JP2841457B2 - Method of forming aluminum film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming an aluminum film such as an aluminum wiring layer formed on a semiconductor device.

[Summary of the Invention] The present invention improves the fine workability, flat surface morphology and step coverage (step coverage) of an aluminum or aluminum alloy film formed on a substrate surface with the increase in the density of a semiconductor integrated circuit. Therefore, by performing ion implantation using an ion species that does not become an impurity on the substrate to form a reaction site, and forming an aluminum film from the upper surface of the reaction site by a chemical vapor deposition method, controllability and stepability are improved. The object is to provide a dense and highly reliable aluminum film with good coverage.

[Prior art] At present, aluminum or aluminum alloy films are
(Large-scale integrated circuit) It is inevitable as wiring, and with the increase in the density of LSIs, improvements in fine workability, flat surface morphology, step coverage (step coverage), and the like are demanded.

Conventionally, as a method of forming this kind of aluminum film,
An aluminum sputtering method is known, but in the sputtering method, the growth species enter the substrate in a place where the mean free path of the growth species is long and the growth species have a relatively uniform direction. In some cases, the coverage at the step is generally poor.

On the other hand, as a method of forming an aluminum film for solving the problem of coverage at the step portion as described above, for example,
A method of performing a CVD method using Al (C ₄ H ₉ ) ₃ (triisobutylaluminum) as a source gas is known.

Other conventional methods include, for example, "Monthly Semico
A method of forming an aluminum film using a plasma CVD method as described in “Nductor World 1983.2” is known. In this method, the CVD source is plasma dissociated,
This is to deposit aluminum on a wafer in a plasma CVD apparatus.

[Problem to be Solved by the Invention] However, such a conventional method has the following problems.

First, in the method by the CVD method, the nucleation density on the substrate is low and a rough aluminum film is obtained, and the fine workability,
There is a problem that the flatness and the corrosion resistance are inferior.
In addition, when CVD is performed by exposing the substrate to a vapor such as TiCl ₄ , the controllability deteriorates, and there is also a problem that the film becomes coarse.

In the conventional method using the plasma CVD method, although the controllability is good, various gases contained in the plasma CVD atmosphere are contained in the deposited aluminum film, which affects the reliability of the LSI wiring. Has the problem of causing

The present invention has been made in view of such a conventional problem, and has as its object to obtain a method for forming a dense and highly reliable aluminum film having good step coverage.

[Means for Solving the Problems] In view of the above, the present invention provides a method for forming a step portion by performing ion implantation on a surface of the substrate having the step portion formed thereon, using an ion species which does not become an impurity with respect to the substrate. The solution is to form a reaction site on the entire region including the substrate and to uniformly deposit and form an aluminum film on the entire surface by chemical vapor deposition from the upper surface of the reaction site.

[Action] The reaction sites formed on the substrate surface have a high bonding property with the aluminum deposited on the substrate surface by the CVD method, so that the controllability of the formed aluminum film is improved, and the aluminum film is densified. Even if there is a steep step portion, the step coverage is improved, and an aluminum film in which the aluminum wiring is not disconnected can be manufactured.

EXAMPLES Hereinafter, details of a method for forming an aluminum film according to the present invention will be described based on examples shown in the drawings.

This embodiment shows an example in which the present invention is applied to a case where an aluminum film 2 is formed on a silicon substrate 1 as a base.

First, FIG. 1A shows a silicon substrate 1 having a step portion A formed on its surface, which is used as a substrate for various semiconductor devices. The shape, structure and position of the step portion A are as follows. It follows the design as appropriate.

Next, an ion species that does not become an impurity, for example, titanium (Ti) is shallowly ion-implanted into the surface of the silicon substrate 1 as shown in FIG.
A reaction site 1a is formed on the entire surface of the silicon substrate 1. The reaction site 1a is, of course, also formed at the step A. The ion implantation into the step A can be performed by changing the ion implantation angle, or by adding silicon to the plasma in which the implanted ions exist. Processing such as exposing the surface of the substrate 1 may be performed.

Next, the silicon substrate 1 on which the reaction site 1a as described above is formed over the entire surface is arranged in a known CVD apparatus,
Al (C ₄ H ₉ ) ₃ was used as the source gas, the temperature was 260 ° C.,
The aluminum film 2 is formed to a predetermined thickness by performing CVD at a pressure of 60 Pa.

As described above, if reaction sites are formed in advance on the surface of the silicon substrate 1 before performing the CVD for forming the aluminum film 2, the adhesion of the growth species (Al) to the silicon substrate 1 is increased, and the film is free from unevenness. Adhesion becomes possible. For this reason,
As shown in FIG. 1C, the aluminum film 2 having good coverage and denseness can be formed even at the step portion A.

In particular, when the present invention is applied, the reliability is improved without breaking the aluminum wiring even in a steep step portion, and application to a multilayer wiring structure and application to a contact hole are also promising.

Although the embodiment has been described above, the present invention is not limited to this, and various design changes can be made.

For example, in the above embodiment, the silicon substrate 1 is used as the base, but it is needless to say that the silicon substrate 1 can be applied to an insulating film such as SiO ₂ or an aluminum film manufacturing process of various semiconductor devices.

Further, in the above embodiment, titanium (T
The reaction site was formed by ion implantation of i), but the same effect can be obtained by implanting various ions such as tungsten (W), carbon (C), and silicon in addition to titanium. .

Further, in the above embodiment, the aluminum film 2 was formed by the CVD method. However, for example, an aluminum silicide (Al-Si) film, aluminum-silicon-copper (AlSiC)
u) Of course, the present invention may be applied to the process of forming an aluminum alloy film such as a film.

[Effects of the Invention] As is apparent from the above description, in the method for forming an aluminum film according to the present invention, the ionic species which do not become impurities with respect to the substrate are formed on the surface of the substrate having the step formed on the surface. A reaction site is formed on the entire area of the substrate including the step by performing ion implantation using, and then an aluminum film is formed on the surface of the substrate by a CVD method.
There is an effect that a dense aluminum film can be formed with good controllability, good step coverage, and no break in the aluminum wiring even at a steep step portion.

Therefore, there is an effect that the fine workability, flat surface morphology, corrosion resistance and the like of the aluminum film can be achieved by the CVD method.

[Brief description of the drawings]

1A to 1C are process diagrams showing an embodiment of a method for forming an aluminum film according to the present invention. 1 ... silicon substrate (base), 1a ... reaction site, 2 ...
... Aluminum film.

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 21/28-21/288 H01L 21/3205 H01L 21/3213 H01L 21/44-21/445 H01L 21 / 768 H01L 29/40-29/51

Claims (1)

(57) [Claims] 1. A reaction site is formed on the entire surface of a substrate including a step by performing ion implantation on the surface of the substrate having a step on the surface using an ion species that does not become an impurity with respect to the substrate. A method for forming an aluminum film in a semiconductor device, wherein an aluminum film is uniformly deposited on the entire surface by chemical vapor deposition from the upper surface of the reaction site.