JPH09121027A - Material for tantalum oxide film vapor phase growth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of particles, improve the smoothness, and realize an easy micro-fabrication in a post-processing by adopting such a material for tantalum oxide film vapor phase growth that comprises high-purity tantalum alkoxide whose chlorine element is less than specific value. SOLUTION: This material is made of high-purity tantalum alkoxide whose chlorine element is less than 10ppm, and the high-purity tantalum alkoxide is used to form a tantalum oxide film on a substrate. Any alkoxide including chlorine element can be applied to the purification method for obtaining high- purity tantalum alkoxide, however, a tantalum nitride is allowed to react with alcohol and is subjected to dechlorination by using ammonium gas. As a result, the obtained tantalum alkoxide whose chlorine element value is adjusted is preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for vapor phase epitaxy of a tantalum oxide film made of high-purity tantalum alkoxide used for manufacturing integrated circuit devices and the like, and a vapor phase growth method using the same.

[0002]

2. Description of the Related Art Tantalum compounds are used for forming capacitors and the like of integrated circuit devices. For example, mixing tantalum alkoxide or tantalum chloride with oxygen or ozone, or tantalum chloride with nitrous oxide, heat
It has been proposed that a tantalum oxide film is vapor-phase grown on a substrate by a VD method, a photo CVD method, a plasma chemical reaction method or the like (for example, JP-A-2-128460, JP-A-2-250970). ).

[0003] In such a method, tantalum alkoxide can form an oxide film on a substrate relatively easily by a method such as thermal CVD or photo-CVD in the presence of oxygen or ozone, and is particularly attracting attention. By the way, the tantalum alkoxide is prepared by a method of reacting tantalum chloride and alcohol as shown in the following formula and then dechlorinating with ammonia gas (in the following formula, R represents an alkyl group).

[0004] _{TaCl 5 + 3ROH → TaCl 2 (} OR) 3 + 3HCl (I) TaCl 2 (OR) 3 + 2NH 3 + 2ROH → Ta (OR) 5 + 2NH 4 Cl (II) but, tantalum alkoxide in obtained in this way It has been found that a small amount of chlorine element remains in the film, which produces a large number of particles when the tantalum oxide film is formed, deteriorating the smoothness of the oxide film and making fine processing in the subsequent step difficult.

[0005]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and an object of the present invention is to produce a tantalum oxide film which produces few particles, is excellent in smoothness, and does not hinder fine processing in a later step. The object is to provide a material for vapor phase epitaxy of a tantalum oxide film composed of a high-purity tantalum alkoxide capable of forming a film and a vapor phase growth method using the same.

[0006]

The present invention provides a chlorine element of 1
A vapor phase epitaxy method comprising forming a tantalum oxide film vapor phase growth material comprising a high purity tantalum alkoxide at 0 ppm or less, and forming a tantalum oxide film on a substrate surface using the high purity tantalum alkoxide.

As the refining method for obtaining the high-purity tantalum alkoxide, which is the material for vapor phase epitaxy of tantalum oxide film of the present invention, any tantalum alkoxide containing chlorine element can be applied, but particularly, Those prepared by a method of reacting tantalum chloride with alcohol as described above and then dechlorinating with ammonia gas are preferable. In the present invention, the chlorine element can be removed without any trouble even if it exists in the form of chloride, chloride ion or free chlorine. Examples of the metal hydride and metal hydride complex compound for removing the chlorine element include lithium hydride, sodium hydride, calcium hydride, lithium aluminum hydride, sodium bis (2-methoxyethoxy) aluminum hydride, diisobutylaluminum hydride. , Aluminum hydride, sodium borohydride, lithium borohydride and the like can be exemplified, and particularly lithium hydride, sodium hydride, calcium hydride, sodium bis (2-methoxyethoxy) aluminum hydride and the like are simple and preferable. Although the amount of the metal hydride and the metal-hydrogen complex compound used depends on the amount of chlorine element contained in the tantalum alkoxide, it is generally preferable to appropriately select and use it in the range of 5 to 30 times mol of the chlorine element.

The treatment of the tantalum alkoxide with the metal hydride or the metal hydrogen complex compound is preferably carried out by adding the above metal hydride or the metal hydrogen complex compound to the tantalum alkoxide and stirring and mixing. In this case, the tantalum alkoxide, the metal hydride or the metal hydride complex compound is conveniently and preferably used as it is, but these are dissolved in an organic solvent such as benzene, toluene, xylene or hexane to a concentration of 50 to 70% and used. Is also good.

By the treatment with the metal hydride or the metal hydrogen complex compound, the chlorine element content is preferably 10 ppm or less. In other words, this means that chlorides, chloride ions, free chlorine, and the like contained in the tantalum alkoxide are contained at 10 ppm or less as a chlorine element.
When the chlorine element is 10 ppm or less, when a tantalum oxide film is formed by a vapor phase growth method such as a thermal CVD method or a photo CVD method, it is possible to suppress the generation of particles on the oxide film, and in the fine device forming process. It can be a mirror surface that does not interfere.

In the present invention, a tantalum oxide film is formed on the surface of a substrate by using a high-purity tantalum alkoxide containing chlorine element of 10 ppm or less by the vapor phase growth method. The growth method can be used as it is, for example, the above high-purity tantalum alkoxide is oxygen,
It is contacted with an atmosphere of ozone or an inert gas containing them such as argon, and is oxidized and decomposed by heat or light such as ultraviolet rays to form a tantalum oxide film on a substrate made of silicon or the like. The alkoxy group of the tantalum alkoxide used in the present invention is not particularly limited, but a methoxy group, an ethoxy group, an iso-propoxy group and the like are particularly preferable because the oxide film can be easily formed.

[0011]

【Example】

Reference example 100 g of tantalum chloride (TaCl ₅ ) is added to toluene 700
Then, 240 ml of ethanol was added dropwise while blowing ammonia gas at a flow rate of 500 ml / min under a nitrogen gas atmosphere. Next, the produced ammonium chloride was filtered off, heated to 50 ° C., and ammonia gas was again blown therein at a flow rate of 500 ml / min for 7 hours. The formed ammonium chloride was filtered off, toluene and ethanol were distilled off from the filtrate, and this was then distilled under reduced pressure (140
C., 0.2 to 0.4 mmHg) to obtain 93 g of pentaethoxytantalum. 300p as chlorine element in this
pm was mixed.

Production Example 1 of high-purity tantalum alkoxide 0.04 g of lithium hydride was added to 20 g of pentaethoxytantalum obtained in the above Reference Example, and the mixture was stirred at a temperature of 150 ° C. for 7 hours. Next, 0.3 ml of ethanol was added, and the mixture was heated to 75 ° C. and stirred for 3 hours, then heated to 100 ° C. and ethanol was distilled off. Then vacuum distillation (14
13 g of pentaethoxy tantalum was recovered at 0 ° C. and 0.2 to 0.4 mmHg). The chlorine element in this pentaethoxytantalum was 1 ppm or less.

Production Example 2 of high-purity tantalum alkoxide 0.4 g of calcium hydride was added to 23 g of pentaethoxytantalum obtained in the above Reference Example, and the mixture was stirred at a temperature of 120 ° C. for 5 hours. Next, add 1.1 ml of ethanol, heat to 65 ° C., stir for 5 hours, then 100 ° C.
The temperature was raised to and ethanol was distilled off. Then, 15.4 g of pentaethoxy tantalum was recovered by vacuum distillation (140 ° C., 0.2 to 0.4 mmHg). The chlorine element in this pentaethoxytantalum was 5.5 ppm.

Production Example 3 of High-Purity Tantalum Alkoxide Pentaethoxytantalum 23.4 obtained in the above reference example
0.4 g of sodium hydride was added to g, and the mixture was stirred at a temperature of 150 ° C. for 5 hours. Then 2.0 ml of ethanol
Add it. After heating to 65 ° C. and stirring for 5 hours, 100
The temperature was raised to ° C and ethanol was distilled off. Then, 11.3 g of pentaethoxytantalum was recovered by vacuum distillation (140 ° C., 0.2 to 0.4 mmHg). The chlorine element in this pentaethoxytantalum was 1 ppm or less.

Production Example 4 of high-purity tantalum alkoxide Pentaethoxytantalum 16.5 obtained in the above reference example
1.2 ml of sodium bis (2-methoxyethoxy) aluminum hydride was added to g, and at a temperature of 110 ° C,
Stir for 5.5 hours. Distillation under normal pressure was carried out as it was, and then distillation under reduced pressure (140 ° C., 0.2 to 0.4 mmHg) was carried out to recover 10.5 g of pentaethoxytantalum. The chlorine element in this pentaethoxytantalum was 1 ppm or less.

Production Example 5 of high-purity tantalum alkoxide Pentaethoxytantalum 25.3 obtained in the above reference example
Lithium aluminum hydride 0.4g was added to g
The mixture was stirred at a temperature of 5 ° C for 5 hours. Then add 1.
After adding 2 ml and heating to 70 ° C. and stirring for 3 hours,
The temperature was raised to 100 ° C. and ethanol was distilled off. Then, 16.0 g of pentaethoxy tantalum was recovered by vacuum distillation (140 ° C., 0.2 to 0.4 mmHg). Chlorine element in this pentaethoxy tantalum is 5.6 ppm
Met.

EXAMPLE Mixed gas of nitrogen and oxygen (nitrogen: 0.8 liter / mi)
n, oxygen: 0.5 liter / min) In a stream of air, a substrate temperature of 420 ° C., a Ta ₂ O ₅ film formation rate of about 10 Å / min, and a high-purity tantalum alkoxide production example 1 by a thermal CVD method. A tantalum oxide film (100 Å) was formed on a silicon substrate by using the pentaethoxy tantalum obtained in the above. The obtained oxide film contained 0.05 particles / cm ² or less. On the other hand, an oxide film was formed by the same method using pentaethoxytantalum containing 300 ppm as the chlorine element obtained in the reference example, and as a result, the oxide film had 10 particles / mm ² .

[0018]

As described above, according to the present invention, as a material for vapor phase epitaxy of a tantalum oxide film, a trace amount of chlorine element in tantalum alkoxide can be further reduced to reduce the chlorine element to 1%.
By using high-purity tantalum alkoxide of 0 ppm or less, generation of particles is small, smoothness is excellent, and a tantalum oxide film that does not hinder microfabrication in a post process can be formed, which is extremely useful for manufacturing integrated circuit devices and the like. It is useful.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H01L 21/316

Claims (2)

[Claims] 1. A material for vapor phase epitaxy of a tantalum oxide film, which is made of high-purity tantalum alkoxide containing 10 ppm or less of chlorine element. 2. A vapor phase growth method characterized in that a tantalum oxide film is formed on the surface of a substrate by using a high-purity tantalum alkoxide having a chlorine element content of 10 ppm or less.