JPH01101653A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent narrow widths and breakage of wirings with controlled movement of atoms composing aluminum by constructing a wiring consisting mainly of aluminum by dividing into a plurality of parts by high melting point metal layers. CONSTITUTION:A wiring consisting mainly of aluminum, wherein an aluminum layer 15 is divided at a distance which is equal to a first pitch of the aluminum layer 13 by a tungsten layer 14 which is a high melting point metal layer. The electric resistance of tungsten is one order of magnitude higher than that of aluminum, but because the thickness of the tungsten layer 14 is very thin, the electric resistance of the entire wiring is least subject to increase. Accordingly, a decrease in the effective width of the aluminum wiring is extremely small with atomic movement of aluminum, etc., observed in microscopic terms, whereby no partial loss or breakage of the aluminum wiring is not virtually allowed to exist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having highly reliable metal wiring.

[Conventional technology]

Conventionally, metal wiring used in semiconductor devices has mainly been made of aluminum, and is often composed of a single composition film of aluminum alone or an alloy of aluminum and silicon. Further, as other metal wiring, wiring having a multilayer structure of a high melting point metal or a metal and silicon or the like has also been proposed.

[Problem that the invention seeks to solve]

In the conventional aluminum wiring structure described above, since the aluminum or aluminum alloy layer is continuously formed over the entire wiring area, a migration phenomenon in which atoms constituting the wiring of aluminum or aluminum alloy move in the wiring direction is likely to occur at high temperatures or when electricity is applied. . When this phenomenon occurs, the wiring width decreases, and if the phenomenon progresses further, in extreme cases, it causes disconnection of the wiring, which significantly impairs the reliability of the device, which is a major problem.

An object of the present invention is to provide a semiconductor device that prevents migration and improves the reliability of aluminum wiring.

[Means for solving problems]

The semiconductor device of the present invention is a semiconductor device having wiring mainly made of aluminum, in which the wiring is divided into a plurality of parts by a high melting point metal layer, and the movement of aluminum constituent atoms is suppressed by the high melting point metal layer, and the wiring is The structure is designed to prevent width reduction and wire breakage.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(d) are diagrams showing a first embodiment of the present invention according to its manufacturing process.

First, as shown in FIG. 1(a), a silicon oxide film 12 is formed on a silicon substrate 11, and an aluminum layer is formed on this. Then, this aluminum layer is photo-etched to form an aluminum layer 13 having a mesh pattern having a width of 2 μm and a pitch interval of 10 μm.

Next, as shown in FIG. 1(b), a tungsten layer 14 is selectively vapor-phase grown on the top and side surfaces of the aluminum layer 13 to a thickness of 1000 nm in a mixed atmosphere of WF6 gas and hydrogen gas. At this time, tungsten Jii 14 is not grown on the silicon oxide film 12. Next, an aluminum layer 15 is formed over the entire surface by sputtering. The thickness of the aluminum Jii 15 is preferably about the same as the thickness of the aluminum layer 13, and both are 1 μm here.

Then, after coating the entire surface with photoresist 16 and flattening the surface, oxygen plasma or CCI! , the entire surface of the wafer is uniformly etched using four gases, and the first
A flat metal surface having a structure in which the aluminum FFs 13 and 15 and the tungsten layer 14 are arranged in the plane direction as shown in FIG. 3(C) is obtained. In the case of this embodiment, even the tungsten layer on the upper surface of the aluminum layer 13 is removed.

Next, the obtained wire-like metal layer of aluminum and tungsten is dry etched using CCP and CF to form a metal wiring layer as shown in FIG. 1(d).

In this case, it is important to pattern the metal wiring layer so that it intersects with the tungsten layer 14, so that the aluminum wiring is separated by the tungsten layer 14.
The aluminum layer 13, 15 and the tungsten layer 14 are connected in series in the length direction of the wiring.

In the wiring of this embodiment, the aluminum layer 15 is subdivided by the tungsten layer 14 into lengths of approximately 10 μm, which is the initial pitch interval of the aluminum layer 13. Further, the electrical resistance of tungsten is one order of magnitude higher than that of aluminum, but since the thickness of the tungsten layer 14 is extremely thin, about 1,000, the electrical resistance of the entire wiring hardly increases.

In the aluminum wiring formed in this way, the length of the aluminum layer 15 is as short as about 10 μm, so the movement or densification of aluminum or aluminum alloy constituent atoms due to thermal or electrical conduction is extremely limited. . Therefore, even if atoms of aluminum or the like move microscopically, the reduction in the effective width of the aluminum wiring is extremely small, and local disappearance or disconnection of the aluminum wiring does not substantially occur.

FIG. 2 is a perspective view for explaining a second embodiment of the present invention.

First, as shown in FIG. 2(a), an aluminum layer 23 having a desired pattern is placed in advance in a region on a silicon oxide film 22 provided on a silicon substrate 21 where wiring is planned. Next, a tungsten layer 24 and an aluminum layer 25 are sequentially formed using the same method as in the first embodiment, and after planarization, this is etched back to obtain a metal film in which aluminum and tungsten are arranged. By processing it into the desired shape and forming the wiring, as shown in Figure 2 (
Obtain the aluminum wiring shown in b).

This embodiment is characterized in that the aluminum layer 23 is arbitrarily formed in advance in areas where wiring is required. Therefore, although the design is somewhat more complicated than the first embodiment, it is possible to facilitate the final processing process of the aluminum wiring, or to increase the density of the tungsten layer 24 depending on the current density flowing through the wiring.
It has advantages such as being able to change the density of the material, improving the degree of freedom in design and improving the reliability of the finished product.

Here, in each of the above embodiments, only the wiring formation method was mentioned, but it goes without saying that the present invention can be applied to the entire normal semiconductor device including active elements such as transistors and circuit components such as contact holes.

Further, in order to make the present invention function more effectively, it is possible to apply a planarization technique such as a bias sputtering method to the formation of the aluminum layer, or to form the aluminum layer! It is particularly effective to take measures in the process such as making the side walls of 13.23 gently sloped in advance.

Further, in this embodiment, tungsten vapor phase growth was used as a method for forming the high melting point metal, but other methods such as sputtering may be used. It goes without saying that other materials such as titanium and molybdenum may also be used.

〔Effect of the invention〕

As explained above, the present invention has a structure in which a wiring mainly made of aluminum is divided into a plurality of parts by a high melting point metal layer, so that the movement of aluminum constituent atoms is suppressed by this high melting point metal layer and the wiring is Width reduction and wire breakage can be prevented, thereby improving the reliability of the entire device. In addition, because the current frequency per unit cross-sectional area can be increased in response to improvements in wiring reliability, device functions can be achieved with narrower wiring widths than before, resulting in higher density and higher integration of devices.
This has the effect of improving circuit functionality.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the first embodiment of the present invention in the order of steps.
Figure (a) is a perspective view, Figures 1 (b) and 1 (C) are sectional views, Figure 1 (d) is a perspective view, and Figures 2 (a) and 2 (b) are main views. FIG. 7 is a perspective view showing a second embodiment of the invention in order of steps. 11.21... Silicon substrate, 12.22-... Silicon oxide film, 13.23... Aluminum layer, 14°24... Tungsten layer, 15.25... Aluminum layer, 16... Photoresist. IJ 13 Figure 1 (d)

Claims (1)

[Claims] (1) A semiconductor device having wiring mainly made of aluminum, characterized in that the wiring is divided into a plurality of parts by a high melting point metal layer.