TW201422835A - Sputtering target and conductive metal oxide film - Google Patents

Abstract

Disclosed is a sputtering target containing indium, a first metal, a second metal and oxygen. Based on 100 at.% of the total atom content of indium, the first metal and the second metal, the range of indium atom content is 10 to 20 at.%, the range of the first metal atom content is 60 to 80 at.% and the range of the second metal atom content is 10 to 20 at.%. Wherein, the first metal is selected from zinc, tin, and a combination thereof, and the second metal is selected from aluminium, titanium, and a combination thereof. The present invention also provides a conductive metal oxide film which is formed by using said sputtering target via sputtering process and has high resistivity. Furthermore, the predetermined thickness of said conductive metal oxide film is maintained and prevented from diminution, thereby not being damaged easily and effectively increasing the yield of the conductive metal oxide film applied to photoelectric elements.

Description

Sputtering target and conductive metal oxide film

The present invention relates to a sputtering target and a conductive metal oxide film, and more particularly to a sputtering target and a high-resistivity conductive metal oxide film which are formed by sputtering to form a conductive metal oxide film having a high electrical resistivity.

A conductive metal oxide film is usually deposited by a sputtering process, which can be formed by reactive sputtering using a metal or metal alloy target, or can be sputtered with a metal oxide sputtering target of the same composition. The conductive metal oxide film is formed.

Among them, an indium tin oxide film (hereinafter referred to as ITO film) has excellent electrical conductivity (that is, low resistivity) and high transparency under visible light irradiation, so it is the most mature conductive metal oxide film. It is also the most widely used conductive metal oxide film in the optoelectronic industry, especially as an electrode layer or current diffusion layer for photovoltaic elements.

Later, some scholars discovered that when the indium tin oxide film also contains zinc, an indium zinc tin oxide film is formed, in addition to maintaining high conductivity, it can also be irradiated by light in a short wavelength range. Has a higher light transmittance. Therefore, the indium zinc tin oxide film is also a conductive metal oxide film which may be applied as a transparent conducting oxide.

As the products required on the market are diversified, the demand for the characteristics of the conductive metal oxide film is not as high as that required in the past. For example, when applied to a touch panel, a relatively high resistance value is required. Conductive metal oxide film. The main practice is to thin the ITO film to increase the resistance of the film; however, the practice of reducing the thickness of the ITO film blindly tends to produce side effects such as thin film resulting in damage, or film thickness. Non-uniformity will cause electrical instability and the yield of the fabricated photovoltaic elements will be low.

Therefore, some studies have suggested that the traditional ITO film should be replaced by a different conductive metal oxide film by changing the metal element or composition ratio, and this method needs to consider many issues, except whether the film is compatible with other components. Similar to the compatibility between ITO film and other components, it also needs to consider the process equipment, process parameters and changes in the waste recycling process, so it has become the research goal of the industry.

According to the foregoing, the inventors have made an effort to study how to use a sputtering process similar to the current ITO film to form a conductive metal oxide film having a high yield, high quality, and high resistivity by sputtering a sputtering target. There is no need to change current process equipment and processes.

Accordingly, it is an object of the present invention to provide a sputtering target that is sputtered to form a high resistivity metal oxide.

Further, another object of the present invention is to provide a metal oxide having a high electrical resistivity.

Thus, the sputtering target of the present invention comprises indium, a first metal, a second metal, and oxygen.

The indium has an atomic content ranging from 10 to 20 at.% based on the total atomic content of indium, the first metal, and the second metal of 100 at.%, the first metal The sub-content is in the range of 60 to 80 at.%, and the second metal has an atomic content ranging from 10 to 20 at.%, wherein the first metal is selected from the group consisting of zinc, tin, and combinations thereof, and the second metal is selected from the group consisting of zinc, tin, and combinations thereof. Aluminum, titanium, and combinations of these.

Preferably, the atomic content of indium ranges from 12 to 18 at.%, the atomic content of the first metal ranges from 64 to 76 at.%, and the content of the second metal ranges from 12 to 18 at.%.

Preferably, the first metal is tin and zinc and the second metal is aluminum.

Preferably, the atomic content of tin in the first metal ranges from 10 to 20 at.%.

Preferably, the atomic content of zinc in the first metal ranges from 10 to 20 at.%.

Preferably, the sputtering target comprises a main component of a polycrystalline phase structure, and a crystal phase structure is different from the subcomponent of the main component, and the main component and the subcomponent each have indium, the first metal And the second metal.

Preferably, the atomic percentage of aluminum in the secondary component is greater than the atomic percentage of aluminum in the primary component.

Preferably, the X-ray diffraction measurement has a diffraction peak at a position where the diffraction angle is 33.0° to 35.0°.

Preferably, the sputtering target has a resistivity greater than 5 x 10 ^-3 Ω-cm and less than 10 ^-1 Ω-cm.

Preferably, the sputtering target has an absolute density greater than 6 g/cm ^-3 .

Thus, the conductive metal oxide film of the present invention is formed by sputtering of the above-described sputtering target.

Preferably, the conductive metal oxide film has a resistance value greater than 10 ⁶ Ω at a film thickness of 100 nm.

Preferably, the conductive metal oxide film has a resistivity of between 0.1 Ω-cm and 1 Ω-cm.

Preferably, the conductive metal oxide film has a light transmittance of more than 85%.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals.

A preferred embodiment of the sputtering target of the present invention comprises indium, a first metal, a second metal, and oxygen, and the total atomic content of the indium, the first metal, and the second metal is 100 at.%, indium. The atomic content ranges from 10 to 20 at.%, the first metal has an atomic content ranging from 60 to 80 at.%, and the second metal has an atomic content ranging from 10 to 20 at.%, wherein the first metal is selected from the group consisting of zinc And tin, and combinations thereof, the second metal is selected from the group consisting of aluminum, titanium, and combinations thereof, and the resistivity of the oxide of the second metal is higher than the resistivity of the oxide of the first metal.

When the preferred embodiment is sputtered in a cavity of a sputtering machine to form a conductive metal oxide film, since the sputtering is formed by a physical deposition principle, the film contains indium. The conductive metal oxide film formed by the sputtering target of the first metal, the second metal, and oxygen also contains indium, the first metal, the second metal, and oxygen.

It should also be noted here that, although, the conductive metal oxide film is special In addition to the influence of the composition of the target components, the properties are also affected by the sputtering environment and parameter values. For example, when oxygen is also introduced into the cavity of the sputtering machine during sputtering, the oxygen may also depend on the environment (such as the temperature of the cavity or the pressure of the cavity or the oxygen content in the cavity). Reacting with the metal component of the sputtering target, thereby affecting the characteristics of the conductive metal oxide film. However, the influence of the sputtering environment and parameter setting on the resistivity of the conductive metal oxide film is usually limited to a range, and there is no way to obtain a stable high resistance ITO film or indium zinc tin oxide under appropriate sputtering conditions. film. Therefore, in a preferred manner, it is still necessary to use a metal oxide target of a suitable composition and composition ratio to obtain a high-resistivity conductive metal oxide film.

In the preferred embodiment, the second metal has an atomic content of 10 to 20 at.%, and the composition of the conductive metal oxide film formed after the sputtering process also contains the second metal, and the conductive metal oxide film The sheet resistance of the ITO film of the same thickness is larger than that of the indium zinc tin oxide film of the same thickness; further, the light transmittance is still comparable to that of the current indium zinc tin oxide film. Specifically, when the conductive metal oxide film has a film thickness of 100 nm, its electric resistance value is more than 10 ⁶ Ω, and the average light transmittance is more than 85%.

It should also be noted that one of the reasons why the resistivity of the conductive metal oxide film formed by the preferred embodiment is greater than the resistivity of the indium zinc tin oxide film is that a predetermined concentration of aluminum or titanium atoms is added. Forming a compound with a higher resistivity with indium zinc tin, thereby lowering the electron mobility and increasing the resistivity.

In particular, if the atomic content of the second metal of the preferred embodiment Less than 10 at.%, the conductive metal oxide film having an excessively low atomic content of the second metal is easily formed after the sputtering process; aluminum is used as the second metal as an example, when aluminum in a conductive metal oxide film When the content is too low, the aluminum atom occupies the lattice position of the original zinc or indium to produce a substitution effect, thereby increasing the concentration of the carrier in the oxide, resulting in an increase in the conductivity of the conductive metal oxide film.

In addition, if the atomic content of the second metal in the preferred embodiment is greater than 20 at.%, the content of alumina or titanium oxide having high insulating property in the material is too high, which will cause the conductive metal formed by sputtering. The oxide film has an excessively high resistance value and insufficient conductivity.

More precisely, the preferred embodiment has an indium content ranging from 12 to 18 at.%, an atomic content of the first metal ranging from 64 to 76 at.%, and an atomic content of the second metal ranging from 12 to 18 at.%. .

And preferably, the first metal is tin and zinc, the second metal is aluminum, and the atomic content of zinc ranges from 10 to 20 at.%, or the atomic content of tin ranges from 10 to 20 at.%. The conductive metal oxide film formed by sputtering is made to have a resistance value of more than 5 × 10 ⁶ Ω at a film thickness of 100 nm, and a light transmittance of more than 87% when irradiated with light having a wavelength in the range of 300 to 1300 nm.

More preferably, the preferred embodiment comprises a primary component and a secondary component having a lattice structure different from the primary component, the primary component and the secondary component both comprising indium, the first metal, and the second metal. The atomic content percentage of the second metal in the subcomponent is greater than the atomic content percentage of the second metal in the main component, and it is presumed that the subcomponent contains a compound having a higher resistivity; the atomic percentage as referred to herein is also based on the main Indium in the component or accessory component, The total content of atoms of the first metal and the second metal is 100 at.%.

Preferably, the sputtering target has a resistivity greater than 5 x 10 ^-3 Ω-cm and less than 10 ^-1 Ω-cm to ensure that the sputtering process can be performed under DC sputtering.

Hereinafter, a method of fabricating a preferred embodiment of the sputtering target of the present invention will be described in detail with the first metal being tin and zinc and the second metal being aluminum.

First, indium oxide powder, zinc oxide powder, tin oxide powder, and an alumina powder having a purity of more than 99.9% are separately prepared.

Next, a ball milling step is performed, the indium oxide powder, the zinc oxide powder, the tin oxide powder, and the alumina powder are first mixed to form a mixed powder, and placed in a ball mill, and then a plurality of balls are added to the ball mill. The zirconia balls are then ball-milled continuously with the mixed powder for 8 hours or more, and the ball-milled mixed powder is separated from the zirconia balls.

Further, a granulation step is carried out, and the ball-milled mixed powder is spray-dried to form a granulated powder having a particle diameter ranging from 20 to 100 μm.

Continuing, a molding step is performed to prepare a mold coated with a release agent, and the granulated powder is placed, and then pressed in an environment having a pressure ranging from 200 to 1200 kg/cm ³ and a temperature ranging from 30 to 50 ° C. A raw embryo target having a relative density ranging from 50 to 65% is obtained.

Next, a sintering step is performed to place the green target in a high temperature sintering furnace in which oxygen is introduced, and then sintered at a temperature ranging from 1300 to 1600 ° C to form the preferred embodiment of the sputtering target of the present invention.

Finally, an integer step can be performed as needed, and the preferred embodiment is cut to a predetermined size and surface-polished to make the surface smooth and flat.

Next, the specific examples and comparative examples of the sputtering target of the present invention, and the composition ratio and characteristics of the conductive metal oxide thin film formed thereon are measured and analyzed.

Measurement and Analysis [Specific example 1]

This Specific Example 1 was obtained by the above-described production method of the preferred embodiment, using 19.2 g of indium oxide powder having a purity of more than 99.9%, 11.3 g of zinc oxide powder, 62.5 g of tin oxide powder, and 7.0 g of alumina powder. When the atomic content of indium, zinc, tin, and aluminum is 100 at.%, the atomic content of indium of the specific example 1 is 16.7 at.%, the atomic content of zinc is 16.7 at.%, and the atomic content of tin is 50 at. %, and the atomic content of aluminum is 16.7 at.%. (The above is the rounding of the atomic content value to the first digit below the decimal point)

Continuing, the specific example 1 was used as a target for a sputtering process at a power density of 3 W/cm ² , a temperature controlled at room temperature, an argon gas having a flow rate of substantially 70 sccm, and an oxygen gas having a flow rate of substantially 4 sccm, and working. a cavity environment with a pressure of 3.5 mTorr was sputter-deposited on a substrate spaced apart from the target to form a thin film, and after sputtering, tempered at 200 ° C to obtain a conductive metal formed by the specific example 1. Oxide film.

[Specific example 2]

This Specific Example 2 was obtained in a manner similar to that of the specific example 1, using 23.7 g of indium oxide powder having a purity of more than 99.9%, 41.8 g of zinc oxide powder, 25.8 g of tin oxide powder, and 8.7 g of alumina powder. When the atomic content of indium, zinc, tin, and aluminum is 100 at.%, the atomic content of indium of the specific example 1 is 16.7 at.%, the atomic content of zinc is 50 at.%, and the atomic content of tin. It is 16.7 at.%, and the atomic content of aluminum is 16.7 at.%. (The above is the rounding of the atomic content value to the first digit below the decimal point)

Continuing, the specific example 2 was used as a target for the sputtering process, and a film was formed similar to the sputtering process of the specific example 1, and then sputtered and tempered at 280 ° C to obtain a film. A conductive metal oxide thin film formed by the specific example 2.

[Comparative Example 1]

Comparative Example 1 was prepared in a manner similar to that of the specific example 1, except that 73.2 g of indium oxide powder having a purity of more than 99.9%, 9.8 g of zinc oxide powder, and 17.0 g of tin oxide powder were separately prepared.

Continuing, the comparative example 1 was used as a target for the sputtering process, and a film was formed similar to the sputtering process of the specific example 1, and then sputtered and tempered at 280 ° C to obtain a film. A conductive metal oxide thin film formed by the comparative example 1.

[Comparative Example 2]

Comparative Example 2 was prepared in a manner similar to that of the specific example 1, except that 90 g of indium oxide powder having a purity of more than 99.9% and 10 g of tin oxide powder were separately prepared.

Continuing, the comparative example 2 was used as a target for the sputtering process, and a film was formed similar to the sputtering process of the specific example 1, and then sputtered and tempered at 280 ° C to obtain a film. A conductive metal oxide thin film (i.e., an ITO thin film) formed by the comparative example 2.

[Comparative Example 3]

This Comparative Example 3 was produced in a manner similar to the production method of the specific example 1, which The difference is that 98 g of zinc oxide powder having a purity greater than 99.9% and 2 g of alumina powder are separately prepared.

Continuing, the comparative example 3 was used as a target for the sputtering process, and a film was formed similar to the sputtering process of the specific example 1, and then sputtered and tempered at 170 ° C to obtain a film. A conductive metal oxide thin film (that is, an AZO thin film) formed by the comparative example 3.

The measurement results of the composition ratio and characteristics are listed in Table 1.

It should be noted that the measurement conditions of the resistance in Table 1 are fixed in both the specific example and the comparative example, and the film thickness is 100 nm; in addition, the specific example 1 and the specific example 2 have higher resistance values and have exceeded the four-point probe. The measurement range of the resistance measurement method cannot measure the resistance of the film by the four-point probe, so the high resistance measurement is used. In addition, since the resistance listed in Table 1 is measured under the condition of a film thickness of 100 nm, the resistivity is obtained by multiplying the measured value of the resistance by the film thickness; the light transmittance is at a film thickness of 100 nm and is subjected to a wavelength range. Light from 300 to 1300 nm The result of the measurement when the line is illuminated.

First, the resistance values of the conductive metal oxide thin film formed by the specific example 1 and the specific example 2 can be understood to be that when the first metal of the sputtering target is zinc and tin, and the second metal is aluminum, the conductive is formed. The resistance value of the metal oxide film is much higher than that of the indium zinc tin oxide target, the indium tin oxide target, and the zinc aluminum oxide target (ie, Comparative Examples 1, 2, and 3, respectively). Sheet resistance of the metal oxide film; this means that when the atomic content of indium ranges from 12 to 18 at.%, the atomic content of the first metal ranges from 64 to 76 at.%, and the atomic content of the second metal ranges from 12 to At 18 at.%, the resistivity of the conductive metal oxide film formed by the sputtering target can be raised to a predetermined range. It can be understood from the measurement result of Comparative Example 3 that the atomic content of aluminum in the sputtering target is less than 10 at.%, and the atomic content of aluminum of the conductive metal oxide film formed is too low to be effectively improved. Resistivity; it can be understood from Comparative Example 1 and Comparative Example 2 that when the sputtering target is only indium, zinc, and/or tin, even if the proportional relationship between indium and the first metal is adjusted, high resistivity cannot be formed. A conductive metal oxide film.

Next, as can be understood from Table 1, the transmittance of the conductive metal oxide film formed by sputtering in the specific example 1 and the specific example 2 of the present invention is still more than 85%, and the sputtering examples of the comparative examples 1, 2, and 3 are compared. The light transmittance of the formed conductive metal oxide film is equivalent.

Referring to FIG. 1 and FIG. 2, the sputtering target of the specific example 1 is scanned by a scanning electron microscope (SEM) to scan the surface of the preferred embodiment and analyze the backscattered electrons. Back-scattering electron (BSE), by As can be understood from the figure, the specific example 1 includes a main component (light color), and a crystal phase structure is different from the subcomponent of the main component (dark color).

Referring to FIG. 3, the energy dispersive spectrometer (EDS) analysis chart can be used to understand that the atomic content of indium, zinc, tin and aluminum based on the main component of the specific example 1 is 100 at.%. At 18.58 at.%, the atomic content of zinc is 14.82 at.%, the atomic content of tin is 61.6 at.%, and the atomic content of aluminum is 5.00 at.%, that is, the atomic content of the first metal of the main component is 76.42 at.%, and the atomic content of the second metal is 5.00 at.%; the atomic content of indium, zinc, tin, and aluminum based on the by-component of the specific example 1 is 100 at.%, and the atomic content of indium is 3.4 at .%, the atomic content of zinc is 31.12 at.%, the atomic content of tin is 6.03 at.%, and the atomic content of aluminum is 59.45 at.%, that is, the atomic content of the first metal of the accessory component is 37.15 at. %, and the atomic content of the second metal is 6.03 at.%.

Referring to Fig. 4, it can be understood from the EDS analysis chart that the atomic content of indium, zinc, tin and aluminum based on the main component of the specific example 2 is 100 at.%, the atomic content of indium is 18.42 at.%, and the atomic content of zinc is 57.89 at.%, the atomic content of tin is 19.01 at.%, and the atomic content of aluminum is 4.68 at.%, that is, the atomic content of the first metal of the main component is 76.9 at.%, and the second metal The atomic content is 4.68 at.%; the atomic content of indium, zinc, tin and aluminum based on the by-component of the specific example 2 is 100 at.%, the atomic content of indium is 9.02 at.%, and the atomic content of zinc is 42.82 at. %, the atomic content of tin is 9.03 at.%, and the atomic content of aluminum is 38.86 at.%, that is, the atomic content of the first metal of the subcomponent is 52.12 at.%, and the atomic content of the second metal is 38.86at.%.

Referring to FIG. 5, it can be understood from the X-ray diffraction (XRD) measurement chart that the specific example 1 is a polycrystalline phase structure and is respectively at a diffraction angle of 25.5° to 26.5° and 30.5°. Diffraction peaks can be observed up to 31.5°, 33.0° to 34.0°, and 51.0° to 52.0°.

Referring to Fig. 6, it can be understood from the XRD measurement chart that the specific example 2 is a polycrystalline phase structure, and the diffraction angles are 16 to 18, 28.5 to 29.5, 33.5 to 34.5, and 35.5 to 36.5, respectively. Diffraction peaks can be observed at °, 41° to 42°, 54.5° to 55.5°, and 60° to 61°.

In summary, the sputtering target of the present invention contains indium, the first metal, the second metal, and oxygen, and the second metal has an atomic content of 10 to 20 at.%, and is formed by sputtering. The conductive metal oxide film has a film thickness equivalent to that of the existing ITO film or indium zinc tin oxide film, and the resistivity thereof is higher than that of the ITO film or the indium zinc tin oxide film, and the light transmittance is still higher than 85% is suitable for use in optoelectronic components, such as touch panels and touch sensors, so it is indeed possible to achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1 is a signal diagram of a surface of the preferred embodiment by electron beam scanning of a sputtering target with a scanning electron microscope and analyzing backscattered electrons; 2 is a partial enlarged view of FIG. 1; FIG. 3 is an energy dispersive spectrometer (EDS) analysis diagram of a specific example 1; FIG. 4 is an EDS analysis diagram of a specific example 2; The X-ray diffraction (hereinafter referred to as XRD) measurement chart of Example 1; and FIG. 6 is an XRD measurement chart of a specific example 2.

Claims (13)

A sputtering target comprising: indium, a first metal, a second metal, and oxygen, based on indium, a total atomic content of the first metal and the second metal, at 100 at.%, an atomic content range of indium 10 to 20 at.%, the first metal has an atomic content ranging from 60 to 80 at.%, and the second metal has an atomic content ranging from 10 to 20 at.%, wherein the first metal is selected from the group consisting of zinc and tin, and In combinations of these, the second metal is selected from the group consisting of aluminum, titanium, and combinations thereof. The sputtering target according to claim 1, wherein the indium has an atomic content ranging from 12 to 18 at.%, and the first metal has an atomic content ranging from 64 to 76 at.%, the atom of the second metal The content ranges from 12 to 18 at.%. The sputtering target according to claim 1, wherein the first metal is tin and zinc, and the second metal is aluminum. A sputtering target according to claim 3, wherein the atomic content of tin ranges from 10 to 20 at.%. A sputtering target according to claim 3, wherein the atomic content of zinc ranges from 10 to 20 at.%. The sputtering target according to claim 3, wherein the sputtering target comprises a main component of a polycrystalline phase structure, and a crystal phase structure is different from an auxiliary component of the main component, and the main component Both the component and the accessory component have indium, the first metal, and the second metal. According to the sputtering target of claim 6, wherein the atomic percentage of aluminum in the auxiliary component is greater than the atomic content of aluminum in the main component The percentage of the amount. The sputtering target according to claim 3, wherein the diffraction peak has a diffraction peak at a diffraction angle of 33.0° to 35.0° by X-ray diffraction measurement. The sputtering target according to claim 3, wherein the sputtering target has a resistivity of more than 5 × 10 ^-3 Ω-cm and less than 10 ^-1 Ω-cm. The sputtering target according to claim 3, wherein the sputtering target has an absolute density of more than 6 g/cm ^-3 . A conductive metal oxide thin film formed by sputtering of the sputtering target according to any one of the above items 1 to 10. The conductive metal oxide film according to claim 11, wherein the conductive metal oxide film has a resistivity of between 0.1 Ω-cm and 1 Ω-cm. The conductive metal oxide film according to claim 11, wherein the conductive metal oxide film has a light transmittance of more than 85%.