JPS61242039A - Semiconductor device - Google Patents

Abstract

PURPOSE:To lessen the change in the electric resistivity of a semiconductor device and to prevent a hillock from generating by a method wherein a metal nitride layer is provided on the metal layer consisting of aluminum or an aluminum alloy. CONSTITUTION:An Al (or Al alloy) layer 5 and a titanium nitride layer 6 are continuously formed on the surface of an Si substrate 1, whereon a Si oxide film 4 having an opening part 3 is formed, by a sputtering method. Photo resist layers 7 are respectively formed on the surface in an electrode configuration and a processing is performed on the titanium layer 6 by a plasma etching method using a CF4-O2 mixed gas. Parts of the Al layer 5 are etched away using the photo resist layers 7 as masks by a CCl4-series dry etching method and lower wirings (first-layer Al wirings) 15 are formed. By this way, the change in the electric resistivity is reduced and the generation of a hillock can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and more particularly to an electrode structure of a semiconductor device having an electrode having a multilayer structure made of aluminum or an alloy thereof.

[Conventional technology]

Conventionally, this type of multilayer electrode structure has generally had a structure of aluminum or its alloy - insulator layer aluminum or its alloy, but there are problems with dielectric breakdown due to hillocks of the first layer aluminum electrode and deterioration due to electromigration. This poses serious problems in terms of corrosion, yield, and reliability. On the other hand, as a conventional technique, there is a method to prevent the occurrence of hillocks on the electrode by forming a metal silicide layer on the aluminum electrode. On Solid State Devices - 7nd Materials (Extended Abstractsof
The 15th Conference on 5o
lid 5tate Devices and mater
ials), Tokyo, 1983, 233-2.
It is shown on page 36.

[Problem that the invention seeks to solve]

As mentioned above. The conventional method of forming a metal silicide on aluminum uses metals that are easily oxidized, such as titanium and molybdenum, so the surface is oxidized during the process of forming an insulating film on the aluminum-metal silicide electrode. A serious drawback is that ohmic contact cannot be established when forming the electrodes of the second layer.

The present invention eliminates the above-mentioned drawbacks, and the change in electrical resistivity of the underlying aluminum or aluminum alloy electrode is small.

Another object of the present invention is to provide a semiconductor device that can prevent the occurrence of hillocks, is resistant to dielectric breakdown between lower layer wiring and upper layer wiring, and can provide sufficient ohmic contact.

[Means for solving problems]

The semiconductor device of the present invention includes a lower electrode having a metal nitride layer on a metal layer made of aluminum or an alloy thereof, an insulating material layer formed on a surface including the lower electrode, and an insulating layer on the lower electrode. The insulating material layer includes an opening provided in a part of the material layer, and an upper layer electrode made of aluminum or an alloy thereof formed on the insulating material layer including the opening.

Note that the object of the present invention can be achieved by using a metal nitride layer selected from titanium, %lJ powder, tungsten, tantalum, and chromium as the metal nitride layer.

〔Example〕

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

FIGS. 1(a) to 1(g) are cross-sectional views shown in order of steps to explain an embodiment of the present invention and its manufacturing method.

This example is manufactured by the following steps.

First, as shown in FIG. 1(a), a diffusion layer 2 is formed on a silicon substrate 1, a silicon oxide film 4 is formed on the silicon substrate, and an opening 3 is provided on the diffusion layer 2.

Next, as shown in FIG. 1(b), an aluminum (or its alloy) layer 5 and a titanium nitride layer 6 are successively formed on the surface of the silicon substrate 1 having the opening 3 in the silicon oxide M4 by sputtering. yo] form.

Next, as shown in FIG. 1(C), a 7 medium resistor is formed in the shape of an electrode on the surface, and the titanium nitride layer 6 is first coated with CF.
Processing is performed by a plasma etching method using a mixed gas of No. 4102. At this time, the aluminum (or alloy thereof) layer is not etched.

Next, as shown in FIG. 1(d), the aluminum layer is etched away using a resist 7 or a mask by a CC/4 dry etching method to form a lower wiring 15.

Next, as shown in FIG. 1(e), 1 foot resist 7
After removing the interlayer insulating film, for example, plasma CVD
A silicon nitride film layer 8 is formed by a method.

Next, as shown in FIG. 1(f), an opening 9 is formed in the silicon nitride film 8, which is an interlayer insulating film on the lower wiring 15. Then, as shown in FIG.

Next, as shown in FIG. 1(g), an upper layer wiring 10 made of aluminum or its alloy layer is formed on the silicon nitride film in which the opening 9 has been formed, thereby achieving the two-layer wiring of this embodiment. .

As described above, the lower electrode 15 having the metal nitride layer 6 on the metal layer 5 made of aluminum or its alloy, the insulator layer 8 formed on the surface including the lower electrode 15, and the insulation on the lower electrode 15 are formed. An opening 9 provided in a part of the material layer 8
and an upper layer electrode 1o made of aluminum or an alloy thereof formed on the insulator layer 8 including the opening.

As explained above, according to this embodiment, the aluminum and titanium nitride layers do not form a reaction layer with each other to the extent of so"c, and the titanium nitride layer completely prevents the occurrence of hillocks of aluminum during heat treatment. In addition, the titanium nitride layer does not oxidize at about 500'C, and has the characteristics of having an electrical resistivity as low as that of titanium.
It is useful in terms of characteristics and reliability.

Although titanium is shown here as the metal forming the nitride, a metal selected from molybdenum, tungsten, tantalum, and chromium may be used in addition to titanium.

〔Effect of the invention〕

As explained above, according to the present invention, the resistance value of the first layer electrode, that is, the lower layer aluminum electrode, does not react with titanium 9ide, so the change in electrical resistivity is small, and the occurrence of hillocks can be prevented. Resistant to dielectric breakdown between first layer wiring (lower layer wiring) and second layer wiring (upper layer wiring). Also, the first
Since the layer electrodes are not oxidized, effects such as sufficient ohmic contact can be obtained.

[Brief explanation of drawings]

FIGS. 1(a) to 1(g) are cross-sectional views shown in order of steps to explain an embodiment of the present invention and its manufacturing method. 1... Silicon substrate, 2... Diffusion layer,
3...Opening, 4...Silicon oxide film, 5...Aluminum (or its alloy) layer, 6
...Titanium nitride layer, 7...7T resist layer, 8...Silicon perforation film, 9...
- Opening, 10... Second layer aluminum wiring (upper layer wiring), 15... First layer aluminum wiring (lower layer wiring). Rod 1 Coral

Claims (2)

[Claims] (1) A lower electrode having a metal nitride layer on a metal layer made of aluminum or its alloy, an insulating layer formed on a surface including the lower electrode, and a part of the insulating layer on the lower electrode. 1. A semiconductor device comprising: an opening provided in the opening; and an upper electrode made of aluminum or an alloy thereof formed on an insulating layer including the opening. (2) The semiconductor device according to claim (1), wherein the metal nitride layer is a metal nitride layer selected from titanium, molybdenum, tungsten, tantalum, and chromium.