JP2003282827A - Ferroelectric thin film memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a ferroelectric capacitor is not protected sufficiently from hydrogen entering from the side wall section of the capacitor, because a conductive hydrogen barrier film can only be formed immediately above the upper electrode of the capacitor though the film has excellent hydrogen barrier ability. <P>SOLUTION: An insulating first hydrogen barrier film is provided immediately above the ferroelectric capacitor and a conductive hydrogen barrier film is formed on the barrier film at a position where the film does not overlap a contact hole. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A non-volatile memory device (ferroelectric memory device) utilizing spontaneous polarization peculiar to a ferroelectric substance is
Due to its features such as high-speed writing / reading and low-voltage operation, it has the possibility of replacing not only conventional non-volatile memory but also most memories such as SRAM (static RAM) and DRAM. Ferroelectric materials include lead zirconate titanate (PZT) and other perovskite oxides and S.
Bismuth layered compounds such as rBi2Ta2O9 are receiving attention.

In general, when the above oxide material is used as a capacitor insulating layer, it is covered with an interlayer insulating film such as SiO 2 for the purpose of electrical insulation between memory elements after the upper electrode is formed. As the film forming method, C having excellent step coverage is used.
The VD (Chemical Vapor Deposition) method is generally used. However, when such a film forming method is used, hydrogen is generated as a reaction by-product. In particular, when activated hydrogen permeates SiO 2 and the upper electrode and reaches the ferroelectric thin film, the reducing action thereof causes the ferroelectric characteristics to be significantly deteriorated. Also, as a switching element
Since the characteristics of the MOS transistor deteriorate due to lattice defects in the silicon single crystal generated in the device manufacturing process, it is necessary to perform heat treatment in hydrogen-mixed nitrogen gas at the final stage. However, the hydrogen concentration in this step is higher than when the interlayer insulating film is formed, and the damage to the ferroelectric thin film becomes more serious.

In order to overcome the reduction degradation of the ferroelectric capacitor due to hydrogen, a method of forming a ferroelectric thin film capacitor and then forming a protective film to cover the ferroelectric thin film capacitor to prevent the invasion of hydrogen is tried. Has been. This protective film is generally called a hydrogen barrier film.

[0004]

2. Description of the Related Art Oxide materials have been vigorously studied as promising candidates for hydrogen barrier films. IrOx is a typical example, and reduction resistance is investigated. For example, J. Electr
ochem.Soc.136,1740 (1989) and Surface Science 144,451
In (1984), between IrOx films produced by different film formation methods,
Resistance to reducing atmosphere has been investigated. According to these reports, the easiness of reduction varies greatly depending on the difference in crystallinity, and IrOx with better crystallinity has better hydrogen resistance. As an example, Ir obtained by oxidizing the surface of single crystal Ir
It is published that the Ox thin film is not reduced even in a high temperature hydrogen atmosphere near 700 ° C. When such an IrOx thin film having good crystallinity is formed on the capacitor, IrOx itself is less likely to be reduced even in a hydrogen atmosphere, and a sufficient hydrogen barrier effect can be expected. However, since IrOx has conductivity, it needs to be formed only on the upper electrode of the capacitor.

[0005]

However, as described above, even if the hydrogen barrier film is formed only on the upper electrode, the barrier effect cannot be expected with respect to hydrogen invasion from the side wall of the capacitor. Materials with excellent hydrogen barrier performance,
There is a problem that the conductive material cannot be directly formed on the side wall of the capacitor. This is a problem common to not only iridium oxides but also conductive hydrogen barrier films. As other conductive hydrogen barrier films, titanium and titanium nitride have been introduced.

According to the present invention, a conductive hydrogen barrier film, which has been formed only directly on the upper electrode of a ferroelectric capacitor despite having an excellent hydrogen barrier performance, has a hydrogen barrier film on the side wall of the capacitor. The purpose is to prevent the reduction deterioration of the ferroelectric due to the process by arranging it at a position where it can be protected from heat.

[0007]

A ferroelectric thin film memory according to claim 1 is a ferroelectric thin film formed by sequentially laminating a lower electrode, an oxide ferroelectric thin film and an upper electrode on a semiconductor substrate. A capacitor, a protective film layer covering the surface of the capacitor, an opening provided on the upper electrode of the protective film layer, and a wiring layer formed on the protective film layer and in the opening. In the ferroelectric thin film memory described above, the protective film layer is composed of a first hydrogen barrier film and a second hydrogen barrier film and an insulating film formed on the first hydrogen barrier film. According to the above configuration, since it is possible to insulate the second hydrogen barrier film and the ferroelectric capacitor by the first hydrogen barrier film, use a conductive material as the second hydrogen barrier film. It has the effect that

According to another aspect of the ferroelectric thin film memory of the present invention,
The area of the opening provided in the second hydrogen barrier film is larger than the area S1 of the opening provided in the first hydrogen barrier film.
S2 is large, and the wiring layer is not in contact with the second hydrogen barrier film. According to the above configuration, even in the structure in which the wiring layer is deposited on the upper electrode of the capacitor, the second hydrogen barrier film ensures insulation with the wiring layer.
It has an effect that a conductive material can be used as the second hydrogen barrier film.

According to a third aspect of the ferroelectric thin film memory,
The area S2 of the opening provided in the second hydrogen barrier film is smaller than the area of the upper electrode of the ferroelectric thin film capacitor. According to the above configuration, the area where the second hydrogen barrier film covers the capacitor becomes larger,
The effect is that more reliable hydrogen barrier performance can be expected.

According to another aspect of the ferroelectric thin film memory of the present invention,
The first hydrogen barrier film is an oxide containing any one of aluminum, magnesium and titanium. According to the above configuration, the first hydrogen barrier film has an effect of exhibiting excellent hydrogen barrier performance.

A method of manufacturing a ferroelectric thin film memory according to a fifth aspect is characterized in that the second hydrogen barrier film is an oxide of iridium. According to the above configuration, the second hydrogen barrier film exhibits an extremely excellent hydrogen barrier performance, so that the reduction deterioration of the ferroelectric thin film can be prevented.

A method of manufacturing a ferroelectric thin film memory according to a sixth aspect is characterized in that the second hydrogen barrier film is titanium. According to the above configuration, the second hydrogen barrier film exhibits an extremely excellent hydrogen barrier performance, so that the reduction deterioration of the ferroelectric thin film can be prevented.

A method of manufacturing a ferroelectric thin film memory according to a seventh aspect is characterized in that the second hydrogen barrier film is a nitride of titanium. According to the above configuration, the second hydrogen barrier film exhibits an extremely excellent hydrogen barrier performance, so that the reduction deterioration of the ferroelectric thin film can be prevented.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, a process of forming a ferroelectric thin film element will be schematically described with reference to the drawings. Board 101
A drive circuit portion (102) of the ferroelectric memory device is formed in advance on the top. Next, after forming a film of platinum or iridium on the entire surface by using a sputtering method or the like, this was patterned into a desired shape by etching. Here, the lower electrodes 103 arranged in parallel with each other were formed. An organic solution containing strontium, bismuth, and tantalum was applied onto this by a spin coating method, and dried to obtain a precursor film. The steps of spin coating and drying were repeated until the precursor film reached the desired film thickness. Finally
A crystalline thin film SrBi2Ta2O9 (hereinafter referred to as SBT) was obtained by performing oxygen annealing treatment at 700 ° C. for 1 hour. In addition, as a film forming method of SBT, a MOCVD method, a sputtering method, or the like can also be used. The SBT was removed by etching except the region covering the lower electrode 103 (104). Subsequently, platinum or iridium was deposited by the sputtering method. This platinum or iridium is patterned by etching, and the lower electrode 103
The upper electrode 105 arranged in the direction orthogonal to is formed (FIG. 3). A region where the lower electrode 103 and the upper electrode 105 intersect is arranged in a matrix as shown in FIG. 3, and this intersecting region corresponds to a ferroelectric capacitor.

Al2O3 was deposited as the first hydrogen barrier film 106 on the ferroelectric capacitors arranged in a matrix as described above. As shown in FIG. 4, this Al2O3 was removed from the drive circuit portion by etching. An iridium oxide film was further formed thereon as a second hydrogen barrier film 107. Like the first hydrogen barrier film, the second hydrogen barrier film was also removed by etching from the periphery of the ferroelectric capacitor region including the drive circuit section (FIG. 5). TEOS (Tetraethylorthosilicate) as the interlayer insulating film 108
A film is formed (FIG. 6), and the lower electrode 103 and the upper electrode 10 are formed.
A contact hole 109 was formed on the surface of the metal layer 5 (FIG. 7). Aluminum was deposited here, and wiring (110) between the ferroelectric capacitor and the drive circuit portion was performed (FIG. 8). Figure 8
9 is a sectional view taken along the line AB in FIG. 9 (Sample 1). On the other hand, for comparison, an element was manufactured without forming a second hydrogen barrier film as a hydrogen barrier film (Sample 2).

It was decided to compare the characteristics of the memory devices obtained by the respective manufacturing methods. Here, we decided to focus on the ferroelectric characteristics of the ferroelectric thin film capacitor. When an appropriate AC voltage is applied between the upper and lower electrodes, a certain amount of electric charge is induced in the upper and lower electrodes depending on the magnitude and direction of the applied voltage. To monitor this state, plotting the applied voltage on the horizontal axis and the charge amount on the vertical axis, a hysteresis loop resulting from the inversion of the polarization axis is obtained. The results are shown in FIGS. 21 to 23.

FIG. 24 shows the hysteresis loop immediately after forming the SBT capacitor. This is as shown in FIG.
Is a hysteresis loop obtained by selecting one lower electrode 103 and one upper electrode 105 and applying a voltage between these electrodes. Similarly, FIGS. 22 and 23 show the hysteresis loops obtained in Sample 1 and Sample 2, respectively. As is clear from the figure, in Sample 1, the ferroelectric characteristics are less deteriorated as compared with immediately after the formation of the SBT capacitor. On the other hand, in Sample 2, it can be seen that the hysteresis loop is thin and the characteristics are significantly deteriorated. It was clarified that a large difference in characteristics appears after the processing process due to the structural difference between the two samples. That is, it is considered that the degree of process deterioration greatly differs due to the presence or absence of the iridium oxide film formed as the second hydrogen barrier film on the ferroelectric thin film capacitor.

In the method of manufacturing the ferroelectric memory described in this embodiment, hydrogen generated in the TEOS film forming step or the passivation film forming step is a major factor causing deterioration of the characteristics of the capacitor. In Sample 1, the hydrogen barrier film formed on the ferroelectric thin film capacitor was Al2O3.
There is only a single layer. For this reason, it is considered that hydrogen was not completely blocked and partially penetrated into the capacitor. Due to the reduction of the SBT thin film, the original ferroelectric property of the film was greatly impaired, and the hysteresis property was significantly deteriorated.
On the other hand, in Sample 2, before forming the TEOS film, an Al2O3 thin film and an iridium oxide film as a second hydrogen barrier film are formed on the ferroelectric thin film capacitor. It is considered that the double barrier structure of the Al2O3 thin film and the iridium oxide film completely blocked the hydrogen generated in the TEOS film formation process or the passivation film formation process, and prevented the invasion of hydrogen into the SBT thin film.

In the device structure of the present invention, the most excellent hydrogen barrier film can be formed on the side wall of the capacitor regardless of whether or not it has conductivity. In the element structure,
Since a large degree of freedom has been created in the formation position of the hydrogen barrier film, it has become possible to reliably protect the ferroelectric substance from reduction degradation due to the process.

(Embodiment 2) First, the stacking process of the ferroelectric thin film element will be schematically described with reference to the drawings. A MOS transistor serving as a switching transistor 202 and an element isolation region 203 were formed on a single crystal silicon substrate 201, and further a boron phosphorus-doped silicon oxide film (BPSG) 204 was formed as an interlayer insulating film.

Next, after forming a resist pattern for forming a contact hole by a lithography process, the contact hole was opened by a dry etching method. After depositing the polysilicon film, phosphorus was doped. Subsequently, the polysilicon film was polished by chemical mechanical polishing to form a polysilicon plug 205 in the contact hole. Next, a titanium nitride film was formed as a barrier metal layer 206 between the lower electrode and the polysilicon plug 205 by a sputtering method. The obtained substrate structure is shown in FIG. A platinum 207 film was formed thereon as a lower electrode. This platinum 207
A precursor film was obtained by applying an organic solution containing strontium, bismuth, and tantalum onto the above by spin coating and drying. The steps of spin coating and drying were repeated until the precursor film reached the desired film thickness.
Finally, by performing oxygen annealing treatment at 700 ° C for 1 hour, SrBi2Ta2O9 (hereinafter referred to as SBT), which is a crystalline thin film, 20
Got 8. Further, platinum 209 was deposited as an upper electrode by the sputtering method (FIG. 11).

Next, the lower electrode, the SBT thin film and the upper electrode were patterned to a desired size to form an SBT thin film capacitor (FIG. 12). After annealing is again performed in an oxygen atmosphere, an Al2O3 thin film 210 is formed as a first hydrogen barrier film so as to cover the capacitor surface.
Was deposited by a sputtering method (FIG. 13). Further, an iridium oxide film 211 was laminated as a second hydrogen barrier film (FIG. 14). Then, only the iridium oxide film was removed from the capacitor peripheral region and a part on the upper electrode (FIG. 15). On top of this, TEOS (Tetraethylort
A hosilicate) film 212 was deposited (FIG. 16). After providing an opening for obtaining electrical contact with the upper electrode of the ferroelectric thin film capacitor (FIG. 17), a wiring material 213 was deposited (FIG. 18). A wiring layer was formed by etching this (FIG. 19). Finally, passivation was formed to secure contact with peripheral circuits (Fig. 2
0). The obtained device structure is called a stack type and is one of memory cell structures aiming at high integration (Sample 3). On the other hand, for comparison, a memory cell was prepared by forming only an Al2O3 thin film as a hydrogen barrier film of an SBT thin film capacitor (Sample 4).

It was decided to compare the characteristics of the memory devices obtained by the respective manufacturing methods. Here, we decided to focus on the ferroelectric characteristics of the ferroelectric thin film capacitor. When an appropriate AC voltage is applied between the upper and lower electrodes, a certain amount of electric charge is induced in the upper and lower electrodes depending on the magnitude and direction of the applied voltage. To monitor this state, plotting the applied voltage on the horizontal axis and the charge amount on the vertical axis, a hysteresis loop resulting from the inversion of the polarization axis is obtained. The results are shown in FIGS. 24 to 26.

FIG. 24 shows the hysteresis loop immediately after forming the SBT capacitor. 25 and 26 show the hysteresis loops obtained in Sample 3 and Sample 4, respectively. As is clear from the figure, in Sample 3, the ferroelectric characteristics are less deteriorated than immediately after the SBT capacitor is formed. On the other hand, in Sample 4, it can be seen that the hysteresis loop is thin and the characteristics are significantly deteriorated. It was clarified that a large difference in characteristics appears after the processing process due to the structural difference between the two samples. That is, it is considered that the degree of process deterioration greatly differs due to the presence or absence of the iridium oxide film formed as the second hydrogen barrier film on the ferroelectric thin film capacitor.

In the method of manufacturing the ferroelectric memory described in this embodiment, hydrogen generated in the TEOS film forming process or the passivation film forming process is a major factor causing deterioration of the characteristics of the capacitor. In Sample 4, the hydrogen barrier film formed on the ferroelectric thin film capacitor was Al2O3.
There is only a single layer. For this reason, it is considered that hydrogen was not completely blocked and partially penetrated into the capacitor. Due to the reduction of the SBT thin film, the original ferroelectric property of the film was greatly impaired, and the hysteresis property was significantly deteriorated.
On the other hand, in Sample 3, before the TEOS film was formed, an Al2O3 thin film and an iridium oxide film as a second hydrogen barrier film were formed on the ferroelectric thin film capacitor. It is considered that the double barrier structure of the Al2O3 thin film and the iridium oxide film completely blocked the hydrogen generated in the TEOS film formation process or the passivation film formation process, and prevented the invasion of hydrogen into the SBT thin film.

In the device structure of the present invention, the most excellent hydrogen barrier film can be formed on the side wall of the capacitor regardless of the presence or absence of conductivity. In the element structure,
Since a large degree of freedom has been created in the formation position of the hydrogen barrier film, it has become possible to reliably protect the ferroelectric substance from reduction degradation due to the process.

(Example 3) Ti was formed as the second hydrogen barrier film 107 in FIG. 5 to prepare a sample (Sample 5). This sample is structurally the same as Sample 1 in Example 1,
The only difference is that the second hydrogen barrier film was changed from iridium oxide film to Ti. When the characteristics of the ferroelectric capacitor were examined, a hysteresis loop as shown in FIG. 27 was obtained. As is clear from comparison with FIG. 22, it can be seen that the ferroelectric characteristics equivalent to those of Sample 1 are exhibited. It was confirmed that the use of Ti as the second hydrogen barrier film is extremely effective in protecting the ferroelectric capacitor from reduction deterioration due to hydrogen caused by the process.

Example 4 TiN was formed as the second hydrogen barrier film 107 in FIG. 5 to prepare a sample (sample 6). This sample is structurally the same as Sample 1 in Example 1,
The only difference is that the second hydrogen barrier film was changed from iridium oxide film to TiN. When the characteristics of the ferroelectric capacitor were examined, a hysteresis loop as shown in FIG. 28 was obtained. As is clear from comparison with FIG. 22, sample 1
It can be seen that it exhibits ferroelectric characteristics equivalent to. It was confirmed that the use of TiN as the second hydrogen barrier film is extremely effective in protecting the ferroelectric capacitor from reduction degradation due to hydrogen caused by the process.

(Example 5) Ti was formed as the second hydrogen barrier film 211 in FIG. 15 to prepare a sample (Sample 7). This sample is structurally the same as Sample 3 in Example 2,
The only difference is that the second hydrogen barrier film was changed from iridium oxide film to Ti. When the characteristics of the ferroelectric capacitor were examined, a hysteresis loop as shown in FIG. 29 was obtained. As is clear from comparison with FIG. 25, it can be seen that the ferroelectric characteristics equivalent to those of Sample 3 are exhibited. It was confirmed that the use of Ti as the second hydrogen barrier film is extremely effective in protecting the ferroelectric capacitor from reduction deterioration due to hydrogen caused by the process.

Example 6 TiN was formed as the second hydrogen barrier film 211 in FIG. 15 to prepare a sample (Sample 8). This sample differs from Sample 3 in Example 2 in structure only in that the second hydrogen barrier film was changed from an iridium oxide film to TiN. When the characteristics of the ferroelectric capacitor were examined, a hysteresis loop as shown in FIG. 30 was obtained. As is clear from comparison with FIG. 25, it can be seen that the ferroelectric characteristics equivalent to those of Sample 3 are exhibited. It was confirmed that the use of TiN as the second hydrogen barrier film is extremely effective in protecting the ferroelectric capacitor from reduction degradation due to hydrogen caused by the process.

[0032]

As described above, in the structure of the ferroelectric thin film memory of the present invention, even if it is a conductive thin film, if it is a material exhibiting an excellent hydrogen barrier performance, it is surrounded by the ferroelectric capacitor. It is possible to place them in a space without gaps. Therefore, it is possible to prevent the reduction deterioration of the ferroelectric substance from hydrogen generated due to the process.

[Brief description of drawings]

FIG. 1 is a plan view showing the structure of a sample at the time when the lower electrode patterning process is completed in the sample 1 manufacturing process.

FIG. 2 is a plan view showing the structure of a sample at the time when a ferroelectric thin film is formed in the manufacturing process of sample 1.

FIG. 3 is a plan view showing the structure of a sample at the time when the formation of the upper electrode is completed in the manufacturing process of sample 1.

FIG. 4 is a plan view showing the sample structure at the time when the first hydrogen barrier film is formed in the manufacturing process of sample 1.

FIG. 5 is a plan view showing the sample structure at the time when the second hydrogen barrier film is formed in the manufacturing process of sample 1.

FIG. 6 is a plan view showing the structure of a sample at the time when an interlayer insulating film is formed in the manufacturing process of sample 1.

FIG. 7 is a plan view showing a sample structure at the time when a contact hole is formed in the manufacturing process of sample 1.

FIG. 8 is a plan view showing a sample structure at the time when a wiring layer is formed in the manufacturing process of sample 1.

9 is a diagram showing a cross section of Sample 1 taken along the line AB in FIG. 8. FIG.

FIG. 10 is a diagram showing a cross section of a start substrate in a manufacturing process of Sample 3.

FIG. 11 is a cross-sectional view showing the structure of the sample at the time when the upper electrode is formed in the process of manufacturing sample 3.

FIG. 12 is a cross-sectional view showing the structure of a sample at the time when a ferroelectric thin film capacitor is formed in the manufacturing process of sample 3.

FIG. 13 is a cross-sectional view showing a sample structure at the time when a first hydrogen barrier film is formed in a manufacturing process of Sample 3.

FIG. 14 is a cross-sectional view showing the sample structure at the time when the second hydrogen barrier film is formed in the manufacturing process of sample 3.

FIG. 15 is a cross-sectional view showing the sample structure at the time when the second hydrogen barrier film is patterned in the sample 3 manufacturing process.

16 is a cross-sectional view showing the structure of a sample at the time when an interlayer insulating film is formed in the manufacturing process of Sample 3. FIG.

FIG. 17 is a cross-sectional view showing the structure of a sample at the time when a contact hole is formed in the manufacturing process of sample 3.

FIG. 18 is a cross-sectional view showing a sample structure at the time when a wiring material is formed into a film in a manufacturing process of sample 3.

FIG. 19 is a cross-sectional view showing the structure of a sample at the time when a wiring layer is formed in the manufacturing process of sample 3.

FIG. 20 is a cross-sectional view showing a sample structure at the time when a passivation film is formed in a manufacturing process of Sample 3.

FIG. 21 shows an initial hysteresis loop measured with the ferroelectric thin film capacitor of Sample 3.

FIG. 22 is a hysteresis loop after formation of passivation measured in a ferroelectric thin film capacitor of Sample 3.

FIG. 23 is a hysteresis loop after formation of passivation measured in a ferroelectric thin film capacitor of Sample 4.

FIG. 24 shows an initial hysteresis loop measured with the ferroelectric thin film capacitor of Sample 1.

25 is a hysteresis loop after passivation formation measured in the ferroelectric thin film capacitor of Sample 1. FIG.

FIG. 26 is a hysteresis loop after passivation formation measured in the ferroelectric thin film capacitor of Sample 2.

FIG. 27 is a hysteresis loop after forming a wiring layer, which is measured by the ferroelectric thin film capacitor of Sample 5.

FIG. 28 is a hysteresis loop after forming a wiring layer, which is measured in the ferroelectric thin film capacitor of Sample 6.

FIG. 29 is a hysteresis loop after formation of passivation measured in the ferroelectric thin film capacitor of Sample 7.

FIG. 30 shows a hysteresis loop after formation of passivation measured in the ferroelectric thin film capacitor of Sample 8.

[Explanation of symbols]

101. Substrate 102. Drive circuit 103. Lower electrode 104. SBT thin film 105. Upper electrode 106. First hydrogen barrier film 107. The second hydrogen barrier film, which is an iridium oxide film in Example 1. In Example 3, Ti. Example 4
In TiN. 108. Interlayer insulating film 109. Contact hole 110. Wiring layer 201. Substrate 202. Switching transistor 203. Element isolation region 204. Interlayer insulating film 205. Polysilicon plug 206. Barrier metal layer 207. Lower electrode 208. SBT thin film 209. Upper electrode 210. First hydrogen barrier film 211. Second hydrogen barrier film 212. Interlayer insulating film 213. Wiring layer 214. Passivation film

Claims (7)

[Claims] 1. A ferroelectric thin film capacitor formed by sequentially stacking a lower electrode, an oxide ferroelectric thin film and an upper electrode on a semiconductor substrate, a protective film layer coated on the surface of the capacitor, and a protective film. A ferroelectric thin film memory comprising an opening provided on the upper electrode of a film layer, and a wiring layer formed on the protective film layer and in the opening,
A ferroelectric thin film memory, wherein the protective film layer comprises a first hydrogen barrier film, a second hydrogen barrier film and an insulating film formed on the first hydrogen barrier film. 2. The area S2 of the opening provided in the second hydrogen barrier film is larger than the area S1 of the opening provided in the first hydrogen barrier film, and the wiring layer has a second area S2. A ferroelectric thin film memory characterized by not contacting a hydrogen barrier film. 3. The ferroelectric thin film memory according to claim 2, wherein an area S2 of an opening provided in the second hydrogen barrier film is smaller than an area of an upper electrode of the ferroelectric thin film capacitor. . 4. The ferroelectric thin film memory according to claim 1, wherein the first hydrogen barrier film is an oxide containing any of aluminum, magnesium and titanium. 5. The ferroelectric thin film memory according to claim 1, wherein the second hydrogen barrier film is an oxide of iridium. 6. The ferroelectric thin film memory according to claim 1, wherein the second hydrogen barrier film is titanium. 7. The ferroelectric thin film memory according to claim 1, wherein the second hydrogen barrier film is a nitride of titanium.