JPH08191053A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a semiconductor device, which has a multilayer wiring structure having little junction leak, and a method of manuacturing the device. CONSTITUTION: A titanium silicide film 14 is formed on the surface of a silicon substrate 11 formed with a diffused layer 12 by an epitaxial growth and moreover, an aluminium film 15 is formed thereon by a selective CVD of aluminium. As the film 14 formed by the epitaxial growth is a single crystal film, the film 14 does not have crystal grain boundaries. Accordingly, a diffusion of the aluminium, which is performed through these crystal grain boundaries, is effectively prevented. The film thickness of the film 14 is set 10nm or thikcer.

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 having a connection structure for electrically connecting metal wiring to a diffusion layer formed in a partial region of the surface of a semiconductor substrate. And a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method of manufacturing a semiconductor device having a multilayer wiring structure, a contact hole is formed in an interlayer insulating film formed on a silicon substrate having a diffusion layer formed on the surface so that the surface of the diffusion layer is exposed. , A method of selectively depositing and growing aluminum in the contact hole by a chemical vapor reaction is disclosed in, for example, "Koichi Tani and Satoshi Nishikawa (OK
I), Extended Abstracts 1993, Intl. Conf. SSDM, pp.5
43-545 ”. However, in the conventional method, since the surface of the silicon substrate is eroded by aluminum during the deposition of aluminum, when the diffusion layer is shallow, aluminum penetrates through the diffusion layer and diffuses to generate a spike, which causes a large junction leakage current. There was a drawback that occurred.

In the element using salicide, TiSi ₂
It needs to be formed on top, but "Chung Yu Ting and Marc
Wittmer (IBM), J. Appl. Phys. 54 (2), 1983, pp.937
~ 943 ”, aluminum diffuses through TiSi ₂ and causes spikes due to aluminum, which causes junction leakage.

[0004]

As described above, when the aluminum plug is formed on the diffusion layer formed on the surface of the semiconductor substrate, spikes due to the diffusion of aluminum into the diffusion layer are likely to occur. It is desirable to provide a barrier layer for preventing diffusion. However, when the aluminum plug is selectively embedded in the contact hole formed in the insulating film, the barrier layer for diffusion prevention must be selectively formed in the contact hole. A method for satisfactorily forming a barrier layer having high diffusion prevention performance has not been proposed.

Further, a silicide film is formed on the diffusion layer,
Although it has been proposed to form an aluminum plug on this silicide film by selective CVD, the conventional silicide film is made of polycrystal, and aluminum is diffused through the grain boundaries, and There is a drawback that the barrier performance is low.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, effectively prevent the diffusion of this metal into the diffusion layer when forming a metal plug by selective CVD, and reduce the contact leakage current. A semiconductor device having the above and a method for manufacturing the same are provided.

[0007]

A semiconductor device according to the present invention is formed by epitaxial growth on a semiconductor substrate, a diffusion layer formed in a partial region of the surface of the semiconductor substrate, and at least a partial region of the diffusion layer. A metal silicide film,
A metal film selectively formed by a chemical vapor reaction on the metal silicide film is provided.

In the method of manufacturing a semiconductor device according to the present invention, in manufacturing a semiconductor device having a connection structure in which metal wiring is electrically connected to a diffusion layer formed in a partial region of the surface of a semiconductor substrate, the diffusion is performed. A step of forming an interlayer insulating film on the surface of the layer, a step of selectively removing the interlayer insulating film to form a contact hole, exposing the surface of the diffusion layer at the bottom thereof, and nitrogen of 10% to 40%. After forming a refractory metal film containing at a concentration of atomic%, heat treatment is performed to react the refractory metal film with the surface of the diffusion layer to form a refractory metal silicide film and a refractory metal nitride film. A step of removing the unreacted portion of the refractory metal film and the nitride film of the refractory metal to leave only the refractory metal silicide film, and a metal on the refractory metal silicide film surface in the contact hole. Select membrane It is characterized in that it comprises a step of burying a metal film to grown hardship and bore.

[0009]

In the semiconductor device according to the present invention, the silicide film epitaxially grown exists between the diffusion layer and the metal film selectively formed in the contact hole, and the silicide film is formed of single crystal. Therefore, since it has no crystal grain boundary, it has extremely excellent characteristics as a diffusion preventing layer, and metal diffusion through the grain boundary does not occur. Therefore, there are no spikes,
Even in the case of a shallow junction, the junction leak current is sufficiently small and excellent device characteristics can be obtained. In particular, in a highly integrated semiconductor device having small contact holes, highly reliable metal wiring can be obtained. In the present invention, as a result of studying the characteristics of the metal silicide film selectively formed at the bottom of the contact hole, it was confirmed that the metal silicide film has excellent barrier performance when formed by epitaxial growth. For example, a titanium film added with nitrogen is formed on a silicon substrate, and a high temperature heat treatment is performed to form a laminated structure of a titanium silicide film and a titanium nitride film. Controlling the nitrogen content in the titanium film Have reported that a titanium silicide film is epitaxially grown at the interface between titanium and a silicon substrate.
In the present invention, by selectively removing the titanium nitride film on the silicide film epitaxially grown by such a method and leaving only the silicide film, it is possible to form a barrier having excellent diffusion prevention performance, Therefore, when the metal film is formed thereon by selective CVD, diffusion into the diffusion layer is suppressed, and the generation of spikes can be prevented.

[0010]

1 is a sectional view showing the structure of an embodiment of a semiconductor device according to the present invention. A diffusion layer 12 is formed on the surface of the silicon substrate 11. On the surface of the silicon substrate 11,
An insulating film 13 is formed, and a titanium silicide film 14 is formed on the surface portion of the silicon substrate which is not covered with this insulating film. In the present invention, it is important that the titanium silicide film 14 is formed by epitaxial growth. An aluminum film 15 is formed on the titanium silicide film 14 by selective CVD. That is, the titanium silicide film 14 is formed in self-alignment with the diffusion layer 12, and the aluminum film 15 is formed in self-alignment with the titanium silicide film.

In the semiconductor device according to the present invention shown in FIG. 1, since the titanium silicide film 14 is formed by epitaxial growth, there is no crystal grain boundary as in the prior art, and therefore diffusion of aluminum through this grain boundary. Does not occur, no aluminum spike occurs in the diffusion layer 12, and no junction leak occurs.

2 to 8 are sectional views of a semiconductor device in successive steps of an embodiment of a method of manufacturing a semiconductor device according to the present invention. As shown in FIG. 2, a P-type silicon substrate 21
A P-type well 22 is formed on the surface of the silicon substrate, and a field oxide film 23 for element isolation is selectively formed on the surface of the silicon substrate. Further, a gate oxide film 24 made of SiO ₂ is formed on the surface of the silicon substrate 21, and a gate electrode 25 made of polysilicon is further formed thereon. On the side surface of this gate electrode 25, Si
A sidewall 26 made of O ₂ is formed. Next, using the field oxide film 23 and the sidewalls 26 as a mask,
(Arsenic) is diffused to form N ⁺ type source region 27 and drain region 28 in a self-aligned manner. The junction depth in these regions is about 0.15 μm.

Next, as shown in FIG.
After forming an interlayer insulating film 29 made of SiO ₂ to a thickness of 1.2 μm on the surface of, a photoresist is formed on this interlayer insulating film, and exposure and patterning are performed to form a contact hole 30. The diffusion layer forming the drain region 28 is exposed at the bottom of the contact hole 30. Next, after removing the photoresist, the semiconductor substrate 21 is introduced into a vacuum apparatus, and a titanium film 31 is formed on the bottom of the contact hole 30 to a thickness of about 20 nm by the sputtering method as shown in FIG. This sputtering is performed in a mixed gas atmosphere of argon / nitrogen (10%),
Titanium is contained in the titanium film 31 at a concentration of 20 atomic%.

Thereafter, the surface of the silicon substrate is subjected to a rapid heat treatment at a temperature of 800 ° C. for 30 seconds in a nitrogen atmosphere,
The semiconductor substrate 21 and the titanium film 31 are reacted with each other to form a laminated structure of epitaxially grown titanium silicide 32 and titanium nitride film 33, as shown in FIG. Then, the unreacted titanium film 31 and titanium nitride film 33 are removed with a sulfuric acid / ammonia hydrogen peroxide solution, and contact holes are formed as shown in FIG.
The titanium silicide film 32 epitaxially grown on the bottom of 30 is exposed.

After cleaning the surface of the silicon substrate 21 by the ammonia-hydrogen peroxide treatment, the silicon substrate 21 is introduced into a vacuum apparatus for forming an aluminum film. Here, dimethyl aluminum hydride (DMAH) is flown on the surface of the silicon substrate 21, and aluminum is deposited only in the contact hole 30 by selective CVD to form an aluminum plug 34, as shown in FIG. in this case,
The aluminum plug 34 is formed so that its surface slightly projects from the contact hole 30. Furthermore, as shown in FIG.
Approximately 0.9 of Al-Cu alloy film so that it contacts the aluminum plug 34.
The aluminum wiring 35 is formed by depositing it to a thickness of μm and performing a desired patterning process.

As described above, it was confirmed that the titanium silicide 32 formed on the bottom of the contact hole 30 has a sufficient barrier property if the film thickness is 10 nm or more. The reason is that the titanium silicide film 32 formed by epitaxial growth as described above has no crystal grain boundaries, and therefore diffusion of aluminum through the crystal grain boundaries can be effectively prevented. In addition, since the underlayer for selective CVD of aluminum is a single crystal, the crystallinity of the CVD-Al film formed on it is also good, and the contact hole 30 is mostly filled with a homogeneous single crystal. become. Although the nitrogen content at the time of sputtering for forming the titanium film 31 was changed within the range of about 10 to 15%, almost the same result as the above was obtained. In this case, the content of nitrogen in the titanium film 31 is
It is equivalent to 20 to 30 atom%. According to the present invention,
The nitrogen content in the titanium film is preferably 10 to 40 atomic%.

FIG. 9 is a graph showing the relationship between the film thickness of the titanium silicide film 32 formed in the contact hole 30 and the junction leak current. Although the magnitude of the junction leak current greatly changes depending on the film thickness of the titanium silicide film 32, it was confirmed that the junction leak current is below the allowable level when the film thickness of the titanium silicide film is 10 nm or more. Therefore, when the contact plug is formed by aluminum CVD, the thickness of the titanium silicide film may be 10 nm or more.

[0018]

As described above, in the semiconductor device according to the present invention, the diffusion layer formed on the surface of the semiconductor substrate,
Since a titanium silicide film that has been epitaxially grown is interposed as a diffusion barrier layer between the contact plug and the contact plug, there is no spike due to metal diffusion when forming the contact plug, and therefore the junction leakage current is reduced and the metal contact plug is also formed. Since is deposited and formed on a single crystal titanium silicide film, it has extremely uniform crystallinity and has excellent device characteristics. Further, according to the method for manufacturing a semiconductor device of the present invention, after forming a refractory metal film such as titanium on the diffusion layer, high temperature heat treatment is performed in a nitrogen atmosphere to form a refractory metal silicide film and a high refractory metal film. After the laminated structure with the nitride film of the melting point metal was formed, the nitride film of the high melting point metal was removed to expose the silicide film, so that the silicide film of the high melting point metal was epitaxially grown,
Therefore, it does not have a grain boundary and has excellent characteristics as a diffusion barrier.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of a semiconductor device according to the present invention.

FIG. 2 is a sectional view showing a first step in an embodiment of the method for manufacturing a semiconductor device according to the present invention.

FIG. 3 is a sectional view of the same step as that shown in FIG.

FIG. 4 is a sectional view of the same next step.

FIG. 5 is a sectional view of the same step as that shown in FIG.

FIG. 6 is a sectional view of the same step as that shown in FIG.

FIG. 7 is a sectional view of the next and subsequent step as well.

FIG. 8 is a sectional view of the same step as that shown in FIG.

FIG. 9 is a graph showing the relationship between the film thickness of the titanium silicide film and the junction leak current.

[Explanation of symbols]

 11 Silicon substrate 12 Diffusion layer 13 Insulating film 14 Titanium silicide film 15 Selective CVD-Al film 21 Silicon substrate 22 Well 23 Field oxide film 24 Gate oxide film 25 Gate electrode 26 Sidewall 27 Source region 28 Drain region 29 Interlayer insulating film 30 Contact Hole 31 Titanium film 32 Titanium silicide film 33 Titanium nitride film 34 Aluminum plug 35 Aluminum wiring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/205 21/768

Claims (5)

[Claims] 1. A semiconductor substrate, a diffusion layer formed in a partial region of the surface thereof, a metal silicide film formed by epitaxial growth on at least a partial region of the diffusion layer, and a metal silicide film formed on the metal silicide film. And a metal film selectively formed by a chemical vapor reaction. 2. The metal silicide film contains nitrogen in an amount of 10-40.
The semiconductor according to claim 1, which is formed by forming a refractory metal film containing atomic% and performing high temperature heat treatment, and then removing the refractory metal nitride film formed on the surface. apparatus. 3. The semiconductor device according to claim 1, wherein the metal silicide film has a thickness of 10 nm or more. 4. When manufacturing a semiconductor device having a connection structure in which metal wiring is electrically connected to a diffusion layer formed in a partial region of the surface of a semiconductor substrate, an interlayer insulating film is formed on the surface of the diffusion layer. The step of forming, the step of selectively removing this interlayer insulating film to form a contact hole and exposing the surface of the diffusion layer at the bottom thereof, and the step of forming a high concentration of nitrogen containing 10% to 40 atomic% After forming the melting point metal film, heat treatment is performed to react the refractory metal film with the surface of the diffusion layer to form a laminated structure of a refractory metal silicide film and a refractory metal nitride film, A step of removing the unreacted portion of the refractory metal film and the refractory metal nitride film to leave only the refractory metal silicide film, and selectively forming a metal film on the refractory metal silicide film surface in the contact hole. Contact hole And a step of filling the inside with a metal film. 5. The method for manufacturing a semiconductor device according to claim 4, wherein the refractory metal silicide film is formed to have a film thickness of 10 nm or more.