JP6557750B1 - Sputtering target material and sputtering target - Google Patents

Abstract

The present invention provides a sputtering target material and a sputtering target that can effectively suppress abnormal discharge when forming a dielectric layer of an optical recording medium and do not require measures for preventing health hazards. Objective. One embodiment of the present invention includes zinc (Zn) oxide, tin (Sn) oxide, and zirconium (Zr) oxide, with respect to all elements other than oxygen (O). Content AZn is more than 0 at% and not more than 50 at%, tin content ASn is not less than 20 at% and not more than 80 at%, zirconium content AZr is more than 0 at% and not more than 40 at%, and the Zn content is represented by the following formula (1 Among the plurality of measured resistivity values, the ratio of the maximum value to the minimum value is 3 or less, and the resistivity value is 5 × 10 -1 [Ω · cm] or less, and indium (In) It is a sputtering target material that does not contain. AZn / (AZn + ASn) ≦ 0.6 (1) [Selection] None

Description

  The present invention relates to a sputtering target material and a sputtering target.

  Optical recording media are typified by optical disks such as CD and DVD, and are classified into three types: read-only, write once, and rewritable. Further, as a recording method of the optical recording medium, a method in which the constituent material of the recording layer changes phase, a method in which the multilayered recording layers react with each other, a method in which the constituent material of the recording layer is decomposed, etc. . As a recording layer material for a write once optical disc, an organic dye material has been widely used so far. However, in recent years, recording density has been increased and an inorganic material has also been used.

When a metal oxide is used as the inorganic material for the recording layer, information is recorded by decomposing the oxide.In order to suppress deterioration due to aging of the recording layer and improve the signal characteristics of the recording layer, It is known to form a dielectric layer on the front and back of the recording layer by sputtering. A sputtering target for forming a dielectric layer (protective layer), in which 90% or more of contained zirconium (Zr) is dispersed in a sputtering target material as a composite oxide phase of Zr and indium (In). Thus, a ZrO ₂ —In ₂ O ₃ -based sputtering target having excellent crack resistance has been proposed (Japanese Patent Laid-Open No. 2009-62585). According to this sputtering target, cracking does not occur even when sputtering is performed at a high output, so that a dielectric layer is formed efficiently and the production efficiency of the optical recording medium is improved.

However, when sputtering is performed at a high output, abnormal discharge occurs, and so-called particles are generated in which the base of the sputtering target becomes a granular lump and scatters in the recording layer. In the ZrO ₂ —In ₂ O ₃ -based sputtering target, The abnormal discharge may not be effectively suppressed. Moreover, since the conductivity of the sputtering target is ensured by the oxide containing In, it is possible to increase the formation speed and shorten the process work time. However, since In is designated as a specific chemical substance, it is a health hazard. It is necessary to take preventive measures.

JP 2009-62585 A

  The present invention has been made based on the above situation, and can effectively suppress abnormal discharge when forming a dielectric layer of an optical recording medium, and there is no need for measures for preventing health problems. It is an object to provide a sputtering target material and a sputtering target.

One embodiment of the present invention made to solve the above problems includes an oxide of zinc (Zn), an oxide of tin (Sn), and an oxide of zirconium (Zr), and all elements other than oxygen (O) In contrast, the zinc content A _Zn is more than 0 at% and not more than 50 at%, the tin content A _Sn is not less than 20 at% and not more than 80 at%, and the zirconium content A _Zr is more than 0 at% and not more than 40 at%, Zn The specific resistance satisfies the following formula (1), and among the measured specific resistance values, the ratio of the maximum value to the minimum value is 3 or less, and the specific resistance value is 5 × 10 ⁻¹ [Ω · cm]. The sputtering target material does not contain indium (In).
A _Zn / (A _Zn + A _Sn ) ≦ 0.6 (1)

The sputtering target material is formed of a Zn oxide, a Sn oxide, and a Zr oxide, and the content is in the above range. Therefore, a sputtering target for forming a dielectric layer having excellent characteristics is manufactured. Can do. Further, since the ratio of the maximum value to the minimum value of the plurality of specific resistance values to be measured is 3 or less and the specific resistance value is 5 × 10 ⁻¹ [Ω · cm] or less, the dielectric layer is formed by sputtering. In this case, abnormal discharge is effectively suppressed, and the generation of particles can be reduced. Moreover, since the said sputtering target material does not contain In element, there is no need for a health disorder prevention measure. Accordingly, the production efficiency of the optical recording medium can be improved.

The sputtering target material has a SnO ₂ phase and a Zn ₂ SnO ₄ phase, and the ratio of the Zr element concentration in the Zn ₂ SnO ₄ phase to the Zr element concentration in the SnO ₂ phase is 0.3 or more and 5 or less. It is good to be. By doing in this way, the sputtering target excellent in intensity | strength can be manufactured.

The sputtering target material comprises crystal grains of ZrO _2, the average particle diameter of the crystal grains of the ZrO ₂ may If it is 5μm or less. By doing in this way, the sputtering target whose strength was more excellent can be manufactured.

  Another embodiment of the present invention made to solve the above problems is a sputtering target including the above sputtering target material. Since the sputtering target can effectively suppress abnormal discharge when the dielectric layer is formed by a sputtering method, the dielectric layer can be formed efficiently.

  As described above, the sputtering target material and the sputtering target of the present invention can effectively suppress abnormal discharge when forming the dielectric layer of the optical recording medium, and there is no need for measures for preventing health problems.

  Hereinafter, embodiments of the sputtering target material and the sputtering target according to the present invention will be described in detail.

[Sputtering target]
A sputtering target according to an embodiment of the present invention is used to form a dielectric layer on the front and back of a recording layer of an optical recording medium. The sputtering target includes an oxide of zinc (Zn), an oxide of tin (Sn), and an oxide of zirconium (Zr), and the zinc content A _Zn is present with respect to all elements other than oxygen (O). More than 0 at% and not more than 50 at%, tin content A _Sn is not less than 20 at% and not more than 80 at%, zirconium content A _Zr is more than 0 at% and not more than 40 at%, and the Zn content satisfies the following formula (1) Among the plurality of measured resistivity values, the ratio of the maximum value to the minimum value is 3 or less, and the resistivity value is 5 × 10 ⁻¹ [Ω · cm] or less and does not contain indium (In). Manufactured with sputtering target material. The sputtering target material is another embodiment of the present invention.
A _Zn / (A _Zn + A _Sn ) ≦ 0.6 (1)

<Sputtering target material>
The sputtering target material includes oxides of Zn, Sn, and Zr. When the sputtering target material includes oxides of Zn, Sn, and Zr, the same oxide can be included in the dielectric layer. The dielectric layer has a function of preventing oxygen released when the oxide of the recording layer is decomposed from the recording layer, a function of maintaining the durability of the recording layer, and a function of adjusting the amount of transmitted light. Have

  Zn is an element for reducing jitter by suppressing variations in the shape or size of recording marks formed in the recording layer by being added to the dielectric layer simultaneously with Sn.

  Sn is an element for providing the dielectric layer with an oxygen barrier function for preventing the recording layer from being decomposed.

  Zr is an element for improving the oxygen barrier function of the dielectric layer and suppressing the deterioration of the recording signal of the recording layer.

The lower limit of the content A _Zn for all elements other than oxygen of Zn in the sputtering target material is more than 0 at%, preferably 20 at%, more preferably 30 at%. On the other hand, the upper limit of the Zn content is 50 at%, preferably 47 at%, and more preferably 45 at%. When the Zn content of the sputtering target material is less than the above lower limit, the dielectric layer lacks Zn oxide and sufficiently suppresses variations in the shape or size of the recording mark formed on the recording layer. There is a risk that it will not be possible. On the other hand, when the Zn content exceeds the above upper limit, the oxide content of other elements may be insufficient.

The lower limit of the content A _Sn with respect to all elements other than oxygen of Sn in the sputtering target material is 20 at%, preferably 30 at%, and more preferably 40 at%. On the other hand, the upper limit of the Sn content is 80 at%, preferably 75 at%, and more preferably 70 at%. If the content of Sn in the sputtering target material is less than the lower limit, the dielectric layer may be deficient in Sn oxide, making it difficult to provide the dielectric layer with an oxygen barrier function that prevents decomposition of the recording layer. There is. On the other hand, when the content of Sn exceeds the above upper limit, the content of oxides of other elements may be insufficient.

The lower limit of the content A _Zr with respect to all elements other than oxygen of Zr in the sputtering target material is more than 0 at%, preferably 5 at%, and more preferably 10 at%. On the other hand, the upper limit of the Zr content is 40 at%, preferably 35 at%, and more preferably 30 at%. When the Zr content of the sputtering target material is less than the lower limit, the dielectric layer lacks Zr oxide, the oxygen barrier function is lowered, and it is difficult to suppress the deterioration of the recording signal of the recording layer. There is a fear. On the other hand, when the content of Zr exceeds the above upper limit, the content of oxides of other elements may be insufficient.

The Zn content satisfies the following formula (1). The lower limit of the value of the following formula (1) is 0, more preferably 0.1, and still more preferably 0.2. On the other hand, as an upper limit of the value of following formula (1), 0.5 is preferable and 0.4 is more preferable. When the value of the following formula (1) exceeds the upper limit, Zn oxide in the dielectric layer increases unnecessarily, and the oxygen barrier function of the dielectric layer may decrease.
A _Zn / (A _Zn + A _Sn ) ≦ 0.6 (1)

  The sputtering target material does not contain In. Specifically, the In content is less than the detection limit of 100 ppm. Since the sputtering target material does not contain the In element designated as the specific chemical substance, there is no need for measures for preventing health problems.

  Of the plurality of specific resistance values measured with the sputtering target material, the upper limit of the ratio of the maximum value to the minimum value is 3, more preferably 2.4, and even more preferably 1.7. When the ratio of the maximum value to the minimum value of the specific resistance exceeds the upper limit, abnormal discharge may not be sufficiently suppressed when forming a dielectric layer with a sputtering target using the sputtering target material. .

The upper limit of the specific resistance value of the sputtering target material is 5 × 10 ⁻¹ [Ω · cm], preferably 3 × 10 ⁻¹ [Ω · cm], and 1 × 10 ⁻¹ [Ω · cm]. Further preferred. When the specific resistance value exceeds the upper limit, abnormal discharge may not be sufficiently suppressed when a dielectric layer is formed with a sputtering target using the sputtering target material.

The sputtering target material has a SnO ₂ phase and a Zn ₂ SnO ₄ phase. The lower limit of the ratio of the Zr element concentration in the Zn ₂ SnO ₄ phase to the Zr element concentration in the SnO ₂ phase is preferably 0.1, more preferably 0.15, and even more preferably 0.2. On the other hand, the upper limit of the ratio of the Zr element concentration is preferably 5, more preferably 4, and even more preferably 3. When the ratio of the Zr element concentration is not in the above lower limit and upper limit range, a large amount of ZrO ₂ that is an insulator remains, and there is a possibility that abnormal discharge starting from ZrO ₂ may occur.

Further, the sputtering target material has ZrO ₂ crystal grains. The upper limit of the average grain size of the ZrO ₂ crystal grains is preferably 5 μm, more preferably 4 μm, and even more preferably 3 μm. When the average grain size of ZrO ₂ exceeds the upper limit, abnormal discharge starting from ZrO ₂ that is an insulator may occur.

[Method of manufacturing sputtering target]
The sputtering target can be obtained by molding and processing a sputtering target material that is an oxide sintered body obtained by mixing and sintering Zn, Sn, and Zr oxides. The manufacturing method of the sputtering target demonstrated below shows the example, and is not limited to the said manufacturing method.

  Specifically, the manufacturing method of the sputtering target includes a step of mixing Zn, Sn, and Zr (S01), a step of drying the mixture (S02), and sintering the dried mixture to obtain an oxide sintered body. A step (S03), a step of forming the oxide sintered body (S04), and a step of bonding the molded product to the backing plate (S05).

<Mixing process>
In the step of mixing Zn, Sn, and Zr (S01), powdery Zn, Sn, and Zr are mixed at a predetermined ratio and mixed. The purity of each raw material powder used is preferably 99.99% or more. If the purity of each raw material powder is less than the lower limit, the characteristics of the dielectric layer formed using the sputtering target may be impaired. The blending ratio of each raw material powder is such that Zn is greater than 0 at% and less than 50 at%, Sn is greater than or equal to 20 at% and less than or equal to 80 at%, and Zr is greater than 0 at% and 40 at with respect to all metal elements excluding oxygen contained in the oxide sintered body. %, And the ratio of the Zn content to the sum of the Zn and Sn contents is adjusted to 0.6 or less.

  The means for mixing is not particularly limited, and for example, using a ball mill, each raw material powder and water can be added to the ball mill and mixed. A dispersant may be used for the purpose of uniformly mixing with water, or a binder may be used for facilitating molding in the preforming step described later. The material of the ball or ball of the ball mill is not particularly limited, and examples thereof include nylon, alumina, zirconia and the like.

<Drying process>
In the drying step (S02), the mixture obtained in the mixing step is dried using, for example, a spray dryer. It is preferred to preform the mixture after drying. Moreover, when a dispersing agent and a binder are used, it is preferable to degrease the mixture.

(Preliminary molding process)
In order to improve the handling property when the dried mixture is set in a sintering furnace, it is preferable to perform preforming. Although it does not specifically limit as a method of a preforming, Filling the mixture after drying to the metal mold | die of a predetermined dimension, and pre-molding with a metal mold press is mentioned. The applied pressure in the die press can be, for example, 0.5 tof / cm ² or more and 1.0 tof / cm ² or less.

(Degreasing process)
When a dispersing agent or binder is added in the mixing step (S01), it is preferable to degrease by heating the dried mixture or preform in order to remove the dispersing agent or binder. The heating conditions are not particularly limited. For example, in the air, the dispersant and the binder can be removed by setting the heating temperature to 500 ° C. and the holding time to 5 hours.

<Sintering process>
In the sintering step (S03), the dried mixture is sintered to form an oxide sintered body. This oxide sintered body is the sputtering target material. Moreover, by the sintering, an SnO ₂ phase and a Zn ₂ SnO ₄ phase are formed on the sputtering target material, and ZrO ₂ crystal grains are formed. As a minimum of heating temperature of sintering, 900 ° C is preferred, 920 ° C is more preferred, and 940 ° C is still more preferred. On the other hand, as an upper limit of heating temperature, 1100 degreeC is preferable and 1050 degreeC is more preferable. When heating temperature is less than the said minimum, oxide sintered compact cannot fully be densified and there exists a possibility that material strength may fall. On the other hand, when the heating temperature exceeds the above upper limit, the crystal grains are coarsened, which may reduce the material strength.

  As an upper limit of the average temperature increase rate up to the heating temperature, 600 ° C./hr is preferable, 500 ° C./hr is more preferable, and 400 ° C./hr is more preferable. When the average heating rate exceeds the above upper limit, abnormal growth of crystal grains is likely to occur, and the relative density of the oxide sintered body may not be sufficiently increased.

  The lower limit of the heating temperature holding time is preferably 0.5 hours, more preferably 2 hours, and even more preferably 3.5 hours. On the other hand, the upper limit of the holding time is preferably 24 hours, more preferably 12 hours, and even more preferably 8 hours. By setting the retention time within the above range, a desired compound phase can be obtained.

  After the heating, it is preferable to further heat under conditions where the heating temperature is 400 ° C. or higher and 700 ° C. or lower and the holding time is 1 hour or longer and 10 hours or shorter. By doing in this way, the relative density of oxide sinter can be raised more.

  The sintering is preferably performed in a reducing atmosphere. By performing the sintering in a reducing atmosphere such as a carbon monoxide (CO) atmosphere or a vacuum atmosphere, the specific resistance can be reduced. Although there is an unclear part about the detailed mechanism, it is considered that the carrier is increased and the conductivity is improved by processing in a reducing atmosphere in which oxygen deficiency occurs.

  Alternatively, in the mixing step (S01), carbon (C) may be added to the material powder and water, the mixture may be dried (S02), and the dried mixture may be sintered. The presence of C in the dried mixture causes a reduction reaction by heating, and the same effect as that obtained by sintering in a reducing atmosphere can be obtained.

<Molding process>
In the forming step (S04), the oxide sintered body (sputtering target material) is formed into a shape corresponding to various uses. The means for molding is not particularly limited, and for example, a cold isostatic pressing method (CIP: Cold Isostatic Pressing) can be employed. The lower limit of the pressure in the CIP, preferably 1000 kgf / cm ^2, more preferably 900 kgf / cm ^2, further preferably 800 kgf / cm ^2. When the applied pressure at CIP is less than the lower limit, the relative density of the oxide sintered body may not be sufficiently improved.

<Joint process>
In the joining step (S05), the molded product is joined to a backing plate to obtain a sputtering target. Although it does not specifically limit as a raw material of a backing plate, The pure copper or copper alloy excellent in heat conductivity is preferable. The means for joining is not particularly limited, but it can be joined by, for example, a bonding agent. Although it does not specifically limit as a kind of bonding agent, Various well-known bonding agents which have electroconductivity can be employ | adopted, for example, Sn type solder material is mentioned. The bonding method is not particularly limited. For example, the molding and the backing plate are heated to a temperature at which the bonding agent dissolves, for example, 140 ° C. or higher and 240 ° C. or lower, and the dissolved bonding agent is applied to the bonding surface of the backing plate. After the bonded surfaces of the objects are bonded and pressure-bonded, cooling can be performed.

[advantage]
Since the sputtering target material and the sputtering target contain respective oxides of Zn, Sn, and Zr and the content of these elements is within a predetermined range, a dielectric layer having excellent characteristics can be formed. . Further, since the ratio of the maximum value to the minimum value of the specific resistance value and the specific resistance value are in a predetermined range, abnormal discharge during sputtering can be suppressed, and generation of particles can be reduced. Furthermore, since it does not contain In, there is no need for measures to prevent health problems. Therefore, an optical recording medium can be produced safely and efficiently by using the sputtering target material and the sputtering target.

According to the manufacturing method of the sputtering target, a sputtering target having excellent strength can be obtained. Therefore, it is possible to suppress cracks due to stress generated by impact during operation in the joining process or thermal history during sputtering. In addition, according to the sputtering target manufacturing method, the specific resistance, the ratio of the Zr element concentration in the Zn ₂ SnO ₄ phase to the Zr element concentration in the SnO ₂ phase, and the average grain size of the ZrO ₂ crystal grains are desired. The value can be easily set. Therefore, a sputtering target capable of safely and efficiently forming a dielectric layer can be manufactured relatively easily.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

Using Samples 1 to 3 in which the blending conditions of Zn, Sn, and Zr were Table 1, moldings of Examples 1 to 4 and Comparative Examples 1 to 3 were obtained under the manufacturing conditions of Table 2. The thickness of the molded product was 6 mm. In the mixing step, water and ammonium polycarboxylate were mixed in each of samples 1 to 3. In the sintering process, hot pressing was performed in a reducing atmosphere. In Table 2, “N ₂ ” represents nitrogen.

<Phase identification>
The identification of the phases of Examples 1 to 4 and Comparative Examples 1 to 3 was measured under the following conditions by X-ray diffraction. In addition, the notation method is based on the chemical formula of the card number of ICDD (International Center for Diffraction Data).
74-2184: Zn ₂ SnO ₄
77-0447: SnO ₂
74-1200: ZrO ₂
86-2265: Sn
750576: ZnO
Analysis conditions:
Target: Cu
Monochromatic: Uses a monochrome mate (K _α )
Target output: 40kV-200mA
(Continuous firing measurement) θ / 2θ scanning Slit: Divergence angle: 1/2 °, Scattering angle: 1/2 °, Light receiving width: 0.15 mm
Monochromator light receiving slit width: 0.6mm
Scanning speed: 2 ° / min
Sampling interval: 0.02 °
Measurement angle (2θ): 5 to 90 °
Analysis device: “X-ray diffractometer RINT-1500” manufactured by Rigaku Corporation

<Evaluation of Zr amount and average particle size>
Evaluation of the Zr amount in the molded product and measurement of the average grain size of the crystal grains of ZrO ₂ were performed according to the following procedure.
(1) The molded product was cut in the thickness direction at an arbitrary position, and the arbitrary position of the cut surface was mirror-ground.
(2) The structure of the mirror-ground cut surface was photographed at a magnification of 10,000 using a scanning electron microscope (SEM), and the phase was identified using energy dispersive X-ray spectroscopy (EDS). The amount of Zr solid solution detected in SEM and EDS was taken as the amount of Zr. It was also measured average grain size of the crystal grains of ZrO _2, which is detected in the SEM and EDS.
(3) The ratio of the Zr amount of the SnO ₂ phase and the Zn ₂ SnO ₄ phase was calculated.
Analysis equipment:
SEM: “JSM-7800F” manufactured by JEOL Ltd.
EDS: “JED-2300” manufactured by JEOL Ltd.

<Measurement method of specific resistance>
The specific resistance was measured by a 4-probe method. Specifically, the surface of the molded product was smoothed by mirror grinding. Measurement was performed by contacting a probe having a distance between terminals of 1.5 mm at intervals of 10 mm from the center of the molded product. The specific resistance value was an average value of the values measured at 10 points, and the ratio of the maximum value to the minimum value of the specific resistance values measured at 10 points was calculated.
Measuring device: “Loresta GP measuring instrument” manufactured by Mitsubishi Chemical Analytech

<Relative density>
The relative density was determined from the porosity measured as follows. First, the molded product was cut in the thickness direction at an arbitrary position, and an arbitrary position of the cut surface was mirror-ground. Next, a photograph was taken at a magnification of 1000 using an SEM, and the area ratio (%) of the pores in a 50 μm square region was measured to obtain the porosity. The same operation was performed at 20 locations, and the average was defined as the average porosity (%) of the sample. The relative density was calculated by [100-average porosity] (%).

<Existence of abnormal discharge>
The presence or absence of abnormal discharge was confirmed as follows. The molded products of Examples 1 to 4 and Comparative Examples 1 to 3 were used as sputtering targets. Using this sputtering target, a dielectric layer was formed on the recording layer by sputtering under the conditions of DC sputtering power 200 W, Ar / 0.1 volume% O ₂ atmosphere, and pressure 0.3 Pa, and abnormal discharge during formation For 100 min. The number of occurrences of arcing per hit was counted and confirmed.

Table 3 shows the measurement results. In Table 3, “specific resistance variation” indicates the ratio of the maximum value to the minimum value of the specific resistance. The “Zr amount ratio” indicates the ratio of the Zr amount in the Zn ₂ SnO ₄ phase to the Zr element concentration in the SnO ₂ phase. “-” Indicates that data is not acquired.

In Comparative Example 1, since the reduction of the oxide is difficult to occur, the specific resistance is increased, and abnormal discharge occurs. In Comparative Example 2, since the Sn content was more than 80 at% and the Zr content was 0 at%, the specific resistance increased and abnormal discharge occurred. In Comparative Example 3, the reduction during sintering was unstable in an N ₂ atmosphere and the influence of the outermost peripheral portion was exerted, so that the variation in specific resistance increased and abnormal discharge occurred.

  The sputtering target material and the sputtering target of the present invention do not require measures for preventing health hazards and can suppress abnormal discharge, and therefore can be suitably used for production of optical recording media.

Claims (4)

Including an oxide of zinc (Zn), an oxide of tin (Sn) and an oxide of zirconium (Zr),
For all elements except oxygen (O),
Zinc content A _Zn is more than 0 at% and 50 at% or less,
The tin content A _Sn is 20 at% or more and 80 at% or less, and the zirconium content A _Zr is 10 at% or more and 40 at% or less,
Zn content satisfies the following formula (1),
Among the measured specific resistance values, the ratio of the maximum value to the minimum value is 3 or less, and the specific resistance value is 5 × 10 ⁻¹ [Ω · cm] or less.
A sputtering target material that does not contain indium (In).
A _Zn / (A _Zn + A _Sn ) ≦ 0.6 (1) The invention has a SnO ₂ phase and a Zn ₂ SnO ₄ phase, and the ratio of the Zr element concentration in the Zn ₂ SnO ₄ phase to the Zr element concentration in the SnO ₂ phase is 0.1 or more and 5 or less. The sputtering target material described. _3. The sputtering target material according to claim 1, comprising ZrO ₂ crystal grains, wherein the ZrO ₂ crystal grains have an average grain size of 5 μm or less.   A sputtering target comprising the sputtering target material according to claim 1, claim 2 or claim 3.