JP2768021B2 - Bonding wire for semiconductor device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding wire for a semiconductor device used for connecting a chip electrode of a semiconductor element and an external lead, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As is well known, in assembling a semiconductor device in which an IC chip (semiconductor element) is incorporated, as a thin metal wire (bonding wire) for connecting the semiconductor element and an external lead, a gold wire, an aluminum wire, Alternatively, a copper wire is used in part. Among these bonding wires, gold wires have been used for the longest time, and in terms of excellent corrosion resistance, the amount of bonding wires for semiconductor devices made of gold or gold alloy is much larger than others.

Conventionally, as shown in FIG. 2, such a bonding wire 1 has a thread-wound bonding spool 2.
Is supported in a single-wound state around the body, and is unwound from its end to be supplied to the joint between the semiconductor element and the external lead.

However, the winding amount of such conventionally used single-layer bonding wire is generally limited to 100 to 200 m.
And a multi-layer bonding wire wound in a cross-winding manner as shown in FIG.
It is getting longer to 0m.

[0005]

However, in such a multi-layered bonding wire cross-wound,
When the thin wire is unwound, it is rubbed against the inner thin wire, and this friction causes the wire to be damaged or unnecessary tension to be generated at the time of bonding, thus causing a loop abnormality or disconnection.

In order to solve such a problem, the winding method has been adjusted. However, when an oxide film is not formed on the surface of a fine wire such as a bonding wire made of gold or a gold alloy, a multilayer winding is performed. Metal bonding easily progressed between the thin wires, and it was difficult to solve the above problem only by adjusting the winding method.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a bonding wire for a semiconductor device according to the first aspect of the present invention contains organic carbon on the surface of a thin wire made of gold or a gold alloy. Surfactant with an average film thickness of 10
By coating at 5000 ° C and annealing at 200 to 700 ° C, more preferably at 300 to 650 ° C, the average film thickness is 5
The film is characterized by being coated with a residual film of the above-mentioned surfactant of up to 1000 °.

According to a second aspect of the present invention, there is provided a method of manufacturing a bonding wire for a semiconductor device, wherein the surface of a fine wire made of gold or a gold alloy is coated with a surfactant containing organic carbon having an average film thickness of 10 to 5 mm.
The thin wire is annealed at 200 to 700 ° C., more preferably at 300 to 650 ° C.
Forming a residual coating of the surfactant of 1000 °.

Further, the bonding wire for a semiconductor device according to the third aspect is the bonding wire for a semiconductor device according to the first aspect, wherein a surface of the fine wire on which the residual film is formed is coated with a second surfactant containing organic carbon. Then, a film having an average film thickness of 10 to 5000 ° composed of the second surfactant and the remaining film was formed.

Further, according to a fourth aspect of the present invention, there is provided the method of manufacturing a bonding wire for a semiconductor device according to the first aspect, wherein the fine wire on which the residual film is formed contains organic carbon. Second
Of the second surfactant and the remaining film to form a film having an average film thickness of 10 to 5000 °.

According to a fifth aspect of the present invention, there is provided a bonding wire for a semiconductor device and a method of manufacturing the same, wherein the surfactant comprises at least one of a fatty acid ester, polyethylene glycol, and an alkylamine.

[0012]

The inventors of the present invention have conducted intensive studies on the surface properties of gold and gold alloys in order to solve the above-mentioned problems, and have obtained the following findings.

That is, when the surface of a fine wire made of gold or a gold alloy is coated with a surfactant containing organic carbon and annealed by passing through a tubular heat treatment furnace, the treatment temperature is generally 700 ° C.
In the following, even after annealing, a small amount of the surfactant remains and adheres strongly to the fine wire surface to form a residual film. This residual film does not peel off even by contact of a bonding wire in the bonding process of the semiconductor device,
The bonding between the bonding wires is suppressed, and the thin wires themselves are protected and strengthened.

By increasing the thickness of the surfactant before the heat treatment or by using a mixture of two or more surfactants, the thickness of the remaining film is increased and the adhesion to the fine wire surface is increased. Will be even stronger.

In addition, the fine wire made of gold or gold alloy is
When the second surfactant is coated via such a heat-treated residual film, the components of the second surfactant are bonded to the residual film, whereby the second surfactant and the residual film are separated from each other. As a result, the second surfactant is firmly fixed to the surface of the fine wire of gold or gold alloy.

Therefore, like the bonding wire for a semiconductor device and the method of manufacturing the same according to the third and fourth aspects, a surfactant containing organic carbon is coated before heat treatment, and after the heat treatment, a second surfactant containing organic carbon is coated. When the surface active agent is coated, the remaining film formed on the surface of the fine wire exerts an undercoating effect to form a very strong organic carbon film. As a result, the intermetallic bonding of the wires is more effectively suppressed, and the fine wires themselves are more strongly protected from friction between the bonding wires when the wires are unwound.

Here, in the bonding wire for a semiconductor device and the method for manufacturing the same according to the first and second aspects, if the average thickness of the surfactant before the heat treatment is less than 10 °, the average thickness of the remaining film after the heat treatment is 5 °. There is a possibility that the wire becomes thinner, and there is a danger that the friction between the metal at the time of bonding and bonding at the time of bonding cannot be suppressed. On the other hand, if the average thickness of the surfactant before the heat treatment exceeds 5000 °, the average thickness of the remaining film exceeds 1000 °, and a stitch bond failure or the like may occur during bonding.

Further, in the bonding wire for a semiconductor device and the method of manufacturing the same according to the third and fourth aspects,
The average film thickness of the film consisting of the surfactant and the remaining film is 1
The reason for setting the thickness to 0 to 5000 ° is that the base of the remaining film having an average thickness of 5 to 1000 ° has already been formed by the heat treatment. When the average thickness of the film is less than 10 °, the effect of suppressing the intermetallic bond is remarkable. Weakened, conversely, average film thickness of 5
If it exceeds 000 mm, it may cause a bonding trouble such as a stitch bond failure.

In the present invention, a surfactant coated,
Although the subsequent heat treatment temperature (annealing temperature) was set to 200 to 700 ° C., it is desirable to set the heat treatment temperature to 300 to 650 ° C. in order to more effectively fix the residual coating on the fine wire surface.

[0020]

Embodiments of the present invention will be described below.

A thin wire made of gold having a wire diameter of 25 μm is coated with a fatty acid ester which is a surfactant containing organic carbon at an average film thickness of 200 ° and 4500 °, and is put into a tubular heat treatment furnace maintained at 450 ° C. at a speed of 35 m / min. And annealed to form a residual film having an average film thickness of 50 ° and 900 °. These are referred to as Example 1 and Example 2, respectively.

The bonding wires for semiconductor devices of Examples 1 and 2 are coated with an alkylamine as a second surfactant containing organic carbon after the annealing.
A bonding wire for a semiconductor device on which a film having an average film thickness of 200 ° and 1000 ° composed of the second surfactant and the remaining film was formed was manufactured. These are referred to as Example 3 and Example 4, respectively.

Further, the surface of the fine wire made of gold having a wire diameter of 25 μm was coated with the above-mentioned fatty acid ester of a surfactant to form a coating having an average film thickness of 100 ° C., and was placed in a tubular heat treatment furnace maintained at 450 ° C. at 35 m / min. Anneal by inserting, average film thickness 3
A bonding wire for a semiconductor device on which a 0 ° residual film was formed was manufactured. Then, this was coated with the second surfactant alkylamine to form a coating having an average film thickness of 150 ° composed of the second surfactant and the remaining coating.
This is Example 5.

On the other hand, for comparison, a film having an average film thickness of 12,000 ° was formed from a bonding wire for a semiconductor device having a wire diameter of 25 μm, which was not coated with a surfactant at all, and the surfactant fatty acid ester, followed by annealing. An average film thickness of 7000 coated with the second surfactant alkylamine and comprising the remaining coating and the second surfactant.
A bonding wire for a semiconductor device on which the film of Å was formed was manufactured. These were compared with Comparative Example 1 and Comparative Example 2, respectively.
And

Here, regarding the unwinding property of the wire, these Examples and Comparative Examples were wound around a bonding spool and kept at 80 ° C. for 10 hours, and then unwrapped as shown in FIG. 1 as an accelerated storage test. A test was conducted to check for abnormalities. In FIG. 1, reference numeral 1 denotes a bonding wire, and reference numeral 2 denotes a cross section of a bonding spool body.

Further, after actually bonding the semiconductor device according to these examples and comparative examples, a bonding test was performed to check for stitch bond defects or the like.

Table 1 shows the results of the unwinding test and the bonding test.

[0028]

[Table 1]

Regarding the unwinding property, when the unwinding is performed normally, the bonding wire 1 is unwound along a vertically downward tangent of the bonding spool 2 as shown by a solid line in FIG. . However, when an abnormality occurs in the unwinding due to the connection or friction with the inner bonding wire, the unwinding is not performed along the tangent as shown by the broken line in FIG. 1, which hinders the supply of the bonding wire. Sometimes.

As can be seen from Table 1, Examples 1 to 5
In the bonding wire for a semiconductor device of Comparative Example 2, such an unwinding abnormality was not recognized, but in the bonding wire of Comparative Example 1, an unwinding abnormality occurred. In the bonding test, no abnormality was observed in Examples 1 to 5, whereas occurrence of abnormality was confirmed in Comparative Examples 1 and 2.

Also, the bonding wire of the present invention was manufactured using the gold alloy for the fine wire and the unwinding test and the bonding test were performed in the same manner as in the above embodiment. I was able to.

As described above, in the bonding wire for a semiconductor device according to the present invention, the intermetallic bond between the wires is suppressed by the residual film or the film comprising the residual film and the second surfactant. Can be stably unwound, and accordingly, a stable supply of bonding wires can be achieved. In addition, since the thin wire itself made of gold or a gold alloy is protected and strengthened by these coatings, it is possible to prevent a situation in which the bonding wire is disconnected due to tension caused by friction at the time of unwinding. It is also possible to suppress occurrence of bonding troubles such as stitch bond failure.

Further, in Examples 3 and 4 of this embodiment, an alkylamine was used as the second surfactant. Here, the alkylamine is lipophilic and is usually made of gold or gold alloy. It is known that it is difficult to adhere to the surface of the film. However, in the present invention, even such a lipophilic surfactant can be firmly fixed to the surface of these fine wires by interposing a residual coating between the fine wires made of gold or a gold alloy. is there. Thus, it is possible to further improve the above-described effects.

As described above, in Examples 3 and 4, a lipophilic alkylamine was used as the second surfactant. However, the present invention is not limited to this. And a hydrophilic surfactant such as polyethylene glycol may be used.

[0035]

As described above, according to the present invention, a fine wire made of gold or a gold alloy is coated with a surfactant containing organic carbon and annealed at a relatively low temperature, whereby the surface of the fine wire is formed. The residual film of the surfactant is fixed.
Then, since the remaining film suppresses the intermetallic bonding of the bonding wires, the unwinding property is improved, and stable supply can be performed. In addition, since the thin wire itself is protected and strengthened by the remaining coating, the thin wire may be damaged by the friction between the bonding wires during unwinding, or the bonding wire may be broken by the tension due to this friction. It is possible to prevent it before it happens.

When such a bonding wire for a semiconductor device is further coated with a second surfactant containing organic carbon, the remaining film strongly adhered to the fine wire surface is further coated with the second surfactant. Is strongly coated. And, by the coating comprising the second surfactant and the remaining coating, the intermetallic bonding between the bonding wires is more effectively suppressed, so that the unwinding property from the bonding spool is improved and the stability is improved. Supply can be made. Further, since the thin wire itself is more strongly protected by the coating, it is possible to more effectively prevent bonding trouble such as loss and disconnection of the bonding wire due to friction and tension at the time of unwinding, and defective stitch bonding. Become.

[Brief description of the drawings]

FIG. 1 is a view showing a state of an unwinding test according to an example of the present invention and a comparative example.

FIG. 2 is a view showing a bonding wire wound around a bonding spool.

FIG. 3 is a view showing a bonding wire wound around a bonding spool in a multi-layer manner by cross winding;

[Explanation of symbols]

 1 Bonding wire 2 Bonding spool

Continuation of the front page (56) References JP-A-4-363036 (JP, A) JP-A-59-167044 (JP, A) JP-A-64-11336 (JP, A) JP-A-62-139217 (JP) JP-A-2-94534 (JP, A) JP-A-1-200514 (JP, A) JP-A-3-165044 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB (Name) H01L 21/60 301

Claims (5)

(57) [Claims] 1. A thin wire made of gold or a gold alloy,
Surfactant containing organic carbon with an average film thickness of 10 to 500
A bonding wire for a semiconductor device, wherein the bonding wire for a semiconductor device is coated with a residual film of the surfactant having an average film thickness of 5 to 1000 ° formed by coating at 0 ° and annealing at 200 to 700 ° C. 2. The surface of a fine wire made of gold or a gold alloy,
Surfactant containing organic carbon with an average film thickness of 10 to 500
This thin wire is annealed at 200 to 700 ° C.
A method for manufacturing a bonding wire for a semiconductor device, comprising forming a residual coating of the surfactant at 1000 °. 3. The surface of the thin wire on which the residual film is formed is coated with a second surfactant containing organic carbon, and the average film thickness of the second surfactant and the residual film is 10 to 10. 2. The bonding wire for a semiconductor device according to claim 1, wherein a coating of 5000 ° is formed. 4. The surface of the fine wire on which the residual film is formed is coated with a second surfactant containing organic carbon, and the average film thickness of the second surfactant and the residual film is 1
3. The method for manufacturing a bonding wire for a semiconductor device according to claim 2, wherein a film of 0 to 5000 [deg.] Is formed. 5. The bonding wire for a semiconductor device according to claim 1, wherein the surfactant comprises at least one of a fatty acid ester, polyethylene glycol, and an alkylamine. Manufacturing method of bonding wire.