JP2007246322A - Metal oxide precursor solution, method for forming metal oxide film, method for manufacturing semiconductor device and method for manufacturing electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal oxide precursor solution which hardly produces striation and to improve film forming property and characteristics of a metal oxide film. <P>SOLUTION: When the metal oxide precursor solution 3 is applied on a substrate 1 by a spin coat method, dried and fired to form a metal oxide film 3a, the metal oxide precursor solution 3 is prepared as a solution having a vapor pressure at 20°C of ≤0.5 hPa, preferably a viscosity at 20°C of ≤20 cP. Reduction of striation and improvement of film forming property are achieved by imparting a vapor pressure at 20°C of ≤0.5 hPa, preferably a viscosity at 20°C of ≤20 cP to a main solvent of a solvent used in the solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal oxide precursor solution, a method for forming a metal oxide film, a method for manufacturing a semiconductor device, and a method for manufacturing an electronic device.

  As a method for forming a metal oxide film used as a ferroelectric film or a piezoelectric film, it can be formed by CVD (chemical vapor deposition) or sputtering, but these methods are expensive. Equipment is required.

  On the other hand, a film forming method using a metal oxide precursor solution is used as a method for forming a film with good quality because it is easy to adjust (prepare) the film components. Further, according to such a method, a uniform film can be formed over a large area, and attention is paid to an effective film forming method.

  The metal oxide precursor solution contains a metal oxide material compound and a solvent. The metal oxide precursor solution is applied onto a substrate, dried and fired to form a metal oxide film. To do.

For example, in the following Patent Document 1 (Japanese Patent Laid-Open No. 2001-48540), a metal alkoxide of Pb, La, Zr and Ti and a partial hydrolyzate thereof are used for forming a high-quality PLZT ferroelectric thin film without striation. And / or a perovskite-type PLZT ferroelectric thin film forming composition containing an organic acid salt, wherein the PLZT ferroelectric thin film forming composition having a water content of 0.8% by weight or less is used. Apply the thin film forming composition to a heat resistant substrate and repeat the process of heating in air, in an oxidizing atmosphere or in a steam-containing atmosphere until a film of the desired thickness is obtained, at least during or after heating in the final process A method for forming a PLZT ferroelectric thin film in which the film is baked at a crystallization temperature or higher is disclosed. In addition, techniques relating to the countermeasure against striation of the ferroelectric thin film are disclosed in, for example, Patent Documents 2 to 5 below.
JP 2001-48540 A Japanese Patent Application Laid-Open No. 10-199336 JP 2001-72416 A JP 2005-38830 A JP 2000-351623 A

  The present inventors are conducting research and development on the formation of a metal oxide film using a metal oxide precursor solution, and intensively studying to form a metal oxide film with good characteristics while preventing striations Are piled up.

  Among others, 1) A suitable solvent used for the metal oxide precursor solution is studied. For example, when silicon shown in the above document is added to the raw material solution, silicon remains as an impurity in the film, Degradation of characteristics as a ferroelectric thin film occurs.

  Moreover, 2) When the raw material solution contains water, a problem arises in its storage property, and its moisture retention management (control of water content) is difficult.

  3) When propylene glycol or a propylene glycol derivative is used as the raw material solution, the viscosity of the raw material solution becomes too high and the film formability is not good.

  4) When a metal compound having a reactive group and a hydrophobic group is used in the raw material solution, it is difficult to synthesize these compounds.

  As described above, as a result of various studies including the conventional raw material solution, the vapor pressure and viscosity of the solvent are important for the prevention of striation, and the precursor solution after mixing the metal compound and the solvent is important. It has been found that the selection and combination of the solvents are important in consideration of the characteristics of the metal compound (for example, solubility in the solvent) so that the vapor pressure and viscosity are good.

  It is an object of the present invention to provide a metal oxide precursor solution that hardly causes striations. Another object is to improve the film formability and characteristics of the metal oxide film. It is another object of the present invention to improve the characteristics of an element or device having a metal oxide film.

  (1) The present invention provides a metal oxide precursor solution having a metal oxide material compound and a solvent, wherein the vapor pressure at 20 ° C. is 0.5 hPa or less. It is.

  According to this configuration, since the vapor pressure at 20 ° C. of the metal oxide precursor solution itself is adjusted to 0.5 hPa or less, the occurrence of striation can be reduced and the film formability can be improved. In addition, the characteristics of the formed film can be improved.

  (2) The present invention is a metal oxide precursor solution having a metal oxide material compound and a solvent, wherein the main solvent constituting 50% by volume or more of the solvent has a vapor pressure of 0.5 hPa at 20 ° C. The metal oxide precursor solution is characterized by the following.

  According to such a configuration, since the vapor pressure at 20 ° C. of the main solvent of the metal oxide precursor solution is adjusted to 0.5 hPa or less, the vapor pressure of the metal oxide precursor solution can be reduced. Can be reduced. Further, the film formability can be improved, and the characteristics of the formed film can be improved.

  The solvent is, for example, a single solvent and is made of 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol.

  The solvent is, for example, a mixed solvent, and a solvent comprising 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol is It is a main solvent constituting 50% by volume or more of the solvent.

  The solvent has a viscosity at 20 ° C. of 20 cP or less, for example.

  (3) The present invention is a metal oxide precursor solution having a metal oxide material compound and a solvent, wherein the solvent is, for example, a mixed solvent, and a main solvent constituting 50% by volume or more of the solvent And the main solvent has a vapor pressure at 20 ° C. of 0.5 hPa or less, and the sub solvent has a lower viscosity at 20 ° C. than the main solvent. It is characterized by being.

  (4) The present invention is a metal oxide precursor solution having a metal oxide material compound and a solvent, wherein the solvent is, for example, a mixed solvent, and a main solvent constituting 50% by volume or more of the solvent A sub-solvent constituting 50% by volume or less of the solvent, the main solvent having a vapor pressure at 20 ° C. of 0.5 hPa or less, and the sub-solvent being a solvent having a polarity greater than that of the main solvent. A metal oxide precursor solution characterized by

  The solvent includes, for example, a crack preventing agent.

  (5) The present invention is a metal oxide precursor solution having a metal oxide material compound and a solvent, and 2- (2-n-butoxyethoxy) as a main solvent constituting 50% by volume or more of the solvent It contains ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol.

  The solvent further contains, for example, a solvent having a polarity greater than that of the main solvent as a secondary solvent.

  The solvent further contains, for example, a crack preventing agent.

  The material compound of the metal oxide is a metal alkoxide, a metal carboxylate, or a metal β-dionato complex.

  (6) The present invention relates to a method for forming a metal oxide film using a metal oxide precursor solution, wherein the metal oxide precursor solution is applied and then dried and fired. It is.

  (7) The present invention is a method for manufacturing a semiconductor device having a metal oxide, the method comprising forming the metal oxide film.

  (8) The present invention is a method for manufacturing an electronic device having a semiconductor device, and the method for manufacturing an electronic device characterized by including the method for manufacturing a semiconductor device. Here, “electronic device” means a general device having a certain function provided with an element having a metal oxide film according to the present invention, and its configuration is not particularly limited. Droplet ejection apparatus having a computer device having a dielectric memory device in general, a mobile phone, a PHS, a PDA, an electronic notebook, an IC card, and other devices that require a storage device, and a piezoelectric element having the metal oxide film Etc. are included.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or related code | symbol is attached | subjected to what has the same function, and the repeated description is abbreviate | omitted.

(Metal oxide film formation method)
A method for forming a metal oxide film according to the present embodiment will be described with reference to FIG. FIG. 1 is a fragmentary cross-sectional view showing a metal oxide film forming process of the present embodiment.

  As shown in FIG. 1A, a metal oxide precursor solution 3 is applied on a substrate 1 by a spin coating method. This metal oxide precursor solution is a solution having a metal oxide material compound (metal compound, organometallic compound) and a solvent. Further, this metal oxide precursor solution has a vapor pressure at 20 ° C. of 0.5 hPa or less. More preferably, the viscosity at 20 ° C. is 20 cP [in the SI unit notation, 0.02 Pa · s] or less. In addition, you may apply | coat (drop) the metal oxide precursor solution 3 on the board | substrate 1 with the inkjet method. Further, a dip coating method may be used.

  Next, as shown in FIG. 1B, the metal oxide precursor solution (coating film) is dried, the solvent in the solution is volatilized, and then subjected to heat treatment (firing) to form a metal oxide film (metal). Oxide thin film) 3a is formed. Thereafter, crystallization annealing is performed on the metal oxide as necessary.

  Thus, according to this embodiment, since the vapor pressure of the metal oxide precursor solution itself is set to 0.5 hPa or less at 20 ° C., the occurrence of striation (film unevenness) can be reduced.

  For example, when the vapor pressure at 20 ° C. of the metal oxide precursor solution itself is 0.5 hPa or more, the solvent is likely to volatilize and striation is likely to occur. For example, as shown in FIG. 2A, in the substantially circular substrate 1, convex portions 51 on the stripes are formed radially on the surface of the metal oxide film 53a from the center. FIG. 2B shows a cross section of this convex portion. FIG. 2 is a plan view and a cross-sectional view showing striations. When such unevenness due to striation occurs, the unevenness is reflected (transferred) on the base during the etching process or the like of the film. Therefore, the bonding properties of other films and elements formed on the base are deteriorated, and the element characteristics are deteriorated.

  This striation is likely to occur when the metal oxide precursor solution is dried. This is thought to occur due to convection in the solution (Marangon convection, Benard convection).

  However, as a result of the study by the present inventors, it has been found that the occurrence of striation can be suppressed by suppressing the vapor pressure as described above, that is, by gradually evaporating.

  Here, the metal oxide precursor solution has a vapor pressure at 20 ° C. of 0.5 hPa or less, and more preferably, the viscosity at 20 ° C. is 20 cP or less. The vapor pressure at 20 ° C. is 0.5 hPa or less, and more preferably, the viscosity at 20 ° C. is 20 cP or less, thereby reducing striation and improving film formability. Here, the main solvent means a solvent constituting 50% by volume or more of the precursor solvent. Here, the volume% of the solvent refers to the ratio of the volume of the specific solvent to the sum of the volumes of the plurality of solvents to be mixed, and is 100 volume% in the case of a single solvent. Here, the sum of the volumes of the plurality of solvents refers to the sum of the volumes of the respective solvents before mixing.

(Experimental example)
Next, a specific metal oxide film formation example (experimental example) examined by the present inventors will be described.

  A metal oxide precursor solution A of PZT (lead zirconate titanate), which is a metal oxide film, was prepared as follows. FIG. 3 shows a preparation flow of a metal oxide precursor solution of PZT (lead zirconate titanate).

  As shown in FIG. 3, 2- (2-n-butoxyethoxy) ethanol is prepared as a solvent (step S1). The 2- (2-n-butoxyethoxy) ethanol is a low vapor pressure solvent (a solvent having a vapor pressure at 20 ° C. of 0.5 hPa or less). Specifically, the vapor pressure at 134 ° C. is 13 hPa, and the boiling point is 230 ° C.

  Next, titanium tetraisopropoxide (Ti compound) is added to 2- (2-n-butoxyethoxy) ethanol as a metal oxide (PZT) material compound and stirred at room temperature for 15 minutes (step S2).

  Next, diethanolamine is added and stirred at room temperature for 15 minutes (step S3). This diethanolamine functions as a stabilizer for Ti, and also functions as a solubilizing agent for Pb and Zr described later. That is, if a highly polar solvent such as diethanolamine is used, the metal complex can be stabilized, and a polar material compound (not easily soluble in oil) can be dissolved.

  Next, lead acetate trihydrate (Pb compound) and zirconium acetylacetonate (Zr compound) are added as material compounds, stirred at 80 ° C. for 20 minutes, and naturally cooled at room temperature (step S4).

  Next, polyethylene glycol is added as a crack preventing agent and stirred at room temperature for 10 minutes (step 5).

  A metal oxide precursor solution A was prepared by the above process. As a comparative example, a metal oxide precursor solution B prepared using 2-n-butoxyethanol as a solvent under the same conditions as in the flow shown in FIG. 3 was also prepared. This 2-n-butoxyethanol is a high vapor pressure solvent having a vapor pressure of 0.8 hPa at 20 ° C., and its boiling point is 171 ° C.

  Next, these metal oxide precursor solutions A and B are applied onto a silicon wafer (substrate) having a diameter of 6 inches by using a spin coat method, and dried at 160 ° C. to form a dry coating film. did.

  In the treatment of the metal oxide precursor solution A, the surface states of the wafers after the metal oxide precursor solutions A and B are dried when the spin coating rotation speed is 1460 rpm are shown in FIGS. 4 and 5, respectively. In each figure, (A) shows the surface state in the central portion of the wafer, and (B) shows the surface state in the outer peripheral portion of the substrate. Further, (A) and (B) are reproduction drawings of the surface photograph of the wafer, and (C) and (D) are drawings showing the surface state of the photographs (figure) of (A) and (B). is there.

  As shown in FIG. 5, when 2-n-butoxyethanol, which is a high vapor pressure solvent, is used, spot-like convex portions are confirmed at the center of the wafer (FIGS. 5A and 5C). In the outer peripheral portion of the wafer, striped convex portions were confirmed (FIGS. 5B and 5D). That is, the occurrence of striation was confirmed.

  In contrast, when 2- (2-n-butoxyethoxy) ethanol, which is a low vapor pressure solvent, is used, as shown in FIG. 4, the protrusions are confirmed at the center and the outer periphery of the wafer. There wasn't. That is, the occurrence of striation was not confirmed. In addition, although illustration is abbreviate | omitted, generation | occurrence | production of striation was not confirmed also when spin-coating the metal oxide precursor solution A with the rotational speed of 1000 rpm, and drying similarly.

  Then, the film thickness in each point (P1-P5) of each dry coating film (wafer) was measured using the optical interference type film thickness measuring apparatus. The result is shown in FIG.

  As shown in FIG. 6, in the dry coating film of the metal oxide precursor solution B, it was confirmed that there was a height difference of about 17.2 μm at the maximum at each point. The height difference refers to the difference between the “mountain” and “valley” columns in FIG. On the other hand, in the dry coating film of the metal oxide precursor solution A, the above height difference is not confirmed when the rotational speed is 1460 rpm or 1000 rpm, and when the rotational speed is 1460 rpm, the film thickness is 410 μm. In the case of 1000 rpm, a film thickness of about 620 μm could be secured.

  Thus, in this experimental example, a dry coating film with reduced striations could be obtained by using a low vapor pressure solvent. Further, as can be seen from FIG. 6, the use of the low vapor pressure solvent tends to reduce the film thickness of the dry coating film by the amount that volatilization is limited. However, it has been found that the reduction of the film thickness can be dealt with by reducing the rotation speed.

(Examination of specific solvents 1)
Next, referring to FIG. 7, a solution suitable for use as a solvent is examined. FIG. 7 is a chart showing the relationship between chemical names (solution names), vapor pressure [hPa], viscosity [cP], solubility in water, and the like. These chemicals are classified according to their basic skeleton into ethylene glycol derivatives, diethylene glycol derivatives, propanediol derivatives, butanediol derivatives and saturated hydrocarbon alcohols. In addition, the boiling point [° C.] and density [g / ml] are also shown for each chemical.

  Among the chemicals shown in FIG. 7, those having a vapor pressure at 20 ° C. of 0.5 hPa or less are suitable for use as the solvent. The “Vapor Pressure” column for chemicals that satisfy this condition is circled.

  The vapor pressure condition is indispensable as a countermeasure against the above-mentioned striations, but the viscosity also affects the improvement of the film forming property. In other words, even if the vapor pressure condition is cleared, if the viscosity is too high, it is difficult to drop droplets, and the film formability is deteriorated such that the solution is difficult to spread even if spin coating is performed. In addition, in order to improve the film forming property, it is necessary to devise such as changing a droplet discharging method or a coating method.

  Accordingly, the viscosity of the solvent at 20 ° C. is preferably 20 cP or less. Among the chemicals shown in FIG. 7, those having a vapor pressure condition and having a viscosity at 20 ° C. of 20 cP or less are suitable for use as a solvent. Among the chemicals shown in FIG. 7, the “viscosity” column of chemicals having a viscosity at 20 ° C. of 20 cP or less is circled.

  Furthermore, it is more preferable that the polarity is higher in addition to the vapor pressure and viscosity conditions. As described above, some metal oxide material compounds require a solubilizer or stabilizer. This is because the metal oxide material compound has many forms such as a carboxylate and a β-dionato complex, and these compounds may be difficult to dissolve in a solvent having a small polarity. Moreover, even if it melt | dissolves, it is uneasy, and may precipitate (deposit) after that, and needs to exist in a solution stably. Such solubility and stability are closely related to the polarity of the solvent. That is, by using a polar solvent as a solubilizing agent / stabilizer, a metal oxide precursor solution can be easily obtained. In general, polar solvents are highly soluble in water, and as a solubilizer / stabilizer, protic solvents such as carboxylic acids and chelating agents such as alkanolamines and β-diketones can be used. .

  Therefore, among the chemicals shown in FIG. 7, among the chemicals having a vapor pressure at 20 ° C. of 0.5 hPa or less and a viscosity at 20 ° C. of 20 cP or less, the solubility in water at 20 ° C. is 20% by volume or more. Are suitable for use as the solvent. Among the chemicals shown in FIG. 7, the column “Solubility in water” of chemicals whose solubility in water at 20 ° C. is 20% by volume or more is circled.

  Therefore, it is preferable to use a chemical having a circle in all of the columns of “vapor pressure”, “viscosity” and “solubility in water” as a solvent.

  In particular, considering the values of vapor pressure, viscosity, and solubility in water, ease of handling, and versatility, all of the columns for vapor pressure, viscosity, and solubility in water are included in diethylene glycol derivatives. It is preferable to use a chemical with a circle as a solvent. In particular, 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol is preferable.

  Chemicals in which all the columns of the above "vapor pressure", "viscosity" and "solubility in water" are circled, that is, the vapor pressure at 20 ° C is 0.5 hPa or less, and the viscosity at 20 ° C is 20 cP or less A chemical having a water solubility of 20% by volume or more at 20 ° C. can be used as a single solvent. Of course, it can also be used as the main solvent of the mixed solvent.

  Thus, by using a solvent that satisfies the above conditions, the vapor pressure of the metal oxide precursor solvent itself can be reduced, and the occurrence of striation can be suppressed. In addition, the optimum viscosity can be maintained and the film formability of the coating film can be improved. Further, by imparting polarity, it is possible to improve the solubility of a material compound (particularly, a metal carboxylate or β-dionato complex) and the stability of the metal after dissolution. In addition, when using a metal alkoxide as a material compound, the solubility with respect to water in 20 degreeC may be 20 volume% or less. However, as the solubility in water increases, the change with time (deterioration due to moisture in the atmosphere) decreases, so there is no problem even if a solubilizing agent or stabilizer is added.

  In addition, a crack preventing agent is added as needed. This crack preventing agent includes a polymer material such as polyethylene glycol, and its use is preferable particularly when a metal oxide film having a thickness of 0.5 μm or more is formed.

(Consideration of specific solvent 2)
In the above examination, the chemicals in which all the columns of “vapor pressure”, “viscosity” and “solubility in water” in FIG. 7 are circled, that is, the vapor pressure at 20 ° C. is 0.5 hPa or less, and Although it has been explained that a chemical having a viscosity at 20 ° C. of 20 cP or less and a solubility in water at 20 ° C. of 20% by volume or more is suitable as a main solvent, “viscosity” and “solubility in water” It is possible to deal with chemicals that do not satisfy the above conditions by the following method. Here, the metal compound is a) a metal alkoxide, b) a metal compound other than the metal alkoxide, but c) a metal compound other than the metal alkoxide when the alkoxide is formed by ligand exchange. When the ligand exchange does not occur, it is classified as follows, and solvent selection and preparation methods are described. 8 to 10 are flowcharts showing a method for selecting and preparing a solvent for the metal oxide precursor solution. In this flowchart, it is assumed that the vapor pressure of the main solvent at 20 ° C. is 0.5 hPa or less.

  As shown in FIG. 8, when all the metal compounds used are metal alkoxides, the following flow is followed. That is, it is determined whether or not the viscosity of the main solvent at 20 ° C. is 20 cP or less. If the viscosity is below (Yes), the solubility in water is 20% by volume or more (satisfying the solubility in water), No adjustment with a secondary solvent is necessary (in other words, it can be used as a single solvent). However, since the stability of the metal oxide precursor solution can be further improved by adding a stabilizer as described above, there is no problem even if a stabilizer is added. As described above, the adjusted metal oxide precursor solution itself has a vapor pressure at 20 ° C. of 0.5 hPa or less and a viscosity at 20 ° C. of 20 cP or less.

  Here, when the viscosity is not 20 cP or less (No), the viscosity is adjusted to 20 cP (20 ° C.) or less using a secondary solvent. In this case, it can be said that the main solvent has a higher viscosity than the sub-solvent.

  When the solubility in water is 20% by volume or more (more preferably, freely mixed or easily soluble) (Yes), adjustment with a secondary solvent is not necessary if the viscosity condition is satisfied (in other words, used as a single solvent) Is possible). When the solubility in water is not 20% by volume or more (No), adjustment is made using a solvent (dissolution aid, stabilizer) having a solubility in other water of 20% by volume or more, that is, a secondary solvent. In this case, it can be said that the main solvent is less polar than the sub-solvent.

  As shown in FIG. 9, when the metal compound to be used contains a metal compound other than the metal alkoxide and all of the metal compound becomes a metal alkoxide by ligand exchange, the following flow is followed. That is, it is determined whether or not the viscosity of the main solvent at 20 ° C. is 20 cP or less. If the viscosity is below (Yes), the solubility in water is 20% by volume or more (the condition for solubility in water is satisfied), No adjustment with a secondary solvent is necessary (in other words, it can be used as a single solvent). However, since the stability of the metal oxide precursor solution can be further improved by adding a stabilizer as described above, there is no problem even if a stabilizer is added. As described above, it is more preferable that the adjusted metal oxide precursor solution itself has a vapor pressure at 20 ° C. of 0.5 hPa or less and a viscosity at 20 ° C. of 20 cP or less.

  Here, when the viscosity is not 20 cP or less (No), the viscosity is adjusted to 20 cP (20 ° C.) or less using a secondary solvent. In this case, it can be said that the main solvent has a higher viscosity than the sub-solvent.

  When the solubility in water is 20% by volume or more (more preferably, freely mixed or easily soluble) (Yes), adjustment with a secondary solvent is not necessary if the viscosity condition is satisfied (in other words, used as a single solvent) Is possible). However, since the stability of the metal oxide precursor solution can be further improved by adding a stabilizer as described above, there is no problem even if a stabilizer is added. When the solubility in water is not 20% by volume or more (No), adjustment is made using a solvent (dissolution aid, stabilizer) having a solubility in other water of 20% by volume or more, that is, a secondary solvent. In this case, it can be said that the main solvent is less polar than the sub-solvent.

  As shown in FIG. 10, when the metal compound to be used contains a metal compound other than the metal alkoxide and ligand exchange does not occur, the following flow is followed. That is, it is determined whether or not the viscosity of the main solvent at 20 ° C. is 20 cP or less. If the viscosity is below (Yes), a solvent having a solubility in other water of 20% by volume or more as a solubilizer, that is, a secondary solvent is used. Use to adjust. Moreover, when viscosity is not 20 cP or less (No), while adjusting a viscosity to become 20 cP (20 degreeC) or less using a subsolvent, the solubility with respect to other water is 20 volume% or more as a solubilizing agent. Prepare with solvent, ie other sub-solvents.

  When the solubility in water is 20% by volume or more (more preferably, freely mixed or easily soluble) (Yes), as a solubilizer, other solvents having a solubility in water of 20% by volume or more, Adjust with solvent. Moreover, when it is not 20 volume% or more (No), it adjusts using the solvent (dissolution auxiliary agent, stabilizer), ie, a subsolvent whose solubility with respect to other water is 20 volume% or more.

  Thus, even if the main solvent does not satisfy the conditions for “viscosity” and “solubility in water” among the above three conditions, a suitable metal oxide precursor can be obtained by appropriately selecting and adjusting the sub-solvent. A solution can be prepared. Here, the sub-solvent refers to a solvent that constitutes 50% by volume or less of the solvent, and it does not matter whether it is a kind or not.

  In the experimental example of the above embodiment, PZT has been described as an example, but the present invention can be widely applied to other metal oxide precursor solutions.

  In addition, as a method for forming a metal oxide film, there are a sol-gel method, an organometallic decomposition (MOD) method, and the like, which are widely applicable to the formation of a metal oxide film using a metal oxide precursor solution.

  The metal oxide film formed using the metal oxide precursor solution is used as a ferroelectric film in a ferroelectric memory or the like. Moreover, it is used for a piezoelectric element etc. as a piezoelectric film. Therefore, the metal oxide precursor solution of this embodiment can be widely applied to a method for manufacturing an element (semiconductor element) having a metal oxide film, and can be widely applied to a method for manufacturing an electronic device having such an element. It is.

It is principal part sectional drawing which shows the formation process of the metal oxide film of this Embodiment. It is the top view and sectional drawing which show striations. It is a figure which shows the preparation flow of the metal oxide precursor solution of PZT (lead zirconate titanate). It is a figure which shows the surface state of the wafer after drying of the metal oxide precursor solution A. It is a figure which shows the surface state of the wafer after drying of the metal oxide precursor solution B. It is a graph which shows the film thickness in each point (P1-P5) of each dry coating film. It is a chart showing the relationship between chemical name (solution name), vapor pressure [hPa], viscosity [cP], solubility in water, and the like. It is a flowchart which shows the selection of the solvent of a metal oxide precursor solution, and a preparation method. It is a flowchart which shows the selection of the solvent of a metal oxide precursor solution, and a preparation method. It is a flowchart which shows the selection of the solvent of a metal oxide precursor solution, and a preparation method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 3 ... Metal oxide precursor solution, 3a ... Metal oxide film, 51 ... Convex part, 53a ... Metal oxide film, S1-S5 ... Step

Claims (15)

A metal oxide precursor solution having a metal oxide material compound and a solvent,
A metal oxide precursor solution having a vapor pressure at 20 ° C. of 0.5 hPa or less. A metal oxide precursor solution having a metal oxide material compound and a solvent,
The main solvent constituting 50% by volume or more of the solvent has a vapor pressure at 20 ° C. of 0.5 hPa or less.   The solvent is a single solvent and is composed of 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol. The metal oxide precursor solution according to claim 1 or 2.   The solvent is a mixed solvent, and a solvent comprising 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol is the solvent. 3. The metal oxide precursor solution according to claim 1, wherein the metal oxide precursor solution is a main solvent constituting 50% by volume or more.   The metal oxide precursor solution according to claim 1 or 2, wherein the solvent has a viscosity at 20 ° C of 20 cP or less. A metal oxide precursor solution having a metal oxide material compound and a solvent,
The solvent is a mixed solvent, and consists of a main solvent constituting 50% by volume or more of the solvent and a sub-solvent constituting 50% by volume or less of the solvent,
The main solvent has a vapor pressure at 20 ° C. of 0.5 hPa or less,
The sub-solvent is a solvent having a lower viscosity at 20 ° C. than the main solvent. A metal oxide precursor solution having a metal oxide material compound and a solvent,
The solvent is a mixed solvent, and consists of a main solvent constituting 50% by volume or more of the solvent and a sub-solvent constituting 50% by volume or less of the solvent,
The main solvent has a vapor pressure at 20 ° C. of 0.5 hPa or less,
The metal oxide precursor solution, wherein the sub-solvent is a solvent having a polarity greater than that of the main solvent.   The metal oxide precursor solution according to claim 1, wherein the solvent contains a crack preventing agent.   A metal oxide precursor solution having a metal oxide material compound and a solvent, wherein 2- (2-n-butoxyethoxy) ethanol, 2- (2- A metal oxide precursor solution containing n-ethoxyethoxy) ethanol or 2- (2-methoxyethoxy) ethanol.   The metal oxide precursor solution according to claim 9, wherein the solvent further contains a solvent having a polarity greater than that of the main solvent as a sub-solvent.   The metal oxide precursor solution according to claim 9 or 10, wherein the solvent further contains a crack preventing agent.   The metal oxide precursor solution according to any one of claims 1 to 11, wherein the material compound of the metal oxide is a metal alkoxide, a metal carboxylate, or a metal β diato complex.   A method of forming a metal oxide film using a metal oxide precursor solution, wherein the metal is formed by applying and drying and firing the metal oxide precursor solution according to any one of claims 1 to 12. A method for forming an oxide film.   A method for manufacturing a semiconductor device having a metal oxide, comprising the method for forming a metal oxide film according to claim 13. 15. A method of manufacturing an electronic device having a semiconductor device, comprising the method of manufacturing a semiconductor device according to claim 14.