JPH05152244A - Formation of wiring, and semiconductor device - Google Patents

Abstract

PURPOSE:To improve filling of aluminum by applying a coating to a contact hole to prevent oxidation of high-melting metal such as titanium, depositing high-melting metal such as titanium on the coating, and depositing aluminum by high-temperature sputtering. CONSTITUTION:A contact hole 2 is formed in a layer 12, and polycrystalline silicon is deposited in the contact hole to form a layer 3 for preventing oxidation of titanium. A titanium layer 4 is formed, and then an aluminum layer 5 is formed by high-temperature sputtering. As a result, an Al-Ti alloy layer is formed between the two layers 4 and 5, and this alloy layer reacts with the underlying polycrystalline silicon, so that an A4l-Ti-Si alloy layer 6 is finally formed. This prevents oxidation of titanium and improves to stabilize filling of aluminum.

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 and a semiconductor device. The present invention has a wiring forming method that provides a highly reliable connection with good filling characteristics when a wiring structure is formed by burying an aluminum-based material in a connection hole by high-temperature sputtering, and such a wiring structure. A semiconductor device is provided.

[0002]

2. Description of the Related Art In the field of electronic materials, for example, semiconductor devices such as LSIs, with the miniaturization of elements, a technique of embedding a metal, which is a wiring material, in fine connection holes has become important. As one of the metal burying techniques, burying an aluminum-based material by high temperature sputtering has been studied. This means is generally a technique for reflowing aluminum to fill the connection hole and flatten it by sputter-depositing aluminum while the substrate such as the substrate having the connection hole is heated to several 100 ° C. .. Recently, it has been reported that this technique can be used to fill a sub-half-micron connection hole, which is very promising.

In this type of conventional technique, as shown in FIG. 12, titanium 40 is usually used as an underlayer of aluminum 50.
Is used to improve the wettability between the aluminum 50 and the base to improve the embedding characteristics. In particular, the wettability of the aluminum 50 and the titanium 40 on the side wall of the connection hole 2 is important. If the wettability of this portion is good, the aluminum 50 will wet due to the interfacial reaction with the titanium 40, and the inside of the connection hole 2 will be promoted. , And good embedding can be achieved. In FIG. 12, 10 is a substrate, 11 is a lower layer wiring on the substrate 10, and aluminum 50 is embedded in the connection hole 2 formed in the interlayer film 12 formed on the substrate 10 to form the lower layer wiring 11 and the upper layer wiring (see FIG. (Not shown).

[0004]

[Problems to be Solved by the Invention]
Due to the influence of the material of the interlayer film 12 in which the connection hole 2 is formed,
There is a problem that the embedding characteristics may deteriorate.
For example, when the interlayer film 12 is a SiO ₂ -based material such as PSG (phosphorus-containing silicate glass), titanium 41 reacts with PSG as schematically shown by reference numeral 41 (particularly hatched) in FIG. Be oxidised. This deteriorates the interfacial reactivity between aluminum and titanium,
The wettability is deteriorated, the embeddability is deteriorated, and the hollow 21 shown in FIG.

As a means for solving the above problems, the present inventors have developed a means for preventing the oxidation of titanium by forming a side wall of SiO ₂ , SiN or the like in the connection hole.
This is an effective means. However, there is a problem that the process tends to be complicated.

[0006]

It is an object of the present invention to solve the above-mentioned problems and to provide a titanium-based high-melting-point metal-based material when a wiring is formed by embedding an aluminum-based material through a titanium-based high-melting-point metal-based material such as titanium. It is an object of the present invention to provide a technology capable of preventing oxidation and stabilizing and improving the burying property of an aluminum-based material to obtain a good wiring structure and easily performing this with a simple process.

[0007]

According to the invention of claim 1 of the present application, in a wiring forming method in which a connection hole formed on a substrate is filled with an aluminum material by high temperature sputtering to form a wiring, titanium is formed in the connection hole. A high-melting-point metal-based material anti-oxidation layer is formed, a titanium-based high-melting-point metal-based material is formed on the anti-oxidation layer, and high-temperature sputtering of an aluminum-based material is performed. In this way, the above-mentioned object is achieved.

The invention according to claim 2 of the present application is the wiring forming method according to claim 1 in which the titanium-based refractory metal-based material antioxidation layer is made of polycrystalline silicon or amorphous silicon. Is achieved.

According to the third aspect of the present invention, the aluminum-based material is embedded in the connection hole formed on the substrate by the high temperature sputtering through the aluminum-titanium-based high melting point metal-based material-silicon-based ternary alloy layer. A semiconductor device having a wiring structure, which achieves the above object.

According to a fourth aspect of the present invention, a silicide layer formed on a silicon substrate by a reaction between a silicon compound formed on the silicon substrate and a metallic material formed on the silicon compound is formed, A semiconductor device having a wiring structure in which a connection hole formed on a silicide layer is filled with an aluminum-based material by high-temperature sputtering via an aluminum-titanium-based refractory metal-based material-silicon-based ternary alloy layer. The object mentioned above is achieved.

In the present invention, the aluminum-based material is a material capable of forming aluminum wiring, and means pure aluminum and aluminum alloy,
Specifically, for example, Al, Al-Si, and Al-Si.
-Cu and other Al alloys can be mentioned.

In the present invention, the titanium-based high-melting-point metal-based material is a generic term for Ti and metals having the same properties as Ti, such as zirconium, and materials based on these.

The titanium-based high-melting-point metal-based material anti-oxidation film refers to a film which is formed in the lower layer or the upper layer of the above-mentioned material to prevent or suppress the oxidation of these materials.

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

[0015]

According to the wiring forming method of the present invention, since the aluminum-based material is formed on the titanium-based high melting point metal-based material by providing the anti-oxidation film, the oxidation of titanium is prevented.
As a result, the wettability between the aluminum-based material and titanium is not deteriorated, and a good and highly reliable buried connection structure can be obtained.

Further, the semiconductor device of the present invention is provided as a good and highly reliable semiconductor device by the wiring having the above-mentioned operation.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, as a matter of course, the present invention is not limited to the examples described below.

Example 1 This example illustrates the present invention by using a 16 megabit class SR.
The present invention is applied to a highly miniaturized and integrated semiconductor device such as AM.

As shown in FIG. 1, the wiring forming method according to the present embodiment is carried out by forming a contact hole 2 formed on a substrate 10 (here, a lower interlayer insulating film formed of PSG) into a contact hole 2 shown in FIG.
In the process shown in FIG. 3, the aluminum-based material 5 is embedded by high temperature sputtering to form wiring. First, as shown in FIG. 1, the titanium-based refractory metal-based material anti-oxidation layer 3 (hereinafter Ti) is formed in the connection hole 2. An antioxidant layer or the like), a titanium-based refractory metal material 4 (hereinafter also abbreviated as Ti-based material) is formed on the oxidation layer 3, and an aluminum-based material 5 High temperature sputtering is performed to obtain the structure shown in FIGS. 2 and 3.

As the titanium oxidation preventing layer 3, for example, polycrystalline silicon or amorphous silicon can be used. In this example, polycrystalline silicon was used.

In this example, more specifically, the wiring structure in the semiconductor device was formed by the following steps.

In this embodiment, a lower layer wiring 11 is formed on a PSG which is a base substrate 10 formed on a silicon semiconductor substrate or the like, a PSG is further formed thereon as an upper layer interlayer film 12, and the interlayer film 12 is formed. A via hole is formed for connecting the lower layer wiring 11 and an upper layer wiring to be formed later by opening the connection hole 2 in the.

In this embodiment, after the connection hole 2 is opened, Ti
Polycrystalline Si is deposited as the oxidation prevention layer 3. As a result, the structure shown in FIG. 1 is obtained. This is not particularly performed because it is not necessary to remove the polycrystalline Si layer at the bottom of the hole by etching back.

Subsequently, a Ti layer is formed as the titanium-based material 4 by the sputtering method, and further, as the aluminum-based material 5, Al (or Al-Si 1 wt% is formed by high-temperature sputtering.
An alloy such as an alloy) is formed. Here, at the time of Al high temperature sputtering, the reaction rapidly progresses at the Al / Ti interface, and the titanium-based material 4 becomes an Al—Ti alloy layer. FIG. 2 shows this state.

Further, this titanium-based material 4 (Al-Ti alloy layer) is a polycrystalline S that constitutes the Ti oxidation preventing layer 3 thereunder.
reacts with i, and finally an Al-based material and a Ti-based material,
Ternary alloy layer 6 with antioxidant layer material, here Al-Ti
-Form a ternary alloy layer of Si. This is shown in FIG.

Here, since the polycrystalline Si itself forming the anti-oxidation layer 3 has a high resistance, if it remains at the bottom of the connection hole 2 as it is, poor electrical continuity occurs, but if it is made into a ternary alloy as described above. The resistance value at the contact portion is reduced and the electrical continuity is improved.

In the above wiring formation, the Ti layer is formed of the interlayer film 12 such as SiO ₂ during the formation of Al which is the Al-based material 5.
Since the Ti layer which is the Ti-based material 4 is not oxidized by the reaction between Ti and SiO ₂ , good Al burying is possible.

Thereafter, after undergoing a process such as formation of a wiring pattern, Al sintering is performed. At this time, Al-Ti-Si
Si in the ternary alloy layer 6 is further diffused into Al, and the contact resistance is further reduced.

According to this embodiment, it is possible to obtain a wiring structure capable of making a good contact in a simple process and obtain a highly reliable semiconductor device.

Second Embodiment Next, a second embodiment will be described. Also in this embodiment, the present invention is applied to the same semiconductor device as that of the first embodiment.

In this embodiment, an insulating film which is an upper interlayer film 12 such as PSG is formed on the lower interlayer film 10 such as PSG which is a substrate, and the connection hole 2 is formed by an ordinary photoresist and RIE process. Open. Here, the film thickness of the interlayer film 12 was 500 nm, and the diameter of the connection hole 2 was 0.5 μm. As a result, the structure shown in FIG. 4 was obtained.

Next, as the Ti oxidation preventing layer 3, polycrystalline S is used.
i was formed into a film with a thickness of 500 nm to obtain the structure shown in FIG. Here L
P (Low pressure) -CVD method
Poly Si) was formed. The film forming conditions are shown below.

Next, a titanium-based material 4 of Ti and an aluminum-based material 5 of Al-Si are formed by a magnetron sputtering apparatus. First, Ti is formed to 100 nm by a normal sputtering method. As a result, the structure shown in FIG. 6 is obtained. After this, without exposing to the atmosphere, Al-S
i is sputtered at a high temperature of 800 nm. The composition of the target used at this time was Al-1 wt% Si, but other compositions, Al-Cu, pure Al, or the like may be used. The respective film forming conditions are shown below. Ti film forming conditions DC power 4 kW process gas Ar 100 SCCM sputtering pressure 0.4 Pa Substrate heating temperature 150 ° C. Al-Si film forming conditions DC power 10 kW film forming rate 0.6 μm / min Process gas Ar 100 SCCM sputtering pressure 0.4 Pa Substrate heating 500 At the time of ℃ Al sputtering, not only substrate heating but also substrate RF bias of about 400 V may be used together.

As shown in FIG. 6, since the Ti-based material 4 does not come into contact with the PSG forming the interlayer film 12, it is not oxidized by the reaction and Al-Si is well embedded. As a result, the structure shown in FIG. 7 is obtained. In addition, an Al—Ti—Si 3 composite metal 6 is formed at the bottom of the connection hole 2. Therefore, good contact characteristics can be obtained.

Next, the wiring layer made of the aluminum-based material 5 is etched into a wiring pattern by the ordinary photoresist and RIE process to form the overcoat 7. As the overcoat 7, plasma CVD is used here.
750 nm of SiN was formed by the method. As a result, the structure shown in FIG. 8 was obtained.

After that, Al sintering is performed. The conditions were 400 ° C. and 60 minutes. Sintering provides even better contact characteristics.

Third Embodiment Next, a third embodiment will be described with reference to FIGS. 9 and 10. In this embodiment, the formation of the insulating film as the upper interlayer film 12 such as PSG and the opening of the connection hole 2 are performed under the same conditions as in the first embodiment.

Next, as the Ti oxidation preventing layer 3, here, amorphous Si is deposited to a thickness of 50 nm by the sputtering method. As a result, the structure shown in FIG. 9 is obtained.

The film forming conditions for amorphous Si are shown below. DC power 0.5kW Process gas Ar 100SCCM Sputtering pressure 0.5Pa Substrate heating temperature 150 ° C

After that, Ti as a titanium-based material and Al-Si film as an aluminum-based material 5 are formed, a wiring pattern is processed, an overcoat 7 is formed, and an Al sinter is performed. All conditions are the same as those in the second embodiment. is there. As a result, the wiring structure shown in FIG. 10 was obtained.

In the case of this embodiment, the amorphous Si layer acts as the Ti oxidation preventing layer 3, and good Al burying and contact characteristics can be obtained as in the first and second embodiments.

Example 4 Reference is made to FIG. In each of the above-described embodiments, examples of so-called via holes connecting the lower layer wiring 11 and the upper layer wiring (not shown) are shown as the connection holes 2. However, these methods are used as contact holes on the Si diffusion layer of the silicon semiconductor substrate. Of course, the present invention can be applied to the present invention, and in the present embodiment, the present invention is embodied by using the silicon substrate 1 as a base and using the silicon diffusion layer as the lower wiring 11a.

In this embodiment, a titanium silicide layer (SITOX-TiSi _{2) is} previously formed as a silicide layer 8 on the Si diffusion layer (which forms the lower wiring 11a) in the following manner.
(Hereinafter, referred to as ") is formed, and then the connection hole 2 is opened.

That is, in the Cytox (SITOX) structure, 50 silicon compounds such as silicon oxide (which may be a thermal oxide film) or silicon nitride are formed on a silicon substrate.
~ 300Å film thickness, then Ti, Ni, C
A film is formed of a metal material such as o, and the silicon compound and the metal material are reacted with each other by heat treatment or other means.
By performing heat treatment at about 600 ° C. in an r atmosphere to cause reaction and silicidation, a silicide layer is obtained. The silicide layer thus obtained has a good function as a barrier metal. In this embodiment, the surface of the silicon substrate, which is the base 1, is converted to SiO ₂ , a Ti layer is formed, and a heat treatment is performed to form the silicide layer 8 made of TiSi ₂ .

SITOX-TiSi ₂ in this embodiment
The formation flow was as follows. Oxidation: 5 nm Ti sputtering film formation: 30 nm, RF bias 50
W primary anneal: 650 ° C., 30 sec, Ti selective etching in Ar gas H ₂ O ₂ : H ₂ O: NH ₄ OH = 2: 2: 1 (10 mi
n) Secondary annealing: 900 ° C., 30 sec, in N ₂ gas

After that, Al-Si was buried in the contact hole 2 which is a contact hole formed in the lower interlayer film 10a, in the same manner as in the above embodiment.

Even in the case of the structure of this example, good Al burying and contact characteristics can be obtained by the mechanism exactly the same as that of the above-mentioned example. In addition, S that is the silicide layer 8
Since ITOX-TiSi ₂ functions as a barrier metal, it is possible to prevent Al from penetrating into the Si diffusion layer which is the lower wiring 11a.

[0048]

As described above, according to the wiring forming method and the semiconductor device of the present invention, when the wiring is formed by embedding the aluminum material through the titanium-based refractory metal material such as titanium, titanium is used. It is possible to prevent oxidation of the high-melting-point metal-based material and stabilize and improve the burying characteristics of the aluminum-based material to obtain a good wiring structure. Moreover, this can be easily performed by a simple process. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a process of Example 1 (1).

FIG. 2 is a diagram showing a process of Example 1 (2).

FIG. 3 is a diagram showing a process of Example 1 (3).

FIG. 4 is a diagram showing a process of Example 2 (1).

FIG. 5 is a diagram showing a process of Example 2 (2).

FIG. 6 is a diagram showing a process of Example 2 (3).

FIG. 7 is a diagram showing a process of Example 2 (4).

FIG. 8 is a diagram showing a process of Example 2 (5).

FIG. 9 is a diagram showing a process of Example 3 (1).

FIG. 10 is a diagram showing the process of Example 3 (2).

FIG. 11 is a diagram showing a fourth embodiment.

FIG. 12 is a diagram showing a conventional technique.

FIG. 13 is a diagram showing a problem of the conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base (semiconductor substrate) 10 Base (lower interlayer film) 2 Connection hole 3 Titanium-based refractory metal-based material Antioxidant layer (polycrystalline S)
i, DOPOS, amorphous Si) 4 Titanium-based high melting point metal-based material 5 Aluminum-based material 6 Ternary alloy layer

Claims (4)

[Claims] 1. A wiring forming method in which an aluminum-based material is buried in a connection hole formed on a substrate by high temperature sputtering to form a wiring, and a titanium-based refractory metal-based material antioxidant layer is formed in the connection hole. A method for forming a wiring, comprising: forming a titanium-based high-melting-point metal-based material on the prevention layer, and further performing high-temperature sputtering of an aluminum-based material. 2. The wiring forming method according to claim 1, wherein the titanium-based refractory metal-based material antioxidant layer is made of polycrystalline silicon or amorphous silicon. 3. A semiconductor device having a wiring structure in which a connection hole formed on a substrate is filled with an aluminum-based material by high-temperature sputtering via an aluminum-titanium-based refractory metal-based material-silicon-based ternary alloy layer. 4. A connection hole formed on a silicon substrate by forming a silicide layer formed by a reaction between a silicon compound formed on the silicon substrate and a metal material formed on the silicon compound. A semiconductor device having a wiring structure in which an aluminum-based material is embedded by high-temperature sputtering via an aluminum-titanium-based refractory metal-based material-silicon-based ternary alloy layer.