JPS6224506A - Formation of light transmitting conductive film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for forming a light-transmitting conductive film. More specifically, the present invention relates to a method of forming a light-transparent conductive film on a light-transparent substrate formed of glass, polymeric material, or the like.

<Prior Art> Conventionally, display elements such as liquid crystal displays, electroluminescent displays, electrochromic displays, etc. ! Light-transmitting conductive films are used as window electrode materials for photoelectric conversion elements such as batteries.

The light-transmitting conductive film can be classified into those using a gold fi thin film such as gold, silver, platinum, or palladium, and those using a metal oxide thin film such as indium oxide or tin oxide. The former has the advantage that it is easy to obtain a low sheet resistance, but has the disadvantage that a film with high light transmittance cannot be easily obtained. On the other hand, with the latter, a film with excellent light transmittance can be easily obtained, but has the disadvantage that the sheet resistance becomes somewhat large. It is desirable for a light-transmitting conductive film to have excellent properties in both light transmittance and sheet resistance, but there is no material that fully satisfies both, and generally,
The material is selected as appropriate depending on the required characteristics, and the material that is currently widely used is the latter metal oxide film.

As methods for forming these light-transmitting conductive films, methods for forming light-transparent conductive films by vacuum evaporation, sputtering, and the like are conventionally known and are also practiced industrially.

<Problems to be Solved by the Invention> In the above-mentioned vacuum evaporation method, indium oxide or tin oxide is used as an evaporation raw material and is heated and evaporated to be deposited on the substrate, so the evaporation rate is slow and the required evaporation particle size is low. In order to obtain the desired amount, the crucible must be heated to a considerably high temperature, which also poses a problem in terms of the durability of the crucible.

On the other hand, in sputtering methods, there are two methods: sputtering using indium oxide or tin oxide as a target, and methods using simple metals such as indium or tin as targets, but in both methods, the substrate is not immersed in plasma. Because of the exposure, the film is seriously damaged at the same time as it is formed.
There are also problems such as sputtering gas being taken into the film. Furthermore, a mixture of argon and oxygen is generally used as the sputtering gas, but since the film quality is greatly affected by the composition and partial pressure of the sputtering gas, it is necessary to sequentially control the composition and partial pressure of the sputtering gas. This is a major problem in industrial implementation.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a novel method for forming a light-transmitting conductive film that can improve productivity and has excellent light transmittance and conductivity.

Means for Solving the Problems> The method for forming a light-transmitting conductive film according to the invention, which was made to solve the above problems, involves heating in a vacuum chamber with a vacuum degree of 10-5 Torr or less. Introducing oxygen gas to have a partial pressure of 5 × 10 to IX 10 Torr near the transparent substrate, and heating a closed crucible with a nozzle supplied with indium or tin or a mixture thereof, The method is characterized in that evaporated particles are ejected from a nozzle to form an oxide film of the metal on the substrate.

The substrate used in this invention is not particularly limited as long as it has light transmittance, and examples thereof include glass, polymer molded bodies (plates, films, sheets, etc.), and the like.

By using polymer films, sheets, etc. with excellent flexibility as substrates, it is possible to obtain flexible light-transmitting conductive films that are used in flexible liquid crystal panels, etc., and which require flexibility. Glass with poor flexibility,
By using a polymer plate or the like as a substrate, it is possible to obtain a light-transmitting conductive film that is used in solar cells and the like and does not require flexibility.

Heating of the substrate is performed to oxidize the film formed on the substrate and convert it into an oxide (In2O3 and 5nO2) film of the metal. When the substrate is not heated, the film formed is a low-grade oxide film of the above-mentioned metal, which has poor light transmittance and unfavorable electrical conductivity. This heating temperature is not particularly limited, and may be appropriately selected depending on the heat resistance of the substrate material used. Generally, if the temperature is set at 100 to 400°C, the lower oxide film formed on the substrate can be effectively oxidized.

The oxygen gas partial pressure used is 5X 10' to IX 10-
A range of 3 Torr is preferred. If the oxygen gas partial pressure is below this range, oxidation will be insufficient, and if it is above this range, the film formation rate will be extremely slow.

The number of nozzles provided in the closed crucible may be one or more, and the evaporated particles ejected from the nozzles can be set to either a cluster flow or a molecular flow depending on the set value of the heating temperature. It is possible. The evaporated particles, which have become a cluster flow or a molecular flow, are ejected from the nozzle and have kinetic energy that is convenient for film formation on the substrate. ! ! ! A light-transmitting conductive film having excellent W properties can be obtained.

In addition, the evaporated particles ejected from the nozzle may be ionized by being bombarded with an electron beam generated from an electron beam generator, and the ionized evaporated particles are accelerated by an electric field to further increase their kinetic energy and have a negative potential. A film may be formed on the substrate. By ionizing in this manner, a light-transmitting conductive film with even better adhesion between the substrate and the film can be obtained.

Antimony, molybdenum, tungsten, or the like may be added to indium, tin, or a mixture thereof supplied to the crucible to improve conductivity.

The thickness of the light-transmitting conductive film thus formed on the substrate is not particularly limited, and is appropriately selected depending on the purpose of use.

Function> The present invention has the above-described configuration, and evaporated particles are ejected from a heated crucible to form a film on a heated substrate and are oxidized to become a metal oxide film. Therefore,
As the evaporation raw material for metal oxide film formation, elemental metals such as indium, tin, or a mixture thereof can be used instead of the metal oxide itself, so the evaporation rate is fast and the required evaporation rate can be achieved without raising the temperature too high. The amount of particles can be obtained, and the durability of the crucible can be improved.

In addition, since a closed crucible is used, the evaporated particles ejected from the nozzle as a cluster flow or molecular flow have kinetic energy that is convenient for film formation, which improves the film formation rate and the adhesion of the film. You can improve your sexuality.

Furthermore, by ionizing the evaporated particles, the adhesion can be further improved.

<Example> Hereinafter, the method according to the present invention will be explained in more detail based on Examples.

The drawing shows a schematic diagram of an example of an apparatus used in the method for forming a light-transmitting conductive film according to the present invention.

At the bottom of the vacuum chamber (1) maintained at a vacuum level of 10'Torr or less, there is a closed crucible (11) equipped with a nozzle supplied with indium, tin, or a mixture thereof, and for heating the crucible (11). crucible heating heater (
9) is located. The metal in the crucible heated by the crucible heater (9) becomes evaporated particles and is ejected from the nozzle (2).

This example device includes an electron beam generating filament (8) for ionizing evaporated particles, an electron extraction electrode (
A blade and an ion accelerating electrode (6) are provided, and the evaporated particles ejected from the nozzle (10) of the closed crucible (11) are bombarded with an electron beam, ionized, and further accelerated by an electric field. The ionized evaporated particles are transferred to a substrate (3) fixed to a substrate holder (2) provided at the top of a vacuum chamber (1).
) (which has a negative potential) and is oxidized by oxygen introduced from the oxygen introduction tube (4) provided near the substrate (3), becoming a lower oxide film of the metal, Further, since the substrate (3) is heated by the substrate heater (13) provided on the upper part of the substrate holder (2), the formed lower oxide film is thermally oxidized and becomes the metal oxide film. - converted.

The introduction position of the oxygen gas is provided near the substrate (3) as illustrated in the attached drawing in order to effectively form a film while efficiently oxidizing the gold a film formed on the substrate (3). Preferably, for example, the flange (12) in the accompanying drawings
When oxygen gas is introduced in the vicinity of , the effect of oxygen is significantly reduced.

The apparatus used in the method of the present invention is not limited to the above-mentioned example of the apparatus; for example, the gist of the present invention may be modified, such as by removing the apparatus necessary for ionizing the evaporated particles from the above-mentioned example of the apparatus. Any device can be used as long as it does not.

Example 1 5 g of indium was supplied to a closed crucible (number of nozzles: 1), and the substrate was a glass plate with a thickness of 0.5 m (visible light transmittance of 92
%) was established. An indium oxide (In203) film of 700% was formed under the conditions shown in Table 1, and the visible light transmittance was 88% and the sheet resistance was 480Ω/hole (Ω/hole means the resistance value per unit square centimeter). A light-transmissive conductive film (the same applies hereinafter) was obtained.

Example 2 5 g of tin was supplied to a closed crucible (number of nozzles: 4),
The substrate is a glass plate with a thickness of 0.45 M (visible light transmittance 93
%) was established. A 1000A tin oxide (SnO2) film was formed under the conditions shown in Table 1, and the visible light transmittance was 83%.
A light-transmitting conductive film with a sheet resistance of 820 Ω/hole was obtained.

Example 3 5 g of indium was supplied to a closed crucible (6 nozzles), and a 100 μm thick polyester film (
Visible light transmittance α4%) was installed. A 1200A indium oxide film was formed under the conditions shown in Table 1 to obtain a light-transmitting conductive film with a visible light transmittance of 84% and a sheet resistance of 330Ω/hole.

Example 4 5 g of indium was supplied to a closed crucible (number of nozzles: 4), and a glass plate (visible light transmittance: 92%) with a thickness of 0.5 #llN was placed on the substrate. An indium oxide film having a thickness of 600 mm was formed under the conditions shown in Table 1 to obtain a light-transmitting conductive film having a visible light transmittance of 87% and a sheet resistance of 580 Ω/hole.

Comparative Example 1 5 U of indium was supplied to a closed crucible (number of nozzles: 1), and a glass plate with a thickness of 0.5 InIn (visible light transmittance 92%) was placed on the substrate. Under the conditions shown in Table 1, 7
A 00A indium oxide film was formed.

The visible light transmittance of this film is 42%, and the sheet resistance is 6 x 106Ω.
/ It was very expensive.

Comparative Example 2 5 grams of tin was supplied to a closed crucible (4 nozzles),
A glass plate (visible light transmittance 93%) with a thickness of 0.45 m was installed. Flange (12) in the attached drawing shows the oxygen gas introduction point.
A tin oxide film of 1000 A was formed under the conditions shown in Table 1, with the temperature changed to approximately 100 Å. The visible light transmittance of this film is 50%
, the sheet resistance was 2×10” Ω/mouth.

Comparative Example 3 5 J of indium was supplied to a closed crucible (number of nozzles: 1), and a 100 μm thick polyester film was placed on the substrate. A 1200A indium oxide film was formed under the conditions shown in Table 1. The visible light transmittance of this film is 12
%, and the sheet resistance was 4×10”Ω/mouth.

(Left below) Effect> As described above, according to the method for forming a light-transmitting conductive film of the present invention, the metal itself can be used as an evaporation raw material when forming an oxide film of a metal such as indium or tin. , the deposition rate is faster, productivity is improved, and the durability of the crucible is also improved, contributing to lower production costs.
Furthermore, the obtained light-transmitting conductive film exhibits a unique effect of being excellent in light transmittance and electrical conductivity.

[Brief explanation of the drawing]

The screen is a schematic diagram of an example of an apparatus used when carrying out the forming method according to the present invention. (1)...Vacuum chamber, (a...
Board holder, (3)... Board, (
4)... Oxygen introduction tube, (5)... Leak valve, (6)... Ion accelerating electrode, (Katana... Electrode for electron extraction, (8)・・・・・・
Filament for electron beam generation, (9)... Crucible heater, (g)... Nozzle, (1
1)......closed crucible, (12)...flange, (13)...substrate heating heater.

Claims (1)

[Claims] 1. A method for forming a light-transparent conductive film made of a metal oxide on a light-transparent substrate in a vacuum chamber, wherein the degree of vacuum in the vacuum chamber is 10^-^5 Torr or less. , 5×10^-^5 to 1×10^-^ near the heated light-transmissive substrate
Oxygen gas is introduced to have a partial pressure of 3 Torr, and a closed crucible with a nozzle supplied with indium, tin, or a mixture thereof is heated, and evaporated particles are ejected from the nozzle to oxidize the metal on the substrate. 1. A method for forming a light-transmitting conductive film, the method comprising forming a transparent conductive film. 2. The method for forming a light-transmitting conductive film according to claim 1, wherein the number of nozzles in the closed crucible is one or more. 3. Claim 1 above, wherein the evaporated particles ejected from the nozzle of the closed crucible are a cluster flow or a molecular flow.
The method for forming a light-transmitting conductive film according to item 1 or 2. 4. Ionize the evaporated particles ejected from the closed crucible,
The method for forming a light-transmitting conductive film according to any one of claims 1 to 3, wherein the metal oxide film is formed on the substrate.