JP2000195820A - Forming method of metal nitride film and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce residual chlorine in a metal nitride film by a method, wherein a process for vapor-growing metallic nitride thin films with gas containing metallic halide gas and hydrogen nitride gas, then a process for irradiating a plasma produced from gas containing hydrogen gas and silane gas on the these films are repeated to obtain a metal nitride film of a desired film thickness. SOLUTION: A process for vapor-growing metal nitride thin films 6a1 to 6an with gas containing metallic halide gas and hydrogen nitride gas and a process for irradiating a plasma produced from a gas, containing hydrogen gas (H2) and silane gas (SiH4) on these thin films 6a1 to 6an are repeated to obtain a metal nitride film 6 of a desired film thickness. When a gas containing H2 gas and SiH4 gas is ionized, these gases collide with electrons in the plasma to produce an H radical (H*) and various Si active species in the plasma. From a these of the H* and the Si active species, the H* is diffused in the metallic nitride thin films containing halogen, is bonded to Cl which is bonded to Ti and is turned into HCl to separate from the plasma.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a metal nitride film and an electronic device using the same, and more particularly, to a method for forming a metal nitride film having a reduced halogen content, and using the same. The present invention relates to an electronic device having a low-resistance conductive layer.

[0002]

2. Description of the Related Art ULSI (Ultra Large Scale Integrate)
The design rules of semiconductor devices such as d-circuits have been miniaturized to the sub-quarter micron level, and multilayer wiring structures are being used frequently. Along with this high integration, for example, a logic unit and a DRAM (Dynamic Random Access Memory)
y) A system LSI device having a mixed section is drawing attention.

For example, a logic unit and a DRAM
In the manufacturing process of the semiconductor device in which the part is mixed,
A contact plug is buried in a contact hole formed facing a source / drain region formed in a semiconductor substrate, and a multi-layer wiring structure including an upper wiring and the like is employed. Such a contact plug structure is required to have low resistance and high heat resistance. This will be described with reference to FIG.

FIG. 8 is a schematic sectional view showing a contact portion between a contact plug of a highly integrated semiconductor device and a semiconductor substrate. That is, Salicide (SelfAligned Silicide) is added to the source / drain portion formed on the semiconductor substrate 1.
A refractory metal silicide layer 2 is formed in a self-aligned manner by a method, and a contact hole 4 facing the refractory metal silicide layer 2 is opened in the interlayer insulating film 3. When the contact plug is buried here, the metal film 5 and the metal nitride film 6 are formed thin to reduce the contact resistance. These are formed by sputtering or CVD (Chemical Vapor Depo
sition) method. In particular, the metal nitride film 6 is an important layer having a barrier property and an adhesive property, and a low pressure CVD method, that is, a thermal CVD method has been proposed for improving step coverage. In this method, a metal halide such as TiCl ₄ and NH ₃ is used as a raw material gas and a chemical reaction on the surface of a substrate to be processed is used. Filmed. Thereafter, a W (tungsten) layer 7 is also formed by the CVD method.
Are embedded to form a contact plug.

When a capacitor of a DRAM is formed, although it depends on its structure, a node electrode is formed of polycrystalline silicon or the like on this contact plug, and this node electrode is thermally oxidized to form a capacitor insulating film. Then, a capacitor electrode (both not shown) is formed. At the time of this thermal oxidation, a heat treatment at about 850 ° C. is required, and a thermal history of about 850 ° C. is also applied to the contact plug portion.

[0006]

As described above, in the step of forming the metal nitride film 6, for example, the TiN film by using the mixed gas of the metal halide and the hydrogen nitride gas,
Residual halogens such as TiCl _x are present in the N film.
The presence of this halogen near the contact interface causes a reduction in the reliability of the semiconductor device. Therefore, it is necessary to remove halogen from the TiN film after film formation.

As a method for desorbing residual chlorine from the TiN film, N
A method of performing a plasma treatment using a gas containing nitrogen such as H ₃ and a method of performing a heat treatment in a gas containing nitrogen similarly are disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 7-221048.
According to this method, the chlorine concentration in the TiN film can be reduced by about one digit immediately after the film formation.

According to the study of the present inventors, it was found that Ti
It is possible by this method to reduce Cl that has been incorporated in the N film in combination with Ti. However,
When the TiN film after the treatment is exposed to the atmosphere, the Ti portion bonded to Cl is recombined with oxygen in the air, and the desorbed C portion is removed.
Almost the same amount of oxygen (O) as 1 is taken in. This relationship is shown in [Table 1].

[0009]

[Table 1]

Returning to FIG. 8, when a thermal history of about 850 ° C. is applied to the contact plug in the DRAM capacitor forming step, O taken in the metal nitride film 6 diffuses into the lower metal film 5. Then, a high-resistance layer 8 containing a large amount of oxygen is newly formed at the interface between the metal film 5 and the refractory metal silicide layer 2, and the contact resistance is significantly increased.
Therefore, in the step of forming the metal nitride film 6, C
It is necessary to take care to prevent the incorporation of O together with the reduction of l.

Accordingly, an object of the present invention is to reduce a residual chlorine in a metal nitride film formed by a mixed gas containing a metal halide gas and a hydrogen nitride gas and to prevent the incorporation of oxygen into the metal nitride film. An object of the present invention is to provide a method for forming a film.

Another object of the present invention is to provide an electronic device such as a highly integrated semiconductor device, which includes a low-resistance and high-reliability metal nitride film as a conductive layer formed by such a method. That is.

[0013]

The present invention proposes to solve the above-mentioned problems. That is, in the method for forming a metal nitride film according to claim 1 of the present invention, a first step of vapor-phase growing a metal nitride thin film on a substrate to be processed by a mixed gas containing a metal halide gas and a hydrogen nitride gas. And a second step of subjecting the metal nitride thin film to plasma irradiation of a mixed gas containing a hydrogen gas and a silane-based gas as constituent elements, wherein the first step and the second step are performed in plural order. Repeated to obtain a metal nitride film having a desired film thickness.

According to a second aspect of the present invention, there is provided a method for forming a metal nitride thin film on a substrate to be processed in a vapor phase by using a mixed gas containing a metal halide gas and a hydrogen nitride gas. A second step of irradiating the metal nitride thin film with plasma of a processing gas containing hydrogen gas as a component, and a plasma irradiating the metal nitride thin film with a processing gas containing silane-based gas as a component. Third to apply
The first step, the second step, and the third step.
Is repeated a plurality of times in this order to obtain a metal nitride film having a desired film thickness.

According to a third aspect of the present invention, there is provided a method for forming a metal nitride thin film on a substrate to be processed in a vapor phase by using a mixed gas containing a metal halide gas and a hydrogen nitride gas. And a second step of subjecting the metal nitride thin film to plasma irradiation of a mixed gas containing hydrogen gas and a gas containing nitrogen as constituent elements. The first step and the second step It is characterized in that a metal nitride film having a desired film thickness is obtained by repeating a plurality of times in order.

According to a fourth aspect of the present invention, there is provided a method for forming a metal nitride thin film on a substrate to be processed in a vapor phase using a mixed gas containing a metal halide gas and a hydrogen nitride gas. A second step of irradiating the metal nitride thin film with a plasma of a processing gas containing hydrogen gas as a component, and a plasma of the processing gas containing a nitrogen-containing gas as a component of the metal nitride thin film. A third step of irradiating is performed, and the first step, the second step, and the third step are repeated in this order a plurality of times to obtain a metal nitride film having a desired film thickness.

In any of the methods for forming a metal nitride film, the thickness of the metal nitride thin film is preferably 30 nm or less, more preferably 20 nm or less. When the thickness of the metal nitride thin film exceeds 30 nm, the effects of dechlorination and oxidation prevention are reduced. The lower limit of the film thickness of the metal nitride thin film is not particularly limited, and may be a film thickness of a monoatomic layer, but from the viewpoint of the film formation throughput,
About 5 nm is a practical lower limit.

In any method of forming a metal nitride film, the plasma irradiation may be performed by adding a rare gas such as Ar for stabilizing the plasma.

An electronic device according to the present invention includes a metal nitride film formed by any one of the above-described methods for forming a metal nitride film as a part of a conductive layer.

[Operation] When a mixed gas containing H ₂ and SiH ₄ is dissociated by discharge and turned into plasma, these gases collide with electrons in the plasma and cause H radicals,
And Si active species such as Si radicals, SiH radicals, SiH ₂ radicals, and SiH ₃ radicals are generated. Of these, H radicals diffuse into the metal nitride thin film containing halogen and combine with Cl which is combined with Ti to form H radical.
It becomes Cl and desorbs. Since the metal nitride thin film has a thickness of 30 nm or less, H radicals can be diffused throughout the entire thickness of the metal nitride thin film to dechlorinate it.

The Ti metal portion from which Cl has been eliminated combines with Si active species such as Si radicals, SiH radicals, SiH ₂ radicals, and SiH ₃ radicals to form a Ti—Si—N metal nitride thin film. Ti-Si-N-based metal nitride thin film is a grain boundary of TiN metal nitride.
Has a structure in which Si atoms are clogged (Stuffing) or precipitated. Therefore, it is possible to prevent grain boundary diffusion of a metal that easily diffuses, such as Cu, and has high barrier properties. Irradiation with H radicals and irradiation with Si active species such as Si radicals, SiH radicals, SiH ₂ radicals, and SiH ₃ radicals may be performed at the same time, or irradiation with Si active species may be performed subsequent to H radical irradiation. .

After the formation of the metal nitride thin film,
By irradiating plasma of active species and Si active species and repeating these, a metal nitride film having a thickness of, for example, 50 nm, which is required as a barrier layer or an adhesion layer, in this case, a Ti-Si-N film is formed. Can be formed. This metal nitride film has a reduced residual halogen and forms a low-resistance and highly reliable contact plug without being oxidized even in a subsequent heat treatment step or without forming a high-resistance layer. be able to.

On the other hand, when a mixed gas containing hydrogen gas and nitrogen is discharged and dissociated into plasma, these gases collide with electrons in the plasma, and generate H radicals in the plasma.
N ₂ radical, NH radical, and N ₂ ⁺ ion, N
H ⁺ ions and the like (N active species) are generated. Of these,
The H radical diffuses into the halogen-containing metal nitride thin film, combines with Cl which is combined with Ti, becomes HCl, and is eliminated. Since the metal nitride thin film has a thickness of 30 nm or less, H radicals can be diffused throughout the entire thickness of the metal nitride thin film to dechlorinate it.

The Ti metal portion from which Cl has been removed binds to N ₂ radicals, NH radicals, and these ions,
It becomes a TiN-based metal nitride thin film. Irradiation of H radicals,
And N ₂ radical, NH radical, and irradiation of such these ions may be subjected simultaneously, followed by irradiation of the H radical, N ₂ radical, NH radical, and may be irradiated with these ions.

After forming the metal nitride thin film,
By irradiating plasma of active species and N-active species and repeating these, it is possible to form a metal nitride film having a thickness of, for example, 50 nm, which is required as a barrier layer or an adhesion layer, in this case, a TiN film. it can. This metal nitride film has a reduced residual halogen, does not oxidize even in the subsequent heat treatment step, and therefore does not form a high-resistance layer, thereby forming a low-resistance and highly reliable contact plug. can do.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

First, a plasma processing apparatus employed in the metal nitride film forming method of the present invention will be described with reference to FIG.

FIG. 7 is a schematic sectional view showing a parallel plate type plasma processing apparatus employed in the metal nitride film forming method of the present invention. That is, the stage 12 on which the substrate 11 to be processed is placed is disposed in the processing chamber 10. The stage 12 is equipped with a temperature control unit and a holding unit (both not shown) for the substrate 11 to be processed. Opposite to the substrate stage 12, a gas shower head 13 for uniformly supplying a processing gas toward the substrate 11 to be processed is provided. The gas shower head 13 has an RF power source 1
4 are connected intermittently. Further, a gas introduction unit 15 is connected to the gas shower head 13. The gas introduction section 15 is composed of a plurality of types of gas introduction pipes, each of which can be selectively used alone or in combination with a metal halide gas, a hydrogen nitride gas, a silane-based gas, a hydrogen gas, a nitrogen gas, a rare gas, or the like. Can be introduced.

According to the plasma processing apparatus shown in FIG. 7, low-pressure CVD, that is, thermal CVD without plasma excitation
And the plasma processing can be continuously performed in the same processing chamber 10. The plasma processing apparatus in FIG. 7 is an example, and may be a continuous processing apparatus in which a low-pressure CVD apparatus and a plasma processing apparatus are separately configured and both are connected by a gate valve. As a plasma generation method, a magnetron type parallel plate type plasma processing apparatus or an apparatus capable of obtaining higher density plasma may be used in addition to the method using a parallel plate type capacitor electrode. As such a plasma processing apparatus, ECR (Electron Cyclotron Resonance)
Plasma processing equipment, ICP (Inductively Coupled Plas)
ma) A processing device, a helicon wave plasma processing device and the like are exemplified. Each of the plasma processing apparatuses is configured to be able to serve as both a low-pressure CVD apparatus and a plasma processing apparatus by switching on and off a plasma generation power supply.

Now, examples of the metal halide gas include metal fluoride, metal chloride, metal bromide and metal iodide. As the metal, a high melting point metal such as Ti, Ta, or W is desirable. As an example, TiCl ₄ (mp
= −25 ° C., bp = 136 ° C.), TiBr ₄ (mp = 3
9 ° C., bp = 230 ° C.), TiI ₄ (mp = 130 ° C.,
bp = 377.1 ° C.), WF ₆ (mp = 2.5 ° C., bp
= 17.5 ° C) or TaF ₅ (mp = 96.8 ° C,
bp = 229.5 ° C.). Of these, T
A metal compound that is liquid at room temperature, such as iCl ₄ , can be preferably used because of easy handling. These metal compounds may be vaporized by a known heating bubbling method, burning method, or the like, and introduced into a CVD chamber via a heating pipe.

Next, examples of the hydrogen nitride gas used in the present invention include NH ₃ and N ₂ H ₄ .
These may be used alone or as a mixture.

The silane-based gas may be a higher-order silane gas such as Si ₂ H ₆ or Si ₃ H ₈ in addition to SiH ₄ .

The metal nitride films to which the present invention is applied include Ti-Si-N, Ta-Si-N, W-Si-N,
TiN, TaN, Ta ₂ N, WN, W ₂ N, etc. are exemplified. These metal nitride films may be used in a single layer or in multiple layers. Further, it may be used by being laminated with a metal film such as Ti, Ta or W.

The step of forming the metal nitride thin film may be a low pressure CVD method similar to the conventional method. In this case, the temperature of the substrate to be processed is selected to be 600 ° C. or higher. When it is desired to lower the temperature of the substrate to be processed, a plasma CVD method may be used. In this case, the temperature of the substrate to be processed is about 200 ° C. to 400 ° C. However, the difference from the conventional method in the step of forming the metal nitride thin film in the present invention is the thickness, which is 30 nm.
Below, preferably, a film thickness of 20 nm or less is selected. The reason is as described above. By repeating the formation of the metal nitride thin film and the plasma treatment a plurality of times, a metal nitride film having a desired film thickness is formed.

Next, an outline of the method for forming a metal nitride film of the present invention will be described with reference to the schematic sectional views of FIGS.

FIG. 1A is an example of a sample to which the metal nitride film forming method of the present invention is applied, in which a metal film 5 is formed on a substrate 11 to be processed. The substrate 11 to be processed is, for example, an impurity diffusion layer of a highly integrated semiconductor device, and the metal film 5 is, for example, a contact metal or a Ti film as an adhesion layer. The metal film 5 is formed by an ionization sputtering method, a plasma CVD method, or the like.

[0037] FIG. 1 (b): forming a metal nitride thin film 6a ₁ by the low pressure CVD method. Metal nitride films 6a ₁ is made of, for example, a TiN film, its thickness is 30nm or less. The low-pressure CVD condition employs a temperature of the substrate to be processed around 650 ° C. by a mixed gas of TiCl ₄ and NH ₃ and N ₂ added as necessary.

[0038] FIG. 1 (c): H in the metal nitride thin film 6a ₁
Plasma irradiation is performed using a mixed gas of ₂ and Ar. The resulting H ^* (H radicals) diffuse the metal nitride thin film 6a ₁ medium is HCl next elimination reacts with Cl bound with Ti.

FIG. 1 (d): The metal nitride thin film 6 a ₁ from which Cl has been desorbed is subjected to plasma irradiation with a mixed gas of SiH ₄ and Ar. Si ^* radicals generated in the plasma,
SiH ^* radical, SiH ₂ ^* radical or SiH
₃ ^* Metal nitride thin film 6 by Si active species such as radical
a The Ti portion from which Cl has been eliminated in a ₁ is silicided,
It becomes TiSiN. Thereby, the metal nitride thin film 6
with residual chlorine in a _1, Ti metal unbound also be sufficiently nitrided.

[0040] In forming the metal nitride film 6 to a thickness of a desired, FIG 1 (b) ~ Figure 1 6a ₁ by repeating the steps (d), 6a _2, lamination of · · · 6a _n Structure.

The step shown in FIG. 1C and the plasma irradiation step shown in FIG. 1D may be performed simultaneously. Again, in this case,
With residual chlorine of the metal nitride films 6a in _1, Ti metal unbound is sufficiently nitrided.

FIG. 2 is a schematic sectional view showing another method for forming a metal nitride film according to the present invention.

FIG. 2A is an example of a sample to which the method for forming a metal nitride film of the present invention is applied, in which a metal film 5 is formed on a substrate 11 to be processed. The substrate 11 to be processed is, for example, an impurity diffusion layer of a highly integrated semiconductor device, and the metal film 5 is, for example, a contact metal or a Ti film as an adhesion layer. The metal film 5 is formed by an ionization sputtering method, a plasma CVD method, or the like.

[0044] FIG. 2 (b): forming a metal nitride thin film 6a ₁ by the low pressure CVD method. Metal nitride films 6a ₁ is made of, for example, a TiN film, its thickness is 30nm or less, preferably 20nm or less. The reduced pressure CVD conditions are TiC
A temperature of around 650 ° C. is employed depending on the mixed gas of l ₄ and NH ₃ and N ₂ .

FIG. 2C: The metal nitride thin film 6 a ₁ has H
Plasma irradiation is performed using a mixed gas of ₂ and Ar.
The generated H ^* (H radical) is converted into a metal nitride thin film 6a ₁
Diffuses in the reaction and reacts with Cl which is bonded to Ti to form HCl.
And desorb.

[0046] FIG. 2 (d): Cl in the metal nitride thin film 6a ₁ desorbed, subjected to plasma irradiation with a mixed gas of N ₂ and Ar. Radicals such as N ₂ ^* and NH ^* generated in the plasma and ions such as N ₂ ⁺ and NH ⁺ cause nitridation of the Ti portion of the metal nitride thin film 6 a ₁ from which Cl has been eliminated. Thus, the residual chlorine in the metal nitride thin film 6a in _1, Ti metal unbound also be sufficiently nitrided.

[0047] In forming the metal nitride film 6 to a thickness of a desired, FIG 2 (b) ~ Figure 2 6a ₁ by repeating the steps (d), 6a _2, lamination of · · · 6a _n Structure.

The step shown in FIG. 2C and the plasma irradiation step shown in FIG. 2D may be performed simultaneously. Again, in this case,
With residual chlorine of the metal nitride films 6a in _1, Ti metal unbound is sufficiently nitrided.

As described above, in any of the methods for forming a metal nitride film, the residual chlorine in the metal nitride film is reduced, and the unbonded metal in the portion from which the chlorine has been removed is immediately silicided or formed. Nitrided. Therefore, even when the metal nitride film is exposed to the atmosphere, oxidation is prevented.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for forming a metal nitride film according to the present invention will be described below. As an example of an electronic device, a contact hole formed in a highly integrated semiconductor device is buried with a conductive layer including a metal nitride film. Examples of using a plug are shown in FIGS.
This will be described in more detail with reference to FIG. However, the present invention is not limited to these examples.

[Embodiment 1] In this embodiment, a metal nitride film made of TiSi-N is formed by the parallel plate type plasma processing apparatus shown in FIG.

FIG. 3A: The substrate to be processed employed in this embodiment has a refractory metal silicide layer 2 and an interlayer insulating film 3 formed on a semiconductor substrate 1 as shown here. A conformal metal film 5 including the inside of the contact hole 4 opened in the film 3 is formed.

The semiconductor substrate 1 is made of a silicon substrate and has an impurity diffusion layer (not shown), that is, a source / drain region of a MOS transistor, an element isolation region, and the like.

The refractory metal silicide layer 2 is made of CoSi ₂
Consists of The refractory metal silicide layer 2 is formed by the following salicide process. That is, the semiconductor substrate 1 is washed with dilute hydrofluoric acid to remove a natural oxide film on the surface of the impurity diffusion layer. Thereafter, the semiconductor substrate 1 is formed by sputtering.
On the surface, a Co layer is formed to a thickness of 10 nm and a TiN layer is formed to a thickness of 5 nm (both are not shown). The TiN layer is a cap layer for preventing oxidation. After this, RTA (Rapid Thermal
According to the Anneal method, a heat treatment is performed at 550 ° C. for 30 seconds to cause a silicidation reaction. The unreacted Co layer on the element isolation region or on the LDD sidewall is removed by immersion in an aqueous ammonia solution (a mixed aqueous solution of NH ₄ OH / H ₂ O ₂ ) at 65 ° C. for 3 minutes. Then, the refractory metal silicide layer 2 is selectively formed on the impurity diffusion layer of the semiconductor substrate 1 by annealing again at 700 ° C. for 30 seconds by the RTA method.

The interlayer insulating film 3 is made of SiO ₂ ,
The film is formed to a thickness of 700 nm by a VD method or a plasma CVD method. Thereafter, the opening diameter is 0.15 μm to 0.3 μm by excimer laser lithography and plasma etching.
Is opened. Contact hole 4
Are open to the refractory metal silicide layer 2.

The oxide residue on the surface of the refractory metal silicide layer 2 exposed at the bottom of the contact hole 4 and the etching residue containing carbon are cleaned by reverse sputtering. At this time, a rare gas such as Ar may be used alone, but H ₂ may be further added to Ar to use the reducing action by H radicals in combination.

Thereafter, a metal film 5 as a contact metal is formed to a thickness of 20 to 50 nm on the entire surface of the substrate to be processed. The metal film 5 is formed of Ti by a plasma CVD method or an ionization sputtering method.

FIG. 3B: The substrate to be processed is placed on the stage 12 of the parallel plate type plasma processing apparatus shown in FIG.
Not used, 10Nm～20n a metal nitride thin film 6a ₁
m, in this embodiment, it is formed to a thickness of 15 nm. (Low pressure CVD conditions of the metal nitride films _{6a 1) TiCl 4 30~50 sccm NH} 3 60~100 sccm N 2 1~5 slm Pressure 10 to 50 Torr temperature 630-680 ° C.

[0059] The metal nitride films 6a ₁ is, 5a in the film
Contains about t% of chlorine. Therefore, when removing the residual chlorine and exposing the substrate to be treated to the atmosphere,
It is necessary to prevent oxidation of the removed Ti metal.

FIG. 3C: In this embodiment, the Ti metal in the removed portion is silicided by the next plasma treatment removal. SiH ₄ 30 to 100 sccm H ₂ 50 to 300 sccm Ar 300 sccm RF power 0.3 to 2 kW Pressure 0.01 to 10 Torr Temperature 630 to 680 ° C.

In this plasma processing step, H ₂ and S
iH ₄ collides with the electrons in the plasma to generate H ^* , Si
H ₃ ^*, SiH ₂ ^*, to generate radicals such as SiH ^* and Si ^*. In this plasma processing step, plasma irradiation may be performed first with H ₂ gas, and then plasma irradiation with SiH ₄ gas may be performed.

FIG. 4D: Of these radicals,
H ^* radicals diffuse a metal nitride thin film 6a ₁ Medium, Ti
Reacts with Cl that is bound to and becomes HCl and is eliminated.

FIG. 4E: In addition, SiH ₃ ^* , SiH
₂ ^*, SiH ^* and Si ^* Each radicals also react with Cl bound with Ti of the metal nitride films 6a in _1, S
This is elimination become a iH _x Cl _y. At the same time these S
The reactive species containing i reacts with the Ti metal portion from which Cl has been eliminated, and turns the metal nitride thin film into a Ti-Si-N-based metal nitride.

As described above, by performing plasma irradiation of the mixed gas containing SiH ₄ and H ₂ , the amount of chlorine in the metal nitride thin film 6 a ₁ is reduced, and the Ti metal in the portion from which chlorine has been desorbed is silicide. Be transformed into Accordingly, risk is small metal nitride films 6a ₁ after plasma irradiation to oxidation proceeds even when exposed to the air.

FIG. 4 (f): However, the metal nitride thin film 6a
The thickness of ₁ is 15 nm in this embodiment, and the thickness is insufficient to function as a barrier layer. Therefore, FIG.
4B to 4E are repeated to obtain a metal nitride film 6 having a desired film thickness. In the present embodiment, FIGS.
Step (e) was repeated four times to obtain a metal nitride film 6 having a thickness of 60 nm.

According to this embodiment, the metal nitride thin film containing residual chlorine is subjected to plasma irradiation with a mixed gas of SiH ₄ and H ₂ , so that the chlorine content is low and the metal nitride thin film is exposed to the atmosphere. It is possible to form a metal nitride film with less fear of oxidation. The metal nitride film obtained in this embodiment is made of a Ti-Si-N-based dense and low-resistance metal nitride containing Si.

[Embodiment 2] In this embodiment, a metal nitride film made of TiN is formed by the parallel plate type plasma processing apparatus shown in FIG. 7, and this step is described with reference to FIGS. I will explain.

FIG. 5A: The substrate to be processed employed in the present embodiment also has a refractory metal silicide layer 2 and an interlayer insulating film 3 formed on a semiconductor substrate 1 as shown here. A conformal metal film 5 including a contact hole 4 opened in the film 3 is formed.

The semiconductor substrate 1 is made of a silicon substrate and has an impurity diffusion layer (not shown), that is, a source / drain region of a MOS transistor, an element isolation region, and the like.

The refractory metal silicide layer 2 is made of CoSi ₂
Consists of The refractory metal silicide layer 2 is formed by the following salicide process. That is, the semiconductor substrate 1 is washed with dilute hydrofluoric acid to remove a natural oxide film on the surface of the impurity diffusion layer. Thereafter, the semiconductor substrate 1 is formed by sputtering.
On the surface, a Co layer is formed to a thickness of 10 nm and a TiN layer is formed to a thickness of 5 nm (both are not shown). The TiN layer is a cap layer for preventing oxidation. Thereafter, 550 is determined by the RTA method.
A heat treatment is performed at 30 ° C. for 30 seconds to cause a silicidation reaction.
The unreacted Co layer on the element isolation region or on the LDD sidewall is removed by immersion in an aqueous ammonia solution (a mixed aqueous solution of NH ₄ OH / H ₂ O ₂ ) at 65 ° C. for 3 minutes.
Then, the refractory metal silicide layer 2 is selectively formed on the impurity diffusion layer of the semiconductor substrate 1 by annealing again at 700 ° C. for 30 seconds by the RTA method.

The interlayer insulating film 3 is made of SiO ₂ ,
The film is formed to a thickness of 700 nm by a VD method or a plasma CVD method. Thereafter, the opening diameter is 0.15 μm to 0.3 μm by excimer laser lithography and plasma etching.
Is opened. Contact hole 4
Are open to the refractory metal silicide layer 2.

The oxide film on the surface of the refractory metal silicide layer 2 exposed at the bottom of the contact hole 4 and the etching residue containing carbon are cleaned by reverse sputtering. At this time, a rare gas such as Ar may be used alone or as a mixture. Alternatively, H ₂ may be further added and the reducing action by H radicals may be used in combination.

Thereafter, a metal film 5 as a contact metal is formed on the entire surface of the substrate to be processed to a thickness of 20 to 50 nm. The metal film 5 is formed of Ti by a plasma CVD method or an ionization sputtering method.

FIG. 5B: The substrate to be processed is placed on the stage 12 of the parallel plate type plasma processing apparatus shown in FIG. 7, and the metal nitride is used in the thermal CVD mode, that is, without using the RF power source 14. A thin film 6a1 of ₁₀ nm to 20 nm,
In this embodiment, it is formed to a thickness of 15 nm. (Low pressure CVD conditions of the metal nitride films _{6a 1) TiCl 4 30~50 sccm NH} 3 60~100 sccm N 2 1~5 slm Pressure 10 to 50 Torr temperature 630-680 ° C.

[0075] The metal nitride films 6a ₁ is, 5a in the film
Contains about t% of chlorine. Therefore, when removing the residual chlorine and exposing the substrate to be treated to the atmosphere,
It is necessary to prevent oxidation of the removed Ti metal.

[0076] FIG. 5 (c): In the present embodiment, the following plasma treatment conditions were subjected to plasma irradiation in the metal nitride thin film 6a _1. H ₂ 100-500 sccm N ₂ 100-1300 sccm Ar 300 sccm RF power 0.3-2 kW Pressure 0.01-10 Torr Temperature 630-680 ° C.

In this plasma processing step, H ₂ and N
₂ collide with electrons in the plasma ^{_{H *, N 2 *, NH}} *
Radicals and ions such as N ₂ ⁺ and NH ⁺ are generated in the plasma. In this plasma processing step, plasma irradiation with H ₂ gas may be performed first, and then plasma irradiation with N ₂ gas may be performed.

FIG. 6D: Of these radicals,
H ^* radicals diffuse a metal nitride thin film 6a ₁ Medium, Ti
Reacts with Cl that is bound to and becomes HCl and is eliminated.

FIG. 6 (e): Reactive species including N such as radicals such as N ₂ ^* and NH ^* and ions such as N ₂ ⁺ and NH ⁺ react with the Ti metal portion from which Cl has been eliminated. and, a metal nitride thin film 6a ₁ and metal nitride TiN system.

As described above, the plasma irradiation of the mixed gas containing N ₂ and H ₂ allows the metal nitride thin film 6 to be irradiated.
The amount of chlorine in a ₁ is reduced, and the Ti metal in the portion from which chlorine has been eliminated is nitrided. Accordingly, risk is small metal nitride films 6a ₁ after plasma irradiation to oxidation proceeds even when exposed to the air.

FIG. 6F: However, the metal nitride thin film 6a
The film thickness of ₁ is also 15 nm in this embodiment, and the thickness is insufficient to function as a barrier layer. Therefore, FIG.
6B to 6E are repeated to obtain a metal nitride film 6 having a desired film thickness. In the present embodiment, FIGS.
Step (e) was repeated four times to obtain a metal nitride film 6 having a thickness of 60 nm.

According to this embodiment, the metal nitride thin film containing residual chlorine is subjected to plasma irradiation with a mixed gas of H ₂ and N ₂ , so that the chlorine content is low and the metal nitride thin film is exposed to the atmosphere. It is possible to form the metal nitride film 6 that is less likely to be oxidized.

The impurity analysis of the metal nitride film 6 obtained in this example was performed. A metal nitride thin film 6a ₁ immediately after the film formation by thermal CVD, shows the Cl content and O content of the metal nitride film 6 were subjected to plasma irradiation with a gas mixture of H ₂ and N ₂ in Table 2 .

[0084]

[Table 2]

As described above, the Cl content can be reduced and the O content can be significantly reduced as compared with the conventional dechlorination by heat treatment in an NH ₃ atmosphere.

Although the method for forming a metal nitride film of the present invention and the electronic device using the same have been described in detail above, the present invention is not limited to these examples, and various embodiments are possible. It is.

For example, in addition to TiN and Ti—Si—N exemplified as materials for the metal nitride film, TaN, Ta ₂ N, W
N, W ₂ N, Ta-Si-N or W-Si-N, etc.
The present invention can be applied to the formation of various metal nitride films or metal nitride films containing silicon. These metal nitride films are:
It can be formed by employing the corresponding metal halide gas and hydrogen nitride gas.

Although the metal nitride thin film is formed by the low pressure CVD method, it may be formed by the plasma CVD method. E of TiN
An example of CR plasma CVD conditions is shown. (Plasma CVD conditions for TiN) TiCl ₄ 5 to 7 sccm H ₂ 50 sccm N ₂ 100 sccm Ar 150 to 170 sccm Microwave power 2800 W Substrate temperature 200 to 500 ° C. NH ₃ is added to N ₂ or the N ₂ NH ₃ and N ₂
It may be replaced with H ₄ .

The method of forming a metal nitride film according to the present invention is particularly suitable for use as a diffusion barrier layer for wiring and contact plugs of various electronic devices such as high-integration semiconductor devices having a logic portion and a memory portion. It can be suitably used for a substrate to be processed which requires heat resistance in the process.

As an electronic device to which the present invention is applied, various semiconductor devices, magnetic head devices, thin-film coil devices, thin-film inductor devices, micromachines, and the like, in addition to application to electrodes and wirings for filling connection holes of highly integrated semiconductor devices. The present invention can be applied to various electronic devices in which the diffusion of the wiring material or the diffusion into the wiring material is concerned, such as a device.

[0091]

As is clear from the above description, according to the method for forming a metal nitride film of the present invention, the residual in the metal nitride film formed by the mixed gas containing the metal halide gas and the hydrogen nitride gas. It is possible to provide a method for forming a metal nitride film in which chlorine is reduced and incorporation of oxygen is prevented. The metal nitride film obtained thereby has low resistance itself, and in a subsequent process,
Even if heat treatment is applied, oxygen does not diffuse, and therefore, there is no possibility that the adjacent conductive layer or the like is oxidized to increase the resistance.

Further, according to the electronic device of the present invention, the metal nitride film formed by such a method is used as a part of the conductive layer, thereby reducing the wiring resistance of electronic devices such as highly integrated semiconductor devices. Thus, the performance of the electronic device can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a method for forming a metal nitride film of the present invention.

FIG. 2 is a schematic sectional view showing another method for forming a metal nitride film of the present invention.

FIG. 3 is a schematic cross-sectional view showing a step in which the method for forming a metal nitride film of the present invention is applied to formation of a contact plug of a highly integrated semiconductor device.

4 is a schematic cross-sectional view showing a step in which the method for forming a metal nitride film of the present invention is applied to formation of a contact plug of a highly integrated semiconductor device, and shows a step subsequent to FIG. 3;

FIG. 5 is a schematic cross-sectional view showing a process in which another method for forming a metal nitride film of the present invention is applied to formation of a contact plug of a highly integrated semiconductor device.

6 is a schematic cross-sectional view showing a step in which another method for forming a metal nitride film of the present invention is applied to formation of a contact plug of a highly integrated semiconductor device, and shows a step subsequent to FIG. 5;

FIG. 7 is a schematic sectional view of a parallel plate type plasma processing apparatus applied in the method for forming a metal nitride film of the present invention.

FIG. 8 is a schematic sectional view illustrating a problem of a conventional method for forming a metal nitride film.

[Explanation of symbols]

1 ... semiconductor substrate, 2 ... refractory metal silicide layer, 3 ... interlayer insulating film, 4 ... contact hole, 5 ... metal film, 6 ... metal nitride film, 6a _1, 6a _2, · · ·, 6a _n ... metal Nitride thin film, 7: W layer 10: processing chamber, 11: substrate to be processed, 12: stage, 13: gas shower head, 14: RF power supply, 15
… Gas inlet

Continued on the front page F term (reference) 4K030 AA02 AA06 AA13 AA17 AA18 BA18 BA29 BA38 BA44 BB12 CA04 CA12 DA03 FA01 FA03 FA10 HA01 HA04 JA01 LA01 LA15 4M104 AA01 BB14 BB20 CC01 DD09 DD16 DD22 DD37 DD44 DD45 DD80 DD84 DD86 FF18 JJ18FF18 JJ30 JJ32 JJ33 JJ34 KK26 LL03 NN06 NN07 PP01 PP04 PP09 PP15 QQ09 QQ12 QQ70 QQ73 QQ81 QQ90 QQ92 QQ94 RR04 SS13 SS15 XX09

Claims (10)

[Claims] A first step of vapor-phase growing a metal nitride thin film on a substrate to be processed with a mixed gas containing a metal halide gas and a hydrogen nitride gas; The method includes a second step of performing plasma irradiation of a mixed gas containing a silane-based gas as a constituent element. The first step and the second step are repeated a plurality of times in this order to form a metal nitride film having a desired thickness. A method for forming a metal nitride film. 2. A first step of vapor-phase growing a metal nitride thin film on a substrate to be processed by using a mixed gas containing a metal halide gas and a hydrogen nitride gas, and forming a hydrogen gas on the metal nitride thin film. A first step of performing plasma irradiation of a processing gas containing a silane-based gas as a constituent element on the metal nitride thin film; And a step of repeating the second step and the third step a plurality of times in this order to obtain a metal nitride film having a desired film thickness. 3. A first step of vapor-phase growing a metal nitride thin film on a substrate to be processed with a mixed gas containing a metal halide gas and a hydrogen nitride gas; A second step of performing plasma irradiation of a mixed gas containing a gas containing nitrogen as a constituent element, wherein the first step and the second step are repeated a plurality of times in this order to obtain a metal nitride film having a desired film thickness. Forming a metal nitride film. 4. A first step of vapor-phase growing a metal nitride thin film on a substrate to be processed using a mixed gas containing a metal halide gas and a hydrogen nitride gas, and forming a hydrogen gas on the metal nitride thin film. A second step of performing plasma irradiation of a processing gas containing as a component, and a third step of performing plasma irradiation of a processing gas containing a gas containing nitrogen as a constituent to the metal nitride thin film, A step of repeating the step, the second step, and the third step a plurality of times in this order to obtain a metal nitride film having a desired film thickness. 5. The metal nitride thin film has a thickness of 30 nm.
The method for forming a metal nitride film according to claim 1, wherein: 6. The metal nitride thin film has a thickness of 20 nm.
The method for forming a metal nitride film according to claim 1, wherein: 7. An electronic device comprising a metal nitride film formed by the method for forming a metal nitride film according to claim 1 as a part of a conductive layer. 8. An electronic device comprising a metal nitride film formed by the method for forming a metal nitride film according to claim 2 as a part of a conductive layer. 9. An electronic device comprising a metal nitride film formed by the method for forming a metal nitride film according to claim 3 as a part of a conductive layer. 10. An electronic device, comprising a metal nitride film formed by the method for forming a metal nitride film according to claim 4 as a part of a conductive layer.