JPH0837236A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the interface state density of a semiconductor substrate from being insufficiently eliminated, by bring a metal wiring layer into contact with the semiconductor substrate or other metal wiring films through a plug film having a base of a tungsten silicide film as an adhesion layer. CONSTITUTION:An adhesion layer 6, composed of tungsten silicide, formed by CVD, enhances the adhesion of a plug film 7. The plug film 7, composed of tungsten, is formed by filling contact holes 5 using the adhesion layer 6 as a base. A metal wiring layer 8 is electrically connected with a semiconductor substrate 1 through the plug film 7. This prevents the insufficient elimination of the interface state density of a semiconductor substrate, which used to be the case because hydrogen is occluded in an adhesion layer to be the base of a metal layer. The above-mentioned method improves the characteristics of semiconductor substrates and the stability of such characteristics, and prevents an adhesion layer from being stripped off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, particularly a semiconductor device having a metal wiring film, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor device having a metal wiring film made of, for example, aluminum, contact between the metal wiring film and a semiconductor substrate is often made via a metal CVD film. And the metal CVD film is
In most cases, it is formed by a blanket tungsten CVD method and usually has an adhesion layer as a base. And in the past, the adhesion layer was generally formed of a titanium-based metal.

[0003]

By the way, in the prior art, since the adhesion layer which is the base of the metal CVD film for making contact between the metal wiring film and the semiconductor substrate is formed of titanium-based metal, first of all, There is a problem that it is difficult to sufficiently reduce the interface state even with sintering. Then, when the cause was investigated, the titanium-based metal had a hydrogen storage property, and therefore, for example, hydrogen in the wiring made of aluminum or hydrogen in the atmosphere at the time of sintering could cause the semiconductor substrate and the gate insulating film, for example. It was found that hydrogen that is stored in the adhesion layer made of the titanium-based metal before reaching the interface of and contributes to the disappearance of the interface state is reduced.

If this is left as it is, it becomes difficult to reduce the dark current and the stability of the threshold voltage is prevented from being improved. Specifically, the dark current causes a decrease in the record holding ability in the case of a semiconductor device such as a DRAM, and in the case of a semiconductor device such as a CCD type solid-state image sensor,
This may cause image defects during high temperature darkness. Second
In addition, during the CVD for forming the blanket tungsten film, the F gas in WF ₆ which is the source gas reacts with titanium, so that the titanium-based metal is easily peeled off. Specifically, peeling off from the periphery of the semiconductor wafer and peeling off inside the contact hole are likely to occur.

The adhesion layer made of titanium-based metal is generally formed by sputtering, but since sputtering has poor step coverage, a contact layer is formed on the inside of the contact hole as the contact hole becomes finer and the aspect ratio becomes higher. It is difficult to form them in close contact with each other, and therefore, there is a problem that the function as an adhesion layer cannot be sufficiently fulfilled. Further, although this adhesion layer also has a role as a barrier metal, it is also a problem that it cannot fully function as a barrier metal due to its poor adhesion to the base. This is because a device failure such as a junction leak is likely to occur when the function as the barrier metal deteriorates. The third problem is poor step coverage due to the formation of the adhesion layer of titanium-based metal by sputtering.

The present invention has been made to solve such a problem, and it is considered that hydrogen is occluded by an adhesion layer which is a base of a metal layer, and the elimination of the interface state of the semiconductor substrate becomes insufficient. To prevent the occurrence of peeling of the adhesive layer by further improving the characteristics and stability of the characteristics, and further preventing the step coverage of the adhesive layer from becoming worse, thereby ensuring close contact with the base of the adhesive layer. The purpose is to prevent the deterioration of the adhesiveness and the deterioration of the function of the adhesion layer.

[0007]

According to another aspect of the present invention, there is provided a semiconductor device in which a contact between a metal wiring film and a semiconductor substrate or another metal wiring film is contacted via a plug film having a tungsten silicide film as an adhesion layer as an underlying layer. It is characterized by A semiconductor device according to a second aspect is the semiconductor device according to the first aspect, further comprising a plug film made of tungsten having a tungsten silicide film as an adhesion layer and serving as an underlying layer for contacting the metal wiring film with the semiconductor substrate or another metal wiring layer. It is characterized in that the contact hole or the via hole selectively formed in the interlayer insulating film is filled.

A method for manufacturing a semiconductor device according to a third aspect is the method for manufacturing a semiconductor device according to the second aspect, wherein the semiconductor substrate or the metal is formed on the interlayer insulating film for insulating between the metal wiring film and the semiconductor substrate or between the metal wiring films. After selectively forming a contact hole or a via hole in which the wiring film is exposed, first, a tungsten silicide film to be an adhesion layer is formed by CVD, and then a tungsten film to be a plug film is formed, and then the contact hole or the via hole is formed. It is characterized in that the tungsten film and the tungsten silicide film outside the via hole are removed by etching back.

[0009]

According to the semiconductor device of the first aspect, the adhesion layer which is the base of the plug film is made of tungsten silicide,
Since tungsten silicide has no hydrogen storage capacity for titanium-based metals, the concentration of hydrogen that can be stored in the adhesion layer becomes low, and as a result hydrogen that reaches the interface of the semiconductor substrate and contributes to the disappearance of the interface level is generated. Will increase. Therefore, the dark current can be reduced and the threshold voltage can be stabilized. Since tungsten silicide is selected as the material for forming the adhesion layer, peeling of the adhesion layer does not occur even if the plug film is formed of the tungsten film. Because tungsten is a blanket tungsten C
This is because WF _6, which is the source gas when forming by VD, does not react with the tungsten silicide forming the adhesion layer. Further, the tungsten silicide film has less reactivity with polycrystalline silicon, single crystal silicon, or the like because it contains silicon as compared with tungsten formed by PVD, which is an allowance for increasing the heat treatment temperature. This is preferable because it can increase the degree.

According to the semiconductor device of the second aspect, since the plug film and the adhesion layer are formed so as to fill the contact hole or the via hole, the metal wiring film / semiconductor substrate without causing a step on the semiconductor surface. It is possible to make contact between the metal wiring films or between the metal wiring films.

According to the semiconductor device manufacturing method of the third aspect, since the tungsten silicide forming the adhesion layer is formed by CVD after the contact hole or the via hole is formed, the titanium nitride film is formed by sputtering as the conventional adhesion layer. It is possible to prevent the step coverage from being deteriorated as in the case, to prevent the adhesion of the adhesion layer to the underlying layer from being deteriorated, and to prevent the original function of the adhesion layer from being deteriorated. After forming the adhesion layer made of tungsten silicide by CVD, the tungsten forming the plug film is blanket tungsten CV.
Even if it is formed by D, there is no possibility that the adhesive layer will be peeled off by WF ₆ supplied at the time of CVD. This is because the source gas WF ₆ has no reactivity with the tungsten silicide forming the adhesion layer, and the adhesion layer made of tungsten silicide is not likely to be deteriorated by the source gas WF ₆ .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The semiconductor device of the present invention and its manufacturing method will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a sectional view showing one embodiment of the semiconductor device of the present invention. In the drawings, 1 is a semiconductor substrate, 2 is a gate insulating film, 3 is a gate electrode made of, for example, polysilicon, 4 is an interlayer insulating film made of a SiO ₂ -based material, and 5 is selectively formed on the interlayer insulating film 4. It is a contact hole. 6 is an adhesion layer made of tungsten silicide formed by the CVD method,
It plays the role of enhancing the adhesion of the plug film (7) described below. The adhesion layer 6 is made of dichlorosilane SiH ₂ Cl.
_It is preferable to form it by CVD at a high temperature of about 500 to 700 ° C. using a ₂ type process gas because the adhesion with the interlayer insulating film 4 made of a SiO ₂ type insulating film becomes very good.

Reference numeral 7 is a plug film made of tungsten and is formed so as to fill the contact hole 5 with the adhesion layer 6 as a base. This formation can be performed by the blanket tungsten CVD method. A metal wiring film 8 is electrically connected to the semiconductor substrate 1 via the plug film 7 and is made of, for example, aluminum.

The semiconductor device shown in FIG. 1 is different from the conventional semiconductor device in that the adhesion layer 6 as the base of the plug film 5 made of tungsten filling the contact hole 5 is formed of tungsten silicide instead of titanium-based metal. That is. Therefore, according to such a semiconductor device,
Since tungsten silicide does not have a hydrogen storage property for titanium-based metals, the concentration of hydrogen that can be stored in the adhesion layer 6 becomes low, and thus hydrogen that reaches the interface of the semiconductor substrate and contributes to the disappearance of the interface level is generated. Will increase. Therefore, the dark current can be reduced and the threshold voltage can be stabilized.

Since tungsten silicide is selected as the material for forming the adhesion layer, peeling of the adhesion layer 6 is not likely to occur even if the tungsten film forming the plug film 7 is formed by the blanket tungsten CVD method. This is because WF _6, which is a source gas when tungsten is formed by blanket tungsten CVD, does not react with the tungsten silicide forming the adhesion layer 4. Since the plug film 7 and the adhesion layer 6 are formed so as to fill the contact hole 5, the contact can be established between the metal wiring film 8 and the semiconductor substrate 1 without causing a step on the semiconductor surface. .

2A to 2C are cross-sectional views showing, in the order of steps, essential parts of the method for manufacturing the semiconductor device shown in FIG. (A) After selectively forming a contact hole 5 in the interlayer insulating film 4, a tungsten silicide film 6 to be an adhesion layer is formed over the entire surface. As described above, the tungsten silicide film 6 is entirely formed by using dichlorosilane SiH ₂
It is preferable to perform CVD at a high temperature near 500 to 700 ° C. using a Cl ₂ -based process gas. This is because, first of all, since it is formed by CVD, the step coverage is much better than when it is formed by sputtering, and it is possible to cope with the miniaturization of contact holes and the high aspect ratio accompanying the miniaturization of elements. And secondly dichlorosilane SiH ₂ Cl ₂ at high temperature.
According to CVD using a system-based process gas, SiO ₂
This is because it is possible to form the tungsten silicide film 6 having excellent adhesion to the interlayer insulating film 4 made of a system insulating film. As described above, the good adhesion of the adhesion layer 6 leads to the fact that the peeling is less likely to occur.
FIG. 2A shows a state after the tungsten silicide film 6 is completely formed. In addition, this CVD is performed in 200 to 400
When it is performed at a temperature of ℃, it is possible to cope with filling the via hole.

(B) CV of tungsten silicide film 6
When the entire formation by D is completed, subsequently, as shown in FIG. 2B, a tungsten film 7 to be a plug film is formed by a blanket tungsten CVD method. In this CVD, a WF ₆ type gas is used as a source gas, but since the tungsten silicide forming the adhesion layer does not react with this gas, there is no possibility of peeling at the peripheral portion of the semiconductor wafer or at the contact hole. . (C) Next, by etching back, the tungsten film 7 to be the plug film in the contact hole 5 and the tungsten silicide film 6 to be the adhesion layer underlying the tungsten film 7 are left.
The tungsten film 7 and the tungsten silicide film 6 are removed. As a result, the plug film 7 that completely fills the contact hole 5 and does not protrude from the contact hole 5 is formed using the adhesion layer 6 as a base.

According to such a method of manufacturing a semiconductor device, since the tungsten silicide film forming the adhesion layer 4 is formed by CVD after the contact hole 5 is formed, when a titanium silicide film is formed as a conventional adhesion layer by sputtering. As described above, it is possible to prevent the step coverage from being deteriorated, and thus prevent the adhesion of the adhesion layer 4 to the base from being deteriorated and prevent the original function of the adhesion layer 4 and the function as a barrier metal from being deteriorated. You can Then, after the adhesion layer 4 made of tungsten silicide is formed by CVD, there is no possibility that the adhesion layer 4 is peeled off by the source gas WF ₆ supplied when the tungsten forming the plug film 7 is formed by blanket tungsten CVD. Because the source gas WF ₆
This is because the fluorine F therein has no reactivity with the tungsten silicide forming the adhesion layer, and there is no possibility that the tungsten silicide will be deteriorated by the source gas WF ₆ .

The steps shown in FIGS. 2A to 2C are as follows.
For example, it is advisable to carry out continuously using a multi-chamber as shown in FIG. That is, the CVD for forming tungsten silicide in the chamber C1 and the CVD for forming the tungsten film forming the plug film in the chamber C2.
Then, in the chamber C3, the tungsten film and the tungsten silicide film are sequentially etched back. In addition, L is a load part and U is an unload part. In the above-described embodiment, the contact between the semiconductor substrate 1 and the metal wiring film 8 is made by the plug film 7 formed in the contact hole 5 of the interlayer insulating film 4, but the present invention is not limited to this. The contact between the metal wiring films of different layers insulated via the via can also be implemented by a mode in which the plug film is used as the base of the adhesion layer formed in the via hole.

[0020]

According to the semiconductor device of claim 1, the contact between the metal wiring film and the semiconductor substrate or another metal wiring film is
It is characterized in that it is formed through a plug film having a tungsten silicide film as an adhesion layer as an underlying layer. Therefore,
According to the semiconductor device of the first aspect, the adhesion layer that is the base of the plug film that makes contact is made of tungsten silicide, and since the tungsten silicide does not have a hydrogen storage property for titanium-based metal, the adhesion layer can store it. The concentration of hydrogen becomes low, and more hydrogen reaches the interface of the semiconductor substrate and contributes to the disappearance of the interface state. Therefore, the dark current can be reduced and the threshold voltage can be stabilized.

Since tungsten silicide is selected as the material for forming the adhesion layer, peeling does not occur in the adhesion layer even if the plug film is formed of the tungsten film. Because it is a source gas of W when blanket tungsten CVD is used to form tungsten.
This is because F ₆ does not react with the tungsten silicide forming the adhesion layer.

According to another aspect of the semiconductor device of the present invention, a plug film made of tungsten having a tungsten silicide film as an adhesion layer as an underlying layer is formed so as to fill a contact hole or a via hole selectively formed in the interlayer insulating film. It is characterized by Therefore, according to the semiconductor device of the second aspect, since the plug film and the adhesion layer are formed so as to fill the contact hole or the via hole, a step between the metal wiring film and the semiconductor substrate is not caused on the semiconductor surface. Alternatively, the metal wiring films can be contacted with each other.

According to a third aspect of the method of manufacturing a semiconductor device, after a contact hole or a via hole is selectively formed in an interlayer insulating film, a tungsten silicide film as an adhesion layer is first formed by CVD, and then a tungsten silicide film is formed. And then the tungsten film and the tungsten silicide film outside the contact hole or via hole are removed by etchback. Therefore, according to the method of manufacturing a semiconductor device of claim 3, since the tungsten silicide forming the adhesion layer is formed by CVD after the formation of the contact hole or the via hole, when the titanium-based metal is formed by sputtering as the conventional adhesion layer. As described above, it is possible to prevent the step coverage from being deteriorated, prevent the adhesion of the adhesion layer to the base from being deteriorated, and prevent the function of the adhesion layer from being deteriorated. Then, after the adhesion layer made of tungsten silicide is formed by CVD, the source gas W supplied at the time of CVD for forming tungsten forming the plug film
There is no possibility that the adhesion layer will peel off due to F ₆ . This is because WF ₆ has no reactivity with the tungsten silicide forming the adhesion layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a semiconductor device of the present invention.

2A to 2C are cross-sectional views showing the main part of the method for manufacturing the semiconductor device shown in FIG. 1 in the order of steps.

FIG. 3 is a configuration diagram showing a multi-chamber used for carrying out the method of manufacturing the semiconductor device shown in FIG.

[Explanation of symbols]

 1 Semiconductor Substrate 4 Interlayer Insulating Film 5 Contact Hole 6 Adhesion Layer Made of Tungsten Silicide 7 Plug Film (Tungsten Film) 8 Metal Wiring Film (Aluminum)

Claims (3)

[Claims] 1. A semiconductor device having a metal wiring film, wherein the contact between the metal wiring film and the semiconductor substrate or another metal wiring film is taken through a plug film having a tungsten silicide film as an adhesion layer as an underlying layer. A semiconductor device characterized by 2. A plug film having a tungsten silicide film as an adhesion layer and serving as a base for contacting a metal wiring film with a semiconductor substrate or another metal wiring film, said metal wiring film / semiconductor substrate or another metal wiring film 2. The semiconductor device according to claim 1, wherein the contact hole or the via hole selectively formed in the inter-layer insulating film interposed therebetween is filled. 3. After selectively forming a contact hole or a via hole in the interlayer insulating film, first, a tungsten silicide film to be an adhesion layer is formed by CVD, then a tungsten film to be a plug film is formed, and thereafter, 3. The method for manufacturing a semiconductor device according to claim 2, wherein the plug film using the adhesion layer as a base is formed by removing the tungsten film and the tungsten silicide film outside the contact hole or the via hole by etching back.