JPH0869994A - Production of semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a method for producing a semiconductor in which the reliability of device can be enhanced by removing the native oxide without using any hydrofluoric based aqueous solution or gas and depositing a silicide of high melting point metal having low content of fluorine in the pretreatment of an underlying substrate for depositing the silicide of a high melting point metal. CONSTITUTION: In a method for depositing tungsten silicide 34 on a wafer 12 to produce a semiconductor device, the wafer 12 is exposed to hydrogen plasma 28 prior to deposition of the tungsten silicide 34 in order to remove native oxide grown on the wafer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment method in a semiconductor device manufacturing process, and more particularly to a semiconductor device manufacturing method for removing a natural oxide film or the like on an underlying substrate.

[0002]

2. Description of the Related Art With the recent miniaturization of semiconductor devices, reduction of wiring resistance and contact resistance, and physical stability by heat treatment are required for electrodes and wiring materials. Therefore, when forming a film to be an electrode or wiring, it is important to sufficiently remove dust, contaminants, natural oxide film, etc. on the surface of the base.

As a pretreatment for depositing an electrode material or the like, conventionally, wet etching using a hydrofluoric acid (HF) aqueous solution or surface treatment for removing a natural oxide film or the like by HF gas containing water has been the mainstream. there were. In forming the refractory metal silicide film, typically a tungsten silicide (WSi _x) is also such a deposition pretreated with HF-based solution or gas has been carried out.

[0004]

However, in the above-described conventional method for manufacturing a semiconductor device in which film forming pretreatment is performed using an HF-based aqueous solution or gas, the surface from which the natural oxide film has been removed is contained in HF. There was a problem that the fluorine (F) that had been used remained. Therefore, if the gate electrode using the refractory metal silicide film is formed after this pretreatment, the remaining F is taken into the gate oxide film by the heat treatment in the subsequent step, the gate capacitance is lowered, and the current driving capability of the transistor is reduced. There was a problem such as the decrease.

When forming a refractory metal silicide film in a contact hole having a small opening diameter, if an HF-based aqueous solution is used to remove the natural oxide film, water may remain in the contact hole. There is a problem that the natural oxide film is not sufficiently removed and the contact resistance between the deposited electrode material and the underlying substrate increases. Further, when the refractory metal silicide film is deposited by the CVD method, SiF _x is generated simultaneously with the film formation. Therefore, when continuously depositing the WSi _x film in the same chamber, SiF _x has remaining inside the chamber that occurs during film formation, then SiF _x in when performing film formation However, there is a problem that the F concentration in the refractory metal silicide film increases due to the incorporation of F.

Further, when the F concentration in the refractory metal silicide film increases, when the source / drain diffusion layer is formed in the gate electrode by self-alignment by boron (B) ion implantation, the refractory metal is subjected to heat treatment in a subsequent step. B implanted in the gate electrode due to the effect of F in the silicide film
However, there is a problem that the threshold voltage of the transistor is changed due to the increase of the diffusion of the element and reaching the channel region.

The object of the present invention is to remove the natural oxide film without using an HF-based aqueous solution or gas, and to form a refractory metal silicide film containing a small amount of F, thereby improving device reliability. It is an object of the present invention to provide a method of manufacturing a semiconductor device, which can improve the manufacturing cost.

[0008]

The above object is to provide a method for manufacturing a semiconductor device in which a refractory metal silicide film is formed on a base substrate, before forming the refractory metal silicide film or a film forming the material. And a step of exposing the underlying substrate to hydrogen plasma to remove a natural oxide film grown on the underlying substrate.

In the method of manufacturing a semiconductor device described above, a plasma of argon, helium, or nitrogen gas is used instead of the plasma of hydrogen to achieve the method of manufacturing a semiconductor device. In addition, in the above-described method for manufacturing a semiconductor device, a method for manufacturing a semiconductor device is characterized in that a gate electrode is formed of the refractory metal silicide film.

Further, in the above-described method of manufacturing a semiconductor device, the method of manufacturing a semiconductor device is characterized in that an electrode of a contact hole portion is formed of the refractory metal silicide film. Further, in the above-described method for manufacturing a semiconductor device, the refractory metal silicide film is a tungsten silicide film, which is achieved.

[0011]

According to the present invention, when forming a gate electrode using a refractory metal silicide film, the natural oxide film on the wafer is removed by using plasma of hydrogen or an inert gas, and the residual oxide remains in the chamber. Since the F that has been removed is removed, F does not remain on the surface from which the native oxide film has been removed, and the F concentration contained in the refractory metal silicide film deposited thereafter can be reduced. As a result, the F concentration taken into the gate oxide film can be reduced, so that the reduction of the gate capacitance can be prevented.

Further, even when the source / drain diffusion layers are formed in the gate electrode by self-alignment by B ion implantation, the F concentration contained in the refractory metal silicide film can be reduced, so that the F electrode concentration in the gate electrode is reduced. It is possible to prevent the threshold voltage of the transistor from changing because the implanted B does not reach the channel region due to the heat treatment in the later process.

Further, when the refractory metal silicide electrode is formed in the contact hole, the wafer is pretreated by using hydrogen plasma, and the refractory metal silicide film is deposited immediately after that, so that the inside of the contact hole is naturally formed. The oxide film is sufficiently removed, the adhesion is improved, and the contact resistance can be suppressed low.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of a semiconductor device manufacturing apparatus according to this embodiment, and FIG. 2 is a view showing a semiconductor device manufacturing method according to this embodiment.

A susceptor 14 for mounting a wafer 12 is provided in the chamber 10 for film formation. The susceptor 14 has a built-in heater (not shown) that heats the wafer 12 during film formation. At a position facing the susceptor 14, a counter electrode 16 for applying a high frequency to the susceptor 14 to generate plasma is arranged.

The chamber 10 further includes the chamber 1
An exhaust pipe 18 for evacuating the inside of the chamber 0, a SiH ₄ supply pipe 20 for supplying monosilane (SiH ₄ ) serving as a silicon source when forming a WSi _x film, and a tungsten hexafluoride (WF _{6 serving as} a tungsten source). ) H ₂ supply pipe 24 is connected for supplying the hydrogen (H ₂₎ for performing WF ₆ supply pipe 22, and a film formation pretreatment supplies. Susceptor 1
A high frequency power source 26 for generating plasma is connected to the counter electrode 4 and the counter electrode 16.

Next, a method of manufacturing the semiconductor device according to this embodiment will be described. First, the wafer 12 to be deposited is placed on the susceptor 14, and the inside of the chamber 10 is decompressed by a vacuum pump (not shown) connected to the exhaust pipe 18.
Next, the temperature of the susceptor 14 is raised to the temperature at which the WSi _x film is formed, and then H _{2 is} supplied from the H ₂ supply pipe 24.
Gas is introduced and high frequency is applied between the susceptor 14 and the counter electrode 16 to generate H ₂ plasma 28 (FIG. 2).
(A)).

In a reducing gas atmosphere such as hydrogen gas, 10
A method of removing a natural oxide film on the surface of a silicon substrate by performing a high temperature heat treatment at about 00 ° C. is generally known, but in the present invention, the H ₂ plasma 28 has a similar function. That is, the natural oxide film grown on the wafer 12 can be removed by the energy of the H ₂ plasma 28 instead of removing the natural oxide film by causing a reduction reaction by thermal energy.

Pretreatment with H ₂ plasma 28 has additional advantages. That is, Si on the inner wall of the chamber 10
When F _x 30 is adsorbed, SiF _x 30 can also be removed (FIG. 2 (b)). Since the SiF _x 30 is transformed into the form of HF 32 or the like by the H ₂ plasma 28, the SiF _x 30 is easily removed from the inner wall of the chamber 10. As a result, the F concentration in the deposited WSi _x film can be reduced. The SiF _x 30 is generated during the growth of the WSi _x film, and when a plurality of wafers 12 are continuously formed, the SiF _x 30 is adsorbed to the inner wall of the chamber 10 during the previous film formation.

In this way, the pretreatment of the wafer 12 and the plasma cleaning of the inner wall of the chamber 10 can be performed at the same time. Then, after stopping the introduction of the H ₂ gas, the SiH ₄ gas from the SiH ₄ supply pipe 20, WF
₆ WF ₆ gas is introduced through the supply pipe 22. As a result, WF ₆ and SiH ₄ react on the wafer 12 to form the WSi _x film 34 (FIG. 2C). In this way WS
By depositing the i _x film 34, pretreatment and deposition can be performed in the same chamber, so that the F concentration in the film can be reduced and the film can be formed immediately after the natural oxide film is removed.

As described above, according to this embodiment, since the pretreatment of the wafer 12 using H ₂ plasma enables the natural oxide film to be removed immediately before the WSi _x film 34 is formed, it is deposited. Adhesion of the WSi _x film 34 is improved, and film peeling can be prevented. Further, the natural oxide film is removed without using the HF-based aqueous solution and the chamber 10 is used.
Since the residual F inside was removed, the deposited WSi _x film 3
The F concentration contained in 4 can be reduced. As a result, the F concentration taken into the gate oxide film can be reduced, so that the reduction of the gate capacitance can be prevented.

Further, even if the source / drain diffusion layers are formed in the gate electrode by self-alignment by B ion implantation, the F concentration contained in the refractory metal silicide film can be reduced, so that the F electrode concentration in the gate electrode is reduced. It is possible to prevent the implanted B from reaching the channel region due to the heat treatment in the subsequent step and changing the threshold voltage of the transistor.

Further, the WSi _x film 3 is formed in the contact hole.
4 is formed, a pretreatment of the wafer 12 with H ₂ plasma 28 is performed, and immediately after that, a WSi _x film 34 is deposited, so that the natural oxide film in the contact hole is sufficiently removed and adhered. And the contact resistance can be kept low. Various modifications are possible without being limited to the above-mentioned embodiment of the present invention.

For example, in the above embodiment, H ₂ plasma was used in the step of removing the natural oxide film.
The native oxide film may be removed using plasma of an inert gas such as r), helium (He), nitrogen (N ₂ ). However, in this case, the removal method is not a chemical reaction but a physical removal method. Further, in the above embodiment, the pretreatment for forming the WSi _x film is shown as an example, but MoSi _x , TiS
i _x, it can be TaSi _x, etc., be another refractory metal silicide film to obtain a similar effect.

Further, in the above embodiment, an example of depositing the refractory metal silicide film is shown, but it may be applied to a process of salicide formation, for example, silicidation after depositing the refractory metal film. In this case, this can be achieved by subjecting the underlying substrate to H ₂ plasma treatment before depositing the refractory metal film.

[0026]

As described above, according to the present invention, when forming a gate electrode using a refractory metal silicide film, the natural oxide film on the wafer is removed by using plasma of hydrogen or an inert gas. At the same time, since F in the chamber is removed, F does not remain on the surface from which the natural oxide film has been removed, and the F concentration contained in the refractory metal silicide film deposited thereafter can be reduced. As a result, the F concentration taken into the gate oxide film can be reduced, so that the reduction of the gate capacitance can be prevented.

Also, when the source / drain diffusion layers are formed in the gate electrode by self-alignment by B ion implantation, the F concentration contained in the refractory metal silicide film can be reduced, so It is possible to prevent the threshold voltage of the transistor from changing because the implanted B does not reach the channel region due to the heat treatment in the later process.

Further, when the refractory metal silicide electrode is formed in the contact hole, the wafer is pretreated with hydrogen plasma, and the refractory metal silicide film is deposited immediately after that, so that the natural inside of the contact hole is formed. The oxide film is sufficiently removed, the adhesion is improved, and the contact resistance can be suppressed low.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a semiconductor device manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[Explanation of symbols]

10 ... Chamber 12 ... Wafer 14 ... Susceptor 16 ... Counter electrode 18 ... Exhaust pipe 20 ... SiH ₄ supply pipe 22 ... WF ₆ supply pipe 24 ... H ₂ supply pipe 26 ... High frequency power supply 28 ... H ₂ plasma 30 ... SiF _x 32 ... HF 34 ... WSi ₂ film

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device in which a refractory metal silicide film is formed on a base substrate, wherein the base substrate is subjected to hydrogen plasma before the refractory metal silicide film or a film forming the material is formed. And a step of removing the natural oxide film grown on the underlying substrate, the method of manufacturing a semiconductor device. 2. The method for manufacturing a semiconductor device according to claim 1, wherein instead of the plasma of hydrogen, argon, helium,
Alternatively, a method for manufacturing a semiconductor device, which uses plasma of nitrogen gas. 3. The method of manufacturing a semiconductor device according to claim 1, wherein a gate electrode is formed of the refractory metal silicide film. 4. The method of manufacturing a semiconductor device according to claim 1, wherein an electrode of a contact hole portion is formed of the refractory metal silicide film. 5. The method of manufacturing a semiconductor device according to claim 1, wherein the refractory metal silicide film is a tungsten silicide film.