JPH0594990A - Manufacture of multilayer interconnection - Google Patents

Abstract

PURPOSE:To prevent a lower layer Al from being fluorinated when a through- hole is filled with W grown on all the surface through a chemical vapor growth method using WFo as material gas and to protect Al against corrosion when w is etched back. CONSTITUTION:A first Al wiring is formed into a laminated structure composed of a Ti 13, a TiN 14, an Al-Cu alloy 15, and a TiW alloy 16, an interlayer insulating film is formed of a plasma oxide film 17, and a through-hole is provided. Then, a Ti 18 and a TiN 19 are formed through a sputtering method, and a W 20 is made to grow all the surface through a chemical vapor growth method. In succession, the W 20 is etched by SF6 gas, and in succession the TiN 19 and the Ti 18 are etched with C2 gas, and the through-hole is filled with metal. Then, a second Al wiring is formed of Al-Cu alloy 121.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-layer wiring, and more particularly to a method for manufacturing a multi-layer wiring mainly containing aluminum.

[0002]

2. Description of the Related Art For higher integration and higher speed of semiconductor devices,
Wiring for connecting elements is becoming finer and multilayered. Therefore, the opening (hereinafter referred to as a through hole) provided in the interlayer insulating film for connecting the wiring layers is also miniaturized. However, in order to maintain the insulation between the wiring layers or to prevent the increase of the wiring capacitance, the interlayer insulation The thickness of the film cannot be reduced, and the so-called aspect ratio, which is the ratio between the size and the depth of the through hole, is increasing. Therefore, it has become impossible to form a metal in the through hole with good coverage by the sputtering method that has been used to grow the wiring metal. In particular, aluminum alloys widely used as wiring materials have poor coverage.

Therefore, a chemical vapor deposition method has been used in which a metal can be formed with good coverage even in a through hole having a large aspect ratio. Usually, a metal halide is used as a raw material, and the most frequently used one is tungsten hexafluoride (WF ₆ ), which is reduced with hydrogen or silane (SiH ₄ ) to grow tungsten. ing.

This chemical vapor deposition method also has two types, one is so-called selective growth in which it is grown only on silicon or metal but not on an insulating film such as a silicon oxide film. Is a method of growing the entire surface of the substrate.

Although selective growth has been mainly studied for through holes connecting aluminum wirings at a relatively low temperature of 200 to 300 ° C., when tungsten is directly grown on aluminum, 3 is formed on the surface of aluminum.
There is a problem that a high resistance material of aluminum fluoride (AlF ₃ ) is formed, which increases the connection resistance. In order to solve this problem, it has been studied to grow tungsten at a high temperature of about 550 ° C., and the VLSI multi-level interconnection conference (VLS) has been studied.
I multilevel interconnect
Ion Conference) 1989 Low Resistance Submicron Sieve D Tungsten
Inter-level via plug-on aluminum-copper-silicon (Low-resistance
submicRON CVDW interleave
1 Via Plugs on Al-Cu-Si). However, in this method, since the growth is performed at a high temperature, the selectivity is deteriorated, tungsten easily grows on an insulating film such as a silicon oxide film, and a short circuit easily occurs between adjacent wirings. There is a problem that the high temperature easily causes disconnection due to so-called stress migration in which a part of the first aluminum wiring is missing.

Therefore, a refractory metal layer of tungsten, molybdenum or the like is provided on the surface of the first aluminum wiring, and when tungsten is selectively grown on the refractory metal layer, a fluorine layer is formed at the interface with the refractory metal layer. The method of suppressing the formation of a compound is also used.

This is described, for example, in JP-A-2-28253. However, even in this method, it is difficult not to grow tungsten on the interlayer insulating film at all, and as the growth film thickness of tungsten increases, tungsten grows in a granular manner on the interlayer insulating film,
There is a problem of causing a short circuit between adjacent wirings.

Therefore, another method, that is, a blanket growth method, in which the entire surface of the substrate is grown, is attracting attention. A method using this blanket growth will be described with reference to the drawings. FIG. 14 is a cross-sectional view of main steps of the first example. First, after forming a first aluminum wiring with an aluminum alloy 23 in which a trace amount of silicon or copper is added to aluminum, an interlayer insulating film is formed with a silicon oxide film (hereinafter referred to as a plasma oxide film) formed by a plasma CVD method. A through hole reaching the first aluminum wiring is formed at a desired position in the oxide film 24 (separated diagram A in FIG. 14). Next, titanium 25 and titanium nitride 26 are sequentially formed by a sputtering method, and WF is formed on the entire surface.
₆ and H ₂ gas are used to grow tungsten to a thickness of about several tens of nm by a low pressure chemical vapor deposition method at a temperature of about 350 to 500 ° C. (division B in FIG. 14). Then aluminum,
After the silicon and copper alloy 28 is grown by the sputtering method, it is patterned into a desired shape by using a normal lithography technique and a dry etching technique to form an aluminum two-layer wiring (division C in FIG. 14).

FIG. 15 is a sectional view showing main steps of the second example. After forming a through hole reaching the first aluminum wiring 33 at a desired position of the plasma oxide film 34 as in the first embodiment, titanium 35 and titanium nitride 36 are sequentially formed by a sputtering method (see FIG. ). Next, tungsten 37 is formed to a thickness of 0.5 to 1.0 μm on the entire surface by reduced pressure chemical vapor deposition to completely fill the through holes (separated diagram B in FIG. 15). Then, so-called etch back is performed by etching away the tungsten 37, the titanium nitride 36, and the titanium 35 on the plasma oxide film 34 by the reactive ion etching method (minute diagram C in FIG. 15). After that, an aluminum / silicon / copper alloy 38 is formed by a sputtering method, and this is patterned into a desired shape to form an aluminum two-layer wiring (division D in FIG. 15).

As for this second example, the VLSI described above is used.
Multi-level interconnection conference (VLSI multilevel intercon
Section conf.) 1989 Proceedings, pages 113 to 121.

[0011]

In this conventional method for forming a multi-layer wiring, as in the second example, tungsten 37 is used.
In the case where the tungsten is grown by the low pressure chemical vapor deposition method and then only the tungsten inside the through hole is left to be etched, a chlorine-based gas is used as the etching gas. The advantage of chlorine gas as the etching method is the 51st Academic Meeting of the Japan Society of Applied Physics (Autumn 1990)
It is described in Proceedings 280-SZD-21. Generally, a fluorine-based gas such as sulfur hexafluoride (SF ₆ ) is first used to etch the tungsten 37 at a high speed until the surface of the titanium nitride 36 is exposed, and then switched to a chlorine-based gas to flatten the surface. A method of etching the titanium nitride 36, the titanium 35, and the tungsten 37 in the through hole with good properties is adopted. In this etching method, since the final etching gas is chlorine-based, when the inside of the through hole is not completely filled as shown in FIG. 16A, the tungsten inside the through hole is etched through the gap of the tungsten. Therefore, there is a problem that the first aluminum wiring is exposed (part B in FIG. 16) and corrodes. This problem becomes more frequent as the through holes become finer and the aspect ratio increases and the tungsten filling shape deteriorates.

Further, in the first conventional example, etching back is not performed, but in a high aspect ratio through hole, since titanium nitride serving as a base film for tungsten growth is formed by the sputtering method, the through hole is formed. The film thickness inside becomes thin, and when tungsten grows, fluorine diffuses in the grain boundaries of titanium nitride and reaches the first aluminum wiring to form a high resistance material of AlF ₃ , which increases the connection resistance. There's a problem. In order to solve this problem, if the film thickness of titanium nitride is increased, the film is formed by the sputtering method, which results in an overhang shape on the side wall of the through hole. Then, when tungsten is grown, as shown in FIG. Cavities tend to form in the holes, degrading reliability.

In order to show how much the film thickness of the underlying metal layer is required when forming tungsten by the chemical vapor deposition method, titanium tungsten (T) is used as the underlying metal layer.
FIG. 17 shows the relationship between the TiW alloy film thickness when the iW) alloy is used and the connection resistance per through hole. The size of the through hole is 0.8 μm × 0.8 μm and the depth is 0.8 μm.

When the thickness of the TiW alloy is 100 nm, it is 500.
Shows a small and stable connection resistance value of ~ 700Ω,
When it is 50 nm or less, it becomes a large value of 1 Ω or more and is not stable. This tendency is more remarkable as the TiW film thickness becomes thinner.

FIG. 18 shows the ratio (h / φ) of the depth (h) of the through hole to the size (φ) of the through hole, that is, the aspect ratio, and the film thickness (a) of the TiW alloy formed by the sputtering method. The relationship (b / a) with the film thickness (b) of the TiW alloy at the bottom of the through hole, that is, the step coverage is shown. The step coverage (b / a) is about 12% in a through hole of φ = 0.8 μm and h = 0.8 μm, and when sputtered to a thickness of 100 nm, 12 nm at the bottom of the through hole and 6 nm when sputtered to 50 nm. Is. In other words, if the thickness of the underlying metal layer is not more than about 10 nm at the bottom of the through hole, it is considered that the through hole portion of the first aluminum wiring is fluorinated by WF ₆ and the connection resistance is increased. Therefore, in order to form a base metal layer having a thickness of 10 nm or more on the bottom of the through hole, it is necessary to form a base metal layer having a larger film thickness by a sputtering method for a through hole having a larger aspect ratio (h / φ). 15 when (h / φ) is 1.5
A base metal layer having a thickness of about 0 nm is required. When tungsten is grown on it by chemical vapor deposition, an overhang shape is formed on the sidewall of the through hole, and a gap is generated in the through hole, which not only lowers the reliability but also does not etch back. The film thickness of the second aluminum wiring becomes thick, the coverage of the passivation film formed thereon deteriorates, and when the third aluminum wiring is further formed thereon, it becomes difficult to flatten the interlayer insulating film. There is a problem.

[0016]

In the method of manufacturing a multilayer wiring according to the present invention, a chemical method using a metal halide in an opening formed in an interlayer insulating film connecting the first aluminum wiring and the second aluminum wiring is used. In a method of manufacturing a multilayer wiring, which includes a step of growing a metal by a full-face growth method using a vapor-phase growth method, and in some cases, a step of completely etching the metal and leaving it only in an opening provided in an interlayer insulating film, It has a feature that a metal other than aluminum is laminated on at least an upper layer of the aluminum wiring.

[0017]

The present invention will be described below with reference to the drawings.
1 to 7 are cross-sectional views of main steps of one embodiment of the present invention.

First, titanium (Ti) is formed on a silicon substrate 1 on which elements are formed and whose surface is covered with a silicon oxide film 2.
3 to 10 to 100 nm, titanium nitride (TiN) 4 to 50 to 200 nm, and Al to Cu alloy 5 in which about 0.5 to 3% of copper is added to aluminum to 300 to 1000 n.
m, titanium-tungsten (TiW) alloy 6 is sequentially formed by the sputtering method (FIG. 1). Ti3 is for reducing the connection resistance with the silicon substrate 1,
TiN 4 is for preventing the reaction between the silicon substrate 1 and the Al—Cu alloy 5. It is desirable that the Al—Cu alloy 5 and the TiW alloy 6 be continuously sputtered without being exposed to the atmosphere. Because Al-Cu alloy 5 and TiW
This is because the connection resistance with the alloy 6 can be minimized.

Next, these Ti3, TiN4 and Al-Cu
After patterning the alloy 5 and the TiW alloy 6 into a desired wiring shape (FIG. 2), an interlayer insulating film is formed with a plasma oxide film 7, and a through hole reaching the TiW alloy 6 at a desired position of the plasma oxide film 7 is formed. Are formed (FIG. 3).

Next, the silicon oxide film is removed by 10 to 50 by a reverse sputter etching method using argon (Ar) gas.
After etching the surface of the silicon substrate under the condition that the TiW alloy 8 is etched by about 20 nm, the TiW alloy 8 is reapplied to
Sputter to a thickness of 0 nm (Fig. 4).

Next, tungsten hexafluoride (WF ₆ ) is reduced with hydrogen (H ₂ ) to form tungsten 9 on the TiW alloy 8 to a thickness of 50 to 300 nm. WF ₆ at this time
On the other hand, H ₂ flows from 15 to 35, and Ar is added to 20 to 20
When the pressure is set to about 40 Torr and the temperature is set to about 350 to 450 ° C., the tungsten 9 grows on the TiW alloy 8 with good coverage (FIG. 5).

Next, the Al--Cu alloy 10 is added again to 0.4.
It is formed by a sputtering method to have a thickness of ˜2.0 μm (FIG. 6). It is desirable that the tungsten 9 and the Al—Cu alloy 10 are formed without being exposed to the air because the connection resistance is reduced.

Next, the Al--Cu alloy 10, tungsten 9, and TiW alloy 8 are patterned into a desired shape, and then heat treatment is performed at a temperature of 400 to 500 ° C. for about 5 to 30 minutes to complete an aluminum two-layer wiring ( (Fig. 7).

Next, another embodiment of the present invention will be described with reference to the drawings. 8 to 13 are sectional views of the main steps. Similar to the embodiment, Ti 13, TiN 14, Al-Cu are formed on the silicon substrate 11 covered with the silicon oxide film 12.
After forming the first aluminum wiring in the laminated structure of 15 and TiW16, an interlayer insulating film is formed by the plasma oxide film 17, and the TiW1 film is formed at a desired position of the plasma oxide film 17.
A through hole reaching 6 is formed (FIG. 8).

Next, the surface of the silicon substrate is etched by a reverse sputter etching method using Ar gas to remove the oxide film layer on the surface of TiW16 exposed in the through holes. Then, Ti18 is 10 to 100 nm and TiN19 is 10 nm.
It is formed by a sputtering method to have a thickness of 200 nm (FIG. 9).

[0026] Next, a tungsten 20 to a thickness of 0.2~1.0μm by the so-called hydrogen reduction method using reducing WF ₆ with hydrogen, completely fill the through hole (Figure 10). Therefore, the grown film thickness of tungsten 20 is
Make it slightly larger than half the size (diameter) of the through hole. Next, the tungsten 20 is entirely etched by reactive ion etching using SF ₆ gas until the surface of the TiN 19 is exposed, and then the etching gas is changed to chlorine (Cl ₂ ) to remove the plasma oxide film 17
The TiN19 and Ti18 are entirely etched and removed until the surface of is exposed (FIG. 11). After that, an Al-Cu alloy 121 is formed to a thickness of 0.4 to 2.0 μm by a sputtering method (FIG. 12).
Is patterned into a desired shape, and heat treatment is performed at a temperature of 400 to 500 ° C. for about 5 to 30 minutes.
The layer wiring is completed (FIG. 13).

In this embodiment, Ti18 and TiN formed by the sputtering method in the fine through holes.
A slight gap may be formed in the tungsten 20 at the through-hole portion, reflecting the slight overhang shape of No. 19, but after that, the tungsten 20, TiN 19, T
Even if i18 is etched back by the reactive ion etching method, since TiW16 is present on the first aluminum wiring, the Al—Cu alloy 15 is not exposed and the chlorine gas corrodes the Al—Cu alloy. There is no.

The upper layer metal of the first aluminum wiring in the above-mentioned two embodiments was TiW, and the underlying layer for growing the entire surface of tungsten was TiW or TiN, but these metals were TiW or TiN. There is no need to limit it, and any metal that does not react with halogen to form a high resistance substance may be used. For example, in addition to TiW and TiN, tungsten (W), molybdenum (Mo), refractory metal silicide such as tungsten silicide or molybdenum silicide is preferable. Further, as a method for forming the upper layer metal of the first aluminum wiring on aluminum or an aluminum alloy, a sputtering method which can form while keeping the surface of aluminum clean because no reaction gas is used is preferable. If the aluminum alloy is formed by the sputtering method without being exposed to the air after formation, it is possible to prevent the surface of aluminum from being oxidized and the connection resistance at this interface is small and stable. Further, when a metal is entirely grown by a chemical vapor deposition method using a metal halide as a raw material, an underlayer metal layer is not always necessary, and the entire surface growth is possible without the underlayer metal layer. The metal grown by the growth method has poor adhesion to the interlayer insulating film and is easily covered. In order to prevent this covering, it is better to form the underlying metal layer with good adhesion to the interlayer insulating film by the sputtering method. The thickness of this underlying metal layer is preferably about 5 to 50 nm. If the thickness is less than 5 nm, the adhesion with the interlayer insulating film cannot be completely improved. In particular, when the adhesion on the side wall of the through hole is poor and is thicker than 50 nm, an overhang shape is formed on the side wall of the through hole, and when tungsten or the like is subsequently grown by the chemical vapor deposition method, a gap is formed inside the through hole. This is because the reliability is deteriorated. Therefore, in the case of a fine through hole having an aspect ratio of 0.8 or more, even if the underlying metal layer is formed to a thickness of 50 nm by the sputtering method, it is 1 at the bottom of the through hole.
Since the film thickness is only 0 nm or less, the effect of the present invention is particularly large in the through hole having the aspect ratio of 0.8 or more.

In the above-described embodiment of the present invention, tungsten is grown using WF ₆ gas as the source gas, but it is not limited to tungsten and other metals may be used. For example, there is a method of growing Mo using MoF ₆ gas as a raw material gas, and it is more preferable to use fluoride as a raw material gas. It is possible to grow a metal using chloride as a raw material, but chlorine tends to remain in the grown metal, and if an aluminum alloy is deposited on it, chlorine may corrode aluminum. is there. However, it is not always the case that chloride cannot be used, and titanium nitride or the like formed by chemical vapor deposition using plasma is used with titanium tetrachloride (TiCl ₄ ) and nitrogen or ammonia (NH ₃ ) as source gases. It is also possible.

[0030]

As described above, in the method for manufacturing a multilayer wiring according to the present invention, since the metal layer other than aluminum is provided at least on the upper layer of the first aluminum wiring, the through hole provided in the interlayer insulating film is provided. Even if the metal is grown by the full-scale growth by the chemical vapor deposition method using the metal halide as a raw material, it is possible to prevent the aluminum of the first aluminum wiring from reacting with the halogen and reduce the connection resistance in the through hole. It can be stably formed.

FIG. 19 shows the connection resistance per through hole of the aluminum two-layer wiring formed according to the embodiment of the present invention and the film thickness of the TiW alloy as the underlying metal layer in the chemical vapor deposition of tungsten. Show the relationship. The film thickness of the TiW alloy is stable, showing almost the same connection resistance value in the range of 10 to 100 nm. Therefore, the thickness of the underlying metal layer is 1
Since a thickness of about 0 nm is sufficient, the underlying metal layer does not have an overhang shape even in a fine through hole having an aspect ratio of 1 or more, and the tungsten coating shape formed thereon is good. Even if it is formed, the covering property can be improved, the aluminum is not broken, and even if the through hole is filled with tungsten, there is no gap and there is no problem of lowering the reliability.

Further, when etching back the tungsten formed by the chemical vapor deposition method, even if there is a gap in the through hole, it is possible to prevent the aluminum of the first aluminum wiring from being exposed. So, aluminum is exposed to chlorine gas,
There is also an effect that aluminum can be prevented from being corroded and stable through-hole connection can be achieved.

Further, since the film thickness of the underlying metal layer when the metal is entirely grown by chemical vapor deposition can be made thin, the etching back becomes easy, and the film thickness of the aluminum wiring when the etching back is not performed. Since the thickness becomes thin, the coverage of the passivation film formed thereon is good and the reliability is not lowered. Furthermore, the flattening of the interlayer insulating film is facilitated when forming the aluminum wiring of the third and subsequent layers, and the use of the present invention facilitates the manufacture of aluminum three-layer wiring or more.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the features of a manufacturing process according to a manufacturing method of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another feature of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 4 is a sectional view showing still another feature of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing still another characteristic of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 6 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 7 is a cross-sectional view showing still another characteristic of the manufacturing process according to the manufacturing method of the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing the features of a manufacturing process according to a manufacturing method of another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing another feature of the manufacturing process according to the manufacturing method of another embodiment of the present invention.

FIG. 10 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of another embodiment of the present invention.

FIG. 11 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of another embodiment of the present invention.

FIG. 12 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of another embodiment of the present invention.

FIG. 13 is a cross-sectional view showing still another feature of the manufacturing process according to the manufacturing method of another embodiment of the present invention.

FIG. 14 is a cross-sectional view of main steps of a conventional manufacturing method.

FIG. 15 is a cross-sectional view of main steps of a conventional manufacturing method.

FIG. 16 is a cross-sectional view for explaining the problems of the conventional example.

FIG. 17 is a graph showing a connection resistance value per through hole with respect to a TiW alloy film thickness in a conventional example.

FIG. 18: TiW vs. aspect ratio of through hole
It is a graph which shows the step coverage of an alloy.

FIG. 19 is a graph showing a connection resistance value per through hole with respect to a TiW alloy film thickness according to an example of the present invention.

[Explanation of symbols]

1,11,21,31,41 Silicon substrate 2,12,22,32,42 Silicon oxide film 3,13,18,25,35,45 Titanium 4,14,19,26,36,46 Titanium nitride 5, 10,15,121 Al-Cu alloy 6,8,16 TiW alloy 7,17,24,34,44 Plasma oxide film 9,20,27,37,47 Tungsten 23,28,33,38,43 Al-Si -Cu alloy

Claims (11)

[Claims] 1. A step of forming a first aluminum wiring, a step of forming an interlayer insulating film, a step of forming an opening reaching the first aluminum wiring in the interlayer insulating film, and a metal halide as a raw material. In the method for producing a multi-layer wiring including the step of entirely growing a metal by the chemical vapor deposition method, a metal other than aluminum is laminated on at least an upper layer of the first aluminum wiring. Production method. 2. A step of forming a first aluminum wiring, a step of forming an interlayer insulating film, a step of forming an opening in the interlayer insulating film reaching the first aluminum wiring, and using a metal halide as a raw material. In the method for producing a multilayer wiring, which includes a step of completely growing a metal by chemical vapor deposition and a step of completely etching the completely grown metal by dry etching, at least an upper layer of the first aluminum wiring is made of a material other than aluminum. A method of manufacturing a multi-layer wiring, comprising laminating metals. 3. The method for manufacturing a multilayer wiring according to claim 2, wherein the dry etching includes a step of etching with a chlorine-based gas. 4. A base metal layer formed by a sputtering method when a metal is entirely grown by a chemical vapor deposition method using the metal halide as a raw material, and there is a base metal layer. Manufacturing method of multilayer wiring. 5. The method for manufacturing a multilayer wiring according to claim 1, wherein a metal other than aluminum, which is laminated on at least an upper layer of the first aluminum wiring, is formed by a sputtering method. 6. The method of forming a metal other than aluminum to be laminated on at least an upper layer of the first aluminum wiring by a sputtering method, after the aluminum or aluminum alloy is formed, without exposing to the atmosphere. Item 6. A method for manufacturing a multilayer wiring according to Item 5. 7. The uppermost layer of a metal other than aluminum laminated on at least an upper layer of the first aluminum wiring is a metal which does not react with halogen to form a high resistance substance. The method for manufacturing a multilayer wiring according to claim 2. 8. The metal underlayer and the uppermost layer when a metal is entirely grown by chemical vapor deposition using the metal halide as a raw material are metals that do not react with halogen to form a high resistance substance. The method for manufacturing a multilayer wiring according to claim 4, which is characterized in that. 9. The metal halide is tungsten hexafluoride (WF ₆ ) or molybdenum hexafluoride (MoF ₆ ).
The method for manufacturing a multilayer wiring according to claim 1 or 2, wherein 10. The manufacturing method of multilayer wiring according to claim 4, wherein the thickness of the underlying metal layer when the metal is grown by chemical vapor deposition using the metal halide as a raw material is 5 to 50 nm. Method. 11. The ratio (h / φ) between the size (φ) and the depth (h) of the opening formed in the interlayer insulating film is 0.8 or more. Manufacturing method of multilayer wiring.