JPH10223569A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the reliability of a barrier metal in a minutely formed contact holes. SOLUTION: After an interlayer insulating film 4 has been formed on the impurity area 3 of a silicon substrate 1, a contact hole 6 communicated with the impurity region 3 is formed through the insulating film 4. Then a barrier metal 9 containing a noncrystallized titanium nitride film 8 is obtained, by forming a titanium nitride film 8 and a titanium film 7 as a barrier metal 9 on the entire surface of a device, including the internal surface of the contact hole 6 and introducing silicon ions into the titanium nitride film 8. In addition, an aluminum alloy film 10 is formed on the barrier metal 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly, to a wiring structure and a technique for forming the same.

[0002]

2. Description of the Related Art In recent years, with the increase in the degree of integration of semiconductor devices, further reduction in the design rules of wiring and contacts has been required. However, with the reduction in the size of the wiring, the deterioration of the reliability of the aluminum wiring, which is currently most frequently used, has become apparent. Therefore, by adding a trace amount of silicon or copper to aluminum to form an alloy, or by forming a laminated structure of an aluminum wiring layer and a high melting point metal (titanium or tungsten) layer or a high melting point metal nitride layer, EM ( Electromigratio
n) Improving resistance and SM (stressmigration) resistance.

Further, by providing a barrier metal under the aluminum wiring layer, a reaction between the aluminum wiring and the silicon substrate in the contact portion is suppressed. As the barrier metal, a refractory metal layer or a nitride layer thereof is mainly used. If a barrier metal is used, alloy spikes caused by the incorporation of silicon in the silicon substrate into aluminum wiring can be suppressed. It is possible to prevent an increase in junction leak caused by the spike breaking the junction layer.

[0004] In recent years, the degree of integration of semiconductor devices has been further increasing, and it has been required to reduce the diameter of contact holes for connecting aluminum wiring and a substrate. However, when the diameter of the contact hole is reduced, it becomes difficult to deposit a titanium nitride film and an aluminum wiring layer having a sufficient thickness in the contact hole, and it is necessary to secure the thickness of the aluminum wiring layer which is a main wiring layer. Inevitably, the thickness of the titanium nitride film as a barrier metal must be reduced.

However, in general, a titanium nitride film has a crystal structure because it is formed by a sputtering method. When the titanium nitride film is too thin, silicon in a silicon substrate is taken into aluminum wiring starting from a crystal grain boundary. Therefore, there is a fear that the function as a barrier metal may not be achieved. Therefore, use of a titanium nitride film having an amorphous structure as a barrier metal is described in JP-A-5-291560.

[0006]

However, this publication describes that particles having a certain kinetic energy or more are irradiated in order to obtain a titanium nitride film having an amorphous structure. Furthermore, there is a problem that the titanium nitride film as the barrier metal has a large contact resistance with the substrate at the bottom of the contact hole and does not exhibit good ohmic characteristics.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to secure the reliability as a barrier metal even in a contact hole which has been miniaturized.

[0008]

According to a first aspect of the present invention, there is provided a semiconductor device in which a lower conductive layer and an upper conductive layer are sandwiched by a barrier metal having a laminated structure including a titanium film and an amorphous titanium nitride film thereon. Connected. According to a second aspect of the present invention, the lower conductive layer is formed using silicon as a main material, and the upper conductive layer is formed using aluminum as a main material.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a barrier metal comprising a titanium film and a titanium nitride film on the lower conductive layer; The method includes a step of amorphizing the titanium nitride film by the introduction, and a step of forming an upper conductive layer on the barrier metal.

In a fourth aspect of the present invention, the method of manufacturing a semiconductor device further comprises the steps of: forming an insulating film on the lower conductive layer; forming a contact hole in the insulating film so as to communicate with the lower conductive layer. Forming a titanium film on the bottom of the contact hole and a barrier metal comprising a titanium nitride film thereon; and introducing at least silicon ions into the titanium nitride film to make the titanium nitride film amorphous. Forming an upper conductive layer connected to the lower conductive layer via the barrier metal at least in the contact hole.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device, the lower conductive layer is formed using silicon as a main material,
The upper conductive layer is formed using aluminum as a main material. That is, in the semiconductor device and the method of manufacturing the same according to the present invention, since at least a part of the barrier metal has an amorphous structure, there is no crystal grain boundary in this part, and even if the barrier metal is thinned, the lower conductive material is formed. There is no concern that the components of the layer and the components of the upper conductive layer will interdiffuse.

Further, a titanium film having good ohmic characteristics is provided below the titanium nitride film as a barrier metal,
Since the lower conductive layer is in contact with the titanium film, the contact resistance between the lower conductive layer and the barrier metal is small.
In particular, in the method of manufacturing a semiconductor device according to the present invention, silicon ions are implanted into a barrier metal having a crystal structure as a technique for amorphizing a barrier metal (titanium nitride film). There is no fear of adversely affecting the conductive properties of the conductive layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. 1 to 4 are cross-sectional views sequentially showing the manufacturing process of the semiconductor device according to the present embodiment. Hereinafter, description will be made with reference to these drawings. Step 1 (see FIG. 1): An element isolation film 2 is formed on a single crystal silicon substrate 1 by using the LOCOS method. Next, an impurity is implanted into the substrate 1 by ion implantation to form an impurity region (diffusion layer) 3. The impurities used here include, for example, phosphorus as an N-type impurity and boron as a P-type impurity. Subsequently, an interlayer insulating film (for example, a silicon oxide film) (film thickness:
(1 μm) 4 is formed. Then, heat treatment (processing temperature: 850 ° C., processing time: 30 minutes) is performed in a nitrogen atmosphere. After that, a resist pattern 5 for contact opening is formed on the interlayer insulating film 4.

Step 2 (see FIG. 2): A contact hole 6 is formed in the interlayer insulating film 4 by dry etching using the resist pattern 5 as an etching mask. As a result, the impurity region 3 is exposed at the bottom of the contact hole 6. Step 3 (see FIG. 3): Using a direct current sputtering method, titanium (T) is formed on the entire surface of the device including the inside of the contact hole 6.
i) Deposit a film 7 of 50 nm. The deposition conditions are, for example,
Argon (Ar) gas atmosphere, DC power: 8 KW, pressure:
5 mT and a substrate temperature of 300 ° C. are used.

Further, using a direct current sputtering method,
A 70 nm titanium nitride (TiN) film 8 is deposited. The deposition conditions are, for example, a gas atmosphere in which argon (Ar) and nitrogen (N ₂ ) are mixed at a ratio of 1: 1, DC power: 8 KW, pressure:
3.5 mT and a substrate temperature of 300 ° C. are used. The TiN film 8 thus formed is not in an amorphous state, but has a polycrystalline structure because a peak such as (111) is observed by XRD diffraction.

Then, in order to amorphize the polycrystalline TiN film 8, silicon ions (S
i ⁺ ), acceleration energy: 30 KeV, dose: 1 × 1
The injection is performed under the condition of 0 ¹⁶ / cm ² . Thus, a barrier metal 9 including the Ti film 7 and the amorphous TiN film 8 is formed.

Step 4 (see FIG. 4): Using a sputtering method,
An aluminum alloy film (Al-Si (1%)-Cu (0.5%)) film 10 is formed on the entire surface of the device including the inside of the contact hole 6. In step 4, without filling the contact hole 6 with the aluminum alloy film 10, for example, forming a tungsten plug in the contact hole,
The aluminum alloy film 1 is electrically connected to this plug.
0 may be formed.

Although the barrier metal between the impurity region of the silicon substrate and the wiring has been described as an example, the present invention is, of course, applicable to the barrier metal between the lower wiring and the upper wiring in the multilayer wiring structure.

[0019]

According to the present invention, since at least a part of the barrier metal has an amorphous structure, there is no crystal grain boundary in this part. There is no concern that the components of the upper conductive layer will interdiffuse. In addition, as a barrier metal, a titanium film having good ohmic characteristics is provided under the titanium nitride film so that the lower conductive layer and the titanium film are in contact with each other.
The contact resistance between the lower conductive layer and the barrier metal is small, and the electrical characteristics are good.

In particular, in the inventions of claims 3 to 5,
As a technique for amorphizing the barrier metal (titanium nitride film), silicon ions are implanted into a barrier metal having a crystal structure, so that there is no fear that the conductive properties of the lower conductive layer are adversely affected. Therefore, the reliability as a barrier metal can be ensured even in a contact hole that has been miniaturized.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a manufacturing process of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a manufacturing process of the semiconductor device according to the embodiment of the present invention.

FIG. 3 is a sectional view illustrating a manufacturing process of the semiconductor device according to the embodiment of the present invention;

FIG. 4 is a sectional view illustrating a manufacturing process of the semiconductor device according to the embodiment of the present invention;

[Description of Signs] 1 silicon substrate 3 impurity region (lower conductive layer) 4 silicon oxide film (insulating film) 6 contact hole 7 titanium film 8 titanium nitride film 9 barrier metal 10 aluminum alloy film (upper conductive layer)

Claims (5)

[Claims] 1. A semiconductor device wherein a lower conductive layer and an upper conductive layer are connected via a barrier metal having a laminated structure composed of a titanium film and an amorphous titanium nitride film thereon. 2. The semiconductor device according to claim 1, wherein the lower conductive layer is formed using silicon as a main material, and the upper conductive layer is formed using aluminum as a main material. 3. A step of forming a barrier metal comprising a titanium film and a titanium nitride film on the lower conductive layer, and introducing silicon ions into at least the titanium nitride film to form the titanium nitride film. Crystallizing; forming an upper conductive layer on the barrier metal;
A method for manufacturing a semiconductor device, comprising: 4. A step of forming an insulating film on the lower conductive layer, a step of forming a contact hole communicating with the lower conductive layer in the insulating film, and forming a titanium film on at least a bottom of the contact hole and a titanium film on the titanium film. A step of forming a barrier metal made of a titanium nitride film; a step of amorphizing the titanium nitride film by introducing silicon ions into at least the titanium nitride film; and a step of interposing the barrier metal in at least the contact hole. Forming an upper conductive layer connected to the lower conductive layer by using the method. 5. The method according to claim 3, wherein the lower conductive layer is formed using silicon as a main material, and the upper conductive layer is formed using aluminum as a main material.