JP2004104032A - Laminated structure for metal wiring and method of forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated structure for metal wiring including a copper layer which is formed on a barrier layer and has relaxed internal stress, and a method of forming the same. <P>SOLUTION: The laminated structure for metal wiring includes a substrate, the barrier layer formed directly or indirectly on the substrate for preventing copper from being diffused over the substrate, and the copper layer mainly composed of copper as a base layer of a copper layer for wiring, and the barrier layer contains at least either TaSiN or WSiN. The method of forming the laminated structure for metal wiring includes a barrier layer formation step for forming the barrier layer containing at least either TaSiN or WSiN for preventing copper from being diffused over the substrate directly or indirectly on the substrate, and a copper layer formation step for forming the copper layer mainly composed of copper as the base layer of the copper layer for wiring. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laminated structure for metal wiring and a method for forming the same, and more particularly, to a wiring for a large-scale integrated circuit device (hereinafter referred to as “LSI”), a liquid crystal display device (hereinafter referred to as “LCD”), and the like. The present invention relates to a laminated structure including a copper layer used as an underlayer of a copper layer, and a method for forming the same.
[0002]
[Prior art]
At present, as a laminated structure for metal wiring widely used in LSIs, LCDs, etc., a base layer for a wiring copper layer formed by an electrolytic plating technique and diffusion of copper into a substrate of an element or a circuit are considered. There is a laminated structure including a barrier layer containing Ta, TaN, or the like for prevention.
[0003]
A typical copper wiring structure including such a laminated structure (for example, see Patent Document 1) will be described with reference to FIG.
[0004]
[Patent Document 1]
JP-A-2002-105687 (pages 3 and 4, FIG. 8)
[0005]
Referring to FIG. 5, SiO 2 is formed on a silicon substrate 28. ₂ The layer 30, the barrier layer 32, the copper layer 34, and the wiring copper layer 36 are formed.
[0006]
SiO ₂ Layer 30 is used as an insulating layer. The barrier layer 32 contains TaN and is used to prevent copper from diffusing into the silicon substrate 28. The copper layer 34 forms a base layer (hereinafter, referred to as a “copper seed layer”) of the wiring copper layer 36. The wiring copper layer 36 is electrolytically plated on the copper layer 34. SiO ₂ The contact hole 38 formed by removing a part of the layer 30 is for electrical connection between the silicon substrate 28 and the wiring copper layer 36.
[0007]
[Problems to be solved by the invention]
Incidentally, the copper layer 34 formed on the barrier layer 32 has an internal stress. This internal stress increases as the thickness of the copper layer 34 increases, and induces mechanical damage such as cracking, lowering of adhesive strength, and peeling of the copper layer 34.
[0008]
The copper layer for wiring 36 formed on the copper layer 34 having such an internal stress causes mechanical damage such as crack generation, decrease in adhesion, and peeling due to the crack generation of the copper layer 34.
[0009]
In addition, the internal stress and mechanical damage of the copper layer 34 and the wiring copper layer 36 increase the electrical characteristics of the wiring copper layer 36, particularly the specific resistance.
[0010]
An object of the present invention is to provide a laminated structure for metal wiring including a copper layer formed on a barrier layer and having a reduced internal stress, and a method for forming the same.
[0011]
[Means for Solving the Problems, Functions and Effects]
The laminated structure for metal wiring according to the present invention includes a substrate, a barrier layer formed directly or indirectly on the substrate, for preventing diffusion of copper into the substrate, and And a copper layer as a base layer of the wiring copper layer, the copper layer having copper as a main component, and the barrier layer includes at least one of TaSiN and WSiN.
[0012]
According to the present invention, the composition of the barrier layer includes at least one of TaSiN and WSiN, so that the internal stress of the copper layer formed on the barrier layer can be made relatively small.
[0013]
Thereby, it is possible to prevent mechanical damage such as generation of cracks, reduction in adhesive strength, and occurrence of peeling of the underlying copper layer formed on the barrier layer. It is also possible to prevent mechanical damage such as crack generation, decrease in adhesive strength, and peeling of the wiring copper layer formed on the base copper layer. Further, it is possible to prevent an increase in the electrical characteristics of the wiring copper layer, in particular, an increase in specific resistance.
[0014]
Preferably, the TaSiN contains Si at a composition ratio in the range of 0.01 to 0.1. Alternatively, the WSiN includes a composition ratio of Si in a range of 0.03 to 0.25, or includes a composition ratio of N in a range of 0.15 to 0.25. Thereby, the effect of relaxing the internal stress can be further increased.
[0015]
According to the method of forming a laminated structure for metal wiring according to the present invention, a barrier layer containing at least one of TaSiN and WSiN for preventing diffusion of copper to the substrate is formed directly or indirectly on the substrate. Forming a copper layer as a base layer of the copper layer for wiring, which is a copper layer containing copper as a main component, on the barrier layer.
[0016]
According to the method of the present invention, the laminated structure can be formed.
[0017]
The method for forming a laminated structure for metal wiring further includes a heat treatment step of heating the copper layer so that aggregation occurs in the copper layer after the formation of the copper layer, for example, heating the copper layer at 250 ° C. or more. Can be included. Thereby, the internal stress can be further reduced.
[0018]
The method for forming a laminated structure for metal wiring further includes a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, and after forming the other copper layer. And a second heat treatment step of heating the other copper layer so that the other copper layer is aggregated. Further, the second copper layer forming step and the second heat treatment step may be repeated.
[0019]
The second copper layer forming step includes forming a copper layer having a thickness dimension of 20 nm or less by a physical deposition method, and the second heat treatment step heats the copper layer at 250 ° C. or more. Can be included.
[0020]
The method of forming a laminated structure for metal wiring further includes repeating a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, The copper layer forming step may include forming a part of the copper layer by a chemical deposition method or a physical deposition method, heating at 250 ° C. or more, and then forming the rest of the copper layer.
[0021]
The barrier layer forming step is performed by a reactive sputtering method using an alloy material containing Ta and Si, wherein the alloy material contains Si in a composition ratio in a range of 0.02 to 0.15. , A barrier layer made of TaSiN, wherein the barrier layer contains Si having a composition ratio of TaSiN in the range of 0.02 to 0.1.
[0022]
Alternatively, the barrier layer forming step includes the step of reactive sputtering using an alloy material containing W and Si, wherein the alloy material contains Si in a composition ratio in the range of 0.05 to 0.4. The method can include forming a barrier layer made of WSiN, the barrier layer containing Si having a composition ratio of WSiN in the range of 0.03 to 0.25.
[0023]
The copper layer forming step may include forming the copper layer by electroless plating or a chemical deposition method.
[0024]
The method for forming a laminated structure for metal wiring may further include a step of forming a wiring copper layer on the copper layer.
[0025]
Another laminated structure for metal wiring according to the present invention includes a substrate, a barrier layer formed directly or indirectly on the substrate to prevent diffusion of copper into the substrate, and the barrier layer. And a copper layer containing copper as a main component and having an agglomerated region, as a base layer of the wiring copper layer formed on the layer.
[0026]
According to the present invention, the agglomerated region in the copper layer acts to relieve the internal stress of the copper layer.
[0027]
From this, it is possible to prevent the copper layer having the aggregated region from being mechanically damaged such as generation of cracks, decrease in adhesion, and generation of peeling. It is also possible to prevent mechanical damage such as crack generation, decrease in adhesive strength, and peeling of the wiring copper layer formed on the base copper layer. Further, it is possible to prevent an increase in the electrical characteristics of the wiring copper layer, in particular, an increase in specific resistance.
[0028]
The aggregation region may be formed along a boundary between the copper layer and the barrier layer, or may occupy substantially the entire copper layer.
[0029]
Another method for forming a laminated structure for metal wiring according to the present invention includes, directly or indirectly on a substrate, a barrier layer forming step of forming a barrier layer for preventing diffusion of copper to the substrate. Forming a copper layer as a base layer of a wiring copper layer on the barrier layer, the copper layer being a copper-based copper layer; and forming the copper layer so that aggregation occurs in the copper layer. And a heat treatment step of heating.
[0030]
ADVANTAGE OF THE INVENTION According to this invention, the laminated structure for metal wiring which has a copper layer with a comparatively small internal stress can be formed by producing an aggregation area | region in a copper layer.
[0031]
The heat treatment step includes heating the copper layer so that agglomeration occurs along a boundary between the copper layer and the barrier layer, or agglomeration occurs in substantially all of the copper layer, for example, the copper layer Is heated at 250 ° C. or higher. Thereby, the internal stress can be further reduced.
[0032]
Another forming method of the laminated structure for the metal wiring further includes a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer; After the formation of the second copper layer, a second heat treatment step of heating the other copper layer so that the another copper layer is aggregated. Further, the second copper layer forming step and the second heat treatment step may be repeated.
[0033]
The second copper layer forming step includes forming a copper layer having a thickness dimension of 20 nm or less by a physical deposition method, and the second heat treatment step heats the copper layer at 250 ° C. or more. Can be included.
[0034]
Another method of forming a stacked structure for the metal wiring further includes repeating a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, The second copper layer forming step may include forming a part of the copper layer by a chemical deposition method or a physical deposition method, heating at 250 ° C. or more, and then forming the rest of the copper layer. it can.
[0035]
The copper layer forming step may include forming the copper layer by electroless plating or a chemical deposition method.
[0036]
The method for forming a laminated structure for metal wiring may further include a step of forming a wiring copper layer on the copper layer.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, the laminated structure for metal wiring includes a substrate 10, a barrier layer 14, a copper layer 16 containing copper as a main component, and an insulating layer 12 disposed as necessary.
[0038]
As the substrate 10, a semiconductor substrate including silicon or another semiconductor, a composite substrate including a non-semiconductor substrate such as glass and a semiconductor layer including silicon or another semiconductor directly or indirectly formed thereon is used. be able to. In the illustrated example, the substrate 10 is made of a silicon substrate.
[0039]
As the insulating layer 12, an oxide can be used. In the illustrated example, the insulating layer 12 is made of silicon dioxide (hereinafter referred to as “SiO 2”). ₂ " )) And are formed on the substrate 10. The insulating layer 12 is used as a gate insulating layer in a transistor, for example.
[0040]
The barrier layer 14 includes at least one of an alloy containing Ta, Si, and N (hereinafter, “TaSiN”) and an alloy containing W, Si, and N (hereinafter, “WSiN”). In the illustrated example, the barrier layer 14 is made of TaSiN, and has a thickness of 30 nm.
[0041]
The barrier layer 14 is used to prevent copper from diffusing into the substrate 10 and forms a direct lower layer of the copper layer 16. The barrier layer 14 is formed indirectly on the substrate 10, in the illustrated example, on the insulating layer 12. The barrier layer 14 may be formed directly on the substrate 10 without the interposition of the insulating layer 12, instead of the illustrated example.
[0042]
The copper layer 16 is formed on the barrier layer 14 and forms a base layer (hereinafter, referred to as a “copper seed layer”) of a copper layer for wiring (not shown). In the illustrated example, the thickness dimension of the copper layer 16 is 20 nm. The wiring copper wire is formed on the copper layer 16 and is used for connection with an external electrode (not shown).
[0043]
Next, the internal stress of the copper layer 16 in the laminated structure for the metal wiring will be described.
[0044]
The internal stress of the copper layer 16 on the barrier layer 14 having different composition ratios (weight ratios) of Si in TaSiN was examined by using an X-ray diffraction method applying X-ray spectroscopy. As shown in FIG. 2, the angle of the X-ray diffraction spectrum with respect to the (111) crystal plane of copper of the copper layer 16 with respect to the composition ratio of Si in TaSiN of the barrier layer 14 was measured, and the angle between the measured angle and the reference angle was measured. An angle shift amount Δ2θ as a difference was obtained.
[0045]
Since the angle shift amount Δ2θ in the copper layer 16 is proportional to the internal stress of the copper layer 16, the change in the internal stress can be obtained by measuring the change in the angle shift amount Δ2θ.
[0046]
In the graph shown in FIG. 2, the horizontal axis represents the composition ratio of Si in TaSiN of the barrier layer 14, and the vertical axis represents the angle shift Δ2θ of the X-ray diffraction spectrum with respect to the (111) crystal plane of copper of the copper layer 16. Is shown.
[0047]
The angle shift amount Δ2θ is calculated by the following equation (1) using a reference angle 43.295 ° defined by the ASTM (American Society for Testing Materials) standard. I asked. Here, A ° is an actually measured angle.
[0048]
(Equation 1)
Δ2θ = 43.295 ° −A ° (1)
[0049]
In the graph shown in FIG. 2, paying attention to the broken line obtained by connecting the white circles (丸), it is understood that Δ2θ decreases with an increase in the Si composition ratio of TaSiN.
[0050]
Further details will be described. For comparison, the value of Δ2θ was measured for the copper layer 16 when the composition ratio of Si in TaSiN was 0, that is, when the barrier layer was made of TaN (therefore, when the barrier layer was a conventional barrier layer). did. The obtained value of Δ2θ was 0.25. This shows a value corresponding to the internal stress of the copper layer on the conventional barrier layer made of TaN. That is, it indicates that the internal stress is large.
[0051]
The value of Δ2θ for the copper layer 16 when the composition ratio of Si in TaSiN of the barrier layer 14 is approximately 0.01 is approximately 0.15, and the value of Δ2θ when the composition ratio of Si is 0 is 0. .25. Therefore, it is understood that the internal stress of the copper layer 16 has been reduced.
[0052]
Further, Δ2θ was measured when the composition ratio of Si was approximately 0.045, approximately 0.07, and approximately 0.08. The obtained values of Δ2θ were approximately 0.13, approximately 0.11, and approximately 0.11, respectively. These values of Δ2θ are further reduced from the value of Δ2θ of 0.25 when the Si composition ratio is approximately 0.01. Therefore, it is understood that the internal stress of the copper layer 16 is further reduced.
[0053]
Such reduction or relaxation of the internal stress was confirmed until the composition ratio of Si in TaSiN of the barrier layer 14 was set to approximately 0.1. Therefore, when the composition ratio of Si in TaSiN of the barrier layer 14 is approximately 0.01 to approximately 0.1, the internal stress of the copper layer 16 is relaxed.
[0054]
In the above example, the barrier layer 14 has been described as being made of TaSiN. Next, a case where the barrier layer 14 is made of WSiN will be described. The thickness dimension of the barrier layer 14 was 30 nm, similarly to the barrier layer 14 made of TaSiN, and the same substrate 10, insulating layer 12, and copper layer 16 as described above were used.
[0055]
Also in this case, the angle of the X-ray diffraction spectrum with respect to the (111) crystal plane of copper of the copper layer 16 with respect to the composition ratio of Si in WSiN of the barrier layer 14 is measured, and the difference between the measured angle and the reference angle is obtained. By calculating a certain angle shift amount Δ2θ, a change in the internal stress of the copper layer 16 was examined.
[0056]
As a result, it was confirmed that when the composition ratio of Si in WSiN of the barrier layer 14 was approximately 0.03 to approximately 0.25, the internal stress of the copper layer 16 was reduced to a preferable value.
[0057]
For the barrier layer 14 made of WSiN, the angle of the X-ray diffraction spectrum with respect to the (111) crystal plane of copper of the copper layer 16 with respect to the composition ratio of N in the WSiN of the barrier layer 14 was measured. The change in internal stress was investigated.
[0058]
As a result, it was confirmed that when the composition ratio of N in WSiN of the barrier layer 14 was approximately 0.15 to approximately 0.25, the internal stress of the copper layer 16 was reduced to a preferable value.
[0059]
Thus, the internal stress of the copper layer 16 formed on the barrier layer 14 containing at least one of TaSiN and WSiN is reduced. This also indicates that the copper layer 16 has high orientation properties with respect to the (111) crystal plane of copper.
[0060]
Further, the copper layer for wiring (not shown) formed on the copper layer 16 whose internal stress has been alleviated also has its internal stress alleviated.
[0061]
Since the internal stress of the wiring copper layer and the copper particle size of the wiring copper layer are in inverse proportion, the copper particle size of the wiring copper layer in which the internal stress has been reduced has the internal stress reduced. It is larger than the copper grain size of the non-wiring copper layer. Further, since the copper particle size of the wiring copper layer and the specific resistance of the wiring copper layer are in inverse proportion, the specific resistance of the copper wiring layer having a large copper particle size is smaller than that of the copper having a small copper particle size. It is smaller than the specific resistance of the wiring layer.
[0062]
Therefore, the wiring copper layer formed on the copper layer 16 in which the internal stress is relaxed has a lower specific resistance than the wiring copper layer formed on the copper layer 16 in which the internal stress is not relaxed. In addition, the electrical characteristics of the wiring copper layer are improved.
[0063]
Next, a method of forming a laminated structure for the metal wiring described with reference to FIG. 1 will be described.
[0064]
First, the insulating layer 12 is formed on the substrate 10. By using, for example, a p-type silicon (100) wafer as the substrate 10 and thermally oxidizing a part of the silicon wafer, a silicon oxide layer (specifically, SiO 2) as the insulating layer 12 is formed. ₂ Layer).
[0065]
Next, a barrier layer 14 made of TaSiN and having a thickness of, for example, 30 nm, and a copper layer 16 having a thickness of 20 nm are formed on the insulating layer 12 in the same sputtering chamber in this order. Form. The copper layer 16 can be formed by a sputtering method using a copper target material, and the barrier layer 14 can be formed by a reactive sputtering method in a nitrogen atmosphere using an alloy target material containing Ta and Si.
[0066]
Thus, a laminated structure for metal wiring can be formed. A stacked structure including the barrier layer 14 made of WSiN and the barrier layer 14 containing TaSiN and WSiN can be formed in the same manner.
[0067]
Preferably, the copper layer 16 is heated after the formation of the copper layer 16 (hereinafter, referred to as “annealing”). Thereby, the internal stress of the copper layer 16 is further reduced.
[0068]
This will be described in detail with reference to FIG. In the graph shown in FIG. 2, paying attention to the broken line obtained by connecting the black circles (●), the percentage of the composition ratio of Si in TaSiN when the copper layer 16 was heated at 400 ° C. after the copper layer 16 was formed. Indicates the value of Δ2θ. It is understood that the value of Δ2θ is smaller by approximately 0.1 as compared with the case where the copper layer 16 is not heated, as indicated by the broken line obtained by connecting the white circles (）). That is, it is understood that the internal stress of the copper layer 16 is further reduced.
[0069]
As a result of examining the effect of heating for relaxing the internal stress of the copper layer 16 at various heating temperatures, it was found that the copper layer 16 should be heated at 250 ° C. or higher after the formation of the copper layer 16. According to this, aggregation occurs in the copper layer 16. Due to this aggregation, the internal stress of the copper layer 16 is reduced.
[0070]
The effect of heating the copper layer 16 can be further utilized. For example, another copper layer is formed on the heated copper layer 16 on the barrier layer 14 (second copper layer forming step), and the copper layer is heated (second heat treatment) so as to cause aggregation. Step) alleviates the internal stress of the copper layer. By repeating the second copper layer forming step and the second heat treatment step, relaxation of the internal stress of the copper layer is further promoted.
[0071]
Further, in the second copper layer forming step, a copper layer having a thickness dimension of 20 nm or less is formed by a physical deposition method, and in the second heat treatment step, the copper layer is heated at 250 ° C. or more. If this is the case, the internal stress relaxation of the copper layer is more effectively realized.
[0072]
A part of another copper layer is formed on the copper layer 16 on the barrier layer 14 by a chemical deposition method or a physical deposition method, and after heating this at 250 ° C. or more, the remaining copper layer is removed. By repeating the formation, a heating effect on the internal stress relaxation of the copper layer is further exhibited.
[0073]
The barrier layer 14 can be formed by a reactive sputtering method in a nitrogen atmosphere using an alloy target material containing Ta and Si having a Si composition ratio in the range of 0.02 to 0.15. According to this, a TaSiN barrier layer containing Si at a composition ratio in the range of 0.02 to 0.1 is formed.
[0074]
Further, the barrier layer 14 can be formed by a reactive sputtering method in a nitrogen atmosphere using an alloy target material containing W and Si in which the composition ratio of Si is in the range of 0.05 to 0.4. According to this, a WSiN barrier layer containing Si having a composition ratio in the range of 0.03 to 0.25 is formed.
[0075]
If the copper layer 16 is formed by electroless plating or chemical deposition, for example, the coverage of the copper layer on the barrier layer in the contact hole is improved, and the copper layer is uniformly formed on the barrier layer in the contact hole. It is coated with an appropriate thickness dimension.
[0076]
FIG. 3 shows another laminated structure for metal wiring. This laminated structure includes a substrate 18, a barrier layer 22, and a copper layer 24, and optionally includes an insulating layer 20.
[0077]
This laminated structure is substantially the same as the laminated structure shown in FIG. However, the components of the barrier layer 22 may include various elements including elements widely used at present, for example, Ta, Si, W, and N, in addition to the examples described above. In the illustrated example, the barrier layer 22 is made of TaN, and has a thickness of 30 nm.
[0078]
The copper layer 24 has an aggregation region 26. The agglomerated region 26 is a region in which at least copper as a main component is agglomerated as compared with other regions in the copper layer 24, that is, a region having a large volume density or a region having few crystal grain boundaries.
[0079]
Next, the internal stress of the copper layer 24 in the laminated structure for metal wiring will be described. The internal stress was examined by the same method as described above, that is, by using an X-ray diffraction method applying X-ray spectroscopy.
[0080]
The above measurement was performed on the copper layer 24 having the aggregation regions 26 having different sizes. According to the result, as the aggregation region 26 increases, the angle shift amount Δ2θ of the copper layer 24 decreases. Therefore, it was found that the internal stress of the copper layer 24 having the aggregated region 26 was relaxed, and the copper layer 24 having the larger aggregated region 26 was further relaxed.
[0081]
When the copper layer 24 has the aggregation region 26 formed along the boundary between the copper layer 24 and the barrier layer 22, the internal stress is uniformly reduced. In addition, when the copper layer 24 has the aggregation region 26 occupying almost all of the copper layer 24, it is further relaxed.
[0082]
These also indicate that the copper layer 24 has high orientation properties with respect to the (111) crystal plane of copper.
[0083]
Furthermore, the internal stress is also reduced in the wiring copper layer (not shown) formed on the copper layer 24 in which the internal stress has been reduced.
[0084]
Next, a method of forming a laminated structure for the metal wiring described with reference to FIG. 3 will be described.
[0085]
First, the insulating layer 20 is formed on the substrate 18. For example, a p-type silicon (100) wafer is used as the substrate 18 and a part of the silicon wafer is thermally oxidized to form a silicon oxide layer (specifically, SiO 2) as the insulating layer 20. ₂ Layer).
[0086]
Next, a barrier layer 14 made of TaSiN and having a thickness of, for example, 30 nm, and a copper layer 16 having a thickness of 20 nm are formed on the insulating layer 12 in the same sputtering chamber in this order. Form. The copper layer 16 can be formed by a sputtering method using a copper target material, and the barrier layer 14 can be formed by a reactive sputtering method in a nitrogen atmosphere using an alloy target material containing Ta and Si.
[0087]
Next, a barrier layer 22 made of TaN and having a thickness of, for example, 30 nm, and a copper layer 24 having a thickness of 20 nm are formed on the insulating layer 20 in the same sputtering chamber in this order. Form. The copper layer 24 can be formed by a sputtering method using a copper target material, and the barrier layer 22 can be formed by a reactive sputtering method in a nitrogen atmosphere using an alloy target material containing Ta. After the formation of the copper layer 24, the copper layer 24 is heated at 400 ° C.
[0088]
Please refer to FIG. In the graph shown in FIG. 4, paying attention to the broken line obtained by connecting the black circles (●), the internal stress of the copper layer 24 when the copper layer 24 is heated at various temperatures after the formation of the copper layer 24 is shown. Show. When the copper layer 24 is heated at approximately 250 ° C., the internal stress decreases as compared to the internal stress of the copper layer 24 when the temperature is zero, that is, when no heating is performed. By setting the heating temperature to approximately 300 ° C. and approximately 400 ° C., the internal stress of the copper layer 24 is further reduced. As the heating temperature is set to approximately 300 ° C. and approximately 400 ° C., the degree of decrease in the internal stress of the copper layer 24 decreases.
[0089]
In the graph shown in FIG. 4, attention is paid to the broken line obtained by connecting the black squares (■), and the case where the barrier layer 22 made of Ta is used is shown. Also in this case, when the copper layer 24 is heated at approximately 400 ° C., the internal stress decreases compared to the internal stress of the copper layer 24 when the temperature is zero, that is, when the copper layer 24 is not heated.
[0090]
The aggregation is caused by heating the copper layer 24 at 250 ° C. or higher after the formation of the copper layer 24.
[0091]
The effect of heating such a copper layer 24 so as to cause aggregation can be further utilized. For example, if another copper layer is formed on the heated copper layer 24 on the barrier layer 22 and the copper layer is heated, the internal stress of the copper layer is reduced. By repeating such a copper layer formation and heat treatment, the internal stress relaxation of the copper layer is further promoted.
[0092]
If a copper layer having a thickness of 20 nm or less is formed by a physical deposition method and the copper layer is heated at 250 ° C. or more, the internal stress of the copper layer can be effectively reduced.
[0093]
If a part of another copper layer is further formed on the heated copper layer 24 on the barrier layer 22, heated at 250 ° C. or more, and the remaining copper layer is formed, the inside of the copper layer is repeatedly formed. A heating effect on stress relaxation is further exhibited.
[0094]
If the copper layer 24 is formed by electroless plating or chemical deposition, for example, the coverage of the copper layer on the barrier layer in the contact hole is improved, and the copper layer is uniformly formed on the barrier layer in the contact hole. It is coated with an appropriate thickness dimension.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a laminated structure for metal wiring according to the present invention.
FIG. 2 is a graph showing an angle shift amount of a copper layer in the multilayer structure shown in FIG. 1, and a graph showing a method of forming a multilayer structure for metal wiring according to the present invention.
FIG. 3 is a sectional view showing an embodiment of a laminated structure for metal wiring according to the present invention.
FIG. 4 is a graph showing a method for forming a laminated structure for metal wiring according to the present invention.
FIG. 5 is a cross-sectional view showing a conventional wiring structure.
[Explanation of symbols]
[Explanation of symbols]
10, 18 substrates
12, 20 insulation layer
14, 22 barrier layer
16, 24 copper layer

Claims (32)

A substrate, formed directly or indirectly on the substrate, a barrier layer for preventing diffusion of copper to the substrate, and formed on the barrier layer as a base layer for a wiring copper layer. A stacked structure for metal wiring, wherein the stacked structure includes a copper layer and a copper layer containing copper as a main component, and the barrier layer includes at least one of TaSiN and WSiN. The structure of claim 1, wherein the barrier layer comprises TaSiN, wherein the TaSiN comprises a compositional ratio of Si in a range of 0.01 to 0.1. The structure of claim 1, wherein the barrier layer comprises WSiN, wherein the WSiN comprises a compositional ratio of Si in a range of 0.03-0.25. The structure of claim 1 wherein said barrier layer comprises WSiN, said WSiN comprising a compositional ratio of N in the range of 0.15 to 0.25. A barrier layer forming step of forming a barrier layer containing at least one of TaSiN and WSiN on the substrate, directly or indirectly, for preventing diffusion of copper into the substrate;
Forming a copper layer which is a copper layer as a base layer of the wiring copper layer on the barrier layer, the copper layer being mainly composed of copper. 6. The method of claim 5, further comprising, after forming the copper layer, a heat treatment step of heating the copper layer such that the copper layer agglomerates. The method of claim 6, wherein the heat treating step comprises heating the copper layer at 250 ° C. or higher. Further, a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, and after the formation of the other copper layer, aggregation of the other copper layer occurs. A second heat treatment step of heating said other copper layer. 9. The method according to claim 8, wherein the step of forming the second copper layer and the step of performing the second heat treatment are repeated. The second copper layer forming step includes forming a copper layer having a thickness dimension of 20 nm or less by a physical deposition method, and the second heat treatment step heats the copper layer at 250 ° C. or more. The method of claim 8, comprising: The method further includes repeating a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, wherein the second copper layer forming step includes a chemical deposition method or a physical layer method. 6. The method of claim 5, comprising forming a portion of the copper layer by mechanical deposition and heating above 250 <0> C to form the remainder of the copper layer. 6. The barrier layer forming step according to claim 5, wherein the step of forming a barrier layer includes forming a barrier layer made of TaSiN, wherein the TaSiN contains Si at a composition ratio in a range of 0.01 to 0.1. the method of. The barrier layer forming step is performed by a reactive sputtering method using an alloy material containing Ta and Si, wherein the alloy material contains Si in a composition ratio in a range of 0.02 to 0.15. 6. The method of claim 5, comprising forming a barrier layer of TaSiN, wherein the TaSiN comprises Si in a composition ratio in the range of 0.02 to 0.1. The barrier layer forming step is a reactive sputtering method using an alloy material containing W and Si, wherein the alloy material contains Si in a composition ratio in the range of 0.05 to 0.4. 6. The method of claim 5, including forming a barrier layer comprising WSiN, wherein the WSiN comprises Si at a compositional ratio in the range of 0.03-0.25. 6. The barrier layer forming step according to claim 5, wherein the step of forming the barrier layer includes forming a barrier layer made of WSiN, wherein the WSiN contains N in a composition ratio in a range of 0.15 to 0.25. the method of. The method of claim 5, wherein the step of forming a copper layer comprises forming the copper layer by electroless plating. The method of claim 5, wherein the step of forming a copper layer comprises forming the copper layer by a chemical deposition method. The method of claim 5, further comprising forming a wiring copper layer on the copper layer. A substrate, formed directly or indirectly on the substrate, a barrier layer for preventing diffusion of copper to the substrate, and formed on the barrier layer as a base layer for a wiring copper layer. And a copper layer containing copper as a main component and having a coagulated region. 20. The structure of claim 19, wherein the aggregation region is formed along a boundary between the copper layer and the barrier layer. 20. The structure of claim 19, wherein said agglomeration region occupies substantially all of said copper layer. Directly or indirectly on the substrate, a barrier layer forming step of forming a barrier layer to prevent diffusion of copper to the substrate,
On the barrier layer, a copper layer forming step of forming a copper layer that is a copper layer as a base layer of the wiring copper layer and is mainly composed of copper,
A heat treatment step of heating the copper layer so that aggregation occurs in the copper layer. 23. The method of claim 22, wherein the heat treating step includes heating the copper layer such that aggregation occurs along a boundary between the copper layer and the barrier layer. 23. The method of claim 22, wherein the heat treating step includes heating the copper layer such that substantially all of the copper layer is agglomerated. 23. The method of claim 22, wherein the heat treating step comprises heating the copper layer at 250C or higher. Further, a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, and after the formation of the other copper layer, aggregation of the other copper layer occurs. A second heat treatment step of heating said other copper layer. 27. The method of claim 26, wherein the step of forming a second copper layer and the step of heat treating are repeated. The second copper layer forming step includes forming a copper layer having a thickness dimension of 20 nm or less by a physical deposition method, and the second heat treatment step heats the copper layer at 250 ° C. or more. 27. The method of claim 26, comprising: The method further includes repeating a second copper layer forming step of forming another copper layer containing copper as a main component on the copper layer, wherein the second copper layer forming step includes a chemical deposition method or a physical layer method. 23. The method of claim 22, comprising forming a portion of the copper layer by a static deposition method and heating above 250 <0> C before forming the remainder of the copper layer. 23. The method of claim 22, wherein the step of forming a copper layer comprises forming the copper layer by electroless plating. 23. The method of claim 22, wherein the step of forming a copper layer comprises forming the copper layer by a chemical deposition method. 23. The method of claim 22, further comprising forming a wiring copper layer on the copper layer.

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