JPH06216066A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor device, where in a gate electrode or a wiring layer of high melting point metal silicide film which is lessened in resistance, hardly changed in characteristics, excellent in adhesion to a base insulating film, and high enough in step coverage is formed by removing residual impurities of source gas. CONSTITUTION:An N<+>-type impurity region 12 is formed on the surface of a silicon substrate 10, a silicon oxide film 14 is formed on the surface of the substrate 10, a contact hole 16 high in an aspect ratio is provided to the silicon oxide film 14, and a WSi, wiring layer 18 connected to the N<+>-type impurity region 12 through the intermediary of the contact hole 16 is formed through such a manner that WF6 gas of 5sccm as source gas and SiHCl3 gas of 200sccm as reaction gas are introduced into a vacuum CVD reactor reduced to a pressure of 1.0Torr and kept at a growth temperature of 750 deg.C or so for about three minutes to form a WSi2 film of thickness 15nm or so on a wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to forming a gate electrode or a wiring layer made of a refractory metal silicide film by using a CVD (Chemical Vapor Deposition) method. On how to do.

[0002]

2. Description of the Related Art With the recent increase in speed of semiconductor devices,
It has been required to reduce the resistance of the gate electrode of the transistor and the wiring layer. Therefore, a refractory metal silicide film has been used in place of the impurity-doped polysilicon film as a material for the gate electrode and the like.

Conventionally, as a method for forming such a refractory metal silicide film, for example, when forming a WSi ₂ (tungsten silicide) film, WF ₆ (tungsten hexafluoride) is used as a source gas and SiH ₄ (silane). ) Is used as a reaction gas, and a growth temperature of 300 to 40 is used.
Most of them formed at 0 ° C.

[0004]

However, in the conventional method for forming a refractory metal silicide film using SiH ₄ as a reaction gas, for example, a WSi ₂ film, the growth temperature is as low as 300 to 400 ° C. , F (fluorine) impurities from the WF ₆ gas remain in the WSi ₂ film.

[0005] Therefore, when using this WSi ₂ film as the gate electrode and a wiring layer, the resistance by the presence of F impurities in WSi ₂ film is increased, the realization of high-speed by initially is the object delay time reduction of There was a problem that was blocked. Further, when it is used for the gate electrode, the F impurity in the WSi ₂ film penetrates into the gate oxide film by the subsequent heat treatment process, which causes a problem that the device characteristics are changed.

The WSi ₂ film formed at a low growth temperature of 300 to 400 ° C. is not so good in crystallinity and is close to amorphous, and its resistance value is considerably high. Therefore, a step of performing an annealing treatment at a temperature of 700 ° C. or higher is required. Further, at such a low growth temperature, since the surface mobility of the molecular species obtained by the thermal decomposition of SiH ₄ is small, even if there are uneven steps on the base, sufficient step coverage with the WSi ₂ film can be obtained. A situation occurs in which you cannot obtain it.

For example, as shown in FIG. 3A, an n + type impurity region 42 formed on the surface of a silicon substrate 40.
The contact hole 4 opened in the silicon oxide film 44.
When the thin film WSi ₂ wiring layer 48 connected through 6 is formed by using the conventional CVD method using SiH ₄ as a reaction gas, the WSi grown on the n + -type impurity region 42 in the contact hole 46 is grown. _The step coverage t1 / t2 represented by the ratio of the thickness t1 of the _two wiring layer 46 to the thickness t2 of the WSi2 wiring layer 46 grown on the silicon oxide film 42 outside the contact hole 44 is extremely low. .

For this reason, the WSi ₂ film formed by the conventional CVD method using SiH ₄ as a reaction gas is used in the tendency that the aspect ratio of the contact hole becomes higher with the miniaturization of semiconductor devices in recent years. Then, it becomes difficult to form a thin film wiring layer having a uniform thickness in a contact hole having a high aspect ratio, and there is a problem that disconnection or the like due to poor coverage may occur.

Further, when the underlying layer on which the WSi ₂ film is formed is an insulating film such as a silicon oxide film, the adhesion temperature between the WSi ₂ film and the underlying insulating film is poor because the growth temperature is low. Therefore, when the WSi ₂ film is used as a gate electrode or a wiring layer, it is necessary to have a polycide structure composed of a composite layer of a polysilicon film and a WSi ₂ film, which complicates the process, and There was also the problem of increased resistance.

If, for example, the growth temperature of the WSi ₂ film is increased to solve these problems, the thermal decomposition of SiH ₄ rapidly progresses, and Si is excessively reduced to produce Si.
Growth occurs preferentially, so that a good WSi ₂ film that is stoichiometrically appropriate is not formed, and Si-rich WSix (x
> 2) A film is formed. Further, in the case of forming a TiSi ₂ (titanium silicide) film as the refractory metal silicide film, instead of SiH ₄ , for example, Si
A selective growth method of a TiSi ₂ film has been proposed in which HCl ₃ (trichlorosilane) gas is used as a reaction gas to selectively grow a TiSi ₂ film on a silicon substrate (Japanese Patent Laid-Open Publication No. 6-58242).
No. 1-183199).

That is, as shown in FIG. 3B, an n + type impurity region 42 is formed on the surface of the silicon substrate 40,
When a contact hole is opened in the silicon oxide film 44 on the n + -type impurity region 42, for example, TiCl ₄ (titanium tetrachloride) gas as a source gas, H ₂ gas as a carrier gas, and SiHCl ₃ gas as a reaction gas are used. Then, the TiSi ₂ film 50 is grown only on the n + type impurity region 42 in the contact hole. Then, the silicon oxide film 44 and the TiSi ₂ film 50 are made to have substantially the same thickness to flatten the surfaces, and an aluminum wiring layer (not shown) is formed on the flattened silicon oxide film 44 and the TiSi ₂ film 50. To do. Thus n in the contact hole
TiSi ₂ film 5 selectively grown on + type impurity region 42
By providing a flat aluminum wiring layer connected to the n + -type impurity region 42 via 0, the problem of disconnection or the like is solved.

Indeed, in the case of the present invention, the growth temperature 600
Since the temperature is as high as ˜900 ° C., the situation in which impurities from the source gas remain in the silicide film as described above does not occur. However, according to the present invention, TiSi ₂ is formed on the silicon oxide film 44 by adjusting the flow rate ratio of the source gas containing Ti (titanium) to the reaction gas containing Si under the growth conditions so as to be Ti-rich.
The film 50 is not grown, and Ti is formed only on the n + -type impurity region 42 in the contact hole opened in the silicon oxide film 44.
Since the Si ₂ film 50 is selectively grown, it does not solve the above-mentioned problems to be solved by the present invention.

[0013] That is, in this TiSi ₂ film selective growth method, because on the insulating film TiSi ₂ film does not grow, applying this method to the case of forming a gate electrode or wiring layer TiSi ₂ film itself Can not. Therefore, the present invention realizes a low resistance by eliminating impurities remaining from the source gas, prevents characteristic fluctuations, has sufficient step coverage, and has good adhesion to the underlying insulating film. It is an object of the present invention to provide a method for manufacturing a semiconductor device in which a gate electrode or a wiring layer made of a silicide film is formed.

[0014]

The above object is a gas for generating a hydrogen-containing gas species and hydrogen chloride on a semiconductor substrate, using a halide of a refractory metal as a source gas, and thermally decomposing or reacting with a hydrogen gas. Forming a refractory metal silicide film by using a chemical vapor deposition method using as a reaction gas, and patterning the refractory metal silicide film into a predetermined shape to form a gate electrode or a wiring layer. And a method of manufacturing a semiconductor device.

In the method for manufacturing a semiconductor device described above, as the reaction gas, trichlorosilane, dichlorosilane, trichlorosilane or a mixed gas of dichlorosilane and hydrogen gas, or a mixed gas of silicon tetrachloride and hydrogen gas is used. It is achieved by a method for manufacturing a semiconductor device, which is characterized by being used. In the method for manufacturing a semiconductor device described above, the semiconductor substrate is covered with an insulating film, and the refractory metal silicide film is directly formed on the insulating film. Achieved by the method.

[0016]

According to the present invention, in the formation of a refractory metal silicide film by chemical vapor deposition, a refractory metal halide is used as a source gas, and a silicon is obtained by thermal decomposition or reaction with hydrogen gas as a reaction gas. 500 to by using a gas species containing a gas species and hydrogen chloride, such as trichlorosilane, dichlorosilane, trichlorosilane or a mixed gas of dichlorosilane and hydrogen gas, or a mixed gas of silicon tetrachloride and hydrogen gas, 900
Since the growth in the high temperature region of ℃ becomes possible, the concentration of impurities from the source gas remaining in the refractory metal silicide film is significantly reduced, and the resistance of the refractory metal silicide film is reduced, and the reaction The surface mobility of the molecular species of the gas is increased to significantly improve the step coverage with respect to the unevenness of the base.

[0017]

The present invention will be described below based on illustrated embodiments. FIG. 1 is a process sectional view for explaining a method of forming a WSi ₂ wiring layer according to an embodiment of the present invention, and FIG.
FIG. 3 is a schematic diagram showing an apparatus for growing a _two film. Figure 1
As shown in (a), for example, an n + type impurity region 12 is formed on the surface of the silicon substrate 10, and a silicon oxide film 14 is further deposited on the silicon substrate 10.
Then, it is assumed that a wiring layer connected to the n + type impurity region 12 must be formed through the contact hole 16 opened in the silicon oxide film 14. Moreover, the aspect ratio of the contact hole 16 is set to be considerably high in order to miniaturize the semiconductor device.

Further, as shown in FIG.₂film
The growth device is a heater 2 in the low pressure CVD reactor 20.
2 to control the growth temperature. That
The WF low pressure CVD reactor 20 has a WF₆Container 24,
SiHCl₃Container 26 and H ₂From the cylinder 28
Via MFC (Mass Flow Controller) 30
The source gas and reaction gas are supplied under reduced pressure.
It

Now, as shown in FIG. 1A, the wafer 32 is mounted on the heater 22 in the low pressure CVD reactor 20 and the internal pressure is set to 1 by the vacuum pump while maintaining the wafer temperature at about 750 ° C. Reduce the pressure to about 0.0 Torr.
In such a state, in the low pressure CVD reactor 20,
WF ₆ gas with a flow rate of 5 sccm is supplied as a source gas, SiHCl ₃ gas with a flow rate of 200 sccm and H with a flow rate of 100 sccm are supplied.
A mixed gas with _two gases is supplied as a reaction gas. Under such growth conditions, when the growth is performed for about 3 minutes, the thickness becomes 1
A WSi ₂ film of about 50 nm is formed on the wafer 32.

After the WSi ₂ film is formed on the wafer 32 in this way, the WSi ₂ film is patterned into a predetermined shape. As shown in FIG. 1B, the contact hole 16 opened in the silicon oxide film 14. W connected to the n + type impurity region 12 on the surface of the silicon substrate 10 via
The Si ₂ wiring layer 18 is formed. As described above, according to the present embodiment, the WF ₆ gas is used as the source gas and the mixed gas of SiHCl ₃ gas and H ₂ gas is used as the reaction gas, and the WSi ₂ film is grown in the high temperature region of the growth temperature of 750 ° C. by, the stoichiometric appropriate WSi ₂ film is formed, F impurities from WF ₆ gas WSi ₂
The concentration remaining in the film is also reduced to about 1/10 of that of the WSi ₂ film grown using the conventional SiH ₄ as the reaction gas. As a result, the resistance of the WSi ₂ wiring layer 18 can be prevented from increasing and the delay time of the semiconductor device can be shortened to achieve high speed.

Further, S obtained in a high temperature region of about 750 ° C.
iHCl₃The surface mobility of the molecular species of
SiH in the low temperature region of 00 ℃_FourSurface mobility of
Compared with Fig. 1 (b) and Fig. 3 (a),
Obviously, if there are uneven steps on the substrate,
Coverability was improved by about 30% over the conventional case. By this
Even in contact holes with high aspect ratio
Thin film WSi with thickness ₂By forming the wiring layer 18,
Therefore, it will not cause disconnection due to poor coverage.
In addition, it is possible to miniaturize semiconductor devices.
It was

The WSi ₂ film formed according to this embodiment is also used.
Since the film has good crystallinity and an annealing process for reducing the resistance is unnecessary, the process can be simplified accordingly. Further, the WSi ₂ film formed according to this example has a high growth temperature, and
₂ Adhesion between the wiring layer 18 and the underlying silicon oxide film 14 is good, and therefore the polysilicon film and WS are used as the wiring layer.
Since it is not necessary to form a polycide structure composed of a composite layer with the i ₂ film, the process is correspondingly simplified and the resistance as a wiring layer is also reduced. Needless to say, the underlying layer that is in close contact with the WSi ₂ wiring layer 18 is not limited to the silicon oxide film 14 and may be any other insulating film.

In the above embodiment, a mixed gas of SiHCl ₃ gas and H ₂ gas was used as the reaction gas, but instead of this, SiH ₂ Cl ₂ (dichlorosilane) was used.
Mixed gas or SiCl ₄ in the gas and H ₂ gas be used a mixed gas of a (silicon tetrachloride) gas and H ₂ gas may have the same effect. Further, SiHCl ₃ gas or SiH ₂ Cl ₂ gas may be used alone without mixing H ₂ gas, but according to the experiments by the present inventors, at least for improving the step coverage, Better results were obtained when mixed with _two gases. It is considered that the presence of H ₂ gas plays some role in increasing the surface mobility of the molecular species of the reaction gas.

The growth temperature in the above embodiment is about 7
The growth temperature is set to 50 ° C, but the growth temperature is 500 to 9
It may be a high temperature region of 00 ° C. In addition, the above embodiment,
Although the case where the WSi ₂ film is used for the wiring layer has been described, the present invention is not limited to this and may be used for the gate electrode, for example. In this case, the F impurity from the WF ₆ gas is WSi ₂
Since the concentration remaining in the film was reduced to about 1/10 of that in the conventional case, it was found that W
Since it is possible to prevent the F impurity in the Si ₂ film from penetrating into the gate oxide film, it is possible to reduce the resistance of the gate electrode, stabilize the device characteristics, and improve the reliability.

Further, when this WSi ₂ film is used for the gate electrode, the adhesion with the underlying gate oxide film is improved, and it is not necessary to form a polycide structure composed of a composite layer of a polysilicon film and a WSi ₂ film. Therefore, the process is simplified correspondingly, and the resistance as the gate electrode is also reduced.
Further, in the above-mentioned embodiment, the high melting point metal silicide film W
Although the case of forming the Si ₂ film has been described, the present invention is not limited to this. For example, MoSi ₂ (molybdenum silicide) is used.
The present invention can also be applied to a refractory metal silicide film such as a film or a TiSi ₂ film.

[0026]

As described above, according to the present invention, a refractory metal halide is used as a source gas, and a gas species containing silicon and hydrogen chloride are generated as a reaction gas by thermal decomposition or reaction with hydrogen gas. Refractory metal on a semiconductor substrate by a chemical vapor deposition method using a gas such as trichlorosilane, dichlorosilane, trichlorosilane or a mixed gas of dichlorosilane and hydrogen gas, or a mixed gas of silicon tetrachloride and hydrogen gas. By growing a silicide film and forming a gate electrode or a wiring layer made of this refractory metal silicide film, the concentration of impurities from the source gas remaining in the refractory metal silicide film can be significantly reduced. , Lowering the resistance of the gate electrode or the wiring layer makes it possible to speed up the semiconductor device and Stabilization of element characteristics by preventing penetration into the gate oxide film, and can improve a reliability.

Further, since the surface mobility of the molecular species of the reaction gas can be increased to remarkably improve the step coverage with respect to the unevenness of the underlayer, the contact hole having a high aspect ratio has a uniform thickness. It is possible to form a thin film wiring layer, and it is possible to miniaturize the semiconductor device without causing disconnection due to poor coverage. Furthermore, a refractory metal silicide film that is stoichiometrically appropriate and has good crystallinity can be obtained, and annealing treatment after film formation is unnecessary, and the adhesion with the underlying insulating film is good, Since it is not necessary to form a polycide structure that combines with the silicon film, the process can be simplified.

[Brief description of drawings]

FIG. 1 is a process sectional view illustrating a method for forming a WSi ₂ wiring layer according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an apparatus for growing a WSi ₂ film.

FIG. 3 is a cross-sectional view for explaining a conventional method for forming a wiring layer made of a refractory metal silicide film.

[Explanation of symbols]

10 ... Silicon substrate 12 ... N + type impurity region 14 ... Silicon oxide film 16 ... Contact hole 18 ... WSi ₂ wiring layer 20 ... Decompression CVD reactor 22 ... Heater 24 ... WF ₆ container 26 ... SiHCl ₃ container 28 ... H ₂ cylinder 30 ... MFC 32 ... Wafer 40 ... Silicon substrate 42 ... N + type impurity region 44 ... Silicon oxide film 46 ... Contact hole 48 ... WSi ₂ wiring layer 50 ... TiSi ₂ film

Claims (3)

[Claims] 1. A chemical gas using a halide of a refractory metal as a source gas on a semiconductor substrate, and a gas that generates silicon gas and hydrogen chloride by thermal decomposition or reaction with hydrogen gas as a reaction gas. It has a step of forming a refractory metal silicide film by using a phase growth method, and a step of patterning the refractory metal silicide film into a predetermined shape to form a gate electrode or a wiring layer. Manufacturing method of semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the reaction gas is trichlorosilane, dichlorosilane, trichlorosilane or a mixed gas of dichlorosilane and hydrogen gas, or silicon tetrachloride and hydrogen gas. A method of manufacturing a semiconductor device, which uses a mixed gas. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is covered with an insulating film, and the refractory metal silicide film is directly formed on the insulating film. A method for manufacturing a semiconductor device, comprising: