JPH06333926A - Aluminum alloy wiring material - Google Patents

Abstract

PURPOSE:To provide an Al alloy wiring material which is used for the wiring of semiconductor integrated circuits, etc., and from which vapor-deposited films which are further reduced in such film defects as the hillock phenomena, bamboo phenomena, etc., can be obtained. CONSTITUTION:The wiring material is manufactured by mixing yttrium in Al, Al-Si alloy, Al-Co alloy, or Al-Si-Co alloy by <=5wt.%. Therefore, a high- quality wiring film from which the occurrence of film defects is extremely reduced, and, at the same time, which has high hardness and extremely low resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring material used for wiring semiconductor integrated circuits and the like.

[0002]

2. Description of the Related Art In wiring technology for semiconductor integrated circuits, etc., a vapor deposition film of aluminum or aluminum-based alloy is formed,
After etching it, heat treatment is performed to remove the internal strain and form an ohmic contact with the silicon substrate.

When such a wiring is formed of aluminum, there are drawbacks such that electromigration occurs due to energization to change the characteristics of the substrate, or the cross-sectional area of the wiring changes to easily break the wire. In addition, there is a drawback that a so-called hill-rock phenomenon occurs in which aluminum crystals are abnormally grown during the heat treatment and protrude to the film surface to significantly deteriorate the film characteristics.

In order to overcome the above drawbacks, an alloy containing a small amount of silicon, copper, or both added to aluminum is used. By using such an alloy, the occurrence of electromigration and hilllock phenomenon during energization can be suppressed to a considerable extent.
As the degree of integration of semiconductors further increases, the line width of wirings becomes narrower, and the occurrence of the above defects cannot be ignored even in such a vapor deposited film of aluminum alloy.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an aluminum alloy wiring material capable of obtaining a vapor deposition film for wiring with fewer defects such as electromigration and hilllock phenomenon. It is what Further, the present invention aims to deal with a defect called a bamboo phenomenon caused by the coarsening of the crystal generated after the heat treatment.

[0006]

DISCLOSURE OF THE INVENTION The present invention is an aluminum alloy wiring containing 5% by weight or less of yttrium in aluminum, an alloy of aluminum and silicon, an alloy of aluminum and copper, or an alloy of aluminum, silicon and copper. It is a material. The amount of each of the alloy components silicon and copper is preferably 5% by weight or less.

In the wiring material according to the present invention, since yttrium is contained in aluminum or an aluminum alloy, the melting point becomes extremely high, which can serve as crystal nuclei during solidification of aluminum, so that very fine crystals can be obtained. It is possible to prevent the bamboo phenomenon.

Further, since it has a large molecular unit, it prevents movement of aluminum atoms during energization or heat treatment,
It is possible to improve the occurrence of various migrations and hill rock phenomenon.

Further, in an aluminum alloy containing copper,
We have found that increasing the copper content increases the effect of preventing the migration and hillocks, but when the copper content increases, copper may be added in the wiring film etching process such as copper chloride. They tend to replace non-volatile materials and reduce the reliability of the resulting integrated circuit.

On the other hand, the alloy according to the present invention has an advantage that it does not adversely affect the reliability of the integrated circuit because the yttrium halide which is considered to be generated by etching is volatile.

The amount of yttrium added to the aluminum alloy according to the present invention increases the defect improving effect as the content increases, while the resistance of the wiring film increases and the etching characteristics change. 5 for reasons such as
Exceeding wt% is not practical.

As described above, the characteristics of the wiring film of the integrated circuit are that various film defects do not occur and at the same time the resistance value of the wiring film is small, the etching is easy, and the film morphology after etching is good. The various conditions such as the good etching characteristics of the above must be fully considered.

The aluminum alloy wiring material according to the present invention is mainly formed into a target by sputtering vapor deposition,
It is deposited as a wiring film of an integrated circuit by means of electron beam evaporation or the like.

[0014]

Example An Al-Si (1 wt%)-Y (0.3 wt%) sputtering target was prepared. As a comparative example, a sputtering target of Al-Si (1% by weight) was prepared. These sputtering targets were sputtered using a magnetron DC sputtering device to deposit a film having a thickness of 0.5 μm on a Si substrate whose surface was converted to SiO ₂ by thermal oxidation.

These films were subjected to 30 at 400 ° C. in a nitrogen atmosphere.
After heat treatment for 1 minute, 1500 using electron microscope
As a result of observing the number of hillocks generated by taking a double magnified photograph, the hillrock number of the film of the present invention was 1/10 that of the film of the comparative example.

Further, as a result of measuring the specific resistance of these films, the film according to the comparative example was 2.9 after the heat treatment at 400 ° C. and 3.1 after the heat treatment at 450 ° C., which is the present invention. The film is 3.1 after heat treatment at 400 ℃, 450 ℃
It was 2.9 after heat treatment. All the above units are (× 10 ⁻⁶ Ω · cm). From this, it was found that there was almost no difference in the specific resistance.

Further, as a result of measuring the Vickers hardness of the film, the film according to the comparative example had a hardness of 34, while the film according to the present invention had a hardness of 117. The reason why the film according to the present invention has less electromigration and less hillock phenomenon is considered to be related to high hardness.

The above film is etched to have a width of 10 μm and a length of 1
A pattern having a thickness of 00μ and a thickness of 0.5μ was formed. Sixteen patterns were created for each pattern, and a life test was performed to observe electromigration. Life test condition is ambient temperature 1
The temperature was 50 ° C. and the current density was 1.5 × 10 ⁶ A / cm ² .
As a result, the average time of disconnection was 572 hours in the case of the comparative example, whereas it was 804 hours in the case of the present invention.
Therefore, it was found that the film according to the present invention has little electromigration and has a long life.

[0019]

According to the present invention, the occurrence of electromigration, hilllock phenomenon, bamboo phenomenon, etc. due to energization can be remarkably reduced, so that the reliability in manufacturing a semiconductor integrated circuit can be extremely increased. is there. Further, there is a feature that the film characteristics such as resistance value and etching property of the wiring film are not impaired.

Claims (2)

[Claims] 1. An aluminum alloy wiring material containing 5% by weight or less of yttrium in aluminum or an aluminum alloy. 2. The aluminum alloy wiring material according to claim 1, wherein the alloy component of the aluminum alloy is silicon, copper, or silicon and copper.