JP3584091B2 - Copper source material for CVD and film forming method using the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a copper source material for CVD suitable for depositing copper or a copper-containing material by a chemical vapor deposition (CVD) method.
[0002]
[Prior art]
[0003]
Various proposals have been made for forming a thin film of copper or a copper-containing substance by a CVD method as a thin film useful for a superconducting material or an LSI wiring material. It is advantageous to use an organic copper complex as a starting compound when copper or a copper-containing substance is deposited by a CVD method.
[0004]
BACKGROUND ART Conventionally, an organic complex of a metal or a compound thereof has been used as a raw material compound when a film is formed by a CVD method, and an organic portion (ligand) constituting such an organometallic complex is as follows. Β-diketones such as dipivaloylmethane and hexafluoroacetylacetone are generally known. JP-A-4-72066 and JP-A-4-74866 disclose organic compounds constituting a complex with metals belonging to Group IIA, IIIA, IVA and IB of the periodic table having 1 to 5 carbon atoms. 1,3 diketones having a lower alkyl group are described.
[0005]
As the CVD method, a thermal CVD method, an optical CVD method, a plasma CVD method, and the like are known. In each case, a thin film is formed by decomposing a vapor of a raw material compound. In this case, the vapor is generally sublimated from the raw material compound in a solid state.
[0006]
[Problems to be solved by the invention]
The conventionally proposed organocopper complex using a β-diketone organic compound as a ligand generally has a high melting point (about 200 ° C.). For this reason, when it is applied to a raw material compound of the CVD method, a raw material vapor is generated by sublimation from a solid state without heating it to a high temperature higher than its melting point.
[0007]
In the case of sublimation from the solid state, as the remaining amount of the raw material in the raw material container decreases, the surface area of the raw material compound decreases, and the vaporization rate slows down. There is a problem that the film speed cannot be secured for a long time. Further, when the vaporization rate changes, it is difficult to control the composition of a thin film of a substance in which copper and other elements are combined (for example, YBa ₂ Cu ₃ O ₇ ). There is also a problem.
[0008]
The organometallic complexes described in the above-mentioned JP-A-4-72066 and JP-A-4-74866 are also characterized in that they have high sublimability, and as a raw material compound for CVD, they are evaporated in a solid state. Things. Therefore, there is the same problem as described above.
[0009]
An organometallic complex using a ligand containing fluorine in the molecule, such as hexafluoroacetylacetone, has a low melting point, but fluoride may be present as an impurity in the formed film. Results in significantly impairing the properties of the film.
[0010]
Accordingly, an object of the present invention is to provide a copper source material for CVD having a low melting point capable of solving the above-mentioned problems.
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to solve such a problem. As a result, an organocopper complex having β-diketone of 6-ethyl-2,2-dimethyl-3,5-octanedione as a ligand was produced by CVD. It has a very low melting point (approximately 69-70 ° C) that can be used in a liquid state as a raw material compound, and has extremely advantageous properties for film formation by CVD, in which the evaporation temperature and the decomposition temperature are clearly separated. . Due to this characteristic, when this is used as a copper source material in the CVD method, it can be evaporated from a liquid state, and supply of a raw material vapor of copper to a base material and decomposition and deposition of copper on the base material. Can be performed stably, so that the above-mentioned problem can be solved.
[0012]
That is, according to the present invention, 6-ethyl-2,2-dimethyl-3,5-octanedione is a copper source material for CVD used for depositing copper or a copper-containing material by a CVD method. The present invention provides a source material for CVD comprising an organocopper complex as a ligand.
[0013]
According to the present invention, when copper or a copper-containing substance is deposited on a substrate by a CVD method, 6-ethyl-2,2-dimethyl-3,5-octanedione is coordinated with copper as a copper source substance. A copper or copper-containing substance formed by a CVD method, wherein the organic copper complex is heated to a temperature equal to or higher than the melting point thereof, and the complex is evaporated from a liquid phase of the complex. Provide the law.
[0014]
The organocopper complex according to the present invention is represented by the general formula of Chemical Formula 1, and is considered to be a novel compound.
[0015]
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[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The β-diketone-based organic copper complex according to the present invention is obtained by adding a copper carboxylate (for example, copper acetate or the like) and a ligand, 6-ethyl-2,2-dimethyl-3,5-octanedione, to a water-ethanol solution. The resulting precipitate can be collected by filtration, and purified by a purification method such as recrystallization or distillation.
[0017]
In order to use the thus obtained organic copper complex of the present invention as a raw material compound for the CVD method and form a film of the copper or copper-containing material by the CVD method, for example, as shown in FIG. The raw material container 2 containing the copper complex 1 is maintained at a predetermined temperature (a temperature higher than the melting point, for example, 80 to 100 ° C.) in the thermostat 3, and the flow rate of an inert carrier gas (eg, argon gas) 4 is measured by a flow meter 5. By introducing into the raw material container 2 while adjusting (for example, 5 to 500 ml / min), a gas flow accompanied by the organic copper complex is generated from the container 2.
[0018]
The generated organic copper complex vapor is led into the reaction tube 7 of the thermal decomposition furnace 6. The reaction tube (for example, a quartz tube) 7 is heated by a heater 8, and the substrate 9 installed in the tube is heated and maintained at a predetermined temperature (for example, 400 to 800 ° C.). Copper deposits on the top and forms a film. The piping from the raw material container 2 to the thermal decomposition furnace 6 is preferably maintained at a temperature higher than the heating temperature of the raw material container by 5 to 20 ° C. by the heat insulating layer 10 or a heat insulating means in order to prevent condensation. Exhaust gas from the reaction tube 7 is discharged through a cooling trap 11. In the figure, reference numeral 12 denotes a valve, and reference numeral 13 denotes a rotary pump. When forming a copper oxide film, an appropriate amount of gaseous oxygen is supplied from the oxygen container 14 through the flow meter 15 and the valve 16 into the reaction atmosphere (for example, within the reaction space 7). In addition, in order to form a film of a composite material with another element, a raw material compound of the other material is simultaneously introduced into the reaction chamber 7, although not shown.
[0019]
【Example】
[Example 1]
The bis (6-ethyl-2,2-dimethyl-3,5-octanedionato shown in Chemical Formula 1 as a raw material compound as a copper source is placed in a raw material container 2 made of stainless steel using the CVD equipment shown in FIG. 2) An operation of depositing copper and forming a film thereon using a silicon substrate as the substrate 9 was performed.
[0020]
The bis (6-ethyl-2,2-dimethyl-3,5-octandionato) copper of Chemical Formula 1 was produced as follows. First, 10 g of copper acetate monohydrate was dissolved in 200 ml of water, 20 g of 6-ethyl-2,2-dimethyl-3,5-octanedione and 20 ml of methanol were added thereto, and the mixture was stirred. After filtration and drying under reduced pressure, 5.4 g of bis (6-ethyl-2,2-dimethyl-3,5-octanedionato) copper was obtained by sublimation purification. The melting point of the obtained complex was measured to be 69 to 70 ° C.
[0021]
1 g of this organic copper complex was charged into the container 2 and the temperature of the thermostat 3 was kept at a constant temperature of 100 ° C. With the silicon substrate 9 heated and maintained at 600 ° C. by the heater 8, argon gas as a carrier gas was passed at 100 ml / min to guide the compound to the quartz reaction tube 7. The piping from the vessel 2 to the pyrolysis furnace 6 was kept warm so as to be kept at 120 ° C.
[0022]
When a film forming operation was performed for 30 minutes under these conditions, a uniform copper thin film having a thickness of 1700 angstroms was obtained.
[0023]
The film forming operation was repeated under exactly the same conditions as above except that the amount of bis (6-ethyl-2,2-dimethyl-3,5-octanedionato) copper charged in the container 2 was changed to 2 g. In this case, a uniform copper thin film having a thickness of 1700 angstroms was obtained. That is, even when the amount of the raw material compound charged in the container 2 was changed, a film having the same thickness could be formed. This indicates that the amount of evaporation from the starting compound is constant during the treatment time and the amount of decomposition is also constant.
[0024]
[Example 2]
The same processing as in Example 1 was performed for 30 minutes, except that gaseous oxygen was added from the oxygen source 14 via the flowmeter 15 and the valve 16 into the reaction tube 7 at a flow rate of 50 ml / min. As a result, a copper oxide thin film having the same thickness of 2400 angstroms was obtained for both the raw material loading amounts of 1 g and 2 g.
[0025]
[Comparative Example 1]
Example 1 except that bis (dipivaloylmethanato) copper having a melting point of 197 to 198 ° C was used in place of bis (6-ethyl-2,2-dimethyl-3,5-octandionato) copper. A film was formed under the same conditions as described above. As a result, after 30 minutes, a copper thin film having a thickness of 2000 Å was obtained for a material having a loading of 1 g and a copper thin film having a thickness of 2800 Å for a loading having a material loading of 2 g. This indicates that the evaporation amount also changed over time with the change in the volume of the raw material in the container.
[0026]
[Comparative Example 2]
The same process as in Comparative Example 1 was performed for 30 minutes, except that gaseous oxygen was added from the oxygen source 14 to the reaction tube 7 via the flowmeter 15 and the valve 16 at a flow rate of 50 ml / min. As a result, a thin film of copper oxide having a thickness of 2800 angstroms was obtained for a material having a loading of 1 g, and a thickness of 3900 angstroms was obtained for a material having a loading of 2 g.
[0027]
【The invention's effect】
As described above, the β-diketone-based organocopper complex according to the present invention has a low melting point, a high vaporization property, and an evaporating temperature and a decomposition temperature separated from each other. When used as a copper source material for production, it has an excellent advantage that it can be used in a liquid state, and since it has a constant evaporation rate, a stable film formation rate can be obtained. It has the feature that it is possible to form a thin film.
[0028]
Therefore, according to the present invention, a great contribution can be made to a technique for forming copper or a copper-containing substance useful for a superconducting material or an LSI wiring material.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of equipment arrangement of equipment for performing a thermal CVD method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Organometallic complex 2 Raw material container 3 Thermostat 4 Inert carrier gas 5 Flow meter 6 Pyrolysis furnace 7 Quartz reaction tube 8 Heater 9 Substrate 10 Heat insulation layer 11 Cooling trap 12 Valve 13 Rotary pump 14 Oxygen source

Claims (4)

A copper source material for CVD used for depositing copper or a copper-containing material by a CVD method, wherein organic copper having 6-ethyl-2,2-dimethyl-3,5-octanedione as a copper ligand Copper source material for CVD consisting of a complex. The copper source material for CVD according to claim 1, wherein the organic copper complex is represented by Chemical Formula 1.

The copper source material for CVD according to claim 1 or 2, wherein the organic copper complex has a melting point of 69 to 70 ° C. When copper or a copper-containing substance is deposited on a substrate by a CVD method, an organic copper complex using 6-ethyl-2,2-dimethyl-3,5-octanedione as a copper ligand is used as a copper source substance. A method for forming a copper or copper-containing material by a CVD method, wherein the organic copper complex is heated to a temperature equal to or higher than the melting point of the organic copper complex, and the complex is evaporated from a liquid phase of the complex.

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