JP4009719B2 - Method for producing nickel silicide film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a nickel silicide film that realizes a metal / semiconductor junction in semiconductor device engineering and the like, and further, a multilayer film structure having the junction structure, and a multilayer film intermediate for realizing the multilayer film structure. Concerning the structure.
[0002]
[Prior art]
In order to realize large-scale integrated circuit technology, it is essential to reduce the contact resistance at the metal / semiconductor interface. In recent years, a nickel silicide film has attracted attention as a metal electrode layer in the above-described laminated structure because of its low resistance and a flat interface and plane. The nickel silicide film is formed by, for example, depositing a nickel film on a p-type silicon substrate by vapor deposition or the like, and then heating the stacked body including the p-type silicon substrate and the nickel film to a predetermined temperature. It is formed by mutually diffusing silicon element and nickel element in the nickel film.
[0003]
[Problems to be solved by the invention]
However, when the nickel silicide film is formed as described above, group III impurities such as B in the p-type silicon substrate are redistributed in the nickel silicide film or in the p-type silicon substrate. As a result, there is a problem in that the impurities hardly exist in the vicinity of the interface, which is the junction region between the nickel silicide film and the p-type silicon substrate, and the contact resistance increases. As a result, the characteristics of the finally obtained semiconductor device show only extremely low device efficiency depending on the large contact resistance between the nickel silicide film and the p-type silicon substrate.
[0004]
It is an object of the present invention to reduce the contact resistance at the metal / semiconductor interface and suppress the deterioration in efficiency of a semiconductor element having such a laminated structure.
[0005]
[Means and Actions for Solving the Problems]
In order to achieve the above object, the present invention provides:
Preparing a predetermined silicon substrate,
On the silicon substrate, forming a silicon base film containing a predetermined impurity and carbon, by forming a nickel film on the silicon base layer, a process of forming a multilayered intermediate structure,
Heat-treating the multilayer intermediate structure to form a nickel silicide film;
The equipped, characterized Rukoto allowed to localize the impurities at the interface between the nickel silicide film and the silicon base layer, to a method for manufacturing a nickel silicide film.
[0006]
The present invention also provides:
A silicon substrate containing predetermined impurities;
A nickel-containing film formed on the silicon substrate;
At least carbon interposed between the silicon substrate and the nickel-containing film;
It is related with the multilayer film intermediate structure characterized by comprising.
[0007]
The inventors of the present invention have intensively studied to achieve the above object. As a result, a nickel-containing film is formed on a silicon substrate containing a predetermined impurity to produce a laminate, and carbon is interposed between the silicon substrate and the nickel-containing film of the laminate. By producing a multilayer film intermediate structure and applying heat treatment to the multilayer film intermediate structure, the silicon element constituting the silicon substrate and the nickel element constituting the nickel-containing film are diffused to each other, In addition to forming a nickel silicide film, the present inventors have found that the impurities contained in the silicon substrate are unevenly distributed in a junction region, that is, an interface between the silicon substrate and the obtained nickel silicide film.
[0008]
As a result, it has been found that the contact resistance between the silicon base material and the nickel silicide film can be sufficiently reduced, and a metal / semiconductor junction having a contact resistance sufficiently small enough for practical use can be realized. Therefore, by constructing a semiconductor element from a multilayer structure including the silicon substrate and the nickel silicide film, the efficiency can be sufficiently improved due to a sufficiently small contact resistance of the metal / semiconductor junction. Can do.
[0009]
In the present invention, the carbon may be present at least between the silicon substrate and the nickel-containing film, and the specific form of existence is not particularly limited. For example, it can be contained on the nickel-containing film side of the silicon substrate, or can be contained so as to be substantially uniform in the thickness direction of the silicon substrate. Moreover, it can be made to exist in the form of a film between the silicon substrate and the nickel-containing film. However, in order to make the impurities in the silicon base material unevenly distributed at the interface between the silicon base material and the nickel silicide film, the carbon is preferably contained in the silicon base material.
[0010]
Further, the silicon substrate can be formed of a predetermined silicon film, or can be formed directly from a predetermined silicon substrate. In the former case, a substrate for supporting the silicon film is required. For example, the substrate is formed on a substrate such as a silicon substrate by using a known film forming method.
[0011]
The silicon substrate preferably contains germanium. Thereby, a nickel silicide film having a composition of Ni (Si _1-α Ge _α ) containing germanium can be formed, and the thermal stability of the nickel silicide film can be further improved. In the case where the silicon substrate does not contain germanium, the nickel silicide film forms a stable NiSi phase under specific heat treatment conditions.
[0012]
Note that the multilayer film structure of the present invention can be obtained through the production method and the multilayer film intermediate structure. The multilayer film structure of the present invention has a metal / semiconductor junction composed of the silicon base material and the nickel silicide film, and the contact resistance is reduced by impurities that are unevenly distributed at the interface between the two. .
Details and other features of the present invention are described below.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are views for explaining a method for producing a nickel silicide film according to the present invention. As shown in FIG. 1, a substrate 11 made of, for example, silicon is prepared, and a carbon-containing silicon base film 12 is formed on the silicon substrate 11 by a predetermined film forming method. Next, predetermined impurities (B, P, As, Sb, Ga, Al, etc.) are contained in the silicon base film 12 using an ion implantation method or the like. At this time, the impurities are localized in the surface layer portion of the silicon base film 12.
[0014]
The inclusion of the impurities can also be performed during the formation of the silicon base film 12. In this case, by appropriately adjusting the implantation conditions of the ion implantation, the impurities can be contained so as to be localized in the surface layer portion of the silicon base film 12 or become substantially uniform in the thickness direction. It can also be made to contain. Further, when the silicon base film 12 is formed using a CVD method or the like, it can be contained using an impurity gas containing the impurity element instead of the ion implantation method. Also in this case, by adjusting the timing of introducing the impurity gas, the impurity gas can be contained so as to be localized in the surface layer portion of the silicon base layer 12 or contained so as to be substantially uniform in the thickness direction. It can also be made.
[0015]
Next, the nickel film 13 is formed on the silicon base film 12 by using a known film forming method, and the multilayer intermediate structure 10 is obtained.
[0016]
Next, the multilayer intermediate structure 10 is subjected to a heat treatment to diffuse the silicon element constituting the silicon base film 12 and the nickel element constituting the nickel film 13 to each other, so that a nickel silicide film 15 as shown in FIG. Form. The heat treatment is performed by heating to 350 ° C. to 850 ° C., for example, in an inert non-oxidizing atmosphere such as a vacuum atmosphere or a nitrogen atmosphere. The heat treatment time is about several seconds to several tens of minutes.
[0017]
At this time, the impurities are unevenly distributed in the surface layer portion 12A of the silicon base film 12 in the vicinity including the interface 16 between the silicon base film 12 and the nickel silicide film 15 because the silicon base film 12 contains carbon. become. Therefore, the contact resistance between the silicon base film 12 and the nickel silicide film 15 is reduced by the presence of the impurity in the vicinity of the interface 16 at a high concentration. As a result, the contact resistance of the metal / semiconductor junction composed of the silicon base film 12 and the nickel silicide film 15 can be sufficiently reduced.
[0018]
Therefore, in the case where a semiconductor element is formed from the multilayered laminated structure 20 having the metal / semiconductor junction as shown in FIG. 2, the efficiency is sufficiently improved based on the low contact resistance of the metal / semiconductor junction. Can do.
[0019]
The nickel film 13 needs to completely react with the silicon base film 12 to form the nickel silicide film 15, but the silicon base film 12 does not need to react with the nickel film 13 as shown in FIG. As such, the lower region may remain. Further, the thicknesses of the nickel film 13 and the silicon base film 12 are appropriately adjusted so that the nickel film 13 and the silicon base film 12 react completely and disappear completely after the nickel silicide film 15 is formed. You can also.
[0020]
The thickness of the nickel silicide film 15 is not particularly limited. However, when the nickel silicide film 15 is used as an electrode layer of a semiconductor element, the thickness is preferably 5 nm to 100 nm.
[0021]
The amount of carbon contained in the silicon base film 12 is not particularly limited, but is preferably 0.001 atomic% to 10 atomic%, and more preferably 0.1 atomic% to 4 atomic%. As a result, the formation of the nickel silicide film 15 and the localization in the vicinity of the interface 16 of the impurity can be balanced, and a metal / semiconductor junction with a lower contact resistance can be realized.
[0022]
Further, the silicon base film 12 can contain germanium. Thus, for example, a NiSi—NiSi ₂ phase can be generated in the nickel silicide film 15 obtained through the above-described heat treatment, and the thermal stability of the nickel silicide film 15 can be improved. Germanium is preferably contained in the silicon underlayer 12 at a ratio of 1 atomic% to 50 atomic%. As a result, the low contact resistance of the metal / semiconductor junction composed of the nickel silicide film 15 and the nickel silicon base film 12 and the thermal stability of the nickel silicide film 15 can be balanced.
[0023]
Further, according to the above manufacturing method, a stable NiSi ₂ phase can be generated in the nickel silicide film 15 even when germanium is not contained in the silicon base film 12.
[0024]
The nickel film 13 can be replaced with a metal other than nickel, such as Au, Ti, Co, Pt, and Pd, depending on the purpose.
[0025]
1 and 2, a silicon substrate 11 is prepared, and a silicon base film 12 containing carbon and impurities is formed on the silicon substrate 11. However, without providing such a silicon base film 12, silicon Carbon and impurities can also be contained directly in the substrate 11. In this case, a p-type or n-type silicon substrate doped with a predetermined impurity is prepared, and carbon is contained in at least a surface layer portion of the silicon substrate by performing ion implantation or the like on the silicon substrate. .
[0026]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
(Example)
First, a (001) silicon substrate was prepared, this silicon substrate was heated to 500 ° C., and a carbon-containing silicon underlayer was formed on the silicon substrate to a thickness of about 400 nm by using a CVD method. At the same time, B as an impurity was doped into the silicon underlayer by introducing an impurity gas. The carbon concentration was 2 × 10 ²⁰ cm ⁻³ and the B impurity concentration was 7 × 10 ²⁰ cm ⁻³ .
[0027]
Next, a nickel film was formed on the silicon base film to a thickness of 20 nm by using an electron gun vapor deposition method, thereby producing a multilayer intermediate structure. Next, the multilayer intermediate structure was heat-treated at 750 ° C. for 30 seconds in a nitrogen atmosphere.
[0028]
The multilayer laminated structure thus obtained was subjected to secondary ion mass spectrometry, and composition analysis in the thickness direction was performed. The results are shown in FIG.
[0029]
(Comparative example)
A multilayer film structure was fabricated in the same manner as in the above example except that carbon was not contained in the silicon base film and the heat treatment temperature was 850 ° C. The multilayer film structure was subjected to secondary ion mass spectrometry, and composition analysis in the thickness direction was performed. The results are shown in FIG.
[0030]
As apparent from FIGS. 3 and 4, when carbon is contained in the silicon base film according to the present invention, the surface layer portion of the silicon base film in the vicinity of the interface between the nickel silicide film and the silicon base film is used. It can be seen that the B impurity is present exceeding the contained B impurity concentration (7 × 10 ²⁰ cm ⁻³ ), and the B impurity is unevenly distributed in the vicinity of the interface. On the other hand, when carbon is not contained in the silicon base film, the localization of B impurities does not occur in the surface layer portion of the silicon base film in the vicinity of the interface between the nickel silicide film and the silicon base film. It can be seen that the B impurity concentration monotonously decreases from the interface toward the surface.
[0031]
Therefore, it can be seen that in the multilayer film structures in the above-described embodiments obtained according to the present invention, a low contact resistance metal / semiconductor junction composed of the nickel silicide film and the silicon base film is realized.
[0032]
As described above, the present invention has been described in detail based on the embodiments of the present invention with specific examples. However, the present invention is not limited to the above contents, and all modifications and changes can be made without departing from the scope of the present invention. It can be changed.
[0033]
【The invention's effect】
As described above, according to the method for producing a nickel silicide film and the multilayer intermediate structure of the present invention, a multilayer structure having a metal / semiconductor junction with reduced contact resistance can be obtained. Therefore, in the case where a semiconductor element is configured from this multilayer film structure, the efficiency of the element can be sufficiently improved.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a method for producing a nickel silicide film of the present invention.
FIG. 2 is also a diagram for explaining a method for producing a nickel silicide film of the present invention.
FIG. 3 is a composition analysis profile in the thickness direction of the multilayer film structure of the present invention by secondary ion mass spectrometry.
FIG. 4 is a composition analysis profile in the thickness direction of a multilayer film structure produced without using a carbon-containing silicon underlayer by secondary ion mass spectrometry.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Multilayer film intermediate structure 11 Silicon substrate 12 Silicon base film 13 Nickel film 15 Nickel silicide film 16 Interface 20 between nickel silicide film and silicon base film 20 Multilayer film structure

Claims (7)

Preparing a predetermined silicon substrate,
On the silicon substrate, forming a silicon base film containing a predetermined impurity and carbon, by forming a nickel film on the silicon base layer, a process of forming a multilayered intermediate structure,
Heat-treating the multilayer intermediate structure to form a nickel silicide film;
The equipped, characterized Rukoto allowed to localize the impurities at the interface between the nickel silicide film and the silicon base film, a method for manufacturing a nickel silicide film. The method for producing a nickel silicide film according to claim 1, wherein the impurity is contained at least in a surface layer portion of the silicon base film . The method for producing a nickel silicide film according to claim 1 , wherein the impurity is uniformly contained in the thickness direction of the silicon base film. The carbon is characterized by the inclusion in a proportion from 0.001 atomic% to 10 atomic% in the silicon substrate in the method for manufacturing a nickel silicide film according to any one of claims 1 to 3. The method for producing a nickel silicide film according to claim 1, wherein the silicon base film further contains germanium in addition to the impurities and carbon .   6. The method for producing a nickel silicide film according to claim 5, wherein the germanium content is 1 atomic% to 50 atomic%. The nickel silicide film is characterized in that it comprises at least one of NiSi phase and NiSi ₂ phase, a method for manufacturing a nickel silicide film according to any one of claims 1-6.

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