JPH0817830A - Wiring structure - Google Patents

Abstract

PURPOSE:To obtain an excellently reliable wiring structure, in which reaction between wiring material and the material which comes in contact with the wiring material, is suppressed, having at least two layers of wiring material (Al material and the like) and the material (Ti material and the like) which comes in contact with the wiring material. CONSTITUTION:This wiring structure has two or more layers of a wiring material 26 and a material 25 which comes in contact with the wiring material 26. A substrate, with which the reaction between the wiring material, such as Al and the like and the material such as Ti and the like which comes in contact with the wiring material, is suppressed, is added to the wiring material. The additive is the substance in which the activation energy of the additive such as H, Sb, Co and the like and the Ti and the like is smaller than the activation energy of the Al, etc., and the Ti, etc., in the above-mentioned additive. The activation energy of the material of the additive and the Ti, etc., is smaller than the activation energy of the Al, etc., and the additive in the above-mentioned additive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure, and more particularly to a wiring structure having at least two layers of a wiring material and a material in contact with the wiring material. The present invention can be applied to various wiring structures of this kind, and can be preferably used as a wiring structure in the field of IC devices and other various semiconductor devices.

[0002]

2. Description of the Related Art For example, in the field of semiconductor devices, wiring widths have become finer with the miniaturization of elements. Along with this, it is necessary to form a wiring excellent in electromigration (EM) resistance.

For example, an Al-based wiring in a conventional semiconductor device, for example, a conventional Al-Si-based wiring is a material in which Cu is added to Al-Si in an amount of 0.5% to 2% for the purpose of enhancing electromigration resistance. Are used.

An example of applying this material to a MOSFET will be described below with reference to FIGS. 12 to 14.

(A) Referring to FIG. Element isolation region 12
(LOCOS-SiO ₂ ) and gate region are formed.
The gate region includes a gate material 15 (poly Si, polycide, etc.), a gate insulating film 17 (SiO ₂ ), and sidewalls 16a and 16b. That is, the LDD regions 14a, 1
Ion implantation for forming 4b is performed to form gate sidewall 1
6a and 16b are formed, and source / drain 13a and 13 are formed.
Ion implantation for forming b is performed.

(B) SOG, CVD-SiO ₂ , TEO
An interlayer insulating film 18 is formed of S-SiO ₂ or the like, and further,
The wiring connection hole 19 is formed as shown in FIG.

(C) Further, a TiN / Ti laminated film 20 is formed by a sputtering method. Further, a metal plug 21 (here, a W plug) is formed as a connection embedding material. After that, two layers of Al-Si-Cu / Ti are deposited on the entire surface by the sputtering method and patterned. Reference numeral 22 indicates a base Ti layer, 2
4 shows an upper layer Al (Al-Si-Cu) wiring. The wiring region is formed as described above, and the structure of FIG. 14 is obtained.

The reason why the wiring structure is a two-layer structure of Al--Si--Cu / Ti shown by reference numerals 24 and 22 is for the purpose of improving resistance to electromigration and stress migration (SM), and the upper Al system is used. Wiring 2
One reason is that the wiring is electrically connected as long as the base Ti22 is connected even if the wire 4 is disconnected.

Further, the reason why Si is contained in the main wiring Al is that, in the conventional method, a barrier metal such as TiN was not used and
In order to prevent Al from penetrating through the underlying Si when the 1-wiring and the underlying Si are in contact with each other, a level of Si in which Si dissolves was previously contained in Al. But,
The current wiring structure is W / TiN at the part in contact with the Si substrate.
Due to the / Ti contact, there is no need to include Si in Al.

Further, in the wiring using Al-Si-Cu, as shown in FIG. 15 (a), the Si nodules 27 are formed at a temperature associated with the subsequent film formation such as CVD. Therefore, when the interlayer film on the upper Al wiring 26 'is patterned by dry etching, the Si
l If exposed on the surface, exposed to fluorine plasma, Si
Is etched, which causes a problem of forming voids in the wiring. In FIG. 15, reference numeral 25 'is an Al-Ti alloy layer.

Therefore, in recent years, Al-Cu containing no Si has been used as a wiring material. However, by making the wiring structure an Al-Cu / Ti structure, at the time of final sintering (for example, 400 ° C.), Al
Since the Ti and the base Ti react remarkably, for example, as shown in FIG.
5 (b), the Al—Ti alloy layer 25 ′ becomes thicker as indicated by the symbol T, and as a result, the resistance of the wiring increases. On the other hand, in the conventional Al-Si-Cu system wiring, this problem is small. It is presumed that the reaction between the underlying Ti and Al is because the reaction of the Al—Ti alloying reaction is hindered by the influence of Si contained in the wiring, and thus the reaction is suppressed. It is considered that this is because Si reacts with Ti, and the amount of Ti that should react with Al decreases.

As described above, it is desired to configure the wiring material so that it does not contain Si. For example, it is necessary to solve the various problems described above, and a solution to that problem is desired.

There are many cases regarding the technique related to the laminated wiring structure in which it is desired to suppress the mutual reaction between the two, such as the above Al-based material and Ti material, but a means for fundamentally solving this has not been found. The current situation.

[0014]

It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a structure having at least two layers of a wiring material (Al-based material or the like) and a material (Ti-based material or the like) in contact with the wiring material. With respect to the wiring structure that it has, it is possible to suppress a reaction between the wiring material and the above-mentioned material that is in contact with the wiring material (for example, a reaction between an Al-based material and a Ti-based material), and thus to obtain a wiring structure with good reliability. I am trying.

[0015]

According to the invention of claim 1 of the present application, in a wiring structure having at least two layers of a wiring material and a material in contact with the wiring material, the wiring material is in contact with the wiring material. A substance that suppresses a reaction with a material is added to the wiring material, and the addition substance has an activation energy of the addition material and the material in contact with the wiring material,
A wiring structure characterized by being a substance having a smaller activation energy than that of the wiring material and the material in contact with the wiring material, thereby achieving the above object.

The invention of claim 2 of the present application relates to a wiring material,
In a wiring structure having a structure of at least two layers of a material in contact with the wiring material, a substance that suppresses a reaction between the wiring material and the material in contact with the wiring material is added to the wiring material, and the added substance is A wiring structure characterized in that the activation energy of the additive material and the material in contact with the wiring material is smaller than the activation energy of the wiring material and the additive material, thereby achieving the above object. To do.

In the invention of claim 3 of the present application, the wiring material is A
The wiring structure according to claim 1 or 2, wherein the wiring structure is an l-based material, and a material in contact with the wiring material is a Ti-based material.

According to the invention of claim 4 of the present application, the wiring material is A
3. The wiring structure according to claim 1, wherein the wiring structure is an l-based material, and a material in contact with the wiring material is W. The wiring structure according to claim 1 or 2, achieves the above object.

In the invention of claim 5 of the present application, the additive substance is
The wiring structure according to claim 3, wherein the wiring structure is H, Sb, or Co, thereby achieving the above object.

In the invention of claim 6 of the present application, the substance added to the Al-based material is such that the reaction temperature of the added substance and the Ti-based material is
The wiring structure according to claim 2 or 5, wherein the wiring structure is a substance that is lower than the reaction temperature of the Al-based material and the Ti-based material, thereby achieving the above object.

The invention of claim 7 of the present application is characterized in that the substance added to the Al-based material is a substance whose reaction temperature between the additive substance and the Ti-based material is lower than the reaction temperature between the additive substance and the Al-based material. The wiring structure according to claim 2, 5 or 6, which achieves the above object.

The invention according to claim 8 of the present application is the wiring structure according to claim 2, 5, 6 or 7, wherein the Al-based material is an Al alloy containing no Si. The above object is achieved.

The invention according to claim 9 of the present application is a wiring structure according to any one of claims 3 to 7, which is a wiring having an Al-based alloy material and an underlying Ti structure. The above object is achieved.

The invention according to claim 10 of the present application is the wiring structure according to claim 1 or 2, characterized in that the wiring material is a Cu-based material, and thereby achieves the above object. .

The invention according to claim 11 of the present application is the wiring structure according to claim 10, characterized in that the material in contact with the wiring material is a Ti-based material, and thereby achieves the above object. is there.

[0026]

According to the present invention, a wiring structure in which two kinds of materials are laminated, for example, an Al-based material / Ti-based material such as Al
Even if the alloy / Ti wiring structure is used, the wiring material (Al-based material) contains an additive substance that suppresses the reaction between the two materials, for example, the reaction between the underlying Ti and Al. A substance in which the activation energy of the additive substance and the material in contact with the wiring material is smaller than the activation energy of the wiring material and the material in contact with the wiring material, or the additive substance is the additive material and the wiring material. Since the activation energy of the material in contact with the wiring material is smaller than the activation energy of the wiring material and the additive substance, the reaction suppressing action can be effectively and reliably achieved.

That is, for example, if the structure is Al / Ti,
A substance that is more reactive with Ti than Al is reacted with Ti is contained.

For example, let X be a certain substance. The reaction temperature between X and Ti is a (or Gibbs free energy of reaction is E1). The reaction temperature of Al and Ti is b (or Gibbs free energy of reaction is E2), and X and A
Let l be the reaction temperature of c (or the Gibbs free energy of the reaction is E3), then a <b and a <c (or E3
> E1 and E3> E2).

It is difficult for X and Al to react with each other, and X and Ti
The reaction of occurs more violently than the reaction of Al and Ti.

FIG. 5 is a phase diagram of Al and Ti.
It can be seen that the reaction between Al and Ti easily proceeds.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. However, it should be understood that the present invention is not limited to the illustrated embodiments.

This embodiment shows an example in which the present invention is applied to a wiring structure of a MOS device, and is an example using an Al alloy containing about 1% hydrogen in Al. Ti reacts with hydrogen to form TiH _2, etc. This makes Al
The reaction with can be prevented.

6 and 7 are phase diagrams showing the phase states of Al and H of Ti, respectively. It can be seen that H significantly reacts with Ti.

In this example, a MOS transistor having the wiring structure according to the present invention was manufactured by the following steps (a) to (d). Please refer to FIG. 1 to FIG. (A) The element isolation region 12 and the gate regions 15 and 17 are formed on the Si (100) substrate 1. Further, LDD ion implantation is performed to form LDD regions 14a and 14b. Then, a Si oxide film is formed on the entire surface under the following conditions.

Condition gas SiH ₄ / O ₂ / N ₂ = 250/250/10
0 sccm temperature 420 ° C. pressure 13.3 Pa film thickness 0.25 μm

Further, the entire surface is etched back under the following conditions to form the sidewalls 16a and 16b on the gate 15. Condition gas C ₄ F ₈ = 50 sccm RF power 1200 W Pressure 2 Pa

Then, source / drain region formation 13
Impurity ion implantation for a and 13b is performed. Ion implantation was performed under the following conditions. Conditions N channel As 20 keV, 5e15 / cm ² P channel BF _{2 20} keV, 3e15 / cm ² The structure of FIG. 1 was obtained by the above.

(B) After that, the interlayer film 18 is formed. First, for example, a CVD oxide film using TEOS is formed under the following conditions. Condition gas TEOS = 50 sccm Pressure 40 Pa Temperature 720 ° C. Film thickness 400 nm

Further, for example, a film of BPSG or the like is formed under the following conditions. Thereby, the interlayer film 18 is formed. Condition gas SiH ₄ / PH ₃ / B ₂ H ₆ / O ₂ / N ₂ = 80/7/7/1000 / 32000sccm Temperature 400 ° C. Pressure 101325 Pa Film thickness 500 nm

After the resist pattern, the contact hole 19 is formed by dry etching under the following conditions. Condition gas C ₄ F ₈ = 50 sccm RF power 1200 W Pressure 2 Pa

Further, contact ion implantation is performed to form a junction region. Condition example N channel As 20 keV, 5e15 / cm ² P channel BF _{2 20} keV, 3e15 / cm ² Then, activation annealing is performed at 1050 ° C. for 5 seconds.

From the above, the structure shown in FIG. 2 is obtained.

(C) Next, contact embedding is performed. First, Ti20 and TiN20 'are formed. Ti is formed using a collimator. Ti film forming condition example power 4 kW film forming temperature 450 ° C. Ar = 100 sccm film thickness 30 nm pressure 0.47 Pa

Example of TiN film forming conditions Gas Ar / N ₂ = 40/70 sccm Power 5 kW Pressure 0.47 Pa Film thickness 10 nm

Further, CVDW is deposited as follows. First, SiH ₄ gas is first flowed under the following conditions. Then, W is formed by CVD under the following conditions. Condition gas WF ₆ / H ₂ = 95/550 sccm Temperature 450 ° C. Pressure 10640 Pa Film thickness 400 nm

After that, W is formed as the filling material 21 only in the connection hole by etching back under the following conditions. Condition gas SF ₆ = 50 sccm Microwave power 850 W RF power 150 W Pressure 1.33 Pa The structure shown in FIG.

(D) Al-H (1%)-Cu (0.5
%) 26 / Ti25 is formed by sputtering. First, Ti
The film 25 is formed under the following conditions. Ti film forming condition example Power 4 kW Film forming temperature 150 ° C. Ar = 100 sccm Film thickness 30 nm Pressure 0.47 Pa

Next, Al-H (1%)-Cu (0.5
%) 26 is formed. Film forming condition example Power 22.5 kW Film forming temperature 150 ° C. Ar = 40 sccm Film thickness 500 nm Pressure 0.47 Pa

After that, the Al—H—Cu / Ti wiring layer 26 is formed by resist patterning and dry etching. Condition gas BCl ₃ / Cl ₂ = 60 / 90s
ccm Microwave power 1000W RF power 50W Pressure 0.016Pa

Even after the subsequent heat treatment at about 400 ° C., Ti is hydrogenated, so that alloying of Al and Ti hardly occurs.

Thus, the wiring structure shown in FIG. 4 was obtained.

According to this embodiment, the following effects are exhibited. The alloying reaction between Al and Ti is suppressed. The reliability of wiring is improved. No Si noger is formed. Since it is not necessary to change the wiring structure only by changing the wiring material, it can be applied to the conventional process as it is, and the development cost can be suppressed.

Example 2 This example is an example in which Sb is contained in Al. T
The reaction of Al and Ti can be suppressed by forming iSb. 8 and 9 are phase diagrams of Al and Sb of each Ti. It can be seen that Ti has a high reactivity with Sb.

In this embodiment, only the Al alloy film forming material in the step (d) of the embodiment 1 is changed.

In this embodiment, in the step (d), Al
-Sb (1%)-Cu (0.5%) is deposited.

Others are the same as in the first embodiment. This embodiment also exhibits the same effect as that of the first embodiment.

Example 3 This example is an example in which Co is contained in Al. C
By making oTi, the reaction between Al and Ti can be prevented. 10 and 11 are phase diagrams of Al and Co of Ti, respectively. Ti has high reactivity with Co, and the same effect as when Sb is used can be obtained.

That is, the present embodiment is a modification of only the Al alloy film forming material in the alloy process of (d) of the first embodiment.

In this embodiment, in the step (d), Al-
Co (1%)-Cu (0.5%) is deposited.

Others are the same as in the first embodiment. This embodiment also exhibits the same effect as that of the first embodiment.

The present invention is not limited to the above-mentioned embodiments, and other structures may be adopted as long as the object can be achieved. For example, it can be applied to devices other than MOS devices (bipolar transistors, CCDs, etc.).

[0062]

As described above in detail, according to the present invention,
Regarding a wiring structure having at least two layers of a wiring material (Al-based material or the like) and a material (Ti-based material or the like) in contact with the wiring material, a reaction between the wiring material and the material in contact with the wiring material (for example, Al (Reaction between a Ti-based material and a Ti-based material) can be suppressed, and thus a highly reliable wiring structure can be obtained.

[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 the process of Example 1 (4).

FIG. 5 is a phase diagram of Al—Ti.

FIG. 6 is a phase diagram of Al—H.

FIG. 7 is a phase diagram of Ti—H.

FIG. 8 is a phase diagram of Al—Sb.

FIG. 9 is a phase diagram of Ti—Sb.

FIG. 10 is a phase diagram of Al—Co.

FIG. 11 is a phase diagram of Ti—Co.

FIG. 12 is a diagram showing a conventional technique (1).

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

FIG. 14 is a diagram showing a conventional technique (3).

FIG. 15 is a diagram showing a problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Si substrate 2 Element isolation region 13a, 13b Source / drain region 15 Gate wiring (WSi / DOPOS) 16a, 16b Gate sidewall 17 Gate oxide film 18 SiO ₂ 25 Ti 21 W plug 20, 21 TiN / Ti 26 Al alloy

Claims (11)

[Claims] 1. A wiring structure having at least two layers of a wiring material and a material in contact with the wiring material, wherein a substance that suppresses a reaction between the wiring material and the material in contact with the wiring material is added to the wiring material. In addition, the additive substance is a substance whose activation energy between the additive substance and the material in contact with the wiring material is smaller than the activation energy between the wiring material and the material in contact with the wiring material. Wiring structure. 2. In a wiring structure having at least two layers of a wiring material and a material in contact with the wiring material, a substance that suppresses a reaction between the wiring material and the material in contact with the wiring material is added to the wiring material. In addition, the wiring structure, wherein the additive substance is a substance whose activation energy between the additive substance and the material in contact with the wiring material is smaller than the activation energy between the wiring material and the additive substance. 3. The wiring structure according to claim 1, wherein the wiring material is an Al-based material, and the material in contact with the wiring material is a Ti-based material. 4. The wiring structure according to claim 1, wherein the wiring material is an Al-based material, and the material in contact with the wiring material is W. 5. The wiring structure according to claim 3, wherein the additive substance is H, Sb or Co. 6. The substance added to the Al-based material is a substance whose reaction temperature between the added substance and the Ti-based material is lower than the reaction temperature between the Al-based material and the Ti-based material.
Or the wiring structure according to 5. 7. The substance to be added to the Al-based material is a substance whose reaction temperature between the additive and Ti-based material is lower than the reaction temperature between the additive and Al-based material.
Or the wiring structure according to 6. 8. The wiring structure according to claim 2, 5, 6 or 7, wherein the Al-based material is an Al alloy containing no Si. 9. The wiring structure according to claim 3, which is a wiring having an Al-based alloy material and a base Ti structure. 10. The wiring structure according to claim 1, wherein the wiring material is a Cu-based material. 11. The wiring structure according to claim 10, wherein the material in contact with the wiring material is a Ti-based material.