JPH06151608A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the step coverage of an aluminum wiring in contact hole part or a via hole part of a high aspect ratio. CONSTITUTION:A titan thin-film 5 of 200nm or less is formed on the whole surface including the inner part of a via hole 10 formed in a layer insulating layer 4, and a wiring film 6 of aluminum alloys is deposited by sputtering on the titan thin-film 5. At that time, a films of Al-Ti alloys is formed in a boundary part between the titan thin-film 5 and the wiring film 6 of aluminum alloys, and the wiring film 6 of aluminum alloys is surely deposited in the inner part of the via hole 10 through the reaction of making alloys, so that the quality of forming a film in the part of the via hole 10 may be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device capable of improving the step coverage of a metal wiring film in a contact hole portion or a via hole portion, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Hitherto, multi-layer wiring has been promoted in order to increase the density of semiconductor integrated circuits. In recent years, however, due to the miniaturization of the wiring, contact holes for connecting a semiconductor substrate and metal wiring and upper wirings have been formed. The aspect ratio of the via hole connecting the lower layer wiring is increasing.

Therefore, how to form a metal wiring film with good coverage (step coverage) on the contact hole portion or via hole portion having a high aspect ratio is a big problem at present.

Regarding the wiring material, an Al alloy is currently the mainstream in consideration of its wiring resistance, workability, and cost, but the film composition in the case of the Al alloy is the composition of the film. In consideration of controllability, throughput, film quality, etc., the deposition method by sputtering (sputtering method) is the best.

[0005]

The sputtering method is generally known as a film forming method with good step coverage, but when the aspect ratio becomes large especially in the contact hole portion and the via hole portion as at present. , Step coverage in these areas is becoming insufficient.

Therefore, an object of the present invention is to provide a semiconductor device having improved step coverage particularly in a contact hole portion or a via hole portion having a high aspect ratio, and a manufacturing method thereof.

[0007]

In order to solve the above problems, in the semiconductor device of the present invention, a titanium thin film is laid under the metal wiring film.

In the present invention, preferably, the titanium thin film has a thickness of 200 nm or less.

Further, in the present invention, preferably, the metal wiring film is mainly made of aluminum.

Also, in the present invention, preferably, the titanium thin film is a through hole formed in at least an insulating film between a semiconductor substrate and a metal wiring or an interlayer insulating film between a lower wiring and an upper metal wiring. Is formed on the inner surface of the.

The semiconductor device manufacturing method of the present invention is
A step of forming a through hole in an insulating film formed on a semiconductor substrate or an interlayer insulating film formed on a lower wiring,
A step of depositing and forming a titanium thin film on the entire surface of the insulating film or the interlayer insulating film including the inner surface of the through hole; a step of depositing and forming a film mainly made of aluminum on the titanium thin film; and a step mainly made of aluminum And a step of processing the film and the titanium thin film into a wiring pattern.

[0012]

In the present invention, the titanium thin film is laid under the metal wiring film. This titanium thin film reacts with the wiring material metal when the metal wiring film is deposited and formed, and the titanium thin film of the metal wiring film at the step portion is formed. Improve film formability.

For example, when aluminum or an aluminum alloy is used as the wiring material metal, when the aluminum or aluminum alloy film is deposited and formed by, for example, the sputtering method, the aluminum or aluminum alloy film is formed at the boundary between the aluminum or aluminum alloy film and the titanium thin film. An Al-Ti based alloy film is formed. Then, as the Al--Ti alloying reaction progresses, aluminum or aluminum alloy is surely deposited, for example, from the step portion to the bottom portion of the contact hole or via hole having a high aspect ratio to obtain a wiring film having good step coverage. To be

Unlike the conventional barrier metal, the titanium thin film of the present invention preferably has a film thickness of 200 nm or less, more preferably 10 to 200 nm.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a via hole portion connecting upper and lower wirings in the order of manufacturing steps thereof.

First, as shown in FIG. 1A, an Al alloy wiring film 3 which is a lower layer wiring is patterned on a Si oxide film 2 formed on a Si substrate 1, and the entire surface is further formed. ,
A Si oxide film 4 which is an interlayer insulating film is formed. Then, a via hole 10 is opened in this Si oxide film 4. In this embodiment, the size of the via hole 10 is 0.8 μm in diameter and 1 μm in depth.

Next, as shown in FIG. 1B, a Ti film 5 is formed on the entire surface of the Si oxide film 4 including the inner surface of the via hole 10.
To form a film. In this embodiment, the Ti film 5 is formed by the sputtering method.
Was formed and the film thickness was set to 20 nm.

Next, as shown in FIG.
An Al alloy wiring film 6 is formed on the film 5. In this embodiment, the Al alloy wiring film 6 is formed by the sputtering method and the thickness thereof is 800 nm. At this time, the film forming temperature of the Al alloy wiring film 6 was set to 300 ° C. or lower.

The Al alloy wiring film 6 and the Ti film 5 formed as described above are processed into a wiring pattern by photolithography and etching, and then the via hole 1 is formed.
The electrical open defect rate at the 0 portion and the coverage rate of the wiring film by cross-sectional observation were examined. As a result, the via open defect rate in the 6-inch wafer was 40% when the Ti film 5 was not used, while it was 0% when the Ti film 5 was used. Further, the coverage by cross-section observation was several% when the Ti film 5 was not used, but improved to 30% or more when the Ti film 5 was used. On the other hand, the resistance value is higher than that in the case without the Ti film 5.
The increase was about 0.03Ω.

Although the embodiment in which the present invention is applied to the via hole portion for connecting the wirings has been described above, the present invention can be similarly applied to the contact hole portion for connecting the semiconductor substrate and the metal wiring. . In addition, a barrier metal (for example, TiN) is formed in these via holes and contact holes.
After forming the film, the titanium thin film according to the present invention is formed on the barrier metal, and the Al or Al alloy wiring film is formed on the titanium thin film.

Unlike the conventional barrier metal, the titanium thin film of the present invention preferably has a film thickness of 200 nm or less, more preferably 10 to 200 nm.

Further, in the above-mentioned embodiment, the lower layer wiring is A
Although the l-alloy wiring film 3 is used, the lower wiring is, for example, polycrystalline Si.
It may be a wiring film. Further, as a method of forming the Ti film 5,
Besides the normal sputtering method, a CVD method, a collimating sputtering method, or the like can be used. Further, the upper metal wiring film formed on the Ti film 5 may be any one that reacts with Ti, and may be, for example, a Cu-based one.

[0024]

According to the present invention, a very thin titanium thin film is laid under a metal wiring film, and when a metal wiring film is deposited and formed, an alloying reaction between the wiring material metal and titanium as a base is performed. To use. Therefore, for example, the step coverage of the metal wiring film in the contact hole portion or the via hole portion having a high aspect ratio is improved, and the reliability of the wiring and the manufacturing yield of the device are improved.

Further, according to the present invention, it is not necessary to increase the substrate temperature or apply a reverse bias to the substrate when forming the metal wiring film. Therefore, there is a concern that these may adversely affect the internal circuit. There is no.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a semiconductor device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Si substrate 2 Si oxide film 3 Al alloy wiring film (lower layer wiring) 4 Si oxide film (interlayer insulating film) 5 Ti film 6 Al alloy wiring film (upper layer metal wiring) 10 Via hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Nakano 5-10-1 Fuchinobe, Sagamihara-shi Nippon Steel Corp. Electronics Company Research Laboratory

Claims (5)

[Claims] 1. A semiconductor device in which a titanium thin film is laid under a metal wiring film. 2. The semiconductor device according to claim 1, wherein the titanium thin film has a thickness of 200 nm or less. 3. The semiconductor device according to claim 1, wherein the metal wiring film is mainly made of aluminum. 4. The titanium thin film is formed on at least an inner surface of a through hole formed in an insulating film between a semiconductor substrate and a metal wiring or an interlayer insulating film between a lower wiring and an upper metal wiring. The semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor device. 5. A step of forming a through hole in an insulating film formed on a semiconductor substrate or an interlayer insulating film formed on a lower wiring, and the insulating film or the interlayer insulating film including an inner surface of the through hole. A step of depositing and forming a titanium thin film on the entire surface of the substrate, a step of depositing and forming a film mainly made of aluminum on the titanium thin film, and a step of processing the film mainly made of aluminum and the titanium thin film into a wiring pattern. A method of manufacturing a semiconductor device, comprising: