Al bonding wire or Al bonding ribbon

Abstract

This invention provides an Al bonding line or Al bonding strip that exhibits good temperature cycling reliability and good first-joint strength, as required in next-generation SiC power semiconductor devices, even during high-temperature temperature cycling tests. The Al bonding line or Al bonding strip contains 3.0% by mass or more and 20.0% by mass of Si. When the Si concentration (atomic %) in the depth direction from the surface of the Al bonding line or Al bonding strip is measured by X-ray photoelectron spectroscopy (XPS), the ratio of the average Si concentration Ca in region a (depth of 5 nm to 50 nm from the surface) to the average Si concentration Cb in region b (depth of 800 nm to 1200 nm from the surface) is 0.03 or more and 0.5 or less.

Description

Technical Field

[0001] This invention relates to an Al bonding wire or Al bonding tape. Background Technology

[0002] In semiconductor devices, bonding wires (wire materials) or bonding strips (strip materials) connect electrodes formed on a semiconductor chip to electrodes on a lead frame or substrate. Power semiconductor devices primarily use bonding wires or bonding strips made of aluminum (Al). Al bonding wires typically have a diameter ranging from 100 μm to 600 μm, while Al bonding strips generally have a width ranging from 100 μm to 3000 μm and a thickness ranging from 50 μm to 600 μm. Here, Al bonding wires or Al bonding strips are collectively referred to as Al bonding materials.

[0003] In power semiconductor devices, silicon (Si) is mostly used as the semiconductor chip material, and Al-Si alloys or Al-Cu alloys are mostly used as the electrode materials formed on the semiconductor chip. In addition, power semiconductor devices using Al bonding wires or Al bonding strips are mostly used in high-power equipment such as air conditioning or solar power generation systems, as well as automotive semiconductor devices.

[0004] Regarding the bonding methods for Al bonding wires or Al bonding strips, there are first bonding with electrodes on semiconductor chips and second bonding with electrodes on lead frames or substrates, both employing wedge bonding. Wedge bonding refers to a method where ultrasonic vibration and load are applied to the Al bonding wire or Al bonding strip using a metal clamp (appliance), breaking down the surface oxide film of the Al bonding wire or Al bonding strip and the electrode material to expose a newly formed surface, thus achieving solid-state diffusion bonding. This bonding method is characterized by bonding in a solid-state state without melting the bonding materials, and is a bonding technique different from welding techniques that melt the bonding materials.

[0005] In next-generation power semiconductor devices, stable operation over extended periods is required compared to general-purpose power semiconductor devices. Power semiconductor devices operate by repeatedly switching current on and off. When current is supplied to a Si semiconductor chip via Al bonding wires or Al bonding strips, the temperature of the first junction rises. Conversely, when the current supply is stopped, the temperature of the first junction drops. Thus, during the operation of the power semiconductor, the first junction repeatedly heats up and cools down. This subjects the first junction to repeated thermal stress caused by the difference in thermal expansion between the Al bonding wires or Al bonding strips and the semiconductor chip. When using Al bonding wires or Al bonding strips composed only of high-purity Al, the Al bonding wires or Al bonding strips are damaged in a short time due to thermal stress, making it difficult to meet the performance requirements of next-generation power semiconductor devices. Therefore, in next-generation power semiconductor devices, it is necessary to improve the junction lifetime (hereinafter also referred to as "temperature cycling reliability") accompanying the heating and cooling of the first junction.

[0006] To address the requirements for temperature cycling reliability, Al bonding wires with a primary focus on improving mechanical strength were proposed. As a method to enhance the mechanical properties of Al bonding wires, the addition of specific elements to Al was proposed.

[0007] Patent Document 1 discloses a bonding wire made of an Al alloy containing at least magnesium (Mg) and silicon (Si), wherein the combined content of Mg and Si is more than 0.03% by mass and less than 0.3% by mass. This patent document discloses a high-strength effect achieved through solid solution strengthening of Mg or Si, or an effect of inhibiting crack propagation through precipitated magnesium silicide (Mg2Si), thereby delaying the decrease in bonding strength of the first joint during cold temperature cycling tests in a temperature range of 70°C to 120°C.

[0008] Patent Document 2 discloses a bonding wire characterized by being composed of an alloy containing 0.01 to 0.2% by mass of iron (Fe), 1 to 20 ppm by mass of silicon (Si), and the remainder being Al with a purity of 99.997% by mass or higher. The Fe solid solution content is 0.01 to 0.06%, the Fe precipitation is less than 7 times the Fe solid solution content, and the average crystal grain size is 6 to 12 μm, forming a fine microstructure. This patent document discloses a method to uniformly disperse intermetallic compound particles of Fe and Al within Al, thereby improving the mechanical strength of the matrix, and further refining the recrystallized particles, thereby suppressing the decrease in the bonding strength of the first bonding portion during thermal shock testing in a temperature range of -50°C to 200°C.

[0009] Patent document 3 discloses a bonding wire made by melting an Al-Si alloy containing 0.1 to 5% by mass of silicon (Si), with the remainder consisting of Al and impurities, then spraying and rapidly cooling the melted alloy to form a fine wire. This patent document discloses that by rapidly cooling the molten Al-Si alloy and dispersing the Si finely and uniformly, the mechanical strength is improved.

[0010] Prior art literature

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2014-131010

[0013] Patent Document 2: Japanese Patent Application Publication No. 2014-129578

[0014] Patent Document 3: Japanese Patent Application Publication No. 59-57440 Summary of the Invention

[0015] As mentioned above, next-generation power semiconductor devices are required to withstand longer periods of use compared to general-purpose power semiconductor devices. During operation, the temperature of the first junction repeatedly rises and falls. As a result, the Al bonding wires or Al bonding strips, due to their larger coefficient of linear thermal expansion than the semiconductor chip, experience thermal stress at the first junction caused by the difference in their coefficients of linear thermal expansion (and the difference in their linear thermal expansion), potentially leading to fatigue failure of the Al bonding wires or Al bonding strips. Temperature cycling testing is one of the tests used to accelerate the evaluation of the junction's lifespan (temperature cycling reliability) during the temperature rise and fall associated with this first junction. Al bonding wires or Al bonding strips used in next-generation power semiconductor devices are required to exhibit excellent temperature cycling reliability in temperature cycling tests.

[0016] Previously, the use of silicon carbide (SiC), with its higher heat resistance, was predicted to advance in next-generation power semiconductor devices that would replace the mainstream silicon (Si) power semiconductor devices. Connections for SiC power semiconductor devices require more stringent temperature cycling reliability under more demanding conditions than existing technologies. For example, while Si power semiconductor devices require temperature cycling reliability within a range of -40°C to 150°C, SiC power semiconductor devices, as a stringent requirement, need temperature cycling reliability within a range of -40°C to 175°C.

[0017] Furthermore, in next-generation SiC power semiconductor devices that utilize the heat resistance of SiC for high output, it is necessary to maintain good temperature cycling reliability even under stringent testing conditions where the upper limit of the temperature cycling test is increased to 185°C. When the upper limit of the temperature cycling test is further increased from 175°C to 185°C, a problem arises: the temperature difference during temperature cycling increases by 10°C, amplifying the aforementioned difference in linear thermal expansion at the junction of Al bonding lines or Al bonding strips, thus accelerating fatigue failure.

[0018] Furthermore, during bonding, if poor bonding occurs, such as Al bonding lines or Al bonding bands peeling off from the electrodes, it can lead to product defects or reduced manufacturing yield. Therefore, it is necessary to obtain good bonding strength in each bonding joint. Regarding this, in the first bonding joint, to obtain good bonding strength, the semiconductor chip can sometimes be damaged when subjected to strong ultrasonic vibration or load. In particular, when using Al bonding lines or Al bonding bands with increased strength through the addition of Si, their hardness can easily damage the semiconductor chip during the first bonding. When adjusting the ultrasonic vibration or load to reduce such damage, the following issues arise: due to the high deformation resistance or instability of the deformation direction, it is impossible to stably ensure the bonding area, etc., and thus insufficient bonding strength (hereinafter also referred to as "first bonding strength") of the first bonding joint cannot be obtained. These initial bonding problems of the first bonding joint further become a major factor in the reduction or instability of temperature cycling reliability, thus hindering the practical application of Al bonding lines or Al bonding bands with increased strength due to the addition of Si.

[0019] The present invention was made in view of the above-mentioned problems, and its object is to provide an Al bonding line or Al bonding strip that exhibits good temperature cycling reliability and good first bonding strength, as required in next-generation SiC power semiconductor devices and in high-temperature temperature cycling tests.

[0020] Technical means for solving technical problems

[0021] The inventors have conducted dedicated research to address the aforementioned problems and discovered that an Al bonding line or Al bonding band can solve these problems. Based on this understanding, further repeated research led to the completion of this invention. The Al bonding line or Al bonding band contains 3.0% by mass or more and 20.0% by mass of Si, and when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding line or Al bonding band is measured by X-ray photoelectron spectroscopy (XPS), the ratio Ca / Cb of the average Si concentration Ca in region a with a depth of 5 nm or more and 50 nm or less from the surface to the average Si concentration Cb in region b with a depth of 800 nm or more and 1200 nm or less from the surface is 0.03 or more and 0.5 or less.

[0022] That is, the present invention includes the following contents.

[0023] <1>

[0024] An Al bonding wire or Al bonding strip containing 3.0% by mass and less than 20.0% by mass of Si.

[0025] When the Si concentration (atomic %) in the depth direction from the surface of the Al bonding line or Al bonding band was determined by X-ray photoelectron spectroscopy (XPS), the ratio of the average Si concentration Ca in region a (depth of 5 nm to 50 nm from the surface) to the average Si concentration Cb in region b (depth of 800 nm to 1200 nm from the surface) was 0.03 to 0.5.

[0026] <2>

[0027] As described in <1>, the Al bonding line or Al bonding strip, wherein...

[0028] The average diameter of the Si phase in the L-section (including the section in the direction of the central axis) of the Al bonding line or Al bonding band is greater than 0.8 μm and less than 4 μm.

[0029] <3>

[0030] As described in <1> or <2>, the Al bonding line or Al bonding strip, wherein,

[0031] The average concentration of Si element Cf in the region f, which is 5 nm or more and 30 nm or less from the surface, is 0.1 atomic% or more and 4 atomic% or less.

[0032] <4>

[0033] As described in any one of <1> to <3>, the Al bonding line or Al bonding strip, wherein...

[0034] When the crystal orientation of the Al phase in the L section (including the section in the direction of the central axis) of the Al bonding line or Al bonding band is determined, the orientation ratio of <100> crystal orientation with an angle difference of less than 15° from the direction parallel to the central axis (RD direction) is more than 15% and less than 50%.

[0035] <5>

[0036] The Al bonding line or Al bonding band as described in any one of <1> to <4> further contains more than 10 ppm by mass and less than 800 ppm by mass of any one or more of Sr, Na, P and B.

[0037] <6>

[0038] The Al bonding line or Al bonding band as described in any one of <1> to <5> further contains more than 100 ppm by mass and less than 2000 ppm by mass of any one or more of Ni, Ti, Fe, Zn and Mg.

[0039] <7>

[0040] As described in any one of <1> to <6>, the Al bonding line or Al bonding strip, wherein...

[0041] The total concentration of elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn and Mg in the Al bonding line or Al bonding band is less than 0.5% by mass.

[0042] <8>

[0043] As described in any one of <2> to <7>, the Al bonding line or Al bonding strip, wherein...

[0044] The average diameter of the Si phase was measured using a SEM-EDS-EBSD instrument.

[0045] <9>

[0046] As described in any one of <4> to <8>, the Al bonding line or Al bonding strip, wherein...

[0047] The orientation ratio of the crystal orientation is the value measured using a SEM-EDS-EBSD device.

[0048] <10>

[0049] Al bonding wires or Al bonding strips as described in any one of <1> to <9> are used in semiconductor devices.

[0050] <11>

[0051] A semiconductor device comprising an Al bonding line or Al bonding strip as described in any one of <1> to <10>.

[0052] Invention Effects

[0053] According to the present invention, it is possible to provide an Al bonding line or Al bonding strip that exhibits good temperature cycling reliability and good first bonding strength, as required in next-generation SiC power semiconductor devices, even in high-temperature temperature cycling tests. Attached Figure Description

[0054] Figure 1 This illustrates an example of the Si concentration distribution when the Si concentration in the depth direction was measured and evaluated using XPS for the Al bonding line or Al bonding line of the present invention. The distribution of Si concentration in the depth direction is shown when the total amount of metallic Si and metallic Al is set to 100 atomic percent.

[0055] Figure 2 This represents an example of the peak value of SiO valence of Si2p obtained by XPS for the Al bonding line or Al bonding strip of the present invention. Figure 2 This figure is used to illustrate the quantitative analysis of Si element based on the peak value of Si0 valence in Si2p.

[0056] Figure 3 This is a schematic diagram illustrating the measurement surface (inspection surface) used to determine the crystal orientation of the Al phase and the average diameter of the Si phase in relation to the Al junction line. The measurement surface is a cross-section (L-section) along the central axis direction containing the central axis of the Al junction line.

[0057] Figure 4 This is a schematic diagram illustrating the measurement surface (inspection surface) used to determine the crystal orientation of the Al phase and the average diameter of the Si phase, specifically for the Al bonding zone. The measurement surface is a cross-section (L-section) along the central axis direction, including the central axis of the Al bonding zone. Detailed Implementation

[0058] Hereinafter, the present invention will be described in detail according to its preferred embodiments. In the description, reference will sometimes be made to the accompanying drawings, but the drawings are only intended to illustrate the shape, size, and arrangement of the constituent elements to a general extent. The present invention is not limited to the embodiments and examples described below, and can be implemented in any way without departing from the scope of protection of the present invention and its equivalents.

[0059] [Al bonding line or Al bonding strip]

[0060] The Al bonding line or Al bonding band of the present invention is characterized in that, when the Si concentration (atomic %) in the depth direction from the surface of the Al bonding line or Al bonding band is measured by X-ray photoelectron spectroscopy (XPS), the ratio of the average concentration Ca of Si element in region a with a depth of 5 nm or more and 50 nm or less from the surface to the average concentration Cb of Si element in region b with a depth of 800 nm or more and 1200 nm or less from the surface, Ca / Cb, is 0.03 or more and 0.5 or less.

[0061] As mentioned earlier, in temperature cycling tests (hereinafter also referred to as "TCT"), when using Al bonding lines or Al bonding bands composed only of high-purity Al, a problem arises because cracks propagate relatively quickly within these Al bonding lines or Al bonding bands, reducing temperature cycling reliability. It has been confirmed that by using Al alloys with a high concentration of added Si, the thermal expansion of the Al bonding lines or Al bonding bands can be reduced, improving temperature cycling reliability. On the other hand, when using Al alloys with a high concentration of added Si, there are cases where sufficient temperature cycling reliability cannot be achieved in high-temperature cycling tests (hereinafter also referred to as "high-temperature temperature cycling tests" or "high-temperature TCT") with relatively high upper temperature limits (e.g., 185°C). As mentioned earlier, in next-generation power semiconductor devices with high heat resistance, such as SiC power semiconductor devices, good temperature cycling reliability is required even in high-temperature temperature cycling tests under the aforementioned stringent test conditions, necessitating further improvements in temperature cycling reliability.

[0062] It was confirmed that during high-temperature cycling tests, defects are accelerated near the initial joint interface of the first Al bond line or Al bond band. Regarding the bonding method of Al bond lines or Al bond bands, diffusion at the joint interface is typically suppressed due to room temperature bonding, thus increasing the influence of the surface condition of the Al bond line or Al bond band on the bonding performance. During high-temperature cycling tests, the increased temperature difference during cycling amplifies the difference in linear thermal expansion at the joint, leading to thermal strain concentration near the joint interface from an earlier stage. Therefore, the surface condition of the Al bond line or Al bond band may become a major cause of accelerated crack propagation. Since crack growth at the joint interface or crack propagation within the Al bond line or Al bond band also accelerates the decrease in temperature cycling reliability.

[0063] Regarding the propagation of cracks at the interface, which is a major factor in reliability degradation during high-temperature cycling tests, the inventors have discovered that surface modification of Al bonding lines or Al bonding bands is effective. In Al bonding lines or Al bonding bands composed of Al alloys with high Si concentrations (hereinafter also referred to as "high-concentration Al-Si alloys"), the surface condition has a greater impact on temperature cycling reliability. Specifically, it has been found that for Al bonding lines or Al bonding bands composed of high-concentration Al-Si alloys, by setting a predetermined slope (gradient) of Si concentration in the depth direction in a region from its surface to a certain depth—specifically, by setting a Si concentration slope such that the ratio Ca / Cb of the average Si concentration Ca in region a (depth of 5 nm to 50 nm from the surface) to the average Si concentration Cb in region b (depth of 800 nm to 1200 nm from the surface) is 0.03 to 0.5—crack propagation near the interface can be suppressed even during high-temperature cycling tests, thus achieving good temperature cycling reliability. Furthermore, it has been found that by modifying the surface of the Al bonding line or Al bonding band composed of a high-concentration Al-Si alloy with a slope having the aforementioned predetermined Si concentration, the problem of initial bonding of the first bonding portion can be solved, and good first bonding strength can be achieved.

[0064] The reasons why the Al bonding wire or Al bonding strip of the present invention also exhibits good temperature cycling reliability and good first bonding strength in high-temperature temperature cycling tests are speculated as follows.

[0065] It is believed that for Al bonding lines or Al bonding bands composed of high-concentration Al-Si alloys, setting a predetermined slope for the Si concentration in the depth direction from the surface to a certain depth—that is, setting a slope for the Si concentration such that the Si concentration near the surface is low and the Si concentration at depth is high, while satisfying the aforementioned Ca / Cb ratio condition—results in increased surface deformability of the Al bonding line or Al bonding band under ultrasonic vibration or load during bonding, promoted destruction of the surface oxide film, and promoted diffusion of Al atoms at the bonding interface. As a result, the bonding strength increases and the deformation shape stabilizes, which in turn helps maintain a strong bond at the bonding interface during temperature cycling tests. The main factor contributing to these effects is believed to be that, in the region from the surface of the Al bonding line or Al bonding band to a certain depth, the surface side is relatively softer and has higher purity compared to the depth (from the perspective of Al concentration). It is believed that on the surface side, the interface control effect caused by the low concentration slope of Si, the help of the reduction of the difference in linear thermal expansion coefficient caused by the internal Si phase (described later), and the resulting reduction in thermal stress will work synergistically. As a result, a significant effect of achieving good temperature cycling reliability will be achieved in the high-temperature cycling test with an upper limit temperature of 185°C.

[0066] As described above, the Al bonding line or Al bonding strip of the present invention modifies the surface in a region from its surface to a certain depth, such that the Si concentration in the depth direction has a predetermined slope. As a result, it is presumed that, as mentioned above, it can also exhibit good temperature cycling reliability in high-temperature temperature cycling tests and can exhibit good first bonding strength.

[0067] Hereinafter, the structure of the Al bonding line or Al bonding strip of the present invention will be described in detail. Hereinafter, the Al bonding line or Al bonding strip will also be collectively referred to as "Al bonding line, etc." or "line, etc."

[0068] -Si concentration-

[0069] The Al bonding wire or Al bonding strip of the present invention contains 3.0% by mass or more and 20.0% by mass or less of Si.

[0070] A Si concentration of 3.0% by mass or higher and 20.0% by mass or lower helps reduce thermal strain at the joint and improves temperature cycling characteristics. Specifically, a Si concentration of 3.0% by mass or higher can significantly improve temperature cycling reliability even in high-temperature temperature cycling tests. Furthermore, regarding the upper limit of Si concentration, with the advancement and optimization of equipment and conditions used for wire manufacturing and bonding, it is possible to suppress defects such as wire breakage and surface deterioration during processing, reduction in initial bond strength due to hardening, or damage to the semiconductor chip, while allowing for higher costs. However, a Si concentration of 20.0% by mass or lower can effectively suppress these defects and achieve the expected temperature cycling reliability. From the viewpoint of achieving good temperature cycling reliability even in high-temperature temperature cycling tests, the concentration of Si in the Al bonding wires, etc., of the present invention is 3.0% by mass or more, preferably 3.5% by mass or more, more preferably 4.0% by mass or more, and even more preferably 4.2% by mass or more, 4.4% by mass or more, 4.5% by mass or more, 4.6% by mass or more, 4.8% by mass or more, or 5.0% by mass or more. Furthermore, from the viewpoint of effectively suppressing defects such as the reduction in initial bonding strength and damage to the semiconductor chip caused by hardening, while simultaneously achieving the expected temperature cycling reliability, the concentration of Si in the Al bonding wires, etc., of the present invention is 20.0% by mass or less, preferably 19.0% by mass or less, 18.0% by mass or less, 17.0% by mass or less, 16.0% by mass or less, 15.0% by mass or less, 14.5% by mass or less, 14.0% by mass or less, 13.5% by mass or less, 13.0% by mass or less, or 12.5% ​​by mass or less. Furthermore, when the hardness of the Al bonding wire, etc., is high, damage to the semiconductor chip is more likely to occur during the first bonding due to ultrasonic vibration and the bonding conditions of the load. From the viewpoint of obtaining good bonding strength under a wider range of bonding conditions, the Si concentration in the Al bonding wire, etc., of the present invention is more preferably 12.0% by mass or less, more preferably 11.5% by mass or less or 11.0% by mass or less, and particularly preferably 10.8% by mass or less, 10.6% by mass or less, 10.5% by mass or less, 10.4% by mass or less, 10.2% by mass or less or 10.0% by mass or less.

[0071] For the concentration analysis of elements contained in the Al bonding lines of the present invention, an ICP (Inductively Coupled Plasma) luminescence spectrophotometer or an ICP mass spectrometer can be used. In cases where elements originating from atmospheric pollutants, such as oxygen or carbon, are adsorbed on the surface of the Al bonding lines, it is effective to clean them with acid or alkali according to the adsorbed substances before analysis.

[0072] The Al bonding wires and the like of the present invention contain 3.0% by mass and 20.0% by mass of Si, and are composed of an Al phase in which Si is dissolved in Al, and a Si phase formed by Si crystallization or precipitation. Here, regarding the Al phase, other additive elements besides Si can also be dissolved in solid. Furthermore, the Si phase is a general term for Si crystals and Si precipitates. Si crystals are formed from the molten liquid during solidification and are relatively coarse with a size of about 1 to 25 μm. In contrast, Si precipitates are formed in a solid state and are smaller with a size of about 0.1 to several μm. Compared to Al, the Si phase has a smaller coefficient of linear thermal expansion, which helps to reduce the difference in the coefficient of linear thermal expansion between the Al bonding wires and the semiconductor chip, and can reduce thermal stress, thereby improving temperature cycling reliability.

[0073] -Slope of Si concentration-

[0074] When the Si concentration (atomic %) in the depth direction from the surface of the Al bonding line or Al bonding band of the present invention is measured by X-ray photoelectron spectroscopy (XPS), the ratio of the average Si concentration Ca in region a with a depth of 5 nm or more and 50 nm or less from the surface to the average Si concentration Cb in region b with a depth of 800 nm or more and 1200 nm or less from the surface, Ca / Cb, is 0.03 or more and 0.5 or less.

[0075] In this invention, the slope of the Si concentration along the depth direction is measured and evaluated using X-ray photoelectron spectroscopy (XPS). XPS allows for high-precision quantitative analysis along the surface depth direction from Al bonding lines and similar surfaces using the sputtering operation of the apparatus. By using XPS, low concentrations of Si, such as approximately 0.1 atomic%, can be accurately determined.

[0076] In this invention, when measuring and evaluating the slope of Si concentration in the depth direction using XPS, the Si concentration is determined when the total amount of metallic Si and metallic Al is set to 100 atomic%.

[0077] exist Figure 1 The diagram illustrates an example of the Si concentration distribution when measuring and evaluating the Si concentration in the depth direction using XPS for the Al bonding line or Al bonding strip of the present invention. In a region from the surface to a certain depth, a predetermined slope can be identified for the Si concentration in the depth direction; that is, a slope where the Si concentration is low on the surface side, high at depth, and gradually increases in the depth direction.

[0078] Regarding the morphology of Si detected by XPS, solid-solution Si in the Al phase, Si particles (precipitated, crystallized), and Si-containing intermetallic compounds are all considered. The sources of the detected Si vary as described above, but these are not differentiated. Instead, based on the Si concentration detected by XPS, it is determined whether a predetermined slope of Si concentration (the aforementioned ratio Ca / Cb) is met. By doing so, the slope of the Si concentration along the depth direction measured by XPS is adjusted, thereby solving and achieving the desired problem and effect, which is an important feature of this invention.

[0079] The Si concentration is determined based on the peak value of metallic Si (Si with a valence of 0) detected by XPS. Since the detected energies of metallic Si and Si oxide peak values ​​differ, the concentration of metallic Si can be determined separately from Si oxide. The concentration of metallic Si in the surface region of Al bond lines or Al bond bands affects temperature cycling reliability and first bond strength. It is confirmed that Si oxide is rarely formed on the surface of Al bond lines or Al bond bands or on the surface of Si particles. Furthermore, even if it is formed, the Si oxide layer is quite thin, and therefore has virtually no impact on temperature cycling reliability and first bond strength. Therefore, it is excluded from the analysis in determining the concentration slope of this invention.

[0080] In this invention, when the Si concentration in the depth direction is measured from the surface of the Al bonding line or Al bonding band by XPS, the ratio of the average Si concentration Ca in region a with a depth of 5 nm or more and 50 nm or less from the surface to the average Si concentration Cb in region b with a depth of 800 nm or more and 1200 nm from the surface, Ca / Cb, is in the range of 0.03 or more and 0.5 or less.

[0081] The reason for using the average Si concentration Ca in region a, which is 5 nm to 50 nm below the surface, is that region a is deformed due to ultrasonic vibration and load application during bonding, significantly affecting the performance of the bonding interface. The analysis of the outermost region, less than 5 nm below the surface, is susceptible to surface contamination, leading to larger deviations in Si concentration measured by XPS; therefore, it is excluded from the analysis range. Furthermore, regions with a depth exceeding 50 nm have less impact on the bonding interface and are also excluded from the analysis range. The reason for using the average Si concentration Cb in region b, which is 800 nm to 1200 nm below the surface, is that it represents an appropriate depth range for determining the Si concentration characteristic of the internal composition of Al bonding lines or Al bonding bands, considering the relatively stable Si concentration and the need to avoid long sputtering times during measurement to ensure analytical efficiency. Furthermore, for both region a (depth of 5 nm to 50 nm) and region b (depth of 800 nm to 1200 nm), the slope of the Si concentration is evaluated by using the ratio Ca / Cb based on the average Si concentrations (Ca and Cb), thus minimizing the influence of Si concentration deviations. Additionally, by comparing the average Si concentration Cb in region b (measured by XPS) within the sample with the average Si concentration Ca in region a (measured using the same method) on the sample surface, the ratio Ca / Cb is calculated, which is effective for accurately determining the slope of the Si concentration in the depth direction. Therefore, it is possible to determine with high precision whether the slope of the Si concentration in the depth direction is suitable for achieving good temperature cycling reliability and good first-bond strength in Al bond lines or Al bond bands that exhibit good bonding strength in high-temperature temperature cycling tests.

[0082] When the relative Si concentration near the surface and at depth, i.e., the Ca / Cb ratio, is in the range of 0.03 or higher and 0.5 or lower, the Al bond line or Al bond band exhibits good temperature cycling reliability and good first-order bond strength, due to the increased surface deformability of the Al bond line or Al bond band when ultrasonic vibration or load is applied during bonding, the promotion of surface oxide film destruction, and the promotion of Al atom diffusion at the bonding interface. From the viewpoint of achieving Al bond lines or Al bond bands that exhibit even better temperature cycling reliability and better first-order bond strength in high-temperature temperature cycling tests, the Ca / Cb ratio is preferably 0.48 or lower, more preferably 0.46 or lower, and even more preferably 0.45 or lower, 0.44 or lower, 0.42 or lower, or 0.4 or lower. The lower limit of the Ca / Cb ratio is 0.03 or higher, which can solve and achieve the expected problems and effects. However, it can also be 0.04 or higher, 0.05 or higher, 0.06 or higher, 0.08 or higher, or 0.1 or higher. In particular, when the Ca / Cb ratio is 0.45 or lower, exceptionally good temperature cycling reliability can be achieved in high-temperature temperature cycling tests, and better first bond strength can be easily achieved, which is preferred.

[0083] In this invention, the relative ratio of Si concentration near the surface to that at depth, namely the Ca / Cb ratio, is controlled within a certain range of 0.03 or higher and 0.5 or lower. This achieves Al bonding lines or Al bonding bands that exhibit good temperature cycling reliability and good first bonding strength even in high-temperature temperature cycling tests. It has also been found that controlling the Ca / Cb ratio within a certain range is effective and important in solving the problem.

[0084] In this invention, the Si concentration in the depth direction in a region from the surface of an Al bonding line or Al bonding band to a certain depth can be obtained by performing compositional analysis via XPS while digging down along the depth direction (towards the center of the line, etc.) from the surface of the Al bonding line or Al bonding band by Ar sputtering. Specifically, it is possible to repeat 1) Ar-based sputtering and 2) compositional analysis of the sputtered surface to obtain the Si element concentration variation (so-called depth direction concentration distribution) in the depth (center) direction from the surface of the Al bonding line or Al bonding band.

[0085] In one embodiment, the Si concentration in the depth direction in a region from the surface of the Al bonding line or Al bonding strip of the present invention to a certain depth is determined by the following steps (1) to (4).

[0086] (1) Preparation of test samples

[0087] The sample containing the Al bonding line or Al bonding band to be measured is placed on the sample stage. At this time, the position is adjusted on the XPS device's operating screen so that the length direction of the sample is transverse. Additionally, if the sample is an Al bonding band (with a rectangular or approximately rectangular cross-sectional shape having a width W and a thickness T), it is positioned so that the direction of the width W is parallel to the surface of the sample stage, and the direction of the thickness T is perpendicular to the surface of the sample stage.

[0088] (2) XPS-based measurement

[0089] In XPS-based measurements, the measurement area is selected while observing the SXI (Scanning X-ray Image) image of the device, ensuring that the area near the vertex of the Al junction line or Al junction band is included in the measurement region. Here, the vertex of the Al junction line or Al junction band is defined as the position directly above the central axis of the sample when viewed from above. Furthermore, under the following conditions, 1) Ar-based sputtering and 2) post-sputtering surface composition analysis were repeated, with depth measurements performed from the sample surface, and the spectra of Si2p and Al2p were detected. The peak values ​​of the Si2p and Al2p spectra were detected at energies of approximately 98.5–99.5 eV and 71.5–73.0 eV, respectively.

[0090] • Measuring apparatus: ULVAC-PHI Versa Probe3

[0091] • Ultimate vacuum level: Approximately 1×10 -8 Torr

[0092] • X-ray source: Monochromatic Al (1486.6 eV)

[0093] • Measurement area: 100μm (sample length direction) × 20μm (sample circumference direction) quadrilateral

[0094] • Photoelectron extraction angle: 45 degrees

[0095] • Detection depth: several nm

[0096] •Ar sputtering

[0097] Accelerating voltage; 2kV

[0098] Sputtering area; 2×2mm quadrilateral

[0099] Sputtering rate: 9.2 nm / min (SiO2 conversion)

[0100] • Analysis pitch in the depth direction: 5nm pitch (depth range of 0-50nm from the surface), 10nm pitch (depth range of 50-200nm from the surface), 20nm pitch (depth range of more than 200nm from the surface).

[0101] As described above, in XPS-based measurements, the sputtering velocity and depth can be calculated using standard SiO2 conversions. Furthermore, considering analytical accuracy, measurement time, and operability, the depth-direction analytical pitch can be selected finely on the surface and coarsely at deeper depths. For example, as mentioned above, a 5nm pitch can be set for depths of 0–50 nm from the surface, a 10nm pitch for depths of 50–200 nm from the surface, and a 200nm pitch for depths exceeding 200 nm from the surface.

[0102] (3) Quantitative analysis of each element in Si and Al

[0103] Based on the detection spectra of Si2p and Al2p obtained from the surface of the sample at various depths in the depth direction, the elements of Si and Al are quantified in the following order.

[0104] In detail, the quantification of Si is performed within the energy range (approximately 95.0–101.0 eV) of the peak energy of Si0 valence (metallic Si) containing Si2p. Adjustments were made within this quantification range for the energy values ​​at the low and high energy ends, based on factors such as the shape of the peak. The background of the quantification range was determined using the Shirley method, and the Si element was quantified using the peak area obtained by subtracting the background.

[0105] exist Figure 2 The diagram illustrates an example of the peak value of the SiO valence of Si2p obtained by XPS for the Al bonding line or Al bonding band of the present invention. The peak value of the SiO valence of Si2p is contained in a quantitative range of about 95.0 to 101.0 eV, with the low energy end of the peak value being between 95 and 96.5 eV and the high energy end being selectable between 99.8 and 101.3 eV.

[0106] The quantitative analysis of Al was performed using the same steps as the quantitative analysis of Si, targeting the energy range (approximately 69.0–79.0 eV) of the peak energy of Al0 valence (metallic Al) containing Al2p.

[0107] (4) Calculation of Si concentration

[0108] Using the quantitative values ​​of Si and Al at each depth along the depth direction from the sample surface, and the relative sensitivity coefficients of each element set in the XPS device, the Si concentration (atomic %) at which the total Si and Al at each depth along the depth direction from the sample surface reaches 100 atomic %. Additionally, C, which is not affected by contaminants on the sample surface, is included in the analysis. Then, the arithmetic mean of the Si concentration in region a (depth of 5 nm to 50 nm from the surface) is denoted as the average concentration Ca, the arithmetic mean of the Si concentration in region b (depth of 800 nm to 1200 nm from the surface) is denoted as the average concentration Cb, and the arithmetic mean of the Si concentration in region f (depth of 5 nm to 30 nm from the surface) is denoted as the average concentration Cf.

[0109] In this invention, the slope of the Si concentration in the depth direction and the average concentration of Si near the surface (described later) are evaluated by averaging (arithmetic mean) the values ​​obtained from measuring at two or more locations. From the viewpoint of ensuring the objectivity of the measurement data, it is preferable to use two or more samples randomly selected from a plurality of samples obtained at intervals of 50 cm or more relative to the central axis of the Al bonding line or Al bonding band of the object to be measured for measurement. The average concentration Ca, average concentration Cb, and average concentration Cf are set as the average (arithmetic mean) of the values ​​obtained for each sample through steps (1) to (4) above.

[0110] -Average concentration of Si near the surface-

[0111] Regarding the Al bonding line or Al bonding strip of the present invention, when the Si concentration (atomic %) in the depth direction is measured from the surface of the Al bonding line or Al bonding strip by XPS, it is preferable that a predetermined slope of Si concentration (the above ratio Ca / Cb) is satisfied, and furthermore, the average concentration Cf of Si element in the region f at a depth of 5 nm or more and 30 nm or less from the surface is 0.1 atomic % or more and 4 atomic % or less.

[0112] By controlling the average concentration Cf of Si element in the region f near the surface within the aforementioned range, in addition to satisfying the predetermined slope of the Si concentration (the aforementioned ratio Ca / Cb), the lifespan (number of cycles until defect occurs) of Al bonding lines or Al bonding bands can be further improved during high-temperature cycling tests. By suppressing this average concentration Cf to a lower level within the aforementioned range, it becomes possible to promote softening and recrystallization near the surface of Al bonding lines, improve deformability during bonding, and form a flat bonding interface. As a result, it is believed that the lifespan of Al bonding lines, etc., can be further improved during high-temperature cycling tests. From the viewpoint of being able to further improve the lifespan of Al bonding lines, etc., during high-temperature cycling tests, the average concentration Cf of Si element in the region f near the surface is more preferably 3.8 atomic% or less or 3.6 atomic% or less, and more preferably 3.5 atomic% or less, 3.4 atomic% or less, 3.2 atomic% or less, or 3 atomic% or less. Regarding the lower limit of the average concentration Cf, it is preferably 0.1 atomic% or more, for example, it could also be 0.12 atomic% or more, 0.14 atomic% or more, 0.15 atomic% or more, 0.16 atomic% or more, 0.18 atomic% or more, or 0.2 atomic% or more, etc. The reason for using the average concentration Cf of Si element in the region f near the surface is that this region f has a significant impact on the temperature cycling reliability and lifespan in high-temperature temperature cycling tests.

[0113] By controlling the average Si concentration Cf near the surface to be lower than the Si concentration Ct in the Al bonding line or Al bonding band as a whole, the aforementioned improvement in lifetime can be further improved. Preferably, in one embodiment, the ratio Cf / Ct of the surface Si concentration Cf to the Si concentration Ct in the Al bonding line or Al bonding band as a whole is in the range of 0.03 or higher and 0.8 or lower. Here, the Si concentration Ct is based on the Si concentration in the Al bonding line or Al bonding band as determined by an ICP emission spectrophotometer and an ICP quality analyzer. From the viewpoint of achieving better temperature cycling reliability in high-temperature temperature cycling tests, it is more preferable that this ratio Cf / Ct is 0.7 or lower, and even more preferably 0.6 or lower, 0.55 or lower, or 0.5 or lower. Furthermore, it is preferable that the lower limit of this ratio Cf / Ct is 0.03 or higher, but it may also be, for example, 0.04 or higher, 0.05 or higher, 0.06 or higher, 0.08 or higher, or 0.1 or higher. By controlling the ratio Cf / Ct within the above range, deformation near the surface of the Al bonding line or Al bonding strip when ultrasonic vibration or load is applied during bonding can be promoted, and metal bonding at the bonding interface can be promoted. As a result, a higher effect can be obtained in improving the life of the Al bonding line or Al bonding strip in high-temperature temperature cycling tests.

[0114] As described above, in this invention, the slope of the Si concentration in the depth direction and the concentration of Si near the surface are measured and evaluated using XPS. By using XPS, it is possible to accurately measure low concentrations of Si (approximately 0.1 atomic%), and to determine with high precision whether conditions are met for Al bond lines or Al bond bands exhibiting good temperature cycling reliability and first-order bond strength, suitable for achieving such bonding.

[0115] -Average diameter of Si phase in section L-

[0116] Regarding the Al bonding line or Al bonding strip of the present invention, it is preferred that the average diameter of the Si phase in its L-section (the section including the central axis direction of the central axis) is 0.8 μm or more and 4 μm or less.

[0117] In this invention, the central axis of the Al bonding line, the cross section (L section) including the central axis direction, and the direction parallel to the central axis (RD direction) described later are as follows: Figure 3 As shown. In Figure 3In the example shown, an Al joint line with a circular cross-sectional shape is depicted. However, in the case of an Al joint strip with a rectangular or approximately rectangular cross-sectional shape having 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. Furthermore, the L section refers to the section in the direction of the central axis, which includes the central axis, and the section in the direction of the thickness T. Figure 4 Here, when machining the cross-section to expose the L-section of the Al joint line, it is sometimes deviated from the central axis of the Al joint line. In this case, when the length of the L-section in the direction perpendicular to the central axis is more than 90% of the diameter of the Al joint line, it can be regarded as a cross-section including the central axis.

[0118] In Al alloys containing a high concentration of Si of 3.0% to 20.0% by mass, Si, present in quantities exceeding its solid solubility, exists as Si particles through crystallization or precipitation. When the Si particles become coarse, cracks can form at their tips during high-temperature cycling tests, leading to a decrease in the fatigue resistance of the surface region of the Al bonding line or Al bonding band. On the other hand, by controlling the average diameter of the Si phase in the L-section to a relatively small particle size of 0.8 μm to 4 μm, the thermal fatigue resistance resulting from the Si particles in the surface region can be improved.

[0119] The product satisfies the following characteristics: containing 3.0% to 20.0% by mass of Si, and when the Si concentration in the depth direction is measured by XPS from the surface, the ratio of the average Si concentration Ca in region a (5 nm to 50 nm from the surface) to the average Si concentration Cb in region b (800 nm to 1200 nm from the surface) is 0.03 to 0.5. Furthermore, the average diameter of the Si phase in the L-section is 0.8 μm to 4 μm. Therefore, better temperature cycling reliability can be achieved in high-temperature temperature cycling tests. By combining the slope of the Si concentration in regions from the surface to a certain depth with a small-particle-size Si phase, a synergistic effect is obtained, related to the control of the interface and the reduction of thermal strain. This further improves the temperature cycling reliability in high-temperature temperature cycling tests. Furthermore, because the linear thermal expansion coefficient of the Si phase is lower than that of Al, the Si phase present inside the interior has the following effect compared to the surface region: it reduces the linear thermal expansion coefficient of the Al bonding line or Al bonding band as a whole, thereby improving temperature cycling reliability.

[0120] From the viewpoint of achieving better temperature cycling reliability in high-temperature temperature cycling tests, the average diameter of the Si phase in the L-section of the Al bonding line or Al bonding strip of the present invention is more preferably 3.8 μm or less or 3.5 μm or less, further preferably 3.4 μm or less, 3.2 μm or less or 3 μm or less, and regarding the lower limit thereof, more preferably 1 μm or more, further preferably 1.1 μm or more, and even more preferably 1.2 μm or more or 1.5 μm or more.

[0121] A method for determining the average diameter of the Si phase in the L-section of an Al junction line or Al junction band is described. The average diameter of the Si phase in the L-section can be determined using a SEM-EDS-EBSD apparatus. Specifically, a method can be used that combines information on Al and Si concentrations obtained by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) with information on crystal orientation obtained by electron backscatter diffraction (EBSD). More specifically, in the measurement area with the L-section of the Al junction line or Al junction band as the inspection surface, the concentration determination of Al and Si using EDS and the crystal orientation analysis using EBSD are performed simultaneously. Then, using the analysis software attached to the apparatus, the Al and Si phases are separated and extracted from the EDS measurement results. Specifically, the chemical-assisted scanning (Chi Scan) function, which is a feature of the analysis software OIM DataCollection or OIM Anaysis (both manufactured by TSLSolution) attached to the FE-SEM (Field Emission-Scanning Electron Microscope) device, is preferably utilized. Then, for the region identified as the Si phase, the crystal orientation can be analyzed using the analysis software attached to the device. When the orientation difference between the measurement points is 15° or more, it is determined to be a grain boundary and the equivalent circle diameter is calculated. The average value of the equivalent circle diameter of each Si phase is defined as the average diameter of the Si phase. In the process of calculating the average diameter of the Si phase, regions where the crystal orientation cannot be measured, or regions where the orientation analysis reliability is low even if it can be measured, are excluded from the calculation. Therefore, in one embodiment, the average diameter of the Si phase in the L section of the Al bonding line or Al bonding band of the present invention is calculated by the following steps (1) to (3).

[0122] (1) Using the L-section of the Al bonding line or Al bonding band as the inspection surface, the concentration determination of Al and Si using EDS and the crystal orientation determination using EBSD are carried out simultaneously.

[0123] (2) Using chemical-assisted scanning, Al and Si are separated and extracted. Specifically, based on the EDS measurement results of Si, a tolerance equivalent to the threshold of Si is set, thereby enabling the separation and identification of Al and Si. Using the crystal information of Al and Si in the material file, the crystal orientation can be analyzed.

[0124] (3) For regions identified as Si phase, the crystal orientation is analyzed. When the orientation difference between measurement points is greater than 15°, it is determined to be a grain boundary, and the equivalent circle diameter of each grain is calculated. Then, the equivalent circle diameter of each grain is averaged to calculate the average diameter of the Si phase. Here, the average calculation is performed using the area average (area-weighted average) that can be selected in the software attached to the device. By using the average value obtained by area average, it is possible to accurately determine whether the conditions related to the average diameter of the Si phase, which are suitable for achieving better temperature cycling reliability in high-temperature temperature cycling tests, are met. In the calculation of area average, it is calculated by multiplying the ratio of the area of ​​each particle to the area of ​​all particles by the average value of the area of ​​each particle. The software will automatically perform the calculation.

[0125] In this invention, when calculating the average diameter of the Si phase in the L-section, only Si phases with a diameter (equivalent circle diameter) of 0.5 μm or more are considered. Therefore, it is possible to determine with high precision whether the requirement related to the average diameter of the Si phase in the L-section is met, which is suitable for achieving better temperature cycling reliability in high-temperature temperature cycling tests.

[0126] In step (2) above, the tolerance (%) can be selected within the range of 20% to 40%, and in the standard analysis of the L-section of Al bonding lines or Al bonding bands, it is preferable to compare it at about 30%. Further explanation is given regarding the step of adjusting this tolerance. Preferably, the tolerance value is selected or confirmed such that the shape and size of the Si phase extracted and identified by the chemical-assisted scanning function are equivalent to the shape and size of the Si phase identified from the EDS diagram showing the Si elemental concentration in a two-dimensional EDS analysis.

[0127] In this invention, the average diameter of the Si phase in the L-section is set as the average (arithmetic mean) of the values ​​obtained from at least three measurements. Preferably, when selecting the measurement area, from the viewpoint of ensuring the objectivity of the measurement data, samples for measurement are taken from the Al bonding line or Al bonding band of the object being measured at intervals of 50 cm or more relative to the central axis direction of the Al bonding line or Al bonding band, and then used for measurement. Furthermore, in this invention, regarding the measurement area in the L-section based on the EBSD method, it is preferable that the length of the Al bonding line or Al bonding band in the central axis direction is 300 μm or more and less than 800 μm, and that the entire Al bonding line or Al bonding band extends into the measurement area in a direction perpendicular to the central axis of the Al bonding line or Al bonding band. However, if the size is large and it is difficult to measure the entire area, it can be adjusted within a range of less than 600 μm.

[0128] In addition to the methods described above, there are other methods for determining the average diameter of the Si phase that include binarization processing based on the observation image of the L-section. However, in this invention, because it has many measurement functions and can determine multiple characteristics such as the average diameter of the Si phase and the orientation ratio of the crystal orientation of the Al phase (described later) in a single measurement, it is possible to perform automatic analysis. It is a widely used device and analysis technique, and the measurement is relatively easy. Therefore, as described above, it is preferable to use a method that combines the Al concentration and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD.

[0129] -Crystal orientation of the Al phase in section L-

[0130] Regarding the Al bonding line or Al bonding strip of the present invention, it is preferable that, when the crystal orientation of the Al phase in its L-section is measured, the orientation ratio of the <100> crystal orientation (hereinafter also referred to as "the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction") with an angle difference of 15° or less relative to the direction parallel to the central axis (RD direction) is 15% or more and 50% or less. When the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is within the above range, a better initial bonding strength (first bonding strength) of the first bonding portion can be achieved. This is believed to be because, when ultrasonic vibration is applied in the RD direction and the Al bonding line or Al bonding strip deforms, the <100> crystal orientation with lower deformation resistance is oriented in the RD direction, thereby promoting the deformation of the bonding interface and metal bonding.

[0131] That is, when the Si concentration in the depth direction is measured by XPS from the surface to the content of 3.0% to 20.0% by mass of Si, the ratio of the average Si concentration Ca in region a with a depth of 5 nm to 50 nm from the surface to the average Si concentration Cb in region b with a depth of 800 nm to 1200 nm from the surface, Ca / Cb, is in the range of 0.03 to 0.5. In addition, the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L section is in the range of 15% to 50%, thereby achieving a better first bonding strength. The slope of the Si concentration in the region from the surface to a certain depth, which controls the bonding interface, and the orientation of the <100> crystal orientation of the Al phase in the RD direction, are synergistically obtained, thereby further improving the first bonding strength. As a result, it also helps to improve the reliability of temperature cycling in high-temperature temperature cycling tests.

[0132] From the viewpoint of achieving better first bond strength, regarding the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction in the L section of the Al bond line or Al bond band of the present invention, it is more preferably 20% or more, further preferably 22%, 24%, 26%, or 28% or more, and even more preferably 30% or 35% or more. Regarding the upper limit of the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction, from the viewpoint of achieving better first bond strength, it is more preferably 48% or less or 45% or less, further preferably 42% or less, and even more preferably 40% or less.

[0133] A method for determining the orientation ratio of the Al phase crystal orientation in the L-section of an Al junction line or Al junction band is described. The orientation ratio of the Al phase crystal orientation in the L-section is the same as that for determining the average diameter of the Si phase described above, and can be measured using a SEM-EDS-EBSD apparatus. Specifically, the following method can be used: combining the Al concentration and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD. More detailed steps can be described in the same way as those previously described in relation to the determination of the average diameter of the Si phase; that is, for the region identified as the Al phase, the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction can be calculated using the analysis software attached to the apparatus. When calculating the orientation ratio, within the measurement region, a partial ratio is calculated using the area of ​​crystal orientations that can only be identified based on a certain reliability as the denominator. Regarding the Al phase crystal orientation, the area ratio of the <100> crystal orientation in the RD direction is taken as the orientation ratio of the <100> crystal orientation in the RD direction. Therefore, in one embodiment, the orientation ratio of the crystal orientation of the Al phase in the L section of the Al bonding line or Al bonding band of the present invention is calculated by the following steps (1) to (3).

[0134] (1) In the measurement area where the L section of the Al bonding line or Al bonding band is used as the inspection surface, the concentration measurement of Al and Si using EDS and the crystal orientation measurement using EBSD are performed simultaneously.

[0135] (2) Using chemical-assisted scanning, Al and Si are separated and extracted. Specifically, based on the EDS measurement results of Si, a tolerance equivalent to the threshold of Si is set, thereby enabling the separation and identification of Al and Si. Using the crystal information of Al and Si in the material file, the crystal orientation can be analyzed.

[0136] (3) For the region identified as Al phase, analyze the crystal orientation and calculate the orientation ratio of the <100> crystal orientation of Al phase in the RD direction.

[0137] When determining the orientation ratio of the Al phase crystal orientation in the L section, the tolerance setting range, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation based on the EBSD method in the above (2) steps are the same as those for the determination of the average diameter of the Si phase.

[0138] -Addition of Sr, Na, P, and B-

[0139] Alternatively, the Al bonding line or Al bonding strip of the present invention may also contain any one or more of Sr, Na, P, and B (hereinafter also referred to as "Group 1"). The total concentration of Group 1 may also be 0 ppm by mass, preferably 1 ppm by mass or more, more preferably 3 ppm by mass or more, further preferably 5 ppm by mass or more, and especially preferably 8 ppm by mass or more or 10 ppm by mass or more. Regarding the upper limit of the total concentration of Group 1, it 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, further preferably 2,000 ppm by mass or less or 1,000 ppm by mass or less, and especially preferably 900 ppm by mass or less or 800 ppm by mass or less. Preferably, in one embodiment, the total concentration of Group 1 is 10 ppm by mass or more and 800 ppm by mass or less.

[0140] The Al bonding wire or Al bonding strip of the present invention further contains a total of 10 ppm by mass or more and 800 ppm by mass or less of any one of Sr, Na, P, and B, thereby reducing the frequency of wire breakage during the wire drawing process of the Al bonding wire or Al bonding strip. Al alloys containing a high concentration of 3.0% by mass or more and 20.0% by mass or less of Si tend to have an increased frequency of wire breakage during wire drawing. One reason is believed to be that the Si phase particles that crystallize during solidification cause stress concentration during wire drawing, inducing wire breakage. It is speculated that by adding the first element, the granular Si phase can be evenly distributed, and the growth and coarsening of the Si phase can be suppressed, thereby alleviating stress concentration during wire drawing and reducing wire breakage.

[0141] 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 strip of the present invention is more preferably 20 ppm by mass or more, further preferably 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more. Regarding the upper limit thereof, it 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, further preferably 680 ppm by mass or less, 650 ppm by mass or less, 620 ppm by mass or less, or 600 ppm by mass or less, and particularly preferably 580 ppm by mass or less, 550 ppm by mass or less, 520 ppm by mass or less, or 500 ppm by mass or less.

[0142] When the Al bonding line or Al bonding strip of the present invention contains any one or more elements from the first group, it may also contain any one element from the first group, any two elements from the first group, any three elements from the first group, or all four elements from the first group. Furthermore, when the Al bonding line or Al bonding strip of the present invention contains any one or more elements from the first group, it may also contain Sr, Na, P, or B.

[0143] When the Al bonding wire or Al bonding strip of the present invention contains Sr from the first element group, the concentration of Sr may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, or 8 ppm or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of Sr is more preferably 10 ppm or more, and even more preferably 20 ppm or more, 30 ppm or more, 40 ppm or more, or 50 ppm or more. Regarding the upper limit of the Sr concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, or 900 ppm or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of Sr is more preferably 800 ppm by mass or less, and 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.

[0144] When the Al bonding wire or Al bonding strip of the present invention contains Na from the first element group, the concentration of Na may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, or 8 ppm or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of Na is more preferably 10 ppm or more, and even more preferably 20 ppm or more, 30 ppm or more, 40 ppm or more, or 50 ppm or more. Regarding the upper limit of Na concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, or 900 ppm or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of Na is more preferably 800 ppm by mass or less, and 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.

[0145] When the Al bonding wire or Al bonding strip of the present invention contains P from the first element group, the concentration of P may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, or 8 ppm or more. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of P is more preferably 10 ppm or more, and even more preferably 20 ppm or more, 30 ppm or more, 40 ppm or more, or 50 ppm or more. Regarding the upper limit of the P concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, or 900 ppm or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of P is more preferably 800 ppm by mass or less, and 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.

[0146] When the Al bonding wire or Al bonding strip of the present invention contains B from the first element group, the concentration of B may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, or 8 ppm 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 or more, and even more preferably 20 ppm or more, 30 ppm or more, 40 ppm or more, or 50 ppm or more. Regarding the upper limit of the B concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, or 900 ppm or less. Furthermore, from the viewpoint of reducing the frequency of wire breakage during wire drawing, the concentration of B is more preferably 800 ppm by mass or less, and 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.

[0147] Addition of Ni, Ti, Fe, Zn, and Mg

[0148] Alternatively, the Al bonding wire or Al bonding strip of the present invention may also contain any one or more of Ni, Ti, Fe, Zn, and Mg (hereinafter also referred to as "Group 2"). The total concentration of Group 2 may be 0 ppm by mass, preferably 1 ppm or more or 3 ppm or more, more preferably 5 ppm or more or 8 ppm or more, further preferably 10 ppm or more or 30 ppm or more, and particularly preferably 50 ppm or more, 80 ppm or more, or 100 ppm or more. Regarding the upper limit of the total concentration of Group 2, it is preferably 10,000 ppm or less by mass, more preferably 8,000 ppm or less by mass, further preferably 5,000 ppm or less by mass, and particularly preferably 3,000 ppm or less by mass or 2,000 ppm or less by mass. Preferably, in one embodiment, the total concentration of Group 2 is 100 ppm or more and 2,000 ppm or less by mass.

[0149] The Al bonding wires or Al bonding bands of the present invention further contain a total of 100 ppm by mass or more and 2000 ppm by mass or less of any one of Ni, Ti, Fe, Zn, and Mg, thereby suppressing damage and scraping on the surface of the Al bonding wires or Al bonding bands and forming a smooth surface. Regarding Al alloys containing a high concentration of 3.0% by mass or more and 20.0% by mass or less of Si, surface hardening or shedding of the Si phase and Al oxide present on the surface can occur, resulting in damage and scraping on the surface during wire drawing, leading to Al bonding wires or Al bonding bands with uneven surfaces. It is anticipated that the addition of the second element group will improve the stabilization of Al oxides on the surface of the Al bonding wires or Al bonding bands, refine the Al grain structure, and harden the surface, thereby reducing damage and scraping during wire drawing. It is believed that by setting a predetermined slope for the Si concentration in a region from the surface to a certain depth, and by adding a second element group, damage and scraping of the Al bonding line or Al bonding band surface can be suppressed, thereby improving the effect of forming a smooth surface.

[0150] From the viewpoint of suppressing surface damage and scratching, and forming Al bonding lines or Al bonding bands with smooth surfaces, the total concentration of the second element group in the Al bonding lines or Al bonding bands of the present invention is more preferably 150 ppm by mass or more, further preferably 200 ppm by mass or more, 250 ppm by mass or more, or 300 ppm by mass or more. Regarding its upper limit, it is preferably 1800 ppm by mass or less, more preferably 1600 ppm by mass or less, 1500 ppm by mass or less, or 1200 ppm by mass or less, further preferably 1000 ppm by mass or less, 900 ppm by mass or less, or 800 ppm by mass or less, and particularly preferably 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0151] When the Al bonding wire or Al bonding strip of the present invention contains any one or more elements from the second group, it may also contain any one element from the second group, any two elements from the second group, any three elements from the second group, any four elements from the second group, or all five elements from the second group. Furthermore, when the Al bonding wire or Al bonding strip of the present invention contains any one or more elements from the second group, it may also contain Ni, Ti, Fe, Zn, or Mg.

[0152] When the Al bonding line or Al bonding band of the present invention contains Ni from the second element group, the concentration of Ni may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, 8 ppm or more, 10 ppm or more, 30 ppm or more, 50 ppm or more, or 80 ppm or more. Furthermore, from the viewpoint of suppressing surface damage and scratching, and forming an Al bonding line or Al bonding band with a smooth surface, the concentration of Ni is more preferably 100 ppm or more, and even more preferably 150 ppm or more, 200 ppm or more, 250 ppm or more, or 300 ppm by mass. Regarding the upper limit of Mn concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, or 3,000 ppm or less. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming Al bonding lines or Al bonding bands with smooth surfaces, the Ni concentration is more preferably 2000 ppm by mass or less, and even more preferably 1800 ppm by mass or less, 1600 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0153] When the Al bonding line or Al bonding band of the present invention contains Ti from the second element group, the concentration of Ti may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, 8 ppm or more, 10 ppm or more, 30 ppm or more, 50 ppm or more, or 80 ppm or more. Furthermore, from the viewpoint of suppressing surface damage and scratching, and forming an Al bonding line or Al bonding band with a smooth surface, the concentration of Ti is more preferably 100 ppm or more, and even more preferably 150 ppm or more, 200 ppm or more, 250 ppm or more, or 300 ppm by mass. Regarding the upper limit of the Ti concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, or 3,000 ppm or less. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming Al bonding lines or Al bonding bands with smooth surfaces, the concentration of Ti is more preferably 2000 ppm by mass or less, and even more preferably 1800 ppm by mass or less, 1600 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0154] When the Al bonding line or Al bonding band of the present invention contains Fe from the second element group, the concentration of Fe may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, 8 ppm or more, 10 ppm or more, 30 ppm or more, 50 ppm or more, or 80 ppm or more. Furthermore, from the viewpoint of suppressing surface damage and scratching, and forming an Al bonding line or Al bonding band with a smooth surface, the concentration of Fe is more preferably 100 ppm or more, and even more preferably 150 ppm or more, 200 ppm or more, 250 ppm or more, or 300 ppm by mass. Regarding the upper limit of the Fe concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, or 3,000 ppm or less. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming Al bonding lines or Al bonding bands with smooth surfaces, the Fe concentration is more preferably 2000 ppm by mass or less, and even more preferably 1800 ppm by mass or less, 1600 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0155] When the Al bonding line or Al bonding band of the present invention contains Zn from the second element group, the concentration of Zn may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, 8 ppm or more, 10 ppm or more, 30 ppm or more, 50 ppm or more, or 80 ppm or more. Furthermore, from the viewpoint of suppressing surface damage and scratching, and forming an Al bonding line or Al bonding band with a smooth surface, the concentration of Zn is more preferably 100 ppm or more, and even more preferably 150 ppm or more, 200 ppm or more, 250 ppm or more, or 300 ppm by mass. Regarding the upper limit of the Zn concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, or 3,000 ppm or less. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming Al bonding lines or Al bonding bands with smooth surfaces, the concentration of Zn is more preferably 2000 ppm by mass or less, and even more preferably 1800 ppm by mass or less, 1600 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0156] When the Al bonding line or Al bonding band of the present invention contains Mg from the second element group, the concentration of Mg may be 0 ppm by mass, but preferably it is 1 ppm or more, 3 ppm or more, 5 ppm or more, 8 ppm or more, 10 ppm or more, 30 ppm or more, 50 ppm or more, or 80 ppm or more. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming an Al bonding line or Al bonding band with a smooth surface, the concentration of Mg is more preferably 100 ppm or more, and even more preferably 150 ppm or more, 200 ppm or more, 250 ppm or more, or 300 ppm by mass. Regarding the upper limit of the Mg concentration, it is preferably 10,000 ppm or less, 8,000 ppm or less, 5,000 ppm or less, or 3,000 ppm or less. Furthermore, from the viewpoint of suppressing surface damage and scraping, and forming Al bonding lines or Al bonding bands with smooth surfaces, the concentration of Mg is more preferably 2000 ppm by mass or less, and even more preferably 1800 ppm by mass or less, 1600 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0157] As the aluminum raw material for manufacturing the Al bonding wire or Al bonding strip of the present invention, Al with a purity of 4N (Al: 99.99% by mass or more) is preferably used, and even more preferably, Al with a purity of 5N (Al: 99.999% by mass or more) or more with fewer impurities is used. Alternatively, in one embodiment, Al with a purity of 3N (Al: 99.9% by mass or more) may be used.

[0158] Alternatively, without hindering the effects of the present invention, the Al bonding line or Al bonding strip of the present invention may also 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" refers to elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn, and Mg. The total concentration of other elements in the Al bonding line or Al bonding strip is not particularly limited without hindering the effects of the present invention. The total concentration of the other elements may also be, for example, less than 0.5% by mass, less than 0.4% by mass, less than 0.3% by mass, less than 0.2% by mass, less than 0.15% by mass, less than 0.1% by mass, less than 0.08% by mass, less than 0.06% by mass, less than 0.05% by mass, less than 0.04% by mass, less than 0.03% by mass, less than 0.025% by mass, less than 0.02% by mass, less than 0.018% by mass, less than 0.016% by mass, less than 0.015% by mass, less than 0.014% by mass, less than 0.012% by mass, or less than 0.01% by mass. The lower limit of the total concentration of the other elements is not specifically limited and may also be 0% by mass.

[0159] In one embodiment, the remaining portion of the Al bonding line or Al bonding strip of the present invention is composed of Al and other elements. Therefore, in a preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, and other elements. In another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more elements from the first element group, and other elements. In yet another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more elements from the second element group, and other elements. In yet another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more elements from the first element group, any one or more elements from the second element group, and other elements.

[0160] In one embodiment, the remaining portion of the Al bonding line or Al bonding strip of the present invention is composed of Al and unavoidable impurities. Therefore, in a preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, and unavoidable impurities. In another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more of the first element group, and unavoidable impurities. In yet another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more of the second element group, and unavoidable impurities. In yet another preferred embodiment, the Al bonding line or Al bonding strip of the present invention is composed of Al, Si, any one or more of the first element group, any one or more of the second element group, and unavoidable impurities.

[0161] In a preferred embodiment, the Al bonding line or Al bonding strip of the present invention does not have a coating with a metal other than Al as the main component on its outer periphery. Here, "coating with a metal other than Al as the main component" means a coating with a content of metal other than Al of 50% by mass or more.

[0162] The Al bonding wire or Al bonding strip of the present invention can be either an Al bonding wire or an Al bonding strip. When the present invention is an Al bonding wire, its wire diameter is not particularly limited, and can 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 this wire diameter is not particularly limited, and can 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 can be in the range of 100 to 600 μm, preferably in the range of 200 to 400 μm. When the present invention is an Al bonding strip, the dimensions (width W × thickness T) of its rectangular or substantially rectangular cross-section are not particularly limited; for example, W can be 100 to 3000 μm, and T can be 50 to 600 μm.

[0163] The Al bonding wires or Al bonding strips of the present invention provide excellent temperature cycling reliability even in high-temperature temperature cycling tests. Therefore, the Al bonding wires or Al bonding strips of the present invention are preferably used as Al bonding wires or Al bonding strips for semiconductor devices. The Al bonding wires or Al bonding strips of the present invention are particularly preferably used as Al bonding wires or Al bonding strips for power semiconductor devices, and are even more preferably used as Al bonding wires or Al bonding strips for next-generation power semiconductor devices such as SiC power semiconductor devices.

[0164] -Manufacturing method of Al bonding wire or Al bonding tape-

[0165] An example of a method for manufacturing the Al bonding wire or Al bonding strip of the present invention will be described. Hereinafter, an example of manufacturing the Al bonding wire will be described.

[0166] The Al and alloying elements used as raw materials are preferably of high purity. Regarding Al, it is preferred that the purity is 99.5% by mass or more, with the remainder consisting of unavoidable impurities; more preferably, the purity is 99.9% by mass or more, with the remainder consisting of unavoidable impurities; and even more preferably, the purity is 99.99% by mass or more, with the remainder consisting of unavoidable impurities. Regarding Si, the first element group, the second element group, and other elements used as alloying elements, it is preferred that the purity is 99.9% by mass or more, with the remainder consisting of unavoidable impurities; more preferably, the purity is 99.99% by mass or more, with the remainder consisting of unavoidable impurities. The Al alloy used for Al bonding wires can be manufactured by loading the raw materials of Al and alloying elements into a crucible made of graphite or alumina that has been processed to obtain a cylindrical ingot, and melting it in an electric furnace or a high-frequency heating furnace. Regarding the diameter of the cylindrical ingot, considering the machinability in subsequent processing steps, it is preferred to be Φ6mm or more and less than 8mm. Regarding the furnace atmosphere during melting, to prevent excessive oxidation of the constituent elements Al or Si, Group 1, Group 2, and other elements, an inert or reducing atmosphere is preferred. Regarding the maximum temperature reached by the molten metal during melting, considering ensuring the fluidity of the molten metal while facilitating control of the Si phase size during solidification, a range of 700°C or higher but less than 1050°C is preferred. Cooling methods during solidification can include water cooling, furnace cooling, and air cooling.

[0167] After a solution treatment at high temperature is performed on a cylindrical ingot obtained by melting, repeated wire drawing using a die is carried out to produce wire of the target diameter. The drawn wire can then be used as an Al-bonded wire through a final heat treatment in an electric furnace.

[0168] <Control of the slope of Si concentration>

[0169] Controlling the slope of Si concentration in a region from the surface to a certain depth is effective by controlling the wire feed speed (drawing speed), die reduction ratio, lubricity at the wire-die interface, and the atmosphere of intermediate heat treatment during the wire drawing process. Below, an example of manufacturing conditions is shown for setting a predetermined slope of Si concentration in the depth direction (i.e., for controlling the Ca / Cb ratio to be between 0.03 and 0.5) in a region from the surface to a certain depth.

[0170] -Linear feed speed-

[0171] By controlling the wire feed speed at high speed according to the wire diameter to be drawn, the deformation of the surface area is assisted, which is effective in promoting the concentration slope. As a specific example, it is preferable to set the average wire drawing speed during the drawing process to be more than 20 m / min and less than 50 m / min, in the range from 1 / 2 wire diameter to the final wire diameter, for the wire diameter at the start of the drawing process.

[0172] -Die Reduction Ratio-

[0173] Regarding the die reduction rate in wire drawing, drawing with a high reduction rate for coarse diameters and a low reduction rate for fine diameters is effective in controlling the density slope. Specifically, it is preferable to set the die reduction rate from the wire diameter at the start of drawing to half its diameter to a range of 20% or more and less than 40%, and the die reduction rate from half the wire diameter to the final wire diameter to a range of 10% or more and less than 25%. Here, when the reduction rate of each die is denoted as P1, P1 is expressed by the following formula.

[0174] P1 = {(R2)} 2 -R1 2 ) / R2 2}×100

[0175] In the formula, R2 represents the diameter of the wire before processing (mm), and R1 represents the diameter of the wire after processing (mm).

[0176] -Lubricity-

[0177] By improving the lubricity of the interface between the wire and the die during wire drawing, the deformation that promotes surface elongation along the drawing direction can be facilitated, thereby increasing the concentration slope of the surface area. Regarding the lubricant used in wire drawing, it is preferable to select a liquid containing surfactants or similar substances that reduce the coefficient of friction in an aqueous system.

[0178] -Atmosphere of intermediate heat treatment-

[0179] Adjusting the atmosphere of the intermediate heat treatment is also effective in controlling the concentration slope in the surface region. Intermediate heat treatment refers to the heat treatment performed midway through the wire drawing process from the ingot to the final wire diameter. Preferably, the intermediate heat treatment is performed in an inert gas atmosphere such as N2. This allows for control of Si oxidation in Al during wire drawing, helping to maintain a low Si concentration near the surface.

[0180] <Control of the average diameter of the Si phase>

[0181] To adjust the average diameter of the Si phase in the L-section to a range of 0.8 μm to 4 μm, the following methods are effective: adjusting the melting temperature during ingot manufacturing to a range of 800°C to 1050°C; adjusting the casting temperature to a range of 700°C to 780°C; and controlling the solution treatment temperature to a range of 450°C to 550°C, with a solution treatment time of 1 hour to 6 hours. The casting temperature refers to the temperature at which molten liquid is poured into a mold, etc., equivalent to the solidification initiation temperature. When the casting temperature is high, the Si phase crystallizing during solidification tends to become coarser and columnar, resulting in an increase in the average diameter of the Si phase. When the solution treatment temperature is high, the columnar Si phase is broken and granulated, thus tending to decrease the average diameter of the Si phase. To further reduce the average diameter of the Si phase, increasing the cooling rate during solidification is effective; for example, water cooling is also effective.

[0182] <Control of the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction>

[0183] Adjusting the intermediate heat treatment conditions is effective in adjusting the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction of the L section to a range of 15% or more and 50% or less. Setting the intermediate heat treatment temperature range to 250°C or more and less than 400°C, and the time to 1 hour or more and less than 48 hours is effective. The number of intermediate heat treatments is preferably in the range of 2 to 4 times. Preferably, at least one intermediate heat treatment is performed within the range of 4.0 to 5.5 times the final wire diameter, and at least one intermediate heat treatment is performed within the range of 2.0 to 3.5 times the final wire diameter. By performing intermediate heat treatment under these conditions, the processing strain of the Al phase is reduced, causing slight recrystallization, thereby reducing the processing structure of the Al phase in the final wire diameter. This improves the degree of recrystallization of the Al phase in subsequent heat treatments and promotes crystal orientation rotation, making it easier to adjust the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction. On the other hand, when the intermediate heat treatment temperature is set to less than 250°C or more than 400°C, there are concerns that the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction will become unstable.

[0184] For the final heat treatment conditions, adjusting the temperature range to above 200℃ and below 360℃, and the time to above 2 hours and below 24 hours, is effective. Through final heat treatment, the recovery and recrystallization of the Al phase progresses. Simultaneously, the amount of Si dissolved in the Al phase changes according to the heat treatment temperature, and the recrystallization temperature also changes. By adjusting the recrystallization progress caused by the final heat treatment, controlling the crystal orientation becomes easier.

[0185] As described above, the manufacturing of Al bonded wire as a representative example will be explained. Al bonded strip as a strip can also be manufactured using essentially the same steps. The temperature and time of the heat treatment can be used under conditions roughly the same as described above. Furthermore, when manufacturing Al bonded strip by rolling, the reduction ratio of the die can be replaced with the reduction ratio for adjustment.

[0186] [Semiconductor Devices]

[0187] Using the Al bonding wires or Al bonding strips of the present invention, electrodes on a semiconductor chip are connected to external electrodes on a lead frame or substrate, thereby enabling the manufacture of a semiconductor device. That is, the semiconductor device of the present invention includes the Al bonding wires or Al bonding strips of the present invention. As previously described, both the first bonding with the electrodes on the semiconductor chip and the second bonding with the electrodes on the lead frame or substrate utilize wedge bonding.

[0188] In one embodiment, the semiconductor device of the present invention is characterized by including an Al bonding line or Al bonding strip for making the circuit board, the semiconductor chip, and the circuit board and the semiconductor chip conductive, wherein the Al bonding line or Al bonding strip is the Al bonding line or Al bonding strip of the present invention.

[0189] In the semiconductor device of the present invention, the circuit board and the semiconductor chip are not particularly limited, and any known circuit board and semiconductor chip that can be used to construct the semiconductor device can be used. Alternatively, a lead frame may be used instead of a circuit board. For example, the semiconductor device described in Japanese Patent Application Publication No. 2020-150116 may be configured as a semiconductor device including a lead frame and a semiconductor chip mounted on the lead frame.

[0190] Examples of semiconductor devices include those supplied to electrical products (e.g., computers, mobile phones, digital cameras, televisions, air conditioners, solar power systems, etc.) and vehicles (e.g., motorcycles, automobiles, trams, ships, and aircraft, etc.), among which power semiconductor devices (power semiconductor devices) are preferred.

[0191] Example

[0192] Hereinafter, embodiments of the present invention will be shown and specifically described. However, the present invention is not limited to the embodiments shown below.

[0193] [sample]

[0194] The sample preparation method is explained. Regarding Al as the raw material, a raw material with a purity of 4N (99.99% by mass or higher) is used, with the remainder consisting of unavoidable impurities. Regarding Si, Group 1 elements (Sr, Na, P, B), Group 2 elements (Ni, Ti, Fe, Zn, Mg), and other elements used as alloying elements, alloying elements with a purity of 99.99% by mass or higher are used, with the remainder consisting of unavoidable impurities. Al alloys for Al bonding lines or Al bonding bands are manufactured by: loading Al raw materials and alloying element raw materials into an alumina crucible and melting them in a high-frequency heating furnace. The furnace atmosphere during melting is set to an Ar atmosphere, the maximum molten liquid temperature during melting is set to 700°C or higher and less than 1050°C, and the casting temperature is set to a range of 700°C or higher and less than 780°C. The cooling method during solidification is set to air cooling in the atmosphere or water cooling in water.

[0195] A cylindrical ingot with a diameter of 6 mm was obtained through melting. After solution treatment and homogenization, the ingot was drawn using a die and subjected to intermediate heat treatment to produce an Al bonding wire with a diameter of 300 μm. Furthermore, using this 300 μm Al bonding wire as the starting material, an Al bonding strip with a thickness of 100 μm and a width of 600 μm was manufactured through a two-stage rolling process. The solution treatment temperature range was set to be above 450°C and below 550°C, and the time was set to be above 1 hour and below 6 hours. After the solution treatment, homogenization was continuously performed during cooling. The cooling method after homogenization was air cooling in the atmosphere.

[0196] The intermediate heat treatment was performed 2 to 4 times. At least one intermediate heat treatment was performed within the range of 4.0 to 5.5 times the final wire diameter, and at least one intermediate heat treatment was performed within the range of 2.0 to 3.5 times the final wire diameter. The intermediate heat treatment was performed at temperatures above 250°C and below 400°C, and for times above 1 hour and below 48 hours. Furthermore, the intermediate heat treatment was performed in an N2 gas atmosphere.

[0197] During the wire drawing process, a commercially available lubricant (containing a surfactant that reduces the coefficient of friction in a water-based system) was used. Regarding the reduction rate of the wire surface area for each die during wire drawing, the reduction rate was set to be 20% or more and less than 40% from the start of wire drawing up to 3mm of wire diameter, and 10% or more and less than 25% from 3mm of wire diameter up to the final wire diameter. Furthermore, the wire feed speed during wire drawing was set to an average of 20m / min or more and less than 50m / min within the range of 3mm of wire diameter to the final wire diameter.

[0198] Set the final heat treatment temperature range to above 200℃ and below 360℃, and the time to above 2 hours and below 24 hours.

[0199] <Method for determining Si concentration based on X-ray photoelectron spectroscopy (XPS)>

[0200] (1) Preparation of test samples

[0201] The Al bonding line or Al bonding band specimen to be measured is placed on the specimen stage. At this time, the position is adjusted on the XPS device's operating screen so that the length direction of the Al bonding line or Al bonding band specimen is transverse. If the specimen is an Al bonding band (with a rectangular cross-sectional shape having a width W of 600 μm and a thickness T of 100 μm), it is positioned so that the direction of the width W is parallel to the surface of the specimen stage, and the direction of the thickness T is perpendicular to the surface of the specimen stage.

[0202] (2) XPS-based measurement

[0203] In XPS-based measurements, the measurement area is selected while observing the SXI (Scanning X-ray Image) image of the device, ensuring that the area near the apex of the Al bond line or Al bond band sample is included in the measurement region. Then, under the following conditions, the spectra of Si2p and Al2p are detected by XPS in the depth direction from the surface of the Al bond line sample. The peak positions of the Si2p and Al2p spectra are detected at energies of approximately 98.5–99.5 eV and 71.5–73.0 eV, respectively.

[0204] • Measuring apparatus: ULVAC-PHI Versa Probe3

[0205] • Ultimate vacuum level: Approximately 1×10 -8 Torr

[0206] • X-ray source: Monochromatic Al (1486.6 eV)

[0207] • Measurement area: 100μm (sample length direction) × 20μm (sample circumference direction) quadrilateral

[0208] • Photoelectron extraction angle: 45 degrees

[0209] • Detection depth: several nm

[0210] •Ar sputtering

[0211] Accelerating voltage; 2kV

[0212] Sputtering area; 2×2mm square

[0213] Sputtering rate: 9.2 nm / min (SiO2 conversion)

[0214] • Analysis pitch in the depth direction: 5nm pitch (depth range of 0-50nm from the surface), 10nm pitch (depth range of 50-200nm from the surface), 20nm pitch (depth range of more than 200nm from the surface).

[0215] (3) Quantitative analysis of each element in Si and Al

[0216] Based on the detection spectra of Si2p and Al2p obtained from the surface of the sample at various depths in the depth direction, the quantification of each element of Si and Al is performed according to the following steps.

[0217] In detail, the quantification of Si is performed within the energy range (approximately 95.0–101.0 eV) of the peak energy of Si0 valence (metallic Si) containing Si2p. Adjustments were made within this quantification range for the energy values ​​at the low and high energy ends, based on factors such as the shape of the peak. The background of the quantification range was determined using the Shirley method, and the Si element was quantified using the peak area obtained by subtracting the background.

[0218] The quantitative analysis of Al was performed using the same steps as the quantitative analysis of Si, targeting the energy range (approximately 69.0–79.0 eV) of the peak energy of Al0 valence (metallic Al) containing Al2p.

[0219] (4) Calculation of Si concentration

[0220] Using the quantitative values ​​of Si and Al at various depths along the depth direction from the sample surface, and the relative sensitivity coefficients of each element set in the XPS device, the Si concentration was calculated when the total amount of metallic Si and metallic Al at various depths along the depth direction from the sample surface was set to 100 atomic%. Then, the arithmetic mean of the Si concentration in region a with a depth of 5 nm to 50 nm from the surface was denoted as the average concentration Ca, the arithmetic mean of the Si concentration in region b with a depth of 800 nm to 1200 nm from the surface was denoted as the average concentration Cb, and the arithmetic mean of the Si concentration in region f with a depth of 5 nm to 30 nm from the surface was denoted as the average concentration Cf.

[0221] For the determination of Si concentration, two samples were randomly selected from a plurality of samples obtained from the Al bonding line or Al bonding band of the test object at intervals of 50 cm or more relative to the central axis of the line or band. Then, the average concentration Ca, average concentration Cb, and average concentration Cf were set as the average (arithmetic mean) of the values ​​obtained for the two samples through the steps (1) to (4) above.

[0222] <Methods for Determining Elemental Content>

[0223] Concentration analysis of elements contained in Al junction lines or Al junction bands was performed using either ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) (Hitachi High-Tech Science Co., Ltd. "PS3520UVDDII") or ICP-MS (Inductively Coupled Plasma-Mass Spectrometer) (Agilent Technologies Co., Ltd. "Agilent 7700x ICP-MS"). The concentrations (mass ppm) of each element within the Al junction lines or Al junction bands as a whole were determined through these measurements.

[0224] <Method for determining the orientation ratio of Al phase crystals>

[0225] The crystal orientation of the Al phase was determined by using the L-section (including the section along the central axis direction) of the Al junction line or Al junction zone as the inspection surface.

[0226] For the measurements, an FE-SEM (Hitachi High-Tech SU-70) was used. For the analytical software, APEX (for data collection), OIM Data Collection (for chemical-assisted scanning), and OIM Anaysis (for data analysis) from TSL Solutions were used. Three measurement areas were randomly selected at intervals of 50 cm or more relative to the central axis of the Al junction line or Al junction band, and measurements were performed on these three areas. The measurement area was determined as follows: it was 300 μm or more but less than 800 μm in the direction of the central axis of the Al junction line or Al junction band, and the Al junction line or Al junction band completely entered the measurement area in a direction perpendicular to this central axis. Furthermore, for the main conditions of EDS and EBSD measurements, the accelerating voltage was set to 15 kV, the measurement magnification was set to 350x, the scan speed was set to 30–120 points / second, and the measurement interval was set to the range of 0.1–0.3 μm. While a faster scan speed could shorten the measurement time, there were concerns about a decrease in the accuracy of EDS measurements. Preferably, an appropriate scanning speed is selected within the above range.

[0227] The orientation ratio of the Al phase crystal orientation in the L section of the Al bonding line or Al bonding band was determined using a SEM-EDS-EBSD apparatus, and a method was used to combine the Al concentration and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD. More specifically, the determination was performed according to the following steps (1) to (3).

[0228] (1) In the measurement area where the L section of the Al bonding line or Al bonding band is used as the inspection surface, the concentration measurement of Al and Si using EDS and the crystal orientation measurement using EBSD are performed simultaneously.

[0229] (2) Al and Si were separated and extracted using the chemical-assisted scanning function of the EBSD analysis software. Specifically, Al and Si were separated and identified by setting a tolerance equivalent to the threshold of Si based on the EDS measurement results of Si. The crystal information of Al and Si in the material file was used for crystal orientation analysis. Here, the tolerance condition was mainly set to 30%, and adjustments were made as needed.

[0230] (3) For the region identified as Al phase, the crystal orientation was analyzed, and the orientation ratio of the <100> crystal orientation of the Al phase in the RD direction was calculated. As the crystal orientations to be investigated, at least three types of crystal orientations that are representative of Al metal, namely <111>, <110>, and <100>, were selected, and crystal orientations with higher ratios were selected as needed. Here, the partial ratio was used for the orientation ratio of the crystal orientations.

[0231] The orientation ratio of the <100> crystal orientation of the Al phase in the RD direction is set as the average value (arithmetic mean) of the values ​​obtained by the above steps (1) to (3) for the three measurement areas.

[0232] <Method for determining the average diameter of the Si phase>

[0233] The determination of the average diameter of the Si phase in the L-section of the Al bonding line or Al bonding band was performed in the same manner as the determination of the crystal orientation of the Al phase, using a SEM-EDS-EBSD apparatus and employing a method that combines the Al and Si concentration information obtained by SEM-EDS with the crystal orientation information obtained by EBSD. Specifically, after performing steps (1) and (2) above, the determination was performed according to step (3) below.

[0234] (3) For the region identified as the Si phase, the crystal orientation is analyzed. When the orientation difference between the measurement points is greater than 15°, it is identified as a grain boundary, and the equivalent circle diameter of each grain is calculated. Then, the equivalent circle diameter of each grain is averaged to calculate the average diameter of the Si phase. Here, the average value obtained by area averaging (area-weighted average) is used in the averaging calculation. In addition, when calculating the average diameter of the Si phase in section L, only the Si phase with a diameter (equivalent circle diameter) of 0.5 μm or more is considered.

[0235] The average diameter of the Si phase is set as the average value (arithmetic mean) of the values ​​obtained by the above steps (1) to (3) for the three measurement areas.

[0236] [Evaluation methods for Al bonding lines or Al bonding bands]

[0237] The evaluation method for Al bonding wires is described. The wire diameter of the Al bonding wires used for evaluation is set to Φ300μm. The semiconductor chip is made of Si. For the electrodes on the semiconductor chip, electrodes with an Al-0.5% Cu alloy film with a thickness of 4μm are used. For the substrate, a substrate with a Ni film of 5μm is used. For bonding the Al bonding wires, a commercially available wire bonding machine (manufactured by Ultrasonic Industries Co., Ltd.) is used, and both the first bonding (bonding to the aforementioned electrodes on the semiconductor chip) and the second bonding (bonding to the aforementioned substrate) are wedge bondings. For bonding the Al bonding strips, a Hessian fully automatic bonding machine "BJ955" equipped with a bonding head is used.

[0238] <Evaluation Methods for High-Temperature Cycling Reliability>

[0239] For high-temperature temperature cycling (HTCT), a commercially available thermal shock testing apparatus was used. In HTCT, the sample chamber moved between a low-temperature bath and a high-temperature bath, repeatedly heating and cooling. The temperature of the low-temperature bath was set to -40°C, and the temperature of the high-temperature bath was set to 185°C. The test began when the sample chamber was in the high-temperature bath, and one cycle was defined as the time the chamber moved to the low-temperature bath and returned to the high-temperature bath. The time the sample chamber spent in the low-temperature bath and the high-temperature bath was set to 20 minutes each. The sample for HTCT was configured with a semiconductor chip mounted on a substrate, and the electrodes on the semiconductor chip were connected to the electrodes on the substrate using Al bonding wires or Al bonding strips. After 1000 cycles, the sample was removed and a shear test was performed on the first joint. The shear strength of the first joint, used to evaluate temperature cycling reliability, was the average of the shear strengths at five randomly selected locations. The ratio of the shear strength F2 after the temperature cycling test to the shear strength F1 before the temperature cycling test (F2 / F1) was used for evaluation. When the strength ratio is less than 50%, it is judged as having a problem in practical application and recorded as "0". When the strength ratio is above 50% but less than 70%, it is judged as needing improvement and recorded as "1". When the strength ratio is above 70% but less than 75%, it is judged as excellent and recorded as "2". When the strength ratio is above 75%, it is judged as exceptionally excellent and recorded as "3". "0" and "1" are unqualified, and "2" and "3" are qualified. The evaluation results are recorded in the "High-Temperature Temperature Cycling Reliability" column of the table.

[0240] <Evaluation of High-Temperature Cycling Reliability (After 1300 Cycles)>

[0241] In the aforementioned high-temperature TCT, samples were taken after 1300 cycles of testing, and a shear test was performed on the first joint. The average shear strength of five randomly selected locations at the first joint was calculated for the evaluation of temperature cycling reliability. The ratio (F2 / F1) of the shear strength value F2 after the high-temperature TCT (1300 cycles) to the shear strength value F1 before the high-temperature TCT was used for evaluation. When the ratio was less than 50%, it was considered to have a practical problem and recorded as "0"; when the ratio was 50% or more but less than 60%, it was considered to have no practical problem and recorded as "1"; when the ratio was 60% or more but less than 70%, it was considered excellent and recorded as "2"; and when the ratio was 70% or more, it was considered exceptionally excellent and recorded as "3". "0" indicates failure, and "1", "2", and "3" indicate acceptance. The evaluation results are recorded in the "High-Temperature Cycling Reliability (After 1300 Cycles)" column of the table.

[0242] <Evaluation Method for First Bond Strength>

[0243] The evaluation method for the first bond strength is described. The first bond strength was evaluated using a shear strength test. Ten first bonds were performed under bonding conditions suitable for reliability testing, and the shear strength of the first bond was measured. Under these bonding conditions, the ultrasonic output was set slightly high to ensure the bonding area. For the shear strength measurement, a commercially available micro-shear strength testing machine (Nordson 4000-PLUS) was used. The shear speed was set to 200 μm / s, and the height of the shearing tool was set to 10 μm from the electrode surface. The shear strength measurement was performed by fixing the substrate with the Al bonding wire or Al bonding strip bonded using a clamp. When the average shear strength of the 10 first joints is above 1500 gf, it is judged as excellent and rated as "3"; when it is above 1300 gf but below 1500 gf, it is judged as having no practical problems and rated as "2"; when it is above 1000 gf but below 1300 gf, it is judged as needing improvement and rated as "1"; when it is below 1000 gf, it is judged as having practical problems and rated as "0". The evaluation results are recorded in the "First Joint Strength" column of the table.

[0244] <Evaluation Methods for Wire Breakage During Processing>

[0245] The evaluation method for wire breakage during processing is explained. Wire drawing was performed from wire diameters of 6mmφ to 0.3mmφ, and the number of breakages was recorded. The feed rate, reduction ratio, and other processing conditions for wire drawing were selected based on the aforementioned conditions, and appropriate manufacturing conditions were adjusted and modified for each wire. The length of the Al-jointed wires drawn ranged from 100 to 200m, and the number of breakages per 100m was calculated. A breakage count of 0 was considered good and rated "3"; a breakage count of 1 was considered manageable with improvements to manufacturing conditions and rated "2"; a breakage count of 2 to 4 was considered a productivity issue and rated "1"; and a breakage count of 5 or more was considered difficult to implement and rated "0". The evaluation results are recorded in the "Wire Breakage During Processing" column of the table.

[0246] (Evaluation methods for surface damage and scraping)

[0247] The surface properties of Al bonding lines or Al bonding bands were evaluated focusing on damage and scratching. The diameter of the Al bonding lines was set to Φ300μm. For the Al bonding bands, three measurement areas were randomly selected at intervals of more than 1m relative to the central axis of the Al bonding lines, and three samples of approximately 2cm in length were collected from each of the three areas. A total of nine samples were observed. Specifically, the surface was observed using SEM at magnifications ranging from 50 to 500x. Damage exceeding 50μm in length and scratching exceeding 30μm in length were considered undesirable. The number of damaged or scratched areas was counted. A count of 0 was considered good, rated as acceptable ("3"); a count of 1 to 2 was considered practically feasible ("2"); a count of 3 to 7 was considered poor surface properties ("1"); and a count of 8 or more was considered difficult to use practically ("0"). The evaluation results are recorded in the "Surface Properties" column of the table.

[0248] The evaluation results of the embodiments and comparative examples are shown in Tables 1 to 4. Examples 1 to 40 and Comparative Examples 1 to 7 in Tables 1 to 3 are results related to Al bonding lines, and Examples B1 to B3 and Comparative Example B1 in Table 4 are results related to Al bonding bands.

[0249] Table 1

[0250]

[0251] Table 2

[0252]

[0253] Table 3

[0254]

[0255] Table 4

[0256]

[0257] Explanation of reference numerals in the attached figures

[0258] 1 Al joint line

[0259] 10. Central axis

[0260] 11 L-section

[0261] 2 Al joint zone

[0262] 20 central axis

[0263] 21 L-section

Claims

1. An Al bonding wire or Al bonding strip containing 3.0% by mass and less than 20.0% by mass of Si, When the Si concentration in atomic percent along the surface depth direction of the Al bonding line or Al bonding band was determined by X-ray photoelectron spectroscopy, the ratio of the average Si concentration Ca in region a with a depth of 5 nm to 50 nm from the surface to the average Si concentration Cb in region b with a depth of 800 nm to 1200 nm from the surface, Ca / Cb, was 0.03 to 0.

5.

2. The Al bonding line or Al bonding strip as described in claim 1, wherein, The average diameter of the Si phase in the L-section of the Al bonding line or Al bonding band, i.e., the section including the central axis in the direction of the central axis, is greater than 0.8 μm and less than 4 μm.

3. The Al bonding line or Al bonding strip as described in claim 1 or 2, wherein, The average concentration of Si element Cf in the region f, which is 5 nm or more and 30 nm or less from the surface, is 0.1 atomic% or more and 4 atomic% or less.

4. The Al bonding line or Al bonding strip as described in any one of claims 1 to 3, wherein, When the crystal orientation of the Al phase in the L section of the Al bonding line or Al bonding band, i.e., the section containing the central axis, is determined, the orientation ratio of <100> crystal orientation with an angle difference of less than 15° with respect to the direction parallel to the central axis, i.e., the RD direction, is more than 15% and less than 50%.

5. The Al bonding line or Al bonding strip as described in any one of claims 1 to 4, further comprising any one or more of Sr, Na, P, and B totaling 10 ppm by mass or more and 800 ppm by mass or less.

6. The Al bonding wire or Al bonding strip as described in any one of claims 1 to 5, further comprising any one or more of Ni, Ti, Fe, Zn, and Mg totaling 100 ppm by mass or more and 2000 ppm by mass or less.

7. The Al bonding line or Al bonding strip as described in any one of claims 1 to 6, wherein, The total concentration of elements other than Al, Si, Sr, Na, P, B, Ni, Ti, Fe, Zn and Mg in the Al bonding line or Al bonding band is less than 0.5% by mass.

8. The Al bonding line or Al bonding strip as described in any one of claims 2 to 7, wherein, The average diameter of the Si phase was measured using a SEM-EDS-EBSD instrument.

9. The Al bonding line or Al bonding strip as described in any one of claims 4 to 8, wherein, The orientation ratio of the crystal orientation is the value measured using a SEM-EDS-EBSD device.

10. The Al bonding wire or Al bonding strip as described in any one of claims 1 to 9, for use in a semiconductor device.

11. A semiconductor device comprising an Al bonding line or Al bonding strip as described in any one of claims 1 to 10.

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