JP3087692B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device, wherein the connection hole is electrically connected to the lower and upper conductive layers via the connection hole in the insulator layer. Technology related to embedding with materials.

[0002]

2. Description of the Related Art In a semiconductor integrated circuit or the like, a sputtering method is generally used for forming a conductor film of an internal wiring connecting elements and a peripheral circuit formed on a semiconductor substrate. In recent years, the miniaturization of semiconductor integrated circuits has progressed, and inevitably the diameters of contact holes connecting wirings and impurity diffusion layers and through holes connecting wirings have also been reduced.

[0003] For such fine holes, it has become difficult to secure required reliability and electrical characteristics by forming a conductive film by a conventional sputtering method (conventional sputtering method). Therefore, a technique of embedding a conductor or the like into a fine hole has become indispensable. As one of the techniques, an aluminum reflow method has attracted attention. In this method, an aluminum-based alloy is formed by sputtering and then heated at a high temperature in the same vacuum to fluidize the aluminum-based alloy film and fill holes.

FIG. 3 is a diagram schematically showing the manufacturing steps of the conventional aluminum reflow method in the order of the steps. As shown in FIG. 3, after a contact hole is formed in interlayer insulating film 2 on diffusion layer 3 formed in silicon substrate 1 (FIG. 3A)
Barrier film for preventing the reaction of aluminum (referred to as "aluminum") with the silicon substrate in order to prevent spikes and leakage of aluminum (referred to as "aluminum") to the silicon substrate 1 caused by high-temperature heating in a later step. Then, a titanium film 4 and a titanium nitride film 5 are sequentially deposited (see FIG. 3B). Further, at this time, heat treatment may be performed in a nitrogen atmosphere within a temperature range of 600 to 1000 ° C. in order to improve the barrier properties of these barrier films.

Next, a titanium layer 6 is formed. The thickness of the aluminum alloy film 7 on the side wall of the hole is very small when formed by a normal sputtering method. For this reason, when the aluminum alloy layer 7 is formed directly on the titanium nitride layer 5 and heat-treated, a step break occurs in this portion, and voids are generated. By providing this titanium layer 6, a thin alloy layer 9 of aluminum and titanium (see FIG. 3 (d)) is formed in the heating step, and functions as an adhesive plate to prevent disconnection. The effect of the titanium layer 6 is described in, for example, Japanese Patent Application Laid-Open No. 8-153794.
It is also described in the official gazette.

Next, an aluminum alloy film 7 (for example, AlCu) is continuously formed without breaking the vacuum (see FIG. 3C), and further heated at a temperature of 400 to 500 ° C. without breaking the vacuum. Then, the aluminum alloy film 7 is caused to flow to fill the contact holes (see FIG. 3D).

However, in the conventional aluminum reflow method, when applied to a fine contact hole having a particularly high aspect ratio, even if the titanium layer 6 is provided to prevent disconnection, aluminum overhangs in the opening. The aluminum alloy film 7 is formed large and heated as it is
When the aluminum alloy film 7 is
Is closed, and voids 11 are formed (see FIG. 3E).

This phenomenon can be explained by the behavior of aluminum atoms during heating. That is, aluminum atoms begin to diffuse on the surface by heating, but due to the difference in surface area, the upper part of the wiring (FIG. 3)
The diffusion amount of aluminum atoms on the inner wall of the hole (A in FIG. 3C) is smaller than that in B) of FIG. For this reason, the opening is closed by aluminum atoms diffused from the upper part of the wiring before aluminum atoms sufficient to fill the inside of the hole diffuse to the bottom of the hole. This is because the gap between the overhang portions becomes smaller as the size of the finer holes decreases, and is significantly affected. If the thickness of the aluminum alloy film 7 is reduced in order to reduce the gap between the overhang portions, sufficient aluminum atoms for embedding are not supplied, so that embedding failure also occurs.

As an aluminum reflow method for solving this problem, for example, a method shown in FIG. Similar to the conventional aluminum reflow method described with reference to FIG. 3, a contact hole is formed, and a titanium film 4 and a titanium nitride film 5, which are barrier films, are formed (see FIG. 4B).

After that, an aluminum film 12 is formed by a CVD (chemical vapor deposition) method, and an aluminum alloy film 7 is formed by a sputtering method without breaking vacuum (see FIG. 4C).

Further, without breaking the vacuum, 400 to 50
Heating is performed at 0 ° C. to fluidize the aluminum film 12 and the aluminum alloy 7 and fill the holes (see FIG. 3D).

In this method, since the aluminum film 13 is formed with a sufficient thickness on the inner wall of the hole by the CVD method, it is not necessary to form a titanium layer for preventing aluminum from being disconnected.

In addition, since the overhang is not formed with aluminum by the CVD method and the hole can be buried to some extent,
The aluminum alloy layer 7 can be made thinner by the subsequent sputtering method.

As a result, overhang can be reduced as compared with the conventional aluminum reflow method shown in FIG. 3, so that finer holes can be buried without generating voids.

[0015]

Conventionally, aluminum or its alloy film has been used as an electrode wiring material of a semiconductor device because of its good conductivity and good workability.
As a forming method, a sputtering method is mainly used because of simplicity of the process and high productivity.

On the other hand, in the aluminum reflow method described in Japanese Patent Application Laid-Open No. H7-115073 described with reference to FIG. 4, a CVD method is used in order to improve the embedding property. However, the formation of an aluminum film by the CVD method is not generally used in the manufacture of semiconductor devices at the present time, so that there is a problem that it is necessary to introduce new equipment and the cost becomes high. ing.

Since the film forming speed is about 1/100 of that of a normal sputtering method, the throughput is reduced and the productivity is reduced.

In the case of aluminum wiring, reliability (resistance to electromigration and stress migration)
In general, an alloy film to which impurities such as silicon and copper are added is used to improve the quality.

However, at present, the technology for forming a film of pure aluminum by the CVD method has been considerably developed, but it is difficult to form aluminum to which impurities are added. Further, even in the above-described aluminum reflow method (Japanese Patent Application Laid-Open No. H7-115073), in the case of a finer hole, the overhang of the opening at the time of heating is also the same as in the conventional aluminum reflow method shown in FIG. The formed aluminum is blocked and voids are formed (see FIG. 4E).

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device in which a conductive material can be embedded in a fine hole without voids. It is another object of the present invention to provide a method of manufacturing a semiconductor device which allows finer holes to be buried without using a new process which increases costs and lowers productivity.

[0021]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention includes a step of forming a conductive region or a conductor wiring on a substrate, and a step of forming a conductive region or a conductor wiring on the substrate. Forming an insulator layer having a connection hole, and further forming a conductor wiring material over the connection hole, and further performing a heat treatment on the substrate to form the connection hole into the conductor. In the method of manufacturing a semiconductor device to be embedded with a wiring material, a process of suppressing diffusion of atoms forming the conductor during the heat treatment is performed on the surface of the conductor wiring material formed before the heat treatment.

In the present invention, the conductor wiring material is an aluminum alloy film or a copper film, and the treatment for suppressing the diffusion of atoms forming the conductor forms a titanium thin film on the surface of the conductor film. I do.

Further, in the present invention, the conductor wiring material is an aluminum alloy film or a copper film, and the treatment for suppressing the diffusion of atoms forming the conductor exposes the surface of the conductor film to nitriding plasma. And

[0024]

Embodiments of the present invention will be described below. In the embodiment of the present invention, before the conductor film is buried in the hole by heating, the treatment for suppressing the diffusion of the conductor atom in the upper part of the conductor wiring is performed, so that the diffusion of the conductor atom in the hole (sidewall) is performed. Prioritize. This prevents the overhang portion of the conductor layer from being closed before the completion of the filling in the hole, thereby preventing a void from being formed. For this reason, the conductor film can be buried without voids even in fine holes.

According to a preferred embodiment of the present invention, a titanium film (4 in FIG. 1) as a barrier film and a titanium nitride film (5 in FIG. 1) are formed in a contact hole, and the titanium film (FIG. 1) is formed. 6), an aluminum alloy film (7 in FIG. 1) and a titanium thin film (8 in FIG. 1) are sequentially formed without breaking vacuum. Then, the inside of the contact hole is filled with an aluminum alloy film (7 in FIG. 1) by performing a heat treatment at 400 to 500 ° C. without breaking the vacuum. Subsequently, by forming the titanium thin film 8 on the aluminum alloy film, an alloy layer of aluminum and titanium (9 in FIG. 1) is formed on the wiring in the heat treatment step, thereby suppressing the diffusion amount of aluminum atoms. Thereby, before the inside of the contact hole is buried, it is possible to prevent the upper portion of the hole from being closed and form a void. Therefore, it is possible to bury the fine contact holes without voids.

In the embodiment of the present invention, after the hole is filled with an aluminum alloy film, the aluminum alloy film is exposed to nitrogen plasma to suppress the diffusion amount of aluminum atoms in the upper part of the wiring layer, thereby reducing the amount of aluminum atoms in the hole. Is embedded without voids.

Further, in the embodiment of the present invention, an existing process (conventional sputtering method) may be used, so that investment in new equipment is not required.

As described above, when the present invention is applied to the manufacture of a semiconductor device, fine holes can be buried without incurring extra investment and a decrease in productivity, and the production yield and reliability of a semiconductor integrated circuit can be improved.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

[Embodiment 1] FIG. 1 is a process cross-sectional view schematically showing a cross section in the order of the manufacturing process, taking a case of forming a contact hole as an example, for explaining the manufacturing method of the first embodiment of the present invention. It is.

As shown in FIG. 1A, an impurity diffusion layer 3 and an insulating film 2 having a thickness of 1.0 μm are formed on a main surface of a semiconductor substrate 1 and are formed by a photoresist method and anisotropic etching.
The impurity diffusion layer 3 is exposed, and a contact hole is formed. Thereafter, the surface of the impurity diffusion layer 3 is cleaned by various chemicals or reverse sputtering, and as shown in FIG. 1B, the titanium film 4 is
Is formed to a thickness of 0.1 μm. Here, a lamp heat treatment may be performed in a nitriding atmosphere at 400 to 1000 ° C. for 20 to 120 seconds for the purpose of ensuring the barrier properties of the contact and stabilizing the contact resistance.

Next, as shown in FIG. 1C, a titanium film 6 and an aluminum alloy film 7 are formed in order of 0.03 μm and 0.9 μm, respectively, by sputtering.

Subsequently, without breaking the vacuum, a titanium thin film 8 on the island is formed on the aluminum alloy film 7 above the wiring (B in FIG. 1D) by a sputtering method. In order to form the titanium thin film 8 in an island shape, it is calculated from the deposition rate of titanium to be 10 to 20.
A sputtering time corresponding to a film thickness of about angstrom (1-2 nm) may be set.

Then, as shown in FIG. 1E, the inside of the hole is filled with an aluminum alloy film 7 by performing a heat treatment at 400 to 500 ° C. without breaking the vacuum.

Here, the function of the titanium film 6 and the titanium thin film 8 will be described.

As described in the prior art, the titanium film 6
This is to prevent the aluminum alloy film 7 thinned on the side wall of the hole from being cut off in the subsequent heat treatment process to generate voids. This will be described more specifically.

At the time of the heat treatment, the titanium film 6 and the aluminum alloy film 7 react on the side wall of the hole to form a laminated structure of an aluminum-titanium alloy layer and an excess aluminum alloy layer 7.

The aluminum-titanium alloy layer 9 serves as a strong adhesive plate, and the excess aluminum alloy layer 7 on the side wall of the hole does not easily flow. However, since the surface is active, aluminum atoms diffused from the top of the hole can move to the bottom of the hole using this as a bridge. If the titanium film 6 is not provided,
When the aluminum alloy film 7 is formed directly on the titanium nitride 5 and heat treatment is performed, aluminum atoms on the side wall of the hole are attracted to the upper and lower portions of the hole due to poor wettability, and are cut off. Then, the diffusion path of the aluminum atoms to the bottom of the hole is cut off, resulting in the formation of voids.

Next, the function of the titanium thin film 8 will be described. In the conventional aluminum reflow method in which the titanium thin film 8 is not formed, the side wall of the hole (FIG. 3) is compared with the amount of aluminum atoms diffused from the upper part of the wiring (B in FIG.
(C) A little from A) to the bottom of the hole.
For this reason, the upper portion of the hole is closed before a sufficient amount of aluminum atoms to fill the inside of the hole diffuses to the bottom of the hole. Then, a void is formed. This is due to the difference in the supply of aluminum atoms that diffuse. This is because aluminum atoms diffuse from the top and bottom of the wiring in all directions, but inside the hole only from the side wall having a relatively small surface area.

In this embodiment, when there is a titanium thin film 8, an alloy layer 9 of aluminum and titanium is formed above the wiring during the heat treatment. Then, as described above, since the alloy layer 9 of aluminum and titanium is strong, diffused aluminum atoms are not supplied from here. That is, the amount of aluminum atoms per unit time diffused from the upper part of the wiring (B in FIG. 1D) to the upper part of the hole can be reduced. If the diffusion amount of the aluminum atoms is equal to or less than that from the hole side wall to the hole bottom, the upper portion of the hole will not be closed before the inside of the hole is buried. Therefore, in this embodiment,
It enables the filling of finer holes.

[Embodiment 2] FIG. 2 is a process cross-sectional view schematically showing a cross section in the order of processes, taking a case of forming contact holes as an example, for explaining a manufacturing method of a second embodiment of the present invention. is there.

Similar to the first embodiment, after forming a titanium film 4 and a titanium nitride film 5 as barrier films in contact holes, a titanium film 6 and an aluminum alloy film 7 are formed respectively (FIG. 2C). reference).

Subsequently, the aluminum alloy film 7 is maintained without breaking the vacuum.
Is exposed to nitriding plasma by a parallel plate. The conditions of the nitriding plasma are as follows: RF power: 300 W, nitriding pressure:
80 mTorr, substrate temperature: 50 ° C., process time:
5 sec is preferred. As a result, the aluminum nitride film 10 is partially formed on the surface of the aluminum alloy film 7 and a part of the bottom of the hole (see FIG. 2D).

Since the nitride ions 10 'are incident on the silicon substrate 1 almost perpendicularly, the aluminum alloy film 7 on the side wall of the hole, which is shadowed by the overhang portion, is not nitrided. The aluminum nitride alloy layer 11 is also strong like the alloy layer of aluminum and titanium, and thus has an effect of suppressing the diffusion amount of aluminum atoms above the wiring. Therefore, the same operation and effect as those of the first embodiment can be obtained, and thereafter, the inside of the hole is filled with the aluminum alloy film 7 without voids by performing a heat treatment at 400 to 500 ° C. without breaking the vacuum (FIG. 2).
(E)).

In the first embodiment, titanium is described as an example. However, the present invention is not limited to this as long as the same effect can be obtained with other film types.

In the second embodiment, nitrogen plasma is described as an example. However, the present invention is not limited to oxygen plasma as long as the same effect can be obtained.

Further, in both the first and second embodiments,
Although an aluminum alloy film has been described as an example of the conductor layer,
If the same effect as that of a copper film can be obtained, it can be applied to other conductor types.

Needless to say, the same effect can be obtained not only in the contact hole but also in the through hole connecting the wirings.

[0049]

As described above, according to the present invention,
This has the effect that the conductor film can be embedded without voids even in fine holes.

The reason is that, in the present invention, before the conductor film is buried in the hole by heating, the treatment for suppressing the diffusion of the conductor atoms in the upper part of the conductor wiring is performed, so that the inside of the hole (side wall) is formed. Priority is given to conductor atom diffusion, so that the overhang portion of the conductor layer is closed before completion of filling in the hole, and it is possible to prevent voids from being formed, and it is possible to bury the conductor film without voids even in fine holes. That's why.

Further, in the present invention, an existing process (conventional sputtering method) may be used, so that investment in new equipment is not required.

As described above, according to the method for manufacturing a semiconductor device of the present invention, fine holes can be buried without causing extra investment and a decrease in productivity, and the production yield and reliability of a semiconductor integrated circuit are improved. And its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is a process sectional view schematically showing a manufacturing process of a first embodiment of the present invention in the order of processes.

FIG. 2 is a process sectional view schematically showing a manufacturing process of a second embodiment of the present invention in the order of processes.

FIG. 3 is a process sectional view schematically showing a manufacturing process of a conventional aluminum reflow method in a process order.

FIG. 4 is a process sectional view of a conventional improved aluminum reflow method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Interlayer insulating film 3 Impurity diffusion layer 4 Titanium film 5 Titanium nitride film 6 Titanium film 7 Aluminum alloy film 8 Titanium thin film 8 'Titanium particles 9 Aluminum and titanium alloy film 10 Aluminum nitride film 10' Nitrogen ion 11 Void 12 CVD-Aluminum A Hole side wall B Wiring top

Claims (4)

(57) [Claims] A step of forming a conductive region or a conductor wiring on a substrate; a step of forming an insulator layer having a connection hole on the conductive region or the conductor wiring; Forming a body wiring material, and further comprising a step of heat-treating the substrate to fill the connection holes with the conductor wiring material, wherein the conductor wiring material is an aluminum alloy film. Or made of copper film ,
The formed conductor wiring made of an aluminum alloy film or a copper film
The surface of the material, method of manufacturing a semiconductor device for forming a thin titanium film into an island shape, it is characterized. 2. A step of forming a conductive region or a conductor wiring on a substrate; a step of forming an insulator layer having a connection hole on the conductive region or the conductor wiring; Forming a body wiring material, and further comprising: heat-treating the substrate to fill the connection holes with the conductor wiring material; and forming a surface of the conductor wiring material formed before the heat treatment. A method of manufacturing a semiconductor device for performing a treatment for suppressing diffusion of atoms forming the conductor during the heat treatment, wherein the conductor wiring material is made of an aluminum alloy film or a copper film ;
A method for manufacturing a semiconductor device, wherein the treatment for suppressing the diffusion of atoms forming the conductor comprises exposing the surface of the conductor film to nitriding plasma. 3. A conductive wiring material made of an aluminum alloy film or a copper film is formed in a contact hole or a through hole (hereinafter simply referred to as a “hole”) provided in an insulating film formed on a substrate, and heat treatment is performed. By embedding the inside of the hole with the conductive wiring material by applying, a titanium film is formed in an island shape on the surface of the conductive wiring material made of the aluminum alloy film or the copper film in which the hole is embedded. A method of manufacturing a semiconductor device, comprising: suppressing a diffusion amount of atoms of the conductive wiring material in an upper part of a wiring layer, thereby enabling burying of a fine contact hole without voids. 4. A contact hole or a through hole (hereinafter simply referred to as "hole") provided in an insulating film formed on a substrate.
), A conductive wiring material made of an aluminum alloy film or a copper film is formed, and the hole is filled with the conductive wiring material by performing a heat treatment. Further, the surface of the conductive wiring material is exposed to nitrogen plasma without breaking vacuum. A method for manufacturing a semiconductor device, wherein the exposure reduces the amount of diffusion of atoms of the conductive wiring material in the upper part of the wiring layer, thereby enabling fine contact holes to be buried without voids.