TW201734238A - Sputtering target - Google Patents

Abstract

The sputtering target of the present invention includes: Nb; Si; and inevitable impurities, and has an average relative density of 90% or more and a standard deviation of the relative density of 2.5 or less. The sputtering target may have an average area ratio of voids of 10% or less and a standard deviation of the area ratio of voids of 1.2 or less.

Description

Sputter target

The present invention relates to a sputtering target for forming an oxide film containing Nb and Si.

The application claims priority based on Japanese Patent Application No. 2015-247832, filed on Dec.

An antireflection film for use in an optical machine such as a camera lens is known, for example, a laminated film obtained by combining an intermediate refractive index material film with a high refractive index material film or a low refractive index material film. The intermediate refractive index material film used for the antireflection film is known to contain an oxide film of Nb and Si (hereinafter referred to as NbSiO film). The NbSiO film is generally formed by a reactive sputtering method using a sputtering target containing Nb and Si.

Patent Document 1 discloses that a target for forming an optical film having a desired refractive index by a reactive sputtering method is such that Si is a main component element and a predetermined mixing ratio with respect to the main component is made by Ta, a mixture of at least one element of Nb, Zr, Ti or Al or a compound thereof It is cured. Patent Document 1 describes that Si and Nb are used as raw materials to produce a target of 80 atm% for Si and 20 atm% for Nb, and a target of 70 atm% for Si and 30 atm% for Nb. Moreover, the target described in Patent Document 1 was observed, and as a result, the constituent structures were Si and Nb.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1]: JP-A-2004-68109

The NbSiO mode easily adjusts the refractive index by changing the ratio of the content of Nb to Si, and thus is excellent as a material of the intermediate refractive index material film.

At this time, the intermediate refractive index material film used for the antireflection material needs to have a small refractive index deviation in the film surface.

However, as described in Patent Document 1, it is difficult to form a NbSi film having a small variation in refractive index by using a reactive sputtering method which constitutes a target having Si and Nb in a structure. It is presumed that it is easy to form a pore between the Si phase and the Nb phase when a target in which Si and Nb are not alloyed is used, and a local abnormal discharge is likely to occur by the void.

In view of the foregoing, it is an object of the present invention to provide an effect of suppressing the occurrence of abnormal discharge and forming a refraction when a film is formed by a reactive sputtering method. A sputtering target in which a NbSiO film having a small deviation is formed.

In order to solve the above problems, the sputtering target of the present invention is characterized in that it contains Nb, Si and an unavoidable impurity, and the average value of the relative density is 90% or more, and the standard deviation of the relative density is 2.5 or less.

In the sputtering target thus constructed, the average value of the relative density is higher than 90%, and the standard deviation is less than 2.5%, that is, the number of pores in the target surface is small, so by reactive sputtering At the time of film formation, local abnormal discharge is unlikely to occur due to voids in the target, and the variation in refractive index in the plane in the NbSiO film after film formation can be made small. Further, the average value of the relative densities refers to the average value of the relative densities of the test pieces taken from the plurality of portions of the target surface. The average value of the relative densities is preferably an average value of the relative densities of the test pieces taken from five or more sites.

In the sputtering target of the present invention, the average area ratio of the voids is 10% or less, and the standard deviation is preferably 1.2 or less.

At this time, the average value of the area ratio of the pores is low, and the standard deviation is low, that is, the pores existing in the target surface are fine, so that it is not easy to cause local abnormal discharge due to the pores, and the film is formed after the film is formed. The deviation of the in-plane refractive index in the NbSiO film is small. The average value of the area ratio of the pores at this time means the average value of the area ratio of the pores measured by the plurality of portions in the target. The average value of the area ratio of the pores is preferably an average value of the area ratio of the pores of the test piece of the target surface 5 or more.

The sputtering target of the present invention is preferably the aforementioned unavoidable impurities The total amount of Cu, Ti, and Fe is 300 ppm by mass or less.

At this time, it is possible to suppress the occurrence of abnormal discharge due to the foreign matter containing the elements, and to make the variation in the refractive index in the plane of the NbSiO film after the film formation small. Further, since the total content of elements Cu, Ti, and Fe which affect the refractive index of the NbSiO film in the unavoidable impurities is limited, the difference in refractive index sought in the NbSiO film after film formation can be reduced, so that the refractive index can be further reduced. Deviation.

In the sputtering target of the present invention, the total content of Fe, Cr, and Ni in the unavoidable impurities is preferably 500 ppm by mass or less.

At this time, it is possible to suppress the occurrence of abnormal discharge due to the foreign matter containing the elements, and to reduce the variation in the in-plane refractive index of the NbSiO film after the film formation. Further, since Fe, Cr, and Ni are elements which increase the attenuation coefficient of the NbSiO film, by limiting the total content of the elements, the decay coefficient of the NbSiO film after film formation can be reduced, and the amount of light absorption can be reduced.

In the sputtering target of the present invention, the total content of Ti and Zr in the unavoidable impurities is preferably 500 ppm by mass or less.

At this time, the toughness (impact resistance) of the sputtering target can be improved.

Preferably, the sputtering target of the present invention has a Nb-Si compound phase formed of a compound of Nb and Si in the target surface.

At this time, since the single phase portion of Nb and Si is reduced and the field of the existing element is increased, the variation in the composition in the target surface can be reduced. Therefore, the NbSiO film formed by the reactive sputtering method using the sputtering target has a uniform composition and can reduce variation in refractive index in the plane.

In the above sputtering target, the aforementioned Nb-Si compound phase is flat The cut length is preferably 50 μm or less.

At this time, since the Nb-Si compound phase is finely crystallized, the target surface is fine, and it is difficult to form a large pore, so that local abnormal discharge is unlikely to occur due to voids.

The sputtering target of the present invention may have a Nb phase formed of Nb in the target surface, and the average cut length of the Nb phase is preferably 50 μm or less.

At this time, since the sputtering target contains a large amount of Nb, and the Nb phase is dispersed in a fine crystal form, the Nb content is relatively large, that is, the NbSiO film having a large refractive index can be uniformly formed into a film.

The sputtering target of the present invention may have a Si phase formed of Si in the target surface, and an average cut length of the Si phase is 50 μm or less.

At this time, since the sputtering target contains a large amount of Si and the Si phase is dispersed in a fine crystal form, the NbSiO film having a small refractive index can be formed into a film relatively uniformly.

In the sputtering target of the present invention, the Nb and the Si of the Si are preferably in the range of 5:95 to 80:20. That is, in the sputtering target of the present invention, when the number of moles of Nb is "Nb" and the number of moles of Si is "Si", it is preferable to satisfy the following formula.

50≦[Nb]/([Nb]+[Si])×100≦80

At this time, the field of the Nb-Si compound phase in the target surface is increased, and the composition uniformity in the target surface can be improved.

In the sputtering target of the present invention, the molar ratio of the Nb to the Si may be in the range of 50:50 to 80:20. That is, the sputtering target of the present invention is When the number of moles of Nb is [Nb], and the number of moles of Si is [Si], the following formula can be satisfied.

5≦[Nb]/([Nb]+[Si])×100≦80

At this time, the field of the Nb-Si compound phase formed in the target surface can be surely increased, and the composition uniformity in the target surface can be further improved, and the refractive index of the NbSiO film after film formation can be relatively increased.

According to the present invention, it is possible to provide a sputtering target in which a NbSiO film having a small variation in refractive index is formed by suppressing the occurrence of abnormal discharge during film formation by a reactive sputtering method.

Fig. 1 is a plan view showing a position at which a test piece for measuring a relative density of a sputtering target (rectangular plate) according to an embodiment of the present invention is measured.

Fig. 2 is a plan view showing a measurement range of a void area ratio of a sputtering target (rectangular plate) according to an embodiment of the present invention.

Fig. 3 is a plan view showing a measurement position of a refractive index of a NbSiO film obtained by forming a sputtering target film according to an embodiment of the present invention.

The sputtering target of one embodiment will be described in detail below.

The sputtering target of this embodiment can be used for reactive sputtering An NbSiO film such as an intermediate refractive index material film of an antireflection film used in an optical device such as a camera lens or the like is formed.

The sputtering target of the present embodiment is formed of Nb, Si, and an unavoidable impurity. More specifically, the sputtering target of the present embodiment may contain only Nb and Si and unavoidable impurities.

In the sputtering target of the present embodiment, the refractive index of the NbSiO film formed by the reactive sputtering method can be adjusted by appropriately setting the molar ratio of Nb to Si contained in the target.

Nb and Si Moore are preferably in the range of 5:95 to 80:20. That is, when the number of moles of Nb is [Nb] and the number of moles of Si is [Si], it is preferable to satisfy the following formula.

5≦[Nb]/([Nb]+[Si])×100≦80

In this case, the density of the target can be increased, and Nb and Si in the NbSiO film obtained by the high-density target film formation by the reactive sputtering method are not easily deflected, and the composition is easily made uniform. Therefore, the deviation of the refractive index of the film-forming NbSiO film can be reduced.

Further, Si has an effect of an adhesive, and thus excessive reduction in the Si content lowers the strength of the target. In addition, when Si is too much, the electrical conductivity is lowered, and static electricity is liable to occur. That is, when Si is excessively large, the charge in the target is easily concentrated, and abnormal discharge occurs when the film is formed by the reactive sputtering method.

The molar ratio of Nb to Si can range from 50:50 to 80:20. At this time, a NbSiO film having a relatively high refractive index can be formed into a film by a reactive sputtering method in a uniform composition.

The unavoidable impurities contained in the sputtering target of this embodiment Among them, Cu, Ti, and Fe are preferably contained in a total amount of 300 ppm by mass or less. Thereby, abnormal discharge occurs due to the presence of foreign matter containing the elements on the target surface of the sputtering target, and the refractive index deviation in the surface of the NbSiO film after film formation is small. In addition, Cu, Ti, and Fe are elements which affect the refractive index of the NbSiO film, and by limiting the total content of these elements to 300 ppm by mass or less, variations in the refractive index of the NbSiO film after film formation can be reduced.

In addition, the total content of Fe, Cr, and Ni in the unavoidable impurities contained in the sputtering target of the present embodiment is preferably 500 ppm by mass or less. Thereby, it is possible to suppress the occurrence of abnormal discharge by the foreign matter containing the elements on the target surface of the sputtering target, and to reduce the refractive index deviation in the plane of the NbSiO film after the film formation. Further, since Fe, Cr, and Ni are elements which increase the attenuation coefficient of the NbSiO film, by limiting the total content of the elements, the attenuation coefficient of the NbSiO film after film formation can be lowered, and the amount of light absorption can be reduced.

In addition, the total content of Ti and Zr in the unavoidable impurities contained in the sputtering target of the present embodiment is preferably 500 ppm by mass or less. Thereby, the toughness (impact resistance) of the sputtering target can be improved.

Elements such as Cu, Ti, Fe, Cr, and Ni are impurities which are easily mixed when a sputtering target is produced. Therefore, care must be taken when manufacturing the sputtering target of this embodiment to prevent the incorporation of such elements. Further, in the sputtering target of the present embodiment, the total content of Cu, Ti, and Fe and the total content of Fe, Cr, and Ni may each be 20 ppm by mass or more. When a sputtering target having a total content of Cu, Ti, and Fe and a total content of Fe, Cr, and Ni of less than 20 ppm by mass is produced, it is necessary to strictly limit the incorporation of impurities in the manufacturing process, or it is necessary to use a high-purity raw material, thereby improving manufacturing. Costs and so on are not conducive to industriality. In addition to the target The total content of the unavoidable impurities (the elements other than the Nb and the Si) is preferably 1000 ppm by mass or less, and more preferably 20 ppm by mass or more from the viewpoint of the above-mentioned production cost and the like.

In the sputtering target of the present embodiment, the average value of the relative density of the test piece taken from the plurality of portions of the target surface is 90% or more, and the standard deviation of the relative density is 2.5 or less. When the relative density is less than 90% on average, abnormal discharge is likely to occur when the film is formed by reactive sputtering, and the film formation speed is slowed down. Further, when the standard deviation of the relative density exceeds 2.5, the variation in the refractive index of the NbSiO film after film formation by the reactive sputtering method is increased. The average value of the relative density is preferably 95% or more. Further, the average value of the relative density is preferably 133% or less, and the standard deviation of the relative density is preferably 0 or more.

In the present embodiment, when the sputtering target is a rectangular flat plate (length 126 mm × width 178 mm × thickness 6 mm), as shown in FIG. 1 , the intersection position (11) of the center line in the longitudinal direction and the center line in the width direction is centered. A test piece having a length of 30 mm in the longitudinal direction and a length of 30 mm in the width direction was cut out, and a test piece having a length of 30 mm in the longitudinal direction and a length of 30 mm in the width direction was cut out from the four corner portions (12) to (15). The relative density was determined with respect to the five test pieces (length 30 mm × width 30 mm × thickness 6 mm), and the average value and standard deviation were calculated. Further, the relative density was calculated from the density (measured density) of the test piece and the theoretical density of the sputtering target by the following formula.

Relative density = measured density / theoretical density × 100

The measured density of the test piece was calculated from the test piece size measured by the cursor and the weight of the test piece measured by an electronic balance.

The theoretical density of the sputtering target is such that the molar ratio of Nb when the total number of Nb and Si contained in the target is 100 mole is x and the molar ratio of Si is (100-x), and secondly The atomic weight of _Nb is M _Nb and the atomic weight of _Si is M _Si . The mass W _{Nb of Nb} and the mass W _{Si of Si are} calculated by the following formula.

W _Nb = x × M _Nb / 100

W _Si = (100-x) × M _Si /100

Further, the volume V _{Nb of Nb} and the volume V _{Si of Si are} calculated by the following equation, with the density of _Nb being ρ _Nb and the density of _Si being ρ _Si .

V _Nb = x × M _Nb / (100 × ρ _Nb )

V _Si = (100-x) × M _Si / (100 × ρ _Si )

Thereafter, the theoretical density ρ _{T of the} sputtering target is calculated from W _Nb , W _Si , V _Nb , and V _Si by the following formula.

ρ _T =(W _Nb +W _Si )/(V _Nb +V _Si )

In the sputtering target of the present embodiment, the average value of the area ratio of the pores in the plurality of portions of the target surface is 10% or less, and the standard deviation of the pore area ratio is 1.2 or less. Further, the average value of the area ratio of the voids is preferably 0% or more, and the standard deviation of the area ratio of the voids is preferably 0 or more.

Further, in the present embodiment, when the sputtering target is a rectangular flat plate (length 126 mm × width 178 mm × thickness 6 mm), as shown in Fig. 2, the intersection position (21) and 4 of the center line in the longitudinal direction and the center line in the width direction are as shown in Fig. 2 . The corner portions are each measured at a position of 10 mm in the longitudinal direction and 10 mm in the width direction (22) to (25), and the area ratio of all the existing holes in the range of 1 mm in the longitudinal direction and 2 mm in the width direction is measured, and the area ratio is calculated. Average and standard deviation. In addition, when the area ratio of the pores is 100% of the measured target surface range (2 mm ² ), the percentage of the area of the pores present in the target surface area and the area ratio of the pores are by scanning electron microscope. The secondary electron image of the target surface captured by (SEM) was obtained by using an image solution program.

The sputtering target of the present embodiment has a Nb-Si compound phase formed of a compound containing Nb and Si in the target surface. By forming the Nb-Si compound phase by Nb and Si, the single phase portion of Nb and Si can be reduced, and the field in which the two elements are present is increased, so that the variation in the composition in the target surface can be reduced. Since the variation in the composition in the target surface is small, the composition of the NbSiO film after film formation by the reactive sputtering method can be made uniform, and the variation in the refractive index in the plane can be reduced. Further, the area ratio of the Nb-Si compound phase in the target surface is preferably 1% or more, more preferably 12% or more and 97% or less.

The Nb-Si compound phase is preferably an average cut length of 50 μm or less. When the average cutting length of the Nb-Si compound phase is 50 μm or less, the target surface can be made fine and large pores are not easily formed. Therefore, when the film is formed by reactive sputtering, localization is not easily caused by voids. Abnormal discharge. Further, when the average cut length of the Nb-Si compound phase exceeds 50 μm, the number of abnormal discharges is increased, and the variation in the in-plane refractive index of the NbSiO film after the film formation by the reactive sputtering method is large. The average cut length of the Nb-Si compound phase is more preferably 0.5 μm or more.

The average cut length of the Nb-Si compound phase was the same as the area ratio of the above-mentioned measured pores, and was measured from the measurement results of the secondary electron image and element distribution of the target surface to be photographed. The diagonal is first pulled out relative to the secondary electron image. Secondly, after the position of the Nb-Si compound phase photographed by the secondary electron image is located by the elemental analysis result, the length of the diagonal passing through the Nb-Si compound phase and the number of Nb-Si compound phases passing through the diagonal are determined by an image analysis program. . Then with The value obtained by dividing the total length of the Nb-Si compound phase by the number of passes is taken as the cut length of the Nb-Si compound phase. The cut length was obtained by measuring the (21) to (25) 5 portions shown in Fig. 2 and using the average value as the average cut length.

The sputtering target of the present embodiment may have a Nb phase formed of Nb in the target surface. At this time, the average cut length of the Nb phase is preferably 50 μm or less. The average cut length of the Nb phase is more preferably 0.5 μm or more.

The average cut length of the Nb phase can be determined by the same method as the above Nb-Si compound.

The sputtering target of the present embodiment may have a Si phase formed of Si in the target surface. The average cut length of the Si phase at this time is preferably 50 μm or less. The average cut length of the Si phase is more preferably 0.5 μm or more.

The average cut length of the Si phase can be measured by the same method as the above Nb-Si compound.

The sputtering target of the present embodiment may have a Nb-Si compound phase alone or have two or more phases. It is preferred to have two phases, and it is preferable to combine the Nb-Si compound phase with the Nb phase or the Nb-Si compound phase and the Si phase by reducing the composition variation.

Next, a method of manufacturing the sputtering target of the present embodiment will be described.

The sputtering target of the present embodiment can be obtained, for example, by sintering a mixed powder of a mixed monomer Nb powder and an Si powder, and then processing the obtained sintered body. The average particle diameter of the Nb powder is preferably in the range of 20 μm or more and 100 μm or less. The average particle diameter of the Si powder is preferably 50 μm or more and 150 μm. The scope below.

When mixing the Nb powder and the Si powder, it is preferred to use a mixing device having a pulverizing function. A mixing device having a pulverizing function can be, for example, a ball mill. The pulverizing medium of the ball mill is preferably a ceramic ball made of ZrO ₂ or the like. By using a mixing device having a pulverizing function, the Nb powder and the Si powder can be mixed into a uniform composition while making the particle sizes uniform. By making the Nb powder and the Si powder have the same particle size, the density at the time of sintering the mixed powder can be increased, and the average value of the relative density can be increased to obtain a fine sintered body having a small standard deviation.

When the Nb powder and the Si powder are mixed, in order not to oxidize the surface of the Nb powder and the Si powder, it is preferably carried out in an inert gas atmosphere, in a vacuum or in a reducing atmosphere.

In the pulverization, it is preferred to carry out the D50 of the obtained mixed powder (the particle size at which the cumulative frequency of the particle size distribution is 50%) is 50 μm or less. When the D50 of the powder mixture is large, the average cut length of the Nb-Si compound phase, the Nb phase, and the Si phase of the obtained target is too long. The D50 of the mixed powder is preferably 30 μm or less. When the mixing device uses a ball mill, the amount of the sphere filled in the bottle (mixing container) is 1 L with respect to the volume of the bottle, and the weight of the sphere is preferably in the range of 0.8 to 1.5 kg. Further, the pulverization time (mixing time) is preferably 3 hours or longer.

In the case of sintering the mixed powder, it is preferred to carry out the heating in a state in which the mixed powder is filled in a mold having a certain shape. The sintering of the mixed powder is preferably carried out in a vacuum, in an inert gas atmosphere or in a reducing environment. The heating temperature is preferably 1200 ° C or higher. When the heating temperature is lower than 1200 ° C, sintering is insufficient and it is difficult to form a sintered body having a relative density of more than 90%. As a method of sintering the mixed powder, a pressure sintering method such as a hot press method or a HIP method (thermally isotropic pressurized sintered body) can be used. When the hot press method is used, the applied pressure is preferably 150 kg/cm ² or more. When the pressure is less than 150 kg/cm ² , the applied pressure will be insufficient, and it is difficult to form a sintered body having a relative density of more than 90%.

The sintered body obtained by sintering the mixed powder can be subjected to a cutting process or a grinding process to obtain a sputtering target having a certain shape.

The sputtering target thus obtained can be used by bonding to a driving disk formed of copper or SUS (stainless steel) or other metal (for example, Mo, Ti) by welding.

Next, a film formation method using the NbSiO film of the sputtering target of the present embodiment will be described.

The sputtering target of this embodiment can be formed by a reactive sputtering method in the presence of oxygen to obtain a NbSiO film.

First, the sputtering target and the substrate of the present embodiment are fixed in a sleeve of a sputtering apparatus. Next, the inside of the casing was depressurized, and a mixed gas of argon and oxygen was introduced, and an NbSiO film was formed on the substrate by electric power.

The average value of the refractive index of the NbSiO film obtained by using the sputtering target of the present embodiment varies depending on the ratio of Nb to Si contained in the NbSiO film, and is generally in the range of 1.4 or more and 2.3 or less. The standard deviation of the refractive index of the NbSiO film is generally 0.05 or less, preferably 0.02 or less. Further, the average value of the attenuation coefficient of the NbSiO film is generally in the range of 1 × 10 ^-4 or more and 2 × 10 ^-3 or less. The standard deviation of the decay coefficient of the NbSiO film is generally 1 × 10 ^-3 or less.

In this case, when the NbSiO film of the present embodiment is formed on a rectangular glass substrate (length 100 mm × width 100 mm), as shown in Fig. 3, the center position (31) and the x4 angles in the longitudinal direction and the width direction are respectively The refractive index and the coefficient of decay were measured at positions (32) to (35) 5 in the longitudinal direction of 10 mm and 10 mm in the width direction, and the average value and standard deviation were calculated. Further, the refractive index and the coefficient of decay are obtained by the envelope method. That is, after the reflectance and the light transmittance of the NbSiO film were measured using a spectrophotometer, the reflectance and the light transmittance were calculated. The measurement wavelength of the reflectance and the light transmittance was 550 nm.

The embodiments of the present invention have been described above, but the present invention is not limited thereto, and can be appropriately modified without departing from the scope of the technical idea of the invention.

For example, the sputtering target shown in FIGS. 1 and 2 is a rectangular flat plate, but the shape of the sputtering target is not particularly limited, and may be a circular plate shape or a cylindrical shape. Moreover, when it is a circular-plate shape or a cylindrical shape, the average value of the relative density of a sputtering target, the standard deviation, the average value of the area ratio of the pores, and the standard deviation of it, and it is preferable to measure the position of 5 or more.

[Examples]

[Making a sputtering target]

(Inventive Examples 1 to 8 and Comparative Examples 1 to 4)

Nb powder (purity: 3N, average particle diameter: 30 μm) and Si powder (purity: 3N, average particle diameter: 100 μm) were prepared as raw material powders, and each was weighed so that the addition ratio (mole ratio) was as shown in Table 1 below. Shown.

The raw material powder weighed is put into a bottle of a ball mill (material: polyethylene). A sphere (material: ZrO ₂ , particle diameter: 5 nm) was filled in the bottle according to the filling amount shown in the following Table 1, and the bottle was replaced with Ar gas, and the bottle mouth was covered. Next, the bottle body was placed in a ball mill, and pulverized and mixed at a rotation speed of 104 rpm and a mixing time shown in Table 1 below to obtain a mixed powder.

The average particle diameter of the obtained mixed powder was measured by the following method. The results are shown in Table 1.

<Method for Measuring Average Particle Diameter of Mixed Powder>

An appropriate amount of the mixed powder was added to an aqueous solution having a sodium hexametaphosphate concentration of 0.2% to prepare a dispersion. The particle size distribution of the mixed powder in the dispersion was measured using a particle size distribution measuring apparatus (Microtrac MT3000 manufactured by Nikkiso Co., Ltd.) to determine the average particle diameter.

The sintering was carried out for 2 hours under the conditions of the sintering temperature and the sintering pressure shown in Table 1 below to obtain a sintered body of 150 mm × 200 mm × 7 mm thick. The obtained sintered body was processed to prepare a sputtering target of 126 mm × 178 mm × 6 mm thick.

(Example 9 of the present invention)

A sputtering target was produced in the same manner as in Inventive Example 2 except that the raw material powder collected was pulverized and mixed for 3.0 hours using a vibration mixer.

(Inventive Example 10)

A sputtering target was produced in the same manner as in Inventive Example 2, except that 100 mass ppm of Fe powder, Cu powder, and Ti powder were added to each of the raw material powders (Nb powder and Si powder) weighed, and then the mixed powder was pulverized using a ball mill.

(Example 11 of the present invention)

A sputter target was produced in the same manner as in the inventive example 2 except that 100 mass ppm of Fe powder, Cr powder, and Ni powder were added to each of the raw material powders (Nb powder and Si powder) weighed, and then the mixture was pulverized and mixed using a ball mill. .

(Inventive Example 12)

A sputtering target was produced in the same manner as in Inventive Example 2 except that 200 mass ppm of Ti powder and Zr powder were added to each of the raw material powders (Nb powder and Si powder) which were weighed, and then the mixture was pulverized and mixed using a ball mill.

(Example 13 of the present invention)

A sputtering target was produced in the same manner as in Inventive Example 2 except that 250 mass ppm of Ti powder and Zr powder were added to each of the raw material powders (Nb powder and Si powder) which were weighed, and then the mixture was pulverized and mixed using a ball mill.

(Inventive Example 14)

Nb powder (purity: 5N, average particle diameter: 30 μm) and Si powder (purity: 5N, average particle diameter: 100) prepared for use as a raw material powder The sputter target was produced in the same manner as in the inventive example 2 except that the addition ratio (mole ratio) was as shown in the following Table 1.

(Comparative Example 5)

In addition to the NbSi ₂ powder (purity: 3N, average particle diameter: 10 μm) used as a raw material powder and Si powder (purity: 3N, average particle diameter: 100 μm), the molar ratio is 50:50, and the present invention In the same manner as in Example 1, a sputtering target was produced.

[Evaluating Sputter Target]

The composition of the sputtering target obtained in the above Examples 1 to 11 and Comparative Examples 1 to 5 (the molar ratio of Nb to Si, the total content of Fe, Ti, and Cu, and the total of Fe, Cr, and Ni) were measured by the following methods. Content, total content of Ti, Zr), average value of relative density and its standard deviation, average of porosity and its standard deviation, composition of structure and average cut length of Nb-Si compound phase and Nb phase or Si phase, dimension After the measurement, the crack from the indentation, the film formation speed and the abnormal discharge number when the film is formed by the reactive sputtering target method, and the average value of the refractive index and the decay coefficient of the NbSiO film obtained by the sputtering method Deviation from its standard. The results are shown in Table 2 and Table 3.

(composition)

(1) Mob ratio of Nb and Si

From the addition ratio of the Nb powder to the Si powder used as the raw material powder, the molar ratio when the total amount of Nb and Si was 100 was calculated.

(2) Total content of Fe and Cu, total content of Fe, Cr, Ni, total content of Ti, Zr

The quantitative analysis of Fe, Ti, Cu, Cr, Ni, and Zr was carried out by ICP luminescence analysis, and the sample used was a mixture of the raw material powder before mixing and the target powder.

(the average of the relative density and its standard deviation)

Each of the parts (11) to (15) shown in Fig. 1 was cut out to have a test piece of 30 mm × 30 mm × 6 mm. The relative density of the cut test pieces was determined by the above method, and the average value and the standard deviation were calculated.

(the average of the area ratio of the holes and its standard deviation)

After taking a secondary electron image of a range of 1 mm × 2 mm in the five portions (21) to (25) shown in Fig. 2, the area ratio of the voids was obtained by the above method, and the average value and the standard deviation were calculated.

(average cut length of Nb-Si compound phase and Nb phase or Si phase)

After taking a secondary electron image in the range of 1 mm × 2 mm in the 5 portions (21) to (25) shown in Fig. 2, the average cut length of the Nb-Si compound phase and the Nb phase or the Si phase is obtained by the above method. Calculate the average value.

(Cracks from indentation after Vickers measurement)

Using a Vickers hardness tester (MVK-G13) with a SPEED dial: 3 (10 μm/sec) and a load of 100 g, the positive square pyramid of diamond is driven into the 5 (21) to (25) shown in Fig. 2. Part. The number of indentations in which the crack occurred was measured by the indentation of the positive four-corner pressure cone of the five parts. After the Vickers measurement, the crack from the indentation has higher toughness (impact resistance).

(film formation speed)

After welding the target to the copper transmission disc, the post-weld evaluation target is mounted in the sleeve of the magnetron sputtering device, and after exhausting to 1×10 ^-4 Pa, the air pressure is 0.3 Pa, and the power is input: pulse The NbSiO film was formed on the substrate under the conditions of DC300W (cycle number: 50 kHz), target-substrate distance: 70 mm, and Ar/O ₂ ratio: 1.5. The film formation rate was measured by film formation at 500 sec under the above-described sputtering conditions, and the film thickness of the NbSiO film after film formation was measured using a step measurement machine, and the film thickness was measured by sputtering time (500 sec).

(abnormal discharge times)

Continuous discharge was performed for 1 hour under the same conditions as the above-described measurement film formation rate, and the number of abnormal discharges during discharge was measured.

(the average of the refractive index and the decay coefficient and its standard deviation)

A glass substrate of 100 mm × 100 mm was mounted in a magnetron sputtering apparatus, and a NbSiO film having a thickness of 450 nm was formed on the glass substrate under the same conditions as the above-described measurement deposition rate.

The refractive index and the decay coefficient of the five portions (31) to (35) shown in Fig. 3 were measured by the above method, and the average value and the standard deviation were calculated. Further, a spectrophotometer (U-4100, manufactured by Japan Hi-Tech Co., Ltd.) was used.

As is apparent from the results of Table 2, the sputtering target for Comparative Examples 1 to 5 which is the average value of the relative density and the standard deviation thereof is outside the range of the present invention, and the number of abnormal discharges at the time of film formation by the reactive sputtering method is large. In particular, the NbSiO film formed by using the sputtering target of Comparative Examples 1 and 2 having an average cut length of 60 mm or more of the Nb-Si compound phase and the Nb phase is a standard deviation of the in-plane refractive index. The difference has a large value.

The average value of the relative relative density and the standard deviation thereof are the sputtering targets of the inventive examples 1 to 14 within the scope of the present invention, and the number of abnormal discharges at the time of film formation by the reactive sputtering method is small, and the film formation speed is small. Faster. Further, the NbSiO film formed by using the sputtering target of Examples 1 to 5 of the present invention can significantly reduce the standard deviation of the in-plane refractive index. Further, the NbSiO film formed by sputtering targets of Examples 1 to 8 and 10 to 14 of the present invention in which the total content of Fe, Cr, and Ni is 500 ppm by mass or less is such that the coefficient of decay can be remarkably reduced. In addition, the sputtering targets of Examples 1 to 12 and 14 of the present invention in which the total content of Ti and Zr is 500 ppm by mass or less are such that cracks are not easily generated by the indentation of the Vickers hardness tester, and toughness (impact resistance) can be improved. Destructive).

[Industry use possibility]

The sputtering target of the present invention can suppress the occurrence of abnormal discharge during film formation by the reactive sputtering method, and form a film of a NbSiO film (a film containing an oxide of Nb and Si) having a small variation in refractive index.

Claims (11)

A sputtering target characterized by containing Nb and Si and an unavoidable impurity, and an average value of relative density is 90% or more, and a standard deviation of the relative density is 2.5 or less. The sputtering target of claim 1, wherein an average value of the area ratio of the pores is 10% or less, and a standard deviation of the area ratio of the pores is 1.2 or less. The sputtering target according to claim 1, wherein the total content of Cu, Ti, and Fe in the unavoidable impurities is 300 ppm by mass or less. The sputtering target according to claim 1, wherein the total content of Fe, Cr, and Ni in the unavoidable impurities is 500 ppm by mass or less. The sputtering target according to claim 1, wherein the total content of Ti and Zr in the unavoidable impurities is 500 ppm by mass or less. The sputtering target according to any one of claims 1 to 5, wherein the target surface has a Nb-Si compound phase formed of a compound of Nb and Si. The sputtering target according to claim 6, wherein the Nb-Si compound phase has an average cut length of 50 μm or less. The sputtering target according to claim 6 or 7, wherein the target surface further has a Nb phase formed of Nb, and the Nb phase has an average cut length of 50 μm or less. The sputtering target according to claim 6 or 7, wherein the target surface further has a Si phase formed of Si, and the Si phase has an average cut length of 50 μm or less. The sputtering target according to any one of claims 1 to 9, wherein the aforementioned Nb The molar ratio to the aforementioned Si is in the range of 5:95 to 80:20. The sputtering target of claim 10, wherein the molar ratio of the aforementioned Nb to the aforementioned Si is in the range of 50:50 to 80:20.