JP2785694B2 - Organic silver compounds for forming silver thin films by metalorganic chemical vapor deposition with high vapor pressure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic silver compound for forming a silver thin film by metalorganic chemical vapor deposition having a high vapor pressure.
Metallic Chemical Vapor Depositio (Metalorganic Chemical Vapor Depositio)
n: Hereinafter referred to as “MOCVD method”. The present invention relates to an organic silver compound suitable for being used as a vapor deposition raw material when formed according to the above (1).

[0002]

2. Description of the Related Art Conventionally, as a vapor deposition raw material used for forming various silver thin films such as contacts and wirings of a semiconductor device by MOCVD, (1,5-cyclooctadiene) represented by the following structural formula (II) is used. ) (1,1,1,
Organic silver compound comprising 5,5,5-hexafluoro-2,4-pentanedionato) silver (I) (hereinafter abbreviated as "(COD) (hfac) Ag") or the following structural formula (II)
(Trimethylphosphine) (1,1,
1,5,5,5-hexafluoro-2,4-pentanedionato) silver (I) (hereinafter referred to as “(TMP) (hfac) A
g ". ) Are known.

[0003]

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[0004]

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In order to form a silver thin film by MOCVD using such a deposition material, for example, as shown in a schematic explanatory view of FIG. 1, a substrate 5 is placed on a heater 6 provided in a reaction furnace 7, On the other hand, in a heating furnace 3 provided in connection with the reaction furnace 7, the vapor deposition raw material 1 made of the organic silver compound in the vaporization vessel 2 is vaporized, and the obtained vapor such as Ar or the like introduced through a pipe 4 The carrier gas is supplied into the reaction furnace 7 and diffused, and silver is deposited on the heating substrate 5. In the drawing, reference numeral 8 denotes a vacuum pipe. This method is called a thermal decomposition type MOCVD method.

[0006]

However, the organic silver compound represented by the structural formula (II), which has been conventionally used as a vapor deposition material in the above-mentioned pyrolysis type MOCVD method, is different from the heating temperature at the time of vaporization. It is extremely unstable, and there is a problem in the thermal stability of the compound such that most of the organic silver compound causes a thermal decomposition reaction in the vaporization container 3 in FIG. On the other hand, the organic silver compound represented by the structural formula (III) has higher thermal stability than the organic silver compound represented by the structural formula (II), but impurities such as phosphorus may be mixed into the produced silver film. There is a disadvantage that there is.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and is useful for forming a silver thin film by a MOCVD method such as a thermal decomposition type MOCVD method. It is intended to provide an organic silver compound.

[0008]

The organic silver compound for forming a silver thin film by metalorganic chemical vapor deposition having a high vapor pressure according to the present invention is characterized by being represented by the following general formula (I).

[0009]

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(Wherein, in the formula (I), R ¹ represents hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms, and R ² represents a fluorinated alkyl group having 1 to 8 carbon atoms) , R
³ and R ⁴ represent a linear or branched alkyl group having 1 to ⁴ carbon atoms. That is, the present inventors consider from the above viewpoint that the pyrolysis type MOCV
When producing silver thin films by other MOCVD methods including the D method, research was conducted to find a high-purity deposition material for forming a silver thin film having a uniform vaporization rate and excellent thermal stability during vaporization. As a result, the organic silver compound represented by the general formula (I) has a trialkylsilyl group at the trans position in the ethylene derivative of the ligand, and thus has the structural formula (I)
It is possible to obtain a more stable vaporization rate than the conventional organic silver compounds of I) and (III), and to terminate the terminal of β-diketone which is one of the ligands with a bulky alkyl group or a fluorinated alkyl group. The present inventors have found that by substituting the above, excellent volatility and thermal stability can be obtained, and have completed the present invention.

Hereinafter, the present invention will be described in detail.

In the general formula (I) representing the organic silver compound of the present invention, R ¹ is preferably hydrogen, methyl, t-butyl, isopropyl or the like.

R ² is preferably a linear alkyl fluoride group such as a trifluoromethyl group and a heptafluoropropyl group.

R ³ and R ⁴ are preferably a methyl group, an ethyl group, an n-propyl group and the like. In addition,
R ³ and R ⁴ may be the same or different, but it is preferable that R ³ and R ⁴ are the same substituent.

Specific examples of the organic silver compound of the present invention include:
[Trans-1,2-, which is exemplified in the section of Examples below.
(Bistrimethylsilyl) -ethene] (1,1,1,
2,2,3,3-heptafluoro-7,7-dimethyl-
4,6-octandionato) silver (I), [trans-
1,2- (bistrimethylsilyl) -ethene] (1,
1,1-trifluoro-5,5-dimethyl-2,4-hexanedionato) silver (I).

Such an organic silver compound is synthesized, for example, according to the following reaction, as shown in Examples described later.

Si (R ³ ) ₃ -C≡CH + Si (R ⁴ ) ₂ ClH → Si (R
³ ) ₃ -CH = CH-Si (R ⁴ ) ₂ Cl Si (R ³ ) ₃ -CH = CH-Si (R ⁴ ) ₂ Cl + R ⁴ MgI → Si (R ³ ) ₃ -CH = CH
-Si (R ⁴ ) ₃ + MgClI 1 / 2Ag ₂ O + Si (R ³ ) ₃ -CH = CH-Si (R ⁴ ) ₃ + R ¹ COCH ₂ COR ² →
Compound of general formula (I) Such an organic silver compound of the present invention can be prepared by MOCVD such as thermal decomposition type MOCVD by the same operation as a conventional organic silver compound.
It can be used as a raw material for depositing a silver thin film by the method.

[0018]

The organic silver compound for forming a silver thin film according to the present invention has a trialkylsilyl group at the trans position in the ethylene derivative of the ligand, so that the conventional organic compounds represented by the structural formulas (II) and (III) can be used. Vaporization at a more stable vaporization rate than silver compounds,
In addition, the introduction of a bulky alkyl group or a fluorinated alkyl group at the terminal of β-diketone, which is one of the ligands, shows excellent volatility and thermal stability.

[0019]

The present invention will be described more specifically with reference to the following examples.

EXAMPLE 1 Synthesis of Organic Silver Compound A dry, nitrogen-purged three-necked flask was charged with 26.0 g of trimethylsilylacetylene and 4 m of a 10% by weight aqueous solution of chloroplatinic acid.
and heated to 50 ° C. 25 g of dimethylchlorosilane was slowly dropped from the dropping funnel, and heated and stirred at 50 ° C. After completion of the reaction, purification was carried out by distillation under reduced pressure,
8.3 g of trans-1- (chlorodimethylsilyl)
-2- (trimethylsilyl) -ethene was obtained (boiling point 56
６０60 ° C./20 torr). This compound was dissolved in 60 ml of anhydrous diethyl ether, 102 ml of a 1 molar ether solution of methylmagnesium iodide was slowly added dropwise in an ice bath, and the mixture was heated and stirred for 4 hours after completion of the addition. Again in the ice bath, 100 ml of a saturated aqueous ammonium chloride solution was slowly added. The aqueous layer was extracted three times with ether, the organic layer and the extracted solution were combined, and the solvent was distilled off under reduced pressure. 9. The remaining oil is purified by distillation under reduced pressure.
4 g of trans-1,2- (bistrimethylsilyl)
-Ethene (hereinafter abbreviated as "BTMSE") was synthesized (boiling point: 85 to 90C / 100 torr).

Next, 140 ml of dry methylene chloride sufficiently degassed with nitrogen was poured into 5.56 g of silver oxide to obtain a suspension solution. In addition to the above BTMSE 4.13
g with vigorous stirring.
2,2,3,3-heptafluoro-7,7-dimethyl-
5.0 g of 4,6-octanedione (hereinafter abbreviated as "Hfod") was added dropwise by a syringe one by one. After stirring the reaction system for 2 hours, the mixture was filtered under a nitrogen stream, and the filtrate was filtered for 3 hours.
Distillation was performed under reduced pressure at 5 ° C. to obtain 15.8 g of white powder. The purification is performed by sublimation (60 ° C./0.2 torr), and the organic silver compound of the present invention represented by the following structural formula (IV), which is a white powder, [trans-1,2- (bistrimethylsilyl) -ethene] ( 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octandionato) silver (I) (hereinafter "(BTMSE) (fod) Ag"
Abbreviated. ) 8.5 g were obtained. Its melting point is 53
６０60 ° C. The obtained organic silver compound was identified by the following NMR results.

1H-NMR (CDCl ₃ ); 0.19 (s, 18
H), 1.12 (s, 9H), 5.71 (s, 1H), 6.02 (s, 2H)

[0023]

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Separately, 140 ml of dry methylene chloride sufficiently deaerated with nitrogen was poured into 5.91 g of silver oxide to obtain a suspension solution, and the BTMSE prepared in the same manner as above was prepared.
4.39 g were added with vigorous stirring and
5.0 g of 1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (hereinafter abbreviated as “Hpta”) was added dropwise by a syringe one by one. Reaction system 2
After stirring for an hour, the mixture was filtered under a nitrogen stream, and the filtrate was distilled off under reduced pressure at 35 ° C. to obtain 16.7 g of a white powder. Purification is performed by sublimation (50 ° C./0.2 torr), and the organic silver compound of the present invention represented by the following structural formula (V), which is a white powder, [trans-1,2- (bistrimethylsilyl) -ethene] (1 , 1,1-trifluoro-5,5-dimethyl-2,4-hexanedionato) silver (I) (hereinafter referred to as “(BT
MSE) (pta) Ag ". ) 7.2 g were obtained. Its melting point was around 49-55 ° C. The obtained organic silver compound was identified by the following NMR results.

1H-NMR (CDCl ₃ ); 0.22 (s, 18
H), 1.13 (s, 9H), 5.68 (s, 1H), 5.92 (s, 2H)

[0026]

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For the purpose of comparison, the compounds represented by the structural formulas (II) and (III) are the same under the same conditions except that 1,5-cyclooctadiene and trimethylphosphine are used in place of the above BTMSE. Conventional organic silver compounds (CO
D) (hfac) Ag and (TMP) (hfac) Ag were synthesized respectively.

FIGS. 2, 3 and 4 show the resulting organic silver compound of the present invention (BTMSE) (fod) Ag (FIG. 2) and (BTM
In order to evaluate the vaporization characteristics of SE) (pta) Ag (FIG. 3) and conventional organic silver compound (COD) (hfac) Ag (FIG. 4), a thermogravimetric curve (heating rate 10 ° C./min, nitrogen atmosphere) was used. Indicated.

Deposition of Silver Thin Film Using the organic silver compound of the present invention and the conventional organic silver compound, a silver thin film is prepared by the apparatus shown in FIG. 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: 1 inch of Ti on a 1 inch square Si substrate
Substrate deposited at a thickness of 000 mm by sputtering Substrate temperature; 300 ° C. Vaporization temperature; 60 ° C. Pressure; 2 torr Carrier gas flow rate; 100 ccm Ar

[0031]

[Table 1]

Discussion The following is clear from the results shown in FIGS.
That is, the organic silver compound of the present invention is 140 to 160 ° C. from room temperature.
Although the organic silver compound can be completely vaporized at a temperature of up to about 30%, on the other hand, about 30% of a residue is generated in the conventional organic silver compound when the vaporization is completed. From this, it is apparent that the organic silver compound of the present invention has excellent thermal stability during vaporization.

The following is clear from Table 1. That is, in the organic silver compound of the present invention, the film thickness increases at a substantially constant rate with respect to the film forming time, and the film forming speed is higher than that of the conventional organic silver compound, whereas the film thickness of the conventional organic silver compound is In the case of the film formation time, the tendency to decrease the film formation amount becomes remarkable from the time when the film formation time exceeds 30 minutes.

When the organic silver compound of the present invention was used, no decomposition silver was generated in the vaporization vessel of the apparatus shown in FIG. 1, whereas in the case of the conventional organic silver compound, the decomposition silver was not used. Was found. From this, the organic silver compound of the present invention is vaporized at a constant rate with respect to the film forming time without being decomposed in the vaporization container, and is more excellent in thermal stability and volatility during vaporization than the conventional organic silver compound. The organic silver compound.

[0035]

As described in detail above, the organic silver compound for forming a silver thin film by metalorganic chemical vapor deposition having a high vapor pressure according to the present invention is solid at around room temperature, has a stable vaporization rate, and In addition to its excellent thermal stability, it is extremely useful as a material for forming a uniform and dense silver thin film by the MOCVD method without the risk of contamination of impurities, and is effective for the production of a silver thin film useful as a wiring material for semiconductor devices. Can be used.

[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 is a graph showing a thermogravimetric curve of the organic silver compound of the present invention.

FIG. 3 is a graph showing a thermogravimetric curve of the organic silver compound of the present invention.

FIG. 4 is a graph showing a thermogravimetric curve of a conventional organic silver compound.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Katsumi Ogi 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture, Central Research Laboratory of Mitsubishi Materials Corporation (56) References JP-A-5-59551 (JP, A) Hei 5-106045 (JP, A) JP-A-7-133285 (JP, A) WO 92/7971 (WO, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07F 7/08 C07F 19/00 C23C 16/18 CA (STN) REGISTRY (STN) WPIDS (STN)

Claims (1)

(57) [Claims] 1. An organic silver compound represented by the following general formula (I) for forming a silver thin film by metalorganic chemical vapor deposition having a high vapor pressure. Embedded image (However, in the above formula (I), R ¹ is hydrogen or carbon atom 1)
Represents a linear or branched alkyl group having 8 to 8 carbon atoms, R ² represents a fluorinated alkyl group having 1 to 8 carbon atoms, and R ³ and R ⁴ represent a linear or branched alkyl group having 1 to ⁴ carbon atoms. Is shown. )