JPH06104207A - Method for manufacturing semiconductor device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a highly reliable semiconductor device by forming a refractory metal silicide on a silicon surface at low temperature with high selectivity. According to the present invention, when a contact hole is formed on a semiconductor substrate and a refractory metal is selectively formed on a silicon surface exposed in the contact hole, an organic group and a halogen are used as ligands. High-melting point metal complex and silane-based gas, or high-melting point metal complex having only organic group as a ligand, gas containing silane-based gas and halogen, or high-melting point metal complex having organic group as a ligand and halogen A silane-based gas is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a method of filling a contact hole.

[0002]

2. Description of the Related Art In recent years, with the high integration of semiconductor devices, circuits are becoming finer. For example, the area of a connecting portion for connecting a gate electrode or a source / drain diffused layer to a metal wiring. Is very small.

As a result, the aspect ratio of the contact hole is increased, so that the step coverage of the wiring film is deteriorated, and the thinned portion in the step portion causes a problem of increased resistance.

As a method for solving this, a method has been proposed in which tungsten or the like is selectively embedded in the contact hole by a CVD method, and then a wiring film of aluminum or the like is formed. There are two methods for burying tungsten: a selective CVD method in which tungsten is selectively grown in a contact hole, and a blanket tungsten CVD method in which a tungsten film is formed in a blanket shape and then etched back to leave tungsten in the contact hole. is there.

First, a method of burying tungsten in the contact hole by using the selective tungsten CVD method will be described. 3A to 3D are cross-sectional views showing the embedding step.

First, a field oxide film 2 is formed on a silicon substrate 1 to form an element region such as an impurity diffusion layer 3 in a separated region, and then an interlayer insulating film 4 having a film thickness of 1 is formed on the element region. A silicon oxide film 4 of 0.5 μm is formed. Then, the interlayer insulating film 4 is formed by photolithography.
Then, a contact hole 5 is formed so as to contact the impurity diffusion layer 3 (FIG. 3 (a)).

Thereafter, a Ti film 6 is formed by a sputtering method so that the film thickness at the bottom of the contact hole is 20 nm, and a TiN film 7 having a film thickness of 20 nm is further formed (FIG. 3 (b)).

Then, heat treatment is performed at 750 ° C. to form a 40 nm TiSi ₂ film 8 at the bottom of the contact hole, the unreacted Ti film 6 and TiN film 7 are removed, and the TiSi ₂ film 8 is formed only at the bottom of the contact hole. (Fig. 3 (c)).

After that, a mixed gas of WF ₆ and SiH ₄ mixed at 10: 7 is introduced onto a wafer heated to 230 to 300 ° C. to selectively form the tungsten film 9 (FIG. 3). (d)).

Next, a method of burying tungsten in the contact hole by using the blanket tungsten CVD method will be described. 4A to 4D are cross-sectional views showing the embedding step.

Similar to the selective tungsten CVD method, the field oxide film 2, the impurity diffusion layer 3 and the S layer are formed on the silicon substrate 1.
After forming the iO ₂ film 4 and the contact hole 5, 2
A 0 nm Ti film 6 and a 70 nm TiN film 7 are formed (FIG. 4).
(a)).

After that, WF ₆ , SiH _4, and H ₂ are added at 10: 7: 1.
The tungsten film 9 is formed into a blanket by introducing the tungsten film 9 at a rate of 000 onto a wafer heated to 350 to 450 ° C. (FIG. 4 (b)).

Further, a tungsten film 9 on the SiO ₂ film 4
Is etched back together with the TiN film 8 and the Ti film 7 to leave the tungsten film 9 inside the contact hole (FIG. 4 (c)).

In this method, the reason why the TiSi ₂ film 8 is previously formed as a base is that the selective tungsten C
When the tungsten film 9 is formed by the VD method, the silicon substrate 1 is etched so as to grow at the same speed even if the impurity diffusion layers 3 of different types are formed on the same substrate. This is to prevent the tungsten film 9 from growing through the impurity diffusion layer 3 and causing a junction leak, and the Ti film 6 and the TiN film 7 are formed by the blanket tungsten CVD method by the selective tungsten CVD method. The reason is to improve the adhesion between the SiO ₂ film 4 and the tungsten film 9 in addition to the same reason as described above.

When the tungsten film 9 is formed by the blanket tungsten CVD method, the tungsten film 9 on the SiO ₂ film 4 can be used as it is as a wiring film. In this case, since tungsten is a refractory metal, there is an advantage in that after the wiring is formed, heat treatment at a higher temperature can be performed than in the case where a conventional aluminum wiring is used.

However, as described above, in the method in which the Ti film 6 is formed on the bottom of the contact hole by the sputtering method and then reacted with the silicon substrate 1, the aspect ratio of the contact hole is further increased when the integrated circuit is further miniaturized. The sputtering method has a problem that the Ti film cannot be uniformly formed on the bottom of the contact hole, as shown in FIG. Further, as described above, the Ti film 6 and the Ti film are formed under the tungsten film 9.
When a laminated body of the N film 7 is formed, the Ti film 6 and the silicon substrate 1 react with each other when a high temperature process of 550 ° C. or higher is performed, and FIG.
As shown in (d), there is a problem that the TiSi ₂ film 8 penetrates the impurity diffusion layer 3 and grows to cause a junction leak.

Even if the Ti film 6 and the TiN film 7 are formed by the CVD method, the depth of the impurity diffusion layer 3 becomes shallow, so that FIG.
As shown in FIG. 3, there is a problem that the TiSi ₂ film 8 penetrates the impurity diffusion layer 3 and grows to cause a junction leak.

As a method for solving this, there is a method in which a TiSi ₂ film 8 is formed at the bottom of the contact hole and then a TiN film 7 is formed, and then a tungsten film 9 is formed in a blanket form, as in the case of the selective tungsten CVD method. .

As a method for solving such a problem, a selective CVD method is used to form TiSi _{2 on} the bottom of the contact hole.
A method of forming the film 8 has been proposed. According to this method, after forming the contact hole 5, TiCl ₄ and SiH ₄ are formed.
Are introduced at a ratio of 1:25 onto a wafer heated to 650 to 850 ° C., and the TiSi ₂ film 8 is selectively formed on the bottom of the contact hole.
Is formed. By this method, a high temperature heat treatment step can be performed after the tungsten wiring is formed.

[0020]

[SUMMARY OF THE INVENTION In the selective CVD method using the TiCl ₄ and SiH ₄ as described above, in the method of selectively forming the TiSi ₂ film on the silicon surface which is exposed in the contact hole, TiCl ₄ and vice Since the product HCl or the like consumes the Si substrate and SiCl _x is formed and evaporated, the TiSi ₂ film 8 penetrates the impurity diffusion layer 3 to cause a junction leak.
This is not limited to Ti, but has been a similar problem for other refractory metal silicides.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for forming a refractory metal silicide at the bottom of a contact hole so that a junction leak does not occur.

[0022]

Therefore, in the present invention, a refractory metal complex having an organic group and a halogen as a ligand and a silane-based gas, or a refractory metal complex having an organic group as a ligand and a silane-based gas. A gas containing gas and halogen, or a silane-based gas containing halogen and a high melting point metal complex having an organic group as a ligand is used. Here, the refractory metal is, for example, Ti, V, Co, Ni, Mo, Pd, W.
In the above, the organic group is an atomic group containing at least one element of C and N, O, S, etc. and binding to these refractory metals, and the silane-based gas is, for example, SiH ₄ or S.
i ₂ H ₆ , an organic silane having an organic group such as a methyl group, and the silane-based gas containing halogen are, for example, SiH ₃
Cl, SiH ₂ Cl ₂ , SiHCl ₃ , Si ₂ H ₄ F ₂
The halogen-containing gas is, for example, a simple halogen gas such as chlorine or bromine, hydrogen chloride such as hydrogen chloride or hydrogen bromide, or the like.

[0023]

As a result of various experiments, the inventors of the present invention have found that if the reaction system contains both an organic group and a halogen element, the high melting point with good selectivity can be obtained at a low temperature without etching the substrate. It was found that a metal silicide film can be formed.

The reason is considered as follows. That is, first, the refractory metal complex containing an organic group is dissociated at a low temperature, the reaction is started, and the refractory metal film is formed on silicon. On the other hand, this reaction energy turns halogen into an organic halogen, which is different from SiO _2. Difficult to react, Si
It is considered that the nuclei are hard to be formed on O ₂ and therefore the selectivity is maintained well.

In the present invention, the reaction system may contain both an organic group and a halogen element, and a refractory metal complex having an organic group and a halogen as a ligand and a silane-based gas, or an organic group. Either a high-melting point metal complex having only as a ligand, a silane-based gas and a gas containing halogen, or a high-melting point metal complex having an organic group as a ligand and a halogenated silane-based gas may be used.

[0026]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 (a) to 1 (d) are sectional views showing the steps of manufacturing a semiconductor device according to an embodiment of the present invention. First, a field oxide film 2 is formed on an n-type silicon substrate 1, a p + impurity diffusion layer 3 having a depth of 40 nm is formed in the separated region, and an interlayer insulating film 4 having a film thickness of 1 is formed on the p + impurity diffusion layer 3. .5μ
A silicon oxide film (SiO ₂ ) of m ₂ is formed, and a 0.6 μm square contact hole 5 is formed therein by photolithography (FIG. 1 (a)). Then BCl ₃ or F
After removing the natural oxide film on the exposed silicon by RIE using ₂ , the silicon substrate was transferred in vacuum and
After heating to 00 to 550 ° C., TiCl ₃ (CH ₃ ) is introduced at 1 sccm and SiH ₄ is introduced at 15 to 30 sccm to form a TiSi ₂ film 8 having a thickness of 30 nm only on the bottom of the contact hole 5 (see FIG. )).

After that, the substrate temperature is set to 200 to 300 ° C., WF ₆ is introduced at 10 sccm, SiH ₄ is introduced at 7 sccm, and TiSi is introduced.
_The W film 9 is selectively formed only on the ₂ film 8 (FIG. 1C).
). Then, a Ti film 6 having a film thickness of 20 nm, a TiN film 7 having a film thickness of 70 nm, and an aluminum film or an aluminum alloy film 10 having a film thickness of 300 nm are sequentially formed and patterned to form a wiring pattern (FIG. 1 (d)). .

Although the contact hole thus obtained is fine, the TiSi ₂ film 8 can be formed uniformly and without etching the silicon substrate, so that there is no junction leak and the contact resistance is low. A wiring structure can be obtained.

In the above embodiment, when forming the TiSi ₂ film, the silicon substrate is heated to 300 to 550 ° C. and selected C using TiCl ₃ (CH ₃ ) and SiH ₄ is used.
Although the VD method is used, the present invention is not limited to this. For example, in the same manner as in the other steps, the silicon substrate is heated to 200 to 400 ° C. and Ti [N (C
H ₃ ) ₂ ] ₄ at 1 sccm, SiH ₄ at 50 to 200 sccm,
It may be carried out by introducing ₁ to 10 sccm of HCl or Cl ₂ . Even with this method, the TiSi ₂ film can be formed with excellent selectivity only on the bottom of the contact hole. Also, Ti [N (CH ₃ ) ₂ ] ₄ was added at 1 sccm, SiH
Supply ₂ Cl ₂ about 20sccm, temperature 200 ~ 400 ℃
You may form into a film with.

Further, the silicon substrate is heated to 200 to 400 ° C. and Ti [N (CH ₃ ) ₂ ] ₄ is added at 1 sccm and SiH ₃
It may be performed by introducing Cl in an amount of 25 to 100 sccm. Further, even by these methods, the TiSi ₂ film can be formed with excellent selectivity only on the bottom of the contact hole.

Furthermore, in the above embodiment, after the TiSi ₂ film 8 is selectively formed at the bottom of the contact hole, the W
Although the W film is selectively embedded only in the contact hole by the film selective CVD method, the W film may be formed in a blanket shape. Next, as a second embodiment of the present invention, a wiring method in which a W film is formed in a blanket shape will be described. 2A to 2D are cross-sectional views showing the manufacturing steps of the semiconductor device according to the second embodiment of the present invention. T
Until the formation of the iSi ₂ film, it is formed in exactly the same way as in the first embodiment.

That is, first, the field oxide film 2 is formed on the n-type silicon substrate 1, the p + impurity diffusion layer 3 having a depth of 40 nm is formed in the separated region, and the interlayer insulating film 4 is further formed on the p + impurity diffusion layer 3. As a film, a silicon oxide film (SiO ₂ ) having a film thickness of 1.5 μm is formed, and a 0.6 μm square contact hole 5 is formed therein by photolithography (FIG. 2).
(a)).

Then, RIE using BCl ₃ or F ₂
After removing the natural oxide film on the exposed silicon,
The silicon substrate is transported in a vacuum and heated to 300 to 550 ° C., then TiCl ₃ (CH ₃ ) is added at 1 sccm and SiH ₄
Is introduced into the contact hole 5 to form a TiSi ₂ film 8 having a thickness of 50 nm only on the bottom of the contact hole 5 (FIG. 2 (b)).
).

Further, at the same temperature, TiCl ₃ (CH ₃ )
Of 1 sccm and NH ₃ of 10 to 20 sccm to obtain a film thickness of 100
A TiN film 7 having a thickness of nm is formed (FIG. 2 (c)).

Thereafter, the substrate temperature is set to 350 to 450 ° C., WF ₆ is 10 sccm, SiH ₄ is 7 sccm, and H ₂ is 100 to 100 sccm.
By introducing 1000 sccm, the W film 9 is formed into a blanket shape (FIG. 2 (d)).

Thereafter, the TiN film 7 and the W film 9 are patterned to form a wiring pattern (FIG. 2 (e)).

Although the contact hole thus obtained is fine, the TiSi ₂ film 8 can be formed uniformly and without etching the silicon substrate, so that there is no junction leak and the contact resistance is low. A wiring structure can be obtained. Further, since the wiring is formed of the W film 9 which is a refractory metal, a high temperature heat treatment step can be performed on the upper layer, and at that time, silicon and impurities are diffused from the impurity diffusion layer 3 into the W film 9. Is prevented by the TiN film 8 and the TiN film 8 is made of SiO ₂
Since it is on the film 4, the adhesion between the W film 9 and the SiO ₂ film 4 can be improved.

In the above embodiment, when forming the TiSi ₂ film, the silicon substrate is heated to 300 to 550 ° C. and the selective C using TiCl ₃ (CH ₃ ) and SiH ₄ is used.
Although the VD method is used, the present invention is not limited to this. For example, in the same manner as other steps, the silicon substrate is heated to 250 to 500 ° C. and Ti [N (CH ₃ ) 2 is used.
₂ ] ₄ 1 sccm, SiH ₄ 50-200 sccm, HCl
Alternatively, it may be performed by introducing Cl _{2 at 1} to 10 sccm. Further, when forming the TiN film, the silicon substrate is heated to 250 to 500 ° C. and Ti [N (C
H ₃ ) ₂ ] ₄ may be introduced at 1 sccm, and NH ₃ may be introduced at 20 to 50 sccm. Even with this method, the TiSi ₂ film can be formed extremely selectively only on the bottom of the contact hole, and a highly reliable contact wiring structure can be obtained.

When the TiSi ₂ film is formed, the silicon substrate is heated to 200 to 400 ° C. and Ti [N (C
H ₃ ) ₂ ] ₄ at 1 sccm and SiH ₃ Cl at 25-100 sc
It may be done by introducing cm. Furthermore, Ti [N
(CH ₃ ) ₂ ] ₄ is about 1 sccm and SiH ₂ Cl ₂ is 20
A film may be formed at a temperature of 200 to 400 ° C. by supplying about sccm. Even with this method, the TiSi ₂ film can be formed with excellent selectivity only on the bottom of the contact hole.

Although the formation of the contact to the p + impurity diffusion layer has been described in the above embodiment, it is needless to say that it is applicable to the formation of the contact to the n + impurity diffusion layer. Further, as a halogen used when forming the TiSi ₂ film, a gas containing chlorine, Ti
Cl ₃ (CH ₃ ), SiH ₃ Cl and HCl were used, but F, Br and I are also applicable, and TiF ₃ (CH
₃ ), SiH ₃ F, HF, TiBr ₃ (CH ₃ ), Si
H ₃ Br and HBr, TiI ₃ (CH ₃₎ or SiH ₃ may be used such as I or HI. Furthermore, these gases may be used after being made into plasma by discharge or the like.

Furthermore, as an organic group (CH ₃ ) or N
(CH ₃ ) ₂ was used, but not limited thereto, C ₂ H ₅ , CO, N (C ₂ H ₅ ) ₂ , OC ₂ H ₇ ,
It may be an organic group composed of an element selected from C, H, N, O and S, such as OCOCH ₃ and SCH ₃ , or an organic group that coordinates in a π orbit, and may be monodentate or bidentate. .

When TiSi ₂ is formed using a refractory metal complex and a silane-based gas, if the refractory metal complex contains halogen and an organic group, it does not depend on the coordination ratio of its ligand. Applicable. That is, when X and R are each monodentately coordinated with a ligand, even TiX ₃ R may have TiX ₂ R
₂ or TiXR ₃ , and when plural kinds of X and R are contained, the kinds of X and R may be different. In the above examples, the tetravalent Ti complex was used as the refractory metal complex, but other valences may be used, and other refractory metals such as V, Co, Ni, Mo, Pd and W may be used. The present invention can be similarly applied to the case where a complex is used. When the refractory metal complex is solid or liquid and has a low vapor pressure, the source and the pipe are heated below the decomposition temperature and introduced into the reaction chamber. Further, an inert gas such as Ar may be used as a carrier gas at the time of introduction.

Furthermore, in the second embodiment,
Although TiN was formed by using the refractory metal complex and NH ₃ , a refractory metal carbide or boride may be used instead of TiN. For example, when forming a refractory metal carbide, a refractory metal complex and CH ₄ or the like, and when forming a refractory metal boride, a refractory metal complex and B ₂ H ₆ or the like are used. You can In this case, all the ligands of the high melting point metal complex may be halogen or all organic groups.

In addition, although the selective growth between the surface of the single crystal silicon substrate and the surface of the silicon oxide film is used in the above embodiment, the present invention is not limited to this, and the polycrystalline silicon film,
Selective growth may be used between the surface of a silicon film such as an amorphous silicon film and the surface of an insulating film.

In addition, various modifications can be made without departing from the scope of the present invention.

[0047]

As described above, according to the present invention, when the refractory metal silicide film is selectively formed on the silicon surface exposed in the contact hole, an organic group and a halogen element are provided in the reaction system. Therefore, the refractory metal silicide film can be formed with good selectivity at low temperature.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of a conventional semiconductor device.

FIG. 4 is a manufacturing process diagram of a conventional semiconductor device.

FIG. 5 is a diagram showing a refractory metal silicide film formed by using a conventional semiconductor device manufacturing method.

[Explanation of symbols]

1 silicon substrate 2 field insulating film 3 p + impurity diffusion layer 4 interlayer insulating film 5 contact hole 6 Ti film 7 TiN film 8 TiSi ₂ film 9 W film 10 aluminum film or aluminum alloy film

Claims (1)

[Claims] 1. A refractory metal having an organic group and a halogen as a ligand when selectively growing refractory metal silicide on a silicon surface exposed in a contact hole formed in an insulating film on a semiconductor substrate surface. Gas containing a complex and a silane-based gas, a high-melting point metal complex having an organic group as a ligand and a silane-based gas and a halogen, or a high-melting point metal complex having an organic group as a ligand and a silane-based gas including a halogen. A method of manufacturing a semiconductor device, wherein a refractory metal silicide is selectively grown on a silicon surface by the selective CVD method used.