JPH0766157A - Formation of wiring - Google Patents

Abstract

PURPOSE:To provide a method for forming a wiring in which delamination does not take place in the process for forming a wiring of high melting point metal and generation of particles is prevented. CONSTITUTION:A metallic layer 4 of Ti, for example, is formed at a contact part and a barrier metal layer 5 is formed thereon followed by formation of high melting point metal layer 6 of Blk-W, for example, by CVD. In such method for forming a wiring, an anti-oxidation layer 8 is formed, under the underlying metal layer 4, of a metal, e.g. Al, having higher standard generation energy than the metal layer 4 or of an insulation film of SiN, for example, containing no oxygen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring forming method. INDUSTRIAL APPLICABILITY The wiring forming method of the present invention can be used in various fields having a wiring structure, and can be used, for example, as a method of forming wirings or contacts of electronic materials (semiconductor devices etc.).

[0002]

2. Description of the Related Art There are various demands such as miniaturization for various materials having a wiring structure. For example, miniaturization and high performance are required for various devices of semiconductor integrated circuits. In order to meet this demand, in the field of semiconductor devices, a wiring generally uses a multilayer wiring structure with an interlayer insulating film interposed. On the other hand, at the same time, due to the demand for higher density, miniaturization of wiring patterns is progressing.

As a result of the above requirements, the wiring formed on the interlayer insulating film and the wiring portion under the interlayer insulating film, the Si semiconductor, etc. through various connection holes called contact holes and via holes opened in the interlayer insulating film. The diameter of the connection hole that forms the electrical connection to the impurity diffusion region portion in
Inevitably miniaturized. In this case, the interlayer insulating film needs to have a predetermined thickness due to problems such as its electrical reliability and parasitic capacitance, and as a result, the aspect ratio of the connection hole tends to increase.

As described above, as a technique for embedding a conductive material such as a metal plug in a connection hole having a high aspect ratio,
Blanket tungsten (Blk- by CVD method)
W) formation or high temperature Al sputtering.

In any of these Blk-W CVD, Al high temperature sputtering, etc., a barrier metal layer is formed as an underlying layer in order to prevent adhesion and metal penetration. In the case of Blk-W, the barrier metal layer is sometimes called an adhesion layer because the purpose is mainly to secure the adhesion between W and the underlying film.

FIG. 3 shows a sectional view of an example of a conventional technique using Blk-W. The structure of FIG. 3 can be formed as follows, for example. For example, Al-1% S on the surface of a semiconductor substrate
When forming a lower layer wiring in which the i film 1 and the antireflection film TiON 2 are laminated and then connecting the wiring through a connection hole opened in the formed interlayer insulating film SiO ₂ 3, first, a metal for forming an ohmic contact is formed. A Ti film is formed as the layer 4. Next, titanium nitride TiN is used as the barrier metal layer 5.
Blk-W, which is a refractory metal 6, is formed on this film.
To form a film.

When TiN is directly formed without forming Ti, Al exposed in the contact hole is nitrided in a sputtering atmosphere for forming TiN, and ohmic contact cannot be obtained.

[0008]

However, in the above-mentioned conventional technique, when the refractory metal 6 (Blk-W) is deposited, the metal layer (Ti) 4 and SiO ₂ 3 are formed during the deposition as shown in FIG. Peeling may occur at the interface of. This is considered to be due to the following mechanism. WF which is the source gas
₆ is originally blocked by TiN5 which is a barrier metal, but penetrates into the interface at the side wall of the contact hole with poor coverage. In this interface Ti4 and SiO ₂ 3
React to form titanium oxide TiO ₂ 7 inevitably, and if WF ₆ invades here, Ti with high vapor pressure is formed.
OF _x is formed. Therefore, peeling is considered to occur. This peeling causes particles, which is a problem for the wiring connection structure, and is not preferable especially in the semiconductor process.

[0009]

An object of the present invention is to provide a wiring forming method for solving the above-mentioned problems. Even in the wiring forming for forming a refractory metal, film peeling or the like does not occur in the wiring forming process. It is an object of the present invention to provide a wiring forming method that prevents inconveniences such as occurrence.

[0010]

In order to achieve the above object, the invention according to claim 1 of the present application provides a step of forming a metal material layer for connection formation in a contact portion for forming an electrical connection, and the metal. In the step of forming a barrier metal on the upper layer of the base material layer and the method of forming a wiring on the upper layer of the refractory metal base material by the CVD method, the oxidation preventing layer is formed below the lower metal base material layer. To take.

According to the invention of claim 2 of the present application, in the invention of claim 1, a metal having a larger standard generation energy than that of the lower metal-based material layer is used as the antioxidant layer. For example, when the lower metal-based material is Ti, Al can be used. (For the standard energy of formation of metal, for example, for the standard energy of nitride, see “Rare Metal Encyclopedia” (April 1991, Fuji Techno System), p. 207).

According to a third aspect of the present invention, in the first aspect of the invention, an insulating film containing no oxygen is used as the oxidation preventing layer. As an insulating film that does not contain oxygen,
For example, SiN can be used.

[0013]

According to the present invention, as the lower metallic material layer,
A low-resistance contact is obtained using a material that can obtain a low-resistance ohmic contact, and a refractory metal material (Blk-W film or the like) so that peeling does not occur.
Can be formed into a film. For example, an upper layer of the interlayer insulating film is made of an insulating film containing no oxygen (such as a silicon nitride film), or a metal having a higher standard production energy than the metallic material is formed as a lower layer of the metallic material layer (Ti, etc.). Then, by forming an antioxidant layer, a metal layer (Ti, etc.) as an adhesion layer
This is because it is configured to prevent the oxidation of

That is, in the present invention, in order to prevent the oxidation of Ti or the like as the adhesion layer, the upper layer of the interlayer insulating film is, for example, a silicon nitride film, or the lower layer of the metal-based material layer of, for example, Ti is used. As a result of forming the anti-oxidation layer by forming a metal having a standard generation energy larger than that, etc., even if a source gas such as WF ₆ enters at the time of film formation of Blk-W which is a refractory metal, Although TiF ₃ having a high vapor pressure may be formed, TiOF _x is not formed and peeling does not occur.

[0015]

EXAMPLES Specific examples of the present invention will be described below. However, as a matter of course, the present invention is not limited to the embodiments described below.

Example 1 In this example, an Al film having a larger standard production energy than Ti was formed as an antioxidant layer under a Ti film which is a metal layer (metal-based material layer) for connection formation. , Ti is prevented from being oxidized.

In this embodiment, a step of forming Ti as a connection forming metal layer 4 for obtaining an ohmic contact at a contact portion for forming an electrical connection, and a barrier metal 5 of TiN as an upper layer of the metal layer. The step of forming is performed to obtain the structure of FIG.
The high melting point metal 6, Blk-W, is formed by the VD method, and FIG.
When forming the wiring shown in (b), Al, which is a metal having a standard generation energy larger than that of the lower metal layer 4 under the lower metal layer 4 (in particular, Al-1 wt% Si is used in this embodiment).
Thus, the antioxidant layer 8 is formed.

More specifically, in this embodiment, the wiring was formed by the following steps. First, the lower layer wiring 1 to be connected
As a result, Al-1% Si (hereinafter referred to as AlSi) wiring is formed. An antireflection film TiON2 having a thickness of 30 nm is laminated on the lower layer wiring 1 (AlSi).

On top of this, plasma C is formed as an interlayer insulating film 3.
SiO ₂ of 600 nm is deposited as an interlayer insulating film 3 by the VD method under the following conditions. Gas system used: Tetraethoxysilane (TEOS) / O
₂ = 350/350 SCCM Gas pressure: 1.33 kPa Wafer temperature: 390 ° C. RF bias: 350 W Subsequently, a contact hole is formed by a normal lithography process and a dry etching process.

After that, first, AlSi is formed as an antioxidant layer 8.
A film of 30 nm is formed by the sputtering method. The film formation was performed by a sputtering device having a multi-chamber. A film was formed under the following conditions. Ar flow rate: 100 SCCM Gas pressure: 0.5 Pa Wafer temperature: 150 ° C. Target power: 4 kW

Subsequently, Ti is deposited as a metal layer 4 for connection to a thickness of 30 nm in another chamber without breaking the vacuum.
The film forming conditions were as follows. Ar flow rate: 100 SCCM Gas pressure: 0.5 Pa Wafer temperature: 150 ° C. Target power: 4 kW

By changing the film forming conditions in the same chamber, TiN is formed as the barrier metal 5 under the following conditions. As a result, the structure shown in FIG. 1A was obtained. Ar / N ₂ flow rate: 40/70 SCCM Gas pressure: 0.5 Pa Wafer temperature: 150 ° C. Target power: 5 kW

Next, in the single-wafer CVD apparatus, the refractory metal layer 6 is formed.
Then, Blk-W6 is deposited to obtain the structure shown in FIG. The film formation includes a nucleation process by SiH ₄ reduction and a W film formation process by H ₂ reduction. The conditions of each process were as follows. Nucleation gas system: WF ₆ / SiH ₄ = 7/5 SCCM gas pressure: 530 Pa wafer temperature: 450 ° C. W film forming gas system: WF ₆ / H ₂ = 95/550 SCCM gas pressure: 10 kPa wafer temperature: 450 ° C.

At this time, between the AlSi which is the anti-oxidation layer 8 and the SiO ₂ which is the interlayer insulating film 3, an A
l ₂ O ₃ 9 is formed, and TiO ₂ is formed as in the conventional example.
Is not formed. Therefore, even if WF ₆ enters, no volatile substance is generated and peeling does not occur.

After that, the refractory metal 6, W, is etched back, and Al wiring is formed thereon to obtain a wiring structure.

In this embodiment, A is used as the Ti oxidation preventing layer.
Although 1Si was used, pure Al or another Al alloy may be used as long as the standard generation energy is larger than Ti. Also, other metals may be used. In order to reduce the Si natural oxide film and make ohmic contact,
Further, since TiO ₂ is not formed, a material having a standard formation energy of negative and larger than Si and Al is preferable.

Example 2 In this example, as an upper layer of the interlayer insulating film SiO ₂ ,
P-Si which is an insulating layer containing no oxygen as an antioxidant layer
N is formed in advance, and TiO is produced by the reaction between Ti and SiO _2.
Prevents the formation of ₂ .

Description will be made with reference to FIG. In this embodiment, first, the Al-1% Si wiring which is the lower wiring 1 is formed. An antireflection film TiON2 having a thickness of 30 nm is laminated on the lower layer wiring 1 (AlSi). As the interlayer insulating film 3, SiO ₂ is deposited to 600 nm by plasma CVD under the following conditions under the following conditions. Gas system used: Tetraethoxysilane (TEOS) /
O ₂ = 350/350 SCCM Gas pressure: 1.33 kPa Wafer temperature: 390 ° C. RF bias: 350 W

Further, the antioxidant layer 1 is formed by the plasma CVD method.
0 is deposited to 50 nm of SiN. The conditions were as follows. Gas system: SiH ₄ / NH ₃ / N ₂ = 180/500 /
720SCCM Gas pressure: 40Pa Wafer temperature: 350 ° C

Subsequently, a contact hole is formed by an ordinary lithography process and a dry etching process. As a result, the structure shown in FIG. 2A is obtained.

In the following, as in Example 1, Ti as the connecting metal layer 4 and TiN as the barrier metal layer 5 were formed by the sputtering method, and Blk-W was used as the refractory metal 6 by CVD.
2B to obtain the structure of FIG. Also in this case, Ti as the metal layer 4 and SiO _{2 as the} interlayer insulating film 3
Since P-SiN that is the antioxidant layer 10 is sandwiched between them, TiO ₂ is not formed, and if W-
Even if F ₆ enters, no volatile substance is generated and peeling does not occur.

After that, the high melting point metal 6, Blk-W, may be etched back to form an Al wiring thereon. Also in this case, the antioxidant layer is not limited to P-SiN. As long as the insulating film does not contain oxygen, various materials such as SiC and SiCN can be used.

[0033]

As described above, according to the wiring forming method of the present invention, even if the wiring is formed of a refractory metal, film peeling or the like does not occur in the wiring forming process, and thus particles are generated. Inconvenience can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a step of a wiring forming method according to a first exemplary embodiment.

2A to 2C are diagrams showing steps of a wiring forming method according to a second embodiment.

FIG. 3 is a diagram showing a conventional technique.

FIG. 4 is a diagram showing a problem of the conventional technique.

[Explanation of symbols]

1 Lower Layer Wiring (AlSi) 2 Antireflection Film (TiON) 3 Interlayer Insulating Film (SiO ₂ ) 4 Metallic Material Layer (Ti) 5 Barrier Metal (TiN) 6 Refractory Metal (Blk-W) 8 Antioxidation Layer (Al) 10 Antioxidant layer (SiN)

Claims (3)

[Claims] 1. A step of forming a metal material layer for forming a connection on a contact portion for forming an electrical connection, a step of forming a barrier metal on an upper layer of the metal material layer, and a CVD method on the upper layer thereof. A wiring forming method for forming a refractory metal-based material, comprising forming an antioxidant layer under a lower metal-based material layer. 2. The wiring forming method according to claim 1, wherein a metal whose standard generation energy is larger than that of the lower metal-based material layer is used as the oxidation preventing layer. 3. The wiring forming method according to claim 1, wherein an insulating film containing no oxygen is used as the oxidation preventing layer.