JP2000003884A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a barrier metal layer which has an excellent barrier and adhesion property, by providing an insulating film having an opening part on a semiconductor substrate, providing a nitride film on the insulating film, providing the thin film comprising high melting-point metal compound on the nitride film, and providing a conducting layer on the thin film. SOLUTION: On a semiconductor Si substrate 11, an SiO2 film 12 as an insulating film is deposited. A contact hole is formed on the surface of this SiO2 film 12. On the SiO2 film 12 wherein the contact hole is formed, a WSiN film 13 as a barrier layer is deposited. This WSiN film has the amorphous structure. Then, on this WSiN film 13, a WSi film 14, which is crystallized by high temperature sputtering of 450 deg.C-650 deg.C is deposited. Furthermore, Cu 15 is deposited on the rough surfaced WSi film 14. The Cu 15 is fused by laser melting and embedded, and the Cu wiring is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having a barrier metal between a conductive layer and a semiconductor substrate and a method of manufacturing the same.

[0002]

2. Description of the Related Art As circuit elements formed inside a semiconductor device become finer, the diffusion depth and the like of a diffusion layer also become finer. Therefore, if the contact hole is directly buried with copper or a copper alloy, there is a possibility that junction penetration or junction leak may occur. Further, copper has poor adhesion to an insulating film or a silicon substrate.

In order to prevent this, that is, to secure a barrier property in the contact hole and to improve the adhesion, a barrier metal film is formed when the contact hole is buried. This barrier metal layer is used not only for the contact portion but also for forming wirings and electrodes on the insulating film.

At present, Ta, TiW, and the like are used as barrier metal materials. Although these materials have good adhesion to copper, they are poor in barrier properties because they are polycrystals and are columnar crystals having crystal grain boundaries perpendicular to the underlayer.

FIG. 4 shows a Ta film or TiW as a barrier metal.
FIG. 4 is a cross-sectional view of a contact hole after laser melting when a film 44 is used. S on Cu at bottom of contact hole
A precipitate 46 of i was observed, and a spike 4
7 has occurred.

[0006] In addition to the barrier properties and adhesion, it is desired to lower the resistance of the wiring layer in order to improve the performance of the device. Therefore, the barrier metal layer, became more MoSi x resistance is relatively excellent in heat resistance _low, polysilicide structure formed by laminating a refractory metal silicide such as WSi _x is generally used. These refractory metal silicides are well suited for processes using polycrystalline silicon, and are very excellent in that they do not require many changes even if a polysilicide structure is introduced.

However, if, for example, tungsten silicide is used as a single-film barrier metal between the insulating film and the copper-embedded electrode or wiring, since tungsten silicide has a crystalline structure, copper permeates through crystal grain boundaries. Reliability was low. For example, JP-A-7-16165
No. 9 discloses a semiconductor device using gold as an electrode, in which a tungsten nitride film is formed on a tungsten film formed on a GaAs substrate, and a method of manufacturing the same.

However, when the electrode is made of Cu, the upper surface of the tungsten nitride film has an amorphous structure, so that the surface is smooth and poor in adhesion.

FIG. 5 shows a contact hole 53 after laser melting when a WSiN single film 54 is used as a barrier metal.
FIG. Since the WSiN film has an amorphous structure, the surface is smooth and has poor adhesion to Cu 55, and voids 56 are generated at the bottom of the contact holes 53.

As described above, a barrier metal having excellent adhesion to a conductive metal, particularly copper, and excellent barrier properties has been desired.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having a barrier metal layer having excellent barrier properties and excellent adhesion to an electrode or a wiring layer, and a method of manufacturing a semiconductor device. is there.

[0012]

According to the present invention, there is provided a semiconductor device comprising:
A semiconductor substrate, an insulating film having an opening on the semiconductor substrate, a nitride film of a refractory metal compound provided on the semiconductor substrate and the insulating film, or provided on the insulating film, and provided on the nitride film. And a conductive layer provided on the thin film.

The nitride film has an amorphous structure, and the thin film has a crystalline structure. Further, specifically explaining the semiconductor device of the present invention, the nitride film is tungsten nitride silicide, the thin film is tungsten silicide, and the conductive layer is copper.

Further, a method of manufacturing a semiconductor device according to the present invention
Forming an insulating film over the semiconductor substrate, forming an opening in the insulating film, and over the semiconductor substrate and the insulating film;
Or a step of forming a nitride film of a high melting point metal compound on the insulating film, a step of forming a thin film made of the high melting point metal compound on the thin film, and a step of depositing a conductive layer on the thin film. It is characterized by doing.

The nitride film has an amorphous structure, and the thin film has a crystalline structure. In the method of manufacturing a semiconductor device according to the present invention, the temperature of the thin film forming step is 450 ° C. to 600 ° C.
And Further, in the method of manufacturing a semiconductor device according to the present invention, an opening forming step, a nitride film forming step, a thin film forming step,
After the conductive layer deposition step, the method may further include a step of melting the conductive layer and filling the opening in the opening. In the method of manufacturing a semiconductor device according to the present invention, specifically, the nitride film is tungsten nitride silicide, the thin film is tungsten silicide, and the conductive layer is copper.

According to the semiconductor device and the method of manufacturing the same of the present invention, the two-layered barrier metal provided on the insulating film of the semiconductor substrate maintains good adhesion between the insulating film and copper as an electrode while maintaining good adhesion. Copper can be prevented from permeating the insulating film. Specifically, the nitride film made of tungsten nitride silicide provided immediately above the insulating film has an amorphous structure, and the thin film made of tungsten silicide provided on the nitride film is formed by high-temperature sputtering or sputtering. Has a crystal structure by high temperature annealing.

The nitride film may be in contact with both the semiconductor substrate and the insulating film, or may be in contact only with the insulating film.

The temperature for high temperature sputtering or high temperature annealing of the thin film is about 450 ° C. to 600 ° C. Since the nitride film, which is the lower layer of the thin film, is crystallized at about 750 ° C., the amorphous structure is maintained in the temperature range of 450 ° C. to 600 ° C. As described above, since the crystallization temperatures of the two barrier metals are different, the lower nitride film remains amorphous and does not transmit copper, and the upper thin film has a crystal structure. It becomes uneven and comes into good contact with copper. The resistivity of the lower nitride film is 400μΩ
・ It is about cm.

Furthermore, since the same sputtering target can be used for forming the barrier metal layer by sputtering, the production can be performed efficiently in terms of work and cost. Specifically, using a tungsten silicide target, the lower nitride film is formed by sputtering with a gas containing nitrogen gas, and the upper thin film is formed by high-temperature sputtering at about 450 ° C. to 600 ° C. Alternatively, at the time of forming the lower nitride film, for example, sputtering is performed by using nitrogen gas and argon gas, and the upper layer is formed only by appropriately changing the sputtering gas, such as performing only sputtering with argon gas, thereby forming two barrier metal layers. be able to. The flow rate of the nitrogen gas during the sputtering of the lower layer is, for example, about 10 to 15% with respect to the total amount of the nitrogen gas and the argon gas.
The sputtering time is about 30 seconds for the lower nitride film and about 30 seconds for the upper thin film. By adjusting the time of this sputtering, the film thickness to be formed can be changed.

The sputtering target used in the present invention is tungsten silicide, and the ratio of tungsten to silicon is 1: 0.1 to 0.1: 1, preferably 1: 0.
5 to 0.5: 1, most preferably 1: 1. Also,
Oxygen, nitrogen, etc. as impurities are ≤300 ppm in total
It is preferred to be on the order of magnitude.

The film thickness of the barrier metal of the present invention is about 50 nm in total of the nitride film and the thin film, and is about 25 nm each, but it is not always necessary to have the same thickness. This film thickness can be controlled by changing the deposition time as described above.

Further, the copper of the electrode has a structure having a groove along the contact hole if it is simply deposited. Since this structure is inferior in performance as a semiconductor element, it is better to use a buried structure in which the surface of the deposited copper is flattened.
The copper embedded wiring structure is realized by a laser melt method or reflow sputtering. This may be done in a vacuum. However, this buried wiring is not essential to a two-layer barrier metal formed by utilizing the fact that the crystallization temperature is different.

The opening diameter of the contact hole in the semiconductor device of the present invention is about 0.5 to 2.0 μm.

Although the barrier metal of the present invention has been described by taking a contact hole as an example, the present invention is not limited to this, and can be applied to a trench wiring or a multilayer wiring as shown in FIG. .

The present invention utilizes the fact that the crystallization temperatures of the two barrier layers are different to improve the adhesion to a metal having poor adhesion while maintaining the barrier properties. The barrier layer may be multi-layered or the combination of the barrier layer and the conductive metal may be appropriately changed without departing from the technical idea of the present invention.

[0026]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Embodiment 1] FIGS. 1D and 2D
According to the method, the SiO ₂ insulating films 12 and 22 having the contact holes on the Si substrates 11 and 21 and the SiO ₂ insulating film 1
There is provided a semiconductor device in which WSiN films 13 and 23 are formed on layers 2 and 22 and WSi films 14 and 24 are formed on WSiN films 13 and 23 and a Cu conductive layer is buried thereon.

Hereinafter, embodiments and modified embodiments of the method of manufacturing a semiconductor device according to the present invention will be described with reference to the drawings.

Embodiment 2 First, as shown in FIG. 1A, an SiO ₂ film 12 is deposited as an insulating film on a semiconductor Si substrate 11 by a CVD method or the like, and RIE is performed on the surface of the SiO ₂ film 12. A contact hole is formed by a method or the like.

SiO ₂ film 1 with contact hole formed
2, a WSiN film 13 as a barrier layer was formed by using a WSi target,
Deposition is performed by reactive sputtering using a mixed gas of about 0 to 15%. Since this WSiN film has an amorphous structure, it exhibits excellent barrier properties.

Next, as shown in FIG. 1B, the WSSiN film 13 was further crystallized by high-temperature sputtering using argon gas at 450 ° C. to 650 ° C.
An i film 14 is deposited. The surface of the WSi film is roughened by crystallization. Due to the rough surface having irregularities, excellent adhesion with Cu to be deposited next is realized. The total thickness of the WSiN film 13 and the WSi film 14 is about 50 nm.

Further, as shown in FIG. 1C, Cu 15 is deposited on the roughened WSi film 14 by sputtering to have a thickness of 1 to 3 μm.

In this state, since there is a gap in the contact hole portion, the reliability as an element is lowered.
As shown in (d), Cu15 is melted by laser melt to form embedded Cu wiring.

According to the present embodiment, since the crystallization temperature of the WSiN film 13 is about 750 ° C., it does not crystallize at 450 to 600 ° C., and only the WSi film 14 can be crystallized. 13 exhibits sufficient barrier properties while being amorphous, and the WSiN film 14 is crystallized to form a rough surface and adheres well to the Cu 15.

As described above, a two-layer barrier metal can be efficiently formed by utilizing the difference in crystallization temperature between WSiN and WSi.

[Embodiment 3] In the modified embodiment,
The steps (a), (c) and (d) are the same as those in FIG. 1, but in FIG. 2 (b), the upper layer WSi film 24 'is deposited by performing normal sputtering with argon gas, and In b) ′, a WSi film 24 crystallized by further performing a high-temperature annealing process at 450 ° C. to 650 ° C. is generated. By this annealing treatment, a tungsten silicide layer having a higher degree of crystallinity is formed, and a structure having more excellent adhesion to Cu can be realized.

[0037]

According to the semiconductor device of the present invention, the tungsten silicide in the upper layer of the barrier metal has irregularities on the surface, so that the contact area with Cu increases, so that very excellent adhesion can be obtained. Since the tungsten silicide under the barrier metal has an amorphous structure, excellent barrier properties can be obtained.

Further, according to the method of manufacturing a semiconductor device of the present invention, by using film materials having different crystallization temperatures, a film in contact with a semiconductor substrate and / or an insulating film exhibits excellent barrier properties as an amorphous structure. However, the film that comes into contact with the conductive layer has a good crystal structure and good adhesion to the conductive layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a contact hole of a semiconductor device according to an embodiment of the present invention and a diagram showing a manufacturing process thereof.

FIG. 2 is a cross-sectional view of a contact hole of a semiconductor device according to one embodiment of the present invention and a diagram showing a manufacturing process thereof.

FIG. 3 is a perspective view showing a modification of the present invention.

FIG. 4 is a cross-sectional view of a contact hole of a semiconductor device using a conventional barrier metal.

FIG. 5 is a cross-sectional view of a contact hole of a conventional semiconductor device using a barrier metal.

[Explanation of symbols]

11 and 21 ... Si substrate 12, 22 ... SiO ₂ insulating film 13, 23 ... WSiN film 14, 24 ... Previous WSi film WSi film 24 '... crystallized crystallized 15, 25 ... Cu 44 ... Ta film or TiW film 46 ... Si precipitates 47 ... spike 51 ... Si substrate 52 ... _SiO 2 53 ... Si contact portion 54 ... WSiN unilamellar 55 ... Cu 56 ... void

Continued on the front page F term (reference) 4M104 BB28 BB36 BB37 DD16 DD37 DD40 DD42 DD78 DD79 FF18 HH04 5F033 AA04 AA29 AA64 AA67 AA73 AA74 BA15 BA17 BA24 BA25 BA38 BA45 DA07 DA15 DA34 DA38

Claims (8)

[Claims] A semiconductor substrate; an insulating film having an opening formed on the semiconductor substrate; and a nitride of a high melting point metal compound provided on the semiconductor substrate and the insulating film or on the insulating film. A semiconductor device comprising: a film; a thin film made of a high melting point metal compound provided on the nitride film; and a conductive layer formed on the thin film. 2. The nitride film has an amorphous structure,
2. The thin film according to claim 1, wherein the thin film has a crystal structure.
13. The semiconductor device according to claim 1. 3. The method according to claim 1, wherein the nitride film is tungsten nitride silicide, the thin film is tungsten silicide,
2. The semiconductor device according to claim 1, wherein said conductive layer is copper. A step of forming an insulating film on the semiconductor substrate; a step of forming an opening on the insulating film; and forming a refractory metal compound on the semiconductor substrate and the insulating film or on the insulating film. Forming a nitride film, forming a thin film made of a refractory metal compound on the thin film, and depositing a conductive layer on the thin film. Production method. 5. The nitride film has an amorphous structure,
5. The thin film according to claim 4, wherein the thin film has a crystal structure.
The manufacturing method of the semiconductor device described in the above. 6. The method for manufacturing a semiconductor device according to claim 4, wherein the temperature of said thin film forming step is from 450 ° C. to 600 ° C. 7. The method according to claim 4, further comprising a step of melting the conductive layer and filling the opening in the opening. 8. The nitride film is tungsten nitride silicide, the thin film is tungsten silicide,
The method according to claim 4, wherein the conductive layer is made of copper.