JP2015183269A - Sputtering target for formation of solid electrolyte thin film and thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target for allowing stably depositing a homogeneous thin film of solid electrolyte material for a lithium ion secondary battery by sputtering.SOLUTION: Raw material powders for Li source and raw material powders for B source are weighed such that Li/B atomic ratio is 2.9 - 3.1. The raw material powders are sintered at 650°C - 700°C. A produced sintered body is processed to a target shape to provide a sputtering target having a composition of LiBO(x and y are in atomic%, and satisfy 2.9≤x/y≤3.1). The sputtering target includes Al:less than 100 wtppm, Ca: less than 500 wtppm, Fe: less than 10 wtppm, Na: less than 500 wtppm, Ni:less than 10 wtppm, Si: less than 150 wtppm, Cu: less than 10 wtppm, and K: less than 150 wtppm. The total amount of the metals is less than 100 wtppm.

Description

  The present invention relates to a solid electrolyte material for a lithium ion secondary battery.

Lithium ion secondary batteries are attracting attention as high-power and large-capacity secondary batteries, and various researches and developments are actively conducted. However, the electrodes and electrolytes that make up lithium-ion secondary batteries are energy efficient. Many issues remain to be studied from the viewpoints of density, charge / discharge characteristics, manufacturing process, material cost, and the like. In particular, in recent years, research and development of solid electrolytes that replace liquid electrolytes that have had the problem of liquid leakage have been actively conducted.

As the solid electrolyte material, Patent Document 1 discloses a lithium ion conductive solid electrolyte material made of Li _{2 + x} C _{1-x + y} B _x O _{3 + 2y} , and Patent Document 2 discloses LiaPbMcOdNe (M is Si , B, Ge, Al, C, Ga, S) are disclosed. Patent Document 3 discloses a lithium ion conductive solid electrolyte containing lithium (Li), boron (B), sulfur (S), and oxygen (O) as constituent components. Furthermore, Patent Document 4 discloses a solid electrolyte represented by Li _x —B—O _y —N _z .

  As described above, various proposals have been made for solid electrolyte materials in order to improve the characteristics of lithium secondary batteries. However, both are intended to improve the characteristics of the solid electrolyte thin film, and the production of the thin film is limited to the disclosure that it can be produced by sputtering the target. Nothing is shown.

JP-A-5-54712 JP 2005-038843 A JP 2006-222063 A Special table 2011-521421 gazette

  An object of the present invention is to provide a sputtering target for forming a solid electrolyte of a lithium ion secondary battery, and in particular, a sputtering target capable of stably forming a thin film of a homogeneous solid electrolyte by sputtering. It is an issue to provide.

1) Li ₃ BO characterized by comprising a composition represented by the formula: Li _x B _y O ₃ (wherein x and y are atomic% and satisfy 2.9 ≦ x / y ≦ 3.1) ₃ sputtering target.
2) Al content less than 100wtppm, Ca content less than 500wtppm, Fe content less than 10wtppm, Na content less than 500wtppm, Ni content less than 10wtppm, Si content less than 150wtppm, Cu content less than 10wtppm The Li content is a Li ₃ BO ₃ sputtering target as described in 1) above, wherein the K content is less than 150 wtppm.
3) The Li ₃ BO ₃ sputtering target according to 2) above, wherein the total content of Al, Ca, Fe, Na, Ni, Si, Cu, and K is less than 100 wtppm.
4) The Li ₃ BO ₃ sputtering target according to 3) above, wherein each content of Al, Ca, Fe, Na, Ni, Si, Cu, and K is less than 20 wtppm.
5) The Li ₃ BO ₃ sputtering target according to 1) to 4) above, wherein the relative density is 90% or more.
6) The Li ₃ BO ₃ sputtering target according to any one of 1) to 5) above, wherein coarse particles having a particle diameter of 2 mm or more are not present.
7) Li ₃ BO ₃ above 1, characterized in that it consists of a single phase) ~6) Li ₃ BO ₃ sputtering target according to any one of.
8) The Li ₃ BO ₃ sputtering target according to any one of 1) to 7) above, wherein black spots having a diameter of 2 mm or more do not exist.
9) After weighing the raw material powder to be the Li source and the raw material powder to be the B source so that the atomic ratio of Li / B is 2.9 to 3.1, the raw material powder is baked at 650 ° C. to 700 ° C. A method for producing Li ₃ BO ₃ , wherein
10) The raw material powder as the Li source and the raw material powder as the B source are weighed so that the atomic ratio of Li / B is 2.9 to 3.1, and then the raw material powder is heated at 700 to 1000 ° C. dissolved by synthesizing the Li ₃ BO _3, after grinding the Li ₃ BO ₃ was obtained, the production method of the Li ₃ BO _3, characterized in that sintering at 650 ° C. to 700 ° C..
11) The raw material powder as the Li source and the raw material powder as the B source are weighed and mixed so that the atomic ratio of Li / B is 2.9 to 3.1, and then the mixed powder is below the melting point of the raw material powder. After firing the sintered body, the sintered body was pulverized and then sintered at 500 ° C. to 700 ° C. to synthesize Li ₃ BO ₃ , and the resulting Li ₃ BO ₃ was pulverized and then sintered at 650 ° C. to 700 ° C. A method for producing Li ₃ BO ₃ , characterized in that:
12) A method for producing a Li ₃ BO ₃ sputtering target, wherein Li ₃ BO ₃ produced by the production method according to any one of 9) to 11) above is processed into a target shape.
13) 1) above 8) The solid electrolyte film formed by using Li ₃ BO ₃ sputtering target according to any one of.

The sputtering target for forming a solid electrolyte thin film of the present invention has an effect that an abnormal discharge (arcing) is hardly generated at the time of film formation and can be formed with a homogeneous solid electrolyte thin film. Moreover, the lithium ion secondary battery using such a solid electrolyte thin film has the effect that the stable electroconductivity and charging / discharging characteristic are acquired.

The sputtering target of the present invention have the formula: (wherein, x, y are atomic%) Li _x B _y O ₃ in, and satisfies a 2.9 ≦ x / y ≦ 3.1. When x / y is less than 2.9, a different phase such as LiBO ₂ phase is generated in addition to the Li ₃ BO ₃ phase, or abnormal grain growth occurs, which is not preferable, and x / y is 3.1. Exceeding this is not preferable because LiOH and the like remain and deliquescence increases. Further, when the Li atom% is small, black spots may be generated on the surface of the sputtering target. Therefore, it is preferable that the Li atom% is large in the numerical range.

  In the sputtering target of the present invention, as impurities, Al content: less than 100 wtppm, Ca content: less than 500 wtppm, Fe content: less than 10 wtppm, Na content: less than 500 wtppm, Ni content: less than 10 wtppm, Si content: 150 wtppm Less than, Cu content: less than 10 wtppm, K content: less than 150 wtppm. Since these metal impurities tend to lower the electrical conductivity of the solid electrolyte and inhibit the movement of Li ions, it is possible to obtain excellent characteristics as a solid electrolyte material by reducing these impurities. The above impurities preferably have a total content of less than 100 wtppm, and more preferably have a respective content of less than 20 wtppm.

The sputtering target of the present invention has a relative density of 90% or more (theoretical density is 2.14 g / cm ³ ). Thus, by densifying the sputtering target, stable sputtering can be performed, and a thin film having excellent uniformity can be formed. In addition, the sputtering target of the present invention is characterized in that there are no coarse particles having a particle diameter of 2 mm or more, and there are no black spots (a state in which black patterns are sparsely scattered) having a diameter of 2 mm or more. Such coarse grains and black spots are not preferable because they cause arcing (abnormal discharge) and generate particles during sputtering.

The sputtering target of the present invention can be produced by the following method.
First, a powder serving as a Li source such as lithium carbonate, anhydrous lithium hydroxide, lithium hydroxide monohydrate, and lithium oxide, and a powder serving as a B source such as boron, boron oxide, and boric acid are prepared. And any 1 or more types of powder used as Li source and 1 or more types of powder used as B source are weighed so that the atomic ratio of Li / B may be 2.9-3.1.
Next, these powders are mixed. For mixing raw materials, dry mixing is preferably used, but wet mixing using a medium such as water or alcohol may be used. Moreover, it is preferable to mix sufficiently so that the powder used as a Li source and the powder used as a Bi source may each disperse | distribute uniformly.

The raw material powder weighed and mixed as described above is synthesized by heating. As a synthesis method, any method of dissolution or baking may be used. In the case of dissolution, Li ₃ BO ₃ can be synthesized in a liquid phase by heating at a temperature of 700 ° C. or higher. About the upper limit of temperature, it is preferable to set it as 1000 degrees C or less on account of an apparatus.
On the other hand, in the case of firing that is a solid-phase reaction, an unreacted part is likely to remain, so that it is necessary not to leave an unreacted part. Boric acid, lithium carbonate, lithium hydroxide, and the like have a low melting point and melt in the course of firing, so that the reaction is likely to proceed locally and compositional deviation occurs. Therefore, after firing at a temperature lower than the melting point of each raw material powder in advance and partially synthesizing it, this is dry pulverized, and then the melting point of each raw material powder (preferably 500 ° C. or higher), Li ₃ By performing firing at 700 ° C. or lower, which is directly below the melting point of BO ₃ , the compositional deviation is eliminated.

The above synthesis process can be performed more than once as necessary to perform more uniform synthesis. On the other hand, in the case of dissolution, the necessity is low, but in order not to leave unreacted components, it may be better to perform dissolution several times. In the case of dissolution, there are problems such as foaming due to gas generation and adhesion to a container, but in the case of firing, there are few problems associated with the generation of such gas.
There is no particular limitation on the atmosphere in the synthesis by firing or dissolution, and it can be carried out in any atmosphere such as vacuum, reduced pressure, inert atmosphere, air, and oxidizing atmosphere. In the air, which can be carried out in a simple furnace, is particularly desirable.
With regard to the firing temperature described above, the reaction proceeds even at a low temperature of about 400 ° C., but since it takes time to complete the reaction, it is desirable to perform the synthesis at a higher temperature within the above range. Moreover, you may implement by multiple times of heat processing.

Alternatively, a sintered body of Li ₃ BO ₃ can be obtained by press-molding the mixed powder without passing through the synthesis step and then sintering. In this case, other than the combination of lithium oxide and boron oxide, H ₂ O and CO ₂ may be desorbed and the relative density may be lowered. Further, in the case of a combination of lithium oxide and boron oxide, handling a large amount of powder containing lithium oxide in the mixing and molding process is a safety problem, so it must be handled with care.

The Li ₃ BO ₃ obtained as described above is pulverized by a dry method to produce a powder. Thereafter, the pulverized powder is sintered by hot pressing or the like. There is no particular limitation on the sintering method, but in the method of sintering after pressure molding, water or a binder may be used to improve the moldability, and the synthesized Li ₃ BO ₃ is rich in hygroscopicity and absorbs moisture. Since this is a material to be avoided, special care must be taken when molding such a method.
Hot pressing is advantageous in that a sintered body having a predetermined shape can be produced. In addition, there is an advantage that a high-density sintered body can be obtained at a relatively low temperature, and a high-strength target can be obtained by suppressing the particle size to a small value. From the above, it is a particularly excellent manufacturing method.

The Li ₃ BO ₃ sputtering target produced by the method as described above has a relative density of 90% or more (theoretical density is 2.14 g / cm ³ ), so that stable sputtering is possible. Since it consists of a single phase of Li ₃ BO ₃ , a thin film with excellent uniformity can be formed. Moreover, since there are no coarse particles having a particle diameter of 2 mm or more and black spots having a diameter of 2 mm or more, arcing (abnormal discharge) does not occur during sputtering, and the generation of particles can be significantly suppressed. Here, the grain size means a diameter when the crystal grains are surrounded by an equivalent circle diameter. Moreover, the black spot means a dot-like pattern which is black compared with the surroundings when visually observed, and the diameter when the dot-like pattern is surrounded by an equivalent circle diameter was evaluated.

  Hereinafter, description will be made based on Examples and Comparative Examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.

Example 1
As an example synthesized by firing, lithium hydroxide monohydrate and 3N boron oxide were weighed so as to have a target composition and then mixed for 5 hours in a dry ball mill. After calcination for 2 hours, the mixture was pulverized with a dry ball mill for 10 hours, further baked at 500 ° C. in the atmosphere for 2 hours, and then pulverized with a dry ball mill for 10 hours. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
As a result of measuring the obtained sintered body with an X-ray diffraction (XRD) apparatus, it was confirmed that it was a single phase of Li ₃ BO ₃ . The relative density was 93%. Furthermore, impurities Al, Ca, Fe, Na, Ni, Si, Cu, and K were respectively less than 50 wtppm, 34 wtppm, less than 10 wtppm, 260 wtppm, less than 10 wtppm, 74 wtppm, less than 10 wtppm, and 110 wtppm. The Li / B ratio of the sintered body was 2.9. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing did not occur and stable film formation was achieved.

(Example 2)
As an example of synthesis by dissolution, lithium hydroxide monohydrate and 3N boron oxide were weighed so as to have a target composition, then mixed for 5 hours in a dry ball mill, and then this mixed powder was filled into a carbon crucible. After being heat-treated in an argon atmosphere at 700 ° C. for 1 hour to dissolve, the cooled ingot was coarsely pulverized with a mortar and then pulverized with a dry ball mill for 10 hours. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
The results obtained sintered body was measured by X-ray diffraction apparatus, it was confirmed that a single phase of Li ₃ BO _3. The relative density was 92%. Furthermore, impurities Al, Ca, Fe, Na, Ni, Si, Cu, and K were less than 50 wtppm, less than 10 wtppm, less than 10 wtppm, 410 wtppm, less than 10 wtppm, 85 wtppm, less than 10 wtppm, and 15 wtppm, respectively. The Li / B ratio of the sintered body was 3.0. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing did not occur and stable film formation was achieved.

(Example 3)
As an example of using wet mixing for mixing raw material powders, lithium carbonate and 3N boron oxide were weighed to a target composition, then mixed in a wet ball mill using pure water for 10 hours, and then the slurry was dried. The mixed powder was fired at 400 ° C. for 2 hours in the atmosphere, pulverized for 10 hours in a dry ball mill, further baked for 2 hours at 600 ° C. in the air, and then pulverized for 10 hours in a dry ball mill. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
The results obtained sintered body was measured by X-ray diffraction apparatus, it was confirmed that a single phase of Li ₃ BO _3. The relative density was 95%. Furthermore, impurities Al, Ca, Fe, Na, Ni, Si, Cu, and K were less than 50 wtppm, less than 10 wtppm, less than 10 wtppm, 13 wtppm, less than 10 wtppm, 50 wtppm, less than 10 wtppm, and 15 wtppm, respectively. The Li / B ratio of the sintered body was 3.1. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing did not occur and stable film formation was achieved.

Example 4
As an example of using raw material powder other than boron oxide, lithium carbonate and 5N boric acid were weighed to a target composition, mixed for 10 hours in a wet ball mill using pure water, and then the slurry was dried. The powder was fired in air at 400 ° C. for 2 hours, pulverized in a dry ball mill for 10 hours, further baked in air at 600 ° C. for 2 hours, and then pulverized in a dry ball mill for 10 hours. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
The results obtained sintered body was measured by X-ray diffraction apparatus, it was confirmed that a single phase of Li ₃ BO _3. The relative density was 95%. Furthermore, impurities Al, Ca, Fe, Na, Ni, Si, Cu, and K were all less than 10 wtppm. The Li / B ratio of the sintered body was 3.1. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing did not occur and stable film formation was achieved.

(Example 5)
As an example of raising the sintering temperature, lithium hydroxide monohydrate and 3N boron oxide were weighed so as to have a target composition and then mixed for 5 hours in a dry ball mill. After calcination for 2 hours at 0 ° C., the mixture was pulverized for 10 hours by a dry ball mill, further baked for 2 hours at 500 ° C. in the atmosphere, and then pulverized for 10 hours by a dry ball mill. Thereafter, the pulverized powder was sintered in a vacuum at 700 ° C. for 4 hours by hot pressing to prepare a sintered body.
As a result of measuring the obtained sintered body with an X-ray diffraction (XRD) apparatus, it was confirmed that it was a single phase of Li ₃ BO ₃ . The relative density was 96%. Furthermore, impurities Al, Ca, Fe, Na, Ni, Si, Cu, and K were less than 50 wtppm, 53 wtppm, less than 10 wtppm, 130 wtppm, less than 10 wtppm, 85 wtppm, less than 10 wtppm, and 15 wtppm, respectively. The Li / B ratio of the sintered body was 2.9. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing did not occur and stable film formation was achieved.

(Comparative Example 1)
As an example of insufficient synthesis, lithium oxide monohydrate and 3N boron oxide were weighed to a target composition, then mixed for 2 hours with a V-type mixer (V-con), The mixed powder was baked at 500 ° C. for 2 hours in the air and then pulverized for 10 hours by a dry ball mill. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
As a result of measuring the obtained sintered body with an X-ray diffractometer, it was confirmed that Li ₃ BO ₃ was a main phase, but some LiBO ₂ , Li ₂ O and the like were present. The relative density was 93%, and the Li / B ratio of the sintered body was 2.9. Thus, due to insufficient mixing, the synthesis was insufficient and the Li ₃ BO ₃ single phase was not achieved.
Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, there were no black spots having a diameter of 2 mm or more on the surface, but it was confirmed that a large number of coarse particles having a particle diameter of 2 mm or more were generated. Thus, it was found that when there is a B-rich phase, coarse grains grow during sintering.
Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing that seems to be caused by coarse particles occurred, and stable film formation was difficult.

(Comparative Example 2)
As an example of adjusting the Li / B ratio to be less than 2.9, lithium carbonate and 3N boron oxide were weighed so that the Li / B ratio was less than 2.9, and then mixed in a dry ball mill for 10 hours. Next, this mixed powder was fired in the atmosphere at 400 ° C. for 2 hours, pulverized in a dry ball mill for 10 hours, further baked in the air at 600 ° C. for 2 hours, and then pulverized in a dry ball mill for 10 hours. Then, this pulverized powder was sintered in a vacuum at 650 ° C. for 4 hours to produce a sintered body.
The Li / B ratio of the obtained sintered body was 2.8. As a result of measuring this with an X-ray diffractometer, it was confirmed that Li ₃ BO ₃ was the main phase, but some LiBO ₂ and Li ₂ CO ₃ were present. The relative density was 95%. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When this target surface was observed, many black spots with a diameter of 2 mm or more existed on the surface, and some of them were coarse particles with a particle diameter of 2 mm or more. As described above, black spots and coarse grains which were thought to be caused by the B-rich phase or Li ₂ CO ₃ were generated. Next, when this target was attached to a sputtering apparatus and sputtering was performed, arcing occurred and target cracking due to arcing occurred.

(Comparative Example 3)
As an example of producing a target by melt casting, melted lithium carbonate and 3N boron oxide were weighed so as to have a target composition, and then mixed with V-con for 2 hours. After firing for a period of time, the mixture was pulverized with a dry ball mill for 10 hours. Next, the mixed powder was filled in a carbon crucible having a diameter of 7 inches, dissolved by heat treatment at 800 ° C. for 1 hour in an argon atmosphere, and then cooled in a furnace to obtain a plate-like ingot (bulk body). .
As a result of measuring the obtained bulk body with an X-ray diffractometer, it was confirmed that it was a single phase of Li ₃ BO ₃ . The relative density was 100%. The Li / B ratio of the sintered body was 2.9. Next, when this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm, cracking occurred. Moreover, when this target surface was observed, the black spot with a diameter of 2 mm or more did not exist on the surface, but it confirmed that many coarse grains with a particle diameter of 2 mm or more existed. When this target was attached to a sputtering apparatus and sputtering was performed, many arcing occurred, cracks occurred in the target, and stable film formation was difficult. Thus, it was found that when the melt cast product was processed and the target was produced as it was, the crystal grains became large, the strength was weak, and it was easy to break.

(Comparative Example 4)
As an example of lowering the sintering temperature, lithium hydroxide monohydrate and 3N boron oxide were weighed so as to have a target composition, and then mixed in a dry ball mill for 5 hours. Next, this mixed powder was fired in the atmosphere at 400 ° C. for 2 hours, pulverized in a dry ball mill for 10 hours, further baked in the air at 500 ° C. for 2 hours, and then pulverized in a dry ball mill for 10 hours. Thereafter, the pulverized powder was sintered in a vacuum at 600 ° C. for 4 hours by hot pressing to prepare a sintered body.
The relative density of the obtained sintered body was significantly reduced to 88%. Incidentally, the results of measurement by X-ray diffraction apparatus, it was confirmed that a single phase of Li ₃ BO _3. Moreover, Li / B ratio of the sintered compact was 2.9. Next, this sintered body was processed into a sputtering target having a diameter of 6 inches and a thickness of 5 mm. When the surface of the target was observed, black spots with a diameter of 2 mm or more did not exist on the surface, and coarse particles with a particle diameter of 2 mm or more could not be confirmed. Next, when this target was attached to a sputtering apparatus and sputtering was performed, sufficiently stable film formation could not be performed.

The sputtering target of the present invention is useful for forming a solid electrolyte thin film of a lithium ion secondary battery, in particular, a lithium electrolyte secondary battery thin film for automobile use, information communication equipment, household equipment, etc. is there.

Claims (13)

Formula: Li _x B _y O ₃ (wherein, x, y are in atomic%, satisfying the 2.9 ≦ x / y ≦ 3.1) sputtering target characterized by comprising a composition represented by. Al content less than 100wtppm, Ca content less than 500wtppm, Fe content less than 10wtppm, Na content less than 500wtppm, Ni content less than 10wtppm, Si content less than 150wtppm, Cu content less than 10wtppm, K Content is less than 150 wtppm, The sputtering target of Claim 1 characterized by the above-mentioned. The sputtering target according to claim 2, wherein the total content of Al, Ca, Fe, Na, Ni, Si, Cu, and K is less than 100 wtppm. 4. The sputtering target according to claim 3, wherein the content of each of Al, Ca, Fe, Na, Ni, Si, Cu, and K is less than 20 wtppm. 5. The sputtering target according to claim 1, wherein the relative density is 90% or more. 6. The sputtering target according to any one of claims 1 to 5, wherein coarse particles having a particle size of 2 mm or more are not present. The sputtering target according to any one of claims 1 to 6, characterized in that it consists li ₃ BO ₃ single phase. The sputtering target according to claim 1, wherein there are no black spots having a diameter of 2 mm or more. After weighing the raw material powder to be the Li source and the raw material powder to be the B source so that the atomic ratio of Li / B is 2.9 to 3.1, the raw material powder is sintered at 650 ° C. to 700 ° C. A method for producing Li ₃ BO ₃ , wherein After weighing the raw material powder as a Li source and the raw material powder as a B source so that the atomic ratio of Li / B is 2.9 to 3.1, the raw material powder is heated and melted at 700 ° C. to 1000 ° C. to synthesize Li ₃ BO ₃ Te, pulverized and Li ₃ BO ₃ was obtained, the production method of the Li ₃ BO _3, characterized in that sintering at 650 ° C. to 700 ° C.. The raw material powder as the Li source and the raw material powder as the B source are weighed and mixed so that the atomic ratio of Li / B is 2.9 to 3.1, and then the mixed powder is at a temperature not higher than the melting point of the raw material powder. After firing this sintered body, the sintered body is pulverized and then sintered at 500 ° C. to 700 ° C. to synthesize Li ₃ BO ₃ , and the obtained Li ₃ BO ₃ is pulverized and then sintered at 650 ° C. to 700 ° C. A process for producing Li ₃ BO ₃ , characterized in that Li ₃ BO ₃ sputtering target manufacturing method which is characterized in that processing the Li ₃ BO ₃ manufactured by the method according to the shape of the target to any one of claims 9-11. The solid electrolyte film formed by using Li ₃ BO ₃ sputtering target according to any one of claims 1-8.