WO2009040670A2

WO2009040670A2 - Semiconductor device and manufacturing method therefor

Info

Publication number: WO2009040670A2
Application number: PCT/IB2008/003119
Authority: WO
Inventors: Kotaro Miyatani
Original assignee: Tokyo Electron Limited
Priority date: 2007-09-26
Filing date: 2008-09-25
Publication date: 2009-04-02
Also published as: WO2009040670A3

Abstract

The present invention is a method of forming a barrier layer, which includes an insulator, on a fluorocarbon film formed on a substrate, the method including the steps of producing a plasma from a gas, forming the barrier layer on the fluorocarbon film by using the plasma and exposing the surface of the substrate to the plasma including a nitrogen to dope the nitrogen to the surface of the barrier layer.

Description

SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREFOR

TECHNICAL FIELD

[0001]

This application claims priority to U.S. Provisional Application Serial No. 60/995,432, filed on September 26, 2007, entitled "Manufacturing Method for Semiconductor Device", which is incorporated herein by reference in its entirety.

[0002]

The present invention relates to a semiconductor device contains a low-permittivity film as an interlayer insulator and a manufacturing method therefor.

BACKGROUND OF THE INVENTION

[0003]

In order to realize high integration of semiconductor devices, multilayer wiring structures have been adopted. However, with the progress of the high integration, delay of an electrical signal passes through a wiring (wiring delay) has becoming an issue to the increase in speed of the device operation. Because this wiring delay is proportional to the product of resistance of the wiring and the capacity between wirings, it has been demanded to lower the resistance of the electrode wiring material and lower the permittivity of the interlayer insulator that insulates between each layer, in order to shorten the wiring delay. [0004]

As an interlayer insulator, for example, a film (SiCOH film) having a relative permittivity of about 2.7 and containing porous silica, which has sufficient mechanical strength, carbon, oxygen and hydrogen and a fluorine added carbon film (hereinafter referred as "fluorocarbon film) which is a compound of carbon (C) and fluorine (F) that are lower in relative permittivity compare to the SiCOH film, have been considered to be adopted.

[0005]

This fluorocarbon film is low in oxidation resistance, heat resistance, pressure resistance, stress resistance and so on, thus it is difficult to apply as a single layer to a semiconductor device. For this reason, normally an inorganic insulator, such as silicon oxide that has been used as an interlayer insulator material, is formed on a fluorocarbon film and used as a laminated interlayer insulator.

[0006]

However, there may be a case where the fluorine atom in the fluorocarbon film diffuses into the inorganic insulator on the upper layer resulting in a film peeling of the fluorocarbon film and the inorganic insulator. As techniques for suppressing this film peeling, following conventional techniques have been considered.

[0007]

Unexamined Japanese Patent Application Publication No. Hl 1-087342 discloses a technique for controlling a forming condition of a silicon oxide film 16 to suppress the film peeling between a low permittivity organic film 15 and the silicon oxide film 16. Specifically, disclosed is a technique that the film surface temperate is set to not less than the temperature in which the silicon oxide 16 grows under a reducing atmosphere and not more than 350 ⁰C, a silane gas is used as a material gas supplied to an atmosphere of chemical vapor deposition, and a dinitrogen monoxide gas is used as a gas to oxidize the silane gas.

[0008]

Also, the Unexamined Japanese Patent Application Publication No. 2003-370059 discloses a technique for strengthen the adhesiveness of a low permittivity film and a silicon insulator by an anchor effect form the silicon insulator formed by treatment of roughening the surface of the low permittivity film when forming the silicon insulator on the low permittivity film.

[0009]

Unexamined Japanese Patent Application Publication No. 2004-39704 discloses a technique for strengthen the adhesiveness of a low permittivity film and a capping film (silicon insulator) by forming a texture on the contact faces of each other when forming the capping film on the low permittivity film.

[0010]

Unexamined Japanese Patent Application Publication No. 2004-111688 discloses a technique for performing a plasma process using inert gas or hydrogen gas to an organic film before forming an intermediate film containing a silicon on an organic insulator containing a fluorine. This improves the adhesiveness of both of the organic film and the intermediate film.

[0011]

However, none of the conventional techniques described above disclose the technical thoughts to prevent the film peeling of both in a stand point that the fluorine atom in the fluorocarbon film diffuses into the inorganic insulator. Further, following conventional techniques can be considered as the technique for forming an inorganic insulator on a fluorocarbon film.

[0012]

For example, Unexamined Japanese Patent Application Publication No. H 10- 199976 discloses a technique for employing a laminate structure of a silicon insulator over the fluorocarbon film as an interlayer insulator. In this technique, a technique of applying a heat treatment before burying a conductive material after forming a contact hole is disclosed. However, it does not provide a consideration for the adhesiveness of the fluorocarbon film and the silicon insulator.

[0013]

Unexamined Japanese Patent Application Publication No. 2000-68261 discloses a method for obtaining a semiconductor device in which both the filling in the wiring layer and the flattening the surface are realized in one deposition, that is a technique of laminating an organic film and an inorganic film as a portion of an interlayer insulator to realize flatness, and forming a second insulator 4 after treating the surface of the first insulator 3 with plasma. However, it does not describe nor mention the improvement on the adhesiveness of the organic film and the inorganic film.

[0014]

Unexamined Japanese Patent Application Publication No. 2005-50958 discloses a manufacturing method of a semiconductor device that includes the steps for forming a low permittivity insulator 15, forming a silicon contained insulator 26 on the low permittivity insulator 15, and applying a plasma treatment on the surface of the silicon contained insulator 26. The plasma treatment process is provided to effectively remove amines, N-H group or the like from the surface of the silicon contained insulator 26, but it does not contribute to the adhesiveness of the low permittivity film 15 and the silicon contained insulator 26.

[0015]

Unexamined Japanese Patent Application Publication No. 2004-095611 discloses a technique for forming an etching stopper 78 (inorganic series insulator) on a low permittivity interlayer insulator 77 and applying a heat treatment thereafter. This suppresses the infusion of the moisture into the gate insulator. However, the consideration for the peeling of the interlayer insulator 77 and the etching stopper 78 has not been made.

[0016]

As described above, none of the conventional techniques describe nor mention about the suppression of the film peeling in the aspect of the diffusion of the fluorine atom in the fluorocarbon film in the laminate structure of the fluorocarbon film, which is a low permittivity film, and the inorganic series insulator. For this reason, it is difficult to provide the semiconductor device in which the film peeling of both of fluorocarbon film and the inorganic series insulator is suppressed, even the conventional techniques above are applied.

[0017]

The present invention has been made considering above issues, and there has been a demand for development of the semiconductor device, that is improved the adhesiveness of the inorganic series insulator formed on the fluorocarbon film, and its manufacturing method.

SUMMARY OF THE INVENTION

[0018]

One aspect of the present invention is a method of forming a barrier layer, which includes an insulator, on a fluorocarbon film formed on a substrate, the method including the steps of producing a plasma from a gas, forming the barrier layer on the fluorocarbon film by using the plasma and exposing the surface of the substrate to the plasma including a nitrogen to dope the nitrogen to a surface of the barrier layer.

[0019]

According to the manufacturing method of forming a barrier layer pertaining to the present invention, the insulator is nitrided by exposing the substrate in the nitrogen plasma after forming the insulator on the fluorocarbon film that is different from the fluorocarbon film, thereby the barrier layer containing the barrier can be formed. As a result, the diffusing of the fluorine atom into the barrier layer can be suppressed. Thus the semiconductor device with an improved adhesiveness between the fluorocarbon film and the barrier layer can be manufactured. Also, the inorganic series insulator can efficiently be nitrided.

[0020]

In the method of forming the barrier layer, the gas may include a small amount of nitrogen gas or a small amount of ammonia gas.

[0021]

In the method of forming the barrier layer, the method may include the step of producing a plasma by using a gas excluding a nitrogen gas and the step of forming a barrier layer excluding the nitrogen on the fluorocarbon film by using the plasma prior to forming the barrier layer.

[0022]

In the method of forming the barrier layer, the barrier layer may include a SiCN film, an amorphous carbon film or an amorphous carbon film including a silicon.

[0023]

In the method of forming the barrier layer, the barrier layer may include a compound containing a Si-N bond or a C-N bond.

[0024]

In the method of forming the barrier layer, the insulator may include a nitrogen atom.

[0025]

In the method of forming the barrier layer, the substrate may be heated at the step of exposing the surface of the substrate to the plasma.

[0026]

In the method of forming the barrier layer, the method may include the step of forming a conductive layer on the barrier layer.

[0027]

In the method of forming the barrier layer, the method may further include the steps of forming a contact hole which passes through the barrier layer and the fluorocarbon film and the step of filling the contact hole with a conductive material.

[0028]

In the method of forming the barrier layer, the fluorocarbon film may be formed by using at least one gas selected from the group consisting of C₂F₄, C₂F₆, C₃Fg, C₄F₈, C₆F₆, CH₂F₂ and CHF_3. BRIEF DESCRIPTION OF THE DRAWINGS

[0034]

Figure 1 is a cross-sectional diagram illustrating a semiconductor device pertaining to the embodiment.

Figure 2 is a cross-sectional diagram illustrating a semiconductor device pertaining to the embodiment.

Figure 3 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 4 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 5 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 6 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 7 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 8 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 9 is a cross section diagram illustrating a process of a manufacturing process of the semiconductor device pertaining to the embodiment.

Figure 10 is a cross section diagram illustrating a semiconductor device pertaining to another embodiment.

Figures 11 and 12 show data acquired by measuring fluorine concentrations using substrates as samples, in which a fluorocarbon film and insulator are formed, by using SIMS (secondary ion mass spectrometry).

DETAILED DESCRIPTION OF INVENTION

[0035] (Semiconductor Device)

The semiconductor device of the present invention is characterized by having a substrate, a fluorocarbon film formed on the substrate, a barrier layer formed on the fluorocarbon film and the barrier layer contains a barrier in the film for adjusting a content amount of fluorine atom. An example of the semiconductor device of the present invention will be explained with reference to figure 1. Figure 1 is a cross-section diagram illustrating a semiconductor device pertaining to the present invention.

[0036]

The semiconductor device according to the embodiment includes a substrate 10, a fluorocarbon film 20 and a barrier layer 30 as shown in figure 1.

[0037]

The substrate 10 is a semiconductor substrate. As the substrate 10, for example, a silicon substrate or a semiconductor substrate of various compounds may be used. [0038]

The Fluorocarbon film 20 is formed over the substrate 10. In addition, various semiconductor elements, or other insulators and wirings may be formed between the substrate 10 and the fluorocarbon film 20, although they are not shown in the figure 1. The fluorocarbon film 20 is a film formed from a carbon atom and a fluorine atom. Specifically, the fluorocarbon film 20 is generally a CF series material that can be indicated by (-CF₂-)n. As a material gas for forming a fluorocarbon film with the CVD method, C₂F₄, C₂F₆, C₃F₈, C₄F₈, C₆F₆, CH₂F₂, CHF₃ or the like may be considered.

[0039]

The barrier layer 30 is an insulator consisting of an insulating material different from the fluorocarbon film. Specifically, it is preferably an inorganic series insulator. This barrier layer 30 may be an etching mask or a CMP stopper against the fluorocarbon film. For example, it is preferably a layer selected from a group consist of SiCN, nitride added amorphous carbon, and amorphous carbon which partially contains silicon. The barrier layer 30 may be formed from a single insulating material or a plurality of insulating materials different from each other.

[0040]

Further, the barrier layer 30 pertaining to the embodiment includes a barrier 32 for adjusting the content amount of fluorine atom in the barrier layer 30 (the barrier 32 is included in the barrier layer, thus not shown in the figure). The barrier layer 30 is nitrided in the nitriding process and the surface of the barrier layer contains nitrogen. The surface film of the barrier layer containing the nitrogen can suppress the fluorine atom from the fluorocarbon film 20 from entering and diffusing. Normally, there are some parts of the surface of the barrier layer contain more nitrogen compare to the other parts. In such parts that contain more nitrogen can further suppress the fluorine atom from entering and diffusing.

[0041]

Next, the barrier 32 of the barrier layer 30 will be explained specifically. The barrier 32 is a compound which contains Si-N bond or C-N bond in the layer consisting the barrier layer 30, such as SiCN or nitride added amorphous cabon. Specifically, it is a compound indicated by a formula SiCN That is, in a case of barrier layer 30 consist of SiCN, both the SiN structure and the SiC structures may be mixed. Also, in a case when barrier layer 30 is formed from nitride added amorphous carbon, both the CN structure and amorphous carbon structure may be mixed. Normally, the barrier layer 30 formed from the nitride added amorphous carbon contains a C-C bond, Si-C bond, C-N bond, and Si-N bond. By having such a barrier 32, the barrier layer 30 can suppress the diffusion of the fluorine atom from the fluorocarbon film.

[0042]

Further, in the semiconductor device pertaining to the embodiment, the nitrogen atom content in the film of the barrier layer 30 may be around 5%. On the other hand, nitrogen atom content in the barrier 32 is preferably about 10 to 15%.

[0043] According to the semiconductor device pertaining to the embodiment, the barrier layer 30 having the barrier 32 capable of adjusting the content amount of the fluorine is formed on the fluorocarbon film 20. For this reason, the fluorine in the fluorocarbon film 20 can be suppressed from diffusing into the barrier layer 30. As a result, the semiconductor device that has favorable adhesiveness of the fluorocarbon film 20 and barrier layer 30 can be provided without damaging the barrier layer 30.

[0044]

Next, a semiconductor device pertaining to another embodiment of the present invention is hereinafter explained with the reference to figure 2. The semiconductor device pertaining to another embodiment is a semiconductor device having a conductive section 40, which passes trough the fluorocarbon film 20 and barrier layer 30, in the semiconductor device shown in figure 1. Figure 2 is a cross-section diagram illustrating a semiconductor device pertaining to another embodiment. In addition, the same reference numbers are used for the same members contained in the semiconductor device shown in figure 1 and the explanation of those members will be omitted.

[0045]

The semiconductor device according to the second embodiment has a conductive section 40, which passes through the fluorocarbon film 20 and barrier layer 30 as shown in figure 2. The conductive section 40 is formed in a contact hole 46, which passes through the fluorocarbon film 20 and barrier layer 30. Specifically, the conductive section 40 consist of a barrier film 42 formed in an inner face of the contact hole 46 and a conductive material 44, which fills the contact hole 46 on the barrier film 42. Barrier film 42 is formed from a high-melting point metal compound. A conductive material mainly formed by copper may be used as the conductive material 44. At this time, a main component means that it makes up not less than half of the material that consists the conductive material.

[0046]

Further, a wiring layer 50 is provided on the conductive section 40. The wiring layer 50 is electrically connected to a wiring in a lower layer (not shown) through the conductive section 40. As the wiring layer 50, a copper, a copper alloy, or the like may be used.

[0047]

According to the semiconductor device pertaining to the embodiment, the wiring layer 50 is provided on the barrier layer 30 containing the barrier 32 that is capable of suppressing the diffusion of the fluorine atom. For this reason, the corrosion of the wiring layer 50 attributed to the fluorine atom can be suppressed. As a result, the semiconductor device with a high reliability can be provided.

[0048] (Manufacturing Method of Semiconductor Device)

Next, a manufacturing method of the semiconductor device according to the embodiment will be explained with reference to the figures 3 to 9. Each of the figures 3 to 9 is a cross-section diagram illustrating a process of a manufacturing method of the semiconductor device of the embodiment. [0049]

First, the fluorocarbon film 20 is formed on the substrate 10 as shown in figure 3. The forming method of the fluorocarbon film 20 is performed by, for example, a CVD method. When the CVD method is used, C₂F₄, C₂F₆, C₃F₈, C₄C₈, C₆F₆, CH₂F₂, CHF₃ or the like may be considered as a material gas (film forming gas). In such a case, as a CVD device, a parallel plate type CVD device, or a CVD device utilizes a microwave plasma using RLSA (Radial Line Slot Antenna) may be used. Further, the film thickness of the fluorocarbon film 20 is preferably 90 - 300 run.

[0050]

Next, an insulator 31 (the insulator prior to a nitrogen atom is added)is formed on the fluorocarbon film 20 as shown in figure 3. This insulator 31 is nitrided in a subsequent process and becomes the barrier layer 30. As the insulator 31, an inorganic insulator may be used. For example, SiCN, SiC, SiOC, SiOCH, amorphous carbon or the like may be used. Especially, it is preferable to use the silicon carbide or the amorphous carbon. In this way, the permittivity of the interlayer insulator can be lowered. In addition, in a case when the amorphous carbon is used, the layer is preferably added with a silicon. This is because the strength of the film (barrier layer) can be improved.

[0051]

The insulator 31 may be formed by, for example, the CVD method. Examples of forming a silicon carbide as the insulator 31 and forming an amorphous carbon as the insulator 31 by the CVD method are hereinafter explained.

[0052]

When forming the silicon carbide, it is preferable to use a methyl silane series gas as a film forming gas. Specifically, an alkyl silicon compound, such as, trimethyl silane (SiH(CH₃)₃) or tetramethyl silane (Si(CH₃)₄) (hereinafter referred as TMS), and an inert gas, such as argon (Ar), helium (He), krypton (Kr), neon (Ne) or xenon (Xe), are deposited on a substrate by introducing them into a plasma CVD reaction chamber where electric field exists.

[0053]

Further, the silicon carbide may be a nitrogen added silicon carbide (hereinafter referred as "SiCN"). In such a case, nitrogen gas may be added as forming gas. At this time, the flow rate of the nitrogen gas against the overall forming gas is preferably around 5% - 20% (Usually, the amount of 50 - 200sccm nitrogen gas may be used in the film forming process. Within this range, the suppression effect for the fluorine atom in the fiuorocarbon film 20 can be exerted without damaging the fluorocarbon film 20 with the nitrogen plasma.

[0054]

When forming the amorphous carbon (a-C), a carbon hydride series gas may be used as a material gas. Specifically, a gas having a composition formula indicated by C₃Hb (a is a counting number and b=2^χa-2). In the formula, b may be [2χa+2] or [2χa]. Specifically, it is preferable to use a compound selected from a group consist of CH₄, C₂H₄, C₂H₂, C₄H₆, and the like. Further, in a case of the amorphous carbon, it may be a silicon added amorphous carbon. In a case when the silicon added amorphous carbon(hereinafter referred to as "a-C: Si") is formed, a silane series gas may be added to the film forming gas. As the silane series gas, SiH₄, Si₂H₆, SiH(CH₃)₃, SiH₂(CH₃ )₂, and SiH₃CH₃ can be considered. At this time, the flow rate of the carbon hydride series gas and silane series gas is preferably 100 - 300 seem.

[0055]

Next, as shown in figure 4, the substrate 10 with the insulator 31 formed thereon is exposed to nitrogen plasma. By this, the insulator 31 is nitrided thereby and the barrier layer 30 can be formed as shown in figure 1. That is, this process generates a barrier 32, which controls the content amount of the fluorine atom in the insulting film 31. The process for exposing to the nitrogen plasma (hereinafter also referred as a "nitriding process"), is preferably performed in the atmosphere that is heated. In such a case, the azotizing of the insulator 31 can be accelerated. The heated atmosphere is preferably 300 - 380 °C. In this temperature range, the insulator 31 can favorably be nitrided.

[0056]

Each condition of nitriding process is described as follows. The temperature of nitriding is preferably about 300°C to 380 °C. The film thickness of the barrier layer to be nitrided is preferably about 20nm to lOOnm. As a material for forming the barrier layer, for example, SiCN or silicon added amorphous carbon may be used. In addition, it is insufficient to just expose the barrier layer in a nitrogen atmosphere in the nitriding process and the plasma containing nitrogen needs to be produced. Further, in the nitriding process, any type of gas may be used as the gas for nitriding the barrier layer as long as it contains the nitrogen. And, for example, nitrogen gas (N₂) and ammonia gas (NH₃) may be used.

[0057]

As a device to obtain a nitrogen plasma, a parallel plate type plasma generating device, or a RLSA (Radial Line Slot Antenna) type microwave plasma device may be used. In a case when the RLSA type microwave plasma device is used, a high density plasma can be obtained in a low energy, thus the damage to the insulator 31 is decreased, and the azotizing can be performed efficiently due to the high density.

[0058]

An example of a condition for the nitrogen plasma generation will be hereinafter explained. In a case of the parallel plate type plasma generating device, the pressure is preferably, 5 - 30Pa; input power is preferably 1500 - 3000W; and the nitrogen gas flow rate is preferably 200 - 1000 seem, and further preferably 200 - 500 seem. In a case when the microwave plasma device is used, the condition same as the parallel plate type plasma generating device may be used. By these processes above, the semiconductor device pertaining to the present invention (refer to figure 1) can be manufactured.

[0059]

Next, a forming process for the semiconductor device having a conductive section 40 which passes through the fluorocarbon film 20 and the barrier layer 30 of this semiconductor device (refer to figure 2) will be explained with reference to the figures 5 to 9. Figures 5 to 9 are cross-section diagrams illustrating a manufacturing process of the semiconductor device referred in the figure 2.

[0060]

First, a mask Ml having an opening within a predetermined range is formed on the barrier layer 30 as shown in figure 5. At this time, a resist may be used as the mask Ml.

[0061]

Next, the barrier layer 30 is etched by using the mask Ml as shown in figure 6. Either wet etching or dry etching may be used for the etching of the barrier layer 30.

[0062]

Next, as shown in figure 7, the fluorocarbon film 20 is etched by using the barrier layer 30, which has a formed pattern. The etching of the fluorocarbon film 20 may be performed by the dry etching. By this process, the contact hole 46, which passes through the fluorocarbon film 20 and the barrier layer 30, is formed.

[0063]

Next, the conducting section, which electrically connects the wirings on the upper and lower layers, is formed in the contact hole 46. In this embodiment, in a case when the conductive section 40 is structured by the barrier film 42 formed on the inner face of the contact hole 46 and the conductive material 44 (refer to figure 2) is explained.

[0064]

First, the barrier film 42, which covers the inner face of the contact hole 46, is formed as shown in figure 8. The barrier film 42 serves to suppress the metal atom, which constitutes the conductive material formed later, from diffusing into the interlayer insulator (the fluorocarbon film 20 or the like), and to improve the adhesiveness of the conductive material. As the barrier film 42, Ta, and TaN, may be used. The film thickness of the barrier film 42 is 5 - 20nm. The barrier film 42 can be formed by a sputtering method and so on.

[0065]

Next, the contact hole 46 is filled as shown in figure 8, and further a conductive material layer 43 is formed so as to cover the barrier layer 30. As the conductive material layer 43, for example, it is preferably a layer mainly formed by copper. As a method for forming the conductive material layer 43, for example, a plating method may be employed. When forming the conductive material layer 43 by the plating method, first an underlying layer (seed layer) is formed on the barrier layer, thereafter overall conducive material layer is formed by an electrolytic plating or an electroless plating.

[0066]

Next, as shown in figure 9, the conductive material layer 43 and barrier film 42 are removed until the upper face of the barrier layer 30 is exposed. The removal of the conductive material layer 43 and barrier film 42 is performed by the CMP (Chemical Mechanical Polishing) method. By the process above, the conductive section 40 is formed.

[0067]

Next, the wiring layer 50 is formed on the conductive section 40. The wiring layer can be formed by, first, forming a wiring material layer (not shown) on the barrier layer 30, and then patterning the layer. By these processes above, the semiconductor device referenced in the figure 2 can be manufactured.

[0068]

In addition, the contact formed by the single damascene method has been explained in the embodiment, but it is not limited to the single damascene method. The conductive section 40 and the wiring layer 50 may be integrated into a unit in order to be formed by the dual damascene method as show in figure 10.

[0069]

According to the manufacturing method of the semiconductor device pertaining to the embodiment, the barrier layer 30 having the barrier 32 capable of suppressing the diffusion of the fluorine atom can be formed by exposing the substrate to nitride the insulator 31 after forming the insulator 31 on the fluorocarbon film 20. Thereby, the semiconductor device that is capable of maintaining the adhesiveness of the fluorocarbon film 20 and the barrier layer 30, as well as, capable of suppressing the corrosion of the wiring 50, can be manufactured. As a result, the semiconductor device with a high reliability can be manufactured.

[0070]

Next, explained is experimental data, in which an insulator is nitrided and the diffusion of fluorine atom is suppressed by exposing a substrate in the nitrogen plasma after forming the insulator on a fluorocarbon film. Figures 11 and 12 are showing data of measurement using substrates as samples, in which a fluorocarbon film and insulator is formed, by using SIMS (secondary ion mass spectrometry). Here, the fluorine element concentration is measured against the depth direction of a substrate after forming the film. Figures 11 and 12 use a substrate as a sample, in which a SiC film is formed on a fluorocarbon film.

[0071]

Figure 11 and 12 are showing data acquired by measuring fluorine element concentration using a substrate as a sample, in which a SiC film is formed on a fluorocarbon film, by using SIMS (secondary ion mass spectrometry). Figure 11 uses the sample which is formed without a process of exposing the substrate in the nitrogen plasma after forming the SiC film. On the other hand, figure 12 uses the sample which is formed by performing the process of exposing the substrate in the nitrogen plasma after forming the SiC film. In figures 11 and 12, the vertical axis indicates the element concentration of fluorine and horizontal axis indicates the depth of substrate after forming the film. In the both figures, the areas where surrounded by the doted lines indicate the fluorine concentration in the SiC film. [0072]

By looking at the area indicated by the doted line in figure 11 , it can be noted that the fluorine diffuses deep into the SiC layer from the surface. Meanwhile, by looking at the at the area indicated by the doted line in figure 12, it can be noted that the fluorine diffuses only to the shallow portion of the SiC film (the portion close to the fluorocarbon layer), thus the diffusion of fluorine is comparably prevented in the mid layer portion and the surface portion of the SiC film. As a result of comparing these data, it can be concluded that the insulator is nitrided and the diffusion of fluorine atom is suppressed when the process of exposing the substrate in the nitrogen plasma is performed after forming the SiC film. When the diffusion of fluorine atom is suppressed, the adhesiveness of the fluorocarbon film and insulator can be maintained and the corrosion of wiring layer can be suppressed, thereby, it is effective in manufacturing semiconductor devices with high reliability.

INDUSTRIAL APPLICABILITY

[0075]

In addition, in a case when forming a barrier layer in the present invention, the film formed by using a gas adding the nitrogen in advance and the film adding the nitrogen after forming the film by nitriding have different nitrogen concentration profiles. In the film formed by using a gas adding the nitrogen in advance, the nitrogen is contained evenly across the top and bottom of the film. However, in the film adding the nitrogen after forming the film by nitriding, higher amount of nitrogen contained on the surface and hardly no nitrogen contained in the interface with the fluorocarbon film ( Example of the depth of the nitrogen contained in not more than IOnm from the surface).

[0076]

Further, because the barrier layer with different nitrogen content can be formed as described above, a stacked structure of films with different nitrogen concentrations (for example, a stacked structure of SiC film and SiN film) can be formed. However, normally the distribution of nitrogen concentration is consecutive in the barrier layer.

Claims

CLAIMSWhat is claimed is:

1. A method of forming a barrier layer, which includes an insulator, on a fluorocarbon film formed on a substrate, the method comprising the steps of : producing a plasma from a gas; forming the barrier layer on the fluorocarbon film by using the plasma; and exposing the surface of the substrate to the plasma including a nitrogen to dope the nitrogen to a surface of the barrier layer.

2. The method of forming the barrier layer of claim 1 , wherein the gas includes a small amount of nitrogen gas or a small amount of ammonia gas.

3. The method of forming the barrier layer of claim 1, the method further comprising: producing a plasma by using a gas excluding a nitrogen gas and forming a barrier layer excluding the nitrogen on the fluorocarbon film by using the plasma by using a gas excluding a nitrogen gas prior to the step of forming the barrier layer on the fluorocarbon film.

4. The method of forming the barrier layer of claim 1, wherein the barrier layer includes a SiCN film, an amorphous carbon film or an amorphous carbon film including a silicon.

5. The method of forming the barrier layer of claim 1, wherein the barrier layer includes a compound containing a Si-N bond or a C-N bond.

6. The method of forming the barrier layer of claim 1, wherein the insulator includes a nitrogen atom.

7. The method of forming the barrier layer of claim 1, wherein the substrate is heated at the step of exposing the surface of the substrate to the plasma.

8. The method of forming the barrier layer of claim 1, the method further comprising: forming a conductive layer on the barrier layer.

9. The method of forming the barrier layer of claim 1, the method further comprising the steps of: forming a contact hole which passes through the barrier layer and the fluorocarbon film; and filling the contact hole with a conductive material.

10. The method of forming the barrier layer of claim 1, wherein the fluorocarbon film is formed by using at least one gas selected from the group consisting Of C₂F₄, C₂F₆, C₃F₈, C₄F₈, C₆F₆, CH₂F₂ and CHF_3.