JPH07130850A - Method for forming wiring - Google Patents

Abstract

PURPOSE:To control reaction which is generated simultaneously with nitriding without increasing the number of processes by forming a conductive material layer, a reaction prevention layer, and a barrier layer formation material on a semiconductor substrate and then performing a nitriding treatment for forming a barrier layer. CONSTITUTION:After, for example, elements are formed on an Si substrate 1, an interlayer insulation layer 13 such as SiO2 is formed and then a contact hole is opened as a connection hole 2. Then, a Ti barrier layer formation material layer 5, a TiN reaction prevention layer 4, and a Ti conductive material layer 3 are formed successively by a single wafer CVD magnetron sputter device. Then, nitriding annealing of the barrier layer formation material 5 is performed and then TiN barrier layer 51 is formed. Since the reaction prevention layer 4 exists as a silicide stop layer, a Ti Six layer 31 which is controlled to be properly thick is formed at the Ti/Si interface and a suffuciently thick TiN barrier layer 51 with nitriding Ti which is the barrier layer formation material layer 5 is formed on an upper layer.

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 method for forming a wiring having a structure having a wiring on a semiconductor substrate and a barrier layer that suppresses the interaction between the wiring and the underlying layer.

[0002]

2. Description of the Related Art Conventionally, a wiring having a structure having a wiring and a barrier layer for suppressing the interaction between the wiring and the underlying layer has been used on a semiconductor substrate. This is used, for example, in the form of forming a barrier metal layer for preventing the interaction between the Al-based material and the underlying Si when the Al-based wiring is formed on the Si semiconductor substrate.

With the miniaturization and integration of semiconductor devices, demands for the barrier layers as described above are becoming strict.

That is, as semiconductor devices, especially LSIs, become highly integrated and the internal wirings thereof become finer, the aspect ratios of various connection holes such as contact holes are increasing. Along with this, low resistance contact characteristics are demanded in high aspect ratio contact holes (contact holes etc.), and a method of forming a barrier layer having a high barrier property becomes important.

In the present specification, the barrier layer generally refers to a wiring and a layer having an action of suppressing the interaction between the wiring and the underlying layer. Typically, for example, an Al-based material (A
a barrier metal used to prevent penetration of Si, Al alloys, or alloys containing these as a main component) into a Si substrate, or to prevent Si from being eaten by WF ₆ when forming a CVD blanket W. it can.

As a method of forming a barrier layer such as a barrier metal, a method of forming a Ti film 30 and a TiN film 50 as shown in FIG. 11 by a sputtering method and a reactive sputtering method has been widely used. There is. In this case, TiN
In order to enhance the barrier property of the film 50, an annealing process is generally performed after the film formation. In FIG. 11, 1 is S
i semiconductor substrate, 11 is a Si diffusion layer, 12 is a LOCOS region (SiO ₂ ), 13 is a SiO ₂ interlayer insulating film, and 2 is a connection hole (contact hole).

On the other hand, various attempts have been made to form TiN by directly subjecting a sputtered Ti film to a nitriding annealing treatment. As shown in FIG. 12, Ti30 is formed into a film, and the Ti30 is nitrided to form TiN as shown in FIG.
This is a technique in which the film 32 is used as a barrier layer.

The TiN film obtained by directly nitriding Ti has a crystal orientation of TiN (111) as compared with a reactive sputtered TiN film or a film obtained by annealing the TiN film.
Since the orientation is strong, the Al film formed on the Al (1
11) It has the advantages of promoting the growth in the orientation and improving the reliability of the Al wiring. Further, in recent years, due to the further increase in the aspect ratio of the contact hole, the step coverage of the Ti or TiN film formed by the conventional sputtering method is insufficient. Therefore, the collimated sputtering method has been studied as a method for improving the step coverage. If this is the case, the sputtering speed is slow, and in this case, the throughput is reduced due to the decrease in the film formation speed. Here, the film formation rate of the reactive sputter TiN is 1 of the Ti film formation rate.
Since it is as slow as about ⅓ to ⅕, it is possible to perform T
Deposition of iN causes further reduction in throughput. On the other hand, the direct sputtering method and the method using the nitriding of Ti do not deposit TiN, and are therefore advantageous in terms of throughput especially when performing collimated sputtering.

In the direct nitriding annealing method for Ti, silicidation generally occurs at the Ti / Si interface at the time of annealing, and the TiSix conversion reaction proceeds. This T
Although iSix is useful for improving the contact property, there is a problem that it is difficult to control this TiSix formation reaction by the direct nitriding method. That is, in order to secure a sufficient barrier property, it is necessary to form the Ti 30 to a certain thickness in advance as shown in FIG. However, Ti
If 30 is thick, the TiSix conversion reaction proceeds too much during the nitriding annealing process, and the TiSix layer 31 is deeply formed as shown in FIG. 13, which may cause a problem that junction breakage occurs at the contact portion in the A portion of FIG. is there.
That is, the thicker the barrier metal is, the thicker the Ti30 is, the more silicidation occurs, which causes a problem.

As a means for preventing this, a method of performing Ti film formation and nitriding annealing in two steps has been studied (NAH Wils, et. Al., “STUDY”).
OFTiN FILMS FOR USE IM D
EEP SUBMICRON DEVICES "(Pro
ceeding of 1993 VMIC)). In this case, first, a thin Ti film is formed and an annealing process is performed to control the TiSix layer to an appropriate thickness in advance, and then a thick Ti film is formed and an annealing process is performed to form a thick TiN film. However, this conventional technique has a problem in that the number of process steps is increased.

The above-mentioned problem that other reactions may occur when the nitride film is formed is a problem that can occur when the barrier layer is formed by nitriding.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a wiring forming method in which a material that can be a barrier layer by nitriding Ti is directly nitrided to form a barrier layer, a reaction that occurs at the same time as nitriding, for example, It is an object of the present invention to provide a technique capable of controlling the silicidation reaction and not increasing the number of process steps.

[0013]

According to the invention of claim 1 of the present application, a wiring having a structure having a wiring and a barrier layer for suppressing the interaction between the wiring and the underlying layer is formed on a semiconductor substrate. A method, wherein the barrier layer is formed by nitriding a barrier layer-forming material that becomes a material exhibiting a barrier action by nitriding and has a possibility of reacting with the underlying layer,
A method for forming a wiring, comprising forming a conductive material layer, a reaction preventive layer, and a barrier layer forming material on a semiconductor substrate in this order, and then performing a nitriding treatment for forming a barrier layer. To do.

The invention according to claim 2 of the present application is the method for forming a wiring according to claim 1, characterized in that the material for forming the barrier layer is Ti, whereby the above object is achieved. Is.

The invention according to claim 3 of the present application is the method for forming a wiring according to claim 2, characterized in that the reaction preventing layer is a Ti compound, and thereby achieves the above object. is there.

The invention according to claim 4 of the present application is the method for forming a wiring according to claim 2, characterized in that the Ti compound is TiN, TiON, or TiOx. To do.

The invention of claim 5 of the present application is characterized in that the conductive material layer is formed on a silicon substrate, and is a layer made of a material serving as a silicidation supply source. The method for forming a wiring according to any one of items 1 to 4, which achieves the above object.

The structure of the present invention will be described below with reference to FIG. That is, the present invention preferably uses a conductive material layer T, which serves as a silicidation supply source such as Ti.
a reaction prevention layer such as a silicidation stop layer such as iN,
Step I of forming a barrier layer forming material that exhibits a barrier action by nitriding Ti on the semiconductor substrate in this order is performed, and then nitriding treatment for barrier layer formation (TiN conversion by nitriding Ti etc.) II.

The following is a description with reference to the examples of FIGS. 2 to 5 showing an embodiment of the present invention, which will be described later in detail.

The present invention is based on Si as illustrated in FIG.
A method of forming a wiring having a structure having a wiring 7 such as an Al wiring and a barrier layer 51 that suppresses interaction between the wiring 7 and a base (Si substrate or the like) thereof on a semiconductor substrate 1 such as a substrate. In the case where the barrier layer 51 is formed by nitriding a barrier layer forming material (for example, Ti) which becomes a material exhibiting a barrier action by nitriding and has a possibility of reacting with the underlying layer, the structure shown in FIG. Conductive material layer 3 (TiSix
And a reaction prevention layer 4 for improving conductivity.
(Silicidation prevention layer such as TiN) and the barrier layer forming material 5 (Ti etc.) are formed in this order on the semiconductor substrate 1 as shown in FIG. Thus, the barrier layer 51 (TiN or the like) is formed.

[0021]

According to the present invention, even when the barrier layer is formed by nitriding a barrier layer forming material which becomes a material exhibiting a barrier function by nitriding and has a possibility of reacting with the underlying layer, the reaction preventing layer is formed. Since the conductive material layer is formed, the barrier layer forming material does not directly react with the base even during nitriding, and even if there is a possibility of reaction, it is suppressed.
Therefore, the barrier layer can be formed while controlling such reaction. No extra complicated process is required.

[0022]

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. Although the following embodiments show an example in which the wiring is formed at the same time as filling the connection hole, the present invention is not limited to this, and the present invention can be applied to the case where the wiring is formed on the lower ground of the planar structure. Further, the following examples embody the present invention with respect to so-called contact holes for connecting between the underlying semiconductor substrate and wiring of metal or the like, but are similarly applicable to so-called via holes for connecting between lower layer-upper layer wiring. .

Example 1 In this example, the present invention is applied to the formation of Al-based wiring in the production of highly integrated Si-based LSI.

In this embodiment, in the method for manufacturing a barrier metal in a contact hole on a Si substrate, a structure of Ti for barrier metal formation / TiN layer for silicidation / Ti as conductive material / (substrate) is obtained in order from the upper layer. . This is a wiring forming method in which TiN is used as a barrier metal by performing nitriding annealing treatment after forming these films. When the above film formation structure is used, the lower layer Ti is converted to TiSix by the annealing treatment at the time of nitriding, which contributes to lower contact resistance, and the upper layer Ti is converted to TiN and becomes a barrier layer. Since the silicidation stop layer (TiN) is formed between the lower layer Ti and the upper layer Ti, only the lower layer Ti is converted to TiSix and does not extend to the upper layer Ti. Therefore, it is possible to form a thick TiN layer while controlling the film thickness of the TiSix layer well. Also, there is no special process increase.

This embodiment will be described in more detail below. Please refer to FIG. 2 to FIG.

Referring to FIG. After elements are formed on the Si substrate 1 by a normal LSI process (reference numeral 12
The interlayer insulating film 13 made of SiO ₂ or the like is formed, and a contact hole is formed as the connection hole 2 by an ordinary photoresist and RIE process. Here, the diameter of the contact hole was 0.4 μm and the depth was 0.8 μm.

Next, Ti5 / TiN4 / Ti3 was formed in order from the top of the drawing by a single wafer type DC magnetron sputtering apparatus. The lower layer Ti is the conductive material layer 3, the TiN is the reaction preventing layer 4 having a silicidation preventing action, and the upper layer T.
i is a barrier layer forming material 5 that exhibits a barrier action by nitriding, and these are formed on the semiconductor substrate 1 in this order.

Ti was formed by a normal sputtering method, and TiN was formed by a reactive sputtering method. The respective layers can be formed in different sputtering chambers, but can also be formed in one sputtering chamber by switching the process gas. The film thickness of each layer was 70 nm / 20 nm / 30 nm for the upper layer TiN / Ti / lower layer Ti. In this way, Ti, which is the barrier layer forming material 5, is formed thickly.

The film forming conditions for Ti and TiN are shown below. Ti film forming condition DC power 4 kW process gas Ar 100 SCCM pressure 0.4 Pa substrate temperature 150 ° C. TiN film forming condition DC power 5 kW process gas Ar / N ₂ 40/70 SCCM pressure 0.4 Pa substrate temperature 150 ° C.

Next, in order to form a barrier layer by nitriding, nitriding annealing of Ti, which is the barrier layer forming material 5, is performed in this example. Thereby, as shown in FIG. 4, a structure in which TiN was formed as the barrier layer 51 was obtained. Although the lamp heating method is used here for annealing, it is also possible to use the foreness annealing method or the like.

An example of heating conditions will be shown. Nitriding annealing conditions Temperature 800 ° C Time 60 sec. Gas atmosphere Oxygen may be added to the N ₂ gas atmosphere.

When obtaining the structure shown in FIG. 4, since TiN which is the reaction preventing layer 4 is used as the silicidation stop layer,
TiSix with controlled thickness at Ti / Si interface
The layer 31 is formed, and a sufficiently thick TiN barrier layer 51 in which Ti, which is the barrier layer forming material 5, is nitrided is formed on the upper layer.

Next, a plug is formed in the connection hole 2 (contact hole) or an Al wiring 7 is formed. Here, an example is shown in which the hole is filled with an Al-based material (especially Al-1 wt% Si) by Al high-temperature sputtering, and the Al wiring 7 is formed at the same time. In this case, in order to improve the wettability of the Al-based material, it is preferable to form a Ti layer on the base of the Al-based material.
nm. The film forming conditions are the same as above. Further, here, Al-1 wt% Si was used as a target material as an Al-based alloy.

The film forming conditions for this Al-based material are shown below. Al-Si film forming conditions Film thickness 600 nm Film forming rate 0.6 μm / min. DC power 10 kW Process gas Ar 100 SCCM Pressure 0.4 Pa Substrate temperature 500 ° C. A substrate bias of about RF450V may be applied during Al-Si film formation.

The structure after film formation is shown in FIG. An Al—Si—Ti alloy layer 71 is formed on the interface between the Al—Si and the Ti 6 which is the wiring 7.

Here, instead of performing the Al high temperature sputtering, it is also possible to perform the Al reflow method or the hole filling with the CVD tungsten. That is, various conventionally known wiring forming means can be used.

According to this embodiment, the following effects are brought about. Since the TiN is formed by nitriding Ti, the barrier layer 5
As No. 1, a TiN barrier metal having a strong TiN (111) orientation and excellent reliability can be formed. Since the lower layer Ti as the conductive material layer 3 can be independently formed with good controllability and can be thinned, for example, Ti at the Ti / Si interface is formed.
It is possible to satisfactorily control the thickness of the reaction film for Six conversion. In order to obtain the above effect, the number of steps is hardly increased. The through top at the time of forming the barrier layer 51 is improved.

Example 2 This example is a modification of Example 1, and the reaction preventive layer 4 as the silicidation stop layer is made of T instead of TiN.
This is an example using iON. In this embodiment, the structure corresponding to FIG. 3 showing the first embodiment is the structure shown in FIG. That is, the reactivity preventing layer 4 is formed of TiON which functions as a silicidation stop layer.

The film forming conditions of TiON in this case are shown below. TiON film forming conditions DC power 5 kW process gas Ar / N ₂ -6% O ₂ 40/70 SCC
M pressure 0.4Pa substrate temperature 150 ° C

Other than the above, the same effects as in Example 1 could be obtained by making the same as Example 1.

Example 3 In Example 1, all layers of Ti as the conductive material 3 and the barrier layer forming material 5 and TiN as the reaction preventing layer 4 were formed by the normal sputtering method. It is also possible to form a part of the layers by the collimator sputtering method. In this embodiment, the collimator sputtering method is adopted.

The film forming conditions in this embodiment are shown below. Ti film forming conditions DC power 8 kW process gas Ar 100 SCCM pressure 0.4 Pa substrate temperature 150 ° C. TiN film forming conditions DC power 8 kW process gas Ar / N ₂ 40/70 SCCM pressure 0.4 Pa substrate temperature 150 ° C.

Since the film thickness of TiN is as very thin as 20 nm, the decrease in throughput due to the low film forming rate of TiN reactive sputtering causes almost no problem.

Therefore, it can be seen from the present embodiment that the present invention is particularly effective when the collimator sputtering method is used.

Example 4 In Example 2, all layers of Ti as the conductive material 3 and the barrier layer forming material 5 and TiON as the reaction preventing layer 4 were formed by the normal sputtering method, but all of these layers were formed. It is also possible to form a part of the layers by the collimator sputtering method. In this embodiment, the collimator sputtering method is adopted.

The film forming conditions in this example are shown below. Ti film forming condition DC power 8 kW process gas Ar 100SCCM pressure 0.4 Pa substrate temperature 150 ° C. TiON film forming condition DC power 8 kW process gas Ar / N ₂ -6% O ₂ 40/70 SCC
M pressure 0.4Pa substrate temperature 150 ° C

As in Example 3, since the film thickness of TiON is as very thin as 20 nm, the decrease in throughput due to the low film formation rate of TiON reactive sputtering causes almost no problem, and the same as in Example 3. , Is advantageous in production.

Therefore, it can be seen from this example that the present invention is particularly effective when the collimator sputtering method is used.

Embodiment 5 In each of the embodiments described above, TiN or TiON is used as the silicidation stop layer which is the reaction prevention layer 4. TiO _x can also be used as the silicidation stop layer. This embodiment has this configuration, and the barrier metal film formation structure is Ti / T.
iO _x / Ti. This forming method is as follows.

As shown in FIG. 7, a single-wafer type DC magnetron sputtering apparatus was used to form Ti of 50 as the conductive material layer 3.
nm film is formed. The conditions are the same as in Example 1.

Next, this substrate is once exposed to the atmosphere, and as shown in FIG. 8, the Ti surface is oxidized to form a reaction preventing (silicidation preventing) layer 4 as a TiO _x layer.

Next, Ti is deposited to 70 nm as the barrier layer forming material 5 by the sputtering method again. As a result,
Get the structure of.

Next, nitriding annealing treatment is performed (FIG. 10).
The conditions are the same as in Example 1. Thereby, the barrier layer 51
As a result, the structure of FIG. 10 having a TiN layer is obtained.

In this embodiment, the TiO _x layer serves as a silicidation stop layer, and the same good Ti as in Embodiment 1 is obtained.
Six and TiN layers can be formed.

Here, as a method of forming a TiO _x layer on the surface of Ti, a method of introducing oxygen gas into the sputtering chamber after forming Ti instead of opening to the atmosphere is also possible.
Further, in the multi-chamber sputtering apparatus, it is also possible to provide one dedicated oxygen gas introducing chamber, carry the substrate into the oxygen gas introducing chamber after Ti film formation, and perform the oxidation treatment. As a result, it is not necessary to form a Ti film twice in the sputtering apparatus, and the throughput is improved.

[0056]

As described above, according to the present invention, in a wiring forming method in which a material that can form a barrier layer by nitriding Ti or the like is directly nitrided to form a barrier layer, a reaction that occurs at the same time as nitriding, that is, a silicidation reaction, is well controlled. It is possible to do so, and there is an effect that the number of process steps is not increased.

[Brief description of drawings]

FIG. 1 is a process drawing showing the constitution 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 steps of Example 1 in order. (2).

FIG. 4 is a sectional view showing the steps of Example 1 in order. (3).

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

FIG. 6 is a diagram showing a process of a second embodiment.

7A to 7C are sectional views showing steps of Example 5 in order. (1).

FIG. 8 is a sectional view showing the steps of Example 5 in order. (2).

FIG. 9 is a sectional view showing the steps of Example 5 in order. (3).

FIG. 10 is a sectional view showing the steps of Example 5 in order. (4).

FIG. 11 is a diagram showing a conventional technique (1).

FIG. 12 is a diagram showing a conventional technique (2) and its problems (1).

FIG. 13 is a diagram showing a conventional technique (2) and its problems. (2).

[Explanation of symbols]

I The conductive material layer (such as a material serving as a silicidation supply source such as Ti), the reaction preventing layer (such as a silicidation stop layer such as TiN), and the barrier layer forming material (such as Ti) on the semiconductor substrate in this order. Forming process II Nitriding treatment for barrier formation (Ti by nitriding Ti, etc.
N conversion step 1 Semiconductor substrate (Si substrate) 2 Connection hole (contact hole) 3 Conductive material layer (Ti) 4 Reaction prevention (silicidation prevention layer (TiN, TiO)
N) 5 Barrier layer forming material (Ti) 51 Barrier layer (TiN) 6 Layer for improving wettability of Al-based material (Ti) 7 Wiring (Al-based wiring)

Claims (5)

[Claims] 1. A method for forming a wiring having a structure having a wiring and a barrier layer for suppressing interaction between the wiring and an underlying layer on a semiconductor substrate, wherein the barrier layer exhibits a barrier function by nitriding. After forming the conductive material layer, the reaction preventive layer, and the barrier layer forming material in this order on the semiconductor substrate, when the barrier layer forming material that becomes the material and may react with the underlying layer is formed by nitriding A method for forming a wiring, comprising performing a nitriding treatment for forming a barrier layer. 2. The method for forming a wiring according to claim 1, wherein the barrier layer forming material is Ti. 3. The method of forming a wiring according to claim 2, wherein the reaction prevention layer is a Ti compound. 4. The method of forming a wiring according to claim 3, wherein the Ti compound is TiN, TiON, or TiOx. 5. The conductive material layer is formed on a silicon substrate and is a layer made of a material serving as a silicidation supply source. Wiring formation method.