JP2002004036A - ZnS-SiO2 TARGET MATERIAL AND ITS PRODUCTION METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ZnS-SiO2 target material capable of applying DC sputtering and provided with high-speed and stable sputtering properties thereby and to provide its production method. SOLUTION: This material is sintered with ZnS and SiO2 as essential components, and its electric resistance is controlled to <=1.0×104 Ωcm. As the components, Cu is further contained, and when the content of ZnS is defined as 100 mol%, the Cu content can be controlled to >=0.0002 mol%. The target material is produced by sintering a powdery mixture containing ZnS powder and SiO2 powder as essential components and further containing Cu powder. The Cu powder is added by >=0.0002 mol% to the ZnS content when the ZnS content is defined as 100 mol%. Donor impurities composed of one or more kinds of elements selected from iodine, chlorine, indium, aluminum and gallium may moreover be added to the above powdery mixture by suitable quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applicable to a DC sputtering method, whereby a ZnS
About ZnS-SiO ₂ based target having a low electrical resistivity can be deposited -SiO ₂ system layer.

[0002]

2. Description of the Related Art ZnS is one of II-VI group direct transition type compound semiconductors, and has a band gap of at least 3.5 eV at room temperature, so that it is transparent to light in the visible light region. A light emitting recombination center having high luminous efficiency can be easily formed by adding an appropriate impurity.
In addition to being widely used as a fluorescent material, it is considered to be promising as an optical device material in the ultraviolet region.

[0003] In recent years, phase-change type optical disks represented by CD-RW and DVD-RW have become widespread, and a ZnS-SiO
_Two- system membranes have been used. Demand for ZnS-SiO ₂ based target used for the film formation is increasing accordingly.

[0004] As a prior art relating to a ZnS-SiO ₂ based target material, there is a technique aimed at increasing the density (Japanese Unexamined Patent Publication No.
Japanese Patent Application Laid-Open No. 10-81954, Japanese Patent Application Laid-Open No. 10-81954, a device in which the uniformity of the film thickness distribution is improved (Japanese Patent Application Laid-Open No. 10-46328),
Japanese Patent Application Laid-Open No. Hei 10-81960) and a method in which crack generation during sputtering is suppressed (Japanese Patent Application Laid-Open No. 10-28013)
No. 8, JP-A-9-143703) and an improvement in sputter rate (JP-A-11-216).
No. 64 gazette).

[0005]

However, ZnS
-Among the SiO ₂ -based target materials, a target material capable of performing high-speed and stable sputtering has not yet been realized, and its development is desired.

The present invention has been made in view of the above circumstances, and is intended to provide a Zn alloy having a high-speed and stable sputtering property.
An S-SiO ₂ -based target material and a method for producing the same are provided.

[0007]

The ZnS-SiO of the present invention is provided.
_{The 2} target material is a ZnS—SiO ₂ target material obtained by sintering ZnS and SiO ₂ as essential components, and has an electric resistivity of 1.0 × 10 ⁴ Ωcm or less. This target material further contains C as a component.
u, and the Cu content is such that the ZnS amount is 1 with respect to the ZnS amount.
When it is set to 00 mol%, it can be made 0.0002 mol% or more. Further, it contains at least one element selected from iodine, chlorine, indium, aluminum and gallium, and the total content thereof is 1.0 × 10 ¹⁶
cm ^-3 or more. Further, the average particle size of ZnS can be set to 15 μm or more.

Further, the ZnS-SiO of the present invention_TwoSystem target
The manufacturing method of the sheet material is ZnS powder and SiO_TwoPowder
Sintering of mixed powder containing Cu powder as an essential component
ZnS-SiO_TwoThe method of manufacturing
The Cu powder has a ZnS content of 100 mol with respect to the ZnS content.
% And 0.0002 mol% or more
The electric resistivity is 1.0 × 10^FourΩcm or less ZnS-
SiO_TwoThis is a method of obtaining a system target material. This manufacturing method
In the method, the mixed powder further comprises iodine, chlorine,
One of the elements selected from indium, aluminum and gallium
Containing at least one species of donor impurity
1.0 × 10 in total number of atoms¹⁶cm ^-3What to do
Can be.

Further, the manufacturing method of the present invention is a method for manufacturing a ZnS-SiO ₂ target material in which a mixed powder containing ZnS powder and SiO ₂ powder as essential components is sintered, wherein the ZnS powder has an average crystallinity. Using a powder having a particle size of 15 μm or more, the sintered body after sintering is immersed in a zinc melt to obtain a ZnS—S having an electric resistivity of 1.0 × 10 ⁴ Ωcm or less.
This is a method for obtaining an iO ₂ -based target material.

Further, the production method of the present invention is a method for producing a ZnS—SiO ₂ target material in which a mixed powder containing ZnS powder and SiO ₂ powder as essential components is sintered. Using a powder of 15 μm or more, the ZnS powder is sintered in a state where evaporation of Zn from the ZnS powder is suppressed, and the ZnS powder having an electric resistivity of 1.0 × 10 ⁴ Ωcm or less.
This is a method for obtaining a SiO ₂ -based target material.

Further, the production method of the present invention, a mixed powder containing a ZnS powder and SiO ₂ powder as an essential component method of manufacturing a ZnS-SiO ₂ based target is sintered, a halogen element as the ZnS powder Is heated in a coexistence atmosphere of Cu and Cu vapor to obtain a powder in which Cu atoms are added to ZnS.
This is a method for obtaining a ZnS—SiO ₂ -based target material of ⁴ Ωcm or less.

Further, the production method of the present invention, a mixed powder containing a ZnS powder and SiO ₂ powder as an essential component method of manufacturing a ZnS-SiO ₂ based target sintering, sintering of the powder mixture At this time, the mixed powder and a halogen element coexist, and sintering is performed in a state where evaporation of halogen gas and Zn generated by thermal decomposition during sintering is suppressed, and the electric resistivity is 1.0 × 10 ⁴ Ωcm or less. ZnS
This is a method for obtaining a SiO ₂ -based target material.

Further, the production method of the present invention, a mixed powder containing a ZnS powder and SiO ₂ powder as an essential component method of manufacturing a ZnS-SiO ₂ based target sintering, sintering of the powder mixture At this time, the mixed powder and Zn
And sintering in the state of coexisting with a halide of Cu or a halide of Cu to obtain a ZnS—SiO ₂ target material having an electric resistivity of 1.0 × 10 ⁴ Ωcm or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have proposed ZnS-SiO ₂
In order to obtain high-speed and stable sputterability in a system-based target material, it is most effective to apply DC sputtering. To this end, the electrical resistivity of the target material must be reduced to a practical level at which DC sputtering can be performed. Based on the belief that it is necessary to lower the resistivity, we conducted intensive research.

The conventional ZnS-SiO ₂ target material has an electric resistivity of 1.0 × 10 ⁷ Ωcm or more. It is considered that the reason for the high electrical resistance is that the ZnS grains constituting the target material itself are high-resistance substances, and the ZnS grain boundaries existing in the target form electrical resistance. Therefore, as means for lowering the electric resistivity, ZnS which is an essential component of the target is added with a donor impurity, or conductivity is improved by removing a cause of carrier compensation, and ZnS particles in the target are improved. It was considered effective to increase the diameter and reduce the grain boundaries, which is one of the resistance factors. In addition, it may be effective to metallize the grain boundaries of ZnS with a conductive material such as a metal to impart electrical conductivity to the grain boundaries. The present invention has been completed by paying particular attention to the above.

In ZnS, constituent elements Zn and S have different dissociation pressures, respectively.
Report that the dissociation pressure of is higher than that of S
al Growth 88 (1988) p193-204. This suggests that ZnS produced in a high-temperature environment has many Zn vacancies. For this reason, it is considered that the presence of Zn vacancies is one of the causes of inhibiting the resistance reduction of ZnS. This will be described in more detail.

The Zn atom in the ZnS crystal usually discharges two electrons to the adjacent S atom position and is positively charged. For this reason, even if the lattice position where Zn originally exists is a hole, it is positively charged when viewed from the surroundings of the Zn hole.
It is considered that n vacancies have the property of easily capturing electrons. In other words, the fact that the Zn vacancy defect acts as a defect that captures electrons that are responsible for electrical conduction is the cause of the high resistance of the ZnS material. Generally, in order to obtain n-type conductive ZnS, a donor impurity that easily releases electrons such as indium, aluminum, potassium, iodine, chlorine, and bromine is added. However, when there is a Zn vacancy, the donor impurity is released. Since electrons are captured, Zn vacancies cause an increase in electrical resistance. Therefore, in order to reduce the resistance of ZnS, a process for reducing Zn vacancies or a process for suppressing the formation of Zn vacancies is required. The inventor has
As a result of intensive research based on such an idea, it was found that by adding Cu as one of the methods for lowering the resistance, the electrical resistivity was dramatically reduced.

It is considered that the reason for lowering the resistance by adding Cu is that the addition of Cu suppresses electron capture in Zn vacancies. The following can be mainly considered as a mechanism for suppressing electron capture. 2 if Zn vacancies remain
Where Cu acts as a valence acceptor, Cu enters the Zn vacancy site to become a monovalent acceptor, thereby reducing the degree of electron capture. Alternatively, Cu exists at an interstitial position or an S position adjacent to the Zn vacancy, and is paired with the Zn vacancy to lose the electron trapping property of the Zn vacancy. Further, when Cu is excessively added, many point defects are formed, and the electrical conductivity is improved by a hopping mechanism via the point defects.

Based on the above findings, ZnS powder and SiO
_{2 The} powder is an essential component, and the mixed powder obtained by adding and mixing the Cu powder is sintered to obtain a ZnS-Si having a low electric resistivity.
As a result of producing an O ₂ -based target material and performing DC sputtering using the same, as is clear from the examples described later, if the electric resistivity is 1.0 × 10 ⁴ Ωcm or less, a stable D value is obtained.
It was determined that C sputtering was possible. That is, in order to enable DC sputtering, it is necessary to set the electric resistivity to 1.0 × 10 ⁴ Ωcm or less. Furthermore, when DC sputtering is applied, not only the pulse DC method can obtain a film deposition rate 1.8 times the conventional rate than the conventional method, but the arc cut method can obtain a film forming rate 2.5 times the conventional rate, and even when the present invention is applied to the conventional RF sputtering method. A film deposition rate of 1.5 times was obtained. Although the target material did not intentionally add an n-type impurity, the conductivity was obtained because addition of Cu suppressed the electron trapping action by Zn vacancies, resulting in a donor residual impurity. It is considered that the electrons emitted from the aluminum and the chlorine have served as carriers that carry electric conductivity.

Regarding the Cu content in the ZnS—SiO ₂ based target material, the Cu content is expressed in mol% with respect to the ZnS content when the ZnS content is 100 mol%, that is, the mole number of the ZnS content is M1, Cu The number of moles is M2
The amount of Cu is expressed as M2 / M1 × 100% (mol%), and is set to 0.0002 mol% or more. 0.0002
If it is less than mol%, a sufficient effect cannot be obtained, and 1.0 × 10 ⁴
It is difficult to obtain a practical level of electrical resistivity of Ωcm or less. However, when the Cu content is less than 0.002 mol%, it is difficult to uniformly disperse Cu, and a high-resistance portion remains locally, so that arcing is likely to occur during sputtering. Therefore, a content of 0.002 mol% or more is preferable. If the Cu content exceeds 10 mol%, the target tends to crack when densified, and the like, so that it is preferable to keep the Cu content to 10 mol% or less.

Further, SiO ₂ in the target material may be used.
With respect to the content of SiO _{2, the} amount of SiO ₂ is represented by mol% based on the amount of ZnS when the amount of ZnS is 100 mol%, and 1
The content is preferably 0 to 45 mol%. SiO ₂ is necessary for making the sputtered film amorphous, and if it is less than 10 mol%, the sputtered film will crystallize, and peeling due to film stress will be observed. On the other hand, if it exceeds 45 mol%,
The refractive index of the sputtered film decreases, and the sputtered film deviates from the optical characteristics required as a dielectric film.

The composition of the mixed powder is almost the same as the composition of the target material obtained by sintering the mixed powder. The essential components of the mixed powder or the target material are ZnS and Si.
In addition to O ₂ , it contains unavoidable impurities and does not hinder the inclusion of various components contributing to the reduction of resistance within a range that does not impair the optical characteristics required as a sputtered film, for example, the above-described Cu and donor impurities described below. Means

In the above-mentioned target material, the desired low electrical resistivity can be obtained without adding any n-type impurity. However, in addition to Cu, one or more donor impurities such as iodine are added in combination. Thereby, the resistance can be further reduced. The reason is considered to be that Cu plays a role of reducing the number of Zn vacancies, iodine and the like as N-type impurities having a donor property do not interfere with each other, and each works effectively.

As described above, in general, N-type conductive Zn is used.
In order to obtain S, a donor impurity such as indium, aluminum, gallium, iodine, or chlorine that easily emits electrons is added. However, if there is a Zn vacancy, the electrons emitted by the additional impurity are easily captured by the Zn vacancy. Therefore, no matter how much donor is added, the electrical resistance cannot be reduced. The present inventors have also attempted to simultaneously add Cu and indium, aluminum, gallium, and chlorine, which are typical donor impurities, in addition to iodine, and obtained a composite of one or more of these donor impurities and Cu. By addition
Electron capture phenomenon by Zn vacancies can be eliminated,
It was found that the electrical resistivity dropped dramatically.

The donor impurities iodine, indium,
Regarding the method of adding aluminum and gallium, ZnS powder was prepared by adhering these components to the surface of ZnS powder particles in advance.
A powder may be used, and the donor impurity may be added to and mixed with the ZnS powder, the SiO ₂ powder, and the Cu powder at the same time, or a mixed powder thereof. As for chlorine, zinc chloride may be mixed simultaneously with ZnS powder or the like, or may be added to the mixed powder.

Regarding the contents of the above-mentioned iodine, chlorine, indium, aluminum and gallium, it is preferable that the total amount of one or more of them is 1.0 × 10 ¹⁶ cm ⁻³ or more in terms of the number of atoms. If it is less than 1.0 × 10 ¹⁶ cm ⁻³ , a sufficient effect is hardly obtained because the carrier concentration is too low. However, 1.0
The content exceeds × 10 ¹⁹ / cm ^3, the atomic ratio i.e. activation rate acts as an n-type impurity is decreased, the effect of lowering the electrical resistivity is saturated, 1.0 × 10 ¹⁹ / cm ³
It is better to stop below. Even when the above-mentioned donor impurity is positively added, the amount of Cu is set to 0.1 as described above.
0002 mol% or more is added, preferably 10 mol% or less.

The reduction of the resistance by removing Zn vacancies or increasing the carrier concentration has been described above.
A method for lowering the resistance by reducing the grain boundaries will be described. The present inventor has studied in detail the influence of the ZnS grain boundary of the target material. As a result, by reducing the grain boundary, that is, by increasing the ZnS crystal grain size, the grain boundary forming the resistance component is reduced. As is clear from the examples, it was found that by setting the average crystal grain size of ZnS to at least 15 μm or more, the electrical resistivity could be reduced to a practical level at which DC sputtering was possible. In the present invention, the average crystal grain size was evaluated by the Fullman method. That is, the crystal grain boundaries were recognized by mirror polishing and etching, the structure was observed with an electron microscope, and the average crystal grain size was determined using the following equation. Dm = (4 / π) · (NL / NS) where Dm is the average crystal grain size, NL Is the number of crystal grains per unit length hit by an arbitrary straight line on the observation surface observed with a microscope, and NS is the number of crystal grains contained in an arbitrary unit area.

As a method of increasing the crystal grain size of ZnS in the target material, first, ZnS having a large crystal grain size is used.
A method of using powder as a raw material powder will be described. Z
The crystal grain size of the nS powder can be expanded by using a halogen element such as iodine as a catalyst and using ZnS in the presence of a halogen element.
This can be realized by soaking and heating the powder. Specifically, ZnS powder may be vacuum-sealed in a quartz glass container together with a halogen element such as iodine, and heated under uniform heat. At this time, ZnS powders having various crystal grain sizes can be obtained by adjusting the heating temperature and the heating time. In the present invention, such a method is called a halogen transport method.

The halogen element may be iodine which is solid at room temperature, chlorine or bromine which is gaseous or liquid, or not only a single halogen element but also a halogen element such as indium, aluminum, gallium or the like. A halide with a group III element or a halide with Zn or Cu may be used. From the viewpoint of handleability, iodine and halide which are solid at room temperature are preferable. The halide is easily thermally decomposed by heating, the halogen element works effectively as a catalyst for increasing the particle size, and the group III element is taken into ZnS as a donor, contributing to lowering the resistance. It is generally known that a halogen element such as iodine, which is substituted for S at the S lattice position in ZnS and acts as a donor impurity, and the halogen element also acts as a donor as well as an increase in particle size. It is also expected. For this reason, the halogen transport method is considered to be the most excellent method for obtaining uniform particles doped with carriers uniformly. When using a halide of Zn,
In addition to the effect of the halogen element generated by thermal decomposition to enlarge the particle size, increasing the partial pressure of Zn vapor during halogen transport increases the
An effect of suppressing the increase in the Zn composition in nS and, consequently, the formation of Zn vacancies can also be expected. In the case of using a halide of Cu, in addition to the action of expanding the grain size by the halogen element, Cu acts during the grain growth, and C
u atoms can be provided. The advantage of using a Cu halide will be further described later.

In the halogen transport method for expanding the grain size of ZnS crystal grains, the heating temperature is preferably in the range of 700 to 900 ° C. In this temperature range, it was confirmed that the particle size increases with an increase in the processing temperature and the processing time. In order to obtain a realistic growth rate, it is desirable that the temperature be at least 700 ° C. or higher.

As one of the methods for growing a ZnS single crystal, an iodine transport method is known, for example, as described in Sharp Technical Report No. 37, paragraphs 13 to 16.
In the iodine transport method, a ZnS raw material is disposed at one end of a quartz ampoule in which iodine is enclosed, and a seed of a ZnS single crystal is disposed at the other end. Placed in a furnace with a temperature heating zone. In the quartz ampoule, ZnS is transported from the high temperature side to the low temperature side via iodine, and a crystal grows in the low temperature part. According to this method, a single crystal of about 20 grams can be obtained in about one month. However, the present inventors vacuum-enclosed ZnS powder in a quartz glass container together with iodine and tried to enlarge the particle size by a conventional iodine transport method.On the low temperature side, the particle size was remarkably reduced to about several mm. On the other hand, on the other hand, on the other hand, on the high temperature side, some particles remained in the state of raw material powder, and the variation in particle diameter became large as a whole. The target material using such ZnS powder as the raw material powder becomes non-uniform in material, which leads to deterioration of the quality of the sputtered film. Therefore, the conventional iodine transport method is difficult to apply as a method for enlarging the crystal grain size of ZnS powder.

A mixed powder composed of a ZnS powder whose crystal grain size is enlarged by the halogen transport method according to the present invention (the halogen element used is iodine) and a SiO ₂ powder is filled in a carbon mold, and hot pressed. The ZnS—SiO ₂ -based target material simply sintered by the method described above had an electric resistivity of 1.0 × 10 ⁷ Ωcm or more, and did not reach a practically low level of resistivity capable of DC sputtering. Then, as a result of immersing the sintered material in the zinc melt for about several tens of hours and performing a process of reducing Zn vacancies (referred to as a zinc melt process),
The resistivity dropped sharply. The resistance decrease width is larger as the average crystal grain size of ZnS is larger. When the average grain size is 15 μm or more, 1.0 × 10 ⁴ Ωcm to which DC sputtering can be applied.
The following has been reached. That is, ZnS in the target tissue
The average crystal grain size is at least 15 μm or more, that is, the ZnS powder used as a raw material has a ZnS average crystal grain size of at least 15 μm.
By setting m or more, the resistance can be reduced to a practical level without adding Cu. It should be noted that all of these targets contain iodine in IC
It was confirmed by P-Mass analysis.

As described above, a mixed powder using ZnS powder grown as a raw material powder by the halogen transport method is sintered, and the obtained sintered body is treated with a zinc melt to add Cu. And a practically low resistance can be realized. However, when the zinc melt treatment is performed, φ10
In the production of large target materials of about 0 mm or more,
There are problems such as cracks occurring during removal from the zinc melt and a relatively long time required for the treatment.

Then, a method for realizing a low resistance without performing a zinc melt treatment after sintering will be described below. When a mixed powder of ZnS powder and SiO ₂ powder is hot-pressed, the hot press sinters the powder in an unsealed state, so that Zn is removed from the ZnS crystal during hot pressing and Zn vacancies are generated. It is presumed that by performing the zinc melt treatment, Zn is filled in Zn vacancies generated by Zn elimination and the number of Zn vacancies is reduced, thereby realizing low resistance. Therefore, by preventing Zn loss (generation of Zn vacancies) at the time of sintering, it is possible to realize a low resistance at a practical level. That is, the average crystal grain size is 15 μm.
When sintering a mixed powder of ZnS powder and SiO ₂ powder of m 2 or more and sintering in a state where evaporation of Zn is prevented, a target material having an intended low resistivity can be obtained.

To prevent the evaporation of Zn from ZnS, for example, the mixed powder is vacuum-enclosed in a heat-resistant and flexible hermetically sealed container (capsule) and subjected to HIP (Hot Isostatic Pressing) treatment ( Capsule HIP) and Z
This can be realized by discharging Zn vapor in a vacuum sealed container provided with n reservoirs and performing sintering processing such as hot pressing under the control of Zn vapor pressure. In addition, the semi-closed mold in which the clearance of the fitting portion is suppressed to a very small value (for example, about several tens μm or less), although the effect of preventing Zn detachment is slightly inferior to that of the densification and sintering under the closed atmosphere. It can also be realized by a hot press or the like. The clearance of the fitting portion of the mold used in a normal hot press (sometimes referred to as an unsealed hot press) is about 100 μm.

Next, a method of realizing a low resistance by sintering in a non-sealed atmosphere by a normal hot press or the like without performing a zinc melt treatment will be described. This method is a method of producing a target material by sintering a mixed powder of a ZnS powder and a SiO ₂ powder which are treated by a halogen transport method in which a halogenated substance of Cu or a simple substance of a halogen element and Cu are simultaneously added. It is.

In carrying out the halogen transport method, the Cu
Is thermally decomposed into Cu and halogen gas,
A halogen gas is generated from a single halogen element. When the halogen transport method is performed, halogen gas and Cu atoms are taken into the ZnS crystal via the gas phase. As described above, the Cu atoms incorporated in the ZnS crystal have an effect of reducing the effect of incorporation into the Zn vacancy positions or the compensation effect due to pairing with the Zn vacancies. A greenish-brown ZnS powder obtained by applying the iodine transport method by simultaneously adding iodine and Cu powder to the ZnS powder raw material is suitable as the raw material powder.

The ZnS powder obtained by this method and S
When the mixed powder with the iO ₂ powder is used, the electric resistivity can be remarkably reduced to a level of 10 0 to 1 Ωcm without performing a zinc melt treatment even in a normal hot press. . In this method, Cu
Since the effect of lowering the resistance by the addition of atoms is remarkable, the average crystal grain size of ZnS does not necessarily need to be grown to 15 μm or more. Of course, by setting the average crystal grain size to 15 μm or more, lower resistance can be achieved.

Further, another process which can realize a low resistance without performing a zinc melt treatment after sintering will be described. This process uses ZnS with an increased grain size.
This is a method in which sintering is performed while using ZnS crystal grains during sintering without using a powder raw material. Specifically, when sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components, the mixed powder and a halogen element coexist, and halogen gas and Zn vapor generated by thermal decomposition during sintering are used. Sintering in a state in which the dissipation of water is suppressed.

The sintering is performed, for example, in a capsule HIP, Z
It can be carried out by hot pressing in a closed chamber provided with an n-reservoir, or semi-closed hot pressing using a mold in which the clearance of the fitting portion is formed densely. By the sintering, the dissipation of the halogen gas and the escape of Zn from ZnS are prevented, and the generation of Zn vacancies is suppressed. The rate can be a practically low resistivity.

The halogen element is used as a sintering aid, and may be a simple halogen element such as iodine, chlorine, or bromine.
n, other indium, aluminum, gallium, etc.
It may be a halide with a group III element. From the viewpoint of handleability, iodine and halide which are solid at room temperature are preferable. The halide is easily thermally decomposed by heating, and the generated halogen gas effectively works as a catalyst for increasing the particle size. In addition, the group III element is taken into ZnS as a donor, thereby contributing to lowering the resistance.

When a halide of Cu or a halide of Zn is used as a sintering aid, sintering can be carried out in a non-sealed atmosphere by ordinary hot pressing or the like, and the productivity is excellent. At room temperature, chlorine is a gas, bromine is a liquid, and iodine is the only solid halogen substance. However, since its boiling point is as low as 185 ° C., it tends to volatilize during temperature rise even when used as a sintering aid. . Also, among the halides, aluminum iodide, gallium chloride, and the like have a high vapor pressure, and components are lost during sintering in a non-closed atmosphere typified by ordinary hot pressing during temperature rise. Therefore, when these components are used as sintering aids,
As described above, sintering in a closed or semi-closed atmosphere is required. However, halides of Zn or Cu, such as copper iodide and copper chloride, have a high boiling point, can suppress volatilization during temperature rise, and do not have the above-mentioned disadvantages. The target material having a low resistivity can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not construed as being limited to such Examples. For example, as a sintering method, there is no need to employ a pressure sintering method for simultaneously performing densification and sintering by pressing as in a hot press or a capsule HIP. Tying techniques. In this case, since the evaporation of Zn from ZnS occurs during the sintering step, when it is necessary to prevent the evaporation of Zn, a measure such as performing sintering under a Zn vapor pressure may be adopted.

[0044]

EXAMPLES <Example group A> Average particle size 7 μm (0.02
The primary particles having a diameter of 0.03 μm are aggregated to form a particle having a diameter of about 7 μm.
A mixed powder was prepared by using ZnS powder of the following particles), Cu powder having an average particle size of 5 μm, and SiO ₂ powder having an average particle size of 3 μm or less. Table 1 shows the amount of Cu powder added to ZnS powder (5 mol). The amount of SiO ₂ powder added was 1.25 mol (25 mol with respect to ZnS powder).
%).

The mixed powder was adjusted to φ1 such that the thickness became 7 mm.
The carbon molds of 00 mm and 50 mm square were filled, pressed by a non-enclosed hot press (the clearance at the fitting portion of the mold was 100 μm), densified and sintered. The conditions of the hot press are a maximum temperature of 1000 ° C., a pressure of 24.5 MPa,
The atmosphere was Ar.

Using the obtained target material sample, Cu
Was confirmed by SEM-EDX.
Although a little segregated at the grain boundaries, it was dissolved in ZnS. The average crystal grain size of ZnS in the structure of the target material was measured by the Fullman method.
It was about 5 μm. Further, the electric resistivity of each target material was measured, and DC sputtering (input power of DC sputtering during film formation: 5 W / cm ² ) was performed.
The arc generation status (the number of times of arcing) at that time was examined.
The results of these investigations are also shown in Table 1.

The electric resistivity was measured by the four-terminal method for those which can be measured by the four-terminal method. However, when the electric resistivity becomes 1.0 × 10 ⁴ Ωcm or more, the electric resistance of the electrode is often increased. Accurate measurement cannot be performed due to poor ohmic characteristics. Only in this case, the resistance was measured by the two-terminal method. 5 × 5 × 0.6t in 4-terminal method
(Mm) A measurement piece cut out in a plate shape was prepared, and a gold wire was soldered at four corners using an alloy electrode containing indium as a main component, and the measurement was performed. In the two-terminal method, 5 × 5 × 0.
An indium metal electrode was formed on one surface of each of the 6 t (mm) measurement pieces, and the resistance was measured from the amount of current when a voltage of 30 V was applied.

[0048]

[Table 1]

Sample No. 1 had no Cu added.
Sputter discharge could not be performed. When the target material of Sample No. 2 in which the amount of Cu added is less than 0.0002 mol% is applied to DC sputtering, arcing frequently occurs, the discharge state becomes unstable, and two modes of glow discharge and arc discharge are performed. Alternately occurred. Usually, ZnS-
The SiO ₂ film is transparent, but with the transition of the discharge mode,
As a result of irradiating the film with a large number of charged particles, the film was damaged and turned black, indicating that it could not be used as a dielectric film for an optical recording medium. From Sample Nos. 2 to 13, it was observed that the arcing rate and the electrical resistivity tended to decrease as the Cu addition amount increased. It was found that Sample Nos. 3 to 13 having an electric resistivity of 1.0 × 10 ⁴ Ωcm or less were practically usable as an optical recording dielectric film since no blackening of the film occurred. Further, Cu
When the addition amount was 0.002 mol% or more, arcing was sharply reduced, and the discharge state was very stable. If the added amount of Cu is less than 0.002 mol%, uniform dispersion of Cu is difficult,
It is considered that there is a locally high-resistance portion, which may cause arcing. However, in the case of No. 13 in which the added amount of Cu was 11 mol%, the target material tended to crack easily during densification.

Further, with respect to the sample target materials to which Cu was added in an amount of 0.0002 mol% or more (sample Nos. 3 to 13),
A dielectric film having a thickness of 1 μm was formed by DC sputtering, and the optical characteristics were evaluated by ellipsometry. As a result, the refractive index at a wavelength of 635 nm was 2.1.
The transmittance was about 7 and the transmittance was 95% or more in all the samples. This is a sufficient value for the optical characteristics required for the dielectric film. Furthermore, using the target materials of Sample No. 1 (Comparative Example) and No. 10 (outer diameter: φ100 mm), the sputter deposition rates by reducing the resistivity of the target materials were compared. The input power during sputtering was 400 W, the atmosphere was Ar, and the pressure during sputtering was 5 mTorr. When RF sputtering was performed using the No. 1 target material, the film formation rate was 0.33 nm / (W · cm ² ) · sec. On the other hand, when the target material of No. 10 was used, the deposition rate was 0.82 nm / (W · c
m ² ) · sec, pulse DC sputtering (pulse frequency 50 kHz)
0.59 nm / (W · cm ² ) · se for z, Duty ratio 40%)
c, In the RF sputtering, the rate was 0.48 nm / (W · cm ² ) · sec, and an excellent film formation rate was obtained.

<Example Group B> Average particle size 7 μm (0.02
Primary particles having a diameter of about 0.03 μm are aggregated and
Secondary particles), ZnS powder having an average particle size of 5 μm.
Cu powder and SiO with an average particle size of 3 μm or less_TwoIncluding powder
Then, a mixed powder further containing donor impurities was prepared. Z
Cu powder and donor impurities for nS powder (5 mol)
Table 2 shows the addition amounts of the substances. The addition amount is Z
mol% based on the nS amount, SiO _TwoOf Zn
The content was 25 mol% based on the S powder. II-VI group compound half
Group VII as a donor impurity of ZnS, one of the conductors
Elements or Group III elements apply, but in this example
Are iodine and chlorine as Group VII elements, and
Luminium, gallium, and indium were used. Iodine
The addition method is to add a predetermined amount of iodine to ZnS powder particles in advance.
Raw material powder to which elementary particles were attached was used. How to add chlorine
After grinding zinc chloride in a nitrogen atmosphere, ZnS powder,
SiO_TwoPowder and Cu powder at the same time
Was. For indium, aluminum and gallium
Attached to ZnS powder particle surface in the same way as the addition of iodine
Raw material powder was used.

Using the above mixed powder, a target material was prepared by hot pressing in the same manner as in Example Group A, and the electrical resistivity was measured. The results are also shown in Table 2. In addition, the average crystal grain size of ZnS in the target material was set to Fullman
When measured by the method, each sample was about 8.7 μm.

[0053]

[Table 2]

In Table 2, the electrical resistivity of the samples Nos. 21 to 26 in which iodine and Cu were simultaneously added is about one digit lower than that in the case where only Cu was added. However, in Sample No. 21 in which the added amount of Cu was less than 0.0002 mol%, the electrical resistivity was more than 1.0 × 10 ⁴ Ωcm, and it can be seen that the resistance cannot be reduced only by adding iodine. Sample Nos. 32 to 35 in which chlorine, indium, aluminum, and gallium were simultaneously added with Cu as donor impurities as in the case of iodine,
When only Cu is added (Sample No. 8 in Table 1 of Example Group A)
), Which indicates that the simultaneous addition with the donor impurity is effective for further lowering the resistance.

Sample Nos. 25 and 27 to 31 in the table were as follows:
The results of examining the amount of iodine (number of atoms) for optimizing the addition amount of the dopant are shown. For these samples, I
The amount of iodine was analyzed by the CP-Mass method, and the analysis values are shown in the table. As a result, the iodine content was 1.0 × 10 ¹⁵
No. of cm ^-3 . In No. 31, the electrical resistivity was equivalent to the case where iodine was not added (Sample No. 8 in Table 1). This indicates that the donor impurity concentration in at least the composite addition is preferably 1.0 × 10 ¹⁶ cm ⁻³ or more.

<Example Group C> In order to investigate the influence of the crystal grain size of ZnS in the target material, various ZnS powders having different crystal grain sizes were produced by a halogen transport method using uniform heating. The ZnS powder has an average particle diameter of about 7 μm (a primary particle having a diameter of 0.02 to 0.03 μm is collected to form a 7 μm
A secondary particle having a diameter of about m) is vacuum-sealed together with iodine in a quartz glass container together with iodine, and is heated uniformly to increase the crystal grain size. The processing conditions were as follows: the amount of iodine added was 2 mg / cc per unit volume according to the volume of the quartz container.
It was kept for 8 hours under soaking at 00 ° C., 840 ° C. and 900 ° C., respectively. As a result, the average crystal grain size of the obtained ZnS powder was 11 μm, 16 μm, 26 μm, 42 μm, 8 μm, respectively.
It was 3 μm. For some of the powders, Cu was added in an amount of 0.1 mol based on the ZnS amount when the iodine transport method was performed.
%, The iodine content was adjusted to 2 mg / cc, and the mixture was kept at 900 ° C. for 8 hours to obtain a powder having a particle size of 106 μm.

A mixed powder is prepared by mixing the above-mentioned expanded particle size ZnS powder (5 mol) and SiO ₂ powder (25 mol% based on the amount of ZnS), and this mixed powder is unsealed hot pressed or capsule HIP. It was densified and sintered to produce a target material. Table 3 shows the average particle size of the used ZnS powder (the one with “(Cu)” indicates the one added with Cu during the iodine transport method) and the type of sintering method. The conditions of the hot pressing were the same as those in Example Group A, and the conditions of the capsule HIP were a holding temperature of 1000 ° C.
The holding pressure was 100 MPa and the holding time was 3 hours. Also,
For sample Nos. 41 to 45 in Table 3, the target material after sintering was subjected to a zinc melt treatment in which it was immersed in a zinc melt at 920 ° C. for 24 hours.

The electrical resistivity of the target material manufactured as described above was measured in the same manner as in Example Group A. The crystal grain size of ZnS in the target material was measured for each sample after sintering. The results are shown in Table 3.

[0059]

[Table 3]

Samples Nos. 41 to 45 in Table 3 all have a resistance of 1.0 × 10 ⁷ Ωcm or more when only hot pressing is applied. Looks like not. This is due to the Zn
It is considered that the resistance is increased due to the formation of the holes. On the other hand, when these samples were subjected to the zinc melt treatment after sintering, the resistivity was lowered in each case, and it is apparent that the enlargement of the particle size is clearly effective for lowering the resistance. In particular, in Sample Nos. 42 to 45 in which the average crystal grain size of ZnS was 15 μm or more, 1.0 × 10
⁴ Ωcm or less.

On the other hand, in sample No. 46, the capsule HIP method was applied so that zinc did not escape during sintering. By performing densification and sintering in a closed atmosphere, densification,
Low resistance was obtained directly without performing a zinc melt treatment after sintering. The resistivity of sample No. using raw materials with the same particle size
45 was almost the same as the one subjected to the zinc melt treatment.

[0062] Sample No. 47 is obtained by densification and sintering by a normal hot press. However, since Cu coexists when the particle size of ZnS is increased, it is necessary to perform a zinc melt treatment after sintering. Thus, a target material having a very low resistance of 1 Ωcm level was obtained. This embodiment is excellent in productivity without performing densification and sintering in a closed atmosphere, without the need to perform a zinc melt treatment after sintering. The ZnS powder used for the preparation of the sample is subjected to the iodine transport method containing Cu, so that the particle size tends to be slightly larger. Cu
In the case where no Cu was contained, polyhedral crystal grains having a specific crystal plane were obtained, but in the case where Cu was contained, the anisotropy during the growth process was lost, resulting in spherical grains. For this reason, it was observed that the densification rate in sintering was also increased.
In any of the samples, the crystal grain sizes of ZnS powder material and ZnS in the target material are almost equal, and it can be seen that the crystal grain size hardly changes by sintering or zinc melt treatment.

<Example Group D> Average particle size 7 μm (0.02
Primary particles having a diameter of about 0.03 μm to form secondary particles having a diameter of about 7 μm), SiO ₂ powder having an average particle diameter of 3 μm or less, and various sintering aids containing a halogen element. A mixed powder to which an agent powder (average particle size of 10 μm or less) was added was prepared. The types of the sintering aid are as shown in Table 4. The amount of the sintering aid was 0.1 mol% and the amount of the SiO ₂ powder was 25 mol% based on the ZnS powder (5 mol).

Using the mixed powder, the mixed powder was sintered by a non-closed hot press or capsule HIP to prepare a target material. The hot pressing conditions were the same as in Example A, and the capsule HIP conditions were a holding temperature of 10
00 ° C., holding pressure 100 MPa, and holding time 3 hr. For the target material prepared as described above,
In the same manner as in Example Group A, the electrical resistivity and the crystal grain size of ZnS in the target material were examined. Table 4 shows these results.
Are shown together.

[0065]

[Table 4]

Samples Nos. 51 and 52 in Table 4 used zinc iodide as a sintering aid and used hot pressing and capsule HIP as sintering methods, respectively. The aim was to suppress the formation of Zn vacancies. The average crystal grain size of ZnS in the target material after sintering has grown to 27 μm and 46 μm, respectively, and the resistivity has been reduced to the first half of the 10th power in each case. Sample No. 53 uses zinc chloride as a sintering aid. In this example, zinc iodide was used as a sintering aid.
Although slightly inferior to Nos. 51 and 52, the effect is found in the growth of crystal grains and the reduction in resistivity.

Samples Nos. 54 and 55 used Cu halide as a sintering aid, and although these were sintered by hot pressing in a non-closed atmosphere, the crystal grains The growth is remarkable. The reason is that these halogenated substances evaporate less than others,
It is considered that the halogen gas promoted grain growth and Cu atoms were added to ZnS, without being removed from the mold until the temperature reached a high temperature state.

Sample Nos. 56 to 59 were made of indium iodide, aluminum iodide, gallium chloride,
Gallium iodide is used. Since these halides are substances having a high vapor pressure, they are sintered by capsule HIP. All of these target materials also have a practically low resistivity.

[0069]

As described above, the ZnS-S of the present invention is used.
The electrical resistivity of the iO ₂ -based target material is 1.0 × 10 ⁴ Ω
cm or less, so DC sputtering can be applied,
A ZnS—SiO ₂ film suitable as a dielectric film for an optical recording medium can be stably manufactured at high speed by DC sputtering. According to the manufacturing method of the present invention, ZnS—SiO ₂ having a low resistivity applicable to the DC sputtering is used.
The system target material can be easily manufactured.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Miyamoto 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo F-term in Kobe Steel Research Institute, Kobe Research Institute (reference) 4G030 AA26 AA34 AA37 AA56 CA05 GA24 GA29 GA35 4K029 CA05 DC05 DC09

Claims (11)

[Claims] 1. A ZnS—SiO ₂ target material sintered with ZnS and SiO ₂ as essential components,
ZnS— having an electric resistivity of 1.0 × 10 ⁴ Ωcm or less.
SiO ₂ target material. 2. It further contains Cu, and the Cu content is ZnS
0.0% when the ZnS amount is 100 mol% with respect to the amount
The ZnS-S according to claim 1, which is at least 002 mol%.
iO ₂ -based target material. 3. The method according to claim 1, further comprising at least one element selected from iodine, chlorine, indium, aluminum and gallium, wherein the total content of the elements is at least 1.0 × 10 ¹⁶ cm ^-3 in terms of the number of atoms. ZnS-SiO ₂ described in 1 or ₂
System target material. 4. The ZnS—SiO _{2 according} to claim 1, wherein the average particle size of ZnS is 15 μm or more.
System target material. 5. A method of sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components and further containing Cu powder.
A method for producing an nS—SiO ₂ target material, wherein Cu powder is added in an amount of 0.0002 mol% or more when the ZnS amount is 100 mol% with respect to the ZnS amount, and the electric resistivity is 1. ZnS-Si of 0 × 10 ⁴ Ωcm or less
Method of manufacturing a ZnS-SiO ₂ based target to obtain O ₂ based target. 6. The mixed powder further contains a donor impurity composed of at least one element selected from iodine, chlorine, indium, aluminum, and gallium, and the total content of the donor impurity is 1.0 × 10 ¹⁶ cm ^-3 or more in the production method of the ZnS-SiO ₂ based target according to claim 5 is. 7. A method for producing a ZnS—SiO ₂ target material, comprising sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components, wherein the ZnS powder has an average crystal grain size of 15 μm or more. the use, the sintered body after sintering was immersed in a zinc melt, the manufacture of electrical resistivity 1.0 × 10 ⁴ Ωcm obtain the following ZnS-SiO ₂ based target ZnS-SiO ₂ based target Method. 8. A method for producing a ZnS—SiO ₂ target material comprising sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components, wherein a powder having a particle size of 15 μm or more is used as the ZnS powder. Sintering the ZnS powder while suppressing the evaporation of Zn from the ZnS powder, and having an electrical resistivity of 1.0 × 10 ⁴ Ωcm or less.
Method of manufacturing a ZnS-SiO ₂ based target to obtain a SiO ₂ based target. 9. A method for producing a ZnS—SiO ₂ target material, comprising sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components, wherein the ZnS powder is a coexistence atmosphere of a halogen element and Cu vapor. Using a powder obtained by heating in ZnS and adding Cu atoms to ZnS, the electrical resistivity is 1.0 × 10 ⁴ Ωcm by sintering.
Obtain the following ZnS-SiO ₂ based target ZnS-
A method for producing a SiO ₂ target material. 10. A ZnS-SiO _{2 for} sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components.
A method for producing a system target material, wherein the mixed powder and a halogen element coexist during sintering of the mixed powder, and in a state where evaporation of halogen gas and Zn generated by thermal decomposition during sintering is suppressed. Sintered, ZnS-S with electric resistivity of 1.0 × 10 ⁴ Ωcm or less
method of manufacturing a ZnS-SiO ₂ based target to obtain iO ₂ based target. 11. A ZnS-SiO _{2 for} sintering a mixed powder containing ZnS powder and SiO ₂ powder as essential components.
A method for producing a system-based target material, comprising: sintering the mixed powder in a state where the mixed powder and a halide of Zn or a halide of Cu coexist; an electric resistivity of 1.0 × Z of 10 ⁴ Ωcm or less
ZnS-SiO ₂ to obtain a nS-SiO ₂ based target
Method of manufacturing a target material.