JP4549947B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device for preventing diffusion of hydrogen into a capacitive insulating film made of a ferroelectric film or a high dielectric constant film constituting a capacitive element, and a manufacturing method thereof.

  As a ferroelectric memory, a small-capacity memory of 1 to 64 kbit using a planar type structure has begun to be mass-produced, and recently, a large-capacity memory of 256 kbit to 4 Mbit using a stack type structure has become the center of development. Yes. In order to realize a stack type ferroelectric memory, it is indispensable to greatly improve the degree of integration and, in turn, miniaturize the ferroelectric memory. In order to realize this, it is important to achieve matching between the steps of forming a ferroelectric capacitor, forming a transistor, and forming a wiring.

  For this reason, for example, the treatment may be performed in a hydrogen atmosphere as typified by a contact embedding technique using W-CVD or a heat treatment in a hydrogen atmosphere performed to restore the characteristics of the transistor. In many semiconductor processes, it is a problem to maintain the polarization characteristics of the ferroelectric film without reducing the ferroelectric capacitor.

  Conventionally, a technique of coating a ferroelectric capacitor with a hydrogen barrier film is common. This is because the hydrogen barrier film typified by aluminum oxide film and silicon nitride film shields the diffusion of hydrogen generated in the semiconductor process after the formation of the ferroelectric capacitor, thereby reducing the polarization amount of the ferroelectric film. It is to prevent. By adopting a structure that completely covers the periphery of the ferroelectric capacitor as the covering structure of the ferroelectric capacitor by the hydrogen barrier film, the deterioration of the polarization characteristics of the ferroelectric film is most effectively prevented (for example, , See Patent Document 1). In this way, deterioration of polarization characteristics due to hydrogen of the ferroelectric capacitor is prevented, and a highly integrated ferroelectric memory or high dielectric memory is realized.

  Hereinafter, a conventional semiconductor device having a ferroelectric capacitor having a completely covered structure will be described with reference to FIG. FIG. 11 is a cross-sectional view of a conventional semiconductor device.

  As shown in FIG. 11, impurity diffusion layers 11 are formed on the surface layer portion of the semiconductor substrate 10 so as to be separated from each other. A gate oxide film 12 and a gate electrode 13 are formed on the semiconductor substrate 10, and sidewalls 14 are formed on both side surfaces of the gate oxide film 12 and the gate electrode 13. An element isolation oxide film 15 is formed on the semiconductor substrate 10. A first interlayer insulating film 16 is formed on the semiconductor substrate 10 so as to cover the gate oxide film 12, the gate electrode 13, the sidewalls 14, and the element isolation film 15, and the first interlayer insulating film 16. A first hydrogen barrier film 17 is formed thereon.

  On the first hydrogen barrier film 17, a ferroelectric capacitor composed of a lower electrode 18, a capacitive insulating film 19 made of a ferroelectric film and an upper electrode 20 is formed. A second hydrogen barrier film 21 is formed. A third hydrogen barrier film 22 is formed on the first hydrogen barrier film 17 so as to cover the side surfaces of the ferroelectric capacitor and the second hydrogen barrier film 21. A second interlayer insulating film 23 is formed on the first interlayer insulating film 16 so as to cover the first hydrogen barrier film 17 and the third hydrogen barrier film 22. On the second interlayer insulating film 23, wirings 24a and 24b are formed. The wiring 24 a is connected to the upper surface of the second hydrogen barrier film 22 so as to extend through the second interlayer insulating film 23 and the third hydrogen barrier film 22. The wirings 24 a and 24 b are connected to the upper surface of the impurity diffusion layer 11 so as to extend through the first interlayer insulating film 16 and the second interlayer insulating film 23.

As described above, the periphery of the ferroelectric capacitor shown in FIG. 11 is completely covered with the first hydrogen barrier film 17, the second hydrogen barrier film 21, and the third hydrogen barrier film 22. After the formation of the dielectric capacitor, even if the ferroelectric capacitor is subjected to a heat treatment in a reducing atmosphere, hydrogen can be prevented from diffusing into the capacitive insulating film 19, so that the ferroelectric constituting the capacitive insulating film 19 can be suppressed. Degradation of the polarization characteristics of the body membrane can be reduced.
Patent No. 3098474 (3rd page, Fig. 1)

  However, when the present inventors performed a heat treatment in a reducing atmosphere on the ferroelectric capacitor whose periphery is covered with the hydrogen barrier film as described above, the ferroelectric film constituting the capacitive insulating film was subjected to heat treatment. It has been found that the deterioration of the polarization characteristics cannot be completely prevented. In particular, when hydrogen annealing was performed at a high concentration, it was noticeable that the polarization characteristics of the ferroelectric film could not be completely prevented.

  This will be specifically described below with reference to FIGS. 12, 13, 14, and 15A and 15B.

  The present inventors performed heat treatment in a reducing atmosphere on a ferroelectric capacitor whose periphery is covered with a hydrogen barrier film as shown in FIG.

  As shown in FIG. 12, a first interlayer insulating film 31 is formed on a semiconductor substrate 30 on which memory cell transistors (not shown) are formed, and the first interlayer insulating film A first hydrogen barrier film 32 made of a silicon nitride film is formed on 31. A conductive second hydrogen barrier film 33 is formed on the first hydrogen barrier film 32. On the second hydrogen barrier film 33, a lower electrode 34 made of a platinum film as a surface layer, a capacitive insulating film 35 made of, for example, an SBT (SrTaBiO) film as a ferroelectric film, and an upper electrode 36 made of a platinum film. A ferroelectric capacitor is formed.

  On the first hydrogen barrier film 32, a second interlayer insulating film 37 for relaxing the step of the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 33 and the ferroelectric capacitor. Is formed. A third hydrogen barrier film 38 made of a titanium aluminum oxide film is formed on the first interlayer insulating film 31 so as to cover the side surfaces of the first hydrogen barrier film 32 and the second interlayer insulating film 37. Yes. A contact plug 39 is formed so as to extend through the first hydrogen barrier film 32 and the first interlayer insulating film 31, and the contact plug 39 connects the semiconductor substrate 30 and the lower electrode 34 of the ferroelectric capacitor. The second hydrogen barrier film 33 is connected.

  As described above, the ferroelectric capacitor shown in FIG. 12 has a structure in which the periphery is completely covered by the first hydrogen barrier film 32, the second hydrogen barrier film 33, and the third hydrogen barrier film 38. Therefore, even if heat treatment in a reducing atmosphere is performed after the formation of the ferroelectric capacitor, the diffusion of hydrogen into the capacitive insulating film 35 is suppressed, so that the polarization of the ferroelectric film constituting the capacitive insulating film 35 is suppressed. It is possible to prevent deterioration of characteristics.

  FIG. 13 shows a capacitive insulation made of a ferroelectric film when the ferroelectric capacitor shown in FIG. 12 is subjected to a heat treatment at 400 ° C. for 10 minutes in each atmosphere having a hydrogen concentration of 4% and 100%. The polarization characteristics of the film 35 are shown. As is apparent from FIG. 13, when the heat treatment is performed in each atmosphere having a hydrogen concentration of 4% and 100%, the amount of polarization of the capacitive insulating film 35 made of a ferroelectric film is reduced, and the hydrogen concentration is 100%. As shown in the case of the heat treatment in the% atmosphere, it has been found that when the heat treatment is performed in a particularly strong reducing atmosphere, the degree of deterioration of the polarization characteristics of the ferroelectric film is large.

  FIG. 14 shows a connection portion between the first hydrogen barrier film 32 and the second hydrogen barrier film 38 when heat treatment is performed at 400 ° C. for 10 minutes in the atmosphere of 100% hydrogen concentration shown in FIG. FIG. 14 shows a TEM cross-sectional view. As is apparent from FIG. 14, the connection portion 12A between the first hydrogen barrier film 32 made of a silicon nitride film and the third hydrogen barrier film 38 made of a titanium aluminum oxide film is formed. It was observed that a gap was formed.

  Thus, the present inventors have found that the cause of the deterioration of the polarization characteristics of the ferroelectric film is that hydrogen diffuses through the interface where the hydrogen barrier films are connected to each other. That is, the present inventors have selected the material used for the hydrogen barrier film or the hydrogen barrier films are connected to each other because the degree of deterioration of the polarization characteristics of the ferroelectric film is largely attributed to the adhesion between the hydrogen barrier films. It has been found that the state of the connection surface is extremely important.

  In order to analyze in detail the connection state in the connection portion 12A between the first hydrogen barrier film 32 and the third hydrogen barrier film 38, the inventors of the present invention, as an example, FIG. As shown, the experiment was conducted using a structure in which hydrogen barrier films were connected in a simulated manner.

  In the structure shown in FIG. 15A, a silicon nitride film (first hydrogen barrier film) and a titanium aluminum oxide film (second hydrogen barrier film) are sequentially formed on a silicon substrate (not shown). The present inventors observed a cross section of this structure with a TEM.

  As a result, as is apparent from FIG. 15A, an altered layer having a thickness of about 3.0 nm is formed at the connection portion (interface portion) between the silicon nitride (SiN) film and the titanium aluminum oxide (TiAlO) film. Was confirmed.

  Further, the present inventors analyzed the altered layer and silicon nitride film formed at the interface between the silicon nitride film and the titanium aluminum oxide film shown in FIG. 15A using EELS (Electron Energy Loss Spectroscopy). As is apparent from FIG. 15B, an Si—O 2 peak was detected in the analysis result for the altered layer. FIG. 15B is a TEM cross-sectional view for explaining an EELS analysis result with respect to an experimental sample at a connection portion between the first and second hydrogen barrier films, and loss energy (Loss Energy (eV)) and density. The relationship diagram with (Intensity) is shown.

  Based on such experimental results, the present inventors have determined that the altered layer formed at the interface between the silicon nitride film and the titanium aluminum oxide film is a silicon oxide film. This is because silicon (Si) in the silicon nitride film and oxygen (O) in titanium aluminum oxide are in contact with each other, and a heat treatment performed in a later step (for example, a heat treatment for crystallizing the capacitor insulating film) This is because it can be assumed that a stable Si—O 2 bond was formed.

  According to the above experimental results, even in the connection part between the actual hydrogen barrier films composed of the silicon nitride film and the titanium aluminum oxide film, Si—O 2 bonds are similarly formed, and the silicon oxide film It can be considered that it is formed.

  The silicon oxide film does not have a barrier property that prevents entry of hydrogen from the outside. For this reason, the connection portion between the silicon nitride film on which the silicon oxide film is formed and the titanium aluminum oxide film is weak against hydrogen, and thus plays a role of allowing hydrogen from the outside to pass therethrough.

  Actually, the connecting portion 12A shown in FIG. 14 is different from the structure shown in FIG. 15A, and the connecting portion 12A extends in the vertical direction. Considering that the contact state between the hydrogen barrier films is poor and that the film stress tends to concentrate on the connecting portion 12A, it is expected that Si—O 2 bonds are partially formed in the connecting portion 12A. . That is, it is expected that the connecting portion 12A is in a state in which a silicon oxide film made of Si—O 2 bonds and a gap are mixed.

  Therefore, the connecting portion 12A has no hydrogen barrier property regardless of whether the Si—O 2 bond is formed or the gap is formed. That is, as shown in FIG. 14, it means that the connecting portion 12A plays a role of a hydrogen diffusion path. In other words, if Si—O bonds are detected at the connection between the hydrogen barrier films, the combination of one hydrogen barrier film and the other hydrogen barrier film connected to each other will reduce the hydrogen content. This suggests that a diffusion path is likely to be formed.

  In the case of the conventional semiconductor device shown in FIG. 11, the first hydrogen barrier film 17 is made of a silicon nitride film having a thickness of 10 to 200 nm formed by a low pressure CVD method or a sputtering method. The second hydrogen barrier film 21 is made of a titanium nitride film having a thickness of 50 nm formed by sputtering, and the third hydrogen barrier film 22 is formed by laminating a silicon oxide film and a silicon nitride film in order from the bottom. Or a film containing oxygen and nitrogen, such as a silicon oxynitride film.

  However, when a laminated film of a silicon oxide film and a silicon nitride film is used as the third hydrogen barrier film 22, the hydrogen barrier property is weak in the first place, so that the ferroelectric film in the conventional semiconductor device shown in FIG. It is considered that the degree of deterioration of the polarization characteristics is high. In the case of the conventional semiconductor device shown in FIG. 11, the first, second, and third hydrogen barrier films 17, 21, and 22 are used for the purpose of reducing the deterioration of the polarization characteristics of the ferroelectric film. Although adopting a structure that completely covers the dielectric capacitor, paying attention to improving the adhesion of the part where the hydrogen barrier films are connected, the selection of the material used for the hydrogen barrier film or the surface of the hydrogen barrier film There is no disclosure of how the process is performed. Furthermore, discussions from such a viewpoint have not yet been made.

  In view of the above, the present invention improves the adhesion between the hydrogen barrier films at the portions where they are connected to each other, so that when the ferroelectric capacitor is heat-treated in a reducing atmosphere, An object is to reduce deterioration of polarization characteristics.

  In order to solve the above problems, a first semiconductor device according to the present invention includes a first hydrogen barrier film, a capacitive element formed on the first hydrogen barrier film, and a capacitive element so as to cover the capacitive element. A first hydrogen barrier film and a second hydrogen barrier film, the first hydrogen barrier film and the second hydrogen barrier film are formed of atoms of the same type that cause the first hydrogen barrier film and the second hydrogen barrier film to be in close contact with each other. It contains at least one.

  According to the first semiconductor device, since the first hydrogen barrier film and the second hydrogen barrier film contain the same kind of atoms that promote adhesion, the first hydrogen barrier film and the second hydrogen barrier film are included. Adhesion with the barrier film can be improved. For this reason, it is possible to prevent hydrogen from diffusing into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected to each other, and thus the ferroelectric film or the high dielectric constant film is used. Degradation of the polarization characteristics of the capacitor insulating film can be reduced.

  In the first semiconductor device, it is preferable that the first hydrogen barrier film and the second hydrogen barrier film are in close contact with each other at the peripheral portion of the capacitor element by chemically bonding atoms of the same type. .

  In this case, the first hydrogen barrier film and the second hydrogen barrier film are not merely physically connected to each other but are connected by chemical bonds of the same kind of atoms. The adhesion between the hydrogen barrier film and the second hydrogen barrier film is improved.

  In the first semiconductor device, the atom is preferably a nitrogen atom or an oxygen atom.

  Thus, the first hydrogen barrier film and the second hydrogen barrier film can be formed by a relatively easy process, and the adhesion between the first hydrogen barrier film and the second hydrogen barrier film is increased. Can be improved.

  In order to solve the above problems, a second semiconductor device according to the present invention covers a first hydrogen barrier film, a capacitor element formed on the first hydrogen barrier film, and the capacitor element. The first hydrogen barrier film and the second hydrogen barrier film are adhered to each other by mutual diffusion. The first hydrogen barrier film and the second hydrogen barrier film containing metal atoms are characterized in that the metal atoms are in close contact with each other as a result of mutual diffusion of the metal atoms.

  According to the second semiconductor device, the first hydrogen barrier film and the second hydrogen barrier film contain metal atoms that promote adhesion, and the metal atoms have a large diffusion coefficient. And the second hydrogen barrier film can be improved in adhesion. That is, the first hydrogen barrier film and the second hydrogen barrier film are in close contact by mutual diffusion of metal atoms. For this reason, since it is possible to suppress the diffusion of hydrogen into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, the capacitance formed of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be further reduced.

  In the second semiconductor device, the metal atom is preferably Ti or Ta.

  In this case, Ti or Ta has a very large diffusion coefficient, and has a higher function of improving the adhesion between the first hydrogen barrier film and the second hydrogen barrier film. Therefore, Ti or Ta is more effective than a ferroelectric film or a high dielectric constant film. Degradation of the polarization characteristics of the capacitive insulating film can be greatly reduced.

  In order to solve the above-described problem, a third semiconductor device according to the present invention covers a first hydrogen barrier film, a capacitor element formed on the first hydrogen barrier film, and the capacitor element. A second hydrogen barrier film formed in such a manner that the first hydrogen barrier film and the second hydrogen barrier film are connected to each other at a peripheral portion of the capacitor element through an adhesion layer. Features.

  According to the third semiconductor device, the adhesion between the first hydrogen barrier film and the second hydrogen barrier film is provided by interposing the adhesion layer between the first hydrogen barrier film and the second hydrogen barrier film. Therefore, the range of selection of materials used for the first hydrogen barrier film and the second hydrogen barrier film is not limited, and the capacitance insulating film made of a ferroelectric film or a high dielectric constant film is not limited. It is possible to reduce the deterioration of the polarization characteristics.

  In the third semiconductor device, the adhesion layer preferably stores hydrogen.

  In this way, a small amount of hydrogen diffused in the adhesion layer can be captured, so that hydrogen diffused in the capacitor insulating film can be effectively suppressed, so that a capacitor made of a ferroelectric film or a high dielectric constant film can be used. Degradation of the polarization characteristics of the insulating film can be further reduced.

  In the third semiconductor device, the adhesion layer preferably includes a transition metal.

  This makes it possible to prevent hydrogen from being diffused by using a metal that absorbs hydrogen, and to further enhance the effect of bringing the first hydrogen barrier film and the second hydrogen barrier film into close contact with each other. Can do.

  In the third semiconductor device, the adhesion layer preferably contains Ti or Ta.

  In this case, since Ti or Ta has a large diffusion coefficient, it is possible to further enhance the effect of bringing the first hydrogen barrier film and the second hydrogen barrier film into close contact with each other.

  In order to solve the above-described problem, the fourth semiconductor device according to the present invention is formed on the first hydrogen barrier film having the oxidized region on the upper surface and the first hydrogen barrier film. A capacitor element, and a second hydrogen barrier film containing oxygen formed so as to cover the capacitor element, wherein the first hydrogen barrier film and the second hydrogen barrier film are formed at the periphery of the capacitor element. It is characterized by being in close contact by an oxygen bond through an oxidized region.

  According to the fourth semiconductor device, oxygen contained in the oxidized region of the first hydrogen barrier film and oxygen contained in the second hydrogen barrier film are bonded to each other by oxygen bonding. The two hydrogen barrier films are not merely physically connected to each other but are in close contact with each other by chemical bonds. In other words, the first hydrogen barrier film and the second hydrogen barrier film are in close contact with oxygen atoms as bridges. For this reason, since it is possible to suppress the diffusion of hydrogen into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, the capacitance formed of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be further reduced.

  In order to solve the above problems, a fifth semiconductor device according to the present invention is formed on a first hydrogen barrier film having a nitrided region on the upper surface and the first hydrogen barrier film. A capacitor element and a second hydrogen barrier film containing nitrogen formed so as to cover the capacitor element are provided, and the first hydrogen barrier film and the second hydrogen barrier film are nitrided at the periphery of the capacitor element. It is characterized in that it is in close contact by nitrogen bonding through the formed region.

  According to the fifth semiconductor device, the nitrogen contained in the nitrided region of the first hydrogen barrier film and the nitrogen contained in the second hydrogen barrier film are nitrogen-bonded to form a first hydrogen barrier film and a second hydrogen barrier film. The two hydrogen barrier films are not merely physically connected to each other but are in close contact with each other by chemical bonds. In other words, the first hydrogen barrier film and the second hydrogen barrier film are in close contact with each other by bridging nitrogen atoms. For this reason, since it is possible to suppress the diffusion of hydrogen into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, the capacitance formed of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be further reduced.

  In the first to fourth semiconductor devices, the first hydrogen barrier film and the second hydrogen barrier film do not interpose a silicon oxide film between the first hydrogen barrier film and the second hydrogen barrier film. It is preferable that it adheres closely.

  As described above, since the silicon oxide film serving as a hydrogen diffusion path to the capacitor insulating film is not interposed, deterioration of the polarization characteristics of the capacitor insulating film made of the ferroelectric film or the high dielectric constant film can be further reduced.

  In the first to fourth semiconductor devices, the first hydrogen barrier film and the second hydrogen barrier film are preferably films made of the same material.

  In this way, the adhesion between the first hydrogen barrier film and the second hydrogen barrier is improved, and the first thermal barrier film is not affected by thermal expansion, thermal contraction, or stress change due to heat treatment in a subsequent process. Since the portion where the hydrogen barrier film and the second hydrogen barrier film are connected is thermally stabilized, the deterioration of the polarization characteristics of the capacitive insulating film made of a ferroelectric film or a high dielectric constant film can be further reduced. Can do.

  In the first to fourth semiconductor devices, the capacitor element is formed on the lower electrode formed on the first hydrogen barrier film, the capacitor insulating film formed on the lower electrode, and the capacitor insulating film. The capacitor insulating film is preferably made of a ferroelectric film or a high dielectric constant film.

In the first to fourth semiconductor devices, the capacitive insulating film is made of SrBi ₂ (Ta _x Nb _{1 -x} ) ₂ O ₉ , Pb (Zr _x Ti _{1 -x} ) O ₃ , (Ba _x Sr _{1 -x} ) TiO. _{3, (Bi x La 1-} x) 4 Ti 3 O 12 ( where, in the above, X is satisfying the relationship of 0 ≦ x ≦ 1), or is preferably made of Ta ₂ O _5.

  In order to solve the above-described problem, a first method for manufacturing a semiconductor device according to the present invention includes a step of forming a first hydrogen barrier film, and a capacitor element is formed on the first hydrogen barrier film. And a step of forming a second hydrogen barrier film so as to cover the capacitor element and to be in contact with the first hydrogen barrier film at a peripheral portion of the capacitor element, the first hydrogen barrier film and the second hydrogen barrier film. The barrier film includes at least one atom of the same type that causes the first hydrogen barrier film and the second hydrogen barrier to adhere to each other, and the first hydrogen barrier film and the second hydrogen barrier film are the same type of atom. Are closely attached by chemically bonding.

  According to the first method for fabricating a semiconductor device, the first hydrogen barrier film and the second hydrogen barrier film contain the same kind of atoms that promote adhesion, and thus the first hydrogen barrier film and the second hydrogen barrier film Adhesion with the hydrogen barrier film 2 can be improved. That is, the first hydrogen barrier film and the second hydrogen barrier film are not merely physically connected to each other, but are connected by chemical bonds of the same kind of atoms. And the adhesion between the second hydrogen barrier film and the second hydrogen barrier film are improved. For this reason, since it is possible to suppress the diffusion of hydrogen into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, the capacitance formed of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be reduced.

  In the first method for manufacturing a semiconductor device, a surface exposed at a peripheral portion of the capacitive element in the first hydrogen barrier film between the process of forming the capacitive element and the process of forming the second hydrogen barrier film Etching, and the etching dissociates the bonding hands in the bonded state of atoms contained in common in the first hydrogen barrier film and the second hydrogen barrier film to form unbonded hands. It is preferable to do.

  In this way, the atoms that are commonly included in the first hydrogen barrier film and the second hydrogen barrier film dissociate the bonding state with other atoms included in the first hydrogen barrier film, thereby causing unbonded bonds. And bonded to atoms commonly included in the second hydrogen barrier film. For this reason, the first hydrogen barrier film and the second hydrogen barrier film are not merely physically connected to each other, but are connected by a chemical bond of atoms included in common. The adhesion between the barrier film and the second hydrogen barrier film is improved. Accordingly, it is possible to suppress hydrogen from diffusing into the capacitor insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, so that the capacitor made of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be reduced.

  In this case, the etching is preferably dry etching using an inert gas.

  As described above, by using an inert gas, it is possible to break bonds between atoms commonly included in the first hydrogen barrier film and the second hydrogen barrier film without causing an undesired chemical reaction. . For this reason, many unbonded hands can be generated on the surface of the first hydrogen barrier film.

  In the first method for manufacturing a semiconductor device, the second hydrogen barrier film is formed by reactive sputtering in an atmosphere containing atoms that are commonly included in the first hydrogen barrier film and the second hydrogen barrier film. Preferably it is formed.

  In this case, atoms commonly contained in the first hydrogen barrier film and the second hydrogen barrier film existing in the atmosphere are connected to the first hydrogen barrier film and the second hydrogen barrier film. Since the second hydrogen barrier film is deposited while being taken into the portion, the adhesion between the first hydrogen barrier film and the second hydrogen barrier film can be improved.

  In the first method for manufacturing a semiconductor device, the atom is preferably a nitrogen atom or an oxygen atom.

  Thus, the first hydrogen barrier film and the second hydrogen barrier film can be formed by a relatively easy process, and the adhesion between the first hydrogen barrier film and the second hydrogen barrier film is increased. Can be improved.

  In the first method for manufacturing a semiconductor device, a surface exposed at a peripheral portion of the capacitive element in the first hydrogen barrier film between the process of forming the capacitive element and the process of forming the second hydrogen barrier film It is preferable to provide the process of removing a layer.

  In the first method of manufacturing a semiconductor device, at least a part of the outer region of the region where the capacitor element is formed in the first hydrogen barrier film between the step of forming the capacitor element and the step of removing the surface layer The first hydrogen barrier film and the second hydrogen barrier even when another layer is interposed between the first hydrogen barrier film and the capacitor. Since the film can be reliably connected, the adhesion between the first hydrogen barrier film and the second hydrogen barrier film can be reliably improved.

  In the first method for manufacturing a semiconductor device, the step of removing the surface layer preferably includes a step of cleaning the surface layer with hydrofluoric acid.

  In this way, only the surface layer can be easily removed by controlling the concentration of hydrofluoric acid and the cleaning time.

  In the first method for manufacturing a semiconductor device, the step of removing the surface layer preferably includes a step of removing the surface layer by dry etching using an inert gas.

  In this way, only the surface layer can be easily removed, and damage to the first hydrogen barrier film can be suppressed.

  In order to solve the above-described problem, a second method of manufacturing a semiconductor device according to the present invention includes a step of forming a first hydrogen barrier film, and a capacitor element is formed on the first hydrogen barrier film. And a step of forming a second hydrogen barrier film so as to cover the capacitor element and to be in contact with the first hydrogen barrier film at a peripheral portion of the capacitor element, the first hydrogen barrier film and the second hydrogen barrier film. The barrier film includes metal atoms that cause the first hydrogen barrier film and the second hydrogen barrier film to adhere to each other by mutual diffusion, and the first hydrogen barrier film and the second hydrogen barrier film have the metal atoms interdiffused. By doing so, the capacitor element is in close contact with the peripheral edge portion of the capacitor element.

  According to the second method for manufacturing a semiconductor device, the first hydrogen barrier film and the second hydrogen barrier film contain metal atoms that promote adhesion, and the metal atoms have a large diffusion coefficient. Adhesion between the hydrogen barrier film and the second hydrogen barrier film can be improved. That is, the first hydrogen barrier film and the second hydrogen barrier film are adhered to each other by mutual diffusion of metal atoms. For this reason, since it is possible to suppress the diffusion of hydrogen into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected, the capacitance formed of the ferroelectric film or the high dielectric constant film. Degradation of the polarization characteristics of the insulating film can be further reduced.

  In the second method for manufacturing a semiconductor device, the metal atom is preferably Ti or Ta.

  In this way, the first hydrogen barrier film and the second hydrogen barrier film can be formed by a relatively easy process, and Ti or Ta has a large diffusion coefficient. Adhesiveness with the second hydrogen barrier film can be improved.

  In order to solve the above-described problem, a third method of manufacturing a semiconductor device according to the present invention includes a step of forming a first hydrogen barrier film, and a capacitor element is formed on the first hydrogen barrier film. A step of oxidizing the exposed surface of the first hydrogen barrier film at the periphery of the capacitive element, and a second hydrogen barrier containing oxygen so as to cover the capacitive element and to be in contact with the oxidized surface And a step of forming a film.

  According to the third method for manufacturing a semiconductor device, the surface layer oxidized in the first hydrogen barrier film is connected to the second hydrogen barrier film containing oxygen atoms. Since the adhesion between the film and the second hydrogen barrier film can be improved, it is possible to reduce the deterioration of the polarization characteristics of the capacitive insulating film made of the ferroelectric film or the high dielectric constant film.

  In the third method of manufacturing a semiconductor device, at least a part of an outer region of the region where the capacitor element is formed in the first hydrogen barrier film is formed between the step of forming the capacitor element and the step of oxidizing the surface. If the step of exposing is further provided, the first hydrogen barrier film and the second hydrogen barrier film are provided even when another layer is interposed between the first hydrogen barrier film and the capacitor. Can be reliably connected to each other, so that the adhesion between the first hydrogen barrier film and the second hydrogen barrier film can be reliably improved.

  In the third method for fabricating a semiconductor device, the step of oxidizing the surface preferably includes a step of performing a rapid heat treatment in an oxygen atmosphere.

  In this way, it is possible to easily oxidize only the surface of the first hydrogen barrier film and to suppress the influence on the base in the first hydrogen barrier film.

  In the third method for fabricating a semiconductor device, the step of oxidizing the surface preferably includes a step of exposing the surface to oxygen plasma.

  In this case, since the oxidation is performed at a low temperature, only the surface of the first hydrogen barrier film can be more easily oxidized, and the influence on the base in the first hydrogen barrier film can be further suppressed. it can.

  In order to solve the above problems, a fourth method of manufacturing a semiconductor device according to the present invention includes a step of forming a first hydrogen barrier film, and a capacitor element is formed on the first hydrogen barrier film. A step of nitriding a surface of the first hydrogen barrier film exposed at a peripheral portion of the capacitive element, and a second hydrogen barrier containing nitrogen so as to cover the capacitive element and to be in contact with the nitrided surface And a step of forming a film.

  According to the fourth method for manufacturing a semiconductor device, the first hydrogen barrier film is connected by a nitrogen bond to connect the surface layer nitrided in the first hydrogen barrier film and the second hydrogen barrier film containing nitrogen atoms. Since the adhesion between the film and the second hydrogen barrier film can be improved, it is possible to reduce the deterioration of the polarization characteristics of the capacitive insulating film made of the ferroelectric film or the high dielectric constant film.

  In the fourth method of manufacturing a semiconductor device, at least a part of an outer region of the region where the capacitive element is formed in the first hydrogen barrier film is formed between the step of forming the capacitive element and the step of nitriding the surface. If the step of exposing is further provided, the first hydrogen barrier film and the second hydrogen barrier film are provided even when another layer is interposed between the first hydrogen barrier film and the capacitor. Can be reliably connected to each other, so that the adhesion between the first hydrogen barrier film and the second hydrogen barrier film can be reliably improved.

  In the fourth method for fabricating a semiconductor device, the step of nitriding the surface preferably includes a step of performing a rapid heat treatment in a nitrogen atmosphere.

  In this way, only the surface of the first hydrogen barrier film can be easily nitrided, and the influence on the base in the first hydrogen barrier film can be suppressed.

  In the fourth method for fabricating a semiconductor device, the step of nitriding the surface preferably includes a step of exposing the surface to nitrogen plasma.

  In this case, since nitriding is performed at a low temperature, only the surface of the first hydrogen barrier film can be more easily nitrided, and the influence on the base in the first hydrogen barrier film can be further suppressed. it can.

  In order to solve the above problems, a fifth method for manufacturing a semiconductor device according to the present invention includes a step of forming a first hydrogen barrier film, and a capacitor element is formed on the first hydrogen barrier film. A step of forming an adhesion layer on a portion of the first hydrogen barrier film exposed at a peripheral portion of the capacitor element, and a second hydrogen barrier film covering the capacitor element and in contact with the adhesion layer And a step of performing.

  According to the fifth method for fabricating a semiconductor device, the first hydrogen barrier film and the second hydrogen barrier are formed by forming an adhesion layer between the first hydrogen barrier film and the second hydrogen barrier film. Since the adhesion to the film can be improved, the range of selection of materials used for the first hydrogen barrier film and the second hydrogen barrier film is not limited, and the ferroelectric film or the high dielectric constant film can be used. It is possible to reduce the deterioration of the polarization characteristics of the capacitive insulating film.

  In the fifth method for manufacturing a semiconductor device, at least a part of the outer region of the region where the capacitor element is formed in the first hydrogen barrier film between the step of forming the capacitor element and the step of forming the adhesion layer The first hydrogen barrier film and the second hydrogen barrier even when another layer is interposed between the first hydrogen barrier film and the capacitor. Since the film can be reliably connected, the adhesion between the first hydrogen barrier film and the second hydrogen barrier film can be reliably improved.

  In the fifth method for fabricating a semiconductor device, the adhesion layer preferably occludes hydrogen.

  In this way, since a small amount of hydrogen diffused in the adhesion layer can be captured, hydrogen diffused in the capacitive insulating film can be effectively suppressed, and therefore, it is made of a ferroelectric film or a high dielectric constant film. Degradation of the polarization characteristics of the capacitor insulating film can be further reduced.

  In the fifth method for fabricating a semiconductor device, the adhesion layer preferably contains Ti or Ta.

  In this case, since Ti or Ta has a very large diffusion coefficient, the adhesion between the first hydrogen barrier film and the second hydrogen barrier film is further improved, and Ti or Ta has the ability to occlude hydrogen. Therefore, since hydrogen diffused in the capacitor insulating film can be effectively suppressed, deterioration of the polarization characteristics of the capacitor insulating film made of a ferroelectric film or a high dielectric constant film can be greatly reduced.

  According to the first semiconductor device of the present invention, since the first hydrogen barrier film and the second hydrogen barrier film contain the same kind of atoms that promote adhesion, the first hydrogen barrier film and the second hydrogen barrier film Adhesion with the hydrogen barrier film 2 can be improved. For this reason, it is possible to prevent hydrogen from diffusing into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected to each other, and thus the ferroelectric film or the high dielectric constant film is used. Degradation of the polarization characteristics of the capacitor insulating film can be reduced.

  According to the second semiconductor device of the present invention, the first hydrogen barrier film and the second hydrogen barrier film contain metal atoms that promote adhesion, and the metal atoms have a large diffusion coefficient. Adhesion between the hydrogen barrier film and the second hydrogen barrier film can be improved. That is, the first hydrogen barrier film and the second hydrogen barrier film are in close contact by mutual diffusion of metal atoms. For this reason, it is possible to prevent hydrogen from diffusing into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected to each other, and thus the ferroelectric film or the high dielectric constant film is used. Degradation of the polarization characteristics of the capacitor insulating film can be further reduced.

  According to the third semiconductor device of the present invention, the adhesion layer is interposed between the first hydrogen barrier film and the second hydrogen barrier film, so that the first hydrogen barrier film and the second hydrogen barrier film are Since the adhesiveness of the first hydrogen barrier film and the second hydrogen barrier film is not limited, the capacitance of the ferroelectric film or the high dielectric constant film can be improved. Degradation of the polarization characteristics of the insulating film can be reduced.

  According to the fourth semiconductor device of the present invention, oxygen contained in the oxidized region of the first hydrogen barrier film and oxygen contained in the second hydrogen barrier film are oxygen-bonded, whereby the first hydrogen barrier. The film and the second hydrogen barrier film are not merely physically connected to each other but are connected by a chemical bond. For this reason, it is possible to prevent hydrogen from diffusing into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected to each other, and thus the ferroelectric film or the high dielectric constant film is used. Degradation of the polarization characteristics of the capacitor insulating film can be further reduced.

  According to the fifth semiconductor device of the present invention, the nitrogen contained in the nitrided region of the first hydrogen barrier film and the nitrogen contained in the second hydrogen barrier film are nitrogen-bonded to form the first hydrogen barrier. The film and the second hydrogen barrier film are not merely physically connected to each other but are connected by a chemical bond. For this reason, it is possible to prevent hydrogen from diffusing into the capacitive insulating film through the interface where the first hydrogen barrier film and the second hydrogen barrier film are connected to each other, and thus the ferroelectric film or the high dielectric constant film is used. Degradation of the polarization characteristics of the capacitor insulating film can be further reduced.

(First embodiment)
The semiconductor device according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a cross-sectional structure of the semiconductor device according to the first embodiment.

  As shown in FIG. 1, on a semiconductor substrate 100 on which memory cell transistors (not shown) are formed, a first BPSG film made of a silicon oxide film doped with, for example, boron, phosphorus, or the like is formed. One interlayer insulating film 101 is formed, and a first hydrogen barrier film 102 made of a silicon nitride film is formed on the first interlayer insulating film 101. A conductive second hydrogen barrier film 103 made of a titanium aluminum nitride film is formed on the first hydrogen barrier film 102. A lower electrode 104 is formed on the second hydrogen barrier film 103. The lower electrode 104 includes an upper film made of a platinum film and a lower film made of an iridium oxide film, an iridium film, a titanium nitride aluminum film, or a titanium nitride film as a barrier film. The lower electrode 104 includes an upper layer film made of a platinum film and a lower layer film made of a laminated film in which two or more of an iridium oxide film, an iridium film, a titanium aluminum nitride film, or a titanium nitride film are laminated as a barrier film. You may comprise.

  A capacitive insulating film 105 made of, for example, an SBT (SrTaBiO) film is formed on the lower electrode 104 as a ferroelectric film, and an upper electrode 106 made of a platinum film is formed on the capacitive insulating film 105. Has been. As described above, a ferroelectric capacitor (capacitor element) is formed by the lower electrode 104, the capacitor insulating film 105, and the upper electrode 106.

  On the first hydrogen barrier film 102, a second layer made of an ozone TEOS film for relaxing the step of the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 103 and the ferroelectric capacitor. An interlayer insulating film 107 is formed. A third hydrogen barrier film 108 made of a titanium aluminum nitride film is formed on the first interlayer insulating film 101 so as to cover the side surfaces of the first hydrogen barrier film 102 and the second interlayer insulating film 107. .

  A contact plug 109 made of a W film is formed so as to extend through the first hydrogen barrier film 102 and the first interlayer insulating film 101, and the contact plug 109 is connected to the semiconductor substrate 100 into which arsenic or the like is implanted. The lower electrode 104 of the ferroelectric capacitor is connected through the second hydrogen barrier film 103. A third interlayer insulating film 110 is formed on the first interlayer insulating film 101 so as to cover the third hydrogen barrier film 108. A wiring is usually formed on the third interlayer insulating film 110.

  As described above, the ferroelectric capacitor shown in FIG. 1 has a structure in which the periphery is completely covered by the first hydrogen barrier film 102, the second hydrogen barrier film 103, and the third hydrogen barrier film 108. Yes.

  Here, the semiconductor device according to the first embodiment is characterized in that the first hydrogen barrier film 102 is made of a silicon nitride film, the third hydrogen barrier film 108 is made of a titanium aluminum nitride film, and the first hydrogen barrier film 102 is made of silicon nitride film. The barrier film 102 and the third hydrogen barrier film 108 include the same kind of atoms that in close contact with each other, here nitrogen atoms in common.

  FIG. 2 shows a capacitive insulating film made of a ferroelectric film when the ferroelectric capacitor shown in FIG. 1 is subjected to a heat treatment at 400 ° C. for 10 minutes in an atmosphere having a hydrogen concentration of 4% and 100%. The polarization characteristics of 105 are shown, and the data shown in FIG. 13 in the above-described conventional example are also shown.

  As is apparent from FIG. 2, the polarization characteristics of the capacitive insulating film 105 made of a ferroelectric film are compared with the conventional example described above in the case of heat treatment in each of the hydrogen concentrations of 4% and 100%. As shown in the case of the heat treatment in an atmosphere having a hydrogen concentration of 100%, the deterioration of the film is made of a ferroelectric film when the heat treatment is performed in a particularly strong reducing atmosphere. It can be seen that the degree of suppressing the deterioration of the polarization characteristics of the capacitor insulating film 105 is large.

  FIG. 3 shows a connection portion between the first hydrogen barrier film 102 and the third hydrogen barrier film 108 when heat treatment is performed at 400 ° C. for 10 minutes in the atmosphere of 100% hydrogen concentration shown in FIG. As shown in FIG. 3, the connection portion 3A between the first hydrogen barrier film 102 made of a silicon nitride film and the third hydrogen barrier film 108 made of a titanium aluminum nitride film is clearly shown in FIG. No gaps as shown in FIG. 12 were observed.

  Here, in the portion where the first hydrogen barrier film 102 and the third hydrogen barrier film 108 are in contact with each other, the first hydrogen barrier film 102 and the third hydrogen barrier film 108 are bonded by a covalent bond of nitrogen. . That is, the nitrogen atom has a bond so as to cross over the first hydrogen barrier film 102 and the second hydrogen barrier film 108 and plays a role of crosslinking. Accordingly, a layer made of nitrogen atoms is formed in the boundary region where the first hydrogen barrier film 102 and the second hydrogen barrier film 108 are in contact with each other, so that no gap is formed, and the first region is not formed. In the portion where the hydrogen barrier film 102 and the third hydrogen barrier film 108 are connected, a silicon oxide film having a role of a hydrogen diffusion path is not formed.

  In this way, the present inventors reconfirmed that the cause of the deterioration of the polarization characteristics of the ferroelectric film is that it largely depends on the state of the interface where the hydrogen barrier films are connected to each other. By improving the adhesion between the hydrogen barrier films by including the same kind of atoms that promote adhesion to each of the hydrogen barrier films having a portion to be formed, the polarization characteristics of the ferroelectric film can be improved. The effect that deterioration can be suppressed was acquired.

  As described above, according to the first embodiment, the first hydrogen barrier film 102 and the third hydrogen barrier film 108 include the same type of atoms that closely contact each other. The first hydrogen barrier film and the second hydrogen barrier film are not merely physically connected to each other but are connected by chemical bonds of the same kind of atoms. And the third hydrogen barrier film 108 are improved in adhesion. Therefore, hydrogen can be prevented from diffusing into the capacitive insulating film 105 through the interface where the first hydrogen barrier film 102 and the third hydrogen barrier film 108 are connected, so that the capacitive insulating film made of a ferroelectric film The deterioration of the polarization characteristics of 105 can be reduced. As a result, a highly reliable ferroelectric memory can be realized.

  In addition, the ferroelectric capacitor shown in FIG. 1 has a structure in which the lower electrode 104 serves as a capacity defining port, but instead, it may have a structure in which the upper electrode 106 serves as a capacity defining port.

  Further, in the first embodiment, the capacitor insulating film 105 is composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 105 is made of a ferroelectric film, it is needless to say that the same effect can be obtained even when the capacitor insulating film 105 is made of a high dielectric constant film.

  Further, in the first embodiment, the case where the first hydrogen barrier film 102 and the third hydrogen barrier film 108 include nitrogen atoms in common as the same kind of atoms that make the films in close contact with each other has been described. However, a silicon oxynitride film is used for the first hydrogen barrier film 102, and a titanium aluminum oxide film or an aluminum oxide film is used for the third hydrogen barrier film 108, so that the first hydrogen barrier film 102 and the third hydrogen barrier film 102 By including oxygen atoms in common in the hydrogen barrier film 108 as the atoms that make the films in close contact with each other, the first hydrogen barrier film 102 and the third hydrogen are in the same manner as in the case where the atoms to be attached are nitrogen atoms. Adhesion with the barrier film 108 can be improved. As described above, the nitrogen atoms or the oxygen atoms are commonly included in the first hydrogen barrier film 102 and the third hydrogen barrier film 108 because nitride or oxidation is performed in heat treatment, plasma treatment, reactive sputtering, CVD, and the like. Since formation of an object becomes easy, the freedom degree in a semiconductor process can be raised.

  In the first embodiment, not only when a silicon oxynitride film is used for the first hydrogen barrier film 102 and a titanium aluminum oxide film or an aluminum oxide film is used for the third hydrogen barrier film 108, Any film may be used as long as it functions as a barrier film and contains oxygen atoms in common.

  The first hydrogen barrier film 102 and the third hydrogen barrier film 108 may be films made of the same material. As a result, the adhesion between the first hydrogen barrier film 102 and the third hydrogen barrier 108 is improved, and the first hydrogen barrier film 102 and the third hydrogen barrier 108 are not affected by thermal expansion, thermal contraction, or stress change due to heat treatment in a subsequent process. Since the portion where the hydrogen barrier film 102 and the third hydrogen barrier film 108 are connected is thermally stabilized, the deterioration of the polarization characteristics of the capacitive insulating film made of a ferroelectric film or a high dielectric constant film is further reduced. Can be made.

(Second Embodiment)
A semiconductor device according to the second embodiment of the present invention will be described below with reference to FIG. FIG. 4 shows a cross-sectional structure of the semiconductor device according to the second embodiment.

  As shown in FIG. 4, on a semiconductor substrate 200 on which memory cell transistors (not shown) are formed, a first BPSG film made of a silicon oxide film doped with, for example, boron, phosphorus or the like is formed. One interlayer insulating film 201 is formed, and a first hydrogen barrier film 202 made of a titanium aluminum oxide film is formed on the first interlayer insulating film 201. On the first hydrogen barrier film 202, a conductive second hydrogen barrier film 203 made of a titanium aluminum nitride film is formed. A lower electrode 204 is formed on the second hydrogen barrier film 203. The lower electrode 204 includes an upper film made of a platinum film and a lower film made of an iridium oxide film, an iridium film, a titanium aluminum nitride film, or a titanium nitride film as a barrier film. The lower electrode 204 includes an upper layer film made of a platinum film and a lower layer film made of a laminated film in which two or more of an iridium oxide film, an iridium film, a titanium aluminum nitride film, or a titanium nitride film are laminated as a barrier film. You may comprise.

  A capacitive insulating film 205 made of, for example, an SBT (SrTaBiO) film is formed on the lower electrode 204 as a ferroelectric film, and an upper electrode 206 made of a platinum film is formed on the capacitive insulating film 205. Has been. As described above, a ferroelectric capacitor (capacitance element) is formed by the lower electrode 204, the capacitor insulating film 205, and the upper electrode 206.

  On the first hydrogen barrier film 202, a second layer made of an ozone TEOS film for relaxing the step of the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 203 and the ferroelectric capacitor. An interlayer insulating film 207 is formed. A third hydrogen barrier film 208 made of a tantalum nitride film is formed on the first interlayer insulating film 201 so as to cover the side surfaces of the first hydrogen barrier film 202 and the second interlayer insulating film 207.

  A contact plug 209 made of a W film is formed so as to extend through the first hydrogen barrier film 202 and the first interlayer insulating film 201, and the contact plug 209 is connected to the semiconductor substrate 200 implanted with arsenic or the like. The lower electrode 204 of the ferroelectric capacitor is connected through the second hydrogen barrier film 203. A third interlayer insulating film 210 is formed on the first interlayer insulating film 201 so as to cover the third hydrogen barrier film 208. A wiring is usually formed on the third interlayer insulating film 210.

  As described above, the ferroelectric capacitor shown in FIG. 4 has a structure in which the periphery is completely covered by the first hydrogen barrier film 202, the second hydrogen barrier film 203, and the third hydrogen barrier film 208. Yes.

  Here, the semiconductor device according to the second embodiment is characterized in that the first hydrogen barrier film 202 is made of a titanium aluminum oxide film, and the third hydrogen barrier film 208 is made of a tantalum nitride film, and is mutually connected by mutual diffusion. For example, titanium, aluminum, and tantalum, which are metal atoms that adhere the film, are included. That is, by including the metal atoms in common in the first hydrogen barrier film 202 and the third hydrogen barrier film as described above, the first hydrogen barrier film 202 and the second hydrogen barrier film 202 are formed by the mutual diffusion action of the metal atoms. 3 and the hydrogen barrier film 208 can be improved. In addition, since titanium or tantalum has a high diffusion coefficient, the mutual diffusion action is increased, so that the adhesion between the first hydrogen barrier film 202 and the third hydrogen barrier film 208 is further improved.

  As described above, according to the second embodiment, due to the presence of metal atoms contained in the first hydrogen barrier film 202 and the third hydrogen barrier film 208, an interdiffusion action occurs and the first hydrogen barrier film. Since the adhesion between the first hydrogen barrier film 202 and the third hydrogen barrier film 208 is improved, hydrogen diffuses into the capacitor insulating film 205 through the interface where the first hydrogen barrier film 202 and the third hydrogen barrier film 208 are connected. Since this can be suppressed, it is possible to reduce the deterioration of the polarization characteristics of the capacitive insulating film 205 made of a ferroelectric film. As a result, a highly reliable ferroelectric memory can be realized. In addition, metal atoms that are widely used in semiconductor processes can be used as the atoms for bringing the films into close contact with each other in the first hydrogen barrier film 202 and the third hydrogen barrier film 208. Among these, titanium and tantalum can be used. Is advantageous in that the diffusion coefficient is increased and the mutual diffusion action is increased.

  In the second embodiment, the first hydrogen barrier film 202 and the third hydrogen barrier film 208 may contain the same kind of metal atoms. For example, the first hydrogen barrier film 202 may be made of titanium aluminum oxide, and the third hydrogen barrier film 208 may be made of titanium aluminum nitride. In this case, since the first hydrogen barrier film 202 and the third hydrogen barrier film 208 are joined by the metal bond of titanium which is the same kind of metal atom, the adhesion between the films is further improved.

  Further, the ferroelectric capacitor shown in FIG. 4 has a structure in which the lower electrode 204 serves as a capacity defining port, but instead, a structure in which the upper electrode 206 serves as a capacity defining port may be used.

  Further, in the second embodiment, the capacitor insulating film 205 is composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Although the capacitor insulating film 205 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 205 is made of a high dielectric constant film.

  Further, the first hydrogen barrier film 202 and the third hydrogen barrier film 208 may be films made of the same material. As a result, the adhesion between the first hydrogen barrier film 202 and the third hydrogen barrier 208 is improved, and the first hydrogen barrier film 202 is not affected by thermal expansion, thermal contraction, or stress change due to heat treatment in a subsequent process. Since the portion where the hydrogen barrier film 202 and the third hydrogen barrier film 208 are connected is thermally stabilized, the deterioration of the polarization characteristics of the capacitive insulating film made of a ferroelectric film or a high dielectric constant film is further reduced. Can be made.

(Third embodiment)
Hereinafter, a semiconductor device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a cross-sectional structure of a semiconductor device according to the third embodiment.

  As shown in FIG. 5, on a semiconductor substrate 300 on which memory cell transistors (not shown) are formed, a first made of a BPSG film which is a silicon oxide film to which, for example, boron, phosphorus or the like is added. A first hydrogen barrier film 302 made of a silicon nitride film is formed on the first interlayer insulating film 301. On the first hydrogen barrier film 302, a conductive second hydrogen barrier film 303 made of a titanium aluminum nitride film is formed. A lower electrode 304 is formed on the second hydrogen barrier film 303. The lower electrode 304 is composed of an upper layer film made of a platinum film and a lower layer film made of an iridium oxide film, an iridium film, a titanium aluminum nitride film, or a titanium nitride film as a barrier film. The lower electrode 304 includes an upper layer film made of a platinum film and a lower layer film made of a laminated film in which two or more films of an iridium oxide film, an iridium film, a titanium aluminum nitride film, or a titanium nitride film are laminated as a barrier film. You may comprise.

  A capacitive insulating film 305 made of, for example, an SBT (SrTaBiO) film is formed on the lower electrode 304 as a ferroelectric film, and an upper electrode 306 made of a platinum film is formed on the capacitive insulating film 305. Has been. As described above, a ferroelectric capacitor (capacitor element) is formed by the lower electrode 304, the capacitor insulating film 305, and the upper electrode 306.

  On the first hydrogen barrier film 302, a second layer made of an ozone TEOS film for relaxing the step of the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 303 and the ferroelectric capacitor. An interlayer insulating film 307 is formed. An adhesion layer 308 made of a titanium film having a thickness of 1 to 10 nm is formed on the first interlayer insulating film 301 so as to cover the side surfaces of the first hydrogen barrier film 302 and the second interlayer insulating film 307. Has been. On the adhesion layer 308, a third hydrogen barrier film 309 made of a titanium aluminum nitride film is formed. Thus, the first hydrogen barrier film 302 and the third hydrogen barrier film 309 are connected via the adhesion layer 308.

  A contact plug 310 made of a W film is formed so as to extend through the first hydrogen barrier film 302 and the first interlayer insulating film 301. The contact plug 310 and the semiconductor substrate 300 implanted with arsenic or the like The lower electrode 304 of the ferroelectric capacitor is connected via the second hydrogen barrier film 303. A third interlayer insulating film 311 is formed on the first interlayer insulating film 301 so as to cover the third hydrogen barrier film 309. A wiring is usually formed on the third interlayer insulating film 311.

  As described above, the ferroelectric capacitor shown in FIG. 5 has a structure in which the periphery is completely covered by the first hydrogen barrier film 302, the second hydrogen barrier film 303, and the third hydrogen barrier film 309. Yes.

  Here, the feature of the semiconductor device according to the third embodiment is that an adhesion layer 308 is interposed between the first hydrogen barrier film 302 and the third hydrogen barrier film 309 so that the first hydrogen barrier film is formed. This is an improvement in adhesion between the 302 and the third hydrogen barrier film 309.

  As described above, according to the third embodiment, the adhesion layer 308 is interposed between the first hydrogen barrier film 302 and the third hydrogen barrier film 309, so that the first hydrogen barrier film 302 and the first hydrogen barrier film 302 3 can be improved in adhesion to the third hydrogen barrier film 309, so that the selection range of materials used for the first hydrogen barrier film 302 and the third hydrogen barrier film 309 is not limited, and the capacitor insulating film Since hydrogen can be prevented from diffusing into 305, deterioration of polarization characteristics of the capacitor insulating film 305 made of a ferroelectric film can be reduced. As a result, a highly reliable ferroelectric memory can be realized.

  In order to prevent hydrogen from diffusing into the capacitor insulating film 305 through the adhesion layer 308, the adhesion layer 308 includes the 3A, 4A, and 5A groups which are transition metals, and occludes hydrogen contained in these metals. By utilizing this capability, hydrogen can be further prevented from diffusing into the capacitor insulating film 305 through the adhesion layer 308, so that the deterioration of the polarization characteristics of the capacitor insulating film 305 made of a ferroelectric film can be further reduced. In particular, if titanium or tantalum is used as the transition metal, titanium or tantalum has a high diffusion coefficient, so that the effect of closely adhering the first hydrogen barrier film 302 and the third hydrogen barrier film 309 to each other can be further enhanced. Can do.

  In the third embodiment, the case where a silicon nitride film is used as the first hydrogen barrier film 302 and a titanium aluminum nitride film is used as the third hydrogen barrier film 309 has been described. However, the present invention is not limited thereto. Instead, any material can be used as long as it is a hydrogen barrier film.

  In the third embodiment, since the adhesion layer 308 is interposed between the first hydrogen barrier film 302 and the third hydrogen barrier film 309, the first hydrogen barrier film 302 and the adhesion layer 308 are separated from each other. A silicon oxide film is not formed between the third hydrogen barrier film 309 and the adhesion layer 308. Accordingly, hydrogen does not enter between the first hydrogen barrier film 302 and the third hydrogen barrier film 308.

  Further, the ferroelectric capacitor shown in FIG. 5 has a structure in which the lower electrode 304 serves as a capacity defining port, but instead, it may have a structure in which the upper electrode 306 serves as a capacity defining port.

  Further, in the third embodiment, the capacitor insulating film 305 is composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, such as a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 105 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 305 is made of a high dielectric constant film.

(Fourth embodiment)
A method for manufacturing a semiconductor device according to the fourth embodiment of the present invention will be described below with reference to FIGS. 6 (a) to 6 (e).

As shown in FIG. 6A, a silicon oxide film indicated by SiO ₂ to which, for example, boron and phosphorus are added on a semiconductor substrate 400 on which memory cell transistors (not shown) are formed. A first interlayer insulating film 401 made of a BPSG film is formed. Next, a first hydrogen barrier film 402 made of a silicon nitride film is formed on the first interlayer insulating film 401 by plasma CVD. Incidentally, when the first hydrogen barrier film 402 made of a silicon nitride film is formed by plasma CVD, generally a large amount of active hydrogen is generated, but before the ferroelectric capacitor described later is formed, the active hydrogen The influence of can be avoided in principle.

  Next, as shown in FIG. 6B, the first interlayer insulating film 401 and the first hydrogen barrier film 402 are made of a W film or a polysilicon film, and the lower end thereof is connected to the memory cell transistor. Plug 403 is formed. Next, after depositing a hydrogen barrier layer made of a titanium aluminum nitride film on the first hydrogen barrier film 402 and the contact plug 403, an iridium film and an iridium oxide film are sequentially formed on the hydrogen barrier layer from the bottom. A first conductive film made of a platinum film that promotes crystal growth of the ferroelectric film is deposited through an oxygen barrier layer made of the laminated body. Thereafter, the hydrogen barrier layer, the oxygen barrier layer, and the first conductive film are patterned to form the second hydrogen barrier film 404 and the lower electrode 405 connected to the upper end portion of the contact plug 403.

  Next, after forming a ferroelectric film made of an SBT film and a second conductive film made of a platinum film in order from the bottom on the lower electrode 405, the ferroelectric film and the second conductive film are patterned. Thus, the capacitor insulating film 406 and the upper electrode 407 are formed. In this manner, a ferroelectric capacitor (capacitive element) composed of the lower electrode 405, the capacitor insulating film 406 and the upper electrode 407 is formed, and the contact plug 403 is connected to the semiconductor substrate 400 via the second hydrogen barrier film 404. And the lower electrode 405 of the ferroelectric capacitor are electrically connected. Next, an insulating film made of an ozone TEOS film and relaxing the step in the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 404 and the ferroelectric capacitor on the first hydrogen barrier film 402. 408 is deposited. The semiconductor device manufacturing process described above is merely an example, and the present embodiment is not limited to this.

  Next, as shown in FIG. 6C, by patterning the insulating film 408, the surface of the first hydrogen barrier film 402 existing at the peripheral edge of the ferroelectric capacitor is exposed (here, Thus, the patterned insulating film 408 is called an insulating film 408a, and the first hydrogen barrier film 402 whose surface is exposed is called a first hydrogen barrier film 402a). Thus, by exposing at least a part of the outer region of the region where the ferroelectric capacitor is formed on the surface of the first hydrogen barrier film 402, the first hydrogen barrier film 402, the ferroelectric capacitor, Even when another layer is interposed between the first hydrogen barrier film 402 and the third hydrogen barrier film 410 to be described later, the first hydrogen barrier film 402 can be reliably connected. Adhesion with the third hydrogen barrier film 410 can be reliably improved.

  As shown in FIG. 6C, a surface layer 409 is formed on the surface of the exposed portion of the first hydrogen barrier film 402a. That is, since patterning is usually performed by dry etching or wet etching, the residue of the gas used in the dry etching, the residue of the chemical solution used in the wet etching, these gas or chemical solution and the first hydrogen barrier A reaction layer with the film 402 or an oxide layer or the like generated by ashing or the like when removing the resist used as a mask during patterning is formed on the surface of the exposed portion of the first hydrogen barrier film 402 as the surface layer 409. It is formed.

  Next, as shown in FIG. 6D, the surface layer 409 in the first hydrogen barrier film 402a is removed by washing with hydrofluoric acid (here, the surface layer 409 is removed). The later first hydrogen barrier film 402 is referred to as a first hydrogen barrier film 402b). In this way, only the surface layer can be easily removed by controlling the concentration of hydrofluoric acid and the cleaning time.

  Next, as shown in FIG. 6E, a first layer made of a titanium aluminum nitride film is formed on the first hydrogen barrier film 402b after the surface layer 409 is removed so as to cover the entire insulating film 408a. 3 hydrogen barrier film 410 is formed. In FIG. 6E, the first hydrogen barrier film 402b and the third hydrogen barrier film 410 are shown in a patterned state. However, they may not be patterned.

  As described above, according to the fourth embodiment, the first hydrogen barrier film 402 is formed on the surface of the first hydrogen barrier film 402, which is a factor that reduces the adhesion between the first hydrogen barrier film 402 and the third hydrogen barrier film 410. After removing the altered surface layer 409, the first hydrogen barrier film 402 and the third hydrogen barrier film 410 are adhered to each other in order to connect the first hydrogen barrier film 402 and the third hydrogen barrier film 410. Therefore, the deterioration of the polarization characteristics of the capacitive insulating film 406 made of a ferroelectric film can be reduced. As a result, a highly reliable dielectric memory can be realized.

  In the fourth embodiment, the first hydrogen barrier film 402 and the third hydrogen hydrogen barrier film 410 are not limited to these as long as they contain the same kind of atoms.

  In the fourth embodiment, when the surface layer 409 is removed, wet etching is performed using hydrofluoric acid as a chemical solution, but dry etching using plasma using an inert gas such as argon gas is performed. May be. Thus, even when an aluminum oxide film or the like that is easily damaged by wet etching using hydrofluoric acid as a chemical solution is used as the first hydrogen barrier film 402, the first hydrogen barrier film 402 is used. Only the surface layer 409 can be removed without affecting the inside. Further, even the surface layer 409 that cannot be chemically removed by wet etching using hydrofluoric acid as a chemical solution can be removed by a physical method by ejecting atoms.

  In the fourth embodiment, for example, the ferroelectric capacitor shown in FIG. 6E has a structure in which the lower electrode 405 serves as a capacity defining port, but instead, the upper electrode 407 has a capacity defining function. It may be a mouth structure.

  In the fourth embodiment, the capacitor insulating film 406 is formed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 406 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 406 is made of a high dielectric constant film.

(Fifth embodiment)
A semiconductor device manufacturing method according to the fifth embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 7A, a silicon oxide film represented by SiO ₂ to which, for example, boron and phosphorus are added on a semiconductor substrate 500 on which memory cell transistors (not shown) are formed. A first interlayer insulating film 501 made of a BPSG film is formed. Next, a first hydrogen barrier film 502 made of a silicon nitride film is formed on the first interlayer insulating film 501 by plasma CVD. Incidentally, when the first hydrogen barrier film 502 made of a silicon nitride film is formed by the plasma CVD method, generally, a large amount of active hydrogen is generated, but before the ferroelectric capacitor described later is formed, the active hydrogen The influence of can be avoided in principle.

  Next, as shown in FIG. 7B, the first interlayer insulating film 501 and the first hydrogen barrier film 502 are made of a W film or a polysilicon film, and the lower end thereof is connected to the memory cell transistor. A plug 503 is formed. Next, after depositing a hydrogen barrier layer made of a titanium aluminum nitride film on the first hydrogen barrier film 502 and the contact plug 503, an iridium film and an iridium oxide film are sequentially formed on the hydrogen barrier layer from the bottom. A first conductive film made of a platinum film that promotes crystal growth of the ferroelectric film is deposited through an oxygen barrier layer made of the laminated body. Thereafter, the hydrogen barrier layer, the oxygen barrier layer, and the first conductive film are patterned to form a second hydrogen barrier film 504 and a lower electrode 505 connected to the upper end portion of the contact plug 503.

  Next, a ferroelectric film made of an SBT film and a second conductive film made of a platinum film are formed on the lower electrode 505 in order from the bottom, and then the ferroelectric film and the second conductive film are patterned. Thus, the capacitor insulating film 506 and the upper electrode 507 are formed. In this manner, a ferroelectric capacitor (capacitor element) composed of the lower electrode 505, the capacitor insulating film 506, and the upper electrode 507 is formed, and the contact plug 503 is connected to the semiconductor substrate 500 via the second hydrogen barrier film 504. Are electrically connected to the lower electrode 505 of the ferroelectric capacitor. Next, an insulating film which is formed of an ozone TEOS film and relaxes a step in the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 504 and the ferroelectric capacitor on the first hydrogen barrier film 502. 508 is deposited. The semiconductor device manufacturing process described above is merely an example, and the present embodiment is not limited to this.

  Next, as shown in FIG. 7C, the surface of the first hydrogen barrier film 502 existing at the periphery of the ferroelectric capacitor is exposed by patterning the insulating film 508 (note that Thus, the patterned insulating film 508 is referred to as an insulating film 508a). Thus, by exposing at least a part of the outer region of the region where the ferroelectric capacitor is formed on the surface of the first hydrogen barrier film 502, the first hydrogen barrier film 502, the ferroelectric capacitor, Even when another layer is interposed between the first hydrogen barrier film 502 and the third hydrogen barrier film 510 to be described later, the first hydrogen barrier film 502 can be reliably connected. Adhesion with the third hydrogen barrier film 510 can be reliably improved.

  Next, as shown in FIG. 7D, by performing a rapid heating process in an oxygen atmosphere, a surface of the first hydrogen barrier film 502 made of a silicon nitride film is formed on a surface of a silicon oxide layer indicated by, for example, Si0. A surface oxide layer 509 is formed (here, the first hydrogen barrier film 502 after the surface oxide layer 509 is formed is referred to as a first hydrogen barrier film 502a). Further, the surface of the first hydrogen barrier film is not damaged by performing the rapid heat treatment in an oxygen atmosphere in the range of 400 ° C. to 800 ° C. without damaging the underlying portion of the first hydrogen barrier film 502. The surface oxide layer 509 can be formed by oxidizing only the surface.

  Next, as shown in FIG. 7E, a third hydrogen barrier film 510 made of an aluminum oxide film is formed on the first hydrogen barrier film 502a so as to cover the entire insulating film 508a. FIG. 7E shows a state in which the first hydrogen barrier film 502a and the third hydrogen barrier film 510 are patterned. However, the patterning may be omitted.

  As described above, according to the fifth embodiment, the surface oxide layer 509 oxidized in the first hydrogen barrier film 502 and the third hydrogen containing oxygen atoms that promote adhesion to the surface oxide layer 509 are obtained. In order to connect the barrier film 510, the first hydrogen barrier film 502 and the third hydrogen barrier film 510 are not merely physically connected to each other but are connected by chemical bonds of the same kind of atoms. Therefore, the adhesion between the first hydrogen barrier film 502 and the third hydrogen barrier film 510 can be improved, so that deterioration of the polarization characteristics of the capacitive insulating film 506 made of a ferroelectric film can be reduced. it can. In this case, oxygen atoms are cross-linked at a portion where the first hydrogen barrier film 502 and the third hydrogen barrier film 510 are connected, and the first hydrogen barrier film 502 and the third hydrogen barrier film 510 are Therefore, an oxide film having a role of a hydrogen diffusion path is not formed.

  In the fifth embodiment, when the surface of the first hydrogen barrier film 502 is oxidized to form the surface oxide layer 509, a rapid heating process is performed in an oxygen atmosphere, but the surface is exposed to oxygen plasma. Thus, the surface oxide layer 509 may be formed. In this case, the surface oxide layer 509 can be formed at a low temperature in the range of 300 ° C. to 600 ° C., so that damage to the underlying portion of the first hydrogen barrier film 502 can be further reduced.

  In the fifth embodiment, a surface oxide layer 509 is formed by oxidizing the surface of the first hydrogen barrier film 502, and the surface oxide layer 509 and the second hydrogen barrier film 510 containing oxygen atoms are combined. The case where the adhesion between the first hydrogen barrier film 502 and the third hydrogen barrier film 510 is improved by connection is described. However, a surface nitride layer is formed by nitriding the surface of the first hydrogen barrier film 502 using, for example, a titanium aluminum oxide film, and a third layer using, for example, a titanium aluminum nitride film containing the surface nitride layer and nitrogen is used. Even in the case of connecting to the hydrogen barrier film 510, the nitrogen atoms contained in the third hydrogen barrier film 510 have an action of promoting adhesion to the surface nitride layer. Adhesion between the hydrogen barrier film 502 and the third hydrogen barrier film 510 can be improved.

  In the fifth embodiment, for example, the ferroelectric capacitor shown in FIG. 7E has a structure in which the lower electrode 505 serves as a capacity defining port. Instead, the upper electrode 507 has a capacity defining function. It may be a mouth structure.

  In the fifth embodiment, the capacitor insulating film 506 is formed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Although the capacitor insulating film 506 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 506 is made of a high dielectric constant film.

(Sixth embodiment)
A semiconductor device manufacturing method according to the sixth embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 8A, a silicon oxide film represented by SiO ₂ to which, for example, boron and phosphorus are added on a semiconductor substrate 600 on which memory cell transistors (not shown) are formed. A first interlayer insulating film 601 made of a BPSG film is formed. Next, a first hydrogen barrier film 602 made of a silicon nitride film is formed on the first interlayer insulating film 601 by plasma CVD. Incidentally, when the first hydrogen barrier film 602 made of a silicon nitride film is formed by the plasma CVD method, generally a large amount of active hydrogen is generated, but before the ferroelectric capacitor described later is formed, the active hydrogen The influence of can be avoided in principle.

  Next, as shown in FIG. 8B, the first interlayer insulating film 601 and the first hydrogen barrier film 602 are made of a W film or a polysilicon film, and the lower end thereof is connected to the memory cell transistor. A plug 603 is formed. Next, after depositing a hydrogen barrier layer made of a titanium aluminum nitride film on the first hydrogen barrier film 602 and the contact plug 603, an iridium film and an iridium oxide film are sequentially formed on the hydrogen barrier layer from the bottom. A first conductive film made of a platinum film that promotes crystal growth of the ferroelectric film is deposited through an oxygen barrier layer made of the laminated body. Thereafter, the hydrogen barrier layer, the oxygen barrier layer, and the first conductive film are patterned to form a second hydrogen barrier film 604 and a lower electrode 605 that are connected to the upper end portion of the contact plug 603.

  Next, a ferroelectric film made of an SBT film and a second conductive film made of a platinum film are formed on the lower electrode 605 in order from the bottom, and then the ferroelectric film and the second conductive film are patterned. Thus, the capacitor insulating film 606 and the upper electrode 607 are formed. In this manner, a ferroelectric capacitor including the lower electrode 605, the capacitor insulating film 606, and the upper electrode 607 is formed, and the contact plug 603 is connected to the semiconductor substrate 600 and the ferroelectric via the second hydrogen barrier film 604. The lower electrode 605 of the capacitor is electrically connected. Next, an insulating film which is formed of an ozone TEOS film and relaxes a step in the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 604 and the ferroelectric capacitor on the first hydrogen barrier film 602. 608 is deposited. The semiconductor device manufacturing process described above is merely an example, and the present embodiment is not limited to this.

  Next, as shown in FIG. 8C, by patterning the insulating film 608, the surface of the first hydrogen barrier film 602 existing on the peripheral edge of the ferroelectric capacitor is exposed (here, Thus, the patterned insulating film 608 is referred to as an insulating film 608a). In this way, by exposing at least a part of the outer region of the region where the ferroelectric capacitor is formed on the surface of the first hydrogen barrier film 602, the first hydrogen barrier film 602, the ferroelectric capacitor, Even when another layer is interposed between the first hydrogen barrier film 602 and the third hydrogen barrier film 610 to be described later, the first hydrogen barrier film 602 can be reliably connected. Adhesion with the third hydrogen barrier film 610 can be reliably improved.

  Next, as shown in FIG. 8D, an adhesion layer 609 made of a titanium film is formed on the first hydrogen barrier film 602 so as to cover the insulating film 608a.

  Next, as shown in FIG. 8E, a third hydrogen barrier film 610 made of a titanium aluminum nitride film is formed on the adhesion layer 609. In FIG. 8E, the first hydrogen barrier film 602, the adhesion layer 609, and the third hydrogen barrier film 610 are shown in a patterned state, but they may not be patterned.

  As described above, according to the sixth embodiment, by forming the adhesion layer 609 between the first hydrogen barrier film 602 and the third hydrogen barrier film 610, 3 can improve the adhesion to the third hydrogen barrier film 610, so that the range of selection of materials used for the first hydrogen barrier film 602 and the third hydrogen barrier film 610 is not limited, and the ferroelectric body Degradation of the polarization characteristics of the capacitor insulating film 606 made of a film can be reduced.

  In order to prevent hydrogen from diffusing into the capacitor insulating film 606 through the adhesion layer 609, the adhesion layer 609 includes the transition metals 3A, 4A, and 5A, and occludes hydrogen contained in these metals. By utilizing this capability, hydrogen can be further prevented from diffusing into the capacitor insulating film 606 through the adhesion layer 609, so that the deterioration of the polarization characteristics of the capacitor insulating film 606 made of a ferroelectric film can be further reduced. In particular, if titanium or tantalum is used as the transition metal, titanium or tantalum has a high diffusion coefficient. Therefore, due to mutual diffusion between the adhesion layer 609 and the first hydrogen barrier film 602 and the third hydrogen barrier film 610. The effect of bringing the first hydrogen barrier film 602 and the third hydrogen barrier film 610 into close contact with each other can be further enhanced.

  In the sixth embodiment, the case where a silicon nitride film is used as the first hydrogen barrier film 602 and a titanium aluminum nitride film is used as the third hydrogen barrier film 610 has been described. However, the present invention is not limited thereto. Instead, any material can be used as long as it is a hydrogen barrier film.

  In the sixth embodiment, for example, the ferroelectric capacitor shown in FIG. 8E has a structure in which the lower electrode 605 serves as a capacity defining port, but instead, the upper electrode 607 has a capacity defining function. It may be a mouth structure.

  Further, in the sixth embodiment, the capacitor insulating film 606 is a case of being composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 606 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 606 is made of a high dielectric constant film.

(Seventh embodiment)
A method for manufacturing a semiconductor device according to the seventh embodiment of the present invention will be described below with reference to FIGS. 9 (a) to 9 (e).

As shown in FIG. 9A, a silicon oxide film represented by SiO ₂ to which, for example, boron and phosphorus are added on a semiconductor substrate 700 on which memory cell transistors (not shown) are formed. A first interlayer insulating film 701 made of a BPSG film is formed. Next, a first hydrogen barrier film 702 made of a silicon nitride film is formed on the first interlayer insulating film 701 by plasma CVD. Incidentally, when the first hydrogen barrier film 702 made of a silicon nitride film is formed by the plasma CVD method, generally a large amount of active hydrogen is generated, but before the ferroelectric capacitor described later is formed, the active hydrogen The influence of can be avoided in principle.

  Next, as shown in FIG. 9B, the first interlayer insulating film 701 and the first hydrogen barrier film 702 are made of a W film or a polysilicon film, and a lower end thereof is connected to the memory cell transistor. A plug 703 is formed. Next, after depositing a hydrogen barrier layer made of a titanium aluminum nitride film on the first hydrogen barrier film 702 and the contact plug 703, an iridium film and an iridium oxide film are sequentially formed on the hydrogen barrier layer from the bottom. A first conductive film made of a platinum film that promotes crystal growth of the ferroelectric film is deposited through an oxygen barrier layer made of the laminated body. Thereafter, the hydrogen barrier layer, the oxygen barrier layer, and the first conductive film are patterned to form a second hydrogen barrier film 704 and a lower electrode 705 connected to the upper end portion of the contact plug 703.

  Next, after forming a ferroelectric film made of an SBT film and a second conductive film made of a platinum film in order from the bottom on the lower electrode 705, the ferroelectric film and the second conductive film are patterned. Thus, the capacitor insulating film 706 and the upper electrode 707 are formed. In this manner, a ferroelectric capacitor including the lower electrode 705, the capacitor insulating film 706, and the upper electrode 707 is formed, and the contact plug 703 is connected to the semiconductor substrate 700 and the ferroelectric via the second hydrogen barrier film 704. The lower electrode 705 of the capacitor is electrically connected. Next, an insulating film that is formed of an ozone TEOS film and relaxes the step in the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 704 and the ferroelectric capacitor on the first hydrogen barrier film 702. 708 is deposited. The semiconductor device manufacturing process described above is merely an example, and the present embodiment is not limited to this.

  Next, as shown in FIG. 9C, the surface of the first hydrogen barrier film 702 formed on the peripheral portion of the ferroelectric capacitor is exposed by patterning the insulating film 708 (here, Thus, the patterned insulating film 708 is referred to as an insulating film 708a). Thus, by exposing at least a part of the outer region of the region where the ferroelectric capacitor is formed on the surface of the first hydrogen barrier film 702, the first hydrogen barrier film 702, the ferroelectric capacitor, Even if another layer is interposed between the first hydrogen barrier film 702 and the third hydrogen barrier film 709 made of, for example, a titanium aluminum nitride film to be described later, the first hydrogen barrier film 702 can be reliably connected. The adhesion between the first hydrogen barrier film 702 and the third hydrogen barrier film 709 can be improved with certainty.

  Next, as shown in FIG. 9D, the exposed surface of the first hydrogen barrier film 702 is dry-etched using an inert gas such as argon or nitrogen to thereby form the first hydrogen barrier film 702 and Since atoms of the same type (nitrogen atoms in this embodiment) that are commonly included in the third hydrogen barrier film 709 dissociate hands that are bonded to other atoms included in the first hydrogen barrier film 702. In the exposed surface region 702a of the first hydrogen barrier film 702, the number of unbonded bonds (bonding of nitrogen atoms in this embodiment) increases.

  Next, as shown in FIG. 9E, a third hydrogen barrier film 709 made of a titanium aluminum nitride film so as to cover a portion of the region 702a on the surface of the first hydrogen barrier film 702 by sputtering. Form. In FIG. 9E, the first hydrogen barrier film 702 and the third hydrogen barrier film 709 are shown in a patterned state. However, the patterning may be omitted.

  As described above, according to the seventh embodiment, the first hydrogen barrier film 702 and the third hydrogen barrier film 709 are commonly included in the exposed surface of the first hydrogen barrier film 702. Since one kind of atom dissociates a hand in a bonded state with another atom included in the first hydrogen barrier 702 by etching and becomes a hand of a bond in an unbonded state, the first hydrogen barrier film 702 And the third hydrogen barrier film 709 are not merely physically connected to each other but are connected by chemical bonds, so that the first hydrogen barrier film 702 and the third hydrogen barrier film to be formed later are connected. Adhesion with 709 can be improved. Accordingly, it is possible to reduce deterioration of the polarization characteristics of the capacitor insulating film 706 made of a ferroelectric film or a high dielectric constant film. In this case, a silicon oxide film having a role of a hydrogen diffusion path is not formed in a portion where the first hydrogen barrier film 702 and the third hydrogen barrier film 509 are connected.

  In the seventh embodiment, the case where a silicon nitride film is used as the first hydrogen barrier film 702 and a titanium aluminum nitride film is used as the third hydrogen barrier film 709 has been described. However, the present invention is not limited thereto. Instead, any material can be used as long as it is a hydrogen barrier film.

  In the seventh embodiment, for example, the ferroelectric capacitor shown in FIG. 9E has a structure in which the lower electrode 705 serves as a capacity defining port. Instead, the upper electrode 707 has a capacity defining function. It may be a mouth structure.

  Further, in the seventh embodiment, the capacitor insulating film 706 is composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, for example, a film made of a PZT system, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 706 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 706 is made of a high dielectric constant film.

(Eighth embodiment)
A method for manufacturing a semiconductor device according to the eighth embodiment of the present invention will be described below with reference to FIGS. 10 (a) to 10 (e).

As shown in FIG. 10A, a silicon oxide film indicated by SiO ₂ to which, for example, boron and phosphorus are added on a semiconductor substrate 800 on which memory cell transistors (not shown) are formed. A first interlayer insulating film 801 made of a BPSG film is formed. Next, a first hydrogen barrier film 802 made of a silicon nitride film is formed on the first interlayer insulating film 801 by plasma CVD. Incidentally, when the first hydrogen barrier film 802 made of a silicon nitride film is formed by the plasma CVD method, generally a large amount of active hydrogen is generated, but before the ferroelectric capacitor described later is formed, the active hydrogen The influence of can be avoided in principle.

  Next, as shown in FIG. 10B, the first interlayer insulating film 801 and the first hydrogen barrier film 802 are made of a W film or a polysilicon film, and the lower end thereof is connected to the memory cell transistor. A plug 803 is formed. Next, after depositing a hydrogen barrier layer made of a titanium aluminum nitride film on the first hydrogen barrier film 802 and the contact plug 803, an iridium film and an iridium oxide film are sequentially formed on the hydrogen barrier layer from the bottom. A first conductive film made of a platinum film that promotes crystal growth of the ferroelectric film is deposited through an oxygen barrier layer made of the laminated body. Thereafter, the hydrogen barrier layer, the oxygen barrier layer, and the first conductive film are patterned to form a second hydrogen barrier film 804 and a lower electrode 805 connected to the upper end portion of the contact plug 803.

  Next, after forming a ferroelectric film made of an SBT film and a second conductive film made of a platinum film on the lower electrode 805 in order from the bottom, the ferroelectric film and the second conductive film are patterned. Thus, the capacitor insulating film 806 and the upper electrode 807 are formed. In this way, a ferroelectric capacitor including the lower electrode 805, the capacitor insulating film 806, and the upper electrode 807 is formed, and the contact plug 803 is connected to the semiconductor substrate 800 and the ferroelectric via the second hydrogen barrier film 804. The lower electrode 805 of the capacitor is electrically connected. Next, an insulating film that is formed of an ozone TEOS film and relaxes a step in the ferroelectric capacitor so as to cover the side surface of the second hydrogen barrier film 804 and the ferroelectric capacitor on the first hydrogen barrier film 802. 808 is deposited. The semiconductor device manufacturing process described above is merely an example, and the present embodiment is not limited to this.

  Next, as shown in FIG. 10C, the surface of the first hydrogen barrier film 802 formed on the peripheral edge of the ferroelectric capacitor is exposed by patterning the insulating film 808 (note that Thus, the patterned insulating film 808 is referred to as an insulating film 808a). Thus, by exposing at least part of the outer region of the region where the ferroelectric capacitor is formed on the surface of the first hydrogen barrier film 802, the first hydrogen barrier film 802, the ferroelectric capacitor, Even if another layer is interposed between the first hydrogen barrier film 802 and the third hydrogen barrier film 809 made of, for example, a titanium aluminum nitride film described later, the first hydrogen barrier film 802 can be reliably connected. The adhesion between the first hydrogen barrier film 802 and the third hydrogen barrier film 809 can be improved with certainty.

  Next, as shown in FIGS. 10D and 10E, the same species contained in common to the first hydrogen barrier film 802 and the third hydrogen barrier film 809 on the first hydrogen barrier film 802. A third hydrogen barrier film 809 made of a titanium aluminum nitride film is formed in an atmosphere containing the above atoms (in this embodiment, nitrogen atoms). A specific example is a reactive sputtering method in which titanium aluminum sputtered from a target made of titanium aluminum is nitrided in a nitrogen atmosphere. Note that FIG. 10E shows the final shape in which the first hydrogen barrier film 802 and the third hydrogen barrier film 809 are patterned, but the pattern may not be patterned.

  As described above, according to the eighth embodiment, the third hydrogen barrier film 809 is formed in an atmosphere containing atoms that are commonly included in the first hydrogen barrier film 802 and the third hydrogen barrier film 809. By being formed, atoms commonly included in the first hydrogen barrier film 802 and the third hydrogen barrier film 809 in the atmosphere are connected to the first hydrogen barrier film 802 and the third hydrogen barrier film 809. This is taken into the area 802a shown in FIG. Therefore, the first hydrogen barrier film 802 and the third hydrogen barrier film 809 are not merely physically connected to each other but are connected by chemical bonds. 3 can be improved in adhesion to the hydrogen barrier film 809, so that deterioration of the polarization characteristics of the capacitor insulating film 806 made of a ferroelectric film or a high dielectric constant film can be reduced. In this case, a silicon oxide film having a role of a hydrogen diffusion path is not formed in a portion where the first hydrogen barrier film 802 and the third hydrogen barrier film 809 are connected.

  In the eighth embodiment, the method of performing reactive sputtering in a nitrogen atmosphere when the first hydrogen barrier film 802 and the third hydrogen barrier film 809 contain nitrogen atoms has been described. The invention is not limited to this, and reactive sputtering may be performed in an atmosphere containing atoms commonly contained in the hydrogen barrier film.

  In the eighth embodiment, for example, the ferroelectric capacitor shown in FIG. 10E has a structure in which the lower electrode 805 serves as a capacity defining port. Instead, the upper electrode 807 has a capacity defining function. It may be a mouth structure.

  Further, in the eighth embodiment, the capacitor insulating film 806 is composed of an SBT film as a ferroelectric film, but instead of this, a material that can be reduced, such as a film made of PZT, The same effect can be obtained even when the film is made of a BLT film, a BST film, or a tantalum oxide film. Further, although the capacitor insulating film 806 is made of a ferroelectric film, it goes without saying that the same effect can be obtained even when the capacitor insulating film 806 is made of a high dielectric constant film.

  In each of the above embodiments, the case where the structure of the ferroelectric capacitor is a stack type structure has been described, but the structure of the capacitor in the present invention is not limited to this.

  As described above, the present invention is useful for a semiconductor device that reduces deterioration of polarization characteristics of a capacitive insulating film made of a ferroelectric film or a high dielectric constant film, and a manufacturing method thereof.

1 is a cross-sectional view of a semiconductor device according to a first embodiment of the present invention. It is a graph which shows the polarization characteristic of the ferroelectric film in the 1st Embodiment of this invention. It is TEM sectional drawing which shows the connection part of the hydrogen barrier films | membranes in the 1st Embodiment of this invention. It is sectional drawing of the semiconductor device of the 2nd Embodiment of this invention. It is sectional drawing of the semiconductor device of the 3rd Embodiment of this invention. (A)-(e) is sectional drawing which shows the manufacturing method of the semiconductor device of the 4th Embodiment of this invention. (A)-(e) is sectional drawing which shows the manufacturing method of the semiconductor device of the 5th Embodiment of this invention. (A)-(e) is sectional drawing which shows the manufacturing method of the semiconductor device of the 6th Embodiment of this invention. (A)-(e) is sectional drawing which shows the manufacturing method of the semiconductor device of the 7th Embodiment of this invention. (A)-(e) is sectional drawing which shows the manufacturing method of the semiconductor device of the 8th Embodiment of this invention. It is sectional drawing of the semiconductor device which has the conventional ferroelectric capacitor. It is sectional drawing of the semiconductor device which the present inventors used for the object of experiment. It is a graph which shows the polarization characteristic of the ferroelectric film in the semiconductor device which the present inventors used for the object of experiment. It is TEM sectional drawing which shows the connection part of hydrogen barrier films | membranes in the semiconductor device which the present inventors used for the object of experiment. (A) is TEM sectional drawing of the experimental sample used for the analysis of the connection part of hydrogen barrier films | membranes, (b) is for EELS analysis result with respect to the experimental sample of the connection part of hydrogen barrier films | membranes It is TEM sectional drawing and a related figure of loss energy and density.

Claims (11)

A first hydrogen barrier film;
A capacitive element formed on the first hydrogen barrier film;
A second hydrogen barrier film formed so as to cover the capacitive element,
The first hydrogen barrier film and the second hydrogen barrier film are in close contact with each other so that a silicon oxide film is not interposed in a boundary region where the first hydrogen barrier film and the second hydrogen barrier film are in contact with each other. ,
The first hydrogen barrier film has a region formed by oxidation on an upper surface or a side surface,
The second hydrogen barrier film contains oxygen;
Wherein the first hydrogen barrier film and the second hydrogen barrier film, through the region formed by the oxidation in the peripheral portion of the capacitor, you characterized in that it is in close contact with the oxygen binding half Conductor device. A first hydrogen barrier film;
A capacitive element formed on the first hydrogen barrier film;
A second hydrogen barrier film formed so as to cover the capacitive element,
The first hydrogen barrier film and the second hydrogen barrier film are in close contact with each other so that a silicon oxide film is not interposed in a boundary region where the first hydrogen barrier film and the second hydrogen barrier film are in contact with each other. ,
The first hydrogen barrier film has a region formed by nitriding on an upper surface or a side surface,
The second hydrogen barrier film contains nitrogen;
Wherein the first hydrogen barrier film and the second hydrogen barrier film, through the region formed with the nitride in the peripheral portion of the capacitor, characterized in that it is in close contact with the nitrogen-binding half Conductor device. The first hydrogen barrier film and the second hydrogen barrier film contain metal atoms that adhere the first hydrogen barrier film and the second hydrogen barrier film by mutual diffusion,
Wherein the first hydrogen barrier film and the second hydrogen barrier film by the metal atom is interdiffusion at the periphery of the capacitor, according to claim 1 or 2, characterized in that in close contact A semiconductor device according to 1. The semiconductor device according to claim 3 , wherein the metal atom is Ti or Ta. A first hydrogen barrier film;
A capacitive element formed on the first hydrogen barrier film;
A second hydrogen barrier film formed so as to cover the capacitive element,
The first hydrogen barrier film and the second hydrogen barrier film are in close contact with each other so that a silicon oxide film is not interposed in a boundary region where the first hydrogen barrier film and the second hydrogen barrier film are in contact with each other. ,
Comprising an adhesive layer on the boundary region between the first hydrogen barrier film and the second hydrogen barrier film,
Wherein the first hydrogen barrier film and the second hydrogen barrier film, semi-conductor device you characterized by being connected via the adhesion layer. The semiconductor device according to claim 5 , wherein the adhesion layer occludes hydrogen. The semiconductor device according to claim 5 , wherein the adhesion layer includes a transition metal. The semiconductor device according to claim 5 , wherein the adhesion layer contains Ti or Ta. The first hydrogen barrier film and the second hydrogen barrier film, the semiconductor device according to any one of claims 1 to 8, characterized in that a film made of the same material. The capacitive element includes a lower electrode formed on the first hydrogen barrier film, a capacitive insulating film formed on the lower electrode, and an upper electrode formed on the capacitive insulating film. Prepared,
The capacitor insulating film, a semiconductor device according to any one of claims 1 to 9, characterized in that a ferroelectric film or a high dielectric constant film. The capacitor insulating _{film, SrBi 2 (Ta x Nb 1} -x) 2 O 9, Pb (Zr x Ti 1-x) O 3, (Ba x Sr 1-x) TiO 3, (Bi x La 1-x 11. The semiconductor device according to claim 10 , wherein the semiconductor device is made of ₄ Ti ₃ O ₁₂ (wherein X satisfies a relationship of 0 ≦ x ≦ 1) or Ta ₂ O ₅ .