JPH02215140A - Fine gold alloy wire for semiconductor element and its bonding method - Google Patents

Abstract

PURPOSE:To contrive the improvement of a bonding efficiency by a method wherein a fine gold alloy wire, which is formed of a specified amount of specified metals with the remnant consisting of a specified metal and an inevitable impurity, is used. CONSTITUTION:When a semiconductor element is bonded to an Al electrode using a fine gold alloy wire, which contains one kind or more of Ni, Cu and Mn by 100 to 10000wt.ppm in total with the remnant consisting of Au and inevitable impurity, the formation of metallic compounds of Au and each of Ni, Cu and Mn is inhibited even at the time of use of the wire in a high- temperature environment, the circularity of the wire at the time of a ball-up is increased and a bonding efficiently is improved without increasing the thickness of an Au-Al compound.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to bonding wires and Ag alloy wiring coatings on Si chips when used at high temperatures in semiconductor devices used in automobile interior parts, etc. This invention relates to a thin gold alloy wire for semiconductor devices that is less likely to cause connection failures due to deterioration of the joints.

[Conventional technology]

In general, transistors, IC1s, L'Sr, and the like are known as semiconductor elements, and one of the methods for manufacturing rC is as shown below.

(a) First, as a lead frame material, the plate thickness is 20.1
A Cu alloy strip having a value of ~0.3+u+ is prepared.

(b) From this lead frame material, a lead frame matching the shape of the IC to be manufactured is formed by etching or press punching.

(C) Next, the Si chip is heat-bonded to a predetermined location on the lead frame using a conductive resin such as Ag paste, or Ag is formed in advance on one side of the Si chip and the lead frame.

Soldering or Au brazing is performed through a plating layer made of Au, Ag, Ni, Cu, or an alloy thereof.

(d) Ball bonding is performed over the Si chip and the lead frame using a fine Au wire having a diameter of 20 to 50 μm as a bonding wire to the electrode surface of a preformed Ag or the like.

(e) Subsequently, the portion of the lead frame to which the Si deep, bonding wire, and Si chip are attached is sealed with resin for the purpose of protecting them.

(``)Finally, the interconnected portions of the lead frame are cut out to form individual ICs.

A method consisting of the main steps (a) to ('') above is known.

[Problem to be solved by the invention]

Incidentally, recently, the environmental conditions in which devices using semiconductor elements are used have become more and more severe. There is a growing demand for use in such environments. However, in conventional gold wires, an intermetallic compound between Au and Al is formed at the joint with the σ electrode surface and becomes brittle, resulting in disconnection or poor connection due to the subsequent resin sealing process or vibrations during use. This has the disadvantage that the stability of the product is impaired.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a gold bonding wire that improves reliability under high temperatures. (a) Gold contains appropriate amounts of Ni, Cu, and Mn This has the effect of suppressing the formation of intermetallic compounds between Al and Au at high temperatures.

(b) In order to exhibit the above effect, the above metal element needs to be added to gold in an amount of at least 100 ppm by weight (hereinafter simply referred to as ppm). Also, the amount added is 10,000
If it exceeds ppm, when the tip of the gold wire is heated for bonding, the melted tip will not have a true spherical shape, resulting in poor bonding properties.

(c) Gold containing one or more of the above Ni, Cu, and Mn, and further Be, Ge, Ca, La, Si, Sn,
Ti, Zr.

By adding elements such as Mg and B, these elements enhance the effect of suppressing intermetallic compounds of Ni, Cu, and Mn.

(d) If a bonding wire containing 100 ppm or more of Ni, Cu, and Mn is heated in the air, these metals will oxidize and become impurities, reducing the sphericity of the ball, but the bonding process should be performed in an inert atmosphere. By doing so, the above problem can be avoided.

The findings shown in (a) to (d) above were obtained.

This invention has been made based on the above knowledge, and in the first claim, contains a total of 100 to 10()00 ppm of one or more of Ni, Cu, and Mn, and the balance is Provided is a gold alloy thin wire for a semiconductor device comprising Au and inevitable impurities, and furthermore, in the second claim, a total amount of one or more of Ni, Cu, and Mn is 100 to 10,000 pp.
Including m, Be, Ge, Ca, La, S i, S n, T
i, Zr.

1 to 50 of each of one or two or more of Mg and B
ppm, and contains 100 ppm or less in total, and the remainder is A
Provided is a thin gold alloy wire for a semiconductor device comprising u and unavoidable impurities; In this method, a voltage is applied between the wires to melt the tip of the thin gold alloy wire for semiconductor elements to form a ball, and the ball is pressed and bonded to the A12 electrode.

[Effect]

In the gold alloy fine wire for semiconductor devices of the present invention, the content of Ni, Cu, and Mn as alloy components is 100 to 1000.
0pp- was determined because its content is 10091111
If it is less than 1, as mentioned above, when putting the semiconductor device into practical use,
It has no effect of suppressing the formation of intermetallic compounds at the joint between the wire and the Aff electrode when used at high temperatures, and its content is 100o.

If it exceeds ppm, work hardening due to deformation of the ball formed at the tip of the wire during wire bonding will occur rapidly, resulting in a decrease in sphericity, making bonding difficult and reducing connection strength. This is based on the reason that

Moreover, in the second invention, Be, Ge, Ca
, La.

The content of S i, S n, T i, Z r, Mg, and B was set to 1 to 50 ppn+, respectively, because l ppm
If it is less than Ni or Cu.

There is no effect of promoting the action of Mn, and each 50 p
If it exceeds pm, the sphericity decreases as described above, and the wire drawing processability decreases, resulting in a decrease in efficiency when manufacturing the wire. Further, if each of the components is within the above range but the total amount exceeds 100 ppIl, similar problems will occur.

According to the gold alloy thin wire for semiconductor devices having such a composition, A
Even when the device is used in a high-temperature environment after bonding the electrode and the wire, N:, Cu, and Mn suppress the formation of intermetallic compounds between Aρ and Au at the bonding part, and B e , G e, Ca, L aS i, S
n, T i, Z r, Mg, B or the above Ni, Cu
, promotes the action of Mn and further enhances the inhibitory effect.

In addition, as in the method of the third claim, by performing the bonding step in an inert atmosphere, both the metal element and the auxiliary additive element are prevented from being oxidized, and the sphericity is improved when the ball is raised by heating. Forms a high ball, improves the efficiency of bonding work, and maintains bonding strength.

〔Example〕

EXAMPLES Hereinafter, the gold alloy fine wire of the present invention will be specifically explained with reference to Examples.

Molten gold alloys having the components shown in Table 1 are prepared and cast using the usual melting method, and then rolled to an appropriate cross-sectional dimension using a channel rolling mill, and then wire-drawn to form a diameter : A thin wire with a diameter of 25 μm. In addition, as a comparative material, a gold alloy thin wire having a composition outside the composition range of the present invention was manufactured in the same manner.

Next, using the various gold alloy thin wires obtained as a result,
Ball bonding was performed on the electrode surface having the ACC alloy wiring film using a bonding machine. In the bonding method, while holding the bonding wire, the tip of the wire is heated and melted by electric discharge in a nitrogen or gas atmosphere, and after balling up, it is pressed against the electrode surface.

Furthermore, semiconductor devices manufactured by connecting using the thin gold wires and bonding methods of Examples and Comparative Examples were heated at 250°C with N,
After being held in the atmosphere for 900 minutes, the strength of the joint between the gold alloy thin wire on the S1 chip and the 1lli electrode was measured by a shear test, and the samples were cut to investigate the A12-Au intermetallic compound at the joint. The layer thickness was measured.

In addition, a tensile test of the wire at room temperature was conducted. These results are summarized in Table 1.

From the results shown in this table, the gold alloy fine wires (No, 1 to 21) of the examples of the invention described in the first claim have a ball shape when poled up, and the formed Al2 -The maximum layer thickness of Au intermetallic compound is 4.9μ
m, and the bonding strength was 54 g or more, giving good results overall.

On the other hand, those that fall outside the scope of the ingredient limitations of the present invention (
No. 100 to 110) indicates that one or more of the above test items is defective.

Here, if the added amounts of Ni, Cu, and Mn are lower than the components of the present invention, the thickness of the Au-Al2 compound layer becomes large although the sphericity when balled up is high.

In the invention as set forth in claim 2, the tensile strength at room temperature is improved by about 3 g by adding a trace component to the above-mentioned components.

Next, in order to confirm the effect of the invention of claim 3, a gold base material having an impurity amount of 1Oppm or less was added with Ni in an amount falling within the range of claim I (No. 3
~g) and comparative example (No, 1.2, 9.10).

A sample of the third claim was bonded in a gas atmosphere, and a comparative example was prepared by bonding a sample with the same components in the air, and the same tests as above were conducted. The results are shown in Table 2.

According to this result, even if the components are included in the range of the components specified in the first and second claims of the present application, those that are poled up by heating in an oxidizing atmosphere will not produce oxides. Due to the change in properties due to this, it becomes distorted, resulting in a decrease in bonding strength. However, within the scope of the components defined in the first and second claims of the present application,
Moreover, only the ball-up ball in a non-oxidizing atmosphere showed good results in terms of ball sphericity, Au-Al compound layer thickness, and bonding strength.

〔Effect of the invention〕

As detailed above, the invention of the first claim of the present application is:
A total of one or more of Ni, Cu, and Mn
00-10,000 ppm, and the balance is Au and unavoidable impurities. Therefore, even if the wire is bonded to an electrode whose main component is Al and held at high temperature, these metal elements will not be absorbed. suppresses the formation of Al-Au intermetallic compounds and prevents a decrease in the strength of the bonded portion, and within this range of components, good bonding performance can be obtained without distorting the ball shape during pole-up.

The invention of the second claim also provides a total amount of 100 to 110,000 pp of one or more of Ni, Cu, and Mn.
Contains and further includes Be, Ge, Ca, La, Si.

1 to 50 ppm each of one or more of Sn, Ti, Zr, Mg, and B, totaling 100 ppa+
These elements include Ni, Cu,
It acts synergistically with Mn, further strengthening the above-mentioned intermetallic compound generation suppressing effect, and can also improve the tensile strength of the gold wire at room temperature.

The third aspect of the invention is to perform pole bonding in an inert atmosphere using the above-mentioned gold alloy thin wire for semiconductor devices, thereby preventing the oxidation of relatively easily oxidized components contained in the gold wire. The purpose is to prevent this from occurring, maintain the sphericity of the ball, allow smooth bonding, and fully exhibit the characteristics of the gold wire having the above-mentioned composition.

Claims (3)

[Claims] (1) Contains a total of 100 to 10,000 ppm by weight of one or more of Ni, Cu, and Mn, and the remainder is Au.
and unavoidable impurities. (2) Contains a total of 100 to 10,000 ppm by weight of one or more of Ni, Cu, and Mn, Be, Ge,
Contains one or more of Ca, La, Si, Sn, Ti, Zr, Mg, and B in an amount of 1 to 50 ppm by weight or less and a total of 100 ppm or less by weight, with the remainder consisting of Au and unavoidable impurities. Gold alloy fine wire for semiconductor devices. (3) Using the gold alloy thin wire for a semiconductor device according to claim 1 or 2, applying a voltage between the gold alloy thin wire for a semiconductor device and an electrode in an inert atmosphere, A method for joining thin gold alloy wires for semiconductor devices, which comprises melting the tip of the thin gold alloy wire for semiconductor devices to form a ball, and pressing the ball to an Al electrode to bond the ball.