JP7126322B2 - aluminum bonding wire - Google Patents

Description

The present invention relates to Al bonding wires.

2. Description of the Related Art In a semiconductor device, electrodes formed on a semiconductor element and electrodes on a lead frame or substrate are connected by bonding wires. As materials for bonding wires, integrated circuit semiconductor devices such as VLSI use gold (Au) or copper (Cu), while power semiconductor devices mainly use aluminum (Al). For example, Patent Literature 1 shows an example of using a 300 μmφ aluminum bonding wire (hereinafter referred to as “Al bonding wire”) in a power semiconductor module. In power semiconductor devices using Al bonding wires, wedge bonding is used as a bonding method for both the connection with the electrodes on the semiconductor element and the connection with the electrodes on the lead frame and the substrate.

Power semiconductor devices using Al bonding wires are often used as semiconductor devices for high-power equipment such as air conditioners and photovoltaic systems, and for vehicles. In these semiconductor devices, the bonding portion of the Al bonding wire is exposed to a high temperature of 100 to 150.degree. When a material made of only high-purity Al is used as an Al bonding wire, it is difficult to use the wire in a high-temperature environment because the wire tends to soften in such a temperature environment.

Patent Document 2 discloses an Al wire containing 0.02 to 1% by weight of Fe. In an Al wire containing no Fe, recrystallization occurs immediately above the wire bonding interface at high temperatures during semiconductor use, forming small crystal grains and causing cracks. On the other hand, the recrystallization temperature can be raised by containing Fe: 0.02% or more. By annealing after wire drawing, the wire crystal grain size before bonding is set to 50 μm or more. The crystal grain size is large, and since it does not recrystallize even at high temperatures when semiconductors are used, cracks do not occur.

In Invention Product 3 of Patent Document 3, a 99.99 wt% (4N) high-purity Al-0.2 wt% Fe alloy ingot is prepared, and after wire drawing, it is annealed at 300 ° C. for 30 minutes and then slowly cooled to remove processing strain. A wire with a diameter of 300 μm is disclosed which has been softened by heating. By aging at 100 to 200°C for 1 minute to 1 hour after bonding, it is possible to suppress the progress of cracks that occur in the joints due to repeated application of large currents during use even when the maximum operating temperature reaches 200°C. It's going to be

Patent Document 4 describes a bonding wire made of aluminum (Al) having a purity of 99.99% or more with iron (Fe) of 0.2 to 2.0% by mass and a balance of 0.01 to 0.01% Fe in the Al matrix. It is disclosed that the Fe.Al intermetallic compound particles are uniformly crystallized with a solid solution of 0.05%, a homogenous fine recrystallized structure having a wire-drawn matrix structure of the order of several μm. By adding solution treatment and quenching treatment before the refining heat treatment, the amount of dissolved Fe is increased to 0.052%, which is the solid solubility limit at 650 ° C., followed by wire drawing and subsequent refining heat treatment. By making the crystal grain size finer and highly purifying Al, dynamic recrystallization occurs at the time of bonding to avoid chip damage. Further, in Patent Document 5, Fe is 0.01 to 0.2% by mass, Si is 1 to 20% by mass, and the balance is Al with a purity of 99.997% by mass or more, and the solid solution amount of Fe is 0.997% by mass. 01 to 0.06%, the amount of precipitated Fe is 7 times or less of the solid solution amount of Fe, and the fine structure has an average crystal grain size of 6 to 12 μm. The recrystallization temperature is stabilized by suppressing the Fe content and maintaining the ratio between the Fe precipitation amount and the Fe solid solution amount within a certain range, and the strength is improved by adding a small amount of Si. , and as a result, the thermal shock test results are stabilized.

JP-A-2002-314038 JP-A-8-8288 JP 2008-311383 A JP 2013-258324 A JP 2014-129578 A

Even in a semiconductor device using an Al bonding wire containing Fe as described in Patent Documents 2 to 5, the bonding reliability of the bonding wire bonding portion is sufficiently obtained in a high temperature state in which the semiconductor device is operated. There was something I couldn't do.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an Al bonding wire that provides sufficient bonding reliability at a bonding wire bonding portion in a high-temperature state in which a semiconductor device using the Al bonding wire is operated.

That is, the gist of the present invention is as follows.
[1] Containing 0.02 to 1% by mass of Fe, further containing 0.05 to 0.5% in total of at least one or more of Mn and Cr, and the balance being Al and inevitable impurities, An Al bonding wire characterized by having a total solid solution amount of Fe, Mn and Cr of 0.01 to 1%.
[2] The Al bonding wire according to [1], wherein the average crystal grain size in a cross section perpendicular to the longitudinal direction of the wire is 0.1 to 50 μm.
[3] In a cross section perpendicular to the longitudinal direction of the wire, the area ratio of crystals having an angle difference of 15° or less between the <111> orientation of the crystal and the longitudinal direction of the wire is 30 to 90% [1] Or the Al bonding wire according to [2].
[4] The Al bonding wire according to any one of [1] to [3], which has a Vickers hardness in the range of Hv 20 to 40.
[5] The Al bonding wire according to any one of [1] to [4], which has a wire diameter of 50 to 600 μm.

The Al bonding wire of the present invention contains, in mass%, 0.02 to 1% Fe, further contains at least one or more of Mn and Cr in a total of 0.05 to 0.5%, and the balance is Al and Composed of unavoidable impurities, the total solid solution amount of Fe, Mn, and Cr is 0.01 to 1%, so that the bonding of the bonding wire at the high temperature state in which the semiconductor device using the Al bonding wire is operated. Sufficient reliability is obtained.

In the inventions described in Patent Documents 4 and 5, Fe is contained in the Al bonding wire, and the solid solution Fe amount in the wire is increased by solution heat treatment during wire production and subsequent rapid cooling treatment. As the strength of the wire increases, the recrystallization temperature rises, and it is attempted to prevent the progression of recrystallization during use at high temperatures to maintain the wire strength.

However, even in a semiconductor device using an Al bonding wire containing Fe to increase the solid-solution Fe amount, if the semiconductor device is operated at a high temperature for a long time, the bonding strength of the bonding wire decreases. It was found that the phenomenon that the joint reliability was not sufficiently obtained was observed. Observation of the cross section of the bonding wire of the semiconductor device after long-term operation at high temperature shows that the crystal grain size of the wire has increased compared to that during bonding. It was presumed that the strength decreased and the reliability of the joint decreased.

In contrast, in the present invention, the aluminum bonding wire contains a predetermined amount of one or both of Mn and Cr in addition to Fe, so that Fe, Mn, Cr The total solid solution amount of is 0.01 to 1%. As a result, the recrystallization temperature of the wire rises, and even when the semiconductor device is used continuously in a high-temperature environment for a long time, it is possible to sufficiently suppress the progress of recrystallization of the bonding wire and prevent deterioration of the strength of the wire. can. A detailed description will be given below.

A joint reliability evaluation test after high-temperature long-term history will be described.
The components of the bonding wires used were the Al bonding wire of the comparative example containing only 0.5% by mass of Fe, and the Al bonding wire of the present invention containing 0.5% of Fe and 0.5% of Mn. The wire diameter after wire drawing is 200 μm. In the middle of the wire drawing process, solution heat treatment and subsequent quenching treatment are performed to increase the solid solution amount of Fe and Mn, and the drawn wire is subjected to refining heat treatment to reduce the Vickers hardness of the bonding wire to Hv40 or less. adjusted to All of the wires had an average crystal grain size of about 10 μm.

The total amount (% by mass) of Fe, Mn, and Cr dissolved in the wire was evaluated by the residual resistance ratio (RRR). The residual resistance ratio is the ratio of the electrical resistance at room temperature (293K) to the electrical resistance at liquid helium temperature (4K), and the electrical resistance in the superconducting state changes depending on the amount of impurities, and the value reflects the amount of solid solution. Thus, the total amount (% by mass) of solid solution of Fe, Mn, and Cr in aluminum can be calculated. The Al bonding wire of the comparative example had a solid solution amount of Fe of 0.005 to 0.009%, whereas the Al bonding wire of the present invention had a total solid solution amount of Fe and Mn of 0.02 to 0. .94%.

In the semiconductor device, wedge bonding is used for both the first joint between the semiconductor chip and the bonding wire and the second joint between the external terminal and the bonding wire.

High-temperature long-term history was performed by a power cycle test. In the power cycle test, heating and cooling are repeated for the semiconductor device to which the Al bonding wire is bonded. Heating is performed for 2 seconds until the temperature of the bonding wire bonding portion in the semiconductor device reaches 140°C, and then cooling is performed for 5 seconds until the temperature of the bonding portion reaches 30°C. This heating/cooling cycle is repeated 200,000 times.

After the high-temperature long-term history, the joint shear strength of the first joint was measured to evaluate the joint reliability. As a result, for the Al bonding wire of the comparative example containing 0.5% by mass of Fe only, the bond shear strength was less than 50% compared to the initial value, and the reliability of the bond was insufficient. On the other hand, for the Al bonding wire of the present invention containing 0.5% Fe and 0.5% Mn, the bond shear strength is 90% or more compared to the initial value, and the reliability of the bond is sufficiently improved. was able to secure

After the high-temperature history for a long time, crystal observation of the cross section of the wire was performed, and it was found that the Al bonding wire of the present invention containing 0.5% Fe and 0.5% Mn maintained an average crystal grain size of 50 μm or less. On the other hand, the average grain size of the Al bonding wire of the comparative example containing 0.5% by mass of Fe alone exceeded 50 μm. The wire of the present invention, which contains both Fe and Mn and, as a result, has a total solid solution amount of Fe and Mn of 0.01% or more, has a high recrystallization temperature, and recrystallization proceeds even after high-temperature history for a long time. presumably did not. On the other hand, the wire of the comparative example, which contained only Fe and, as a result, had a solid-solution amount of Fe of less than 0.01%, had a low recrystallization temperature, and recrystallization progressed in a high-temperature long-term history. It is considered that the reliability of the joint could not be sufficiently ensured due to the decrease in strength.

The component composition of the bonding wire of the present invention will be described. % means % by mass.
<<0.02 to 1% of Fe>>
By containing 0.02% or more of Fe in the Al bonding wire, combined with the effect of compound addition with Mn, Cr, etc. described below, the solid solution strengthening effect of the wire due to the increase in the total solid solution amount of Fe, Mn, Cr, In addition, it is possible to exhibit the effect of preventing progress of recrystallization during high-temperature, long-time use of the semiconductor device. More preferably, Fe is 0.1% or more. More preferably 0.5% or more. On the other hand, if the Fe content exceeds 1%, the wire hardness becomes too high, causing chip cracks, deterioration of bondability, and deterioration of joint reliability, so the upper limit was made 1%. It is more preferable that Fe is 0.8% or less.

<<0.05 to 0.5% in total of at least one of Mn and Cr>>
By containing at least one of Mn and Cr in total of 0.05% or more, in combination with the effect of combined addition with Fe, the solid-solution strengthening effect due to the increase in the total solid-solution amount of Fe, Mn, and Cr in the wire and the effect of preventing progress of recrystallization during long-term use of the semiconductor device at high temperatures. Both Mn and Cr exhibit similar effects. More preferably, the total content of Mn and Cr is 0.1% or more. It is more preferable if it is 0.3% or more. On the other hand, if the total content of Mn and Cr exceeds 0.5%, the wire hardness becomes too high, causing chip cracks, deterioration in bondability, and deterioration in bond reliability. 5%. More preferably, the total content of Mn and Cr is 0.4% or less.

The remainder of the bonding wire consists of Al and unavoidable impurities. Si and Cu are mentioned as an unavoidable impurity element. The smaller the total content of unavoidable impurities, the smaller the variations in material properties can be suppressed, which is preferable. Favorable results can be obtained by using aluminum with a purity of 4N (Al: 99.99% or more) as the aluminum raw material for manufacturing the wire.

<<The total solid solution amount of Fe, Mn, and Cr is 0.01 to 1%>>
By setting the total solid solution amount of Fe, Mn, and Cr to 0.01% or more, the recrystallization temperature of the wire can be sufficiently raised. As a result, it is possible to exhibit the effect of preventing progress of recrystallization during long-term use of the semiconductor device at high temperatures. More preferably, the total amount of solid solution of Fe, Mn and Cr is 0.05% or more. More preferably 0.5% or more. On the other hand, if the total solid solution amount of Fe, Mn, and Cr exceeds 1%, the wire hardness becomes too high, causing chip cracks and deterioration of bondability, so the upper limit was made 1%. More preferably, the total solid solution amount of Fe, Mn, and Cr is 0.9% or less. It is more preferable if it is 0.8% or less. By subtracting the Fe solid solution amount from the Fe content, the amount of precipitated Fe can be calculated.

《Average grain size of wire》
In the present invention, the average crystal grain size in a cross section (C cross section) perpendicular to the wire longitudinal direction of the bonding wire is preferably 0.1 to 50 μm. As a method for measuring the average crystal grain size, the area of each crystal grain is obtained using a measurement method such as EBSD (Electron Back Scatter Diffraction Patterns), and the area of each crystal grain is converted to the area of a circle, and the average diameter is calculated. and If the average crystal grain size is 0.1 μm or more, recrystallization due to refining heat treatment during wire drawing is progressing moderately, and solution heat treatment is performed in the process of wire manufacturing to forcibly dissolve the components contained in the wire. Combined with this, the wire is softened, and it is possible to prevent the occurrence of chip cracking at the time of bonding and the deterioration of bondability of the joint. On the other hand, if the average crystal grain size exceeds 50 μm, it indicates that recrystallization of the wire has progressed too much, making it difficult to obtain sufficient strength. By performing a refining heat treatment in the wire drawing process, the average crystal grain size in the C cross section of the wire can be made 0.1 to 50 μm.

<<<111> orientation area ratio of wire>>
In the present invention, preferably, in a cross section (C cross section) perpendicular to the longitudinal direction of the bonding wire, the crystal area ratio (<111> orientation area ratio ) is 30 to 90%. EBSD can be used to measure the <111> orientation area ratio. The <111> azimuth area ratio can be calculated by using the analysis software attached to the apparatus with the cross section perpendicular to the longitudinal direction of the bonding wire as the inspection plane. If the <111> orientation area ratio is 90% or less, recrystallization due to refining heat treatment during wire drawing progresses appropriately, the wire softens, chip cracking occurs during bonding, and the bondability of the joint deteriorates. etc. can be prevented. On the other hand, if the <111> orientation area ratio is less than 30%, it indicates that recrystallization of the wire has progressed too much, making it difficult to obtain sufficient strength. By performing refining heat treatment in the wire drawing process, the <111> orientation area ratio in the cross section perpendicular to the wire longitudinal direction can be 30 to 90%.

《Vickers Hardness of Wire》
In the present invention, the Vickers hardness is preferably in the range of Hv 20 to 40 in a cross section (C cross section) perpendicular to the wire longitudinal direction of the bonding wire. By setting Hv to 40 or less, chip cracking does not occur during bonding, good bondability can be achieved, and loops can be easily formed for wiring to the semiconductor device. On the other hand, when the Vickers hardness decreases to less than Hv20, it indicates that the recrystallization of the wire has progressed too much, and the reliability of the joint may decrease. Therefore, the lower limit of the Vickers hardness is preferably Hv20. As described above, solution heat treatment and quenching treatment are performed in the wire manufacturing process to increase the total solid solution amount of Fe, Mn, and Cr, and further, a refining heat treatment is performed in the wire drawing process to reduce the Vickers of the wire. The hardness can be in the range of Hv20-40.

《Wire Diameter》
Preferably in the present invention, the bonding wire diameter is 50-600 μm. Wires with a thickness of 50 μm or more are generally used because large currents flow in power devices. .

<<Manufacturing method of bonding wire>>
The bonding wire of the present invention is manufactured by obtaining an Al alloy containing predetermined components and then subjecting it to conventional rolling and wire drawing.
In the middle of production, a solution heat treatment and a subsequent quenching treatment are performed. The solution heat treatment can be performed when the wire diameter is about 1 mm. The solution heat treatment conditions are preferably 570 to 640° C. for 1 to 3 hours. The rapid cooling treatment after the solution heat treatment is preferably rapid cooling in water. As a result, the total solid solution amount of Fe, Mn, and Cr can be within the range of the present invention in combination with the fact that Al contains one or both of Fe, Mn, and Cr within the range of the present invention. .
Refining heat treatment is performed during one or both of the wire drawing process and the wire drawing process. As the temperature and time of the refining heat treatment are increased, the average crystal grain size increases, the <111> orientation ratio decreases, and the Vickers hardness decreases. The refining heat treatment conditions can be selected so as to achieve a suitable average crystal grain size, <111> orientation ratio, and Vickers hardness within the heat treatment temperature range of 250 to 350° C. and the heat treatment time range of 2 to 4 hours. .

Aluminum with a purity of 99.99% by mass (4N) and Fe, Mn, and Cr with a purity of 99.9% by mass or more were melted as raw materials to obtain an Al alloy having the composition shown in Table 1. This alloy was used as an ingot, and the ingot was subjected to groove roll rolling and wire drawing. When the wire diameter was 800 μm, solution heat treatment was performed at (temperature, time) 620° C. for 3 hours and then cooled. There were two types of cooling conditions: rapid cooling (water cooling) and slow cooling (air cooling). Thereafter, die wire drawing was performed with a final wire diameter of 200 μm, and after the wire drawing was completed, refining heat treatment was performed (temperature, time) at 270° C. for 10 seconds.

The Fe, Mn, and Cr contents in the wire were analyzed using ICP (luminescence spectroscopy). In addition, the total solid solution amount of Fe, Mn, and Cr in the wire (% by mass) was evaluated by the residual resistance ratio (RRR).

Using this wire, the average crystal grain size in the cross section perpendicular to the longitudinal direction of the wire, the area ratio of the crystal in which the angle difference between the crystal <111> orientation and the wire longitudinal direction is within 15 ° (<111> orientation area ratio) , the Vickers hardness was measured.
The average crystal grain size was measured by measuring the area of each crystal grain using EBSD and averaging the diameter when the area of each crystal grain was regarded as a circle.
The <111> orientation area ratio was measured by EBSP in a cross section perpendicular to the longitudinal direction of the bonding wire, and the <111> orientation area ratio was calculated using analysis software attached to the apparatus.
The Vickers hardness was measured using the hardness of the C section, and the hardness was measured at the center position in the radial direction of the C section.

In the semiconductor device, the semiconductor chip electrodes were made of Al--Cu, and the external terminals were made of Ag. Wedge bonding was used for both the first joint between the semiconductor chip electrode and the bonding wire and the second joint between the external terminal and the bonding wire.

The bondability of the bonding wire in the semiconductor device was determined based on the presence or absence of defective bonding (non-bonding) at the initial stage of the first bonding portion (before the high-temperature long-term history). Those which are joined are indicated by ◯, and those which are not joined are indicated by x in the "Joinability" column of Tables 1 and 2.

For evaluation of chip cracks in semiconductor devices, the metal on the pad surface was dissolved with acid, and the presence or absence of chip cracks under the pads was observed under a microscope for evaluation. The results are shown in Table 1, "chip crack" column, with ◯ indicating no cracks and x indicating those with cracks.

High-temperature long-term history was performed by a power cycle test. In the power cycle test, heating and cooling are repeated for the semiconductor device to which the Al bonding wire is bonded. Heating is performed for 2 seconds until the temperature of the bonding wire bonding portion in the semiconductor device reaches 140°C, and then cooling is performed for 5 seconds until the temperature of the bonding portion reaches 30°C. This heating/cooling cycle is repeated 200,000 times.

After a long time at high temperature, the joint shear strength of the first joint was measured to evaluate the reliability of the joint. Shear strength measurements were made as a comparison with the initial joint shear strength. 95% or more of the initial bonding strength was marked as ⊚, 90% or more was marked as ○, 70% or more was marked as △, and 50% or less was marked as ×.

Table 1 shows manufacturing conditions and manufacturing results. Mn and Cr are shown as "second components". In Table 1, numerical values for components outside the scope of the present invention and numerical values for evaluation results outside the preferred range of the present invention are underlined.

Example No. of the present invention in Table 1. 1 to 18 are examples of the present invention. Rapid cooling is performed after the solution treatment. The composition of the wire and the total solid solution amount of Fe, Mn, and Cr are within the range of the present invention, and the average grain size, <111> orientation area ratio, and Vickers hardness of the wire are all within the preferred range of the present invention. All the evaluation results of bondability and chip cracks were "Good". This is the result of containing the components specified in the present invention, performing solution heat treatment and quenching treatment to reduce the precipitated Fe/dissolved Fe ratio, and further performing moderate recrystallization by refining heat treatment.

Inventive Example No. In the evaluation of joint reliability after high-temperature long-term history of Nos. 1 to 18, all were "○" or "⊚". As a result of containing the components specified in the present invention and the total solid solution amount of Fe, Mn, and Cr, the solid solution strengthening of the wire is achieved, the recrystallization temperature is increased, and recrystallization in high temperature and long time history is improved. This is because it hinders progress. In particular, invention example No. For Nos. 7 to 12, the Fe content was within the preferred range of the present invention, and all of the joint reliability evaluation results were "⊚."

Comparative Example No. in Table 1. 1 to 13 are comparative examples. The cooling conditions after the solution treatment are rapid cooling in Comparative Examples 1 to 10 and slow cooling in Comparative Examples 11 to 13.
Comparative example no. 1 to 3, the Fe content is less than the lower limit of the present invention, Comparative Example No. Further, Comparative Example No. 1 has a total content of Mn and Cr less than the lower limit of the present invention. In No. 3, the total content of Mn and Cr exceeds the upper limit of the present invention. In both cases, the reliability evaluation result was "x". In addition, when the internal quality of the wire after high temperature history for a long period of time was evaluated, comparative example No. All of Nos. 1 to 3 had an average crystal grain size exceeding 50 μm. It is presumed that Fe in the wire was insufficient, the recrystallization temperature did not rise sufficiently, and recrystallization proceeded excessively in the high-temperature long-term history.

Comparative example no. In Nos. 4 and 5, the total content of Mn and Cr was less than the lower limit of the present invention, and the total solid solution amount of Fe, Mn and Cr was less than 0.01%. In both cases, the reliability evaluation result was "x". When the wire internal quality was evaluated after high-temperature history for a long time, the average crystal grain size exceeded 50 μm in all cases. The total content of Mn and Cr in the wire is insufficient. It is presumed that this is because recrystallization excessively progressed in the high-temperature long-term history without sufficient increase.

Comparative example no. In No. 6, the total content of Mn and Cr exceeds the upper limit of the present invention. As a result, the Vickers hardness of the wire was outside the upper limit of the preferred range. In addition, both the bondability after bonding and the chip cracks were "x", and the reliability evaluation result was also "x".

Comparative example no. 7 to 10, the Fe content exceeds the upper limit of the present invention. Furthermore, Comparative Example No. 7 and 8, the total content of Mn and Cr is less than the lower limit of the present invention; In No. 10, the total content of Mn and Cr exceeds the upper limit of the present invention. Comparative example no. In all of Nos. 7 to 10, since the Fe content exceeds the upper limit of the present invention, the Vickers hardness is outside the preferred upper limit of the present invention. Comparative example no. In 10, the total content of Mn and Cr exceeds the upper limit, so even if forced solid solution is not completely dissolved, it precipitates, and the average crystal grain size is less than the preferred lower limit of the present invention, and the <111> orientation area ratio. is outside the preferred upper limit of the present invention. As a result, Comparative Example No. In all of Nos. 7 to 10, both the bondability and chip cracks were evaluated as "x", and the joint reliability evaluation result after high-temperature long-term history was also evaluated as "x".

Comparative example no. In Nos. 11 to 13, the composition range is within the range of the present invention, but the cooling condition after the solution treatment at the time of production is "slow cooling", and as a result, the solid solution of Fe and Mn in the wire does not sufficiently proceed. However, the total solid solution amount of Fe, Mn, and Cr was less than 0.01%. The wire hardness was also below the lower limit of the preferred range. In both cases, the reliability evaluation result was "x". Moreover, when the internal quality of the wire after high-temperature history for a long time was evaluated, the average crystal grain size exceeded 50 μm in all cases. It is presumed that the total solid solution amount of Fe, Mn, and Cr could not be 0.01% or more, so the recrystallization temperature did not rise sufficiently, and recrystallization proceeded excessively in the high-temperature long-term history. be.

Claims (5)

In mass%, it contains 0.02 to 1% Fe, further contains 0.05 to 0.5% in total of at least one of Mn and Cr, and the balance is Al and inevitable impurities, Fe and Mn , and a total amount of solid solution of Cr is 0.01 to 1%. 2. The Al bonding wire according to claim 1, wherein the average crystal grain size in a cross section perpendicular to the longitudinal direction of the wire is 0.1 to 50 μm. Claim 1 or claim 1, characterized in that, in a cross section perpendicular to the longitudinal direction of the wire, the area ratio of crystals in which the angle difference between the crystal <111> orientation and the longitudinal direction of the wire is within 15° is 30 to 90%. 3. Al bonding wire according to 2. The Al bonding wire according to any one of claims 1 to 3, characterized in that the Vickers hardness is in the range of Hv20-40. Al bonding wire according to any one of claims 1 to 4, characterized in that the wire diameter is 50-600 µm.