JPH11158186A - Reduction of viscosity of dimethylaluminum hydride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the viscosity of the subject compound useful as a precursor, etc., for the chemical vapor deposition of an aluminum thin film by adding a specific amount of an additive such as a tertiary amine, an aromatic amine or a tertiary phosphine to dimethylaluminum hydride. SOLUTION: An additive selected from the group consisting of a tertiary amine having the formula NR<1> R<2> R<3> (R<1> to R<3> are each a 1-10C alkyl, a 1-10C aryl or a 1-10C arylalkyl or, together with N, forms one or more heterocyclic structures) (e.g. trihexylamine), an aromatic amine (e.g. 3-benzylpyridine) and a tertiary phosphine having the formula PR<4> R<5> R<6> (R<4> to R<6> are each a 1-10C alkyl, a 1-10C aryl or a 1-10C arylalkyl) (e.g. tribenzylphosphine) in an amount of 0.1-10 mol.% based on dimethylaluminum hydride(DMAH) is added thereto to thereby afford the objective dimethylaluminum hydride useful as a precursor, etc., for the chemical vapor deposition of an aluminum thin film used as an interconnector of a semiconductor and having a reduced viscosity for improving the productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the viscosity of dimethylaluminum hydride (DMAH) useful as a precursor for chemical vapor deposition of aluminum thin films by adding small amounts of tertiary amines, aromatic amines or tertiary phosphines. On how to lower.

[0002]

2. Description of the Related Art In an aluminum thin film used as an interconnector of a semiconductor, gaseous aluminum atoms obtained by sputtering or evaporation are usually deposited on a substrate / substrate surface by physical vapor deposition (PVD).
However, the PVD method has a step cover (step coverag).
e) Interconnectors manufactured due to poor properties are not conductive and increase the current density due to melt separation (fusi
ng away).

In order to solve such a problem, a gaseous aluminum compound, generally an organoaluminum precursor compound, is transferred onto a preheated substrate surface, where the compound is decomposed at a controlled rate to form an aluminum thin film. Forming chemical vapor deposition (CVD) methods have been attempted.

In such a CVD method, the precursor compound is vaporized using a bubbler type precursor transfer system or a direct liquid injection type transfer system. In such a system, since the vaporization rate of the precursor compound is controlled by the considerable partial viscosity, a low-viscosity precursor is preferable in order to improve productivity in mass production of semiconductors.

[0005] Dimethylaluminum hydride (DMAH)
Is a stable liquid having a vapor pressure of 2.2 torr at room temperature, and is one of organometallic precursor compounds useful for CVD of aluminum thin films. However, DMAH has a problem that its viscosity at room temperature is as high as 6,400 cp (centipoise). Such high viscosities are due to the formation of trimers or higher oligomers in the liquid state by DMAH, and thus vaporize DMAH in bubbler-type or direct liquid-injection type precursor transfer systems. It becomes very difficult. For this reason, the CVD method of depositing an aluminum thin film using DMAH has not been applied to a mass production system.

Attempts have been made to solve the aforementioned problems by using an improved bubbling device to improve the vaporization of DMAH (US Pat. No. 5,552,552).
181), which is complex and expensive.

Further, a method of using a trialkylamine-alane adduct such as dimethylethylamine-alane as a low-viscosity organometallic precursor compound has been attempted (US Pat. No. 5,545,591). A simple 1: 1 stoichiometric complex of a trialkylamine and an alane is unstable and therefore difficult to handle and difficult to produce.

The present inventors have studied to develop an efficient CVD method for the production of aluminum thin films by lowering the DMAH viscosity and have found that the DMAH viscosity can be significantly reduced by adding a small amount of a specific additive. The inventors of the present invention have found that the amount is reduced, and completed the present invention.

[0009]

Accordingly, it is an object of the present invention to provide a method for reducing the viscosity of dimethyl aluminum hydride (DMAH).

[0010]

According to one aspect of the present invention, an additive selected from the group consisting of tertiary amines, aromatic amines and tertiary phosphines is provided in the present invention by DMAH.
A method for reducing the viscosity of DMAH is provided which comprises adding in an amount of 0.1 to 10 mol% with respect to

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Additives which can be used to reduce the viscosity of the DMAH according to the invention are tertiary amines, aromatic amines or tertiary phosphines.

The tertiary amine that can be used in the present invention is a compound having one or more tertiary amino groups, and the nitrogen atom of each tertiary amino group has an appropriate hydrocarbon substituent. These are a monovalent alkyl, aryl, arylalkyl group and a divalent or trivalent bridging group having two or more tertiary amino groups (br
idging group). Preferably, NR ¹ R ² R
A monofunctional tertiary amine having the formula ³ wherein R ¹ , R ² and R ³ are each independently a C _1-10 alkyl, aryl or arylalkyl group, or together with a nitrogen atom Form one or more heterocyclic structures. More preferably, R in the formula of NR ¹ R ² R ^3
A tertiary amine having a large steric volume wherein at least one or more of ¹ , R ² and R ³ is a C 6-10 alkyl group or an aryl group, such as N-ethyl-N-methylaniline or trihexylamine It is. DMA
In order to reduce the viscosity of H to such an extent that it can be used in a bubbler, the tertiary amine of the present invention may be used in an amount of 0.1 to 10 mol%, preferably 0.1 to 3 mol%, based on DMAH. .

The aromatic amine that can be used in the present invention is an aromatic heterocyclic compound having one or more ring nitrogen atoms. Representative examples of aromatic amines, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, isoquinoline and compounds of these substituted, the substituent is a C _1-10 alkyl, aryl or arylalkyl group is there. Preferred aromatic amines are substituted pyridines such as 3-benzylpyridine. The aromatic amine is 0.1 to 1 with respect to DMAH.
It can be used in an amount of 0 mol%, preferably 0.1 to 3 mol%.

Tertiary phosphines which can be used in the present invention are compounds having the formula PR ⁴ R ⁵ R ⁶ , wherein R ⁴ , R ⁵ and R ⁶ are each independently C _1-10 It is an alkyl, aryl or arylalkyl group. Preferably, it is a phosphine having at least one or more aryl or arylalkyl groups, and more preferably, a triarylalkylphosphine such as tribenzylphosphine. Tertiary phosphines can be used in amounts of 0.1 to 10 mol%, preferably 0.1 to 3 mol%, based on DMAH.

DMAH containing the additives according to the invention has a significantly lower viscosity. For example, DMAH containing 0.37 mol% of tribenzylphosphine is observed to have a viscosity of 0.6 cp, a 10,000-fold reduction over pure DMAH.

Since the use of the low-viscosity DMAH of the present invention facilitates the vaporization of DMAH, the additive of the present invention can be used in aluminum thin film CVD using a conventional bubbler type precursor transfer system or a direct liquid injection type precursor transfer system. Can be useful as a precursor.

DMAH containing the additive of the present invention is efficiently vaporized at a temperature of from 20 to 100 ° C., preferably from 20 to 30 ° C., at a vapor pressure of from 2.2 to 30 torr. Temperatures in the 400 ° C. range and 9.8 × 10 ^-4 to 9.8 × 10 torr
The aluminum thin film is obtained by vapor deposition on the substrate at a pressure of.

[0018]

The present invention will be described in more detail with reference to the following examples. However, the following examples only illustrate the present invention and do not limit the scope of the present invention.

Example 1 0.3 N-ethyl-N-methylaniline was added to DMAH,
0.6, 1.6, 2.4 or 3.2 mol% were added. The viscosity of this solution was measured at room temperature using a digital viscometer (RVTD).
V-1 (Brookfield). As a result, as can be seen from FIG. 1, the viscosity of pure liquid DMAH is 6,400 cp, while that of DMAH containing 3.2 mol% of N-ethyl-N-methylaniline is 6 cp.

Example 2 Trihexylamine is replaced by 0.63, 1.24, 1.85 or 2.46 instead of N-ethyl-N-methylaniline.
The procedure of Example 1 was repeated except that it was used in an amount of mol%.

As a result, as can be seen from FIG.
The viscosity of DMAH containing 6 mol% of trihexylamine dropped to 70 cp.

Example 3 The procedure of Example 1 was repeated, except that N-ethyl-N-methylaniline was replaced by triethylamine in an amount of 0.56, 1.28, 5.49 or 7.68 mol%. The procedure was repeated.

As a result, as can be seen from FIG.
DMAH containing 15 mole% triethylamine has a viscosity of 15
0 cp.

EXAMPLE 4 Instead of N-ethyl-N-methylaniline, 3-benzylpyridine is replaced with 0.47, 0.98, 1.35 or 1.9.
The procedure of Example 1 was repeated except that it was used in an amount of 3 mol%.

As a result, as can be seen from FIG. 1, 1.93.
The viscosity of DMAH containing mol% of 3-benzylpyridine decreased to 10 cp.

EXAMPLE 5 The procedure of Example 5 was repeated except that diethylphenylphosphine was used in an amount of 0.88, 1.58, 2.23 or 2.67 mol% instead of N-ethyl-N-methylaniline. Step 1 was repeated.

As a result, as can be seen from FIG.
The viscosity of DMAH containing mol% diethylphenylphosphine was reduced to 50 cp.

Example 6 Instead of N-ethyl-N-methylaniline, tribenzylphosphine is replaced with 0.08, 0.16, 0.24 or 0.1.
The procedure of Example 1 was repeated except that it was used in an amount of 37 mol%.

As a result, as can be seen from FIG.
The viscosity of DMAH containing mol% tribenzylphosphine was reduced to 60 cp.

[0030]

EFFECT OF THE INVENTION DMA containing a small amount of additive according to the present invention
H has a significantly reduced viscosity and can be useful as a precursor for CVD of aluminum thin films using conventional or direct liquid injection type precursor delivery systems.

[Brief description of the drawings]

FIG. 1. N-ethyl-N-methylaniline, trihexylamine, triethylamine, 3-benzylpyridine,
4 is a graph showing a change in the viscosity of DMAH depending on the amount of diethylphenylphosphine and tribenzylphosphine added.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yun Jong-ho, Republic of Korea, 790-784 Department of Chemical Engineering, Pohang Institute of Technology, 31 Kosyo-dong, Minami-ku, Pohang-si, Gyeongsangbuk-do (72) Inventor Park Jun-Eun, Republic of Korea, 790 −784 31 Pohang Dosan, Minami-ku, Pohang-si, Gyeongsangbuk-do

Claims (7)

[Claims] 1. An additive selected from the group consisting of tertiary amines, aromatic amines and tertiary phosphines in an amount of 0.1 to 10 mol% based on dimethylaluminum hydride (DMAH). A method for lowering the viscosity of DMAH, comprising: 2. The method of claim 1, wherein the tertiary amine is of the formula NR ¹ R ² R ³ wherein R ¹ , R ² and R ³ are each independently a C _1-10 alkyl, aryl or arylalkyl group; Or one which forms one or more heterocyclic structures with a nitrogen atom). 3. The method of claim ² , wherein at least one of R ¹ , R ² , and R ³ is a C _6-10 alkyl or aryl group. 4. The method according to claim 1, wherein the aromatic amine is a substituted pyridine, wherein the substituent is a C _1-10 alkyl, aryl or arylalkyl group. 5. The method according to claim 4, wherein the substituted pyridine is 3-benzylpyridine. 6. The tertiary phosphine of the formula PR ⁴ R ⁵ R
⁶ (wherein R ⁴ , R ⁵ and R ⁶ are each independently
The method according to claim 1, wherein the compound has _1-10 alkyl, aryl or arylalkyl group). 7. The method according to claim 6, wherein the tertiary phosphine is tribenzylphosphine.