Patent Application
20060030161
The present invention relates more particularly to semiconductor elements.
At the present moment, the progress in the semiconductor field is remarkable, and LSIs are being converted into ULSIs. And, so as to improve a signal processing speed, forming a fine-grained structure is being developed. Also, copper having a low resistance is selected as wiring conductor materials, the spacing between wiring conductors is filled with a material having a very low dielectric constant, and a trend of extremely thinning a film goes up steadily. A conversion of a gate oxide film, which is currently made of SiO2, into a metal oxide film such as HfO2 has been also studied.
However, even if the above-mentioned idea is adopted, the formation of a fine-grained structure leads to extremely shallow diffusion layers at source-drain regions. Therefore, the resistance is increased, so it is difficult to improve the signal processing speed. In recent years, not only the contact at the source-drain region, but also the resistance of the gate electrode has been perceived as problems, and it has been long wanted to develop new materials.
In order to overcome such problems, metal silicide such as TiSi2 and CoSi2 have been studied.
[Patent document 1] JP-P1994-204173A
However, it is predicted that TiSi2 or CoSi2 has a limit in performance improvement in the future.
In view of such a limitation, the present inventor et al. consider that NiSi must be introduced for the future semiconductor elements.
It is considered that the sputtering technique allows this NiSi thin film to be prepared easily.
The sputtering, however, damages the semiconductor elements physically. Moreover, NiSi may make a reactive consumption of Si, being a base substrate, at a high temperature to turn into NiSi2. Moreover, there is a limit in uniformity of a film having a large area.
For that reason, a technique of forming NiSi films at a low temperature, for example, with a CVD (chemical vapor deposition) process has been waited.
Also, it is predicted that the nickel film will hold an important place as an electrode with a development in micro-machines of recent years.
Thus, the task to be solved by the present invention is to provide a technology of forming silicide (NiSi) films or nickel films with the CVD process, which is capable of solving the above-mentioned problems.
In the course of going aggressively with a research for solving the above-mentioned problems, the present inventor et al. noticed that it was very important to specify what should be employed as configuration materials of the nickel films or the silicide films.
And, as a result of further having continued the research, it has been found out that Ni(PF3)4 is employed very preferably as an Ni source. Moreover, in addition hereto, it has been also found out that in a case of employing chemical compounds represented with SixH(2x+2), where X is an integer of 1 or more, more preferable silicide films can be produced.
The present invention has been achieved based upon such knowledge.
That is, in order to solve the above-mentioned problems, a method is applied of forming a film containing Ni, comprising:
an Ni source supply step of supplying Ni(PF3)4 as an Ni source of said film; and
a decomposition step of decomposing Ni(PF3)4 supplied in said Ni source supply step.
Also, a method is applied of forming a nickel silicide film containing Ni and Si, comprising:
an Ni source supply step of supplying Ni(PF3)4 as an Ni source of said film;
an Si source supply step of supplying SixH(2x+2), where X is an integer of 1 or more, as an Si source of said film;
a decomposition step of decomposing Ni(PF3)4 supplied in said Ni source supply step; and
a decomposition step of decomposing SixH(2x+2) supplied in said Si source supply step.
The present invention provides a film obtained in said film forming methods.
Moreover, the present invention provides a film forming material for forming a film having Ni, wherein an Ni source of said film is Ni(PF3)4.
Also, the present invention provides a film forming material for forming a nickel silicide film having Ni and Si, wherein an Ni source of said film is Ni(PF3)4, and wherein an Si source of said film is SixH(2x+2), where X is an integer of 1 or more.
Moreover, the present invention provides a semiconductor element comprising a film having Ni, wherein Ni(PF3)4 is supplied as an Ni source of said film, and wherein said film is configured by decomposing said supplied Ni(PF3)4.
In particular, the present invention provides a semiconductor element comprising a nickel silicide film having Ni and Si, wherein Ni(PF3)4 is supplied as an Ni source of said film, wherein SixH(2x+2), where X is an integer of 1 or more, is supplied as an Si source of said film, and wherein said film is configured by decomposing said supplied Ni(PF3)4 and SixH(2x+2).
Said Ni(PF3)4 is a reaction product between one or more chemical compounds selected from the group consisting of [C5H5]2Ni, [(CH3)C5H4]2Ni, [(C2H5)C5H4]2Ni, [(i-C3H7)C5H4]2Ni and [(n-C4H9)C5H4]2Ni, and PF3. Its purity is 99% or more.
PF3 is produced in forming said film, that is, in decomposing said Ni(PF3)4. Employing this PF3 for synthesis of Ni(PF3)4 is very convenient.
Accordingly, the present invention further comprises a reaction step of reacting PF3, which is a decomposition product to be produced at the time that Ni(PF3)4 for forming a film is decomposed, with one or more chemical compounds selected from the group consisting of [C5H5]2Ni, [(CH3)C5H4]2Ni, [(C2H5)C5H4]2Ni, [(i-C3H7)C5H4]2Ni and [(n-C4H9)C5H4]2Ni, and employs Ni(PF3)4 obtained in said reaction step for film forming.
Said SixH(2x+2) is, particularly, one or more chemical compounds selected from the group consisting of SiH4, Si2H6, and Si3H8.
In the present invention, the film forming materials are decomposed simultaneously or separately. The decomposition is made by employing at least one of the techniques selected from the group consisting of heat, light, and a hot filament.
The film forming method of the present invention further comprises a reducing agent supply step of supplying a reducing agent (particularly, hydrogen).
The film forming material of the present invention is, particularly, a material for forming a film with the CVD process. Moreover, it is a material for forming the silicide film in the semiconductor elements such as MOSFETs.
In accordance with the present invention, the nickel film or the nickel silicide film is obtained with the CVD process of hardly damaging the substrate. Moreover, there is no fear that NiSi2 is formed through the chemical reaction with Si of the base substrate.
The semiconductor element provided with the film formed by employing Ni(PF3)4 was excellent as compared with the semiconductor element provided with the film formed by employing TiSi2 or CoSi2.
This and other objects, features and advantages of the present invention will become apparent upon a reading of the following detailed description and a drawing, in which:
The film forming method of the present invention is a method of forming the nickel film (or the nickel silicide film). It comprises an Ni(PF3)4 supply step of supplying Ni(PF3)4 as an Ni source of said film, and a decomposition step of decomposing Ni(PF3)4 supplied in said Ni(PF3)4 supply step. It further comprises a reducing agent supply step of supplying a reducing agent (particularly, hydrogen). Also, it further comprises an SixH(2x+2) (where X is an integer of 1 or more, preferably an integer of 10 or less.) supply step of supplying SixH(2x+2) as an Si source of the nickel silicide film, and a decomposition step of decomposing SixH(2x+2) supplied in said SixH(2x+2) supply step. The film forming method of the present invention is, particularly, a method using the CVD process. In the present invention, the film forming materials are decomposed simultaneously or separately. The decomposition is made by employing at least one of the techniques selected from the group consisting of heat, light, and a hot filament.
The film of the present invention is a film obtained by said film forming methods.
The film forming material of the present invention is a film forming material for forming the nickel film (or the nickel silicide film). An Ni source of said film is Ni(PF3)4. An Si source of said nickel silicide film is SixH(2x+2), where X is an integer of 1 or more.
Said Ni(PF3)4 is, particularly, a chemical compound produced by reacting one or more chemical compounds selected from the group consisting of [C5H5]2Ni, [(CH3) C5H4]2Ni, [(C2H5)C5H4]2Ni, [(i-C3H7)C5H4]2Ni and [(n-C4H9)C5H4]2Ni with PF3. Its purity is 99% or more. PF3 is produced at the time of decomposing Ni(PF3)4 in forming the film of the present invention. Accordingly, PF3 produced by this decomposition can be employed for said PF3.
The chemical compound, which is preferable as said SixH(2x+2), is one or more chemical compounds selected from the group consisting of SiH4, Si2H6, and Si3H8.
The film forming material of the present invention is, particularly, a material for forming a film with the CVD process. Moreover, it is a material for forming the silicide film in the semiconductor elements such as MOSFETs.
The element of the present invention comprises the nickel film or the nickel silicide film formed in the above-mentioned film forming methods. Or, the element of the present invention comprises the nickel film or the nickel silicide film formed by employing the above-mentioned film forming materials.
Specific embodiments will be described below.
Ni(PF3)4 was placed in the container 1, and was maintained at 20° C. The decomposition reactor 3 was evacuated in vacuum. The substrate 4 was heated at 150-350° C.
The needle valve 12 was released and the vaporized Ni(PF3)4 was introduced into the decomposition reactor 3 via a conduit. Mixed gas of SiH4 and H2 were introduced at a rate of 20 ml/min as reaction gas at the time of introducing Ni(PF3)4 into the decomposition reactor 3.
As a result, the film was formed on the substrate 4.
When this film was investigated with an XPS (X-ray photoelectron spectroscopy), existence of Ni and Si was confirmed. And, as a result of investigating it with an X-ray, it was confirmed that the film was an NiSi film.
This NiSi film was preferred for the next generation semiconductor elements.
Additionally, Ni(PF3)4 employed in this embodiment is one obtained by reacting [C5H5]2Ni with PF3. A check with a gas chromatograph demonstrated that its purity was 99% or more.
A similar process was performed by employing Ni(PF3)4 obtained by reacting [(CH3)C5H4]2Ni with PF3, Ni(PF3)4 obtained by reacting [(C2H5)C5H4]2Ni with PF3, Ni(PF3)4 obtained by reacting [(i-C3H7)C5H4]2Ni with PF3, and Ni(PF3)4 obtained by reacting [(n-C4H9)C5H4]2Ni with PF3 instead of Ni(PF3)4 obtained by reacting [C5H5]2Ni with PF3, respectively.
The obtained silicide films are ones similar to the above-mentioned silicide film.
The embodiment 2 was carried out similarly to the embodiment 1 with the exception that the reaction gas Si2H6 was employed instead of SiH4.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The embodiment 3 was carried out similarly to the embodiment 1 with the exception that the reaction gas Si3H8 was employed instead of SiH4.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
In the embodiment 1, the decomposition of the chemical compound was made with the heating means. The embodiments 4 and 5 were carried out similarly to the embodiment 1 with the exception that the means of the photo-irradiation or the laser-irradiation was employed instead of this heating means.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
In the embodiment 1, the decomposition of the chemical compound was made with the heating means.
The embodiment 6 was carried out similarly to the embodiment 1 with exception that the decomposition was made with Ni(PF3)4 brought into contact with the hot filament 10 heated at 800° C. or more on the way to the Si substrate 4 instead of this decomposition heating means.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
Ni(PF3)4 is decomposed in the film forming. Ni is deposited on the Si substrate 4, thus allowing the film to be produced. PF3 is recovered into the recovery apparatus/reactor 9. And, PF3 recovered by the recovery apparatus/reactor 9 was reacted with [C5H5]2Ni. This reaction product was purified so that its purity became 99% or more to obtain the reproduced Ni(PF3)4. The embodiment 7 was carried out similarly to the embodiment 1 with the exception that this reproduced Ni(PF3)4 was employed instead of Ni(PF3)4 employed in the embodiment 1.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The embodiment 8 was carried out similarly to the embodiment 7 with the exception that [(CH3)C5H4]2Ni was employed to obtain the reproduced Ni(PF3)4 instead of [C5H5]2Ni.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The embodiment 9 was carried out similarly to the embodiment 7 with the exception that [(C2H5)C5H4]2Ni was employed to obtain the reproduced Ni(PF3)4 instead of [C5H5]2Ni.
As result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The embodiment 10 was carried out similarly to the embodiment 7 with the exception that [(i-C3H7)C5H4]2Ni was employed to obtain the reproduced Ni(PF3)4 instead of [C5H5]2Ni.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The embodiment 11 was carried out similarly to the embodiment 7 with the exception that [(n-C4H9)C5H4]2Ni was employed to obtain the reproduced Ni(PF3)4 instead of [C5H5]2Ni.
As a result, the similar NiSi film was formed. This NiSi film was preferred for the next generation semiconductor elements.
The chemical vapor deposit apparatus of
And, the film was formed on the substrate 4.
When this film was investigated with the XPS, existence of Ni was confirmed. Also, as a result of investigating it with an X-ray, it was confirmed that it was an Ni film.
Particularly, the present invention can be usefully applied in the semiconductor fields.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-231619 | Aug 2004 | JP | national |
