JP2021111755A - Formation method of metal wiring - Google Patents

Abstract

To provide a reliable formation method of a metal wiring.SOLUTION: A lamination structure is prepared that includes a metal wiring layer containing copper, and an interlayer insulating layer laminated on the metal wiring layer and provided with an opening that exposes a part of the surface of the metal wiring layer. On the surface of the interlayer insulating layer and the exposed surface of the metal wiring layer exposed at the opening, a copper-aluminum layer is formed by a sputtering method such that the thickness of the copper-aluminum layer deposited on the surface of the interlayer insulating layer is thicker than the thickness of the copper-aluminum layer deposited on the exposed surface. Plasma is exposed on the copper-aluminum layer deposited on the surface and the exposed surface of the interlayer insulating layer, and therefore, the thickness of the copper-aluminum layer deposited on the surface is reduced, and the copper-aluminum layer deposited on the exposed surface is removed from the exposed surface, and a natural oxide film of the metal wiring layer formed on the exposed surface is removed from the exposed surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for forming metal wiring.

In electronic components such as LSIs, a conductive layer is embedded in a via hole provided in an interlayer insulating layer, and the metal wiring layers between the layers are electrically connected by the conductive layer. The conductive layer is embedded in the via hole by forming the conductive layer between the via hole and the surface of the interlayer insulating layer, and then removing the conductive layer on the interlayer insulating layer by a chemical mechanical polishing method (for example, patent). Reference 1).

Here, poor contact between the conductive layer in the via hole and the metal wiring reduces the yield of electronic components, so suppressing poor contact has become an important issue. In particular, as the via hole node becomes narrower, the contact resistance between the conductive layer and the metal wiring causes an increase in wiring resistance.

For example, a natural oxide film is usually formed on the surface of the metal wiring before the step of embedding the conductive layer in the via hole. The step of removing the natural oxide film by a dry process before embedding the conductive layer in the via hole is an important step in the manufacturing process of electronic parts.

JP-A-2010-177365

By the way, with the recent increase in speed of electronic components, a Low-k material having a small parasitic capacitance is used as an interlayer insulating layer. Since this Low-k material is generally composed of a low density, when the interlayer insulating layer is exposed to plasma when the natural oxide film is removed by a dry process, the interlayer insulating layer is damaged by the plasma. There is a possibility of receiving it.

In addition, if the metal component contained in the natural oxide film reattaches to the inner wall of the via hole of the interlayer insulating layer after removing the natural oxide film, the reattached metal may diffuse into the interlayer insulating layer due to the thermal history of the manufacturing process. be.

When the above phenomenon occurs, the interlayer insulating layer loses its function as a low-k material, and the reliability of electronic components may be reduced.

In view of the above circumstances, an object of the present invention is to provide a highly reliable method for forming a metal wiring in a metal wiring included in an electronic component.

In order to achieve the above object, the following forming method is applied to the metal wiring forming method according to one embodiment of the present invention.
A laminated structure having a metal wiring layer containing copper and an interlayer insulating layer laminated on the metal wiring layer and provided with an opening in which a part of the surface of the metal wiring layer is exposed is prepared.
The above, which is deposited on the surface of the interlayer insulating layer and the exposed surface of the metal wiring layer exposed at the opening by the sputtering method, on the surface of the interlayer insulating layer rather than the thickness of the copper-aluminum layer deposited on the exposed surface. The copper-aluminum layer is formed so that the thickness of the copper-aluminum layer is increased.
By exposing the surface of the interlayer insulating layer and the copper-aluminum layer deposited on the exposed surface to plasma, the thickness of the copper-aluminum layer deposited on the surface is reduced, and the copper-aluminum layer deposited on the exposed surface is reduced. Is removed from the exposed surface, and the natural oxide film of the metal wiring layer formed on the exposed surface is removed from the exposed surface.

According to such a method of forming a metal wiring, an electronic component having a highly reliable metal wiring is provided without impairing the function of the interlayer insulating layer.

In the method for forming the metal wiring, as the sputtering method, a sputtering method in which isotropic sputtering is prioritized over anisotropic sputtering, or a normal of the sputtering target and a normal of the interlayer insulating layer are not used. A sputtering method may be adopted in which the sputtering method is performed in parallel.

According to such a method of forming the metal wiring, the difference in the thickness of the copper-aluminum layer deposited on each of the surface and the exposed surface of the interlayer insulating layer can be surely taken, and the electron provided with the highly reliable metal wiring can be surely taken. Parts are provided.

In the method for forming the metal wiring, the plasma is a plasma in which an inert gas is discharged, and the thickness of the copper-aluminum layer deposited on the surface is reduced by physical etching using the plasma to reduce the thickness of the copper-aluminum layer. The copper-aluminum layer and the natural oxide film deposited on the exposed surface may be removed.

According to such a method of forming the metal wiring, the natural oxide film is removed without impairing the function of the interlayer insulating layer, and an electronic component having a highly reliable metal wiring is provided.

In the above-mentioned metal wiring forming method, as the above-mentioned physical etching, an etching method in which anisotropic etching is prioritized over isotropic etching may be adopted.

According to such a method of forming the metal wiring, the natural oxide film is removed without impairing the function of the interlayer insulating layer, and an electronic component having a highly reliable metal wiring is provided.

In the method for forming the metal wiring, the interlayer insulating layer may be a Low-k layer.

According to such a method of forming a metal wiring, an electronic component having a highly reliable metal wiring is provided without impairing the function of the Low-k layer as an interlayer insulating layer.

In the method for forming the metal wiring, the copper-aluminum layer may be a CuAl ₂ layer.

According to such a metal wiring forming method, an oxide barrier film is formed on the side surface of the opening of the interlayer insulating layer, and a highly reliable metal wiring is provided without impairing the function of the Low-k layer. Electronic components are provided.

In the method for forming the metal wiring, the opening is a via hole or a trench provided in the interlayer insulating layer, and the opening width of the via hole or the line width of the trench may be 20 nm or less.

According to such a method for forming a metal wiring, an electronic component having a highly reliable metal wiring is provided without impairing the function of the interlayer insulating layer even if the opening width or the line width is as described above. NS.

In the method for forming the metal wiring, after removing the natural oxide film, the copper-aluminum wiring may be formed in the opening by a sputtering method or a plating method.

According to such a method of forming a metal wiring, an electronic component having a highly reliable metal wiring is provided.

In the method for forming the metal wiring, the component of the copper-aluminum layer may be the same as the component of the copper-aluminum wiring.

According to such a method of forming the metal wiring, the step of removing the copper-aluminum layer becomes unnecessary, and the manufacturing process of the metal wiring is simplified.

As described above, according to the present invention, there is provided a highly reliable method for forming a metal wiring in a metal wiring included in an electronic component.

FIGS. (A) and (b) are schematic cross-sectional views showing a part of a laminated structure of an interlayer insulating layer, a metal wiring, and a metal wiring layer in an upper layer of an electronic component. It is a schematic cross-sectional view which shows the manufacturing process of the laminated structure exemplified in FIG. 1 (a). It is a schematic cross-sectional view which shows the manufacturing process of the laminated structure exemplified in FIG. 1 (a). It is a schematic cross-sectional view which shows the manufacturing process of the laminated structure exemplified in FIG. 1 (b). It is a schematic cross-sectional view which shows the manufacturing process of the laminated structure exemplified in FIG. 1 (b). It is a schematic cross-sectional view which shows an example of the operation of this embodiment. It is a schematic cross-sectional view which shows the modification of the manufacturing process of a laminated structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. XYZ axis coordinates may be introduced in each drawing. Further, the same member or a member having the same function may be designated by the same reference numeral, and the description may be omitted as appropriate after the description of the member.

1 (a) and 1 (b) are schematic cross-sectional views showing a part of a laminated structure of an interlayer insulating layer, a metal wiring, and a metal wiring layer in an upper layer of an electronic component.

1 (a) and 1 (b) show an interlayer insulating layer, a metal wiring, and a metal wiring layer in an upper layer of an electronic component (for example, a semiconductor device) including a transistor, a resistor, a capacitor, a memory, and the like. ..

The laminated structure 1 shown in FIG. 1A includes metal wiring layers 10 and 30, interlayer insulating layers 11, 21 and 31, and metal wiring 20.

The metal wiring layer 10 is, for example, a wiring layer provided below the laminated structure 1 and electrically connected to any one of a transistor, a resistor, a capacitor, a memory, and the like (not shown). Alternatively, the potential of the metal wiring layer 10 may be floating. An interlayer insulating layer 11 is provided on the outer periphery of the metal wiring layer 10.

The lower end 20d of the metal wiring 20 is electrically connected to the metal wiring layer 10, and the upper end 20u thereof is connected to the metal wiring layer 30. The interlayer insulating layer 21 is laminated on the metal wiring layer 10 and the interlayer insulating layer 11, and the outer periphery of the metal wiring 20 is surrounded by the interlayer insulating layer 21. For example, the metal wiring 20 is embedded in an opening 21h such as a via hole provided in the interlayer insulating layer 21. The opening 21h may be, for example, a trench in addition to the via hole.

The metal wiring layer 30 is electrically connected to the upper end 20u of the metal wiring 20. The interlayer insulating layer 31 is laminated on the interlayer insulating layer 21, and the interlayer insulating layer 31 is provided on the outer periphery of the metal wiring layer 30.

The materials of the metal wiring layers 10 and 30 and the metal wiring 20 are materials containing Cu. For example, the materials of the metal wiring layers 10 and 30 and the metal wiring 20 are Cu alloys. Here, the Cu alloy is an intermetallic compound such as _{CuAl 2} (CuAl _{2-θ layer).} The material of the interlayer insulating layers 11, 21, and 31 is, for example, a Low-k material having a relative permittivity of 2 or less (CVD-SiOC, CVD-SiO _2, etc.).

When the material of the metal wiring layer 30 is pure Cu, a barrier layer may also be provided between the metal wiring layer 30 and the interlayer insulating layers 21 and 31.

Further, in the laminated structure 2 shown in FIG. 1B, an interlayer insulating layer 31 is further provided on the interlayer insulating layer 21, and an opening 31h having an opening width wider than the opening 21h is formed in the interlayer insulating layer 31. ing. The opening 21h is provided with a wiring portion 25a of the metal wiring 25, and the opening 31h is provided with a wiring portion 25b of the metal wiring 25 having a wider line width than the wiring portion 25a. That is, the metal wiring 25 has a wiring portion 25a and a wiring portion 25b. In other words, the wiring portion 25a is a via wiring, and the wiring portion 25b is an electrode. Such a laminated structure is also included in the present embodiment. The material of the metal wiring 25 is a Cu alloy such as _{CuAl 2} (CuAl _{2-θ layer).}

The manufacturing process of the laminated structure 1 shown in FIG. 1A will be described.

2 (a) to 3 (b) are schematic cross-sectional views showing a manufacturing process of the laminated structure 1 illustrated in FIG. 1 (a).

As shown in FIG. 2A, first, a laminated structure 1a having a metal wiring layer 10 and interlayer insulating layers 11 and 21 is prepared. In the laminated structure 1a, the interlayer insulating layer 11 is provided on the outer periphery of the metal wiring layer 10, and the interlayer insulating layer 21 is laminated on the metal wiring layer 10 and the interlayer insulating layer 11. The interlayer insulating layer 21 is provided with an opening 21h in which a part of the surface 10s of the metal wiring layer 10 is exposed.

The opening 21h may be a via hole penetrating between the upper and lower main surfaces of the interlayer insulating layer 21, or a trench extending in a direction parallel to the main surface of the interlayer insulating layer 21. For example, when the opening width (line width in the case of a trench) of the opening 21h is 5 to 15 nm, the depth of the opening 21h is 20 to 40 nm.

The laminated structure 1a is formed by combining, for example, a film forming technique such as CVD and sputtering, an etching technique using a dry or wet method, and a manufacturing process such as photolithography. Here, when the opening 21h is formed in the interlayer insulating layer 21 and a part of the metal wiring layer 10 is exposed, a natural oxide film (for example, copper oxide) is formed on the exposed surface 101 of the metal wiring layer 10. There is.

Next, as shown in FIG. 2B, a copper-aluminum layer 201 is formed on the surface 21s of the interlayer insulating layer 21 and the exposed surface 101 of the metal wiring layer 10 exposed at the opening 21h. The components of the copper-aluminum layer 201 are the same as those of the metal wiring 20. For example, the copper-aluminum layer 201 is a Cu alloy such as _{a CuAl 2} layer (CuAl _{2-θ layer).} The copper-aluminum layer 201 is formed by a sputtering method using a Cu alloy target such as _{CuAl 2 in a reduced pressure atmosphere.}

Here, as the sputtering method, a sputtering method in which the directivity of the sputtering particles is relaxed is applied. For example, a sputtering method that prioritizes isotropic sputtering over anisotropic sputtering is applied, and the copper-aluminum layer deposited on the surface 21s of the interlayer insulating layer 21 rather than the thickness of the copper-aluminum layer 201 deposited on the exposed surface 101. The copper-aluminum layer 201 is formed so that the thickness of 201 is increased.

For example, the anisotropic sputtering, for example, to set relatively long distance between the substrate and the target, including the laminated structure 1a, a plasma of low pressure region (for ^{example, 10} -6 ^Pa~10 -1 Pa) The sputtering method to be used is applicable. In isotropic sputtering, the distance between the substrate and the target is set relatively short ^{, and plasma in the medium pressure region to the high pressure region (for example, 10 -1} Pa to 10 Pa) is used. The sputtering method to be used is applicable. For plasma discharge, a magnetron discharge method based on a plasma confinement method using a mirror magnetic field and a discharge method that self-maintains the plasma state by applying a high voltage to the material itself combined with the magnetron discharge method are adopted.

By adopting such a sputtering method in which the step covering property is suppressed, the sputtering particles are less likely to reach the exposed surface 101 than the surface 21s, and the layers are more difficult to reach than the thickness of the copper aluminum layer 201 deposited on the exposed surface 101. The thickness of the copper-aluminum layer 201 deposited on the surface 21s of the insulating layer 21 becomes thicker. For example, a copper-aluminum layer 201 of 2 nm to 5 nm is formed on the surface 21s, and a copper-aluminum layer 201 of 0.5 nm to 1.5 nm is formed on the exposed surface 101.

Next, as shown in FIG. 2C, for example, plasma is exposed to the copper-aluminum layer 201 deposited on the surface 21s of the interlayer insulating layer 21 and the exposed surface 101 to perform physical etching.

In physical etching, plasma discharged from an inert gas such as Ar, He, Ne, or Xe is used as the plasma gas. As the physical etching using this plasma, a sputtering method in which the directivity of plasma ions is improved is applied. For example, an etching method in which anisotropic etching is prioritized over isotropic etching is applied. For example, a negative potential bias is superimposed on the substrate including the laminated structure 1a, and plasma treatment is performed in a ^{low pressure region (for example, 10 -3 Pa to 10 -1 Pa).}

As a result, the ions in the plasma can easily reach not only the copper-aluminum layer 201 deposited on the surface 21s of the interlayer insulating layer 21 but also the copper-aluminum layer 201 deposited on the exposed surface 101, so that the ions in the plasma easily reach the surface 21s of the interlayer insulating layer 21 and the surface 21s of the interlayer insulating layer 21. Both copper-aluminum layers 201 deposited on the exposed surface 101 are simultaneously etched. However, since the thickness of the copper-aluminum layer 201 deposited on the surface 21s is thicker than the thickness of the copper-aluminum layer 201 deposited on the exposed surface 101, the copper-aluminum layer 201 deposited on the exposed surface 101 is removed first, and the surface 21s The copper-aluminum layer 201 deposited on the surface 21s remains on the surface 21s.

As a result, the thickness of the copper-aluminum layer 201 deposited on the surface 21s is reduced, and the copper-aluminum layer 201 deposited on the exposed surface 101 is removed from the exposed surface 101. Further, the exposed surface 101 is overetched by physical etching, and the natural oxide film of the metal wiring layer 10 formed on the exposed surface 101 is removed from the exposed surface 101.

Next, as shown in FIG. 3A, after the natural oxide film on the exposed surface 101 is removed, a metal wiring layer 20L made of _{CuAl 2 is formed on the opening 21h and the copper aluminum layer 201 by a sputtering method or} It is formed by the plating method. The metal wiring layer 20L may be reflowed at 200 to 350 ° C., if necessary, after being formed on the opening 21h and the copper-aluminum layer 201.

Next, as shown in FIG. 3B, the surplus of the metal wiring layer 20L on the interlayer insulating layer 21 is removed by chemical mechanical polishing, and the surplus is removed and left in the opening 21h. Is formed. After that, as shown in FIG. 1A, the interlayer insulating layer 31 is formed on the interlayer insulating layer 21, and further, the metal wiring layer 30 electrically connected to the metal wiring 20 is formed in the interlayer insulating layer 31. Is formed.

The manufacturing process of the laminated structure 2 shown in FIG. 1B will be described.

4 (a) to 5 (b) are schematic cross-sectional views showing a manufacturing process of the laminated structure 2 illustrated in FIG. 1 (b).

As shown in FIG. 4A, a laminated structure 2a having a metal wiring layer 10 and interlayer insulating layers 11, 21, and 31 is prepared. In the laminated structure 2a, the interlayer insulating layer 21 is provided with an opening 21h, and the interlayer insulating layer 31 is provided with an opening 31h communicating with the opening 21h. The opening width of the opening 31h is formed wider than the opening width of the opening 21h.

The laminated structure 2a is formed by combining, for example, a film forming method such as CVD or sputtering, an etching method by a dry method or a wet method, and a wafer process such as photolithography. After the opening 21h is formed in the interlayer insulating layer 21, a natural oxide film may be formed on the exposed surface 101 of the metal wiring layer 10.

Next, as shown in FIG. 4B, the surface 31s of the interlayer insulating layer 31, the surface 21s of the interlayer insulating layer 21 of the interlayer insulating layer 21 exposed at the opening 21h, and the metal wiring layer 10 exposed at the opening 21h. A copper-aluminum layer 201 is formed on the exposed surface 101 of the above.

Here, as the sputtering method, a sputtering method in which the directivity of the sputtering particles is relaxed is applied. For example, a sputtering method that prioritizes isotropic sputtering over anisotropic sputtering is applied as in the manufacturing process of the laminated structure 1a. As a result, the thickness of the copper-aluminum layer 201 deposited on the surface 31s of the interlayer insulating layer 31 and the surface 21s of the interlayer insulating layer 21 becomes thicker than the thickness of the copper-aluminum layer 201 deposited on the exposed surface 101. Since the opening width of the opening 31h is wider than the opening width of the opening 21h, the thickness of the copper-aluminum layer 201 deposited on the surface 31s of the interlayer insulating layer 31 is the copper-aluminum layer deposited on the surface 21s of the interlayer insulating layer 21. It is formed thicker than the thickness of 201.

Next, as shown in FIG. 4C, a manufacturing process of, for example, a laminated structure 1a on the surface 31s of the interlayer insulating layer 31, the surface 21s of the interlayer insulating layer 21, and the copper aluminum layer 201 deposited on the exposed surface 101. Physical etching with improved directivity is applied in the same manner as above.

As a result, the thickness of the copper-aluminum layer 201 deposited on the surfaces 31s and 21s is reduced, and the copper-aluminum layer 201 deposited on the exposed surface 101 is removed from the exposed surface 101. Further, the exposed surface 101 is overetched by physical etching, and the natural oxide film of the metal wiring layer 10 formed on the exposed surface 101 is removed from the exposed surface 101.

_{Next, as shown in FIG. 5A, a metal wiring layer 25L made of CuAl 2} as a material is formed on the openings 31h and 21h and the copper-aluminum layer 201 by a sputtering method or a plating method. The metal wiring layer 25L may be subjected to a reflow process at 200 to 350 ° C., if necessary.

Next, as shown in FIG. 5B, the surplus of the metal wiring layer 25L on the interlayer insulating layer 31 was removed by chemical mechanical polishing, and the surplus was removed and left in the openings 31h and 21h. The metal wiring 25 is formed. That is, as shown in FIG. 1B, the wiring portion 25b of the metal wiring 25 is formed in the opening 31h, and the wiring portion 25a of the metal wiring 25 is formed in the opening 21h. As a result, the laminated structure 2 is formed. The copper-aluminum layer 201 on the surface 21s is incorporated as part of the metal wiring 25.

The operation of this embodiment will be described.

FIG. 6 is a schematic cross-sectional view showing an example of the operation of the present embodiment.

In the present embodiment, the interlayer insulating layer 21 is removed when the copper aluminum layer 201 deposited on the exposed surface 101 is removed by physical etching and the natural oxide film of the metal wiring layer 10 formed on the exposed surface 101 is removed. The surface 21s of the surface is covered with the copper-aluminum layer 201. That is, the copper-aluminum layer 201 deposited on the surface 21s functions as a protective layer for the interlayer insulating layer 21 during physical etching.

As a result, the surface 21s of the interlayer insulating layer 21 is less likely to be damaged by plasma and maintains its function as a Low-k material.

Further, due to the high reactivity between the aluminum in the copper aluminum layer 201 and the oxygen in the interlayer insulating layer 21, the interface between the protective layer and the interlayer insulating layer 21 is extremely thin, for example, as a conceivable layer. Aluminum oxide (AlO _x ) layer is formed. This aluminum oxide layer functions as a barrier layer for metal components and suppresses diffusion of Cu and Al in the protective layer into the interlayer insulating layer 21.

Further, a copper-aluminum layer 201 is formed on the exposed surface 101 when the natural oxide film is removed. A part of the copper-aluminum layer 201 reattaches to the side surface 21w of the opening 21h during physical etching.

As a result, due to the high reactivity between the aluminum in the copper aluminum layer 201 and the oxygen in the interlayer insulating layer 21, an ultrathin aluminum oxide layer is also formed at the interface between the metal wiring 20 and the interlayer insulating layer 21. It is thought that. The barrier property of the aluminum oxide layer suppresses the diffusion of Cu and Al in the metal wiring 20 into the interlayer insulating layer 21.

Further, since the components of the copper-aluminum layer 201 and the components of the metal wiring 20 are the same, excellent adhesion between the metal wiring 20 and the interlayer insulating layer 21 due to the presence of copper-aluminum reattached to the side surface 21w. Is obtained.

Further, since the component of the copper-aluminum layer 201 and the component of the metal wiring 20 are the same, the step of removing the copper-aluminum reattached to the side surface 21w becomes unnecessary, and the manufacturing process can be simplified. Since the step of removing the copper aluminum reattached to the side surface 21w becomes unnecessary, damage to the interlayer insulating layer 21 is suppressed.

Further, in the manufacturing process of the laminated structure 2a, although the copper-aluminum layer 201 remains on the surface 21s of the interlayer insulating layer 21, the components of the metal wiring 25 embedded in the openings 31h and 21h are the same as those of the copper-aluminum layer 201. Therefore, the copper-aluminum layer 201 is incorporated in a part of the metal wiring 25. This eliminates the need for the step of removing the copper-aluminum layer 201 remaining on the surface 21s.

Depending on the sputtering conditions, the copper-aluminum layer 201 may be deposited on the side surface of the opening 21h or the side surface of the opening 31h in addition to the exposed surface 101. The copper-aluminum layer 201 deposited on the side surface of the opening 21h or the side surface of the opening 31h may be removed by physical sputtering, or may remain on the side surface of the opening 21h or the side surface of the opening 31h after physical sputtering. Even if the copper-aluminum layer 201 remains on the side surface of the opening 21h or the side surface of the opening 31h, the same effect as when the copper-aluminum layer 201 on the exposed surface 101 is reattached to the side surface of the opening 21h or the side surface of the opening 31h is obtained. ..

FIG. 7 is a schematic cross-sectional view showing a modified example of the manufacturing process of the laminated structure.

In the sputtering film formation of the copper-aluminum layer 201, the normal line 40n of the Cu alloy target 40 used as the sputtering target and the normal line 21n of the interlayer insulating layer 21 may be made non-parallel to perform the sputtering film formation. At the time of sputtering film formation, the substrate including the laminated structure 1a may be appropriately rotated in a direction parallel to the surface 21s.

According to such a method, the directivity of the sputtering particles is further relaxed, and the thickness of the copper-aluminum layer 201 deposited on the surface 21s of the interlayer insulating layer 21 is larger than the thickness of the copper-aluminum layer 201 deposited on the exposed surface 101. Is likely to become thicker. Thereby, the difference between the thickness of the copper-aluminum layer 201 deposited on the exposed surface 101 and the thickness of the copper-aluminum layer 201 deposited on the surface 21s of the interlayer insulating layer 21 can be more reliably provided. The modified example may be applied to the manufacturing process of the laminated structure 2a.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made. Each embodiment is not limited to an independent form, and can be combined as technically as possible.

1, 1a, 2, 2a ... Laminated structure 10, 20L, 25L, 30 ... Metal wiring layer 10s, 21s, 31s ... Surface 11, 21, 31 ... Interlayer insulation layer 20, 25 ... Metal wiring 20u ... Upper end 20d ... Lower end 21h, 31h ... Opening 21w ... Side surface 21n, 40n ... Normal line 25a, 25b ... Wiring part 40 ... Cu alloy target 101 ... Exposed surface 201 ... Copper aluminum layer

Claims (9)

A laminated structure having a metal wiring layer containing copper and an interlayer insulating layer laminated on the metal wiring layer and provided with an opening in which a part of the surface of the metal wiring layer is exposed is prepared.
Regarding the copper-aluminum layer formed on the surface of the interlayer insulating layer and the exposed surface of the metal wiring layer exposed at the opening by the sputtering method, the thickness of the interlayer insulating layer is larger than the thickness of the copper-aluminum layer deposited on the exposed surface. The copper-aluminum layer is formed so that the thickness of the copper-aluminum layer deposited on the surface is increased.
By exposing the surface of the interlayer insulating layer and the copper-aluminum layer deposited on the exposed surface to plasma, the thickness of the copper-aluminum layer deposited on the surface is reduced, and the copper-aluminum layer deposited on the exposed surface is reduced. A method for forming a metal wiring, which removes the natural oxide film of the metal wiring layer formed on the exposed surface from the exposed surface and removes the natural oxide film of the metal wiring layer from the exposed surface. The method for forming a metal wiring according to claim 1.
As the sputtering method, a sputtering method in which isotropic sputtering is prioritized over anisotropic sputtering, or a sputtering method in which the normal of the sputtering target and the normal of the interlayer insulating layer are not parallel to each other is adopted. How to form metal wiring. The method for forming a metal wiring according to claim 1 or 2.
The plasma is a plasma in which an inert gas is discharged, and the thickness of the copper-aluminum layer deposited on the surface is reduced by physical etching using the plasma, and the copper-aluminum layer deposited on the exposed surface and the plasma. A method for forming a metal wiring for removing the natural oxide film. The method for forming a metal wiring according to claim 3.
A method for forming a metal wiring, which employs an etching method in which anisotropic etching is prioritized over isotropic etching as the physical etching. The method for forming a metal wiring according to any one of claims 1 to 4.
A method for forming a metal wiring using a Low-k layer as the interlayer insulating layer. The method for forming a metal wiring according to any one of claims 1 to 5.
A method for forming a metal wiring using _two CuAl layers as the copper-aluminum layer. The method for forming a metal wiring according to any one of claims 1 to 6.
A method for forming a metal wiring, wherein the opening is a via hole or a trench provided in the interlayer insulating layer, and the opening width of the via hole or the line width of the trench is 20 nm or less. The method for forming a metal wiring according to any one of claims 1 to 7.
A method for forming a metal wiring in which a copper-aluminum wiring is formed in the opening by a sputtering method or a plating method after removing the natural oxide film. The method for forming a metal wiring according to claim 8.
A method for forming a metal wiring in which the components of the copper-aluminum layer are the same as the components of the copper-aluminum wiring.

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