KR20000014279A - Process for preparing alkylimido-tris-alkylamidotantalnium and preparing tantalnium nitride film - Google Patents

Abstract

PURPOSE: Alkylimino-tris-alkylamidotantalum as an organometallic precursor is prepared which can prepare tantalum film. CONSTITUTION: Title compounds(formula I; R1 is C3- C7 alkyl group; R2 is hydrogen or methyl group; R3 is ethyl, methyl, isopropyl or t-butyl group) are prepared from compound II£Lin(R2)(R3); R2 is hydrogen or methyl group; R3 is ethyl, methyl, isopropyl or t-butyl group| and compound III£(LiNH(R1); R1 is C3- C7 alkyl group|. Thus, 1.2 mole of compound II and 0.3 mole of compound III are suspended in 500 ml of dry n-hexane, followed by cooling to -78°C. 1.2 Mole of TaCl5 is slowly added and heated for 5 hours to give the title compound.

Description

Alkylimido-tris-alkylamido tantalum, preparation method thereof and tantalum nitride film production method using the same

The present invention relates to an alkylimido-tris-alkylamido tantalum used as an organometallic precursor in an organometallic chemical vapor deposition process, a method for producing the same, and a method for producing a TaN film using the same.

As semiconductors are highly integrated, there is a need for copper wiring having low resistivity and excellent resistance to electromigration compared to aluminum wiring. A diffusion barrier is formed between the metal film and the silicon film in order to prevent the materials forming the contact and the metal constituting the silicon film from diffusing with each other and the materials in adjacent regions do not cause a chemical reaction with each other. Therefore, the material used as the diffusion barrier must be (1) not diffused into the metal film or silicon film, stable enough to not react with the metal film or silicon film, and (2) adhere well to the metal film and silicon film. (3) Low contact resistance for metal film and silicon film. Titanium nitride (hereinafter referred to as "TiN") film or tantalum nitride (hereinafter referred to as "TaN") film is studied as a diffusion barrier formed between the aforementioned copper metal film and silicon film. have.

In order to form a diffusion barrier, a sputtering method, a chemical vapor deposition method, and the like are used. In the case of forming a diffusion barrier using a sputtering method, there is a problem in that the step coverage of the diffusion barrier formed as the semiconductor device is highly integrated and the aspect ratio increases. In order to solve this problem, a method of forming a diffusion barrier using chemical vapor deposition has been attempted. However, when the TiN film formed by the chemical vapor deposition method is used as a diffusion barrier between the copper metal film and the silicon film, heat treatment at 500 ° C. or higher for 30 minutes causes copper to diffuse into the silicon film. Therefore, such a TiN film has a problem in that its characteristics as a diffusion barrier for copper metal wiring are poor. In order to solve this problem, a method of forming a TaN film having excellent diffusion barrier properties for copper metal wiring by chemical vapor deposition has been studied.

The TaN film may be formed by chemical vapor deposition using TaCl ₅ , N ₂ and H ₂ or using TaCl ₅ and NH ₃ . However, when using this method, the reaction temperature is 800 ° C-1300 ° C, which is too high for the semiconductor process. Therefore, in order to lower the reaction temperature, an organometallic precursor such as Ta (N (CH ₃ ) ₂ ) ₅ may be used instead of TaCl ₅ . When Ta (N (CH ₃ ) ₂ ) ₅ is used, the deposition reaction temperature is significantly lowered to 200 ° C. However, in this case, there is a problem that Ta ₃ N ₅ of tetragonal system having a specific resistance of 10 ⁶ µΩcm or more is made. Therefore, in order to solve this problem, using an organometallic precursor containing a double bond between tantalum and nitrogen than when using TaCl ₅ can form a TaN film deposited at a relatively low temperature and a low resistivity. However, since much carbon remains in the TaN film thus formed, not only the TaN phase but also the TaCN phase is present. As a result, the resistivity of the deposited TaN film is larger than 1000 µΩcm, which is much larger than 135-250 µΩcm, which is the resistivity of the TaN film formed by the sputtering method. Therefore, even when an organometallic precursor including a double bond of tantalum and nitrogen is used, there is a problem in that the TaN film has a high specific resistance.

An object of the present invention is to provide an alkylimido-tris-alkylamido tantalum, which is an organometallic precursor capable of forming a TaN film having excellent step coverage and low resistivity by organometallic chemical vapor deposition at low temperature. There is a purpose.

Another object of the present invention is to provide a method for preparing alkylimido-tris-alkylamido tantalum as the organometallic precursor.

Another object of the present invention is to provide a method for preparing a TaN film by organometallic chemical vapor deposition using the alkylimido-tris-alkylamido tantalum.

Alkylimido-tris-alkylamido tantalum according to the present invention for achieving the above object is a compound represented by the following formula (1).

Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group.

In particular, R1 is preferably a t-butyl, allyl or benzyl group having excellent radical stability among alkyl groups.

One embodiment of the method for producing an alkylimido-tris-alkylamido tantalum according to the present invention for achieving the above another object is to form a mixed solution by mixing a compound having the formula (2) and a compound having the formula (3) And a step of cooling the mixed solution and reacting by adding TaCl ₅ to the cooled mixed solution to complete the alkylimido-tris-alkylamido tantalum having the formula (2).

LiN (R2) (R3)

LiNH (R1)

Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group.

Another embodiment of the method for preparing alkylimido-tris-alkylamido tantalum according to the present invention for achieving the above another object is to provide an alkyl amido solution, such as the formula (4), and the alkyl amido solution The step of cooling and the addition of Ta (N (R 2) (R 3)) ₅ to the alkyl amido solution to react to complete the alkylimido-tris-alkyl amido tantalum having the formula (1).

(R1) NH ₂

Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group.

According to another aspect of the present invention, there is provided a method of preparing a TaN film by an organometallic chemical vapor deposition method using an alkylimido-tris-alkylamido-tantalum, in which the chemical formula 1 Providing an alkylimido-tris-alkylamido tantalum having, vaporizing the alkylimido-tris-alkylamido tantalum, and depositing a TaN film on the semiconductor substrate. The TaN film formed by this manufacturing method is preferably used as a diffusion barrier formed between the copper metal film and the silicon film.

The alkylimido-tris-alkylamido tantalum produced by the present invention is used as an organometallic precursor of a TaN film used as a diffusion barrier between a copper metal film and a silicon film, thereby providing a TaN film having excellent step coverage and low specific resistance. Can be formed.

Hereinafter, an alkylimido-tris-alkylamido tantalum of the present invention, a method for producing the same, and a method for producing a TaN film by an organometallic chemical vapor deposition method using the same will be described. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art the scope of the invention. It is apparent that various modifications and improvements are possible to those skilled in the art without departing from the spirit and scope of the present invention as provided to fully inform the present invention.

Alkylimido-tris-alkylamido tantalum

Alkylimido-tris-alkylamido tantalum according to the present invention is used as an organometallic precursor in a metal organic chemical vapor deposition process. This compound is preferably used as an organometallic precursor for forming a TaN film used as a diffusion barrier for copper metal wiring.

Alkylimido-tris-alkylamido tantalum according to the present invention is represented by the following formula (1).

<Formula 1>

In particular, R1 is one of alkyl groups, preferably t-butyl, allyl or benzyl group with excellent radical stability. R2 is one of hydrogen or methyl groups and R3 is one of ethyl, methyl, isopropyl, or t-butyl groups.

Alkylimido-tris-alkylamido tantalum is used as an organometallic precursor for depositing TaN films. In this case, in the alkylimido-tris-alkylamido tantalum, the double bond of tantalum and nitrogen is maintained without being decomposed in the thermal decomposition step of the chemical vapor deposition process. Therefore, the TaN film formed using the alkylimido-tris-alkylamido tantalum becomes a cubic phase with low specific resistance. The t-butyl, allyl or benzyl groups used for R 1 are easily dissociated and removed during the chemical vapor deposition process because of their excellent radical stability among the various alkyl groups. And, the alkyl group R3 bonded to the nitrogen atom which is single-bonded with tantalum is easily removed by the beta-hydride removal mechanism. In addition, the alkyl group R3 is removed by a simple pyrolysis reaction, and has a minimum number of carbon atoms in the alkyl group, thereby minimizing the amount of residual carbon in the deposited film. Therefore, when the alkylimido-tris-alkylamido tantalum according to the present invention is used as an organometallic precursor, a TaN film having excellent step coverage and low specific resistance can be formed.

Method for preparing alkylimido-tris-alkylamido tantalum

<Example 1>

The synthesis of alkylimido-tris-alkylamido tantalum proceeds using the Schlenk technique under a nitrogen atmosphere. Solvents such as hexanes are dried using sodium benzophenone before use. 1.2 moles of the compound having Formula 2 and 0.3 mole of the compound having Formula 3 were placed in a 1000 ml Schlenk flask containing 500 ml of dry n-hexane. Next, the Schlenk flask is placed in a dry ice bath to cool the suspension solution in the Schlenk flask to -78 ° C. Slowly add 1.2 mol of TaCl ₅ to it. The mixture is then slowly warmed up and held for 5 hours to complete the reaction shown in Scheme 1 below.

TaCl ₅ + 4LiNH (R1) + Li (R2) (R3) → ((R2) (R3) N) ₃ Ta = N (R1) + 5LiCl + (R1) NH ₂

R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group.

After completion of the reaction the precipitate is filtered off and washed three times with 100 ml of n-hexane. The volatile compounds are then removed using vacuum to give pure alkylimido-tris-alkylamido tantalum.

Example 2

1.5 moles of the compound having the above formula (4) was placed in a 1000 ml Schlenk flask containing 500 ml dry n-hexane. The Schlenk flask is placed in a dry ice bath and cooled to -78 ° C. Slowly add 1.2 moles of Ta (N (R2) (R3) ₂ ) ₅ into the cooled Schlenk flask. The mixture is then slowly warmed up to room temperature and held for 3 hours to complete the reaction. After the reaction was completed, the precipitate was filtered off and washed three times with 100 ml of n-hexane. The volatile compounds are then removed using vacuum to give pure alkylimido-tris-alkylamido tantalum.

Method for preparing TaN film using alkylimido-tris-alkylamido tantalum

A method of preparing a TaN film by organometallic chemical vapor deposition using the alkylimido-tris-alkylamido tantalum having the formula (5) according to the present invention as an organometallic precursor will be described.

First, an alkylimido-tris-alkylamido tantalum is provided into a cold wall organometallic chemical vapor deposition apparatus. At this time, the base pressure of the chamber is 2 × 10 ^-6 torr, precursor delivery is carried out using a liquid delivery system, the temperature of the evaporator (30 ℃-60) Keep the temperature. Then, the precursor delivery line, the chamber and the showerhead are heated to prevent the precursor from condensation. Next, after vaporizing the alkylimido-tris-alkylamido-tantalum, a TaN film is deposited on the semiconductor substrate. It is preferable to clean the semiconductor substrate before depositing the TaN film. At this time, the cleaning method may be washed in a cleaning solution in which hydrofluoric acid (HF) and ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and pure water (Deionized Water) are mixed, or in a deposition chamber, radio frequency (RF) ) Can be cleaned by argon or hydrogen sputtering using plasma.

Experimental Example

When the TaN film is deposited at a deposition temperature in the range of 350 ° C to 650 ° C, the resistivity of the deposited film decreases as the deposition temperature increases, but the deposition rate does not change significantly. When the deposition temperature is 450 deg. C, the formed TaN film has a specific resistance of 400 mu m cm. Elemental analysis of TaN films using Auger Electron Spectroscopy (AES) is N / Ta = 0.7, or elemental analysis of TaN films using Rutherford Backscattering Spectroscopy (RBS). 1.1 indicates more nitrogen. As a result of analyzing the TaN film using AES, oxygen and carbon are present in the TaN film at about 4%, respectively, which is greatly reduced than that of the TaN film by the chemical vapor deposition process. When the TaN film is deposited in a trench having an aspect ratio of 2 and a critical dimension of 0.45 by the method according to the present invention, the TaN film is 100% when the deposition temperature is 400 ° C and 70 when the deposition temperature is 450 ° C. Step coverage of% can be obtained.

In addition, when the TaN film formed by the present invention is used as a diffusion barrier, even if it is heat-treated at 550 ° C. for 30 minutes, it is possible to obtain a property that copper does not diffuse into silicon by the TaN film.

The TaN film formed by the present invention is preferably used as a diffusion barrier formed between the copper metal film and the silicon film.

As described above, by using the alkylimido-tris-alkylamido tantalum according to the present invention as an organometallic precursor for forming a TaN film, a TaN film having excellent step coverage and low specific resistance is subjected to organometallic chemical vapor deposition at low temperatures. It can be formed as.

Claims (11)

Alkylimido-tris-alkylamido tantalum represented by the following formula (1). <Formula 1> Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group. The alkylimido-tris-alkylamido tantalum of claim 1, wherein R 1 is a t-butyl, allyl or benzyl group. Mixing a compound having Formula 2 and a compound having Formula 3 to form a mixed solution; <Formula 2> LiN (R2) (R3) <Formula 3> LiNH (R1) Wherein R 1 is one of alkyl groups having 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group. Cooling the mixed solution; And TaCl ₅ is added to the cooled mixture to react the mixture, thereby completing alkylimido-tris-alkylamido tantalum having the following formula (1), wherein the alkylimido-tris-alkylamido tantalum is prepared. Method for producingium <Formula 1> Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group. 4. The method of claim 3, wherein R 1 is t-butyl, allyl or benzyl. 5. The method of claim 3, wherein the cooling of the mixed solution is performed by lowering the temperature of the mixed solution to −78 ° C. 5. Providing an alkyl amido solution such as Formula 4; <Formula 4> (R1) NH ₂ Cooling the alkyl amido solution; And Ta (N (R2) (R3)) ₅ is added to the alkyl amido solution and reacted to form an alkylimido-tris-alkylamido tantalum having the following formula (1): Method for preparing imido-tris-alkylamido tantalum. <Formula 1> Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group. The method of claim 6, wherein R 1 is t-butyl, allyl or benzyl. The alkylimido-tris-alkyl comprising the step of preparing a TaN film by organometallic chemical vapor deposition using an alkylimido-tris-alkylamido tantalum having the formula 1 as an organometallic precursor Method for manufacturing TaN film using amido tantalum. <Formula 1> Wherein R 1 is one of alkyl groups of 3 to 7 carbon atoms, R 2 is one of hydrogen or methyl group, and R 3 is one of ethyl, methyl, isopropyl, or t-butyl group. The method of claim 6, wherein the preparing of the TaN film by the organometallic chemical vapor deposition method comprises: providing the alkylimido-tris-alkylamido tantalum into an organometallic chemical vapor deposition apparatus, and the alkylimido- Vaporizing tris-alkylamido tantalum, and depositing a TaN film on a semiconductor substrate, wherein the alkylimido-tris-alkylamido tantalum is produced. 10. The method of claim 8, wherein the TaN film is used as a diffusion barrier. 10. A method of manufacturing a TaN film using the alkylimido-tris-alkyl amido tantalum. 11. The method of claim 10, wherein the diffusion barrier is formed between a copper metal film and a silicon film. 12. The method of claim 10, wherein the alkylimido-tris-alkyl amido tantalum is used.