JPH0685084A - Connection formation - Google Patents

Abstract

PURPOSE:To obtain a method of forming an aluminum-based material connecting construction having good wettability and high reliability by preventing oxidation of a backing portion of aluminum-based materials through the improvement and stabilization of embedding characteristics of the aluminum-based materials to fine connecting holes. CONSTITUTION:In a method of forming a connection by embedding an aluminum-based material 6 by high temperature spattering in a connecting hole 3 formed on a substrate 1, a Si layer 4 such as polysilicon or polysilicon introduced with impurities is formed as an oxidation prevention film in the connecting hole, and high temperature spattering with an aluminum-based material is performed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a connection. The present invention is, for example, various electronic materials (semiconductor devices, etc.)
It can be used as a connection forming technology. The present invention provides a connection forming method capable of obtaining a good connection characteristic and a highly reliable connection when an aluminum-based material is embedded in a connection hole by high-temperature sputtering to form a connection structure.

[0002]

2. Description of the Related Art In the field of electronic materials, for example, semiconductor devices such as LSI, with the miniaturization of elements, it is important to embed a metal, which is a wiring material, in a fine connection hole to form a connection structure. It is becoming. As one of the metal embedding techniques, embedding of an aluminum-based material by high temperature sputtering has been studied. In this means, generally, a substrate such as a substrate having a connection hole is heated to several hundreds of degrees Celsius to form an aluminum-based material by sputter deposition, so that the aluminum-based material is reflowed or close to a reflowed state (strictly speaking, strictly speaking). It is unclear, but it is considered that the same behavior as in the case of melting will be obtained), and then the connection hole is filled and flattened. Recently, it has been reported that this technique can be used to fill a sub-half-micron connection hole, which is very promising.

In the conventional aluminum connection forming method by high temperature sputtering, as shown in FIG. 23, titanium which also functions as a barrier metal as an underlayer of the aluminum-based material 6 (Al-1% Si alloy in the figure). 5 is used to improve the wettability between the aluminum-based material 6 and the base to improve the embedding characteristics. In particular, the wettability of the aluminum-based material 6 and the titanium 5 on the side wall of the connection hole 3 is important, and if the wettability of this part is good,
The aluminum-based material 6 advances by wetting due to the interfacial reaction with the titanium 5, and is drawn into the inside of the connection hole 3 so that good filling can be achieved. In FIG. 23, 1 is a substrate such as a substrate, and in the connection hole 3 formed in the interlayer film 2 formed on this substrate 1,
The aluminum-based material 6 is embedded to form a connection between a lower layer wiring, for example, a diffusion layer of the substrate and an upper layer wiring (not shown).

When embedding an aluminum-based material, it is known that if the base of the aluminum-based material contains oxygen, the wettability deteriorates and it is difficult to embed. For example, as an interlayer insulating film 2, SiO ₂ as shown in FIG. 23
In the case of using, when the substrate is heated during the film formation of the aluminum-based material, oxygen diffuses into the aluminum-based material base as schematically shown by the arrow in FIG. 23, and the wettability deteriorates. The same applies to the case where oxygen-containing TiON or the like is used as the barrier metal, for example, when a structure such as Ti / TiON / Al-Si is adopted, and the fine connection holes cannot be embedded, and an embedding failure as indicated by reference numeral 30 occurs. There was a problem of doing.

As a measure for solving the above problem, the present applicant previously proposed a structure in which the side wall of the connection hole is made of SiN. Although this is an excellent technique, SiN tends to have difficulty in embedding a fine connection hole because the side wall above the connection hole becomes thicker (poor step coverage).

Therefore, in the aluminum-based material embedding technique by high-temperature sputtering, it is possible to improve the overhang (the shape where the side wall above the connection hole becomes thicker and the connection hole becomes substantially smaller) and to satisfactorily fill the fine connection hole. There is a need for a way to do it.

[0007]

SUMMARY OF THE INVENTION The present invention was devised to meet the above demands, and also improves the embedding property of an aluminum-based material in a fine connection hole (for example, a connection hole of half micron or deep half micron or less). The present invention aims to provide a method for stabilizing the embedding property, preventing the base portion of the aluminum-based material from being oxidized, and improving its wettability, thereby forming a stable and highly reliable aluminum-based material connection structure. Is.

[0008]

According to the invention of claim 1 of the present application, in a connection forming method of forming a connection by embedding an aluminum material in a connection hole formed on a substrate by high temperature sputtering, a silicon is formed in the connection hole. A connection forming method is characterized in that a layer is formed to serve as an anti-oxidation film, and high temperature sputtering of an aluminum-based material is performed, thereby achieving the above object.

The invention according to claim 2 of the present application is the method for forming a connection according to claim 1, wherein the silicon layer is made of polycrystalline silicon, single crystal silicon, or amorphous silicon, and thereby achieves the above object. Is.

According to a third aspect of the present application, in a connection forming method of forming a connection by burying an aluminum material in a connection hole formed on a substrate by high temperature sputtering, an impurity-doped silicon layer is formed in the connection hole. As an antioxidant film,
This is a connection forming method characterized by performing high-temperature sputtering of an aluminum-based material, thereby achieving the above object.

The invention according to claim 4 of the present application is the method for forming a connection according to claim 3, wherein the impurity-doped silicon layer is made of impurity-doped polycrystalline silicon, single crystal silicon, or amorphous silicon. This achieves the above object.

The invention of claim 5 of the present application is the method of forming a connection according to claim 4, wherein the impurity-introduced silicon layer is made of phosphorus-doped polycrystalline silicon, and thereby achieves the above object. .

In the present invention, the aluminum-based material is a material capable of forming aluminum wiring, and refers to pure aluminum, aluminum alloy or the like, and specifically, for example, Al, Al-Si, Al. −
Si-Cu and other Al alloys can be mentioned.

In the present invention, the high temperature sputtering of an aluminum-based material refers to a technique for forming Al or the like by performing sputtering under heating. This high-temperature sputtering technique is described in detail in Koyama, Taguchi, and Sugano, "Embedding Al in high-aspect-ratio contact holes by high-temperature sputtering" (Proceedings of 40th Integrated Circuit Technology Symposium, pp. 19-24).

FIG. 1 shows an example of the configuration of the present invention, particularly the invention of claim 1.
Shown in. In the configuration example of FIG. 1, an aluminum-based material 6 is formed in a connection hole 3 formed on a substrate which is a substrate 1 by high temperature sputtering.
In a connection forming method of burying a metal to form a connection, a silicon layer 4 (here, a poly-Si layer) is formed in the connection hole 3 to form an antioxidant film (oxygen barrier), and high temperature sputtering of an aluminum-based material is performed to obtain a It is a thing. In this configuration example, Ti5 is interposed as a barrier metal between the silicon layer 4 and the aluminum-based material 6. In this configuration example,
The interlayer film 2 forming the connection hole 3 is made of SiO ₂ ,
The silicon layer 4 acts as an oxygen barrier, oxygen does not intrude from the interlayer film 2, the Al-Si alloy is not deteriorated by oxidization, and a good buried connection structure is obtained.

[0016]

According to the present invention, the CV is formed on the connection hole, especially on the side wall thereof.
Since silicon (Poly-Si or the like) is formed by D or the like in a sidewall shape, for example, such a silicon layer has a surface reaction rate-determining property, so that it has good step coverage and good wettability, and thus a good and stable aluminum-based material is used. Embed if possible. Also, S on the sidewall
The step coverage is better and the overhang shape is improved compared to the case where iN is added.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. Of course, the present invention is not limited to the embodiments.

Example 1 In this example, in the production of a highly miniaturized semiconductor device, Al-1 was used as an aluminum-based material in a fine connection hole.
The present invention is applied to the case where a% Si alloy is embedded. Especially, the diffusion layer and the first
Connection hole with layer Al wiring (called one contact)
An example executed for embedding is described.

As shown in FIG. 2, 6000 Å PSG is formed as an interlayer insulating film on the Si substrate 1.

After that, the connection hole 3 is opened by a photoresist process and an RIE process (FIG. 3). The connection hole 3 has a hole diameter of 0.5 μm, an interlayer film thickness of 0.6 μm, and an aspect ratio of 1.2.

Next, Ti5 is formed by a normal sputtering method.
1. TiON 52 is formed into 300Å and 700Å, respectively (FIG. 4).

Next, a Poly-Si layer 41 is formed.
That is, in order to form a sidewall-shaped silicon layer for suppressing the diffusion of oxygen from PSG and TiON to the Al underlayer, in this embodiment, Poly-Si is formed by 300Å by the CVD method (FIG. 5). When the thermal CVD method of silane is used, the deposition temperature is about 650 ° C.

The Poly-Si layer 41 is an anisotropic R
Etched back by IE and Pol only on the side wall of connection hole 3
A sidewall of y-Si is formed to be a silicon layer 4 for oxygen barrier (FIG. 6). Poly-Si is connection hole 3
This is because if it remains on the bottom surface of, the contact resistance will increase and conduction will not be established.

Next, the normal high temperature sputtering method (500 ° C.)
Due to Ti, Al-1% forming the aluminum-based material 6
Si and, if necessary, TiON (antireflection film) are formed to 300, 5000 and 300Å, respectively (FIG. 7).

According to this embodiment, the Al burying characteristic of the fine connection hole is improved, the Al burying characteristic is stabilized, the overhang shape of the Al underlayer is improved, and the Al underlayer Ti layer is oxidized. Can be prevented.

Embodiment 2 This embodiment is an example applied to a connection hole between Al and Al, and is a case where a connection between the first layer (lower layer) and the second layer (upper layer) Al wiring is formed.

As shown in FIG. 8, A is used as the lower Al wiring.
On the substrate made of 1-1% Si1a, SiN2a and SiO2 ₂ as an interlayer insulating film are formed at 500 Å and 6 respectively.
000Å form (Fig. 8).

After that, the connection hole 3 is opened by a photoresist process and an RIE process (FIG. 9). The connection hole 3 has a hole diameter of 0.5 μm, an interlayer film thickness of 0.65 μm, and an aspect ratio of 1.3.

Next, Poly-Si is deposited by CVD using a CVD method.
Form 0Å. This Poly-Si is etched back by anisotropic RIE so that only the sidewall of the contact hole 3 is Poly-S.
A sidewall of i is formed to be a silicon layer 4 (FIG. 10).

Next, Ti is deposited by a normal high temperature sputtering method.
5. Al-1% Si as the aluminum-based material 6 and Ti (500, 6000 (or 8,000), 500Å) are formed if necessary (FIG. 11).

This embodiment shows the same effect as that of the first embodiment.

Example 3 In this example, conductive impurity-introduced Poly-Si was used as the silicon layer, and removal of the silicon layer at the bottom of the contact hole was not necessary.

As shown in FIG. 12, an interlayer insulating film 2 (for example, PSG, SiO ₂ etc.) is formed on the Si substrate 1 by 6,000Å (FIG. 12).

By the photoresist process and the RIE process,
A connection hole 3 for making a connection with the diffusion layer of the Si substrate 1 is opened (FIG. 13). The connection hole 3 has a diameter of 0.5 μm, an interlayer film thickness of 0.6 μm, and an aspect ratio of 1.2.

Next, Ti51,
TiON52 (or TiN) 300 Å, 700 respectively
Å Form (Fig. 14).

Next, the interlayer insulating film 2 (PSG, Si
Oxygen diffuses from O ₂ ) or barrier metal (TiON 52), reacts with the Al underlayer to deteriorate the wettability, and in order to prevent the embedding characteristics from deteriorating, the poly-type with reduced resistance by doping with phosphorus or the like. 300 Si by CVD method
Å Create. Thereby, as shown in FIG. 15, a structure in which the silicon layer 4 having an oxygen barrier function is formed is obtained.

Next, the normal high temperature sputtering method (substrate temperature 5
Ti53 is formed at 300 Å at 00 ° C (Fig. 1).
6).

Next, as the aluminum-based material 6, Al-
1% Si (or Al-1% Si-0.5% Cu, etc.) and TiON as an antireflection film of 5,000 each
0,300Å is formed (FIG. 17, the antireflection film is not shown).

According to this embodiment, the Al burying characteristic of the fine connection hole is improved, the Al burying characteristic is stabilized, the underlayer of Al is prevented from being oxidized, the wettability with Al can be improved, and the sidewall of the connection hole is improved. It is also possible to omit the etch back process for leaving the silicon layer.

Example 4 An interlayer insulating film (eg PSG, SiO 2) is formed on the silicon substrate 1.
₂ etc.) to form 6,000Å (Fig. 18).

After that, the connection hole 3 is opened by a photoresist process and an RIE process (FIG. 19). The connection hole 3 has a diameter of 0.5 μm, an interlayer film thickness of 0.6 μm, and an aspect ratio of 1.2.

Next, Ti51,
TiON52 (or TiN) is formed to 300,700Å (FIG. 20).

Then, the interlayer insulating film 2 (PSG or Si
O _2, etc.) or the barrier oxygen diffuses from the metal (TiON52), reacts with the Al underlayer, the wettability is poor, in order to prevent the embedding characteristic deteriorates, the low-resistance by doping phosphorus or the like Poly -Si by CVD method 50
It is formed as 0Å to form the silicon layer 4 (FIG. 21).

Next, high temperature sputtering method (substrate temperature 500 ° C.)
5,000 Å of Al-1% Si as an aluminum-based material 6 directly on the Poly-Si forming the silicon layer 4 by
Formed (FIG. 22).

In this embodiment, the poly-Si having a low resistance is used.
Is thickened to form an oxygen barrier layer, and Poly-Si having good wettability of Al is directly used as a base.

In addition, this embodiment exhibits the same effect as that of the third embodiment.

[0047]

According to the present invention, the embedding characteristics of the aluminum-based material in the fine connection holes are also improved, the embedding characteristics are stabilized, oxidation of the underlying portion of the aluminum-based material is prevented, and its wettability is improved. A good and stable and highly reliable aluminum-based material connection structure can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a structural example of the present invention.

2A to 2C are sectional views showing steps of Example 1 in order (1).

3A to 3C are sectional views showing the steps of Example 1 in order (2).

4A to 4C are sectional views showing the steps of Example 1 in order (3).

5A to 5C are sectional views showing steps of Example 1 in order (4).

FIG. 6 is a sectional view showing the steps of Example 1 in order (5).

FIG. 7 is a sectional view showing the steps of Example 1 in order (6).

FIG. 8 is a sectional view showing the steps of Example 2 in order (1).

9A to 9C are sectional views showing the steps of Example 2 in order (2).

FIG. 10 is a sectional view showing the steps of Example 2 in order (3).

FIG. 11 is a sectional view showing the steps of Example 2 in order (4).

FIG. 12 is a sectional view showing the steps of Example 3 in order (1).

FIG. 13 is a sectional view sequentially showing the steps of Example 3 (2).

14A to 14C are sectional views showing the steps of Example 3 in order (3).

FIG. 15 is a cross-sectional view showing the process of Example 3 in order (4).

FIG. 16 is a sectional view showing the steps of the embodiment 3 in order (5).

FIG. 17 is a sectional view sequentially showing the steps of Example 3 (6).

FIG. 18 is a sectional view sequentially showing the steps of the fourth embodiment (1).

FIG. 19 is a sectional view sequentially showing the steps of the fourth embodiment (2).

20A to 20C are sectional views showing the steps of Example 4 in order (3).

FIG. 21 is a cross-sectional view showing the process of Example 4 in order (4).

22A to 22C are sectional views showing the steps of the fourth embodiment in order (5).

FIG. 23 is a diagram showing a conventional structure.

[Explanation of symbols]

 1 Base (Substrate) 2 Interlayer Film 3 Connection Hole 4 Silicon Layer 6 Aluminum Material

Claims (5)

[Claims] 1. A method of forming a connection in which a connection hole is formed on a substrate by burying an aluminum-based material in the connection hole by high-temperature sputtering to form a connection. A connection forming method characterized by performing sputtering. 2. The silicon layer comprises polycrystalline silicon, single crystal silicon, or amorphous silicon.
The method for forming a connection according to. 3. A connection forming method for forming a connection by embedding an aluminum-based material in a connection hole formed on a substrate by high-temperature sputtering to form a connection, in which an impurity-introduced silicon layer is formed as an antioxidant film, and an aluminum-based material is used. The method for forming a connection is characterized in that the high temperature sputtering is performed. 4. The connection forming method according to claim 3, wherein the impurity-doped silicon layer is made of impurity-doped polycrystalline silicon, single crystal silicon, or amorphous silicon. 5. The connection forming method according to claim 4, wherein the impurity-introduced silicon layer is composed of phosphorus-doped polycrystalline silicon.