JPH02186634A - Manufacture of integrated circuit device - Google Patents

Abstract

PURPOSE:To make it possible to form a wiring, which is strong against a stress- migration and is inhibited from generating hillocks, by a method wherein first to third metal films for forming a wiring of a three layer structure are formed by a sputtering method which is conducted using the same vacuum chamber. CONSTITUTION:A silicon oxide film 12 is formed on a silicon substrate 11 by thermal oxidation, a first titanium film 13A is sputtered on this film 12, subsequently, an Al film 14 is sputtered in a vacuum identical with a vacuum, in which the film 13A is sputtered, and moreover, a second titanium film 13B is sputtered. Then, a three layer wiring film consisting of the films 13A, 14 and 13B is patterned by a reactive ion etching method to form a three layer wiring 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an integrated circuit device, and in particular to a method for forming three-layer wiring.

[Conventional technology]

Aluminum films and aluminum alloy films formed by sputtering are widely used as wiring materials for semiconductor integrated circuits. This is because aluminum has advantages such as low resistivity, easy processing, good adhesion, and low cost.

In addition, the advantages of the sputtering method, compared to the vapor deposition method, are that the degree of coverage of the metal film on the underlying step is better, that sputter etching is possible, that good ohmic contact can be obtained, and that the formation of an alloy film is possible. For example, it is easy to use.

In recent years, as a countermeasure against electromigration and stress migration, which are the biggest drawbacks of aluminum wiring, aluminum-copper alloy films formed by sputtering using materials doped with about 0.1% to 2% copper in aluminum have been developed. Aluminum-Silicon-
Copper alloy films and the like have come to be used.

[Problem to be solved by the invention]

However, the above-mentioned conventional wiring films made of aluminum or aluminum alloys have a problem in that when the wiring thickness becomes 1 μm or less as the degree of integration increases, even alloy films containing copper do not have sufficient resistance to stress migration.

This is caused by the tensile stress of the aluminum wiring or aluminum alloy wiring itself, as well as the stress from the protective film and interlayer insulation film, which particularly affects thin and narrow wiring, which can lead to disconnection. This is because it becomes

[Means to solve the problem]

In the method for manufacturing an integrated circuit device of the present invention, first . Second. a step of sequentially forming a third metal film by a sputtering method using the same vacuum chamber; Second. This process includes a step of patterning the third metal film to form a three-layer interconnection structure.

〔Example〕

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

FIGS. 1A and 1B are cross-sectional views of a semiconductor chip for explaining a first embodiment of the present invention, and are examples in which the present invention is applied to a single layer of aluminum wiring.

First, as shown in FIG. 1(a), a silicon oxide film 12 is formed on a silicon substrate 11 by thermal oxidation. Next, first apply the first titanium film 13A on top of this with a thickness of 1000 to 2000.
Sputtering to a person's thickness. Before sputtering, the substrate is heated to about 100° C. to 200° C., and moderate heating is performed during sputtering so that the substrate temperature is kept almost constant. The sputtering speed is approximately 1000 persons/min or appropriate.

After the sputtering of the first titanium film] and 3A is completed, an aluminum film 14 (or an aluminum alloy film) is subsequently sputtered to a predetermined thickness in the same vacuum. At this time, the substrate is heated to 100°C to 200°C if necessary. Further, the appropriate sputtering speed is about 1000 people/min.

After sputtering the aluminum film 14, a second titanium film 13B is further sputtered to a thickness of 1000 to 2000 nm in the same vacuum as the first titanium film 13A. At this time, it is not necessary to heat the substrate.

Next, as shown in FIG. 1(b), a first titanium film 13A is formed.
, a three-layer wiring film consisting of the aluminum film 14 and the second titanium film 13B is patterned by reactive ion etching to form a three-layer wiring 20. Next, a silicon nitride film 15 is formed thereon as a protective film by plasma vapor deposition.

As described above, according to the first embodiment, the aluminum film 14
By covering the top and bottom of the 3-layer wiring 20 with a titanium film,
The strong compressive stress exerted by the upper protective film is alleviated, making stress migration of the aluminum wiring less likely to occur. Furthermore, even if the aluminum wiring were to break, the wiring would be connected by the upper and lower titanium films, so
Complete disconnection can be prevented. By creating a three-layer wiring structure in which the top and bottom of the aluminum film are covered with titanium films,
Wiring that is resistant to stress migration can be obtained.

FIGS. 2(a) to 2(C) are cross-sectional views of a semiconductor chip for explaining a second embodiment of the present invention.

The embodiment in Section 2 is an example of application to two-layer aluminum wiring.

First, as shown in FIG. 2(a), similarly to the first embodiment, a three-layer wiring 20 made of an aluminum film sandwiched between titanium films is formed on a silicon oxide film 12. Thereafter, a first silicon nitride film 15A and a second silicon nitride film 15B are formed as interlayer insulating films by plasma vapor deposition. Here, a silicon coating film 16 such as a silica film is used between the bi-chambered silicon films for flattening.

Next, after opening a through hole 7 in this interlayer insulating film for electrical connection with the third layer wiring 20, a third titanium film 3C and a second titanium film 7 are formed in the same manner as in the first embodiment. The aluminum film 14A and the fourth titanium film 1.3D are successively sputtered in the same vacuum. Here, in order to make good ohmic contact with the three-layer wiring 20 before sputtering, it is important to perform sputtering in a vacuum to remove the oxide layer on the surface of the titanium film in the through-hole portion.

Next, as shown in FIG. 2(C), the third titanium film 13C2, the second aluminum film 14A, and the fourth titanium film 13D are patterned by reactive ion etching, and the second three-layer wiring 2OA is patterned. A third silicon nitride film 15C is formed thereon as a protective film by plasma chemical vapor deposition.

In this way, in the second embodiment as well, by covering the top and bottom of the aluminum wiring with titanium films, the strong compressive stress exerted by the protective film and the interlayer insulating film is alleviated, making it difficult for stress migration to occur in the aluminum wiring. Furthermore, since complete disconnection between the aluminum layer and the titanium layer can be prevented, it is possible to provide wiring that is resistant to stress migration. Furthermore, as a secondary effect, hillocks on the aluminum wiring that occur during the heat treatment in the post-process can also be suppressed by the pressing effect of the titanium layer thereon.

In the above embodiments, a titanium film and an aluminum film are used, but a molybdenum film or a tungsten film can be used instead of the titanium film, and an aluminum alloy film can be used instead of the aluminum film.

〔Effect of the invention〕

As explained above, the present invention is resistant to stress migration and suppresses hillocks by forming the first to third metal films for forming a three-layer wiring structure by a sputtering method using the same vacuum chamber. This has the effect of allowing wiring to be formed. Therefore, the quality of the integrated circuit device can be improved.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a semiconductor chip for explaining first and second embodiments of the present invention. 11... Silicon substrate, 12... Silicon oxide film,
13A-13D...Titanium film, 14...Aluminum film, 15.15A-15C...Silicon nitride film, 1
6... Silicon coating film, 17... Through hole, 2
0.2OA...3 layer wiring.

Claims (1)

[Claims] A step of sequentially forming first, second, and third metal films on a semiconductor substrate via an insulating film by a sputtering method using the same vacuum chamber, and patterning the first, second, and third metal films. 1. A method of manufacturing an integrated circuit device, the method comprising the step of forming a three-layer wiring structure.