JP2660289B2 - Method and apparatus for forming transparent conductive film pattern - Google Patents

Description

The present invention relates to a method and an apparatus for forming a transparent conductive film pattern.

<Prior Art> In general, a transparent electrode is indispensable in a crystal display element, an optoelectronic element such as an electroluminescent element, and the like.
The pattern of the transparent electrode or wiring (hereinafter referred to as an electrode pattern) is usually formed by chemically or physically removing a non-electrode pattern forming portion of the transparent conductive film. A step is formed at the boundary of the non-existing portion, and this step has an adverse effect on the quality and characteristics of the thin film electronic device such as a crystal element and an electroluminescent element. That is, in a liquid crystal element, the orientation of the liquid crystal is adversely affected, and in an electroluminescent element, the quality is degraded because an insulating layer formed on a transparent electrode causes a step, and it is easy to induce destruction or deterioration of the element at this point. It is a problem. Further, a so-called transparent touch panel, which is known as a large use of the transparent electrode, is used, for example, as an input device that allows see-through of a display. However, this also has the following problems. That is, the transparent electrode of such a touch panel is formed in a predetermined pattern, but the conventional method is different from the electrode part due to a fine parallax due to a step between the electrode part and the non-electrode part and an optical difference due to a difference in surface material. Since the non-electrode portion is clearly visible to the naked eye, for example, when a transparent touch panel is used on a display behind it, when the display behind the display is seen through, the electrode patterns overlap and it is unsightly. Therefore, a transparent conductive film pattern having no step with the non-electrode pattern portion is demanded.

A method for eliminating the step has already been described in Japanese Patent Application Laid-Open No. 62-190815.
There is a proposal for the issue. That is, the electrode portion and the non-electrode portion are to be differentiated by introducing or implanting oxygen ions or impurity ions for compensating donors in the film into the transparent conductive film portion other than the electrode pattern forming portion to increase the resistance. This is an excellent idea.

As a method for introducing or implanting the ions into the film, the publication discloses a method using a high-frequency magnetron sputtering apparatus, a method using a plasma anodic oxidation apparatus, a method using an ion implantation apparatus, and a method using a laser beam irradiation apparatus. The electrode pattern obtained by these methods has a surface resistance of several tens of ohms / sq.
It is of the order of ₆ Ω / □, and the above-mentioned step is not recognized, so that it is functionally sufficient.

<Problems to be Solved by the Invention> However, all methods have a problem in productivity and the like, as is known from the embodiments shown in the above-mentioned publications.

That is, in the plasma anodizing method, the processing time is as long as 30 minutes, and depending on the type of the transparent conductive film, the processing temperature is 200 minutes.
Since the temperature is as high as 350 ° C., it is difficult to apply the method to a transparent conductive film formed on a plastic substrate having poor heat resistance, and the method using a high-frequency magnetron sputtering apparatus is almost the same. A method using an ion implantation apparatus or a laser beam irradiation apparatus has a concern about temperature rise and irradiation damage, and there is a problem in productivity in large-area processing.

<Means for Solving the Problems> The present invention has solved the above-mentioned problems by using electron cyclotron resonance (hereinafter, referred to as ECR) oxygen plasma for the treatment for increasing the resistance of the non-pattern forming portion of the transparent conductive film. .

<Effect> Since the ionization rate of ECR oxygen plasma is orders of magnitude higher than that of other oxygen plasmas generated by glow discharge or the like, a large ion current can be obtained, the energy of ions can be controlled, and under low gas pressure. Since ions and radicals are taken out by plasma generation and a diverging magnetic field and, if necessary, a mirror magnetic field, the directivity and uniformity are very good, so oxygen ions and radicals are introduced into the transparent conductive film, It is extremely suitable for the purpose of increasing the resistance of the transparent conductive film by donor compensation or the like, and the transparent conductive film having a large area can be easily subjected to a high-resistance treatment uniformly at a low temperature at the same time.

In addition, a gas of a compound that generates ions of an element serving as an impurity for compensating a donor in the transparent conductive film other than oxygen ions, such as phosphorus, copper, nitrogen, tin, lead, or antimony when the transparent conductive film is zinc oxide. The method of irradiating the transparent conductive film with ions or radicals generated by introducing a compound gas containing nitrogen and the like (hereinafter referred to as an impurity gas) together with oxygen gas into a plasma generation chamber to form plasma together with oxygen gas, and also irradiating the transparent conductive film with high resistance The productivity of the chemical treatment can be increased. There is no particular limitation on the impurity gas, and an effective gas can be freely selected and used. Further, an inert gas such as argon or helium is introduced into the plasma generation chamber simultaneously with the oxygen gas or the impurity gas, and can be used as a carrier gas or for improving the ionization rate.

Further, a method in which the above-mentioned impurity gas is brought into contact with the transparent conductive film while the transparent conductive film is being irradiated with oxygen plasma is also extremely effective in improving the productivity of the treatment for increasing the resistance of the transparent conductive film. This is because the oxygen plasma collides with the impurity gas to generate ions and radicals of an element for compensating the donor, and these are trapped in the transparent conductive film to function to compensate the donor.

The transparent conductive film according to the present invention can be exemplified by a conductive film made of a metal, a metal oxide or the like, and is not particularly limited. Specifically, indium tin oxide, tin oxide, aluminum, silicon-added zinc oxide, and fluorine-doped oxide An example is a conductive thin film made of tin or the like. Further, the method for forming the transparent conductive film on the substrate is not particularly limited, but includes, for example, a sputtering method, an evaporation method,
An ion plating method can be exemplified.

The substrate on which the transparent conductive film according to the present invention is formed is not particularly limited. For example, a transparent substrate such as a glass or plastic film or sheet, or an opaque substrate such as a ceramic substrate or a silicon single crystal substrate is preferably used.

The transparent conductive film pattern according to the present invention is applied not only to the liquid crystal display element, the optoelectronic element such as the electroluminescent element and the transparent electrode of the transparent touch panel, but also to any application that requires the formation of the transparent conductive film pattern and the transparent electrode pattern. It is possible to improve the performance of these applied products.

 Next, the apparatus will be described.

FIG. 1 is a sectional view showing a specific example of a preferred apparatus (second invention) for carrying out the method of the first invention of the present invention, and the present invention is within the scope described in the first invention. It is of course possible to use any device.

 This will be described below with reference to FIG.

Here, the ECR oxygen plasma generation chamber 1 has a structure capable of maintaining a pressure on the order of 10 ^-3 to 10 ^-4 Torr suitable for electron cyclotron resonance. A cooling water jacket 2 is provided on the peripheral wall to prevent a rise in temperature due to collision of gas in an electron cyclotron resonance state, and can be connected to an external cooling water supply device (not shown). A solenoid coil 3 is arranged outside the plasma generation chamber 1 so that a magnetic field can be applied to the plasma generation chamber. A microwave introduction window 4 for providing an oscillating electric field in a direction perpendicular to the magnetic field is provided at an upper portion of the plasma generation chamber 1, and the outside thereof is connected to a microwave oscillator 6 through a microwave waveguide 5. At this time, the window 4 is usually provided with a partition wall made of an appropriate material enough to pass microwaves, so that a necessary pressure can be maintained. Also, there is no problem in using an antenna input method instead of the microwave waveguide. An oxygen gas inlet 7 is provided at an appropriate place in the plasma generation chamber 1 (the upper part of the plasma generation chamber in FIG. 1) so that it can be connected to an external oxygen gas supply device (not shown). I have. The oxygen gas inlet may be provided at two or more places as needed. In FIG. 1, an impurity gas inlet 8 is provided in addition to the oxygen gas inlet, but this is provided for the case where the impurity gas is used together, and the use of the impurity gas is not set as a processing condition. In this case, it is not necessary to provide the impurity gas inlet 8. Even when an impurity gas is used in combination, it is also possible to mix the oxygen gas with the oxygen gas beforehand and use the oxygen gas inlet 7 to introduce the oxygen gas together.
In this case, the installation of the impurity gas inlet is unnecessary.

Oxygen ions and radicals generated in the ECR plasma generation chamber 1 are in an extremely high energy state, and it is not preferable to increase the resistance of the transparent conductive film in this atmosphere because of problems such as irradiation damage. A processing chamber 9 for increasing the resistance of a transparent conductive film is provided adjacent to the ECR plasma generation chamber 1, where plasma irradiation processing is performed. Therefore, a plasma extraction unit 10 for guiding plasma is provided in the processing chamber so as to communicate with both chambers at the lower part of the plasma generation chamber, that is, at the boundary with the high resistance processing chamber 9 side. Therefore, from the side of the high resistance processing chamber 9, the take-out part 10 becomes the plasma take-in part 10. A transparent conductive film holding device 12 for holding the transparent conductive film 11 at the plasma irradiation position is provided in the high resistance processing chamber.
At this time, it is convenient to provide a device capable of taking the transparent conductive film 11 in and out without breaking the vacuum state. If the transparent conductive film is formed on a soft substrate, the unwinding and winding mechanism can be provided in the transparent conductive film gripping device, which is convenient for long continuous processing and further improves productivity. I do.

As a so-called masking method of shielding the pattern forming portion of the transparent conductive film from plasma irradiation, a method of overlapping a pattern mask prepared in advance in the shape of a pattern on the transparent conductive film, or a method of forming a transparent conductive film using a resist ink. An appropriate method such as a so-called resist mask method in which a pattern is formed thereon and the resist ink is removed with a chemical solution or the like after the non-pattern portion is made to have a high resistance by plasma irradiation is not particularly limited.

In addition, in order to maintain the transparent conductive film being irradiated with the ECR oxygen plasma at a predetermined temperature, it is free to provide an appropriate temperature control device 20 as necessary, for example, to reduce the heat resistance of the substrate on which the transparent conductive film is formed. It is preferable to keep the temperature appropriately.
A solenoid coil 13 for applying a mirror magnetic field is arranged around the periphery of the high-resistance processing chamber. The diverging magnetic field is used as a mirror magnetic field near the plasma intake 10 to reduce the energy of the plasma diffused from the plasma intake. Work to make it work. This is a transparent conductive film holding device 12 instead of a solenoid coil.
A permanent magnet may be provided near the lower side of. Electrodes 14 and 15 are provided in the plasma intake section and the plasma irradiation area of the transparent conductive film holding device, respectively, so that plasma can be extracted. Is connected to the power supply 16 provided in the power supply. When the strength of the plasma energy diffused from the plasma generation chamber or the magnitude of the ion current is insufficient and the efficiency of the treatment for increasing the resistance of the transparent conductive film is low, the treatment is remarkably performed by applying a voltage to the electrode. Time can be reduced. That is, when a DC voltage is applied, ions in the plasma are accelerated in the direction of the film, and when an AC voltage is applied, ions to be neutralized are reactivated. This is because, in addition to increasing the kinetic energy of ions, the density of ions and radicals that reach the transparent conductive film per unit time is increased.

As described above, ions can be controlled over a wide range by adjusting the intensity of their energy and the direction of their movement by applying an electric or magnetic field. Since the ECR oxygen plasma has an extremely high ionization rate, extremely active oxygen ions and radicals can be generated, and it is easy to control and easy to select optimum conditions.

In the treatment chamber for increasing the resistance of the transparent conductive film, an impurity gas is introduced into the chamber from an impurity gas supply device provided outside, and the air outlet 17 is positioned near the plasma irradiation area of the transparent conductive film holding device 12. A gas introduction pipe 18 is provided, and the impurity gas can be brought into contact with the transparent conductive film which is being irradiated with oxygen plasma or oxygen plasma containing the impurity gas, and donor compensation impurities other than oxygen are introduced into the transparent conductive film. Can be introduced. This method is particularly useful when it is not preferable to introduce an impurity gas into the plasma generation chamber due to corrosion problems or the like. The plasma generation chamber and the high resistance processing chamber are maintained at an extremely low pressure by an external vacuum exhaust device (not shown) through an exhaust port 19.

To actually perform the processing, first, the transparent conductive film holding device 12
Next, the transparent conductive film 11 is set, and then vacuum suction is performed from the exhaust port 19 to obtain a required pressure (degree of vacuum). At this time, even if the gas is supplied from the oxygen gas inlet 7, the impurity gas inlet 8 used as needed, and the impurity gas outlet 17, the supply amount and the vacuum suction amount of these gases are such that the required pressure can be maintained. Set. Oxygen and impurity gas introduced into the plasma generation chamber 1 are oscillated from the micro oscillator 6 and applied to the plasma in the generation chamber 1 by the microwave introduced into the ECR oxygen plasma generation chamber 1 through the introduction window 4 and the solenoid coil 3. ECR plasma is generated by the action of the applied magnetic field, enters the high resistance treatment chamber through the extraction window 10, and acts on the transparent conductive film.

The microwave introduction window 4, oxygen gas inlet 7, impurity gas inlet 8 and the like in the present apparatus may be provided on the inner wall of the ECR oxygen plasma generation chamber 1, or may be provided inside the ECR oxygen plasma generation chamber 1, and are required inside the generation chamber. It can be placed anywhere in the production chamber as long as it can take in microwaves and gas. In addition, the plasma outlet 10 is free to be provided anywhere in the plasma generation chamber 1, and the plasma inlet 10 is also free to be provided anywhere in the high-resistance treatment chamber 9. If the two are connected, there is no particular limitation. Absent.

FIG. 1 shows the vertical direction of the drawing so that the vertical direction of the actual device coincides with the vertical direction.

The above specific example is a preferred example of implementing the second invention, and the second invention can take any other form within the scope.

<Example 1> Indium tin oxide (ITO) having a thickness of about 100 nm formed on a polyethylene terephthalate film having a thickness of 100 µm
A stainless steel mask is adhered to a part of the surface of each of the transparent conductive film, the tin oxide (SnO ₂ ) transparent conductive film and the aluminum-added zinc oxide (ZnO: Al) transparent conductive film, and the transparent mask of the apparatus shown in FIG. It was attached to a conductive film holding device and irradiated with ECR oxygen plasma under the processing conditions shown in Table 1.

At this time, the surface resistance of the unmasked portion during the irradiation time was as shown in Table 2.

The parts irradiated with ECR oxygen plasma are ITO film, SnO ₂ film and
In both ZnO: Al films, a remarkable increase in sheet resistance was observed,
The irradiation of 5 minutes reached the order of 10 ⁶ Ω / □ (measurement limit of the measuring machine used). On the other hand, where the stainless steel mask was applied, the surface resistance did not change. In addition, the place where the stainless steel mask is used and the other places are SnO for ITO.
_In the case of No. _2, no remarkable change in optical characteristics or change in film thickness was observed.

<Example 2> A commercially available ITO transparent conductive film (120 nm thick) formed on a glass substrate, a commercially available fluoridated tin oxide (SnO ₂ : F) transparent conductive film (500 nm thick), and a sputtering method were used. A high-frequency voltage (15 kHz, 100 W) is applied between the electrode of the plasma inlet and the electrode of the transparent conductive film holding device for each of the ZnO: Al transparent conductive films (thickness: 500 nm), and otherwise the same as in Example 1. Treatment under the conditions gave the results in Table 3.

The non-mask portion reached 2 × 10 ⁶ Ω / □ by irradiation for 2 minutes.
During this time, there was no change in the surface resistance of the mask portion, and no substantial difference in thickness between the mask portion and the non-mask portion was observed.
Also, no distinction could be made between the treated part and the non-treated part with the naked eye.

<Example 3> adding oxygen gas to 5% of N ₂ O gas or SO ₂ gas in the plasma generating chamber and subjected to high-resistance treatment under the same conditions as in Example 1. Both the indium oxide / tin oxide film and the tin oxide film reached the order of 10 ⁶ Ω / □ by the treatment for 2 minutes.
Further, a 1% phosphine (PH ₃ ) gas with respect to oxygen gas was added to the aluminum-added zinc oxide film.
The resistance value of the plasma-irradiated portion of the film subjected to the high-resistance treatment under the same conditions as described above became unmeasurable after about 2 minutes.

The addition of the impurity gas was also effective in increasing the resistance of the transparent conductive film.

Example 4 At the same time as irradiating the transparent conductive film with ECR oxygen plasma under the same conditions as in Example 2, diethyl zinc (DEZ) equivalent to 1% of oxygen gas supplied from the impurity gas outlet to the plasma generation chamber was used. ) Gas or trimethylaluminum (TMA) gas was brought into contact with the transparent conductive film. Indium oxide - DEZ gas to the tin film, a result of the act, respectively the TMA gas to the tin oxide film, 10 in any of the 2-minute treatment ⁶
The order of Ω / □ was reached, there was no change in the surface resistance of the mask portion, and no substantial difference in thickness between the mask portion and the non-mask portion was observed. Similarly, when the NO ₂ gas or SO ₂ gas corresponding to 10% of the oxygen gas was brought into contact with the ZnO: Al film, the resistance reached about 10 ⁶ Ω / □ after about 1 minute. W (CO) equivalent to 1% of oxygen gas
₆ , it was confirmed that bringing a Cr (CO) ₆ or Fe (CO) ₅ gas into contact with the ZnO: Al film was also extremely effective.

<Effects of the Invention> As described above, the present invention is based on the fact that the ionization rate of ECR plasma is remarkably higher than that of plasma generated by other methods. The use of ECR oxygen plasma for the treatment results in a significant reduction in the time required to increase the resistance of the transparent conductive film without a change in its thickness, compared to the methods already proposed. The method for forming a transparent conductive film pattern according to the present invention has practicality, for example, it is possible to easily and efficiently increase the resistance of a transparent conductive film using a plastic material having poor heat resistance as a substrate. It is much better.

Furthermore, the apparatus for forming a transparent conductive film pattern according to the present invention has a simple structure and an unconventional structure. If necessary, a solenoid coil for applying a mirror magnetic field is installed. The installation of the electrodes enables control of the energy of the irradiation plasma, and furthermore, if necessary, by providing an inlet for impurity gas or the like, the optimum processing conditions according to the use of the transparent conductive film and the substrate material from a wide range, that is, It is possible to easily select conditions for efficiently introducing oxygen ions and radicals and, if necessary, impurity ions and radicals into the transparent conductive film in a non-sputtering state. In this case, a special effect is obtained such that processing can be performed under the optimum conditions.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a preferred apparatus for forming a transparent conductive film pattern according to the present invention. 1. ECR plasma generation chamber 9. High resistance processing chamber

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-190815 (JP, A) JP-A-62-89873 (JP, A) JP-A-60-175312 (JP, A)

Claims (6)

(57) [Claims] 1. A method of masking a surface of a pattern forming portion of a transparent conductive film formed on a substrate, and applying oxygen plasma generated by electron cyclotron resonance having a high ionization rate to a non-pattern forming portion to increase resistance. A method for forming a transparent conductive film pattern, comprising performing a treatment. 2. Impurity ions for compensating donors in the transparent conductive film are generated together with oxygen ions by electron cyclotron resonance having a high ionization rate, and are introduced together with the oxygen ions into a non-pattern forming portion of the transparent conductive film to increase the resistance. The method according to claim 1, wherein the processing is performed. 3. A method of irradiating an oxygen plasma generated by electron cyclotron resonance having a high ionization rate on a non-pattern forming portion of a transparent conductive film, the compound containing an element serving as an impurity for compensating a donor in the transparent conductive film. The method for forming a transparent conductive film pattern according to claim 1, wherein the non-pattern formed portion is made to have a high resistance by contacting the gas with the non-pattern formed portion of the transparent conductive film. 4. A cooling jacket provided on a peripheral wall, a solenoid coil for applying a magnetic field provided on an outer periphery of the jacket, and a configuration having a microwave introduction window, an oxygen gas inlet and a plasma outlet in a room. An oxygen plasma generation chamber by the electron cyclotron resonance plasma method provided, a mirror magnetic field application solenoid coil provided on the outer periphery as necessary, a plasma intake unit configured to communicate with the plasma extraction unit, and a plasma irradiation position. A transparent conductive film gripping device, an electrode provided in the plasma irradiation area of the plasma intake portion and the transparent conductive film gripping device as necessary, and an exhaust port connected to an external vacuum exhaust device. And a high resistance treatment chamber. 5. The transparent conductive film according to claim 4, further comprising an inlet for a compound gas containing an element serving as an impurity for compensating a donor in the transparent conductive film in the electron cyclotron resonance plasma generation chamber. Pattern forming equipment. 6. The transparent conductive film provided in the transparent conductive film holding device is located at a position where a gas of a compound containing an element serving as an impurity for compensating donors in the transparent conductive film can be contacted. 5. The apparatus for forming a transparent conductive film pattern according to claim 4, further comprising an outlet.