JP2003338609A - Semiconductor device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely and easily suppress the reduction reaction of a capacity insulating film in a process performed in a reducing gas atmosphere. <P>SOLUTION: At least a part of a capacitive element 112 comprising a capacitive lower electrode 109, a capacitance insulating film 110 and a capacitive upper electrode 111 is coated with a second hydrogen barrier film 113 formed of at least one of bismuth tantalate, bismuth niobate and bismuth tantalum niobate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device and a manufacturing method thereof, and more particularly to a semiconductor memory device using a capacitive insulating film made of an insulating metal oxide and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, along with the progress of digital technology, the tendency to process and store a large amount of data has been promoted, and electronic equipment has become more sophisticated and semiconductor devices used in the electronic equipment have become more sophisticated. The miniaturization of the semiconductor element in it is rapidly progressing. Therefore, for example, in order to realize high integration of a dynamic RAM, a technique of using a high dielectric material as a material for a capacitive insulating film in place of conventional silicon oxide or nitride has been widely researched and developed. Also,
Aiming at the practical application of a non-volatile RAM capable of an unprecedented low operating voltage and high-speed writing / reading, research and development on a semiconductor memory device using a ferroelectric film having a spontaneous polarization characteristic are actively conducted. .

The most important task for realizing the semiconductor memory device as described above is to develop a process capable of integrating a capacitive element in a CMOS integrated circuit without deterioration of characteristics.

By the way, for example, when an attempt is made to integrate a conventional capacitive element using a ferroelectric film into a CMOS integrated circuit, a process performed in an atmosphere of a reducing gas such as hydrogen, which is indispensable in the CMOS integrated process, is performed. However, the capacitance insulating film is reduced and the ferroelectric characteristics of the capacitance element are deteriorated.

Specifically, in a manufacturing process of a semiconductor memory device using a thin film made of a metal oxide material such as a ferroelectric material as a capacitive insulating film, generally, after forming a capacitive element,
The capacitative element is covered with an interlayer insulating film mainly for electrical insulation between the capacitative elements. At this time, a reducing gas such as hydrogen is generated as a reaction by-product. Further, in manufacturing a semiconductor memory device, it is necessary to perform heat treatment in a gas mixed with hydrogen in order to repair deterioration of transistor characteristics that occurs during manufacturing. However, it is known that the process performed in these reducing gas atmospheres causes deterioration of ferroelectric characteristics, particularly deterioration of leak current characteristics.

As a measure for preventing the characteristic deterioration of the capacitive element due to such reducing gas, for example, the characteristic deterioration of the ferroelectric capacitor, aluminum oxide or titanium nitride is used to prevent hydrogen and the like from entering the capacitor section. There has been proposed a method of covering the capacitor portion with a hydrogen barrier film made of, for example.

[0007]

However, when a conventional hydrogen barrier film material such as aluminum oxide or titanium nitride is used, it is possible to form a very dense hydrogen barrier film by an atomic layer deposition method or the like. Since it is necessary to use a device or perform a special process, there arises a problem that the manufacturing cost becomes high. That is, a hydrogen barrier film that can be formed with a simple manufacturing method and structure and that can reliably prevent the intrusion of hydrogen and the like has not yet been realized.

In view of the above, the present invention surely and easily suppresses the reduction reaction of the capacitive insulating film in the process performed in a reducing gas atmosphere, thereby realizing a semiconductor memory device having excellent characteristics at low cost. The purpose is to be able to.

[0009]

In order to achieve the above object, the inventors of the present invention have examined various materials for suitability as hydrogen barrier film materials, and as a result, have found that bismuth tantalate, bismuth niobate or tantalum niobate. It has been found that by using bismuth, it is possible to easily realize a hydrogen barrier film capable of reliably preventing the intrusion of hydrogen and the like while preventing generation of hydrogen during film formation and performing no special process.

The present invention has been made on the basis of the above findings, and specifically, a semiconductor device according to the present invention is configured so as to contact a capacitor insulating film and at least one surface of the capacitor insulating film. On the premise of a semiconductor device including a capacitive element composed of an electrode provided on a substrate, at least a part of the capacitive element is formed by a hydrogen barrier film made of at least one of bismuth tantalate, bismuth niobate and bismuth tantalum niobate. It is covered.

According to the semiconductor device of the present invention, since the capacitive element is covered with the hydrogen barrier film, it is possible to prevent the reducing gas from diffusing into the capacitive insulating film. It is possible to reliably suppress the reduction reaction of the capacitive insulating film in the process performed in a gas atmosphere, and thereby prevent the deterioration of the capacitive insulating film characteristics such as the ferroelectric characteristics, especially the leakage current characteristics.
Further, as a hydrogen barrier film material, bismuth tantalate,
Since bismuth niobate or bismuth tantalum niobate is used, the hydrogen barrier film can be easily formed without performing a special process. Therefore, a semiconductor memory device having excellent characteristics can be realized at low cost.

In the present specification, "hydrogen barrier film"
Means a barrier film against diffusion of reducing gas such as hydrogen gas.

In the semiconductor device of the present invention, it is preferable that at least a part of the hydrogen barrier film is in direct contact with the capacitive insulating film.

In this way, it is not necessary to form an interlayer film between the capacitive insulating film and the hydrogen barrier film, so that the semiconductor memory device can be easily manufactured.

In the semiconductor device of the present invention, the capacitance insulating film is preferably made of a ferroelectric material or a high dielectric material.

In this way, when a bismuth layered ferroelectric material such as strontium bismuth tantalate is used as the material of the capacitive insulating film, the hydrogen barrier film material of the present invention contains the same constituent elements as the bismuth layered ferroelectric material. Since it has a crystal structure similar to that of the bismuth layered ferroelectric substance, characteristic deterioration of the capacitive insulating film due to diffusion of constituent elements of the hydrogen barrier film material does not occur. That is, the hydrogen barrier film material of the present invention is particularly effective in a semiconductor memory device using a bismuth layered ferroelectric substance as a capacitor insulating film material.

In the semiconductor device of the present invention, the hydrogen barrier film preferably has a thickness of 5 nm or more and 200 nm or less.

This makes it possible to reliably prevent the reduction reaction of the capacitive insulating film due to the reducing gas such as hydrogen while miniaturizing the semiconductor memory device.

A method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device having a capacitive element including a capacitive insulating film and an electrode provided in contact with at least one surface of the capacitive insulating film. Given the method, bismuth tantalate, so as to cover at least a portion of the capacitive element,
The method includes a step of forming a hydrogen barrier film made of at least one of bismuth niobate and bismuth tantalum niobate.

According to the method of manufacturing a semiconductor device of the present invention,
Since the capacitive element is covered with the hydrogen barrier film, it is possible to prevent the reducing gas from diffusing into the capacitive insulating film.
It is possible to reliably suppress the reduction reaction of the capacitive insulating film in the process performed in an atmosphere of a reducing gas such as hydrogen, which is indispensable in the MOS integration process, and thereby, the characteristic deterioration of the capacitive insulating film such as the ferroelectric property, especially, It is possible to prevent the deterioration of the leakage current characteristic. Moreover, since bismuth tantalate, bismuth niobate or bismuth tantalum niobate is used as the hydrogen barrier film material, the hydrogen barrier film can be easily formed without performing a special process. Therefore, a semiconductor memory device having excellent characteristics can be realized at low cost.

In the method of manufacturing a semiconductor device of the present invention,
The step of forming the hydrogen barrier film is preferably performed so that at least a part of the hydrogen barrier film is in direct contact with the capacitor insulating film.

In this way, it is not necessary to form an interlayer film between the capacitive insulating film and the hydrogen barrier film, so that the semiconductor memory device can be easily manufactured.

In the method of manufacturing a semiconductor device of the present invention,
The capacitive insulating film is preferably made of a ferroelectric material or a high dielectric material.

In this manner, when a bismuth layered ferroelectric material such as strontium bismuth tantalate is used as the material of the capacitive insulating film, the hydrogen barrier film material of the present invention contains the same constituent elements as the bismuth layered ferroelectric material. Since it has a crystal structure similar to that of the bismuth layered ferroelectric substance, characteristic deterioration of the capacitive insulating film due to diffusion of constituent elements of the hydrogen barrier film material does not occur. That is, the hydrogen barrier film material of the present invention is particularly effective in a semiconductor memory device using a bismuth layered ferroelectric substance as a capacitor insulating film material.

In the method of manufacturing a semiconductor device of the present invention,
The thickness of the hydrogen barrier film is preferably 5 nm or more and 200 nm or less.

By doing so, it is possible to surely prevent the reduction reaction of the capacitive insulating film due to the reducing gas such as hydrogen while miniaturizing the semiconductor memory device.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A semiconductor device and a method for manufacturing the same according to a first embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1A to 1C are sectional views showing each step of the method for manufacturing a semiconductor device according to the first embodiment.

First, as shown in FIG. 1A, an element isolation region 101 is formed on a surface portion of a semiconductor substrate 100 to partition a transistor region, and then a gate insulating film is formed on the semiconductor substrate 100 in the transistor region. A gate electrode 103 is formed via 102. Next, low-concentration impurities are ion-implanted into the semiconductor substrate 100 using the gate electrode 103 as a mask, and then a gate protective insulating film 104 is formed on the upper surface and side surfaces of the gate electrode 103, and then the gate electrode 103 and the gate protective insulating film are formed. Semiconductor substrate 1 using 104 as a mask
A high-concentration impurity is ion-implanted at 00. This allows
An impurity diffusion layer 105 having an LDD structure and serving as a source region or a drain region of a field effect transistor forming a memory cell is formed.

Next, as shown in FIG. 1A, after depositing a first interlayer insulating film 106 over the entire surface of the semiconductor substrate 100, the first interlayer insulating film 106 is subsequently deposited. A first hydrogen barrier film 107 made of at least one of bismuth tantalate, bismuth niobate and bismuth tantalum niobate and having a thickness of about 5 to 200 nm is formed over the entire surface.
For example, it is deposited by using a metal organic decomposition method (MOD method), a metal organic chemical vapor deposition method (MOCVD method), a sputtering method, or the like. After that, dry etching is sequentially performed on the first hydrogen barrier film 107 and the first interlayer insulating film 106 to form a contact hole reaching the impurity diffusion layer 105, and then a first contact hole is completely filled. 1 over the entire surface of the hydrogen barrier film 107,
For example, a conductive film such as a tungsten film or a polysilicon film is deposited by using the CVD method. After that, an upper portion of the first hydrogen barrier film 107 (that is, an outer portion of the contact hole) in the conductive film is removed by an etch back or a CMP method so that the source region or the drain region in the impurity diffusion layer 105 is removed. The contact plug 108 connected to either one is formed.

Next, a laminated film formed by depositing, for example, a titanium film, a titanium nitride film, an iridium oxide film and a platinum film in this order from the bottom over the entire surface of the first hydrogen barrier film 107 by using the sputtering method. Then, the laminated film is patterned by dry etching. This allows
As shown in FIG. 1B, a capacitor lower electrode 109 connected to the contact plug 108 is formed. Next, a ferroelectric film having a thickness of about 50 to 200 nm made of, for example, strontium bismuth tantalate having a bismuth layered perovskite structure is formed over the entire surface of the first hydrogen barrier film 107 including the lower capacitor electrode 109. MOD method, M
After depositing using OCVD or sputtering,
The ferroelectric film is patterned to form a capacitive insulating film 110. Incidentally, in the first embodiment, the capacitive insulating film 110
Are formed so as to extend over the plurality of capacitance lower electrodes 109 and extend to the outside of each capacitance lower electrode 109.

Next, a stacked layer formed by sequentially depositing, for example, a platinum film and a titanium film (or a titanium nitride film) on the entire surface of the first hydrogen barrier film 107 including the capacitor insulating film 110 from the bottom. After forming the film, the laminated film is patterned by dry etching. As a result, as shown in FIG. 1B, the capacitive lower electrode 1 is formed through the capacitive insulating film 110.
09, a capacitance upper electrode 111 is formed, and as a result, a capacitance element 112 including the capacitance lower electrode 109, the capacitance insulating film 110, and the capacitance upper electrode 111 is formed.

Next, as shown in FIG. 1C, bismuth tantalate, bismuth niobate, and tantalum niobate are entirely over the first hydrogen barrier film 107 including the upper capacitor electrode 111. Second hydrogen barrier film 113 made of at least one of bismuth and having a thickness of about 5 to 200 nm
Are deposited by using, for example, the MOD method, the MOCVD method, the sputtering method, or the like. As a result, the capacitive element 112 becomes the first hydrogen barrier film 107 and the second hydrogen barrier film 11.
A structure covered by 3 is formed. In particular,
The lower surface of the capacitive lower electrode 109 and the lower surface of the capacitive insulating film 110 are directly covered with the first hydrogen barrier film 107, and the upper surface and the side surface of the capacitive upper electrode 111 and the side surface of the capacitive insulating film 110 are the second hydrogen barrier film. Directly covered by 113. Note that after forming the second hydrogen barrier film 113, the first hydrogen barrier film 107 and the second hydrogen barrier film 113 may be patterned by dry etching, if necessary.

Next, as shown in FIG. 1C, a second interlayer insulating film 114 is deposited over the entire surface of the first interlayer insulating film 106 including the second hydrogen barrier film 113. To do.
Next, a titanium film, a titanium nitride film, an aluminum film, and a titanium nitride film are stacked in this order from the bottom over the entire surface of the second interlayer insulating film 114, or a titanium film and a nitride film are sequentially stacked from the bottom. Titanium film, tungsten film, titanium film,
After forming a laminated film formed by depositing a titanium nitride film, an aluminum film, and a titanium nitride film, the laminated film is patterned to form a wiring layer 115.

As described above, according to the first embodiment, since the capacitive element 112 is covered with the first hydrogen barrier film 107 and the second hydrogen barrier film 113, the reducing gas contains the capacitive insulating film 110. Can be prevented from spreading. Therefore, in the process performed in an atmosphere of a reducing gas such as hydrogen, which is indispensable in the CMOS integration process,
Since the reduction reaction of the capacitive insulating film 110 can be surely suppressed,
It is possible to prevent the characteristics of the capacitive insulating film 110, that is, the deterioration of the ferroelectric characteristics, particularly the deterioration of the leakage current characteristics. In addition, since bismuth tantalate, bismuth niobate, or bismuth tantalum niobate is used as the material of the first hydrogen barrier film 107 and the second hydrogen barrier film 113, the first hydrogen barrier film can be formed without any special process. The film 107 and the second hydrogen barrier film 113 can be easily formed. Therefore, a semiconductor memory device having excellent characteristics can be realized at low cost.

FIG. 2 shows the leakage current characteristics of the semiconductor memory device of this embodiment before and after the step (hereinafter sometimes referred to as hydrogen treatment) performed in an atmosphere of a reducing gas such as hydrogen. The results of measurement using the current-voltage measurement method are shown for each of the above. As shown in FIG. 2, in the semiconductor memory device of this embodiment, it is clear that the leakage current characteristics are not deteriorated even after the hydrogen treatment.

Further, according to the first embodiment, the side surface of the capacitive insulating film 110 is directly covered with the second hydrogen barrier film 113. Therefore, the capacitive insulating film 110 and the second
Since it is not necessary to form an interlayer film with the hydrogen barrier film 113, the semiconductor memory device can be easily manufactured.

In the first embodiment, strontium bismuth tantalate, which is one of the bismuth layered ferroelectrics, is used as the material of the capacitive insulating film 110, but other materials such as lead titanate are used instead. The same effect can be obtained by using the above ferroelectric material or a high dielectric material such as barium titanate. When a bismuth layered ferroelectric material such as strontium bismuth tantalate is used as the material of the capacitive insulating film 110, the hydrogen barrier film material of this embodiment has the same constituent element as the bismuth layered ferroelectric material. And has a crystal structure of the same genus as the bismuth layered ferroelectric substance, the characteristic deterioration of the capacitive insulating film 110 due to the diffusion of the constituent elements of the hydrogen barrier film material does not occur. That is, the hydrogen barrier film material of the present embodiment, specifically, bismuth tantalate, bismuth niobate, and bismuth tantalum niobate are particularly effective in a semiconductor memory device using a bismuth layered ferroelectric as a capacitor insulating film material. It is something to demonstrate.

In the first embodiment, the film thickness of each of the first hydrogen barrier film 107 and the second hydrogen barrier film 113 is preferably 5 nm or more and 200 nm or less. This makes it possible to reliably prevent the reduction reaction of the capacitive insulating film 110 due to the reducing gas such as hydrogen while miniaturizing the semiconductor memory device.

Further, in the first embodiment, the entire capacitive element 112 is covered with the first hydrogen barrier film 107 and the second hydrogen barrier film 113, but instead of this,
Needless to say, even when a part of the capacitor 112 is covered with only one of the first hydrogen barrier film 107 and the second hydrogen barrier film 113, a certain degree of effect can be obtained.

Further, although the semiconductor memory device having the one-transistor / one-capacitor type memory cell structure is targeted in the first embodiment, the present invention is not limited to this, and a semiconductor memory device having another memory cell structure, for example, A semiconductor memory device having a capacitor formed integrally with the transistor at the gate portion of the transistor, such as a one-transistor type memory cell, may be targeted.

(Second Embodiment) A semiconductor device and a method of manufacturing the same according to a second embodiment of the present invention will be described below with reference to the drawings.

FIGS. 3A to 3C are sectional views showing each step of the method for manufacturing a semiconductor device according to the second embodiment.

First, as shown in FIG. 3A, an element isolation region 101 is formed on the surface of a semiconductor substrate 100 to partition a transistor region, and then a gate insulating film is formed on the semiconductor substrate 100 in the transistor region. A gate electrode 103 is formed via 102. Next, low-concentration impurities are ion-implanted into the semiconductor substrate 100 using the gate electrode 103 as a mask, a gate protective insulating film 104 is formed on the upper surface and side surfaces of the gate electrode 103, and then the gate electrode 103 and the gate protective insulating film are formed. Semiconductor substrate 1 using 104 as a mask
A high-concentration impurity is ion-implanted at 00. This allows
An impurity diffusion layer 105 having an LDD structure and serving as a source region or a drain region of a field effect transistor forming a memory cell is formed.

Next, as shown in FIG. 3A, after depositing the first interlayer insulating film 106 over the entire surface of the semiconductor substrate 100, the first interlayer insulating film 106 is subsequently deposited. A first hydrogen barrier film 107 made of at least one of bismuth tantalate, bismuth niobate, and bismuth tantalum niobate and having a thickness of about 5 to 200 nm is formed over the entire surface.
For example, it is deposited by using the MOD method, the MOCVD method, the sputtering method, or the like. Then, the first hydrogen barrier film 107
Then, dry etching is sequentially performed on the first interlayer insulating film 106 to form a contact hole reaching the impurity diffusion layer 105, and then on the first hydrogen barrier film 107 so that the contact hole is completely filled. A conductive film such as a tungsten film or a polysilicon film is deposited on the entire surface by using the CVD method. After that, an upper portion of the first hydrogen barrier film 107 (that is, an outer portion of the contact hole) in the conductive film is removed by an etch back or a CMP method so that the source region or the drain region in the impurity diffusion layer 105 is removed. The contact plug 108 connected to either one is formed.

Next, a laminated film formed by depositing, for example, a titanium film, a titanium nitride film, an iridium oxide film, and a platinum film in this order from the bottom on the entire surface of the first hydrogen barrier film 107 by using the sputtering method. Then, the laminated film is patterned by dry etching. This allows
As shown in FIG. 3B, a capacitor lower electrode 109 connected to the contact plug 108 is formed. Next, a ferroelectric film having a thickness of about 50 to 200 nm made of, for example, strontium bismuth tantalate having a bismuth layered perovskite structure is formed over the entire surface of the first hydrogen barrier film 107 including the lower capacitor electrode 109. MOD method, M
After depositing using OCVD or sputtering,
The ferroelectric film is patterned to form a capacitive insulating film 110. Incidentally, in the second embodiment, the capacitive insulating film 110
Are formed so as to extend over the plurality of capacitance lower electrodes 109 and extend to the outside of each capacitance lower electrode 109.

Next, a stacked layer formed by sequentially depositing, for example, a platinum film and a titanium film (or a titanium nitride film) over the entire surface of the first hydrogen barrier film 107 including the capacitive insulating film 110. After forming the film, the laminated film is patterned by dry etching. As a result, as shown in FIG. 3B, the capacitive lower electrode 1 is formed through the capacitive insulating film 110.
09, a capacitance upper electrode 111 is formed, and as a result, a capacitance element 112 including the capacitance lower electrode 109, the capacitance insulating film 110, and the capacitance upper electrode 111 is formed.

Next, as shown in FIG. 3C, a capacitive element protective insulating film 116 is formed over the entire surface of the first hydrogen barrier film 107 including the capacitive upper electrode 111.
Then, a thickness of at least one of bismuth tantalate, bismuth niobate, and bismuth tantalum niobate is formed over the entire surface of the capacitor element protective insulating film 116 to a thickness of 5 to 5.
The second hydrogen barrier film 113 having a thickness of about 200 nm is deposited by using, for example, the MOD method, the MOCVD method, the sputtering method, or the like. Thus, a structure in which the capacitor 112 is covered with the first hydrogen barrier film 107 and the second hydrogen barrier film 113 is formed. Specifically, the lower surface of the capacitive lower electrode 109 and the lower surface of the capacitive insulating film 110 are directly covered with the first hydrogen barrier film 107, and the upper surface and side surface of the capacitive upper electrode 111 and the side surface of the capacitive insulating film 110 are capacitive. It is covered with the second hydrogen barrier film 113 via the element protection insulating film 116. Note that the first hydrogen barrier film 107 is formed after the second hydrogen barrier film 113 is formed.
And the second hydrogen barrier film 113 and the capacitor protection insulating film 11
6 and 6 may be patterned by dry etching if necessary.

Next, as shown in FIG. 3C, a second interlayer insulating film 114 is deposited over the entire surface of the first interlayer insulating film 106 including the second hydrogen barrier film 113. To do.
Next, a titanium film, a titanium nitride film, an aluminum film, and a titanium nitride film are stacked in this order from the bottom over the entire surface of the second interlayer insulating film 114, or a titanium film and a nitride film are sequentially stacked from the bottom. Titanium film, tungsten film, titanium film,
After forming a laminated film formed by depositing a titanium nitride film, an aluminum film, and a titanium nitride film, the laminated film is patterned to form a wiring layer 115.

As described above, according to the second embodiment, since the capacitive element 112 is covered with the first hydrogen barrier film 107 and the second hydrogen barrier film 113, the reducing gas contains the capacitive insulating film 110. Can be prevented from spreading. Therefore, in the process performed in an atmosphere of a reducing gas such as hydrogen, which is indispensable in the CMOS integration process,
Since the reduction reaction of the capacitive insulating film 110 can be surely suppressed,
It is possible to prevent the characteristics of the capacitive insulating film 110, that is, the deterioration of the ferroelectric characteristics, particularly the deterioration of the leakage current characteristics. In addition, since bismuth tantalate, bismuth niobate, or bismuth tantalum niobate is used as the material of the first hydrogen barrier film 107 and the second hydrogen barrier film 113, the first hydrogen barrier film can be formed without any special process. The film 107 and the second hydrogen barrier film 113 can be easily formed. Therefore, a semiconductor memory device having excellent characteristics can be realized at low cost.

Specifically, the leakage current characteristic of the semiconductor memory device of this embodiment was similar to the leakage current characteristic of the first embodiment shown in FIG. That is, also in the semiconductor memory device of this embodiment, the deterioration of the leak current characteristics did not occur after the hydrogen treatment.

Further, according to the second embodiment, the side surface of the capacitive insulating film 110 is covered with the second hydrogen barrier film 113 via the capacitive element protective insulating film 116. Therefore, the constituent elements of the hydrogen barrier film material can be suppressed from diffusing into the capacitive insulating film 110, whereby the capacitive insulating film 11 can be suppressed.
The characteristic deterioration of 0 can be prevented more reliably.

In the second embodiment, strontium bismuth tantalate, which is one of the bismuth layered ferroelectrics, is used as the material of the capacitive insulating film 110, but other materials such as lead titanate are used instead. The same effect can be obtained by using the above ferroelectric material or a high dielectric material such as barium titanate. When a bismuth layered ferroelectric material such as strontium bismuth tantalate is used as the material of the capacitive insulating film 110, the hydrogen barrier film material of this embodiment has the same constituent element as the bismuth layered ferroelectric material. And has a crystal structure of the same genus as the bismuth layered ferroelectric substance, the characteristic deterioration of the capacitive insulating film 110 due to the diffusion of the constituent elements of the hydrogen barrier film material does not occur. That is, the hydrogen barrier film material of the present embodiment, specifically, bismuth tantalate, bismuth niobate, and bismuth tantalum niobate are particularly effective in a semiconductor memory device using a bismuth layered ferroelectric as a capacitor insulating film material. It is something to demonstrate.

In addition, in the second embodiment, the film thickness of each of the first hydrogen barrier film 107 and the second hydrogen barrier film 113 is preferably 5 nm or more and 200 nm or less. This makes it possible to reliably prevent the reduction reaction of the capacitive insulating film 110 due to the reducing gas such as hydrogen while miniaturizing the semiconductor memory device.

Further, in the second embodiment, the entire capacitive element 112 is covered with the first hydrogen barrier film 107 and the second hydrogen barrier film 113, but instead of this,
Needless to say, even when a part of the capacitor 112 is covered with only one of the first hydrogen barrier film 107 and the second hydrogen barrier film 113, a certain degree of effect can be obtained.

In the second embodiment, the semiconductor memory device having the one-transistor / one-capacitor memory cell structure is targeted, but the present invention is not limited to this, and a semiconductor memory device having another memory cell structure, for example, A semiconductor memory device having a capacitor formed integrally with the transistor at the gate portion of the transistor, such as a one-transistor type memory cell, may be targeted.

[0057]

According to the present invention, the reduction reaction of the capacitive insulating film due to hydrogen or the like can be surely suppressed in the process in the reducing gas atmosphere in the manufacturing process of the semiconductor memory device, so that the ferroelectric characteristics, etc. It is possible to prevent the deterioration of the characteristics of the capacitive insulating film, especially the deterioration of the leakage current characteristics. Moreover, since the hydrogen barrier film can be easily formed without performing a special process, a semiconductor memory device having excellent characteristics can be realized at low cost.

[Brief description of drawings]

1A to 1C are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a leakage current characteristic of the semiconductor device according to the first embodiment of the present invention, measured by a current-voltage measuring method before and after a process performed in a reducing gas atmosphere. It is a figure which shows the result.

3A to 3C are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

100 semiconductor substrate 101 element isolation region 102 gate insulating film 103 gate electrode 104 Gate protection insulation film 105 Impurity diffusion layer 106 first interlayer insulating film 107 first hydrogen barrier film 108 Contact plug 109 capacitance lower electrode 110 capacitance insulating film 111 Capacitor upper electrode 112 Capacitive element 113 Second hydrogen barrier film 114 Second interlayer insulating film 115 wiring layer 116 Capacitor protection insulation film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 29/788 H01L 27/10 651 29/792 F term (reference) 5F058 BA20 BC03 BD01 BD05 BF06 BF12 BF80 BJ10 5F083 AD10 AD21 AD49 FR02 FR05 GA25 GA27 JA14 JA17 JA38 JA39 JA40 JA43 JA60 MA06 MA17 PR40 5F101 BA62 BB02 BD02

Claims (8)

[Claims] 1. A semiconductor device comprising a capacitive element including a capacitive insulating film and an electrode provided in contact with at least one surface of the capacitive insulating film, wherein at least a part of the capacitive element is provided. A semiconductor device covered with a hydrogen barrier film comprising at least one of bismuth tantalate, bismuth niobate, and bismuth tantalum niobate. 2. The at least part of the hydrogen barrier film is in direct contact with the capacitive insulating film.
The semiconductor device according to. 3. The semiconductor device according to claim 1, wherein the capacitance insulating film is made of a ferroelectric material or a high dielectric material. 4. The semiconductor device according to claim 1, wherein the hydrogen barrier film has a film thickness of 5 nm or more and 200 nm or less. 5. A method of manufacturing a semiconductor device, comprising a capacitive element including a capacitive insulating film and an electrode provided so as to contact at least one surface of the capacitive insulating film, the method comprising: A method of manufacturing a semiconductor device, comprising the step of forming a hydrogen barrier film made of at least one of bismuth tantalate, bismuth niobate, and bismuth tantalum niobate so as to cover at least a part. 6. The step of forming the hydrogen barrier film is performed so that at least a part of the hydrogen barrier film is in direct contact with the capacitance insulating film.
A method of manufacturing a semiconductor device according to item 1. 7. The method of manufacturing a semiconductor device according to claim 5, wherein the capacitance insulating film is made of a ferroelectric material or a high dielectric material. 8. The method of manufacturing a semiconductor device according to claim 5, wherein the film thickness of the hydrogen barrier film is 5 nm or more and 200 nm or less.