JPH1112727A - Aluminum alloy single crystal target - Google Patents

Abstract

[PROBLEMS] To provide an aluminum alloy single crystal target which is excellent in the film quality and film forming characteristics of an aluminum thin film which is macroscopically and uniformly distributed by finely and uniformly microdispersing an additive element. I do. SOLUTION: Aluminum having a purity of 99.9% by weight or more and one of the elements having atomic numbers 3 to 83, excluding noble gases, are added.
In an aluminum alloy single crystal solidified and cast in one direction to which a seed or two or more additive elements are added, the additive element is contained in a total range of 0.1 to 10% by weight, and a concentrated portion of the additive element is formed. In a direction perpendicular to the casting direction of the single crystal.
It is distributed continuously or intermittently in the casting direction of the single crystal at an interval of 05 mm to 0.2 mm, and the concentration distribution of the added element is made within ± 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal target of an aluminum alloy for sputtering, which is mounted on a sputtering apparatus and used for producing a thin film.

[0002]

2. Description of the Related Art A sputtering method irradiates a sputtering target with ions in a vacuum and collides the target with a substance on the surface of the target, thereby evaporating a substance constituting the target and depositing the substance on a substrate to form a thin film. Is widely used for forming a thin film. As a sputtering target used in this method, for example, a reflection film of an optical disk, an electrode wiring of a liquid crystal display, a wiring of an LSI, etc., are made of high-purity aluminum based on aluminum to which various elements are added for the purpose of improving thin film characteristics. Alloys are used. In particular, for wiring materials such as LSI, an aluminum alloy obtained by adding various elements such as Si and Cu to high-purity aluminum is used, and after forming a thin film on a substrate by a sputtering method using this alloy as a target, etching is performed. Circuit thin lines are formed. Also, Ta,
A high-purity aluminum alloy to which a high melting point metal such as Co, Ni, and Nd is added is used.

In the sputtering method, it is known that the crystal structure on the surface and inside of the target has a great effect on the emission characteristics of atoms from the target, and on the film formation characteristics of an aluminum thin film on a substrate [for example, , G.
K. Wehner, Phys. Rev .. 102 , 69
9 (1956)], it is expected that excellent film forming characteristics can be obtained by controlling the crystal orientation in accordance with the required characteristics.

Heretofore, as a target material of an aluminum alloy, a polycrystalline aluminum alloy which has been subjected to processing or heat treatment to adjust its crystal structure and crystal orientation has been used. However, it is difficult to completely control the crystal orientation to a specific orientation according to the purpose. In addition, it is known that the additive element distribution of the target material affects the additive element distribution of the aluminum thin film in the sputtering method, and in the case of this kind of polycrystalline alloy,
Since macroscopic segregation of additional element components occurs due to the solid-liquid distribution phenomenon at the time of solidification, they are used after being homogenized by high-temperature heating. On the other hand, Japanese Patent Application Laid-Open No. 7-300667 describes a target material of a single crystal of an aluminum alloy and a method for producing the same by controlling the drawing direction of the cast material by continuous casting to within 2 ° with respect to the center axis of the mold. ing.

[0005]

However, even in the case of a single crystal target material of an aluminum alloy,
The additive element distribution of the target material in sputtering affects the additive element distribution of the aluminum thin film,
In the case of a single crystal, there is a problem such as generation of recrystallized grains due to high temperature heating, and it has been demanded to make the concentration of the added element uniform. For this reason, it has been proposed to uniformly disperse the additional element during solidification, but as with polycrystals, a macroscopic segregation of the additional element component occurs due to the solid-liquid distribution phenomenon during solidification. There is no.

The method and the target material described in the above-mentioned Japanese Patent Application Laid-Open No. 7-300667 do not cause a solid-liquid distribution phenomenon of a solute in a macroscopic view, and provide a uniform concentration distribution of the added element. There is a possibility that crystal nuclei may be generated on the mold surface due to slight variations in the size, which is not sufficient for the manufacturing method, the concentration distribution width of the additive element as a target material is narrow, and the interval between the enrichment parts is not sufficiently controlled. Is not always enough. An object of the present invention is to provide an aluminum thin film formed by a sputtering method, in which 0.1 to 10% by weight of an additive element is finely and uniformly and micro-dispersed, thereby being excellent in film quality and film forming characteristics. An object of the present invention is to provide an aluminum alloy single crystal target.

[0007]

Means for Solving the Problems The inventors of the present invention have studied the distribution of added elements in an aluminum alloy single crystal in a microscopic dispersion state under a microscope and a photoelectric photometric emission spectroscopy usually used for elemental analysis of aluminum. As a result of intensive studies on the macroscopic distribution over the entire casting measured by the method, the heat-melted single crystal material was brought into contact with the seed crystal using an insulating template and the seed crystal, and the seed crystal was partially removed. In a continuous production method of a single crystal that starts growing a single crystal after being dissolved in, under specific production conditions, by enriching the enriched portion of the additive element of the aluminum alloy single crystal microscopically and finely, It has been found that the macro concentration distribution becomes uniform. The present invention has been completed.

That is, the present invention is as follows. (1) One-way solidified and solidified aluminum alloy obtained by adding one or more additional elements from elements with atomic numbers from 3 to 83 to aluminum having a purity of 99.9% by weight or more, excluding rare gases. In the crystal, the additive element is contained in a range of 0.1 to 10% by weight in total, and the enrichment portion of the additive element is 0.05 m in a direction perpendicular to the casting direction of the single crystal.
An aluminum alloy single crystal target which is continuously or intermittently distributed in the casting direction of the single crystal at an interval of m to 0.2 mm. (2) The aluminum alloy single crystal target according to (1), wherein the concentration distribution of the additional element is within ± 10%. (3) The aluminum alloy single crystal target according to the above (1) or (2), wherein the crystal orientation of the aluminum alloy single crystal to be a sputtering surface is (100), (110) or (111). (4) The aluminum alloy single crystal target according to any one of (1) to (3), wherein a difference between a crystal orientation of the aluminum alloy single crystal and a crystal orientation of subcrystal grains contained in the alloy single crystal is within 10 °. (5) The additive element is Ag, Au, Ca, Co, Cr, C
u, Fe, Ge, Hf, In, Li, Mg, Mn, M
o, Na, Nb, Nd, Ni, Si, Sn, Ta, T
The aluminum alloy single crystal target according to any one of (1) to (4), which is one or more elements selected from i, V, W, Y, and Zr. (6) The aluminum alloy single crystal target according to the above (1) to (5), wherein the additional element is Cu and / or Si. (7) Continuous production of a single crystal using a heat-insulating template and a seed crystal, in which the raw material of the heat-melted single crystal is brought into contact with the seed crystal to partially dissolve the seed crystal and then start growing the single crystal. In the method, the raw material and the seed crystal of the single crystal are aluminum or an alloy thereof, and after the dissolution of the seed crystal has substantially stagnated, the seed crystal is grown by starting or strengthening the cooling of the seed crystal; The length equivalent to the length of the single crystal grown from the seed crystal by 2.5 mm in the direction opposite to the crystal growth direction.
The aluminum alloy single crystal target according to (1), wherein the single crystal is grown by continuously or intermittently pulling the single crystal grown from the seed crystal at a rate in the range of / mm to 100 mm / min. (8) The aluminum alloy single crystal target according to any one of (1) to (7), wherein the target has a structure in which two or more single crystal materials are combined in parallel or radially. Hereinafter, the present invention will be described in detail.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The target of the present invention can be manufactured by the following method. That is, the purity of the raw material is 99.9.
An aluminum alloy raw material obtained by adding one or more additional elements from among the elements having atomic numbers 3 to 83, excluding the rare gas, to aluminum by weight or more is melted in a crucible, and the lower part of the crucible is melted. The seed crystal is charged into the attached mold to start casting. The mold temperature distribution at the start of casting is controlled by controlling the temperature of the mold inlet to be higher than the melting point of the aluminum alloy by the heat from the crucible and the melted aluminum alloy. I do. The seed crystal charged in the mold comes into contact with the molten raw material and partially dissolves, and the single crystal growth starts from the state where the solid-liquid solidification interface between the raw material melt and the seed crystal is formed at a fixed position in the mold. . After the de-heating / supplying heat balance is maintained and the solidification interface rests at a fixed position, the cooling of the seed crystal is started or strengthened and held for several seconds to several tens of minutes. By this operation, crystal growth from the seed crystal occurs, the solidification interface moves to the aluminum alloy melt side, and a single crystal that inherits the crystal orientation of the seed crystal grows. The growth proceeds toward the high temperature side of the mold, and the mold temperature at the position corresponding to the solidification interface of the grown single crystal material is higher than the melting point of the aluminum alloy, no crystal nuclei are generated from the mold, and the single crystal is formed only from the seed crystal. grow up. Subsequently, a length equal to or less than the solidification progress amount of the aluminum alloy due to the change in the cooling condition is drawn in a direction opposite to the solidification direction, and casting is started.

After starting the drawing under such conditions, a time for growing the single crystal is set, and the operation of drawing out the grown portion is repeated to continue casting. If the coagulation amount and the withdrawal amount can be substantially matched, this operation can be performed continuously. Withdrawal speed is 2.5mm / min ~ 100m
m / min, preferably from 4 mm / min to 50 mm / min. At 2.5 mm / min or less, segregation of the alloying element occurs, so that the microscopic dispersion of the alloying element cannot be made uniform and a single crystal material having a uniform macroscopic concentration distribution cannot be obtained. 1
At a speed of more than 00 mm / min, it is difficult to control the withdrawal amount due to the mechanism of the apparatus, and it becomes difficult to perform single crystallization.

In the present invention, high purity aluminum having a purity of 99.9% or more is used as aluminum as a raw material. Aluminum having a purity lower than that has many impurities and is not suitable as a sputtering target. As the seed crystal, a single crystal of aluminum or an alloy thereof having the crystal orientation of the single crystal material to be produced can be used. Preferably, pure aluminum or the same material as the single crystal material to be produced is used.

As one or more additional elements from the elements having atomic numbers 3 to 83 excluding the rare gas,
Ag, Au, Ca, Co, Cr, Cu, Fe, Ge, H
f, In, Li, Mg, Mn, Mo, Na, Nb, N
d, Ni, Si, Sn, Ta, Ti, V, W, and Zr are preferably one or more elements, and Cu and / or Si are more preferable.

[0013] In the aluminum alloy single crystal produced by this method, the enriched portion of the additive element is uniformly and microscopically dispersed.
The concentration of the macroscopic additive element becomes uniform. That is, the enriched portions of the added elements can be distributed continuously or intermittently in the direction perpendicular to the casting direction of the single crystal at an interval of 0.05 mm to 0.2 mm and in the casting direction of the single crystal.
Further, it is possible to produce a single crystal in which the difference between the crystal orientation of the aluminum alloy single crystal and the crystal orientation of the sub-crystal grains contained in the alloy single crystal is within 10 ° and the concentration distribution of the added element is within ± 10%. .

Next, from the obtained aluminum alloy single crystal, a sputter target can be produced by a usual method for producing a sputter target such as cutting and bonding. In addition, by using a single crystal material that matches the thickness of a sputter target to be manufactured, processing into a sputter target becomes easy. Further, a target having a size of, for example, 1 m × 1 m or more, such as for a liquid crystal, can be a single target by combining small single crystals. In this combination type target, the film formation characteristics similar to those of the single type target can be obtained by making the crystal orientation of each single crystal material and the distribution of the concentration layer of the additive element uniform. Also, manufacturing a large target with this combination type is advantageous in terms of productivity and manufacturing cost.

In general, the sputtering method is industrially widely applied to a reflection film, a light-shielding film, a moisture-proof film, a wiring material, and the like because a high-quality thin film is obtained, the productivity is high, and the damage to the material to be coated is small. Although being used, the target of the present invention can be used as a sputtering target for various commercially available devices by applying a normal sputtering method, and the characteristics of each thin film can be adjusted according to the application and purpose. .

Further, since the target of the present invention is a single-crystal target, if the crystal orientation of the evaporation surface of the target is controlled to, for example, (111), the deposition rate of the aluminum thin film by the sputtering method is remarkably increased. improves. In addition, if the crystal orientation of the plane parallel to the substrate is controlled to (110), the atoms emitted by sputtering have high straightness and are perpendicularly incident on the substrate, so that the step coverage (step coverage) is good. By controlling the crystal orientation of the sputtering target, for example, it is expected to be effective for forming a film in a contact hole or the like having a high aspect ratio.

Among the thin films obtained by the sputtering method using the target of the present invention, Ag, Au, Ca, C
o, Cr, Cu, Fe, Ge, Hf, In, Li, M
g, Mn, Mo, Na, Nb, Nd, Ni, Si, S
When one or more elements are added from among n, Ta, Ti, V, W, and Zr, the reflectance, corrosion resistance, heat resistance,
An aluminum thin film with enhanced strength and the like can be obtained.
When Cu and / or Si is added as a wiring material such as I, it is possible to cope with thinning.

In the target of the present invention, the additive amount of the additive element is 0.1 to the target in the total amount of the additive element.
1 to 10% by weight. When the content is 0.1% by weight or less, the macroscopic concentration distribution of the additional element is improved without controlling the concentration portion of the additional element. If it exceeds 10% by weight, it becomes difficult to produce a single crystal material in which a concentrated portion of the additional element is micro-dispersed.

In the target of the present invention, the enriched portion of the additional element refers to a compound of an alloy element and aluminum or a layer formed of a plurality of alloy elements but not forming a compound or compound but having a high alloy element concentration. By
Since the enriched portion of the added element is distributed continuously or intermittently in the direction perpendicular to the casting method of the single crystal at a distance of 0.05 mm to 0.2 mm and in the casting direction of the single crystal, High-purity aluminum with a low added element concentration is obtained between the element enrichment sections. During the enrichment section when the additive element does not form a compound, the additive element is in a continuously changed state.

In the target of the present invention, the concentration of the macroscopic additive element can be measured by a photoelectric photometric emission spectrometer or the like used for analyzing impurities in ordinary aluminum, and shows an average concentration in a range of several mm. . This concentration distribution is expressed as a percentage of ± {(maximum concentration−minimum concentration) / (maximum concentration + minimum concentration)}. When the target of the present invention is used as a sputtering target, it is ± 10%.
%, It can be used without practical problems.

Generally, a subcrystal grain boundary is usually formed in a single crystal such as aluminum (alloy) produced by a solidification method. When the target of the present invention is used as a target having a high film formation rate using a crystal orientation having a high sputtering rate and an improvement in bottom coverage of fine wiring utilizing an aluminum atom emission component perpendicular to the target surface, If the deviation of the crystal orientation based on the crystal grain boundaries is within 10 °, it can be used without practical problems.

[0022]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 The inner dimension of the opening horizontally mounted on the bottom of the crucible has a width of 400.
An aluminum single crystal having a width of 395 mm, a thickness of 15 mm, and a length of 300 mm having a (110) plane as a seed crystal is charged into a graphite mold having a height of 15 mm, a height of 15 mm, and a length of 200 mm. Starting from the outlet end of the mold,
A water cooling nozzle was set at a position of a seed crystal of 100 mm in the opposite direction to the molten aluminum alloy containing 5% copper,
The raw material aluminum alloy charged in the crucible was melted while cooling at room temperature (20 ° C.) water 1 liter / minute. After the temperature of the aluminum alloy melt at the inlet of the mold is stabilized at 720 ° C, it is confirmed that the seed crystal is partially melted in the mold and the position of the solidification interface is constant. Then, the cooling position of the seed crystal is changed to the outlet end of the mold. The side was moved 10 mm and held for 15 minutes. Then 10
0.2 mm was drawn at a speed of 0 mm / min, and casting was started. Subsequently, in the same manner, a continuous cast plate of an aluminum alloy single crystal having a length of 600 mm and an upper surface having a (110) plane was obtained at a casting speed of 4 mm / min at a casting speed of 4 mm / min. The crystal orientation of the obtained plate was measured by the Schultz reflection orientation by X-ray diffraction, the measurement of the interval between the concentrated portions of added copper as shown in FIG. 1 was performed by microstructure observation, and the copper concentration distribution was 1 mm chamfered. The surface of the cast material was subjected to macroscopic measurement using an emission spectrometer [GQM-75 manufactured by Shimadzu Corporation]. Table 1 shows the measurement results. The enriched portion of copper as an additional element was distributed at intervals of 0.19 mm in a direction perpendicular to the casting (solidification) direction of the obtained single crystal and continuously or intermittently in the casting direction of the single crystal. .

Example 2 A continuous cast plate having a length of 600 mm was obtained under the same conditions as in Example 1 except that the casting conditions were set at a casting speed of 7 mm per minute by drawing 0.2 mm at a time interval of 1.7 seconds. . Table 1 shows the measurement results of the crystal orientation, the deviation of the crystal orientation of the sub-crystal grains, the interval between the copper enrichment portions, and the macroscopic copper concentration distribution. The enriched portion of copper as an additional element was continuously or intermittently distributed in the casting direction of the single crystal.

Example 3 Example 1 was repeated except that the casting conditions were set to 10 mm per minute by drawing 0.2 mm at 1.2 second intervals.
Under the same conditions as above, a continuous cast plate having a length of 600 mm was obtained. Table 1 shows the measurement results of the crystal orientation, the deviation of the crystal orientation of the sub-crystal grains, the interval between the copper enrichment portions, and the macroscopic copper concentration distribution. The enriched portion of copper as an additional element was continuously or intermittently distributed in the casting direction of the single crystal.

Example 4 Example 1 was repeated except that the casting conditions were set at a casting speed of 20 mm per minute by drawing 0.2 mm at 0.6 second intervals.
Under the same conditions as above, a continuous cast plate having a length of 600 mm was obtained. Table 1 shows the measurement results of the crystal orientation, the deviation of the crystal orientation of the sub-crystal grains, the interval between the copper enrichment portions, and the macroscopic copper concentration distribution. The enriched portion of copper as an additional element was continuously or intermittently distributed in the casting direction of the single crystal.

[0026]

[Table 1]

COMPARATIVE EXAMPLE 1 A casting speed of 2.2 mm per minute was obtained by drawing 0.1 mm at the start of casting and then drawing 0.1 mm at 2.7 second intervals thereafter. Under the same conditions as in Example 1, a continuous cast plate having a length of 600 mm was obtained. Table 2 shows the measurement results of the crystal orientation, the deviation of the crystal orientation of the sub-crystal grains, the interval between the copper enriched portions, and the macroscopic copper concentration distribution.

Comparative Example 2 Example 1 was repeated except that the amount of withdrawal at the start of casting was 0.5 mm, and the subsequent casting conditions were 60 mm per minute by withdrawing 0.5 mm at 0.5 second intervals. Under the same conditions, a continuous cast plate having a length of 600 mm was obtained. Crystal orientation,
Table 2 shows the measurement results of the deviation of the crystal orientation of the sub-crystal grains, the interval between the copper enrichment portions, and the macroscopic copper concentration distribution.

[0029]

[Table 2]

[0030]

According to the present invention, it is possible to obtain a crystal orientation controlled aluminum alloy single crystal target in which the macroscopic concentration of the additive element is made uniform by dispersing the additive element finely and uniformly. This makes it possible to improve the uniformity of the film quality and the film forming properties of the aluminum thin film produced by the sputtering method, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a microstructure observation diagram of an aluminum alloy single crystal target of the present invention.

[Explanation of symbols]

 1. 1. Additive element concentrating unit 2. Concentration unit interval Solidification direction

Claims (8)

[Claims] An aluminum alloy having a purity of 99.9% by weight or more and one of the elements having atomic numbers of 3 to 83, excluding rare gases.
In an aluminum alloy single crystal solidified and cast in one direction to which a seed or two or more additional elements are added, the additional element is contained in a total range of 0.1 to 10% by weight, and the enriched portion of the additional element is In a direction perpendicular to the casting direction of the single crystal.
An aluminum alloy single crystal target characterized by being distributed continuously or intermittently in the casting direction of the single crystal at an interval of 05 mm to 0.2 mm. 2. The aluminum alloy single crystal target according to claim 1, wherein the concentration distribution of the additional element is within ± 10%. 3. The crystal orientation of an aluminum alloy single crystal to be a sputtering surface is (100), (110) or (111).
The aluminum alloy single crystal target according to claim 1 or 2, wherein 4. The difference between the crystal orientation of an aluminum alloy single crystal and the crystal orientation of subcrystal grains contained in the alloy single crystal is 10 °.
The aluminum alloy single crystal target according to any one of claims 1 to 3, wherein 5. The method according to claim 1, wherein the additive element is Ag, Au, Ca, Co, C.
r, Cu, Fe, Ge, Hf, In, Li, Mg, M
n, Mo, Na, Nb, Nd, Ni, Si, Sn, T
5. The aluminum alloy single crystal target according to claim 1, wherein the target is one or more elements selected from a, Ti, V, W, Y, and Zr. 6. The aluminum alloy single crystal target according to claim 1, wherein the additional element is Cu and / or Si. 7. Using a heat insulating template and a seed crystal, heat-melted single crystal raw material is brought into contact with the seed crystal to partially dissolve the seed crystal and then start growing the single crystal. In a typical production method, the raw material and the seed crystal of the single crystal are aluminum or an alloy thereof, and after the dissolution of the seed crystal has substantially stagnated, the seed crystal is grown by starting or strengthening the cooling of the seed crystal, 1. The length equivalent of the single crystal grown from the seed crystal by the cooling is set in the direction opposite to the crystal growth direction.
2. The aluminum alloy single crystal target according to claim 1, wherein the single crystal grown from the seed crystal at a speed in the range of 5 mm / min to 100 mm / min is continuously or intermittently drawn from a mold to grow the single crystal. 8. The aluminum alloy single crystal target according to claim 1, wherein the target has a structure in which two or more single crystal materials are combined in parallel or radially.