JPS61258449A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device provided with its very long-lived wiring conductors by a method wherein a wiring conductor having the low- reliable conductor width region is replacement-formed into plural microscopic conductors in parallel connection. CONSTITUTION:This semiconductor integrated circuit device is one obtainable by simply dividing a wiring conductor having its conductor width of 10mum into microscopic conductors and includes five microscopic conductors 1, each having the conductor width of 2mum, and a parallel connection conductor part 2. The current densities J of the microscopic conductors 1 are respectively uniform and are set in the same one as the current density of the wiring conductor having its conductor width of 10mum. Yet the wiring longevities (t50) of these microscopic conductors 1 reach as long as 20 times or more than the wiring density of the wiring conductor having its conductor width of 10mum. As a result, though the occupation area of this semiconductor integrated circuit device somewhat increases, the reliability of the wiring can be rapidly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor integrated circuit device using aluminum or an alloy thereof as a wiring conductor.

(Prior Art) It is already well known that aluminum or an alloy thereof is used as a wiring material for semiconductor integrated circuit devices.

These wiring materials are usually deposited on a substrate by sputtering to form a wiring conductor with a specified width and thickness.

In this case, the lifetime of the wiring conductor (generally expressed as the sum of the median lifetimes) is conventionally determined by the occurrence of the electro-migration phenomenon, and the conductor width of the wiring to be formed is usually approximated by the following empirical formula. It was decided that.

In other words, tH=AWtJ eXp (φ/Ni=A(Wt) I exp(φ/kt) The problem that the invention is intended to solve) However, the inventor recently conducted an experiment regarding miniaturization of wiring conductors. According to the wiring life t,. The conductor width W is 10 to 2
It was confirmed that the minimum point was found in the range of 0.8 m, and that fine conductors smaller than this behaved in a completely different manner. In other words, when the conductor width W is decreased while keeping the current density J and thickness t constant, the life span of the wiring conductor -10 continues to decrease as the conductor width W decreases, but it reverses around approximately 10 to 20 μm. However, on the contrary, it begins to show characteristics that result in a long life. The slope of this inversion curve is extremely steep, and for example, a fine conductor with a conductor width of 1 μm has a wiring median life tso that is several tens of times or more than that of a conductor width of 20 μm, which was conventionally considered to be highly reliable.

(Objective of the Invention) An object of the present invention, based on the above experimental data, is to provide a semiconductor integrated circuit device having a wiring conductor with a miniaturized structure that can guarantee an extremely long life.

(Structure of the Invention) The semiconductor integrated circuit device of the present invention includes that at least one wiring conductor made of aluminum or an aluminum alloy is formed by parallel connection using fine conductors having a conductor width of 5 μm or less.

(Means for solving the problem) That is, according to the present invention, at least the conductor @W10~2
Wiring conductors whose median lifespan of 0 μm rapidly decreases have a much higher and dramatically longer wiring lifespan than this.
It is replaced with a fine conductor having a conductor width of 5 μm or less, and is connected in parallel according to the current capacity. According to more detailed experiments, even when the current density J is doubled without changing the film quality, the lifespan is ts.

Since data has been obtained that does not change the improvement effect, the number of parallel fine conductors to be replaced can be far smaller than the number of simple divisions.

(Function) The sputtered film of aluminum and aluminum alloy is
At present, it is not possible to provide a sufficient explanation as to why such physical properties are exhibited at a conductor width of 10 to 20 μm. However, overcoming conventional expectations, it has been demonstrated that a fine conductor with a conductor width of 5 μm or less has the same level of reliability as a wiring conductor with a conductor width several times that of the conductor. The wiring structure of the connection is particularly important when the conductor width is lO~
Deterioration in reliability of a 20 μm wiring conductor can be effectively and reliably relieved.

The present invention will be described in detail below with reference to the drawings.

(Example) Figure tJ1 is a wiring conductor diagram showing one embodiment of the present invention.

In this embodiment, a wiring conductor of 1110 μm is simply divided into fine conductors, and includes five fine conductors l each having a conductor width of n2 μm and a parallel connection conductor portion 2. In this embodiment, the current density J of the fine conductors 1 is set to be equal to n and the same as that of a wiring conductor having a conductor width of 10 μm. However, since the wiring life tso of this fine conductor 1 is more than 20 times that of a wiring conductor of conductor @10 μm, the reliability of the wiring can be dramatically improved, although the area occupied is increased somewhat. This phenomenon is explained by the following fact I by the inventor.
i1 is clearly explained based on facts.

FIG. 2 is an experimental data diagram showing the relationship between the conductor width (W) and the median life (tso) of an aluminum wiring conductor.

In this experiment, an aluminum wiring conductor was used that was sputtered onto a semiconductor substrate surface heated to a temperature of 300 to 400°C, and then annealed for 20 to 60 minutes at a temperature of 400 to 450°C. am”), two different conditions were selected.

That is, the conductor width W is L2 (μm) and 3.2 (
μm) and 7.1 (μm) wiring conductors have a current density J of 2 × 10” (A/am”) and the same
Current density J of wiring conductor of 7.1 (μm) and 19 (μm)
was selected to be half of that, I x 1G (A/am), and the median lifetime tso of each interconnect was tested. Here, the median lifetime tso of the wiring is normalized based on the conductor width value of 7.1 (μm) tested for two current densities.

According to this experimental data, the median lifetime of the wiring, t,.

does not simply continue to shorten as the conductive width (W) decreases, as predicted by the conventional experimental formula, but rather a minimum point appears at 10 to 20 μm, which is far beyond expectations.
It is recognized that when entering the fine region of 5 (μm) or less, the increase increases dramatically.

Moreover, in this experimental data, even if the current density is doubled, the median lifetime tso of the wiring of these fine conductors shows a similar tendency. Therefore, based on this experimental data, it is possible to make the number of parallel fine conductors much smaller than the number of simple divisions.

FIG. 3 is a wiring conductor diagram showing another embodiment of the present invention, in which a wiring conductor with a conductor width of 10 Am was constructed based on the above experimental data.
It is formed using two fine conductors 3. The conductor width of the fine conductor 3 in this example is selected to be 2 μm, the same as in the previous example, and the current density is set to slightly more than double. Therefore, by adjusting the thickness t to be a little thicker and slightly relaxing the current density, it becomes possible to form extremely reliable wiring within a small area.

Needless to say, the physical properties of an aluminum wiring conductor vary greatly depending on its formation conditions. This experimental data is one example, and after repeated experiments, the median lifespan of the wiring t
The minimum point of so is observed over a wide range of conductor width W of 10 to 20 μm. However, it has been confirmed that in many cases, a dramatic improvement in the interconnect lifetime tlO is observed in a fine region exceeding 5 μm. This also applies to alloy materials.

(Effects of the Invention) As described in detail above, according to the present invention, by replacing the unreliable wiring conductor in the conductor width region with a parallel connection of a plurality of fine conductors, an extremely long life can be achieved. Since a semiconductor device including wiring conductors can be obtained, its reliability can be significantly improved. It is also possible to reduce the wiring area.

[Brief explanation of drawings]

Fig. 1 is a wiring conductor diagram showing an embodiment of the present invention, and Fig. 2 shows the conductor width (W) and median life (-) of an aluminum wiring conductor.
FIG. 3 is a wiring conductor diagram showing another embodiment of the present invention. 1.3... Fine conductor, 2... Parallel connection conductor section, W... Wiring conductor width, "NO..."
・Median life of wiring, t... Thickness of wiring conductor, J... Current density.

Claims (1)

[Claims] 1. A semiconductor integrated circuit device, wherein at least one wiring conductor made of aluminum or an aluminum alloy is formed by parallel connection of fine conductors having a conductor width of 5 μm or less.