JPH06220624A - Target for sputtering and its production - Google Patents

Abstract

PURPOSE:To enable simplifying of a device and to improve a film forming velocity by constituting the target of the sintered body composed essentially of SiC and a Ta compd. CONSTITUTION:The target for sputtering is composed of the sintered body consisting essentially of SiC and at least one kind Ta compd. selected from the group consisting of TaC, TaN, TaB2, TaSi2 and TaH2. The amount of the Ta compd. is 10-50vol.% based on the total amount (vol.) of SiC and the Ta compd. The SiC powder and the powder of the Ta compd. selected from the group consisting of TaC, TaN, TaB2, TaSi1 and TaH2 are mixed, heated and sintered to obtain the sintered body. The compounding a mount of the Ta compd. is 10-50vol% based on the total amount (vol.) of SiC and the Ta compd. In this way, an operating property can be improved because a long time and continuous sputtering can be executed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target composed of a sintered body containing SiC and a Ta compound as main components, and a method for producing the same. The sputtering target of the present invention is particularly preferably used as a highly durable protective layer for heat ray shielding glass, thermal heads and the like.
It is useful as a sputtering target used when forming a Ta-C thin film by sputtering.

[0002]

2. Description of the Related Art Recently, a number of thin films having various functions have been applied in the fields of optics and electronics, but in general, these functional thin films alone may have problems in abrasion resistance and chemical stability. Many. Therefore, a film having excellent wear resistance, oxidation resistance, chemical resistance and the like is formed on the surface of these functional thin films for protection from the use environment.

For example, it efficiently shields solar radiation heat,
Heat ray shielding glass, which has the effect of reducing air-conditioning load, is widely used as window glass for buildings and automobiles from the viewpoint of energy saving. It has a heat ray shielding function for metals such as Ti, Cr, and Ni or metal compounds. The surface of the thin film is covered with a highly durable protective film. Further, a thermal head used for a facsimile or the like has a protective film having excellent oxidation resistance and abrasion resistance formed on the surface of a heating element.

Conventionally, as the protective film material as described above, S
iO _x , SiC, SiN _x, etc. have been put to practical use. As a method for forming a thin film, a vacuum vapor deposition method, a CVD method (chemical vapor deposition method), a sputtering method and the like are widely used. Among them, the sputtering method, in particular the DC sputtering method, has a higher selectivity of the substrate, mass productivity, and
It is considered advantageous in terms of manufacturing costs. However, in the direct-current sputtering method, film characteristics, film forming rate, operability, etc. greatly depend on the properties of the target material used, and therefore there is a strong demand for improving the characteristics of the sputtering target even in the formation of the protective film.

As a target for direct-current sputtering which has been conventionally used for forming a thin film of SiO _x , SiN _x, etc., there is a Si polycrystalline body to which conductivity is imparted by adding boron or the like. As a result, a target thin film was formed by a reactive sputtering method in which oxygen or nitrogen was introduced. In addition, SiC
As a target for direct-current sputtering for forming a thin film, there was a SiC reaction sintered body containing free Si.

[0006]

However, when the above-mentioned Si polycrystalline body or SiC reaction sintered body is used as a target for DC sputtering, there are the following inconveniences. When using a Si polycrystal as a sputtering target and performing reactive sputtering in an atmosphere of oxygen or nitrogen, the surface of the Si target undergoes an oxidation reaction or a nitriding reaction to form an electrically insulating substance such as SiO ₂ or S.
Since i ₃ N _{4 and the} like are formed and the electrical conductivity of the target is deteriorated, arc discharge easily occurs and the process becomes unstable.

When the SiC reaction sintered body is used as a sputtering target, it is difficult to form a high-purity SiC thin film because it contains a large amount of free Si. Further, when reactive sputtering is performed in an oxygen or nitrogen atmosphere, SiO ₂ is generated on the surface similarly to the Si target, so that it is difficult to maintain stable DC sputtering in a short time.

On the other hand, conventional SiO _x , SiN _x , S
With respect to the protective film such as iC, the use environment has become more severe as the functionality of the product becomes higher, so that the problem of its characteristics has been pointed out. For example, it has become clear that the SiO _x film has drawbacks in wear resistance, the SiN _x film has chemical resistance and adhesion to a substrate, and the SiC film has toughness.

The present invention has been made in view of the above technical background, and an object thereof is to have a small refractive index and absorption coefficient in the visible region as optical characteristics, and further, abrasion resistance and chemical stability. An object of the present invention is to provide a sputtering target capable of stably forming a protective film having excellent properties and the like by a DC sputtering method, and a method for manufacturing the same.

[0010]

[Means for Solving the Problems] The above object, SiC and TaC, TaN, from TaB _2, TaSi _2, the sintered body and at least one of Ta compound selected from the group consisting of TaH ₂ as a main component And a sputtering target. Such a sintered body is made of SiC powder with TaC, TaN, TaB ₂ , TaSi.
₂ , obtained by mixing powder of at least one Ta compound selected from the group consisting of ₂ and TaH ₂ and heating and sintering.

The sputtering target of the present invention and the method for producing the same will be described below in detail. The SiC powder used in the present invention is not particularly limited and may be a commonly used one, for example, one produced by a method such as a silica reduction method or an Acheson method is used.
The crystalline phase of SiC may be amorphous, α-type, β-type, or a mixed phase thereof. Further, the average particle size of this SiC powder is preferably 1 μm or less because the sinterability is improved.

The Ta compounds include TaC, TaN and Ta.
B _2, TaSi ₂ and TaH ₂ and the like. The average particle size of these Ta compound powders is preferably 10 μm or less. If the average particle size exceeds 10 μm, SiC
Mixing of the powder and the Ta compound powder may become non-uniform, resulting in a decrease in the density of the sintered body and an increase in the specific resistance value, which is not preferable.

A mixture is prepared by mixing SiC powder and one or more kinds of Ta compound powder. Here, when the SiC powder and the Ta compound powder are mixed, it is preferable that the compounding amount of the Ta compound powder is in the range of 10 to 50% by volume based on the total amount of the SiC powder and the Ta compound powder. That is, when the compounding amount of the Ta compound powder is less than 10% by volume, the effect of compounding the Ta compound powder is not sufficiently exerted, and when the obtained sintered body is used as a sputtering target, a film formed Alkali resistance becomes poor. In addition, if the amount of Ta compound in the sintered body is too small, the specific resistance value of the sintered body at room temperature becomes too high, which makes DC direct stapling difficult, and reactive sputtering with oxygen, nitrogen, etc. is performed. In that case, the amount of SiO ₂ having a high specific resistance value is increased, arc discharge easily occurs, and the process becomes unstable. Conversely, 50
When the content of Ta compound powder exceeds about 3% by volume, the film formed by using the obtained sintered body as a sputtering target has insufficient wear resistance and cannot be used as a protective film.

Further, if necessary, SiC and Ta compound may be added to carbon and boron as a sintering aid, or carbon and boron compound (eg, boron carbide B ₄ C, BN, B ₂ O ₃ etc.).
It is also possible to add one or more selected from the above.
The amount of sintering aid added is 100 total amount of SiC and Ta compounds.
It is preferable that 1 to 5 parts by weight of carbon and 0.5 to 5 parts by weight of one or more selected from boron and boron compounds are used with respect to parts by weight. If the amount of carbon is less than 1 part by weight, the addition amount is too small and the effect of densification is small. If the amount of carbon added exceeds 5 parts by weight, sintering is rather hindered. Further, if the addition amount of boron and the boron compound is less than 0.5 parts by weight, the effect of the addition is not sufficiently observed, and even if the addition amount exceeds 5 parts by weight, the density of the sintered body is almost leveled and the addition amount is Can't get enough effect.

A mixture of SiC powder, Ta compound powder and the like is shaped into a desired shape as a sputtering target, the obtained shaped body is heated in a temperature range of 1900 ° C. to 2400 ° C., and further sintered and sputtered. Get the target for. For molding the mixture powder, conventionally known methods such as a press molding method, an extrusion molding method, and an injection molding method can be adopted. In this case, it is preferable to add a molding binder, and as such a binder, polyvinyl alcohol, polyvinylpyrrolidone or the like can be used, and a dispersant such as stearate may be added if necessary.

For sintering, conventional methods such as atmospheric pressure sintering, atmospheric pressure sintering, hot press sintering, hot isostatic pressing (HIP) and the like can be adopted. The sintering temperature is also not particularly limited, but is 190
Heating temperatures below 0 ° C lead to insufficient sintering,
At a heating temperature higher than 0 ° C, SiC and Ta compounds are likely to evaporate, and grain growth may reduce the strength and toughness of the sintered body.
It is preferred to sinter in the temperature range of 0 ° C. Further, as the atmosphere during sintering, any of a vacuum atmosphere, an inert atmosphere and a reducing gas atmosphere can be adopted.

[0017]

The sputtering target of the present invention, having the above-mentioned structure, forms a Si-Ta-C-based protective film having excellent wear resistance, acid resistance and alkali resistance. Further, by performing reactive sputtering in an atmosphere of oxygen or nitrogen using this target, since a protective film having a low refractive index in the visible region and optical characteristics such as a low absorption coefficient is formed, for example, It is useful for forming a protective film such as heat ray shielding glass.

Further, this sputtering target contains a conductive Ta compound uniformly and has a specific resistance value of 1 Ω · cm or less at room temperature, so that it can be used in a DC sputtering apparatus having a simple structure. This is advantageous in terms of mass productivity and cost. Also, when reactive sputtering is performed using oxygen or nitrogen, abnormal arc discharge is unlikely to occur even if the surface of this target is oxidized or nitrided, stable DC sputtering becomes possible, and in terms of operability, etc. Be advantageous. This is an oxide of the Ta element (Ta) that imparts conductivity to the target.
It is considered that O, Ta ₂ O ₅ ) and nitride (TaN) have good conductivity, and therefore the specific resistance value of the target itself hardly changes from that before use.

[0019]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 β-type SiC powder having an average particle diameter of 0.3 μm and a BET specific surface area of 18 m ² / g was used as the SiC powder. This S
Add 3 parts of TaC powder with an average particle size of 1.05 μm to iC powder.
0% by volume was added, and 3 parts by weight of polyvinyl alcohol was added as a molding binder to 100 parts by weight of the total amount of SiC and TaC. The mixture was dispersed in methanol and further mixed by a ball mill for 12 hours.

The mixture is then dried and 160x
It was molded into 160 × 10 mm, and pressureless sintering was performed in an argon atmosphere under the conditions of a sintering temperature of 2100 ° C. and a sintering time of 90 minutes. When the density of the obtained sintered body was examined, it was 4.85 g.
Was / cm ² . The specific resistance value at room temperature was measured by the four-terminal method and found to be 0.08 Ω · cm. Next, the upper and lower sides of this sintered body were ground and bonded to a copper packing plate with indium to obtain a sputtering target.

As shown in FIG. 1, reactive sputtering was carried out in a DC bipolar sputtering device using the above sputtering target. That is, as shown in FIG. 1, a negative high voltage electrode 2 extends in a vacuum container 1, a sputtering target 4 is attached to the lower end thereof, a shield plate 3, a shutter 5, a gas introduction port 7 and a vacuum exhaust port 8.
At DC bipolar sputtering apparatus seemed to, Si-Ta _j -C on glass substrate 6 by reactive sputtering
to form a _k -N _m -O _n film. Sputtering is carried out in an atmosphere gas containing 20% by volume of oxygen and 80% by volume of nitrogen at a total flow rate of oxygen and nitrogen of 100 cc / min and a pressure of 0.03 to.
rr, power output 3 kW. As a result, pinholes or peeling was hardly observed in the _{Si-Ta j -C k -N m} -O n film formed on the substrate, was homogeneous.

When the wear resistance of this film was examined by a wear test using loose abrasive grains, good results were obtained. Further, the film was immersed in a 1N H ₂ SO ₄ solution for 24 hours,
Changes in optical properties such as absorption coefficient and reflectance of the film were investigated. As a result, almost no influence of acid on the film was recognized, and it was found that the film formed by the sputtering target according to the present invention has extremely excellent acid resistance. When the above test was carried out with a 1 N NaOH solution, it was found that the alkali resistance was similarly excellent.

Although the sputtering was carried out continuously for 8 hours, stable operation could be continued and the film formation rate was almost constant. On the other hand, when a DC sputtering target using a commercially available SiC reaction sintered body for comparison was used to perform DC sputtering under the same conditions, an abnormal arc discharge occurred 30 minutes after the start of operation. It became difficult to form a film. In addition, the obtained Si-
C _j -N _k -O _m membrane alkali resistance was poor.

Examples 2 to 8 The same SiC powder as in Example 1 was mixed with TaC, TaN and Ta.
Ta selected from the group consisting of B ₂ , TaSi ₂ , and TaH ₂ .
One or more compound powders are added in the mixing ratio shown in Table 1,
Further, if necessary, sintering aids such as C and B and C and B ₄ C were added at the compounding ratios shown in Table 1, and mixed, dried, molded and sintered under the same conditions as in Example 1. The sintered body density and the specific resistance value at room temperature of the obtained sintered body were examined in the same manner as in Example 1, and the results are shown in Table 1 together with the measurement results of Example 1. In Table 1, the amounts of the SiC powder and the Ta compound powder are volume% based on the total amount of both, and the amount of the sintering aid is parts by weight based on 100 parts by weight of the total amount of the SiC and Ta compound. From the results shown in Table 1, it was confirmed that the effect of the present invention can be sufficiently obtained even if the type and the compounding ratio of the Ta compound are changed, and the sintering aid is added.

[Table 1]

[0025]

As described above, the film formed by using the sputtering target of the present invention has excellent wear resistance, acid resistance, alkali resistance, etc., and also has a low refractive index and a low absorption in the visible region. Since it also has optical characteristics such as coefficient, it is useful as a highly durable protective film for heat ray shielding glass, optical disks, thermal heads and the like. Moreover, since the sputtering target of the present invention has excellent conductivity, it becomes possible to perform DC sputtering,
The apparatus can be simplified and the film formation speed can be improved. As a result, it is advantageous in terms of mass productivity and manufacturing cost. Further, even when used as a reactive sputtering target in an oxygen or nitrogen atmosphere, abnormal arc discharge hardly occurs as compared with the conventional Si or SiC target, so that continuous sputtering can be stably performed for a long time. Operability is also improved.

[0026]

[Brief description of drawings]

FIG. 1 shows an example of a DC bipolar sputtering device for performing sputtering using the sputtering target of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Negative high voltage electrode 3 ... Shield plate 4 ... Sputtering target of this invention 5 ... Shutter 6 ... Glass substrate 7 ... Gas introduction port 8 ... Vacuum exhaust port

Claims (4)

[Claims] 1. SiC and TaC, TaN, TaB ₂ , T
A sputtering target, comprising a sintered body containing, as a main component, at least one Ta compound selected from the group consisting of aSi ₂ and TaH ₂ . 2. The sputtering target according to claim 1, wherein the amount of the Ta compound is 10 to 50% by volume based on the total amount (volume) of SiC and the Ta compound. 3. TaC, TaN, Ta in SiC powder
A powder of at least one Ta compound selected from the group consisting of B ₂ , TaSi ₂ , and TaH ₂ is mixed, and this is heated and sintered to obtain a sintered body containing SiC and a Ta compound as main components. A method of manufacturing a sputtering target, comprising: 4. The method for producing a sputtering target according to claim 3, wherein the compounding amount of the Ta compound is 10 to 50% by volume based on the total amount (volume) of SiC and the Ta compound.