JP3062464B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device using Cu for metal wiring.

[0002]

2. Description of the Related Art In recent years, with higher performance of semiconductor devices, higher speeds of semiconductor devices have been increasingly required, and it is necessary to reduce wiring resistance in order to realize higher speeds. Becomes At present, as an effective means for lowering the resistance of metal wiring, aluminum (A
l) or a wiring material made of an Al—Cu alloy containing about 0.1 wt% to 0.5 wt% of copper (Cu),
Attempts have been made to replace u.

However, when Cu is used for the wiring material,
Since dry etching is not as easy as Al, a conventional wiring forming method using dry etching cannot be performed. Therefore, when a wiring material made of Cu is used, a wiring pattern is formed on an insulating film, and a wiring pattern formed on the insulating film is filled with Cu to form an embedded wiring. In general, before filling a wiring pattern with a metal film made of Cu, a barrier layer for preventing oxidation of Cu and diffusion of Cu to the insulating film side is formed. As a material of the barrier layer, a nitride of a high melting point metal such as titanium (Ti), tantalum (Ta), and tungsten (W) is used.

[0004]

However, the conventional semiconductor device using the metal wiring made of Cu is a Cu
Since the barrier layers are provided on the bottom and side surfaces of the wiring body, the barrier layer having a higher specific resistance than Cu occupies part of the metal wiring, and the cross-sectional area of the wiring body is reduced. However, there is a problem that the wiring resistance is increased as compared with the case where no wiring is provided.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and enables a metal wiring made of Cu to be provided with a barrier layer that prevents oxidation of Cu and diffusion into an insulating film and has a small specific resistance. The purpose is to:

[0006]

In order to achieve the above-mentioned object, the present invention provides a barrier layer formed between a wiring body portion made of Cu and an insulating film, which has an anti-oxidation function of the wiring body portion and a Cu layer. Having a function of preventing diffusion into the insulating film and using a metal having a small specific resistance.

[0007]

[0008]

[0009]

[0010] semi-conductor device according to the present invention, a plurality of semiconductor devices formed on a substrate, an insulating film for insulating each other semiconductor devices from each other the plurality of metal that is a plurality of semiconductor elements electrically connected A metal wiring, wherein the metal wiring is a wiring main body made of a metal containing Cu, and a first barrier layer made of a first metal that covers the bottom surface and side surfaces of the wiring main body in a close contact state. And a second barrier layer made of a second metal having a passivation film formed on the interface with the insulating film and covering the surface of the first barrier layer on the side opposite to the wiring main body in an intimate contact state. And the specific resistance of the first metal is
The first barrier layer prevents Cu contained in the wiring body from diffusing to the insulating film side, and the second barrier layer forms an oxidation of the wiring body by a passivation film. To prevent

According to the semiconductor device of the present invention, the first barrier layer for preventing the diffusion of Cu contained in the wiring body toward the insulating film is provided on the bottom and side surfaces of the wiring body made of metal containing Cu. A second barrier layer formed in close contact with the surface of the first barrier layer on the side opposite to the wiring body and preventing oxidation of the wiring body by a passivation film formed of an oxide film formed at an interface with the insulating film. Because the barrier layer of is provided,
In the wiring body, the Cu in the wiring body is prevented from being diffused to the insulating film side by the first barrier layer, so that the insulating property of the insulating film is not deteriorated. However, since the passivation film generated at the interface between the second barrier layer and the insulating film prevents diffusion of oxygen from the outside to the wiring main body, the resistance of the wiring main body does not decrease. Further, the first metal forming the first barrier layer formed on the wiring main body side has a lower specific resistance than the second metal forming the second barrier layer, so that the low resistance of the wiring main body is low. Does not hinder resistance.

[0012]

In the semiconductor device of the present invention , the first metal is an alloy containing Cu in supersaturation, and the second metal is Cr,
It is preferably Fe, Ti, Co, Ni, Nb, Ta or an alloy thereof.

In the semiconductor device according to the present invention , the first metal is preferably an alloy composed of Al and Cu.

[0015]

(First Embodiment) A first embodiment of the present invention.
An embodiment will be described with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a metal wiring of a semiconductor device according to a first embodiment of the present invention. As shown in FIG. 1, a semiconductor substrate 10 made of silicon (Si) has, for example, two MOSFETs as semiconductor elements.
(Not shown) are formed, and a source / drain region 10a of each MOSFET and an element isolation film 11 for separating the source / drain region 10a from each other are formed. A first insulating film 12 made of silicon oxide (SiO ₂ ) is formed on the semiconductor substrate 10, and the source / drain region 10 a of the first insulating film 12 is formed above each source / drain region 10 a. A contact hole 12a exposing the upper surface is selectively formed. Titanium nitride (TiN) / Ti
Metal / contact metal layer 1 formed by stacking
3 is formed, and a plug 14 filled with W is formed on the barrier metal / contact metal layer 13 in the contact hole 12a.

The second insulating film 1 is formed on the first insulating film 12.
In the second insulating film 15, an opening 15a to be a metal wiring forming region in contact with the upper surface of the plug 14 is selectively formed. In the opening 15a, a wiring made of Cu is formed. A main body 16 and a wiring main body 16 made of Cr
And a barrier layer 17 which covers the bottom and side surfaces of the metal wiring 18 in close contact with each other. Here, the first insulating film 12 and the second insulating film 1 in the barrier layer 17 are used.
At the interface with 5, a passive film is formed.

On the second insulating film 15, a passivation film 19 made of silicon nitride (SiN) for preventing oxidation of the metal wiring 18 is formed.

In this embodiment, the metal wiring 1
Although 8 is one layer, it may be a multilayer wiring of two or more layers.

Although the MOSFET is used as the semiconductor element, any semiconductor active element or semiconductor passive element may be used.

Hereinafter, a method of manufacturing the semiconductor device configured as described above will be described with reference to the drawings.

FIGS. 2A to 2D show cross-sectional structures in the order of steps of a method for manufacturing a semiconductor device according to the first embodiment of the present invention. First, for example, as shown in FIG.
Source / drain region 10a of two MOSFETs and LOC separating source / drain region 10a from each other
A 2.0 μm thick SiO 2 film is formed on a semiconductor substrate 10 made of Si on which an element isolation film 11 made of an OS film or the like is formed.
After depositing the first insulating film 12 of ₂ , the first insulating film 12 is planarized.

Next, above the source / drain regions 10a in the first insulating film 12, the upper surfaces of the source / drain regions 10a are exposed and contact holes 12a having an inner diameter of 0.5 μm are opened. The thickness is 50 nm on the wall surface and the bottom surface of the contact hole 12a by using the method.
A barrier metal / contact metal layer 13 formed by laminating a TiN layer having a thickness of 70 nm and a Ti layer having a thickness of 70 nm is deposited.

Subsequently, W is deposited over the entire surface of the substrate 10 by chemical vapor deposition (CVD), and then flattened by etching back, thereby forming a barrier metal / contact in the contact hole 12a. A plug 14 made of W is filled on the metal layer 13.

Next, as shown in FIG.
After depositing a second insulating film 15 of SiO _{2 having a} thickness of 0.5 μm over the entire surface, a mask pattern (not shown) is formed by using photolithography, and then the mask pattern is used. By etching the second insulating film 15 and performing predetermined patterning on the second insulating film 15, an opening 15a to be a metal wiring formation region is formed.

Next, as shown in FIG. 2C, a film thickness of 5
A barrier forming layer 17A made of 0 nm Cr and
After successively depositing the wiring main body forming layer 16A made of μm Cu, the barrier forming layer 17A and the wiring main body forming layer 16A are filled in the openings 15a by performing reflow at a reflow temperature of 500 ° C.

Next, as shown in FIG. 2D, planarization is performed by chemical mechanical polishing (CMP) until the upper surface of the second insulating film 15 is exposed. After forming a metal wiring 18 composed of a barrier layer 17 covering the bottom and side surfaces of the wiring main body 16 in close contact with each other, a passivation film 19 made of SiN is deposited on the entire surface of the substrate 10.

In this embodiment, the barrier layer 1
7, Cr was used, but the present invention is not limited to this, and Fe or Cr-F
An e-alloy may be used.

Further, the barrier forming layer 17A and the wiring main body forming layer 16A are formed by the sputtering method and the subsequent reflow heat treatment, but may be formed by the plating method.

Here, the wiring body portion forming layer 1 made of Cu
After depositing 6A, the state of oxidation of the wiring body portion forming layer 16A side at the interface between the wiring body portion forming layer 16A and the barrier forming layer 17A was examined using a transmission electron microscope (TEM). No Cu oxide was detected on the part forming layer 16A side.

Further, a second electron beam is obtained using Auger electron spectroscopy.
When the concentration of Cu on the second insulating film 15 side at the interface between the insulating film 15 and the barrier forming layer 17A was examined, Cu was not detected.

When the barrier forming layer 17A is not provided on the wiring body portion forming layer 16A, Cu contained in the wiring body portion forming layer 16A near the interface with the second insulating film 15 is oxidized, and Cu was diffused in the second insulating film 15 near the interface with the wiring body portion forming layer 16A.

When the specific resistance of the metal wiring 18 was measured, it was 2.2 μΩ · cm when Cr or Fe was used for the barrier layer 17. Of 2.4 μΩ · cm.

As described above, the semiconductor device according to the present embodiment includes the wiring body 16 made of Cu and the barrier layer 17 made of Cr or Fe, which covers the bottom and side surfaces of the wiring body 16 in close contact. Cr or Fe constituting the barrier layer 17 is made of a passivation made of an oxide film having excellent corrosion resistance at the interface with the first insulating film 12 and the second insulating film 15. Since a film is formed, S
Since Cu in the wiring body 16 is not oxidized by oxygen contained in the insulating film made of iO ₂ or oxygen in an oxidizing atmosphere, the resistance value of the wiring body 16 does not increase.

In addition, Cr or Fe constituting the barrier layer 17 prevents the diffusion of Cu, so that the worst case in which the metal wirings 18 are short-circuited due to the diffusion of Cu to the insulating film side is avoided. be able to.

Further, since Cr or Fe constituting the barrier layer 17 has a lower specific resistance than a conventional nitride of a high melting point metal such as Ti, Ta, or W, it protects the metal wiring 18 mainly composed of Cu. At the same time, a reduction in resistance can be reliably realized.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIGS. 3A to 3D show sectional structures in the order of steps of a method for manufacturing a semiconductor device according to the second embodiment of the present invention. As described above, the barrier layer for protecting the wiring main body made of Cu has two functions of preventing diffusion of Cu from the wiring main body and preventing intrusion of oxygen from the outside into the wiring main body, and has a low resistance. It is desirable to have the characteristic that there is. Therefore, the present embodiment aims to optimize these functions and characteristics. Here, the manufacturing steps up to FIG. 3A and FIG. 3B are the same as the manufacturing steps shown in FIG. 2A and FIG.

As shown in FIG. 3C, the film thickness is 25 nm over the entire surface of the substrate 10 by using the sputtering method.
, An oxygen barrier forming layer 21A as a second barrier layer forming layer, and a copper barrier forming layer 2 as a first barrier layer forming layer made of Mo having a thickness of 25 nm.
2A and a wiring main body forming layer 16A made of Cu having a thickness of 1 μm are sequentially deposited, and then reflowed at a reflow temperature of 500 ° C., whereby the oxygen barrier forming layer 21 is formed.
A, copper barrier forming layer 22A and wiring body portion forming layer 16A
Is filled in the opening 15a.

Next, as shown in FIG. 3D, planarization is performed using a CMP method until the upper surface of the second insulating film 15 is exposed. A metal wiring 18 composed of a copper barrier layer 22 that covers the bottom surface and side surfaces of the wiring 16 in close contact and an oxygen barrier layer 21 that covers the surface of the copper barrier layer 22 on the side opposite to the wiring body 16 in close contact. After the formation, a passivation film 19 made of SiN is deposited on the entire surface of the substrate 10.

In this embodiment, Cr is used for the oxygen barrier layer 21, but the present invention is not limited to this.
-A Fe alloy may be used. Further, the oxygen barrier layer 21
In order to provide the copper barrier layer 22 with a Cu diffusion preventing function, a passivation film may be formed, and Ti, cobalt (Co), nickel (Ni), niobium (Nb), Ta,
Al or an alloy thereof may be used.

Although the oxygen barrier forming layer 21A, the copper barrier forming layer 22A, and the wiring main body forming layer 16A are formed by a sputtering method and a subsequent reflow treatment, a plating method may be used.

Here, the metal wiring forming region 1 in FIG. 3 (c) will be described by enlarging it to FIG. 4. After depositing a wiring main body forming layer 16A made of Cu, the wiring main body forming layer 16A is formed using a TEM. When the state of oxidation of the wiring main body forming layer 16A side at the interface between the layer 16A and the copper barrier forming layer 22A was examined, no Cu oxide was detected on the wiring main body forming layer 16A side.

Further, the second electron beam is measured using Auger electron spectroscopy.
When the concentration of Cu on the second insulating film 15 side at the interface between the insulating film 15 and the oxygen barrier forming layer 21A was examined,
u was not detected.

When the specific resistance of the metal wiring 18 was measured, it was 2.0 μΩ · cm when Cr or Fe was used for the oxygen barrier layer 21.

As described above, the semiconductor device according to the present embodiment includes the wiring body 16 made of Cu and the wiring body 16.
And a copper barrier layer 22 as a first barrier layer made of Mo covering the bottom and side surfaces of the copper barrier layer 22 in close contact with each other.
It has a metal wiring 18 made of r or Fe or the like and composed of an oxygen barrier layer 21 as a second barrier layer.

As a result, a passivation film made of an oxide film having excellent corrosion resistance is formed on the interface between the first insulating film 12 and the second insulating film 15 of Cr, Fe, or the like constituting the oxygen barrier layer 21. Therefore, the wiring main body 1 may be damaged by oxygen contained in the insulating film made of SiO ₂ or oxygen in an oxidizing atmosphere.
Since Cu of No. 6 is not oxidized, the resistance value of the wiring body 16 does not increase.

Further, Mo constituting the copper barrier layer 22 is:
In order to prevent the diffusion of Cu, the worst case in which the metal wirings 18 are short-circuited due to the diffusion of Cu to the insulating film side can be avoided. Further, Mo is C
Since the specific resistance is smaller than that of r or Fe, it is possible to further reduce the resistance.

(Modification of Second Embodiment) Hereinafter, a modification of the second embodiment of the present invention will be described with reference to the drawings.

FIGS. 5A to 5D show cross-sectional structures in the order of steps of a method for manufacturing a semiconductor device according to a modification of the second embodiment of the present invention. This modification is to improve the adhesion of the wiring body portion made of Cu with the copper barrier layer by using an Al—Cu alloy containing Cu in supersaturation for the copper barrier layer as the first barrier layer, and to improve the copper barrier layer. It is intended to further reduce resistance. Here, the copper barrier layer is referred to as an adhesion layer.

Here, the manufacturing steps up to FIGS. 5A and 5B are the same as the manufacturing steps shown in FIGS. 2A and 2B. I do.

As shown in FIG. 5C, the film thickness is 25 nm over the entire surface of the substrate 10 by using the sputtering method.
An oxygen-barrier forming layer 21A as a forming layer of a second barrier layer, an Al-Cu alloy having a thickness of 25 nm, a Cu concentration of 10 wt%, and a supersaturated state, and a first barrier layer Adhesion layer forming layer 32 as a forming layer of
A and wiring body portion forming layer 1 made of Cu having a thickness of 1 μm
6A are sequentially deposited, and then reflowed at a reflow temperature of 500 ° C., whereby the oxygen barrier forming layer 21A,
The opening 15a is filled with the adhesion layer forming layer 32A and the wiring main body forming layer 16A.

Next, as shown in FIG. 5D, planarization is performed using a CMP method until the upper surface of the second insulating film 15 is exposed. After forming the metal wiring 18 composed of an adhesion layer 32 that covers the bottom and side surfaces of the adhesion layer 16 in close contact, and an oxygen barrier layer 21 that covers the surface of the adhesion layer 32 opposite to the wiring body 16 in close contact Then, a passivation film 19 made of SiN is deposited on the entire surface of the substrate 10.

In this embodiment, the oxygen barrier layer 21
Was used, but not limited to this, Fe or Cr-Fe
An alloy may be used. Further, the oxygen barrier layer 21 is made of C
In order to provide the adhesion layer 32 with a function of preventing the diffusion of u, a passivation film may be formed, and Ti, cobalt (Co), nickel (Ni), niobium (Nb), Ta, Al, or an alloy thereof is used. You may.

Here, the metal wiring forming region 1 in FIG. 5C will be described by enlarging it to FIG. 6. After depositing a wiring main body forming layer 16A made of Cu, the wiring main body forming layer 16A is formed using a TEM. When the state of oxidation of the wiring main body forming layer 16A at the interface between the layer 16A and the adhesion layer forming layer 32A was examined, no Cu oxide was detected on the wiring main body forming layer 16A side.

Further, the second electron beam is measured using Auger electron spectroscopy.
When the concentration of Cu on the second insulating film 15 side at the interface between the insulating film 15 and the oxygen barrier forming layer 21A was examined,
u was not detected.

When the adhesion of the wiring body portion forming layer 16A was evaluated by using a peeling method, higher adhesion was obtained than in the first embodiment or the second embodiment.

As described above, the semiconductor device according to the present modification has the wiring main body 16 made of Cu and the wiring main body 16.
Cu that covers the bottom and side surfaces of Cu in close contact with Al-
Adhesion layer 32 made of Cu alloy as first barrier layer
And an oxygen barrier layer 21 made of Cr or Fe or the like, which covers the surface of the adhesion layer 32 on the side opposite to the wiring body 16 in an adhesion state, and which is an oxygen barrier layer 21 as a second barrier layer. I have.

Therefore, the Cr constituting the oxygen barrier layer 21
Or, the first insulating film 12 and the second insulating film 15
Since a passive film made of an oxide film having excellent corrosion resistance is generated at the interface with the substrate, Cu in the wiring body 16 is not oxidized by oxygen contained in the insulating film made of SiO ₂ or oxygen in the oxidizing atmosphere. The resistance of the wiring body 16 does not increase.

Further, the Cu-supersaturated Al—Cu alloy that forms the adhesion layer 32 prevents the Cu excessively contained in the alloy from invading from other parts by diffusion of Cu.
The worst case in which the metal wirings 18 are short-circuited due to the diffusion of u can be avoided. Also, since the specific resistance of Al-Cu alloy is smaller than that of Mo,
Further lower resistance can be realized, and the wiring body 16
Cu and Al of the adhesion layer 32 form an alloy at the interface, and the adhesion to the wiring body 16 is higher than that of Cr, Fe, Mo, or the like, so that the reliability of the wiring body 16 for a long time is improved. .

[0061]

【The invention's effect】

[0062]

[0063] According to the semi-conductor device of the present invention, the first barrier layer made of a metal which is formed by close contact on the bottom and side surfaces of the wiring main body formed of Cu is included in the routing unit C
Since u is prevented from diffusing to the insulating film side, the insulating property of the insulating film is not deteriorated. Also, a second barrier layer formed in close contact with the surface of the first barrier layer opposite to the wiring body portion.
In the barrier layer, a stable passivation film made of an oxide film is formed at the interface with the insulating film, and the passivation film prevents oxidation from the outside of the wiring body portion. Is suppressed.

Further, the first metal forming the first barrier layer formed on the wiring main body side has a lower specific resistance than the second metal forming the second barrier layer. Since the resistance of the wiring portion is not prevented, predetermined electrical characteristics can be obtained for the metal wiring containing Cu, and the reliability of the wiring main body can be improved.

[0065]

In the semiconductor device of the present invention , the first metal is an alloy containing Cu in supersaturation, and the second metal is Cr,
When Fe, Ti, Co, Ni, Nb, Ta or an alloy thereof is used, an alloy containing Cu in supersaturation can prevent the diffusion of Cu contained in the wiring body and has a lower resistance than Cr or Fe. Therefore, the first barrier layer can be reliably formed, and the base metal of the alloy and Cu contained in the wiring body form an alloy at the interface. The reliability of the part can be further improved. In addition, since a passivation film is formed and low resistance is made of Cr or Fe, the second barrier layer can be reliably formed.

In the semiconductor device according to the present invention , if the first metal is an alloy composed of Al and Cu, an alloy containing Cu in supersaturation can be surely formed.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view showing a semiconductor device according to a first embodiment of the present invention.

FIGS. 2A to 2D are cross-sectional views illustrating a method of manufacturing the semiconductor device according to the first embodiment of the present invention in order of process.

FIGS. 3A to 3D are cross-sectional views in a process order showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a partially enlarged view of one step in a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIGS. 5A to 5D are cross-sectional views illustrating a method of manufacturing a semiconductor device according to a modification of the second embodiment;

FIG. 6 is a partially enlarged view of one step in a method of manufacturing a semiconductor device according to a modification of the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 metal wiring formation region 10 semiconductor substrate 10a source / drain region 11 element isolation film 12 first insulating film 12a contact hole 13 barrier metal / contact metal layer 14 plug 15 second insulating film 15a opening 16 wiring body 16A wiring Body part forming layer 17 Barrier layer 18 Metal wiring 19 Passivation film 21 Oxygen barrier layer (second barrier layer) 21A Oxygen barrier forming layer 22 Copper barrier layer (First barrier layer) 22A Copper barrier forming layer 32 Adhesion layer (Second layer) 1A barrier layer) 32A adhesion layer forming layer

Claims (2)

(57) [Claims] 1. A semiconductor comprising: a plurality of semiconductor elements formed on a substrate; an insulating film that insulates the plurality of semiconductor elements from each other; and a metal wiring electrically connected to the plurality of semiconductor elements. The device, wherein the metal wiring includes a wiring main body made of a metal containing Cu, and a bottom surface and side surfaces of the wiring main body that are in close contact with each other.
A first barrier layer made of a second metal and a second metal having a passivation film formed at an interface with the insulating film.
And a second barrier layer that covers the surface of the barrier layer on the side opposite to the wiring main body in a close contact state, wherein the specific resistance of the first metal is smaller than the specific resistance of the second metal. The first barrier layer is formed of Cu contained in the wiring main body.
The second barrier layer prevents oxidation of the wiring main body by the passivation film , the first metal is an alloy containing Cu in supersaturation, The second metal is Cr, Fe, Ti, Co, Ni, N
b, Ta, or an alloy thereof . 2. The semiconductor device according to claim 1 , wherein said first metal is an alloy made of Al and Cu.