JPH04284668A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor device by a method wherein a semiconductor substrate is prevented from reacting with a wiring layer and a burrier layer for preventing a contact failure from being generated is provided. CONSTITUTION:A semiconductor device is constituted in such a way as to have a process wherein an insulating film (an SiO2 film) 3 is formed on a semiconductor Si substrate 1 with an element (an impurity region) 2 formed therein and a contact hole 4 is formed in the film 3, a process wherein conductor multilayer films 5, 6 and 7 consisting of a first titanium(Ti) film 5 which is connected to the substrate 1, a titanium nitride(TiN) film 6 and a second titanium(Ti) film 7 are formed in the hole 4, a process wherein the film 7 is all or partially oxidized to form a titanium oxide(TiO2) film 8 and a process for forming a wiring layer (an Al layer) 9 on the film 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a semiconductor device in which a wiring layer is formed on a semiconductor substrate via a barrier layer and a method of manufacturing the same.

[0002] On a large number of elements formed on a semiconductor substrate,
Usually, a wiring layer of Al or the like is formed via an interlayer insulating film. The wiring layer is connected to the semiconductor substrate within a contact hole formed in an interlayer insulating film.

By the way, as elements formed on Si substrates become smaller and devices become more highly integrated, problems may arise in which Al in the wiring layer reacts with Si in the substrate, causing bond breakdown.

[0004] Therefore, in recent years, a barrier layer has been provided in the through hole in order to prevent the reaction between the Al wiring layer and the Si substrate.

[0005]

2. Description of the Related Art FIGS. 2(a) to 2(d) are sectional views showing a conventional example in the order of steps. The conventional example will be described below with reference to these figures.

FIG. 2(a) A SiO2 film 3 is formed as an interlayer insulating film on a Si substrate 1 on which a reference element (impurity region) 2 is formed, and the SiO2
A contact hole 4 is formed in the film 3 to expose the element 2.

FIG. 2(b) A titanium (Ti) film 5 and a titanium nitride (TiN) film 6 are formed in this order over the entire surface by a reference sputtering method.

Refer to FIG. 2(c). This substrate is placed in a heating furnace and heated at 450° C. for about 30 minutes in an atmosphere containing oxygen and nitrogen.
A titanium oxynitride (TiNO) film 10 is formed on the surface of the iN film 6.

FIG. 2(d) An Al layer 9 is formed on the reference TiNO film 10 as a wiring layer. The Ti film 5 and TiN film 6 form a so-called barrier layer, and
Maintaining electrical continuity between the l layer 9 and the Si substrate 1, and keeping the Al layer 9
However, since the function of preventing the reaction between Al and Si is not sufficient, it is not possible to improve the function by forming the TiNO film 10. It is being done.

However, even in this case, when the semiconductor device is completed through subsequent steps including heating, the barrier layer may lose its function. FIG. 3 is a cross-sectional view showing the conventional problem.

In the process after forming the Al layer 9, various types of heating are performed at a temperature that does not melt Al, but in the heating process, the barrier layer does not function sufficiently and the Si of the Si substrate 1 is exposed to the wiring in the contact hole area. It melts into layer 9, and conversely it melts into wiring layer 9.
Al enters the Si substrate 1 through the barrier layer and forms alloy spikes 11, causing contact failure, and may also penetrate through the impurity region 2 and cause junction breakdown.

As devices become more highly integrated, impurity regions 2
Since alloy alloys tend to be formed thinner and thinner, the occurrence of alloy spikes 11 becomes a serious problem. Even if we try to form a TiNO film 10 with high barrier properties by controlling the temperature, time, and atmosphere in the heating furnace in order to increase the effect as a barrier layer, the quality is not stable and it is difficult to achieve the desired effect as a barrier layer. I can't give it to you.

[0013]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to provide a semiconductor device having a barrier layer that has higher barrier properties and can be formed stably, and a method for manufacturing the same.

[0014]

[Means for solving the problem] Figures 1(a) to (e)
FIG. 3 is a step-by-step cross-sectional view showing an example. The above problem is solved in a semiconductor device having a semiconductor substrate 1, a wiring layer 9 formed on the semiconductor substrate 1, and barrier layers 5, 6, 8 interposed in contact with the semiconductor substrate 1 and the wiring layer 9. The barrier layers 5, 6, and 8 include a three-layer structure consisting of a titanium film 5, a titanium nitride film 6, and a titanium oxide film 8. The solution is to provide a semiconductor device with a thickness that maintains electrical conduction and prevents chemical reactions between the two.

[0015] Furthermore, the semiconductor device is solved by a semiconductor device in which the semiconductor substrate 1 is a Si substrate, and the wiring layer 9 is an Al layer or an alloy layer containing Al as a main component. There is also a step of forming an insulating film 3 on the semiconductor substrate 1 on which the element is formed, forming a contact hole 4 in the insulating film 3, and forming a first titanium film in the contact hole 4 to be connected to the semiconductor substrate 1. Steps of forming conductor multilayer films 5, 6, and 7 by a film 5, a titanium nitride film 6, and a second titanium film 7, and forming a titanium oxide film 8 by oxidizing all or part of the second titanium film 7. The problem is solved by a method for manufacturing a semiconductor device, which includes a step of forming a wiring layer 9 on the titanium oxide film 8.

[0016]

[Operation] Titanium oxide film 8 is titanium oxynitride (TiNO)
It has higher barrier properties than membranes and can easily provide stable quality.

Furthermore, the titanium oxide film 8 can be formed to a thickness that maintains electrical continuity between the semiconductor substrate 1 and the wiring layer 9 and prevents chemical reactions between the two. Further, the semiconductor substrate 1 is a Si substrate, and the wiring layer 9 is A
When a barrier layer containing the titanium oxide film 8 is formed in a semiconductor device which is an L layer or an alloy layer mainly composed of Al, the effect is significant.

Furthermore, the titanium oxide film 8 is first formed by forming the titanium film 7.
For example, if the surface is oxidized,
It can be formed easily and stably by performing high-temperature, high-speed heating in an oxygen-containing atmosphere.

By the presence of such a titanium oxide film 8, it is possible to eliminate the occurrence of alloy spikes, prevent junction breakdown, and prevent contact failure.

[0020]

Embodiment FIGS. 1(a) to 1(e) are sectional views showing an embodiment in the order of steps, and the embodiment will be described below with reference to these figures.

FIG. 1(a) A Si substrate 1 on which a reference element (impurity region) 2 is formed is coated with S with a thickness of 0.8 to 1 μm by CVD as an interlayer insulating film.
An iO2 film 3 is formed, and a contact hole 4 exposing the element 2 is formed in the SiO2 film 3.

FIG. 1(b) A first titanium (Ti) film 5 with a thickness of several hundred to 1,000 Å and a titanium nitride (TiN
) The films 6 are deposited in this order. The process up to this point is the same as the conventional example.

FIG. 1(c) A second titanium (Ti) film 7 having a thickness of, for example, 100 Å is deposited over the entire surface by a reference sputtering method.

Referring to FIG. 1(d), this substrate was heated at high temperature and high speed (Rapid Thermal).
The second Ti film 7 is oxidized to titanium oxide (TiO2) by heating at 800 to 950°C for 20 to 30 seconds in a mixed atmosphere of oxygen and nitrogen.
) to change the quality of the film 8.

[0025] Also, the second Ti film 7 is coated in advance with a thickness of 200
The surface of the second Ti film 7 is formed to a thickness of ~300 Å and heated at high temperature and high speed in a mixed atmosphere of oxygen and nitrogen to form a TiO2 film with a thickness of several tens to hundreds of Å.
The film 8 may be formed, and an extremely thin TiNO film connected to the second Ti film 7 may be formed below it.

Referring to FIG. 1(e), an Al layer 9 having a thickness of, for example, 1 μm is formed as a wiring layer on the TiO2 film 8 by sputtering.

The Ti film 5 thus formed, Ti
The N film 6, the TiO2 film 8, and the TiNO film serve as a so-called barrier layer that maintains electrical continuity between the Al layer 9 and the Si substrate 1 and prevents the Al of the Al layer 9 from reacting with the Si of the Si substrate 1. When the semiconductor device was completed through the subsequent process including heating, no alloy spikes were observed.

The thickness of the TiO2 film 8 is several tens to 200 Å.
The optimum thickness is 500 Å or more, and although the effect of preventing the reaction between Al and Si becomes greater, electrical conductivity decreases, which is not desirable.

Further, in the embodiment, an example in which an Al layer is used as the wiring layer 9 has been described, but for example, an alloy layer containing a small amount of Si or a small amount of Si, Cu, etc. can also be used. Note that, according to the present invention, a titanium silicide layer is inevitably formed due to the reaction between Si of the Si substrate 1 and Ti of the first Ti film 5, but this is not a substantial problem for the present invention.

[0030]

[Effect of the invention] As explained above, according to the present invention,
This method has the remarkable effect of preventing junction breakdown due to the reaction between Si of the semiconductor substrate 1 and Al of the wiring layer 9 to produce alloy spikes, and also preventing poor contact between the semiconductor substrate 1 and the wiring layer 9. can play.

The present invention contributes to increasing the density of semiconductor devices.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(e) are process-order cross-sectional views showing an example.

FIGS. 2(a) to 2(d) are step-by-step sectional views showing a conventional example.

FIG. 3 is a sectional view showing a conventional problem.

[Explanation of symbols]

1 is a semiconductor substrate, Si substrate 2 is an element, impurity region 3 is an insulating film, SiO2 film 4 is a contact hole 5 is a barrier layer, and a Ti film, the first Ti film 6 is a barrier layer. The TiN film 7 is a barrier layer and a Ti film, the second Ti film 8 is a barrier layer, the TiO2 film 9 is a wiring layer, the Al layer 10 is a barrier layer, and the TiNO film 11 is a barrier layer. alloy spike

Claims (3)

[Claims] [Claim 1] A semiconductor substrate (1), a wiring layer (9) formed on the semiconductor substrate (1), and a barrier layer interposed in contact with the semiconductor substrate (1) and the wiring layer (9). (5, 6, 8), wherein the barrier layer (5, 6, 8) is a titanium film (5),
It includes a three-layer structure consisting of a titanium nitride film (6) and a titanium oxide film (8), and the titanium oxide film (8) maintains electrical continuity between the semiconductor substrate (1) and the wiring layer (9) and connects both 1. A semiconductor device characterized by having a thickness that prevents chemical reactions between the semiconductor devices. 2. The semiconductor device according to claim 1, wherein the semiconductor substrate (1) is a Si substrate, and the wiring layer (9) is an Al layer or an alloy layer containing Al as a main component. [Claim 3] A semiconductor substrate (1) on which an element is formed.
A step of forming an insulating film (3) on the insulating film (3), forming a contact hole (4) in the insulating film (3), and forming a first titanium film in the contact hole (4) to be connected to the semiconductor substrate (1). A step of forming a conductor multilayer film (5, 6, 7) consisting of a film (5), a titanium nitride film (6), and a second titanium film (7), and a step of forming a conductor multilayer film (5, 6, 7) by forming the second titanium film (7) in whole or in part. 1. A method for manufacturing a semiconductor device, comprising the steps of partially oxidizing a titanium oxide film (8) to form a titanium oxide film (8), and forming a wiring layer (9) on the titanium oxide film (8).