JPH09194232A - Substrate formed with ito film and formation of ito film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming the above film which is sufficiently thin and is low in resistance as an ITO film to be formed on a color filter substrate for a large-sized color liquid crystal display device of high performance. SOLUTION: A discharge voltage is set at >=70 to <100V by using a vapor deposition apparatus having a plasma beam generating section 30, a hearth 20 to be set with a material to be evaporated and an auxiliary hearth 21 contg. an annular permanent magnet and annular electromagnetic coil arranged around this hearth coaxially with the hearth, by which the ten point average roughness (R1 value) of the surface of the ITO film formed on the surface of a substrate W is made to attain >=4.0 to <15.0nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate having an ITO (indium tin oxide) film formed on its surface using a plasma processing apparatus, and a method for forming an ITO film on the substrate.

[0002]

2. Description of the Related Art An ITO film is excellent as a transparent electrode formed on a color filter substrate for a liquid crystal display, and an ITO film is also formed as a conductive film on a resin substrate. As a method for forming such an ITO film, a vacuum vapor deposition method, a sputtering method, and an RF (high frequency) ion plating method have been conventionally known, but an ITO film is formed on a glass substrate or a resin substrate provided with a color filter. In this case, the substrate temperature is kept at 200 ° C. or higher.

[0003]

By the way, in the color liquid crystal display, from the viewpoint of high resolution and high transmittance, it is required to reduce the film thickness of the transparent electrode, and the size is increased.
From the viewpoint of increasing the response speed, it is required to reduce the resistance of the transparent electrode.

However, since the temperature of the ITO film formed by the conventional apparatus or film forming method is limited to 200 ° C. or lower, the reaction and crystallization of indium and oxygen on the substrate are not sufficiently performed, As a result, the crystal grain size is small,
A film with many defects is formed. Then, since the defects capture carrier electrons, the carrier electron concentration in the film is reduced, and an ITO film having a low resistivity (2.0 × 10 ⁻⁴ Ωcm) required for a color liquid crystal display can be obtained. However, this is an obstacle to manufacturing a large-sized and high-performance color liquid crystal display.

[0005]

In order to solve the above problems, a substrate having an ITO film according to the present invention is formed on the surface of the substrate on the assumption that the following vapor deposition apparatus and vapor deposition conditions are adopted. The 10-point average roughness (RZ value) of the surface of No. 1 was 4.0 nm or more and less than 15.0 nm.

The presumed vapor deposition apparatus comprises a plasma beam generator, a hearth for setting a substance to be vaporized, and an annular permanent magnet and an annular electromagnetic coil arranged around the hearth and coaxially with the hearth. The vapor deposition condition is that the substance to be vaporized is a mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ), and the annular electromagnetic coil is applied to the magnetic field formed by the annular permanent magnet. The magnetic field formed by the above is superposed, and in this state, the plasma beam from the plasma beam generating unit is irradiated to the mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ).

The method of forming an ITO film according to the present invention is
The discharge voltage for generating the plasma beam was set to 70 V or more and less than 100 V on the assumption that the same vapor deposition apparatus and vapor deposition conditions as described above were used.

By setting the discharge voltage to 70 V or more and less than 100 V, the 10-point average roughness (R _Z value) of the surface of the ITO film formed on the substrate surface can be 4.0 nm or more and less than 15.0 nm. , R _Z value is 4.0 nm or more and 15.0 n
When it is less than m, the number of defects in the film that captures carrier electrons is reduced, and the resistance value of the film can be lowered.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a diagram showing an entire configuration of a vapor deposition apparatus used for forming an ITO film according to the present invention on a substrate. The vacuum container 1 has an exhaust port 2 on one side and a plasma beam on the other side. The generator 3 is provided.

Plasma beam generator 3 used in this embodiment
Incorporates a composite cathode type and pressure gradient type plasma beam generation mechanism. The compound cathode type plasma beam generation mechanism concentrates the initial discharge on the auxiliary cathode with a small heat capacity, uses it to heat the main cathode, and makes the main cathode the final cathode for efficient arc discharge. In the pressure gradient type plasma beam generating mechanism, an intermediate electrode is interposed between the cathode and the anode (hearth), and the cathode region is set to 1
By performing discharge while maintaining the anode region at 10 ^-4 torr or more to torr, damage to the cathode due to backflow of ions from the anode region is prevented, and since the gas efficiency of the carrier gas is high,
It enables large current discharge.

A plasma beam generator 3 having such a composite cathode type and pressure gradient type plasma beam generating mechanism.
The auxiliary electrode 6 is held on the cylindrical body 4 via the heat shield 5, and the auxiliary electrode 6 uses a high melting point metal pipe such as W, Ta or Mo. A pipe 7 for sending a carrier gas such as Ar into the plasma beam generator 3 is connected to the rear end of the auxiliary electrode 6.

A disk-shaped main electrode 8 is provided at the tip of the cylindrical body 4.
Is attached, the tip of the auxiliary electrode 6 extends through the hole at the center of the main electrode 8 toward the film forming chamber S side, and an annular permanent magnet is provided at a portion closer to the film forming chamber S side than the main electrode 8. A first intermediate electrode 9 (first grid) incorporated, a second intermediate electrode 10 (second grid) incorporating a coil, and a steering coil 11 are provided, and the cathode (main electrode 7) and the first and first electrodes are provided. 2 intermediate electrodes 9 and 10, and drooping resistors 12 and 13
A variable voltage type main power source 14 is connected via the.

An auxiliary discharge power source 15 and a drooping resistor 16 are connected in parallel to the main power source 14 via a switch 17, and the coil built in the second intermediate electrode 9 is the power source 1
8, the steering coil 11 is excited by the power supply 19.

A main hearth 20 and an auxiliary hearth 21 made of a conductive material having a high thermal conductivity such as copper are arranged at the bottom of the vacuum container 1. The main hearth 20 is the main power source 14
Since it is connected to the positive side of the
Against the anode. Therefore, the plasma beam generated by the plasma beam generator 3 is converged by the first intermediate electrode 9 and the second intermediate electrode 10, guided by the steering coil 11 to the vacuum container 1, and incident on the main hearth 20. On the upper surface of the main hearth 20 on which the plasma beam is incident, a recess for setting an ITO (indium tin oxide) tablet 22 which is a substance to be evaporated is formed.

On the other hand, the auxiliary hearth 21 is made of a conductive material having a high thermal conductivity such as copper, like the main hearth 20, and
An annular permanent magnet 23 and a hearth coil 24 are coaxially laminated in an annular container surrounding the main hearth 20, the hearth coil 24 is connected to a variable power source 25, and the hearth coil 24 is applied to the magnetic field formed by the permanent magnet 23. The magnetic fields formed by For example, the magnetic field on the center side generated by the permanent magnet 23 and the hearth coil 2
The magnetic field on the center side of 4 should have the same direction.

Further, a heater 26 for heating the substrate W is arranged in the upper part of the vacuum container 1, and the substrate W can be moved horizontally by a moving mechanism (not shown).

In the above, the plasma beam generated by the plasma beam generator 3 is made incident on the ITO tablet 22 set on the upper surface of the main hearth 20 to evaporate the metal particles from the ITO tablet 22 as shown in FIG. Ionizing the evaporated metal particles, causing the ionized metal particles to undergo an oxidation reaction on the surface of the substrate W,
The ITO film 27 is formed on the surface of the substrate W. Here, the flight pattern of the ionized metal particles can be adjusted by changing the current value passed from the variable power source 25 to the hearth coil 24, and the ITO film 2 having a uniform thickness on the surface of the substrate W.
7 can be formed.

The vapor deposition apparatus is not limited to the above-mentioned one, but may be the one shown in FIG. That is, FIG.
(A) is a plan view showing a schematic configuration of a vapor deposition apparatus, (b) is a side view showing a schematic configuration, the vapor deposition apparatus is a vacuum container 1
A rotating body 30 is provided inside, and a plurality of substrates W are attached to this rotating body 30, and a plasma beam generator 3 is arranged on the ceiling of the vacuum container 1 and a hearth 20 is arranged on the side wall of the vacuum container 1. The place where the hearth is provided is not limited to the above example, and may be any place as long as it is on the extension line of the plasma beam from the plasma beam generator.

Next, specific examples and comparative examples using the vapor deposition apparatus shown in FIG. 1 will be described. (Example 1) Conditions Tablet: ITO sintered body with 5 wt% Sn added Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 98 V Discharge current: 150A Film forming pressure: 2.0 × 10 ⁻³ torr Oxygen partial pressure: 0.6 × 10 ⁻³ torr Characteristics of ITO film formed under the above conditions Thickness: 279 nm 10-point average roughness (R _Z value) : 4.0 nm Linear transmittance: 85% for light with a wavelength of 550 nm Resistivity: 1.30 × 10 ⁻⁴ Ω · cm

(Example 2) Conditions Tablet: ITO sintered body containing 5 wt% of Sn Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 90 V Discharge current: 150 A Pressure during film formation: 1.8 × 10 ⁻³ torr Oxygen partial pressure: 0.9 × 10 ⁻³ torr Characteristics of ITO film formed under the above conditions Thickness: 280 nm 10-point average roughness (R _Z value): 7.0 nm Linear transmittance: 86% for light having a wavelength of 550 nm Resistivity: 1.20 × 10 ⁻⁴ Ω · cm

(Example 3) Conditions Tablet: ITO sintered body containing 5 wt% of Sn Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 70 V Discharge current: 150 A Pressure during film formation: 3.5 × 10 ⁻³ torr Oxygen partial pressure: 1.2 × 10 ⁻³ torr Characteristics of ITO film formed under the above conditions Thickness: 285 nm 10-point average roughness (RZ Value): 13.0 nm Linear transmittance: 85% for light with a wavelength of 550 nm Resistivity: 1.40 × 10 ⁻⁴ Ω · cm

Comparative Example 1 Conditions Tablet: ITO sintered body containing 5 wt% Sn added Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 60 V Discharge current: 150 A Pressure during film formation: 4.0 × 10 ⁻³ torr Oxygen partial pressure: 2.0 × 10 ⁻³ torr Characteristics of ITO film formed under the above conditions Thickness: 283 nm 10-point average roughness (R _Z value): 15.0 nm Linear transmittance: 83% for light with a wavelength of 550 nm Resistivity: 1.70 × 10 ⁻⁴ Ω · cm

Comparative Example 2 Conditions Tablet: ITO sintered body containing 5 wt% of Sn Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 105 V Discharge current: 150 A Pressure during film formation: 0.6 × 10 ^-3 torr Oxygen partial pressure: 0.3 × 10 ^-3 torr Characteristics of ITO film formed under the above conditions Thickness: 283 nm 10-point average roughness (R _Z value): 2.0 nm Linear transmittance: 86% for light with a wavelength of 550 nm Resistivity: 1.90 × 10 ⁻⁴ Ω · cm

Here, the 10-point average roughness (R _Z value) means L: reference length R ₁ as shown in FIG. 4 (the unevenness of the ITO film is exaggerated for easy understanding). _{, R 3, R 5, R} 7, R 9: elevation R 2 summit from the best extraction portion corresponding to the reference length L to the _{fifth, R 4, R 6, R} 8, R 10: reference length Elevation of the valley bottom from the deepest to the fifth part of the sampling portion corresponding to L RZ value = {(R ₁ + R ₃ + R ₅ + R ₇ + R ₉ ) − (R ₂ + R ₄ + R ₆ + R
₈ + R ₁₀ )} / 5.

FIG. 5 is a graph showing the relationship between the resistivity (Ω · cm) and the RZ value prepared based on the above-mentioned Examples and Comparative Examples. As is clear from this graph, a color filter for liquid crystal display. To satisfy the resistivity required for the transparent electrode formed on the substrate, the R _Z value is 4.0 n.
It is understood that the thickness should be not less than m and less than 15.0 nm.

FIG. 6 is a graph showing the relationship between the R _Z value and the discharge voltage. As is clear from this graph, in order to make the R _Z value 4.0 nm or more and less than 15.0 nm, the discharge voltage is 70 V. It turns out that the voltage should be 100 V or less.

Next, regarding the average value and standard deviation of Sn / In and the average value and standard deviation of resistivity, the apparatus according to the present invention (with auxiliary hearth) and the conventional apparatus (without auxiliary hearth) shown in FIG. 1 were used. The case of forming a film by using is shown in (Table 1) and (Table 2) below. The film forming conditions are as follows, and the substrate 10
The sheet was moved at a constant speed every 5 minutes. Conditions Tablet: ITO sintered body added with 5 wt% of Sn Substrate: 30 cm square, 1.1 mm thick soda lime glass substrate with color filter Substrate heating temperature: 200 ° C. Discharge voltage: 70 V to 100 V (90 V) Discharge current: 150A Discharge gas: Ar (30 sccm) Reaction gas: O ₂ (50 sccm)

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

According to the present invention as described above,
As a vapor deposition device, a plasma beam generator, a hearth for setting a substance to be vaporized, and an annular permanent magnet and an annular electromagnetic coil arranged coaxially with the hearth around the hearth are provided. Type and pressure gradient type were combined and a hearth with a plasma correction function was used, so the current density immediately above the ITO source was increased, and the ion density could be increased (10 ¹¹ / CC or more) and in the plasma. The activity of the film-constituting atoms and molecules is increased, and the oxidation reaction (film formation) on the substrate is sufficiently performed.

In particular, by setting the discharge voltage for generating the plasma beam as low as 70 V or more and less than 100 V, damage to the film growth surface due to positive ions can be reduced and appropriate implantation of positive ions can be performed. The surface roughness (RZ value) is 4.0 nm or more and 15.0 or more, which is dense and has a strong bond between crystal grains, and has a large crystal grain size, and thus has few defects in the film capturing carrier electrons.
It is possible to obtain an ITO film having a thickness of less than nm.

Since the ITO film is thin and has a uniform and low resistance as shown in (Table 1) and (Table 2), it is applied to a liquid crystal display or the like in which a current flows parallel to the substrate. Is extremely effective.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of a vapor deposition apparatus used for forming an ITO film on a substrate according to the present invention.

FIG. 2 is a diagram showing the evaporation state of metal particles from an ITO tablet.

3A is a plan view showing a schematic configuration of a vapor deposition apparatus according to another embodiment, and FIG. 3B is a side view showing a schematic configuration of the vapor deposition apparatus.

FIG. 4 is a diagram used to explain 10-point average roughness (RZ value).

FIG. 5 is a graph showing the relationship between resistivity and 10-point average roughness (RZ value).

FIG. 6 is a graph showing the relationship between 10-point average roughness (RZ value) and discharge voltage.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 3 ... Plasma beam generator, 6 ... Auxiliary electrode, 8 ... Main electrode, 9 ... 1st intermediate electrode, 10 ... 2nd intermediate electrode, 11 ... Steering coil, 14 ... Main power supply, 2
0 ... main hearth, 21 ... auxiliary hearth, 22 ... ITO tablet, 23 ... permanent magnet, 24 ... hearth coil, 27 ... I
TO film, W ... Substrate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsu Tanaka 5-2 Sokai-cho, Niihama-shi, Ehime Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (72) Toshiyuki Sakami 5-2 Sokai-cho, Niihama-shi, Ehime No. Sumitomo Heavy Industries, Ltd. Niihama Works

Claims (2)

[Claims] 1. A vapor deposition apparatus comprising a plasma beam generator, a hearth for setting a substance to be evaporated, and an annular permanent magnet and an annular electromagnetic coil which are arranged around the hearth and coaxially with the hearth. The substance to be evaporated is a mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ), and the magnetic field formed by the annular electromagnetic coil is superposed on the magnetic field formed by the annular permanent magnet. The mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) is irradiated with the plasma beam from the plasma beam generator to evaporate and ionize it, and this is deposited on the surface as an ITO (indium tin oxide) film. The substrate according to the above I
10-point average roughness (RZ value) of the surface of the TO film is 4.0 nm
A substrate on which an ITO film is formed, which is not less than 15.0 nm. 2. A vapor deposition apparatus provided with a plasma beam generator, a hearth for setting a substance to be vaporized, and an annular permanent magnet and an annular electromagnetic coil arranged coaxially with the hearth around the hearth, The substance to be evaporated is a mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ), and the magnetic field formed by the annular electromagnetic coil is superposed on the magnetic field formed by the annular permanent magnet. ITO for irradiating a mixture of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) with a plasma beam from a plasma beam generating unit to vaporize and ionize it, and to attach the vaporized and ionized substance to the substrate A method of forming an (indium tin oxide) film, characterized in that a discharge voltage for generating the plasma beam is set to 70 V or more and less than 100 V. Forming method that ITO film.