TWI838488B - Al bonding wire - Google Patents

Abstract

The present invention provides an Al bonding wire that can fully obtain the bonding reliability of the bonding portion of the bonding wire under the high temperature state in which the semiconductor device using the Al bonding wire is operated. The Al bonding wire contains 0.01 to 1% of Sc and further contains at least one of Y, La, Ce, Pr, and Nd in a total of 0.01 to 0.1%. Thereby, the recrystallization temperature of the metal wire rises, and even when the semiconductor device is continuously used in a high temperature environment, the recrystallization of the bonding wire can be suppressed, and the strength of the metal wire can be prevented from decreasing, so that the reliability of the bonding portion after a long period of high temperature history can be fully ensured.

Description

Al bonding wire

The present invention relates to an Al bonding wire.

In semiconductor devices, electrodes formed on semiconductor elements are connected to electrodes on lead frames or substrates by bonding wires. Gold (Au) or copper (Cu) is used as the material for bonding wires in integrated circuit semiconductor devices such as super LSI (Large Scale Integration), while aluminum (Al) is mainly used in power semiconductor devices. For example, Patent Document 1 shows that 300 μm bonding wires are used in power semiconductor modules. In a power semiconductor device using Al bonding wire, wedge bonding is used as a bonding method for connecting to an electrode on a semiconductor element and connecting to an electrode on a lead frame or a substrate.

Power semiconductor devices using Al bonding wires are mostly used in high-power devices such as air conditioners or solar power generation systems, and semiconductor devices for vehicles. In these semiconductor devices, the bonding parts of the Al bonding wires are exposed to high temperatures of 100 to 300°C. When using materials composed only of high-purity Al as Al bonding wires, the metal wires are easily softened in such temperature environments, making them difficult to use in high-temperature environments.

If an alloy containing Sc (hereinafter referred to as "Sc") in Al is used and Sc is precipitated in the form of Al ₃ Sc, the Al bonding wire can be strengthened. Patent document 2 discloses a bonding wire containing Al as a main component and 0.05 to 1.0% Sc. By precipitating Al ₃ Sc in the bonding wire, an optimal combination of electrical and mechanical properties can be obtained.

However, if a bonding wire with Al ₃ Sc precipitated therein is used to bond to an electrode of a semiconductor device, the metal wire has a high mechanical strength, which may cause the chip of the semiconductor device to crack, and thus cannot be put into practical use. In response to this, Patent Document 3 discloses an invention in which Sc is contained in the Al bonding wire, and Al ₃ Sc is prevented from precipitating in the bonding wire in the stage before bonding by a prior melting treatment, and Al ₃ Sc is precipitated by an aging heat treatment performed after bonding. Since Al ₃ Sc is not precipitated in the bonding stage, the metal wire softens, and the chip does not crack during bonding. On the other hand, since Al ₃ Sc is precipitated by the aging heat treatment performed after bonding, the strength of the metal wire is increased, and the metal wire can maintain sufficient strength even when the semiconductor device is used in a high temperature environment. [Prior art literature] [Patent literature]

[Patent Document 1] Japanese Patent Publication No. 2002-314038 [Patent Document 2] Japanese Patent Publication No. 2016-511529 [Patent Document 3] Japanese Patent Publication No. 2014-47417

[The problem the invention is trying to solve]

Even in a semiconductor device using an Al bonding wire containing Sc as described in Patent Document 3, it is sometimes impossible to obtain sufficient bonding reliability of the bonding portion of the bonding wire under the high temperature state of operating the semiconductor device.

The purpose of the present invention is to provide an Al bonding wire that can fully obtain the bonding reliability of the bonding portion of the bonding wire under the high temperature state of operating a semiconductor device using the Al bonding wire. [Technical means to solve the problem]

In Al bonding wire containing Sc, Al ₃ Sc is precipitated by aging heat treatment after bonding, thereby increasing the strength of the bonding wire as described in Patent Document 3. On the other hand, it is known that when a semiconductor device is continuously used in a high temperature environment, recrystallization of the Al bonding wire proceeds further, resulting in a decrease in the strength of the metal wire.

In this regard, it was clarified that by containing 0.01 to 1% of Sc in addition to Sc and further containing 0.01 to 0.1% in total of at least one of yttrium, yttrium, cerium, yttrium, and neodymium (hereinafter referred to as "Y, La, Ce, Pr, Nd"), the recrystallization temperature of the metal wire is increased, and even when the semiconductor device is continuously used in a high temperature environment, the recrystallization of the bonding wire can be suppressed, thereby preventing the strength of the metal wire from decreasing.

The present invention has been completed based on the above findings, and its main contents are as follows. [1] An Al bonding wire characterized by containing 0.01 to 1% of Sc in mass %, and further containing 0.01 to 0.1% of at least one of Y, La, Ce, Pr, and Nd in total, with the remainder containing Al and inevitable impurities. [2] The Al bonding wire as described in [1] above, wherein the average crystal grain size in a cross section perpendicular to the long side direction of the metal wire (hereinafter also referred to as "C cross section") is 0.1 to 50 μm. [3] The Al bonding wire as described in [1] or [2] above, wherein in a cross section perpendicular to the long side direction of the metal wire (C cross section), the area ratio of crystals in which the angle difference between the <111> orientation and the long side direction of the metal wire is within 15° is 30 to 90%. [4] The Al bonding wire as described in any one of [1] to [3] above, wherein the Vickers hardness is in the range of Hv20 to 40. [5] The Al bonding wire as described in any one of [1] to [4] above, wherein the metal wire diameter is 50 to 600 μm. [Effect of the Invention]

The present invention contains 0.01 to 1% Sc in the Al bonding wire and further contains a total of 0.01 to 0.1% of at least one of Y, La, Ce, Pr, and Nd, so that the recrystallization temperature of the metal wire is increased. Even when the semiconductor device is used continuously in a high temperature environment, the recrystallization of the bonding wire can be suppressed, and the strength of the metal wire can be prevented from decreasing. Therefore, the reliability of the bonding part after a long period of high temperature history can be fully ensured.

Regarding the bonding wire containing Sc in the Al bonding wire, as described in Patent Document 3, the Sc is forced to be dissolved in solid solution by the prior melting treatment, and Al ₃ Sc is not precipitated. Therefore, the metal wire softens in the bonding stage, and the chip does not crack during bonding. Then, Al ₃ Sc is precipitated by the aging heat treatment after bonding, and as a result, the strength of the metal wire is increased, and the recrystallization temperature is increased, which can prevent the recrystallization from proceeding during use at high temperatures, thereby maintaining the strength of the metal wire.

However, as described above, it is clear that even for a semiconductor device having an Al bonding wire with Sc precipitated therein, if the semiconductor device is operated at a high temperature for a long time, the bonding strength of the bonding portion of the bonding wire will decrease, that is, the bonding reliability is not sufficiently obtained. If the cross section of the bonding wire of the semiconductor device after the long-term operation at a high temperature is observed, it is estimated that the crystal grain size of the metal wire is larger than that at the time of bonding, and the long-term operation at a high temperature further advances the recrystallization of the metal wire, thereby reducing the strength of the metal wire and reducing the reliability of the bonding portion.

In contrast, the present invention further contains 0.01 to 1% of Sc in addition to Sc, and at least one of Y, La, Ce, Pr, and Nd (hereinafter referred to as "Y, La, etc.") in total. This increases the recrystallization temperature of the metal wire, and even when the semiconductor device is used continuously for a long time in a high temperature environment, the recrystallization of the bonding wire can be fully suppressed, and the strength of the metal wire can be prevented from decreasing. This is described in detail below.

The Al bonding wire of the present invention contains 0.01-1% Sc by mass%, and further contains 0.01-0.1% of at least one of Y, La, Ce, Pr, and Nd in total, and the remainder contains Al and inevitable impurities. The material having such a composition is subjected to wire drawing to produce a bonding wire with a specific wire diameter. In order to force Sc, Y, La, etc. to be dissolved in a solid solution before, during, or after the wire drawing process, it is preferred to perform a melt heat treatment. As the melt heat treatment conditions, it is preferably set to 570-640°C and 1-3 hours.

After the wire drawing process is completed and the above-mentioned melting heat treatment has been performed, a tempering heat treatment for softening the metal wire is performed in the subsequent stage. The tempering heat treatment can also be added in the middle of the wire drawing process. The crystalline structure of the metal wire is changed from the processed structure to the recrystallized structure by the tempering heat treatment. In this way, the crystalline structure becomes a recrystallized structure, so the softening of the metal wire can be achieved. As the tempering heat treatment conditions, it is preferably set to 250-300°C and 5-15 seconds. In this way, the crystalline structure can be made into a recrystallized structure without precipitating the solid solution Sc, Y, La, etc.

In the present invention, it is preferred that, as described above, by performing a melting treatment during the metal wire manufacturing process, Sc, Y, La, etc. are not precipitated in the metal wire. In the case where the melting heat treatment is not performed, the Vickers hardness of the metal wire becomes a hardness exceeding Hv40 due to the precipitation of Sc, Y, La, etc. in the metal wire. In contrast, the result of performing the melting heat treatment and the tempering heat treatment is that Sc, Y, La, etc. are forced to be solid-dissolved, and the crystal structure is made into a recrystallized structure, thereby softening the metal wire to a Vickers hardness of less than Hv40. By using the Al bonding wire of the present invention that has been softened in this way to bond semiconductor electrodes, chip cracking of the semiconductor electrode will not occur.

After the bonding is completed, the semiconductor device including the bonding wire is subjected to aging heat treatment in order to precipitate Sc, Y, La, etc. in the bonding wire. As a result of the aging heat treatment, Sc, Y, La, etc. in the bonding wire are precipitated. Sc is precipitated in the form of Al ₃ Sc, Y is precipitated in the form of Al ₃ Y, La is precipitated in the form of Al ₁₁ La ₃ , Ce is precipitated in the form of Al ₁₁ Ce ₃ , Pr is precipitated in the form of Al ₁₁ Pr ₃ , and Nd is precipitated in the form of Al ₁₁ Nd _3. These precipitates are formed in the metal wire, and as a result, the metal wire is precipitation strengthened and the strength of the metal wire is increased. As the aging heat treatment conditions, it is preferably set to 250 to 400°C and 30 to 60 minutes.

Just after the aging heat treatment and after the high temperature and long time history under not so strict conditions, the Al bonding wire containing only Sc and the Al bonding wire containing Sc and Y, La, etc. can achieve precipitation hardening of precipitates without causing excessive recrystallization, so the mechanical strength can be maintained, and the reliability of the joint between the bonding wire and the electrode of the semiconductor device is fully maintained. However, it is clear that when kept in a more strict environment, that is, at a higher temperature and for a longer time, the reliability of the joint of the Al bonding wire containing only Sc decreases. In contrast, it can be seen that if the Al bonding wire of the present invention contains Y, La, etc. in addition to Sc, the reliability of the joint is ensured even after being exposed to such a more strict environment.

The reliability evaluation test of the joint after high temperature and long time history is explained. The composition of the bonding wire used is Al bonding wire of the comparative example containing only 0.5 mass% of Sc, and Al bonding wire of the present invention containing 0.5% Sc and 0.1% Y. The wire diameter of the metal wire after wire drawing is 200 μm. During the wire drawing step, a melting heat treatment is performed to force Sc and Y to solid solution, and the metal wire after wire drawing is subjected to a tempering heat treatment to adjust the Vickers hardness of the bonding wire to below Hv40.

In a semiconductor device, a first bonding portion between a semiconductor chip and a bonding wire and a second bonding portion between an external terminal and the bonding wire are both wedge-type bonds.

The high temperature long time history is conducted by the dynamic cycle test. The dynamic cycle test is to repeatedly heat and cool the semiconductor device with Al bonding wire. The heating is carried out for 2 seconds until the temperature of the bonding part of the bonding wire in the semiconductor device reaches 140℃, and then it is cooled for 5 seconds until the temperature of the bonding part reaches 30℃. The above heating and cooling cycle is repeated 200,000 times.

After the high temperature long time history, the joint shear strength of the first joint was measured to evaluate the reliability of the joint. The result showed that the joint shear strength of the Al joint wire containing only 0.5 mass% of Sc was less than 50% of the initial strength, and the reliability of the joint was insufficient. In contrast, the Al joint wire of the present invention containing 0.5% Sc and 0.1% Y had a joint shear strength of more than 90% of the initial strength, which fully ensured the reliability of the joint.

The component composition of the bonding wire of the present invention is described. % represents mass %.

《0.01-1% Sc》 By containing 0.01% or more of Sc in the Al bonding wire, the precipitation strengthening effect of the metal wire and the prevention of recrystallization during long-term use at high temperatures of semiconductor devices can be exerted in combination with the composite addition effect of Y, La, etc. described below. Sc is preferably 0.1% or more, more preferably 0.3% or more, and more preferably 0.5% or more. On the other hand, if the Sc content exceeds 1%, the hardness of the metal wire becomes too high, which may cause chip cracks, poor bonding, and reduced reliability of the bonding part, so the upper limit is set to 1%. Sc is preferably 0.8% or less.

《At least one of Y, La, Ce, Pr, Nd in a total of 0.01-0.1%》 By containing at least one of Y, La, Ce, Pr, Nd (Y, La, etc.) in a total of 0.01% or more, the above-mentioned composite addition effect of Sc can be complemented to exert the precipitation strengthening effect of the metal wire and the effect of preventing recrystallization during high-temperature and long-term use of semiconductor devices. Y, La, Ce, Pr, and Nd all exert the same effect. The total content of Y, La, etc. is preferably 0.03% or more. Further preferably, it is 0.05% or more. On the other hand, if the total content of Y, La, etc. exceeds 0.1%, the hardness of the metal wire becomes too high, which will lead to chip cracks, poor bonding, and reduced reliability of the bonding part, so the upper limit is set to 0.1%. The total content of Y, La, etc. is more preferably 0.08% or less.

In the concentration analysis of Sc, Y, La, etc. in the bonding wire, an ICP (Inductively Coupled Plasma) emission spectrometer or an ICP mass spectrometer can be used. The content of Sc, Y, La, etc. shown in the present invention is based on the concentration measured by ICP emission spectrometer or ICP mass spectrometer. The remaining part of the bonding wire contains Al and inevitable impurities. As inevitable impurity elements, Si, Fe, and Cu can be listed. The less the total content of inevitable impurities, the smaller the change in material properties can be suppressed, so it is better. By using aluminum with a purity of 4 N (Al: more than 99.99%) as the aluminum raw material when manufacturing the metal wire, better results can be obtained.

《Average crystal grain size of metal wire》 In the present invention, it is preferred that the average crystal grain size of the bonding wire in the cross section (C cross section) perpendicular to the long side direction of the metal wire is 0.1 to 50 μm. As a method for measuring the average crystal grain size, the area of each grain is obtained using a measurement method such as EBSD (Electron Back Scatter Diffraction Patterns), and the average diameter is set when the area of each grain is regarded as a circle. If the average crystal grain size is 0.1 μm or more, recrystallization is carried out appropriately by the tempering heat treatment during wire drawing, and the components contained in the metal wire are forced to be dissolved by the melting heat treatment during the metal wire manufacturing process, which complements the softening of the metal wire, which can prevent the chip from cracking during bonding and the decrease in bonding properties of the bonding part. On the other hand, if the average grain size exceeds 50 μm, it indicates that the recrystallization of the metal wire is excessively advanced, and even if precipitates are formed by aging heat treatment, it is difficult to obtain sufficient strength, and the reliability of the joint may be reduced. By performing tempering heat treatment during the wire drawing process, the average grain size in the C section of the metal wire can be made 0.1 to 50 μm.

《<111> Aspect Area Ratio of Wire》 In the present invention, it is preferred that the area ratio of crystals whose <111> orientation and the angle difference between the long side direction of the metal wire and the <111> orientation in the cross section (C cross section) perpendicular to the long side direction of the bonding wire is within 15° (hereinafter referred to as "<111> orientation area ratio") is 30-90%. EBSD can be used to measure the <111> orientation area ratio. The cross section perpendicular to the long side direction of the bonding wire is used as the inspection surface, and the <111> orientation area ratio can be calculated by using the analysis software attached to the device. In the process of calculating the <111> orientation area ratio, the parts where the crystal orientation cannot be measured or the parts where the reliability of the orientation analysis is low even if the orientation can be measured are excluded and calculated later. If the <111> aspect ratio is less than 90%, recrystallization proceeds moderately by the tempering heat treatment during wire drawing, and the melt heat treatment is performed during the process of wire manufacturing to force the components contained in the wire to be dissolved, which complements the softening of the wire, and can prevent chip cracking during bonding and the decrease in bonding properties of the bonded part. On the other hand, if the <111> aspect ratio is less than 30%, it shows that the recrystallization of the wire is excessively advanced, and even if precipitates are formed by aging heat treatment, it is difficult to obtain sufficient strength, and the reliability of the bonded part may be reduced. By performing the tempering heat treatment during the wire drawing process, the <111> aspect ratio in the cross section perpendicular to the long side direction of the wire can be set to 30 to 90%.

《Vickers hardness of metal wire》 In the present invention, it is preferred that the Vickers hardness of the bonding wire in the cross section (C cross section) perpendicular to the long side direction of the metal wire is in the range of Hv20 to 40. By setting it below Hv40, the chip will not crack during bonding and good bonding is achieved. In addition, a loop can be easily formed to wire the semiconductor device. On the other hand, if the Vickers hardness drops below Hv20, it indicates that the recrystallization of the metal wire is excessive, and even if precipitates are formed by aging heat treatment, it is difficult to obtain sufficient strength, and the reliability of the bonding part may be reduced. Therefore, the lower limit of the Vickers hardness is preferably set to Hv20. As described above, by performing a melt heat treatment during the metal wire manufacturing process to force the components contained in the metal wire to solid solution, and then performing a tempering heat treatment during the wire drawing process, the Vickers hardness of the metal wire can be made into the range of Hv20 to 40.

《Metal Wire Diameter》 In the present invention, the preferred bonding wire diameter is 50 to 600 μm. For power-based devices, since large currents flow through them, metal wires of 50 μm or more are usually used. However, if the wire is 600 μm or more, it becomes difficult to handle or the wire bonding machine is not compatible, so metal wires of 600 μm or less are used. [Example]

Aluminum with a purity of 99.99 mass% (4 N) and yttrium, rhodium, vanadium, ferromagnetic acid, and neodymium with a purity of 99.9 mass% or more were used as raw materials and melted to obtain Al alloys with the compositions shown in Tables 1 and 2. The alloy was made into ingots, the ingots were rolled with grooved rolls, and then wire drawn. At the stage where the metal wire diameter was 800 μm, it was melt-heat treated at 620°C for 3 hours and rapidly cooled in water. Thereafter, the final wire diameter was set to 200 μm for die wire drawing, and after the wire drawing process was completed, it was tempered at 270°C for 10 seconds.

The wire was used to measure the average crystal grain size, the area ratio of crystals with an angle difference of 15° or less between the <111> orientation and the long side of the wire (<111> orientation area ratio), and Vickers hardness in a cross section perpendicular to the long side of the wire (C cross section). The average crystal grain size was measured as follows: the area of each grain was calculated using the EBSD method, the area of each grain was converted into the area of a circle, and the diameter was averaged. The <111> orientation area ratio was measured by measuring the cross section perpendicular to the long side of the wire using EBSD, and the <111> orientation area ratio was calculated using the analysis software provided with the device. The Vickers hardness is measured using a micro Vickers hardness tester to measure the hardness at the center of the radius in the C section.

In the semiconductor device, the semiconductor chip electrode is Al-Cu, and the external terminal is Ag. The first bonding portion between the semiconductor chip electrode and the bonding wire, and the second bonding portion between the external terminal and the bonding wire are both wedge-shaped bonds.

After bonding, aging heat treatment was performed at 350°C for 45 minutes.

The bonding property of the bonding wire in the semiconductor device is judged based on the presence or absence of poor bonding (non-bonding) in the initial stage of the first bonding part (before the high temperature and long time history). In the "bonding property" column of Tables 1 and 2, the bonded ones are recorded as ○, and the non-bonded ones are recorded as ×. Regarding the evaluation of chip cracks in the semiconductor device, the metal on the pad surface is dissolved using acid, and the presence or absence of chip cracks under the pad is observed and evaluated using a microscope. In the "chip crack" column of Tables 1 and 2, no cracks are recorded as ○, and cracks are recorded as ×.

The high temperature long time history is conducted by the dynamic cycle test. The dynamic cycle test is to repeatedly heat and cool the semiconductor device with Al bonding wire. The heating is carried out for 2 seconds until the temperature of the bonding part of the bonding wire in the semiconductor device reaches 140℃, and then it is cooled for 5 seconds until the temperature of the bonding part reaches 30℃. The above heating and cooling cycle is repeated 200,000 times.

After the above high temperature and long time, the shear strength of the first joint is measured to evaluate the reliability of the joint. The shear strength is measured in the form of comparison with the initial shear strength of the joint. In the "Reliability Test" column of Tables 1 and 2, 95% or more of the initial joint strength is recorded as ◎, 90% or more but less than 95% is recorded as ○, 50% or more but less than 90% is recorded as △, and less than 50% is recorded as ×.

The manufacturing conditions and manufacturing results are shown in Tables 1 and 2. Y, La, Ce, Pr, and Nd (Y, La, etc.) are indicated as "second component". In Table 2, the values of component contents exceeding the range of the present invention and the values of evaluation results exceeding the preferred range of the present invention are underlined.

[Table 1] No. Ingredient content (mass%) Metal wire quality Performance Sc Ingredient 2 Crystalline grain size (μm) (111) Direction (%) Hardness Hv Gygosity Wafer cracks Reliability test Y La Ce Pr Nd Total Examples of the present invention 1 0.01 0.01 0 0 0 0 0.01 49 56 twenty four ○ ○ ○ 2 0.01 0 0.01 0 0 0 0.01 43 57 29 ○ ○ ○ 3 0.01 0 0 0.01 0 0 0.01 41 56 twenty four ○ ○ ○ 4 0.01 0 0 0 0.01 0 0.01 45 56 twenty four ○ ○ ○ 5 0.01 0 0 0 0 0.01 0.01 45 59 26 ○ ○ ○ 6 0.01 0.1 0 0 0 0 0.1 twenty four 63 29 ○ ○ ○ 7 0.01 0 0.1 0 0 0 0.1 twenty four 67 28 ○ ○ ○ 8 0.01 0 0 0.1 0 0 0.1 twenty one 66 32 ○ ○ ○ 9 0.01 0 0 0 0.1 0 0.1 twenty three 66 30 ○ ○ ○ 10 0.01 0 0 0 0 0.1 0.1 29 65 29 ○ ○ ○ 11 0.01 0.01 0.01 0 0 0 0.02 32 59 26 ○ ○ ○ 12 0.01 0.01 0 0.01 0 0 0.02 36 58 28 ○ ○ ○ 13 0.01 0.01 0 0 0.01 0 0.02 35 58 27 ○ ○ ○ 14 0.01 0.01 0 0 0 0.01 0.02 36 61 29 ○ ○ ○ 15 0.01 0.05 0.05 0 0 0 0.1 20 69 29 ○ ○ ○ 16 0.01 0.05 0 0.05 0 0 0.1 twenty two 65 27 ○ ○ ○ 17 0.01 0.05 0 0 0.05 0 0.1 twenty two 70 27 ○ ○ ○ 18 0.01 0.05 0 0 0 0.05 0.1 25 68 27 ○ ○ ○ 19 0.5 0.01 0 0 0 0 0.01 14 72 26 ○ ○ ◎ 20 0.5 0 0.01 0 0 0 0.01 10 71 29 ○ ○ ◎ twenty one 0.5 0 0 0.01 0 0 0.01 14 70 27 ○ ○ ◎ twenty two 0.5 0 0 0 0.01 0 0.01 12 71 28 ○ ○ ◎ twenty three 0.5 0 0 0 0 0.01 0.01 11 73 25 ○ ○ ◎ twenty four 0.5 0.1 0 0 0 0 0.1 9 69 33 ○ ○ ◎ 25 0.5 0 0.1 0 0 0 0.1 13 70 31 ○ ○ ◎ 26 0.5 0 0 0.1 0 0 0.1 10 69 31 ○ ○ ◎ 27 0.5 0 0 0 0.1 0 0.1 12 69 30 ○ ○ ◎ 28 0.5 0 0 0 0 0.1 0.1 4 73 33 ○ ○ ◎ 29 0.5 0.01 0.01 0 0 0 0.02 12 66 30 ○ ○ ◎ 30 0.5 0.01 0 0.01 0 0 0.02 4 71 33 ○ ○ ◎ 31 0.5 0.01 0 0 0.01 0 0.02 6 74 32 ○ ○ ◎ 32 0.5 0.01 0 0 0 0.01 0.02 9 70 32 ○ ○ ◎ 33 0.5 0.05 0.05 0 0 0 0.1 3 71 32 ○ ○ ◎ 34 0.5 0.05 0 0.05 0 0 0.1 11 71 32 ○ ○ ◎ 35 0.5 0.05 0 0 0.05 0 0.1 5 74 32 ○ ○ ◎ 36 0.5 0.05 0 0 0 0.05 0.1 2 77 34 ○ ○ ◎ 37 1.0 0.01 0 0 0 0 0.01 2.0 78 34 ○ ○ ○ 38 1.0 0 0.01 0 0 0 0.01 1.6 76 32 ○ ○ ○ 39 1.0 0 0 0.01 0 0 0.01 1.7 74 32 ○ ○ ○ 40 1.0 0 0 0 0.01 0 0.01 1.1 76 32 ○ ○ ○ 41 1.0 0 0 0 0 0.01 0.01 1.3 77 36 ○ ○ ○ 42 1.0 0.1 0 0 0 0 0.1 1.4 77 34 ○ ○ ○ 43 1.0 0 0.1 0 0 0 0.1 1.8 81 36 ○ ○ ○ 44 1.0 0 0 0.1 0 0 0.1 1.5 81 34 ○ ○ ○ 45 1.0 0 0 0 0.1 0 0.1 0.9 82 35 ○ ○ ○ 46 1.0 0 0 0 0 0.1 0.1 1.1 78 34 ○ ○ ○ 47 1.0 0.01 0.01 0 0 0 0.02 1.4 80 34 ○ ○ ○ 48 1.0 0.01 0 0.01 0 0 0.02 1.2 80 37 ○ ○ ○ 49 1.0 0.01 0 0 0.01 0 0.02 0.7 81 34 ○ ○ ○ 50 1.0 0.01 0 0 0 0.01 0.02 1.2 82 36 ○ ○ ○ 51 1.0 0.05 0.05 0 0 0 0.1 1.0 84 37 ○ ○ ○ 52 1.0 0.05 0 0.05 0 0 0.1 0.9 86 38 ○ ○ ○ 53 1.0 0.05 0 0 0.05 0 0.1 0.1 88 38 ○ ○ ○ 54 1.0 0.05 0 0 0 0.05 0.1 0.8 86 38 ○ ○ ○

[Table 2] No. Ingredient content (mass%) Metal wire quality Performance Sc Ingredient 2 Crystalline grain size (μm) (111) Direction (%) Hardness Hv Gygosity Wafer cracks Reliability test Y La Ce Pr Nd Total Comparison Example 1 0.005 0 0 0 0 0 0 59 63 twenty four ○ ○ × 2 0.005 0.05 0 0 0 0 0.05 49 56 27 ○ ○ × 3 0.005 0.15 0 0 0 0 0.15 43 55 41 × × × 4 0.5 0 0 0 0 0 0 9 68 29 ○ ○ △ 5 0.5 0.005 0 0 0 0 0.005 12 73 30 ○ ○ △ 6 0.5 0.15 0 0 0 0 0.15 9 71 43 × × × 7 1.5 0 0 0 0 0 0 0.6 86 45 × × × 8 1.5 0.005 0 0 0 0 0.005 0.7 84 41 × × × 9 1.5 ​ ​ 0.05 0 0 0 0 0.05 0.8 87 42 × × × 10 1.5 0.15 0 0 0 0 0.15 0.08 97 46 × × ×

The examples No. 1 to 54 of the present invention in Table 1 are examples of the present invention. The composition range of the metal wire is within the range of the present invention. In addition, the average grain size, <111> azimuth area ratio, and Vickers hardness of the metal wire are all within the preferred range of the present invention. The evaluation results of bonding and chip cracking are all "○". As a result, the composition specified in the present invention is contained, the contained elements are forced to be solid-dissolved by the melting heat treatment, and the appropriate recrystallization is carried out by the tempering heat treatment.

The reliability of the joints after high temperature and long time history of Examples No. 1 to 54 of the present invention are all "○" or "◎". The reason is that: the composition specified in the present invention is contained, and Sc, Y, La, etc. are precipitated by aging heat treatment after joining, resulting in precipitation strengthening of the metal wire, and the recrystallization temperature is increased, which prevents the recrystallization from proceeding during the high temperature and long time history. In particular, regarding Examples No. 19 to 36 of the present invention, the Sc content is within the preferred range of the present invention, and the joint reliability evaluation results are all "◎".

Comparative Examples No. 1 to 10 in Table 2 are comparative examples. In Comparative Examples No. 1 to 3, the Sc content did not reach the lower limit of the present invention, and the reliability evaluation results were all "×". In addition, the internal quality of the metal wire after high-temperature long-term history was evaluated, and the results showed that the average grain size of Comparative Examples No. 1 to 3 exceeded 50 μm. The reason is speculated to be: the Sc content in the metal wire is insufficient, even after aging heat treatment, the mechanical strength does not rise sufficiently, the recrystallization temperature does not rise sufficiently, and the recrystallization proceeds excessively during the high-temperature long-term history. Furthermore, the total content of Y, La, etc. in Comparative Example No. 1 did not reach the lower limit of the present invention. Furthermore, the total content of Y, La, etc. in Comparative Example No. 3 exceeded the upper limit of the present invention, and the bonding and chip cracks after bonding were "×".

In comparison examples No. 4 and 5, the total content of Y, La, etc. did not reach the lower limit of the present invention. The reliability evaluation results were all "△". In addition, the internal quality of the metal wire after high temperature and long time was evaluated, and the average grain size exceeded 50 μm. The reason is speculated to be: the total content of Y, La, etc. in the metal wire is insufficient, even after aging heat treatment, the mechanical strength does not rise sufficiently, the recrystallization temperature does not rise sufficiently, and the recrystallization proceeds excessively during the high temperature and long time. In comparison example No. 6, the total content of Y, La, etc. exceeds the upper limit of the present invention. As a result, the Vickers hardness of the metal wire is outside the preferred range. In addition, the bonding and chip cracks after bonding are "×", and the reliability evaluation result is "×".

In Comparative Examples No. 7 to 9, the Sc content exceeds the upper limit of the present invention. Furthermore, in Comparative Examples No. 7 and 8, the total content of Y, La, etc. does not reach the lower limit of the present invention, and in Comparative Example No. 10, the total content of Y, La, etc. exceeds the upper limit of the present invention. Since the Sc content of Comparative Examples No. 7 to 10 exceeds the upper limit of the present invention, the Vickers hardness exceeds the preferred upper limit of the present invention. If Sc exceeds the upper limit, even if it is forced to be dissolved, it will not be completely dissolved and precipitated, so the Vickers hardness exceeds the range. In Comparative Example No. 10, since the total content of Y, La, etc. also exceeds the upper limit, the average crystal grain size does not reach the preferred lower limit of the present invention, and the <111> orientation area ratio exceeds the preferred upper limit of the present invention. If Sc, Y, La, etc. exceed the upper limit, they will not be completely dissolved and precipitate, so the particle size becomes smaller and the <111> orientation becomes more. As a result, the bonding and chip cracking of Comparative Examples No. 7 to 10 are "×", and the bonding reliability evaluation result after high temperature long time history is also "×".

Claims (5)

An Al bonding wire, characterized in that: it contains 0.01-1% Sc by mass%, and further contains 0.01-0.1% of at least one of Y, La, Ce, Pr, and Nd in total, and the remainder contains Al and inevitable impurities, and the average crystal grain size in the cross section perpendicular to the long side direction of the metal wire is 0.1-50μm. An Al bonding wire, characterized in that: it contains 0.01-1% Sc by mass%, and further contains 0.01-0.1% of at least one of Y, La, Ce, Pr, and Nd in total, and the remainder contains Al and inevitable impurities, and in a cross section perpendicular to the long side direction of the metal wire, the area ratio of the crystals whose <111> orientation and the long side direction of the metal wire have an angle difference of less than 15° is 30-90%. For example, in the Al bonding wire of claim 1, in the cross section perpendicular to the long side direction of the metal wire, the area ratio of the crystals whose angle difference between the crystal <111> orientation and the long side direction of the metal wire is within 15° is 30~90%. For Al bonding wires in claim 1 or 2, the Vickers hardness is in the range of Hv20~40. For example, the Al bonding wire of claim 1 or 2, wherein the metal wire diameter is 50~600μm.