JP3223800B2 - Tantalum compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel tantalum compound and, more particularly, to a metalorganic chemical vapor deposition method.
mical Vapor Deposition: Hereinafter referred to as “MOCVD method”. The present invention relates to a tantalum compound useful as a vapor deposition raw material for producing an oxide-based ceramic thin film or a layered ceramic containing tantalum.

[0002]

2. Description of the Related Art In recent years, the MOCVD method has been used as an effective means for producing oxide-based ceramic thin films or layered ceramics, and has been actively studied. For example, the production of a dielectric thin film is one example. In the production, a material having a high volatility and a stable supply amount is required as a deposition material for MOCVD.

[0003] Conventionally, tantalum compounds as a material for vapor deposition by the MOCVD method have been disclosed in JP-A-6-96.
No. 60, Ta (DPM) ₄ Cl (where DPM is a ligand from HDPM: dipivaloylmethane) of a β-diketonate tantalum metal complex, and Ta represented by the following structural formula. (I-PrO) ₄ (DPM) is known.

[0004]

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In order to form a tantalum oxide thin film by MOCVD using such a deposition material, for example, as shown in a schematic explanatory view of FIG. 1, a substrate 6 is placed on a heater 7 provided in a reaction furnace 8. On the other hand, in a heating furnace 3 provided in connection with the reaction furnace 8, the vapor deposition raw material 1 made of the organic bismuth compound in the vaporization vessel 2 is vaporized, and the obtained vapor is introduced into a pipe 4 through Ar 4. , N _2, etc., into the reaction furnace 8 for diffusion, and an oxidizing gas such as O ₂ , N ₂ O, ozone or the like is introduced into the reaction furnace 8 from the pipe 5 as a reaction gas and heated. Tantalum oxide is deposited on the substrate 6. If the oxidizing gas is not introduced, tantalum will precipitate. In the drawing, reference numeral 9 denotes a vacuum pipe, and P denotes a pressure gauge. This method is called a thermal decomposition type MOCVD method.

[0006]

Generally, a β-diketonate tantalum metal complex reacts with moisture in the air to cause hydrolysis, and is extremely susceptible to deterioration, for example, to be increased in quantity, and has poor storage stability. Chip. Such a phenomenon is particularly problematic at the time of film formation, and since a stable supply amount cannot be provided, a large variation occurs in the vaporization rate (that is, the film formation rate). Thus, variations in the vaporization rate cause problems such as impairing the uniformity of the formed film and making it difficult to control the composition.

[0007] Ta (DPM) ₄ Cl or Ta (i-PrO) ₄ conventionally provided as a vapor deposition material for MOCVD.
(DPM) also has the same drawbacks. In particular, since Ta (DPM) ₄ Cl described in JP-A-6-9660 contains chlorine, there is a concern about problems such as corrosion of the apparatus and damage to the film quality.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a tantalum compound for forming a thin film by a MOCVD method which has high volatility, excellent vaporization stability, and enables stable and efficient film formation. I do.

[0009]

Means for Solving the Problems The tantalum compound of the present invention is represented by the following general formula [I].

[0010]

Embedded image (However, in the above formula [I], A is -C (CH ₃ ) ₃ or-
_{(CH 2)} shows a 3 CH _3, R is -C _{(CH 3)} 3 to a shown <br/>. )

[0011] The tantalum compound according to the present invention comprises a conventional β
-By coordinating a bulky t-butoxy group or n-butoxy group than the ligand of the diketonate tantalum metal complex, it becomes possible to avoid a molecular attack such as moisture in the air, In addition, solid crystallinity becomes better as compared with conventional compounds. For this reason, the tantalum compound of the present invention exhibits high volatility and vaporization stability in the monomer structure, and can perform efficient film formation at a high film formation rate under a good composition control by MOCVD. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The tantalum compound of the present invention has the following structural formula
[i] and [ii] .

[0014]

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[0015]

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The tantalum compound of the present invention, as shown in the embodiment of infra, tantalum penta chloride, and t- butanol or n- butanol, be synthesized by reacting a Jipibaroirumeta down it can.

Such a tantalum compound of the present invention can be prepared by the same operation as a conventional tantalum compound by using a pyrolytic MOCVD.
It can be used as a raw material for vapor deposition of a tantalum or tantalum oxide thin film by MOCVD such as CVD.

[0018]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 Synthesis of Tantalum Compound 355 g of tantalum pentachloride (1.
0 mol) was dissolved in 500 ml of dehydrated and purified toluene. Next, 4 equivalents of n-butanol based on the amount of tantalum were added to this solution, and the mixture was vigorously stirred. Further, dipivaloylmethane (HDPM) was slowly added to this reaction solution in an amount of 1.5 equivalents to the amount of tantalum, and the mixture was refluxed for 48 hours. This reaction solution was distilled under reduced pressure (120 ° C., 2 Torr).
This gave a white residue. By recrystallizing this residue with toluene, 320 g of the tantalum compound Ta (n-BuO) ₄ (DPM) of the present invention represented by the above structural formula [i] was obtained.
Obtained. The obtained tantalum compound was identified by elemental analysis by ICP-MS and by IR, NMR and MS.

Elemental analysis; Actual value (%): C = 49.8, H = 8.40, O = 14.8, Ta = 27.7 Calculated value (%): C = 49.4, H = 8 .38, O = 14.6, Ta = 27.6 IR (cm ^-1 ); 3400, 3000, 2980, 2900, 2300, 1600, 1470, 1460, 1380, 1360, 1300, 1250, 1240, 1220, 1200 , 1130, 1020, 920, 880, 800, 750 ¹ H-NMR; δ (ppm) 6.2 (CH), 1.3 (C (CH ₃ ) ₃ ), 1.1 (C (CH ₃₎ ) ₃ ) MS; m / e 660

[Evaluation of Vaporization Characteristics] For the purpose of evaluating the vaporization characteristics of the obtained tantalum compound, a thermogravimetric curve (heating rate 10 ° C./min, dry argon atmosphere) was obtained and the results are shown in FIG.

[Deposition Test of Tantalum Oxide Thin Film] Using the obtained tantalum compound, a tantalum oxide thin film was prepared by the apparatus shown in FIG. The thickness of each film was measured. The film thickness was measured from a cross-sectional SEM image of the film. The measurement results are shown in Table 1.

Substrate: 300 nm Pt sputtered film / 80 nm Ti sputtered film / 500 nm SiO ₂ thermally oxidized film / Si (10
0) substrate temperature; 600 ° C. vaporization temperature; 200 ° C. pressure; 10 Torr carrier gas Ar flow rate; 200 sccm reaction gas O ₂ flow rate; 1000 sccm Ar: O ₂ ratio;

Example 2 The procedure of Example 1 was repeated, except that t-butanol was used instead of n-butanol.
The tantalum compound Ta (t-BuO) of the present invention represented by
₄ (DPM) was obtained. The identification results of this tantalum compound are as follows. 3 and Table 1 show the evaluation results of the vaporization characteristics and the film formation test results obtained in the same manner as in Example 1.

Elemental analysis; Actual value (%): C = 48.9, H = 8.35, O = 14.2, Ta = 27.2 Calculated value (%): C = 49.4, H = 8 .38, O = 14.6, Ta = 27.6 IR (cm ^-1 ); 3350, 2960, 2950, 2880, 2360, 2300, 1600, 1460, 1380, 1360, 1300, 1250, 1220, 1130, 1070 , 1060, 950, 880, 850, 800, 750, 740 ¹ H-NMR; δ (ppm) 6.1 (CH), 1.15 (CH ₃ ), 1.5 (CH ₃ -CH ₂ ) _{, 2.3 (CH 2), 3.8} (CH 2), 1.1 (C (CH 3) 3) MS; m / e66 0

[0026] In the specific Comparative Examples 1 Example 1, without using the n- butanol, except that the divinyl Pharaoh yl methane was added 4 equivalents relative to tantalum amount performed in the same manner, the conventional tantalum Ta _(DPM 4) Cl
I got For this tantalum compound, the evaluation results of the vaporization characteristics and the film formation test results obtained in the same manner as in Example 1 are shown.
4 and Table 1.

Comparative Example 2 A conventional tantalum Ta (i-PrO) ₄ (DPM) was obtained in the same manner as in Example 1 except that t-propyl alcohol was used instead of n-butanol. This tantalum compound, the evaluation results and deposition test results vaporization properties obtained in the same manner as in Example 1 in FIG. 5 and Table 1.

[0028]

[Table 1]

[0029] It is evident that the results shown in Figure 2-5 below. That is, the tantalum compound of the present invention
While it is possible to completely vaporize at temperatures below 400 ° C. , conventional tantalum compounds produce about 5% residue at the end of vaporization. From this,
It is clear that the tantalum compound of the present invention has excellent vaporization stability.

The following is clear from Table 1. That is, in the tantalum compound of the present invention, the film thickness increases at a substantially constant rate with respect to the film formation time, and the film formation rate is higher than that of the conventional tantalum compound, whereas the case of the conventional tantalum compound is In the method, the rate of increase in the film thickness is not constant, and the film formation amount is small.

[0031]

As described in detail above, the tantalum compound of the present invention exhibits excellent volatility and a stable vaporization rate. Therefore, according to the tantalum compound of the present invention, the tantalum oxide-based ceramic thin film obtained by MOCVD is used. In film formation such as
Under good composition control, efficient film formation can be performed at a high film formation rate.

[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 a tantalum compound of the present invention: Ta (n-BuO).
₄ is a graph showing a thermogravimetric curve of (DPM).

FIG. 3 shows a tantalum compound of the present invention: Ta (t-BuO).
₄ is a graph showing a thermogravimetric curve of (DPM).

FIG. 4 shows a conventional tantalum compound: Ta (DPM) ₄ Cl.
3 is a graph showing a thermogravimetric curve of the sample.

FIG. 5: Conventional tantalum compound: Ta (i-PrO) ₄
It is a graph which shows a thermogravimetric curve of (DPM).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Deposition raw material 2 Vaporization container 3 Heating furnace 4 Carrier gas introduction pipe 5 Reaction gas introduction pipe 6 Substrate 7 Heater 8 Reaction furnace 9 Vacuum piping

────────────────────────────────────────────────── ─── Continued on the front page (56) References WO 95/26355 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07F 9/00 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A tantalum compound represented by the following general formula [I]. Embedded image (However, in the above formula [I], A is -C (CH ₃ ) ₃ or-
_{(CH 2)} shows a 3 CH _3, R is -C _{(CH 3)} 3 to a shown <br/>. ) 2. The tantalum compound according to claim 1, which is a deposition material for forming a thin film by metal organic chemical vapor deposition.