JP3275448B2 - Preparation method of lead-based ferroelectric thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to lead titanate (PT),
A lead-based alloy containing lead and titanium and having a perovskite crystal structure, such as lead titanium zirconate (PZT), lanthanum-containing lead zirconate titanium (PLZT), or lead titanium zirconate containing another third component. The present invention relates to a dielectric thin film and a method for manufacturing the same.

More specifically, a lead-based ferroelectric thin film having excellent homogeneity, in which crystal grains are fine and uniform, so that properties and surface properties (surface morphology) are homogenized throughout the thin film, and It relates to a manufacturing method. The present invention also relates to a substrate used for producing the lead-based ferroelectric thin film.

[0003]

2. Description of the Related Art Lead-based ferroelectric thin films can perform various functions such as memory elements, capacitor films, optical waveguides, and optical elements due to their electrical and optical properties, and are indispensable for device structures. It is becoming a component that cannot be done. As the essential characteristics of the lead-based ferroelectric thin film for this purpose, it is essential for the structure of the micro device that the surface is flat and various characteristics are uniform throughout the thin film.

[0004] Lead-based ferroelectric thin films are formed by CVD (chemical vapor deposition).
Using a suitable thin film forming method such as sputtering, sol-gel method, etc., a film is formed on a substrate so as to have a desired composition, and during this film formation (in the case of CVD or sputtering)
Alternatively, it is generally produced by heating a substrate after film formation (in the case of a sol-gel method) to crystallize a thin film. Crystallization by heating the substrate is necessary for completely transforming the thin film into a perovskite-type crystal structure, and without this heating, it is not possible to exhibit predetermined ferroelectric properties.

[0005]

During the heating of the substrate,
Lead oxide (PbO) with a relatively low melting point volatilizes from the thin film,
It is known that it tends to diffuse into the underlying substrate, which causes lead deficiency in the thin film after crystallization by heating. In order to avoid this lead deficiency, conventionally, an excessive Pb component was added to form a film.

However, in the symptomatic treatment of adding an excessive Pb component to avoid lead deficiency, it is inevitable that a local lead excess region or a lead deficiency region occurs. For this reason, crystallization is locally inhibited, and incompletely crystallized portions coexist, so that irregularities are formed on the surface, or portions with different characteristics due to differences in crystal system and crystallinity are formed, and Deterioration of properties and non-uniformity of film characteristics were caused. In addition, the conventional lead-based ferroelectric thin film generally has a large average crystal grain size of 3,000 mm or more, and also in this respect, the uniformity of the thin film surface is poor.

An object of the present invention is to provide a method for producing a lead-based ferroelectric thin film having fine and uniform crystals, a flat surface, excellent surface properties, uniform properties over the entire thin film, and excellent homogeneity. It is to be.

[0008]

In order to achieve the above object, it is necessary to reduce Pb in a thin film by heating during or after film formation, which is a cause of deterioration of surface properties and unevenness of film characteristics.
Preventing O loss is the fundamental solution. The present inventors have conducted research from this point of view.As a result, if a substance containing Ti as a crystal nucleus is present on the surface of the substrate before film formation, diffusion of PbO 2 during heating for crystallization will occur. It can prevent to some extent, and crystallizes into the target perovskite type structure before volatilization occurs, forming a lead-based ferroelectric thin film composed of fine crystals with excellent surface properties without unevenness, uniform properties throughout, and fine crystals. It was found that it can be produced.

Here, the present invention provides a method for producing a lead-based ferroelectric thin film in which a film is formed on a substrate by supplying a raw material from the outside, and the substrate is heated during or after the film formation for thin film crystallization. Forming a Ti-containing layer having a thickness of 30 mm or less that does not contain Pb and contains Ti as a metal or oxide on a substrate surface, and then deposits the film, characterized in that: The method is summarized.

[0010] In another aspect , the invention provides a Pt layer on top,
Raw material supply from outside onto a multilayer substrate with a Ti layer underneath
During or after film formation.
Method for producing a lead-based ferroelectric thin film by heating the substrate
Then, the multilayer substrate is baked before film formation to spread Ti in the Pt layer.
Ti or TiO _x on the surface of Pt layer
Method for producing lead-based ferroelectric thin film
It is. According to the present invention, there is further provided a substrate for producing a lead-based ferroelectric thin film, which has a Ti-containing layer having a thickness of 30 mm or less that does not contain Pb and contains Ti as a metal or oxide. You.

In the present invention, "substrate" means an object on which a lead-based ferroelectric thin film is formed. The substrate may have a single structure (single-layer type) or a multilayer structure in which various layers are formed on the substrate. The type of the substrate is not particularly limited, and is selected according to the use of the ferroelectric thin film.

For example, when the application is a non-volatile RAM (random access memory) utilizing spontaneous polarization of a ferroelectric, a silica (SiO _{2) is used} as a buffer layer on a silicon substrate as a substrate on which a ferroelectric thin film is formed. ) Layer and a Ti layer, on which a platinum electrode layer is further formed, Pt / Ti /
A multilayer structure having a structure of SiO ₂ / Si is exemplified. In some cases, a Ta layer is further interposed between the SiO ₂ layer and the Ti layer.

Conventionally, a lead-based ferroelectric thin film has been manufactured by directly supplying a raw material from the outside onto the platinum electrode layer of this substrate by a method such as CVD, sputtering, or a sol-gel method.

According to the present invention, a Ti-containing layer is formed on the surface of a substrate before film formation in order to function as a crystal nucleus. Here, the substrate surface means the surface of the substrate on which the lead-based ferroelectric thin film is to be prepared (the surface on the film formation side).

The composition of the Ti-containing layer formed on the substrate surface is not particularly limited as long as it does not contain Pb and contains Ti as titanium metal or titanium oxide. The titanium oxide may be titanium oxide or a composite oxide containing titanium oxide. The composition of the Ti-containing layer is Ti, TiO
_x (x is 1 to 6), SrTiO ₃ , BaTiO ₃ , (Ba _y Sr _1-y ) TiO ₃ (y is 1 to 9) and the like are exemplified.

The method for forming the Ti-containing layer is not particularly limited, and any method capable of forming a Ti or Ti oxide layer with a thickness of several mm or more can be adopted. The upper limit of the thickness of the Ti-containing layer is not particularly limited, but generally 30 ° or less is sufficient. Too thick is not only uneconomical, but also
TiO _x is not preferred because it may change the characteristics of the ferroelectric thin film. However, a high dielectric constant material in which the Ti-containing layer itself has the same crystal structure as the lead-based ferroelectric seat (e.g., Sr
In the case of TiO ₃ or a ferroelectric material, even if the thickness of the Ti-containing layer is large (eg, several hundred square meters), there is little effect on the dielectric properties. Since the Ti-containing layer serves to act as a crystal nucleus, it is not necessary to completely cover the substrate, and the Ti-containing layer may be discontinuous as long as it is uniformly distributed on the substrate surface.

The formation of the Ti-containing layer on the substrate surface is performed, for example, by
It can be performed by the following method. Pt / Ti such as Pt / Ti / SiO ₂ / Si and Pt / Ti / Ta / SiO ₂ / Si
A substrate with a multilayer structure having a layer on the surface side, which is baked to diffuse Ti into the Pt layer and allow Ti or TiO _x to appear on the surface of the Pt layer. The firing temperature is preferably in the range of 550 to 650 ° C.
The firing time varies depending on the temperature, but is about 15 to 60 minutes. Since the specific firing conditions vary depending on the structure of the substrate, the optimum conditions may be determined by repeating experiments of firing → thin film formation → heat treatment. If calcination is performed in air (or in other oxidizing atmospheres), TiO _x will appear on the surface, and if calcination is performed in a reducing or inert atmosphere, Ti will appear on the surface.

A device in which a Ti layer is formed on a substrate surface by a vacuum evaporation method, an electron beam evaporation method, or the like. A titanium oxide layer formed on a substrate surface by a CVD method, a sputtering method, a sol-gel method, or the like. This titanium oxide layer may be amorphous or crystallized by heating.

The formation of the Ti-containing layer by the above method can be carried out by any known method. However, as described above, since the Ti-containing layer may be extremely thin, the conditions are selected as such. For example, the processing time may be shortened in vapor deposition, CVD, and sputtering, and the concentration of the solution used for coating may be low in the sol-gel method.

After the Ti-containing layer is thus formed on the substrate, a desired lead-based ferroelectric thin film is formed on the Ti-containing layer by supplying a raw material from the outside by a known method.
The lead-based ferroelectric thin film is composed of a composite oxide having a perovskite structure containing Pb and Ti, and specific examples thereof include lead titanate (PT), lead titanium zirconate (PZT), and lanthanum-containing lead titanium zirconate. (PLZT), and lead titanium zirconate containing other third components. These thin films can be formed by a known film forming method such as a sol-gel method, a CVD method, and a sputtering method.

The production of a lead-based ferroelectric thin film by the sol-gel method can be performed, for example, according to the method described in Japanese Patent Application Laid-Open No. Sho 60-236404. That is, a solution in which a hydrolyzable or thermally decomposable organometallic compound of each metal is dissolved in an organic solvent is prepared, and this solution is applied on the Ti-containing layer of the substrate, and then heated (usually 500 ° C. or lower). The solvent is removed and the organometallic compound is decomposed to be converted into a composite oxide. This heating may be performed in two stages: low-temperature heating for removing the solvent and high-temperature heating for decomposing the organic compound. If necessary, coating and heating are repeated until a desired film thickness is obtained, thereby completing the film formation.

As the organometallic compound as a raw material, a metal alkoxide, a metal carboxylate and the like can be used. Preferred examples of the raw material include carboxylic acid salts such as acetates (lead acetate and lanthanum acetate) and alkoxides such as diisopropoxy lead. Examples of the titanium compound include alkoxides such as tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, and dimethoxydiisopropoxytitanium. The source of zirconium is preferably an alkoxide similar to the titanium compound. The metal alkoxide may be used as it is, or its partial hydrolyzate may be used to accelerate the decomposition.

The CVD method is a method in which a volatile raw material is vaporized and reacted in a reaction furnace by heat, plasma, light or the like to form a film on a substrate. As a raw material used for producing a lead-based ferroelectric thin film by the CVD method, a volatile inorganic compound (eg,
Chloride) and organic compounds (eg, organometallic complexes, metal alkoxides, carboxylate, etc.) can be used. Usable organometallic complexes include acetylacetone (AcAc), heptafluorobutanoyl pivaloylmethane
(FOD), dipivaloylmethane (DPM), trifluoroacetylacetone (TFA), and other complexes having a β-diketone as a ligand.

In the production of a lead-based ferroelectric thin film by sputtering, high-speed particles (eg, oxygen) are generally applied to a target material consisting of a sintered body having the same composition as the thin film to be formed (lead may be added in some cases). (Argon gas containing). It is also possible to use a powder or to use each metal source separately.

As another method, a laser ablation method can be employed for forming the lead-based ferroelectric thin film of the present invention. This method uses a target material similar to the sputtering
This is a method in which laser light such as F 2, KrF 2, or YAG is irradiated with a pulse to adhere the evaporated active particles to the substrate.

As described above, lead and other raw material metals are supplied to the substrate from the outside to form a thin film of a composite metal oxide having a desired composition containing lead. Since the obtained thin film is completely or partially amorphous as it is, the thin film is heated and crystallized at a temperature higher than the crystallization temperature of the composite oxide during or after film formation. Unless the thin film is completely transformed into a crystal having a perovskite structure by this heating, a device cannot exhibit a desired function utilizing spontaneous polarization of a ferroelectric substance. This heating (hereinafter also referred to as heat treatment) varies depending on the ferroelectric composition, but is generally about
Performed at temperatures above 450 ° C. Specific heat treatment temperature is 450-700 ° C for PT, 500-750 ° C for PZT,
In PLZT, the temperature is about 600 to 800 ° C.

In a method of forming a film while heating the substrate, such as CVD, sputtering, or laser ablation, crystallization is achieved by heating during the film formation without performing a separate heat treatment step after the film formation. can do. However, when the crystallization is insufficient, a further heat treatment may be performed after the film formation to complete the crystallization. Since the film forming process (coating, drying, and calcining) by the sol-gel method is generally performed at a temperature lower than the crystallization temperature, it is necessary to heat-treat the film at a temperature higher than the crystallization temperature after film formation to crystallize the thin film.

As described above, in the preparation of a conventional lead-based ferroelectric thin film, lead deficiency occurs during this heating or heat treatment. This is because the melting points of TiO ₂ and ZrO ₂ are very high, 1640 ° C and 2700 ° C, respectively, while the melting point of PbO is 888 ° C.
And near the heat treatment temperature, part of PbO volatilizes during heat treatment,
Alternatively, it is to diffuse into the substrate. In addition, since the crystallization does not occur uniformly, irregularities occur in the thin film during the heat treatment, and very coarse crystals (average particle diameter of at least 3000 mm, usually about 1 to 2 μm) are generated.

In the present invention, since the Ti-containing layer formed on the surface before film formation functions as a crystal nucleus, crystallization is greatly accelerated, and crystallization proceeds before lead volatilization and diffusion become remarkable. Can be done. As a result, lead loss is remarkably suppressed, so that it is not necessary to allow lead to be excessively present in the film forming material in anticipation of lead loss as in the conventional method.

Furthermore, in the method of the present invention, the Ti-containing layer becomes a crystal nucleus and crystallization proceeds rapidly, so that the surface properties of the ferroelectric thin film obtained after the heat treatment are very good.
Specifically, the surface is flat and has no irregularities, and the crystal grains are very fine and uniform with an average particle diameter of 1000 ° or less.

[0031]

EXAMPLE 1 A Pt / Ti / SiO ₂ / Si type multilayer substrate was placed in a firing furnace in air for 60 hours.
It was baked at 0 ° C. for 30 minutes to diffuse Ti into the Pt layer (platinum electrode layer) to form a TiO _x layer on its surface. There was no visible change in the appearance of the Pt layer surface of the substrate due to the firing. FIG. 2 shows a scanning electron micrograph of the surface of the Pt layer of the fired substrate.
FIG. 3A shows the result of the elemental analysis (Auger electron spectroscopy). As can be seen from this figure, Ti and oxygen were detected together with Pt, and it was found that TiO _x was discontinuously deposited on the surface. Although carbon was also detected, this was detected as an impurity at the time of measurement.

On the surface of the Pt layer of the substrate fired in this way,
A thin film of lead titanium zirconate (PZT) was formed as a lead-based ferroelectric thin film by a sol-gel method according to the following procedure. Dissolve 11.65 g of lead acetate trihydrate in 2-methoxyethanol,
After removing water by azeotropic distillation with a solvent, 4.19 g of tetraisopropoxytitanium and 6.12 g of tetra-t-butoxyzirconium were added, the mixture was refluxed, and 9.11 g of acetylacetone (stabilizer) was further added, followed by sufficient stirring. Then water 1.6
Add 6 g, and finally add 100 parts with 2-methoxyethanol.
g and a solution having a concentration of 10% by weight in terms of oxide. The atomic ratio of Ti / Zr in this solution was 52/48.

This organic metal compound solution was applied to the above substrate at 3,000 rpm using a spin coater, dried at 150 ° C. for 10 minutes to remove the solvent, and then calcined at 400 ° C. for 30 minutes to remove the organic compound. Disassembled. This coating, drying and calcining are performed in 5
By repeating the process twice to form a film with a thickness of 0.2 μm, finally, the entire substrate is heat-treated at 600 ° C. for 1 hour to crystallize.
A thin film of PZT (52/48) was obtained.

FIG. 2B shows an electron micrograph of the surface of the obtained PZT thin film. 1 (a) and 1 (b) show electron micrographs at further increased magnifications. As can be seen from these electron micrographs, the surface was uniform throughout and the size of the crystal grains (average particle size) was about 100 mm. Also, from the result of X-ray diffraction, this PZT thin film
It was confirmed that the ferroelectric phase was composed of a single phase of perovskite.

Comparative Example 1 The same Pt / Ti / SiO ₂ / Si type multi-layer substrate as used in Example 1 was applied to the surface of the Pt layer by the sol-gel method by the same operation as in Example 1 without firing. After performing film formation and heat treatment, PZ
A thin film of T (52/48) was prepared. The conditions for film formation and heat treatment were exactly the same as in Example 1.

FIG. 4A shows an electron micrograph of the surface of the Pt layer of the unfired substrate used, and FIG. 4B shows an electron micrograph of the surface of the obtained PZT thin film. The substrate surface before film formation had a flat surface. The surface of the prepared PZT thin film had a surface as shown in FIG. 4 (b) when viewed from above. However, this was because the compositional deviation occurred due to volatilization or diffusion of PbO, so that different parts of the crystal system were It is presumed that it was formed. Further, when the size of the crystal grains was determined from a further enlarged electron micrograph, the average particle size was about 5000 °. From the result of X-ray diffraction, this P
In the ZT thin film, two phases, a perovskite phase and a pyrochlore phase, which are ferroelectric phases, were confirmed.

Example 2 The same Pt / Ti / SiO ₂ / Si type multi-layer substrate as used in Example 1 was applied to the surface of the Pt layer by electron beam evaporation to a degree of vacuum of 1 × 10
Under conditions of ^-6 Torr, acceleration voltage of 10 kV, and emission current of 70 mA, an extremely thin Ti film was formed with a deposition time of 10 seconds. The thickness of this Ti film is estimated to be about 20 °.

On the Ti film of this substrate, a PZT film was formed by a sol-gel method in the same manner as described in Example 1.
After the film formation, a heat treatment was performed at 700 ° C. for 1 hour to crystallize, thereby obtaining a PZT (52/48) thin film. This PZT thin film was composed of a single phase of perovskite, which is a ferroelectric phase, as a result of X-ray diffraction. The surface properties were uniform by observation of the surface with an electron microscope, and the average grain size of crystal grains was about 200 mm. .

Example 3 On the surface of a Pt layer of the same Pt / Ti / SiO ₂ / Si type multilayer substrate used in Example 1, a TiO ₂ film was formed by a sol-gel method. The coating solution used was 0.36 g of tetraisopropoxy titanium
Was dissolved in 99.64 g of 2-methoxyethanol to obtain a 0.1% by weight oxide solution. This solution was applied on the Pt layer of the above substrate at 3000 rpm by a spin coater, and the coating film was dried at 150 ° C. for 10 minutes.
After calcining at 400 ° C. for 30 minutes, a heat treatment was performed at 600 ° C. for 15 minutes to form a TiO ₂ film. The thickness of this film is estimated to be several Å.

On the TiO ₂ film of the substrate thus formed, a PZT film was formed by a sol-gel method in the same manner as described in Example 1, and after the film formation, a heat treatment was performed at 600 ° C. for 1 hour. By crystallization, a PZT (52/48) thin film was obtained. The surface of this thin film had no irregularities, the surface properties were uniform, and the average grain size of the crystal grains was about 100 mm. From the results of X-ray diffraction, it was confirmed that this PZT thin film was composed of a single phase of perovskite, which is a ferroelectric phase.

Comparative Example 2 An SrTiO ₃ film was formed on the Pt layer surface of the same Pt / Ti / SiO ₂ / Si type multilayer substrate used in Example 1 by a sol-gel method.
The coating solution used was tetraisopropoxy titanium 7.74
g of strontium ethoxide and 4.84 g of strontium ethoxide were dissolved in 87.42 g of 2-methoxyethanol to obtain a solution having a concentration of 5.0% by weight in terms of oxide. This solution was applied on the Pt layer of the substrate at 3000 rpm by a spin coater, the coating film was dried at 150 ° C. for 10 minutes, calcined at 400 ° C., and heat-treated at 700 ° C. for 30 minutes to obtain SrTiO ₃ A film was formed. The thickness of this film is estimated to be about 500 mm.

On the SrTiO ₃ film on the substrate thus formed, a PZT film was formed by a sol-gel method in the same manner as described in Example 1, and after the film formation, heat treatment was performed at 600 ° C. for 1 hour. By crystallization, a PZT (52/48) thin film was obtained. This PZT thin film was composed of a single phase of perovskite, which is a ferroelectric phase, as a result of X-ray diffraction. The surface properties were uniform by observation of the surface with an electron microscope, and the average grain size of the crystal grains was about 100 mm. .

Comparative Example 3 A (Ba _0.5 Sr _0.5 ) TiO ₃ film was formed on the Pt layer surface of the same Pt / Ti / SiO ₂ / Si type multilayer substrate used in Example 1 by a sol-gel method. The coating solution used was 2-methoxyethanol 87.82 g of tetraisopropoxy titanium, 2.13 g of strontium ethoxide and 3.06 g of barium ethoxide.
Prepared by dissolving in 99 g, converted to oxide 5.
The solution had a concentration of 0% by weight. After applying this solution on the Pt layer of the above substrate at 3000 rpm by a spin coater, the coating film was dried at 150 ° C. for 10 minutes, calcined at 400 ° C. for 30 minutes, and then heat-treated at 700 ° C. for 30 minutes, A (Ba _0.5 Sr _0.5 ) TiO ₃ film was formed. The thickness of this film is estimated to be about 500 mm.

The substrate (Ba _0.5 Sr
_0.5 ) A PZT film is formed on the TiO ₃ film by a sol-gel method in the same manner as described in Example 1, and after the film is formed, a heat treatment is performed at 700 ° C. for 1 hour to crystallize the PZT film.
A thin film of (52/48) was obtained. The PZT thin film was composed of a single phase of perovskite, which is a ferroelectric phase, as a result of X-ray diffraction. The surface properties were uniform by observation of the surface with an electron microscope, and the average grain size of the crystal grains was about 300 mm. .

Example 4 A Pt / Ti / SiO ₂ / Si type multilayer substrate was fired (600 ° C. × 30 minutes) in the same manner as described in Example 1 to diffuse Ti into the Pt layer. Then, a TiO _x layer appeared on the surface of the Pt layer.
A lead-based ferroelectric thin film was formed by sputtering on the Pt layer of the fired substrate.

The target material for sputtering is PZT.
Was used. The composition ratio of Zr and Ti in this sintered body was 52
/ 48 and contained a 15 mol% excess of PbO 2. The film was formed by rf sputtering under the following conditions.

Plate voltage 2.6 kV Input 1.6 W / cm ² Sputter gas Ar / O ₂ (90/10) Gas pressure 5 × 10 ⁻³ Torr Substrate temperature 600 ° C. Film formation rate 50-100 μm / min Since the film was formed while heating to 600 ° C., PZT crystallized during the film formation. Therefore, the obtained P
No heat treatment of the ZT thin film was performed. According to the result of X-ray diffraction, this PZT thin film was obtained as a single phase of perovskite, which is a ferroelectric phase, and from observation of the surface with a scanning electron microscope, the entire surface was uniform and the average grain size of the crystal grains was about 200 Å.

Example 5 A multilayer substrate of Pt / Ti / SiO ₂ / Si type was fired (600 ° C. × 30 minutes) in the same manner as described in Example 1 to diffuse Ti into the Pt layer. Then, a TiO _x layer appeared on the surface of the Pt layer.
A lead-based ferroelectric (PZT) thin film was formed on the baked Pt layer by MOCVD.

The raw material used was lead dipivaloyl methanate
100-200 sccm (135 ° C.), tetra-t-butoxyzirconium 50-100 sccm (30 ° C.), tetraisopropoxytitanium 50-100 sccm (30 ° C.), and oxygen 700 sccm. The carrier was evaporated at the temperature in parentheses. The heating temperature of the substrate was 600 ° C., the pressure was 1 to 2 Torr, and the deposition rate was 5 to 20 nm / min.

Also in this method, the film was formed while the substrate was heated to 600 ° C., so that PZT crystallized during the film formation. Therefore,
The heat treatment of the obtained PZT thin film was not performed. According to the result of X-ray diffraction, this PZT thin film was obtained as a single phase of perovskite, which is a ferroelectric phase, and from observation of the surface with a scanning electron microscope, the entire surface was uniform and the average grain size of the crystal grains was about It was 100Å.

[0051]

As described above, according to the present invention, a Ti-containing layer acting as a crystal nucleus is deposited on the surface of a substrate, and then a lead-based ferroelectric substance is formed thereon by a sol-gel method as in the prior art. , Formed by sputtering, CVD, etc.
Crystallization by heat treatment prevents the deterioration of surface properties (formation of irregularities) during heat treatment, which has been recognized by the conventional method, and has a very fine and uniform crystal grain with an average particle diameter of 1000 mm or less. A thin film can be produced. As a result, the size of the crystal grains sufficiently corresponds to the device size, the characteristics as a ferroelectric are homogenized throughout the thin film, and the reliability of the device when applied to a micro device is improved.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are scanning electron micrographs at different magnifications showing the crystal structure of the surface of a PZT thin film produced in an example of the present invention.

FIG. 2 (a) shows a crystal structure of one example of a substrate used in an embodiment of the present invention, in which a Pt / Ti / SiO ₂ / Si type substrate is fired to deposit a TiO _x layer on the surface. FIG. 2 (b) is a scanning electron micrograph showing the PZ of the example fabricated using this substrate.
5 is a scanning electron micrograph showing the crystal structure of the surface of a T thin film.

Figure 3, TiO _x on the surface by baking in the same manner as FIG. 2
5 is an Auger spectrum showing a result of elemental analysis of a surface of a Pt / Ti / SiO ₂ / Si type substrate on which a layer is deposited.

FIG. 4 (a) shows an unfired Pt / Ti / SiO ₂ / Si type substrate.
FIG. 4B is a scanning electron micrograph showing the crystal structure of the surface of the Pt layer, and FIG. 4B is a PZT of a comparative example fabricated on this unfired substrate.
5 is a scanning electron micrograph showing the crystal structure of the surface of a thin film.

Continuation of the front page (56) References JP-A-4-133369 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3/00 C23C 14/08 C23C 14/14 C30B 5 / 00

Claims (2)

(57) [Claims] In a method for producing a lead-based ferroelectric thin film, a film is formed on a substrate by supplying a raw material from the outside, and the substrate is heated for film crystallization during or after the film is formed. Not containing, thickness 30 containing Ti as metal or oxide
(4) A method for producing a lead-based ferroelectric thin film, comprising forming the following Ti-containing layer on the substrate surface and then forming the film. 2. A film is formed on a multilayer substrate having a Pt layer as an uppermost layer and a Ti layer therebelow by supplying a raw material from the outside, and the substrate is heated for thin film crystallization during or after the film formation. In the method for producing a lead-based ferroelectric thin film, the multilayer substrate is baked before film formation to diffuse Ti into the Pt layer, whereby Pt
A method for producing a lead-based ferroelectric thin film, characterized by allowing Ti or TiO _x to appear on a layer surface.