JP3546752B2 - Method for manufacturing semiconductor device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device having a plug in a method for manufacturing a semiconductor device.
[0002]
[Prior art]
With the progress of miniaturization of semiconductor devices, it has become common to employ a multilayer wiring structure. In such a multilayer wiring structure, a connection hole such as a contact or a via is opened in an intermediate layer between an upper wiring layer and a lower wiring layer, and a metal such as tungsten is filled into the connection hole to form a plug. A structure in which an upper wiring layer and a lower wiring layer are electrically connected via the connection hole is adopted.
[0003]
A conventional method of manufacturing a semiconductor device having such a plug will be described below by taking a case where a contact hole is provided as an example.
[0004]
FIG. 4 is an explanatory view of a conventional method for manufacturing a semiconductor device having a plug. Hereinafter, each step will be described with reference to FIG.
[0005]
First, as shown in (1), an insulating film 12 such as SiO ₂ is formed on a silicon substrate 10, and as shown in (2), a part of the silicon substrate is formed in the insulating film 12 for forming contact holes. An opening 30 is provided so as to be exposed. The diameter of the opening 30 is usually about 0.1 to 1.0 μm. Next, as shown in (3), a barrier metal layer 14 is formed on the insulating film 12 by a sputtering method. The barrier metal layer 14 generally has a laminated structure of a Ti film of about 300 Å (30 nm) and a TiN film of about 700 Å (70 nm). The barrier layer is also called an adhesion layer, and has an effect of increasing the degree of adhesion between layers above and below this layer. Next, as shown in (4), the plug formation layer 16 is formed on the barrier metal layer 14 by a sputtering method so that the inside of the opening 30 is filled and the surface is made substantially flat. Generally, tungsten (W) is used for this plug formation layer.
[0006]
Further, as shown in (5), the plug 32 is formed by etching back the plug forming layer 16 with a fluorine-based gas.
[0007]
Subsequently, as shown in (6), the barrier metal layer 14 on the insulating film 12 is dry-etched with a chlorine-based gas. In addition, since the barrier metal layer 14 around the plug 32 is further etched by this etching than the position of the surface of the insulating film 12, an annular concave portion 40 is formed around the plug 32.
[0008]
Next, as shown in (7), the metal wiring layer 18 is formed on the insulating film 12 and the plug 32 by a sputtering method. The metal wiring layer 18 is usually made of Al-Cu, Ai-Si-Cu, Al or the like. Next, although not shown, an antireflection film such as a TiN film is formed on the metal wiring layer 18.
[0009]
Next, as shown in (8), a photoresist is applied on the metal wiring layer 18 to form a photoresist film 20, and the photoresist film 20 is exposed and developed. Using this as a mask, the metal wiring layer 16 is dry-etched with a chlorine-based gas.
[0010]
At this time, as shown in (9), on the side wall surfaces of the metal wiring layer 18, the antireflection film, and the photoresist film 20, a polymer, carbon, or the like, which is considered to have been generated from the photoresist film during this etching, is attached. It attaches as a kimono 22. Also, Al and the like are reattached as the deposit 22. If the attached matter 22 is left as it is, it will be adversely affected as a contaminant in the subsequent process. Therefore, the attached matter 22 is peeled off by a chemical such as an amine-based alkaline solution having a capability of dissolving organic matter. This chemical dissolves Al in the metal wiring layer 18 and also dissolves the photoresist film 20.
[0011]
[Problems to be solved by the invention]
However, the following problems have occurred in the above-described conventional technology.
[0012]
As the miniaturization of the semiconductor device progresses, it becomes difficult to form the metal wiring layer 18 so as to completely cover the connection holes such as the contact holes, so that the metal wiring layer 18 does not become as shown in FIG. As shown in (1), the metal wiring is finally formed in a state of being displaced, and the plug 32 may be partially exposed. At this time, since the concave portion 40 is formed around the plug 32 as described above, the concave portion 40 is also partially exposed.
[0013]
Therefore, in the case where the metal wiring layer is formed in a shifted state as described above, when the adhered substance 22 is peeled off with a chemical after the etching of the metal wiring layer 18, as shown as a chemical 50 in FIG. The chemical will enter the recess 40. Further, the chemical liquid enters a fine tunnel-like gap between the metal wiring layer 18 and the concave portion 40 as shown by an arrow A. As described above, this chemical dissolves Al in the metal wiring layer 18, causing corrosion of Al, adversely affecting the connection between the plug 32 and the metal wiring layer 18, and thus lowering the yield of semiconductor products. Is a factor that leads to
[0014]
However, it is very difficult to remove the chemical solution that has entered the minute gap. In addition, in order to avoid such adverse effects, if the above-mentioned chemical solution is changed to a chemical solution with weak dissolving ability, the dissolving ability of deposits on the metal wiring layer is also reduced at the same time. It is also difficult to solve the problem by changing the chemical solution.
[0015]
Therefore, the present invention provides a method of manufacturing a semiconductor device having a plug, in which a chemical solution for removing an adhered substance such as a polymer adhering to a side wall surface of a metal wiring layer enters a recess around the plug and dissolves the metal wiring layer. It is an object of the present invention to provide a method of manufacturing a semiconductor device which can prevent the occurrence of a problem.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device,
(1) First,
Selectively forming an opening in the insulating film to expose a portion of a layer below the insulating film;
Forming a barrier metal layer on the insulating film and the exposed lower layer;
Forming a plug forming layer on the barrier metal layer;
Forming a plug by etching back the plug forming layer;
Forming a metal wiring layer on the plug and barrier metal layer,
Forming an antireflection film on the metal wiring layer;
Forming a metal wiring layer protective film on the antireflection film,
Forming a photoresist film on the metal wiring layer protective film, exposing, developing;
Selectively removing the metal wiring layer protective film and the antireflection film and the metal wiring layer using the developed photoresist film as a mask;
Peeling off the deposits on the metal wiring layer protective film and the antireflection film and the metal wiring layer;
Selectively removing the barrier metal layer using the metal wiring layer protective film that has not been removed as a mask,
Which is characterized by having
[0017]
With such a method for manufacturing a semiconductor device, the barrier metal layer has not been etched yet at the time when the deposit on the metal wiring layer is peeled off by the chemical solution, so that the barrier metal layer around the plug is derived from the etching of the barrier metal layer. There are no recesses. Therefore, even if the metal wiring layer is formed in a displaced state and the concave portion is exposed, it is possible to reliably prevent the chemical solution from entering the concave portion, and this chemical solution adversely affects the connection between the plug and the metal wiring layer. Therefore, the yield of the semiconductor device can be improved. Further, since there is no need to select a chemical solution in consideration of adversely affecting the connection between the plug and the metal wiring layer as in the case of using the conventional technology, the types of available chemical solutions increase, As a result, it is possible to make a selection giving priority to the cost of the chemical solution, the processing time by the chemical solution, and the like.
[0018]
(2) In (1),
The step of selectively removing the barrier metal layer comprises selectively etching the barrier metal layer with a chlorine-based gas or a fluorine-based gas, and the barrier metal layer formed by the chlorine-based gas or the fluorine-based gas. The etching selectivity between the metal and the metal wiring layer protective film is about 2 or more.
[0019]
With such a method for manufacturing a semiconductor device, the etching selectivity between the barrier metal layer and the metal wiring layer protective film is high, so that even when the metal wiring layer protective film itself is formed thin so as to be easily etched. In addition, the metal wiring layer can be reliably protected when the barrier metal is etched.
[0020]
(3) In (2),
The metal wiring layer protective film is a silicon dioxide film formed by a plasma CVD method using tetraethyl orthosilicate as a raw material.
[0021]
According to such a method for manufacturing a semiconductor device, it is possible to easily form a metal wiring layer protective film having a high etching selectivity of the metal wiring layer protective film to the barrier metal layer.
[0022]
(4)
Selectively forming an opening in the insulating film to expose a portion of a layer below the insulating film;
Forming a barrier metal layer on the insulating film and the exposed lower layer;
Forming a plug forming layer on the barrier metal layer;
Forming a plug by etching back the plug forming layer;
Forming a metal wiring layer on the plug and barrier metal layer,
Forming an antireflection film on the metal wiring layer;
Forming a photoresist film on the antireflection film, exposing, developing;
Selectively removing the antireflection film and the metal wiring layer using the developed photoresist film as a mask,
Removing the deposits of the unremoved photoresist film and the antireflection film and the metal wiring layer,
Selectively removing the barrier metal layer using the photoresist film that has not been removed as a mask,
Which is characterized by having
[0023]
With such a method for manufacturing a semiconductor device, the barrier metal layer has not been etched yet at the time when the deposit on the metal wiring layer is peeled off by the chemical solution, so that the barrier metal layer around the plug is derived from the etching of the barrier metal layer. There are no recesses. Therefore, even if the metal wiring layer is formed in a displaced state and the concave portion is exposed, it is possible to reliably prevent the chemical solution from entering the concave portion, and this chemical solution adversely affects the connection between the plug and the metal wiring layer. Therefore, the yield of the semiconductor device can be improved. Further, since there is no need to select a chemical solution in consideration of adversely affecting the connection between the plug and the metal wiring layer as in the case of using the conventional technology, the types of available chemical solutions increase, As a result, it is possible to make a selection giving priority to the cost of the chemical solution, the processing time by the chemical solution, and the like. Further, it is feasible to solve the problem without relatively increasing the number of steps.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It is to be noted that the same reference numerals are used for the same points as those in the related art, and the same reference numerals are used for the matters which are not described in the first embodiment of the present invention.
[0025]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a second embodiment of the present invention. FIG. 3 is a cross-sectional view showing a state in which the metal wiring is shifted in the embodiment of the present invention.
[0026]
First, each step of the first embodiment of the present invention will be described.
[0027]
In FIG. 1A, after a plug formation layer 16 made of tungsten (W) is deposited on the entire surface of a silicon substrate using tungsten hexafluoride (WF ₆ ), a dry process using sulfur hexafluoride (SF ₆ ) is performed. The plug 32 is formed by etching back the plug forming layer 16 except for the portion filled in the opening 30 by etching.
[0028]
At this time, the etching back of the plug formation layer 16 is stopped when the TiN film forming the barrier metal layer 14 is exposed. Further, in the conventional technique, the barrier metal layer 14 is continuously etched. However, in this embodiment, the barrier metal layer 14 is not etched away at this time.
[0029]
The steps before this are the same as those described in the prior art based on (1) to (4) of FIG.
[0030]
Next, as shown in FIG. 1B, after the plug 32 is formed, the metal wiring layer 18 is formed on the barrier metal layer 14 made of a Ti film and a TiN film and the plug 32 by a sputtering method. The material of the metal wiring layer 18 may be Al-Cu or another material such as Al-Si-Cu as long as it is used for metal wiring of a semiconductor device. Next, although not shown, an antireflection film such as a TiN film is formed on the metal wiring layer 18.
[0031]
Next, as shown in FIG. 1C, a metal wiring layer protective film 24 is formed. The metal wiring layer protection film 24 is provided to protect the metal wiring layer 18 when etching the barrier metal layer 14 described later. The metal wiring layer protection film 24 is preferably a silicon dioxide film formed by a plasma CVD method using tetraethylorthosilicate (TEOS) as a raw material for the reason described later.
[0032]
Next, as shown in FIG. 1D, a photoresist is applied on the metal wiring protection film 24 to form a photoresist film 20.
[0033]
Next, as shown in FIG. 1 (5), the photoresist film 20 is exposed and developed, and further, using this photoresist film 20 as a mask, a metal wiring layer protective film 24, an antireflection film, and a metal wiring layer are formed. 18 are selectively removed by dry etching sequentially. When the metal wiring layer protective film 24 is the above-mentioned silicon dioxide film, for example, a fluorine-based gas containing CHF ₃ and CF ₄ as main gases is used as the gas for dry etching. . When the antireflection film is formed of a TiN film, a chlorine-based gas mainly containing Cl ₂ or the like, or a fluorine-based gas mainly containing SF ₆ or CF ₄ is used. When the metal wiring layer 18 is formed of Al-Cu, a chlorine-based gas mainly containing Cl ₂ or BCl ₃ is used. Naturally, the gas for dry etching is not limited to these, and the most appropriate gas is appropriately selected according to the material forming each layer.
[0034]
At this time, as described above, on the side wall surfaces of the metal wiring layer 18, the antireflection film, and the photoresist film 20, a polymer, carbon, or the like, which is considered to have been generated from the photoresist film during this etching, adheres as an adhered substance 22. I do. Also, Al and the like are reattached as the deposit 22.
[0035]
Next, as shown in FIG. 1 (6), the deposits 22 attached from the photoresist 20 to the metal wiring layer 18 by the above-described dry etching are removed by a chemical solution. As this chemical solution, dimethylformamide (DMF), an organic carboxylic acid, or the like is used in addition to the above-mentioned amine-based alkaline solution. At this time, the photoresist film 20 is also dissolved and removed.
[0036]
Next, as shown in FIG. 1 (7), the barrier metal layer is etched with a chlorine-based gas or a fluorine-based gas using the metal wiring layer protective film 24 as a mask. For example, Cl ₂ is used as a chlorine-based etching gas. For example, SF ₆ or CF ₄ is used as a fluorine-based etching gas. The metal wiring layer protective film 24 must be able to sufficiently protect the metal wiring layer 18 as a mask during this etching. Therefore, it is preferable that the etching selectivity with respect to the barrier metal layer 14 is large. Therefore, the selectivity of the metal wiring layer protective film 24 to the barrier metal layer 14 is desirably at least 2 or more, preferably 5 or more. In consideration of these, it is most preferable to use a silicon dioxide film formed of tetraethylorthosilicate by plasma CVD as the metal wiring protective film 24 and Cl ₂ as the etching gas, because a high selectivity can be obtained. It is.
[0037]
Further, the metal wiring protective film 24 must be capable of sufficiently protecting the metal wiring layer 18 as described above. It is desirable to be formed as a thin object.
[0038]
According to this embodiment, as described above, the barrier metal layer 14 has not been etched yet at the time when the attached matter 22 such as the metal wiring layer 18 is removed by the chemical solution. Therefore, as shown in FIG. 3, even if the metal wiring layer 18 that is finally etched and formed into a predetermined pattern is displaced and the concave portion 40 that is formed after the etching of the barrier metal layer 14 is exposed, The chemical does not enter this recess. Therefore, when selecting this chemical, it is not necessary to consider that the chemical enters the concave portion, and it is possible to select the chemical based on the dissolving ability of the deposit such as a polymer and the procurement cost.
[0039]
Further, a second embodiment of the present invention will be described. It should be noted that the same reference numerals are used for the same points as those in the first embodiment of the present invention, and the same reference numerals are used for items which are not described in the second embodiment of the present invention. It is the same as that of the embodiment.
[0040]
As shown in FIGS. 2A and 2B, also in this embodiment, a metal wiring layer 18 is formed, and then, although not shown, an anti-reflection such as a TiN film is formed on the metal wiring layer 18. The steps up to the step of forming a film are the same as those of the first embodiment.
[0041]
Next, in this embodiment, as shown in FIG. 2C, the photoresist film 20 is formed directly on the metal wiring layer, and the metal wiring protective film is not provided. As will be described later, this photoresist film 20 is used as a mask when etching the barrier metal layer 14, so that the adhered substance 22 attached to the metal wiring layer 18 is not completely removed when the chemical substance is removed. It preferably has a thickness.
[0042]
Next, as shown in FIG. 2D, the metal wiring layer 18 is dry-etched with a chlorine-based gas using the photoresist film 20 as a mask. Next, as shown in (5) of FIG. 2, the adhered substance 22 adhered to the metal wiring layer 18 is peeled off with a chemical. Next, as shown in FIG. 2 (6), the barrier metal layer 14 is etched with a chlorine-based gas or a fluorine-based gas using the photoresist film 20 as a mask. Therefore, also in the second embodiment, the barrier metal layer 14 has not been etched yet at the time when the deposit 22 such as the metal wiring layer 18 is peeled off by the chemical solution, and is formed after the barrier metal layer 14 is etched. Even when the recess 40 is exposed, the chemical does not enter the recess.
[0043]
Further, in the second embodiment of the present invention, since it is not necessary to provide a metal wiring protective film, it is possible to solve the problem without increasing the number of steps as compared with the first embodiment of the present invention.
[0044]
In these embodiments, the plug formation layer is completely removed by etching except for the inside of the opening of the interlayer insulating film. However, the etching of this layer is stopped halfway and the formation of the metal wiring pattern is stopped. It may be removed later by etching together with the barrier metal layer. Although tungsten (W) has been described as a material of the plug formation layer, other materials such as polycrystalline silicon may be used. Furthermore, although the contact hole is taken as an example of the opening, the present invention can be applied to the case of a via hole in the same manner as in these embodiments. In addition, although the sputtering method and the CVD method are used as the means for forming each of the above layers, the layers may be formed by other means.
[0045]
As described above, in the embodiment of the present invention, the chemical solution for peeling off the deposit on the side wall surface of the metal wiring layer enters the concave portion around the plug without making a significant modification to the conventional manufacturing process, and the metal wiring is formed. Dissolution of the layer can be prevented.
[0046]
【The invention's effect】
As described above, according to the present invention, a chemical solution that peels off deposits such as a polymer that adheres to the side wall surface of a metal wiring layer during etching of the metal wiring layer enters the recess around the plug and dissolves the metal wiring layer. Can be reliably prevented, and the yield of semiconductor devices can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a sectional view showing a second embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a state where a metal wiring is shifted in the embodiment of the present invention.
FIG. 4 is a diagram illustrating a conventional method for manufacturing a semiconductor device having a plug.
FIG. 5 is a cross-sectional view showing a state where a metal wiring is shifted in a conventional method for manufacturing a semiconductor device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Silicon substrate 12 Insulating film 14 Barrier metal layer 16 Plug formation layer 18 Metal wiring layer 20 Photoresist film 22 Attachment 24 Metal wiring layer protective film 30 Opening 32 Plug 40 Depression 50 Chemical solution A approach direction

Claims (4)

Selectively forming an opening in the insulating film to expose a portion of a layer below the insulating film;
Forming a barrier metal layer on the insulating film and the exposed lower layer;
Forming a plug forming layer on the barrier metal layer;
Forming a plug by etching back the plug forming layer;
Forming a metal wiring layer on the plug and barrier metal layer,
Forming an antireflection film on the metal wiring layer;
Forming a metal wiring layer protective film on the antireflection film,
Forming a photoresist film on the metal wiring layer protective film, exposing, developing;
Selectively removing the metal wiring layer protective film and the antireflection film and the metal wiring layer using the developed photoresist film as a mask;
Peeling off the deposits on the metal wiring layer protective film and the antireflection film and the metal wiring layer;
Selectively removing the barrier metal layer using the metal wiring layer protective film that has not been removed as a mask,
A method for manufacturing a semiconductor device, comprising: The step of selectively removing the barrier metal layer is to selectively etch the barrier metal layer with a chlorine-based gas or a fluorine-based gas, and the barrier metal layer with the chlorine-based gas or the fluorine-based gas. 2. The method according to claim 1, wherein an etching selectivity between the metal and the metal wiring layer protective film is about 2 or more. 3. The method according to claim 2, wherein the metal wiring layer protective film is a silicon dioxide film formed by a plasma CVD method using tetraethyl orthosilicate as a raw material. Selectively forming an opening in the insulating film to expose a portion of a layer below the insulating film;
Forming a barrier metal layer on the insulating film and the exposed lower layer;
Forming a plug forming layer on the barrier metal layer;
Forming a plug by etching back the plug forming layer;
Forming a metal wiring layer on the plug and barrier metal layer,
Forming an antireflection film on the metal wiring layer;
Forming a photoresist film on the antireflection film, exposing, developing;
Selectively removing the antireflection film and the metal wiring layer using the developed photoresist film as a mask,
Removing the deposits of the unremoved photoresist film and the antireflection film and the metal wiring layer,
Selectively removing the barrier metal layer using the photoresist film that has not been removed as a mask,
A method for manufacturing a semiconductor device, comprising:

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