JP2002146521A - Method for manufacturing gold target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which, with respect to the improvement of product yield, a shape hardly causing ingot defects can be formed and, even if the ingot defects occur, they can be easily removed without deteriorating the yield and further to provide a method by which a target having 0.1-10 mm equiaxed crystals can be manufactured by finding the optimum relation between draft and annealing and film deposition characteristics at sputtering can be stabilized, with a view to carrying out the improvement of product yield at manufacturing and the stabilization of sputtering characteristics. SOLUTION: The method for manufacturing the gold target comprises a step of rolling a square-shaped ingot having a dimensional ratio where the ratio of height to the length of a side (height/a side) is regulated to 0.06-0.3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a gold sputtering target for producing a gold thin film used for semiconductors, capacitors, crystal oscillators and the like. A gold thin film is mainly used as an electrode material in semiconductor and capacitor applications, and as a contact material in quartz oscillator applications.

[0002]

2. Description of the Related Art When manufacturing a gold target, it is usual that an ingot is cast in a vertical shape, and the side surface (width) of the ingot is a rolled surface. That is, a method has been widely used in which an ingot is cast so as to have an aspect ratio of 3 to 20, a casting defect portion on an ingot upper surface is removed by cutting, and only a healthy portion is rolled. This method has a disadvantage that the ratio of the cut portion is about 20%, which is not negligible, and leads to deterioration of the product rate. In addition, because of the good workability of gold, it is possible to perform rolling processing to the final shape without considering annealing during processing, and therefore, it has been manufactured without performing intermediate annealing. However, although there is an advantage that the manufacturing cost can be reduced because there is no annealing step in the middle, as a result, the crystal grain size of the target is not controlled, which causes a variation in film forming characteristics.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve the product rate during manufacturing and to stabilize the sputter characteristics. In other words, it is an object of the present invention to provide a method for improving the product rate, in which the shape of the ingot is hardly formed to have a defect, and even if the defect occurs, it can be easily removed without deteriorating the yield. Further, it is effective to control the crystal grain size to stabilize the film forming characteristics at the time of sputtering. For this purpose, the optimum relationship between the workability and the annealing was found.
An object of the present invention is to provide a method for manufacturing a target having an equiaxed crystal of mm.

[0004]

The present invention provides: A method for producing a gold target, comprising rolling a square ingot having the following dimensional ratio: height ratio to height of one side (height / side): 0.06
~ 0.3 2. A method for manufacturing a gold target, comprising rolling a round ingot having the following dimensional ratio: height to diameter ratio (height / diameter): 0.06 to 0.
3 3. The gold target according to the above 1 or 2, wherein the upper and lower surfaces of the ingot after melting and casting are rolled using a gold ingot from which defects at the time of casting have been removed by heating with a gas burner until the surface is melted. 3. Manufacturing method of The upper and lower surfaces of the ingot from which casting defects have been removed are rolled at a working degree of 25 to 45% so as to be the upper and lower surfaces of the rolling, and then annealed at 900 ° C. ± 50 ° C. for 10 minutes to 4 hours and further processed. 70 after rolling at 25-45%
0 ° C. ± 50 ° C., annealing for 10 minutes to 4 hours, rolling of 25 to 45%, and rolling without final annealing to obtain a product of a gold target. Manufacturing method The upper and lower surfaces of the ingot from which casting defects were removed were rolled at a working degree of 25 to 45% so as to be upper and lower surfaces of the rolling, and then annealed at 900 ° C. ± 50 ° C. for 10 minutes to 4 hours. 5. A method for producing a gold target, wherein a product is rolled to a product of up to 45% and rolled without final annealing. The upper and lower surfaces of the ingot from which casting defects have been removed are rolled at a working degree of 25 to 45% so as to be the upper and lower surfaces of the rolling, and then annealed at 900 ° C. ± 50 ° C. for 10 minutes to 4 hours and further processed. 70 after rolling at 25-45%
Annealing at 0 ° C. ± 50 ° C. for 10 minutes to 4 hours, rolling at a rate of 25 to 45%, and final rolling up to a product without final annealing.
6. The method for producing a gold target according to The upper and lower surfaces of the ingot from which casting defects have been removed are rolled so as to be the upper and lower surfaces of the roll, and the degree of processing is 25 to 45.
%, Annealing at 900 ° C. ± 50 ° C. for 10 minutes to 4 hours, further rolling at 25 to 45%, and rolling without final annealing to obtain a product. 7. Method for producing gold target according to any one of 1 to 3 Rolling and annealing reduce the crystal grain size to 0.1 mm to 1 mm.
The method for producing a gold target according to any one of the above items 1 to 7, wherein the particles are controlled to have equiaxed grains of 0 mm.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Gold is melted in an air atmosphere using a usual electric furnace. The mold is cast iron bottom and cast iron side plate 4.
A square mold combining a plurality of sheets or a round mold combining a cast iron cylinder is used. Before casting the ingot, the inner wall of the mold is sufficiently heated with an LPG burner to remove adhering moisture and to attach soot to the inner wall. Even a small amount of water adhering to the mold generates bubbles (defects) in the ingot and needs to be removed. Large amounts of water can cause a small explosion. The reason that soot is adhered to the inner wall is to make it easier to separate the ingot and the mold.

The size of the mold is selected to be the most suitable for the size of the target to be finally manufactured. At this time, in the case of a square mold, the ratio of the height to the length of one side of the upper surface or the lower surface should be considered. And, for round molds, the ratio of height to diameter. That is, the height of the ingot is 0.0 to the length (or diameter) of one side of the upper surface or the lower surface.
It is important to select the mold dimensions so that the ratio is between 6 and 0.3. For example, in order to manufacture a target of 203.2φ × 6t, 5000 g of gold is cast using a 100 × 120 × 25H mold and 100 × 120 × 21.6.
t ingots (height / length = 0.2
2 to 0.18).

[0007] For producing a round target, either a square mold or a round mold may be used. For the production of a square target, a square mold is more suitable in consideration of subsequent stripping after rolling. In addition, since it is easy to fix three of the four side plates of the square mold and to make the remaining one movable, it is possible to fine-tune the mold size according to the product size. It has the advantage that. In any case, it is necessary to make the shape such that a thin ingot having a height of 0.06 to 0.3 with respect to the length (or diameter) can be obtained. Table 1 shows examples of mold dimensions used and obtained ingot sizes for targets of various dimensions. Table 1 shows that
In addition, the product weight, ingot weight and product ratio are also described.

[0008]

[Table 1]

The sample 1 of the square ingot has a ratio of height to length of one side (height / side) of 0.21 to 0.18.
The product rate reaches 74.9%. Sample 2 of the round ingot had a height to diameter ratio (height / diameter) of 0.2.
3, and the product rate is 85.2%. Sample 3 of the round ingot has a height to diameter ratio (height / diameter) of 0.13, and the product ratio is further improved to 90.8%. The sample 4 of the square ingot has a height ratio to one side length (height / one side) of 0.15 to 0.14, and a product ratio of 93.8%. Sample 5 of the square ingot is
The ratio of the height to the length of one side (height / side) is 0.16
０．１0.11 and the product rate is 72.5%. All samples are within the scope of the present invention, and the product rate exceeds 70%.

Next, the upper and lower surfaces of the obtained ingot are heated by an LPG burner or the like until the surface is melted. On the upper surface, there is a nest in the final solidification portion, but the nest can be removed by heating the surface until the surface is partially melted. Defects caused by rebound of contact with the mold may occur on the lower surface, but these defects can also be removed by heating until partial melting. After performing these operations, the upper and lower surfaces subjected to the heat treatment are rolled as rolling surfaces. In this case, the cutting process for removing the defect is not required. That is, a yield of 100% from the ingot to the rolling in the next step is possible.

At the time of rolling, for example, rolling of 1 mm is repeated in one pass. Here, it is desirable that the square ingot is cross-rolled so that the length and width are the same. In the case of a round ingot, it is necessary to shift the rolling direction for each pass so that the round shape can be maintained even after rolling. The first annealing is performed when the rolling processing reaches a working degree of 25 to 45% in total. In rolling, since gold is extremely extensible, processing itself can be performed without management of a pass schedule and without annealing.
However, in order to control the crystal grain size, it is necessary to control the degree of work and perform annealing. First annealing at 900 ° C
Perform at ± 50 ° C. for 10 minutes to 4 hours. 3 to 10m
m equiaxed crystals can be obtained. If annealing is not performed, the crystal will have a cast structure elongated in the rolling direction, and an equiaxed crystal cannot be obtained.

After the first annealing, the rolling process is further continued.
Perform 5-45% processing. The grain size of the product is 3-10m
If it is desired to set it to m, the final thickness is set at this point. When the crystal grain size is further reduced to 3 mm or less,
At this point, the thickness is adjusted so as to be 25 to 45% thicker than the final sheet thickness. Here, the second annealing is performed at 700 ° C. ± 50 ° C. for 1 hour.
Perform for 0 minutes to 4 hours. 0.1 mm by this second annealing
An equiaxed crystal structure with a grain size of ３3 mm can be obtained. 2
After the second annealing, rolling is performed at a working degree of 25 to 45%, and the product is obtained without annealing. In order to make the rolling surface a product surface, there is no scratch on the rolling roll,
It is necessary that the surface of the metal plate is not scratched, and for this purpose it is necessary to manage rolling rolls.

With regard to the thickness of the sheet, since it is finished to the final thickness by final rolling, it is not necessary to perform cutting by machining in the thickness direction, and a high yield can be secured. The square target is finished to the final shape by rough cutting with a shear and processing with a milling machine. The round target is finished to the final shape by lathe processing. Since the cutting is performed only for adjusting the outer shape, a yield of about 80% can be secured. The surface of the machine-finished target is buffed, and for those requiring bonding, Cu plating is performed on the back surface, and after bonding a Cu film, bonding is performed.
A target that does not require bonding is finished after buffing.

[0014]

Examples and Comparative Examples Next, description will be made based on Examples and Comparative Examples. These are for the purpose of facilitating the understanding of the present invention, and the present invention is not limited to these. (Example 1) 5000 g of a gold raw material was placed in a graphite crucible, and gold was melted in an electric furnace. On the other hand, a cast iron mold is assembled to 100 mm x 120 mm, and the inner wall of the mold is LPG.
Heated with a burner for 20 minutes and poured molten gold into a place where soot was sufficiently adhered to the inner wall of the mold, and 100 mm x 12 mm
An ingot of 0 mm × 21.6 mmt was obtained. The ingot was removed from the mold, and the upper surface of the ingot was heated with an LPG burner until the surface was melted. Next, the lower surface of the ingot was similarly heated until the surface was melted.

The ingot was cross-rolled by about 1 mm at a time, and the roll was 136 mm × 136 mm and 14 m thick.
m. Here, the rolled plate was placed in an electric furnace at 900 ° C. and annealed for 1 hour. After annealing, it was further cross-rolled to 9 mm and held in an electric furnace at 700 ° C. for 1 hour. After the second annealing, rolling was further continued to finally obtain a thickness of 6 mm and straightened until a sufficient flatness was obtained. From this plate material, a 203.2φ disk was cut by lathe processing and buffed to obtain a target. The particle size of the obtained target is 1
mm equiaxed crystal

Example 2 4600 g of a gold raw material was put into a graphite crucible, and gold was melted in an electric furnace. On the other hand, a cast iron mold having a diameter of 110 mm is prepared, and the inner wall of the mold is LPG.
Heat it with a burner for 20 minutes and pour molten gold into a place where soot has sufficiently adhered to the inner wall of the mold.
A 5 mmt ingot was obtained. The ingot was removed from the mold, and the upper surface of the ingot was heated with an LPG burner until the surface was melted. Next, the lower surface of the ingot was similarly heated until the surface was melted. This ingot was rolled by a rolling amount of about 1 mm at a time while shifting the rolling direction by 45 degrees every rolling, and rolled to a thickness of 14 mm. The reason why the rolling direction is shifted by 45 degrees here is to maintain a circular shape. The rolled plate was placed in a 900 ° C. electric furnace at the stage of 14 mm and annealed for 30 minutes.

After annealing, further rolled to 9 mm and 700 °
C for 30 minutes. After the second annealing, rolling was further continued to finally obtain a thickness of 5 mm and straightened until a sufficient flatness was obtained. From this plate material by lathe processing 1
An 80φ disk was cut and buffed to obtain a target. The particle size of the obtained target was 0.6 mm equiaxed crystal. This target is of a type used by bonding to a copper backing plate, and Cu plating was performed on the bonding surface of the target by the following method.

First, the masking surface except for the bonding surface is used.
Mask, then scotch the bonding surface
Treat with bright. Next, the target is copper sulfate
1.78A (0.07A / cm) ²)
For a total of 2 hours. At this time,
In order to compensate for non-uniformity, make contact points at least once
It is necessary to perform plating while changing. In this process
A Cu film having a thickness of about 20 μm could be formed. C
Copper plating backing plate with In as brazing material after u plating
Was bonded to the target.

Example 3 13020 g of a gold raw material was put into a graphite crucible, and gold was melted in an electric furnace. On the other hand, a cast iron mold was assembled to 140 mm × 210 mm, the inner wall of the mold was heated by an LPG burner for 20 minutes, and molten gold was poured into a state where soot was sufficiently adhered to the inner wall of the mold to obtain an ingot of 140 mm × 210 mm × 23 mmt. .

The ingot was removed from the mold, and the upper surface of the ingot was heated with an LPG burner until the surface was melted. Next, the lower surface of the ingot was similarly heated until the surface was melted. The ingot was rolled in the width direction in a rolling amount of about 1 mm at a time, and rolled to 215 mm × 210 mm and a thickness of 15 mm. Here, the rolled plate was placed in an electric furnace at 900 ° C. and annealed for 1 hour. After annealing, the final thickness was 10 mm by cross rolling. Straightening was performed until sufficient flatness was obtained. A 250φ disk was cut from this plate material by lathe processing, and buffed to obtain a target. The particle size of the obtained target was a 5 mm equiaxed crystal.

(Comparative Example) Gold material 6 in graphite crucible
250 g was charged and gold was melted in an electric furnace. On the other hand, a cast iron mold 20 mm × 120 mm × 150 mmH was prepared, the inner wall of the mold was heated by an LPG burner for 20 minutes, and molten gold was poured into a place where soot was sufficiently adhered to the inner wall of the mold, and an ingot of 20 mm × 120 mm × 135 mmH was poured. Obtained. A cavity during casting was formed on the upper surface of the ingot, and as a result of ultrasonic inspection, it was found that it was necessary to cut and remove a 27 mm portion from the upper surface. Therefore, cut 27mm from the upper surface, 20mm × 120m × 108m
m ingots were obtained. This ingot was cross-rolled by about 1 mm each time without any intermediate annealing, and 207 m
m × 207 mm × 6 mmt. From this plate material, a 203.2φ disk was cut by lathe processing and buffed to obtain a target. The grain size of the obtained target was such that the cast structure was elongated. Due to the cutting at the time of the ingot, the product rate was about 60%, which was worse than that of Example 1.

[0022]

According to the present invention, a gold ingot is formed in a shape in which defects are hardly formed, and even if a defect occurs, it can be easily removed without deteriorating the yield, so that a gold target can be manufactured with an extremely high efficiency of a product rate of about 80%. It has a remarkable effect, and depends on the optimum relationship between the degree of work and the annealing.
It is an excellent feature that it is possible to make an equiaxed crystal of mm, and it is possible to reduce the cost in the manufacturing process and to stabilize the film forming characteristics during sputtering.

Claims (8)

[Claims] 1. A method for producing a gold target, comprising rolling a square ingot having the following dimensional ratio. Ratio of height to length of one side (height / side): 0.06
~ 0.3 2. A method for producing a gold target, comprising rolling a round ingot having the following dimensional ratio. Ratio of height to diameter (height / diameter): 0.06-0.
3 3. The method according to claim 1, wherein the upper and lower surfaces of the ingot after melting and casting are heated by a gas burner until the surface is melted, and the ingot is rolled using a gold ingot from which defects during casting have been removed. Or the method for producing a gold target according to 2. 4. A working degree of 25 to 45 so that the upper surface and the lower surface of the ingot from which casting defects have been removed are the upper and lower surfaces of the rolling.
% After rolling at 900 ° C ± 50 ° C, 10 min ~ 4
After annealing for an hour, rolling at a working degree of 25 to 45%, annealing at 700 ° C. ± 50 ° C. for 10 minutes to 4 hours, rolling at 25 to 45%, and final annealing A method for producing a gold target, wherein a rolling process is performed without performing the production. 5. A working degree of 25 to 45 so that the upper surface and the lower surface of the ingot from which casting defects have been removed become upper and lower surfaces of the rolled material.
% After rolling at 900 ° C ± 50 ° C, 10 min ~ 4
A method for producing a gold target, wherein annealing is performed for a long time, rolling is further performed by 25 to 45%, and rolling is performed without final annealing to obtain a product. 6. An ingot from which casting defects have been removed, the upper and lower surfaces of which are rolled so that the upper and lower surfaces thereof become upper and lower surfaces of a roll.
% After rolling at 900 ° C ± 50 ° C, 10 min ~ 4
After annealing for an hour, rolling at a working degree of 25 to 45%, annealing at 700 ° C. ± 50 ° C. for 10 minutes to 4 hours, rolling at 25 to 45%, and final annealing The method for producing a gold target according to any one of claims 1 to 3, wherein a rolling process is performed without performing the process. 7. A working degree of 25 to 45 so that the upper surface and the lower surface of the ingot from which casting defects have been removed become upper and lower surfaces of the rolled material.
% After rolling at 900 ° C ± 50 ° C, 10 min ~ 4
The method for producing a gold target according to any one of claims 1 to 3, wherein annealing is performed for a time, rolling is further performed by 25 to 45%, and rolling is performed without final annealing to obtain a product. . 8. The grain size is reduced to 0.1 by rolling and annealing.
The method for producing a gold target according to any one of claims 1 to 7, wherein the grains are controlled to have equiaxed grains of 1 mm to 10 mm.