JPH0964309A - Semiconductor memory device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor memory device and its manufacturing method wherein the film formation temperature and time can be reduced, and fine working and highly precise working are enabled. SOLUTION: In a first heat treatment stage, a first insulator thin film 6 covering a semiconductor substrate 1 and the surface of conductive material inside a contact hole 8 are flattened, precursor solution applied to the surface of a lower electrode 10 formed on the surface is heated, solvent only is eliminated, the precursor is dried, and a dielectric thin film 11 is formed. In this stage, the temperature is quickly raised, the heating temperature is kept nearly equal to the crystallization temperature of the dielectric thin film, organic matter is thermally decomposed and eliminated, and the heating is stopped when fine crystal nuclei are grown. The dielectric thin film 11 is covered with a second insulator thin film 13. A contact hole is made, in which an upper electrode 12 is formed. After the upper electrode is worked in a specific size, characteristics of a dielectric capacitor is stabilized by heating in a second heat treatment stage. The dielectric thin film is crystallized by heating for a sufficient period at a temperature higher than or equal to the crystallization temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric thin film element and a dielectric thin film element used for a semiconductor memory element, a ferroelectric memory element and the like, and a manufacturing method of those elements.

[0002]

2. Description of the Related Art Ferroelectric materials have many functions such as spontaneous polarization, high dielectric constant, electro-optical effect, piezoelectric effect and pyroelectric effect, and are therefore widely applied to device development. For example, its pyroelectricity is used for an infrared linear array sensor, its piezoelectricity is used for an ultrasonic sensor, its electro-optical effect is used for a waveguide type optical modulator, and its high dielectric constant is used. To the capacitors for DRAM and MMIC,
It is used in various fields.

Among them, a ferroelectric non-volatile memory (FRAM) which operates at a high density and at a high speed in combination with a semiconductor memory technology with the recent progress of the thin film forming technology.
Is actively being developed. Non-volatile memory using ferroelectric thin film is not only a replacement for conventional non-volatile memory but also SRAM and DR because of its characteristics such as high speed write / read, low voltage operation, and high write / read endurance.
As a memory that can be replaced with an AM, research and development are being actively conducted toward practical use. For such device development, the remanent polarization (Pr) is large and the coercive electric field (Er) is large.
A material having a small c), a low leakage current, and a large resistance to repeated polarization inversion is required. Furthermore, in order to reduce the operating voltage and adapt to the semiconductor microfabrication process, the film thickness is 2
It is desirable to realize the above characteristics with a thin film of 00 nm or less.

As a ferroelectric or high-dielectric material used for these purposes, an oxide material having a perovskite structure represented by PZT (lead zirconate titanate, Pb (Ti, Zr) O ₃ ) is the mainstream. there were. However, PZ
A material containing lead as its constituent element such as T has a high vapor pressure of lead or an oxide thereof, so that the lead component evaporates during film formation and causes defects in the film, or in the worst case, pinholes. To form. As a result, there are drawbacks such as an increase in leak current and a fatigue phenomenon in which the magnitude of spontaneous polarization decreases with repeated polarization inversion. Regarding the fatigue phenomenon, it is necessary to guarantee that there will be no change in the characteristics even after 10 ¹⁵ times of polarization reversal, considering the replacement of the DRAM with the ferroelectric non-volatile memory. Was desired.

On the other hand, in recent years, research and development of bismuth layer structure compound materials have been conducted. The bismuth layered structure compound material was discovered by Smolenskii et al. In 1959 (GA Smolenskii,
V. A. Isupov and A. I. Agranov
skaya, Soviet Phys. SolidSt
ate, 1, 149 (1959)), and then Subb
Detailed examination was done by arao. (EC Su
bbarao, J .; Phys. Chem. Solid
s, 23, 665 (1962)) Recently, Carlos
A. Paz de Araujo et al. Found that this bismuth layer structure compound thin film is suitable for application to ferroelectric and high-dielectric integrated circuits, and in particular, changes in the characteristics were observed even after 10 ¹² or more polarization inversions. It reports the excellent fatigue properties of not having. (International A
application No. PCT / US92 / 10
542) However, the film forming method in this case is MOD (Me
talOrganicDecomposition)
The annealing temperature for crystallization of the thin film is 800
The temperature is extremely high at ℃ and the annealing time is longer than 1 hour.
When it is formed on an integrated circuit, there is a problem of damage such as contact failure and characteristic deterioration due to mutual diffusion and oxidation between the via hole material and the electrode, which is an obstacle to high integration.

The method of manufacturing the ferroelectric thin film includes physical methods such as vacuum deposition method, sputtering method, laser ablation method and the like, and organic metal compounds are used as a starting material to thermally decompose and oxidize them to form an oxide ferroelectric material. To obtain sol-gel method or MOD method, MOCVD (Metal Organi)
c Chemical Vapor Depositi
on) method or the like is used.

Among the above film forming methods, the sol-gel method or MO
The method D uses a homogeneous mixed raw material solution at the atomic level, the composition control is easy and the reproducibility is excellent, and a large area film can be formed at normal pressure without the need for a special vacuum device.
It is widely used because of its advantages such as industrially low cost.

In particular, the MOD method is also used as a film forming method of the above-mentioned bismuth layered structure compound thin film, and in the film forming process of the conventional MOD method, the ferroelectric thin film or the dielectric thin film is formed by the following steps. Is manufactured (Intern
national Application No. PC
T / US92 / 10542).

1) A step of coating and forming a precursor solution containing a composite alkoxide on a substrate by a spin coating method or the like.

2) In order to separate the solvent and the alcohol and residual water produced by the reaction in the step 1) from the film,
A step of heating and drying the obtained film at 150 ° C. for 30 seconds to several minutes.

3) RTA (Rapid Thermal Annea) for thermally decomposing and removing organic components in the film.
Ling) method, heat treatment at 725 ° C. for 30 seconds in an oxygen atmosphere.

4) A step of heat-treating at 800 ° C. for 1 hour in an oxygen atmosphere to crystallize the film.

5) A step of performing heat treatment at 800 ° C. for 30 minutes in an oxygen atmosphere after forming the upper electrode.

In order to obtain a desired film thickness, steps 1) to 3) are repeated, and finally steps 4) and 5) are performed.

As described above, the ferroelectric thin film or the dielectric thin film can be manufactured.

[0016]

In the conventional method of manufacturing a ferroelectric thin film as described above, a ferroelectric thin film manufactured by performing a step of performing crystallization before forming an upper electrode has a leakage current. In addition to a large current, it is necessary to perform heat treatment at a high temperature of about 800 ° C. for a long time in order to obtain a high remanent polarization value. Therefore, the ferroelectric thin film and the lower electrode become a rough film with large irregularities having a particle size of about 1000 to 2000 angstroms, which increases the leak current and lowers the dielectric strength, which makes further microfabrication difficult. Therefore, it is not suitable for high integration. Similarly, regarding the dielectric thin film, the conventional manufacturing method has the same problem as the ferroelectric thin film.

The present invention has been made in order to solve the above-mentioned problems, and lowers the film forming temperature and shortens the time compared with the conventional manufacturing method, and also reduces the leakage current and the dielectric. An object of the present invention is to provide a manufacturing method for realizing the densification of a thin film and an improvement in precision of fine processing, and a semiconductor memory device manufactured by the manufacturing method and having a high degree of integration.

[0018]

According to the present invention, the above-mentioned object is a method of manufacturing a semiconductor memory device including a memory cell having one switch transistor and one dielectric capacitor. A semiconductor substrate on which a transistor is formed is covered with a first insulator thin film, and a first contact hole penetrating the first insulator thin film is provided;
The inside of the first contact hole is filled with a conductive material, the surface of the first insulator thin film and the surface of the conductive material are flattened, and a lower electrode is formed on the flattened surface. A precursor solution containing at least one metal is applied to the surface of the lower electrode, and the applied precursor solution is heated to remove only the solvent and dried, and the dried precursor is heated to form an oxide film. A first heat treatment step of forming a film, the lower electrode and the oxide film are processed to a predetermined size, and the processed lower electrode and the oxide film are covered with a second insulating thin film, and the second insulating film is formed. A second contact hole penetrating the body thin film is provided, an upper electrode is formed inside the second contact hole, the formed upper electrode is processed into a predetermined size, and the oxide film is heated to thereby dielectric capacitor. Including a second heat treatment step to stabilize the properties of In the first heat treatment step, the heating temperature is rapidly raised to keep it in the vicinity of the crystallization temperature of the material that is the main component of the oxide film, thereby thermally decomposing and removing the organic matter at the same time. In the second heat treatment step, the material serving as the main component of the oxide film is crystallized by heating at a temperature equal to or higher than the crystallization temperature for a sufficient time. This is solved by a method of manufacturing a semiconductor memory device, which comprises forming the oxide film.

According to the present invention, the above-mentioned object is a semiconductor memory device including a memory cell having one switching transistor and one dielectric capacitor, the semiconductor memory device having the switching transistor formed thereon. A first insulator thin film covering the first insulator thin film, a first contact hole penetrating the first insulator thin film and filled with a conductive substance inside, and formed on the surface of the first insulator thin film and the surface of the conductive substance. A lower electrode, an oxide film containing at least one kind of metal formed on the surface of the lower electrode, a second insulator thin film processed to have a predetermined size and covering the lower electrode and the oxide film, A second contact hole penetrating the second insulator thin film and an upper electrode formed in the second contact hole and processed to a predetermined size are provided, and the oxide film has a grain size of 200. It is solved by a semiconductor memory device characterized by Ngusutoromu or less.

According to the present invention, the above-mentioned object is a ferroelectric thin film element or a dielectric thin film element including a memory cell having one switching transistor and one dielectric capacitor, wherein the switching transistor is A first insulator thin film covering the formed semiconductor substrate, a first contact hole penetrating the first insulator thin film and filled with a conductive material, a surface of the first insulator thin film and the first contact thin film. A lower electrode formed on the surface of the conductive material, and an oxide film containing at least one kind of metal formed on the surface of the lower electrode,
A second insulator thin film processed to have a predetermined size and covering the lower electrode and the oxide film, a second contact hole penetrating the second insulator thin film, and formed inside the second contact hole And a top electrode processed into a predetermined size, and the oxide film is a ferroelectric material, which is solved by a ferroelectric thin film element or a dielectric thin film element.

Regarding the features of the method for producing a dielectric thin film or ferroelectric thin film according to the present invention and the details of the optimum film forming conditions, Japanese Patent Application No. 7-14324 previously filed by the present inventors.
No. 3 specification. According to this, by making the temperature of the first heat treatment step very close to the crystallization temperature,
It can be seen that a film having a dense film quality and the best characteristics can be obtained.

According to the method of manufacturing a semiconductor memory device of the present invention, the film forming temperature can be lowered and the time can be shortened as compared with the conventional manufacturing method, and at the same time, a dense and flat dielectric thin film having a small particle size and Since the lower electrode thin film can be obtained, microfabrication becomes easy and highly precise machining becomes possible.
Since it is possible to manufacture a dielectric capacitor having a small leak current and a high withstand voltage, it is extremely useful in device manufacture.

[0023]

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

FIG. 1 is a sectional view showing the structure of an embodiment of a ferroelectric memory cell according to the present invention. The ferroelectric memory cell of FIG. 1 includes a first conductivity type silicon substrate 1 as a semiconductor substrate, an element isolation oxide film 2 and a gate oxide film 3.
A second conductivity type impurity diffusion region 4, a polysilicon word line 5, and 6, 7, 14 and 15 as interlayer insulating films,
A memory portion contact plug 8 in which impurity-diffused polysilicon is buried in a contact hole, a TiN barrier metal layer 9, a lower electrode 10, a ferroelectric thin film 11, a Pt plate line 12 as an upper electrode, and Ta ₂ O. _{5 The} barrier insulating film 13 and the Al bit line 16 are provided.

The method of manufacturing the semiconductor memory device of the present invention will be described below.

FIG. 2 is an explanatory view showing each stage of the embodiment of the method for manufacturing a semiconductor memory device of the present invention.

First, as shown in FIG. 2A, after forming a switching transistor by a known MOSFET formation process and covering it with an interlayer insulating film 6, only a portion where a bit line contacts the impurity diffusion region 4 of the substrate. After forming a contact hole by using a known photolithography method and a dry etching method and burying impurity diffused polysilicon to form a polysilicon plug 8, a known CMP (Chemi) method is used.
cal Mechanical Polishing)
By the method, the surfaces of the interlayer insulating film 6 and the polysilicon plug 8 are flattened.

Next, as shown in FIG. 2B, a TiN barrier metal layer 9 having a film thickness of 2000 is formed by a known sputtering method.
After the angstrom deposition, a Pt thin film is deposited to a thickness of 1000 angstrom by a known sputtering method to form the lower electrode 10. A SrBi ₂ Ta ₂ O ₉ thin film (hereinafter referred to as an SBT thin film) is formed as a ferroelectric thin film 11 on the lower electrode 10, and a method of forming the SBT thin film will be described later in detail.

The formed SBT film 11 and Pt lower electrode 10
Then, the TiN barrier metal layer 9 and the TiN barrier metal layer 9 are processed into a size of 3.0 μm square by using the known photolithography method and dry etching method to form a shape as shown in FIG. An ECR etcher is used for dry etching, and the gas species used are SBT film mixed gas of Ar, Cl ₂ and CF ₄ ,
The Pt lower electrode is a mixed gas of C ₂ F ₆ , CHF ₃ and Cl ₂ , and the TiN barrier metal is Cl ₂ gas. This time,
Since the SBT film 11 and the Pt lower electrode 10 are extremely dense and flat, precise microfabrication is possible and the CD loss can be suppressed to 0.1 μm or less.

Next, as shown in FIG. 2C, a film thickness of 30
A 0 Å Ta ₂ O ₅ barrier insulating film 13 is deposited by a known sputtering method, and then the interlayer insulating film 1 is deposited.
4, a silicon oxide film having a film thickness of 1500 angstrom is deposited by a known CVD method, and then the SBT film 11 is formed.
A 2.0 μm square contact hole is formed in the upper part of the polysilicon plug 8 by a known photolithography method and dry etching method.

Next, as shown in FIG. 2D, the film thickness 10
After forming a Pt upper electrode 12 of 00 angstrom and processing it by a known photolithography method and dry etching method to form a plate line, as a second heat treatment, R
The SBT film is crystallized by performing a heat treatment at 750 ° C. for 30 minutes in an atmospheric oxygen atmosphere using the TA method. Similarly, the cross section of the SBT film 11 after being crystallized is very smooth and dense, and the shape of the ferroelectric capacitor is not damaged.

After that, the interlayer insulating film 15 is deposited and planarized by using the known planarization technique and the CVD method, and the other impurity diffusion of the switch transistor is performed by the known photolithography method and the dry etching method. A contact hole to the region is formed, and a bit line 16 is formed by using a known Al wiring technique to complete the ferroelectric memory cell as shown in FIG.

The method of forming the SBT thin film 11 described above will be described below.

First, a method of synthesizing the precursor solution used for forming the SBT thin film will be described with reference to the flowchart of FIG.

Tantalum ethoxide (Ta (OC ₂ H ₅ ) ₅ ), bismuth 2-ethylhexanate (Bi (C ₇ H ₁₅ COO) ₂ ), and strontium 2-ethylhexanate (Sr (C ₇ H ₁₅ COO)
_{Use 2} ). Tantalum ethoxide 17 is weighed (step S31) and dissolved in 2-ethylhexanate 18 (step S32). 1 to accelerate the reaction
Stir while heating from 00 ℃ to the maximum temperature of 120 ℃,
The reaction is performed for 30 minutes (step S33). Then, 12
The ethanol and water produced by the reaction were removed at 0 ° C. Sr / T of strontium 2-ethylhexanate dissolved in 20 ml to 30 ml of xylene was added to this solution.
Add an appropriate amount so that a = 1/2 (step S34),
The mixture is heated and stirred from 125 ° C. to a maximum temperature of 140 ° C. for 30 minutes (step S35). Then, bismuth 2-ethylhexanate dissolved in 10 ml of xylene was added to this solution as S.
Add an appropriate amount so that r / Bi / Ta = 1/2/2 (step S36), and increase the temperature from 130 ° C to 150 ° C by 10 ° C.
The mixture is heated and stirred for time (step S37). Then, the solution was distilled for 5 hours at a temperature of 130 to 150 ° C. to remove low molecular weight alcohol, water and xylene used as a solvent, and 0.4 to remove dust from the solution.
Filter with a filter having a diameter of 5 μm (step S38). Finally, the concentration of SrBi ₂ Ta ₂ O ₉ in the solution was 0.1 mol.
/ L, and this is used as a precursor solution (step S39). Note that these raw materials are not limited to those described above, and any solvent may be used as long as it can sufficiently dissolve the above-mentioned starting materials.

Next, using this precursor solution, a film is formed in the following steps.

The above precursor solution is dropped onto the rotated wafer and spin coated. The coating conditions are 3000 rpm and 2
It is about 0 seconds. Then, the wafer is placed on a hot plate heated to 120 ° C. and baked in the atmosphere for 5 minutes to be dried. After that, to completely evaporate the solvent, the wafer is
Place on a hot plate heated to 0 ° C. and bake in air for 5 minutes. This film forming process is repeated three times to obtain a film thickness of 2000
An angstrom ferroelectric thin film is formed. afterwards,
As the first heat treatment, the RTA method is used to perform heat treatment at 580 ° C. for 30 minutes in an oxygen atmosphere at atmospheric pressure.

Observation of the SBT thin film thus formed revealed that the surface was smooth and the structure in the film had a particle size of 200 Å or less and was very dense.

FIGS. 4 and 5 are graphs in which the electric characteristics of the ferroelectric memory cell manufactured as described above are measured using a known Sawyer tower circuit. FIG. 4 and FIG.
The values of Pr and Ec when the applied voltage is changed between 1 and 12 V are shown respectively. As can be seen from these graphs, Pr and Ec were saturated at 3 V or higher, and it was confirmed that the ferroelectric capacitor was sufficiently operated. Moreover, the value of the leak current at an applied voltage of 3 V is 5 × 10 ⁻⁹
It was about A / cm ² , and sufficient characteristics were confirmed as a ferroelectric capacitor.

FIG. 6 is a graph plotting the change of the accumulated charge amount δQ with respect to the number of repeated polarization inversions when the voltage of 3V and the pulse of frequency 1MHz are applied to repeat the polarization inversions. No change was observed in the accumulated charge amount even after the polarization reversal of 2 × 10 ¹¹ cycles, showing good characteristics as a nonvolatile memory.

In the above embodiment, the ferroelectric substance
Although SBT was used as the material of the present invention, the present invention is not limited to this.
Not PZT, SrBi₂Nb₂O₉, Sr
Bi ₂(Ta, Nb)₂O₉, Bi_FourTi_ThreeO₁₂, Sr
Bi_FourTi_FourO_Fifteen, SrBi_Four(Ti, Zr)_FourO_Fifteen,
CaBi₂Ta₂O₉, BaBi₂Ta₂O₉, BaB
i₂Nb₂O₉, PbBi₂Ta₂O₉Such as sol-gel
The present invention is not limited as long as it is a material that can be formed into a film by the MOD method or the MOD method.
Applicable.

[0042]

According to the method of manufacturing a semiconductor memory device of the present invention, the film forming temperature can be lowered and the time can be shortened as compared with the conventional manufacturing method, and at the same time, a dense and flat dielectric having a small particle size can be obtained. Since a thin film and a lower electrode thin film can be obtained, microfabrication becomes easy and highly precise processing is possible, and a dielectric capacitor with a small leak current and a high withstand voltage can be manufactured, which is extremely useful in device manufacturing. Is.

According to the semiconductor memory device of the present invention, a dense and flat lower electrode thin film having a particle size smaller than that of the conventional device can be obtained, fine processing can be performed with high accuracy, and leakage current is small and insulation is possible. A dielectric capacitor having a high breakdown voltage can be obtained.

According to the ferroelectric thin film element or the dielectric thin film element of the present invention, since a dense and flat dielectric thin film having a smaller particle size than that of the conventional element can be obtained, it is possible to perform fine processing with high precision. In addition, a dielectric capacitor having a small leak current and a high withstand voltage can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a ferroelectric memory cell according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing steps of a method for manufacturing a semiconductor memory device of the present invention.

FIG. 3 is a flowchart showing a step of synthesizing a precursor solution used in the step of FIG.

FIG. 4 is a graph showing changes in remanent polarization Pr when the voltage applied to the SBT ferroelectric capacitor of FIG. 1 is changed.

5 is a graph showing changes in the coercive electric field Ec when the voltage applied to the SBT ferroelectric capacitor of FIG. 1 is changed.

6 is a graph showing fatigue characteristics of the SBT ferroelectric capacitor of FIG.

[Explanation of symbols]

1 First conductivity type silicon substrate 2 Element isolation oxide film 3 Gate oxide film 4 Second conductivity type impurity diffusion region 5 Polysilicon word line 6, 7, 14, 15 Interlayer insulating film 8 Memory contact plug 9 TiN barrier metal layer 10 Pt lower electrode 11 Ferroelectric thin film 12 Pt plate line 13 Ta ₂ O ₅ barrier insulating film 16 Al bit line

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masayoshi Kiba 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (11)

[Claims] 1. A method of manufacturing a semiconductor memory device including a memory cell having one switch transistor and one dielectric capacitor, wherein a first insulator thin film is formed on a semiconductor substrate on which the switch transistor is formed. And forming a first contact hole penetrating the first insulator thin film, filling the inside of the first contact hole with a conductive substance, and forming a surface of the first insulator thin film and a surface of the conductive substance. And forming a lower electrode on the flattened surface, applying a precursor solution containing at least one metal to the surface of the formed lower electrode, and heating the applied precursor solution. Then, only the solvent is removed and dried, and the first precursor is heated to form an oxide film, and the lower electrode and the oxide film are processed into a predetermined size and processed. Lower electrode and oxidation The film is covered with a second insulator thin film, a second contact hole penetrating the second insulator thin film is provided, an upper electrode is formed inside the second contact hole, and the formed upper electrode is predetermined. And a second heat treatment step of heating the oxide film to stabilize the characteristics of the dielectric capacitor, and rapidly heating the heating temperature in the first heat treatment step. The organic substance is pyrolyzed and removed by keeping it near the crystallization temperature of the material that is the main component of the oxide film, and at the same time, the very fine crystal nuclei are stopped and the second heat treatment step is performed. 2. The method for manufacturing a semiconductor memory device according to, wherein the oxide film is formed by crystallizing a material which is a main component of the oxide film by heating at a temperature equal to or higher than the crystallization temperature for a sufficient time. 2. The method according to claim 1, wherein the oxide film is a ferroelectric material. 3. The method of manufacturing a semiconductor memory device according to claim 1, wherein the oxide film is made of a bismuth layer structure compound material. 4. The temperature when the applied precursor solution is heated to remove only the solvent and dried is 150 ° C. or higher and 350 ° C. or lower, according to any one of claims 1 to 3.
Item 8. A method of manufacturing a semiconductor memory device according to item. 5. The heating rate of the heating temperature in the first heat treatment step is 20 ° C./sec or more, and the heating temperature is 500.
5. The method for manufacturing a semiconductor memory device according to claim 1, wherein the temperature is not lower than 700.degree. C. and not higher than 700.degree. 6. The heating temperature of the second heat treatment step is higher than the heating temperature of the first heat treatment step and is 600 ° C.
6. The method for manufacturing a semiconductor memory element according to claim 1, wherein the temperature is 800 ° C. or higher. 7. The method of manufacturing a semiconductor memory device according to claim 1, wherein the precursor solution contains a metal carboxylate and an alkoxide as components. 8. A semiconductor memory device including a memory cell having one switch transistor and one dielectric capacitor, the first insulator thin film covering a semiconductor substrate on which the switch transistor is formed, A first contact hole penetrating the first insulator thin film and filled with a conductive substance inside; a lower electrode formed on the surface of the first insulator thin film and the surface of the conductive substance; and a lower electrode of the lower electrode. An oxide film containing at least one type of metal formed on the surface, a second insulator thin film that is processed to have a predetermined size and covers the lower electrode and the oxide film, and penetrates the second insulator thin film. A second contact hole and an upper electrode formed inside the second contact hole and processed to a predetermined size, and the grain size of the oxide film is 200 angstroms or less. A semiconductor memory device characterized by: 9. A ferroelectric thin film element or a dielectric thin film element including a memory cell having one switch transistor and one dielectric capacitor, which covers a semiconductor substrate on which the switch transistor is formed. One insulator thin film, a first contact hole penetrating the first insulator thin film and filled with a conductive material inside, and a lower part formed on the surface of the first insulator thin film and the surface of the conductive material. An electrode, an oxide film containing at least one kind of metal formed on the surface of the lower electrode, a second insulator thin film processed to have a predetermined size and covering the lower electrode and the oxide film, A second contact hole penetrating the second insulator thin film; and an upper electrode formed in the second contact hole and processed to a predetermined size. The oxide film is a ferroelectric substance. Special Ferroelectric thin film element or dielectric thin film element to be characterized. 10. The oxide film is Sr, Ba, Bi, P
b, Ti, Ta, Hf, W, Nb, Zr, Sc, Y, L
The ferroelectric thin film element or the dielectric thin film according to claim 9, which contains a metal having a high electropositivity, which comprises one or more elements selected from a, Sb, Cr and Tl. element. 11. The oxide film is Sr, Ba, Bi, P
10. The ferroelectric thin film element or the dielectric thin film element according to claim 9, containing one or more elements selected from b, Ti, Ta, Nb and Zr.