JP3054118B2 - Raw material for lead titanate-based dielectric thin film and capacitor for memory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CVD (Chemical Vapor Deposition) method for forming an oxide-based dielectric thin film used for a dielectric memory such as a DRAM, a dielectric filter, and the like, in particular, a lead titanate-based dielectric thin film. The present invention relates to a raw material for deposition and a memory capacitor using the raw material.

[0002]

2. Description of the Related Art In recent years, high integration of memory devices in semiconductors has been rapidly progressing. For example, in a dynamic random access memory (DRAM), high integration has progressed at a rapid pace of four times the number of bits in three years. This is for the purpose of speeding up the device, reducing power consumption, reducing cost, and the like. However, no matter how the degree of integration is improved, the capacitor, which is a component of the DRAM, must have a certain capacitance. For this reason, it is necessary to reduce the film thickness of the capacitor material, and the use of SiO ₂ which has been used up to that point has caused a limitation in thinning.
So if you can change the material and increase the dielectric constant,
Since capacity can be ensured as in the case of thinning, research on using a dielectric material having a high dielectric constant as a dielectric film of a capacitor for a memory device has recently attracted attention.

As the performance required for such a memory capacitor material, it is most important that the thin film has a high dielectric constant as described above and that the leakage current is small. That is, as long as a high dielectric constant material is used, it is necessary to make the film as thin as possible and to minimize the leak current. As a rough development goal, it is generally considered desirable that the film thickness in terms of SiO ₂ be 1 nm or less, and the leakage current density when applying 1.65 V be 10 ^-8 A / cm ² or less. In addition, in order to form a thin film on a capacitor electrode of a DRAM having a step, it is very advantageous in terms of process to be able to form a film by a CVD method with good adherence to an object having a complicated shape. is there. From such a viewpoint, tantalum oxide, lead zirconate titanate (P
ZT), lead lanthanum zirconate titanate (PLZT),
Oxide-based dielectric materials such as strontium titanate and barium titanate have been studied using various film forming methods.
However, despite the fact that it is most advantageous to form a film by the CVD method, there is a major problem that there is currently no material having stable and good vaporization properties as a CVD material. This is mainly due to β-diketone dipivaloylmethane (D
This is because the PM) compound has poor vaporization characteristics due to heating. This point has been pointed out, for example, in the 52nd JSAP Symposium Proceedings No. 9a-P-11, and is considered to be a drawback caused by the intrinsic instability of metal DPM compounds. Nevertheless, the CVD method has been actively studied as in, for example, the 52nd Annual Meeting of the Japan Society of Applied Physics, Proceedings No. 9a-P-6, and because of the instability of the raw materials as described above, In an extreme case, a situation has arisen in which a raw material must be disposable and a film must be formed. Therefore, due to the drawbacks caused by the above-mentioned raw materials, a technique for producing a dielectric thin film having good performance and good reproducibility of production has not been established at present.

[0004]

As described above, in the production of an oxide dielectric film by the conventional CVD method, C
Due to the poor stability and vaporization of the VD raw material, it has been impossible to stably transport the CVD raw material to the CVD reaction section by heating at a low temperature. Therefore, there is a major problem that it is difficult to control the composition and stable synthesis of a dielectric film having good characteristics cannot be performed. Further, when heating at a high temperature in order to increase the vaporization efficiency of the CVD raw material, the raw material is transported while being thermally decomposed, so that poor crystallinity of the film and deviation of composition are inevitable. In addition, there has been an inconvenience that the raw materials must be disposable as described above. Also, in the conventional method, when the synthesis (reaction) time is lengthened by suppressing the vaporization rate, the stability of the raw material deteriorates with time, and the vaporization property gradually decreases. It is inevitable that the composition in the thickness direction becomes inhomogeneous and the leakage current increases. Therefore, there is a strong demand for the development of a CVD raw material that can provide stable vaporization even when used many times or for a long time, and has good vaporization properties even at low temperature heating. is there.

The CVD raw material for an oxide-based dielectric thin film of the present invention has been made in order to solve the drawbacks of the conventional raw material used in the conventional CVD method. Or, it can be vaporized separately, and can be stably transported to the reaction part, with the aim of synthesizing with good reproducibility a dielectric thin film for a memory capacitor having good performance. Is what you do.

[0006]

Means for Solving the Problems The present inventors have proposed a solid DP widely used in the conventional CVD method as described above.
As a result of a detailed study of the vaporization properties of M compounds and the like, it was found that among these compounds, particularly, alkaline earth metals such as Ba and Sr and solid compounds such as Pb and Ti have poor aging stability and vaporization properties. Was found. Therefore, when an oxide dielectric film containing an oxide of these metals as a main component is formed by a CVD method, it is difficult to control the composition to an intended composition, particularly for a multi-component dielectric film, or it is difficult to continuously control the composition. It was found that it was inevitable that the film could not be formed. Therefore, the present inventors dissolved these compounds in a solvent containing tetrahydrofuran as a main component that can stably exist for a long time to form a single solution, which was heated and vaporized at a relatively low temperature without thermal decomposition. By doing so, it has been found that the controllability of the composition is improved, and the dielectric film having desired characteristics can be continuously formed with good reproducibility, and the present invention has been completed. In particular, the inventors of the present invention use the liquid raw material of the present invention in forming a multi-component oxide-based dielectric thin film, thereby significantly improving the reproducibility of film formation when forming a film continuously. It has been found that when a dielectric film using the raw material of the present invention is used for a memory capacitor in order to improve the performance, the performance is dramatically improved as compared with the conventional one.

The present inventors have also made detailed studies on various organic solvents other than tetrahydrofuran with respect to their dissolving ability to a raw material for synthesizing a dielectric thin film comprising this solid organometallic compound, the vaporization property of the solution, and long-term stability. investigated. As a result, there were many solvents capable of dissolving the solid raw material satisfactorily. However, when an organic metal compound which is a raw material compound for a dielectric film, such as tetrahydrofuran, was dissolved to form a solution, good heat vaporization properties and aging were obtained. Could not be found any other with good stability.

Such a CVD raw material is used for synthesizing a multi-component oxide-based dielectric thin film, and is composed of an organometallic compound containing Pb and an organometallic compound containing Ti.
A liquid raw material comprising an organometallic compound containing r and at least one organometallic compound dissolved in tetrahydrofuran, which is capable of obtaining a stable and reproducible vaporized state by heating, and a conventional method. The use of the same raw material, which was impossible at all, many times did not cause any decrease in vaporization.

That is, the present invention relates to a lead material for a lead titanate-based dielectric thin film obtained by dissolving an organometallic compound containing Pb and an organometallic compound containing Ti in a solvent containing tetrahydrofuran.

The present invention also provides a lead titanate-based dielectric thin film obtained by dissolving an organometallic compound containing Pb, an organometallic compound containing Ti, and an organometallic compound containing Zr in a solvent containing tetrahydrofuran. It relates to a CVD raw material.

[0011] The CVD raw material can take a form composed of two or three types of solutions obtained by dissolving an organometallic compound alone in a solvent containing tetrahydrofuran.

The organic metal compound may be a metal acetylacetonate, dipivaloylmethanato, alkoxide, hexafluoroacetylacetonate, pentafluoropropanoylpivaloylmethanato, cyclopentadienyl or a derivative thereof. It is preferable that the number of species is two or more.

Further, it is preferable that the organometallic compound is a metal dipivaloyl methanate compound.

Further, the memory capacitor of the present invention comprises:
A dielectric film is formed as a memory capacitor by forming a film using a CVD method using a lead titanate-based dielectric thin film CVD raw material in which the metal compound is dissolved in tetrahydrofuran or a solvent containing tetrahydrofuran. is there.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The tetrahydrofuran used in the present invention has a low boiling point and can dissolve various organometallic compounds well. For this dissolving ability,
It is believed that this is due to properties such as tetrahydrofuran having a relatively large dielectric constant. The solution in which the organic metal is dissolved exhibits good vaporizability even when heated at a temperature lower than the vaporization temperature of the raw material organic metal compound itself, and the raw material compound is stably sent to the reaction section without being decomposed. It is considered something to do. further,
Even if the same raw material of the present invention is used many times, the vaporizability is not reduced at all, so that tetrahydrofuran forms a certain bond with the organometallic compound to prevent its deterioration over time and maintain its long-term stability. It is presumed to form.

[0016]

【Example】

[Example 1] An experiment for investigating the vaporizability of the raw material of the present invention was conducted using a normal hot wall type CVD apparatus. As the raw material compounds, particularly for Sr and Ba, which are not good in vaporization and stability, their acetylacetonates are used, and these are added in tetrahydrofuran at a concentration of 0.1%.
Two solutions dissolved at a concentration of 3 mol% were prepared. Amount of strontium oxide and barium oxide deposited on magnesium oxide substrate by their continuous vaporization times during heating at 220 ° C and their deposition on the same substrate at vaporization temperatures of every 20 ° C in the range of 180-240 ° C The amount was determined by the gravimetric method. In each case, it was confirmed by X-ray diffraction that the deposit was a film of an oxide of Sr or Ba.

For comparison, a solution prepared by dissolving the same starting compound in methanol or acetone was used instead of tetrahydrofuran using the same apparatus and film forming conditions as described above. Further, a solid raw material organometallic compound not using an organic solvent was directly subjected to the CVD method, and the amounts of Sr and Ba oxides deposited on the magnesium oxide substrate were determined in the same manner as above and compared. Tables 1 to 4 show these results.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

As is clear from Tables 1 and 3, when the CVD raw material of the present invention was used, compared with the conventional solid raw material organometallic compound and methanol and acetone solutions, the same heating temperature was used. In the first vaporization, an oxide film deposition of 20 times or more was obtained. In addition, a stable deposition amount was obtained with the raw material of the present invention even when film formation was performed by continuous vaporization, whereas the deposition amount of the oxide film was significantly increased with other raw materials as the number of times of vaporization increased. It has dropped. Further, as is clear from Tables 2 and 4, when the raw material of the present invention is used at any temperature, the deposition of an oxide film is far superior to that of the others due to its good vaporization. The quantity was obtained.

Further, under the same conditions as in Tables 1 and 3, 10
The deposition amount due to continuous vaporization more than once was investigated. As a result, in the case of the conventional solid raw material organic compound, methanol solution, and acetone solution, deposition by vaporization of the raw material did not occur at all by heating about 15 times. On the other hand, when the raw material of the present invention is used, the deposition amount of the oxide due to the vaporization of the CVD raw material does not fluctuate at all even when the film formation is repeated 20 times or more. The same was true until all the materials were gone.

Example 2 Using the same CVD apparatus as in Example 1, Pb dipivaloyl methanate, Zr dipivaloyl methanate and Ti dipivaloyl methanate were used as starting compounds, and these were mixed in tetrahydrofuran. This was dissolved to obtain a material solution of the present invention. At this time, the atomic ratio of each metal atom in the raw material compound was set to Pb: Zr: Ti = 2.2: 1: 1, and the concentration was adjusted to 0.4 mol% in the entire solute. Next,
An experiment for investigating the vaporizability of the present invention was conducted in the same manner as in Example 1. That is, the deposition amount of the PZT-based dielectric oxide on the platinum substrate based on the number of continuous vaporizations at the time of heating at 200 ° C. and the deposition amount on the same substrate at the vaporization temperature of every 20 ° C. in the range of 180 to 240 ° C. are obtained. Was. In each case, it was confirmed by X-ray diffraction that the deposit was a PZT-based oxide film.

For comparison, a solution prepared by dissolving the same organometallic compound in methanol or acetone at the same concentration instead of tetrahydrofuran using the same apparatus and film forming conditions as described above, The raw material organometallic compound is directly subjected to the CVD method, and PZT
The amount of the dielectric oxide deposited on the platinum substrate was determined in the same manner as described above and compared. Tables 5 and 6 show these results.

[0026]

[Table 5]

[0027]

[Table 6]

As is clear from Table 5, when the raw material of the present invention was used, the oxide dielectric film was 10 times or more in the first vaporization as compared with the conventional raw material and the cases of methanol solution and acetone solution. Was obtained. In addition, the raw material of the present invention obtained a very stable deposition amount even when continuous vaporization was performed in the same manner as in Example 1, whereas the other raw materials produced oxides with increasing the number of times of vaporization two or more times. The deposition amount of the film was greatly reduced, and when the number of times of vaporization was repeated more than 15 times, no vaporization occurred, and the deposition amount became zero. Also, as is clear from Table 6, when the CVD raw material of the present invention was used at any temperature, PZT which was much superior to other materials due to its good vaporization property was obtained.
The deposition amount of the base oxide film was obtained.

[Embodiment 3] A strontium titanate-based oxide dielectric film, SrTiO, was formed using an ordinary hot wall type CVD apparatus having a ternary raw material heating system.
An experiment was conducted to synthesize ₃ on a magnesium oxide substrate and evaluate its characteristics as a memory capacitor. As a raw material compound, Sr acetylacetonate was dissolved in tetrahydrofuran at a concentration of 0.2 mol% to obtain a CVD raw material of the present invention, and for Ti, Ti isopropoxide was used as a raw material compound. As the film forming conditions, each CVD raw material was bubbled with argon as a carrier gas and sent to a vaporizer. Sr was set to 195 ° C. and Ti was set to 190 ° C. as a vaporization temperature. The reaction gas is oxygen, the pressure inside the reactor (furnace) is 8 Torr,
The reaction was performed for about 10 minutes while maintaining the substrate temperature at about 690 ° C.
After the reaction, the mixture was allowed to cool to room temperature in an oxygen stream, whereby an oxide dielectric film having a thickness of about 50 nm according to the present invention was obtained. The crystallinity was investigated by X-ray diffraction, and the dielectric constant and the leak current density when a DC voltage of 1.65 V was applied were measured as the capacitor characteristics.

For comparison, a conventional organic metal compound, Sr acetylacetonate and Ti isopropoxide, were used under the same film-forming conditions as described above, using the same CVD apparatus, and using an oxide-based dielectric material having the same composition. A body film was formed. However, since sufficient vaporization was not obtained particularly for Sr, the vaporization temperature was increased to 280 ° C., the compositions were adjusted, and a film was formed. As in the case of using the raw material of the present invention, the reaction was allowed to cool naturally to room temperature in an oxygen stream to obtain a film having a thickness of about 50 nm. This film was similarly evaluated for film quality and performance as a capacitor. Table 7 shows these results.
Shown in

[0031]

[Table 7]

As is clear from Table 7, the CVD of the present invention
When a raw material is used, a memory capacitor film having good performance can be formed by a CVD method even when heating at a lower temperature than in the case of a conventional raw material organometallic compound. In particular, as compared with a conventional film made of a raw material, it was possible to reduce the leak current by one digit or more with substantially the same film thickness. In addition, film formation was performed 10 times continuously under the same synthesis conditions as described above, and the production reproducibility of the film was examined. As a result, the film made of the CVD raw material of the present invention had both a relative dielectric constant and a leak current density of ± 10%. There was no large variation of 5% or less, and it was found that reproducibility was good. On the other hand, in the capacitor film according to the conventional method, both the relative dielectric constant and the leak current density showed a very large variation of about ± 50% with respect to the values in Table 7.

Example 4 Using the same CVD apparatus as in Example 1, Pb dipivaloyl methanate, Zr dipivaloyl methanate and Ti dipivaloyl methanate were used as raw material compounds, and Pb, Zr, Ti Each metal atomic ratio of 2.2:
The components were all dissolved in tetrahydrofuran so as to have a concentration of 0.55 mol% as a whole. The raw material of the present invention was sent to a vaporizer while bubbling with argon gas, and transported to a CVD reactor heated and vaporized at about 200 ° C. Magnesium oxide was used as the substrate, and the substrate temperature was set at about 640 ° C. Thus, a PZT-based oxide dielectric film was formed using the material of the present invention. The thickness of the formed film was 89 nm.

For comparison, a film was formed using a conventional solid raw material organometallic compound which was not dissolved in tetrahydrofuran. However, for the same reason as in Example 3, the set temperature of each raw material was about 25
It was kept at 0 ° C, 230 ° C and 210 ° C. The film thickness in this case is 150 nm
Met. Table 8 shows the characteristics of the two samples as capacitors.

[0035]

[Table 8]

As is clear from Table 8, similarly to the case of Example 3, the capacitor film using the oxide-based dielectric of the present invention was heated at a lower temperature than the conventional material. Regardless, the relative permittivity and the leak current density of the thin film are much better. Further, as in Example 3, film formation was performed 10 times continuously under the same film formation conditions, and the reproducibility of film formation was examined. No large variation was found at both the current densities of ± 5% or less, and it was found that the reproducibility was better as compared with the variation of about ± 50% of the film according to the conventional example.

Example 5 Barium strontium titanate was prepared using the same CVD apparatus as in Example 1 and using organometallic compounds of Sr dipivaloyl methanate, Ba dipivaloyl methanate and Ti dipivaloyl methanate. An attempt was made to form a base oxide dielectric. All of the three organometallic compounds are dissolved in tetrahydrofuran so that the concentration of the entire solute becomes 0.08 mol% (the atomic ratio of Sr, Ba, and Ti is 0.5: 0.5: 1.0). Raw materials were prepared. This solution was heated to about 215 ° C. and vaporized as it was. Use magnesium oxide as the substrate and reduce the substrate temperature to about
Sr _0.5 Ba _0.5 T having a thickness of 30 nm set at 675 ° C.
An oxide dielectric film of iO ₃ was formed.

For comparison, a film was formed using a conventional organometallic compound which was not dissolved in tetrahydrofuran. The film thickness in this case was 70 nm. However, Example 3
For the same reason as described above, the heating temperatures of the Sr and Ti raw materials were maintained at about 285 ° C. and 280 ° C., respectively, which were higher than in the case of the present invention. Table 9 shows the characteristics of the two samples of the present invention and the conventional example as capacitors.

[0039]

[Table 9]

As is clear from Table 9, as in the case of Examples 3 and 4, the capacitor film using the oxide-based dielectric formed by using the raw material of the present invention is larger than that of the conventional raw material. Despite the low-temperature heating, the relative permittivity and the leak current density of the thin film are much better. Further, the film formation was repeated 10 times under the same film formation conditions in the same manner as in Example 1, and the reproducibility of the film was investigated. However, there was no large variation of ± 5% or less, and it was found that the reproducibility was better as compared with the variation of about ± 50% of the conventional film.

Of the three organometallic compounds used above, two of Sr dipivaloyl methanate and Ti dipyrrovale methanate were added to tetrahydrofuran so that the total solute concentration was 0.1 mol% (Sr and Ti). And a solution in which the atomic ratio of Ba is 1: 1) and two kinds of Ba dipivaloyl methanate and Ti dipivaloyl methanate are dissolved in tetrahydrofuran so that the concentration of the entire solute is 0.2 mol% (Ba and T).
Solutions were prepared so that the atomic ratio of i was 1: 1), and the oxide dielectric films of SrTiO ₃ and BaTiO ₃ were each formed to a thickness of 50 nm under the same conditions as the aforementioned Sr _0.5 Ba _0.5 TiO _3. The film was formed with a thickness.

For comparison, a conventional organometallic compound not dissolved in tetrahydrofuran was used to form a film under the same conditions as described above, and the characteristics of each capacitor are shown in Table 10.

[0043]

[Table 10]

As is clear from Table 10, as in the cases of Examples 3 and 4, the capacitor film using the oxide-based dielectric formed using the raw material of the present invention is more effective than the conventional raw material. Despite the low-temperature heating, the relative permittivity and the leak current density of the thin film are much better. Further, the film formation was repeated 10 times under the same film formation conditions in the same manner as in Example 1, and the reproducibility of the film was investigated. However, there was no large variation of ± 5% or less, and it was found that the reproducibility was better as compared with the variation of about ± 50% of the conventional film.

Example 6 Barium strontium titanate-based oxidation was performed using the same CVD apparatus as in Example 1 and using organometallic compounds of Sr dipivaloyl methanate, Ba dipivaloyl methanate and Ti isopropoxide. An attempt was made to form a dielectric material. At this time, Sr and Ba were dissolved in the above-mentioned organometallic compound in tetrahydrofuran at a concentration of 0.35 mol% to obtain two kinds of raw materials of the present invention. This was bubbled with an argon gas as a carrier gas, sent into a vaporizer, vaporized while being heated to about 210 ° C., and transported to a reactor. Since Ti isopropoxide is a liquid raw material compound, it was heated to about 180 ° C. and vaporized as it was. Magnesium oxide was used as the substrate, the substrate temperature was set to about 655 ° C., and an oxide dielectric film having a thickness of 45 nm was formed.

For comparison, a film was formed using a conventional raw material organometallic compound which was not dissolved in tetrahydrofuran. The film thickness in this case was 125 nm. However, for the same reason as in Example 3, the heating temperatures of the Sr and Ti raw materials were maintained at about 235 ° C. and 255 ° C., respectively, which were higher than in the case of the present invention. Table 11 shows the characteristics of the two samples as capacitors.

[0047]

[Table 11]

As is clear from Table 11, as in the case of Examples 3, 4 and 5, the capacitor film using the oxide-based dielectric formed by using the material of the present invention is made of the conventional material. Despite heating at a lower temperature, the relative permittivity and leak current density of the thin film are much better.
Further, the film formation was repeated 10 times under the same film formation conditions in the same manner as in Example 1, and the reproducibility of the film was investigated. However, there was no large variation of ± 5% or less, and it was found that the reproducibility was better as compared with the variation of about ± 50% of the conventional film.

Further, all of the three kinds of organometallic compounds used in the above were added to tetrahydrofuran at a concentration of 0.8 wt.
It was dissolved so as to have a molar percentage (Sr, Ba, Ti in an atomic ratio of 1: 1: 2) to produce a one-part CVD raw material of the present invention. Using this solution, a barium strontium titanate-based oxide dielectric was formed in the same manner as described above, and its capacitor performance was evaluated. As a result, it was found that it had almost the same good characteristics as in Table 11.

In Examples 3, 4 and 5, the main reason why the capacitor performance of the conventional oxide-based dielectric film made of the raw material organometallic compound is not good is that the raw material compound is hardly vaporized by heating and is relatively high. It is considered that the starting compound was decomposed due to the heating at the temperature, and it was difficult to stably transport the starting compound to the reaction section. That is, it is presumed that the main reason why the properties of the sample made of these conventional materials as a memory capacitor film is not good is that the composition during the film formation is inhomogeneous due to the unstable transport of each material.

Using the raw material of the present invention and conducting the same study as in Examples 1 to 5, the synthesis of thin films of dielectric materials such as PLZT, barium titanate, tantalum oxide, lead titanate, bismuth titanate and the like was performed. This was performed many times using the raw materials of the constituent elements. As a result, it was found that, in each case, a dielectric film having better capacitor performance can be produced with good reproducibility using the raw material of the present invention as compared with the conventional raw material, as in the above-described embodiments.

With respect to the conventional solvent used in the present invention for dissolving the organometallic compound, various kinds of solvents were investigated by the same study as in Examples 1 and 2, and the solvent was used at a low temperature such as tetrahydrofuran used in the present invention. The effect of improving the vaporization property by heating, the effect of stabilizing the material by using it many times, and the stable vaporization effect did not appear. Therefore, in the present invention, it is necessary to use tetrahydrofuran as the organic solvent for dissolving the organometallic compound. The organic solvent in the present invention may be any solvent containing 90% by weight or more of tetrahydrofuran, preferably a solvent containing 95% by weight or more of tetrahydrofuran, and more preferably a solvent containing only tetrahydrofuran. If the content of tetrahydrofuran is less than 90% by weight, it becomes difficult to obtain desired heat vaporization properties and stability over time. The solvent to be mixed may be any solvent that is compatible with tetrahydrofuran, and examples thereof include alcohols such as methanol, ethanol, and propanol; ketones such as acetone, dimethyl ketone, and methyl ethyl ketone; and benzene. The details of the mechanism of action of tetrahydrofuran are not clear at this time, but various experimental studies have shown that it can be added to organometallic compounds to form some bonds, resulting in the formation of adducts with excellent vaporizability. Presumed.

Further, in the present invention, a single organometallic compound may be dissolved in tetrahydrofuran as in Examples 1 and 3, or a multi-organic organometallic compound may be dissolved in tetrahydrofuran as in Examples 2, 4 and 5. Sometimes, it can be dissolved to form a one-part solution. Example 6 shows that both forms have the same effect. At this time, the concentration of the organometallic compound in tetrahydrofuran cannot be uniformly defined because the solubility varies depending on the substance, but it is generally 0.001 to 1
It can be arbitrarily selected within the range of 0 mol%. In this case, in each case, the effect of promoting the vaporization of the raw material appears as shown in the examples. The recommended value of the concentration is appropriately about 0.1 to 1 mol% as shown in the examples, but there is no inconvenience even if it is out of this range.

Further, it was confirmed by various experiments similar to the above-mentioned examples that as the raw material compound used in the present invention, an organometallic compound of a dielectric oxide widely used for a memory capacitor can be used. However, in the case of a compound in which a metal atom was bonded to an organic group via an oxygen atom as used in Examples, it was confirmed that the above-mentioned effect of tetrahydrofuran was more effectively exerted. Therefore, in order to meet this condition, in the present invention, metal acetylacetonato, dipivaloylmethanato, alkoxide, hexafluoroacetylacetonato, pentafluoropropanoylpivaloylmethanato, cyclopentadienyl and derivatives thereof are used. Etc. can be used. Alkoxides include methoxide, ethoxide,
Isopropoxide and the like can be used. It was confirmed by the same experiment as in the examples that when any of these was used, the above-mentioned good stability effect with time and the effect of promoting vaporization were exhibited by dissolving in tetrahydrofuran to obtain a solution raw material. Further, in this case as well, it was found that when the metal atom was Pb, Ti, Zr, or an alkaline earth metal, the performance of the formed dielectric film as a capacitor was excellent. It was also found that similar performance was obtained with metal atoms of La, Ta, and Bi. Sr, Ba, and the like can be used as the alkaline earth metal.

However, when the metal element of the organometallic compound is at least one selected from Pb, Ti, Zr and alkaline earth metal as shown in Examples 1 to 6, It was confirmed by experiments that the effects of the present invention were improved and the formed capacitor film exhibited good performance. In particular, when the metal atoms are Pb and Ti, and the dipivaloylmethanato compounds are used as the dipivaloylmethanato compounds, particularly Pb, Ti and Zr are used as the dipivaloylmethanato compounds, the stability of the raw material of the present invention over time It was confirmed that the gasification effect and the good vaporization promotion effect were more greatly exhibited.

[0056]

As described above, the lead material for a lead titanate-based dielectric thin film according to the present invention obtained by dissolving an organometallic compound containing Pb and an organometallic compound containing Ti in a solvent containing tetrahydrofuran. For example, a stable deposition over time can be obtained by heating and vaporizing a large number of times, and a good amount of deposition by vaporization can be obtained by heating at a low temperature. There is an effect that the formed memory capacitor film has good performance.

Further, an organometallic compound containing Pb and Ti
And the organometallic compound containing Zr are dissolved in a solvent containing tetrahydrofuran, and the lead material for a lead titanate-based dielectric thin film of the present invention is good even by heating it many times. A stable vaporization effect over time and a vaporization promotion effect are exhibited by low-temperature heating, so that a dielectric film formed by the CVD method can be more excellent in performance as a capacitor, and the material can be effectively used to achieve a constant quality. Can be obtained at low cost.

When the above-mentioned organometallic compound is composed of two or three kinds of solutions each independently dissolved in a solvent containing tetrahydrofuran, even if it is heated a number of times, it has a good vaporization effect over time and a low temperature heating. Also, the effect of promoting vaporization is exhibited, and the dielectric film formed by the CVD method is more excellent in performance as a capacitor.

Examples of the organometallic compound include acetylacetonate of Pb, Ti or Zr, dipivaloyl methanate, alkoxide, hexafluoroacetylacetonate, pentafluoropropanoyl pivaloyl methanate,
When at least one of cyclopentadienyl or a derivative thereof is used, a stable vaporization effect over time which is excellent even by heating many times and a vaporization promoting effect even by low-temperature heating are exhibited, and the dielectric material formed by the CVD method is used. A product having a stable quality in the performance of the body film as a capacitor can be obtained.

When the dipivaloyl methanato compound of Pb, Ti and Zr is used as the organometallic compound,
A good vaporization effect over time and a good vaporization promotion effect even by low-temperature heating appear even when heating and forming many times, so that the performance of the dielectric film formed by the CVD method as a capacitor is more excellent, and Quality products can be obtained at low cost.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁷ Identification code FI H01L 27/04 (72) Inventor Hisao WATAI 8-1-1 Tsukaguchi Honcho, Amagasaki City, Mitsubishi Electric Corporation References JP-A-5-271253 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 16/40 C01G 23/00 C01G 25/00 C30B 29/32 H01L 21/822 H01L 27/04 CA (STN)

Claims (6)

(57) [Claims] 1. A lead titanate-based dielectric thin film CVD raw material obtained by dissolving an organometallic compound containing Pb and an organometallic compound containing Ti in a solvent containing tetrahydrofuran. 2. A lead titanate-based dielectric thin film CVD raw material obtained by dissolving an organometallic compound containing Pb, an organometallic compound containing Ti, and an organometallic compound containing Zr in a solvent containing tetrahydrofuran. 3. Two or three organic metal compounds each independently dissolved in a solvent containing tetrahydrofuran.
3. The CVD raw material for a lead titanate-based dielectric thin film according to claim 1, comprising a seed solution. 4. The organic metal compound is one of a metal acetylacetonate, dipivaloylmethanato, alkoxide, hexafluoroacetylacetonate, pentafluoropropanoylpivaloylmethanato, cyclopentadienyl or a derivative thereof or 4. The CVD raw material for a lead titanate-based dielectric thin film according to claim 1, wherein the raw material is at least two kinds. 5. The CVD raw material for a lead titanate-based dielectric thin film according to claim 1, wherein the organometallic compound is a dipivaloylmethanato-based compound. 6. A lead titanate film formed by a CVD method using the raw material for a lead titanate-based dielectric thin film according to claim 1, wherein the raw material is used. A memory capacitor formed from a dielectric film.