Aluminum connecting material

Abstract

Provided is an aluminum connecting material that ensures excellent temperature cycle reliability and favorable first bonding strength. This aluminum connecting material contains 4.0-12.0 mass % of silicon and has a specific electric resistance Ra of 2.6 × 10 - 8 Ωm to 3.6 × 10 - 8 Ωm. When the crystal orientation of an aluminum phase in an L cross-section (a cross-section in the central axis direction, including the central axis) of the aluminum connecting material is measured, the total of the orientation ratios of the <110> crystal orientation and the <111> crystal orientation in which the angle difference is 15° or less with respect to the central axis is 20-70%, but when the total of the orientation ratios is 25% or less, the orientation ratio of the <110> crystal orientation in which the angle difference is 15° or less with respect to the central axis direction is 5% or more.

Description

Al connecting material

[0001] The present invention relates to an Al connecting material.

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

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

[0004] There are two methods for joining Al connecting materials: first joining with electrodes on a semiconductor chip, and second joining with electrodes on a lead frame or substrate, both of which use wedge joining. Wedge joining is a method in which ultrasonic vibrations and loads are applied to the Al connecting material via a metal jig (tool), destroying the surface oxide films on the Al connecting material and the electrode material to expose new surfaces and perform solid-state diffusion bonding. This joining method is characterized by connecting the connecting material in a solid state without melting it, and is a joining technique that differs from welding techniques that melt the connecting material.

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

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

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

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

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

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

[0011] As described above, next-generation power semiconductor devices are required to withstand longer periods of use than general-purpose power semiconductor devices. During operation of a power semiconductor device, the temperature of the first joint repeatedly rises and falls. As a result, because the Al connecting material has a higher linear expansion coefficient than the semiconductor chip, thermal stress occurs at the first joint due to the difference in linear expansion coefficients between the two materials, which can ultimately lead to fatigue failure of the Al connecting material. A temperature cycle test is one type of accelerated evaluation test for the life (temperature cycle reliability) of such a first joint as a result of temperature rise and fall. Al connecting materials used in next-generation power semiconductors are required to exhibit excellent temperature cycle reliability in a temperature cycle test. However, when using Al connecting materials strengthened by the addition of Si or other additives, as disclosed in Patent Documents 1 to 3, in temperature cycle tests intended for use in next-generation power semiconductor devices, cracks propagate relatively rapidly in Al alloy electrodes that are weaker than the Al connecting material, making it difficult to consistently achieve good temperature cycle reliability.

[0012] Conventional temperature cycle testing (TCT) can be easily performed using commercially available testing equipment. However, the relatively slow temperature change rate in TCT raises concerns about discrepancies with the fast temperature change rate observed during the operation of power semiconductor devices. Therefore, recently, high-speed temperature cycle testing (hereinafter also referred to as "high-speed TCT"), which accelerates the temperature change rate to more closely resemble actual operating conditions, has been investigated. While the temperature change rate in conventional TCT is, for example, approximately 10°C / min, high-speed TCT achieves a rapid temperature change of, for example, approximately 200°C / min. Regarding the reliability evaluation of Al interconnection joints, even Al interconnection materials that do not exhibit a decrease in reliability when evaluated using conventional TCT may experience a decrease in joint strength and a shortened joint life when evaluated using high-speed TCT. Therefore, there is a demand for Al interconnection materials that exhibit good joint reliability even in high-speed TCT, a more severe test that is closer to actual operating conditions, and thus provide excellent temperature cycle reliability. Hereinafter, the temperature cycle reliability in high-speed TCT may be referred to as "high-speed temperature cycle reliability."

[0013] Furthermore, if bonding defects, such as peeling of the Al connecting material from the electrode, occur during bonding, this can lead to product defects and reduced manufacturing yields, so it is necessary to obtain good bonding strength at each joint. In this regard, applying strong ultrasonic vibrations or loads to the first joint in order to obtain good bonding strength can damage the semiconductor chip. In particular, when using an Al connecting material whose strength has been increased by adding Si or the like, its hardness makes it easy to damage the semiconductor chip during the first bonding. Adjusting the ultrasonic vibrations or load to reduce such damage can sometimes result in insufficient bonding strength at the first joint (hereinafter simply referred to as "first bonding strength") due to its high deformation resistance and unstable deformation direction, making it difficult to stably secure the bonding area. These problems during the initial bonding of the first joint ultimately lead to reduced and unstable temperature cycle reliability, thereby hindering the practical use of Al connecting materials whose strength has been increased by adding Si or the like.

[0014] An object of the present invention is to provide an Al connecting material that satisfies excellent temperature cycle reliability and good first bonding strength.

[0015] As a result of intensive research into the above-mentioned problems, the inventors have found that an Al connecting material containing 4.0 mass% or more and 12.0 mass% or less of Si has a specific range of specific electrical resistivity Ra, and when the crystal orientation of the Al phase in the L cross section (a cross section in the central axis direction including the central axis) of the Al connecting material is measured, the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, is within a specific range, which can solve the above-mentioned problems.Based on this finding, the inventors have conducted further research and completed the present invention.

[0016] That is, the present invention includes the following: <1> An Al connecting material containing 4.0 mass % or more and 12.0 mass % or less of Si, wherein the specific electrical resistivity Ra is 2.6 × 10 －８ Ωm or more 3.6 x 10 －８<2> An Al connection material according to <1>, wherein, when the crystal orientation of the Al phase in the L cross section (a cross section in the central axis direction including the central axis) of the Al connection material is measured, the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, is 20% or more and 70% or less, and when the total orientation ratio is 25% or less, the orientation ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the central axis, is 5% or more. <3> The Al connecting material according to <1> or <2>, wherein, when the crystal orientation of the Si phase in the L cross section is measured, the total orientation ratio of the <111> crystal orientation and the <110> crystal orientation, which have an angular difference of 15° or less with respect to the central axis direction, is 20% or more and 70% or less. <4> The Al connecting material according to any one of <1> to <3>, wherein the average value of the ratio (c / d) of the short side length c to the long side length d of the Al phase in the L cross section is 0.2 or more and 0.7 or less. <5> The Al connecting material according to any one of <1> to <4>, further containing one or more of Sr, Na, Ca, and B in a total amount of 5 ppm to 800 ppm by mass. <6> The Al connecting material according to any one of <1> to <5>, further containing one or more of Fe, Mg, P, and Ti in a total amount of 5 ppm to 500 ppm by mass. <7> The Al connecting material according to any one of <1> to <6>, wherein the total concentration of other elements in the Al connecting material is 0.5 mass % or less.

[0017] According to the present invention, it is possible to provide an Al connecting material that satisfies excellent temperature cycle reliability and good first bonding strength.

[0018] FIG. 1 is a schematic diagram for explaining the measurement surface (inspection surface) when measuring the crystal orientation and shape (shape ratio (c / d)) of the Al phase and Si phase of an Al connecting material. The measurement surface is a cross section (L cross section) in the central axis direction including the central axis of the Al connecting material. FIG. 2 is a schematic diagram for explaining the short side length (c) and long side length (d) of the Al phase in the L cross section. FIG. 3 is a schematic diagram for explaining a hollow defect in the first joint. FIG. 4 is an example of an internal crack in an Al connecting material observed using a soft X-ray transmission device.

[0019] The present invention will be described in detail below with reference to preferred embodiments. While the description may refer to drawings, each drawing merely shows the shape, size, and arrangement of components to the extent that the invention can be understood. The present invention is not limited to the following embodiments and examples, and can be modified and implemented as desired within the scope of the claims of the present invention and their equivalents.

[0020] [Al connecting material] The Al connecting material of the present invention is an Al connecting material containing 4.0 mass % or more and 12.0 mass % or less of Si, and has a specific electrical resistivity Ra of 2.6 × 10 －８ Ωm or more 3.6 x 10 －８ When the crystal orientation of the Al phase in an L-section (a cross section in the direction of the central axis including the central axis) of the Al connecting material is measured, the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, is 20% or more and 70% or less, and when the total orientation ratio is 25% or less, the orientation ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the central axis, is 5% or more.

[0021] As mentioned above, in temperature cycle tests (TCT), when a connecting material made solely of high-purity Al is used, cracks propagate relatively rapidly within the connecting material, making it difficult to achieve good temperature cycle reliability. On the other hand, when an Al connecting material strengthened by the addition of Si or other additives is used, cracks propagate within the Al alloy electrodes, which have relatively low strength, making it difficult to achieve the temperature cycle reliability required for next-generation power semiconductor devices. That is, in high-speed temperature cycle tests (high-speed TCT), in which the temperature change rate is accelerated to approximate actual operating conditions, even Al connecting materials that do not exhibit a decrease in reliability when evaluated using conventional TCT tests may experience a decrease in bond strength and a shortened bond life. Furthermore, when an Al connecting material strengthened by the addition of Si or other additives is used, the semiconductor chip is easily damaged during the first bonding step. Adjusting the ultrasonic vibration or load to reduce such damage may result in insufficient first bonding strength.

[0022] As a result of intensive research to solve the above problems, the inventors have found that an Al connecting material containing 4.0 mass% to 12.0 mass% Si, having a specific electrical resistivity Ra within a specific range, and measuring the crystal orientation of the Al phase in an L-section, in which the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, within a specific range, exhibits good joint reliability even in high-speed TCT, a more severe test that is closer to the conditions of actual use, and can provide excellent temperature cycle reliability and improve first bond strength. Such an Al connecting material of the present invention significantly contributes to achieving the temperature cycle reliability required for next-generation power semiconductor devices and good first bond strength.

[0023] The Al connecting material of the present invention contains 4.0 mass% to 12.0 mass% Si, and is composed of an Al phase in which Si is dissolved in Al, and a Si phase formed by crystallization or precipitation of Si. Here, the Al phase may contain other additive elements in addition to Si as a solid solution. The Si phase is a general term for Si crystallized particles and Si precipitates. Si crystallized particles are formed from the melt during solidification and are coarse, measuring approximately 1 to 20 μm in size, while Si precipitates are formed from the solid state and are small, measuring approximately 0.1 to several μm in size.

[0024] In the present invention, the L-section of the Al connecting material, i.e., the cross section in the central axis direction including the central axis of the Al connecting material, is as will be explained later in the section "(Method for measuring the orientation ratio of the crystal orientations of the Al phase and the Si phase)" with reference to Figure 1.

[0025] The reason why the Al connecting material of the present invention can provide excellent temperature cycle reliability and good first bonding strength is presumed to be as follows.

[0026] When the Si concentration is in the range of 4.0% by mass or more and 12.0% by mass or less, Si crystals tend to be generated in a particulate form. As described above, these Si crystals grow relatively large, contributing to the suppression of linear expansion and the improvement of properties such as temperature cycle reliability. On the other hand, the high Si content of the Al connecting material hardens, which can lead to insufficient deformation during joining or an unstable deformation direction, resulting in a decrease in joining strength. These problems during initial joining ultimately lead to a decrease in temperature cycle reliability and instability, hindering the practical use of Al connecting materials that have been strengthened by the addition of Si, etc.

[0027] The inventors have discovered that in order to improve the initial bonding strength while suppressing damage to the semiconductor chip when ultrasonic vibration and load are applied (hereinafter also referred to simply as "during bonding"), it is effective to simultaneously control (i) the amount of Si and fine precipitates in the solid solution state within the Al phase, and (ii) the orientation of a specific crystal orientation of the Al phase.

[0028] Regarding the above (i), since the Si atoms dissolved in the Al phase act to increase the deformation resistance during joining by increasing lattice strain, pinning dislocations, etc., reducing the amount of Si in the solid solution state softens the Al connecting material and promotes its deformation. Furthermore, some of the dissolved Si precipitates during heat treatment to form fine Si precipitates, and controlling their size within the submicron range can improve uniform deformation during joining and the temperature cycle characteristics of the joint.

[0029] Here, since the solid-solution state of Si cannot be directly observed, it is difficult to accurately measure the amount of solid solution in the entire Al interconnect material. Furthermore, although fine Si precipitates can be partially observed using advanced analysis such as TEM, the observation area is limited, making it difficult to accurately grasp the amount and volume of fine Si precipitates in the Al interconnect material, including particle distribution. In this regard, the specific electrical resistivity of Al-Si alloys obtained by electrical measurement can be managed as an indicator of the amount of Si solid solution and the amount and distribution of fine precipitates in the Al phase. Furthermore, we have found that controlling this specific electrical resistivity is effective in changing the material structure of the Al interconnect material to improve its bondability. For example, reducing the specific electrical resistivity is related to a decrease in the amount of Si solid solution or an increase in the amount of fine precipitates, which contributes to the effect of reducing damage to semiconductor chips during bonding. Conversely, increasing the specific electrical resistivity is related to an increase in the amount of Si solid solution or a decrease in the amount of fine precipitates. The effect of coarsened Si crystallized particles on the specific electrical resistivity is significantly smaller than that of solute Si, and is almost negligible.

[0030] Therefore, adjusting the material structure of the Al connecting material using the specific electrical resistivity of the Al-Si alloy as an index leads to control of the solid solution state of Si and fine Si precipitates, which is effective in suppressing damage to the semiconductor chip during bonding while improving the bonding strength. While the conductivity (the reciprocal of the electrical resistance) has been adjusted in conventional connecting materials made of Al alloys, this has been done from the perspective of electrical properties to facilitate electrical conduction. The optimization of the specific electrical resistivity of the Al-Si alloy in the present invention is characterized in that it is set as an index for controlling the material structure of the solid solution and fine precipitates, rather than for the purpose of adjusting the electrical properties. When controlling the material structure, there is an appropriate range for the specific electrical resistivity. If it falls outside that range, even if the electrical properties are good, it is difficult to suppress damage to the semiconductor chip during bonding while improving the bonding strength. Furthermore, it was confirmed that there is a weak relationship between the specific electrical resistivity and the bonding properties for Al connecting materials containing 3% or less Si by mass. It has been confirmed that the ability to control the specific electrical resistivity as an indicator for improving bonding strength while suppressing damage to the semiconductor chip during bonding is uniquely applicable to the configuration of the present invention, which contains 4.0 mass % or more and 12.0 mass % or less of Si.

[0031] Regarding (ii) above, controlling the texture of the Al phase crystal grains is effective in promoting sufficient deformation during bonding. That is, when the total orientation ratio of the <110> and <111> crystal orientations of the Al phase is in the range of 20% to 70% (however, when the total orientation ratio is 25% or less, the orientation ratio of the <110> crystal orientation with an angular difference of 15° or less with respect to the central axis is 5% or more), it is believed that this promotes deformation of the entire Al connecting material and increases bonding strength. Furthermore, controlling the orientation ratio of the <110> and <111> crystal orientations is believed to enhance the effect of destroying the oxide film present at the bonding interface during bonding, exposing new surfaces, and promoting metal bonding. It is believed that the orientation of the <110> crystal orientation primarily controls deformation of the Al connecting material parallel to the ultrasonic vibration, while the orientation of the <111> crystal orientation primarily controls deformation perpendicular to the ultrasonic vibration (the width direction of the Al connecting material).

[0032] As described above, it is presumed that the Al connecting material of the present invention can provide excellent temperature cycle reliability and good first bond strength as described above, as a result of appropriately controlling the factors that contribute to improving temperature cycle reliability and first bond strength.

[0033] -Si Concentration- A Si concentration in the range of 4.0 mass% or more and 12.0 mass% or less helps reduce thermal distortion at the joint and improve temperature cycle characteristics. If the Si concentration is less than 4.0 mass%, the improvement effect is small, while if it exceeds 12.0 mass%, problems such as a decrease in initial joint strength due to hardening and damage to the semiconductor chip occur. From the viewpoint of obtaining good temperature cycle reliability even in high-speed TCT with an increased temperature change rate, which is close to actual use conditions, the Si concentration in the Al connecting material of the present invention is 4.0 mass% or more, preferably 4.5 mass% or more, more preferably 4.6 mass% or more, 4.8 mass% or more, 5.0 mass% or more, 5.2 mass% or more, 5.4 mass% or more, or 5.5 mass% or more. On the other hand, if the hardness of the Al connecting material is excessive, damage to the semiconductor chip is more likely to occur during the first joining under commonly used ultrasonic vibration and load joining conditions. From the viewpoint of obtaining good bonding strength when performing the first bonding under general bonding conditions, the Si concentration in the Al connecting material of the present invention is 12.0 mass% or less, preferably 11.5 mass% or less or 11.0 mass% or less, and more preferably 10.8 mass% or less, 10.6 mass% or less, 10.5 mass% or less, 10.4 mass% or less, 10.2 mass% or less, or 10.0 mass% or less.

[0034] For example, an ICP (Inductively Coupled Plasma) optical emission spectrometer or an ICP mass spectrometer can be used to analyze the concentration of elements contained in the Al connecting material of the present invention. If elements derived from atmospheric contaminants such as oxygen or carbon are adsorbed on the surface of the Al connecting material, it is effective to wash the surface with an acid or alkali according to the adsorbed substance before analysis.

[0035] - Specific Electrical Resistance - From the viewpoint of obtaining good temperature cycle reliability even in high-speed TCT and obtaining good first joint strength, the specific electrical resistance of the Al connecting material is 2.6 × 10 －８ Ωm or more, preferably 2.7×10－８ Ωm or more, more preferably 2.8×10 －８ The upper limit of the specific electrical resistivity is 3.6×10 Ωm or more from the viewpoint of obtaining excellent temperature cycle reliability and good first bonding strength. －８ Ωm or less, preferably 3.5×10 －８ Ωm or less, more preferably 3.4×10 －８ It is Ωm or less.

[0036] The specific electrical resistance of the Al connecting material can be measured by a DC four-terminal measurement method. For example, a DM7275 manufactured by Hioki E.E. Corporation can be used as a resistance meter to measure the electrical resistance value of a sample at room temperature with a sample length of 200 mm and a measurement current range of 0.02 to 0.1 mA. Five measurements are taken, and the electrical resistance value R of each sample is calculated as the arithmetic average. If the electrical resistance value is R, the length of the sample is L, and the cross-sectional area of ​​the sample is S, the specific electrical resistance value M of the Al connecting material can be calculated by R × (S / L).

[0037] -Crystal orientation of Al phase in L cross section- From the viewpoint of obtaining good temperature cycle reliability even in high-speed TCT and obtaining good first bond strength, when the crystal orientation of the Al phase in the L cross section of the Al connecting material is measured, the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis (hereinafter also referred to as the "total <110> + <111> ratio of the Al phase") is 20% or more, preferably 22% or more, 24% or more, 25% or more, or more than 25%, more preferably 26% or more or 28% or more, even more preferably 30% or more, and even more preferably 35% or more, 40% or more, 42% or more, 44% or more, or 45% or more. When an embodiment in which the <111> + <110> total ratio of the Al phase is low was investigated in detail, it was confirmed that the effect of improving temperature cycle reliability and first bond strength was obtained even when the total ratio was in the range of 20% or more but less than 30%. However, it has been confirmed that it is important that when the total ratio of <111> + <110> of the Al phase is 25% or less, the ratio of the <110> crystal orientation with an angular difference of 15° or less with respect to the central axis direction is 5% or more. From the viewpoint of obtaining excellent temperature cycle reliability and good first bonding strength, the upper limit of the total ratio of <110> + <111> of the Al phase is 70% or less, preferably 65% ​​or less, more preferably 60% or less, and even more preferably 58% or less, 56% or less, or 55% or less.

[0038] From the viewpoint of obtaining even better first joint strength and suppressing hollows in the first joint (a phenomenon in which a portion where the metal bond is insufficient is formed in the joint region between the Al connecting material and the electrode), when the crystal orientation of the Al phase in the L cross section of the Al connecting material is measured, the orientation ratio of the <110> crystal orientation, which has an angle difference of 15° or less with respect to the central axis direction (hereinafter also referred to as the "<110> ratio of the Al phase"), is preferably in the range of 5% to 50%. Regarding the crystal orientation of the Al phase, if the total ratio of the <110> + <111> Al phase is in the range of 20% to 70%, and the <110> ratio of the Al phase is in the range of 5% to 50%, a high effect of suppressing hollows in the first joint and improving the first joint strength can be obtained. The reason why the above effect is obtained when the <110> ratio of the Al phase is in this range is presumed to be as follows. That is, when the <110> ratio of the Al phase is within this range, it is believed that deformation of the Al connecting material in the ultrasonic vibration direction can be promoted, and thus the first bond strength can be further improved. Furthermore, since hollow holes often occur in the ultrasonic vibration direction, it is believed that promoting deformation of the Al connecting material in the ultrasonic vibration direction as described above also suppresses hollow holes. From the viewpoint of obtaining even better first bond strength and suppressing hollow holes in the first bonded portion, the <110> ratio of the Al phase is more preferably 10% or more, even more preferably 12% or more, 14% or more, or 15% or more. Furthermore, the upper limit of the <110> ratio of the Al phase is more preferably 45% or less, even more preferably 40% or less, 38% or less, 36% or less, or 35% or less.

[0039] To measure the orientation ratio of the Al phase crystal orientation in the L-section of an Al connecting material, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by electron backscatter diffraction (EBSD). Specifically, in the measurement area where the L-section of the Al connecting material is used as the inspection surface, Al and Si concentration measurements are performed using EDS, and crystal orientation analysis is performed using EBSD simultaneously. Next, the Al phase and Si phase are separated and extracted from the EDS measurement results using the analysis software provided with the FE-SEM. Specifically, it is preferable to use the Chi Scan function, which is a function of the OIM Data Collection or OIM Analysis software (both manufactured by TSL Solutions) provided with the FE-SEM. Then, for the area identified as Al phase, the orientation ratio of the <110> crystal orientation and the <111> crystal orientation of the Al phase, as well as their total, can be calculated using the analysis software provided with the instrument. To calculate the orientation ratio, a partial ratio is used, which is calculated as a population of the area of ​​only the crystal orientations that could be identified based on a certain reliability within the measurement area. The area ratios of the <110> crystal orientation and the <111> crystal orientation are defined as the orientation ratio of the <110> crystal orientation and the orientation ratio of the <111> crystal orientation, respectively. Therefore, in one embodiment, the orientation ratio of the crystal orientation of the Al phase in the L-section of the Al connection material of the present invention is calculated by the following steps (1) to (3). (1) In the measurement area where the L-section of the Al connection material is used as the inspection surface, the Al and Si concentrations are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) The Chi Scan function is used to separate and extract Al and Si. Specifically, by setting a tolerance equivalent to the Si threshold from the EDS measurement results of Si, Al and Si can be separated and identified. The crystal orientation can be analyzed using the crystal information of Al and Si from the material file. (3) The crystal orientation of the region identified as the Al phase is analyzed, and the orientation ratio of the <110> crystal orientation and the orientation ratio of the <111> crystal orientation of the Al phase are calculated.

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

[0041] In the present invention, the orientation ratios of the <110> crystal orientation and the <111> crystal orientation of the Al phase in the L-section were determined as the average values ​​of the orientation ratios obtained by measuring three or more locations. When selecting the measurement area, in order to ensure the objectivity of the measurement data, it is preferable to obtain measurement samples from the Al connection material to be measured at intervals of 50 cm or more along the central axis of the Al connection material and provide them for measurement. Furthermore, in the present invention, the measurement area for crystal orientation using the EBSD method has a length in the direction of the central axis of the Al connection material of 300 μm or more and less than 800 μm, and it is desirable that the entire Al connection material be included in the direction perpendicular to the central axis of the Al connection material. However, if the size is large and it is difficult to measure the entire Al connection material, the measurement area may be adjusted to a range of less than 600 μm.

[0042] -Crystal orientation of Si phase in L cross section-From the viewpoint of obtaining better temperature cycle reliability in high-speed TCT, when the crystal orientation of the Si phase in the L cross section of an Al connecting material is measured, the total ratio of the <111> crystal orientation and the <110> crystal orientation, which have an angular difference of 15° or less with respect to the central axis direction (hereinafter also referred to as the "total ratio of <111> + <110> of Si phase") is preferably in the range of 20% to 70%. In addition to the above-mentioned control of the specific electrical resistivity and the total ratio of <110> + <111> of Al phase, if the total ratio of <111> + <110> of Si phase is set in this range, the strength retention rate that suppresses the decrease in bonding strength can be improved, or the number of tests until a defect occurs due to a decrease in bonding strength can be extended, thereby achieving better temperature cycle reliability even in high-speed TCT. This is thought to be because the alignment of the <111> and <110> crystal orientations of the Si phase with the <110> and <111> crystal orientations of the Al phase improves the adhesion at the interface between the Si phase and the Al phase, thereby suppressing interfacial delamination even with an increased number of cycles during high-speed TCT, which has a rapid temperature change rate. The total <111> + <110> ratio of the Si phase is more preferably 25% or more, even more preferably 26% or more, 28% or more, or 30% or more. From the viewpoint of obtaining excellent temperature cycle reliability and good first bonding strength, the total <111> + <110> ratio of the Si phase is more preferably 65% ​​or less, even more preferably 60% or less, 58% or less, 56% or less, 55% or less, 54% or less, 52% or less, or 50% or less.

[0043] To measure the orientation ratio of the Si phase's crystal orientation in the L-section of an Al connecting material, a technique can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD, similar to the measurement of the orientation ratio of the Al phase's crystal orientation. The detailed procedure can be the same as that described above in relation to the measurement of the orientation ratio of the Al phase's crystal orientation. That is, for the region identified as the Si phase, the orientation ratio of the <111> crystal orientation and the <110> crystal orientation of the Si phase, as well as their total, can be calculated using the analysis software provided with the device. To calculate the orientation ratio, a partial ratio is used, calculated as a population of the area of ​​only the crystal orientations that can be identified with a certain level of reliability within the measurement area. Therefore, in one embodiment, the orientation ratio of the Si phase's crystal orientation in the L-section of an Al connecting material of the present invention is calculated using the following procedures (1) to (3). (1) In the measurement area where the L-section of the Al connecting material is used as the inspection surface, the Al and Si concentrations are measured using EDS and the crystal orientation is analyzed using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are analyzed separately. Specifically, by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results, Al and Si can be separated and identified. The crystal orientation is analyzed using the Al and Si crystal information from the material file. (3) For the area identified as the Si phase, the crystal orientation is analyzed and the orientation ratio of the <111> crystal orientation and the orientation ratio of the <110> crystal orientation of the Si phase are calculated.

[0044] In the present invention, the orientation ratio of the <111> crystal orientation and the orientation ratio of the <110> crystal orientation of the Si phase in the L cross section were the arithmetic mean values ​​of the orientation ratios obtained by measuring at least three locations. The tolerance setting range, the method for obtaining the measurement sample, and the measurement area of ​​the crystal orientation by the EBSD method in the above procedure (2) are as described above for the measurement of the orientation ratio of the crystal orientation of the Al phase.

[0045] - Shape of the Al phase in the L-section - When joining Al connection materials by applying ultrasonic vibration and load, it is important to control the joint shape. The joint shape of an Al connection material can be evaluated by the indentation width (joint width) at the fractured portion in the direction perpendicular to the central axis of the Al connection material when a shear strength test of the joint is conducted. Reducing and stabilizing the variation in this joint width will ultimately contribute to improving temperature cycle reliability. In this regard, there is concern that Al connection materials strengthened by adding Si or the like will have greater variation in joint width compared to conventional Al connection materials due to their high deformation resistance and instability in the deformation direction.

[0046] The inventors, in the course of studying an Al connection material containing 4.0 mass% to 12.0 mass% Si, having a specific range of specific electrical resistivity, and having a specific range of the total ratio of the <110> + <111> Al phase in its L-section, discovered that the shape of the Al phase in the L-section affects the variation in the joint width during joining of the Al connection material. Specifically, they discovered that the variation in the joint width during joining is reduced when the average value of the ratio (c / d) of the short side length c to the long side length d of the Al phase in the L-section is in the range of 0.2 to 0.7. The value of this ratio (c / d) is an index of flatness. Further explanation will be given with reference to FIG. 2 . FIG. 2 is a schematic diagram showing the Al phase in the L-section of an Al connection material, with the central axis of the Al connection material corresponding to the horizontal direction (left-right direction) in FIG. 2 and the direction perpendicular to the central axis corresponding to the vertical direction (up-down direction) in FIG. 2 . With respect to the Al phase in the L cross section, the above-mentioned "short side length c" corresponds to the dimension indicated by the symbol c in FIG. 2. Also, with respect to the Al phase in the L cross section, the above-mentioned "long side length d" corresponds to the dimension indicated by the symbol d in FIG. 2. Hereinafter, the ratio (c / d) of the short side length c to the long side length d of the Al phase in the L cross section will also be simply referred to as the "shape ratio (c / d) of the Al phase." The numerical value of the shape ratio (c / d) of the Al phase can be obtained using the grain shape aspect ratio in the analysis software provided with the apparatus.

[0047] The reason why the variation in the bonding width during bonding can be reduced by controlling the average value of the shape ratio (c / d) of the Al phase in the Al connecting material of the present invention is presumed to be as follows. If the Al phase is long, such as in a columnar or fibrous shape, the deformation of the Al connecting material becomes non-uniform when ultrasonic vibration and load are applied, causing the bonding width to vary. As mentioned above, optimizing the specific electrical resistivity and controlling the material structure of solid solution and fine precipitation to achieve a state in which deformation is promoted. In addition, optimizing the shape ratio (c / d) of the Al phase is thought to have the effect of uniforming the directionality of deformation, friction, and bonding, thereby stabilizing the bonding width. Because Al connection materials are manufactured by processes such as extrusion and wire drawing, the Al phases generally tend to be flattened along the central axis of the Al connection material. That is, the Al phases tend to be aligned so that the long side length d is aligned along or close to the central axis of the Al connection material. Furthermore, as described above, the complex deformation in directions parallel and perpendicular to the ultrasonic vibration is controlled by optimizing the crystal orientation of the Al phase. Therefore, it is believed that the desired effect can be achieved by controlling the shape ratio (c / d) of the Al phases without specifying the direction. Note that, to reduce the variation in the bonding width during bonding, it is sufficient that the average value of the shape ratio (c / d) of the Al phases in the L cross section is within the preferred range, and it is not necessary for the shape ratio (c / d) of all Al phases to be in the range of 0.2 to 0.7. For example, the Al connection material may contain Al phases with a shape ratio (c / d) of less than 0.2 or greater than 0.7.

[0048] From the viewpoint of reducing the variation in the joining width during joining and better realizing the temperature cycle reliability required for next-generation power semiconductor devices, the average value of the shape ratio (c / d) of the Al phase in the L cross section of the Al connecting material of the present invention is more preferably 0.25 or more, and the upper limit thereof is more preferably 0.65 or less.

[0049] A method for measuring the shape ratio (c / d) of the Al phase in the L-section of an Al connecting material will be described. First, as with the crystal orientation measurement described above, a method can be used that combines information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. The detailed procedure may be the same as that described above in relation to the measurement of the crystal orientation ratio. That is, the crystal orientation of the region identified as Al phase can be analyzed using the analysis software provided with the device. If the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the shape ratio (c / d) is calculated. The average value of the shape ratios (c / d) of each Al phase is defined as the average value of the shape ratio (c / d) of the Al phase. In the process of determining the shape ratio (c / d) of the Al phase, portions where the crystal orientation could not be measured or portions where the crystal orientation could be measured but the reliability of the orientation analysis was low were excluded from the calculation. Therefore, in one embodiment, the average value of the shape ratio (c / d) of the Al phase in the L-section of the Al connecting material of the present invention is calculated using the following steps (1) to (3). (1) Using the L-section of the Al connecting material as the inspection surface, the Al and Si concentrations are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) Using the Chi Scan function, Al and Si are separated and extracted. Specifically, by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results, Al and Si can be separated and identified. The crystal orientation can be analyzed using the Al and Si crystal information from the material file. (3) For the region identified as Al phase, the crystal orientation is analyzed, and if the orientation difference between the measurement points is 15° or more, it is determined to be a grain boundary, and the shape ratio (c / d) of each crystal grain is calculated. The shape ratios (c / d) of each crystal grain are averaged to calculate the average shape ratio (c / d) of the Al phase. Here, the average value of the Al phase shape ratio (c / d) is calculated using the numerical value of the grain shape aspect ratio (hereinafter referred to as the "grain shape aspect ratio") of the analysis software. This value is the average value obtained by averaging the grain shape aspect ratio of each crystal grain. The grain shape aspect ratio is calculated by the ratio (c / d) of the short side length (c) (Grain Shape Minor Axis) to the long side length (d) (Grain Shape Major Axis) of one crystal grain.Furthermore, for the average calculation, the average value obtained by area averaging, which can be selected in the software provided with the device, is used. By using the average value obtained by area averaging, it is possible to accurately measure and determine whether the conditions related to the average value of the shape ratio (c / d) of the Al phase, which is suitable for reducing the variation in the bonding width during bonding, are met. In calculating the area average, the software automatically calculates the average of the values ​​obtained by multiplying each particle area value by the proportion that each particle area occupies in the area of ​​all particles.

[0050] When measuring the average value of the shape ratio (c / d) of the Al phase in the L cross section, the setting range of Tolerance in the procedure (2) above and the measurement area of ​​the crystal orientation by the EBSD method are as described above with respect to the measurement of the orientation ratio of the crystal orientation of the Al phase.

[0051] In addition to the above, there are several other methods for measuring the shape ratio (c / d) of the Al phase, including binarization processing from an observed image of the L cross section. However, in the present invention, a method is used in which the information on the Al concentration and Si concentration obtained by SEM-EDS is combined with the information on the crystal orientation obtained by EBSD, as described above, for reasons such as the fact that the present invention is equipped with many measurement functions and can determine multiple characteristics such as the above-mentioned crystal orientation and the shape ratio (c / d) of the Al phase in a single measurement, that automatic analysis is possible, and that measurement is easy using widely used equipment and analysis techniques.

[0052] -Addition of Sr, Na, Ca, and B- The Al connecting material of the present invention may further contain one or more of Sr, Na, Ca, and B (hereinafter also referred to as "first element group") in a total amount of 5 ppm by mass or more and 800 ppm by mass or less.

[0053] It has been found that in Al connecting materials strengthened by adding Si or other additives, cracks (internal cracks) may occur within the Al connecting material during wire drawing. This is thought to be due to the formation of coarse Si crystals and non-uniform plastic deformation of the Al phase. Since internal cracks can lead to defects such as reduced temperature cycle reliability and melting fracture when a large current is applied, it is necessary to suppress the occurrence of internal cracks.

[0054] Even when the Si content is 4.0 mass% or more and 12.0 mass% or less, the occurrence of internal cracks during processing can be suppressed by further containing one or more of Sr, Na, Ca, and B in a total amount of 5 mass ppm or more and 800 mass ppm or less. Adding the first element group at a total concentration of 5 mass ppm or more and 800 mass ppm or less is thought to reduce the size of Si crystals and uniformly disperse them within the Al connecting material, thereby suppressing the occurrence of crack initiation points. Furthermore, adjusting the amount of Si solid solution within the Al phase by controlling the specific electrical resistivity is thought to have the effect of alleviating processing strain in the Al phase and suppressing crack growth.

[0055] From the viewpoint of suppressing the occurrence of internal cracks during processing, the total concentration of the first element group in the Al connecting material of the present invention is more preferably 20 mass ppm or more, even more preferably 30 mass ppm or more, 40 mass ppm or more, or 50 mass ppm or more, and the upper limit is preferably 750 mass ppm or less, more preferably 740 mass ppm or less, 720 mass ppm or less, or 700 mass ppm or less, from the viewpoint of easily achieving good first bonding strength while suppressing damage to the semiconductor chip.

[0056] - Addition of Fe, Mg, P, and Ti - The Al connecting material of the present invention may further contain one or more of Fe, Mg, P, and Ti (hereinafter also referred to as the "second element group") in a total amount of 5 ppm by mass or more and 500 ppm by mass or less.

[0057] Furthermore, by containing at least one of Fe, Mg, P, and Ti in a total amount of 5 mass ppm to 500 mass ppm, scratches and abrasions on the surface of the Al connecting material can be suppressed, resulting in a smooth surface. Al alloys containing Si at a high concentration of 4.0 mass% to 12.0 mass% can harden the surface and cause the Si phase and Al oxide present on the surface to fall off, resulting in scratches and abrasions on the surface during wiredrawing, resulting in an Al connecting material with large surface irregularities. It is believed that the addition of the second element group stabilizes the Al oxide on the surface of the Al connecting material, refines the structure of the Al crystal grains, and hardens them, thereby reducing scratches and abrasions during wiredrawing. It is believed that controlling the orientation ratio of the crystal orientation of the Al phase in the L cross section and adding the second element group can suppress scratches and abrasions on the surface of the Al connecting material, thereby enhancing the effect of forming a smooth surface.

[0058] From the viewpoint of forming an Al connecting material having a smooth surface by suppressing the occurrence of scratches and abrasion on the surface, the total concentration of the second element group in the Al connecting material of the present invention is more preferably 10 mass ppm or more, even more preferably 20 mass ppm or more, 30 mass ppm or more, 40 mass ppm or more, or 50 mass ppm or more, and the upper limit thereof is preferably 450 mass ppm or less, more preferably 440 mass ppm or less, 420 mass ppm or less, or 400 mass ppm or less, from the viewpoint of easily achieving good first bonding strength while suppressing damage to the semiconductor chip.

[0059] When manufacturing the Al connecting material of the present invention, it is preferable to use Al with a purity of 4N (Al: 99.99% by mass or more) as the aluminum raw material, and it is even more preferable to use Al with a purity of 5N (Al: 99.999% by mass or more) or more, which has a lower amount of impurities.

[0060] The Al connecting material of the present invention may further contain elements other than Al, Si, the first element group, and the second element group (hereinafter also referred to as "other elements"), as long as the effects of the present invention are not impaired. The total concentration of the other elements in the Al connecting material is not particularly limited, as long as the effects of the present invention are not impaired. The total concentration of the other elements may be, for example, 0.5 mass% or less, 0.4 mass% or less, 0.3 mass% or less, 0.2 mass% or less, 0.15 mass% or less, 0.1 mass% or less, 0.08 mass% or less, 0.06 mass% or less, 0.05 mass% or less, 0.04 mass% or less, 0.03 mass% or less, 0.025 mass% or less, 0.02 mass% or less, 0.018 mass% or less, 0.016 mass% or less, 0.015 mass% or less, 0.014 mass% or less, 0.012 mass% or less, or 0.01 mass% or less. The lower limit of the total concentration of the other elements is not particularly limited, and may be 0 mass%. In one embodiment, the remainder of the Al connecting material of the present invention consists of Al and other elements. Therefore, in a preferred embodiment, the Al connecting material of the present invention consists of Al, Si, and other elements. In another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the first element group, and other elements. In yet another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the second element group, and other elements. In yet another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and other elements.

[0061] In one embodiment, the balance of the Al connecting material of the present invention consists of Al and inevitable impurities. Therefore, in a preferred embodiment, the Al connecting material of the present invention consists of Al, Si, and inevitable impurities. In another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the first element group, and inevitable impurities. In yet another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the second element group, and inevitable impurities. In yet another preferred embodiment, the Al connecting material of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and inevitable impurities.

[0062] In a preferred embodiment, the Al connecting material of the present invention does not have a coating containing a metal other than Al as a main component on the outer periphery of the Al connecting material. Here, the term "coating containing a metal other than Al as a main component" refers to a coating in which the content of a metal other than Al is 50 mass % or more.

[0063] The Al connecting material of the present invention may be an Al bonding wire or an Al bonding ribbon. When the Al connecting material of the present invention is an Al bonding wire, its wire diameter is not particularly limited and may be, for example, in the range of 100 to 600 μm. When the Al connecting material of the present invention is an Al bonding ribbon, the dimensions (W×T) of its rectangular or approximately rectangular cross section are not particularly limited and, for example, W may be 100 to 3000 μm and T may be 50 to 600 μm.

[0064] The Al connecting material of the present invention can provide excellent temperature cycle reliability and good first bond strength, and therefore can be suitably used as an Al connecting material for semiconductor devices, particularly for power semiconductor devices.

[0065] -Method of Manufacturing Al Connecting Material- An example of a method of manufacturing an Al connecting material of the present invention will be described below, focusing on the manufacture of an Al bonding wire with a wire diameter of 200 to 400 μm.

[0066] The Al and alloying elements used as raw materials preferably have high purity. The purity of Al is preferably 99.99% by mass or more, with the remainder consisting of inevitable impurities. The purity of Si, the first element group, and the second element group used as alloying elements is preferably 99.9% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for bonding wire can be produced by loading the Al raw material and the alloying element raw materials into a graphite or alumina crucible processed to obtain a cylindrical ingot and melting them using an electric furnace or high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm, taking into account the workability in subsequent processing steps. The atmosphere in the furnace during melting is preferably an inert or reducing atmosphere to prevent excessive oxidation of Al and other elements constituting the wire. The maximum temperature of the molten metal during melting is preferably in the range of 800°C or more and less than 1050°C, taking into account factors such as ensuring the fluidity of the molten metal and making it easier to control the shape and size of the Si phase during solidification. The cooling method after melting can be water cooling, furnace cooling, air cooling, or the like.

[0067] The cylindrical ingot obtained by melting is subjected to a solution treatment in which it is heated at a high temperature, and then repeatedly subjected to wire drawing using a die to produce a wire of the desired wire diameter. The wire after wire drawing can be used as an Al alloy bonding wire by performing a final heat treatment using an electric furnace.

[0068] In order to control the crystal orientation and grain size of the Si phase in the L cross section, it is effective to control the heat treatment conditions such as solution treatment, homogenization treatment, and final heat treatment, as well as the wiredrawing conditions, etc. During the wiredrawing process, it is effective to use a lubricant to ensure lubrication at the contact interface between the wire and the die.

[0069] Specific electrical resistance is 2.6 x 10 －８ Ωm or more 3.6 x 10 －８ An example of the manufacturing conditions for controlling the resistance to a range of Ωm or less is shown below.

[0070] In order to adjust the specific electrical resistivity, it is effective to control the amount of Si solid solution in the Al phase and the amount and distribution of fine precipitates. Specifically, it is effective to subject the ingot to two-stage heat treatment and control the conditions of the final heat treatment.

[0071] In the two-stage heat treatment, it is preferable to perform a solution treatment at a high temperature and then a homogenization treatment continuously during the subsequent cooling. It is effective to perform the solution treatment at a temperature range of 400°C or higher but lower than 550°C for a period of 1 hour or higher but lower than 6 hours. It is effective to perform the homogenization treatment after the solution treatment at a temperature range of 250°C or higher but lower than 350°C for a period of 2 hours or higher but lower than 6 hours. The solution treatment at a high temperature promotes the solid solution of Si, and by adjusting the heat treatment time, it is possible to dissolve a portion of the crystallized Si phase. Furthermore, the homogenization treatment during cooling can control the amount of Si dissolved by precipitating a portion of the excess Si to form fine Si precipitates or by growing some of the Si crystals. For example, if the solution treatment is performed at a high temperature of 500°C to increase the amount of Si dissolved, and then the homogenization treatment is performed at 300°C, the specific electrical resistivity tends to decrease.

[0072] Furthermore, in order to finely adjust the specific electrical resistivity, it is effective to set the temperature range of the final heat treatment to 250°C or higher and lower than 350°C, and the time period to 2 hours or higher and lower than 24 hours. By processing the ingot subjected to the above two-stage heat treatment to form a state in which the Si phase is distributed almost uniformly, and then performing the final heat treatment, it is possible to uniformly control the concentration of Si dissolved in the Al phase. As a result, it becomes easy to control the specific electrical resistivity. For example, if the final heat treatment is performed at a low temperature for a long time, the specific electrical resistivity tends to decrease.

[0073] In order to adjust the total ratio of <110> + <111> of the Al phase in the L cross section to the range of 20% to 70%, it is effective to control the final heat treatment conditions.

[0074] To adjust the total ratio of the <110> + <111> phase of the Al phase to the desired range, the temperature range of the final heat treatment is preferably adjusted to 250°C or higher but lower than 350°C, and the time range is preferably adjusted to 2 hours or higher but lower than 24 hours. The final heat treatment promotes recovery and recrystallization of the Al phase, and at the same time, the amount of Si solid solution in the Al phase changes depending on the heat treatment temperature, thereby changing the recrystallization temperature. By adjusting the progress of recrystallization by the final heat treatment in addition to the formation of the above-mentioned deformation texture, it becomes easy to control the orientation of the crystal orientation. For example, adjusting the final heat treatment to a low temperature or a short time tends to increase the orientation ratio of the densely packed <110> crystal orientation and the <111> crystal orientation.

[0075] In order to adjust the <110> ratio of the Al phase in the L cross section to a range of 5% to 40%, it is effective to control the wire feed speed (wire drawing speed) in the wire drawing process and the final heat treatment conditions.

[0076] Controlling the wire feed speed according to the wire diameter used for wiredrawing is effective for controlling the <110> ratio of the Al phase. The process of drawing a wire to one-fifth the wire diameter of the ingot obtained by melting is referred to as "wiredrawing 1," and the process of drawing a wire from one-fifth the wire diameter to the final wire diameter is referred to as "wiredrawing 2." The wire feed speed in wiredrawing 1 is preferably 10 m / min or more but less than 25 m / min, and the wire feed speed in wiredrawing 2 is preferably 30 m / min or more but less than 50 m / min. Furthermore, it is preferable to adjust the temperature range of the final heat treatment to be 270°C or more but less than 330°C, and the time to be 10 hours or more but less than 24 hours. Setting the wire feed speed within a predetermined range makes it possible to adjust the stress applied in the direction of the wire's central axis during wiredrawing. Furthermore, setting the final heat treatment conditions within a predetermined range promotes the rotation of the crystal orientation, making it easier to control the <110> ratio of the Al phase.

[0077] In order to adjust the crystal orientation of the Si phase, it is effective to subject the ingot to two-stage heat treatment as described above and to control the area reduction rate during wire drawing.

[0078] By adjusting the conditions of the two-stage heat treatment as described above, it is possible to promote the division and growth of the Si phase that crystallizes during the solidification process, thereby promoting the orientation of the Si phase in the <111> and <110> crystal directions.

[0079] Regarding the wire drawing conditions, it is effective to set the wire area reduction rate per die used during wire drawing to a range of 12% or more and less than 30%. Here, if the wire area reduction rate per die is P1, P1 is expressed by the following formula.

[0080] P1 = {(R ２ ２ -R １ ２ ) / R ２ ２}×100 where R ２ is the diameter of the wire before processing (mm), R １ represents the diameter (mm) of the wire after processing.

[0081] By adjusting the wire area reduction rate within the above range, the entire wire is significantly deformed during die processing, increasing processing strain even within the wire, and the Si phase is aligned along the central axis of the wire while simultaneously adjusting the processing strain within the Si phase. By performing a subsequent heat treatment in this wiredrawing state, it is possible to increase the orientation ratio of the <111> crystal orientation and the <110> crystal orientation, which have high atomic density, and also to increase the orientation ratio of the <111> crystal orientation and the <110> crystal orientation, which have high elastic modulus, in the Si phase.

[0082] In order to adjust the shape (shape ratio (c / d)) of the Al phase in the L cross section, it is effective to control the intermediate heat treatment and the final heat treatment.

[0083] Intermediate heat treatment is a heat treatment performed during the process of processing an ingot into a wire of the final wire diameter. The temperature range of the intermediate heat treatment is preferably 300°C or higher and lower than 450°C, and the time period is preferably 30 minutes or higher and lower than 3 hours. Intermediate heat treatment is preferably performed at a wire diameter 2.5 to 4.0 times the final wire diameter. By performing intermediate heat treatment, it is possible to reduce processing strain in the Al phase and promote recrystallization. Primary adjustment of the Al phase facilitates adjustment of the shape ratio (c / d) of the Al phase in the subsequent final heat treatment. For example, increasing the intermediate heat treatment temperature tends to granulate the crystal grains of the Al phase, increasing the shape ratio (c / d).

[0084] It is effective to set the temperature range of the final heat treatment to 250°C or higher and lower than 350°C, and the time period to 2 hours or higher and lower than 24 hours. The above-mentioned processing strain in the wire due to wiredrawing is used as a driving force to promote the progress of recrystallization of the Al phase, thereby adjusting the shape or crystal orientation of the crystal grains. For example, if the final heat treatment is performed at a low temperature for a long time, the crystal grains of the Al phase tend to become granular, and the shape ratio (c / d) tends to increase.

[0085] As mentioned above, the above is an example of the production of Al bonding wire, which is a wire material, as a representative example of an Al connecting material. The same procedure can also be used to produce Al bonding ribbon, which is a strip material. The temperature and time of the heat treatment can be approximately the same as those described above. Furthermore, when producing Al bonding ribbon by rolling, the die area reduction rate can be adjusted by replacing it with the rolling reduction rate.

[0086] [Semiconductor Device] A semiconductor device can be manufactured by connecting electrodes on a semiconductor chip to external electrodes on a lead frame or substrate using the Al connecting material of the present invention. As described above, wedge bonding is used for both the first bonding with the electrodes on the semiconductor chip and the second bonding with the electrodes on the lead frame or substrate.

[0087] In one embodiment, the semiconductor device of the present invention includes a circuit board, a semiconductor chip, and an Al connecting material for electrically connecting the circuit board and the semiconductor chip, and is characterized in that the Al connecting material is the Al connecting material of the present invention.

[0088] In the semiconductor device of the present invention, the circuit board and semiconductor chip are not particularly limited, and known circuit boards and semiconductor chips that can be used to configure a semiconductor device may be used. Alternatively, a lead frame may be used instead of the circuit board. For example, a semiconductor device may be configured including a lead frame and a semiconductor chip mounted on the lead frame, as in the semiconductor device described in JP 2020-150116 A.

[0089] Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, air conditioners, solar power generation systems, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.), and among these, power semiconductor devices are preferred.

[0090] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the examples shown below.

[0091] (Sample) The sample preparation method will be described. The raw material Al had a purity of 4N (99.99% by mass or more), with the remainder consisting of inevitable impurities. The alloying elements Si, the first element group (Sr, Na, Ca, B), and the second element group (Fe, Mg, P, Ti) had a purity of 99.99% by mass or more, with the remainder consisting of inevitable impurities. The Al alloy used for the Al connecting material was produced by loading the Al raw material and the alloying element raw materials into an alumina crucible and melting them using a high-frequency heating furnace. The atmosphere inside the furnace during melting was an Ar atmosphere, and the maximum temperature of the molten metal during melting was 800 to 1050°C. The cooling method after melting was air cooling (cooling in air) or water cooling (cooling in water).

[0092] A cylindrical ingot with a diameter of 6 mm was obtained by melting, and the ingot was subjected to solution treatment and homogenization treatment. After that, wire drawing using a die and intermediate heat treatment were performed to produce an Al connecting material (Al bonding wire) with a diameter of 300 μm. The temperature range of the solution treatment was 400 ° C or higher and lower than 550 ° C, and the time was 1 hour or higher and lower than 6 hours. After the solution treatment, a homogenization treatment was performed continuously during cooling. The temperature range of the homogenization treatment was 250 ° C or higher and lower than 350 ° C, and the time was 2 hours or higher and lower than 6 hours. The cooling method after the homogenization treatment was air cooling in the atmosphere.

[0093] A commercially available lubricant was used during wire drawing, and the wire area reduction rate per die during wire drawing was 12.5% ​​or more and less than 18.0%. The temperature range of the final heat treatment was 250°C or more and less than 350°C, and the time of the final heat treatment was 2 hours or more and less than 24 hours.

[0094] In some examples, the wire feed speed in wire drawing process 1 was 10 m / min or more and less than 25 m / min, and the wire feed speed in wire drawing process 2 was 30 m / min or more and less than 50 m / min. In some examples, the temperature range of the intermediate heat treatment was 300°C or more and less than 450°C, and the time period was 30 minutes or more and less than 3 hours. The intermediate heat treatment was performed once, and was performed with a wire diameter that was 2.5 to 4.0 times the final wire diameter.

[0095] (Method for measuring element content) The concentration analysis of elements contained in the Al connecting material was performed using an ICP-OES ("PS3520UVDDII" manufactured by Hitachi High-Tech Science Corporation) or an ICP-MS ("Agilent 7700x ICP-MS" manufactured by Agilent Technologies, Inc.) as an analytical device.

[0096] The specific electrical resistance of the Al connecting material was measured by a DC four-terminal measurement method. Specifically, a DM7275 manufactured by Hioki E.E. Corporation was used as a resistance meter, and the electrical resistance value of the sample was measured at room temperature with a sample length of 200 mm and a measurement current range of 0.02 to 0.1 mA. The measurement was performed five times, and the electrical resistance value R of each sample was calculated as the arithmetic average. If the electrical resistance value is R, the length of the sample is L, and the cross-sectional area of ​​the sample is S, the specific electrical resistance value M was calculated as R × (S / L).

[0097] (Method for measuring the orientation ratio of the crystal orientations of the Al phase and the Si phase) The L-section (a cross section in the central axis direction including the central axis) of the Al connecting material was used as the inspection surface, and the crystal orientations of the Al phase and the Si phase were measured. In the present invention, the central axis of the Al connecting material and the cross section in the central axis direction including the central axis (L-section) are as shown in FIG. 1. FIG. 1 shows a case where the Al connecting material is an Al bonding wire having a circular cross-sectional shape. However, if the Al connecting material is an Al bonding ribbon having a rectangular or approximately rectangular cross-sectional shape with a width W and a thickness T, the central axis refers to the axis passing through the center of the width W and the center of the thickness T, and the L-section refers to a cross section in the central axis direction including the central axis and in the direction of the thickness T. When processing the cross section to expose the L-section of the Al connecting material, there may be a deviation from the central axis of the Al connecting material. In this case, if the length in the direction perpendicular to the central axis of the L-section is 90% or more of the wire diameter of the Al connecting material (thickness T in the case of a ribbon), it can be considered to be a cross section including the central axis.

[0098] The measurements were performed using an FE-SEM (SU-70 manufactured by Hitachi High-Technologies Corporation) and either OIM Data Collection or OIM Analysis (both manufactured by TSL Solutions) or both. Three measurement areas were randomly selected at intervals of 50 cm or more along the central axis of the Al connecting material, and measurements were performed on the three areas. The measurement area was determined so that it was 300 μm or more and less than 800 μm in the direction of the central axis of the Al connecting material, and the entire Al connecting material was included in the direction perpendicular to the central axis. The main conditions for EDS and EBSD measurements were an acceleration voltage of 15 kV, a scan speed of 30 to 120 points / second, a measurement magnification of 350x, and a measurement interval in the range of 0.1 to 0.3 μm. Here, a fast scan speed can shorten the measurement time, but there is a concern that the EDS measurement accuracy will decrease. It is desirable to select an appropriate scan speed within the above range.

[0099] -Crystal orientation of the Al phase- To measure the orientation ratio of the Al phase in the L-section of the Al connection material, a method was used that combined information on the Al and Si concentrations obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. Specifically, the measurement was performed according to the following procedures (1) to (3). (1) In the measurement area where the L-section of the Al connection material was used as the inspection surface, Al and Si concentrations were measured using EDS and crystal orientation was measured using EBSD simultaneously. (2) Al and Si were separated and extracted using the Chi Scan function, a function of the EBSD analysis software. Specifically, Al and Si were separated and identified by setting a tolerance equivalent to the Si threshold from the Si EDS measurement results. Crystal orientation analysis was performed using the Al and Si crystal information from the material file. Here, the tolerance condition was mainly set to 30% and adjusted as necessary. (3) The crystal orientation of the region identified as the Al phase was analyzed, and the orientation ratio of the <110> crystal orientation and the orientation ratio of the <111> crystal orientation of the Al phase were calculated. The crystal orientations to be investigated were selected from at least three types of typical crystal orientations of Al metal: <111>, <110>, and <100>, and, if necessary, a crystal orientation with a high ratio. Here, the orientation ratio of the crystal orientations was calculated using the partial ratio.

[0100] The orientation ratio of the <110> crystal orientation and the orientation ratio of the <111> crystal orientation of the Al phase were calculated as the average values ​​obtained for the three measurement regions by the above steps (1) to (3).

[0101] -Crystal orientation of Si phase- As with the measurement of the orientation ratio of the crystal orientation of the Al phase, the measurement of the orientation ratio of the crystal orientation of the Si phase in the L cross section of the Al connecting material used a method that combined information on the Al concentration and Si concentration obtained by SEM-EDS with information on the crystal orientation obtained by EBSD. In detail, after carrying out the above procedures (1) and (2), the measurement was carried out according to the following procedure (3). (3) The crystal orientation of the region identified as the Si phase was analyzed, and the orientation ratio of the <111> crystal orientation and the orientation ratio of the <110> crystal orientation of the Si phase were calculated. The partial ratio was used for the orientation ratio of the crystal orientation.

[0102] The values ​​obtained for the three measurement regions by the above steps (1) to (3) were arithmetically averaged to determine the orientation ratio of the <111> crystal orientation and the orientation ratio of the <110> crystal orientation of the Si phase.

[0103] (Method for measuring the shape of the Al phase) The shape of the Al phase (shape ratio (c / d)) in the L cross section of the Al connecting material was measured using a method that combines information on the Al concentration and Si concentration obtained by SEM-EDS with information on the crystal orientation obtained by EBSD, similar to the measurement of the orientation ratio of the crystal orientation of the Al phase. In detail, after performing the above procedures (1) and (2), the measurement was carried out according to the following procedure (3). (3) For the region identified as the Al phase, the crystal orientation was analyzed, and if the orientation difference between the measurement points was 15° or more, it was determined to be a grain boundary, and the shape ratio (c / d) of each crystal grain was obtained. Then, the shape ratio (c / d) of each crystal grain was averaged to calculate the average value of the shape ratio (c / d) of the Al phase. Here, the average value of the shape ratio (c / d) of the Al phase was calculated using the numerical value of the Grain Shape Aspect Ratio ("grain aspect ratio") of the analysis software. Here, the grain shape aspect ratio is calculated by automatically calculating the ratio (c / d) of the short side length (c) (Grain Shape Minor Axis) of one crystal grain to the long side length (d) (Grain Shape Major Axis). Here, the average value obtained by area averaging was used for the average calculation.

[0104] (Method for evaluating Al connecting material) The method for evaluating the Al connecting material will be described. The wire diameter of the Al connecting material (Al bonding wire) used for evaluation was Φ300 μm. The semiconductor chip used was made of Si, and the electrodes on the semiconductor chip were made of an alloy with a composition of Al-0.5% Cu, formed to a thickness of 4 μm. The substrate used was an Al alloy with a Ni film formed to a thickness of 5 μm. A commercially available wire bonder (manufactured by Ultrasonic Industries Co., Ltd.) was used to bond the Al connecting material, and wedge bonding was used for both the first bonding and the second bonding.

[0105] (Method for Evaluating High-Speed ​​Temperature Cycle Reliability) A commercially available high-speed thermal shock tester was used to evaluate the high-speed temperature cycle test (high-speed TCT). In high-speed TCT, hot air is blown onto the sample to rapidly heat it. The sample used for high-speed TCT had a structure in which a semiconductor chip was mounted on a substrate, and electrodes on the semiconductor chip and electrodes on the substrate were connected with an Al connecting material. The sample placed in the sample chamber of the high-speed thermal shock tester was repeatedly subjected to thermal loads, with heating and cooling cycles consisting of one cycle. The minimum temperature during cooling was -50°C, and the maximum temperature during heating was 175°C. The heating time, including the temperature rise time, was 20 seconds, and the cooling time, including the temperature drop time, was 40 seconds. After the start of the test, the sample was removed after 10,000 cycles and a shear strength test of the first bond was performed. The shear strength value of the first bond used to evaluate the high-speed temperature cycle reliability was the average shear strength of 10 randomly selected first bond locations. The strength retention rate was defined as the ratio (percentage) of the average shear strength after high-speed TCT to the average shear strength before the test. The higher the strength retention rate, the better the reliability of the joint. A strength retention rate of 85% or higher was judged to be particularly excellent and rated "4," 80% or higher but less than 85% was judged to be good and rated "3," 75% or higher but less than 80% was judged to be satisfactory and rated "2," 70% or higher but less than 75% was judged to require improvement and rated "1," and less than 70% was judged to be problematic in practical use and rated "0." Ratings of "4," "3," and "2" were acceptable, while "1" and "0" were unacceptable. The evaluation results are listed in the "High-speed temperature cycle reliability (10,000 cycles)" column in the table. The temperature cycle reliability requirement for next-generation power semiconductor devices corresponds to 10,000 cycles.

[0106] (Method for Evaluating First Bond Strength) The method for evaluating the first bond strength will be described. The first bond strength was evaluated by a shear strength test. First bond was performed at 10 locations under typical bonding conditions, and the shear strength of the first bonded portion was measured. A commercially available microshear strength tester (Nordson 4000-PLUS) was used to measure the shear strength. The shear rate was 200 μm / sec, and the height of the shear tool was 10 μm from the electrode surface. The shear strength was measured by fixing the substrate to which the Al connecting material was bonded using a jig. If the average shear strength of the 10 first bonded portions was 1600 gf or more, it was judged to be excellent and rated as "3." If it was 1400 gf or more but less than 1600 gf, it was judged to be practically acceptable and rated as "2." If it was 1000 gf or more but less than 1400 gf, it was judged to require improvement and rated as "1." If it was less than 1000 gf, it was judged to be practically problematic and rated as "0." The evaluation results are shown in the column "1st bonding strength" in the table.

[0107] (Method of Evaluating Damage to Semiconductor Chips) Damage to semiconductor chips was evaluated by dissolving the metal on the pad surface with acid and observing the area under the pad under a microscope (number of evaluations N = 50). A good case with no cracks or bonding traces was given a grade of "3", a case with no cracks but some bonding traces (3 or less out of 50 evaluations) was given a grade of "2", and the rest was given a grade of "1", and these were recorded in the "Chip Damage" column in the table.

[0108] (Method for Evaluating Holes in the First Joint) A method for evaluating defects in the first joint will now be described. After conducting the shear strength test for the first joint described above, the indentations on the fracture surface on the electrode side were observed using an optical microscope or SEM, and areas where a metal bond was not obtained within the fractured region were determined to be holes. Holes are areas where the electrodes are not bonded even when deformed, and can be distinguished from areas where the bond is metal bonded. The shear strength test was performed under the conditions described above, and the fracture surfaces of 10 first joints were observed. The ratio of the total length (K) of the holes in the bond width direction to the bond length (J) in the direction perpendicular to the central axis of the Al connecting material (the bond width direction) was calculated as the hole ratio (K / J) ( FIG. 3 ). The hole ratios were confirmed for the 10 fracture surfaces, and the maximum value was defined as the "hole defect rate." If the defect rate of hollows was less than 5%, it was judged to be good and rated as "3", if it was 5% or more but less than 15%, it was judged to be no problem in practical use and rated as "2", if it was 15% or more but less than 25%, it was judged to need improvement and rated as "1", and if it was over 25%, it was judged to be an obstacle to mass production and rated as "0". The evaluation results are shown in the column for "Hollows in 1st joint" in the table.

[0109] (Method for Evaluating Joint Width Stability) The method for evaluating the stability of the joint width will be described. After conducting the shear strength test of the first joint described above, the indentation width (joint width) of the indentation on the fracture surface on the electrode side was evaluated. Specifically, for the indentation on the fracture surface, the joint length (J) in the direction perpendicular to the central axis of the Al connecting material was measured at the center position of the joint length in the central axis direction of the Al connecting material, and the population standard deviation (σ) was calculated. When σ was 15 μm or more, it was judged to be problematic for practical use and rated "1." When σ was 5 μm or more but less than 15 μm, it was judged to be good and rated "2." When σ was less than 5 μm, it was judged to be excellent and rated "3." "1" was a failure, and "2" and "3" were pass. The evaluation results are shown in the "Joint Width Stability" column in the table.

[0110] (Method for Evaluating Internal Cracks) A method for evaluating internal cracks in Al connecting materials will be described. The manufactured Al connecting materials were evaluated by observation (hereinafter referred to as X-ray observation) using a soft X-ray projection inspection device (μB2600, manufactured by Matsusada Precision). The measurement conditions for X-ray observation can be determined appropriately depending on the wire diameter of the Al connecting material. For the Al connecting material manufactured in this example with a wire diameter of 300 μm, the voltage was adjusted to 50 to 80 kV and the current to 60 to 90 μA. Three locations were randomly selected at intervals of 1 m or more along the central axis of the Al connecting material, and three samples with a length of approximately 8 cm were selected from each of the three locations, for a total of nine measurement samples. Figure 4 shows an example of X-ray observation of an Al connecting material with a wire diameter of 300 μm, in which internal cracks are observed. If the length of an internal crack was 0.3 mm or more, it was judged to be a problematic defect and given a score of "2", and if it was 0.1 mm or more but less than 0.3 mm, it was judged to require attention and given a score of "0.5". The sum of the scores for the measurement points was set as the "crack index". For the crack index of the entire measurement sample, if it was zero it was judged to be good and given a score of "3", if it was in the range of 0.1 to 2.0 it was judged to be no problem for practical use and given a score of "2", if it was in the range of 2.0 to 5.0 it was judged to need improvement and given a score of "1", and if it was over 6.0 it was judged to be difficult to use and given a score of "0". The evaluation results are shown in the "internal crack" column in the table.

[0111] (Method for evaluating surface scratches and abrasions) The surface quality of the Al connecting material was evaluated, focusing on scratches and abrasions. Three measurement areas were randomly selected at intervals of 1 m or more along the central axis of the Al connecting material, and three samples approximately 2 cm long were taken from each of the three areas, for a total of nine samples to be observed. The surface was observed at magnifications ranging from 50 to 500 times using an SEM. Scratches longer than 50 μm and abrasions longer than 30 μm were judged to be defective. The number of scratches and abrasions was counted, and a score of "3" was given for a good pass; two or less scratches were judged to be acceptable for practical use; three to seven scratches were judged to have poor surface quality; and eight or more scratches were judged to be difficult to use and were rated "0." The evaluation results are shown in the "Surface Quality" column in the table.

[0112] The evaluation results of the Examples and Comparative Examples are shown in Tables 1 to 3.

[0113]

[0114]

[0115]

[0116] All of the Al connecting materials of Examples 1 to 58 contained 4.0 mass % or more and 12.0 mass % or less of Si, and their specific electrical resistivity Ra was 2.6 × 10 －８ Ωm or more 3.6 x 10 －８It was confirmed that the Al connecting materials of Example Nos. 1 to 13, 15 to 30, 32 to 50, 52, 53, and 55 to 58, in which the <110> ratio of the Al phase in the L cross section is 5% or more and 50% or less, exhibit better first bond strength and are also more likely to suppress hollowing of the first bonded portion. Example Nos. 1 to 13, 15 to 30, 32 to 50, 52, 53, and 55 to 58, in which the <110> ratio of the Al phase in the L cross section is 5% or more and 50% or less, exhibit better first bond strength and are more likely to suppress hollowing of the first bonded portion. Example Nos. 1 to 13, 15 to 30, 32 to 50, 52, 53, and 55 to 58, in which the <111> ratio of the Si phase in the L cross section is 20% or more and 70% or less, exhibit good temperature cycle reliability and good first bond strength even in high-speed TCT. It was confirmed that the Al connecting materials of Example Nos. 1 to 37 and 40 to 58 tend to have better temperature cycle reliability in high-speed TCT. It was confirmed that the Al connecting materials of Example Nos. 1 to 6, 8 to 23, and 25 to 58, in which the average value of the shape ratio (c / d) of the Al phase in the L cross section is 0.2 or more and 0.7 or less, tend to reduce the variation in the bonding width during bonding and stabilize the bonding width. Furthermore, it was confirmed that the Al connecting materials of Example Nos. 27 to 33, 35 to 37, 48 to 51, and 55 to 58, which contain one or more elements from the first element group (Sr, Na, Ca, B) in a total amount of 5 ppm by mass to 800 ppm by mass, can reduce internal cracks during processing. It was confirmed that the Al connecting materials of Example Nos. 27 to 33, 35 to 37, 48 to 51, and 55 to 58, which contain one or more elements from the second element group (Fe, Mg, P, Ti) in a total amount of 5 ppm by mass to 500 ppm by mass, can reduce internal cracks during processing. It was confirmed that the Al connecting materials of Comparative Examples 39 to 51 and 53 to 58 had smooth surfaces with reduced surface scratches and chipping. On the other hand, it was confirmed that the Al connecting materials of Comparative Examples 1 to 10 had any of the Si concentration, specific electrical resistivity, and total ratio of the <110> + <111> Al phase in the L cross section (including the <110> ratio of the Al phase when the total ratio was 25% or less) outside the range of the present invention, and that either high-speed temperature cycle reliability or 1st bonding strength was not sufficiently obtained.

Claims

1. An Al connecting material containing 4.0 mass% or more and 12.0 mass% or less of Si, and having a specific electrical resistance Ra of 2.6 x 10 －８ Ωm or more 3.6 x 10 －８ an Al connecting material having a resistivity of Ωm or less, and when the crystal orientation of the Al phase in an L cross section (a cross section in the central axis direction including the central axis) of the Al connecting material is measured, the total orientation ratio of the <110> crystal orientation and the <111> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, is 20% or more and 70% or less, and when the total orientation ratio is 25% or less, the orientation ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the central axis, is 5% or more.

2. An Al connecting material as described in claim 1, in which the ratio of the <110> crystal orientation, which has an angular difference of 15° or less with respect to the central axis direction, in the crystal orientation of the Al phase in the L cross section is 5% or more and 50% or less.

3. An Al connecting material as described in claim 1 or 2, in which, when the crystal orientation of the Si phase in the L cross section is measured, the total orientation ratio of the <111> crystal orientation and the <110> crystal orientation, which have an angular difference of 15° or less with respect to the central axis direction, is 20% or more and 70% or less.

4. An Al connecting material according to any one of claims 1 to 3, in which the average ratio (c / d) of the short side length c to the long side length d of the Al phase in the L cross section is 0.2 or more and 0.7 or less.

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

6. An Al connecting material according to any one of claims 1 to 5, further containing at least one of Fe, Mg, P and Ti in a total amount of 5 ppm by mass or more and 500 ppm by mass or less.

7. An Al connecting material according to any one of claims 1 to 6, in which the total concentration of other elements in the Al connecting material is 0.5 mass% or less.

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