JP5434631B2 - CSD coating film removing composition, CSD coating film removing method using the same, ferroelectric thin film and method for producing the same - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is used to remove the outer peripheral edge of a raw material solution coating film in a CSD method such as a sol-gel method in which a raw material solution is applied and baked to form a ferroelectric thin film such as a PZT film or SBT film. The present invention relates to a composition for removing a CSD coating film, a method for removing the outer peripheral edge of the coating film using the composition, a ferroelectric thin film, and a method for producing the same.

  Ferroelectric materials such as PZT (lead zirconate titanate) and SBT (bismuth strontium tantalate) have a perovskite crystal structure and are expected to be applied to devices such as capacitors and ferroelectric memories (FeRAM). Yes. There is a chemical solution deposition method called a CSD (Chemical Solution Deposition) method such as a sol-gel method, a MOD (Metal Organic Decomposition) method, or a method using a combination of these as a method for forming a thin film made of such a ferroelectric (Patent Document 1). , 2).

  In the sol-gel method, a sol (raw material solution) composed of a metal alkoxide is applied to a substrate to form a coating film, which is made into a gel-like coating film that loses fluidity by hydrolysis and polycondensation reaction, and this gel-like coating film is heated. In this method, an oxide film (ferroelectric thin film) is formed by baking. Technologies for forming a coating film of a raw material solution on a substrate (wafer) include a dip coating method in which the substrate is immersed in the raw material solution, a roll coating method, and a spin coating method in which the raw material solution is supplied while rotating the substrate to form a film. Etc. Among these, particularly in the case of the spin coating method, the film tends to be thick at the outer peripheral end portion of the substrate, and the phenomenon of wrapping around the back surface of the substrate easily occurs.

  In the sol-gel method and the like (hereinafter collectively referred to as CSD method, the solution is referred to as a raw material solution), if the film thickness is too thick, the film after heat treatment is likely to crack, and the film peeled off by this crack becomes particles, This can cause a decrease in device yield. For this reason, a method of removing the coating film on the outer peripheral edge of the substrate before the heat treatment is taken.

When forming lead-based perovskite oxides such as PZT, Pt is used as the lower layer of the PZT film. However, SiO ₂ (substrate material) is often exposed at the edge of the substrate. It is used. When the PZT film is in contact with SiO ₂ , cracks are likely to occur even if the PZT film is thin. In this case as well, the method of removing the coating film before the heat treatment at the outer peripheral edge of the substrate is taken.

As a method for removing the coating film on the outer peripheral edge of the substrate, there is a method called edge beadiness (EBR) in which an organic solvent is brought into contact with the outer peripheral edge of the substrate while rotating the substrate after applying the raw material solution.
Patent Document 3 and Patent Document 4 show a method of removing a photoresist layer formed on a substrate surface by EBR, and a thinner composition is used as a rinsing liquid for the removal.

JP 2001-72926 A JP 2002-29752 A JP 2005-227770 Gazette JP 2007-324393 A

  By the way, in the CSD method, when an organic solvent is sprayed onto a coating film to perform EBR, it is very difficult to control the film cross-sectional shape in the vicinity of the spray region. That is, cracks are generated after the heat treatment at the part where the film is partially thickened, and the film may be peeled off locally due to the generation of the cracks, thereby causing particles.

  The present invention has been made in view of such circumstances, and an object of the present invention is to prevent the generation of particles by removing the film at the outer peripheral edge of the substrate without causing cracks or local peeling in the CSD method. To do.

  The CSD coating film removing composition of the present invention comprises β-diketones, β-ketoesters, polyhydric alcohols, carboxylic acids, alkanolamines, α-hydroxycarboxylic acids, α-hydroxycarbonyl derivatives, and hydrazone derivatives. 1 type or 2 or more types of organic solvents chosen, and water are included.

  In the case of removing a part of the coating film from the raw material solution in the CSD method, it is generally considered that the solvent used in the raw material solution is used. As a solvent for this raw material solution, methanol, ethanol, butanol or the like is used. However, if a solvent such as methanol, ethanol, or butanol is sprayed or dropped on the outer peripheral edge for removing the coating film on the outer peripheral edge of the substrate after applying the raw material solution, cracks or Local peeling is likely to occur.

  The cause is considered as follows. That is, these solvents such as methanol, ethanol, and butanol penetrate into the gel-like coating film when sprayed or dripped onto the gel-like coating film by the raw material solution. A part of the film dissolved by the permeation of the solvent is peeled outward in the radial direction by centrifugal force. At this time, the penetration of the solvent inward in the radial direction and the outward extension of the melted film in the radial direction interact with each other. Becomes uneven. For this reason, it is assumed that cracks and local peeling occur in the vicinity of the injection or dropping region after the heat treatment.

  On the other hand, when this gel-like coating film is removed by the removal liquid containing the water of the present invention and the organic solvent as a stabilizer, water has a low penetrating ability to the film, so that the sprayed or dripped portion is removed. The film at the radially outward position is not partially thick, and cracks and local peeling can be prevented. In this case, the raw material solution is hydrolyzable, but by adding an organic solvent having an effect of stabilizing the metal alkoxide of the raw material solution to water, the hydrolysis of the removed raw material solution is suppressed and the precipitate is precipitated. And the contamination of the work environment by sediments can be prevented.

In the composition for removing a CSD coating film of the present invention, the mixing weight ratio of the organic solvent and the water is preferably 50:50 to 5:95, and more preferably 30:70 to 10:90. .
Since the composition for removal touches the coating film of the raw material solution, it is made an appropriate amount sufficient to prevent purification of the precipitate by hydrolysis of the raw material solution without adding an organic solvent excessively, and water is the main component. By using the composition, the film characteristics of the coating film are not changed.

  In the composition for removing a CSD coating film of the present invention, the β-diketone is acetylacetone, the β-ketoester is methyl 3-oxobutanoate and / or ethyl 3-oxobutanoate, and the polyhydric alcohol is propylene glycol, One or more selected from diethylene glycol and triethylene glycol, the carboxylic acid is one or more selected from acetic acid, propionic acid and butyric acid, and the alkanolamines are monoethanolamine, diethanolamine, One or more selected from triethanolamine, and the α-hydroxycarboxylic acid is one or more selected from lactic acid, mandelic acid, citric acid, tartaric acid, and oxalic acid, and the α-hydroxy Carbonyl derivatives are acetol, acetoin, Razon derivative may is one or more selected from 2-propanone hydrazone.

  The CSD coating film removing composition of the present invention comprises one or more mixed solvents A selected from propylene glycol, diethylene glycol, and triethylene glycol, and methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. The coating film formed by applying a raw material solution containing one or two or more mixed solvents B selected from the above as a solvent may be removed.

  A method of removing a coating film using such a composition for removing a CSD coating film is obtained by spraying or dripping the composition for removing a CSD coating film on the outer peripheral edge of the substrate while rotating the substrate, The coating film at the end is removed.

  The method for producing a ferroelectric thin film according to the present invention includes a step of forming a coating film by applying a raw material solution containing an organometallic compound for forming a ferroelectric thin film to a substrate in the CSD method, and rotating the substrate. The CSD coating film removing composition is sprayed or dropped on the outer peripheral edge of the substrate while removing the coating film on the outer peripheral edge of the substrate, and the coating film is heated to be strong. Forming a dielectric thin film.

  According to the present invention, since the coating film is removed by the removing liquid containing an organic solvent and water, a smooth surface can be obtained without causing cracks or local peeling in the removed portion. In addition, hydrolysis of the removed raw material solution can be suppressed to prevent the formation of a precipitate, and contamination of the work environment by the precipitate can be prevented.

It is sectional drawing which shows roughly the state which removes the coating film of an outer peripheral edge part, rotating a board | substrate in embodiment of this invention.

Embodiments of a composition for removing a CSD coating film of the present invention, a method for removing a CSD coating film using the same, and a method for producing a ferroelectric thin film will be described below with reference to the drawings.
This method of manufacturing a ferroelectric thin film is suitable for manufacturing a perovskite oxide thin film containing Pb such as PZT and PLZT, and a layered perovskite oxide thin film containing Bi such as SBT and SBTN. A step of forming a gel-like coating film (coating film) 1 by applying a raw material solution containing a metal compound to the substrate 2 (raw material solution applying step), and an organic material at the outer peripheral edge of the substrate 2 while rotating the substrate 2 A step of removing the gel-like coating film 1 at the outer peripheral end (EBR step) by spraying or dropping a solvent-containing removal liquid (composition for removing the coating film), and a heat treatment of the gel-like coating film 1 And a step of forming a ferroelectric thin film (heat treatment step).

<CSD raw material solution>
The raw material solution of the CSD method to be used will be described. This raw material solution is obtained by dissolving a raw metal compound with a solvent and adding a stabilizer and the like. For example, for PLZT and SBTN, the following There is something.

  The raw metal compounds of the PLZT raw material solution include organic acid salts such as acetates (lead acetate and lanthanum acetate) as lead compounds and lanthanum compounds, alkoxides such as diisopropoxylead, and tetraethoxy titanium as titanium compounds. Alkoxides such as tetraisopropoxytitanium, tetran-butoxytitanium, tetrai-butoxytitanium, tetrat-butoxytitanium, and dimethoxydiisopropoxytitanium are preferred, but organic acid salts or organometallic complexes can also be used. The zirconium compound is the same as the titanium compound. It may be a compounded metal compound containing two or more kinds of component metals. A small amount of a doping element may be contained.

  On the other hand, examples of the raw material metal compound of the CSD solution for SBTN include Sr organometallic compounds such as Sr isopropoxide and alkoxides such as Sr butoxide, and carboxylates such as 2-ethylhexanoic acid Sr. The Sr organometallic compound may be Sr diethylene glycolate or Sr triethylene glycolate. Therefore, in this case, by adding metal Sr to diethylene glycol or triethylene glycol as a solvent and reacting with heating, Sr diethylene glycol is used. Lat or Sr triethylene glycolate may be produced. Bi-ethylhexanoic acid Bi is used as the Bi organometallic compound, Ta diethylene glycolate or Ta triethylene glycolate is used as the Ta organometallic compound, and Nb diethylene glycolate or Nb triethylene glycolate is used as the Nb organometallic compound.

As the organic solvent (solvent A), any one of a single solvent selected from propylene glycol, diethylene glycol and triethylene glycol, or a mixed solvent of two or more may be used.
The organic solvent and each organometallic compound are mixed at an appropriate ratio so as to obtain a desired metal component concentration. Moreover, heating and refluxing are performed for homogenization of the solution.

In order to make the solution thus obtained have a concentration and wettability suitable for coating, the concentration is adjusted using another solvent (solvent B). The organic solvent may be any one of a single solvent selected from methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, or a mixed solvent of two or more.
The total concentration of organometallic compounds in the solution is preferably about 0.1 to 20% by weight in terms of metal oxide.

  In addition, β-diketones (for example, acetylacetone, heptafluorobutanoylpivaloylmethane, dipivaloylmethane, trifluoroacetylacetone, benzoylacetone, etc.), ketone acids ( For example, acetoacetic acid, propionylacetic acid, benzoylacetic acid, etc.) may be blended in a molar ratio to the metal of about 0.2 to 3 times.

<Raw material solution coating process>
By applying the raw material solution to the substrate 2, the gel-like coating film 1 is formed on the entire surface of the substrate 2.
Substrate materials include silicon wafers (single crystal), metals such as platinum and nickel, ruthenium oxide, iridium oxide, strontium ruthenate (SrRuO ₃ ), or lanthanum strontium cobaltate ((La _x Sr _1-x ) CoO _3. And a substrate made of silicon, glass, alumina, quartz or the like having a coating such as a perovskite type conductive oxide.
When the raw material solution is applied onto the substrate 2, a spin coating method is generally used, but other application methods such as spray coating and dip coating are also applicable.

<EBR process>
As shown in FIG. 1A, while rotating the substrate 2 on which the gel-like coating film 1 after the application of the raw material solution is rotated, the organic solvent and water are supplied from the upper nozzle 3 to the outer peripheral end of the substrate 2. By removing or dripping the contained removal liquid (composition for removing coating film, hereinafter referred to as EBR composition) W, the outer peripheral edge of gel-like coating film 1 is removed as shown in FIG. To do.

  In the EBR composition W, the mixing ratio of the organic solvent and water is preferably 50:50 to 5:95. When the ratio of water is larger than 50:50, the organic solvent is prevented from penetrating from the outer peripheral edge of the film into the film, and the phenomenon occurs when the gel film swollen by the organic solvent penetration cracks after heat treatment. The effect that it can suppress is acquired. Further, when the ratio of water is smaller than 5:95, the metal alkoxide in the raw material solution hydrolyzes and precipitates when the residual liquid after applying the raw material solution to the substrate and the EBR composition W come into contact with each other. This prevents a stable mixture. Thereby, particle contamination due to powder scattering or the like is prevented, and an effect that a high quality film can be obtained can be obtained. Furthermore, the more preferable mixing ratio of the organic solvent and water in the composition W for EBR is 30:70 to 10:90. By setting the mixing ratio in this way, it is possible to stably improve the above-described two phenomena (that is, cracks resulting from penetration of organic solvents and particle contamination resulting from precipitation). In other words, the film properties of the coating film can be changed by using an appropriate amount sufficient to prevent purification of precipitates due to hydrolysis of the raw material solution without adding an organic solvent excessively, and by using a composition containing water as a main component. It is preferable not to let this occur.

  In the EBR composition W, the organic solvent functions as a stabilizer that prevents precipitation due to decomposition of a hydrolyzable compound such as a metal alkoxide in the raw material solution. As the organic solvent, a compound having one or more atoms that can be an electron-donating pair such as oxygen, nitrogen, and sulfur and capable of stabilizing the metal compound by coordinate bonding to the metal, that is, Any stabilizer can be used as long as it can be used as a stabilizer for metal alkoxides. Specifically, β-diketones, β-ketoesters, polyhydric alcohols, carboxylic acids, alkanolamines, α-hydroxycarboxylic acid, α-hydroxy One kind of single solvent selected from carbonyl derivatives and hydrazone derivatives, or two or more kinds of mixed solvents are used. In this case, acetylacetone is used as the β-diketone. As the β-ketoester, methyl 3-oxobutanoate and / or ethyl 3-oxobutanoate are used. As the polyhydric alcohol, one or more selected from propylene glycol, diethylene glycol, and triethylene glycol are used. As the carboxylic acids, one or more selected from acetic acid, propionic acid and butyric acid are used. As the alkanolamines, one or more selected from monoethanolamine, diethanolamine, and triethanolamine are used. As the α-hydroxycarboxylic acid, one or more selected from lactic acid, mandelic acid, citric acid, tartaric acid and oxalic acid are used. As the α-hydroxycarbonyl derivative, acetol or acetoin is used. As the hydrazone derivative, 2-propanone hydrazone is used.

The rotation speed of the substrate 2 in the EBR process is, for example, 1000 to 3000 rpm. What is necessary is just to set suitably the position of the injection or dripping of the composition W for EBR corresponding to the position of removal object. For example, when removing the outer side in the radial direction from the outer peripheral edge 5 mm of the substrate 2, the EBR composition W is sprayed or dropped at a position 5 mm radially inward from the outer peripheral edge of the substrate 2. Remove the outer 5 mm film. What is necessary is just to set suitably as the amount of spraying or dripping from the thickness etc. of the gel-like coating film 1, and should just be sufficient quantity to wash away the gel-like coating film 1 which exists in the range of removal object. If it is said rotational speed, it will be enough if it continues spraying or dripping the composition W for EBR for 2 to 5 seconds.
Further, in this EBR process, the nozzle 3 may be moved outward in the radial direction as necessary while rotating the substrate 2 so that the gel-like coating film 1 at the outer peripheral end portion flows easily. .

<Heat treatment process>
The heat treatment process further includes a drying process, a calcination process, and a crystallization annealing process.

(Drying process)
The gel-like coating film 1 after the outer peripheral end portion is removed is dried to remove the solvent. The drying temperature varies depending on the type of solvent, but is usually about 80 to 200 ° C, preferably 100 to 180 ° C. However, since the solvent is removed during the heating in the next step for converting the metal compound in the raw material solution into the metal oxide, the coating film drying step is not necessarily required.

(Calcination process)
Thereafter, as the calcination step, the substrate 2 after drying the gel-like coating film 1 is heated, and the organometallic compound is completely hydrolyzed or pyrolyzed to be converted into a metal oxide, which is an oxidation made of a metal oxide. A material film is formed. This heating is generally performed in an atmosphere containing water vapor in the sol-gel method that requires hydrolysis, for example, air or a water-containing atmosphere (for example, nitrogen atmosphere containing water vapor), and in the MOD method in which pyrolysis is performed, oxygen-containing. Performed in an atmosphere. Although heating temperature changes also with kinds of metal oxide, it is the range of 150-550 degreeC normally, Preferably, it is 300-450 degreeC. The heating time is selected so that hydrolysis and thermal decomposition proceed completely, but it is usually about 1 minute to 1 hour.

  In the case of the sol-gel method or the like, it is often difficult to obtain a film thickness required for the perovskite oxide thin film by a single application, so if necessary, from the raw material solution coating process to the calcining process. By repeating the process, the raw material solution is repeatedly applied, and each time the application is performed, the gel-like coating film 1 is removed from the outer peripheral end portion, and a metal oxide film having a desired film thickness is obtained.

(Crystal annealing process)
Even if the oxide film thus obtained is amorphous or crystalline, the crystallinity is insufficient, so the polarizability is low and it cannot be used as a ferroelectric thin film. Therefore, finally, as a crystallization annealing step, baking is performed at a temperature equal to or higher than the crystallization temperature of the metal oxide to form a crystalline metal oxide thin film having a perovskite crystal structure. The firing for crystallization is not performed once at the end, but may be performed after the above calcination for each applied coating film, but it is necessary to repeat the firing at a high temperature many times. Therefore, it is economically advantageous to carry out the process collectively at the end.

  The firing temperature for this crystallization is usually a relatively low temperature of 500 to 800 ° C., for example, 550 to 700 ° C. Therefore, a substrate having heat resistance enough to withstand this firing temperature is used as the substrate. The firing (annealing) time for crystallization is usually about 1 minute to 1 hour, and the firing atmosphere is not particularly limited, but is usually air or oxygen.

  The perovskite oxide thin film formed in this way is uniformly formed on the substrate, and there is no crack or local peeling at the outer peripheral edge portion. Therefore, a ferroelectric thin film free from particle adhesion can be obtained. Can do.

As described above, in the case of a structure in which the SiO ₂ of the substrate is exposed at the outer peripheral edge with respect to the Pt layer on the surface of the substrate, such as a lead-based perovskite oxide such as PZT, it is applied on the SiO _2. In addition, cracks are likely to occur in PZT. The coating film removing method in the above manufacturing method is effective as a method for removing a film in a range where the SiO ₂ cracks are likely to occur. In this case, water may be jetted or dropped slightly inward from the inner peripheral edge of the SiO ₂ range.

  Next, an example in which PLZT as a Pb-containing perovskite oxide and a SBTN thin film as a Bi-containing layered perovskite oxide were formed, the film at the outer peripheral edge of the substrate was removed, and the surface was observed and comparison An example will be described.

As the raw material solution for the Pb-containing perovskite oxide thin film (PLZT), the following composition was used.
Lead acetate trihydrate as the lead material, lanthanum acetate hemihydrate as the lanthanum material, zirconium n-butoxide as the zirconium material, titanium tetraisopropoxide as the titanium material, and the total of solvent A, Zr and Ti Two times the number of moles of acetylacetone was mixed as a stabilizer and refluxed at 150 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, it is distilled under reduced pressure at 150 ° C. to remove low-boiling organic substances such as by-products, diluted with solvent B to 10 wt% in terms of oxides, and various Pb-containing perovskite oxide thin film CSD solutions. Obtained. Table 1 shows the PLZT composition, solvent A, and solvent B.

As the raw material solution for the Bi-containing layered perovskite oxide (SBTN), the following composition was used.
Bismuth 2-ethylhexanoate as the bismuth raw material, strontium 2-ethylhexanoate as the strontium raw material, tantalum pentaethoxide as the tantalum raw material, niobium pentaethoxide as the niobium raw material, and the total number of moles of solvent A, Ta and Nb 2.5 times the amount of 2-ethylhexanoic acid was mixed as a stabilizer and refluxed at 150 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, it is distilled at 150 ° C. under reduced pressure to remove low-boiling organic substances including by-products, diluted with solvent B to 10 wt% in terms of oxide, and various Bi-containing layered perovskite oxide thin film CSD solutions. Got. Table 2 shows the SBTN composition, solvent A, and solvent B.

  Further, as the film thickness to be formed increases, cracks at the edge are more likely to occur. In order to compare the occurrence of edge cracks under such conditions with the 10 wt% solution described above, it is the same as the raw material solution for the Pb-containing perovskite oxide thin film and the raw material solution for the Bi-containing layered perovskite oxide thin film. A 25 wt% solution was prepared by the method described above. Table 3 shows the PLZT composition, solvent A, and solvent B. Table 4 shows the SBTN composition, solvent A, and solvent B.

Using these raw material solutions, Pb-containing perovskite oxide thin films (PLZT thin films) and Bi-containing layered perovskite oxide (SBTN) thin films were formed. For the substrate, a SiO ₂ film having a thickness of 500 nm is formed on the surface of a Si substrate having a diameter of 4 inches by thermal oxidation, and a Pt film is formed thereon by a sputtering method except for a region from the outer peripheral edge to 3 mm in the radial direction. A Pt (200 nm) / SiO ₂ (500 nm) / Si substrate was used.

(Pb-containing perovskite oxide thin film)
First, as a preliminary experiment, using the solutions A1 to A6 shown in Table 1, 2 ml was sprayed onto a 4-inch Pt / SiO ₂ / Si substrate, and the spin condition was rotated at 500 rpm × 3 sec, and then rotated at 3000 rpm × 15 sec to rotate the entire surface of the substrate. Coated. Thereafter, the substrate was placed on a hot plate heated to 350 ° C. and heated for 5 minutes to thermally decompose the organic matter, thereby obtaining a lead-containing oxide film. This operation was repeated, and the coating was performed a total of 6 times without performing the EBR process, followed by baking at 700 ° C. for 5 minutes with a rapid thermal annealing apparatus RTA (Rapid Thermal Annealing) to obtain a Pb-containing perovskite oxide thin film.
The outermost peripheral portion of the substrate used in this experiment was not coated with Pt, and any portion where the PLZT thin film was in direct contact with SiO ₂ was cracked after firing.

Example 1
Next, as Example 1, after spin-coating the solutions A1 to A6 on the same Pt / SiO ₂ / Si substrate in the same manner as the preliminary experiment, the reaction at the time of firing the Pb-containing film and SiO ₂ Therefore, while rotating the substrate at 2500 rpm with a spin coater, each of the EBR compositions C1 to C61 shown in Tables 5 and 6 below was sprayed at a position 5 mm radially inward from the outer peripheral edge of the substrate. Then, EBR treatment for dissolving the gel-like coating film was performed.

This substrate was placed on a hot plate and heated in the same manner as in the preliminary experiment to obtain a lead-containing oxide film in a state where the outer peripheral edge was removed by etching. This operation was repeated, and the raw material solution was applied a total of 6 times while performing EBR treatment each time, followed by baking at 700 ° C. for 5 minutes with RTA to obtain a Pb-containing perovskite oxide thin film.
In the obtained sample, no crack or film peeling occurred at the end of the Pb-containing film in any of the EBR compositions. In addition, the CBR solution coating film was scattered around the substrate together with the EBR composition by this EBR treatment, but they were not clouded and adhered to the gel.

  Further, using a 25 wt% solution of D1 to D6 shown in Table 5, EBR treatment is performed with each of the EBR compositions C1 to C61 in the same manner as described above, hot plate treatment and RTA treatment are performed, and a Pb-containing perovskite oxide A thin film was obtained. As for the obtained sample, no cracks or film peeling occurred at the end portion of the Pb-containing film in any of the EBR compositions, and even if the film thickness during EBR is large, the effect of preventing cracks, etc. I found out that

(Comparative Example 1)
Next, as Comparative Example 1, a Pb-containing perovskite oxide was used in the same manner as in Example 1 except that n-butanol was used instead of each EBR composition in Table 5 or Table 6 as the EBR solvent. A thin film was obtained. Cracks and film peeling occurred at the end of the Pb-containing film of the obtained sample.

(Bi-containing layered perovskite oxide thin film)
(Example 2)
As Example 2, in the case of a Bi-containing layered perovskite oxide thin film, similarly to the case of the Pb-containing perovskite oxide thin film (Example 1), the solutions B1 to B6 in Table 2 were added to 4 inches of Pt / SiO _2. After spin coating on the Si substrate, in order to avoid cracks due to thick film at the outer peripheral edge of the substrate, the substrate is rotated at 2500 rpm with a spin coater while being positioned 5 mm radially inward from the outer peripheral edge of the substrate. Each of the EBR compositions C1 to C61 shown in Tables 5 and 6 was sprayed to dissolve the gel-like coating film, and EBR treatment was performed. This substrate was heated on a hot plate in the same manner as in the case of the Pb-containing perovskite oxide thin film to obtain a Bi-containing oxide thin film in which the outer peripheral edge was etched. This operation was repeated in the same manner as in the case of the Pb-containing perovskite oxide thin film, and the raw material solution was applied a total of 6 times, and after each EBR treatment, baked at 800 ° C. for 5 minutes by RTA, and the Bi-containing layered state A perovskite oxide thin film was obtained.
In the obtained sample, no crack or peeling occurred at the end of the Bi-containing film in any of the EBR compositions. Further, the raw material solution coating film scattered around the substrate was not clouded and adhered in a gel form.

  In addition, using a 25 wt% solution of E1 to E6, EBR treatment was similarly performed with each of the CBR to C61 EBR compositions, hot plate treatment and RTA treatment were performed, and a Bi-containing layered perovskite oxide thin film was obtained. As for the obtained sample, no crack or peeling occurred at the end of the Bi-containing film in any of the EBR compositions, and the effect of preventing cracks etc. even if the film thickness during EBR is large. I found out that

(Comparative Example 2)
Further, as Comparative Example 2, the Bi-containing layered perovskite oxide was used in the same manner as in Example 2 except that n-butanol was used in place of each EBR composition shown in Table 5 or Table 6 as the EBR solvent. A thin film was obtained. Cracks and film peeling occurred at the end of the Bi-containing film of the obtained sample.

  Next, with respect to the samples (Examples 1 and 2 and Comparative Examples 1 and 2) obtained in this way, the surface level difference was confirmed using a stylus type surface shape measuring device Dektak manufactured by Veeco Instruments of the United States. However, in each sample of Comparative Example 1 and Comparative Example 2, irregularities of about several hundred nm were confirmed in the outer peripheral edge portion of the ferroelectric thin film within a width range of 1000 to 1500 μm. Example 1 and Example 2 Each of the samples had a very smooth surface with only a minute step of 100 nm or less being observed.

  Moreover, when water was put into a beaker in an appropriate amount and each raw material solution (A1 to A6, B1 to B6) shown in Table 1 or Table 2 was added thereto, it was confirmed that a precipitate was formed. When a raw material solution was added to each of the EBR compositions (C1 to C61) shown in FIG. In particular, among Tables 5 and 6, the EBR composition in which the mixing ratio of the organic solvent and water is in the range of 30:70 to 10:90 is a colorless transparent liquid in which the raw material solution is dissolved in the EBR composition. It was.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
In the above embodiment, the PLZT film and the SBTN film have been mainly described. However, the present invention can also be applied to the case of forming other ferroelectric thin films formed by the CSD method.

DESCRIPTION OF SYMBOLS 1 Gel-like coating film 2 Substrate 3 Nozzle W CSD coating film removal composition (removal liquid or EBR composition)

Claims (8)

A composition for removing the coating film before the heat treatment in the CSD method,
one or more organic solvents selected from β-diketones, β-ketoesters, polyhydric alcohols, carboxylic acids, alkanolamines, α-hydroxycarboxylic acids, α-hydroxycarbonyl derivatives, and hydrazone derivatives; And a composition for removing a CSD coating film, comprising water.   The composition for removing a CSD coating film according to claim 1, wherein the mixing weight ratio of the organic solvent and the water is 50:50 to 5:95.   The composition for removing a CSD coating film according to claim 2, wherein a mixing weight ratio of the organic solvent and the water is 30:70 to 10:90.   The β-diketone is acetylacetone, the β-ketoester is methyl 3-oxobutanoate and / or ethyl 3-oxobutanoate, and the polyhydric alcohol is one or two selected from propylene glycol, diethylene glycol, and triethylene glycol One or more selected from acetic acid, propionic acid and butyric acid, and one or more selected from alkanolamines selected from monoethanolamine, diethanolamine and triethanolamine. And the α-hydroxycarboxylic acid is one or more selected from lactic acid, mandelic acid, citric acid, tartaric acid, and oxalic acid, and the α-hydroxycarbonyl derivative is 2-hydroxyacetol, acetoin, and hydrazone derivative. In propanone hydrazone CSD coating film removing composition according to any one of claims 1 to 3, wherein Rukoto.   One or more mixed solvents A selected from propylene glycol, diethylene glycol, and triethylene glycol, and one or more mixed solvents selected from methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. The composition for removing a CSD coating film according to any one of claims 1 to 4, wherein the coating film formed by applying a raw material solution containing the solvent B as a solvent is removed. In the CSD method, a coating film formed by applying a raw material solution to a substrate is removed,
While rotating the substrate, the CSD coating film removing composition according to any one of claims 1 to 5 is sprayed or dropped on an outer peripheral end portion of the substrate to remove the coating film at the outer peripheral end portion. A method for removing a CSD coating film, comprising: In the CSD method, a step of forming a coating film by applying a raw material solution containing an organometallic compound for forming a ferroelectric thin film to a substrate;
While the substrate is rotated, the CSD coating film removing composition according to any one of claims 1 to 5 is sprayed or dropped on an outer peripheral end portion of the substrate, and the coating at the outer peripheral end portion of the substrate is performed. Removing the film;
And a step of forming a ferroelectric thin film by heat-treating the coating film.   A ferroelectric thin film manufactured by the method for manufacturing a ferroelectric thin film according to claim 7.

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