JP6361543B2 - Bi-Ge target for sputtering and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sputtering Bi-Ge target used for manufacturing a phase change optical recording disk and the like and a manufacturing method thereof.

Conventionally, as a medium for recording character information, video information, or music information, various phase change optical recording discs (hereinafter referred to as “phase change discs”) such as CD-RW, DVD-RW, and DVD-RAM. It is used.
These phase change discs have a slightly different configuration of the film formed on the disc depending on the recording method. However, a dielectric layer, a recording layer, a dielectric layer, and a reflective layer are formed on a transparent plastic substrate by sputtering. Manufactured by sequentially laminating layers.

In recent years, with the increase in the amount of information that can be recorded on one disc, it is required to increase the data writing speed and erasing speed of the phase change type disc.
As a countermeasure, it has been proposed to form a Bi—Ge layer between the dielectric layer and the recording layer by sputtering. Thus, by arranging the Bi-Ge layer between the dielectric layer and the recording layer, it becomes possible to increase the data writing speed and the erasing speed of the phase change disk.

Therefore, in order to form this Bi-Ge layer by sputtering, Patent Document 1 includes 20 to 80 at% Bi, the balance Ge and inevitable impurities, and the crystal grain size of Ge is 500 μm or less. Also disclosed is a Ge-Bi alloy target for sputtering.
Here, by increasing the sintering density in the sputtering Ge—Bi alloy target, particles from the sputtering Ge—Bi alloy target are reduced, and abnormal discharge during sputtering is also reduced.

  In this patent document 1, since a Ge—Bi alloy target having a high sintering density cannot be obtained by the powder metallurgy method in which a mixed powder of Ge powder and Bi powder is sintered, the Ge—Bi alloy powder is sintered. To produce a Ge—Bi alloy target for sputtering (see paragraph numbers 0008 and 0014 of Patent Document 1).

JP 2003-277923 A

  However, in the Ge—Bi alloy target for sputtering disclosed in Patent Document 1, the composition of Bi contained in the Ge—Bi alloy target for sputtering is low (for example, within a range of 20 to 50 at%), and a high sintering density. It was difficult to obtain (see Patent Document 1, paragraph numbers 0023, 0026, etc.).

  Further, as a result of the study by the present inventors, in the conventional method of sintering the mixed powder of Ge powder and Bi powder, the composition of the sputtered film is desired in the initial stage of sputtering in addition to the low sintering density. The problem of deviating from the composition occurred.

  Therefore, the present invention provides a sputtering Bi-Ge target that can suppress the deviation of the composition of the sputtered film while shortening the empty sputtering time, and can obtain a high sintered density even when the Bi composition is low, and its An object is to provide a manufacturing method.

 As a preliminary study leading to the present invention, the inventors mixed and sintered Bi powder produced by crushing a Bi ingot with a vibration mill and Ge powder produced by crushing a Ge ingot with a vibration mill, Bi-Ge target for sputtering was produced by machining, and the composition of the sputtered film was evaluated using the Bi-Ge target for sputtering.

As a result, the following problems were found.
Since Bi has ductility as compared with Ge, Bi powder cannot be finely pulverized by treatment with only a vibration mill, unlike Ge powder.
For this reason, when a sputtered film is formed using the Bi-Ge target for sputtering produced using the Bi powder and Ge powder, the composition of the sputtered film deviates from a desired composition in the initial stage of sputtering. Occurred.
As a means to avoid such a problem, it is conceivable to stabilize the composition of Bi and Ge by performing idle sputtering in the initial stage of sputtering. The nature will decline.
Therefore, the present inventors have studied in detail the influence of the manufacturing method on the target structure, and have invented the sputtering Bi-Ge target of the present invention and the manufacturing method thereof.

  In order to solve the above-described problem, according to one aspect of the present invention, Bi is included in a range of 20 at% or more and 60 at% or less, and the balance is composed of Ge and unavoidable impurities. A sputtering Bi-Ge target is provided, which is made of a sintered body and has an average value of a distance between Ge phases interposed in a target material of 20 μm or more and 200 μm or less.

According to the present invention, since the average value of the distance between the Ge phases intervening in the target material is in the range of 20 μm or more and 200 μm or less, the sputtering surface of the sputtering Bi-Ge target in the stage before sputtering. In addition, the Ge structure can be sufficiently exposed. In other words, it is possible to reduce the proportion of the Bi structure exposed on the sputtering surface.
Accordingly, Ge can be sputtered from the initial stage of sputtering, so that it is possible to suppress the sputter film composition from deviating from a desired composition while shortening the idle sputtering time.
Moreover, since it becomes possible to suppress the composition of the sputtered film from deviating from a desired composition, the number of abnormal discharges can be suppressed.

  In addition, Bi is contained in the range of 20 at% or more and 60 at% or less, and the balance has a composition composed of Ge and inevitable impurities, so Bi that can sufficiently achieve the effect of increasing the speed of the phase change disk can be obtained. A -Ge thin film can be formed.

In the Bi-Ge target for sputtering, the oxygen concentration as the inevitable impurity may be 2000 mass ppm or less, and the sintered density y may satisfy the following expression (1).
y ≧ 0.1745 × x + 84.53 (1)
However, in said Formula (1), x is Bi amount (at%) contained in the said Bi-Ge target for sputtering.
The sintered density means a relative value with the actually measured density value with the density value calculated by the following equation (2) as 100%.
Density (100%) = 100 / [(Wa / Da) + (Wb / Db)] (2)
In the formula (2), Wa is the content of element A (wt%), Wb is the content of element B (wt%), Da = theoretical density of element A (g / cm ³ ), Db = element Theoretical density of B (g / cm ³ ).

  As described above, by setting the oxygen concentration contained in the Bi-Ge target for sputtering to 2000 mass ppm or less, a decrease in the sintered density can be suppressed and a deterioration in the characteristics of the sputtered film can be suppressed.

  Furthermore, generation | occurrence | production of a particle and abnormal discharge can be suppressed by satisfy | filling said Formula (1). Further, it is possible to suppress the deviation of the composition of the sputtered film while shortening the idle sputtering time.

In the Bi-Ge target for sputtering, at least one of the Bi powder and the Ge powder may be a pulverized powder.
In this way, by using at least one of Bi powder and Ge powder as pulverized powder, separation due to a difference in specific gravity between elements during mixing can be suppressed.

  In order to solve the above problems, according to another aspect of the present invention, a Bi ingot is formed by sequentially using a step of generating a Ge powder by crushing a Ge ingot by a vibration mill, a vibration mill, and a ball mill. And a step of producing a Bi powder having an average particle size in the range of 20 to 50 μm and an oxygen concentration of 1000 massppm or less, and the Bi powder and the remaining Ge powder are mixed. There is provided a method for producing a Bi-Ge target for sputtering, characterized by comprising a step of producing a mixture containing 20 to 60 at% of the Bi powder and a step of sintering the mixture.

According to the present invention, a Bi ingot is pulverized by sequentially using a vibration mill and a ball mill, so that Bi has an average particle diameter in the range of 20 to 50 μm and an oxygen concentration of 1000 massppm or less. It becomes possible to produce a powder.
Since the average particle diameter of Bi powder as a raw material is as small as 20 to 50 μm, it becomes a Bi—Ge target for sputtering with sufficient Ge powder exposed on the sputtering surface, and the distance between Ge phases can be reduced.
Thereby, Ge powder can be sputtered from the initial stage of sputtering, so that it is possible to suppress the sputter film composition from deviating from a desired composition while shortening the idle sputtering time.

  Furthermore, by using Bi powder having an oxygen concentration of 1000 massppm or less, it is possible to obtain a Bi-Ge target for sputtering with improved sinterability and high sintering density.

  In the method for producing a sputtering Bi-Ge target, an inert gas may be enclosed in the ball mill in the step of generating the Bi powder.

  This makes it possible to suppress oxidation of the finely pulverized Bi powder in the step of generating Bi powder, so that Bi powder having an oxygen concentration of 1000 massppm or less can be generated.

  In the method for producing a sputtering Bi-Ge target, in the step of generating the mixture, the Bi powder and the Ge powder may be mixed in an inert gas atmosphere.

  Thereby, since it is possible to suppress oxygen from being taken into the sputtering Bi-Ge target, the oxygen concentration of the sputtering Bi-Ge target can be reduced to 2000 mass ppm or less.

  According to the Bi-Ge target for sputtering of the present invention and the manufacturing method thereof, it is possible to suppress the deviation of the composition of the sputtered film while shortening the idle sputtering time, and to obtain a high sintered density even when the Bi composition is low. it can.

It is a figure (graph) which shows the particle size distribution of Bi powder of comparative example 1, and the measurement result of an average particle diameter. It is a figure (graph) which shows the particle size distribution of Bi powder of Example 1, and the measurement result of an average particle diameter. 4 is an electron micrograph of the surface of a sputtering Bi—Ge target of Comparative Example 1 and Example 1. FIG.

  Hereinafter, an embodiment to which the present invention is applied will be described in detail.

(Embodiment)
<Bi-Ge target for sputtering>
The Bi-Ge target for sputtering according to the embodiment of the present invention constitutes various phase change optical recording disks (hereinafter referred to as “phase change disks”) such as CD-RW, DVD-RW, and DVD-RAM. This is a target for a sputtering apparatus used when forming a Bi-Ge layer disposed between a dielectric layer and a recording layer.

The Bi-Ge target for sputtering according to the present embodiment includes Bi in a range of 20 at% or more and 60 at% or less, and the balance is composed of Ge and inevitable impurities, and is a sintered body of Bi powder and Ge powder. The average value of the distance between Ge phases intervening in the target material is set to 20 μm or more and 200 μm or less.
The “average value of the distance between each other” refers to the average value of the shortest distances between the surfaces of adjacent Ge particles. Further, the viewing area when calculating the average value of the shortest distance, and 6.89Mm ^2, measurement points, the center surface of the target material.

Here, the reason why the average value of the distance between Ge phases intervening in the target material is set in the range of 20 μm or more and 200 μm or less will be described.
In order to make the average value of the distance between Ge phases smaller than 20 μm, it is necessary to use fine Bi powder as a raw material. However, fine Bi powder has a large surface area and is easily oxidized, and the sintering density of the target Will be reduced.

On the other hand, if the average value of the distance between the Ge phases is larger than 200 μm, the composition of the sputtered film deviates from the desired composition immediately after the start of the sputtering process due to the difference between the sputtering rate of Bi and the sputtering rate of Ge. .
Therefore, by setting the average value of the distance between Ge phases intervening in the target material within the range of 20 μm or more and 200 μm or less, immediately after the start of the sputtering process without reducing the sintered density of the Bi-Ge target for sputtering. The composition of the sputtered film can be prevented from deviating from the desired composition.
Moreover, since it becomes possible to suppress the composition of the sputtered film from deviating from a desired composition, the number of abnormal discharges can be suppressed.

Next, the reason why Bi contained in the Bi-Ge target for sputtering is set in the range of 20 at% or more and 60 at% or less will be described.
If Bi contained in the Bi-Ge target for sputtering is lower than 20 at%, it is difficult to ensure good sinterability. On the other hand, if Bi contained in the Bi-Ge target for sputtering is higher than 60 at%, the effect of increasing the speed of the phase change disk becomes insufficient.

  Therefore, by making Bi contained in the Bi-Ge target for sputtering within the range of 20 to 60 at%, it is possible to sufficiently obtain the effect of increasing the speed of the phase change disk and to ensure good sinterability. can do.

The sputtering Bi-Ge target may be configured such that the oxygen concentration, which is an inevitable impurity, is 2000 mass ppm or less, and the sintered density y (%) satisfies the following formula (3).
y ≧ 0.1745 × x + 84.53 (3)
However, in the above formula (3), x is the amount of Bi (at%) contained in the sputtering Bi-Ge target.

  When the oxygen concentration contained in the sputtering Bi-Ge target is larger than 2000 mass ppm, the sintered density is lowered and the film characteristics of the sputtered film are lowered. Therefore, by setting the oxygen concentration contained in the sputtering Bi-Ge target to 2000 mass ppm or less, it is possible to suppress a decrease in the sintered density of the sputtering Bi-Ge target and to suppress deterioration of the film characteristics of the sputtered film. it can.

  The above formula (3) is a formula representing the relationship between the Bi content (at%) and the sintered density. When the Bi content is small, the sintered density tends to decrease. However, the Bi-Ge target for sputtering that satisfies the above equation (3) can suppress abnormal discharge and generation of particles, and stably perform sputtering. Things will be possible.

  A target whose sintering density y satisfies the above formula (3) is 88% or more (when the Bi composition is 20 to 50 at%) even when the Bi composition in the sputtering Bi-Ge target is low (for example, when the Bi composition is 20 to 50 at%). Sintering density y) can be obtained.

Next, the Ge structure constituting the sputtering Bi—Ge target will be described. The average particle diameter of the Ge structure is preferably in the range of 20 to 70 μm, for example.
By setting the average particle diameter of the Ge structure within the range of 20 to 70 μm, it is possible to suppress the composition of the sputtered film from deviating from a desired composition immediately after the start of the sputtering process.

For example, at least one of the Bi powder and the Ge powder constituting the sintered body may be pulverized powder.
Thus, when at least one of Bi powder and Ge powder is a pulverized powder, separation due to a difference in specific gravity between elements during mixing can be suppressed.

  According to the Bi-Ge target for sputtering of the present embodiment, the sputter film composition can be prevented from being shifted after shortening the idle sputtering time, and a high sintered density can be obtained even when the Bi composition is low.

<Manufacturing method of Bi-Ge target for sputtering>
Next, the manufacturing method of the Bi-Ge target for sputtering of this Embodiment is demonstrated.
First, a Ge ingot is introduced into a vibration mill, the Ge ingot is crushed (pulverized), and then classified by a sieve to generate Ge powder.
At this time, a sieve having a mesh size of 90 μm can be used. Moreover, the average particle diameter of Ge powder can be in the range of 20-70 micrometers, for example.

  Next, by sequentially using a vibration mill and a ball mill filled with an inert gas, the Bi ingot is pulverized and then classified by a sieve, so that the average particle diameter is in the range of 20 to 50 μm. Bi powder having an oxygen concentration of 1000 mass ppm or less is generated.

Since a Bi ingot has ductility, only a Bi powder having an average particle size of about 117 μm can be obtained with a vibration mill.
However, Bi powder having an average particle size of 20 to 50 μm can be obtained by grinding using a ball mill after the vibration mill. As a sieve used for classification of Bi powder after pulverization using a ball mill, for example, a sieve having a coarseness of 90 μm can be used.
Moreover, it can suppress oxidizing Bi powder finely grind | pulverized by enclosing an inert gas in a ball mill. Thereby, the oxygen concentration contained in Bi powder can be 1000 massppm or less.
As the inert gas, for example, nitrogen or a rare gas (for example, argon gas) can be used.

As a ball used in the ball mill, for example, a ZrO ₂ ball having a diameter of 5 mm can be used.

Next, a mixture containing 20 to 60 at% Bi powder and Ge powder (remainder) is generated by mixing Bi powder and Ge powder.
At this time, mixing of Bi powder and Ge powder can be performed using a ball mill. In this case, for example, the atmosphere in the ball mill may be an inert gas atmosphere similar to that described above, and Bi powder and Ge powder may be mixed in the inert gas atmosphere.
Thus, by mixing Bi powder and Ge powder in an inert gas atmosphere, it can suppress that the oxygen concentration contained in a mixture becomes high. Specifically, the oxygen concentration contained in the sputtering Bi-Ge target can be reduced to 2000 mass ppm or less.

Next, the mixture is sintered. At this time, for example, sintering is performed using a hot press machine. As sintering conditions, for example, the maximum temperature during sintering is 250 ° C., the heating rate is 600 ° C./hour, the sintering time is 2 hours, the atmosphere in the sintering chamber is an argon atmosphere, and the pressure applied during sintering is 600 kg. A condition of / cm ³ can be used.

Next, the sintered mixture is cooled in a furnace different from the furnace used for sintering. As the cooling temperature at this time, for example, room temperature (for example, 27 ° C.) can be used. The cooling time in this case can be 3 hours, for example.
Thereafter, a Bi-Ge target for sputtering is manufactured by sequentially performing a machining process and a bonding process.

  According to the manufacturing method of the sputtering Bi-Ge target of the present embodiment, the average particle diameter is in the range of 20 to 50 μm by sequentially pulverizing the Bi ingot using a vibration mill and a ball mill. Bi powder having an oxygen concentration of 1000 massppm or less can be produced.

In the Bi-Ge target for sputtering manufactured using such Bi powder, it is possible to expose sufficient Ge powder to the sputtering surface before the sputtering, and to reduce the distance between Ge phases. be able to. In other words, it is possible to reduce the ratio of the surface area of Bi exposed on the sputtering surface.
Thereby, Ge powder can be sputtered from the initial stage of sputtering, so that it is possible to suppress the sputter film composition from deviating from a desired composition while shortening the idle sputtering time.

In addition, by setting the concentration of Bi powder to 20 to 60 at%, it is possible to sufficiently obtain the effect of increasing the speed of the phase change disk and to ensure good sinterability.
Furthermore, by generating Bi powder having an oxygen concentration of 1000 massppm or less, it is possible to suppress a decrease in the sintered density and to suppress deterioration of the properties of the sputtered film.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

  Hereinafter, although a test example, an Example, and a comparative example are demonstrated, this invention is not limited to the following Example.

(Test Example 1)
<Production and Evaluation of Bi Powder of Comparative Example 1 and Example 1>
In Test Example 1, Bi powder pulverized without using a ball mill (hereinafter referred to as “Bi powder C1”) and Bi powder pulverized using a ball mill (hereinafter referred to as “Bi powder D1”). It produced, the particle size of Bi powder C1 and Bi powder D1 was measured, and each average particle size was computed.

Here, a method for producing the Bi powder C1 of Comparative Example 1 will be described.
First, prepare a Bi ingot. Next, the Bi ingot was pulverized using a vibration mill. At this time, one processing time was set to 60 seconds.
Subsequently, Bi powder C1 was produced by classifying the Bi ingot crushed with a vibration mill using a sieve having a coarseness of 250 μm.

Next, a method for producing the Bi powder D1 of Example 1 will be described.
The Bi powder D1 of Example 1 was processed in the same manner as the Bi powder C1 manufacturing method described above, and then the classified Bi powder was further finely pulverized using a ball mill. It produced by classifying using a 90 micrometer sieve.
At this time, as a ball used in the ball mill, a ZrO ₂ ball having a diameter of 5 mm was used.

Subsequently, the particle size distribution of Bi powder C1 and D1 was measured using Microtrac MT3000 which is a particle size distribution measuring instrument manufactured by Nikkiso Co., Ltd., and the average particle size was calculated. The results are shown in FIGS.
FIG. 1 is a diagram (graph) showing the measurement results of the particle size distribution and average particle size of the Bi powder of Comparative Example 1. FIG. 2 is a graph (graph) showing the measurement results of the particle size distribution and average particle size of the Bi powder of Example 1.

Referring to FIGS. 1 and 2, the highest peak of the particle size distribution of Bi powder C1 of Comparative Example 1 is around 110 μm in particle size distribution, whereas the particle size distribution of Bi powder D1 of Example 1 is The peak was found to have a particle size in the vicinity of 50 μm.
The average particle size of the Bi powder C1 of Comparative Example 1 is 117.0 μm, whereas the average particle size of the Bi powder D1 of Example 1 is 35.1 μm, and the Bi powder C1 of Comparative Example 1 The average particle size was about 1/3 of the average particle size.
From this, it was confirmed that Bi powder having a finer particle size can be produced by performing a grinding process with a ball mill after the vibration mill.

<Production and Evaluation of Bi-Ge Target for Sputtering of Comparative Example 1 and Example 1>
Next, using the Bi powder C1 or Bi powder D1 described above and Ge powder (Ge powder E described later) pulverized by a vibration mill, the Bi-Ge target for sputtering of Comparative Example 1 (hereinafter, referred to as “Powder”). a) referred to as "Bi-Ge target _{S 1} for sputtering", sputtering Bi-Ge target (hereinafter example 1, and referred to as _{"T 1} Bi-Ge target for sputtering"), to prepare the surface of each target Observed with an electron microscope.

<Preparation of Bi-Ge Target for Sputtering of Comparative Example 1>
Here, a method for manufacturing the sputtering Bi-Ge target _{S 1} of Comparative Example 1.
First, a Ge powder (hereinafter referred to as “Ge powder E”) was prepared. Specifically, after preparing the Ge ingot, the Ge ingot was pulverized using a vibration mill. At this time, one processing time was set to 60 seconds.
Next, Ge powder E was produced by classifying the Ge ingot pulverized by a vibration mill using a sieve having a coarseness of 90 μm.
Next, the particle size distribution of the Ge powder E was measured by the same method as described above, and the average particle size was calculated. As a result, the average particle diameter of the Ge powder E was 45 μm.

Then, in a ball mill, so that the composition of the sputtering Bi-Ge target _{S 1,} to introduce a Bi powder C1 and Ge powder E, by mixing a Bi powder C1 and Ge powder E, a mixture was prepared .
As a ball used in the ball mill, a ZrO ₂ ball having a diameter of 5 mm was used, and the mixing time was 3 hours.

Subsequently, the said mixture was sintered using the hot press machine.
At this time, the maximum temperature during sintering is 250 ° C., the temperature raising speed is 600 ° C./hour, the sintering time is 2 hours, the atmosphere in the sintering chamber is an argon atmosphere, and the pressure applied during sintering is 600 kg / cm ³ . did.

Thereafter, in a furnace different from the furnace used for sintering, the sintered mixture is cooled, and a machining process and a bonding process are sequentially performed, so that a disk having a diameter of 200 mm and a thickness of 4 mm is obtained. Jo of sputtering Bi-Ge target _S 1 a (Bi35Ge65 (targets that are a composition of at%)) was prepared.
The cooling temperature of the mixture was room temperature (27 ° C.). The cooling time was 3 hours.

<Preparation of Bi-Ge target for sputtering of Example 1>
In Example 1, the Bi powder D1 was used in place of the Bi powder C1, and the sputtering of Comparative Example 1 described above was performed except that the inside of a ball mill in which the Bi powder D1 and the Ge powder E were mixed was put in an argon gas atmosphere. Bi-Ge target T ₁ for sputtering (a target having a composition of Bi35Ge65 (at%)) was produced by the same method as the production method of Bi-Ge target S ₁ for use.

<Surface Observation of Bi-Ge Target for Sputtering of Comparative Example 1 and Example 1 by Electron Microscope and Results>
Then, cut the sample piece from a sputtering Bi-Ge target S ₁ of the surface of Comparative Example 1 were observed using JSM-6460LV scanning electron microscope manufactured by the surface of the sample piece JEOL Ltd.. The electron micrograph at this time is shown in FIG.
Then, cut the sample piece from a sputtering Bi-Ge target _{T 1} of the surface of Example 1, the surface of the sample piece was observed using a JSM-6460LV. The electron micrograph at this time is shown in FIG.

  3 is an electron micrograph of the surface of the sputtering Bi-Ge target of Comparative Example 1 and Example 1. FIG. In the electron micrograph shown in FIG. 3, the portion that appears black is the Ge structure, and the portion that appears white or gray is the portion corresponding to the Bi structure.

As shown in FIG. 3, the metal structure on the surface of the Bi—Ge target T ₁ for sputtering of Example 1 using Bi powder D 1 having a finer average particle diameter than Bi powder C 1 is used for sputtering of Comparative Example 1. it has been found that considerably finer than the metal structure of the Bi-Ge target S ₁ surface.

Incidentally, the same as the sputtering Bi-Ge target _{S 1} of Comparative Example 1 approach, Bi25Ge75 (at%), Bi30Ge70 (at%), Bi45Ge55 (at%), Bi50Ge50 (at%), Bi55Ge45 (at%) When the sputtering Bi-Ge target having the composition of 1 was prepared and the surface thereof was observed, the same result as the photograph shown in FIG. 3 was obtained.

Further, in the same manner as the sputtering Bi-Ge target T ₁ of the first embodiment, where the above-mentioned 5 composition as has been sputtering Bi-Ge target respectively prepared, and observed the surface, shown in FIG. 3 Results similar to those in the photograph were obtained.

(Test Example 2)
<Production and Evaluation of Bi-Ge Target for Sputtering of Example 2>
In Example 2, Bi powder (hereinafter referred to as “Bi powder D2”) was produced by the same method as the Bi powder D1 generation method described above, except that the processing time by the ball mill was increased.
Then, the result measured by the method mentioned above is shown in Table 1.

Then, a Ge powder E as described in Test Example 1, a Bi powder D2, using, by a similar to the method for manufacturing a sputtering Bi-Ge target _{T 1} of the first embodiment described earlier approach, a diameter 200mm , thickness was produced sputtering Bi-Ge target _{T 2} of the second embodiment which is a 4mm disc-shaped.

Then, to determine the sintered density of the sputtering Bi-Ge target _{T 2} of the second embodiment. The sintered density was calculated using the above equation (3). The results are shown in Table 1.
Subsequently, the average value of the distance between Ge phases measured by line analysis (2000 μm width) was obtained. The results are shown in Table 1.

It was then measured concentration of oxygen contained in the sputtering Bi-Ge target T ₂ of the second embodiment. At this time, the center 10 mm square of the target was sampled and measured using EMGA-550, a gas analyzer manufactured by Horiba, Ltd. The results are shown in Table 1.
It was then measured surface roughness Ra of the sputtering Bi-Ge target _{T 2} of the second embodiment. Specifically, using the SURFCOM130A manufactured by Tokyo Seimitsu Kogyo Co., Ltd., the center of the target was measured at one point (scan width 4 mm). The results are shown in Table 1.

Then, a sputtering Bi-Ge target T ₂ of the second embodiment attached to a sputtering apparatus, on a glass substrate 5 inches, were formed sputtered film having a thickness of 500 nm. At this time, the idle sputtering time was set to 100 seconds.
Then, when the composition of the said sputtered film was investigated using VISTA-PRO which is an emission spectroscopic analyzer manufactured by Agilent Technologies, no deviation occurred in the composition of the sputtered film. The results are shown in Table 1.

  In addition, the presence or absence of the composition deviation of the sputtered film was determined based on the following criteria. Specifically, when the deviation from the center of the composition is 5 at% or more, it is determined that there is a deviation in the composition of the sputtered film, and when the deviation from the center of the composition is less than 5 at%, the composition of the sputtered film It was determined that there was no deviation. The results are shown in Table 1.

As an abnormal discharge evaluation method, a sputtering magnet Bi-Ge target T ₂ is attached to a normal magnetron sputtering apparatus, and after the inside of the sputtering chamber is evacuated to a pressure of 1 × 10 ⁻⁴ Pa, the Ar gas pressure is 0.5 Pa, Sputtering was performed under the conditions that the input power was DC 1000 W and the distance between the target and the substrate was 60 mm, thereby measuring the number of abnormal discharges during sputtering.
For the measurement of the number of abnormal discharges, the arc count function of RPDG-50a, a DC power source manufactured by MKS Instruments, was used, and the number of abnormal discharges for 30 minutes from the start of discharge was measured.
The results are shown in Table 1. When the number of abnormal discharges was less than 10, it was determined that there was no abnormal discharge, and when it was 10 times or more, it was determined that there was abnormal discharge.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 3>
In Example 3, a Bi powder (hereinafter referred to as “Bi powder D3”) was prepared by the same method as the Bi powder D1 generation method described above except that the processing time of the ball mill was shortened. The results measured by the method are shown in Table 1.
Then, prepared by the method described above, the Ge powder E as described in Test Example 1, a Bi powder D3, using the sputtering Bi-Ge target T ₃ of Example 3 which is the same composition as in Example 2 Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

<Preparation and evaluation of the sputtering Bi-Ge target _{T 4} of Example 4>
In Example 4, Bi powder (hereinafter referred to as “Bi powder D4”) was prepared by the same method as the Bi powder D1 generation method described above except that the processing time of the ball mill was shortened. The results measured by the method are shown in Table 1.
Then, prepared by the method described above, the Ge powder E as described in Test Example 1, a Bi powder D4, using a sputtering Bi-Ge target T ₄ of Example 4 which is the same composition as in Example 2 Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 5>
In Example 5, the Bi powder D5 of Example 5 was produced in the same manner as the Bi powder D4 of Example 4 except that argon gas was not sealed in the ball mill in the Bi powder generation step, and the above-described process was performed. The results measured by the method are shown in Table 1.
Next, the sputtering Bi-Ge target T _{5 of} Example 5 having the same composition as that of Example 2 using the Ge powder E described in Test Example 1 and the Bi powder D5 by the above-described method, and Sputtered films were prepared and evaluated by the method described above. The results are shown in Table 1.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 6>
In Example 6, except that the processing time of the ball mill was lengthened, Bi powder D6 of Example 6 was produced by the same method as Bi powder D2 of Example 2, and the results measured by the method described above are shown in Table 1. Shown in
Next, the Bi-Ge target T ₆ for sputtering of Example 6 having the same composition as that of Example 2 was prepared by the above-described method using the Ge powder E described in Test Example 1 and the Bi powder D6. Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

<Production and Evaluation of Bi-Ge Target for Sputtering of Example 7>
In Example 7, the Bi powder D7 of Example 7 was produced by the same method as the Bi powder D3 of Example 3 except that argon gas was not enclosed in the ball mill in the Bi powder production step, and was described above. The results measured by the method are shown in Table 1.
Then, prepared by the method described above, the Ge powder E as described in Test Example 1, a Bi powder D7, using a sputtering Bi-Ge target T ₇ of Example 7 which is the same composition as in Example 2 Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

<Production and Evaluation of Bi-Ge Target for Sputtering of Comparative Example 2>
In Comparative Example 2, the Bi powder C2 of Comparative Example 2 was produced by the same method as the Bi powder D2 of Example 2 except that the processing time of the ball mill was shortened, and the results measured by the above-described method are shown in Table 1. Shown in
Next, the sputtering Bi-Ge target S2 of Comparative Example 2 having the same composition as that of Example ₂ was prepared by the above-described method using the Ge powder E described in Test Example 1 and the Bi powder C2. Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

<Production and Evaluation of Bi-Ge Target for Sputtering of Comparative Example 3>
In Comparative Example 3, the Bi powder C3 of Comparative Example 3 was prepared by the same method as the Bi powder D2 of Example 2 except that the powder was pulverized only by the vibration mill without using a ball mill. The measured results are shown in Table 1.
Then, prepared by the method described above, the Ge powder E as described in Test Example 1, and Bi powders C3, using a sputtering Bi-Ge target S ₃ of Comparative Example 3 which is the same composition as in Example 2 Thereafter, a sputtered film was formed. Then, these were evaluated by the method mentioned above. The results are shown in Table 1.

(Test Example 3)
In Test Example 2 described above, sputtering Bi—Ge targets S _{2 to} S ₇ , T ₂ , T ₃ were produced and evaluated. Test Example 3 differs from Test Example 2 in that a Bi-Ge target for sputtering having a Bi60Ge40 (at%) composition having a higher Bi composition than these targets was prepared and evaluated.

<Production and Evaluation of Bi-Ge Target for Sputtering of Example 8>
In Example 8, the Bi powder D2 produced in Example 2 was used. Table 2 shows the average particle diameter of the Bi powder D2, the presence or absence of argon gas sealed in the ball mill, and the oxygen concentration contained in the Bi powder D2.
In Table 2, the Bi powder used in Examples 9 to 13 and the average particle diameter of Bi powder used in Comparative Examples 4 and 5, whether or not argon gas was sealed in the ball mill, included in the Bi powder It also shows the oxygen concentration.

In Example 8, and Ge powder E as described in Test Example 1, a Bi powder D2, using, by a similar to the method for manufacturing a sputtering Bi-Ge target T ₂ of the second embodiment described above technique, to prepare a sputtering Bi-Ge target _{T 8} of example 8, it was then deposited sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 9>
In Example 9, the sputtering method of Example 9 having the same composition as that of Example 8 using the Ge powder E described in Test Example 1 and the Bi powder D3 prepared in Example 3 by the method described above. to prepare a use Bi-Ge target _{T 9,} followed by forming a sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 10>
In Example 10, the sputtering of Example 10 having the same composition as Example 5 using the Ge powder E described in Test Example 1 and the Bi powder D4 prepared in Example 4 by the above-described method. to prepare a use Bi-Ge target _{T 10,} then forming a sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 11>
In Example 11, the sputtering of Example 11 having the same composition as Example 8 using the Ge powder E described in Test Example 1 and the Bi powder D5 prepared in Example 5 by the above-described method. to prepare a use Bi-Ge target _{T 11,} then forming a sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Production and Evaluation of Bi-Ge Target for Sputtering of Example 12>
In Example 12, the sputtering of Example 12 having the same composition as that of Example 8 using the Ge powder E described in Test Example 1 and the Bi powder D6 prepared in Example 6 by the above-described method. to prepare a use Bi-Ge target _{T 12,} then forming a sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Preparation and Evaluation of Bi-Ge Target for Sputtering of Example 13>
In Example 13, the sputtering of Example 13 having the same composition as that of Example 8 using the Ge powder E described in Test Example 1 and the Bi powder D7 prepared in Example 7 by the method described above. to prepare a use Bi-Ge target _{T 13,} then forming a sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Production and Evaluation of Bi-Ge Target for Sputtering of Comparative Example 4>
In the comparative example 4, the sputtering of the comparative example 4 having the same composition as that of the example 8 by using the Ge powder E described in the test example 1 and the Bi powder C2 prepared in the comparative example 2 by the method described above. to prepare a use Bi-Ge target _{S 4,} then deposited sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

<Production and Evaluation of Bi-Ge Target for Sputtering of Comparative Example 5>
In Comparative Example 5, sputtering of Comparative Example 5 having the same composition as Example 8 using the Ge powder E described in Test Example 1 and Bi powder C3 prepared in Comparative Example 3 by the above-described method. to prepare a use Bi-Ge target _{S 5,} then deposited sputtered film. Then, these were evaluated by the method mentioned above. The results are shown in Table 2.

(Regarding the results of Test Examples 2 and 3 shown in Table 1 and Table 2)
Referring to Tables 1 and 2, it was found that the particle size of Bi powder can be pulverized to about 10 μm by performing pulverization using a ball mill after the vibration mill treatment.

From the results of Comparative Examples 2 to 5, it was confirmed that the composition of the sputtered film was shifted when the average value of the distance between Ge phases was in the range of 210 to 380 μm. On the other hand, from the results of Examples 2 to 13, it was confirmed that there was no deviation in the composition of the sputtered film when the average value of the distance between Ge phases was in the range of 65 to 135 μm.
That is, when the average value of the distance between the Ge phases intervening in the target material is 135 μm or less, there is no deviation in the composition of the sputtered film, and when the average value of the distance between the Ge phases is 210 μm or more, the composition of the sputtered film changes. It turns out that there is.

  From the results of Examples 2 to 4 and 8 to 10, it was found that the oxygen concentration contained in the Bi powder increases as the average particle size of the Bi powder as the raw material decreases. This is presumably because the surface area of the Bi powder is increased and the Bi powder is easily oxidized by decreasing the average particle size.

From the results of Examples 4 and 5, it was found that the Bi powder was easily oxidized unless argon gas was enclosed in the ball mill in the Bi powder production process. In the case of Example 4 and Comparative Example 2, it was found that in the Bi powder production process, it was likely to be oxidized about 4 times unless argon gas was enclosed in the ball mill.
In particular, as shown in Examples 7 and 13, when the average particle diameter of the Bi powder is small (in this case, 35 μm), the oxygen concentration contained in the Bi powder is very high unless argon gas is enclosed in the ball mill. I found out that

  It was confirmed that the oxygen concentration contained in the Bi powders used in Examples 2 to 4 and 8 to 10 was 800 mass ppm at the highest, and was suppressed to 1000 mass ppm or less.

Bi-Ge targets T _{2 to} T ₄ for sputtering in Examples 2 to ₄ are targets with a low Bi composition (35 at%), but can realize a sintered density of 90% or more (at least 94.5%). Was confirmed.

In sputtering Bi-Ge target _T 8 _{through T 10} of Examples 8 to 10 in which Bi composition is a 60at%, it was confirmed to be able to realize a sintered density of 95% or more (97.8% at a minimum).
Bi-Ge targets T _{8 to} T ₁₀ for sputtering and Bi-Ge targets T _{11 to} T ₁₃ , S ₄ , and S ₅ for sputtering in Examples 11 to 13 and Comparative Examples 4 and 5 having the same composition of Bi The maximum density was 92.5%.
From the said result, according to the Bi-Ge target for sputtering of an Example, even if Bi composition was low, it has confirmed that a high sintered density could be obtained.

Further, it was confirmed that when the oxygen concentration of the Bi powder as a raw material was high, the oxygen concentration contained in the target was high, and when the oxygen concentration of the Bi powder as a raw material was low, the oxygen concentration contained in the target was low. .
Furthermore, it was confirmed that the surface roughness of the target was reduced when the sintering density of the target was high, and the surface roughness of the target was increased when the sintering density of the target was low.

Claims (6)

Bi is included in the range of 20 at% or more and 60 at% or less, and the balance is composed of Ge and inevitable impurities, and is composed of a sintered body of Bi powder and Ge powder,
A Bi-Ge target for sputtering, wherein the average value of the distance between Ge phases intervening in the target material is 20 µm or more and 200 µm or less. 2. The Bi—Ge target for sputtering according to claim 1, wherein an oxygen concentration as the inevitable impurity is set to 2000 mass ppm or less and a sintering density y satisfies the following expression (1).
y ≧ 0.1745 × x + 84.53 (1)
However, in said Formula (1), x is Bi amount (at%) contained in the said Bi-Ge target for sputtering.   The Bi-Ge target for sputtering according to claim 1 or 2, wherein at least one of the Bi powder and the Ge powder is a pulverized powder. Generating Ge powder by crushing the Ge ingot by a vibration mill;
A step of pulverizing a Bi ingot by sequentially using a vibration mill and a ball mill to produce Bi powder having an average particle diameter in the range of 20 to 50 μm and an oxygen concentration of 1000 massppm or less. ,
Mixing the Bi powder and the remaining Ge powder to produce a mixture containing 20 to 60 at% of the Bi powder;
Sintering the mixture;
The manufacturing method of the Bi-Ge target for sputtering characterized by including this.   5. The method for producing a Bi—Ge target for sputtering according to claim 4, wherein in the step of generating the Bi powder, an inert gas is sealed in the ball mill.   The method for producing a Bi-Ge target for sputtering according to claim 4 or 5, wherein, in the step of generating the mixture, the Bi powder and the Ge powder are mixed in an inert gas atmosphere.