Raw material for vapor deposition including organoplatinum compound and vapor deposition method using the raw material for vapor deposition

Abstract

A raw material for vapor deposition for producing a platinum thin film or a platinum compound thin film by a vapor deposition method. The raw material for vapor deposition includes an organoplatinum compound represented by the following formula, in which a cyclopentene-amine ligand and an alkyl ligand are coordinated to divalent platinum. The organoplatinum compound of the present invention has moderate thermal stability and can respond flexibly to severe film formation conditions, including a wider film formation area, higher throughput, and the like. ##STR00001##
(In the formula, R.sub.1, R.sub.2, and R.sub.3 are each any one of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an amino group, an imino group, a cyano group, and an isocyano group, each having 4 or less carbon atoms, and R.sub.4 and R.sub.5 are each an alkyl group having 1 or more and 3 or less carbon atoms.)

Claims

1. A raw material for vapor deposition for producing a platinum thin film or a platinum compound thin film by a vapor deposition method, the raw material for vapor deposition comprising an organoplatinum compound represented by a following formula, in which a cyclopentene-amine ligand and an alkyl ligand are coordinated to divalent platinum: ##STR00015## (wherein R.sub.1, R.sub.2, and R.sub.3 are each any one of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an amino group, an imino group, a cyano group, and an isocyano group, each having 4 or less carbon atoms, and R.sub.4 and R.sub.5 are each an alkyl group having 1 or more and 3 or less carbon atoms).

2. The raw material for vapor deposition according to claim 1, wherein R.sub.1 and R.sub.2 are each any one of hydrogen, a methyl group, and an ethyl group.

3. The raw material for vapor deposition according to claim 1, wherein R.sub.3 is hydrogen.

4. The raw material for vapor deposition according to claim 1, wherein R.sub.4 and R.sub.5 are both methyl groups.

5. A vapor deposition method for a platinum thin film or a platinum compound thin film, comprising: vaporizing a raw material including an organoplatinum compound into a raw material gas; and heating the raw material gas while introducing the raw material gas onto a substrate surface, wherein the raw material for vapor deposition defined in claim 1 is used as the raw material.

6. The raw material for vapor deposition according to claim 2, wherein R.sub.3 is hydrogen.

7. The raw material for vapor deposition according to claim 2, wherein R.sub.4 and R.sub.5 are both methyl groups.

8. The raw material for vapor deposition according to claim 3, wherein R.sub.4 and R.sub.5 are both methyl groups.

9. A vapor deposition method for a platinum thin film or a platinum compound thin film, comprising: vaporizing a raw material including an organoplatinum compound into a raw material gas; and heating the raw material gas while introducing the raw material gas onto a substrate surface, wherein the raw material for vapor deposition defined in claim 2 is used as the raw material.

10. A vapor deposition method for a platinum thin film or a platinum compound thin film, comprising: vaporizing a raw material including an organoplatinum compound into a raw material gas; and heating the raw material gas while introducing the raw material gas onto a substrate surface, wherein the raw material for vapor deposition defined in claim 3 is used as the raw material.

11. A vapor deposition method for a platinum thin film or a platinum compound thin film, comprising: vaporizing a raw material including an organoplatinum compound into a raw material gas; and heating the raw material gas while introducing the raw material gas onto a substrate surface, wherein the raw material for vapor deposition defined in claim 4 is used as the raw material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates A TG-DTA curve of an organoplatinum compound of Example 1.

(2) FIG. 2 shows SEM photographs of cross-sections of platinum thin films produced from the organoplatinum compound of Example 1 as a raw material.

DESCRIPTION OF EMBODIMENTS

(3) Hereinafter, best modes for carrying out the present invention will be described. In this embodiment, three kinds of organoplatinum compounds (Example 1 to Example 3) were synthesized. The physical properties of the synthesized organoplatinum compounds were evaluated, and they were used as raw materials for vapor deposition to perform a film formation test.

(4) ##STR00006##

Example 1

(5) To a flask containing 90 ml of hexane, 1.62 g (14.6 mmol) of N,N-dimethyl-3-cyclopentene-1-amine and 1.78 g (5.8 mmol) of (1,5-hexadiene)dimethyl platinum were each added in this order and stirred at room temperature for 16 hours. After the completion of the reaction, the mixture was concentrated to give a white solid. The obtained white solid was sublimated and purified to give 1.68 g (5.0 mmol) of (N,N-dimethyl-3-cyclopentene-1-amine)dimethyl platinum, the desired product (yield: 86%). The synthesis reaction formula of the organoplatinum compound of Example 1 is as follows.

(6) ##STR00007##

Example 2

(7) To a flask containing 50 ml of hexane, 0.27 g (3.3 mmol) of 3-cyclopentene-1-amine and 0.68 g (2.2 mmol) of (1,5-hexadiene)dimethyl platinum were each added in this order and stirred at room temperature for 3 hours. After the completion of the reaction, the mixture was concentrated to give a white solid. The obtained white solid was sublimated and purified to give 0.61 g (2.0 mmol) of (3-cyclopentene-1-amine)dimethyl platinum, the desired product (yield: 91%). The synthesis reaction formula of the organoplatinum compound of Example 2 is as follows.

(8) ##STR00008##

Example 3

(9) To a flask containing 30 ml of hexane, 0.21 g (2.2 mmol) of N-methyl-3-cyclopentene-1-amine and 0.45 g (1.5 mmol) of (1,5-hexadiene)dimethyl platinum were each added in this order and stirred at room temperature for 15 hours. After the completion of the reaction, the mixture was concentrated to give a white solid. The obtained white solid was sublimated and purified to give 0.43 g (1.3 mmol) of dimethyl(N-methyl-3-cyclopentene-1-amine) platinum, the desired product (yield: 87%). The synthesis reaction formula of the organoplatinum compound of Example 3 is as follows.

(10) ##STR00009##

Comparative Example

(11) As a comparative example for the above examples, dimethyl(N,N-dimethyl-3-buten-1-amine) platinum, which is an organoplatinum compound described in conventional art (Patent Document 3), was produced.

(12) To a flask containing 50 ml of hexane, 0.75 g (7.5 mmol) of N,N-dimethyl-3-buten-1-amine and 1.54 g (5.0 mmol) of (1,4-hexadiene)dimethyl platinum were each added in this order and stirred at room temperature for 20 hours. After the completion of the reaction, the mixture was concentrated to give a white solid. The obtained white solid was sublimated and purified to give 1.55 g (4.8 mmol) of dimethyl(N,N-dimethyl-3-buten-1-amine) platinum, the desired product (yield: 96%). The synthesis reaction formula of the organoplatinum compound of this comparative example is as follows.

(13) ##STR00010##

(14) Evaluation of Physical Properties:

(15) The physical properties of the organoplatinum compound produced in Example 1 ((N,N-dimethyl-3-cyclopentene-1-amine)dimethyl platinum) were evaluated by TG-DTA. In the analysis, by use of TG-DTA2000SA manufactured by BRUKER, in a nitrogen atmosphere, the organoplatinum compound sample (5 mg) was heated at a temperature rise rate of 5° C./min to a measurement temperature range, that is, room temperature to 450° C., and changes in the heat quantity and the weight of the sample at that time were observed. The results are shown in FIG. 1.

(16) In FIG. 1, from the results of DTA, the organoplatinum compound of Example 1 has a melting point of about 159° C. from the endothermic peak and a decomposition temperature of about 186° C. from the exothermic peak. Generally, the raw material heating temperature in a vapor deposition method is often set at a temperature around 100° C., and it can be seen that the organoplatinum compound of Example 1 has sufficient thermal stability at such a raw material heating temperature. In addition, in order to obtain a higher vapor pressure, it is expected to increase the heating temperature by about 10° C. to 30° C., and it can be said that the organoplatinum compound of Example 1 can respond also to such heating conditions.

(17) In addition, as a result of examining the results of TG, it can be seen that in the organoplatinum compound of Example 1, vaporization is almost completed at the time when the decomposition temperature is reached. It can be seen that this platinum compound is vaporized quickly at a relatively low temperature, and its vaporization properties are also excellent. In addition, the amount of residues resulting from the decomposition of the compound is relatively large. It is estimated that this residue is metal platinum. These TG-DTA results show that the platinum compound of Example 1 can be vaporized at a relatively low temperature, and decomposition occurs quickly with vaporization, and also show that the compound is suitable for low-temperature film formation.

(18) Then, the organoplatinum compounds of Example 2, Example 3, and the comparative example were also analyzed in the same manner. The results of TG-DTA of each example are shown in Table 1.

(19) TABLE-US-00001 TABLE 1 Organoplatinum Decomposition compound Melting point temperature Example 1 159° C. 186° C. Example 2 128° C. 169° C. Example 3  99° C. 184° C. Comparative Example  75° C. 150° C.

(20) As to the organoplatinum compounds of Examples 2 and 3, as compared with the compound of Example 1, although a decrease in the melting point was seen, the decomposition temperature was equal or only slightly lower. Therefore, it was shown that the organoplatinum compounds of the examples all have suitable vaporization properties and thermal stability. It can be seen that the melting point and the decomposition temperature of the organoplatinum compound of the comparative example are lower as compared with each example. Therefore, it was confirmed that the platinum compound of each example has higher thermal stability over conventional art.

(21) Evaluation of Thermal Stability by Heating Test:

(22) The above TG-DTA is an analysis method excellent in that physical properties intrinsic to a compound (decomposition temperature) can be measured statically and accurately. However, in the raw material heating operation at the time of actual thin film production, even when the heating temperature is lower than the decomposition temperature, due to prolonged heating, local decomposition may occur in the organic compound. In addition, chained decomposition may occur from such local decomposition as a starting point. Thus, it was decided to perform dynamic thermal stability evaluation given a raw material heating operation in thin film production. In this evaluation test, the organoplatinum compounds of Example 1 and the comparative example were heated for a predetermined period of time, and whether compound decomposition occurred was judged. As a specific method, 0.2 g of each of the organoplatinum compounds of Example 1 and the comparative example was collected and placed in a test tube, and heated in air at 100° C. for 1 hour. Then, after the 1-hour heating, whether there were changes in the appearance of the platinum compound was checked.

(23) In this heating test, in the organoplatinum compound of Example 1, no change was seen in the appearance before and after heating, and the white solid state was maintained. Meanwhile, the organoplatinum compound of the comparative example had turned into a black solid after heating for 1 hour. This is regarded as an indication of decomposition (partial decomposition) of the organoplatinum compound. For both of the organoplatinum compounds, the heating temperature (100° C.) in this heating test is lower than the decomposition temperature. In Example 1, decomposition of the compound was not seen at all, but decomposition occurred in the comparative example. This shows that the organoplatinum compound of the comparative example may decompose due to prolonged heating even at a temperature lower than the decomposition temperature, that is, its thermal stability is poor.

(24) In order to respond to the film formation conditions including wide-area film formation, high-throughput film formation, and the like, which is an object of the invention, an organoplatinum compound raw material having a high vapor pressure is required. This means the application of an organoplatinum compound having so high a thermal stability that it can be heated to a temperature at which the desired vapor pressure is shown. From the results of the above heating test, it was confirmed that the organoplatinum compound of the example has higher thermal stability as compared with the comparative example. That is, it can be said that the organoplatinum compound of the example has a better balance between thermal stability and vaporization properties as compared with the comparative example. Then, the organoplatinum compound of the example can suitably respond also to wide-area film formation and high-throughput film formation.

(25) Film Formation Test:

(26) Next, a film formation test was performed, in which a platinum thin film was formed by a CVD method by use of the organoplatinum compound produced in Example 1 ((N,N-dimethyl-3-cyclopentene-1-amine)dimethyl platinum) as a raw material compound. In this film formation test, a hot-wall type thermal CVD device was used as a film formation device. As the reactant gas, hydrogen was passed at a constant flow rate with a mass flow controller. The film formation conditions are as follows.

(27) Substrate: SiO.sub.2 and Si

(28) Substrate dimension: 15 mm×15 mm

(29) Film formation temperature: 175° C.

(30) Specimen temperature: 100° C.

(31) Film formation pressure: 5 torr

(32) Reactant gas (hydrogen) flow rate: 100 sccm

(33) Film formation time: 120 min

(34) As a result of the film formation test, it was confirmed that a platinum thin film can be formed on any of the substrates (SiO.sub.2, Si). As a result of measuring the film thickness and the specific resistance, the Pt film thickness on the SiO.sub.2 substrate was 18 nm, while the Pt film thickness on the Si substrate was 13 nm, that is, the platinum thin film was formed to a sufficient film thickness in each case. In addition, as a result of measuring the specific resistance of each thin film, the values were as excellent as 36μΩ.Math.cm and 40 μΩ.Math.cm, respectively.

(35) FIG. 2 shows SEM photographs of cross-sections of the platinum thin films formed in this embodiment. The thin films formed in this embodiment all had a uniform film thickness, and the surface smoothness was also excellent. From the results of this film formation test, it was confirmed that the organoplatinum compound of the example has suitable vaporization properties and thermal stability as a raw material compound for vapor deposition, and is useful in low-temperature film formation.

INDUSTRIAL APPLICABILITY

(36) The raw material for vapor deposition according to the present invention has a high vapor pressure and is capable of forming a high-precision platinum thin film, etc., at a low temperature, and also has moderate thermal stability and excellent handleability. The present invention is useful in the formation of electrode/wiring materials for various semiconductor elements and semiconductor devices. In particular, the present invention is also effective in film formation on a solid structure, and also applicable to the formation of a solid electrode of a field effect transistor (solid Ni—Pt silicide electrode), which has a three-dimensional structure, for example.