JPH062943B2 - Method for forming metal thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the periodic table of elements VIII used in electronic parts and the like.
A method for forming a thin film of a group metal.

[Conventional technology]

Thin films of Group VIII metals such as platinum are used in electronic parts and the like. As a method for forming a thin film of a Group VIII metal, there is a vapor method, for example, “Thin Film Handbook” (edited by Japan Society for the Promotion of Science, Thin Film 131 Committee, Ohmsha, 1983, 1).
(February publication) Page 108 describes a method for forming a thin film by vapor deposition of palladium, platinum and rhodium.

As the CVD method, for example, J. Electrochem.
c., 120 (5) 686 (1973) (author Myrow J. Rand), dichlorobiscarbonyl platinum (II) ([P
tCl ₂ (CO) ₂ ]), tetrakis (trifluorophosphine)
A method for forming a thin metal film by heating platinum (II) ([Pt (PF ₃ ) ₄ ]) to 600 ° C. under normal pressure is described, and tris (acetylacetonato) ruthenium (III) ([Ru ( acac) ₃ ))
A method for depositing Ru using Ru is disclosed in JP-A-51-141738, and bis (acetylacetonato) platinum (II) ([Pt
(Pac film is formed by using (acac) ₂ ])
Deposition (CF Powell et al. John wily & Sons, Inc., New
York (1966)) pages 310-314 and J. Electrochem. Soc., 120.
(5) 686 (1973) (author Myrow J. Rand).

[Problems to be solved by the invention]

However, the vapor deposition method described above uses only a single metal material as a vapor deposition source.
It is necessary to heat to a high temperature of 00-2000 ℃, for example, 10 ^-2
The melting point under pressure of Torr is 1460 ° C for palladium and 20 for platinum.
Since 90 ° C and 2040 ° C for rhodium, it is necessary to heat above these temperatures. Such high temperature heating is disadvantageous from the viewpoint of energy saving and economy,
At the same time, there is a problem that it becomes difficult to control the deposition rate, and the materials that can be used as the substrate are restricted.

In the case of the above-mentioned CVD method, the substrate temperature is 35
Since it is necessary to heat it to a high temperature of 0 ° C or higher, most of which is 500 to 600 ° C, there is still a problem in energy saving and economical efficiency. In addition, there are cases in which the film formation rate is as slow as 0.001 to 0.01 μm / min, and the formed thin film contains carbon impurities. In general, a gas or liquid raw material is often used in the CVD method, but in that case, it is difficult to intensively supply the raw material in the vicinity of the gas, resulting in poor raw material utilization efficiency. There is also.

Sputtering may be used as a method for forming a Group VIII metal thin film, but in general, since the temperature of the substrate rises sharply in sputtering, the problems of the above-mentioned conventional methods cannot be solved, and the deposition rate is further increased. However, there is a problem that the device is slow and the device is extremely expensive.

Therefore, an object of the present invention is that both the raw material temperature and the gas temperature can be carried out at a low temperature, the control of the film formation is easy, the film formation rate is relatively fast, the material utilization efficiency is high, and an expensive apparatus is not required. It is to provide a method capable of forming a Group VIII metal thin film having high purity. The present inventors have found that a specific organometallic compound containing a Group VIII metal element can be selected as a raw material and decomposed under specific conditions to solve the above-mentioned problems of the prior art.

[Means for solving problems]

That is, the present invention is a method for forming a thin film of a metal of Group VIII of the Periodic Table of the Elements on the surface of a substrate by using an organometallic compound as a raw material for solving the above problems.
The organometallic compound is a solid organometallic compound containing at least one metal element of Group VIII and at least one of carbonyl or a hydrocarbon having 1 to 4 carbon atoms, tris (acetylacetonato) rhodium, bis (acetyl). Acetonato) palladium, bis (cyclopentadienyl)
Palladium, bis (cyclopentadienyl) cobalt,
At least one selected from bis (cyclopentadienyl) nickel and bis (cyclopentadienyl) ruthenium, the organometallic compound at a pressure of 10 ^-1 Torr or less, a raw material temperature of 300 ° C or less, and a substrate temperature of 300 ° C or less. It is intended to provide a method for forming a metal thin film, which comprises vaporizing a compound and causing at least one of heat, plasma and light to act on the vapor.

The organometallic compound used as a raw material in the method of the present invention contains at least one of Group VIII elements of the Periodic Table of Elements, and as Group VIII elements, iron (Fe), cobalt (Co), nickel ( Ni), ruthenium (Ru), rhodium (R
h), palladium (Pd), osmium (Os), iridium (I
r) and platinum (Pt).

One kind of the organometallic compound used is a solid at room temperature and atmospheric pressure, and contains at least one carbonyl or a hydrocarbon having 1 to 4 carbon atoms. If all the hydrocarbons are hydrocarbons having 5 or more carbon atoms, it is difficult to vaporize at 300 ° C or lower except for the compounds mentioned below, and carbon and organic impurities are likely to be incorporated into the formed thin film. . Examples of the hydrocarbon having 1 to 4 carbon atoms include methyl, ethyl, propyl, butyl, allyl, ethylene and the like. The organometallic compound may optionally have a ligand other than carbonyl and a hydrocarbon having 1 to 4 carbon atoms, and such ligands include, for example,
Acetylacetonato, cyclopentadienyl, cyclooctatetraene, 1,4,5-η-4-cyclooctene-1
-Halogen such as yl, fluorine, chlorine, bromine and iodine. Specific examples of solid organometallic compounds containing at least one carbonyl or a hydrocarbon having 1 to 4 carbon atoms and a Group VIII metal element include tricarbonyl (cyclooctatetraene) iron ([Fe (CO) ₃ (C ₈ H ₈ )], enneacarbonyldiiron ((Fe ₂ (CO) ₉ )), octacarbonyldicobalt ((Co ₂ (CO) ₈ )), dodecacarbonyltetracobalt ((Co ₄ (CO)) ₁₂ ]), dodecacarbonyl tricobalt rhodium ([Co ₃ Rh (CO) ₁₂ ]), dodecacarbonyl triruthenium ([Ru ₃ (CO) ₁₂ ]), dodecacarbonyl iron diruthenium ([FeRu ₂ (CO) ₁₂ ]) , Dodecacarbonyl tetrarhodium ([Rh ₄ (CO) ₁₂ ]), hexadecacarbonyl hexarhodium ([Rh ₆ (CO) ₁₆ ]), dicarbonyl (acetylacetonato) rhodium ((Rh (CO) ₂ (acac) ], Diallyl (acetylacetonato) rhodium ([Rh (C ₃ H ₅ ) ₂ (acac)]) ,
Bis (ethylene) cyclopentadienyl rhodium ((Rh
(C ₂ H ₄ ) ₂ (C ₅ H ₅ )]), tetracarbonylpalladium ((Pd
(CO) ₄ ]), tris (ethylene) palladium ((Pd (C
₂ H ₄ ) ₃ ]), allyl (cyclopentadienyl) palladium
((Pd (C ₃ H ₅ ) (C ₅ H ₅ ))), dicarbonyl (acetylacetonato) platinum ((Pt (CO) ₂ (acac))), diallyl platinum ((Pt (C
₃ H ₅ ) ₂ ]), trimethyl (acetylacetonato) platinum ((P
t (CH ₃ ) ₃ (acac)]) and the like. The raw material compound may contain halogen as described above, but in this case, since exhaust gas contains halogen, attention must be paid to environmental hygiene and safety. The method of the present invention has the advantage that raw materials containing no halogen can be selected.

In addition, although it has no carbonyl and hydrocarbon having 1 to 4 carbon atoms, it does not contain tris (acetylacetonato) rhodium (II
I) ([Rh (acac) ₃ ]), bis (acetylacetonato) palladium (II) ([Pd (acac) ₂ ]), bis (cyclopentadienyl) palladium ([Pd (C ₅ H ₅ ) ₂ ]), bis (cyclopentadienyl) cobalt ([Co (C ₅ H _{5) 2]),} bis (cyclopentadienyl) nickel ([Ni (C ₅ H _{5) 2])} and bis (Shikuropentaji (Enyl) ruthenium ((Ru (C
₅ H ₅ ) ₂ ]) can be used in the method of the present invention. These compounds also have a relatively high vapor pressure, but are solid at room temperature and atmospheric pressure.

The above organometallic compounds may be used alone or in combination of two or more, depending on the intended composition of the thin film.

The method of the present invention comprises a pressure of 10 ^-1 Torr or less, preferably 10 ^-2 Tor
rr or less, particularly preferably 10 ^-3 Torr or less, the temperature of the organometallic compound as a raw material is 300 ° C or less, preferably room temperature to 200 ° C, and the substrate temperature is 300 ° C or less, preferably 200 ° C or less. . If the pressure exceeds 10 ^-1 Torr, the raw material temperature must be higher than 300 ° C in order to vaporize the raw material. When the raw material temperature exceeds 300 ° C., it is against the object of the present invention to lower the temperature, and the raw material compound is decomposed before becoming vapor or the film forming rate on the substrate becomes slow. It is also against the object of the present invention to raise the temperature of the substrate higher than 300 ° C. Further, as long as the above-mentioned organometallic compound is used, it is possible to sufficiently form a metal thin film at 300 ° C., so it is higher than 300 ° C. No need.

For the vaporization of the raw material compound, the raw material may be adjusted to an appropriate temperature of 300 ° C. or lower, often 200 ° C. or lower under the above pressure,
Heat if necessary. The specific temperature varies depending on the pressure and the kind of the raw material compound, but can be easily selected.

The method of the present invention introduces the vaporized raw material compound into the vicinity of the surface of the substrate, for example, at a position of 1 to 10 cm from the substrate,
Apply at least one of heat, plasma and light.
As a result, the raw material compound forms a thin film made of a Group VIII element metal or its alloy on the surface of the substrate.

In order to apply heat, the substrate is usually heated, and in this case, the substrate is heated so that the temperature does not exceed 300 ° C.

The method for generating plasma in the reaction vessel is not particularly limited, and examples include high frequency discharge, magnetron type discharge, EC
R discharge or the like can be used. The gas used for plasma excitation is usually air and is not particularly limited. The energy density on the substrate is preferably in the range of 0.1 to 100 W / cm ² .

In addition, as the light used when applying light, for example, CO ₂ laser (10.59 μm), Ar ⁺ laser (0.1257
Laser light such as (μm) can be used.

Heat, plasma, and light may be used in combination of two or more, if necessary.

The shape and material of the gas used in the present invention are not particularly limited, and examples of the material include ceramic, metal, glass, resin and the like. Note that various pretreatments such as primer coating, preheating, ion bombardment treatment, and plasma treatment may be performed in order to improve the adhesion strength between the substrate and the metal thin film.

According to the method of the present invention, the VIII-thickness up to about 5 μm
A thin film of a group metal can be formed with high purity.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 A vapor deposition apparatus equipped with a coil for high-frequency plasma, the outline of which is shown in FIG. 1, was used. The apparatus is provided with a sample table 2 equipped with a heater in a bell jar type reactor 1, and the sample table 2 is provided directly above the sample table 2.
The substrate 3 can be placed at a position separated by cm, and the substrate 3 can also be heated by a heater (not shown). The inside of the reactor 1 can be exhausted by an exhaust pipe 5 equipped with a valve 4, and the degree of vacuum inside can be measured by a vacuum gauge 6 and can be adjusted. The temperatures of the raw material compound 7 and the substrate 3 placed on the sample table 2 can be measured with a thermocouple (not shown). A high frequency coil 8 for exciting plasma in the reactor is provided outside the reactor 1.

Using the above device, but without exciting the plasma,
A ruthenium metal thin film was formed on a glass substrate using [Ru ₃ (CO) ₁₂ ] as a sample at a vacuum degree of 2 × 10 ⁻³ Torr, a substrate temperature of 150 ° C., and a sample temperature of 20 ° C.

The obtained 1 μm thick thin film had a good adhesion strength by a peeling test, and the film forming rate was 0.2 μm / min. Further, the metal thin film was formed almost only on the surface of the substrate, and the utilization efficiency of the raw material was high.

Example 2 Example 1 was repeated, except that [Rh ₄ (CO) ₁₂ ] was used as a sample at the vacuum degree of 5 × 10 ⁻⁴ Torr, the substrate temperature of 150 ° C., and the sample temperature of 200 ° C. In the same manner as above, a rhodium metal thin film was formed on the glass substrate.

The adhesion strength of the obtained 0.5 μm-thick thin film was good by a peeling test, and the film formation rate was 0.1 μm / min.

Example 3 Using the same apparatus as in Example 1, using a vacuum degree of 5 × 10 ⁻⁴ Torr, a substrate temperature of 150 ° C., and a sample temperature of 150 ° C., [Pt (CO) ₂ (aca
c)] was used as a sample in the same manner as in Example 1,
A platinum metal thin film was formed on a glass substrate.

The adhesion strength of the obtained 0.5 μm-thick thin film was good by a peeling test, and the film formation rate was 0.1 μm / min.

Example 4 The same apparatus as in Example 1 was used, except that [Pd (acac) ₂ ] was used as a sample at a vacuum degree of 5 × 10 ⁻⁴ Torr, a substrate temperature of room temperature of 200 ° C., and a sample temperature of 200 ° C. Similarly, a palladium metal thin film was formed on the glass substrate.

The adhesion strength of the obtained 0.5 μm-thick thin film was good by a peeling test, and the film formation rate was 0.1 μm / min.

Example 5 The same apparatus as in Example 1 was used, except that [Co ₂ (CO) ₈ ] was used as a sample at a vacuum degree of 5 × 10 ⁻² Torr, a substrate temperature of 150 ° C., and a sample temperature of room temperature. Similarly, a cobalt metal thin film was formed on the glass substrate.

The adhesion strength of the obtained 0.5 μm-thick thin film was good by a peeling test, and the film formation rate was 0.1 μm / min.

Example 6 Using the same apparatus as in Example 1, at a vacuum degree of 5 × 10 ⁻⁴ Torr, a substrate temperature of room temperature, and a sample temperature of room temperature, [Ru ₃ (CO) ₁₂ ] was used as a sample, and the energy density on the substrate was 10 W. A ruthenium metal thin film was formed on a glass substrate by applying a high frequency plasma of / cm ² .

The obtained 1 μm thick thin film had a good adhesion strength by a peeling test, and the film forming rate was 0.2 μm / min.

Example 7 Using the same apparatus as in Example 1, at a vacuum degree of 5 × 10 ⁻⁴ Torr, a substrate temperature of 150 ° C., and a sample temperature of room temperature, [Co ₂ (CO) ₈ ] and [R 2
Example 3 except that a mixture of u ₃ (CO) ₁₂ ] was used as a sample.
Similarly to the above, a metal thin film was formed on the glass substrate.

The obtained thin film has a deposition ratio of Co: Ru = 70: 30 (weight ratio).
It was a Co-Ru alloy film. The obtained 1 μm thick thin film peeling test showed good adhesion strength, and the film formation rate was
It was 0.2 μm / min.

Example 8 [Pt (CH ₃ ) ₃ (acac)] using the same apparatus as in Example 1 at a vacuum degree of 1 × 10 ⁻⁴ Torr, a substrate temperature of 150 ° C., and a sample temperature of 150 ° C.
A platinum metal thin film (film thickness 0.5 μm) was formed on a glass substrate in the same manner as in Example 1 except that was used as a sample.

The adhesion strength of the obtained thin film by the peeling test was good, and the film formation rate was 0.1 μm / min.

Example 9 Using the same apparatus as in Example 1, using a vacuum degree of 5 × 10 ⁻⁴ Torr, a substrate temperature of 150 ° C., and a sample temperature of 200 ° C., [Rh (C ₃ H ₅ ) ₂ (aca
c)] was used as a sample in the same manner as in Example 1,
A thin film of rhodium (film thickness 0.5 μm) was formed on a glass substrate.

The adhesion strength of the obtained thin film by the peeling test was good, and the film formation rate was 0.1 μm / min.

Comparative Example 1 (Vapor Deposition Method) Pt was used as a sample at the vacuum degree of 5 × 10 ⁻⁵ Torr, substrate temperature of 150 ° C. and sample temperature of 2100 ° C. using the same apparatus as in Example 1, and platinum metal was deposited on a glass substrate by vapor deposition. A thin film was formed.

The adhesion strength of the obtained thin film having a pressure of 0.5 μm as determined by a peeling test was good, and the film formation rate was 0.1 μm / min.

Comparative Example 2 (Sputtering Method) Using a high frequency sputtering apparatus, argon was used as a carrier gas, a vacuum degree was 5 × 10 ^-2 Torr, and a substrate temperature was 200 ° C.
A platinum metal thin film was formed on a glass substrate by a high frequency bipolar sputtering method using Pt as a sample at a sample temperature of room temperature.

The obtained 0.1 μm thick thin film had a good adhesion strength by a peeling test, and the film forming rate was 0.01 μm / min.

Comparative Example 3 (CVD method) Using a CVD apparatus, using hydrogen as a carrier gas,
A platinum metal thin film was formed on a glass substrate using [Pt (PF ₃ ) ₄ ] as a sample at a normal temperature (1 atm), a substrate temperature of 600 ° C., and a sample temperature of 150 ° C. The exhaust gas was passed through an exhaust gas treatment device having a chlorine-based remover and then passed through a water scrubber (containing NaOH) for treatment.

The obtained 0.1 μm thick thin film had a good adhesion strength by a peeling test, and the film forming rate was 0.01 μm / min.

〔The invention's effect〕

According to the method of the present invention, the temperature of the raw material and the substrate is 300 ° C.
A Group VIII metal thin film can be formed at the following low temperatures, and the film formation rate is fast and the rate can be easily controlled by adjusting the heating of the raw material compound. Further, since the raw material compound is a solid, the distance between the raw material and the substrate can be arbitrarily adjusted in the reactor, and the raw material can be installed in the vicinity of the substrate, so that the utilization efficiency for forming a thin film is high. Furthermore, there is an advantage that expensive equipment and raw materials are not required.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the outline of the vapor deposition apparatus used in the examples. 1. Reactor 3. Substrate 7. Raw material compound 8. High frequency coil

Claims (1)

[Claims] 1. A method for forming a thin film of a metal of Group VIII of the Periodic Table of Elements using an organometallic compound as a raw material, wherein the organometallic compound is a metal element of Group VIII. At least one and carbonyl or 1 to 1 carbon atoms
A solid organometallic compound containing at least one of hydrocarbons of 4, tris (acetylacetonato) rhodium, bis (acetylacetonato) palladium, bis (cyclopentadienyl) palladium, bis (cyclopentadienyl) cobalt, At least one selected from bis (cyclopentadienyl) nickel and bis (cyclopentadienyl) ruthenium, the organometallic compound at a pressure of 10 ^-1 Torr or less, a raw material temperature of 300 ° C or less, and a substrate temperature of 300 ° C or less. A method for forming a metal thin film, which comprises vaporizing a compound and causing at least one of heat, plasma and light to act on the vapor.