JP2003247063A - W sputtering target hardly causing particle, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a W sputtering target hardly causing particle and used for depositing a transparent conductive film for a panel display and an electrode film for a semiconductor device by sputtering. <P>SOLUTION: The W sputtering target hardly causing particle has a sintered structure in which W-compound particle phases are dispersed in a W matrix. When the maximum diameter of the above W-compound particle phases is A μm and the minimum diameter is B μm, (A+B)/2≤6 μm is satisfied. This target can be manufactured by filling a container with W powder, holding the container filled with the W powder at 850 to 1,250°C while carrying out deaeration, and then vacuum-sealing the container to perform hot isostatic pressing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a W sputtering target for forming a transparent conductive film in a panel display or an electrode film of a semiconductor device by sputtering, which produces less particles.

[0002]

2. Description of the Related Art Generally, it is known that a transparent conductive film in a panel display or an electrode film of a semiconductor device is formed by sputtering using a W target. The W target used at this time is known. As a method of producing, (a) a W powder is filled in a container, the container filled with the W powder is deaerated, vacuum-sealed, and hot isostatically pressed, or (b) the W powder in hydrogen. A method is known in which a W ingot obtained by sintering is rolled at a heating temperature of 1300 to 1600 ° C. so as not to be recrystallized during processing, and then a recrystallization heat treatment is performed (Japanese Patent Laid-Open No. 2000-31).
9774 gazette). W produced by the method (a)
The target has a sintered structure in which the W compound particle phase is dispersed in the W substrate, and the W target manufactured by the method (b) has a rolled structure in which the W compound particle phase is dispersed in the W substrate. is doing. A commercially available W powder having a purity of at least 99.95% is used for manufacturing a normal W target.

[0003]

However, when a W target produced by using the above-mentioned conventional commercially available W powder is used and sputtering is performed at high power to form a film at a high speed, it is inevitable that many particles are generated. There has been a demand for a W sputtering target that generates less particles even when sputtered with high power. On the other hand, in order to reduce the generation of particles when forming a W thin film by sputtering, a high-purity W target powder is produced using a high-purity W raw material powder with extremely few impurities, and sputtering is performed using this high-purity W target. It is known that the generation of particles is reduced when it is performed, and the generation of particles decreases as the W target has a higher purity. However, since the higher the purity of W powder, the higher the price of W target, the higher the price of W target, especially the demand for the production of transparent conductive films in consumer panel displays and electrode films of semiconductor devices, which are required to reduce costs. The current situation is that we cannot respond.

[0004]

Therefore, the present inventors have
Studies were conducted to produce W-sputtering targets with low particle generation using commercially available W powders with a minimum purity of 99.95%. As a result, (a) W
The size of the W compound particle phase dispersed in the base material has a great influence on the abnormal discharge and thus on the generation of particles,
The finer the W compound particle phase dispersed in the substrate of the W target, the smaller the number of particles generated during sputtering. If the maximum diameter of the W compound particle phase is A μm and the minimum diameter is B μm, (A + B) / 2 is When high power sputtering is performed using a W target having a structure of 6 μm or less, the number of particles generated during sputtering is drastically reduced. (B) The fine W compound particle phase in which (A + B) / 2 is 6 μm or less is dispersed. The W target having a texture of
850 to 1250 ° C while degassing the container filled with powder
The research result was obtained that the temperature was maintained in the above temperature range, and then the container was vacuum-sealed and hot isostatic pressing was performed.

The present invention has been made on the basis of the results of such research. (1) In a W sputtering target having a sintered structure in which a W compound particle phase is dispersed in a W matrix, the W compound The maximum diameter of the particle phase is Aμ
m, and the minimum diameter is Bμm, (A + B) / 2 is 6μm
The following W sputtering target with less particle generation, (2) W powder was filled in a container, and the container filled with this W powder was degassed and held in a temperature range of 850 to 1250 ° C., and then the container was vacuum-sealed. Then, the method for producing a W sputtering target with less particle generation by hot isostatic pressing is characterized.

The W sputtering target described in (1) above with less particle generation is manufactured by finally hot isostatic pressing, but the size of the W target that can be manufactured by hot isostatic pressing is There is a limit. However, in recent years, the size of the panel display tends to expand more and more, and it is necessary to roll the hot isostatic press to manufacture such a larger W sputtering target. In order to roll the hot isostatic press body, it is preferable to roll the hot isostatic press body wrapped in the container as it is (hereinafter, a method of rolling the hot isostatic press body wrapped in the container as it is Called pack rolling). Even if the base material obtained by the pack rolling has a W structure having a rolled structure, if the (A + B) / 2 of the W compound particle phase dispersed in the base material is 6 μm or less, it occurs during sputtering. The result of the study was that the number of particles was extremely small.

Therefore, the present invention provides (3) a W sputtering target having a rolling structure in which a W compound particle phase is dispersed in a W substrate, wherein the maximum diameter of the W compound particle phase is A μm and the minimum diameter is B μm. Then, (A +
B) / 2 W sputtering target having a particle size of 6 μm or less and less particle generation, (4) W powder is filled in a container, and the container filled with this W powder is degassed at 850
The present invention has a feature in a method for producing a W sputtering target in which particles are less likely to occur, in which a container is vacuum-sealed, hot isostatically pressed, and pack-rolled after being kept in a temperature range of ˜1250 ° C.

Further, the W compound particle phase dispersed in the base material of the W target having a recrystallized structure obtained by carrying out the recrystallization heat treatment after the pack rolling is (A)
According to the research result, if + B) / 2 is 6 μm or less, the number of particles generated during sputtering is extremely small. Therefore, the present invention provides (5)
In a W sputtering target having a recrystallized structure in which a W compound particle phase is dispersed in a W substrate, (A + B) / 2 is 6 μm or less when the maximum diameter of the W compound particle phase is A μm and the minimum diameter is B μm. (6) W powder was charged into a container, and the container filled with this W powder was degassed and held in a temperature range of 850 to 1250 ° C., and then the container was vacuum-sealed. The present invention has a feature in a method for producing a W sputtering target in which few particles are generated by hot isostatic pressing, pack rolling, and then recrystallization heat treatment.

In order to manufacture the W sputtering target of the present invention with less particle generation, a commercially available W powder is filled in a container, and the container filled with the W powder is deaerated and kept in a temperature range of 850 to 1250 ° C. After that, it is obtained by vacuum-sealing the container and hot isostatic pressing. The reason for degassing while maintaining the container filled with W powder in the temperature range of 850 to 1250 ° C. is that the W compound particle phase does not become fine even when degassing at less than 850 ° C., and the maximum diameter: A μm,
Minimum diameter: Assuming Bμm, the value of (A + B) / 2 is 6μm
This is because it is not preferable because it will exceed. On the other hand, degassing at a temperature above 1250 ° C. is not preferable because the container is deformed during degassing and the container is severely damaged by oxidation. Therefore, the degassing temperature is 850
-1250 ° C (preferably 950-1200 ° C). The contents of oxygen and nitrogen contained in the W sputtering target of the present invention obtained by degassing in this temperature range and then hot isostatic pressing are respectively oxygen: 40 ppm or less and nitrogen: 25 ppm or less.
It is considered that this is because deaeration removes adsorbed moisture and adsorbed gas contained in the W powder and sublimates and removes the oxidized W contained in the W powder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Example 1 A commercially available pure W powder having a nominal particle diameter of 3 μm was filled in a stainless steel pipe-equipped container while vibrating, and degassed using a vacuum pump, as shown in Table 1. After heating to the degassing temperature, the temperature was maintained at this temperature for 8 hours for degassing, and then the pipe portion was welded and sealed. Next, this sealed stainless steel container was hot isostatically pressed under the conditions of 1250 ° C., 1400 atmospheric pressure, and holding for 6 hours. The container portion of the hot isostatic press obtained in this manner was removed by machining to produce W targets 1 to 4 of the present invention having dimensions of diameter: 125 mm and thickness: 12 mm.

Example 2 A commercially available pure W powder having a nominal particle size of 3 μm was charged into a stainless steel pipe-equipped container while vibrating, and the gas was deaerated using a vacuum pump while the deaeration treatment shown in Table 1 was performed. After heating to the temperature, this temperature was maintained for 8 hours for degassing, and then the pipe portion was welded and sealed. Next, this sealed stainless steel container was hot isostatically pressed under the conditions of 1250 ° C., 1400 atmospheric pressure, and holding for 6 hours. The hot isostatic pressing body thus obtained is further pack-rolled by rolling at a temperature of 1250 ° C., and the container portion of the obtained pack-rolled body is removed by machining to have a diameter of 12
Inventive W targets 5 to 8 having dimensions of 5 mm and thickness: 12 mm were produced.

Example 3 The container portion of the packed rolled body produced in Example 2 was removed by machining, and the recrystallization heat treatment was performed under the conditions of a temperature of 1560 ° C. and a holding time of 20 minutes, and then this recrystallization heat treatment was performed. Due to this diameter: 125 mm, thickness: 12 m
Inventive W targets 9-11 having a dimension of m were produced.

COMPARATIVE EXAMPLE In Example 1, a commercially available pure W powder having a nominal particle diameter of 3 μm was filled in a stainless steel pipe-equipped container while vibrating, and degassed using a vacuum pump until the temperature reached 800 ° C. Comparative W having dimensions of diameter: 125 mm, thickness: 12 mm as in Example 1 except that the body part is heated.
A target 1 was produced. Further, in the same manner as in Example 1 except that the container body was heated to 1270 ° C. while being degassed using a vacuum pump, the diameter was 125 mm and the thickness was 12
A comparative W target 2 having a dimension of mm was produced.

Conventional Example A commercially available pure W powder having a nominal particle size of 3 μm was filled in a stainless steel pipe-equipped container while vibrating, the container was degassed at room temperature, and then the pipe portion was welded and sealed. The same stainless steel container as in Example 1 at 1250 ° C. and 1400a
Hot isostatic pressing was carried out under the condition of tm for 6 hours. The container portion of the hot isostatic press body thus obtained was removed by machining to give a diameter of 125 mm and a thickness of 1
A conventional W target having a dimension of 2 mm was made.

The W targets 1 to 11 of the present invention obtained in Examples 1 to 3 and the comparative W target 1 obtained in Comparative Examples
2 and the conventional W targets obtained in the conventional examples, the contents of oxygen and nitrogen contained in the targets were measured and the results are shown in Table 1. Further, the structures of these targets are observed with a metallurgical microscope and dispersed in the substrate. The maximum diameter A and the minimum diameter B of the W compound particle phase were measured, the value of (A + B) / 2 was determined, and the results are shown in Table 1.

Further, the W targets 1 to 11 of the present invention, the comparative W targets 1 and 2 and the conventional W target were attached to a DC magnetron sputtering apparatus, and the DC power:
5 under the condition of 200 W, Ar pressure: 3 × 10 ⁻³ Torr
After sputtering for 0 hour, sputtering was performed for 10 minutes to form a W thin film, and the number of particles adhering to the W thin film was measured. The results are shown in Table 1.

[0017]

[Table 1]

From the results shown in Table 1, the W target of the present invention 1 obtained by carrying out hot isostatic pressing after holding the container filled with W powder in the temperature range of 850 to 1250 ° C. while degassing 4. Inventive W targets 5 to 8 obtained by further pack rolling, and Inventive W targets 9 to 8 obtained by recrystallization heat treatment
No. 11 has a smaller oxygen and nitrogen content than the conventional W target obtained by degassing at room temperature and then hot isostatic pressing, and the W compound particle phase dispersed in the matrix is extremely fine. Therefore, it can be seen that the W targets 1 to 11 of the present invention manufactured in Examples 1 to 3 have a significantly smaller number of particles generated during sputtering as compared with the conventional W target manufactured in the conventional example. Also, the comparative W obtained by degassing at a temperature outside the conditions of the present invention
It can be seen that the targets 1 and 2 generate slightly more particles during sputtering.

[0019]

According to the present invention, it is possible to provide a W sputtering target with less generation of particles during sputtering, and it is possible to form a transparent conductive film in a panel display or an electrode film of a semiconductor device with a good yield. Is played.

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Claims (7)

[Claims] 1. In a W sputtering target having a sintered structure in which a W compound particle phase is dispersed in a W matrix, the W compound particle phase has a maximum diameter of A μm and a minimum diameter of B.
(A + B) / 2 is 6 μm or less, where W is the W sputtering target with little particle generation. 2. A container is filled with W powder, and the container filled with this W powder is deaerated and held in a temperature range of 850 to 1250 ° C., then the container is vacuum-sealed and hot isostatic pressing is performed. A method for producing a W sputtering target, which is characterized by: 3. A W sputtering target having a rolling structure in which a W compound particle phase is dispersed in a W substrate, wherein the W compound particle phase has a maximum diameter of A μm and a minimum diameter of B.
(A + B) / 2 is 6 μm or less, where W is the W sputtering target with little particle generation. 4. A container is filled with W powder, the container filled with this W powder is degassed and kept in a temperature range of 850 to 1250 ° C., and then the container is vacuum-sealed and hot isostatic pressed. Furthermore, a method for producing a W sputtering target with little particle generation is characterized in that pack rolling is performed. 5. In a W sputtering target having a recrystallized structure in which a W compound particle phase is dispersed in a W matrix, the W compound particle phase has a maximum diameter of A μm and a minimum diameter of B.
(A + B) / 2 is 6 μm or less, where W is the W sputtering target with little particle generation. 6. A container is filled with W powder, and the container filled with this W powder is deaerated and held in a temperature range of 850 to 1250 ° C. Then, the container is vacuum-sealed and hot isostatic pressed. A method for producing a W sputtering target with less particle generation, further comprising pack rolling and then recrystallization heat treatment. 7. The W sputtering target according to claim 1, 3 or 5, wherein oxygen contained in the W sputtering target is 40 ppm or less and nitrogen is 25 ppm or less.