JPH08153854A - Manufacture of ferroelectric thin-film capacitor - Google Patents

Abstract

PURPOSE: To form the thin-film of a compound, capable of being applied to an actual device by conducting calcination for a very short time by quick temperature-rise heating at a temperature higher than the crystallization temperature of a lead- containing complex oxide ferroelectric and performing baking for a relatively prolonged period at the temperature higher than the crystallization temperature. CONSTITUTION: A large number of metallic atoms and decomposed and dissociated organic residual are contained in a metallic oxide thin-film on a lower electrode formed by thermally decomposing an organometallic compound, and an amorphous state not containing any crystalline structure at all is brought. The amorphous state is calcined and treated for a very short time at a temperature higher than the crystallization temperature of an aimed lead-containing complex compound ferroelectric material by one-time quick temperature-rise heating. Baking for a relatively prolonged period is conducted at the temperature higher than the crystallization temperature. Accordingly, the isolation-voltage characteristics of the thin-film of a lead-containing complex compound ferroelectric and a bismuth layer-shaped compound are improved, and the thin-film of the compound capable of being applied to an actual device can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide ferroelectric thin film for use in electronic devices such as non-volatile semiconductor memories and piezoelectric pyroelectric sensors that utilize the remanent polarization characteristics of ferroelectric thin films, as well as transducers and actuators. The present invention relates to a method for manufacturing a capacitor, and particularly to a method for manufacturing a ferroelectric thin film capacitor having excellent withstand voltage characteristics.

[0002]

2. Description of the Related Art Conventionally, ferroelectric compounds have been used in many fields by utilizing their unique electrical characteristics. For example, it is applied to piezoelectric filters and ultrasonic transducers that utilize piezoelectricity, infrared sensors and pyrovidicons that utilize pyroelectricity, and various fields such as optical modulators and optical shutters that utilize the electro-optic effect. ing. In addition, electronic devices using thin films of these materials were also devised,
Studies on thinning are being made vigorously. In particular, a non-volatile memory device equipped with a ferroelectric thin film capacitor that utilizes the stability of remanent polarization is the field that has received the most attention due to the recent trend toward higher storage capacities and higher integration.

Representative materials that are being competitively studied according to such versatile applications include PZT (lead zirconate titanate), PLZT (lead lanthanum zirconate titanate), and the like.
A series of lead-containing complex oxide ferroelectrics have been mentioned, and many researchers have been studying their practical use for many years.

As another promising ferroelectric material,
U.S. Patent Application 9651 identified by the present inventors
90 (filed October 23, 1992), USP9811
33 (filed on November 24, 1992), there is a thin film of bismuth layered perovskite type oxide ferroelectric. This material is superior in polarization reversal fatigue (a phenomenon in which the polarization reversal ability is reduced and the amount of polarization is gradually attenuated by repeating polarization reversal a number of times) is superior to conventional thin films such as PZT and PLZT. Exploiting its advantages, it is expected to be applied to non-volatile memory devices and other electronic and optical devices.

A bismuth layered perovskite type oxide ferroelectric (hereinafter referred to as a bismuth layered compound) has a composition represented by the following general formula (1), and a perovskite-like crystal having a vertex shared in its unit crystal lattice. A repeating unit composed of two parts: a part consisting of a structure and exhibiting ferroelectricity (some compositions have non-ferroelectric properties), and a non-ferroelectric part consisting of bismuth oxide adjacent to this part. And has an extremely long unit cell in the c-axis direction.

(Bi ₂ O ₂ ) ²⁺ (A _m-1 B _m O _{3m + 1} ) ²⁻ (1) A = Bi, Pb, Ba, Sr, Ca, Na, K, Cd A combination of one or more elements at any ratio.

B = Ti, Nb, Ta, W, Mo, Fe,
A combination of one or more elements selected from Co and Cr in an arbitrary ratio. A natural number of m = 1 to 5.
Of these bismuth layered compounds, those showing ferroelectricity applicable to practical devices include Bi ₄ Ti ₃ O.
₁₂ (bismuth titanate) and other SrBi ₄ Ti ₄
O ₁₅ (strontium bismuth titanate), SrBi ₂
Ta ₂ O ₉ (strontium bismuth tantalate) Sr
Bi ₂ Nb ₂ O ₉ (Strontium Bismuth Niobate)
Etc. Also, a solid solution thin film made of a combination of two or more of these, such as SrBi ₂ Nb ₁
It is known that Ta ₁ O ₉ also exhibits excellent ferroelectricity.

In order to form thin films of these lead-containing complex oxide ferroelectrics and bismuth layered compounds on a substrate, a general thin film forming method, that is, a vacuum film forming method typified by a sputtering method and a sol-gel method are used. , Pyrolysis of organic compounds (MOD method)
Solution coating method, a chemical vapor deposition method (CVD
Method), mist deposition (a method similar to CVD in which a liquid material is made into fine mist droplets and deposited on a substrate).

In a vacuum film forming method such as sputtering, substrate heating is used as a conventional means in order to perform crystallization to some extent on a substrate and prevent accumulation of internal stress to improve substrate adhesion. . However, bismuth in the composition of the bismuth layered compound, oxides such as lead in the lead-containing composite oxide ferroelectric have a very large saturated vapor pressure compared to other metal elements or oxides, and under high vacuum. Furthermore, there is a problem in that the composition of the thin film obtained by evaporation easily deviates greatly from the composition of the target or evaporation source, and reproducibility and controllability have not yet been established.

Therefore, in order to precisely control the composition of a compound thin film having a complicated composition such as a ternary or quaternary compound and form a large area under a normal temperature and normal pressure environment, the sol-gel method, MO
Method D is advantageous. Next, the mist deposition method, which can use a raw material solution common to these methods, is based on this.
Regarding the MOD method, the inventors of the present invention relate to a film forming process of a bismuth layered compound thin film in US Patent Application No.
(Filed on May 21, 1992).

A sol-gel method or a MOD method is used to dry a coating film composed of a precursor mixture of metal-organic compounds, and then subjected to a calcination treatment by rapid heating to accelerate the crystallization reaction in the subsequent annealing treatment. It is possible to obtain a crystallized film having a stable composition and form a thin film capacitor having excellent electrical characteristics. However, as a result of further research conducted by the present inventors, in this conventional process, the absolute value of the residual polarization amount, the saturation characteristic of the hysteresis curve, and the like were able to obtain good reproducibility together with fatigue resistance. Withstand voltage characteristics are low, leakage current increases at 5-10V for PZT thin films, and 2-3 for bismuth layered compounds.
It was found that dielectric breakdown may occur even at a DC low voltage of V.

As a practical level of a ferroelectric thin film capacitor, a thin film which can maintain an insulating property with respect to an applied voltage of at least 5 V and has a small leak current is used in semiconductor device applications. There has been a demand for prompt improvement of the withstand voltage characteristics of thin films of such lead-containing complex oxide ferroelectrics and bismuth layered compounds.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has improved the withstand voltage characteristics of thin films of a lead-containing complex oxide ferroelectric and a bismuth layered compound by a conventional process, It is an object of the present invention to provide a method of manufacturing a ferroelectric thin film capacitor that can form a thin film of the compound applicable to a device.

[0014]

The present invention aims to improve the dielectric strength of a lead-containing complex oxide ferroelectric material and a bismuth layered compound thin film, which are related to this, for use in a practical device, and to improve the withstand voltage of the metal-organic compound precursor. The metal oxide thin film obtained by heat-oxidizing is rapidly heated at a higher temperature than the conventional process, more specifically, at a temperature higher than the crystallization temperature of the target lead-containing complex oxide ferroelectric or bismuth layered compound ferroelectric. The problem was solved by performing a calcination treatment by heating for an extremely short time and then performing a calcination treatment for a relatively long time at a temperature higher than the crystallization temperature.

The method of manufacturing the ferroelectric thin film capacitor according to the present invention will be described in detail below. This invention comprises a step of forming a lower electrode layer made of an electrically conductive metal thin film or an oxide thin film on a semiconductor substrate, and a plurality of metal organic compounds corresponding to constituent elements of a target ferroelectric material on the lower electrode layer. A step of forming a thin film containing a precursor mixture of a compound as a main component; a step of heating and oxidizing the thin film to form a metal oxide thin film;
A step of performing a rapid heating process at a rapid temperature, a step of forming an upper electrode layer made of an electrically conductive metal thin film or an oxide thin film on the formed ferroelectric thin film, the upper electrode layer and the ferroelectric thin film In the method for manufacturing a ferroelectric thin film capacitor, which includes a step of forming a capacitor structure by etching a lower electrode layer and the like into a predetermined shape and a step of performing a reheating process on the capacitor structure, a rapid heating temperature is used. Is a crystallization temperature of the ferroelectric material or higher.

In the present invention, the ferroelectric thin film is a bismuth layered compound represented by the general formula (1). (Bi ₂ O ₂ ) ²⁺ (A _m-1 B _m O _{3m + 1} ) ^2- (1) A = one selected from Bi, Pb, Ba, Sr, Ca, Na, K, and Cd, or Combination of multiple elements at any ratio.

B = Ti, Nb, Ta, W, Mo, Fe,
A combination of one or more elements selected from Co and Cr in an arbitrary ratio. A natural number of m = 1 to 5.

In the present invention, the ferroelectric thin film is PZT represented by the general formula (2) or a modified product thereof. _{(Pb 1-x + a A} x) (Zr 1-yz Ti y B z) O 3 + βMeO (2) a = 0~0.2 A = Ca, Sr, Ba, Th, La, Y, Sm, Dy ，
A combination of one or more elements selected from Ce, Bi, and Sb in an arbitrary ratio.

X = 0 to 0.3 y = 0 to 0.9 B = Hf, Sn, Nb, Ta, W, Mo A combination of one or a plurality of elements selected from arbitrary ratios.

Z = 0 to 0.3 β = 0 to 0.05 Me = La, Y, Sm, Dy, Ce, Bi, Sb, N
b, Ta, W, Mo, Cr, Co, Ni, Fe, Cu,
A combination of one or more elements selected from Si, Ge, U and Sc in an arbitrary ratio.

[0021]

In the present invention, the metal oxide thin film formed on the lower electrode by the thermal decomposition of the metal organic compound contains a large amount of organic residues that are decomposed and dissociated with the metal atoms, and the whole has a crystal structure. It is in an amorphous state that does not contain it. This is subjected to at least one rapid heating process at a temperature above the crystallization temperature of the intended ferroelectric material to form a ferroelectric thin film. In the initial stage of this step, countless minute crystal nuclei of the target oxide ferroelectric can be generated in the metal oxide thin film. The thin film is heated above the crystallization temperature all at once with a sudden temperature change,
It is considered that mechanical tension, shear stress, thermal strain, and concentration caused by this occur, nucleation occurs around these, and innumerable nuclei are instantly generated.

The density of crystal nuclei can be controlled by appropriately selecting the conditions (temperature rising rate, processing temperature and holding time) of the rapid heating process, and further promotes crystal growth corresponding to the holding time. By increasing the density of the generated crystal nuclei, the distance between the particles is shortened in proportion to the density and an efficient and uniform crystallization reaction is promoted. The dielectric thin film is formed in a short time.

The thin film capacitor comprising the lead-containing composite oxide ferroelectric and the bismuth layered compound thin film formed by the film forming process of the present invention has few defect layers on the surface of each crystal grain,
Due to the dense film structure in which the non-ferroelectric phase dispersed in the grain boundary layer is also minimized, it exhibits extremely excellent dielectric strength.

Further, in the rapid temperature rising heat treatment, since crystal formation is performed in a very short time, a compound of bismuth oxide or lead oxide in the thin film composition, which is easily vaporized and deficient, is taken into the crystal lattice and is also heated and baked. It is not lost and the composition can be easily controlled, and a uniform thin film having a low defect density on the surface and inside can be obtained.

In the present invention, the ferroelectric thin film is the bismuth layered compound of the formula (1). Therefore, the bismuth layer compound ferroelectric according to the present invention has a layered crystal structure composed of repeating units formed by regularly overlapping the bismuth oxide layer having a two-dimensional spread and the ferroelectric perovskite structure. Many bismuth layered compounds have higher durability against polarization inversion fatigue than lead-containing composite oxides.

By forming a bismuth layered compound by the film forming process of the present invention, it is possible to provide a ferroelectric thin film capacitor having excellent polarization inversion fatigue characteristics and high withstand voltage.

In the present invention, the ferroelectric thin film is PZT of the formula (2) or its modified product. Therefore, the PZT-based ferroelectric material according to the present invention has a large polarization performance, and a large current can be taken out even if the capacitor area is made small, so that the storage capacity can be made high and the cell area can be made small in memory applications. Is advantageous to.

By forming a lead-containing composite oxide ferroelectric thin film by the film forming process of the present invention, it is possible to provide a ferroelectric thin film capacitor having excellent polarization reversal fatigue characteristics and high withstand voltage.

[0029]

【Example】

(Comparative Example 1) SrBi ₂ Ta ₂ O ₉ by the conventional process
A thin film was formed to form a capacitor, which was referred to as Comparative Example 1.

As a precursor solution, 2 each of Sr, Bi and Ta
Using a solution of ethyl hexanoate in xylene, Bi was added in a 10% excess with respect to the stoichiometric ratio. The coating density is 0.
15M, 200nm at a speed of 2000rpm
A film was formed on a silicon substrate provided with a platinum electrode. After the coating film was dried at 250 ° C. for 5 minutes, it was heated to 725 ° C. at a temperature rising rate of 125 ° C./sec using a lamp annealer and subjected to a rapid temperature rising bake for 30 seconds in oxygen. The process from coating film formation to baking was repeated 3 times to form a multilayer film, and annealing (primary annealing) was performed at 800 ° C. for 60 minutes in an oxygen stream. As a result, SrBi ₂ Ta _{2 with} a film thickness of 240 nm was formed.
An O ₉ thin film was obtained. An upper platinum electrode having a film thickness of 200 nm was formed on the ferroelectric thin film by sputtering, and etching was performed using an ion mill to form a capacitor. The capacitor area is 100 μm × 100 μm (= 10000 μm ² ). Finally, the entire substrate was subjected to secondary annealing at 800 ° C. for 30 minutes in an oxygen stream.

The following examples were prepared using the same solution as in Comparative Example 1 above. Process parameters not particularly described are the same as those in Comparative Example 1. (Example 1) A rapid heating process was performed under the conditions of a heating rate of 125 ° C / sec, a holding temperature of 800 ° C, and a holding time of 30 seconds to form a three-layer film having a film thickness of 240 nm. Then, without performing primary annealing, an upper platinum electrode having a film thickness of 200 nm was sputter-deposited on the ferroelectric thin film and etched using an ion mill to form a capacitor. Finally, the whole substrate was subjected to secondary annealing in an oxygen stream at 800 ° C. for 30 minutes, and this was set as Example 1.

(Embodiment 2) Rapid heating process at 125 ° C.
A three-layer film having a film thickness of 240 nm was formed under the conditions of a temperature rising rate of / sec, a holding temperature of 800 ° C., and a holding time of 30 seconds, and primary annealing was performed at 400 ° C. for 60 minutes in an oxygen stream. Other process conditions were the same as in Comparative Example 1, and a thin film capacitor was formed.
Secondary annealing was performed at 30 ° C. for 30 minutes.

(Embodiment 3) Rapid heating treatment at 125 ° C.
Another example was performed under the conditions of a temperature rising rate of 1 / second, a holding temperature of 800 ° C., and a holding time of 30 seconds to form a three-layer film having a film thickness of 240 nm, and annealing at 800 ° C. for 60 minutes in an oxygen stream. A capacitor was formed through the same steps as above. Finally, the entire substrate was subjected to secondary annealing in an oxygen stream at 800 ° C. for 30 minutes, and this was set as Example 3.

(Embodiment 4) Rapid heating process at 125 ° C.
A three-layer film was formed under the conditions of a heating rate of / sec, a holding temperature of 850 ° C., and a holding time of 30 seconds. Other process conditions were the same as in Example 3 to form a thin film capacitor. This is Example 4.

FIG. 1 shows the hysteresis curves of Comparative Example 1 and Examples 1 to 4. In the measurement, a normal Soyer tower circuit was used to apply sine waves of ± 2, ± 4, ± 6, ± 8, and ± 10 V, and a hysteresis curve for each input voltage was observed by observing an oscilloscope.

2 to 6 show current-voltage curves (IV curves) of Comparative Example 1 and Examples 1 to 4. For the measurement, a semiconductor parameter analyzer (product name: hp-4145) manufactured by Hewlett-Packard Company was used to measure the current value flowing between the upper and lower electrodes.

Comparing the hysteresis curves of FIG. 1,
Although the remanent polarization amount 2Pr is smaller in Examples 1 and 2 than in the other cases, Comparative Example 1 and Examples 3 and 4 show almost the same value, but both show good saturation characteristics.

2 to 6 show IV characteristics. It is a figure showing the amount of electric current which passes through a ferroelectric thin film to a certain applied voltage. Comparative Example 1 has a current value of 10 ⁻⁵ (A
/ Cm ² ), it is stable, but beyond that, spike-like leak current is observed and dielectric breakdown finally occurs at an applied voltage of 18V. On the other hand, in Examples 1 and 2, 10
The leak current does not increase up to V or more, and further, in Example 3, 2
Stable up to 0 V, and Example 4 shows stable IV current characteristics up to 25 V or more without breaking. That is, by performing the rapid temperature rising heat treatment at 800 ° C. or higher, it is possible to obtain a ferroelectric capacitor having a small leak current and excellent dielectric strength characteristics.

From the above results, it is shown that the effect of the present invention is clear. (Comparative Example 2) Pb (Zr _0.4 Ti by the conventional process
_{A 0.6} ) O ₃ thin film was formed to form a capacitor, which was designated as Comparative Example 2.

As a precursor solution, Pb acetate, Zr, T
Using a solution of each isopropoxide of i in 2 methoxyethanol, Pb was added in a 7% excess over the stoichiometric ratio.
A solution of 2 methoxyethanol in which acetic acid and distilled water were mixed with the metal in the solution in an equimolar amount was added to this to give a coating concentration of 0.5 M, and a film was formed on a silicon substrate provided with a platinum electrode having a thickness of 200 nm at a cutoff speed of 2000 rpm. . After the coating film was dried at 200 ° C. for 5 minutes, it was heated to 650 ° C. at a temperature rising rate of 125 ° C./sec using a lamp annealer and subjected to rapid temperature rising bake for 30 seconds in oxygen. The process from coating film formation to baking was repeated three times to form a multilayer film, which was annealed at 700 ° C. for 60 minutes in an oxygen stream. As a result, a Pb (Zr _0.4 Ti _0.6 ) O ₃ thin film having a film thickness of 300 nm was obtained. An upper platinum electrode having a film thickness of 200 nm was formed on the ferroelectric thin film by sputtering, and etching was performed using an ion mill to form a capacitor. Area of capacitor is 1
The size is 00 μm × 100 μm (= 10000 μm ² ).
Finally, the entire substrate is kept in an oxygen stream at 700 ° C for 30 minutes for 2 minutes.
Dimensional annealing was performed.

The following examples were prepared using the same solution as in Comparative Example 2 above. Process parameters not particularly described are the same as those in Comparative Example 2. (Example 5) A rapid temperature rising heat treatment was performed under conditions of a temperature rising rate of 125 ° C / sec, a holding temperature of 750 ° C, and a holding time of 30 seconds to form a three-layer film having a film thickness of 300 nm, and 750 in an oxygen stream.
Annealing was performed at 60 ° C. for 60 minutes. The upper platinum electrode was formed into a film and was etched using an ion mill to form a capacitor. Finally, the whole substrate was exposed to oxygen at 750 ° C for 3
Secondary annealing was performed for 0 minutes, and this was set as Example 5.

FIG. 7 shows current-voltage curves (1-V curves) of Comparative Example 2 and Example 5. Comparative Example 2 is about 10
The current value shows 10 ⁻⁵ A / cm ^{2 up} to V, but beyond that, the leak current gradually increases with increasing voltage, and dielectric breakdown occurs at about 30V. In contrast,
Example 5 similarly shows the same value as 10 ⁻⁵ A / cm ² around 10 V, but the leak current hardly increases up to 30 V or more.

In the fifth embodiment, the case where the electrically conductive metal forming the lower electrode layer and the upper electrode layer is platinum has been described, but it has a high melting point that can withstand the calcination and firing temperatures of the ferroelectric thin film. Any of noble metal elements such as rhodium, palladium, ruthenium, rubidium, iridium, osmium, etc., or alloys thereof, which have and have no chemical interaction such as alloying reaction with the ferroelectric constituent elements. Well, and stable in an oxidizing atmosphere,
And by itself having a regular arrangement of oxygen in the crystal structure and excellent interfacial compatibility with the oxide ferroelectric, indium oxide-tin oxide composite compound or ruthenium oxide, rubidium oxide, iridium oxide, osmium oxide. It may be any oxide of a noble metal element. Further, it may have a laminated structure of these metals and oxides.

The above description is based on the embodiment,
The present invention includes the following inventions. 1. (Corresponding to Example 1) A step of forming a lower electrode layer made of an electrically conductive metal thin film or an oxide thin film on a semiconductor substrate, and a plurality of elements corresponding to constituent elements of a target ferroelectric material on the lower electrode layer. A step of forming a thin film containing a precursor mixture composed of a metal organic compound as a main component; a step of heating and oxidizing the thin film to form a metal oxide thin film;
A step of performing a rapid heating process at a rapid temperature, a step of forming an upper electrode layer made of an electrically conductive metal thin film or an oxide thin film on the formed ferroelectric thin film, the upper electrode layer and the ferroelectric thin film In the method for manufacturing a ferroelectric thin film capacitor, which includes a step of forming a capacitor structure by etching a lower electrode layer and the like into a predetermined shape and a step of performing reheating treatment on the capacitor structure, the processing temperature for rapid heating is A method of manufacturing a ferroelectric thin film capacitor, characterized in that the temperature is equal to or higher than the crystallization temperature of a desired ferroelectric material.

(Function) The metal oxide thin film formed on the lower electrode by the thermal decomposition of the metal organic compound contains a large amount of organic residues which are decomposed and dissociated with the metal atoms, and the whole contains a crystal structure. There is no amorphous state.
This is subjected to at least one rapid heating process at a temperature above the crystallization temperature of the intended ferroelectric material to form a ferroelectric thin film. In the initial stage of this step, countless minute crystal nuclei of the target oxide ferroelectric can be generated in the metal oxide thin film. The thin film is heated at a temperature above the crystallization temperature with a sudden temperature change, and mechanical tension, shear stress, thermal strain, and concentration caused by this occur, and nucleation occurs around these, and innumerable nuclei Is considered to occur instantly.

The density of crystal nuclei can be controlled by appropriately selecting the conditions of the rapid heating process (heating rate, processing temperature and holding time), and further promotes crystal growth corresponding to the holding time. By increasing the density of generated crystal nuclei, the distance between particles is shortened in proportion to the density, and efficient and uniform crystallization reaction is promoted. The dielectric thin film is formed in a short time.

(Effect) A thin film capacitor comprising a lead-containing composite oxide ferroelectric and a bismuth layered compound thin film formed by the film forming process of the present invention has few defect layers on the surface of each crystal grain and is dispersed in the grain boundary layer. It has an extremely high dielectric strength due to its dense film structure with the non-ferroelectric phase minimized.

Further, in the rapid temperature rising heat treatment, since the crystal is grown in a very short time, the compound of bismuth oxide or lead oxide in the thin film composition, which is apt to be deficient in evaporation, is taken into the crystal lattice and lost during the heating and firing. Therefore, the composition can be easily controlled, and a uniform thin film having a low defect density on the surface and inside can be obtained. 2. (Corresponding to Examples 2 to 4 and Example 5) In the first item, following the step of performing the rapid temperature rising heat treatment, the ferroelectric thin film is further subjected to a firing treatment in a heating furnace to obtain the ferroelectric substance. A method of manufacturing a ferroelectric thin film capacitor, which is characterized in that a step of forming a thin film is added, and a firing temperature is lower than the rapid heating treatment temperature.

(Structure) According to the above contents. (Function) When the generation and growth of fine crystal nuclei are simultaneously performed by the rapid temperature rising heat treatment, the dielectric strength characteristics of the thin film are improved by the function and effect based on the first term, but due to the rapid crystallization, the grain boundary layer is not yet formed. In some cases, the crystal component is likely to remain and the ferroelectricity after the formation of the capacitor cannot be sufficiently expressed, or a large stress remains in the film to cause cracks over time. Rapid and high-temperature heat treatment promotes an efficient and uniform crystallization reaction by baking a thin film in which crystal nuclei are formed with a certain density and at the same time uncrystallized components remain, at a temperature above the crystallization temperature for a long time. be able to. At the same time, crystal grains fuse with each other to form a dense ferroelectric thin film having a uniform grain size in a short time.

(Effects) According to the film forming process of the present invention described above, the thin film composition of the lead-containing complex oxide ferroelectric and the bismuth layered compound forming the thin film capacitor can be easily controlled, and the size of each crystal grain can be controlled. It is possible to obtain a very good withstand voltage thin film having a uniform and dense film structure in which 3. (Corresponding to Examples 2 to 4 and Example 5) The means for forming a thin film containing a precursor mixture of the metal organic compound as a main component is a solution coating method by spin coating. 3. The method for manufacturing a ferroelectric thin film capacitor as described in 2.

(Constitution) The lead-containing composite oxide ferroelectric material,
For example, a PZT film is formed by using a sol-gel method, and an appropriate metal compound precursor soluble in an organic acid salt such as lead acetate trihydrate, titanium isopropoxide, zirconium propoxide, or an organic solvent such as a metal alkoxide. Is mixed at a composition ratio according to the target material, 2-methoxyethanol,
If necessary, water, a pH adjuster, a hydrolysis catalyst, etc. are added to a precursor solution dissolved in an organic solvent such as 2-methoxy-1-propanol or 2-ethoxyethanol, and the solution is spread on a substrate by spin coating. Form a thin film.

In the case of the bismuth layered compound,
Metal alkoxides such as Sr isopropoxide and Ta ethoxide, metal organic acid salts such as bismuth 2-ethylhexanoate, strontium 2-ethylhexanoate, and strontium n-octanoate, and β-diketone compounds such as acetylacetone compounds and other organic compounds. A suitable metal compound soluble in a solvent is mixed at a ratio corresponding to the composition of the target material, and an aliphatic alcohol such as 2-methoxyethanol, 2methoxy-1-propanol, 2-ethoxyethanol, ethyl acetate, butyl acetate, etc. The MOD method is used in which a precursor solution dissolved in an ester solvent, an aromatic solvent such as toluene or xylene, or another organic solvent is spread on a substrate by spin coating to form a thin film.

The coating film immediately after spin coating is a liquid film containing a large amount of solvent. The organic solvent is evaporated and removed by heating this, and the organic metal compound is thermally decomposed to form a metal oxide thin film. By applying the manufacturing method of the present invention to the formed oxide thin film, a rapid heating process is performed at a crystallization temperature of the ferroelectric material or higher to obtain a raw ferroelectric thin film (hereinafter, a film including a firing step is formed. The thin film that is finally formed by firing in the process is a ferroelectric thin film, and in order to be distinguished from this, the thin film that has been subjected to the rapid heating treatment and before firing is referred to as the "original ferroelectric thin film"). The ferroelectric thin film is baked in a heating furnace at a temperature equal to or higher than the crystallization temperature of the ferroelectric material to complete the crystallization reaction and form a ferroelectric thin film. After forming an upper electrode layer on the ferroelectric thin film and forming a capacitor structure by etching, reheating treatment is performed.

(Function) Since both the sol-gel method and the MOD method can be directly applied to the measurement of the weight or volume of the raw material compound in the first solution preparation step, any complicated compositional composition can be accurately reproduced. This is an advantage over any other vacuum film forming method. Since it is easy to obtain a state in which organic compounds of each metal element are mixed at the molecular level, crystallization, which is a solid-phase reaction, can lower the overall process temperature by several hundred degrees Celsius compared to bulk ceramics. It is the most suitable film forming method for device applications. The uniform amorphous state that has undergone the heating and oxidation process facilitates the generation of crystal nuclei by the subsequent rapid heating and calcination process, and makes it possible to form a homogeneous thin film having no composition distribution or characteristic distribution.

(Effects) As described above, the thin film capacitor formed of the bismuth layer compound thin film obtained by applying the film forming process of the present invention to the thin film formed by the solution coating method has uniform composition and characteristics. Shows a uniform distribution, has a small number of defect layers on the surface of each crystal grain, and has a dense film structure in which the non-ferroelectric phase dispersed in the grain boundary layer is also minimized, thereby exhibiting extremely excellent dielectric strength.

Further, as for suppression of evaporation deficiency of bismuth oxide and lead oxide compounds at the time of calcination by rapid heating, a uniform mixture is formed at the molecular level as described above.
A sufficient effect can be obtained without using an unnecessarily high process temperature. 4. (Easily deducible from Examples 1 and 2) The means for forming a thin film containing a precursor mixture composed of the metal organic compound as a main component is a mist deposition method by spraying a precursor solution. 2. A method of manufacturing a ferroelectric thin film capacitor as described in 1 or 2.

(Structure) The same raw material solution as the precursor solution used in the solution coating method is used, and this is sprayed under normal pressure or reduced pressure to form fine droplets, which are deposited on the substrate.
When a predetermined film thickness is reached, the film is taken out of the film forming tank and heated to evaporate and remove the remaining organic solvent and thermally decompose the organic metal compound to form a metal oxide thin film. By applying the manufacturing method of the present invention to the formed oxide thin film, a rapid heating process is performed at a crystallization temperature of the ferroelectric material or higher to form a ferroelectric thin film, or an uncrystallized component is added. A large amount of the original ferroelectric thin film is left and a firing process is performed at a temperature above the crystallization temperature of the ferroelectric material in a heating furnace to complete the crystallization reaction and form a ferroelectric thin film. After forming an upper electrode layer on the ferroelectric thin film and forming a capacitor structure by etching, reheating treatment is performed.

(Function) Since the same raw material solution as in the solution coating method is used, the reproducibility of the composition control of the solution and the thin film is good, and the mixed state of the elements is a uniform thin film at the same level as the solution coating method. can get.

In addition, the advantage of using the mist deposition method is that it is possible to prevent impurities from being mixed in by consistently performing the system from the supply of the raw material solution to the film formation in a closed system. The point is that it is possible to avoid the occurrence of coating film defects such as tampering. Further, by uniformly depositing from the vapor phase, it is possible to form a film on a stepped substrate surface with good step coverage.

(Effect) The bismuth layered compound thin film obtained by applying the film forming process of the present invention to the thin film formed by the mist deposition method shows a uniform distribution both in terms of composition and characteristics, and causes film defects. It is a high quality thin film. Furthermore, the thin film capacitor obtained by having a dense film structure with few defect layers on the surface of each crystal grain and minimizing the non-ferroelectric phase dispersed in the grain boundary layer exhibits extremely excellent withstand voltage. .

As for the effect of suppressing the evaporation deficiency of the compound that is easily vaporized during the calcination process by rapid heating, it is advantageous that the process temperature can be kept low as in the solution coating method. 5. (Corresponding to Examples 1 to 5) In the step of forming a metal oxide thin film by heating and oxidizing the thin film containing the precursor mixture of the metal organic compound as a main component, the treatment temperature is 500 ° C. or less, and the amorphous Forming a metal oxide thin film in a qualitative state;
4. A method of manufacturing a ferroelectric thin film capacitor as described in 4 above.

(Structure) According to the above contents. (Function) The precursor metal organic compound corresponding to the PZT or bismuth layered compound thin film has a thermal decomposition temperature in the range of 300 to 450 ° C. In the thermal decomposition reaction of the precursor metal organic compound, the organic portion dissociates with the metal atom and burns to generate carbon dioxide and water, which diffuses and desorbs in the gas phase or remains as free carbon in the film. At the same time, the metal atom becomes an oxide by the oxidation reaction. In order to obtain the desired crystalline thin film of the ferroelectric substance, it is sufficient to heat this to the crystallization temperature and grow the crystal, but if the thin film made of the precursor compound is heated at a stroke, it will be accompanied by the solvent and carbonaceous combustion. The shrinkage of the thin film volume is too large and many cracks occur, or the film itself peels off from the substrate. Further, the residual organic matter in the film interferes with the crystallization reaction, and the crystallization reaction does not proceed smoothly.

As a result, a thin film having a large porosity cannot be obtained, and the expected good characteristics cannot be obtained. Since the crystallization temperature of the target PZT is around 700 ° C and the crystallization temperature of the bismuth layer compound is around 800 ° C, the metal oxide is produced by setting the treatment temperature of this heating oxidation step to 500 ° C or less. However, crystallization of the ferroelectric does not occur and a film in an amorphous state is formed. The oxides of the respective constituent elements are uniformly mixed, and by applying a rapid heating calcination treatment according to the present invention to this, a large amount of heat is applied within an extremely short time to burn the residual organic matter all at once, and then to the outside of the film. The target ferroelectric thin film can be obtained by completely desorbing and easily generating fine crystal nuclei.

As described above, in each heat treatment step for forming the ferroelectric thin film, various volumes such as volume shrinkage due to solvent volatilization, volume shrinkage due to combustion and release of organic functional groups, volume shrinkage due to crystallization, etc. In consideration of changes, it is necessary to proceed in stages while preventing peeling and cracking of the thin film.
In particular, in the heating and oxidation process related to drying and oxidative decomposition, the deposition shrinks most, so this process is preferably performed in several steps in order from low temperature to high temperature over the range from the boiling point of the solution solvent to the decomposition temperature of the organic compound. .

(Effect) As described above, by keeping the temperature of the heat oxidation treatment of the precursor compound thin film at 500 ° C. or lower, the crystallization reaction of the original ferroelectric thin film and further the ferroelectric thin film in the next step. Can be rapidly progressed to form a ferroelectric thin film capacitor having excellent withstand voltage characteristics. 6. (Corresponding to Examples 1 to 5) The temperature rising rate of the rapid heating process is in the range of 1 to 200 ° C / sec, and the processing time is in the range of 5 to 300 sec. 5. A method of manufacturing a ferroelectric thin film capacitor as described in 5 above.

(Structure) According to the above contents. (Function) In order to generate fine crystal nuclei by the above-mentioned rapid temperature rising heating, a rapid temperature rise inside the thin film is required.
Mechanical tension and shear stress, thermal strain, and concentration caused inside the thin film heated at a temperature higher than the crystallization temperature due to abrupt temperature change are instantaneously caused to cause these physical and thermal fluctuations. It is considered that innumerable minute crystal nuclei are generated at the center. When the temperature rising rate is 1 ° C./sec or less, the temperature change is too gradual and almost no nucleation occurs.
Since 0 ° C./sec or more is an upper limit of the lamp heating device, it cannot be realized because the temperature control is performed with high accuracy.

It is considered that the generation of the initial crystal nuclei takes place within a very short time, for example, within 1 second, but in reality, it takes a longer time until the temperature of the entire substrate becomes stable.
The practically effective processing time range is 5 to 300 seconds. Heating for a longer time than this promotes the growth of the generated crystal nuclei, and the crystallization reaction proceeds too rapidly, resulting in a large variation in the grain size, and a uniform grain size distribution cannot be obtained. Most of the crystals taken in and crystallized make it difficult to grow crystals in the firing process.

(Effect) By performing the above-mentioned rapid heating, the crystal nuclei are efficiently generated, and the crystal nuclei are uniformly grown in the firing step, thereby showing a uniform distribution in terms of composition and characteristics. A high quality ferroelectric thin film with few film defects can be formed. By obtaining a dense film structure in which the number of defect layers on the surface of polycrystalline particles is small and the non-ferroelectric phase dispersed in the grain boundary layer is also minimized, a thin film capacitor having extremely excellent withstand voltage can be manufactured. 7. (Corresponding to Examples 1 to 5) The ferroelectric thin film capacitor according to any one of items 1 to 6, wherein the atmosphere component for performing the rapid temperature rising heat treatment on the metal oxide thin film contains oxygen of 20 vol% or more. Manufacturing method.

(Structure) According to the above contents. (Function) By carrying out the calcination step by the rapid heating for heating in an oxidizing atmosphere, preferably in an atmosphere containing oxygen of 20 vol% or more (air), residual carbonaceous matter remaining in the metal oxide thin film can be efficiently removed. It burns and vaporizes, and accelerates the oxidation reaction of metal atoms.

(Effect) By promoting the combustion and vaporization of carbonaceous matter in the film, it is possible to reduce the concentration of carbonaceous impurities that cause crystallization reaction inhibition, generation of lattice defects, and decrease in film density. it can. As a result, it is possible to form a high-quality ferroelectric thin film having a uniform distribution in terms of composition and characteristics and having few film defects. By obtaining a dense film structure in which the number of defect layers on the surface of each crystal grain is small and the non-ferroelectric phase dispersed in the grain boundary layer is also minimized, it is possible to manufacture a thin film capacitor having extremely excellent dielectric strength. 8. 8. The ferroelectric thin film formed by the rapid temperature rising heat treatment is a partially crystallized film, and is in a mixed state of an amorphous phase and a crystalline ferroelectric phase. Manufacturing method of ferroelectric thin film capacitor.

(Structure) According to the above contents. (Function) A large number of crystal nuclei are formed in the thin film by rapidly heating the metal oxide film. It is possible to control the size and density of crystal nuclei, the ratio of crystallized parts and amorphous parts, etc. by appropriately selecting the heating rate, holding temperature and holding time as heating conditions for rapid heating. is there. By forming fine crystal nuclei and amorphous parts in a mixed state in the calcination process, while gradually taking in each oxide molecule of the surrounding amorphous part in the subsequent firing process that takes a long time. Each crystal nucleus grows into crystal grains of uniform size with few defects.

(Effect) In the calcination process by rapid heating, only high-density formation of crystal nuclei is promoted to obtain a mixed state of a crystal phase and an amorphous phase, so that crystal grains of uniform size with few defects are obtained. It is possible to obtain a high-density ferroelectric thin film made of, and as a result, it is possible to manufacture a thin film capacitor having extremely excellent withstand voltage. 9. (Corresponding to Examples 1 to 5) The ferroelectric thin film according to any one of Items 1 to 8, wherein the temperature rising rate in the firing step is 100 ° C./minute or less and the treatment time is 5 minutes or more. Method of manufacturing capacitor.

(Structure) According to the above contents. (Function) The original ferroelectric thin film, which is a partially crystallized film formed in the rapid heating process, is baked for a relatively long time compared to the processing time, and the crystallization rate is selected by selecting the baking temperature. The crystal is gradually grown while controlling the temperature to form a homogeneous crystalline thin film. Although many crystal defects are contained in the crystal nuclei formed by the extremely short time temperature change and the constant temperature treatment by the rapid heating method, heating is performed at an extremely slow heating rate of 100 ° C / minute or less for 5 minutes. As described above, these defects are corrected and the defect density is reduced by slowly performing the heat treatment preferably for about 30 minutes to several hours.

The firing temperature is higher than or equal to the crystallization temperature of the intended ferroelectric material thin film, but in order to reduce the thermal damage that the integrated circuit formed on the semiconductor substrate is exposed to a high temperature treatment for a long time, the thermal damage is reduced. Also, it is preferable that the temperature is equal to or lower than the temperature for the rapid heating process.

(Effect) Temperature rising rate is 100 ° C./min or less, 5
By firing the original ferroelectric thin film for a treatment time of not less than a minute, a uniform grain size distribution with few crystal defects and a high-quality, high-characteristic dielectric strength ferroelectric substance based on the above-mentioned action are obtained. Thin film capacitors can be formed. 10. (Corresponding to Examples 1 to 5) Manufacturing of the ferroelectric thin film capacitor described in any one of items 1 to 9, wherein the rapid heating process is performed on a thin film having a film thickness of 0.05 to 1 μm. Method.

(Structure) According to the above contents. (Function) The thin film to be subjected to the calcination treatment according to the present invention preferably has a film thickness of 0.05 to 1 μm. 0.0
If the film thickness is less than 5 μm, the process of lamination becomes long, and it is too thin to form a continuous film, and film defects increase, so that a high quality thin film cannot be obtained. If the thickness of one layer exceeds 1 μm, the phenomenon of peeling from the substrate or cracking easily occurs due to shrinkage of the film volume during the drying and rapid heating process, and fine particles formed when the solvent evaporates. The pores do not collapse even when fired and tend to become a porous film. Further, if the film thickness exceeds 1 μm, an electric field effective for reversing the polarization of the ferroelectric substance cannot be applied at a driving voltage of 5 V or less, which is a normal semiconductor device.

(Effect) By limiting the film thickness, cracks,
It is possible to form a high-quality and highly-insulating ferroelectric thin film capacitor without peeling. 11. (Corresponding to Examples 1 to 5) By repeating the steps from the stacking of the thin films to the rapid temperature rising heat treatment a plurality of times, a multilayer film is formed to obtain a thin film having a predetermined film thickness. Item 10. A method for manufacturing a ferroelectric thin film capacitor according to Item 10.

(Structure) A precursor metal organic compound thin film is formed by using a solution coating method or a mist deposition method, and heating oxidation and rapid temperature rising heat treatment steps are repeated a plurality of times according to the film forming process of the present invention. Then, the ferroelectric thin film having a predetermined film thickness is obtained by multi-layering, and then the ferroelectric thin film capacitor is formed by the steps after the firing step.

(Function) As described above, in the drying and rapid heating process, the film volume is largely shrunk, so that the phenomenon of peeling from the substrate, the occurrence of cracking, and the pores formed at the time of solvent evaporation are shrunk even by firing. The problem that a porous film that is not crushed easily becomes more likely to occur as the target thin film becomes thicker. When a ferroelectric film with a thickness of more than 1 μm is required or 1 μm
If a dense thin film is required even if it is less than m, the thin film is multi-layered and rapid heating treatment is applied to each layer to eliminate excessive stress concentration due to shrinkage per layer. It is possible to suppress the occurrence of cracks, peeling of the film, and increase in the porosity of the film.

(Effect) By forming a thin film in multiple layers and applying it to the film forming process of the present invention, it becomes possible to easily form a film having a thickness of 1 μm or more. 12. 12. The method for manufacturing a ferroelectric thin film capacitor as described in 11 above, wherein the constituent element ratios of the layers forming the multilayer film are different.

(Structure) According to the above contents. (Function) The bismuth layered compound according to the present invention has bismuth oxide which is liable to be vaporized in its constituent elements, and may contain lead oxide or the like. PZT has an essential lead oxide as its constituent element. When the precursor film has a mixing ratio equal to the stoichiometric ratio of the target compound, crystal growth does not proceed completely when defects due to evaporation and desorption of a specific element occur during the subsequent heat treatment step, or the crystal defect density In some cases, the increase in the thickness and the thickness of the grain boundary layer impair the ferroelectricity inherent in the thin film, and the expected polarization characteristics cannot be obtained. In this case, a thin film of one layer or multiple layers having the same composition except that the specific element, bismuth or lead is excessively contained is laminated on a uniform thin film of one layer or multiple layers to form a thin film. A multilayer film having a concentration gradient of the specific element in the film thickness direction from the surface to the inside is heated and baked. When it is desired to realize different functional characteristics in the film thickness direction, thin films having completely different compositions may be laminated.

(Effect) According to the present invention, the intended thin film is formed in multiple layers by changing the composition to correct the composition defect near the surface of the thin film, which results from the conventional defect of evaporation deficiency of lead, bismuth and the like. It is possible to prevent deterioration of polarization performance due to composition deviation from stoichiometric composition ratio, reduction of coercive electric field due to residual excess bismuth or lead in the film, deterioration of film quality due to inhomogeneity of the composition and occurrence of electrical short circuit. Further, it is possible to improve the functional characteristics by arranging the composition of the ferroelectric thin film having different characteristics in each layer. 13. (Corresponding to Examples 1 to 4) The method for manufacturing a ferroelectric thin film capacitor according to any one of items 1 to 12, wherein the ferroelectric thin film is a bismuth layered compound represented by the general formula (1). .

(Bi ₂ O ₂ ) ²⁺ (A _m−1 B _m O _{3m + 1} ) ²⁻ (1) A = Bi, Pb, Ba, Sr, Ca, Na, K, Cd A combination of one or more elements at any ratio.

B = Ti, Nb, Ta, W, Mo, Fe,
A combination of one or more elements selected from Co and Cr in an arbitrary ratio. A natural number of m = 1 to 5.

(Structure) According to the above contents. (Function) The bismuth layered compound ferroelectric material according to the present invention has a layered crystal structure composed of repeating units formed by regularly overlapping two-dimensionally spread bismuth oxide layers and ferroelectric perovskite structures. Many bismuth layered compounds have higher durability against polarization inversion fatigue than lead-containing composite oxides.

(Effect) By forming a bismuth layered compound by the film forming process of the present invention, it is possible to provide a ferroelectric thin film capacitor having excellent polarization inversion fatigue characteristics and high withstand voltage. 14. (Corresponding to Examples 1 to 4) The manufacture of the ferroelectric thin film capacitor according to the above item 13, wherein the bismuth layer compound is strontium bismuth tantalate niobate represented by the general formula (1 '). Method.

SrBi ₂ (Ta _1-x Nb _x ) ₂ O ₉ (1 ′) 0 ≦ x ≦ 1 (Structure) According to the claims.

(Function) Among the bismuth layered compound ferroelectrics relating to the present invention, strontium bismuth niobate titanate: SrBi ₂ (Ta _1-x Nb _x ) ₂ O ₉ (0 ≦ x
≦ 1) is particularly excellent in fatigue of polarization inversion, and even if the polarization inversion is repeated 10 ¹² times or more, the inversion charge amount is not deteriorated, and a very large number of polarization inversions are accompanied by writing, reading, and erasing of recorded information. Most suitable for required semiconductor memory device applications. Tantalum and niobium have the same valences and almost the same atomic radii, and can be arbitrarily substituted in the crystal lattice. By selecting the Ta / Nb ratio, the remanent polarization amount and the polarization reversal threshold, The electric field can be controlled. Therefore, a device design with a high degree of freedom becomes possible.

(Effect) S which is particularly excellent in polarization reversal fatigue characteristics
It is possible to provide a ferroelectric thin film capacitor suitable for semiconductor memory applications by improving the dielectric strength of the rBi ₂ (Ta _1-x Nb _x ) ₂ O ₉ thin film. 15. (Corresponding to Examples 1 to 4) The method for manufacturing a ferroelectric thin film capacitor according to the above item 14, wherein the treatment temperature of the rapid heating is 800 ° C. or higher.

(Structure) According to the above contents. (Function) The crystallization temperature of the SrBi ₂ Ta ₂ O ₉ thin film is 80
The raw ferroelectric thin film of the material can be easily formed by performing a rapid temperature rising heating calcination treatment at a temperature of about 0 ° C. or higher.

(Effect) By performing the rapid temperature rising heat treatment of the present invention at 800 ° C. or higher, Sr excellent in withstand voltage is obtained.
It is possible to obtain a Bi ₂ Ta ₂ O ₉ thin film and provide a ferroelectric thin film capacitor having fatigue resistance and high withstand voltage. 16. (Corresponding to Examples 1, 3 and 4) The method for producing a ferroelectric thin film capacitor as described in the above items 14 and 15, wherein the processing temperature in the firing step is 800 ° C. or higher.

(Structure) According to the above contents. (Function) The crystallization temperature of the SrBi ₂ Ta ₂ O ₉ thin film is 80
By firing at a temperature in the vicinity of 0 ° C. and above this temperature, a ferroelectric thin film of a material having a uniform grain size distribution and a high film density can be easily formed.

(Effect) By performing the firing treatment of the present invention at 800 ° C. or higher, SrBi ₂ T excellent in withstand voltage is obtained.
It is possible to obtain an a ₂ O ₉ thin film and provide a ferroelectric thin film capacitor having fatigue resistance and high withstand voltage. 17． (Corresponding to Example 5) The first to twelfth features that the ferroelectric thin film is PZT represented by the general formula (2) or a modified form thereof.
6. A method for manufacturing a ferroelectric thin film capacitor as described in the item.

(Pb _{1-x + a} A _x ) (Zr _1-yz Ti _y B _z ) O ₃ + βMeO (2) a = 0 to 0.2 A = Ca, Sr, Ba, Th, La, Y, Sm, Dy,
A combination of one or more elements selected from Ce, Bi, and Sb in an arbitrary ratio.

X = 0 to 0.3 y = 0 to 0.9 B = Hf, Sn, Nb, Ta, W, Mo Any combination of one or more elements selected from Mo.

Z = 0 to 0.3 β = 0 to 0.05 Me = La, Y, Sm, Dy, Ce, Bi, Sb, N
b, Ta, W, Mo, Cr, Co, Ni, Fe, Cu,
A combination of one or more elements selected from Si, Ge, U and Sc in an arbitrary ratio.

(Structure) According to the above contents. (Function) The PZT-based ferroelectric material according to the present invention has a large polarization performance and can take out a large current even if the capacitor area is made small. Therefore, the storage capacity can be increased and the cell area can be made small in memory applications. It is advantageous to

(Effect) By forming a lead-containing complex oxide ferroelectric thin film by the film forming process of the present invention,
A ferroelectric thin film capacitor having excellent polarization inversion fatigue characteristics and high withstand voltage can be provided. 18. (Corresponding to Example 5) The method for producing a ferroelectric thin film capacitor as described in the above item 17, wherein the treatment temperature of the rapid heating is 700 ° C. or higher.

(Structure) According to the above contents. (Function) The crystallization temperature of the PZT thin film is around 700 ° C., and the raw ferroelectric thin film of the material can be easily formed by performing the rapid temperature rising calcination treatment at a temperature higher than this.

(Effect) PZT excellent in dielectric strength is obtained by performing the rapid temperature rising heat treatment of the present invention at 700 ° C. or higher.
A thin film can be obtained and a ferroelectric thin film capacitor having fatigue resistance and high withstand voltage can be provided. 19. (Corresponding to Example 5) The method for manufacturing a ferroelectric thin film capacitor as described in the above items 17 and 18, wherein the treatment temperature in the firing step is 700 ° C or higher.

(Structure) According to the above contents. (Function) The crystallization temperature of the PZT thin film is around 700 ° C., and by firing at a temperature higher than this, a ferroelectric thin film of the material having a uniform particle size distribution and a high film density can be easily formed. be able to.

(Effect) By performing the firing treatment of the present invention at 700 ° C. or higher, a PZT thin film having excellent withstand voltage can be obtained, and a fatigue-resistant and withstand-voltage ferroelectric thin film capacitor can be provided.

[0103]

As described in detail above, according to the present invention, it is possible to improve the withstand voltage characteristics of the thin films of the lead-containing complex oxide ferroelectric and the bismuth layered compound by the conventional process, and to apply them to actual devices. A method of manufacturing a ferroelectric thin film capacitor capable of forming a thin film of a compound can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a comparison between hysteresis curves of Comparative Example 1 and Examples 1 to 4.

FIG. 2 is an IV characteristic diagram according to Comparative Example 1.

FIG. 3 is an IV characteristic diagram according to the first embodiment.

FIG. 4 is an IV characteristic diagram according to the second embodiment.

FIG. 5 is an IV characteristic diagram according to the third embodiment.

FIG. 6 is an IV characteristic diagram according to the fourth embodiment.

7 is an IV characteristic diagram of Comparative Example 2 and Example 5. FIG.

Front page continued (72) Inventor Hitoshi Watanabe 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd. (72) Hiroyuki Yumori 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd. (72) Inventor Takashi Mihara 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd. (72) Inventor Takehiro Takahashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Inside Optical Industry Co., Ltd. (72) Inventor Kaoru 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industry Co., Ltd.

Claims (3)

[Claims] 1. A step of forming a lower electrode layer made of an electrically conductive metal thin film or oxide thin film on a semiconductor substrate,
A step of forming on the lower electrode layer a thin film containing a precursor mixture composed of an organic compound of a plurality of metals corresponding to the constituent elements of the target ferroelectric material as a main component, and heating and oxidizing the thin film to form a metal oxide thin film. Forming the ferroelectric thin film, subjecting the formed ferroelectric thin film to at least one rapid heating treatment, and forming an electrically conductive metal thin film or oxide thin film on the formed ferroelectric thin film. Ferroelectric comprising a step of forming an electrode layer, a step of etching a top electrode layer, a ferroelectric thin film, a bottom electrode layer, etc. into a predetermined shape to form a capacitor structure, and a step of subjecting this to reheating treatment. A method of manufacturing a thin film body capacitor, wherein the rapid heating treatment temperature is equal to or higher than the crystallization temperature of the target ferroelectric material. 2. The method of manufacturing a ferroelectric thin film capacitor according to claim 1, wherein the ferroelectric thin film is a bismuth layered compound represented by the general formula (1). (Bi ₂ O ₂ ) ²⁺ (A _m-1 B _m O _{3m + 1} ) ^2- (1) A = one selected from Bi, Pb, Ba, Sr, Ca, Na, K, and Cd, or Combination of multiple elements at any ratio. B = Ti, Nb, Ta, W, Mo,
A combination of one or more elements selected from Fe, Co and Cr in an arbitrary ratio. A natural number of m = 1 to 5. 3. The method for manufacturing a ferroelectric thin film capacitor according to claim 1, wherein the ferroelectric thin film is PZT represented by the general formula (2) or a modified form thereof. _{(Pb1-x + a A x} ) (Zr 1-yz Ti y B z) O 3 + βMeO (2) a = 0~0.2 A = Ca, Sr, Ba, Th, La, Y, Sm, Dy,
A combination of one or more elements selected from Ce, Bi, and Sb in an arbitrary ratio. x = 0 to 0.3 y = 0 to 0.9 B = A combination of one or more elements selected from Hf, Sn, Nb, Ta, W, and Mo at an arbitrary ratio. z = 0-0.3 β = 0-0.05 Me = La, Y, Sm, Dy, Ce, Bi, Sb, N
b, Ta, W, Mo, Cr, Co, Ni, Fe, Cu,
A combination of one or more elements selected from Si, Ge, U and Sc in an arbitrary ratio.