JP2750860B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an electrode wiring by using a flattening step in forming a barrier metal in forming an electrode of a semiconductor device. , Large barrier properties,
A process of forming a contact window in an insulating film on a region where an electrical contact with a base is formed; and a method of forming a contact window formed on the contact window. At least one step of flattening the surface of the first barrier metal film with an organic material film and the step of flattening the first barrier metal film using anisotropic etching are performed.
A step of leaving a first barrier metal film on the insulating film and leaving the barrier metal film in a grown state on a side wall portion serving as a step of the contact window, And a step of depositing the second barrier metal film at least once.

[Industrial applications]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming an electrode wiring by using a flattening step for forming a barrier metal.

[Conventional technology]

2. Description of the Related Art Conventionally, in the manufacture of semiconductor devices, the operation speed has been improved along with the miniaturization of elements, and accordingly, the junction has become shallower. Therefore, in forming the electrode wiring, a barrier metal for preventing mutual diffusion is used in order to prevent a junction breakdown or the like caused by mutual diffusion between the wiring metal and silicon.

FIG. 5 is a sectional view showing such a conventional electrode wiring portion. As shown in the figure, a contact window 4 is formed on a diffusion region 2 formed in a silicon substrate 1 by removing a silicon oxide (SiO ₂ ) film 3, and a contact metal 5 and a barrier are formed in the contact window 4. A metal 6 is formed by sputtering or the like, and a conductive metal 7 for wiring such as aluminum (Al) or gold (Au) is formed on the barrier metal 6.
Are formed. The contact metal 5 is provided to form an electrical contact such as an ohmic contact with the underlying silicon substrate 1. The barrier metal 6 is the underlying silicon and the conductive metal 7.
It is provided to prevent interdiffusion between Al, Au, and the like, and to prevent junction breakdown. As the barrier metal 6, for example, methane nitride (titanium nitride: TiN) is frequently used.

[Problems to be solved by the invention]

However, the conventional barrier metal 6 has the drawback that the film thickness at the side wall portion which is a step of the contact window 4 is thin, the film quality is weak, and the barrier property is incomplete. This is because the barrier metal 6 is deposited by a sputtering method or the like, so that the film quality of the side wall portion is inferior to that of the flat portion, and a difference occurs in the growth direction between the film of the side wall portion and the film of the flat portion.
This is because a discontinuous line is formed at the boundary. For this reason, conventionally, the barrier metal 6 is conventionally deposited thickly or subjected to various heat treatments, but the barrier property is not always sufficient, which hinders miniaturization.

An object of the present invention is to provide a method of manufacturing a semiconductor device which has a large barrier property and is suitable for a miniaturized structure in forming an electrode of the semiconductor device.

[Means to solve the problem]

The object is to form a contact window in an insulating film on a region where an electrical contact with a base is formed, and to planarize the surface of a first barrier metal film grown on the contact window with an organic material film. In performing the step and the flattening step by etching the first barrier metal film using anisotropic etching at least once, the first barrier metal film remains on the insulating film and becomes a step of the contact window. A solution is provided by a method of manufacturing a semiconductor device, comprising: a step of leaving the barrier metal film in a grown state on a side wall portion; and a step of depositing a second barrier metal film at least once on the first barrier metal film. Is done.

[Action]

That is, the present invention performs a planarization step by anisotropic etching of the barrier metal grown on the contact window,
The thickness of the barrier metal on the side wall of the contact window is increased, the film quality is enhanced, and the barrier properties are improved.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

1 (a) to 1 (e) are cross-sectional views showing a manufacturing process of an electrode wiring portion according to an embodiment of the present invention.

First, as shown in FIG. 1A, a silicon oxide (Si) is formed on a diffusion region 12 of a silicon substrate 11 for forming a contact portion such as an electrical contact by a process not shown.
O ₂ ) The film 13 is removed to form a contact window 14 having a width of about 1 μm. In the contact window 14, a first TiN film 15 is deposited as a barrier metal to a thickness of about 2000 ° by a reactive magnetron sputtering method. The conditions for forming the first TiN film 15 by the reactive magnetron sputtering method include, for example, a pressure of 5 × 10 ⁻³ torr and an atmosphere of argon and nitrogen gas (Ar + N ₂ ) at a flow ratio of 1: 1. ,
Round titanium (Ti) measuring 20cm in diameter and 5mm in thickness
An energy of about 3 kw is applied to the target, and the target is grown for about 2 minutes on the silicon substrate 11 at a distance of 10 cm to obtain a first TiN film 15 having a thickness of about 2000 °. Next, as shown in FIG. 2B, on the first TiN film 15,
In the flat portion, a film of an organic material, for example, a resist film 16 is applied so that the film thickness becomes about 3000 °. As a result, the surface of the contact window 14 is almost flatly filled with the resist film 16 having fluidity.

Next, as shown in FIG. 3C, the first TiN film in the flat portion is formed by parallel plate type reactive ion etching (RIE).
Etching is performed to such an extent that 15 is almost removed, that is, to such an extent that the TiN thin film remains on the SiO ₂ film 13 as shown in FIG. The etching conditions are, for example, freon (C
In an atmosphere in which about ₄ % of oxygen gas (O ₂ ) is added to F ₄ ),
Apply energy with pressure of 0.15torr and about 500W and carry out for about 5 minutes. Thereby, the surface is almost flattened.

Next, as shown in FIG. 4D, the resist film 16 in the contact window 14 is peeled off. The stripping conditions are, for example, dry etching in a single-wafer asher in an atmosphere of 100% oxygen gas (O ₂ ), applying energy at a pressure of about 1 torr and about 500 W for about 10 minutes. And then,
The surface is subjected to high frequency (RF) etch cleaning by about 100 mm using a sputtering device. The cleaning conditions are as follows: in an atmosphere of argon (Ar) gas, the pressure is 1 × 10 ^-2 torr,
Input energy of about 0.2 W / cm ^{2 and} perform for about 3 minutes.

Next, as shown in FIG. 4E, a second TiN film 17 is deposited to a thickness of about 2000.degree. Under the same conditions as in the step shown in FIG.

According to the above-described method of manufacturing the electrode portion, the first TiN film 15 is formed in the contact window 14, and the second TiN film 17 is formed after being flattened by the etch-back. A metal is formed. This barrier metal is reinforced by thickening the film thickness of the side wall portion which becomes the step of the contact window 14, and the film quality is enhanced. Therefore, the barrier property also increases. Then, by repeating the above-described etch back a plurality of times as described later, it becomes possible to form an electrode having good characteristics.

FIG. 2 is a sectional view of an electrode portion manufactured by the above method. TiN formed by etch back by the above method
On the film 21, a pure aluminum wiring film 22 is formed to a thickness of about 7,000 °. Parts corresponding to FIG. 1 are denoted by the same reference numerals.

3 (a) and 3 (b) are cross-sectional views of an electrode portion formed for testing the barrier properties of the present invention.

First, as shown in FIG. 2A, about 100 contact windows 14 are formed in order to test the barrier properties, and the TiN film 21 is etched through the contact windows 14 by etching back as shown in FIG. Was formed thereon, and a pure aluminum wiring film 22 was formed thereon to a thickness of about 7000 mm. And 480 ℃, 3
The heat treatment for 0 minutes was repeated about three times. If there is a defect in the TiN film 21 due to this heat treatment, the pure aluminum wiring film 22
Between the silicon substrate 11 and the silicon substrate 11 occurs.

Thereafter, as shown in FIG. 2B, the pure aluminum wiring film 22 and the TiN film 21 were removed with aqua regia, and cracks (defective portions) 20 of the silicon substrate 11 as the base were observed.

FIG. 4 is a view showing a test result of barrier properties according to the embodiment of the present invention. In the figure, the abscissa represents the number of times of etching back, that is, the number of repetitions of etching when forming the TiN film 21, and the ordinate represents the ratio (%) of the number of defective portions to the number of samples, indicating the barrier property. As shown in the figure, the barrier property gradually improves with an increase in the number of etchbacks, and shows 70% when the number of etchbacks is five. This result indicates that the film thickness of the TiN film 21 on the side wall of the contact window 14 increases as the number of times of etching back increases, the film quality increases, and the barrier property improves.

In the present invention, the contact window 14 is made of TiN by a flattening step by at least one etching back.
A film may be formed, and if the film is formed a plurality of times, the film thickness is further increased, the film quality is enhanced, and the barrier property is improved. The contact window 14 may be formed in a region where an electrical contact is made with the base.

In the examples, titanium nitride (Ti
Although N) is used, it can also be applied to commonly used barrier metals.

Furthermore, the thickness of the barrier metal and the molding conditions can be arbitrarily set according to the wiring metal or the characteristics of the transistor.
It is not limited to the embodiment.

〔The invention's effect〕

As described above, according to the present invention, a contact window is formed on a region where an electrical contact is made with a base, and a barrier metal is formed by using a planarization process by anisotropic etching on the contact window. In addition, the thickness of the barrier metal on the side wall of the contact window is increased, the film quality is enhanced, and the barrier property is improved.

[Brief description of the drawings]

1 (a) to 1 (e) are cross-sectional views of a manufacturing process of an embodiment of the present invention, FIG. 2 is a cross-sectional view of an electrode portion of the embodiment of the present invention, and FIGS. FIG. 4 is a cross-sectional view of an electrode part for testing the barrier property of the example, FIG. 4 is a view showing a test result of the barrier property of the embodiment of the present invention, and FIG. 5 is a cross-sectional view of a conventional electrode wiring part. In the figure, 11 is a silicon substrate, 12 is a diffusion region, 13 is a silicon oxide (SiO ₂ ) film, 14 is a contact window, 15 is a first TiN film, 16 is a resist film, 17 is a TiN film, and 20 is a crack. Reference numeral 21 denotes a TiN film, and 22 denotes a pure aluminum wiring film.

Claims (1)

(57) [Claims] A step of forming a contact window in an insulating film on a region where an electrical contact with a base is formed; and a step of forming a first barrier metal film grown on the contact window. A step of flattening the surface of 15) with a film of an organic material (16), and a first barrier metal film (15) using anisotropic etching
When performing a flattening step by etching at least once, the first barrier metal film (15) is left on the insulating film (13), and the barrier metal is formed on the side wall portion serving as a step of the contact window (14). Manufacturing a semiconductor device, comprising: leaving a film (15) in a grown state; and depositing a second barrier metal film (17) at least once on the first barrier metal film (15). Method.