JPH01238043A - Method of forming wiring - Google Patents

Abstract

PURPOSE:To avoid particles by a method wherein, after a wiring layer is formed, ions of metal or the like are implanted into the contact surface between a contact region and the wiring layer to break a natural oxide film in the contact surface. CONSTITUTION:An aluminum wiring layer 3 is formed on the surface of an oxide film 2 on a semiconductor substrate 1. If a contact hole 6 is formed by photoetching after an interlayer insulating film 5 is formed, the contact region 7 of the wiring layer 3 exposed by the contact hole 6 is formed. Then a second layer wiring 8 is formed. If titanium ions Ti<+> are implanted into the contact boundary between the wiring layer 3 and the wiring layer 8, a natural oxide film 4 existing in the contact boundary is broken. After that, the wiring layer 8 is patterned. With this constitution, the possibility of scattering of the broken natural oxide film onto the wiring layer surface can be avoided and a contact resistance can be reduced without increasing the number of particles.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Field of industrial application B1 Overview of the invention C0 Prior art 1 Problems to be solved by the invention E1 Means for solving the problems F1 Effects G. Examples [Figure 1] H9 Effects of the invention (A , Industrial Application Field) The present invention relates to a wiring forming method, and more particularly to a wiring forming method for forming a wiring layer connected to a contact area through an opening in an insulating layer.

(B. Summary of the Invention) In the above wiring forming method, the present invention prevents the generation of particles from the natural oxide film on the contact surface between the wiring layer and the contact area connected to the wiring layer through the opening of the insulating layer. In order to destroy the contact surface without causing damage, ions of metal or the like are implanted into the contact surface after the wiring layer is formed to destroy the natural oxide film on the contact surface.

(C, prior art) As semiconductor integrated circuits become more highly integrated, aluminum multilayers (
For example, 2 to 4 layers) wiring is required. Connections between the upper and lower wiring layers are made through contact holes formed in the interlayer insulating layer.

By the way, the contact surface between the upper and lower wiring layers is coated with alumina Al2O.
Three natural oxide films are formed, which becomes a factor that increases the contact resistance between wiring layers. This is because the aluminum film forming the lower wiring layer is patterned between the time aluminum is deposited to form one wiring layer and the upper wiring layer made of aluminum, for example, is formed. A photo-etching process for forming the insulating layer, a photo-etching process for patterning the insulating layer, etc. are required, and during these various processes, the surface of the underlying wiring layer may be oxidized. This is because

Therefore, one possibility is to perform RF etching cleaning on the lower wiring layer using Ar ions in the vacuum apparatus in which the upper wiring layer is deposited, after forming the lower wiring layer and before depositing the upper wiring layer. It is. This technique of cleaning the surface of the wiring layer of the F layer by RF etching using Ar ions and then forming the upper wiring layer was introduced in Japanese Patent Laid-Open No. 124431/1984 as a method for preventing hillocks on the surface of the lower wiring layer. However, it is also possible to remove the natural oxide film on the surface of the underlying wiring layer made of aluminum.

(D. Problem to be Solved by the Invention) By the way, if the surface of the lower wiring layer is irradiated with Ar or other ions for cleaning after the formation of the lower wiring layer and before the formation of the upper wiring layer, the surface of the lower wiring layer may be cleaned. With the generation of plasma, the particle level on the semiconductor substrate increases. Therefore, there was a problem in that miniaturization of semiconductor devices and improvement in yield were hindered.

The present invention has been made to solve these problems, and is designed to remove particles from the natural oxide film on the contact surface of the contact area with the wiring layer, which is connected to the wiring layer through the opening of the insulating layer. The purpose is to be able to destroy it without causing any damage.

(E. Means for Solving Problems) In order to solve the above-mentioned problems, the wiring formation method of the present invention includes the above-mentioned wiring formation method for forming a wiring layer connected to a contact area through an opening in an insulating layer. The method is characterized in that after the wiring layer is formed, ions of metal or the like are injected into the contact surface between the contact area and the wiring layer to destroy the natural oxide film on the contact surface.

(F. Effect) According to the wiring forming method of the present invention, after the wiring layer is formed, ions of metal or the like are implanted into the contact surface between the wiring layer and the contact area below it, so that the natural Since the oxide film is destroyed, there is no risk of the destroyed natural oxide film scattering onto the surface of the wiring layer.

Therefore, it is possible to reduce the contact resistance without increasing the number of particles.

(G, Example) [FIG. 1] Hereinafter, the wiring forming method of the present invention will be explained in detail according to the illustrated example.

FIGS. 1A to 1D are cross-sectional views showing one embodiment of the wiring forming method of the present invention in the order of steps.

(A) An aluminum wiring layer 3 is formed on the surface of the oxide film 2 on the semiconductor substrate 1. 4 is a natural oxide film naturally formed on the surface of the aluminum wiring layer 3.

Next, an interlayer insulating layer 5 is formed by atmospheric pressure CVD and then photoetched to form a contact hole 6. The region exposed by the contact hole 6 in the wiring layer 3 is a contacted region 7 . Figure 1 (A) shows contact hole 6.
The state after formation is shown.

(B) Next, as shown in FIG. 3B, the wiring layer 8 of the second layer opening is formed. The wiring layer 8 is formed by bias sputtering or the like so as to be able to fill the minute contact hole 6, and to cope with the miniaturization of the element by warping.

(C) Next, as shown in the same figure (C), titanium ion TI
By implanting + into the contact surface between the wiring layer 3 and the wiring layer 8 by ion implantation, the natural oxide film 4 existing on the contact surface is destroyed. In this case, it is necessary to set the ion implantation conditions so that the energy from ion implantation is concentrated not on the surface of the wiring layer 8 but on the contact surface between the wiring layer 3 and the wiring layer 8 where the native oxide film 4 is present. It is.

FIG. 1D shows the state after the natural oxide film 4 (l!) has been destroyed by ion implantation. Thereafter, the wiring layer 8 will be patterned.

After the wiring layer 8 is deposited by, for example, a bias sputtering method, the natural oxide film 4 existing between the wiring layer 8 and the wiring layer 3 below it is destroyed by the implanted metal ions. The contact resistance between 3 and 8 can be reduced without generating particles.

Since titanium ions Ti+ are implanted as metal ions, there is no possibility that the reliability of the aluminum wiring layer 3 or 8 will deteriorate. That is, attempts have been made for several years to add impurities to aluminum films in order to suppress electromigration, and it can be said that, in principle, adding impurities to aluminum reduces the reliability of aluminum. However, it has been confirmed that the reliability of the aluminum film does not deteriorate even if titanium Ti, copper Cu, nickel Ni, magnesium Mg, and chromium Cr are added to the aluminum film. Therefore, by implanting titanium ions Ti+ as in this embodiment, the natural oxide film 4 can be destroyed without deteriorating the reliability of the aluminum wiring layer. Of course, copper ion C is used instead of titanium ion Ti+.
u'', nickel ion Ni'', magnesium ion Mg
The native oxide film 4 may be destroyed by implanting +. It goes without saying that aluminum ions ALL+ may also be implanted.

Incidentally, argon, which is commonly used for modifying silicon films, is not preferable because it generates voids in the aluminum film. Further, silicon Si is not preferable because it causes the formation of Si nodules in the aluminum film.

Incidentally, by repeating the above steps, it is possible to destroy the natural oxide film on the surface of each wiring layer for each wiring layer of a multilayer wiring having a larger number of layers than three or four layers without generating particles.

(H, Effects of the Invention) As described above, the wiring forming method of the present invention includes the steps of forming an insulating layer having an opening on the contact area;
A step of forming a wiring layer connected to the contact region through the opening, and a step of destroying the natural oxide film on the beneficial contact surface by implanting ions into the contact surface between the wiring layer and the contact region. It is characterized by producing offspring.

Therefore, according to the wiring forming method of the present invention, after the wiring layer is formed, ions of metal or the like are implanted into the contact surface between the wiring layer and the contact area below it to remove the natural oxide film present on the contact surface. Since it is destroyed, there is no risk of the destroyed native oxide film being scattered onto the surface of the wiring layer. Therefore, contact resistance can be reduced without increasing particles.

[Brief explanation of the drawing]

FIGS. 1A to 1D are cross-sectional views showing one embodiment of the wiring forming method of the present invention in the order of steps. Explanation of the symbols 4... Natural oxide film, 5... Insulating layer, 6... Opening, 7... Contact region, 8... Wiring layer.

Claims (1)

[Claims] (1) A step of forming an insulating layer having an opening over the contact region; a step of forming a wiring layer connected to the contact region at the opening; and a step of forming an insulating layer having an opening over the contact region; a step of destroying the natural oxide film on the contact surface by implanting ions into the contact surface;