hollow hole"). Hollow holes cause a decrease in bonding strength due to insufficient metal bonding, and can be the starting point for defects in temperature cycle tests.

[0051] When the average diameter of the Si phase in the L cross section is in the range of 0.8 μm to 4.0 μm, it is possible to suppress hollowing at the first bonded portion. It is believed that controlling the average diameter of the Si phase can provide effects such as promoting deformation of the Al phase that contributes to bonding and increasing the transmission efficiency of ultrasonic vibration to the center of the bonded region, thereby suppressing hollowing.

[0052] From the viewpoint of further suppressing hollowing out of the first joint, the average diameter of the Si phase in the L cross section of the Al bonding wire or Al bonding ribbon of the present invention is more preferably 3.8 μm or less or 3.5 μm or less, even more preferably 3.4 μm or less, 3.2 μm or less, or 3.0 μm or less, and the lower limit is 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.

[0053] This section describes a method for measuring the average diameter of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon. The average diameter of the Si phase in the L-section can be measured using a SEM-EDS-EBSD instrument, similar to the measurement of the orientation ratio of the Al phase crystal orientation described above. Specifically, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. More detailed procedures can be similar to those described above in relation to the measurement of the orientation ratio of the Al phase crystal orientation. 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 orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the circle-equivalent diameter is calculated. The average circle-equivalent diameter of each Si phase is defined as the average diameter of the Si phase. In the process of determining the average diameter of the Si phase, areas where the crystal orientation cannot be measured or where the orientation analysis reliability is low are excluded from the calculation. Therefore, in one embodiment, the average diameter of the Si phase in the L-section of the Al bonding wire or Al bonding ribbon of the present invention is calculated by the following steps (1) to (3). (1) Using the L-section of the Al bonding wire or Al bonding ribbon as the inspection surface, Al and Si concentrations are measured using EDS and crystal orientation is measured using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are separated and extracted. Specifically, by setting a tolerance equivalent to the Si threshold 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, and if the orientation difference between the measurement points is 15° or more, it is determined to be a grain boundary and the circle-equivalent diameter of each crystal grain is calculated. The circle-equivalent diameters of each crystal grain are then averaged to calculate the average diameter of the Si phase. Here, for the average calculation, an average value obtained by area averaging (area weighted averaging), which can be selected in the software attached to the device, is used. By using the average value obtained by area averaging, it is possible to accurately measure and determine whether or not the conditions related to the average diameter of the Si phase, which are suitable for suppressing hollowing of the first weld, are met.The average area is calculated by averaging the values ​​obtained by multiplying the ratio of each particle area to the total particle area, and is calculated automatically by the software.

[0054] In the present invention, when calculating the average diameter of the Si phase in the L cross section, only Si phases having a diameter (equivalent circle diameter) of 0.5 μm or more are considered, which makes it possible to accurately determine whether the requirement for the average diameter of the Si phase in the L cross section, which is suitable for suppressing hollowing of the first welded portion, is met.

[0055] When measuring the average diameter of the Si phase in the L cross section, the setting range of the tolerance in the procedure (2) above, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by the EBSD method are the same as those described above for the measurement of the orientation ratio of the crystal orientation of the Al phase.

[0056] In addition to the above, there are several other methods for measuring the average diameter of the Si phase, including binarization processing from an observed image of the L cross section. However, in the present invention, it is preferable to use the method of combining the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD, as described above, for reasons such as the fact that a number of measurement functions are provided and a plurality of properties such as the orientation ratio of the crystal orientation of the Al phase, the average diameter of the Al phase, and the average diameter of the Si phase can be obtained in a single measurement, automatic analysis is possible, and measurement is easy using widely used equipment and analysis techniques.

[0057] -Addition of Sr, Na, Ni, and B- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Sr, Na, Ni, and B (hereinafter also referred to as the "first element group"). The total concentration of the first element group may be 0 ppm by mass, preferably 1 ppm by mass or more, more preferably 3 ppm by mass or more, even more preferably 5 ppm by mass or more, and particularly preferably 8 ppm by mass or more or 10 ppm by mass or more. The upper limit of the total concentration of the first element group is preferably 10,000 ppm by mass or less or 8,000 ppm by mass or less, more preferably 5,000 ppm by mass or less or 3,000 ppm by mass or less, even more preferably 2,000 ppm by mass or less or 1,000 ppm by mass or less, and particularly preferably 900 ppm by mass or less or 800 ppm by mass or less. In one embodiment, the total concentration of the first element group is preferably 10 ppm by mass or more and 800 ppm by mass or less.

[0058] By further containing at least one of Sr, Na, Ni, and B in a total amount of 10 mass ppm to 800 mass ppm, the frequency of wire breakage during wiredrawing of the Al bonding wire or Al bonding ribbon can be reduced. Al alloys containing a high concentration of Si of 3.0 mass% to 20.0 mass% tend to have a higher frequency of wire breakage during the wiredrawing process. This is thought to be due in part to the fact that particles of the Si phase crystallized during solidification cause stress concentration during wiredrawing, inducing wire breakage. It is believed that the addition of the first element group can uniformly distribute the particulate Si phase and inhibit the growth and coarsening of the Si phase, thereby alleviating stress concentration during wiredrawing and reducing wire breakage. It is believed that by controlling the orientation ratio of the crystal orientation of the Al phase in the ND direction in the L cross section and the orientation ratio of the crystal orientation of the Al phase in the RD direction, and by adding the first element group, the effect of alleviating stress concentration during wiredrawing can be enhanced.

[0059] From the viewpoint of reducing the frequency of wire breakage during wire drawing, the total concentration of the first element group in the Al bonding wire or Al bonding ribbon of the present invention is more preferably 20 ppm by mass or more, even more preferably 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more, and the upper limit is preferably 750 ppm by mass or less, more preferably 740 ppm by mass or less, 720 ppm by mass or less, or 700 ppm by mass or less, even more preferably 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, or 600 ppm by mass or less, particularly preferably 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0060] 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, Ni, or B.

[0061] When the Al bonding wire or Al bonding ribbon of the present invention contains Sr from the first element group, the Sr concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. In addition, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the Sr concentration is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the Sr concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the Sr concentration is more preferably 800 ppm by mass or less, even more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0062] 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.

[0063] When the Al bonding wire or Al bonding ribbon of the present invention contains Ni from the first 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, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the Ni 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 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, 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 Ni 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.

[0064] When the Al bonding wire or Al bonding ribbon of the present invention contains B from the first element group, the concentration of B may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, or 8 ppm by mass or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of B is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. The upper limit of the B concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, 3,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 900 ppm by mass or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wiredrawing, the concentration of B is more preferably 800 ppm by mass or less, still more preferably 750 ppm by mass or less, 740 ppm by mass or less, 720 ppm by mass or less, 700 ppm by mass or less, 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, 600 ppm by mass or less, 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0065] -Addition of Mn, Ti, Fe, Cu, Mg- The Al bonding wire or Al bonding ribbon of the present invention may further contain one or more of Mn, Ti, Fe, Cu, and Mg (hereinafter also referred to as the "second element group"). The total concentration of the second element group may be 0 mass ppm, preferably 1 mass ppm or more or 3 mass ppm or more, more preferably 5 mass ppm or more or 8 mass ppm or more, even more preferably 10 mass ppm or more or 30 mass ppm or more, particularly preferably 50 mass ppm or more, 80 mass ppm or more, or 100 mass ppm or more. The upper limit of the total concentration of the second element group is preferably 10,000 mass ppm or less, more preferably 8,000 mass ppm or less, even more preferably 5,000 mass ppm or less, particularly preferably 3,000 mass ppm or less or 2,000 mass ppm or less. In one embodiment, the total concentration of the second element group is preferably 100 ppm by mass or more and 2000 ppm by mass or less.

[0066] The Al bonding wire or Al bonding ribbon of the present invention further contains one or more of Mn, Ti, Fe, Cu, and Mg in a total amount of 100 mass ppm to 2000 mass ppm, thereby suppressing scratches and abrasion on the surface of the Al bonding wire or Al bonding ribbon and forming a smooth surface. Al alloys containing Si at a high concentration of 3.0 mass% to 20.0 mass% may harden the surface and cause Si phases and Al oxides present on the surface to fall off, resulting in scratches and abrasion on the surface during wiredrawing, resulting in an Al bonding wire or Al bonding ribbon with large surface irregularities. It is presumed that the addition of the second element group stabilizes the Al oxide on the surface of the Al bonding wire or Al bonding ribbon, refines the structure of the Al crystal grains, and hardens them, thereby reducing scratches and abrasion during wiredrawing. By controlling the orientation ratio of the crystal orientation of the Al phase in the ND direction in the L cross section and the orientation ratio of the crystal orientation of the Al phase in the RD direction, and by 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.

[0067] From the viewpoint of forming an Al bonding wire or Al bonding ribbon having a smooth surface by suppressing the occurrence of scratches and abrasions on the surface, the total concentration of the second element group in the Al bonding wire or Al bonding ribbon of the present invention is more preferably 150 mass ppm or more, even more preferably 200 mass ppm or more, 250 mass ppm or more, or 300 mass ppm or more, and the upper limit is preferably 1800 mass ppm or less, more preferably 1600 mass ppm or less, 1500 mass ppm or less, or 1200 mass ppm or less, even more preferably 1000 mass ppm or less, 900 mass ppm or less, or 800 mass ppm or less, and particularly preferably 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0068] When the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the second element group, it may contain one element from the second element group, two elements from the second element group, three elements from the second element group, four elements from the second element group, or all five elements from the second element group. Also, when the Al bonding wire or Al bonding ribbon of the present invention contains one or more elements from the second element group, it may contain Mn, Ti, Fe, Cu, or Mg.

[0069] When the Al bonding wire or Al bonding ribbon of the present invention contains Mn from the second element group, the Mn concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasion on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Mn concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Mn concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Mn 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.

[0070] When the Al bonding wire or Al bonding ribbon of the present invention contains Ti from the second element group, the Ti concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. In addition, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Ti concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Ti concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Ti concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0071] When the Al bonding wire or Al bonding ribbon of the present invention contains Fe from the second element group, the Fe concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasion on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Fe concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Fe concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Fe concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0072] 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 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. In addition, from the viewpoint of suppressing the occurrence of scratches and scraping on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Cu 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 Cu 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 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.

[0073] When the Al bonding wire or Al bonding ribbon of the present invention contains Mg from the second element group, the Mg concentration may be 0 ppm by mass, preferably 1 ppm by mass or more, 3 ppm by mass or more, 5 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 80 ppm by mass or more. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasion on the surface and forming an Al bonding wire or Al bonding ribbon having a smooth surface, the Mg concentration is more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass. The upper limit of the Mg concentration is preferably 10,000 ppm by mass or less, 8,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less. Furthermore, from the viewpoint of suppressing the occurrence of scratches and abrasions on the surface and forming an Al bonding wire or Al bonding ribbon with a smooth surface, the Mg concentration is more preferably 2000 mass ppm or less, even more preferably 1800 mass ppm or less, 1600 mass ppm or less, 1500 mass ppm or less, 1200 mass ppm or less, 1000 mass ppm or less, 900 mass ppm or less, 800 mass ppm or less, 700 mass ppm or less, 600 mass ppm or less, or 500 mass ppm or less.

[0074] As the aluminum raw material for manufacturing the Al bonding wire or Al bonding ribbon of the present invention, it is preferable to use Al with a purity of 4N (Al: 99.99% by mass or more), and it is more preferable to use Al with a lower impurity content of 5N (Al: 99.999% by mass or more). In one embodiment, Al with a purity of 3N (Al: 99.9% by mass or more) may be used.

[0075] 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, Ni, B, Mn, Ti, Fe, Cu, and Mg, and the Al bonding wire or Al bonding ribbon of the present invention may further contain elements other than Al, Si, Sr, Na, Ni, B, Mn, Ti, Fe, Cu, and Mg. The total concentration of other elements in the Al bonding wire or Al bonding ribbon is not particularly limited as long as it does not impair the effects of the present invention. The total concentration of the other elements may be, for example, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.15% by mass or less, 0.1% by mass or less, 0.08% by mass or less, 0.06% by mass or less, 0.05% by mass or less, 0.04% by mass or less, 0.03% by mass or less, 0.025% by mass or less, 0.02% by mass or less, 0.018% by mass or less, 0.016% by mass or less, 0.015% by mass or less, 0.014% by mass or less, 0.012% by mass or less, or 0.01% by mass or less. The lower limit of the total concentration of the other elements is not particularly limited, and may be 0% by mass.

[0076] 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.

[0077] In one embodiment, the remainder of the Al bonding wire or Al bonding ribbon of the present invention consists of Al and inevitable impurities. Therefore, in a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, and inevitable impurities. In another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, and inevitable impurities. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the second element group, and inevitable impurities. In yet another preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and inevitable impurities.

[0078] In a preferred embodiment, the Al bonding wire or Al bonding ribbon of the present invention does not have a coating mainly composed of a metal other than Al on the outer periphery of the Al bonding wire or Al bonding ribbon. Here, the term "coating mainly composed of a metal other than Al" refers to a coating in which the content of a metal other than Al is 50 mass % or more.

[0079] The Al bonding wire or Al bonding ribbon of the present invention may be an Al bonding wire or an Al bonding ribbon. When the present invention is an Al bonding wire, its wire diameter is not particularly limited and may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 150 μm or more, 180 μm or more, or 200 μm or more. The upper limit of the wire diameter is not particularly limited and may be, for example, 600 μm or less, 550 μm or less, 500 μm or less, 450 μm or less, or 400 μm or less. In one embodiment, the wire diameter of the Al bonding wire of the present invention may be in the range of 100 to 600 μm, and preferably 200 to 400 μm. When the present invention is an Al bonding ribbon, the dimensions of its rectangular or approximately rectangular cross section (width W x thickness T) are not particularly limited, and for example, W may be 100 to 3000 μm and T may be 50 to 600 μm.

[0080] The Al bonding wire or Al bonding ribbon of the present invention can provide excellent temperature cycle reliability even in 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.

[0081] -Method for manufacturing Al bonding wire or Al bonding ribbon- An example of a method for manufacturing an Al bonding wire or Al bonding ribbon of the present invention will be described below. Hereinafter, an example will be described in relation to the manufacture of an Al bonding wire.

[0082] The Al and alloying elements used as raw materials preferably have a high purity. Al preferably has a purity of 99.5% by mass or more, with the remainder consisting of inevitable impurities, more preferably a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and even more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Si, first element group, second element group, and other elements used as alloying elements preferably have a purity of 99.9% by mass or more, with the remainder consisting of inevitable impurities, and more preferably a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for Al bonding wire can be produced by loading the Al raw material and the alloying element raw material into a graphite or alumina crucible processed to obtain a cylindrical ingot and melting it using an electric furnace or high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm, taking into account the workability in the subsequent processing steps. The atmosphere in the furnace during melting is preferably an inert or reducing atmosphere to prevent excessive oxidation of Al, Si, the first element group, the second element group, and other elements that constitute the wire. The maximum temperature that the molten metal reaches during melting is preferably in the range of 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 that can be used during solidification include water cooling, furnace cooling, and air cooling.

[0083] The cylindrical ingot obtained by melting is subjected to a solution treatment in which it is heated at a high temperature, and then repeatedly subjected to wire drawing using a die to produce a wire of the desired wire diameter. The wire after wire drawing can be used as an Al bonding wire by performing a final heat treatment using an electric furnace.

[0084] <Control of the crystal orientation of the Al phase> In order to control the crystal orientation of the Al phase in the L cross section, it is effective to control the heat treatment conditions such as solution treatment, homogenization treatment, intermediate heat treatment, and final heat treatment, as well as the wiredrawing conditions. Specifically, the strain energy accumulated inside the Al phase during wiredrawing becomes the driving force for recrystallization in heat treatment, and effectively acts to control the crystal orientation of the Al phase and the size of the Si phase. Furthermore, during wiredrawing, it is effective to use a lubricant to ensure lubrication at the contact interface between the wire and the die.

[0085] An example of manufacturing conditions for controlling the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction in the L cross section to a range of 10% to 40% and for controlling the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction to a range of 15% to 50% is shown below.

[0086] In order to adjust the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction, it is effective to combine control of the intermediate heat treatment during wiredrawing and the final heat treatment conditions.

[0087] Adjusting the conditions of the intermediate heat treatment makes it easy to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction. Intermediate heat treatment is a heat treatment performed during the process of processing from an ingot to the final wire diameter. It is effective to set the temperature range of the intermediate heat treatment to 200°C or higher and lower than 400°C, and the time period to 1 hour or higher and lower than 48 hours. The number of intermediate heat treatments is preferably between three and four. For example, when performing three intermediate heat treatments, the wire diameter after the first intermediate heat treatment is preferably 6.5 to 8.0 times the final wire diameter, the wire diameter after the second intermediate heat treatment is preferably 4.0 to 5.5 times the final wire diameter, and the wire diameter after the third intermediate heat treatment is preferably 2.0 to 3.5 times the final wire diameter. By performing intermediate heat treatment, processing strain in the Al phase is reduced and slight recrystallization occurs, thereby reducing the processed structure of the Al phase at the final wire diameter, and subsequent heat treatment increases the progress of recrystallization of the Al phase and promotes 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. On the other hand, if the intermediate heat treatment temperature is 400°C or higher, there is a concern that the orientation ratio of the <100> crystal orientation of the Al phase in the RD will become unstable.

[0088] Optimizing the combination of temperature conditions for these multiple intermediate heat treatments is effective in adjusting the orientation ratio of the <100> crystal orientation of the Al phase in the RD. For example, when performing intermediate heat treatment twice, if the temperatures for the large-diameter and small-diameter intermediate heat treatments are Tm1 (°C) and Tm2 (°C), respectively, setting the temperature Tm1 for the large-diameter wire higher than the temperature Tm2 for the small-diameter wire (Tm1 > Tm2) allows recrystallization to proceed uniformly throughout the wire, making it easy to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD.

[0089] Furthermore, as a process prior to intermediate heat treatment, holding the wire at room temperature for two or more days after wire drawing and then performing intermediate heat treatment is effective in adjusting the orientation ratio of the <110> crystal orientation of the ND Al phase. The working strain introduced into the Al phase during the wire drawing process is used as the driving force to promote the rise and annihilation of dislocations, mainly in the ND direction, during holding at room temperature, thereby promoting recovery, making it easier to adjust the final orientation ratio of the <110> crystal orientation of the ND Al phase. Holding at room temperature is preferably within the range of two to 20 days, and holding in a thermostatic bath at 20 to 50°C can also be used as an alternative.

[0090] Regarding the final heat treatment conditions, it is effective to adjust the temperature range to 200°C or higher and lower than 360°C, and the time range to 2 hours or higher and lower than 20 hours. The final heat treatment promotes recovery and recrystallization of the Al phase, and at the same time, the amount of Si dissolved in the Al phase changes depending on the heat treatment temperature, thereby changing the recrystallization temperature. By adjusting the progress of recrystallization by the final heat treatment, it becomes easy to control the orientation of the crystal orientation. For example, by adjusting the final heat treatment to a low temperature or for a short time, the orientation ratio of the <110> crystal orientation of the dense ND-direction Al phase tends to increase.

[0091] <Control of the Average Diameter of the Al Phase> In order to control the average diameter of the Al phase in the L cross section to a range of 5.0 μm to 40.0 μm, it is effective to control the growth of crystal grains due to recrystallization of the Al phase by adjusting the temperature and time of the heat treatment at the final wire diameter. Specifically, the temperature of the final heat treatment is controlled to a range of 200° C. to less than 300° C., and the time of the final heat treatment is controlled to a range of 2 hours to less than 72 hours. By performing heat treatment at a relatively low temperature for a long period of time, the amount of solid solution Si contained in the Al phase is adjusted, thereby controlling the progress of recrystallization of the Al phase and making it easy to control the average diameter of the Al phase to a desired range.

[0092] <Control of the average diameter of the Si phase> To adjust the average diameter of the Si phase in the L cross section to a range of 0.8 μm or more and 4.0 μm or less, it is effective to adjust the melting temperature in ingot production to a range of 800°C or more and less than 1050°C, and to control the solution treatment temperature to a range of 450°C or more and less than 550°C, and the solution treatment time to a range of 1 hour or more and less than 6 hours. If the solution treatment temperature is high, the columnar Si phase tends to be broken down and granulated, thereby reducing the average diameter of the Si phase. To further reduce the average diameter of the Si phase, it is effective to increase the cooling rate during solidification, and for example, water cooling is also effective.

[0093] As mentioned above, the above is a typical example of the manufacturing of Al bonding wire, which is a wire material. The same procedure can also be used to manufacture Al bonding ribbon, which is a strip material. The temperature and time of the heat treatment can be approximately the same as those described above. Furthermore, when manufacturing Al bonding ribbon by rolling, the die area reduction rate can be adjusted by replacing it with the rolling reduction rate.

[0094] [Semiconductor Device] A semiconductor device can be manufactured by connecting electrodes on a semiconductor chip to external electrodes on a lead frame or substrate using the Al bonding wire or Al bonding ribbon of the present invention. That is, the semiconductor device of the present invention includes the Al bonding wire or Al bonding ribbon of the present invention. As mentioned above, wedge bonding is used for both the first bonding with the electrode on the semiconductor chip and the second bonding with the electrode on the lead frame or substrate.

[0095] 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.

[0096] In the semiconductor device of the present invention, the circuit board and semiconductor chip are not particularly limited, and known circuit boards and semiconductor chips that can be used to configure a semiconductor device may be used. Alternatively, a lead frame may be used instead of the circuit board. For example, a semiconductor device may be configured including a lead frame and a semiconductor chip mounted on the lead frame, as in the semiconductor device described in JP 2020-150116 A.

[0097] Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, air conditioners, solar power generation systems, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.), and among these, power semiconductor devices are preferred.

[0098] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the examples shown below.

[0099] (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, Ni, B), the second element group (Mn, Ti, Fe, Cu, Mg), and other elements (Zn, Sn) had a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for the Al bonding wire or Al bonding ribbon was produced by loading the Al raw material and the alloying element raw materials into an alumina crucible and melting them using a high-frequency heating furnace. The atmosphere in the furnace during melting was an Ar atmosphere, and the maximum temperature of the molten metal during melting was 800°C or higher but lower than 1050°C. The cooling method during solidification was air cooling in the air or water cooling in water.

[0100] A cylindrical ingot with a diameter of 6 mm was obtained by melting, and the ingot was subjected to solution treatment and homogenization treatment. After that, a wire drawing process using a die and intermediate heat treatment were performed to produce an Al bonding wire with a diameter of 300 μm. Furthermore, using the Al bonding wire with a diameter of 300 μm as 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 and lower than 550 ° C, and the time was 2 hours or higher and 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 and lower than 350 ° C, and the time was 2 hours or higher and lower than 5 hours. The cooling method after the homogenization treatment was air cooling in the atmosphere.

[0101] The number of intermediate heat treatments ranged from three to four. The wire diameter after intermediate heat treatment was 7.0 to 8.0 times the final wire diameter for the first intermediate annealing, 4.0 to 5.0 times for the second, and 2.5 to 3.5 times for the third. When four intermediate annealings were performed, intermediate annealing was performed at a wire diameter in the range of 5.5 to 6.5 times the final wire diameter. The temperature range for the first and second intermediate heat treatments was 300°C or higher but lower than 400°C, and the time was 1 hour or higher but lower than 3 hours. The temperature range for the third and fourth intermediate heat treatments was 200°C or higher but lower than 300°C, and the time was 4 hours or higher but lower than 48 hours. After wiredrawing, the wire was held at room temperature for 2 to 7 days before the intermediate heat treatment.

[0102] A commercially available lubricant was used during the wire drawing process, and the wire area reduction rate per die during the wire drawing process was 12.5% ​​or more and less than 16.0%. The temperature range of the final heat treatment was 250°C or more and less than 360°C, and the time of the final heat treatment was 2 hours or more and less than 20 hours.

[0103] In some examples, the wire was drawn using a die with a die angle of 14° or more and less than 18°.

[0104] (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) (manufactured by Hitachi High-Tech Science Corporation, "PS3520UVDDII") or an ICP-MS (Inductively Coupled Plasma-Mass Spectrometer) (manufactured by Agilent Technologies, Inc., "Agilent 7700x ICP-MS") as an analytical device.

[0105] (Method for measuring the orientation ratio of the crystal orientation of the Al phase) The L cross section (cross section in the central axis direction including the central axis) of the Al bonding wire or Al bonding ribbon was used as the inspection surface, and the crystal orientation of the Al phase was measured.

[0106] For the measurements, an FE-SEM (SU-70 manufactured by Hitachi High-Technologies Corporation) was used, and the analysis software used was APEX (for data collection), OIM Data Collection (for ChiScan), and OIM Analysis (for data analysis) manufactured by TSL Solutions. Three measurement areas were randomly selected at intervals of 50 cm or more relative to the central axis of the Al bonding wire or Al bonding ribbon, and measurements were performed on the three areas. The measurement area was determined so that it was 300 μm or more and less than 800 μm in the central axis direction of the Al bonding wire or Al bonding ribbon, and the entire Al bonding wire or Al bonding ribbon was included in the direction perpendicular to the central axis. The main conditions for the EDS and EBSD measurements were an acceleration voltage of 15 kV, a measurement magnification of 350x, a scan speed of 30 to 120 points / second, and a measurement interval in the range of 0.1 to 0.3 μm. Here, if the scanning speed is fast, the measurement time can be shortened, but there is a concern that the measurement accuracy of the EDS may decrease. It is desirable to select an appropriate scanning speed within the above range.

[0107] A SEM-EDS-EBSD device was used to measure the orientation ratio of the Al phase crystal orientation in the L-section of the Al bonding wire or Al bonding ribbon. This method combined the Al concentration and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD. More specifically, the measurements were performed according to the following procedures (1) to (3). (1) In the measurement area where the L-section of the Al bonding wire or Al bonding ribbon was used as the inspection surface, Al and Si concentration measurements were performed using EDS and crystal orientation measurements were performed using EBSD simultaneously. (2) Al and Si were separated and extracted using the Chi Scan function, a function of the EBSD analysis software. Specifically, Al and Si were separated and identified by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results. The Al and Si crystal information in the material file was used for crystal orientation analysis. Here, the tolerance condition was mainly set to 30% and adjusted as necessary. (3) The crystal orientation of the region identified as Al phase was analyzed, and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction and the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction were calculated. The crystal orientations to be investigated were selected from at least three types of typical crystal orientations of Al metal: <111>, <110>, and <100>, and, if necessary, a crystal orientation with a high ratio. Here, the orientation ratio of the crystal orientations was calculated using the partial ratio.

[0108] The orientation ratio of the <100> crystal orientation of the Al phase in the RD direction and the orientation ratio of the <110> crystal orientation of the Al phase in the ND direction were calculated as the average (arithmetic mean) of the values ​​obtained for the three measurement regions by the above steps (1) to (3).

[0109] (Method for Measuring the Average Diameter of Al Phase) To measure the average diameter of the Al phase in the L-section of an Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the orientation ratio of the crystal orientation of the Al phase. The method combined the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD. Specifically, after performing the above procedures (1) and (2), the measurement was performed according to the following procedure (3). (3) For the region identified as Al phase, the crystal orientation was analyzed, and if the orientation difference between the measurement points was 15° or more, it was determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain was calculated. The circle-equivalent diameters of each crystal grain were then averaged to calculate the average diameter of the Al phase. Here, for the average calculation, the average value obtained by the area average (area-weighted average) selectable in the software provided with the device was used. Furthermore, when calculating the average diameter of the Al phase in the L-section, only Al phases with a diameter (circle-equivalent diameter) of 0.5 μm or more were considered.

[0110] The average diameter of the Al 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).

[0111] (Method for Measuring the Average Diameter of Si Phase) To measure the average diameter of the Si phase in the L-section of an Al bonding wire or Al bonding ribbon, a SEM-EDS-EBSD device was used, similar to the measurement of the crystal orientation of the Al phase. The method combined the information on the Al concentration and Si concentration obtained by SEM-EDS with the information on the crystal orientation obtained by EBSD. Specifically, after performing the above procedures (1) and (2), the measurement was performed according to the following procedure (3). (3) For the region identified as the Si phase, the crystal orientation was analyzed, and if the orientation difference between the measurement points was 15° or more, it was determined to be a grain boundary, and the circle-equivalent diameter of each crystal grain was calculated. The circle-equivalent diameters of each crystal grain were then averaged to calculate the average diameter of the Si phase. Here, the average value obtained by area average (area-weighted average) was used in the average calculation. Furthermore, when calculating the average diameter of the Si phase in the L-section, only Si phases with a diameter (circle-equivalent diameter) of 0.5 μm or more were considered.

[0112] 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).

[0113] (Method for evaluating Al bonding wire or Al bonding ribbon) The evaluation method for Al bonding wire will be described. The wire diameter of the Al bonding wire used for evaluation was Φ300 μm. The semiconductor chip used was made of Si, and the electrodes on the semiconductor chip were made of a 4 μm thick film of an alloy with a composition of Al-0.5% Cu. The substrate used was an Al alloy with a 5 μm thick film of Ni. A commercially available wire bonder (manufactured by Ultrasonic Industries Co., Ltd.) was used to bond the Al bonding wire, and wedge bonding was used for both the first bonding (bonding to the electrode on the semiconductor chip) and the second bonding (bonding to the substrate). The Al bonding ribbon was bonded using a Hesse fully automatic bonder "BJ955" equipped with a ribbon bond head.

[0114] (Method for Evaluating Temperature Cycle Reliability) A commercially available thermal shock tester was used to evaluate the temperature cycle test. During the temperature cycle test, the sample chamber was moved between a low-temperature chamber and a high-temperature chamber, repeatedly increasing and decreasing the temperature. The low-temperature chamber temperature was set to -40°C, and the high-temperature chamber temperature was set to 175°C. One cycle consisted of the test starting with the sample chamber in the high-temperature chamber, moving it to the low-temperature chamber, and then returning to the high-temperature chamber. The sample chamber stayed in both the low-temperature and high-temperature chambers for 20 minutes. The samples used for the temperature cycle test had a structure in which a semiconductor chip was mounted on a substrate, and the electrodes on the semiconductor chip and the electrodes on the substrate were connected with Al bonding wire or Al bonding ribbon. After 2000 cycles, the samples were removed and subjected to a shear test on the first bond. The shear strength value of the first bond used to evaluate the temperature cycle reliability was the average shear strength of five randomly selected first bond locations. Evaluation was performed using the strength ratio (F2 / F1) of the shear strength value F2 after the temperature cycle test to the shear strength value F1 before the temperature cycle test. If the strength ratio was less than 50%, it was judged to have practical problems as an evaluation for SiC semiconductors and was given a rating of "0", if the strength ratio was 50% or more but less than 70%, it was judged to need improvement and was given a rating of "1", if the strength ratio was 70% or more but less than 75%, it was judged to be excellent and was given a rating of "2", and if the strength ratio was 75% or more, it was judged to be particularly excellent and was given a rating of "3". "0" and "1" are failures, and "2" and "3" are passes. The evaluation results are shown in the "Temperature cycle reliability" column in the table.

[0115] (Method for evaluating the variation in bond strength in temperature cycle test) In the above-mentioned temperature cycle test, shear strength measurements were performed on 20 first bonded portions after 2000 cycles. When evaluating the variation in bond strength in the temperature cycle test, the unbiased standard deviation (σ) of the shear strength was calculated. The unbiased standard deviation of the shear strength of the first bonded portion is not significantly affected by the conditions of the first bond, and is therefore useful as an index for appropriately evaluating the characteristics of the Al bonding wire or Al bonding ribbon. If σ is less than 30 gf, the variation in bond strength is particularly small, and it is judged to be excellent in stability, and it is rated as "3". If σ is 30 gf or more but less than 50 gf, it is judged to be small in variation in bond strength, and it is judged to be excellent in stability, and it is rated as "2". If σ is 50 gf or more but less than 70 gf, it is judged that the variation in bond strength is within the acceptable range and the stability is good, and it is rated as "1". If σ is 70 gf or more, it is judged that the variation in bond strength is large, and it is problematic in practical use, and it is recorded as "0". The evaluation results are shown in the column "Temperature cycle reliability bonding strength variation (2000 times)" in the table.

[0116] (Method for Evaluating Holes in First Bonded Joints) A method for evaluating hollow defects in first bonded joints will be described. First bonded joints were performed at 10 locations under typical bonding conditions, and the shear strength of the first bonded joints was measured. A commercially available microshear strength tester (Nordson 4000-PLUS) was used to measure the shear strength. The shear rate was 200 μm / sec, and the height of the shear tool was 10 μm from the electrode surface. The shear strength measurement was performed by fixing the substrate bonded with an Al bonding wire or Al bonding ribbon using a jig. After performing the shear strength test of the first bonded joint described above, the indentation on the fracture surface on the electrode side was observed using an optical microscope or SEM, and areas where metal bonding was not achieved within the fractured region were determined to be hollow. Holes in the first bonded joints were areas that were not bonded even when the electrode was deformed, and could be distinguished from areas where metal bonding was achieved. The shear strength test was performed under the conditions described above, and the fracture surfaces of 10 first bonded joints were observed. The ratio of the total length of the hollow region in the bonding width direction (K) to the bonding length (J) in the direction perpendicular to the central axis of the Al bonding wire or Al bonding ribbon (bonding width direction) was calculated as the hollow ratio (K / J) (Figure 3). The hollow ratio was confirmed on 10 fracture surfaces, and the maximum value was defined as the "hollow defect rate." A hollow defect rate of less than 5% was judged to be good and rated "3," 5% to 15% was judged to be acceptable for practical use and rated "2," 15% to 25% was judged to require improvement and rated "1," and 25% or more was judged to be an obstacle to mass production and rated "0." The evaluation results are listed in the "Hollow in 1st Bond" column in the table.

[0117] (Method for Evaluating Wire Breakage During Processing) The method for evaluating wire breakage during processing will be described below. Wire drawing was performed from a wire diameter of 6 mm to a wire diameter of 0.3 mm, and the number of wire breakages was confirmed. The wire drawing conditions, such as the feed rate and area reduction rate, were selected from the conditions described above, and the appropriate manufacturing conditions were adjusted and changed for each wire. The length of the drawn Al bonding wire ranged from 100 to 200 m, and the number of wire breakages was calculated by converting it to per 100 m. If the number of wire breakages was 0, it was judged to be good and rated as "3." If it was 1, it was judged that it could be addressed by improving the manufacturing conditions and rated as "2." If it was 2 to 4, it was judged that there was a decrease in productivity and rated as "1." If it was 5 or more, it was judged that it was difficult to use in practice and rated as "0." The evaluation results are shown in the "Wire Breakage During Processing" column in the table.

[0118] (Method for evaluating surface scratches and abrasions) The surface quality of the Al bonding wire or Al bonding ribbon was evaluated, focusing on scratches and abrasions. The wire diameter of the Al bonding wire was Φ300 μm. The Al bonding ribbon was 100 μm thick and 600 μm wide. Three measurement areas were randomly selected at intervals of 1 m or more along the central axis of the Al bonding wire or Al bonding ribbon, and three pieces of approximately 2 cm length were taken from each of the three locations, for a total of nine samples. Specifically, the surface was observed using an SEM at magnifications ranging from 50 to 500 times. Scratches longer than 50 μm and abrasions longer than 30 μm were judged to be defective. The number of scratches and abrasions was counted, and if there were zero, the sample was judged to be good and passed, giving a rating of "3." If there were one to two locations, the sample was judged to be acceptable for practical use, giving a rating of "2." If there were three to seven locations, the surface quality was judged to be poor, giving a rating of "1." If there were eight or more locations, the sample was judged to be difficult to use, giving a rating of "0." The evaluation results are shown in the "Surface properties" column in the table.

[0119] The evaluation results of the examples and comparative examples are shown in Tables 1 to 4. Examples 1 to 51 and Comparative Examples 1 to 10 in Tables 1 to 3 are results for Al bonding wires, and Examples B1 to B3 and Comparative Example B1 in Table 4 are results for Al bonding ribbons.

[0120]

[0121]

[0122]

[0123]

[0124] REFERENCE SIGNS LIST 1 Al bonding wire 10 Central axis 11 L-section 2 Al bonding ribbon 20 Central axis 21 L-section 3 Al bonding wire 30 Fracture portion 31 Hollow portion

Claims

1. An Al bonding wire or Al bonding ribbon containing 3.0% by mass or more and 20.0% by mass or less of Si, wherein, when the crystal orientation of the Al phase in the L-section (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 <110> crystal orientation, which has an angular difference of 15° or less with respect to the direction perpendicular to the central axis (ND direction), is 10% or more and 40% or less, and the orientation ratio of the <100> crystal orientation, which has an angular difference of 15° or less with respect to the direction parallel to the central axis (RD direction), is 15% or more and 50% or less.

2. An Al bonding wire or Al bonding ribbon as described in claim 1, wherein the average diameter of the Al phase in the L cross section is 5.0 μm or more and 40.0 μm or less.

3. An Al bonding wire or Al bonding ribbon as described in claim 1 or 2, wherein the average diameter of the Si phase in the L cross section is 0.8 μm or more and 4.0 μm or less.

4. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 3, further containing at least one of Sr, Na, Ni, and B in a total amount of 10 ppm by mass or more and 800 ppm by mass or less.

5. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 4, further containing at least one of Mn, Ti, Fe, Cu, and Mg in a total amount of 100 ppm by mass or more and 2000 ppm by mass or less.

6. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 5, wherein the total concentration of elements other than Al, Si, Sr, Na, Ni, B, Mn, Ti, Fe, Cu and Mg in the Al bonding wire or Al bonding ribbon is 0.5 mass% or less.

7. An Al bonding wire or Al bonding ribbon according to any one of claims 1 to 6, wherein the orientation ratio of the crystal orientation is a value measured using a SEM-EDS-EBSD device.

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

9. The Al bonding wire or Al bonding ribbon according to any one of claims 1 to 8, which is for use in a semiconductor device.

10. A semiconductor device comprising an Al bonding wire or an Al bonding ribbon according to any one of claims 1 to 9.

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