JPH06112157A - Semiconductor device and manufacture therefor - Google Patents

Abstract

PURPOSE:To form a metal silicide film not depending on a size of a contact hole by forming a thin metal film after the contact hole is opened on an insulation film, having it subjected to thermal treatment in a gas atmosphere containing nitrogen while forming a metal silicide film mainly containing the thin metal film at the bottom of the contact hole. CONSTITUTION:Photo resist is removed and a thin metal film 30 is formed by means of sputtering. In forming the thin metal film 30 by sputtering, thickness at the bottom of a contact hole 28 having a smaller aspect ratio due to a shadowing effect is smaller than that at the bottom of a contact hole 29. Thermal treatment at 800 deg.C is performed in a N2 atmosphere to form the thin metal film 3 into metal silicide film 31, 32. Thus thickness of metal silicide films 25, 31 at the bottom of the contact hole 28 and thickness of metal silicide films 25, 32 at the bottom of the contact hole 29 are almost constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device using a method of forming a metal silicide film used for manufacturing a semiconductor element and a method of forming a metal plug in a contact hole.

[0002]

2. Description of the Related Art Heretofore, when manufacturing a semiconductor device or the like, silicidation of a metal film has been studied for the purpose of reducing contact resistance.

For example, in the method disclosed in Japanese Patent Laid-Open No. 63-143841, a tungsten silicide film is formed by a sputtering method and used as an electrode or a wiring. This method has a problem that the metal silicide film formed at the bottom of the contact hole depends on the aspect ratio of the contact hole because the metal silicide film is formed by the sputtering method. The metal silicide film thickness at the bottom of the contact hole has a great influence on the contact resistance. For example,
"Nishiyama other 2, silicide film thickness dependence of the TiSi ₂ / Si contact resistance in the silicide structure, 39th Applied Physics Association Lectures Proceedings, 30a-ZM-9 (199
2) p721 ”, it is stated that the contact resistance increases as the film thickness of the metal silicide increases.

Further, when the metal plug 6 is formed in the contact hole by using the selective CVD method, the surface condition of the insulating film 2 significantly affects its selectivity. For example, if the metal plug 6 is formed by the selective CVD method when the surface of the insulating film 2 is rough, metal particles 9 are generated on the insulating film 2 as shown in FIG.

The metal particles 9 cause not only a short circuit between wiring layers but also a short circuit between the metal wirings 11 and 12 as shown in FIG. 3B. In particular, metal particles 9
If the diameter is large, or if the distance between the metal wires 11 and 12 is narrow, there is a high possibility that short circuits between wires will occur frequently.

[0006] For example, the method described in Japanese Patent Laid-Open No. 63-128712 discloses forming a silicon dioxide film on a silicon substrate,
Next, impurities are introduced into the surface of the silicon dioxide film to change the surface state, a contact hole is opened in the silicon dioxide film, and then a W film is formed only inside the contact hole by using the selective CVD method. This method has a problem that, when impurities are introduced into the surface of the silicon dioxide film, a damaged layer is formed on the surface of the silicon dioxide film, and there is a concern that the damage layer may deteriorate the selectivity when the W film is formed by the selective CVD method. there were.

Further, JP-A-62-199034 and JP-A-62-19
9035, and the method described in JP-A-63-44730,
A film having etching characteristics different from those of the insulating film is formed on the insulating film, and after forming the contact hole, a tungsten (W) film is formed only inside the contact hole by the selective CVD method. At this time, W particles deposited on the film due to deterioration of selectivity are simultaneously removed by etching the film. These methods have a problem that the process becomes complicated.

[0008]

The prior art disclosed in Japanese Patent Laid-Open No. 63-143841 discloses that in a sample having a plurality of contact holes with different diameters, the larger the contact hole size, the more metal is formed at the bottom of the contact. There is a problem that the silicide film becomes thick and the contact resistance increases.

Further, JP-A-62-199034 and JP-A-62-19
The conventional techniques described in No. 9035 and Japanese Patent Laid-Open No. 63-44730 not only increase the number of processes but also significantly deteriorate the selectivity, the W film is not a thin film but W particles on the insulating film. As a result, it is more likely to be deposited. In this case, it becomes difficult to etch the film and it becomes very difficult to remove W. Even if the film can be etched, since a large amount of W to be removed is present in the etching solution, it is considered that W is redeposited on the sample surface and causes a short circuit between wirings or between wiring layers.

An object of the present invention is to form a metal silicide film which does not depend on the size of the contact hole.
Another object of the present invention is to form a metal plug excellent in selectivity in a method for forming a metal plug using a CVD method, without depending on its forming condition.

[0011]

In order to achieve the above object, the features of the method or apparatus of the present invention are as follows.

(1) After forming a contact hole in the insulating film, a metal thin film is formed, and heat treatment is performed in a gas atmosphere containing nitrogen such as N ₂ gas or NH ₃ and at least the surface of the metal thin film on the insulating film. Is nitrided and a metal silicide film containing the metal thin film as a main component is formed at the bottom of the contact hole.

(2) After the metal silicide film described in (1) and the metal nitride film on the insulating film are formed, the metal film is formed by the CVD (chemical vapor deposition) method, and the metal silicide film is formed on the metal silicide film. Only the metal film is formed.

(3) The heat treatment described in (1) is performed within a temperature range of 600 to 900 ° C. using either a furnace body or an RTA (rapid thermal anneal).

(4) The metal thin film described in (1) is titanium, tungsten, molybdenum, tantalum, cobalt,
It is made of either nickel.

(5) The metal film using the CVD method described in (2) is formed of aluminum, tungsten, titanium, tantalum, copper, or an alloy film containing these as main components, or a nitride film of these metals. To do.

(6) After opening the contact hole, a metal thin film is formed, and heat treatment is performed in a gas atmosphere containing nitrogen such as N ₂ gas or NH ₃ so that at least the surface of the metal thin film is metal nitrided on the insulating film. There is a step of forming a film and a metal silicide film containing the metal thin film as a main component at the bottom of the contact hole, and further forming a metal film only on the metal silicide film by using the CVD method.

(7) A metal silicide film is formed on the surface of the Si substrate on which impurities are implanted to form a diffusion layer, and thereafter,
A metal film is formed by forming an insulating film, opening a contact hole, and a sputtering method, and only the metal film at the bottom of the contact hole is silicidized.

[0019]

The operation of the present invention will be described with reference to FIGS. The insulating film 2 is formed on the Si substrate 1, and the insulating film 2 is dry-etched using the photoresist as a mask to open a contact hole. Then, after removing the photoresist, the metal thin film 3 is formed (FIG. 1A). Then
6 in a gas atmosphere containing nitrogen such as N ₂ gas or NH _3.
When heat treatment is performed in the temperature range of 00 to 900 ° C., at least the surface of the metal thin film 3 is nitrided on the insulating film 2 to form the metal nitride film 4. On the other hand, in the metal thin film 3 that is in contact with the Si substrate 1, the silicidation reaction with the Si substrate 1 is prioritized over the nitriding reaction on the high temperature side of the temperature range, and becomes the metal silicide film 5 (FIG. 1B). .

For example, when the metal thin film 3 is Ti, RTA
(Rapid Thermal Anneal) is continuously performed in a N ₂ gas atmosphere for 1 minute at 650 ° C. and 1 minute at 800 ° C., at least the surface of the Ti film on the insulating film 2 is nitrided to become a TiN film. In addition, the Ti film in contact with the Si substrate 1 has a TiSix (x <
2) It becomes a film state and becomes a low resistance TiSi ₂ film by heat treatment at 800 ° C. The surface of this TiSi ₂ film may be partially made of TiN, but most of it is in the state of TiSi ₂ .

Further, CV is formed on the metal silicide film 5.
The metal plug 6 is formed by using the D method. Usually, the metal plug 6 is formed by selectively burying the metal only in the contact hole using a selective CVD method, or by forming a metal film on the entire surface of the sample by a full-scale CVD method, and then performing etchback to make contact. Either leave the metal only inside the hole. For example, in the case where a W plug is formed by a selective CVD method using SiH ₄ reduction, its selectivity is greatly influenced by the underlying material of the sample and the surface condition of the underlying film. Further, although the formation temperature can be formed at a relatively low temperature of about 280 ° C., the selectivity is also influenced by the formation temperature, so that temperature control is important.

In the present invention, the metal plug 6 having excellent selectivity is formed only on the metal silicide film 5. For example, when a TiSi ₂ film is used as the material of the metal silicide film 5 and W is used as the material of the metal plug 6, the W plug can be formed by the selective CVD method by SiH ₄ reduction, or by the CVD method by the H ₂ reduction. It is also possible to form a W plug. The CVD method using H ₂ reduction has a formation temperature of about 450 to 550 ° C., which is higher than that of SiH ₄ reduction, and is generally used to form W on the entire surface of a sample. In the present invention, the metal nitride film 4 is formed on the insulating film 2.
Therefore, W is not formed on the metal nitride film 4 even if the CVD method by H ₂ reduction is used, and W is formed only on the TiSi ₂ film at the bottom of the contact hole. As described above, the present invention can form the metal plug 6 having excellent selectivity without depending on the conditions for forming the metal film by the CVD method.

Further, the first wiring layer can be formed by forming the wiring metal film 7 on the entire surface of the sample and etching the wiring metal film 7 using the photoresist as a mask (FIG. 2A).

After forming the metal plug 6, the metal nitride film 4 is dry-etched to form the wiring metal film 7 with the sidewall film 8 of the metal nitride film left only on the sidewall of the contact hole (FIG. 2). (B)). This method is shown in FIG.
Compared with the method described in (1), it is effective in flattening the sample by the film thickness of the metal nitride film 4.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. After the field oxide film 22 is formed on the Si substrate 21, impurities are doped and diffused to form a diffusion layer 23, and further a metal thin film 24 is formed (FIG. 4).
(A)).

Next, heat treatment is performed at 800 ° C. in an N ₂ atmosphere to cause a silicide reaction only in the portion where the metal thin film 24 is in contact with the diffusion layer 23 to cause the metal silicide film 25.
To form. In this embodiment, Ti is used as the material of the metal thin film 24 and a TiSi ₂ film is used as the metal silicide film 25. The unreacted metal thin film 24 on the field oxide film 22 was etched using a mixed solution of H ₂ O ₂ and ammonia. Next, the insulating film 26 is formed (FIG. 4).
(B)). Further, a photoresist 27 is formed to form a desired mask pattern (FIG. 4 (c)).

Then, the insulating film 26 is etched by using the photoresist 27 as a mask to open desired contact holes 28 and 29 (FIG. 5A). At this time, the smaller the aspect ratio of the contact hole (hole depth / hole diameter), the higher the etching rate of the insulating film 26. Therefore, when etching of the contact hole 29 having a large aspect ratio is completed, excessive etching is performed at the bottom of the contact hole 28 having a small aspect ratio, and the metal silicide film 25 is also etched. Therefore, the film thickness of the metal silicide film 25 at the bottom of the contact hole 28 is equal to that of the contact hole 29.
It is thinner than the film thickness of the metal silicide film 25 at the bottom.
In order to secure the reliability of the wiring in the contact hole portion, it is necessary to make the film thickness of the metal silicide film 25 constant regardless of the aspect ratio of the contact hole.

Next, the photoresist 27 is removed (see FIG.
(B)), The metal thin film 30 is formed by sputtering (FIG.5 (c)). When the metal thin film 30 is formed by sputtering, the film thickness at the bottom of the contact hole 28 having a small aspect ratio becomes thicker than the film thickness at the bottom of the contact hole 29 due to the shadowing effect. Further, heat treatment is performed at 800 ° C. in an N ₂ atmosphere in the same manner as described above, and the metal thin film 3 on the bottoms of the contact holes 28 and 29 is formed.
0 is used as the metal silicide films 31 and 32 (see FIG. 6).
(A)). As a result, the film thickness of the metal silicide films 25 and 31 at the bottom of the contact hole 28 and the contact hole 2
The film thicknesses of the metal silicide films 25 and 32 at the bottom of the 9 are substantially constant.

Further, a metal wiring film 33 is formed, and a first wiring layer is formed with a two-layer structure of the metal wiring film 33 and the metal thin film 30 (FIG. 6B). In addition, the metal thin film 30 on the insulating film 26
After etching, the metal wiring film 34 may be formed to serve as the first wiring layer (FIG. 6C).

Next, an example of manufacturing a semiconductor device having a multilayer wiring structure using the present invention will be described. FIG. 7 is a sectional view of the multilayer wiring structure. An insulating film 51 is formed on the Si substrate 50, the insulating film 51 is etched using a photoresist mask, and desired contact holes are opened. Then, the first wiring layer 52 is formed, and the first wiring layer 52 is etched into a desired pattern using a photoresist mask. In this embodiment, a W film is used as the first wiring layer 52.

Then, an interlayer insulating film 53 and a metal nitride film 54 are formed, and the two-layer film is etched using the photoresist as a mask to open a desired hole. Next, a metal film is formed by using the CVD method. At this time, the metal film formed by the CVD method was not formed on the metal nitride film 54 but was deposited only inside the hole, and the metal plug 55 having excellent selectivity could be formed. In this example, a TiN film was used as the metal nitride film 54, and the material of the metal film formed by the CVD method was the W film. Next, the second wiring layer 56 is formed, and the second wiring layer 56 and the metal nitride film 54 are etched using the photoresist as a mask. As a result, the reliability of the wiring in the hole portion can be ensured and the flatness of the sample can be improved.

Next, another embodiment of manufacturing a semiconductor device according to the present invention is shown in FIGS. N ^- Si substrate 1
51 surface is oxidized to form a SiO ₂ layer 152.
The io ₂ layer 152 is etched into a desired pattern by using a photoresist mask, and the P well layer 15 is doped with impurities using this pattern as a mask.
3 is formed (FIG. 8A).

The SiO ₂ layer 152 is removed, an oxide film 154 is formed on the surface of the substrate for stabilization, and then the Si ₃ N ₄ film 1 is formed.
After forming 55, etching is performed with a photoresist pattern 156 to form a desired pattern, and a photoresist pattern 157 is further formed thereon (FIG. 8).
(B)). A P layer 158 is formed by impurity doping using these patterns as a mask, the photoresist patterns 156 and 157 are removed, and then field oxidation is performed to remove the Si ₃ N ₄ film 155 and gate oxidation is performed (FIG. )).

A polycrystalline Si film 159 having a thickness of 0.3 μm is formed, and is etched into a desired pattern using a photoresist mask (FIG. 9A). Next, the insulating film 161
Is formed into a desired pattern with a photoresist mask, and impurity doping and diffusion are performed using the insulating film 161 and the polycrystalline Si film 159 as a mask to form a P high-concentration layer 160 (FIG. 9B). Except for the insulating film 161, the insulating film 16 is formed so as to cover the P high concentration layer 160 by the same method as described above.
2 is formed, and the N high concentration layer 163 is formed (FIG. 9).
(C)).

The insulating film 162 is removed, and a phosphorous glass (PSG) insulating film 164 is formed on the entire surface to a thickness of about 0.6 μm (FIG. 10A). Further, using the photoresist 165 as a mask (FIG. 10B), the insulating film 164 is etched, the contact hole 166 is opened, and then the photoresist 165 is removed (FIG. 10C). The steps up to this point are the same as in the conventional method.

Next, a metal thin film 167 is formed (FIG. 11).
(A)). In this embodiment, a Ti film is used as the metal thin film 167 and its film thickness is 30 nm. Next, heat treatment is performed at 800 ° C. in an N ₂ atmosphere to form the metal thin film 167 on the insulating film 164 as a metal nitride film 168 and the metal thin film 167 in contact with the Si substrate as a metal silicide film 169 (FIG. 11B). ). Further, the metal plug 170 is formed by using the CVD method (FIG. 11C). In this example, a W film having a thickness of 0.6 μm was formed as a metal plug. This CV
The W film formed by the D method is not formed on the metal nitride film 168.
Since it is formed only on the metal silicide film 169, the metal plug 170 having excellent selectivity can be formed.

Next, the metal nitride film 168 is etched by reactive ion etching until the surface of the insulating portion 164 is exposed, and the side wall film 1 is formed only on the side wall of the contact hole 166.
It is left as 71 (FIG. 12A). Further, a metal film is formed by a sputtering method and is etched into a desired pattern by using a photoresist as a mask to form a first wiring layer 172 (FIG. 12B). In this embodiment, a W film is used as the first wiring layer 172 and its thickness is 0.3 μm.

Next, the interlayer insulating film 173 and the metal thin film 174.
And the metal thin film 17 using the photoresist as a mask.
4 and the interlayer insulating film 173 are continuously etched to form desired through holes. The film thickness of the interlayer insulating film 173 was 0.6 μm, a TiN film was used as the metal nitride film 174, and the film thickness was 30 nm. Further, the metal plug 175 is formed by the same method as described above (FIG. 12C).
The metal plug 175 is a W film and its film thickness is 0.5.
μm.

Further, a metal thin film for wiring is formed, and the metal thin film for wiring and the metal nitride film 17 are formed by using the photoresist as a mask.
4 is etched to form a second wiring layer 176 (see FIG. 1).
3). The material of the second wiring layer 176 is Al, and the thickness thereof is 0.5 μm.

As a result, the diameter is 0.25 μm and the depth is 0.6.
A Ti silicide film can be formed on the bottom of the contact hole of μm, and a W film can be embedded on the Ti silicide film to planarize it.
A wiring film having an excellent film coating shape could be formed. Moreover, since the Ti silicide film exists between the W film and the Si substrate, an extremely low contact resistance was obtained.
In addition, it became possible to embed metal in the contact hole with excellent selectivity.

[0041]

According to the present invention, since a metal silicide film having a uniform film thickness can be formed at the bottom of the contact hole without depending on the size of the contact hole, the contact depending on the film thickness of the metal silicide film can be formed. It is possible to prevent an increase in resistance. Moreover, since the contact resistance between the wiring and the Si substrate can be reduced, the contact resistance can be substantially reduced.

Further, after forming a contact hole in the insulating film and forming a metal thin film, the metal thin film at the bottom of the contact hole is entirely a metal silicide film by heat treatment, and the metal thin film on the insulating film is a metal nitride film. By CV
When forming the metal plug in the contact hole using the D method, the metal plug having excellent selectivity could be formed. The formation condition of the metal plug at this time is not limited to the formation condition of the selective CVD method, and the metal plug excellent in selectivity can be formed even under the formation condition of the whole surface CVD method.

[Brief description of drawings]

FIG. 1 is a sectional view of a first step in a contact hole portion of the present invention.

FIG. 2 is a sectional view of a second step in the contact hole portion of the present invention.

FIG. 3 is a sectional view showing a problem of forming a metal plug by a conventional selective CVD method.

FIG. 4 is a cross-sectional view of a first step in the contact hole portion of the embodiment of the present invention.

FIG. 5 is a sectional view of a second step in the contact hole portion of the embodiment of the present invention.

FIG. 6 is a sectional view of a third step in the contact hole portion of the embodiment of the present invention.

FIG. 7 is a sectional view of a multilayer wiring structure according to an embodiment of the present invention.

FIG. 8 is an element sectional view showing a first manufacturing process of an embodiment of the present invention.

FIG. 9 is an element cross-sectional view showing the second manufacturing process of the embodiment of the present invention.

FIG. 10 is an element cross-sectional view showing the third manufacturing process of the embodiment of the present invention.

FIG. 11 is an element sectional view showing a fourth manufacturing process of an example of the present invention.

FIG. 12 is an element sectional view showing a fifth manufacturing process of an example of the present invention.

FIG. 13 is an element sectional view showing a sixth manufacturing process of an example of the present invention.

[Explanation of symbols]

1 ... Si substrate, 2 ... Insulating film, 3 ... Metal thin film, 4 ... Metal nitride film, 5 ... Metal silicide film, 6 ... Metal plug.

Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H01L 21/90 B 7514-4M (72) Inventor Yoshifumi Kawamoto 1-280, Higashi Koikeku, Kokubunji, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Shigenori Oyu 1-280 Higashi Koikekubo, Kokubunji, Tokyo Hitachi Central Research Laboratory (72) Inventor Natsuki Yokoyama 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Central Research Center, Ltd. (72) Inventor Masakazu Kono 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Hitate Cho-LS Engineering Co., Ltd.

Claims (7)

[Claims] 1. A method of manufacturing a semiconductor device, wherein after forming a contact hole in an insulating film, a metal thin film is formed, and a heat treatment is performed in a gas atmosphere containing nitrogen such as N ₂ gas or NH _{3 and the} like. Then, at least the surface of the metal thin film is nitrided, and a metal silicide film containing the metal thin film as a main component is formed at the bottom of the contact hole. 2. The chemical vapor deposition (CV) method according to claim 1, after forming the metal silicide film and the metal nitride film on the insulating film.
D) A method of manufacturing a semiconductor device in which a metal film is formed only on the metal silicide film by using the method. 3. The heat treatment according to claim 1, wherein the heat treatment is 600
A method for manufacturing a semiconductor device, which is performed within a temperature range of 900 ° C. to 900 ° C. 4. A semiconductor device manufactured by the method according to claim 1, wherein the metal thin film is made of any one of titanium, tungsten, molybdenum, tantalum, cobalt and nickel. 5. The CV manufactured by the method according to claim 2.
The metal film using the D method is aluminum, tungsten,
A semiconductor device made of titanium, tantalum, copper, an alloy film containing these as main components, or a nitride film of these metals. 6. A metal thin film is formed after opening a contact hole, and heat treatment is performed in a gas atmosphere containing nitrogen such as N ₂ gas or NH ₃ , and at least the surface of the metal thin film is covered with a metal nitride film on the insulating film. And a step of forming a metal silicide film containing the metal thin film as a main component at the bottom of the contact hole, and further forming a metal film only on the metal silicide film by using a CVD method. Production method. 7. A metal silicide film is formed on the surface of a Si substrate in which impurities are injected to form a diffusion layer, and then an insulating film is formed, contact holes are formed, and a metal film is formed by a sputtering method. Then, a method of manufacturing a semiconductor device is characterized in that the metal film at the bottom of the contact hole undergoes a silicidation reaction.