阅读说明：本技术 氧化物烧结体及溅射靶 (Oxide sintered body and sputtering target ) 是由 松元谦士 井上雅树 中村信一郎 矢野智泰 于 2018-07-02 设计创作，主要内容包括：本发明为一种氧化物烧结体,其中,构成元素为In、Sn、Ti及O,In的含有比率以In<Sub>2</Sub>O<Sub>3</Sub>换算计为88.0～98.2质量％,Sn的含有比率以SnO<Sub>2</Sub>换算计为1.0～8.0质量％,Ti的含有比率以TiO<Sub>2</Sub>换算计为0.8～4.0质量％。通过本发明的氧化物烧结体,能够得到可成膜出即使不进行高温的热处理也能够得到透明性高的透明导电膜、进而电阻低的透明导电膜的薄膜的溅射靶。(The invention provides kinds of oxide sintered bodies, wherein the constituent elements are In, Sn, Ti and O, the content ratio of In is In 2 O 3 88.0 to 98.2% by mass in terms of Sn content 2 1.0 to 8.0% by mass in terms of TiIn the content ratio of TiO 2 Converted to 0.8 to 4.0 mass%. The oxide sintered body of the present invention can provide a sputtering target capable of forming a thin film in which a transparent conductive film having high transparency and a transparent conductive film having low resistance can be obtained without performing a high-temperature heat treatment.)

1, kinds of oxide sintered bodies, wherein the constituent elements are In, Sn, Ti and O, the content ratio of In is In₂O₃88.0 to 98.2% by mass in terms of Sn content₂Converted to 1.0 to 8.0 mass%, and the content of Ti is calculated as TiO₂Converted to 0.8 to 4.0 mass%.

2. According to claimThe oxide sintered body of 1, wherein the specific resistance is 5.0X 10^-4Omega cm or less.

3. The oxide sintered body according to claim 1 or 2, wherein the relative density is 95% or more.

4, kinds of sputtering targets, which are formed of the oxide sintered body according to of any one of claims 1 to 3.

5, kinds of sputtering targets, which is formed by bonding the sputtering target material according to claim 4 and a base material.

6, kinds of transparent conductive film, which has In, Sn, Ti and O as constituent elements, the In content ratio being In₂O₃88.0 to 98.2% by mass in terms of Sn content₂Converted to 1.0 to 8.0 mass%, and the content of Ti is calculated as TiO₂Converted to 0.8 to 4.0 mass%.

7, A method for producing a transparent conductive film, wherein a thin film formed by sputtering the sputtering target according to claim 5 is subjected to a heat treatment at 110 to 145 ℃.

Technical Field

The present invention relates to an oxide sintered body and a sputtering target, and more particularly, to a sputtering target capable of obtaining a thin film having high transmittance in the visible light region and low specific resistance, and an oxide sintered body capable of producing such a target.

Background

In accordance with the development of display devices mainly using liquid crystals, demands for transparent conductive films have been increasing, high transparency has been demanded for transparent conductive films, and further, low resistance has been demanded in steps, an ITO film has been widely used as a transparent conductive film in in view of the demands for high transparency and low resistance, and as a method for forming an ITO transparent conductive film, a method for forming an ITO sputtering target by sputtering has been generally used in in view of the ease of handling.

In particular, recently, with the colorization of liquid crystals, the miniaturization of elements, and the adoption of an active matrix system, there is a demand for a high-performance transparent conductive film of ITO having higher transparency and lower resistance.

Patent document 1 describes a high-transmittance, low-resistance transparent conductive film containing 1 to 20 wt% of tin oxide and 0.05 to 5 wt% of titanium oxide, and a sputtering target, and describes that the high transmittance and the low resistance of the transparent conductive film can be achieved by performing a heat treatment at 300 ℃.

Patent document 2 describes methods for manufacturing a transparent conductive film, in which a sputtering target made of an oxide such as indium oxide, tin oxide, or titanium is sputtered, and the obtained indium tin oxide thin film is crystallized by a heat treatment, and in this method, an amorphous indium tin oxide thin film obtained by sputtering is crystallized by a heat treatment at 200 ℃.

However, the method requiring heat treatment at a high temperature of 200 ℃ or higher cannot be applied to the case of forming a transparent conductive film on a resin film that deforms at 200 ℃ or higher.

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to provide a sputtering target capable of forming a thin film that can provide a transparent conductive film having high transparency and low resistance without performing a high-temperature heat treatment.

Means for solving the problems

The oxide sintered body of the present invention contains In, Sn, Ti and O as constituent elements, and the content ratio of In is In₂O₃88.0 to 98.2% by mass in terms of Sn content₂Converted to 1.0 to 8.0 mass%, and the content of Ti is calculated as TiO₂Converted to 0.8 to 4.0 mass%.

The specific resistance of the oxide sintered body is preferably 5.0X 10^-4Omega cm or less, and the relative density is preferably 95% or more.

The sputtering target of the present invention is formed of the above oxide sintered body.

The sputtering target of the present invention is obtained by bonding the sputtering target material and a base material.

In the transparent conductive film of the present invention, the In content ratio is In₂O₃88.0 to 98.2% by mass in terms of Sn content₂Converted to 1.0 to 8.0 mass%, and the content of Ti is calculated as TiO₂Converted to 0.8 to 4.0 mass%.

The method for producing a transparent conductive film of the present invention comprises subjecting a thin film formed by sputtering the sputtering target to a heat treatment at 110 to 145 ℃.

Effects of the invention

The oxide sintered body of the present invention can provide a sputtering target capable of forming a thin film in which a transparent conductive film having high transparency and a transparent conductive film having low resistance can be obtained without performing a high-temperature heat treatment.

Drawings

FIG. 1 is a graph showing the light transmittance in the wavelength range of 300nm to 800nm of the thin film obtained by sputtering in example 15 and the transparent conductive film obtained by heat-treating the thin film at 125 ℃.

Fig. 2 is a graph showing the light transmittance in the wavelength range of 300nm to 800nm of the transparent conductive film obtained by heat-treating the thin film obtained by sputtering at 125 ℃ in example 15 and comparative examples 1 and 3.

Detailed Description

The oxide sintered body of the present invention contains In, Sn, Ti and O as constituent elements, and the content ratio of In is In₂O₃88.0 to 98.2% by mass in terms of Sn content₂Converted to 1.0 to 8.0 mass%, and the content of Ti is calculated as TiO₂Converted to 0.8 to 4.0 mass%.

In the oxide sintered body, the In content ratio is In₂O₃In terms of SnO, the content of Sn is 88.0 to 98.2 mass%, preferably 90.0 to 97.0 mass%, more preferably 91.5 to 96.0 mass%, and further preferably 93.0 to 95.5 mass% in ₂In terms of TiO, the content of Ti is 1.0 to 8.0 mass%, preferably 2.0 to 7.0 mass%, more preferably 2.7 to 6.0 mass%, and further preferably 3.0 to 5.0 mass% in ₂0.8 to 4.0% by mass, preferably 1.0 to 3.0% by mass, more preferably 1.3 to 2.5% by mass, and further preferably 1.5 to 2.0% by mass in terms of , it goes without saying that inevitable impurities derived from raw materials and the like may be contained in the oxide sintered body of the present invention, and that inevitable impurities may be contained in the oxide sintered body of the present inventionExamples of the impurities to be avoided include Fe, Cr, Ni, Si, W, Zr and the like, and the contents thereof are usually 100ppm or less.

In the present invention, the constituent elements mean constituent elements other than inevitable impurities in the oxide sintered body or the transparent conductive film, and the content ratio of each constituent element means a content ratio of each constituent element in the entire oxide sintered body or the transparent conductive film.

The specific resistance of the oxide sintered body is preferably 5.0X 10^-4Not more than Ω cm, more preferably 4.8X 10^-4Omega cm or less, and preferably 4.5X 10 in the further steps^-4Omega cm or less. This enables sputtering using an inexpensive DC power supply, and can improve the film formation rate and suppress the occurrence of abnormal discharge.

The relative density of the oxide sintered body is preferably 95% or more, more preferably 98% or more, and further preferably 99% or more in the step, and when the relative density is 95% or more, effective sputtering without generation of nodules or breakdown can be achieved, the upper limit of the relative density is not particularly limited, and may exceed 100%.

The oxide sintered body can be produced by the following method, for example.

First, raw material powders are mixed. The raw material powder is usually In₂O₃Powder, SnO₂Powder and TiO₂And (3) powder. In₂O₃Powder, SnO₂Powder and TiO₂The powders are mixed so that the contents of In, Sn, and Ti In the obtained sintered body fall within the above ranges. In the mixed powder obtained by mixing the raw material powders₂O₃Powder, SnO₂Powder and TiO₂The content ratio of the powder to In the oxide sintered body₂O₃Converted In content ratio, SnO₂Converted Sn content ratio, and TiO₂The converted Ti content ratios were respectively.

Since the respective raw material powders are generally aggregated, they are preferably pulverized and mixed in advance, or they are pulverized while being mixed with at .

The method of pulverizing or mixing the raw material powder is not particularly limited, and for example, the raw material powder may be put in a bowl and pulverized or mixed by a ball mill.

The obtained mixed powder may be directly molded to prepare a compact and then sintered, but a binder may be added to the mixed powder and molded to prepare a compact as needed. As the binder, a binder used in obtaining a molded body by a known powder metallurgy method, for example, polyvinyl alcohol, an acrylic emulsion binder, or the like can be used. Alternatively, a dispersion medium may be added to the mixed powder to prepare a slurry, the slurry may be spray-dried to prepare particles, and the particles may be molded.

The molding method may be a method conventionally used in powder metallurgy, for example, cold pressing or CIP (cold isostatic pressing).

Alternatively, a green compact may be produced by temporarily subjecting the mixed powder to green compaction, and then subjecting the pulverized powder obtained by pulverizing the green compact to main compaction.

The molded body may be produced by a wet molding method such as a slip casting method.

The obtained compact may be degreased by a method conventionally used in powder metallurgy, if necessary. The density of the molded article is usually 50 to 75%.

Next, the obtained compact is fired to produce an oxide sintered body. The sintering furnace used for sintering is not particularly limited as long as the cooling rate can be controlled during cooling, and may be one that is generally used in powder metallurgy. As the firing atmosphere, an oxygen atmosphere is suitable.

The temperature rise rate is usually 100 to 500 ℃/h from the viewpoint of densification and prevention of cracking. The firing temperature is 1300-1600 ℃, preferably 1400-1600 ℃. When the firing temperature is within the above range, an oxide sintered body having a high density can be obtained. The holding time at the firing temperature is usually 3 to 30 hours, preferably 5 to 20 hours. When the holding time is within the above range, an oxide sintered body having a high density can be easily obtained.

The cooling rate is usually 300 ℃/hr or less, preferably 50 ℃/hr or less.

The sputtering target of the present invention is formed of the above oxide sintered body. Specifically, the oxide sintered body is cut into a desired shape as needed, and subjected to a process such as grinding, thereby obtaining a sputtering target.

The composition, specific resistance, relative density and other physical properties of the sputtering target are the same as those of the oxide sintered body.

By bonding the sputtering target material to the base material, a sputtering target can be obtained. The substrate is typically Cu, Al, Ti or stainless steel. As the bonding material, a bonding material used for bonding a conventional ITO target, for example, In metal can be used. The bonding method is also the same as the conventional method for bonding an ITO target.

By sputtering the sputtering target, a thin film can be formed. The sputtering can be performed under the conditions in sputtering using a general ITO sputtering target.

The film obtained in this manner is generally amorphous. By subjecting the thin film to heat treatment, so-called annealing, crystallization can be achieved, and a transparent conductive film having high light transmittance and low specific resistance can be obtained. The light transmittance can be significantly improved particularly in the short wavelength range, for example, in the wavelength range of 300 to 380 nm.

The temperature required for this heat treatment is 110 to 145 ℃, preferably 115 to 140 ℃, and further preferably 120 to 135 ℃ in steps, as described above, a temperature of 200 ℃ or higher is required for the heat treatment for increasing the transmittance and decreasing the resistance of the ITO thin film, which has been known in the prior art, and on the other hand, a low temperature of 110 to 145 ℃ is preferable for the heat treatment for increasing the transmittance and decreasing the resistance of the thin film obtained by sputtering the sputtering target of the present invention, and therefore, when the sputtering target of the present invention is used, even in the case of producing a transparent conductive film on a resin film or the like which causes deformation or the like at 200 ℃ or higher, it is possible to produce a transparent conductive filmWhen the transparent conductive film is heat-treated at a temperature exceeding 145 ℃ to produce a transparent conductive film having high light transmittance and low resistance without causing deformation of the film or the like, does not achieve sufficient high transmittance and low resistance, and is contrary to the conventional ITO film (In)₂O₃：SnO₂When the ratio is 90: 10 (mass ratio)) is not preferable because it tends to have a lower transmittance and a higher specific resistance.

The time required for the heat treatment is usually 0.1 to 2 hours, preferably 0.5 to 1 hour. The above heat treatment may be performed in the atmosphere.

By subjecting the thin film obtained by sputtering the sputtering target of the present invention to the above-described heat treatment, the light transmittance and the specific resistance can be improved.

Particularly, with respect to the light transmittance, by performing the heat treatment at the above temperature, it is possible to obtain an ITO thin film (In) having a wavelength region of visible light (for example, 380 to 750nm), particularly a short wavelength region (for example, 300 to 380nm), which is more excellent than that of a conventionally known ITO thin film₂O₃：SnO₂When the ratio is 90: 10 (mass ratio)).

The transparent conductive film obtained In this way has In, Sn, Ti and O as constituent elements, for example, In₂O₃In terms of SnO, the content of Sn is 88.0 to 98.2 mass%, preferably 90.0 to 97.0 mass%, more preferably 91.5 to 96.0 mass%, and further is preferably 93.0 to 95.5 mass%, and the content of Sn is SnO₂In terms of TiO, the content of Ti is 1.0 to 8.0 mass%, preferably 2.0 to 7.0 mass%, more preferably 2.7 to 6.0 mass%, and further is preferably 3.0 to 5.0 mass%, and the content of Ti is TiO₂The transparent conductive film has a high light transmittance and a low resistance as described above, and the transparent conductive film is preferably 0.8 to 4.0% by mass, more preferably 1.0 to 3.0% by mass, even more preferably 1.3 to 2.5% by mass, and further preferably 1.5 to 2.0% by mass in terms of .