JP2014077187A - Sputtering target for thin film formation and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target with which DC sputtering can be performed and the O amount is stably controlled in depositing a targeted thin film including Bi-Ge-O as main components.SOLUTION: A sputtering target is produced by pressure-sintering mixed powders, which are obtained by blending and mixing oxide powders and Bi metal powders, at a temperature below Bi melting point. In the target, the Bi metal is softened to form base material and oxides are dispersed and distributed.

Description

  The present invention relates to a sputtering target for forming a thin film and a method for manufacturing the same, and more particularly to a sputtering target for forming a thin film mainly composed of Bi-Ge-O suitable for a recording film in an optical disc and a method for manufacturing the same. .

  2. Description of the Related Art Conventionally, optical recording media such as CD, DVD, BD (Blu-ray Disc: registered trademark) have been widely used for viewing digital moving image content and recording digital data. Among these, in BD, the wavelength of the laser beam used for recording and reproduction is shortened to 405 nm, and the numerical aperture of the objective lens is set to 0.85. On the optical recording medium side corresponding to the BD standard, tracks are formed at a pitch of 0.1 to 0.5 μm. In this way, recording / reproduction of 25 GB or more is possible with respect to one information recording layer of the optical recording medium.

  By the way, the capacity of moving images and data is expected to increase further in the future. Therefore, a method for increasing the capacity of the optical recording medium by increasing the number of information recording layers in the optical recording medium has been studied. In the BD standard optical recording medium, a technique for realizing a super-large capacity of 200 GB has been reported.

  There are three types of information storage forms for optical recording media: read-only (ROM) type that cannot add or rewrite data, recordable type that can write data only once, and rewritable type that can rewrite data. Broadly divided. In write-once type optical recording media, organic dyes have been widely used as recording film materials. However, since they are not suitable for blue or blue-violet short-wavelength laser light, Bi and O have recently been used as recording film materials. A method using an inorganic material containing the material has been proposed.

  However, when a blue or blue-violet laser beam is used to increase the recording density, the recording mark becomes extremely small, and therefore, if the recording power fluctuates, there is a problem that the recording accuracy tends to deteriorate due to the influence. It was.

  In particular, when the information recording layer of the optical recording medium is multilayered, the information recording layer should be designed so that preferable light reflection characteristics can be obtained by appropriately adjusting the light reflectance, light absorption rate, and light transmittance of each information recording layer. I must. Along with this, since the optimum recording power of each information recording layer is different, there may occur a situation in which recording and reproduction cannot always be performed with the optimum recording power for all the information recording layers. In particular, when the number of layers is increased, the recording power is usually set to a high value. Therefore, the information recording layer near the light incident surface side has a problem that the recording power is excessive and the recording accuracy is likely to deteriorate. It was.

  Therefore, when an inorganic material containing Bi and O is used as the material of the recording film of the optical recording medium, the allowable amount against the fluctuation of the recording power is small. In particular, when recording / reproducing is performed at a high recording power, noise increases rapidly. There was a problem.

In order to solve this problem, a substrate and an information recording layer formed on the substrate on which information is recorded are provided. The information recording layer changes its optical characteristics by light irradiation, and Bi and O Proposed is an optical recording medium comprising a recording film mainly composed of bismuth and a dielectric film formed in contact with the recording film and composed mainly of SiO ₂ (see, for example, Patent Document 1). .

  Here, the recording film is Bi-MO (where M is Mg, Ca, Y, Dy, Ce, Tb, Ti, Zr, V, Nb, Ta, Mo, W, Mn, Fe, Zn). , Al, In, Si, Ge, Sn, Sb, Li, Na, K, Sr, Ba, Sc, La, Nd, Sm, Gd, Ho, Cr, Co, Ni, Cu, Ga, Pb At least one element) as a main component.

JP 2011-34611 A

Incidentally, a Bi—Ge—O main component recording film in which M in Bi—M—O is Ge is formed on the dielectric film by sputtering. Specifically, a substrate on which a light absorption film and a dielectric film are formed is placed in a chamber in which Bi and Ge targets are disposed, and O ₂ gas is supplied into the chamber. Further, when a sputtering gas such as Ar or Xe is supplied into the chamber and collides with a Bi and Ge target, particles of Bi and Ge are scattered. The scattered Bi particles and Ge particles react with O ₂ in the chamber to be oxidized and deposited on the dielectric film of the substrate. As a result, the recording film is formed with a substantially uniform thickness along the uneven pattern of the track. Here, the ratio of Bi and O in the recording film is adjusted by adjusting the sputtering conditions.

  By the way, as a specific method of forming a thin film by sputtering, there are a direct current (DC) sputtering method and a high frequency (RF) sputtering method. In general, a direct current (DC) cathode has a higher voltage value applied than a radio frequency (RF) cathode, and therefore, a film formation speed is usually doubled. This is because the energy of the particles to be sputtered is high, and the electrode voltage does not reverse like RF. In order for the target material atoms to be sputtered from the target surface, an energy higher than a certain threshold energy is required, and a high voltage value is effective when sputtering a substance that is difficult to be sputtered.

  Further, in the RF in the boundary region of the threshold value to be sputtered, sputtering is performed due to the high voltage even when the spatter distribution is generated. However, if the film formation speed is increased, the film formation time is shortened, and there is a possibility that errors due to control of the film formation time and instability of the discharge state increase. In order to perform sputtering by direct current (DC), the specific resistance of the target is 0.5 Ω · cm or less. If the specific resistance is higher than this, the target surface is charged up, so that stable DC discharge is difficult.

  By the way, in order to form the above-described Bi—Ge—O main recording film by sputtering, it is necessary to prepare a Bi target and a Ge target. Of these, the Ge target has a high specific resistance. doing. Therefore, in order to form this recording film by sputtering, it is necessary to employ radio frequency (RF) sputtering as described above. Therefore, when a recording film containing Bi—Ge—O as a main component is formed by the RF sputtering method, there is a problem that the film forming speed is low, and the cost increases.

Furthermore, as described above, when the Bi—Ge—O main component recording film is formed by sputtering, the Bi target and the Ge target need to be individually disposed in the chamber. Then, to this chamber, supplies O ₂ gas, by supplying a sputtering gas such as Ar or Xe, is scattered particles of Bi and Ge, scattered Bi particles, Ge particles and O in the chamber It reacts and oxidizes, and a Bi—Ge—O main component thin film is deposited on the dielectric film of the substrate. However, in order to deposit a Bi—Ge—O main component thin film having a desired component composition, it is important to adjust the sputtering conditions, but it is necessary to control the ratio of Bi and O in the recording film. There is a problem that it is not easy.

  Therefore, the present invention has been made in view of the above-described problems, and a Bi—Ge—O main component thin film can be formed with a single sputtering target, and a desired Bi—Ge—O main component thin film is formed. However, it is possible to easily adjust the composition ratio of the Bi—Ge—O main component, and to reduce the specific resistance of the sputtering target, thereby enabling DC sputtering to be performed. And its manufacturing method.

  Therefore, the inventors have studied a sputtering target that can form a Bi—Ge—O-based thin film using a single sputtering target and that can be formed by DC sputtering.

First, instead of separately producing a Bi metal sputtering target and a Ge metal sputtering target, it is possible to produce a sputtering target with an alloy of Bi metal and Ge metal, and using this BiGe alloy sputtering target, DC A film can be formed by sputtering. However, when applied to a thin film containing a Bi—Ge—O main component, sputtering is performed in a reactive atmosphere into which O ₂ is introduced, and there is a drawback that it is difficult to control the amount of O in the thin film.

   Moreover, a sputtering get can also be manufactured with the sintered compact of Bi oxide and Ge oxide. In this case, the amount of O in the thin film can be controlled by the amount of O in the sputtering target. However, since both Bi oxide and Ge oxide are electrically insulating and have high specific resistance, this sputtering is effective. DC sputtering cannot be performed with the target. In order to impart conductivity to the sputtering target, other elements exhibiting conductivity must be added, which may affect the film characteristics, and this method is not applicable.

  Therefore, the present inventors have made Bi oxidation in order to produce a sputtering target capable of DC sputtering and capable of stably adjusting the amount of O in the formation of the target Bi—Ge—O main component thin film. Reaction during film formation by adding a material, Ge oxide, or a composite oxide of Bi and Ge in the base material of conductive element Bi in which Ge metal particles are dispersed. Instead of relying on the introduction of O in reactive sputtering, the amount of O during film formation was supplied from Bi oxide, Ge oxide, or a composite oxide of Bi and Ge during sputtering.

  On the other hand, as a method for producing a sputtering target containing a plurality of types of components, a mixture obtained by mixing a plurality of types of components at a predetermined ratio is heat-treated at a temperature lower than the melting point of the lowest melting component among the components. A technique of performing pressure treatment and forming into a target shape is known. In this pressure molding, only the component with the lowest melting point becomes a very active state by heat treatment at a temperature lower than the melting point and plays a role as a binder with other components. Is based on the principle that the binding force with each component is increased. Therefore, the manufactured sputtering target has mechanical strength as a target, and the heat treatment temperature is low, so that the charged composition before the heat treatment is maintained as it is even after the heat treatment, and the film is formed even during the sputtering film formation. In addition, the composition of the thin film is very close to the charged composition.

  Therefore, the present inventors pay attention to the fact that the melting point (271.5 ° C.) of Bi is lower than that of Ge, its oxide, Bi oxide, and the like. In order to lower the temperature, low temperature heating and pressurization, that is, pressurizing at a temperature lower than the melting point of Bi, forming a substrate by a continuous phase of conductive element Bi, and Bi oxidation serving as a supply source of O in the substrate Any one of the above materials, Ge oxide, or a composite oxide of Bi and Ge, and Ge metal particles were dispersed and distributed as necessary. The amount of these components was adjusted so that a desired film characteristic Bi—Ge—O thin film was formed. In this way, it has been found that a conductive Bi—Ge—O sputtering target capable of DC sputtering can be obtained.

Therefore, the inventors, as a first test example, 47.7 mol% of Bi metal powder with a particle size of 250 μm or less, 47.5 mol% of Ge metal powder with a particle size of 90 μm or less, and a particle size of 30 μm or less. 5 mol% of Bi oxide powder (Bi ₂ O ₃ ) was prepared, and these raw material powders were mixed by a dry method in a ball mill apparatus to obtain a mixed powder. This mixed powder was hot pressed at a temperature of 245 ° C. and a pressure of 600 kgf / cm ² to produce a sputtering target. The composition component in the manufactured sputtering target was analyzed. The analysis result is shown in FIG.

The photograph in FIG. 1 is an element distribution image obtained by EPMA (Field Emission Electron Beam Probe) for the manufactured sputtering target. From the three photographs in the figure, each element of Bi, Ge, and O The state of the composition distribution can be observed.
Note that the element distribution image by EPMA is originally a color image, but in the photograph of FIG. 1, it is converted into a black and white image. Therefore, the whiter in the photograph, the higher the concentration of the element. ing. Specifically, in the distribution image related to the Bi element, the Bi element is displayed in a white region and is continuously distributed widely. In the distribution image related to the Ge, the Ge element exists in the form of large and small islands, and the distribution related to O. In the image, it is observed that the O element is present as white spots. From these facts, it is presumed that Ge metal grains and Bi oxide grains exist separately in the Bi base.

From the above, in the manufactured sputtering target, Bi forms a substrate in a fired body made of a Bi—Ge—O ternary element, and Ge metal particles and Bi oxide particles are formed in the substrate. It was confirmed that a dispersed phase was formed. And when the specific resistance of the sintered body was measured, a low value of 1.85 × 10 ⁻³ Ω · cm was obtained. Furthermore, when direct current (DC) sputtering was performed in an Ar + O atmosphere introduced with O using the produced sputtering target, a Bi—Ge—O ternary thin film having desired characteristics could be formed. .

Furthermore, the inventors, as a second test example, 47.7 mol% Bi metal powder having a particle size of 250 μm or less, 47.5 mol% Ge metal powder having a particle size of 90 μm or less, and particle size: 0.5 μm. The following Ge oxide powder (GeO ₂ ) was prepared at 5 mol%. Thereafter, a sputtering target was produced in the same manner as in the above test example. The composition component in the manufactured sputtering target was analyzed. The analysis result is shown in FIG.

  The photograph of FIG. 2 is an element distribution image obtained by EPMA with respect to the manufactured sputtering target, similarly to the photograph of FIG. 1. From the three photographs in the figure, each element of Bi, Ge, and O The state of the composition distribution can be observed. In the photograph of FIG. 2, since it is converted into a black and white image as shown in the photograph of FIG. 1, the whiter in the photograph, the higher the concentration of the element. Specifically, in the distribution image related to the Bi element, the Bi element is displayed in a white region and is continuously distributed widely. In the distribution image related to the Ge, the Ge element exists in the form of large and small islands, and the distribution related to O. In the image, it is observed that the O element is present as white spots. From these facts, it is presumed that Ge metal grains and Ge oxide grains exist separately in the Bi base.

From the above, in the manufactured sputtering target, Bi forms a substrate in a fired body made of a Bi—Ge—O ternary element, and Ge metal particles and Ge oxide particles are formed in the substrate. It was confirmed that a dispersed phase was formed. And when the specific resistance of the sintered body was measured, a low value of 8.14 × 10 ⁻³ Ω · cm was obtained. Furthermore, when direct current (DC) sputtering was performed using the manufactured sputtering target, a Bi—Ge—O ternary thin film having desired characteristics could be formed.

Therefore, the present invention has been obtained from the above findings, and the following configuration has been adopted in order to solve the above problems.
(1) A sputtering target of the present invention is a fired body containing Bi and Ge, with the balance being composed of O and inevitable impurities, containing 1 to 41 at% oxygen, and in a Bi metal substrate In the present invention, it has a structure in which oxides are dispersed and distributed.
(2) The sputtering target of (1) is characterized in that the Bi metal has an area ratio of 10 to 90%.
(3) In the manufacturing method of the sputtering target of this invention, the mixed powder obtained by mix | blending and mixing oxide powder and Bi metal powder is pressure-fired at the temperature below melting | fusing point of Bi, Bi metal is obtained. Softens to form a substrate, and the oxide is dispersed and distributed.
(4) In the production method of (3), the mixed powder is a Ge metal powder: 5 to 70 mol%, a kind selected from Bi oxide powder, Ge oxide powder and Bi and Ge composite oxide powder. The above total: 1 to 30 mol% and Bi metal powder: the balance are blended.
(5) In the production method of (3) or (4), the maximum particle size of the Bi metal powder is 300 μm or less.
(6) In the manufacturing method of (4) or (5), the particle diameter of the Ge metal powder is smaller than the particle diameter of the Bi metal powder.
(7) In the production method of any one of (3) to (6), the mixed powder is subjected to pressure firing in a vacuum or an inert gas at a pressure of 300 to 600 kgf / cm ² .

  Here, when manufacturing this thin film forming sputtering target, the amount of each element of Bi, Ge, and O is determined in consideration of the fact that the component composition of the sputtering target becomes the component composition of the thin film to be formed. It depends on the component composition of the Bi—Ge—O ternary thin film to be obtained and is adjusted so as to obtain desired characteristics. The ratio of Bi: Ge can be adjusted in the range of 1: 9 to 9: 1 (atomic ratio). In the sputtering target of the present invention, O in the Bi—Ge—O thin film is supplied from an oxide (Bi oxide, Ge oxide, or a composite oxide of Bi and Ge), and the conductive Bi element. The oxide was dispersed and distributed in the substrate. Further, Ge metal powder was dispersed and distributed as required.

  Therefore, in the production of the sputtering target of the present invention, it is essential to use Bi metal in order to reduce the specific resistance of the target. Without this Bi metal, the specific resistance of the sputtering target will increase and direct current (DC) sputtering cannot be performed. If the Bi metal amount is 30 mol% or less, the conductivity of the target itself is lowered, and if it exceeds 90 mol%, the film characteristics of the thin film after sputtering film formation are affected, for example, the recording characteristics deteriorate. there's a possibility that. For this reason, it is preferable that the Bi metal amount mix | blended in manufacture of a sputtering target is 30-90 mol%.

  Furthermore, in the production of the sputtering target of the present invention, Ge metal powder or Ge oxide powder is used to supply the Ge component in the Bi—Ge—O ternary thin film, but all Ge components are supplied by Ge oxide. If it tries to do, since the density ratio of the target becomes lower, it is preferable to blend 5 to 70 mol% of Ge metal powder. If the Ge metal powder is less than 5 mol%, the effect of improving the density is small, and if it exceeds 70 mol%, the conductivity deteriorates and DC sputtering cannot be performed. Moreover, it is preferable to make the quantity of an oxide into the range of 1-30 mol% with respect to the whole target. When the amount exceeds 30 mol%, the specific resistance of the target increases. When the amount is less than 1 mol%, the effect of stabilizing the amount of oxygen in the thin film after film formation is diminished.

In pressure baking (for example, hot pressing) in the production of the sputtering target of the present invention, pressure baking is performed at a temperature lower than the melting point of Bi. When pressure baking is performed at a temperature equal to or higher than the melting point of Bi, Bi dissolves, and when pressure baking is performed at 200 ° C. or lower, the target density ratio does not increase. The pressure in the pressurized pressure sintering, if it is less than 300 kgf / cm ^2, the density ratio of the target does not rise, preferably with 300~600kgf / cm ^2.

  By performing pressure firing under such conditions, Ge metal powder and oxide powder are harder than Bi metal and do not melt, so even after pressure firing, the powder shape during mixing is On the other hand, since the Bi metal is pressed at a temperature lower than the melting point of the Bi metal, the Bi metal does not melt, but becomes soft and spreads, so that Ge metal grains, oxide grains, In the meantime, Bi metal is in close contact with and bonded to the respective surfaces of the Ge metal grains and the oxide grains. Therefore, the mechanical strength of the fired body is increased and the density ratio is improved. And since Bi metal forms a substrate, the specific resistance of the fired body can be lowered, and its conductivity can be ensured.

  In addition, Bi metal powder having a maximum particle size of 300 μm or less was used for manufacturing the sputtering target of the present invention. This is because Bi metal powder having a particle size of more than 300 μm is difficult to disperse uniformly, and when the particle size is large, the density of the target decreases, the specific resistance of the target increases, and direct current (DC) This is because it is not suitable for sputtering.

  In the sputtering target of the present invention, Bi metal contributes to conductivity by lowering the specific resistance of the target, but Bi metal is difficult to finely pulverize, so use a large particle size, On the other hand, the oxide powder is as fine as possible. The Ge metal powder also contributes to higher density of the target.

  As described above, according to the present invention, a Bi—Ge—O main component thin film can be formed with a single sputtering target, and the direct current (DC) sputtering can be achieved by reducing the specific resistance of the sputtering target. Therefore, it is suitable for use in forming a recording film containing Bi and O as main components in an optical storage medium, and the film forming cost can be reduced. It has an excellent industrial effect.

It is an element distribution image of each element which measured the structure | tissue of the Bi-Ge-O type | system | group sputtering target by EPMA about the 1st specific example of the sputtering target for thin film formation concerning this invention. It is an element distribution image of each element which measured the structure | tissue of the Bi-Ge-O type | system | group sputtering target by EPMA about the 2nd specific example of the sputtering target for thin film formation concerning this invention.

  Next, the sputtering target for forming a thin film and the method for producing the same according to the present invention will be specifically described below in the first to fourth embodiments. The first embodiment is a case where Bi metal, Ge metal, Bi oxide is used as a raw material powder, and the second embodiment is a case where Bi metal, Ge metal, Ge oxide is used as a raw material powder, The third embodiment is a case where Bi metal, Ge metal, both Bi oxide and Ge oxide are used as raw material powder, or a composite oxide of Bi and Ge is used as raw material powder. In this embodiment, metal Bi, Bi oxide, and Ge oxide are used as the raw material powder.

[First Embodiment]
In the first embodiment, in manufacturing a sputtering target for forming a thin film, Bi metal powder, Ge metal powder, Bi oxide (Bi ₂ O ₃ ) powder is used as a raw material, and the amount thereof is adjusted to be a target. This is a case where a sputtering target capable of stably adjusting the amount of O in forming a Bi—Ge—O main component thin film is obtained. Here, Ge oxide (GeO ₂ ) powder is not used.

(Example)
The production of the sputtering target for forming a thin film according to the first embodiment was performed under the following conditions.
First, a Bi metal powder having a purity of 99.9% and a particle size of 250 μm or less, and a Ge metal having a purity of 99.9% and a particle size of 90 μm or less so as to have the composition shown in Table 1 shown below. Powder, particle size: Bi oxide powder of 30 μm or less was weighed as a raw material powder. This weighed raw material powder was placed in a container together with zirconia balls (diameter: 5 mm) 5 times the weight of the powder, and was mixed in a dry manner in a ball mill apparatus for 3 hours. After the mixing, the mixture was passed through a 1 mm sieve to obtain mixed powder.

As shown in Table 2 below, the obtained mixed powder was subjected to pressure firing at a temperature of 180 to 245 ° C. lower than the melting point temperature of Bi for 1 hour at a pressure of 280 to 600 kgf / cm ² (for example, , Hot pressing) to produce the sputtering targets of Examples 1-13. The maximum particle diameters (μm) of the Bi metal powder, Ge metal powder, and Bi oxide powder used are as shown in Table 1, but in the case of Example 13, the maximum particle diameter of the Bi metal powder. A Bi metal powder having a diameter of 600 μm was used. Further, the maximum particle size of Bi metal powder is larger than the maximum particle size of Ge metal powder.

<Particle size measurement>
Each maximum particle size (μm) of the Bi metal powder, Ge metal powder, and Bi oxide powder used was measured by the microtrack method.

(Comparative example)
In order to compare with the Example of the sputtering target for thin film formation of this invention, as Table 1 showed, the sputtering target of Comparative Examples 1-5 was produced. In producing the sputtering targets of Comparative Examples 1 to 5, the same procedure as in the case of producing the sputtering targets of Examples 1 to 13 was performed. Here, in the production of the sputtering target of the comparative example, powders of Bi metal, Ge metal, Bi oxide, and Ge oxide were used as raw materials, weighed as shown in Table 1, and the mixed powder was pressurized. Baked.

Next, about the sputtering target of Examples 1-13 obtained as mentioned above and the sputtering target of Comparative Examples 1-5, the area ratio of a target composition, Bi metal amount, and Ge metal amount is shown in the following way. It was measured. The results are shown in Table 2.
<Target composition>
Bi and Ge were quantitatively analyzed by ICP analysis, and the balance was oxygen.

<Area ratio measurement>
The area ratio of each metal phase was calculated | required from the component image acquired by EPMA.
In EPMA, the atomic weight of each element appears as light and dark on the image. In this system, metal Bi is bright and metal Ge is represented in dark gray. From this, the area ratio of each metal layer is determined in the component image obtained at a magnification of 40 times by determining the boundary between the metal Bi phase, the metal Ge phase, and the other phase based on the light and dark thresholds, and then on the image. The area was calculated by computer processing for each metal phase within the threshold range and obtained by dividing by the measured area.

  Subsequently, the density ratio and specific resistance of the obtained sputtering targets of Examples 1 to 13 and Comparative Examples 1 to 5 were measured in the following manner. The results are shown in Table 3.

<Density ratio measurement>
The density ratio was calculated by machining the sintered body to a predetermined size, measuring the weight, obtaining the bulk density, and then dividing by the theoretical density ρ _fn . The theoretical density ρ _fn is obtained by the following equation.

<Specific resistance measurement>
The specific resistance of the sputtering target was measured using a resistance measuring instrument Loresta GP manufactured by Mitsubishi Chemical Corporation. In the case where measurement was not possible, “out of measurement range” was displayed.

  Furthermore, using the obtained sputtering targets of Examples 1 to 13 and the sputtering targets of Comparative Examples 1 to 5, a Bi—Ge—O main component thin film was formed on the substrate according to the following DC sputtering conditions. . And the oxygen content of the formed thin film was measured by the following method. The results are shown in Table 3.

<DC sputtering conditions>
DC sputtering was performed under the following conditions.
・ Power supply: Pulse DC500W
・ Total pressure: 0.4Pa
Sputtering gas: Ar = 47.5 sccm, O ₂ : 2.5 sccm
-Target-substrate (TS) distance: 70 mm
<Measurement of oxygen content in film>
The amount of oxygen in the film was formed on a Si substrate and quantitatively analyzed using EPMA.

  According to the above results, even when the film was formed using the sputtering targets of Examples 1 to 13, DC sputtering is possible, and in addition, the target Bi—Ge—O main component thin film is formed. It was confirmed that the amount of O could be adjusted stably. On the other hand, in the case of the sputtering targets of Comparative Examples 1 and 2, since the mixed powder itself showed insulation, DC sputtering could not be performed. The sputtering target of Comparative Example 3 is a case of a conventional sputtering target made of Bi metal powder and Ge metal powder, and the amount of incorporated O is small, and the target Bi—Ge—O main component thin film cannot be obtained. In the case of the sputtering target of Comparative Example 4, the specific resistance was high and DC sputtering could not be performed. In the case of the sputtering target of Comparative Example 5, since the temperature under the hot press conditions was higher than the melting point temperature of Bi, Bi metal was melted and not only caused a composition shift but also damaged the apparatus.

  As described above, in the case of the first embodiment using Bi metal powder, Ge metal powder, and Bi oxide powder as raw materials, a mixed powder is obtained by adjusting the amount thereof, and is fired at a temperature not higher than the Bi melting point. According to the sputtering target, it was confirmed that not only DC sputtering was possible, but also the amount of O in forming the target Bi—Ge—O main component thin film could be adjusted stably.

[Second Embodiment]
In the second embodiment, in the production of a sputtering target for forming a thin film, Bi metal powder, Ge metal powder, and Ge oxide (GeO ₂ ) powder are used as raw materials, and the amounts thereof are adjusted to make the target Bi − This is a case where a sputtering target capable of stably adjusting the amount of O in forming the Ge—O main component thin film is obtained. Here, Bi oxide (Bi ₂ O ₃ ) powder is not used.

(Example)
The production of the sputtering target for forming a thin film according to the second embodiment was performed in the same procedure as in the first embodiment.
First, a Bi metal powder having a purity of 99.9% and a particle size of 250 μm or less, and a Ge metal having a purity of 99.9% and a particle size of 90 μm or less so as to have the composition shown in Table 4 shown below. Powder, particle size: Ge oxide powder of 0.5 μm or less was weighed as a raw material powder. This weighed raw material powder was placed in a container together with zirconia balls (diameter: 5 mm) 5 times the weight of the powder, and was mixed in a dry manner in a ball mill apparatus for 3 hours. After the mixing, the mixture was passed through a 1 mm sieve to obtain mixed powder. The maximum particle diameters (μm) of the Bi metal powder, Ge metal powder, and Ge oxide powder used are as shown in Table 4. Further, the maximum particle size of Bi metal powder is larger than the maximum particle size of Ge metal powder.

As shown in Table 5 below, the obtained mixed powder was pressed and fired at a pressure of 600 kgf / cm ² for 1 hour at a temperature of 215 to 245 ° C. lower than the melting point temperature of Bi (for example, hot The sputtering targets of Examples 14 to 18 were manufactured.

(Comparative example)
For comparison with the sputtering targets of Examples 14 to 18, the sputtering targets of Comparative Examples 1 and 3 described in the case of the first embodiment are shown for reference.

  Next, for the sputtering targets of Examples 14 to 18 obtained as described above, the target composition, the area ratio of the Bi metal amount and the Ge metal amount were measured in the same manner as in the first embodiment. . The results are shown in Table 5.

  Furthermore, the density ratio and specific resistance of the obtained sputtering targets of Examples 14 to 18 were measured in the same manner as in the first embodiment. The results are shown in Table 6.

  Further, using the obtained sputtering targets of Examples 14 to 18, a Bi—Ge—O main component thin film was formed on the substrate according to the DC sputtering conditions shown in the case of the first embodiment. Then, the amount of oxygen in the formed thin film was measured by the method shown in the case of the first embodiment. The results are shown in Table 6.

According to the above results, even when the films were formed using the sputtering targets of Examples 14 to 18, DC sputtering is possible, and the film formation of the target Bi—Ge—O main component thin film is possible. The amount of O could be adjusted stably. On the other hand, in the case of the sputtering target of Comparative Example 1, DC sputtering could not be performed because the mixed powder itself showed insulating properties. Furthermore, in the case of the sputtering target of Comparative Example 3, it is the case of a conventional sputtering target made of Bi metal powder and Ge metal powder, and the target Bi—Ge—O main component thin film has a small amount of O taken in. It was not obtained.
As described above, in the case of the second embodiment using Bi metal powder, Ge metal powder, and Ge oxide powder as raw materials, the amount thereof is adjusted to obtain a mixed powder, which is heated and fired at a temperature below the Bi melting point. According to the sputtering target, it was confirmed that not only DC sputtering was possible, but also the amount of O in forming the target Bi—Ge—O main component thin film could be adjusted stably.

[Third Embodiment]
In the third embodiment, when manufacturing a sputtering target for forming a thin film, all of Bi metal powder, Ge metal powder, Bi oxide (Bi ₂ O ₃ ) powder, and Ge oxide (GeO ₂ ) powder are used as raw materials. This is a case in which a sputtering target capable of stably adjusting the amount of O in forming the target Bi—Ge—O main component thin film is obtained by adjusting the amount of.

(Example)
The production of the sputtering target for forming a thin film according to the third embodiment was performed in the same procedure as in the first embodiment.
First, a Bi metal powder having a purity of 99.9% and a particle size of 250 μm or less, and a Ge metal having a purity of 99.9% and a particle size of 90 μm or less so as to have the composition shown in Table 7 shown below. Powder, Bi oxide powder having a particle size of 30 μm or less, and Ge oxide powder having a particle size of 0.5 μm or less were weighed as raw material powders. This weighed raw material powder was placed in a container together with zirconia balls (diameter: 5 mm) 5 times the weight of the powder, and was mixed in a dry manner in a ball mill apparatus for 3 hours. After the mixing, the mixture was passed through a 1 mm sieve to obtain mixed powder. The maximum particle diameters (μm) of the used Bi metal powder, Ge metal powder, Bi oxide powder, and Ge oxide powder are as shown in Table 7. Further, the maximum particle size of Bi metal powder is larger than the maximum particle size of Ge metal powder.

As shown in Table 5 shown below, the obtained mixed powder was subjected to pressure firing at a temperature of 245 ° C. lower than the melting point temperature of Bi at a pressure of 600 kgf / cm ² for 1 hour (for example, hot press). And the sputtering target of Examples 19-21 was manufactured.

(Comparative example)
In order to compare with the examples of the sputtering target for forming a thin film of the present invention, a sputtering target of Comparative Example 6 was produced as shown in Table 7. The sputtering target of Comparative Example 6 was manufactured in the same procedure as in the case of manufacturing the sputtering target of Examples 19-21. Here, in the production of the sputtering target of the comparative example, powders of Bi metal, Ge metal, Bi oxide, and Ge oxide were used as raw materials, weighed as shown in Table 7, and the mixed powder was pressurized. Baked.
For comparison with the sputtering targets of Examples 19 to 20, the sputtering targets of Comparative Examples 1 and 3 are shown as a reference.

  Next, for the sputtering targets of Examples 19 to 21 and the sputtering target of Comparative Example 6 obtained as described above, the target composition, the area ratio of the Bi metal amount and the Ge metal amount are the same as in the first embodiment. Measured in the same manner as The results are shown in Table 8.

  Further, with respect to the sputtering targets of Examples 19 to 21 and the sputtering target of Comparative Example 6, the density ratio and the specific resistance were measured in the same manner as shown in the case of the first embodiment. The results are shown in Table 9.

  Next, using the sputtering targets of Examples 19 to 21 and the sputtering target of Comparative Example 6, the Bi—Ge—O main component thin film was formed on the substrate according to the DC sputtering conditions shown in the case of the first embodiment. Went. Then, the amount of oxygen in the formed thin film was measured by the method shown in the case of the first embodiment. The results are shown in Table 9.

According to the above results, even when the film was formed using the sputtering targets of Examples 19 to 21, DC sputtering was possible, and in addition, in the formation of the target Bi—Ge—O main component thin film. The amount of O could be adjusted stably. On the other hand, in the case of the sputtering target of Comparative Example 1, DC sputtering could not be performed because the mixed powder itself showed insulating properties. Furthermore, in the case of the sputtering target of Comparative Example 3, it is the case of a conventional sputtering target made of Bi metal powder and Ge metal powder, and the target Bi—Ge—O main component thin film has a small amount of O taken in. It was not obtained. Furthermore, in the case of the sputtering target of Comparative Example 6, the amount of oxide increased, and DC sputtering could not be performed.
As described above, even in the case of the third embodiment using all of Bi metal powder, Ge metal powder, Bi oxide, and Ge oxide powder as raw materials, a mixed powder is obtained by adjusting their amounts, and Bi According to the sputtering target heated and fired at a temperature below the melting point, it is confirmed that not only DC sputtering is possible, but also the amount of O in the formation of the target Bi—Ge—O main component thin film can be adjusted stably. did it.

[Fourth Embodiment]
In the fourth embodiment, in manufacturing a sputtering target for forming a thin film, Bi metal powder, Bi oxide (Bi ₂ O ₃ ) powder, Ge oxide (GeO ₂ ) powder, Bi and Ge composite oxide (Bi) ₄ (GeO) ₃ ) As a raw material, by adjusting the amount thereof, a sputtering target capable of stably adjusting the amount of O in the target Bi—Ge—O main component thin film can be obtained. This is the case. In this case, Ge metal powder is not used.

(Example)
The production of the sputtering target for forming a thin film according to the fourth embodiment was performed in the same procedure as in the first embodiment.
First, Bi metal powder having a purity of 99.9% and a particle size of 250 μm or less, a Bi oxide powder having a particle size of 30 μm or less, and a particle size of 0 so that the composition shown in Table 10 shown below is obtained. A Ge oxide powder of 0.5 μm or less and a composite oxide powder of Bi and Ge having a particle size of 10 μm or less were weighed as raw material powders. This weighed raw material powder was placed in a container together with zirconia balls (diameter: 5 mm) 5 times the weight of the powder, and was mixed in a dry manner in a ball mill apparatus for 3 hours. After the mixing, the mixture was passed through a 1 mm sieve to obtain mixed powder. The maximum particle sizes (μm) of the used Bi metal powder, Bi oxide powder, Ge oxide powder, and complex oxide powder of Bi and Ge are as shown in Table 10. Further, the maximum particle size of Bi metal powder is larger than the maximum particle size of Ge metal powder.

As shown in Table 10 shown below, the obtained mixed powder was subjected to pressure firing at a temperature of 245 ° C. lower than the melting point temperature of Bi for 1 hour at a pressure of 600 kgf / cm ² (for example, hot press). And the sputtering target of Examples 22-26 was manufactured.

(Comparative example)
In order to compare with the Example of the sputtering target for thin film formation of this invention, as Table 10 shows, the sputtering target of Comparative Examples 7-9 was produced. The sputtering target of Comparative Example 6 was manufactured in the same procedure as in the case of manufacturing the sputtering target of Examples 22 to 26. Here, in the production of the sputtering targets of Comparative Examples 7 to 9, powders of Bi metal, Bi oxide, and Ge oxide were used as raw materials, weighed as shown in Table 10, and the mixed powder was pressurized. Baked.
For comparison with the sputtering targets of Examples 22 to 26, the sputtering targets of Comparative Examples 1 and 3 are shown as a reference.

  Next, with respect to the sputtering targets of Examples 22 to 26 and the sputtering targets of Comparative Examples 7 to 9 obtained as described above, the target composition, the area ratio of the Bi metal amount and the Ge metal amount are set in the first embodiment. The measurement was performed in the same manner as shown in the above case. The results are shown in Table 11.

  Furthermore, with respect to the sputtering targets of Examples 22 to 26 and the sputtering targets of Comparative Examples 7 to 9, the density ratio and specific resistance were measured in the same manner as shown in the case of the first embodiment. The results are shown in Table 12.

  Next, using the sputtering targets of Examples 22 to 26 and the sputtering targets of Comparative Examples 7 to 9, the Bi—Ge—O main component thin film was formed on the substrate according to the DC sputtering conditions shown in the case of the first embodiment. Film formation was performed. Then, the oxygen amount of the formed thin film was measured by the same method as shown in the case of the first embodiment. The results are shown in Table 12.

According to the above results, even when the films were formed using the sputtering targets of Examples 21 to 26, DC sputtering is possible, and in addition, in the formation of the target Bi—Ge—O main component thin film. The amount of O could be adjusted stably. On the other hand, in the case of the sputtering target of Comparative Examples 1 and 3, it was as described above, and in the case of the sputtering target of Comparative Examples 7 and 8, the amount of oxide increased and DC sputtering could not be performed. Further, in the case of the sputtering target of Comparative Example 9, since the Bi metal powder is large and the oxide is small, the amount of O taken into the film is small, and the target Bi—Ge—O main component thin film cannot be obtained. It was.
As described above, even in the fourth embodiment using Bi metal powder, Bi oxide, Ge oxide powder, and Bi and Ge composite oxide powder as raw materials, the amount of the selected powder is adjusted. According to the sputtering target obtained by obtaining the mixed powder and heated and fired at a temperature equal to or lower than the Bi melting point, not only DC sputtering is possible, but also the amount of O in the formation of the target Bi—Ge—O main component thin film is reduced. It was confirmed that stable adjustment was possible.

The technical scope of the present invention is not limited to the above-described embodiment and examples, and various modifications can be made without departing from the spirit of the present invention.

Claims (7)

A fired body containing Bi and Ge, with the balance being composed of O and inevitable impurities,
Contains 1-41 at% oxygen,
A sputtering target characterized by having a structure in which oxide is dispersed and distributed in a Bi metal substrate.   The sputtering target according to claim 1, wherein the Bi metal has an area ratio of 10 to 90%.   The mixed powder obtained by mixing and mixing the oxide powder and the Bi metal powder is pressurized and fired at a temperature lower than the melting point of Bi, and the Bi metal is softened to form a substrate, and the oxide is dispersed. A method for producing a sputtering target, characterized by being distributed.   The mixed powder is Ge metal powder: 5 to 70 mol%, and a total of one or more selected from Bi oxide powder, Ge oxide powder, and Bi and Ge composite oxide powder: 1 to 30 mol% Bi metal powder: remainder is mix | blended, The manufacturing method of the sputtering target of Claim 3 characterized by the above-mentioned.   The method for manufacturing a sputtering target according to claim 3 or 4, wherein the maximum particle size of the Bi metal powder is 300 µm or less.   6. The method of manufacturing a sputtering target according to claim 4, wherein a particle diameter of the Ge metal powder is smaller than a particle diameter of the Bi metal powder. The method for producing a sputtering target according to any one of claims 3 to 6, wherein the mixed powder is subjected to pressure firing in a vacuum or an inert gas at a pressure of 280 to 600 kgf / cm ² .