JPH10195086A - Organic lead compound and raw material solution for metalorganic chemical vapor deposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound useful as a raw material for metalorganic chemical vapor deposition, having a strong basic ligand of linear branched amine, excellent in vaporizing property and vaporizing stability because of stabilizing a complex in which the ligand coordinates on a metal, and capable of forming a lead-based thin film at a high film-forming rate. SOLUTION: This compound is expressed by the formula (R is methyl or tertbutyl; A is ethylenediamine, tetraethylenediamine or tetraethylenepentamine), e.g. bis(1,1,1,5,5,5-hexamethyl-2,4-pentanedionato)lead.bis(ethylenediamine). The compound is obtained by adding dipivaloylmethane or acetylacetone to a metallic lead in an organic solvent such as toluene or xylene, reacting under heat- refluxing, adding ethylenediamine, tetraethylenediamine or tetraethylenepentamine and reacting under heat-refluxing. A film-forming rate can be increased by using the objective compound dissolved in an organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic lead compound and a raw material solution for metalorganic chemical vapor deposition, and more particularly to a method for producing a lead-based thin film such as lead oxide for producing a ferroelectric memory device of a semiconductor device by metalorganic chemical vapor deposition. Method (Metalorganic Chemical Va)
por Deposition: Hereinafter referred to as “MOCVD method”. The present invention relates to an organic lead compound and a raw material solution for organometallic chemical vapor deposition, which are suitable for use as a raw material for vapor deposition when formed by the method (1).

[0002]

2. Description of the Related Art Conventionally, as a vapor deposition raw material used for forming a lead oxide thin film for manufacturing a ferroelectric memory device of a semiconductor device by MOCVD, a bis (1,1,1) represented by the following structural formula is used. , 5,5,5-hexamethyl-2,4-pentanedionato) lead (hereinafter referred to as "Pb
(DPM) 2 ". )It has been known.

[0003]

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[0004]

The above-mentioned conventional organic lead compound: Pb (DPM) 2 has poor vaporization characteristics and generates residues during vaporization. Further, when this organic lead compound is used as it is as a raw material for metal organic chemical vapor deposition, there is a problem that the reproducibility of film formation is poor due to a large deterioration of vaporization characteristics with time.

The present invention solves the above-mentioned conventional problems, and is a novel organic compound which is excellent in vaporization characteristics and vaporization stability and is useful as a raw material for metal organic chemical vapor deposition capable of forming a lead-based thin film at a high film formation rate. It is an object of the present invention to provide a lead compound and a raw material solution for metal organic chemical vapor deposition.

[0006]

Means for Solving the Problems The organolead compound of the present invention is represented by the following general formula (I).

[0007]

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(In the above general formula (I), R represents a methyl group or t
And A represents ethylenediamine, tetraethylenediamine or tetraethylenepentamine. The organolead compound of the present invention represented by the general formula (I) has a strong basic linear or branched amine ligand A, and this ligand stabilizes a complex coordinated to a metal. Since it is vaporized, it has excellent vaporization characteristics and vaporization stability, and there is no problem of residue during vaporization.

Although this organic lead compound can be used as it is as a raw material for metal organic chemical vapor deposition, it is difficult to obtain a high film forming rate.

By dissolving the organic lead compound in an organic solvent and using it as a raw material for metal organic chemical vapor deposition, the film formation rate can be increased.

The raw material solution for metalorganic chemical vapor deposition of the present invention comprises:
The organic lead compound of the present invention represented by the general formula (I) or the conventionally known organic lead compound represented by the structural formula is dissolved in an organic solvent.

With this raw material solution for metalorganic chemical vapor deposition, a stable film can be formed at a high film forming rate while maintaining a stable structure without increasing the amount to a nonvolatile amount.

In the raw material solution for metalorganic chemical vapor deposition of the present invention, it is preferable to use an oxygen-containing cyclic compound, especially tetrahydrofuran, dimethyltetrahydrofuran, or dimethylfuran as an organic solvent, since the solution viscosity is low and the solution has an appropriate solubility. preferable.

[0014]

Embodiments of the present invention will be described below.

The organic lead compound of the present invention is a bis (1,1,1,5,5,5-hexamethyl-2,4-pentanedionato) lead / bis (ethylenediamine) (hereinafter referred to as bis (ethylenediamine)) represented by the following structural formula. Abbreviated as "Pb (DPM) 2 (en) 2"), bis (2,4-pentanedionato) lead bis (ethylenediamine) (hereinafter referred to as "P
b (acac) 2 (en) 2 ". ), Bis (1,1,1,5,5,5-hexamethyl-2,4-pentanedionato) lead bis (tetraethylenediamine) (hereinafter referred to as “Pb (DPM) 2 (te
en) 2 ". ), Bis (2,4-pentanedionato) lead / bis (tetraethylenediamine) represented by the following structural formula (hereinafter referred to as “Pb (acac) 2 (tee)
n) 2 ". ), Bis (1,1,1,5,5,5-hexamethyl-2,4-pentanedionato) lead bis (tetraethylenepentamine) (hereinafter referred to as "Pb (DPM) 2 (Tetralan) 2 "
Abbreviated. ) Or bis (2,
4-pentanedionato) lead / bis (tetraethylenepentamine) (hereinafter referred to as “Pb (acac) 2 (tetrae)
n) 2 ". ).

[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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Such an organic lead compound of the present invention can be prepared by adding dipivaloylmethane or acetylacetone to metallic lead in an organic solvent such as toluene, xylene, or benzene, as shown in the synthesis examples described below, and heating under reflux. After the reaction, ethylenediamine, tetraethylenediamine or tetraethylenepentamine is further added, and the mixture is heated and refluxed to cause a reaction. The reaction solution is concentrated under reduced pressure to obtain a product, which can be produced.

The organic lead compound of the present invention can be directly vaporized and used as a raw material for metal organic chemical vapor deposition. However, from the viewpoints of film forming speed and composition controllability, the organic lead compound is preferably used after being dissolved in an organic solvent. Is preferred.

The raw material solution for organometallic chemical vapor deposition of the present invention comprises:
The organic lead compound of the present invention or the organic lead compound Pb (DPM) 2 represented by the following structural formula is preferably
An organic lead compound concentration of 0.05 to 0.5 M (mol / liter) is added to an organic solvent such as an oxygen-containing cyclic compound, more preferably one or two or more selected from the group consisting of tetrahydrofuran, dimethyltetrahydrofuran and dimethylfuran. ).

[0025]

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The use of an oxygen-containing cyclic compound such as tetrahydrofuran, dimethyltetrahydrofuran, or dimethylfuran coordinates the lead atom of the organic lead compound to stabilize the complex, thereby maintaining the volatility of the organic lead compound stably. Thus, stable film formation can be performed at a high film formation rate. When the concentration of the organic lead compound in the raw material solution for metal organic chemical vapor deposition is less than 0.05 M, the concentration is too low and the film formation efficiency is poor,
If it exceeds 0.5M, the film formation efficiency is poor and the film has poor morphology.

The organic lead compound and the starting material solution for metalorganic chemical vapor deposition of the present invention can be prepared in the same manner as the conventional starting material for metalorganic chemical vapor deposition by MOCV such as thermal decomposition type MOCVD.
It can be used as a raw material for depositing lead-based thin films such as lead oxide by the D method.

That is, in order to form a lead oxide thin film by MOCVD using the raw material solution for metal organic chemical vapor deposition of the present invention, for example, as shown in a schematic explanatory view of FIG. On the other hand, the substrate 3 is placed on the substrate 2, and on the other hand, the vapor deposition raw material 5 composed of the above-mentioned organic lead compound solution in the raw material container 4 is supplied to the vaporizer 6 by a carrier gas such as Ar and H ₂ from the pipes 11 and 12 and vaporized. At the same time, an oxidizing gas such as O ₂ , N ₂ O, or ozone is introduced into the vaporizer 6 as a reaction gas from a pipe 13, and the vapor of the deposition material 5 and the reaction gas are introduced into the reaction furnace 1, and the heating substrate is heated. A lead oxide thin film is deposited on 3. In the figures, V ₁ , V ₂ , V ₃ , V ₄ , and V ₅ are valves, 7A, 7B, and 7C are flow meters, 8 is a metering pump, 9 is a pressure gauge, 10 is a vacuum pipe, and 11 is a trap. Tube.

When the organic lead compound of the present invention is used as a raw material for metal organic chemical vapor deposition without dissolving in a solvent, the organic lead compound is put into a vaporizer 6 and directly vaporized, and the reaction mixture is supplied to a reactor by a carrier gas. 1 may be supplied.

The raw material solution for metal organic chemical vapor deposition of the present invention may be a solution containing two or more kinds of the organic lead compounds represented by the structural formulas (1) to (4).

[0031]

The present invention will be more specifically described below with reference to Synthesis Examples, Examples and Comparative Examples.

Synthesis Example 1 Synthesis of Pb (DPM) 2 (en) 2 100 g of anhydrous toluene was added to 10 g (0.048 g atomic equivalent) of metallic lead to form a suspension. further,
17. To this suspension was added 2 equivalents of dehydrated and purified dipivaloylmethane with respect to metallic lead while stirring vigorously.
After adding 8 g, the mixture was heated under reflux for 24 hours. After the temperature of the reaction solution was returned to room temperature, 2 equivalents of ethylenediamine was added to lead metal, and the mixture was further heated under reflux for 5 hours. The obtained reaction solution was concentrated under reduced pressure (100 ° C., 10 torr) to give a white solid as the organolead compound of the present invention having the structural formula: Pb (DP
M) 2 (en) 2 (melting point: around 100 to 130 ° C.) was synthesized.

The obtained organolead compound was identified by IR, N
It was performed by MR, MS and elemental analysis. The identification results are as follows.

IR (cm ^-1 ); 3200, 3000, 2900, 230
0, 1600, 1460, 1360, 1300, 1250, 1220, 1130, 900,
880, 840, 800, 750 ¹ H-NMR δ (ppm); 6.4 (CH), 1.2 (-C (CH _{3) 3)} ,
_{2.7 (-CH 2 -), 1.1} (NH) MS (m / e); 694

[0035]

[Table 1]

Synthesis Example 2: Pb (acac) 2 (en) 2
The synthesis was performed in the same manner as in Synthesis Example 1 except that acetylacetone was used instead of dipivaloylmethane, and the organic lead compound of the present invention having the structural formula: Pb (acac) 2 was obtained as a white solid.
(En) 2 (melting point: around 100 to 150 ° C.) was synthesized.

The results of identification of this organic lead compound are as follows.

IR (cm ^-1 ); 3200, 2900, 3050, 170
0, 1630, 1600, 1420, 1360, 1250, 1160, 1000, 950,
920, 900, 840, 780, 640 ¹ H-NMR δ (ppm); 5.4 (CH), 1.5 (-CH ₃₎ , 2.6 (-
CH _2- ), 1.0 (NH) MS (m / e); 526

[0039]

[Table 2]

Synthesis Example 3: Pb (DPM) 2 (teen)
Synthesis of 2 Except that tetraethylenediamine was used in place of ethylenediamine, the same procedure as in Synthesis Example 1 was carried out, and the organic lead compound of the present invention having a structural formula of Pb (DPM) 2 was obtained as a white solid.
(Teen) 2 (melting point: around 80-100 ° C.) was synthesized.

The identification results of this organic lead compound are as follows.

IR (cm ^-1 ); 3000, 2900, 2300, 160
0, 1460, 1360, 1300, 1250, 1220, 1130, 1020, 900,
880, 840, 800, 750 ¹ H-NMR δ (ppm); 6.3 (CH),
2 (-C (CH3 _{) 3)} , 2.5 ( _-C2H5) ,
_{1.05 (-CH 2-) MS (m} / e); 918

[0043]

[Table 3]

Synthesis Example 4: Pb (acac) 2 (tee
n) Synthesis of 2 The same procedure as in Synthesis Example 3 was carried out except that acetylacetone was used instead of dipivaloylmethane, and the organolead compound of the present invention having the structural formula: Pb (acac) 2 was obtained as a white solid.
(Teen) 2 (melting point: around room temperature) was synthesized.

The identification results of this organic lead compound are as follows.

IR (cm ^-1 ); 2900, 3050, 1700, 16
30, 1600, 1420, 1360, 1300, 1250, 1220, 1160, 102
0, 1000, 950, 920, 900, 840, 780, 640 ¹ H-NMR δ (ppm); 5.9 (CH), 1.18 (-C (CH ₃ ) ₃ ),
_{2.3 (-C 2 H 5),} 1.1 (-CH 2-) MS (m / e); 751

[0047]

[Table 4]

Synthesis Example 5: Pb (DPM) 2 (tetra
en) Synthesis of 2 The same procedure as in Synthesis Example 1 was carried out except that tetraethylenepentamine was used instead of ethylenediamine, and the organolead compound of the present invention having a structural formula of Pb (DPM) was obtained as a white solid.
2 (tetrane) 2 (melting point: around room temperature) was synthesized.

The identification results of this organic lead compound are as follows.

IR (cm ^-1 ); 3500, 3200, 3300, 300
0, 2900, 2300, 1650, 1600, 1590, 1460, 1360, 1300,
1250, 1220, 1130, 1020, 900, 880, 650, 840, 800,
750 ¹ H-NMR δ (ppm); 6.1 (CH), 1.1 (-C (CH _{3) 3)} ,
1.3 (NH), 2.8 (-CH 2 -) MS (m / e); 952

[0051]

[Table 5]

Synthesis Example 6: Pb (acac) 2 (tetra
aen) 2 Synthesis was carried out in the same manner as in Synthesis Example 5 except that acetylacetone was used instead of dipivaloylmethane, and the organolead compound of the present invention having a structural formula of Pb (acac) 2 was obtained as a white solid.
(Tetrane) 2 (melting point: around room temperature) was synthesized.

The identification results of this organic lead compound are as follows.

IR (cm ^-1 ); 3500, 3360, 3050, 297
0, 2880, 1700, 1650, 1630, 1595, 1470, 1420, 1380,
1365, 1250, 1220, 1200, 1160, 1023, 1020, 1000, 9
50, 920, 900, 795, 780, 750, 650 ¹ H-NMR δ (ppm); 5.7 (CH), 1.4 (-CH ₃₎ , 1.2 (N
_{-H), 2.7 (-CH 2 -} ) MS (m / e); 785

[0055]

[Table 6]

Synthesis Example 7: Synthesis of Pb (DPM) 2 100 g of anhydrous toluene was added to 10 g (0.048 g atomic equivalent) of metallic lead to prepare a suspension. further,
To this suspension, while stirring vigorously, dehydrated and purified dipivaloylmethane was added in an amount of 27.8 equivalents to metal.
After adding g, the mixture was heated under reflux for 24 hours. This reaction solution was concentrated under reduced pressure (100 ° C., 10 torr) to synthesize a conventional organic lead compound Pb (DPM) 2 having a structural formula.

Examples 1 to 6 and Comparative Example 1 (Evaluation of vaporization characteristics and film formation test) In order to evaluate the vaporization characteristics of each of the organic lead compounds obtained in Synthesis Examples 1 to 7, a thermogravimetric curve (elevation curve) was used. Temperature rate 10 ° C / m
in, dry argon atmosphere), and the results are shown in FIGS.

As is clear from the results shown in FIGS. 2 to 8, the organolead compound of the present invention (FIGS.
Although it is possible to completely vaporize at a temperature of 50 to 350 ° C., about 10% of a residue is generated from the conventional organic lead compound (FIG. 8) at the end of vaporization. This indicates that the organic lead compound of the present invention has better thermal stability during vaporization than the conventional organic lead compound.

Examples 7 to 12, Comparative Example 2: Film formation test (solvent-free) Using each of the organic lead compounds obtained in Synthesis Examples 1 to 7, FIG.
(However, the organic lead compound was directly vaporized in the vaporization vessel 6 without using a solvent.)
According to the CVD method, lead oxide (PbO) under the following film forming conditions
A thin film was prepared, and the film thickness was measured every 10 minutes. The film thickness was measured from a cross-sectional SEM image of the film. Table 7 shows the measurement results.

Film-forming conditions Substrate: A Pt sputter-deposited film having a thickness of 1000 ° formed on a silicon substrate Temperature: 600 ° C. Reaction gas: oxygen Reaction gas flow rate: 1000 ccm Pressure: 700 Pa Carrier gas: helium Carrier gas flow rate: 500 ccm Temperature: 200 ° C

[0061]

[Table 7]

From Table 7, it is evident that the organic lead compound of the present invention has a smaller decrease in film forming rate with time and is superior in vaporization stability as compared with the conventional organic lead compound.

Examples 13 to 19: Film-forming test (tetrahydrofuran solution) Each of the organic lead compounds obtained in Synthesis Examples 1 to 7 was dissolved in tetrahydrofuran at a concentration of 0.2 M, and the apparatus shown in FIG. 1 was used. According to the thermal decomposition type MOCVD method, a lead oxide (PbO) thin film was prepared under the following film forming conditions.
The film thickness was measured every minute, and the results are shown in Table 8.

Film forming conditions Substrate: A Pt sputter-deposited film having a thickness of 1000 ° formed on a silicon substrate Temperature: 600 ° C. Reactive gas: Oxygen Reactive gas flow rate: 1000 ccm Pressure: 700 Pa Carrier gas: Helium Carrier gas flow rate: 500 ccm Container temperature: 220 ° C Raw material solution supply: 0.2 cc / min

[0065]

[Table 8]

Examples 20 to 26: Film formation test (dimethyltetrahydrofuran solution) A solution prepared by dissolving each of the organic lead compounds obtained in Synthesis Examples 1 to 7 in dimethyltetrahydrofuran at a concentration of 0.2 M was used as a raw material solution. Except for the above, a lead oxide (PbO) thin film was produced in the same manner as in Examples 13 to 19, and the film thickness was measured every 10 minutes. The results are shown in Table 9.

[0067]

[Table 9]

Examples 27 to 33: Film formation test (dimethylfuran solution) As the raw material solution, a solution prepared by dissolving each of the organic lead compounds obtained in Synthesis Examples 1 to 7 at a concentration of 0.2 M in dimethylfuran was used. Except for the above, a lead oxide (PbO) thin film was produced in the same manner as in Examples 13 to 19, and the film thickness was measured every 10 minutes. The results are shown in Table 10.

[0069]

[Table 10]

From Tables 8 to 10, it is found that the organolead compound of the present invention is dissolved in an organic solvent, and even a conventional organolead compound is dissolved in an organic solvent to obtain an organometallic chemical vapor deposition. As a raw material for use, it shows a high film formation rate, and it is clear that stable and efficient film formation can be performed.

[0071]

As described in detail above, according to the organolead compound and the raw material solution for organometallic chemical vapor deposition of the present invention, the MOCV
Method D enables stable and efficient deposition of lead-based thin films at high deposition rates, and is effectively used for producing lead-containing thin films useful as superconducting materials, ferroelectric materials, semiconductor thin film materials, etc. can do.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus for explaining a thermal decomposition type MOCVD method.

FIG. 2 shows an organolead compound Pb (DPM) 2 (e) of the present invention.
It is a graph which shows the thermogravimetric curve of n) 2.

FIG. 3 shows an organolead compound Pb (acac) 2 (e) of the present invention.
It is a graph which shows the thermogravimetric curve of n) 2.

FIG. 4 is an organolead compound Pb (DPM) 2 (te) of the present invention.
11 is a graph showing a thermogravimetric curve of (en) 2.

FIG. 5 is an organolead compound Pb (acac) 2 (t) of the present invention.
18 is a graph showing a thermogravimetric curve of E.en.2.

FIG. 6 is an organolead compound Pb (DPM) 2 (te) of the present invention.
5 is a graph showing a thermogravimetric curve of (Traen) 2.

FIG. 7 shows an organolead compound Pb (acac) 2 (t) of the present invention.
3 is a graph showing a thermogravimetric curve of Etraen2.

FIG. 8 is a graph showing a thermogravimetric curve of a conventional organic lead compound Pb (DSPM) 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction furnace 2 Heater 3 Substrate 4 Material container 5 Evaporation material 6 Vaporizer 7A, 7B, 7C Flow meter 8 Metering pump 9 Pressure gauge 10 Vacuum piping 11 Trap tube

Claims (6)

[Claims] 1. An organic lead compound represented by the following general formula (I). Embedded image (In the general formula (I), R represents a methyl group or a t-butyl group, and A represents ethylenediamine, tetraethylenediamine, or tetraethylenepentamine.) 2. The organic lead compound according to claim 1, which is used as a raw material for metal organic chemical vapor deposition. 3. A raw material solution for metalorganic chemical vapor deposition, wherein the organic lead compound according to claim 1 is dissolved in an organic solvent. 4. A raw material solution for organometallic chemical vapor deposition, wherein an organic lead compound represented by the following structural formula is dissolved in an organic solvent. Embedded image 5. The raw material solution for metal organic chemical vapor deposition according to claim 3, wherein the organic solvent is an oxygen-containing cyclic compound. 6. The organic lead compound according to claim 5, wherein the organic solvent is one or more selected from the group consisting of tetrahydrofuran, dimethyltetrahydrofuran and dimethylfuran.