JPH08107148A - Wiring structure and forming method thereof - Google Patents

Abstract

PURPOSE: To realize a method of forming a wiring structure, wherein a lower wiring is excellent in patterning accuracy, and a contact resistance between a plug and the lower wiring is low enough when the lower wiring and upper wiring are connected together with the plug. CONSTITUTION: A conductive layer of laminated structure composed of a Ti thin film 6 and a TiN thin film 7 is formed on the surface of an Al alloy film 5, the Al alloy film 5 and the conductive layer are patterned through a lithography technique, an Si oxide film 8 is deposited on the Al alloy film 5 and the conductive layer, and a contact hole 9 reaching to the conductive layer is provided to the Si oxide film 8. After the contact hole 9 is formed, the TiN thin film 7 exposed at the bottom of the contact hole 9 is removed by etching, a tungsten plug 10 is buried in the contact hole 9 through a selective CVD method, and an Al alloy film 12 is formed so as to be electrically connected to the tungsten plug 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure and a method for forming the same, and more particularly to a multilayer wiring.

[0002]

2. Description of the Related Art In recent years, in multi-layer wiring adopted in highly integrated semiconductor devices, inter-wiring contact (via contact)
There is a demand for lower resistance and improved wiring reliability.
Moreover, semiconductor devices are becoming more highly integrated,
There is a demand for reducing the diameter of contact holes (also synonymous with via holes). However, if the diameter of the contact hole is reduced, it becomes difficult to deposit a wiring material having a sufficient thickness in the contact hole. Therefore, an appropriate metal (tungsten, aluminum, nickel, copper, etc.) is provided in the contact hole by the CVD method.
Has been proposed to form a plug connecting the first layer wiring and the second layer wiring (Japanese Patent Laid-Open No. 4-264).
721 (see H01L21 / 285)).

That is, a titanium nitride thin film is formed on a first wiring layer made of an Al--Si alloy, the wiring layer is covered with an insulating film, and then a contact hole leading to the titanium nitride film is formed in this insulating film. , A tungsten plug is grown on the titanium nitride thin film by a selective CVD method, the contact hole is filled, and Al-S is contacted with the plug.
The second wiring layer made of i alloy is formed.

In particular, in this conventional example, since it is difficult for tungsten to grow selectively on the titanium nitride thin film, the specific resistance of the titanium nitride thin film is 300 Ωcm or less (for example, 100 Ωc).
m) is set.

[0005]

The conventional example has the following problems. 1) The contact resistance between the tungsten plug and the Ti nitride thin film is high. 2) The variation in contact resistance between the tungsten plug and the Ti nitride thin film is large (particularly, this problem becomes more remarkable as the diameter of the contact hole becomes smaller).

The present invention relates to a wiring structure and a method for forming the same, and solves such a problem.

[0007]

A wiring structure according to claim 1 is
A conductive material having a good connection resistance with the plug is interposed between the conductive layer and the conductive plug. Also,
3. The wiring structure according to claim 2, wherein the lower conductive layer and the upper conductive layer are connected via a conductive plug formed in a contact hole, and the conductive plug is formed on the lower conductive layer. Is formed by forming a conductive film made of a substance having a good contact resistance and an antireflection effect during lithography, and forming the conductive plug on the conductive film.

According to a third aspect of the present invention, there is provided a wiring structure in which a lower conductive layer and an upper conductive layer are connected via a conductive plug formed in a contact hole, and at least the lower conductive layer is formed on the lower conductive layer. In addition to forming a conductive film having a two-layered structure, the conductive film lacks an upper layer portion in contact with the plug. In the wiring structure according to claim 4, the conductive film has a lower layer portion made of a material having a good connection resistance with the conductive plug, and an upper layer portion made of a material having a good antireflection effect during lithography. Is.

According to a fifth aspect of the present invention, there is provided a wiring structure in which a lower layer wiring and an upper layer wiring are connected to each other through a tungsten plug formed in a contact hole. In addition to forming a conductive film made of the titanium nitride film, the plug includes at least the part where the titanium nitride film is in contact with the plug is absent and is in contact with the titanium film.

According to a sixth aspect of the wiring structure, the conductive plug or the tungsten plug is formed by a selective CVD method. According to a seventh aspect of the present invention, there is provided a wiring structure forming method, wherein a conductive substance having a good connection resistance with the plug is provided between the conductive layer and the conductive plug, and the conductive plug is selectively grown on the conductive substance. It is a thing.

The method of forming a wiring structure according to claim 8 is
A step of forming a conductive film having a laminated structure of at least two kinds on the surface of the lower conductive layer, a step of patterning the lower conductive layer and the conductive film, and an interlayer insulating film on the lower conductive layer and the conductive film. A step of depositing and forming a contact hole communicating with the conductive film in the interlayer insulating film; and a step of etching away the upper layer part of the conductive film exposed at the bottom of the contact hole at the same time as or after the formation of the contact hole. And a step of embedding a conductive plug in the contact hole, and a step of forming an upper conductive layer so as to be electrically connected to the conductive plug.

A method of forming a wiring structure according to a ninth aspect is:
The conductive film has a lower layer portion made of a material having a good connection resistance with the conductive plug, and an upper layer portion made of a material having a good antireflection effect during lithography. According to a tenth aspect of the present invention, there is provided a wiring structure forming method, wherein the conductive plug is formed by a selective CVD method.

The method of forming a wiring structure according to claim 11 further includes the step of forming a conductive film having a laminated structure of a titanium film and a titanium nitride film thereon on the surface of the lower conductive layer, and the lower conductive layer and Simultaneously with the step of patterning the conductive film, the step of depositing an interlayer insulating film on the lower conductive layer and the conductive film, and forming a contact hole communicating with the conductive film in the interlayer insulating film. Alternatively, after formation, a step of etching away the titanium nitride film exposed at the bottom of the contact hole, a step of embedding a tungsten plug in the contact hole by a selective CVD method, and electrically connecting to the tungsten plug, And a step of forming an upper conductive layer.

According to a twelfth aspect of the present invention, there is provided a method of forming a wiring structure, which comprises depositing an interlayer insulating film on a lower conductive layer and forming a contact hole in the interlayer insulating film, the contact hole communicating with the lower conductive layer; A step of forming a titanium compound film on the bottom surface and the inner surface of the contact hole; a step of forming a conductive plug in the contact hole; and a step of forming an upper conductive layer so as to be electrically connected to the conductive plug. It includes and.

Further, a wiring structure forming method according to a thirteenth aspect is the method of forming a conductive film having a laminated structure of at least two kinds on the surface of the lower conductive layer, and the step of patterning the lower conductive layer and the conductive film. And a step of depositing an interlayer insulating film on the lower conductive layer and the conductive film and forming a contact hole communicating with the conductive film in the interlayer insulating film, and forming a titanium compound film on at least a bottom surface and an inner surface of the contact hole. It includes a step of forming, a step of forming a conductive plug in the contact hole, and a step of forming an upper conductive layer so as to be electrically connected to the conductive plug.

According to a fourteenth aspect of the present invention, there is provided a method of forming a wiring structure, wherein the contact hole is formed simultaneously with or after the contact hole is formed.
At least a part of the conductive film exposed at the bottom of the contact hole is removed by etching. According to a fifteenth aspect of the present invention, in the method of forming a wiring structure, the conductive plug is formed by a technique of forming a metal film having a good covering property such as a blanket tungsten CVD method and an etchback technique.

According to the sixteenth aspect of the present invention, in the method for forming a wiring structure, the conductive film is made of a material whose upper layer has a good antireflection effect during lithography. The method of forming a wiring structure according to claim 17, wherein a step of forming a conductive film having a laminated structure of a titanium film and a titanium nitride film on the titanium film on the surface of the lower wiring layer, the lower wiring layer and the conductive film. A step of patterning, a step of depositing an interlayer insulating film on the lower wiring layer and the conductive film and forming a contact hole communicating with the conductive film in the interlayer insulating film, and simultaneously with or after the formation of the contact hole A step of etching away the titanium nitride film exposed at the bottom of the contact hole, a step of forming a titanium nitride film on at least a bottom surface and an inner surface of the contact hole, and a surface including the inside of the contact hole by a blanket tungsten CVD method. A step of forming a tungsten material on the substrate, and by etching back the tungsten material, the contact Forming a tungsten plug in the hole, so as to be electrically conductive to the tungsten plugs, it is intended to include forming an upper wiring layer.

That is, according to the present invention, a conductive substance having a good contact resistance with the plug, such as titanium, is interposed between the wiring (lower conductive layer) and the conductive plug. Get electrical properties. Further, initially, a material having a good antireflection effect such as titanium nitride is laminated on the conductive material to improve patterning accuracy by lithography, and thereafter, the upper layer material is absent, and the plug is made of the conductive material. The structure is such that substances come into contact with each other.

In particular, when titanium is used as the conductive material and titanium nitride is used as the antireflection film, it is difficult to grow tungsten on the titanium nitride by the selective CVD method. A material such as titanium having a good contact resistance with a tungsten plug is formed on the layer, and a material having a good antireflection effect such as titanium nitride is stacked on the material, so that selective growth of tungsten can be achieved. If the titanium nitride film is removed before, good patterning accuracy of the lower conductive layer and good contact resistance between the plug and the lower conductive layer can be obtained.

Further, as a base film formed before performing a technique for forming a metal film having a good covering property such as a blanket tungsten CVD method, it has high adhesion to a substrate,
A titanium compound film such as titanium nitride that does not cause the film to peel off from the end face of the substrate is used.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which the present invention is embodied in a two-layer wiring will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a manufacturing process of a semiconductor device adopting the wiring structure of the first embodiment, which will be described in order below.

Step 1 (see FIG. 1A): A silicon oxide film 2 having a film thickness of 600 nm is CVed on the single crystal silicon substrate 1.
It is formed by the D method, the thermal oxidation method, or the like. Further, using a magnetron sputtering method, a titanium (Ti) thin film 3 (film thickness 50 nm) and titanium nitride (Ti) are formed on the Si oxide film 2.
N) Thin film 4 (film thickness 100 nm), aluminum alloy film 5 (Al
-Si (1%)-Cu (0.5%)) (film thickness 500n
m), a Ti thin film 6 (thickness 30 nm) and a TiN thin film 7 (thickness 20 nm) are sequentially formed from the bottom.

The Ti thin film 3 and the TiN thin film 4 function as a barrier metal for preventing Al and Si from reacting with each other. Further, the Ti thin film 6 and the TiN thin film 7 (particularly the TiN thin film 7) function as so-called cap metal that prevents light from being reflected by Al in the lithography process and prevents reflected light from affecting the resist. Then, ordinary lithography technology and dry etching technology (RIE
The barrier metal, the aluminum alloy film 5 and the cap metal are patterned into a predetermined shape by applying a resist (not shown), exposing, and etching by a method (for example).

Step 2 (see FIG. 1B): the TiN thin film 7
Then, the Si oxide film 8 (film thickness 600 nm) is deposited on the exposed Si oxide film 2 by the CVD method. Furthermore, ordinary lithography technology and dry etching technology (RIE
Method, etc.), resist (not shown) is applied, exposure and etching are performed, and then the TiN thin film 7 is formed on the Si oxide film 8.
To form a contact hole 9 reaching to.

Step 3 (see FIG. 1C): the Si oxide film 8
With the mask as a mask, only the TiN thin film 7 corresponding to the bottom of the contact hole 9 is removed by RIE (Reactive Ion Etchin).
g) Etching is removed by the method. Etching conditions are: used gas: CHF ₃ 20 sccm, CF ₄ 20 sccm, pressure: 30
0 Torr, power: 500W. In addition, this step 3
It may be performed at the same time when the contact hole 9 is formed in step 2.

Step 4 (see FIG. 1D): The tungsten plug 10 is selectively grown only in the contact hole 9 by the selective tungsten-CVD method. The growth conditions are temperature: 300 ° C., pressure: 10 mTorr, gas used: tungsten hexafluoride (WF ₆ , flow rate 10 sccm) + monosilane (SiH ₄ , flow rate ₆ sccm) (gas flow rate ratio: SiH ₄ /
WF ₆ = 0.6) is suitable, but the temperature is 250 ° C. to 3
In the range of 50 ° C., the gas flow rate ratio (SiH ₄ / WF ₆ ) was 0.
It can be appropriately adjusted within the range of 5 to 0.8.

Step 5 (see FIG. 1E): The oxide film and the like on the surface of the tungsten plug 10 are removed by sputter etching using an inert gas (Ar, for example). Next, a Ti thin film 11 (having a film thickness of 50) is formed on the tungsten plug 10 and the Si oxide film 8 by using a magnetron sputtering method.
nm), Al alloy film 12 (Al-Si (1%)-Cu
(0.5%)) (film thickness 500 nm), TiN thin film 13
(The film thickness is 20 nm) is sequentially formed from the bottom.

Then, the Ti thin film 1 is subjected to resist (not shown) coating, exposure, and etching operations by the usual lithography technique and dry etching technique (RIE method or the like).
1. The aluminum alloy film 12 and the TiN thin film 13 are patterned into a predetermined shape. FIG. 2 shows the relationship between the diameter of the contact hole and the contact resistance with the underlying film when tungsten is grown in the contact hole by the selective CVD method in the structure of the first embodiment.

As is apparent from the results of this experiment, when tungsten is selectively grown on the TiN thin film as in the conventional case, the contact resistance value is relatively high and the variation is large as compared with the present invention, and , The tendency becomes stronger as the diameter of the contact hole becomes smaller. As described above, in the first embodiment, the TiN thin film 7 in which tungsten is difficult to selectively grow is removed before growing tungsten, and the Ti thin film 6 having a good connection resistance with tungsten is used as a base for selective growth. Therefore, even if the diameter of the contact hole 9 is small, a good tungsten plug can be formed.

As the cap metal, the Ti thin film 6 and T
Although the iN thin film 7 has a two-layer structure, it is not limited to two layers. The point is that the uppermost layer has an antireflection effect and the portion in contact with the tungsten plug 10 has a good contact resistance with tungsten. If The cap metal itself may be a single layer as long as it has both an antireflection effect and a good contact resistance. For example, if the plug 10 is tungsten, only the Ti thin film 6 may be used.
The Ti thin film 6 is inferior to the TiN thin film 7 in the antireflection effect, but is sufficiently within the allowable range. (Second Embodiment) A second embodiment in which the present invention is embodied in a two-layer wiring will be described with reference to the drawings.

3 to 8 are sectional views showing a manufacturing process of a semiconductor device adopting the wiring structure of the second embodiment, which will be described below in order. Step (1) (see FIG. 3): A silicon oxide film 22 having a film thickness of 600 nm is formed on the single crystal silicon substrate 21 by a CVD method,
It is formed by a thermal oxidation method or the like. Further, titanium (T) is formed on the Si oxide film 22 by using a magnetron sputtering method.
i) Thin film 23 (film thickness 50 nm), titanium nitride (TiN)
Thin film 24 (film thickness 100 nm), aluminum alloy film 25 (Al
-Si (1%)-Cu (0.5%)) (film thickness 500n
m), Ti thin film 26 (thickness 30 nm), TiN thin film 27
(The film thickness is 20 nm) is sequentially formed from the bottom.

The Ti thin film 23 and the TiN thin film 24 are
It functions as a barrier metal for preventing 1 and Si from reacting with each other. Further, the Ti thin film 26 and the TiN thin film 27 (particularly the TiN thin film 27) function as so-called cap metal that prevents light from being reflected by Al in the lithography process and prevents reflected light from affecting the resist.

Then, the barrier metal, the aluminum alloy film 25, and the cap metal are patterned into a predetermined shape by applying a resist (not shown), exposing, and etching by an ordinary lithography technique and dry etching technique (RIE method or the like). . Step (2) (see FIG. 4): A Si oxide film 28 (film thickness 600 nm) is deposited on the TiN thin film 27 and the exposed Si oxide film 22 by a CVD method. Furthermore, ordinary lithography technology, dry etching technology (RIE method, etc.)
As a result, a contact hole 29 reaching the TiN thin film 27 is formed in the Si oxide film 28 through resist (not shown) coating, exposure, and etching operations.

Step (3) (see FIG. 5): Si oxide film 2
By using 8 as a mask, only the TiN thin film 27 corresponding to the bottom of the contact hole 29 is removed by etching by RIE. Etching condition is gas used: CHF ₃
20 sccm, CF ₄ 20 sccm, pressure: 300 Torr, power: 500 W. The step (3) may be performed at the same time when the contact hole 29 is formed in the step (2).

Step (4) (see FIG. 6): After cleaning the inside of the contact hole 29 by sputter etching using an inert gas (eg, Ar), the bottom surface of the contact hole 29 and the bottom surface of the contact hole 29 are magnetized by a magnetron sputtering method. A titanium nitride (TiN) thin film 30 (film thickness 100 nm) is formed on the inner surface and further on the surface of the Si oxide film 28.

Step (5) (see FIG. 7): By blanket tungsten CVD method, tungsten is formed on the TiN thin film 30 including the inside of the contact hole 29. The forming conditions are temperature: 450 ° C. and pressure: 80
Torr, gas used: Tungsten hexafluoride (WF ₆ , flow rate 70 sccm) + hydrogen (H ₂ , flow rate 420 sccm) (gas flow rate ratio: H ₂ / WF ₆ = 6) is suitable, but the temperature is 425 ° C.
The gas flow rate ratio (H ₂ / WF ₆ ) is 5 to 475 ° C.
It can be adjusted appropriately within the range of 70.

Then, the formed tungsten is anisotropically etched back and processed so that the tungsten is flush with the surface of the Si oxide film 28 to form a tungsten plug 31 in the contact hole 29. Step (6) (see FIG. 8): If necessary, the oxide film or the like on the surface of the tungsten plug 31 is removed by sputter etching using an inert gas (for example, Ar).

Next, using the magnetron sputtering method,
On the tungsten plug 31 and the TiN thin film 30, an Al alloy film 32 (Al-Si (1%)-Cu (0.
5%)) (film thickness 500 nm), TiN thin film 33 (film thickness 2
0 nm) is sequentially formed from the bottom. Then, the aluminum alloy film 32 and the TiN thin film 33 are patterned into a predetermined shape by applying a resist (not shown), exposing, and etching by a usual lithography technique and dry etching technique (RIE method or the like).

FIG. 9 shows the relationship between the diameter of the contact hole and the contact resistance with the underlying film when tungsten is grown in the contact hole by the blanket tungsten CVD method in the structure of the second embodiment. Therefore, by forming a TiN thin film on the entire growth surface before the CVD, the contact resistance is slightly higher than that of the structure of the first embodiment, but it can still be lowered sufficiently.

In the figure, the symbol □ indicates the second embodiment, and the symbol ● indicates that a TiN / Ti thin film is used instead of the TiN thin film. The structure of this TiN / Ti thin film also has a low contact resistance, but Ti has poorer adhesion to the substrate than TiN and is easily peeled off from the end face portion of the substrate.
The present invention is not limited to the above embodiment and may be carried out as follows.

Other than magnetron sputtering, the sputtering method may be diode sputtering, high frequency sputtering, quadrupole sputtering, or the like. As a method of sputter etching, reactive ion beam etching (also referred to as RIBE or reactive ion milling) using a reactive gas (for example, CCl ₄ , SF ₆ ) may be used instead of using an inert gas.

The silicon oxide film may be formed by a method other than the CVD method (PVD method such as sputtering method or vapor deposition method, oxidation method). The silicon oxide film may be replaced with another insulating film (various silicate glass, alumina, silicon nitride film, titanium oxide film, etc.). In the first embodiment, the tungsten plug 10 is made of another metal (aluminum, nickel, copper, molybdenum, etc.).
You may replace with the plug by. In this case, in consideration of the antireflection effect, contact resistance, etc., the Ti thin film 6 or Ti
Instead of the N thin film 7, another conductive material may be used as appropriate.

In the second embodiment, the tungsten plug 31 may be replaced with a plug made of another metal (aluminum, nickel, copper, molybdenum, etc.). In the second embodiment, instead of the TiN thin film 30, T
An iW thin film may be used. In short, if a titanium compound is used, a low contact resistance can be obtained and the adhesion to the substrate is good.

[0044]

According to the wiring structure and the method of manufacturing the same of the present invention, by interposing a conductive substance such as titanium having a good contact resistance with the plug between the wiring and the conductive plug, Good electrical characteristics can be obtained. Moreover, initially, a material having a good antireflection effect such as titanium nitride is laminated on the conductive material to enhance the patterning accuracy by lithography, and thereafter, the upper material is omitted, and the plug is made of the conductive material. Since the structure is such that substances come into contact with each other, the patterning accuracy of the lower layer wiring,
Good contact resistance is obtained for both the plug and the lower layer wiring.

Further, when the conductive plug is formed, a titanium compound film is formed on the base as an adhesion layer,
It is possible to obtain low contact resistance without worrying about film peeling at the edge of the substrate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a semiconductor device of a first embodiment in which a wiring structure of the invention is embodied.

FIG. 2 is a diagram showing a relationship between a diameter of a contact hole and a connection resistance value between a tungsten plug and a base film in the first embodiment.

FIG. 3 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the present invention is embodied.

FIG. 4 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the invention is embodied.

FIG. 5 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the present invention is embodied.

FIG. 6 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the invention is embodied.

FIG. 7 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the invention is embodied.

FIG. 8 is a cross-sectional view showing the manufacturing process of the semiconductor device of the second embodiment in which the wiring structure of the invention is embodied.

FIG. 9 is a diagram showing a relationship between a diameter of a contact hole and a connection resistance value between a tungsten plug and a base film in the second embodiment.

[Explanation of symbols]

1, 21 Silicon substrate 5, 25 Al alloy thin film (lower conductive layer, conductive layer) 6, 26 Ti thin film (conductive material having good contact resistance with plug, conductive film) 7, 27 TiN thin film (with antireflection effect) Good conductive material, conductive film 8, 28 Silicon oxide film (interlayer insulating film) 9, 29 Contact hole 10, 31 Tungsten plug (conductive plug) 12, 33 Al alloy thin film (upper conductive layer) 30 TiN thin film

Claims (17)

[Claims] 1. A wiring structure characterized in that a conductive material having a good connection resistance with the plug is interposed between the conductive layer and the conductive plug. 2. A lower conductive layer and an upper conductive layer are connected via a conductive plug formed in a contact hole, and a contact resistance between the lower conductive layer and the conductive plug. And the conductive plug is formed on the conductive film, and the conductive plug is formed on the conductive film. 3. A lower conductive layer and an upper conductive layer are connected via a conductive plug formed in a contact hole, and a conductive layer having at least two kinds of laminated structures is formed on the lower conductive layer. A wiring structure, wherein a film is formed, and the conductive film lacks an upper layer portion in contact with the plug. 4. The conductive film has a lower layer portion made of a material having a good connection resistance with the conductive plug, and an upper layer portion made of a material having a good antireflection effect during lithography. The wiring structure according to Item 3. 5. A lower layer wiring and an upper layer wiring are connected via a tungsten plug formed in a contact hole, and a conductive film made of a titanium film on the lower layer wiring and a titanium nitride film thereon. And the plug is in contact with the titanium film due to the lack of the titanium nitride film at least at a portion contacting the plug. 6. The wiring structure according to claim 1, wherein the conductive plug or the tungsten plug is formed by a selective CVD method. 7. A wiring structure characterized in that a conductive material having a good connection resistance with the plug is provided between the conductive layer and the conductive plug, and the conductive plug is selectively grown on the conductive material. Forming method. 8. A step of forming a conductive film having a laminated structure of at least two kinds on the surface of the lower conductive layer; a step of patterning the lower conductive layer and the conductive film; A step of depositing an interlayer insulating film on the interlayer insulating film, and forming a contact hole communicating with the conductive film in the interlayer insulating film; and an upper layer portion of the conductive film exposed at the bottom of the contact hole at the same time as or after the formation of the contact hole. And a step of burying a conductive plug in the contact hole, and a step of forming an upper conductive layer so as to be electrically connected to the conductive plug. Method of forming structure. 9. The conductive film has a lower layer portion made of a material having a good connection resistance with the conductive plug, and an upper layer portion made of a material having a good antireflection effect during lithography. 8. The method for forming a wiring structure according to item 8. 10. The method of forming a wiring structure according to claim 7, wherein the conductive plug is formed by a selective CVD method. 11. A step of forming a conductive film having a laminated structure of a titanium film and a titanium nitride film thereon on the surface of the lower conductive layer; a step of patterning the lower conductive layer and the conductive film; A step of depositing an interlayer insulating film on the layer and the conductive film, and forming a contact hole communicating with the conductive film in the interlayer insulating film; exposed at the bottom of the contact hole at the same time as or after the formation of the contact hole A step of etching away the titanium nitride film, a step of burying a tungsten plug in the contact hole by a selective CVD method, and a step of forming an upper conductive layer so as to be electrically connected to the tungsten plug. A method for forming a wiring structure characterized by the above. 12. An interlayer insulating film is deposited on the lower conductive layer,
A step of forming a contact hole communicating with the lower conductive layer in the interlayer insulating film; a step of forming a titanium compound film on at least a bottom surface and an inner surface of the contact hole; and a step of forming a conductive plug in the contact hole. And a step of forming an upper conductive layer so as to be electrically connected to the conductive plug, the method for forming a wiring structure. 13. A step of forming a conductive film having a laminated structure of at least two kinds on the surface of the lower conductive layer, a step of patterning the lower conductive layer and the conductive film, and a step of forming a conductive film on the lower conductive layer and the conductive film. A step of depositing an interlayer insulating film on the interlayer insulating film and forming a contact hole in the interlayer insulating film that communicates with the conductive film; a step of forming a titanium compound film on at least a bottom surface and an inner surface of the contact hole; Forming a conductive plug, and forming an upper conductive layer so as to be electrically connected to the conductive plug. 14. The method for forming a wiring structure according to claim 13, wherein at least a part of the conductive film exposed at the bottom of the contact hole is removed by etching simultaneously with or after the formation of the contact hole. . 15. The wiring structure according to claim 12, 13 or 14, wherein the conductive plug is formed by a technique of forming a metal film having good coverage and an etchback technique. Method. 16. The method of forming a wiring structure according to claim 12, wherein an upper layer portion of the conductive film is made of a material having a good antireflection effect during lithography. 17. A step of forming a conductive film having a laminated structure of a titanium film and a titanium nitride film thereon on the surface of the lower wiring layer, a step of patterning the lower wiring layer and the conductive film, and the lower wiring. Depositing an interlayer insulating film on the layer and the conductive film,
A step of forming a contact hole communicating with the conductive film in the interlayer insulating film, a step of etching away the titanium nitride film exposed at the bottom of the contact hole at the same time as or after the formation of the contact hole, and at least the contact A step of forming a titanium nitride film on the bottom and inner surfaces of the hole; a step of forming a tungsten material on the surface including the inside of the contact hole by a blanket tungsten CVD method; and a step of etching back the tungsten material to form the contact hole. A method of forming a wiring structure, comprising: a step of forming a tungsten plug therein; and a step of forming an upper wiring layer so as to be electrically connected to the tungsten plug.