JP2004247474A - Semiconductor device, manufacturing method thereof, and film forming method - Google Patents

Abstract

Semiconductor device capable of suppressing diffusion of a dopant impurity added to a gate electrode into a channel region and suppressing deterioration of transistor performance when a High-k insulating film is used as a gate insulating film, and a method of manufacturing the same I will provide a.
Kind Code: A1 A gate including a nitrogen-containing high dielectric constant film formed on a silicon substrate by a chemical vapor deposition method using an organometallic material and a nitrogen source material containing silicon and nitrogen as constituent elements. It has an insulating film 15 and a gate electrode 16 formed on the gate insulating film 15.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device using a high dielectric constant film as a gate insulating film and a method for manufacturing the same, and relates to a semiconductor device using a high dielectric constant film capable of suppressing diffusion of dopant impurities added to a gate electrode as a gate insulating film. The present invention relates to an apparatus, a method for manufacturing the same, and a method for forming such a high dielectric constant film.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a gate insulating film of a MIS (Metal Insulator Semiconductor) transistor, a silicon oxide film-based insulating film such as a silicon oxide film or a silicon oxynitride film has been used. However, in recent years, miniaturization and high performance of LSI have been advanced, and the thickness of the gate insulating film has also become extremely thin. For this reason, it is becoming difficult for a silicon oxide film-based insulating film to secure a sufficient withstand voltage due to a gate leak current caused by a tunnel effect. From such a background, various studies have been made on a structure and a material that can secure desired transistor characteristics, obtain a sufficient withstand voltage, and sufficiently suppress a gate leak current as a gate insulating film.
[0003]
In recent years, as a gate insulating film capable of suppressing a gate leak current and securing a sufficient withstand voltage, Al₂O₃, ZrO₂, HfO₂(See, for example, Patent Document 1 and the like). By using an insulating film having a higher dielectric constant than a silicon oxide-based insulating film, the thickness of a gate insulating film for securing equivalent MIS capacitance can be increased. Therefore, by using such a high dielectric constant material, it is expected that the withstand voltage is improved while realizing equivalent transistor characteristics.
[0004]
However, when a High-k insulating film is simply used as a gate insulating film, the following difficulties are known. That is, in a heat treatment in a manufacturing process of a semiconductor device or the like, in a conventional High-k insulating film, diffusion of boron added as a dopant impurity to a gate electrode made of polysilicon cannot be suppressed in a semiconductor substrate. As a result, boron added to the gate electrode diffuses to the channel region in the semiconductor substrate, and the performance of the transistor deteriorates.
[0005]
As a method for preventing the diffusion of boron into the channel region, a method using a high-k insulating film to which nitrogen is added as a gate insulating film is known.
[0006]
For example, in a CVD method, nitrogen monoxide (NO) or ammonia (NH) is used as a nitrogen source together with an organic metal material serving as a metal source of a high dielectric constant material.₃) Is known to form a High-k insulating film to which nitrogen is added.
[0007]
Also, a ZrN film is formed by a sputtering method, and the ZrO film to which nitrogen is added is formed by thermally oxidizing the ZrN film.₂A method of forming a (ZrON) film as a gate insulating film has been proposed (see Non-Patent Document 1). Alternatively, a HfN film is formed by a sputtering method, and the HfN film is thermally oxidized to form a HfO film to which nitrogen is added.₂(HfO_xN_yA method of forming a film as a gate insulating film has been proposed (see Non-Patent Document 2).
[0008]
[Patent Document 1]
JP 2001-230247 A
[Non-patent document 1]
M. Koyama et al. , “Thermally Stable Ultra-Thin Nitrogen Incorporated ZrO.₂  Gate Dielectric Prepared by Low Temperature Oxidation of ZrN "International Electron Devices Meetings Technical Digest (2001), p. 459-462.
[Non-patent document 2]
C. S. Kang et al. , "Improved Thermal Stability and Device Performance of Ultra-thin (EOT <10 angstrom) Gate Dielectric MOSFETs by using Hafnium Oxynitride (EOT <10 angstrom)_xN_y) "2002 Symposium on VLSI Technology Digest of Technical Papers (2001), p. 146-147.
[0009]
[Problems to be solved by the invention]
However, first, NO and NH are used as nitrogen sources in the CVD method.₃In the method of adding nitrogen to the High-k insulating film by adding, it is difficult to efficiently add a necessary amount of nitrogen to the High-k insulating film.
[0010]
In addition, in the method of adding nitrogen to a High-k insulating film by using the conventional sputtering method, it is necessary to first form a nitride film by a sputtering method and then oxidize the nitride film. Therefore, it has been difficult to efficiently form a High-k insulating film to which a nitride film is added. In addition, since a sputtering method is used for film formation, it is difficult to form a gate insulating film with good coverage.
[0011]
An object of the present invention is to provide a semiconductor device capable of suppressing diffusion of a dopant impurity added to a gate electrode into a channel region and suppressing deterioration of transistor performance when a High-k insulating film is used as a gate insulating film. It is to provide a manufacturing method thereof.
[0012]
[Means for Solving the Problems]
The object is to form a nitrogen-containing high dielectric constant film formed on a semiconductor substrate and made of a nitrogen-added high dielectric constant film, and a nitrogen-free high dielectric constant film made of a nitrogen-doped high dielectric constant film. And a gate electrode formed on the gate insulating film.
[0013]
In addition, the above object is achieved by forming a high dielectric constant film to which nitrogen is added by a chemical vapor deposition method using a metal organic material and a nitrogen source material containing silicon and nitrogen as constituent elements on a semiconductor substrate. And a step of forming a gate electrode on the nitrogen-containing high-dielectric-constant film.
[0014]
Further, the above object is to form a high dielectric constant film to which nitrogen is added by a chemical vapor deposition method using an organometallic material and a nitrogen source material containing silicon and nitrogen as constituent elements. This is achieved by a characteristic film forming method.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
The film forming method according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing the structure of a film forming apparatus used in the film forming method according to the present embodiment. The film forming method according to the present embodiment is to form a nitrogen-containing high dielectric constant film made of an aluminum oxide film to which nitrogen is added by MOCVD (Metal Organic Chemical Vapor deposition). .
[0016]
First, the film forming apparatus used in the film forming method according to the present embodiment will be explained with reference to FIG.
[0017]
As shown, a silicon substrate 10 on which a nitrogen-containing high dielectric constant film is to be formed is placed on a susceptor 28 having a heater function in a reaction chamber 26 where the film is formed. Above the susceptor 28, a shower head 30 from which a source gas is jetted is provided. A turbo-molecular pump 32 and a dry pump 34 are connected to the reaction chamber 26 so that the pressure in the reaction chamber 26 can be controlled.
[0018]
A pipe 36 for introducing a source gas or the like into the reaction chamber 26 is connected to the upper side of the shower head 30 of the reaction chamber 26. The pipe 36 includes a pipe 36a for introducing nitrogen gas and oxygen gas, a pipe 36b connected to a cylinder 38a storing an organic metal material used as an Al source, and silicon and nitrogen used as nitrogen sources. And a pipe 36c connected to a cylinder 38b in which a compound containing the compound is stored. The cylinders 38a and 38b are provided with pipes 40a and 40b, respectively, into which nitrogen gas for supplying the raw materials in the cylinders 38a and 38b into the reaction chamber 26 by a bubbling method. The pipes 36, 40a, and 40b are provided with mass flow controllers (MFCs) 42a, 42b, and 42c for controlling the flow rates of the source gas and the like into the reaction chamber, respectively.
[0019]
The raw materials for the MOCVD method include TTBAl (tri (tertiarybutyl)) aluminum and Al [(t-C₄H₉)₃]) And BTBAS (bis (tert-butylylamino) silane, (t-C₄H₉NH)₂SiH₂) Is used.
[0020]
Next, the film forming method according to the present embodiment will be explained with reference to FIG.
[0021]
First, TTBAl and BTBAS stored in the cylinders 38a and 38b, respectively, are introduced into the reaction chamber 26 by a bubbling method using nitrogen gas as a carrier by introducing nitrogen gas from the pipes 40a and 40b into the cylinders 38a and 38b, respectively. Introduce. In addition, TTBAl and BTBAS are introduced into the reaction chamber 26 by a bubbling method, and oxygen gas is introduced into the reaction chamber 26 from a pipe 36a.
[0022]
The film forming conditions include, for example, a flow rate of nitrogen gas used for bubbling for supplying TTBAl from the cylinder 38a into the reaction chamber 26 of 100 to 300 cc / min, and bubbling for supplying BTBAS from the cylinder 38b into the reaction chamber 26. The flow rate of the nitrogen gas used is 50 to 200 cc / min. The temperature of the cylinders 38a and 38b during film formation is set to 20 to 60 ° C., and the temperature of the pipes 36a and 36b is set to 25 to 70 ° C., respectively, to prevent the raw materials from sticking to the inner walls of the pipes 36a and 36b. The pressure in the reaction chamber 26 is 65 Pa, the film forming temperature is 500 ° C., and the film forming rate is 1.7 nm / min.
[0023]
TTBAl and BTBAS introduced into the reaction chamber 26 and jetted toward the silicon substrate 10 via the shower head 30 cause a decomposition reaction. Thus, a nitrogen-containing high dielectric constant film made of an aluminum oxide film to which nitrogen is added is deposited on the silicon substrate 10.
[0024]
Thus, a nitrogen-containing high dielectric constant film made of an aluminum oxide film to which nitrogen is added is formed on the silicon substrate 10.
[0025]
As described above, the film formation method according to the present embodiment uses a nitrogen-containing aluminum oxide film formed of a nitrogen-added aluminum oxide film by a CVD method using BTBAS which is a compound containing silicon and nitrogen as constituent elements as a nitrogen source. There is a main feature in forming a dielectric constant film.
[0026]
As described above, conventionally, a high-dielectric-constant film to which nitrogen is added, such as a ZrON film or an HfON film, needs to be formed using a two-step process of forming a nitride film by sputtering and oxidizing the nitride film. . For this reason, it has been difficult to efficiently add a required amount of nitrogen to the high dielectric constant film. In addition, since the film was formed by the sputtering method, it was difficult to form a high dielectric constant film with good coverage. Furthermore, it has been difficult to form a thin film on the order of several nm uniformly.
[0027]
On the other hand, when a high dielectric constant film is formed by a CVD method, NO or NH is simply used as a nitrogen source.₃It was difficult to form a high dielectric constant film to which nitrogen was sufficiently added only by adding. This is considered to be due to the strong affinity between the metal constituting the high dielectric constant film and oxygen.
[0028]
On the other hand, in the film forming method according to the present embodiment, a nitrogen-containing high dielectric constant film made of an aluminum oxide film to which nitrogen is added is formed by a CVD method using an organometallic material as an Al source and BTBAS as a nitrogen source. Has formed. The present inventor has confirmed that nitrogen can be sufficiently added to an aluminum oxide film with high efficiency by using BTBAS as a nitrogen source.
[0029]
In the film forming method according to the present embodiment, since a compound containing silicon as a constituent element is used as the nitrogen source, the nitrogen-containing high dielectric constant film to be formed contains a trace amount of silicon.
[0030]
As described above, according to the present embodiment, the nitrogen-containing high dielectric constant film made of the aluminum oxide film to which nitrogen is added by the CVD method using BTBAS, which is a compound containing silicon and nitrogen as constituent elements, as a nitrogen source. Is formed, a nitrogen-containing high dielectric constant film made of an aluminum oxide film to which nitrogen is sufficiently added can be efficiently formed.
[0031]
In the present embodiment, BTBAS is supplied into the reaction chamber 26 together with TTBAl as the Al source, but the timing of supplying BTBAS into the reaction chamber 26 may be appropriately set. For example, a film is formed in a state where only TTBAl is supplied without supplying BTBAS, and subsequently, a film is formed in a state where BTBAS is supplied together with TTBAl. Subsequently, film formation is performed in a state where only TTBAl is supplied without supplying BTBAS again. Thus, by supplying BTBAS into the reaction chamber 26 at a desired timing, nitrogen can be added to a position of a predetermined depth of the aluminum oxide film to be finally formed. That is, a stacked film of an aluminum oxide film to which nitrogen is not added and an aluminum oxide film to which nitrogen is added can be formed.
[0032]
In this embodiment, the case where the aluminum oxide film to which nitrogen is added is described as an example. However, as described above, by using BTBAS as a nitrogen source, various high dielectric constants to which nitrogen is added can be used. A film can be formed. For example, a hafnium aluminate (HfAlO) film, a hafnium oxide (HfO₂) Film, zirconium oxide (ZrO)₂) Film, titanium oxide (TiO)₂) Film, tantalum oxide (Ta)₂O₅Also when a high dielectric constant film such as a film is formed by the MOCVD method, by adding BTBAS as a nitrogen source, these high dielectric constant films to which nitrogen has been added can be formed. In addition, a high dielectric constant film made of an oxide of a Group IIIA element, that is, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or the like is formed by MOCVD. Also in the case of forming a film, by adding BTBAS as a nitrogen source, these high dielectric constant films to which nitrogen is added can be formed.
[0033]
[Second embodiment]
The semiconductor device according to the second embodiment of the present invention and the method for fabricating the same will be described with reference to FIGS. FIG. 2 is a sectional view showing the structure of the semiconductor device according to the present embodiment, and FIGS. 3 and 4 are process sectional views showing the method of manufacturing the semiconductor device according to the present embodiment.
[0034]
First, the structure of the semiconductor device according to the present embodiment will be explained with reference to FIG.
[0035]
A gate insulating film 15 is formed on a silicon substrate 10 by sequentially stacking a silicon oxide film 12 and a nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added. On the gate insulating film 15, a gate electrode 16 made of a polysilicon film is formed. A side wall insulating film 18 is formed on the side wall of the gate electrode 16.
[0036]
In the silicon substrate 10, a dopant impurity is introduced at a low concentration in a self-aligned manner with the gate electrode 16, thereby forming a low concentration diffusion layer 20 a. Further, in the silicon substrate 10, a dopant impurity is introduced at a high concentration in a self-alignment manner with the side wall insulating film 18 and the gate electrode 16, thereby forming a high concentration diffusion layer 20b. The low concentration diffusion layer 20a and the high concentration diffusion layer 20b constitute a source / drain diffusion layer 22.
[0037]
Thus, a MOS transistor having the gate electrode 16 and the source / drain diffusion layer 22 is formed on the silicon substrate 10.
[0038]
The semiconductor device according to the present embodiment is mainly characterized in that it has a gate insulating film 15 including a nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added. The nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added is formed by the film forming method according to the first embodiment, that is, the MOCVD method using a compound containing silicon and nitrogen as constituent elements as a nitrogen source. And nitrogen is sufficiently added to the film. With such a nitrogen-containing high dielectric constant film 14, boron added as a dopant impurity to the gate electrode 16 can be sufficiently suppressed from diffusing into the channel region in the silicon substrate 10 by heat treatment, and the performance of the transistor can be improved. Deterioration can be suppressed.
[0039]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIGS.
[0040]
First, an element region (not shown) is defined on the silicon substrate 10 by, for example, a normal STI (Shallow Trench Isolation) method.
[0041]
Next, the SC-2 washing solution (HCl / H₂O₂By cleaning the surface of the silicon substrate 10 using the liquid mixture, a silicon oxide film 12 having a thickness of 1 nm is formed on the surface of the silicon substrate 10 (see FIG. 3A).
[0042]
Next, the nitrogen-containing high-dielectric-constant film 14 made of a nitrogen-added aluminum oxide film having a thickness of 0.5 to 3 nm is formed on the silicon oxide film 12 by the film forming method according to the first embodiment (FIG. 3). (B)).
[0043]
In the method for fabricating the semiconductor device according to the present embodiment, nitrogen is added by the film forming method according to the first embodiment, that is, MOCVD using BTBAS, which is a compound containing silicon and nitrogen as constituent elements, as a nitrogen source. The main feature is that the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film is formed. Since the nitrogen-containing high-dielectric-constant film 14 made of an aluminum oxide film sufficiently doped with nitrogen can be formed, boron added to the gate electrode 16 made of a polysilicon film as a dopant impurity is removed by heat treatment. Diffusion to a channel region in the transistor can be sufficiently suppressed, and deterioration of transistor performance can be suppressed.
[0044]
After the nitrogen-containing high dielectric constant film 14 is formed, a polysilicon film 44 is formed on the nitrogen-containing high dielectric constant film 14 by, for example, a CVD method.
[0045]
Next, a resist film 46 is formed on the polysilicon film 44, and the resist film 46 is left on the region where the gate electrode is to be formed by photolithography (see FIG. 3C).
[0046]
Next, using the resist film 46 as a mask, the polysilicon film 44 is patterned by etching to form the gate electrode 16 made of the polysilicon film 44 (see FIG. 3D).
[0047]
Then, using the gate electrode 16 as a mask, boron ions (B⁺Is ion-implanted to form an impurity-doped region 48a in the silicon substrate 10 which becomes the low-concentration diffusion layer 20a having the LDD structure by self-alignment with the gate electrode 16 (see FIG. 4A). Instead of boron ions, boron fluoride ions (BF₂ ⁺) May be ion-implanted.
[0048]
Next, the resist film 46 used as a mask when patterning the gate electrode 16 is removed.
[0049]
Next, a heat treatment by, for example, an RTA method is performed to activate the dopant impurities implanted into the impurity doped region 48a. Thus, by activating the dopant impurities in the impurity-doped region 48a, the low concentration diffusion layer 20a is formed.
[0050]
Next, a silicon oxide film 50 is formed on the entire surface by, for example, a CVD method (see FIG. 4B).
[0051]
Thereafter, the silicon oxide film 50 is anisotropically etched by, for example, RIE (Reactive Ion Etching: Reactive Ion Etching) to form a sidewall insulating film 18 on the side wall of the gate electrode 16 (see FIG. 4C). ).
[0052]
Then, using the gate electrode 16 and the sidewall insulating film 18 as a mask, boron ions are implanted to form an impurity-doped region 48b to be the high-concentration diffusion layer 20b having the LDD structure (see FIG. 4D). At this time, boron is also added to the gate electrode 16 as a dopant impurity.
[0053]
Next, heat treatment by, for example, an RTA method is performed to activate boron in the gate electrode 16 and the impurity-doped region 48b. Thus, by activating boron as a dopant impurity in the impurity doped region 48b, the high concentration diffusion layer 20b is formed, and the source / drain diffusion of the LDD structure composed of the low concentration diffusion layer 20a and the high concentration diffusion layer 20b is performed. Layer 22 is formed.
[0054]
Thus, the semiconductor device according to the present embodiment shown in FIG. 2 is manufactured.
[0055]
In the method for fabricating the semiconductor device according to the present embodiment, the nitrogen-containing high-dielectric-constant film 14 made of an aluminum oxide film to which nitrogen is added is used as the gate insulating film 15 by the MOCVD method using BTBAS as the nitrogen source. It is formed between the electrode 16. For this reason, at the time of high-temperature processing in a manufacturing process such as heat treatment for activating dopant impurities, diffusion of boron added to the gate electrode 16 to a channel region formed in the silicon substrate 10 is suppressed. be able to.
[0056]
As described above, according to the present embodiment, the nitrogen-containing high dielectric constant film 14 made of the aluminum oxide film to which nitrogen is added is formed by the MOCVD method using the organometallic material as the Al source and BTBAS as the nitrogen source. Therefore, it is possible to efficiently form the nitrogen-containing high dielectric constant film 14 to which nitrogen is sufficiently added. Accordingly, it is possible to suppress the boron added as a dopant impurity to the gate electrode 16 made of the polysilicon film from diffusing into the channel region in the silicon substrate 10 and suppress the deterioration of the transistor performance.
[0057]
[Third embodiment]
The semiconductor device according to the third embodiment of the present invention and the method for fabricating the same will be described with reference to FIGS. FIG. 5 is a sectional view showing the structure of the semiconductor device according to the present embodiment, and FIG. 6 is a graph showing the depth profile of the material composition of the gate insulating film in the semiconductor device according to the present embodiment. The same components as those of the semiconductor device and the method of manufacturing the same according to the second embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0058]
The basic structure of the semiconductor device according to the present embodiment is substantially the same as that of the semiconductor device according to the second embodiment. The semiconductor device according to the second embodiment is different from the semiconductor device according to the second embodiment in that a nitrogen-containing high dielectric The difference is that a nitrogen-containing high dielectric constant film 52 composed of a nitrogen-added hafnium aluminate (HfAlO) film is used instead of the refractive index film 14. That is, as shown in FIG. 5, a gate insulating film 53 formed by sequentially stacking a silicon oxide film 12 and a nitrogen-containing high dielectric constant film 52 made of a hafnium aluminate film to which nitrogen is added on a silicon substrate 10. Is formed.
[0059]
The semiconductor device according to the present embodiment is characterized mainly in that it has a gate insulating film 53 including a nitrogen-containing high dielectric constant film 52 made of a hafnium aluminate film to which nitrogen is added. The nitrogen-containing high dielectric constant film 52 made of a hafnium aluminate film to which nitrogen is added is the same as the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added in the second embodiment. Since the film is formed by a MOCVD method using a compound containing nitrogen and nitrogen as constituent elements, nitrogen is sufficiently added to the film. With such a nitrogen-containing high dielectric constant film 52, boron added as a dopant impurity to the gate electrode 16 can be sufficiently suppressed from diffusing into a channel region in the silicon substrate 10, and deterioration of transistor performance can be prevented. Can be suppressed.
[0060]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained.
[0061]
The semiconductor device according to the present embodiment can be manufactured in substantially the same manner as that according to the second embodiment, except that the nitrogen-containing high dielectric constant film 52 is formed. Hereinafter, the method for forming the nitrogen-containing high dielectric constant film 52 in the semiconductor device according to the present embodiment will be described.
[0062]
As the source gas for forming the nitrogen-containing high dielectric constant film 52, TTBAl was used as an Al source in the same manner as the film forming method according to the first embodiment used in the method for manufacturing a semiconductor device according to the second embodiment. BTBAS (bis (tertiarybutylamino) silane, (t-C₄H₉NH)₂SiH₂) Is used. Further, as an Hf source, TTBHf (tri (tertarybutyl) hafnium, Hf [(t−C₄H₉)₃]) Is used.
[0063]
At the time of film formation, TTBAl and BTBAS are supplied into the reaction chamber 26 by a bubbling method in the same manner as in the case of the film formation method according to the first embodiment, and TTBHf is supplied to the reaction chamber by a bubbling method using nitrogen gas as a carrier. 26. Further, TTBAl, BTBAS, and TTBHf are introduced into the reaction chamber 26 by a bubbling method, and oxygen gas is introduced into the reaction chamber 26 from a pipe 36a.
[0064]
The deposition conditions are, for example, a flow rate of nitrogen gas used for bubbling for supplying TTBAl into the reaction chamber of 30 to 300 cc / min, and a flow rate of nitrogen gas used for bubbling for supplying BTBAS into the reaction chamber of 50 to 200 cc. / Min, the flow rate of nitrogen gas used for bubbling for supplying TTBHf into the reaction chamber is 50 to 500 cc / min, the pressure in the film formation chamber is 65 Pa, the film formation temperature is 500 ° C., and the film formation rate is 1.7 nm / min. And
[0065]
As described above, the method for fabricating the semiconductor device according to the present embodiment includes the hafnium aluminate film to which nitrogen is added by the MOCVD method using BTBAS, which is a compound containing silicon and nitrogen as constituent elements, as a nitrogen source. The main feature is that the nitrogen-containing high dielectric constant film 52 is formed.
[0066]
The inventors of the present application have confirmed that nitrogen can be sufficiently added to a hafnium aluminate film with high efficiency by using BTBAS as a nitrogen source. FIG. 6 is a graph showing the depth profile of the material composition of the nitrogen-containing high dielectric constant film 52 in the semiconductor device according to the present embodiment, which is measured by RBS (Rutherford Backscattering Spectrometry).
[0067]
The range from the depth of about 0 to 3.5 nm on the horizontal axis of the graph shown in FIG. 6 is the nitrogen-containing high dielectric constant film 52. The silicon oxide film 12 has a depth of about 3.5 to 4.75 nm. The silicon substrate 10 has a depth of about 4.74 nm or more. As is clear from the graph, it can be seen that nitrogen is almost uniformly added at a maximum nitrogen concentration of 4 at% (atomic percentage) in the thickness direction of the nitrogen-containing high dielectric constant film 52 made of a hafnium aluminate film.
[0068]
Thus, by forming the nitrogen-containing high dielectric constant film 52 made of a hafnium aluminate film to which nitrogen is sufficiently added, boron added as a dopant impurity to a gate gate electrode made of a polysilicon film is heat-treated. It is possible to sufficiently suppress the diffusion into the channel region in.
[0069]
As described above, according to the present embodiment, a nitrogen-containing high dielectric constant made of a hafnium aluminate film to which nitrogen is added by MOCVD using an organometallic material as an Al source and a Hf source and using BTBAS as a nitrogen source. Since the film 52 is formed, it is possible to efficiently form the nitrogen-containing high dielectric constant film 14 to which nitrogen is sufficiently added. Accordingly, it is possible to suppress the boron added as a dopant impurity to the gate electrode 16 made of the polysilicon film from diffusing into the channel region in the silicon substrate 10 and suppress the deterioration of the transistor performance.
[0070]
[Fourth embodiment]
The semiconductor device and the method for fabricating the same according to the fourth embodiment of the present invention will be explained with reference to FIG. FIG. 7 is a sectional view showing the structure of the semiconductor device according to the present embodiment. The same components as those of the semiconductor device and the method of manufacturing the same according to the second embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0071]
The basic structure of the semiconductor device according to the present embodiment is substantially the same as the semiconductor device according to the second embodiment shown in FIG. The main features of the semiconductor device according to the present embodiment are, as shown in FIG. 7, a silicon oxide film 12, a nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added, and further, nitrogen is added. And a high dielectric constant film 56 made of a normal aluminum oxide film. It should be noted that the phrase "no nitrogen is added" in the specification of the present application means that nitrogen is not intentionally added to the film. For example, a film formed without adding a nitrogen source or other source material such as BTBAS during film formation by the MOCVD method is a film to which nitrogen is not added.
[0072]
In the semiconductor device according to the second embodiment, the gate insulating film 15 having the silicon oxide film 12 and the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added is formed. In this case, the addition of nitrogen to the nitrogen-containing high dielectric constant film 14 causes problems such as generation of fixed charges at the interface with the nitrogen-containing high dielectric constant film 14, and the high dielectric constant material is used for the gate insulating film. It is also assumed that the advantages that have been used are not fully utilized.
[0073]
On the other hand, the semiconductor device according to the present embodiment has a high dielectric constant film 56 made of a normal aluminum oxide film to which nitrogen is not added, on the nitrogen-containing high dielectric constant film 14 to which nitrogen is added. I have. With such a laminated structure, first, similarly to the case of the second embodiment, diffusion of boron added to the gate electrode 16 into the channel region is suppressed by the nitrogen-containing high dielectric constant film 14 to which nitrogen is added. be able to. Further, the advantage of using a high-dielectric-constant material for the gate insulating film can be fully utilized by the separately formed ordinary high-dielectric-constant film 56 to which nitrogen is not added.
[0074]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained.
[0075]
The semiconductor device according to the present embodiment can be manufactured in substantially the same manner as that according to the second embodiment. Here, a laminated structure of the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added and the high dielectric constant film 56 made of a normal aluminum oxide film can be formed as follows. .
[0076]
First, in the same manner as in the second embodiment, a nitrogen-containing high dielectric constant made of a nitrogen-added aluminum oxide film is formed by MOCVD using TTBAl and BTBAS as a raw material, using the film forming method according to the first embodiment. The rate film 14 is formed.
[0077]
Subsequent to the formation of the nitrogen-containing high-dielectric-constant film 14, the supply of BTBAS to the reaction chamber 26 of the film forming apparatus was stopped and the supply of the nitrogen source was shut off, and the MOCVD method using TTBAl as a raw material was performed. An aluminum oxide film is formed. Thus, in the reaction chamber 26 of the same film forming apparatus as that on which the nitrogen-containing high-dielectric-constant film 14 to which nitrogen is added is formed, the high-dielectric-constant film 56 made of a normal aluminum oxide film to which nitrogen is not added. Are continuously formed.
[0078]
As described above, in the reaction chamber 26 of the same film forming apparatus, the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added and the high dielectric constant film 56 made of a normal aluminum oxide film are used. A laminated structure is formed.
[0079]
As described above, according to the present embodiment, the nitrogen content of the aluminum oxide film formed by the MOCVD method using the organometallic material as the Al source and BTBAS as the nitrogen source is efficiently and sufficiently doped with nitrogen. Since the high dielectric constant film 56 to which nitrogen is not added is formed on the dielectric constant film 14, the diffusion of boron added as a dopant impurity to the gate electrode 16 made of the polysilicon film into the channel region is performed by the nitrogen-containing high dielectric constant. On the other hand, the advantage of using a high-dielectric-constant material for the gate insulating film can be fully utilized by the ordinary high-dielectric-constant film 56 to which nitrogen is not added, while suppressing by the dielectric film 14.
[0080]
In this embodiment, the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added and the normal high dielectric constant film 56 are continuously formed in the reaction chamber 26 of the same film forming apparatus. However, both need not necessarily be formed continuously. That is, the nitrogen-containing high dielectric constant film 14 and the high dielectric constant film 26 may be formed using separate film forming apparatuses.
[0081]
In the present embodiment, the high dielectric constant film 56 made of an aluminum oxide film to which nitrogen is not added is formed on the nitrogen-containing high dielectric constant film 14 made of an aluminum oxide film to which nitrogen is added. The dielectric constant film 56 is not limited to the aluminum oxide film, and another high dielectric constant film to which nitrogen is not added may be formed.
[0082]
Further, in the present embodiment, the normal high dielectric constant film 56 to which nitrogen is not added is formed on the nitrogen-containing high dielectric constant film 14, but the nitrogen-containing high dielectric constant film 14 and the nitrogen-free high dielectric constant film are not added. The upper and lower portions of the normal high dielectric constant film 56 may be exchanged. That is, as shown in FIG. 8, a normal high dielectric constant film 56 to which nitrogen is not added is formed on the silicon oxide film 12, and the nitrogen-containing high dielectric constant film 14 is formed on the normal high dielectric constant film 56. May be formed.
[0083]
In the present embodiment, the semiconductor device according to the second embodiment has a stacked structure of an aluminum oxide film to which nitrogen is added and an aluminum oxide film to which nitrogen is not added. Also in the device, the same laminated structure as that according to the present embodiment may be formed. That is, a stacked structure of a hafnium aluminate film to which nitrogen is added and a hafnium aluminate film to which nitrogen is not added may be formed.
[0084]
[Fifth Embodiment]
The semiconductor device according to the fifth embodiment of the present invention and the method for fabricating the same will be described with reference to FIG. FIG. 9 is a sectional view showing the structure of the semiconductor device according to the present embodiment. The same components as those of the semiconductor device and the structure according to the second embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0085]
The basic structure of the semiconductor device according to the present embodiment is substantially the same as the semiconductor device according to the second embodiment shown in FIG. The main feature of the semiconductor device according to the present embodiment is that, as shown in FIG. 9, the nitrogen-containing high dielectric constant films 14a and 14b made of a nitrogen-added aluminum oxide film are formed of a normal aluminum oxide film to which nitrogen is not added. The point is that it is formed above and below the high dielectric constant film 58 made of. That is, the semiconductor device according to the present embodiment has the silicon oxide film 12, the nitrogen-containing high dielectric constant film 14a to which nitrogen is added, the normal high dielectric constant film 58 to which nitrogen is not added, and the nitrogen added. A gate insulating film 59 is formed by sequentially stacking the nitrogen-containing high dielectric constant film 14b. The nitrogen-containing high dielectric constant films 14a and 14b are formed by the film forming method according to the first embodiment, that is, the MOCVD method using a compound containing silicon and nitrogen as constituent elements as a nitrogen source. Sufficient nitrogen is added.
[0086]
In the semiconductor device according to the present embodiment, as in the case of the second embodiment, the diffusion of boron added to the gate electrode 16 into the channel region is performed above and below the high dielectric constant film 58, The high-permittivity films 14a, 14b further effectively suppress the high-permittivity material, while the high-permittivity film 58 formed between the nitrogen-containing high-permittivity films 14a, 14b reduces the high-permittivity material to a gate insulating film. The advantage used in the above can be fully utilized.
[0087]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained.
[0088]
The semiconductor device according to the present embodiment can be manufactured in substantially the same manner as that according to the second embodiment. Here, the laminated structure of the high dielectric constant film 58 made of a normal aluminum oxide film and the nitrogen-containing high dielectric constant films 14a and 14b made of an aluminum oxide film to which nitrogen is added formed above and below the film is the fourth embodiment. As in the case of the embodiment, in the MOCVD method, by appropriately switching the presence or absence of addition of BTBAS as a nitrogen source, it can be formed as follows.
[0089]
First, in the same manner as in the second embodiment, a nitrogen-containing high dielectric constant made of a nitrogen-added aluminum oxide film is formed by MOCVD using TTBAl and BTBAS as a raw material, using the film forming method according to the first embodiment. The rate film 14a is formed.
[0090]
Subsequent to the formation of the nitrogen-containing high dielectric constant film 14a, only the supply of BTBAS to the reaction chamber 26 of the film forming apparatus was stopped and the supply of the nitrogen source was shut off, and the MOCVD method using TTAl as a raw material was performed. A high dielectric constant film 58 made of an aluminum oxide film is formed.
[0091]
Next, in the same manner as in the second embodiment, a nitrogen-containing high dielectric constant film 14b made of a nitrogen-added aluminum oxide film is formed by MOCVD using TTBAl and BTBAS as raw materials.
[0092]
As described above, in the reaction chamber 26 of the same film forming apparatus, the high dielectric constant film 58 made of a normal aluminum oxide film and the nitrogen-containing high A laminated structure with the dielectric films 14a and 14b is continuously formed.
[0093]
In this embodiment, the nitrogen-containing high dielectric constant films 14a and 14b made of an aluminum oxide film to which nitrogen is added and the normal high dielectric constant film 56 are continuously formed in the reaction chamber 26 of the same film forming apparatus. However, it is not always necessary to form them continuously. That is, the nitrogen-containing high dielectric constant films 14a and 14b and the high dielectric constant film 26 may be formed using separate film forming apparatuses.
[0094]
In this embodiment, a high dielectric constant film 58 made of an aluminum oxide film to which nitrogen is not added is formed between the nitrogen-containing high dielectric constant films 14a and 14b made of an aluminum oxide film to which nitrogen is added. However, the high dielectric constant film 58 is not limited to the aluminum oxide film, and another high dielectric constant film to which nitrogen is not added may be formed.
[0095]
Further, in the present embodiment, in the semiconductor device according to the second embodiment, a stacked structure of an aluminum oxide film to which nitrogen is not added and an aluminum oxide film to which nitrogen is not formed formed thereover is formed. In the semiconductor device according to the third embodiment, the same stacked structure as that according to the present embodiment may be formed. That is, a stacked structure of a hafnium aluminate film to which nitrogen is not added and a hafnium aluminate film to which nitrogen is added formed above and below the film may be formed.
[0096]
[Modified embodiment]
The present invention is not limited to the above embodiment, and various modifications are possible.
[0097]
For example, in the above embodiment, the case where nitrogen is added to the aluminum oxide film or the hafnium aluminate film has been described as an example. However, a high dielectric constant film to which nitrogen can be added by applying the present invention is not limited thereto. Not something. For example, hafnium oxide (HfO₂), Zirconium oxide (ZrO)₂), Titanium oxide (TiO)₂), Tantalum oxide (Ta)₂O₅The present invention may be applied to a high-dielectric-constant film made of (1) to add nitrogen. Further, the present invention is applied to a high dielectric constant film made of an oxide of a group IIIA element, that is, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or the like. Nitrogen may be added by application. Alternatively, nitrogen may be added to a high dielectric constant film made of an aluminate containing these metals according to the present invention.
[0098]
In the above embodiment, the case where BTBAS is used as the nitrogen source for forming the nitrogen-added high dielectric constant film by the MOCVD method has been described as an example, but the nitrogen source material is not limited to BTBAS. Any compound containing silicon and nitrogen as constituent elements can be used as a nitrogen source material for forming a nitrogen-added high dielectric constant film. For example, TDMASi (tetradimethylaminosilane) or the like can be used as a nitrogen source material.
[0099]
Further, the metal source such as Al for forming the nitrogen-added high dielectric constant film by the MOCVD method is not limited to TTBAl and TTBHf shown in the above embodiment. For example, an organic metal material such as TEAl (triethylaluminum) and TDMAHf (tetradimethylaminohafnium) can be used as a metal source.
[0100]
In the above-described embodiment, the case where boron is ion-implanted as a dopant impurity into the gate electrode 16 after patterning the polysilicon film on the gate electrode 16 has been described. Boron may be added. That is, when a polysilicon film is formed by the CVD method, diborane (B₂H₆) May be added to the gate electrode 16 to add boron as a dopant impurity.
[0101]
In the above embodiment, the gate electrode 16 made of the polysilicon film is formed, but the material and structure of the gate electrode 16 are not limited to this. For example, a metal silicide may be stacked on a polysilicon film, and the gate electrode 16 may have a polycide structure. Further, a metal film may be stacked on the polysilicon film, and the gate electrode 16 may have a polymetal structure.
[0102]
Further, in the above embodiment, the case where the silicon oxide film 12 is formed at the interface between the silicon substrate 10 and the nitrogen-containing high dielectric constant films 14, 14b or the high dielectric constant film 56 has been described. Need not be formed. Alternatively, instead of the silicon oxide film 12, a silicon oxide film-based insulating film such as a silicon nitride oxide film may be formed.
[0103]
(Supplementary Note 1) A nitrogen-containing high dielectric constant film formed of a nitrogen-added high dielectric constant film and a nitrogen-free high dielectric constant film of a nitrogen-free high dielectric constant film formed on a semiconductor substrate. And a gate electrode formed on the gate insulating film.
[0104]
(Supplementary Note 2) The semiconductor device according to Supplementary Note 1, wherein the gate insulating film has the nitrogen-containing high dielectric constant film above and below the nitrogen-free high dielectric constant film, respectively.
[0105]
(Supplementary Note 3) The semiconductor device according to supplementary note 1 or 2, wherein the gate insulating film further includes a silicon oxide-based insulating film at an interface with the semiconductor substrate.
[0106]
(Supplementary Note 4) In the semiconductor device according to any one of Supplementary Notes 1 to 3, the nitrogen-containing high dielectric constant film includes an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a tantalum oxide film, or a hafnium aluminate film. A semiconductor device, characterized in that is added.
[0107]
(Supplementary Note 5) The semiconductor device according to any one of Supplementary Notes 1 to 4, wherein boron is added to the gate electrode.
[0108]
(Supplementary Note 6) Nitrogen formed of a high dielectric constant film to which nitrogen is added by a chemical vapor deposition method using a metal organic material and a nitrogen source material containing silicon and nitrogen as constituent elements on a semiconductor substrate. A method for manufacturing a semiconductor device, comprising: a step of forming a high-k film containing nitrogen; and a step of forming a gate electrode on the high-k film containing nitrogen.
[0109]
(Supplementary Note 7) In the method for manufacturing a semiconductor device according to Supplementary Note 6, the nitrogen-free high dielectric constant film made of the high dielectric constant film to which nitrogen is not added is provided on the semiconductor substrate or the nitrogen containing high dielectric constant film. A method for manufacturing a semiconductor device, further comprising a step of forming.
[0110]
(Supplementary Note 8) The method of manufacturing a semiconductor device according to supplementary note 7, wherein the nitrogen-containing high dielectric constant film and the nitrogen-free high dielectric constant film are continuously formed in the same reaction chamber. Manufacturing method.
[0111]
(Supplementary Note 9) In the method of manufacturing a semiconductor device according to any one of Supplementary Notes 6 to 8, the step of forming the gate electrode includes forming the gate electrode to which boron is added. Method.
[0112]
(Supplementary Note 10) The method of manufacturing a semiconductor device according to any one of Supplementary Notes 6 to 9, wherein the nitrogen source material is BTBAS.
[0113]
(Supplementary Note 11) In the method of manufacturing a semiconductor device according to any one of Supplementary Notes 6 to 10, wherein the nitrogen-containing high dielectric constant film is an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a tantalum oxide film, or a hafnium aluminate. A method for manufacturing a semiconductor device, wherein nitrogen is added to a film.
[0114]
(Supplementary Note 12) A high dielectric constant film to which nitrogen is added is formed by a chemical vapor deposition method using an organometallic material and a nitrogen source material containing silicon and nitrogen as constituent elements. Film forming method.
[0115]
(Supplementary note 13) The film forming method according to supplementary note 12, wherein the nitrogen source material is BTBAS.
[0116]
(Supplementary Note 14) The film formation method according to supplementary note 12 or 13, wherein the high dielectric constant film is an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a tantalum oxide film, or a hafnium aluminate film. Film formation method.
[0117]
【The invention's effect】
As described above, according to the present invention, a nitrogen-added high dielectric constant film is formed by a chemical vapor deposition method using a metal organic material and a nitrogen source material containing silicon and nitrogen as constituent elements. Since the film is formed, a high dielectric constant film to which nitrogen is sufficiently added can be efficiently formed.
[0118]
Further, according to the present invention, a nitrogen-added high dielectric constant is formed on a semiconductor substrate by a chemical vapor deposition method using a metal organic material and a nitrogen source material containing silicon and nitrogen as constituent elements. Since a nitrogen-containing high dielectric constant film made of a film is formed and a gate electrode is formed on the nitrogen-containing high dielectric constant film, boron added to the gate electrode as a dopant impurity diffuses into a channel region in a semiconductor substrate. , And deterioration of the performance of the transistor can be suppressed.
[0119]
Further, according to the present invention, a semiconductor substrate to which nitrogen formed by a chemical vapor deposition method using an organometallic material and a nitrogen source material containing silicon and nitrogen as constituent elements is added. Since a gate insulating film having a nitrogen-containing high-k film made of a dielectric film and a nitrogen-free high-k film to which nitrogen is not added is formed, a boron channel region added to the gate electrode as a dopant impurity is formed. While diffusion into the gate insulating film is suppressed by the nitrogen-containing high dielectric constant film, the advantage of using the high dielectric constant material for the gate insulating film can be sufficiently utilized by the nitrogen-free high dielectric constant film.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a structure of a film forming apparatus used in a film forming method according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a structure of a semiconductor device according to a second embodiment of the present invention;
FIG. 3 is a process sectional view (part 1) illustrating the method for fabricating the semiconductor device according to the second embodiment of the present invention;
FIG. 4 is a process sectional view (part 2) illustrating the method for fabricating the semiconductor device according to the second embodiment of the present invention.
FIG. 5 is a sectional view showing a structure of a semiconductor device according to a third embodiment of the present invention.
FIG. 6 is a graph showing a depth profile of a material composition by a RBS of a high dielectric constant film in a semiconductor device according to a third embodiment of the present invention.
FIG. 7 is a sectional view illustrating a structure of a semiconductor device according to a fourth embodiment of the present invention;
FIG. 8 is a cross-sectional view illustrating a structure of a semiconductor device according to a modification of the fourth embodiment of the present invention.
FIG. 9 is a cross-sectional view illustrating a structure of a semiconductor device according to a fifth embodiment;
[Explanation of symbols]
10. Silicon substrate
12 ... Silicon oxide film
14, 14a, 14b: nitrogen-containing high dielectric constant film
15 ... Gate insulating film
16 ... Gate electrode
18 ... Sidewall insulating film
20a: low concentration diffusion layer
20b: High concentration diffusion layer
22: source / drain diffusion layer
26 ... Reaction chamber
28 ... susceptor
30 ... shower head
32 ... Turbo molecular pump
34 ... Dry pump
36, 36a, 36b, 36c ... piping
38a, 38b ... cylinder
40a, 40b ... piping
42a, 42b, 42c ... mass flow controller
44 ... Polysilicon film
46 ... Resist film
48a: impurity-doped region
48b: impurity-doped region
50: silicon oxide film
52 ... Nitrogen-containing high dielectric constant film
53 ... Gate insulating film
56 ... High dielectric constant film
57 ... Gate insulating film
58 ... High dielectric constant film
59 ... Gate insulating film

Claims (10)

A gate insulating film formed on a semiconductor substrate and including a nitrogen-containing high-k film made of a nitrogen-doped high-k film and a nitrogen-free high-k film made of a nitrogen-free high-k film. A membrane,
And a gate electrode formed on the gate insulating film. The semiconductor device according to claim 1,
The semiconductor device, wherein the gate insulating film has the nitrogen-containing high dielectric constant film above and below the nitrogen-free high dielectric constant film, respectively. The semiconductor device according to claim 1, wherein
The semiconductor device, wherein the gate insulating film further includes a silicon oxide-based insulating film at an interface with the semiconductor substrate. Nitrogen-containing high dielectric constant film composed of a high dielectric constant film to which nitrogen is added by a chemical vapor deposition method using a metal organic material and a nitrogen source material containing silicon and nitrogen as constituent elements on a semiconductor substrate. Forming a film;
Forming a gate electrode on the nitrogen-containing high-dielectric-constant film. The method for manufacturing a semiconductor device according to claim 4,
Forming a non-nitrogen-containing high-k film made of a high-k film to which nitrogen is not added, on the semiconductor substrate or on the nitrogen-containing high-k film. Method. The method for manufacturing a semiconductor device according to claim 5,
A method for manufacturing a semiconductor device, wherein the nitrogen-containing high dielectric constant film and the nitrogen-free high dielectric constant film are continuously formed in the same reaction chamber. The method for manufacturing a semiconductor device according to claim 4, wherein
The method of manufacturing a semiconductor device, wherein in the step of forming the gate electrode, the gate electrode to which boron is added is formed. The method for manufacturing a semiconductor device according to claim 4, wherein
The method for manufacturing a semiconductor device, wherein the nitrogen source material is BTBAS. The method for manufacturing a semiconductor device according to claim 4, wherein
The method for manufacturing a semiconductor device, wherein the nitrogen-containing high dielectric constant film is a film obtained by adding nitrogen to an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a tantalum oxide film, or a hafnium aluminate film. Forming a high dielectric constant film to which nitrogen is added by a chemical vapor deposition method using an organic metal material and a nitrogen source material containing silicon and nitrogen as constituent elements. .

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