JPH113892A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper wiring of low resistance and high reliability by preventing surface oxidation of the copper wiring etc., and easily burying interlayer films between wiring layers, and decreasing absolute steps. SOLUTION: An insulating film 12, a titan film 14 and a titan nitride film 16 as a first barrier film, a copper film 18, a titan nitride film 20 as a second barrier film, and a silicon nitride film 22 as a film for forming an etching mask are sequentially laminated on a silicon substrate 10, and a photoresist 24 is coated thereon, and a wiring pattern is formed by a photolithography technique, and the silicon nitride film 22 is etched using the photoresist 24 as an etching mask to form an etching mask 22. After the photoresist 24 is removed by ashing wiring layer is formed by etching using the etching mask 22, and the etching mask 22 is removed by etching, and immersed in a benzotriazol liquid to form a Cu-BTA (benzotriazole) compound 26 at the sidewall of the copper film 18. And an interlaminar insulating film 28 is formed to obtain the copper wiring of low resistance and high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device in which an element using copper as a wiring material is formed on a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, an IC, an LSI or a super LSI in which a large number of elements and wirings are formed on a semiconductor substrate at high density.
And the like are manufactured. In order to achieve higher speed and higher capacity in this type of semiconductor device,
It was necessary to increase the degree of integration. However, the reduction in wiring width due to this higher integration leads to higher resistance,
It is desirable to use a wiring material having as small a resistance as possible. For this reason, recently, a semiconductor device using copper, which is a low-resistance material, as a wiring material instead of aluminum or the like has been proposed.

[0005] FIGS. 5A to 5 C show a part of a manufacturing process of a conventional semiconductor device when copper is used as a wiring material. Here, in order to simplify the description, description of a method for forming a transistor portion is omitted.

As shown in FIG. 5A, an insulating film 52 is formed on a silicon substrate 50 by a CVD (Chemical Vapor Deposition) method to separate a transistor portion from a wiring layer. Is done. Then, a titanium film (Ti) 54 is formed on the insulating film 52 by a sputtering method, and a titanium nitride film (TiN) 56 is formed thereon by a reactive sputtering method or an RTA (Rapid Thermal Anneal) method. Further, a copper film (Cu) is formed thereon by sputtering or CVD.
58 had been formed.

Next, as shown in FIG. 5B, a photoresist 6 having a thickness of about 1.0 μm is formed on the copper film (Cu) 58.
In addition, a wiring layer is formed by applying a reactive ion etching (RIE) method after applying a desired wiring pattern by photolithography to form a desired wiring pattern using this as an etching mask. As an etching gas used for performing the reactive ion etching, for example, silicon tetrachloride (SiCl ₄ ), nitrogen (N ₂ ), and argon (Ar) have been used. The temperature of the silicon substrate 50 was set to about 300 ° C. because the vapor pressure of copper chloride generated by etching was low and the etching rate was low. Then, after removing the photoresist 60 by the oxygen ashing method, FIG.
As shown in (c), the insulating film 62 was formed as an interlayer film filling the space between the wiring layers.

[0006]

However, in such a conventional method of manufacturing a semiconductor device, the step of removing the photoresist 60 by oxygen ashing and the step of forming the insulating film 62 involve a copper film. There was a disadvantage that the electric resistance of the No. 58 increased. This is because the surface of the copper film 58 is oxidized by oxygen plasma or ozone used for ashing, and when the insulating film 62 is formed by a plasma CVD method or the like, the copper oxide is formed in a high-temperature oxygen atmosphere or by an oxygen plasma. Is probably formed. That is, copper oxide (for example, Cu ₂ O, C
uO) has a high electrical resistance and, unlike alumina (aluminum oxide: Al ₂ O ₃ ), oxidation of copper is promoted by diffusing into the interior, so that the wiring width tends to be narrower due to integration, and copper As the oxidation proceeds, the overall wiring resistance rises at a stretch.

Therefore, various methods have been proposed to prevent oxidation of copper wiring. For example, JP-A-63-1
No. 74336 proposes a method of forming an antioxidant film on the surface of a copper wiring. However, since this method only considers oxidation of the copper surface, oxidation from the side wall is likely to occur. There is a disadvantage that the total thickness of the wiring layer becomes large and it becomes difficult to bury the interlayer insulating film.

Further, JP-A-62-290150, JP-A-63-73645, and JP-A-63-156341.
JP-A-6-275620, JP-A-6-27562
No. 1, JP-A-6-130743, and the like,
In order to prevent oxidation not only from the surface of the copper wiring but also from the side wall, a method has been proposed in which an antioxidant film is formed on the entire substrate after the copper wiring is formed. However, these methods are not practical because oxidation at the time of ashing as described above is not considered, and cannot be applied to a fine pattern because an oxidation prevention film is formed after forming a copper wiring. Further, there is an inconvenience that it is difficult to bury the interlayer film.

Therefore, in each of these methods, the copper film is always oxidized at the time of ashing, so that a heat treatment is applied in an atmosphere containing hydrogen to reduce the copper oxide oxidized at the time of ashing to form a copper film. Has also been proposed. However, in this method, hydrogen diffuses into the copper film and is reduced to copper (Cu) by a reaction of (Cu ₂ O + H ₂ → 2Cu + H ₂ O). At the same time, water vapor is generated. The water vapor has a disadvantage that bubbles and cracks are generated in the copper film to deteriorate the film quality.

Therefore, in order to prevent oxidation during ashing, for example, according to Japanese Patent Application Laid-Open No. 6-244181, a film of another constituent element is formed on a film for preventing oxidation of the upper surface of copper. First, there has been proposed a method in which a hard mask is formed by patterning this film with a resist, and after removing the resist, the copper laminated film is patterned by the hard mask to form an interlayer insulating film thereon.
However, in this method, although the oxidation at the time of ashing can be prevented, the film thickness of the wiring pattern is increased by forming the hard mask, so that the film thickness of the interlayer film necessary for filling is also increased. There was an inconvenience. That is, as the thickness of the interlayer film increases, the depth of the connection hole increases, and the time required for etching to form the connection hole increases, so that the throughput decreases and the dimensional controllability deteriorates. In addition, when the thickness of the wiring pattern is increased, voids (Voi) are formed between the wirings when the interlayer film is formed.
A cavity referred to as d) is likely to occur. Furthermore, as the film thickness of the wiring pattern increases, the absolute step increases,
Even if an interlayer film is formed, it is difficult to planarize, and there is an inconvenience that exposure becomes more difficult as the wiring becomes higher.

The present invention has been made in view of the inconveniences of the prior art, and prevents oxidation of copper wiring, diffusion of copper from an insulator, and diffusion of impurities with respect to copper. An object of the present invention is to provide a method for manufacturing a semiconductor device having a low-resistance and high-reliability copper wiring by appropriately embedding between wirings to reduce an absolute step in an upper wiring at the time of exposure.

[0012]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device in which an element using copper as a wiring material is formed on a semiconductor substrate. Forming an insulating film on the substrate, sequentially forming a first barrier film, a copper film, and a second barrier film on the insulating film; and forming an etching mask on the second barrier film Forming a film for forming an etching mask; applying a photosensitive agent on the film for forming the etching mask; selectively exposing the photosensitive agent to form a predetermined wiring pattern on the photosensitive agent; Etching the film for forming the etching mask using the patterned photosensitive agent as a mask to form an etching mask; removing the photosensitive agent; and using the etching mask to form the first flash. Forming a wiring layer by etching the film, the copper film, and the second barrier film; removing the etching mask; forming a layer for preventing oxidation and diffusion on at least a side wall of the copper wiring layer And a step of forming a protective film covering the entire wiring layer.

According to this, a first barrier film, a copper film, and a second barrier film are sequentially formed on the insulating film, and the resultant is etched to form a wiring layer. Can be protected from oxidation and the like by a barrier film. When a wiring layer is formed by this etching, a photosensitive agent such as a photoresist is not directly used as an etching mask, but an etching mask is formed using a photosensitive agent when patterning a film for forming an etching mask. Since etching is performed using an etching mask (also referred to as a hard mask), oxidation of copper due to ashing used for removing a photosensitive agent can be prevented. Also,
Since this etching mask is removed after the wiring layer is formed by etching, the total thickness of the wiring pattern does not increase, so that the embedding characteristics when embedding the protective film between the wirings are not impaired, and the generation of voids and the like does not occur. Can be suppressed. In addition, since the etching mask can be configured to be thick, a large margin for the etching conditions of the wiring layer can be obtained. Furthermore, since the thickness of the protective film required for embedding can be reduced, the depth of the connection hole is reduced, the time required for etching is shortened, the throughput is improved, and the dimensional controllability of the connection hole is good. Becomes Further, when the film thickness of the wiring pattern is reduced, the absolute step can be reduced, so that a large margin of the exposure condition for the upper wiring can be obtained. As described above, since a copper wiring that can reliably prevent oxidation and the like can be formed on a semiconductor substrate, a semiconductor device with low resistance and high reliability can be manufactured.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device in which an element using copper as a wiring material is formed on a semiconductor substrate, wherein a step of forming an insulating film on the substrate, A step of sequentially forming a first barrier film, a copper film, and a second barrier film on the film; a step of forming a film for forming an etching mask on the second barrier film; Applying a photosensitive agent on the film, forming a predetermined wiring pattern on the photosensitive agent by selectively exposing the photosensitive agent, and etching the mask using the photosensitive agent on which the wiring pattern is formed as a mask. Etching a film for formation to form an etching mask; removing the photosensitive agent; and etching the first barrier film, the copper film, and the second barrier film using the etching mask. A step of forming a wiring layer; a step of removing the etching mask and the second barrier film; a step of forming a layer for preventing oxidation and diffusion on the upper surface and side walls of the copper wiring layer; Forming a protective film covering the entire layer.

According to this, in addition to the effect of the first aspect, after the wiring layer is formed by etching using the etching mask, the second barrier film is removed together with the etching mask. . For this reason, it is possible to further reduce the thickness of the wiring layer, to further improve the embedding characteristics of the protective film for embedding the wiring layer, to reduce the thickness of the protective film, and to reduce the depth of the connection hole. Since the depth becomes shallower, the time required for etching becomes shorter, the throughput is improved, and the dimensional controllability of the connection hole can be improved. In addition, if the thickness of the wiring layer is reduced, the absolute step is further reduced, and the margin of the exposure condition of the upper wiring can be further increased. As described above, since a copper wiring that can reliably prevent oxidation and the like can be formed on a semiconductor substrate, a semiconductor device with low resistance and high reliability can be manufactured.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the first barrier film and the second barrier film are made of silicon nitride, silicon oxynitride, and titanium nitride. , Tungsten nitride, titanium tungsten nitride, tungsten, niobium, niobium nitride,
It is one of aluminum, tantalum and tantalum nitride.

According to this, since the first barrier film and the second barrier film are formed of the material for preventing the oxidation of the copper wiring, the oxidation of the copper wiring is reliably prevented by these barrier films. Can be.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the film for forming an etching mask is made of one of silicon nitride, silicon oxide, and silicon oxynitride. It is characterized by being.

According to this, since the film on which the etching mask is formed is made of a material constituting a so-called hard mask, ashing when removing the etching mask is unnecessary, and oxidation of the copper film during ashing is prevented. be able to. Further, by using a material having an easy etching selectivity with the second barrier film at the time of etching when forming the etching mask, the etching mask can be surely formed.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the film for forming an etching mask and the second barrier film are different film types. It is characterized by the following.

According to this, since the film for forming the etching mask and the second barrier film are formed of different film types, the film for forming the etching mask is etched to form the etching mask. A selectivity can be obtained, and an etching mask can be formed reliably.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the step of etching the film for forming an etching mask to form an etching mask includes the step of: 2 is left.

According to this, when a film for forming an etching mask is etched by using a photosensitive agent such as a photoresist as a mask, the etching mask is surely formed by over-etching to the second barrier film thereunder. be able to. At this time, since the etching is performed so as to leave the second barrier film, the copper film can be prevented from being oxidized even if the photosensitive agent is removed by ashing.

According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor device according to the first, second, or sixth aspect, the step of etching the film for forming an etching mask to form an etching mask. Is characterized by containing a compound represented by CnHmF (2n + 2-m).

According to this, when etching the film for forming the etching mask, CnHmF (2n + 2-m)
In order to use an etching gas containing a compound represented by
The etching mask can be formed by reliably patterning the film for forming the etching mask.

According to an eighth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first, second, sixth, or seventh aspect, the film for forming the etching mask is etched. Is characterized in that the etching rate of the second barrier film is lower than the etching rate of the film for forming the etching mask.

According to this, as the etching condition, the etching rate of the second barrier film is lower than the etching rate of the film for forming the etching mask.
An etching mask can be formed by reliably patterning a film for forming an etching mask while leaving the second barrier film.

According to a ninth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the first barrier film, the second barrier film, and the copper film are formed by using the etching mask. The etching gas used in the step of forming a wiring layer by etching is a gas containing chlorine.

According to this, when etching is performed in the step of forming the wiring layer, by using a gas containing chlorine, the vapor pressure of (CrCl) ₃ is increased by another gas (for example, F,
Since it is higher than the vapor pressure of the copper halide such as I), the copper wiring can be surely formed.

According to a tenth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, the etching gas used in the step of removing the etching mask is C gas.
It is characterized by containing a compound represented by nHmF (2n + 2-m).

According to this, in the step of removing the etching mask, the etching is performed by using the etching gas containing the compound represented by CnHmF (2n + 2-m), thereby leaving the second barrier film. The mask can be reliably removed.

According to an eleventh aspect of the present invention, in the method of manufacturing a semiconductor device according to the second aspect, the etching gas used in the step of removing the etching mask and the second barrier film is hexafluoride. It is characterized by containing sulfur.

According to this, in the step of removing the etching mask and the second barrier film, sulfur hexafluoride (C
By performing etching using an etching gas containing F ₆ ), the etching mask and the second barrier film can be reliably removed. Then, when the etching mask and the second barrier film are surely removed, the thickness of the entire wiring layer can be reduced, the filling between the wirings with a protective film or the like is properly performed, and the voids between the wirings are formed. Is less likely to occur. Also, when the thickness of the protective film necessary for filling is reduced, the depth of the connection hole becomes shallower, the time required for etching becomes shorter, the throughput can be improved, and the dimensional controllability of the connection hole becomes better. . Further, if the film thickness of the wiring layer is reduced, the absolute step can be reduced, so that a large margin for the exposure conditions of the upper wiring can be obtained.

According to a twelfth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or tenth aspect,
The etching condition used in the step of removing the etching mask is characterized in that the etching rate of the second barrier film is lower than the etching rate of the film of the etching mask.

According to this, as the etching condition, the etching rate of the second barrier film is made slower than that of the etching mask, so that only the etching mask is surely etched while leaving the second barrier film. Can be removed.

According to a thirteenth aspect, in the method of manufacturing a semiconductor device according to the second or eleventh aspect,
The etching conditions used in the step of removing the etching mask and the second barrier film are such that an etching rate of the film for forming the etching mask is substantially equal to an etching rate of the second barrier film. I do.

According to this, as the etching conditions, the etching rate of the film for forming the etching mask and the etching rate of the second barrier film are made substantially equal, so that the etching mask and the second barrier film can be reliably formed. Can be removed.

According to a fourteenth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the step of forming a layer for preventing oxidation and diffusion on at least a side wall of the copper wiring layer is performed. The surface of the wiring layer is treated in a gas atmosphere.

According to this, by treating the surface of the wiring layer in a gas atmosphere, a layer for preventing oxidation and diffusion can be formed on at least the side wall of the copper wiring layer.

According to a fifteenth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the step of forming a layer for preventing oxidation and diffusion on at least a side wall of the copper wiring layer is performed. Wherein the surface of the wiring layer is subjected to a solution treatment.

According to this, by performing a solution treatment on the surface of the wiring layer, a layer for preventing oxidation and diffusion can be formed on at least the side wall of the copper wiring layer.

According to a sixteenth aspect of the present invention, in the semiconductor device according to the first or second aspect, the step of forming a layer for preventing oxidation and diffusion on at least a side wall of the copper wiring layer includes the step of forming the wiring It is characterized in that impurities are implanted into the layer.

According to this, a layer for preventing oxidation and diffusion can be formed on at least the side wall of the copper wiring layer by implanting impurities into the wiring layer.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the method of manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows Embodiment 1
4 is a process sectional view illustrating the method for manufacturing the semiconductor device according to FIG. In FIG. 1A, an insulating film 12 for separating a transistor portion and a wiring layer is formed on a silicon substrate 10.
Is formed by a CVD (Chemical Vaper Deposition) method.

Next, on the insulating film 12, a titanium film (Ti) 14 as a first barrier film and a titanium nitride film (Ti
N) 16 are formed. Next, a copper film (Cu) 18 is formed on the titanium nitride film (TiN) 16 and a titanium nitride (TiN) 20 as a second barrier film is formed thereon.
Are sequentially formed. Here, the titanium film (Ti) 14 is
The titanium nitride film (TiN) 20 is formed by a sputtering method or a CVD method, and is formed by a reactive sputtering method in a nitrogen atmosphere or a CVD method using a source gas containing nitrogen. ) 18
Is formed by a sputtering method or a CVD method. This copper film 18 is not limited to pure copper,
It may contain some other elements, or may be a copper alloy.

In this case, the thicknesses of the titanium film (Ti) 14 are 150 angstroms, the titanium nitride film (TiN) 16 is 800 angstroms, and the copper film (C
u) 18 Å, 5000 angstrom, titanium nitride film 2
Although 0 was formed as 800 Å, it is not necessarily limited to these film thicknesses. Here, as a film for forming an etching mask which is used as an etching mask in a later step, a silicon nitride film (SiN) 2
2 is formed, and its film thickness is about 3000 Å.

As described above, the insulating film 12, the first barrier film [titanium film (Ti) 14, titanium nitride film (TiN) 16], the copper film (Cu) 18, the second film
Barrier film [titanium nitride film (TiN) 20], film for etching mask formation [silicon nitride film (SiN) 22]
Are sequentially laminated and then, as shown in FIG.
A photoresist 24 is applied on silicon nitride (SiN) 22 to a thickness of about 1.0 μm, and a desired wiring pattern is formed using photolithography.

Then, reactive ion etching (RI
The film for forming the etching mask [silicon nitride film (SiN) using the photoresist 24 as a mask by the method E).
22], thereby etching the etching mask 2
Form 2 The etching gas at this time is CF
Etching is performed by reactive ion etching using ₄ and H ₂ . As the gas flow rate in this case, CF ₄ is 25
A (SCCM), H ₂ is 15 (SCCM). When the high frequency power at the time of etching is 400 (W) and the gas pressure is 5 (mTorr), the etching rate ratio between the silicon nitride (SiN) 22 and the titanium nitride film (TiN) 20, which is a hard mask, is SiN. / TiN = 6. Therefore, in order to reliably pattern the silicon nitride (SiN) 22, the titanium nitride film (TiN) 20 as the second barrier film is not lost even if over-etching is performed. The silicon nitride (SiN) 22 is etched while leaving the etching mask, so that an etching mask can be reliably formed.

Next, as shown in FIG. 1C, the photoresist 24 is removed by ashing. At this time, since the surface of the copper film (Cu) 18 is covered with titanium nitride (TiN) 20, which is a second barrier film, it is not oxidized.

Next, as shown in FIG. 1D, a titanium nitride film (TiN) 20 to a titanium film (TiN) are formed by reactive ion etching (RIE) using the silicon nitride film (SiN) 22 as an etching mask. ) Wiring is formed by etching up to 14. As an etching gas at this time, chlorine (Cl ₂ ), silicon tetrachloride (SiCl ₄ ), nitrogen (N ₂ ), and argon (Ar) are used. The gas flow rate here is chlorine (Cl
₂ ) 25 (SCCM), silicon tetrachloride (SiCl ₄ ) 25 (SCCM), nitrogen (N ₂ ) 100 (SCCM), and argon (Ar) 50 (SCCM). The high-frequency power at the time of etching is 400 (W), and the pressure is 15 (mT
orr). The temperature of the silicon substrate is set to about 300 ° C. because the vapor pressure of copper chloride generated by etching is low and the etching rate is low. In this case, the respective etching rate ratios of silicon nitride (SiN) 22 and copper (Cu), which are hard masks, and titanium nitride film (TiN) 20 are SiN / TiN ≒ 10,
SiN / Cu ≒ 10.

Next, as shown in FIG. 1E, the above-mentioned film for forming an etching mask [silicon nitride film (SiN) 22] is removed. At this time, etching was performed by reactive ion etching using CF ₄ and H ₂ as an etching gas. In this case, the gas flow rate is 25 (SCCM) for CF _{4 and} 15 (SCCM) for H ₂ . The high frequency power is 400 (W) and the pressure is 5
(MTorr), the ratio of the etching rates of the silicon nitride (SiN) 22 and the titanium nitride film (TiN) 20, which is a hard mask, was set to SiN / TiN = 6.
A film for forming an etching mask [silicon nitride (Si) is formed while leaving a titanium nitride film (TiN) 20 as a second barrier film.
N) 22] can be reliably removed. As described above, since the film for forming the etching mask is finally removed, the thickness of the film for forming the etching mask can be increased, so that the margin of the etching conditions in forming the wiring pattern can be increased. Can be.

Next, in FIG. 1F, a silicon wafer for forming a semiconductor device is immersed in a solution containing benzotriazole (BTA). At this time, the copper film (C
Since the insoluble Cu-BTA compound 26 is formed on the surface (side wall) of u) 18, a barrier layer for preventing oxidation of copper can be formed.

Next, as shown in FIG. 1G, an interlayer insulating film 28 is formed as a protective film for burying the wiring layers and protecting the wiring layers at the same time.

As described above, according to the first embodiment, the surface of the copper film (Cu) 18 is
6, it is not oxidized to the inside of the wiring,
Resistance rise can be prevented.

Further, since the etching mask [silicon nitride (SiN) 22] is removed here, the thickness of the entire wiring layer can be reduced, and the characteristics of embedding the interlayer insulating film 28 between the wirings are impaired. And voids are less likely to occur between wirings. Furthermore, when the thickness of the entire wiring layer is reduced, the thickness of the interlayer film required for embedding can be reduced, so that the depth of the connection hole is reduced, the time required for etching is reduced, and the throughput is improved. And the dimensional controllability of the connection hole is improved. Further, since the silicon nitride (SiN) 22, which is a hard mask, is finally removed, a thick hard mask can be formed, and the etching conditions (selection ratio between the hard mask and the wiring layer) when forming a wiring pattern can be reduced. The margin can be increased. Further, as described above, if the total thickness of the wiring is reduced, the absolute step is reduced, so that the margin of the exposure condition of the wiring in the upper layer can be widened.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described with reference to FIG. Here, for the same or equivalent components as in the first embodiment described above,
The same reference numerals are given and the description is simplified or omitted.

The manufacturing steps of the semiconductor device according to the second embodiment shown in FIG. 2 are the same up to FIG.
(E) and subsequent steps are shown in FIGS. 2 (a) to 2 (c). Therefore, only the steps characteristic of the second embodiment will be described with reference to FIG.

In FIG. 1D described above, after etching the titanium nitride film (TiN) 20 to the titanium film (Ti) 14 using the etching mask 22, FIG.
The feature of the second embodiment resides in that the etching mask 22 and the titanium nitride film (TiN) 20 as the second barrier film are simultaneously removed by RIE as shown in FIG. The etching mask 22 and the second barrier film 20
Here, a gas containing sulfur hexafluoride (SF ₆ ) is used as an etching gas used for etching and removing. As for the etching conditions, the material is selected so that the etching rates of the etching mask 22 and the second barrier film 20 are substantially equal.

As described above, the etching mask 22
2B and the second barrier film 20, the silicon wafer is immersed in a solution containing benzotriazole (BTA), as shown in FIG. The Cu-BTA compound 26 can be formed on the (upper surface and side wall), thereby forming a barrier layer that protects the surface of the copper film 18 from being oxidized.

Then, as shown in FIG. 2C, an interlayer insulating film 28 is formed as a protective film for burying the wiring layers and protecting the wiring layers at the same time.

As described above, according to the second embodiment, the surface (upper surface and side wall) of the copper film (Cu) 18 is made of Cu-B
Since the wiring is covered with the TA compound 26, it is not oxidized to the inside of the wiring, and the resistance can be prevented from rising. Further, since the etching mask 22 and the second barrier layer 20 are removed, the thickness of the wiring layer can be further reduced, and the interlayer insulating film 28 can be removed.
The characteristics of embedding between the wirings are improved, and voids are less likely to be generated between the wirings. Furthermore, since the thickness of the interlayer film required for embedding can be further reduced, the depth of the connection hole becomes shallower, the time required for etching becomes shorter, the throughput can be further improved, and the dimensional controllability of the connection hole is improved. It will be good.

Also in the case of the second embodiment, since the hard mask is finally removed, it is possible to form the hard mask thickly, and the etching conditions (forming the hard mask and the wiring layer) at the time of forming the wiring pattern can be obtained. The margin of the etching selectivity can be increased.

In the second embodiment, since the total thickness of the wiring layer is further reduced and the absolute step can be reduced, the margin of the exposure condition of the upper wiring can be widened.

Embodiment 3 Next, Embodiment 3 of the present invention will be described with reference to FIG. Here, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

The manufacturing steps of the semiconductor device according to the third embodiment shown in FIG. 3 are the same steps up to FIG.
(F) and subsequent steps are shown in FIGS. 3 (a) and 3 (b). Therefore, only the steps characteristic of the third embodiment will be described with reference to FIG.

In FIG. 1E, after removing the film for forming the etching mask, as shown in FIG. 3A, the surface of the wiring layer is treated in a gas atmosphere to oxidize and oxidize. Embodiment 3 is characterized in that a barrier layer for preventing diffusion is formed. As a gas used for treating the surface of the wiring layer in a gas atmosphere, silane (Si
A gas containing H ₄ ) is used. By heating the substrate to about 300 ° C. and flowing silane gas in a vacuum vessel, copper and the silane gas undergo a solid-gas phase reaction to form a thin copper silicide 30 on the surface. This forms a barrier layer that protects the surface of the copper film 18 from being oxidized.

Next, as shown in FIG. 3B, an interlayer insulating film 28 is formed as a protective film for burying the wiring layers and protecting the wiring layers at the same time.

As described above, according to the third embodiment, since the surface of copper film (Cu) 18 is covered with silicide, it is not oxidized to the inside of the wiring, and the resistance is not increased. can do. In addition, since a treatment is performed in a gas atmosphere to form a layer for preventing oxidation and diffusion on the surface of the copper wiring layer, the treatment can be performed in a vacuum vessel continuously with the step of removing the film for forming the etching mask. Since the formation of the oxide film is hindered, an increase in the resistance value can be further suppressed.

In the third embodiment, the method in which only the etching mask 22 is removed has been described. However, as in the second embodiment, the etching mask 22 and the second barrier film 2 are removed.
0 may be removed at the same time, and the method is not limited to this.

Although silane is shown as the gas for the atmosphere treatment, it is not limited to this. For example, disilane may be used.

Although the silicide of copper is shown as the substance formed by the treatment in the gas atmosphere, the substance is not limited to this as long as it can prevent oxidation of copper.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. Here, the same or equivalent components as those in the first, second, and third embodiments are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

The manufacturing steps of the semiconductor device according to the fourth embodiment shown in FIG. 4 are the same steps up to FIG.
(F) and subsequent steps are shown in FIGS. 4 (a) and 4 (b). Therefore, only the steps characteristic of the fourth embodiment will be described with reference to FIG.

In FIG. 1E, after removing the film for forming the etching mask, as shown in FIG. 4A, silicon (Si) is implanted into the side wall of the wiring layer by ion implantation. Embodiment 4 is characterized in that a barrier layer for preventing oxidation and diffusion is formed. At this time, the semiconductor substrate on which the wiring layer is formed is tilted and rotated at an angle of about 5 °, not perpendicularly to the silicon injection direction. As a result, silicon is also injected into the very side surface of the wiring.

Then, a heat treatment is performed in an oxygen or nitrogen atmosphere to form a copper silicide 32 and a copper film 18.
Surface is oxidized or nitrided, and the barrier properties are further improved.

Next, as shown in FIG. 4B, an interlayer insulating film 28 is formed as a protective film for burying the wiring layers and protecting the wiring layers at the same time.

As described above, according to the fourth embodiment, since the surface of copper film (Cu) 18 is covered with silicide, it is not oxidized to the inside of the wiring, and the resistance is not increased. can do.

In the fourth embodiment, the method of removing only the etching mask 22 has been described. However, as in the second embodiment, the etching mask 22 and the second barrier film 2 are removed.
0 may be removed at the same time, and the method is not limited to this.

Although silicon is shown as an ion species to be implanted, the present invention is not limited to this.

In addition, although silicide of copper has been described as a substance formed by ion implantation, any substance that prevents oxidation of copper may be used, and is not limited thereto.

In each of the above-described embodiments, a titanium film (T
i) A titanium nitride film (TiN) 16 was shown by 14 and reactive sputtering in a nitrogen atmosphere, and a titanium nitride film (TiN) 20 was shown as a second barrier film by reactive sputtering in a nitrogen atmosphere. However, as long as it prevents copper oxidation, it is not limited to titanium nitride. As other materials, for example, silicon nitride, silicon oxynitride, titanium nitride, tungsten nitride, titanium tungsten nitride, tungsten, chromium, niobium, niobium nitride, aluminum, tantalum, and tantalum nitride may be used.

[0083]

As described above, according to the method of manufacturing a semiconductor device according to the first aspect, it is possible to prevent oxidation of copper due to ashing when removing the photosensitive agent, and to reduce the thickness of the wiring layer. Can be formed thinly, the characteristics of embedding the protective film between the wirings are not impaired, the generation of voids and the like can be suppressed, and a large margin for the etching conditions of the wiring layer can be obtained. In addition, since the thickness of the protective film required for filling can be reduced, the depth of the connection hole becomes shallower, the time required for etching becomes shorter, the throughput can be improved, and the dimension controllability of the connection hole can be improved. Is good. Further, since the film thickness of the wiring layer is reduced, the absolute step is reduced, and a large margin for the exposure condition of the upper wiring can be obtained. In this way, a low-resistance and highly-reliable copper wiring can be formed.

According to the method of manufacturing a semiconductor device of the second aspect, in addition to the effect of the first aspect, the thickness of the wiring layer can be further reduced, so that the protective film covering the wiring layer can be formed. The embedding characteristics are improved, the thickness of the protective film can be reduced, the depth of the connection hole becomes shallower, the time required for etching becomes shorter, the throughput can be improved, and the dimension controllability of the connection hole is improved. It will be good. Further, when the film thickness of the wiring layer is reduced, the absolute step is further reduced, and the margin of the exposure condition of the upper wiring can be further increased. In this way, a low-resistance and highly-reliable copper wiring can be formed.

According to the method of manufacturing a semiconductor device of the third aspect, since the first barrier film and the second barrier film are formed of a material that prevents oxidation of the copper wiring, the oxidation of the copper wiring is prevented. These barrier films can reliably prevent this.

According to the method of manufacturing a semiconductor device of the present invention, since the film forming the etching mask is made of a material forming a so-called hard mask, ashing is not required when removing the etching mask. Becomes
The copper film can be prevented from being oxidized at the time of ashing, and a material having an easy etching selectivity with the second barrier film at the time of etching at the time of forming the etching mask is formed, so that the etching mask is surely formed. be able to.

According to the method of manufacturing a semiconductor device of the fifth aspect, the film for forming the etching mask and the second barrier film are formed of different film types, so that the film for forming the etching mask is formed. When an etching mask is formed by etching, an etching selectivity can be obtained, and the etching mask can be formed reliably.

According to the method of manufacturing a semiconductor device of the sixth aspect, the etching mask is formed by etching the film for forming the etching mask so as to leave the second barrier film. Therefore, the photosensitive agent is removed by ashing. Even so, the copper film can be prevented from being oxidized.

According to the method of manufacturing a semiconductor device of the present invention, an etching gas containing a compound represented by CnHmF (2n + 2-m) is used when etching a film for forming an etching mask. An etching mask can be formed by reliably patterning a film for forming a mask.

According to the method of manufacturing a semiconductor device of the present invention, as the etching condition, the etching speed of the second barrier film is lower than the etching speed of the film for forming the etching mask. The etching mask can be formed by reliably patterning the film for forming the etching mask while leaving the second barrier film.

According to the method of manufacturing a semiconductor device according to the ninth aspect, since the etching gas used in the step of forming the wiring layer is a gas containing chlorine, oxidation of the copper wiring is prevented. Furthermore, a low-resistance and high-reliability copper wiring can be provided without affecting the filling characteristics of the interlayer film.

According to the method of manufacturing a semiconductor device of the tenth aspect, in the step of removing the etching mask,
Since the etching is performed using the etching gas containing the compound represented by CnHmF (2n + 2-m), the etching mask can be surely removed while leaving the second barrier film.

According to the method of manufacturing a semiconductor device of the eleventh aspect, in the step of removing the etching mask and the second barrier film, etching is performed using an etching gas containing sulfur hexafluoride (CF ₆ ). As a result, the etching mask and the second barrier film can be reliably removed.

According to the method of manufacturing a semiconductor device of the twelfth aspect, as the etching condition, the etching rate of the second barrier film is lower than the etching rate of the etching mask. Only the etching mask can be surely etched and removed.

According to the method of manufacturing a semiconductor device of the present invention, as the etching conditions, the etching rate of the film for forming the etching mask and the etching rate of the second barrier film are substantially equal. The second barrier film and the second barrier film can be reliably removed.

According to the semiconductor device manufacturing method of the present invention, since the surface of the wiring layer is treated in a gas atmosphere, a layer for preventing oxidation and diffusion is formed on at least the side wall of the copper wiring layer. can do.

According to the method of manufacturing a semiconductor device of the present invention, the surface of the wiring layer is subjected to the solution treatment.
A layer for preventing oxidation and diffusion can be formed on at least the side wall of the copper wiring layer.

According to the method of manufacturing a semiconductor device of the sixteenth aspect, since impurities are implanted into the wiring layer, a layer for preventing oxidation and diffusion is formed on at least the side wall of the copper wiring layer. Can be.

[Brief description of the drawings]

FIG. 1 is a process sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment.

FIG. 2 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment.

FIG. 3 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the third embodiment.

FIG. 4 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the fourth embodiment.

FIG. 5 is a process sectional view illustrating a method for manufacturing a conventional semiconductor device.

[Explanation of symbols]

Reference Signs List 10 silicon substrate (semiconductor substrate) 12 insulating film 14 titanium film (part of first barrier film) 16 titanium nitride film (part of first barrier film) 18 copper film 20 titanium nitride film (second barrier film) ) 22 silicon nitride (film for forming etching mask,
Etching mask) 24 Photoresist (photosensitive agent) 26 Cu-BTA compound (layer for preventing oxidation and diffusion) 28 Interlayer insulating film (protective film) 30 Copper silicide (layer for preventing oxidation and diffusion) 32 Copper silicon (A layer that prevents oxidation and diffusion)

Claims (16)

[Claims] 1. A method of manufacturing a semiconductor device in which an element using copper as a wiring material is formed on a semiconductor substrate, comprising: a step of forming an insulating film on the substrate; and a first barrier on the insulating film. A step of sequentially forming a film, a copper film, and a second barrier film; a step of forming a film for forming an etching mask on the second barrier film; and a step of forming a photosensitive agent on the film for forming the etching mask. Coating, selectively exposing the photosensitive agent to form a predetermined wiring pattern on the photosensitive agent, and etching the film for forming an etching mask using the photosensitive agent on which the wiring pattern is formed as a mask. Forming an etching mask by etching; removing the photosensitive agent; etching the first barrier film, the copper film, and the second barrier film using the etching mask to form a wiring layer Removing the etching mask, forming a layer for preventing oxidation and diffusion on at least side walls of the copper wiring layer, and forming a protective film covering the entire wiring layer. A method for manufacturing a semiconductor device, comprising: 2. A method for manufacturing a semiconductor device in which an element using copper as a wiring material is formed on a semiconductor substrate, comprising: a step of forming an insulating film on the substrate; and a first barrier on the insulating film. A step of sequentially forming a film, a copper film, and a second barrier film; a step of forming a film for forming an etching mask on the second barrier film; and a step of forming a photosensitive agent on the film for forming the etching mask. Coating, selectively exposing the photosensitive agent to form a predetermined wiring pattern on the photosensitive agent, and etching the film for forming an etching mask using the photosensitive agent on which the wiring pattern is formed as a mask. Forming an etching mask by etching; removing the photosensitive agent; etching the first barrier film, the copper film, and the second barrier film using the etching mask to form a wiring layer Removing the etching mask and the second barrier film; forming a layer for preventing oxidation and diffusion on the upper surface and side walls of the copper wiring layer; and protecting the entire wiring layer. A method of manufacturing a semiconductor device, comprising: at least a step of forming a film. 3. The method according to claim 1, wherein the first barrier film and the second barrier film are formed of silicon nitride, silicon oxynitride, titanium nitride, tungsten nitride, titanium tungsten nitride, tungsten, niobium, niobium nitride, aluminum, tantalum, and tantalum nitride. 2. A method according to claim 1, wherein
A method for manufacturing a semiconductor device according to claim 2. 4. The method according to claim 1, wherein the film for forming the etching mask is any one of silicon nitride, silicon oxide, and silicon oxynitride. 5. The method according to claim 1, wherein the film for forming the etching mask and the second barrier film are of different film types. 6. The semiconductor device according to claim 1, wherein the second barrier film is left in the step of etching the film for forming an etching mask to form an etching mask. Manufacturing method. 7. The etching gas used in the step of forming an etching mask by etching the film for forming an etching mask includes a compound represented by CnHmF (2n + 2-m). The method of manufacturing a semiconductor device according to claim 2. 8. The etching condition used in the step of etching the film for forming an etching mask to form an etching mask is such that the etching rate of the second barrier film is higher than the etching rate of the film for forming the etching mask. 8. The method for manufacturing a semiconductor device according to claim 1, wherein said step (c) is delayed. 9. The method according to claim 1, wherein the first mask is formed using the etching mask.
The etching gas used in the step of forming the wiring layer by etching the barrier film, the second barrier film, and the copper film is a gas containing chlorine. A method for manufacturing a semiconductor device. 10. An etching gas used in the step of removing the etching mask is CnHmF (2n + 2
The method for manufacturing a semiconductor device according to claim 1, wherein a compound represented by -m) is included. 11. The semiconductor device according to claim 2, wherein the etching gas used in the step of removing the etching mask and the second barrier film contains sulfur hexafluoride. Production method. 12. An etching condition used in the step of removing the etching mask, wherein an etching rate of the second barrier film is lower than an etching rate of a film of the etching mask. A method for manufacturing a semiconductor device according to claim 10. 13. The etching conditions used in the step of removing the etching mask and the second barrier film are as follows:
12. The method according to claim 2, wherein an etching rate of the film for forming the etching mask is substantially equal to an etching rate of the second barrier film. 14. The method according to claim 1, wherein in the step of forming a layer for preventing oxidation and diffusion on at least the side wall of the copper wiring layer, the surface of the wiring layer is treated in a gas atmosphere. 13. The method for manufacturing a semiconductor device according to item 5. 15. The method according to claim 1, wherein the step of forming a layer for preventing oxidation and diffusion on at least a side wall of the copper wiring layer includes performing a solution treatment on a surface of the wiring layer. A method for manufacturing a semiconductor device. 16. The method according to claim 1, wherein the step of forming a layer for preventing oxidation and diffusion on at least the side wall of the copper wiring layer comprises implanting an impurity into the wiring layer. Semiconductor device.