CN102945694B - ITO (indium tin oxide) base plate and preparation method of ITO base plate - Google Patents

Abstract

The invention discloses an ITO substrate, which comprises a substrate and a first ITO film layer deposited on one surface of the substrate, and the first ITO film layer is in a nano-crystalline state. The above-mentioned ITO substrate includes a substrate and a first ITO film layer deposited on one surface of the substrate, and the first ITO film layer is in a nanocrystalline state. The first nanocrystalline ITO film layer has periodic arrangement of internal ions and is anisotropic, while the amorphous ITO film layer has no periodic arrangement of internal ions and isotropic. Compared with the traditional amorphous ITO film layer, the nanocrystalline first ITO film layer of the ITO substrate has a lower resistivity. The present invention also provides a preparation method of the above-mentioned ITO substrate.

Description

ITO substrate and preparation method thereof

technical field

The invention relates to the field of preparation of conductive substrates, in particular to an ITO substrate and a preparation method thereof.

Background technique

ITO (indium tin oxide) thin film is an n-type semiconductor material, which has the advantages of high electrical conductivity, high transmittance of visible light, high mechanical hardness and stable chemical properties. Therefore, it has a wide range of applications in the fields of plasma displays, liquid crystal displays, electroluminescent displays, touch screens, solar cells, and transparent electrodes of electronic instruments.

The ITO substrate used in the traditional capacitive touch screen is obtained by depositing an ITO film layer on the substrate by using a magnetron sputtering coating process at room temperature. However, the ITO film layer prepared under this condition is amorphous, so that the resistivity of the ITO film layer of the prepared ITO substrate is relatively high.

Contents of the invention

Based on this, it is necessary to provide an ITO substrate with a lower resistivity of the ITO film layer and a preparation method thereof.

An ITO substrate includes a substrate and a first ITO film layer deposited on one surface of the substrate, and the first ITO film layer is in a nanocrystalline state.

In one embodiment, the thickness of the first ITO film layer is 20nm ~ 40nm;

The material of the substrate is polymethyl methacrylate, polyethylene terephthalate or polycarbonate.

In one embodiment, the first ITO film layer contains 1% to 20% SnO ₂ by mass percentage, and the balance is In ₂ O ₃ ;

Or the first ITO film layer contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ .

In one embodiment, it also includes a second ITO film layer deposited on the other surface of the substrate, and the second ITO film layer is in a nanocrystalline state;

The second ITO film layer contains 1% to 20% by mass of SnO ₂ , the balance being In ₂ O ₃ ; or the second ITO film layer contains 0.3% to 5% by mass of TiO ₂ , the balance being The amount is In ₂ O ₃ .

A preparation method for an ITO substrate, comprising the steps of:

Provide substrates and targets;

Using plasma-induced process, the substrate temperature is room temperature, the sputtering power is 4kW~8kW, the flow rate of argon gas is 300sccm~500sccm, the flow rate of oxygen gas is 1sccm~20sccm, and the partial pressure of impurity gas is less than 5×10 ^-7 torr Depositing a first nanocrystalline ITO film layer on one surface of the substrate by using the target material to obtain the ITO substrate.

In one embodiment, the partial pressure of the impurity gas is detected by a residual gas analyzer.

In one embodiment, the condition that the partial pressure of the impurity gas is less than 5×10 ^-7 torr is controlled by the following method:

The substrate is placed between the winding hub and the unwinding hub in the vacuum equipment, the substrate is unfolded and rotated back and forth, and the impurity gas adsorbed on the surface of the substrate is removed by the vacuum pumping equipment.

In one embodiment, the thickness of the first ITO film layer is 20nm ~ 40nm;

The material of the substrate is polymethyl methacrylate, polyethylene terephthalate or polycarbonate.

In one embodiment, the target material contains 1%-20% SnO ₂ by mass percentage, and the balance is In ₂ O ₃ ;

Or the target material contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ .

In one embodiment, it further includes the operation of depositing a second ITO film layer in a nanocrystalline state on the other surface of the substrate by using the target material.

The above-mentioned ITO substrate includes a substrate and a first ITO film layer deposited on one surface of the substrate, and the first ITO film layer is in a nanocrystalline state. The first nanocrystalline ITO film layer has periodic arrangement of internal ions and is anisotropic, while the amorphous ITO film layer has no periodic arrangement of internal ions and isotropic. Compared with the traditional amorphous ITO film layer, the nanocrystalline first ITO film layer of the ITO substrate has a lower resistivity.

Description of drawings

Fig. 1 is the structural representation of the ITO substrate of an embodiment;

Fig. 2 is the flow chart of the preparation method of ITO substrate as shown in Fig. 1;

Fig. 3 is the X-ray diffraction spectrogram of the ITO substrate that embodiment 1 prepares;

Fig. 4 is an X-ray diffraction spectrum diagram of an ITO substrate prepared in a comparative example.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

As shown in FIG. 1 , an ITO substrate according to one embodiment includes a substrate 10 and a first ITO film layer 20 deposited on one surface of the substrate 10 . The first ITO film layer 20 is in a nano-crystalline state.

The above-mentioned ITO substrate includes a substrate 10 and a first ITO film layer 20 deposited on one surface of the substrate 10 , and the first ITO film layer 20 is in a nanocrystalline state. The first nano-crystalline ITO film layer 20 has anisotropic internal ions arranged periodically, while the amorphous ITO film layer has isotropic internal ion arrangement without periodicity. Compared with the traditional amorphous ITO film layer, the nanocrystalline first ITO film layer 20 of this ITO substrate has lower resistivity and higher conductivity.

The thickness of the first ITO film layer 20 may be 20nm-40nm. The thinner the thickness of the first ITO film layer 20, the better the light transmittance. In the present embodiment, when the thickness of the first ITO film layer 20 is 20nm ~ 40nm, the surface resistance of the first ITO film layer 20 is not Very high, at the same time, the light transmittance is high. In other embodiments, the thickness of the first ITO film layer 20 can be flexibly selected according to needs.

The material of the substrate 10 may be polymethylmethacrylate (polymethylmethacrylate, PMMA), polyethylene terephthalate (polyethylene terephthalate, PET) or polycarbonate (Polycarbonate, PC).

The first ITO film layer 20 contains 1%-20% by mass of SnO ₂ , and the balance is In ₂ O ₃ . Alternatively, the first ITO film layer 20 contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ .

Ti ⁴⁺ in TiO ₂ or Sn ⁴⁺ in SnO ₂ can replace the position of In ³⁺ in the In ₂ O ₃ lattice, thus forming an electron carrier. The greater the carrier concentration, the first ITO film layer The lower the resistivity, but the addition of too large Sn ⁴⁺ or Ti ⁴⁺ ions will form a carrier scattering center, thereby affecting the mobility of carriers, and instead make the resistivity of the first ITO film layer improve. The first ITO film layer 20 comprises SnO ₂ according to mass percentage 1%～20% or TiO ₂ mass percentage 0.3%～5%, when the balance is In ₂ O ₃ , the carrier concentration of the first ITO film layer 20 and high mobility. In other embodiments, the ITO substrate further includes a second ITO film layer deposited on the other surface of the substrate, and the second ITO film layer is in a nanocrystalline state.

The second ITO film layer contains 1%-20% of SnO ₂ according to mass percentage, and the balance is In ₂ O ₃ . Or the second ITO film layer contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ .

The traditional ITO substrate has a single-layer coating structure, which requires two ITO film layers to be bonded together with optical glue, which has the disadvantages of poor bonding and increased cost of optical glue. The first ITO film layer and the second ITO film layer are respectively deposited on the two surfaces of the substrate, which has the advantages of low resistivity and high light transmittance, and can also save the cost of the touch screen.

The thickness of the second ITO film layer may be 20nm-40nm. The thinner the thickness of the second ITO film layer, the better light transmittance, in the present embodiment, when the thickness of the second ITO film layer is 20nm～40nm, the surface resistance of the second ITO film layer is not very high, At the same time, the light transmittance is high. In other embodiments, the thickness of the second ITO film layer can be flexibly selected according to needs.

The preparation method of the above-mentioned ITO substrate shown in Fig. 2 comprises the steps:

S110, providing a substrate 10 and a target.

The material of the substrate can be PMMA, PET or PC.

S120, using a plasma-induced process, when the temperature of the substrate 10 is room temperature, the sputtering power is 4kW~8kW, the flow rate of argon gas is 300sccm~500sccm, the flow rate of oxygen gas is 1sccm~20sccm, and the partial pressure of the impurity gas is less than 5×10 ^-7 torr Under the condition of using the target material to deposit and form the first ITO film layer 20 in a nanocrystalline state on one surface of the substrate 10, an ITO substrate is obtained. The oxygen content has a great influence on the resistivity and light transmittance of the first ITO film layer 20 . Oxygen vacancies in the first ITO film layer 20 are another source of electron carriers, and the first ITO film layer 20 will reduce the resistivity with the increase of oxygen vacancies. The influence of the mobility of the electrons is greater, so that the resistivity of the first ITO film layer 20 increases instead, and the lower the resistivity 20 of the first ITO film layer, the higher the light transmittance. At the same time, if the oxygen content is too low, a black low-valent compound InO will be generated, which will affect the light transmittance of the first ITO film layer 20 .

In this embodiment, the oxygen content is 1sccm-20sccm, and the prepared first ITO film layer 20 has an appropriate amount of free electrons and oxygen holes, and has a low surface resistance. At the same time, the oxygen content is appropriate, and black InO will not be produced, and the obtained first ITO film layer 20 has better light transmittance. In addition, the oxygen content can be properly adjusted according to the sputtering power of the target and the pressure of the argon gas, so that the prepared first ITO film layer 20 has the lowest resistivity after shrinking.

The partial pressure of the impurity gas can be detected by a residual gas analyzer (Residual gas analyzer, RGA). The impurity gases may be _H2O and _CO2 etc. If the partial pressure of H ₂ O and other impurity gases in the chamber monitored by RGA is greater than ×10 ^-7 torr, the substrate can be placed between the winding hub and the unwinding hub in the vacuum equipment, so that the substrate is unfolded and rotated back and forth, The impurity gas adsorbed on the surface of the substrate is removed by vacuum pumping equipment, so as to reduce the pollution of the impurity gas to the first ITO film layer 20 .

The thickness of the first ITO film layer 20 may be 20nm-40nm. The thinner the thickness of the first ITO film layer 20, the better the light transmittance. In this embodiment, the thickness of the first ITO film layer 20 can be 20nm ~ 40nm, and the surface resistance of the first ITO film layer 20 is also Not very high, at the same time, the light transmittance is high. In other embodiments, the deposition rate and deposition time of the first ITO film layer 20 can be adjusted according to needs to prepare the first ITO film layer 20 with a required thickness. The target material contains 1%-20% of SnO ₂ by mass percentage, and the balance is In ₂ O ₃ . Alternatively, the target material contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ .

When SnO ₂ or TiO ₂ in the target is sputtered onto the surface of the substrate 10, Ti ⁴⁺ in TiO ₂ or Sn ⁴⁺ in SnO ₂ can replace the position of In ³⁺ in the In ₂ O ₃ lattice, In ₂ In ³⁺ in O ₃ is positive trivalent, while Sn ⁴⁺ or Ti ⁴⁺ is positive tetravalent, thus forming an electron carrier, the greater the carrier concentration, the lower the resistivity of the film, but too large The addition of Sn ⁴⁺ or Ti ⁴⁺ ions will form a carrier scattering center, thereby affecting the mobility of the carriers, and instead increasing the resistivity of the first ITO film layer. The first ITO film layer 20 comprises SnO ₂ according to mass percentage 1%～20% or TiO ₂ mass percentage 0.3%～5%, when the balance is In ₂ O ₃ , the carrier concentration of the first ITO film layer 20 and high mobility.

S120 may also include an operation of depositing a second nanocrystalline ITO film layer on the other surface of the substrate by using a target material.

The traditional ITO substrate has a single-layer coating structure, which requires two ITO film layers to be bonded together with optical glue, which has the disadvantages of poor bonding and increased cost of optical glue. The first ITO film layer 20 and the second ITO film layer are respectively deposited on the two surfaces of the substrate, which has the advantages of low resistivity and high light transmittance, and can also save the cost of the touch screen.

The electrical conductivity of the first ITO film layer 20 is directly proportional to the carrier concentration and the carrier transfer rate of the first ITO film layer 20 . The carrier concentration of the first ITO film layer 20 is related to the Sn ⁴⁺ content, Ti ⁴⁺ content and O ^2- content in the first ITO film layer 20, in order to obtain a higher carrier concentration can be controlled by the target The content of tin or titanium in and the oxygen content in the plasma-induced process are achieved. The carrier mobility rate is related to the crystallization state, lattice structure and lattice defects of the first ITO film layer 20 . The O ^2- generated by the oxygen in the plasma source can enter the gap in the first ITO film layer 20 and supplement the oxygen hole positions between the In ³⁺ , so that the crystallization of In ₂ O ₃ is more complete, and a higher loading capacity can be obtained. The carrier mobility rate reduces the recombination probability of electrons in the crystal, thereby reducing the resistivity of the first ITO film layer 20 .

The traditional ITO substrate is prepared using the process of magnetron sputtering coating at room temperature, and the ITO prepared at room temperature is amorphous, so the resistivity of the ITO film layer will be very high. To achieve a surface resistance of 150Ω/□, an ITO film layer with a thickness of 80nm needs to be deposited, and the light transmittance of the ITO substrate is about 70%.

The first nanocrystalline ITO film layer deposited at room temperature by adopting plasma-induced process conditions can improve the conductivity of the first ITO film layer and reduce the resistivity of the first ITO film layer. To achieve a surface resistance of 150Ω/□, the thickness of the deposited first ITO film layer needs to be about 20nm~40nm, and the light transmittance can be increased to more than 84%.

The above method adopts plasma-induced process conditions to deposit and form the first nanocrystalline ITO film layer on one surface of the substrate. In the first nano-crystalline ITO film layer, the internal ions are arranged periodically and have anisotropy. The amorphous ITO film layer has no periodicity in the arrangement of its internal ions and is isotropic. Compared with the traditional amorphous ITO film layer, the nanocrystalline first ITO film layer of the ITO substrate has lower resistivity and higher electrical conductivity. At the same time, the above method can also deposit and form a second ITO film layer in a nanocrystalline state on the other surface of the substrate. Compared with the traditional method of using two ITO film layers to be bonded together with optical glue, the production cost of the touch screen can be reduced. .

The following is the specific embodiment part.

Example 1

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 12% by mass of SnO ₂ and the balance of In ₂ O ₃ is used as the cathode.

Using plasma-induced process conditions, the substrate temperature is room temperature, the oxygen flow rate is 13sccm, the partial pressure of impurity gas is 4×10 ^-7 torr, the argon flow rate is 400sccm and the sputtering power is 6kW. A first ITO film layer with a thickness of 35 nm was formed by sputtering on one surface to obtain an ITO substrate with a surface resistance of 170Ω/□ and a resistivity of the ITO film layer of 595 μΩ·cm.

Example 2

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material including 1% SnO ₂ and the balance In ₂ O ₃ is used as the cathode.

Using plasma-induced process conditions, under the conditions that the substrate temperature is room temperature, the oxygen content is 1 sccm, the impurity gas partial pressure is 3×10 ^-7 torr, the argon gas consumption is 300 sccm and the sputtering power is 4kW, a The first ITO film layer with a thickness of 30 nm was formed by sputtering on the surface, its surface resistance was 300Ω/□, and the resistivity of the ITO film layer was 900 μΩ·cm.

Then, a second ITO film layer with a thickness of 30 nm was formed by sputtering on the other surface of the PET substrate according to the method for preparing the first ITO film layer, and an ITO substrate was prepared.

Example 3

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 20% by mass of SnO ₂ and the balance of In ₂ O ₃ is used as the cathode.

Using plasma-induced process conditions, the temperature of the substrate is room temperature, the oxygen content is 20 sccm, the partial pressure of other impurities is 3×10 ^-7 torr, the amount of argon gas is 500 sccm and the sputtering power is 8kW. One surface was sputtered to form an ITO film layer with a thickness of 40nm to obtain an ITO substrate with a surface resistance of 180Ω/□ and a resistivity of the ITO film layer of 720μΩ·cm.

Example 4

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 0.3% by mass of TiO ₂ and the balance of In ₂ O ₃ is used as the cathode.

Using plasma-induced process conditions, under the conditions that the substrate temperature is room temperature, the oxygen content is 6 sccm, the impurity gas partial pressure is 4×10 ^-7 torr, the argon gas consumption is 500 sccm and the sputtering power is 6 kW, a The first ITO film layer with a thickness of 36 nm was formed by sputtering on the surface, its surface resistance was 160Ω/□, and the resistivity of the ITO film layer was 540 μΩ·cm.

Example 5

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 5% by mass of TiO ₂ and the balance of In ₂ O ₃ is used as the cathode.

Using the plasma-induced process conditions, under the conditions that the substrate temperature is room temperature, the oxygen content is 6 sccm, the impurity gas partial pressure is 4×10 ^-7 torr, the argon gas consumption is 400 sccm and the sputtering power is 6 kW, a The first ITO film layer with a thickness of 28 nm was formed by sputtering on the surface, its surface resistance was 160Ω/□, and the resistivity of the ITO film layer was 784 μΩ·cm.

Example 6

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 2.3% by mass of TiO ₂ and the balance of In ₂ O ₃ is used as the cathode.

Using the plasma-induced process conditions, under the conditions that the substrate temperature is room temperature, the oxygen content is 6 sccm, the impurity gas partial pressure is 4×10 ^-7 torr, the argon gas consumption is 500 sccm and the sputtering power is 5 kW, a The first ITO film layer with a thickness of 20 nm was formed by sputtering on the surface, its surface resistance was 400Ω/□, and the resistivity of the ITO film layer was 800 μΩ·cm.

comparative example

The PET substrate with a thickness of 125 μm was plasma-cleaned to remove surface impurities.

A target material comprising 10% by mass of SnO ₂ and the balance of In ₂ O ₃ is used as the cathode.

At room temperature, under the conditions that the oxygen content is 12 sccm, the impurity gas partial pressure is 2×10 ^-6 torr, the argon gas consumption is 500 sccm and the sputtering power is 8KW, a layer with a thickness of 80 nm is sputtered on one surface of a PET substrate. The surface resistance of the first ITO film layer is 150Ω/□, and the resistivity of the ITO film layer is 1200 μΩ·cm.

Figure 3 and Figure 4 are respectively the X-ray diffraction spectrum of the ITO substrate obtained according to the preparation method of Example 1 and the X-ray diffraction spectrum of the ITO substrate prepared in the comparative example. As shown in Figure 3, the diffraction peaks at 30°, 35.5° and 51° are the diffraction peaks of In ₂ O ₃ crystal. Correspondingly, the diffraction peak at 30° is attributed to the diffraction of the [222] crystal plane of In ₂ O ₃ crystal, the diffraction peak of 35.5° is attributed to the diffraction of the [400] crystal plane of In ₂ O ₃ crystal, and the diffraction peak of 51° is attributed to Diffraction from the [440] crystal plane of an In ₂ O ₃ crystal. However, no diffraction peaks of In ₂ O ₃ crystals appear in FIG. 4 , and the prepared ITO film is amorphous. Therefore, the first ITO film layer prepared by plasma-induced process conditions at room temperature has a nanocrystalline structure, while the ITO film layer prepared by traditional magnetron sputtering method at room temperature is amorphous. Compared with the traditional amorphous ITO film layer, the nanocrystalline first ITO film layer of the ITO substrate prepared by plasma-induced process conditions has lower resistivity and higher electrical conductivity.

The above-mentioned embodiments only represent one or several implementations of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (5)

1. a preparation method of ITO substrate, is characterized in that, comprises the steps: Provide substrates and targets; Using plasma-induced process, under the condition that substrate temperature is room temperature, sputtering power is 4kW-8kW, argon flow rate is 300sccm-500sccm, oxygen flow rate is 1sccm-20sccm and impurity gas partial pressure is less than 5×10 ^-7 torr , using the target material to deposit a first nanocrystalline ITO film layer on one surface of the substrate to obtain the ITO substrate; The condition that the partial pressure of the impurity gas is less than 5×10 ^-7 torr is controlled by the following method: the substrate is placed between the winding hub and the unwinding hub in the vacuum equipment, and the substrate is unfolded and rotated back and forth, The impurity gas adsorbed on the surface of the substrate is removed by vacuum pumping equipment. 2. The preparation method of the ITO substrate according to claim 1, wherein the partial pressure of the impurity gas is detected by a residual gas analyzer. 3. The preparation method of the ITO substrate according to claim 1, wherein the thickness of the first ITO film layer is 20nm～40nm; The material of the substrate is polymethyl methacrylate, polyethylene terephthalate or polycarbonate. 4. The method for preparing an ITO substrate according to claim 1, wherein the target material comprises 1% to 20% SnO ₂ by mass percentage, and the balance is In ₂ O ₃ ; Or the target material contains 0.3%-5% TiO ₂ by mass percentage, and the balance is In ₂ O ₃ . 5 . The method for preparing an ITO substrate according to claim 1 , further comprising the operation of depositing and forming a second nanocrystalline ITO film layer on the other surface of the substrate by using the target. 6 .