JPH07130851A - Wiring formation method - Google Patents

Abstract

PURPOSE:To provide a method for forming the wiring of Al wiring where the filling capacity of a connection hole is improved while fully utilizing the advantage of Al wiring formation technology that the process is simple. CONSTITUTION:After an Al material thin-film formation step I is performed in advance, a step II of Al material to the surface inside a connection hole for covering is performed and a process III of filling the connection hole with Al material is properly performed by a high-temperature sputter, reflow, etc., to form Al wiring.

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,
In particular, the present invention relates to a wiring forming method including a step of filling a connection hole with an Al-based material. The present invention is
For example, it can be used as a technique for forming Al-based material wiring of various electronic materials (semiconductor devices and the like).

[0002]

2. Description of the Related Art In the technical field of forming Al-based wiring, the semiconductor device field is representative, and miniaturization and ultra-miniaturization are progressing in every field.

For example, in the case of a semiconductor integrated circuit device, L
With the high integration of SI, the wiring, especially the internal multi-layer wiring is being miniaturized / multi-layered. Along with this, a technique for burying a connection hole, particularly a technique for satisfactorily burying the connection hole with a wiring material, no matter how fine the connection hole is, becomes important. As such a technique for filling fine connection holes, an Al high temperature sputtering method, an Al reflow method (both of the concepts of Al include an Al alloy or an Al-based material containing Al or an aluminum alloy as a main component) and the like are considered. ing.

In the Al high temperature sputtering method, an Al-based material is heated to be in a fluidized state or in a state close to that to perform filling at the same time as sputtering.
This is a technique for filling and planarizing the Al-based material while flowing it by forming a film of the Al-based material in a state of being heated near the melting point of the l-based material. On the other hand, the Al reflow method is
After forming an Al-based material, it is melted and embedded. Typically, the Al-based material is once formed by room temperature sputtering, and then the substrate is heated to near the melting point of the Al-based material to form an Al-based material. This is a method of reflowing a system material to achieve embedding / planarization.

The Al embedding characteristic of the above technique is
It is known to depend on the base material of the system material. That is, as shown in FIG. 13, when a material 4 having excellent wettability with an Al-based material such as Ti is used as the base of the Al-based material 6, A
Good filling is achieved while the alloy layer 62 (Al—Ti alloy layer) is formed at the interface between the 1-based material 6 and Ti that is the material 4 having excellent wettability. In addition, in FIG. 12, 1
Is an Al wiring as a lower layer wiring, 2 is a connection hole, and 3 is an interlayer insulating film (SiO ₂ ).

[0006] These methods are advantageous in terms of process simplicity and the like as compared with methods using CVD tungsten or the like. On the other hand, however, it is not necessarily considered that the technique using CVD is superior to the technique using CVD in terms of the ability to fill the fine connection holes.

[0007] Against this background, it is desired to further improve the burying ability in the Al-based wiring forming technology. For example, the burying ability of the fine connection hole by Al high temperature sputtering or Al reflow is improved. It is eagerly awaited.

[0008]

It is an object of the present invention to solve the above-mentioned problems of the prior art and to make use of the advantage of the Al wiring forming technique that the process is simple, while improving the filling ability of the connection hole.
An object of the present invention is to provide a wiring forming method for system wiring.

[0009]

According to the invention of claim 1 of the present application, in a wiring forming method including a step of burying a connection hole with an Al-based material, a thin film of the Al-based material is formed in advance and heated. A wiring forming method including a step of fluidly coating an Al-based material forming the thin film on an inner surface of a connection hole, which achieves the above object.

According to the invention of claim 2 of the present application, the connection hole is made of Al.
The embedding step of embedding with an Al-based material is embedding of an Al-based material by high-temperature sputtering, and heating for forming a thin film of an Al-based material is by heating a substrate. A wiring forming method, which achieves the above object.

According to the invention of claim 3 of the present application, the connection hole is made of Al.
The wiring according to claim 1, wherein the embedding step of embedding the Al-based material is embedding of the Al-based material by reflow, and the heating for forming the thin film of the Al-based material is heating of the substrate. A forming method, which achieves the above object.

The present invention will be described below with reference to FIG. That is, in the present invention, after performing the Al-based material thin film forming step I in advance, the fluid coating step II of the Al-based material on the inner surface of the connection hole is performed, and the Al-based material of the connection hole is formed by high-temperature sputtering or reflow. An embedding step III with a material is performed.

[0013]

In the present invention, since the Al-based material thin film is formed in advance and the fluid coating process of the Al-based material on the inner surface of the connection hole is performed, a thin Al-based material film is formed on the inner surface of the connection hole. To be done. Such an Al-based material film has extremely good wettability with the same Al-based material. Therefore, when the step of burying the connection hole with the Al-based material by high-temperature sputtering, reflow, or the like is carried out, the Al-based material film has extremely good burying characteristics. Embedding of Al-based material can be realized.

[0014]

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 following examples.

Example 1 In this example, the present invention is applied to embedding a via hole at the time of forming an Al-based wiring in manufacturing a highly integrated Si-based LSI.

In this embodiment, a thin A of about 100 nm is filled in the contact hole filling by Al high temperature sputtering.
By coating an l-based material coating and subsequently heating the substrate, Al is fluidized inside the connection hole to form a film of an Al-based material, and the filling characteristics of the subsequent Al high-temperature sputtering are improved.

That is, this embodiment is an example in which the present invention is embodied by using the Al high temperature sputtering method for filling the connection hole. Please refer to FIG. 2 to FIG.

As shown in FIG. 2, after forming a lower layer wiring 1 such as an Al wiring, an interlayer insulating film 3 is formed of SiO ₂ or the like, and a connection hole 2 is opened by a usual photoresist process and RIE process. To do. The connection hole 2 of this embodiment is a so-called via hole for connecting the lower layer Al-based wiring and the upper layer Al-based wiring. In this embodiment, the interlayer film thickness is 800 nm and the connection hole diameter is 0.4 μm.

Next, a single-layer DC magnetron sputtering apparatus is used to form an underlying Ti film as a material 4 having excellent wettability with the Al-based material, and the structure shown in FIG. 3 is obtained.

The Ti film forming conditions are shown below. Ti film forming condition Film thickness 100 nm DC power 4 kW Process gas Ar 100 SCCM Pressure 0.4 Pa Substrate temperature 150 ° C.

In this embodiment, since the connection hole is a via hole, the base layer (material 4 having excellent wettability) is a Ti single layer. When applied to the contact hole connected to the diffusion layer of the Si substrate, a barrier metal such as TiN is usually required, and such an example will be described later in detail (Example 3).
reference).

Next, using the same single-wafer sputtering apparatus,
An Al-based material thin film 5 is formed by high-temperature sputter deposition of Al or Al alloy as the l-based material. Here, Al-1 wt% Si was used as the Al alloy. The Al-Si film formation was continuously performed in a vacuum after the Ti film formation. Al
The final film thickness of the system material film is 600 nm, but here, as the Al system material thin film 5, a film having a thickness of 100 nm is once formed without heating the substrate at a high temperature.

The film forming conditions for the Al-based material thin film 5 in this case are shown below. Al-Si film forming conditions (1) Film thickness 100 nm Film forming rate 1.2 μm / min. DC power 20kW Process gas Ar 100SCCM Pressure 0.4Pa No substrate heating (room temperature)

The shape of the Al-based material thin film 5 after film formation is shown in FIG. When the aspect ratio of the connection hole 2 is large as in this embodiment, almost no Al-Si, which is an Al-based material, can enter the inside of the hole as illustrated.

Next, in a vacuum, the substrate is heated continuously in order to cause the Al-Si which is the Al-based material to flow to the inner surface of the connection hole 2. The surface flow referred to here is a phenomenon in which an Al-based material (Al or Al alloy, etc.) that has gained energy by heating the substrate spreads over the surface of the underlayer by migrating (different from so-called solid phase diffusion, etc.). Things). Here, a gas heating method from the substrate surface was used as the heating method. Any other heating means can be adopted,
It is also possible to use a lamp heating method or the like.

The substrate heating conditions here are shown below. Al-Si surface diffusion heating condition Heating temperature 500
℃ heating time 30sec. Gas Ar 100SCCM Substrate back surface back pressure 8.0 Torr

By performing the above heating, as shown in FIG. 5, the Al-Si forming the Al-based material thin film 5 has the contact hole 2
Flows in the direction indicated by the arrow 52 to fluidly coat the inside of the connection hole 2 as indicated by reference numeral 51.

Finally, as shown in FIG. 6, Al-Si is further connected to the bottom of the connection hole 2. The Al-based material film formed in this manner is indicated by reference numeral 50.
At this time, the Al—Si—Ti ternary alloy layer 53 is formed at the interface between the Al—Si (film 50) and the Ti material 4.

The shape shown in FIG. 6 in which Al-Si which is an Al-based material is connected to the bottom of the connection hole 2 to form the film 50 makes subsequent filling by Al high temperature sputtering extremely easy.

Next, Al-Si as an Al-based material is continuously sputtered in vacuum to form a 500 nm thin film at high temperature, and the contact hole 2 is completely filled with Al-Si to obtain the structure shown in FIG. Reference numeral 6 indicates an Al-based material that is a filling material.

The conditions for this embedding are shown below. Al-Si film forming condition (2) Film thickness 500n
m deposition rate 0.6 μm / min. DC power 10kW Process gas Ar 100SCCM Pressure 0.4Pa Substrate temperature 500 ° C

During the film formation of Al-Si which is the Al-based material 6,
A substrate bias of about RF450V may be applied.

According to this embodiment, the following concrete effects can be obtained. The embedding characteristics of the Al-based material in Al high-temperature sputtering are improved. The Al high-temperature sputtering apparatus conventionally used can be used as it is.

Example 2 In this Example, the present invention is embodied in the case of forming an Al-based wiring similar to that in Example 1 and filling a contact hole by Al reflow. In this embodiment, 100n
A thin Al-based material having a thickness of about m is formed, and the substrate is subsequently heated to surface-flow Al inside the connection hole to form a film of the Al-based material and improve the filling characteristics of the subsequent Al reflow. did.

That is, this embodiment is an example in which the Al reflow method is used for filling the connection hole as described above.

The process up to the opening of the connection hole 2 and the Ti film formation, which is the film 4 excellent in wettability with the Al-based material by the single-wafer sputtering apparatus, was the same as in the first embodiment.

Next, as an Al-based material, Al-Si100n
m was sputter-deposited without heating the substrate at a high temperature to form an Al-based material thin film 5 to obtain the structure of FIG. This film forming condition is "Al-Si film forming condition (1)" shown in Example 1.
Is the same as.

Next, the substrate is heated continuously in a vacuum for diffusing the Al-based material thin film 5 made of Al--Si on the inner surface of the contact hole. The heating conditions are the same as in Example 1. As a result, the Al-based material film 50 is formed as shown in FIG.
Get the structure of. An Al—Si—Ti ternary alloy layer 53 is simultaneously formed at the interface between the film 50 (Al—Si), the Al-based material, and the material 4 (Ti) having excellent wettability, as in the above example. Also in the case of this embodiment, the Al seen in FIG.
The shape in which -Si is connected to the bottom of the connection hole 2 to form the film 50 makes subsequent filling by Al reflow very easy.

Next, Al-Si 500 nm, which is an Al-based material, is continuously sputter-deposited in a vacuum. As a result, the structure of FIG. 10 in which the Al-based material 6 is formed is obtained. The film forming conditions for this Al-based material 6 are shown below. Al-Si film forming conditions (3) Film thickness 500 nm Film forming rate 1.2 μm / min. DC power 20kW Process gas Ar 100SCCM Pressure 0.4Pa No substrate heating (room temperature)

Next, Al reflow heating is performed to fill the connection hole 2 to obtain the structure shown in FIG. Also in this case, the gas heating method from the back surface of the substrate is used, but a lamp heating method or the like can also be used.

The reflow conditions for the Al-based material here are shown below. Al-Si reflow heating condition Heating temperature 500
℃ heating time 120sec. Gas Ar 100SCCM Substrate back surface back pressure 8.0 Torr

According to this embodiment, the following concrete effects can be obtained. The Al burying property in Al reflow is improved. The Al reflow apparatus conventionally used can be used as it is.

Example 3 In this example, the present invention is applied to the case where the connection hole 2 is a contact hole connected to the diffusion layer 11 of the Si substrate 10. In Example 1, the connection is made as shown in FIG. Although a Ti layer single layer indicated by reference numeral 4 is formed in the hole 2, a barrier metal such as TiN is usually required in the case of this embodiment.

Therefore, as shown in FIG. 12, the film formation structure is Ti (100 nm) / TiN (70 nm) / Ti (30
nm). Here, the lower layer Ti41 functions as a conductive layer for obtaining a low contact resistance, and the upper layer Ti43 functions as a wet layer in which Al is embedded. TiN is the barrier layer 42. These layers may be continuously formed in a vacuum. For the purpose of strengthening the barrier property of TiN, T
When exposed to the atmosphere after iN film formation, further 500 ° C, 6
0 min. There is also a case where annealing treatment is performed to some extent.

The film forming conditions of TiN (barrier layer 42) in this embodiment are shown below. TiN film forming conditions Film thickness 70 nm DC power 5 kW Process gas Ar70 / N ₂ 100 SCCM Pressure 0.4 Pa Substrate temperature 150 ° C.

According to the present embodiment, the same effect as that of the first embodiment can be obtained also in filling the contact hole.

Embodiment 4 In this embodiment, embedding of an Al-based material by the Al reflow technique of Embodiment 2 is applied to embedding a contact hole as described in Embodiment 3.

According to the present embodiment, the same effect as that of the second embodiment can be obtained when the contact hole is filled.

[0049]

According to the present invention, there is provided a method of forming an Al-based wiring, which has an improved capability of burying a contact hole such as a contact hole or a via hole while taking advantage of the Al wiring forming technique which is simple in process. Could be provided.

[Brief description of drawings]

FIG. 1 is a flow diagram showing the steps of the 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 cross-sectional view showing a third embodiment.

FIG. 13 is a diagram showing a conventional technique and its problems.

[Explanation of symbols]

I Al-based material thin film deposition process II Flow coating process of Al-based material on inner surface of connection hole III Filling process of connection hole with Al-based material (high temperature sputtering or reflow) 1 Lower layer wiring (Al) 2 Connection hole (Via hole, contact hole) 3 Interlayer insulating film (SiO ₂ ) 4 Material excellent in wettability with Al-based material (Ti) 5 Al-based material thin film (Al-Si) 50 Al-based material film (Al-Si) 6 Al-based material (Al-Si)

Claims (3)

[Claims] 1. A wiring forming method comprising a step of burying a connection hole with an Al-based material, wherein a thin film of the Al-based material is formed in advance, and the Al-based material constituting the thin film is flowed to the inner surface of the connection hole by heating. A wiring forming method comprising a step of covering. 2. The embedding step of burying the connection hole with an Al-based material is burying of the Al-based material by high-temperature sputtering, and the heating for forming a thin film of the Al-based material is by heating the substrate. The wiring forming method according to claim 1, wherein the wiring is formed. 3. An embedding step of embedding the connection hole with an Al-based material is embedding of the Al-based material by reflow, and heating for forming a thin film of the Al-based material is by heating the substrate. The wiring forming method according to claim 1.