JP2002047559A - Ito film, and film deposition method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ITO film having a surface roughness (Ra) of <=1 nm without any new manufacturing step such as a polishing step. SOLUTION: This ITO film is manufactured by an ion plating method using a film deposition apparatus comprising a plasma beam generation source and a hearth disposed in a vacuum container and having an incident surface of the plasma beam in which a consistent magnetic field is formed by an annular permanent magnet disposed in the vicinity of the hearth in a concentric manner with the axis of the hearth, the adjusted magnetic field on the consistent magnetic field by an electromagnetic coil disposed concentric with the axis of the hearth to change the magnetic field in the vicinity of the hearth, the plasma beam from the plasma beam generation source is led to an evaporation material for depositing the ITO film to deposit the ITO film, and characterized in that the specific resistance is <=4 μΩm, and the mean surface roughness (Ra) is <=1 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ITO film and a method of forming the same, and more particularly, to an ITO film having improved surface roughness and a method of forming the same.

[0002]

2. Description of the Related Art Electro-optical parts and display elements such as organic E
Characteristics required for a transparent electrode film used for an electrode of an L display include a low specific resistance, a flat film surface, and a high visible light transmittance.

There are various types of transparent electrode films of this kind, and recently, ITO films have attracted attention. When the ITO film is used as a transparent electrode film for an organic EL display, an abnormal discharge due to local electric field concentration can be prevented by flattening the surface morphology of the ITO film, and occurrence of blackout can be suppressed.

[0004]

Generally, the average surface roughness (Ra) of an ITO film formed by sputtering, which is a technique used for forming an ITO film, is about 3 nm. It is considered that this is because in the sputtering method, the crystal growth rate is different and the directionality of the crystal is poor, so that a fine step is formed. However, with such a surface roughness, there is a problem in extending the life of the organic EL display. Therefore, in some cases, an ITO film is formed and then polished to obtain a surface roughness of about 1 nm. However, performing polishing means that the number of manufacturing steps increases.

Therefore, an object of the present invention is to reduce the surface roughness (Ra) to 1 nm without going through a new manufacturing process such as polishing.
An object of the present invention is to provide an ITO film that:

Another object of the present invention is to provide a film forming method capable of forming the above-mentioned ITO film.

[0007]

According to the present invention, there is provided a plasma beam generating source and a hearth arranged in a vacuum vessel and having a plasma beam incident surface, and a center axis of the hearth near the hearth. A stationary magnetic field is formed by an annular permanent magnet arranged concentrically with respect to the center of the hearth, and an adjustment magnetic field is superimposed on the stationary magnetic field by an electromagnetic coil arranged concentrically with respect to the center axis of the hearth, thereby forming a stationary magnetic field near the hearth. A magnetic field is changed, and a film is formed by an ion plating method of forming a ITO film on a substrate by guiding a plasma beam from the plasma beam generation source to an evaporation material for forming an ITO film contained in the hearth, An ITO film having a specific resistance of 4 μΩm or less and an average surface roughness (Ra) of 1 nm or less is provided.

By setting the temperature of the substrate to 150 ° C. or higher, an ITO film having a specific resistance of 1.5 μΩm or less and an average surface roughness (Ra) of 1 nm or less can be obtained.

[0009] Further, by setting the temperature of the substrate to 100 ° C. or less, an amorphous film having an average surface roughness (Ra) of 0.5 nm or less is formed.
An O film is obtained.

[0010] Furthermore, 15
An ITO film characterized by being crystallized by heat treatment at 0 ° C. or more and having an average surface roughness (Ra) of 0.5 nm or less and a low specific resistance is obtained.

Further, SiO 2 is previously formed on the substrate by ion plating or sputtering.
_Thus , an ITO film is obtained, in which _two films are formed and formed on the SiO ₂ film with an average surface roughness (Ra) of 1 nm or less.

According to the present invention, there is also provided a plasma beam generating source, and a hearth disposed in a vacuum vessel and having a plasma beam incident surface, wherein the hearth is concentric with the center axis of the hearth near the hearth. A stationary magnetic field is formed by the arranged annular permanent magnet, and an adjustment magnetic field is superimposed on the stationary magnetic field by an electromagnetic coil arranged concentrically with respect to the center axis of the hearth to change the magnetic field near the hearth, An ion plating method of forming a ITO film on a substrate by guiding a plasma beam from the plasma beam generation source to an evaporation material for forming an ITO film accommodated in the hearth has a specific resistance of 4 μΩm or less and an average surface roughness of less than 4 μΩm. A method for forming an ITO film, characterized in that an ITO film having a thickness (Ra) of 1 nm or less is formed.

In this film forming method, an ITO film having a specific resistance of 1.5 μΩm or less and an average surface roughness (Ra) of 1 nm or less can be formed by setting the temperature of the substrate to 150 ° C. or more.

In the present film forming method, the average surface roughness (R
a) An amorphous film having a thickness of 0.5 nm or less can be formed.

It should be noted that the above amorphous film has
By performing heat treatment at 0 ° C. or more, crystallization is performed, and the average surface roughness (Ra) can be 0.5 nm or less and the specific resistance can be reduced.

In the present deposition method, when the SiO ₂ film is formed in advance by ion plating or sputtering on the substrate, ITO on the SiO ₂ film with an average surface roughness (Ra) 1 nm or less A film can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ion plating apparatus to which the present invention is applied will be described with reference to FIG. Figure 1
, The cylindrical portion 12 provided on the side wall of the vacuum vessel 11
Is mounted with a pressure gradient type plasma beam generator 13. The plasma beam generator 13 includes a glass tube 15 whose one end is closed by a cathode 14. Within this glass tube 15, a disc according LaB ₆ 16, tantalum T
A cylinder 18 of molybdenum Mo having a built-in pipe 17 is fixed to the cathode 14. The pipe 17 is for introducing the carrier gas 10 made of an inert gas such as argon Ar and helium He into the plasma beam generator 13. In this embodiment, oxygen gas is introduced in addition to the carrier gas 10.

First and second intermediate electrodes 19, 2 are provided between the cylindrical portion 12 and the end of the glass tube 15 opposite to the cathode 14.
0 are arranged concentrically. In the first intermediate electrode (first grid) 19, an annular permanent magnet 21 for converging the plasma beam is incorporated. Second intermediate electrode 2
An electromagnet coil 22 for converging the plasma beam is also built in 0 (second grid). The electromagnet coil 22 is supplied with power from a power supply 23.

A steering coil 24 for guiding a plasma beam into the vacuum chamber 11 is provided around the cylindrical portion 12 on which the plasma beam generator 13 is mounted. The steering coil 24 is excited by a power supply 25 for the steering coil. Between the cathode 14 and the first and second intermediate electrodes 19 and 20, there are respectively provided drooping resistors 26 and 2
7, a variable voltage type main power supply 28 is connected.

Referring also to FIG. 2, a main hearth 30 and an annular auxiliary hearth (auxiliary anode) 31 disposed around the main hearth 30 are installed at the bottom inside the vacuum vessel 11. The main hearth 30 is constituted by a cylindrical hearth body 33, and has a concave portion 33 a into which a plasma beam from the plasma beam generator 13 enters. In the through hole of the hearth body 33, I
It contains an evaporant 32 such as a TO (indium-tin oxide) tablet. The auxiliary hearth 31 is constituted by an annular container 34. A hearth coil 36 concentrically laminated with an annular ferrite magnet 35 is housed in the container 34. Main hearth 30 and auxiliary hearth 3
1 is made of a conductive material having good thermal conductivity, for example, copper. The auxiliary hearth 31 is different from the main hearth 30
It is attached via an insulator. The main hearth 3
0 and the auxiliary hearth 31 are connected via a resistor 48. The main hearth 30 is connected to the positive side of the main power supply 28. Therefore, the main hearth 30 includes the plasma beam generator 1.
3 constitutes an anode from which the plasma beam is sucked.

The hearth coil 36 in the auxiliary hearth 31 constitutes an electromagnet, and is supplied from a hearth coil power supply 38 shown in FIG. In this case, the direction of the magnetic field on the center side of the excited hearth coil 36 is configured to be the same as the magnetic field on the center side generated by the ferrite magnet 35. The hearth coil power supply 38 is a variable power supply, and can change the current supplied to the hearth coil 36 by changing the voltage. As shown in FIG. 2, each of the main hearth 30 and the auxiliary hearth 31
Cooling water is supplied so as to flow through cooling water pipes 39 and 40. In the auxiliary hearth 31, only a pipe for supplying cooling water is shown, and a pipe for discharging cooling water is not shown.

Returning to FIG. 1, inside the vacuum chamber 11 is also provided a substrate 4 on which evaporation particles are deposited on the upper part of the main hearth 30.
1 is provided.
The substrate holder 42 is provided with a heater 43 and a cooling unit (not shown). The heater 43 is supplied with power from a heater power supply 44. The cooling unit uses cooling water as a cooling source, and includes a cooling water circulation path. The substrate holder 42 is electrically insulated and supported by the vacuum vessel 11. A bias power supply 45 is provided between the vacuum vessel 11 and the substrate holder 42.
Is connected. As a result, the substrate holder 42 is biased to a negative potential with respect to the vacuum vessel 11 connected to the zero potential. The auxiliary hearth 31 is connected to the positive side of the main power supply 28 via a hearth switch 46. To the main power supply 28, a drooping resistor 29 and an auxiliary discharge power supply 47 are connected in parallel via a switch S1.

In this ion plating apparatus, a discharge occurs between the cathode of the plasma beam generator 13 and the main hearth 30 in the vacuum vessel 11, thereby forming a plasma beam (not shown). This plasma beam reaches the main hearth 30 by being guided by a magnetic field determined by the steering coil 24 and the ferrite magnet 35 in the auxiliary hearth 31. The evaporating substance 32 stored in the main hearth 30 is heated by the plasma beam and evaporates. The evaporated particles are ionized by the plasma beam and adhere to the surface of the substrate 41 to which the negative voltage is applied, forming an ITO film.

By changing the current supplied to the hearth coil 36 laminated concentrically with the ferrite magnet 35, the film thickness distribution on the surface of the substrate 41 and the film formation speed can be adjusted. The positional relationship between the ferrite magnet 35 and the hearth coil 36 may be upside down from the relationship shown in FIG. 1, and the direction of the magnetic poles of the ferrite magnet 35 may be opposite to the direction shown in FIG.

In this embodiment, an ITO film is formed on the substrate 41 by the above-described ion plating apparatus while supplying oxygen gas using ITO as an evaporation material. By controlling the film forming conditions, an ITO film having a specific resistance of 4 μΩm or less and a surface roughness (Ra) of 1 nm or less can be formed.

For example, when a film is formed at a substrate temperature of 150 ° C. or more, the specific resistance is 1.5 μΩm or less and the surface roughness (Ra) is 1
It is possible to form an ITO film of nm or less.

When the film is formed at a substrate temperature of 100 ° C. or less, the specific resistance is 4 μΩm or less and the surface roughness (Ra) is 0.5 n.
m or less can be formed as an ITO film.

An amorphous film is formed at a substrate temperature of 100 ° C. or less, and then crystallized by a heat treatment, so that the specific resistance is 2.5 μΩm or less and the surface roughness (Ra) is reduced.
An ITO film having a thickness of 0.5 nm or less can be formed. This is because the specific resistance decreases as the temperature of the substrate 41 increases.

An embodiment of the present invention will be described below.

(Embodiment 1) In the above-described ion plating apparatus, the pressure in the vacuum vessel 11 is 3 × 10 ⁻³ Torr.
r, partial pressure of oxygen gas 3 × 10 ⁻⁴ Torr, discharge current 15
An ITO film having a thickness of 150 nm was formed on a glass substrate at 0 A and a substrate temperature of 200 ° C. At this time, the specific resistance is 1.4 μΩm,
A surface roughness (Ra) of 0.67 nm (measured by an atomic force microscope (AFM)) was obtained.

(Embodiment 2) In the above ion plating apparatus, the pressure in the vacuum vessel 11 is 3 × 10 ⁻³ Torr.
r, partial pressure of oxygen gas 3 × 10 ⁻⁴ Torr, discharge current 15
An ITO film having a thickness of 150 nm was formed on a glass substrate at 0 A and a substrate temperature of 60 ° C. The film obtained in this case is an amorphous film. At this time, the specific resistance was 4 μΩm and the surface roughness (R
a) 0.15 nm (however, measured with an atomic force microscope (AFM)) was obtained.

(Embodiment 3) In the above-mentioned ion plating apparatus, a discharge current of 150 A, a substrate temperature of 60.degree.
After forming the O film, a heat treatment was performed at 200 ° C. for 30 minutes to crystallize the amorphous film. At this time, the specific resistance is 2.1 μΩ
m and a surface roughness (Ra) of 0.15 nm (measured by an atomic force microscope (AFM)) were obtained.

The heat treatment in the third embodiment is
The heat treatment may be performed in the vacuum vessel 11 using the heater 43, or may be taken out of the vacuum vessel 11 and performed in another annealing apparatus. Alternatively, when a processing device for the next step is provided adjacent to the vacuum container 11, the vacuum container 11 and the processing device are often performed through a passage sealed with the atmosphere. Heat treatment can be performed in the passage.

Further, in Examples 2 and 3 described above, the water was 2 ×
By adding at 10 ^-5 Torr, the surface roughness can be improved. This is because fine crystals may be formed in the amorphous film, which adversely affects the surface roughness, but such fine crystals are lost by the addition of water.

The reason why a flat film having a surface roughness of 1 nm or less can be obtained in the present invention is considered to be related to the following. In the ion plating method by Haas, in which an auxiliary anode in which a ferrite magnet 35 and a Haas coil 36 are combined is arranged around the plasma beam generator 13 and the surroundings, the ionization rate of the evaporated particles is very high, that is, the ITO evaporated material is mostly In ion , Sn ions, and oxygen ions, and many of these ions are accelerated at a potential corresponding to the main hearth potential (specifically, about 20 V depending on the film formation conditions), and have high and relatively uniform energy. It is thought to be beaten. This is presumed to be a factor for obtaining a dense and flat film. Substrate 41
At a high temperature of 150 ° C. or higher, a film having extremely good crystal orientation was obtained. Extremely good orientation is considered to be a factor of good flatness regardless of the polycrystalline film.

In each of the above embodiments, the IT
Although the case where the O film is formed, the case where the substrate is a plastic substrate is also applicable. At this time, the substrate temperature is 100 ° C.
Since it is generally not preferable to perform the above heating, the ITO film forming conditions according to the second embodiment are mainly applied. When using a plastic substrate, as shown in FIG.
First, an SiO ₂ film 52 is formed on the substrate 1 (to impart a water or gas shielding property to the substrate and increase the smoothness of the substrate surface), and it is preferable to form an ITO film 53 thereon. In this case, the ITO film 53 has an average surface roughness (Ra).
1 nm or less can be obtained. In some cases, it is preferable to first form an SiO ₂ film even on a glass substrate. The formation of the SiO ₂ film may be performed by any of the well-known sputtering method and ion plating method.

[0037]

According to the present invention, an ITO film having a surface roughness (Ra) of 1 nm or less can be provided without going through a new manufacturing process such as polishing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an ion plating apparatus to which the present invention is applied.

FIG. 2 is a diagram showing an internal structure of a main hearth shown in FIG. 1 and an auxiliary hearth arranged around the main hearth.

FIG. 3 is a cross-sectional view when an ITO film is formed on a plastic substrate according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Carrier gas 11 Vacuum container 13 Plasma beam generator 14 Cathode 15 Glass tube 19 1st intermediate electrode 20 2nd intermediate electrode 24 Steering coil 28 Main power supply 30 Main hearth 31 Auxiliary hearth 35 Ferrite magnet 36 Hearth coil 51 Plastic substrate 52 SiO ₂ film 53 ITO film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K029 BA45 BA46 BA50 BB02 BB10 BC09 CA05 DD05 GA01 5G307 FA01 FB01 FC03 FC10 5G323 BA02 BB04 BC03

Claims (10)

[Claims] An annular permanent magnet including a plasma beam generating source and a hearth disposed in a vacuum vessel and having a plasma beam incident surface, and disposed concentrically with a center axis of the hearth near the hearth. Form a stationary magnetic field with a magnet,
The adjusting magnetic field is superimposed on the stationary magnetic field by an electromagnetic coil arranged concentrically with respect to the center axis of the hearth to change the magnetic field near the hearth, and the plasma beam from the plasma beam source is applied to the hearth. The contained ITO
The film is formed by an ion plating method in which an ITO film is formed on a substrate by being led to an evaporation material for film formation, and has a specific resistance of 4 μm.
An ITO film having an average surface roughness (Ra) of 1 nm or less and an average surface roughness (Ra) of 1 nm or less. 2. The ITO film according to claim 1, wherein the substrate has a temperature of 150.degree.
An ITO film having an average surface roughness (Ra) of at most 5 μΩm and an average surface roughness (Ra) of at most 1 nm. 3. The ITO film according to claim 1, wherein said substrate is formed as an amorphous film having an average surface roughness (Ra) of 0.5 nm or less by setting the temperature of said substrate to 100 ° C. or less. ITO film. 4. The ITO film according to claim 3, wherein the amorphous film is crystallized by performing a heat treatment at 150 ° C. or more to have an average surface roughness (Ra) of 0.5 nm.
IT characterized by a low specific resistance
O film. 5. The ITO film according to claim 1, wherein an SiO ₂ film is formed on the substrate in advance by an ion plating method or a sputtering method.
An ITO film formed on the SiO ₂ film with an average surface roughness (Ra) of 1 nm or less. 6. An annular permanent magnet including a plasma beam generation source and a hearth disposed in a vacuum vessel and having a plasma beam incident surface, and disposed concentrically with a center axis of the hearth near the hearth. Form a stationary magnetic field with a magnet,
The adjusting magnetic field is superimposed on the stationary magnetic field by an electromagnetic coil arranged concentrically with respect to the center axis of the hearth to change the magnetic field near the hearth, and the plasma beam from the plasma beam source is applied to the hearth. The contained ITO
An ITO film having a specific resistance of 4 μΩm or less and an average surface roughness (Ra) of 1 nm or less is formed by an ion plating method in which an ITO film is formed on a substrate by leading to an evaporation material for film formation. Method of forming an ITO film. 7. The film forming method according to claim 6, wherein the specific resistance is set at 1.degree.
IT with 5 μΩm or less and average surface roughness (Ra) of 1 nm or less
A method for forming an ITO film, comprising forming an O film. 8. The film forming method according to claim 6, wherein an amorphous film having an average surface roughness (Ra) of 0.5 nm or less is formed by setting the temperature of the substrate to 100 ° C. or less. Method of forming an ITO film. 9. The film forming method according to claim 8, wherein the amorphous film is crystallized by performing a heat treatment at 150 ° C. or more to have an average surface roughness (Ra) of 0.5 nm.
IT characterized by a low specific resistance
A method for forming an O film. 10. The film forming method according to claim 6, wherein an SiO ₂ film is formed on the substrate in advance by an ion plating method or a sputtering method, and the SiO ₂ film has an average surface roughness (Ra) of 1 nm or less. _{2. A} method for forming an ITO film, comprising forming an ITO film on the film.