JPH09157851A - Platinum thin film forming material by organometallic chemical vapor deposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the purity of a thin film and increase a film forming rate by using an organoplatinum compd. of specified structure having appropriate heat stability and excellent volatility and thermal decomposition characteristics as the thin film forming material. SOLUTION: As a thin film forming material, (1,5-dimethyl-cyclooctadienyl) diethylplatinum shown by structural formula I and a Pt(IV) compd. obtained by mixing an electron-donating compd. with the diethylplatinum in >=2 molar ratio and shown by structural formula II are used. In structural formula II, A is an amic or etheric electron-donating compd. When an amine compd. is used as the electron-donating compd., one or >=2 kinds selected from a group consisting of ethylenediamine, triethylenetetramine, tetraethylenepentamine, diethylhexamine and pentaethylenehexamine are used, and tetrahydrofuran is used in the case of the etheric compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material for forming a platinum thin film by metalorganic chemical vapor deposition, and in particular, a platinum thin film such as a base electrode for a dielectric memory of a semiconductor device is subjected to a metalorganic chemical vapor deposition method. Hereinafter, referred to as “MOCVD method”),
The present invention relates to an organoplatinum compound suitable for use as a vapor deposition material.

[0002]

2. Description of the Related Art Conventionally, as a vapor deposition material used in forming various platinum thin films such as a base electrode for a dielectric memory of a semiconductor device by MOCVD, a bis (represented by the following structural formula (i) ( 1,1,1,5,5,5
-Hexafluoro-2,4-pentanedionato) platinum (I
I) (hereinafter abbreviated as “Pt (hfac) ₂ ”) and (1,5-cyclooctadienyl) represented by the following structural formula (ii) (1,1,1,5,5,5) -Hexafluoro-2,
4-pentanedionato) platinum (II) (hereinafter “(COD) P
abbreviated as "t (hfac)". ) And other various platinum compounds are known.

[0003]

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[0004]

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The present applicant has previously expressed the following structural formula as a raw material for forming a platinum thin film by metalorganic chemical vapor deposition, which has a high vapor pressure and is excellent in vaporization stability, volatility and thermal stability. (1,5-Dimethyl-1,5-cyclooctadienyl) diethylplatinum (hereinafter “(DMCOD) DEPt”)
Abbreviated. ) Was proposed (Japanese Patent Application No. 6-306203 (hereinafter referred to as “prior application”).

[0006]

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To form a platinum thin film by MOCVD using such a vapor deposition material, for example, the substrate 5 is placed on a heater 6 provided in a reaction furnace 7 as shown in the schematic explanatory view of FIG. On the other hand, in the heating furnace 3 provided so as to be connected to the reaction furnace 7, the vapor deposition material 1 made of the above-mentioned organoplatinum compound in the vaporization vessel 2 is vaporized, and the obtained vapor is introduced through the pipe 4 into Ar and H. Carrier gas such as ₂ is fed into the reaction furnace 7 to diffuse the carrier gas, and platinum 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.

[0008]

However, the organoplatinum compounds represented by the above structural formulas (i) and (ii), which are conventionally used as the vapor raw material in the above-mentioned thermal decomposition type MOCVD method, all have decomposition temperatures. Since it is high, it is necessary to set the substrate temperature high and perform film formation under high temperature conditions. Even in the case of a platinum film obtained under high temperature conditions in this way, the decomposition characteristics of the raw materials, especially the ligand bound to platinum, are poor, and some of them are taken into the platinum film without decomposition. As a result, the film mainly contains a large amount of impurities such as residual carbon.
It is also an important issue in high purification, which is a required characteristic in dielectric device design.

With the organoplatinum compound according to the prior application represented by the above structural formula, such a problem can be solved, but further improvement in characteristics is desired.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a raw material for forming a platinum thin film by metalorganic chemical vapor deposition, which has excellent thermal decomposition characteristics and a high film formation rate. .

[0011]

The raw material for forming a platinum thin film by metalorganic chemical vapor deposition of the present invention is (1,5-dimethyl-
1,5-Cyclooctadienyl) diethyl platinum ((DM
It is obtained by mixing COD) DEPt) and an electron donor compound.

By mixing (DMCOD) DEPt with an electron donor compound, the electron donor compound becomes (DM
COD) The general formula below coordinated to the platinum atom of DEPt
A Pt (IV) compound represented by [I] is produced (in the general formula below, A represents an electron donor compound). Thus, by coordinating the electron donor compound, (DM
The electron density of the platinum atom of COD) DEPt, and further the methyl group and ethyl group of the cyclooctadienyl group is compensated by the electron donor compound, and the obtained Pt (IV) compound has moderate thermal stability and high volatility. And, it has a property of being easily thermally decomposed.

[0013]

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The raw material for forming a platinum thin film by the metal organic chemical vapor deposition of the present invention can be obtained by mixing (DMCOD) DEPt with an electron donor compound at a molar ratio of at least twice.

In the present invention, the electron donor compound is preferably an amine compound such as ethylenediamine, triethylenetetramine, tetraethylenepentamine, diethylenetriamine, pentaethylenehexamine, or an ether compound such as tetrahydrofuran.

[0016]

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

The raw materials for forming a platinum thin film by metalorganic chemical vapor deposition of the present invention are (1,5-dimethyl-1,5-cyclooctadienyl) diethyl platinum ((DMCOD) DEPt) represented by the above structural formula. , This (DMCOD) D
By donating an electron to the platinum atom of EPt, (DMCO
D) It is obtained by mixing with an electron donor compound capable of stabilizing DEPt, and in the usual case, the above-mentioned general formula [I]
As shown in, the two electron donor compounds are Pt (IV) compounds coordinated with platinum atoms.

In the present invention, the electron donor compound may be a linear, branched or cyclic ether compound, or a linear, branched or cyclic amine compound, specifically as follows. The thing is illustrated.

Ether-based compound Tetrahydrofuran: C ₄ H ₈ O Amine-based compound Ethylenediamine: NH ₂ (CH ₂ ) ₂ NH ₂ Triethylenetetramine: NH ₂ (CH ₂ ) ₂ NH (CH ₂ )
₂ NH (CH ₂ ) ₂ NH ₂ tetraethylenepentamine: NH ((CH ₂ ) ₂ NH (CH
₂ ) ₂ NH ₂ ) ₂ Diethylenetriamine: NH ₂ (CH ₂ ) ₂ NH ₂ (CH ₂ ) ₂ NH ₂ Pentaethylenehexamine: NH ₂ ((CH ₂ ) ₂ NH)
₄ (CH ₂ ) ₂ NH ₂ Specific examples of the organoplatinum compound according to the present invention in which these electron donor compounds are coordinated are as follows.

[0020]

[Chemical 6]

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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Such an organic platinum compound of the present invention is
Obtained by dissolving (DMCOD) DEPt in a suitable organic solvent such as n-hexane, adding an electron donor compound such as tetrahydrofuran at a predetermined ratio, stirring and reacting, and distilling off the solvent after the reaction. You can

Such an organic platinum compound is (DMCO
D) It may be composed of only a single compound in the structure of DEPt, or may be composed of a mixture of isomers.

[0028]

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

Examples 1 to 6 and Comparative Example 1 (a) Synthesis of Organoplatinum Compound (Comparative Example 1) 10 g of K ₂ PtCl ₄ was dissolved in 200 ml of water, and 100 m of n-propyl alcohol was added to this platinum solution.
1 was added, followed by 20 ml of 1,5-dimethyl-1,5-cyclooctadiene and 0.18 g of stannous chloride. The mixture was stirred for about 2 days, filtered, and the residue on the filter was washed with water and ethyl alcohol. Acetone was poured into the obtained solid substance to prepare a suspension solution, and 7.2 g of sodium iodide was added and stirred. Then, acetone was distilled off under reduced pressure, and the residue was washed with water and dried to obtain 8.5 g of (1,5-dimethyl-1,
5-cyclooctadienyl) diiodo platinum (hereinafter referred to as "D
Abbreviated as MCODPtI ₂ ". ) Was synthesized (melting point>
120 ℃ decomposition).

Then, under cooling, the synthesized DMCODPt
100m of dry diethyl ether with sufficient degassing to I ₂
l was poured, 100 ml of an ethyl magnesium iodide ether solution (Grignard reagent) was added to this solution, and the mixture was stirred for 3 hours. While further cooling, a saturated aqueous solution of ammonium chloride was added to this solution for hydrolysis, followed by filtration, and the filtrate was separated into an ether layer and an aqueous layer. Aqueous layer is diethyl ether 10
The mixture was extracted with 0 ml, and the ether layers were combined and dried over anhydrous magnesium sulfate. Ether under reduced pressure (30 ° C / 2 torr)
The organic platinum compound (1,5-dimethyl-1,5-cyclooctadienyl) diethylplatinum ((DMCOD) DE) represented by the above structural formula, which is a light yellow liquid, is distilled off under r).
2.3 g of Pt) (melting point: 5 ° C. or lower) was obtained.

(Example 1) The above (DMCOD) DEPt
2.3 g of n-hexane was dissolved in 20 ml of (DMCO
D) DEPt and tetrahydrofuran were mixed in a molar ratio of 1: 2, stirred at room temperature for 1 hour, concentrated, and the solvent was distilled off to give the organoplatinum of the present invention represented by the above structural formula. 0.8 g of the compound (DMCOD) DEPt.THF (melting point <−5 ° C.) was obtained as a yellow liquid.

The obtained organoplatinum compound was identified by C,
H and O were analyzed by dry elemental analysis to determine I for platinum.
The elemental analysis was performed by CP emission. The identification results are as follows.

Elemental analysis (%) Actual value: C = 46.7, H =
7.48, O = 3.27, Pt = 42.1 Calculated value: C = 46.9, H = 7.38, O = 3.47, Pt =
42.3 (Example 2) Under the same conditions as in Example 1 except that ethylenediamine was used in place of tetrahydrofuran, (DMCOD) Dept. en (melting point <
5 ° C.) 0.5 g was obtained. The identification results are as follows.

Elemental analysis (%) Calculated value: C = 42.8, H =
7.57, N = 6.23, Pt = 43.4 Actual value: C = 42.7, H = 7.59, N = 6.25, Pt = 43.4 (Example 3) Example 1 except that triethylenetetramine was used instead of tetrahydrofuran. (DMCOD) DEPt · trie of the organic platinum compound of the present invention represented by the above structural formula, which is a light yellow liquid under exactly the same conditions.
1.2 g of n (melting point <5 ° C.) were obtained. The identification results are as follows.

Elemental analysis (%) Calculated value: C = 44.8, H =
8.22, N = 10.5, Pt = 36.4 Actual value: C = 44.9, H = 8.20, N = 10.3, Pt = 36.5 (Example 4) Example 1 except that tetraethylenepentamine was used instead of tetrahydrofuran. (DMCOD) DEPt.tet of the organic platinum compound of the present invention represented by the above structural formula, which is a light yellow liquid under exactly the same conditions as
1.2 g of raen (melting point <−20 ° C.) was obtained. The identification results are as follows.

Elemental analysis (%) Calculated value: C = 45.7, H =
8.47, N = 12.1, Pt = 33.7 Actual value: C = 45.5, H = 8.47, N = 12.2, Pt = 33.6 (Example 5) Exactly the same as Example 1 except that diethylenetriamine was used instead of tetrahydrofuran. Under the conditions of (DMCOD) DEPt.dien of the organic platinum compound of the present invention represented by the above structural formula, which is a light yellow liquid.
0.5 g (melting point <−20 ° C.) was obtained. The identification results are as follows.

Elemental analysis (%) Calculated value: C = 43.9, H =
7.92, N = 8.53, Pt = 39.6 Measured value: C = 43.8, H = 7.93, N = 8.53, Pt = 39.8 (Example 6) Example 1 except that pentaethylenehexamine was used instead of tetrahydrofuran. (DMCOD) DEPt.pta of the organic platinum compound of the present invention represented by the above structural formula, which is a light yellow liquid under exactly the same conditions.
0.5 g of en (melting point <−20 ° C.) was obtained. The identification results are as follows.

Elemental analysis (%) Calculated value: C = 46.3, H =
8.68, N = 13.5, Pt = 31.4 Actual value: C = 46.2, H = 8.70, N = 13.5, Pt = 31.5 (b) Thermogravimetric change of organoplatinum compound Each organoplatinum obtained by the above synthesis (a) For the purpose of evaluating the vaporization characteristics of the compound, thermogravimetric curves (heating rate 10 ° C /
min, dry argon atmosphere) and the results are shown in Figure 2
As shown in FIG.

(C) Deposition of platinum thin film Using each of the organoplatinum compounds obtained in the synthesis of (a) above, a platinum thin film was formed under the following conditions according to the thermal decomposition MOCVD method using the apparatus shown in FIG. The film was manufactured and the film thickness was measured every 10 minutes. The film thickness was measured from a cross-sectional SEM image of the film. The measurement results are shown in Table 1.

Substrate: 25 mm square Si substrate with TiN deposited by sputtering to a thickness of 100 nm Substrate temperature: 200 ° C. vaporization temperature: 80 ° C. pressure: 0.2 torr carrier gas flow rate: 50 ccm of H ₂

[0041]

[Table 1]

(D) Consideration From the results shown in FIGS. 2 to 8, it is possible to completely vaporize both the organoplatinum compound of the present invention and the organoplatinum compound of the prior application at a temperature from room temperature to about 150 ° C. Both show excellent properties that are almost the same with respect to thermal stability during vaporization, but from Table 1, the organoplatinum compound of the present invention has a further improved film formation rate as compared with the organoplatinum compound according to the prior application. It is clear that

It should be noted that any of the organic platinum compounds shown in FIG.
No formation of decomposed platinum is found in the vaporization vessel of the apparatus shown in FIG. 1, the organoplatinum compound of the present invention is vaporized at a high film forming rate without decomposing in the vaporization vessel, thermal stability during vaporization,
It was confirmed to be an organoplatinum compound having excellent volatility.

[0044]

As described in detail above, the raw material for forming a platinum thin film by metalorganic chemical vapor deposition of the present invention is excellent in thermal decomposition characteristics, has a significantly high film formation rate, and has no problem of residual impurities. Is extremely useful as a high-efficiency, high-purity platinum thin film forming raw material, and can be effectively used for producing a platinum thin film useful as a base electrode for a dielectric memory of a semiconductor device.

[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 an organic platinum compound (DMCOD) DEPt of the present invention.
It is a graph showing a thermogravimetric curve of THF.

FIG. 3 is an organic platinum compound (DMCOD) DEPt of the present invention.
It is a graph showing a thermogravimetric curve of en.

FIG. 4 is an organic platinum compound (DMCOD) DEPt of the present invention.
-It is a graph which shows the thermogravimetric curve of trien.

FIG. 5: Organic platinum compound (DMCOD) DEPt of the present invention
-A graph showing the thermogravimetric curve of tetraen.

FIG. 6 is an organic platinum compound (DMCOD) DEPt of the present invention.
It is a graph showing a thermogravimetric curve of dien.

FIG. 7: Organoplatinum compound (DMCOD) DEPt of the present invention
It is a graph showing a thermogravimetric curve of ptaen.

FIG. 8 Organoplatinum compound (DMCOD) DE according to the prior application
It is a graph which shows the thermogravimetric curve of Pt.

[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

Claims (6)

[Claims] 1. A platinum thin film formation by organometallic chemical vapor deposition obtained by mixing (1,5-dimethyl-1,5-cyclooctadienyl) diethyl platinum represented by the following structural formula and an electron donor compound. Raw material. Embedded image 2. The organometallic compound according to claim 1, which is obtained by mixing (1,5-dimethyl-1,5-cyclooctadienyl) diethylplatinum with an electron donor compound at a molar ratio of 2 times or more. Raw material for forming platinum thin films by chemical vapor deposition. 3. The raw material for forming a platinum thin film by metal organic chemical vapor deposition according to claim 1 or 2, wherein the electron donor compound is an amine compound. 4. The amine compound according to claim 3,
A raw material for forming a platinum thin film by metal organic chemical vapor deposition, which is one or more selected from the group consisting of ethylenediamine, triethylenetetramine, tetraethylenepentamine, diethylenetriamine and pentaethylenehexamine. 5. The raw material for forming a platinum thin film by metal organic chemical vapor deposition according to claim 1 or 2, wherein the electron donor compound is an ether compound. 6. The raw material for forming a platinum thin film by metal organic chemical vapor deposition according to claim 5, wherein the ether compound is tetrahydrofuran.