JP3001894B2 - Method and apparatus for etching multilayer thin film element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an etching method and an apparatus for patterning a functional layer in a multilayer thin film element such as a thin film EL element.

[Prior Art] For example, as shown in FIG. 2, a thin-film EL element composed of a multilayer thin film is formed on a transparent substrate 51 by a transparent electrode 52, a first insulating layer 53,
An EL element having a double insulation structure having a basic structure in which a light emitting layer 54, a second insulating layer 55, and a back electrode 56 are laminated is mainly used, but cost and light emitting conditions (voltage, frequency, etc.) are used.
In order to realize higher brightness, higher luminous efficiency, lower voltage drive, DC power supply drive, commercial frequency drive, and lower cost, a transparent substrate 51, a transparent electrode 52 as shown in FIG. The development and commercialization of a so-called MIS-structure EL element which has a light emitting layer 54, an insulating layer 55, and a back electrode 56 as a basic structure and excludes the first insulating layer 53 in FIG. .

As for the usage of the thin film EL element, an area is expanded from a surface light source, and a still image and further a moving image display as a display plate are being researched and developed in recent years.

In order to display an image with the thin-film EL element having the above basic configuration, in order to emit light only in a portion corresponding to the image,
Whether the transparent electrode and / or the back electrode is patterned into the shape of the image to be displayed (FIG. 4 (A)), the light emitting layer is patterned (FIG. 4 (B)), or both the electrode and the light emitting layer (FIG. 4 (C)).

When a moving image is displayed as a more advanced display mode, each of the transparent electrode and the back electrode is patterned into a plurality of stripes, and the stripes are arranged orthogonally (FIGS. 5A and 5B). )), A so-called XY matrix electrode system, and in order to eliminate bleeding caused by scattering of light from the light-emitting portion, the light-emitting layer should be a stripe corresponding to the electrode, or a square dot matrix system (FIG. 6), etc. Either of the methods is adopted.

Regarding multicoloring, a method of stacking single-color EL with different color tones has already been announced, but there are many technical difficulties, so the light emitting layer is patterned into fine pixels, and the pixels are further divided into the number of colors. Research and development are being carried out on a method of forming a light emitting layer for distributing a required color tone for each section and disposing an XY matrix electrode corresponding to each layer.

Here, the patterning of the transparent electrode or the light emitting layer, which is one of the functional layers, usually covers the non-removed portion with a resist pattern,
This is done by chemically or physically shaving off the uncovered portion, ie, etching.

As a method of covering the non-removed portion with the resist pattern, a photolithography method or a method of directly printing a resist material is used. The former is generally used for fine patterning. Most resist materials are organic polymer materials.
The selection is made in consideration of the etching conditions.

For the etching of the transparent electrode, chemical etching by a wet method is generally used. Electrode materials are required to have chemical stability as a constituent material of display devices, so tin oxides such as SnO ₂ and ITO are often used.However, etching is difficult, so etching with ECR hydrogen plasma is proposed. (Japanese Patent Application No. 63-72785).

Emission layer patterning has been undertaken in R & D for the development of multi-color display EL, as an alternative to the mono-color stacking method, for example, held in New Orleans on May 11-15, 1987. Report by Dr. Yamauchi at the Information Display Society of Japan (SID) (1987)
SID digest pages 230-233) and September 15, 1987-1
Report by C. Brunel at the 7th International Display Conference (IDRC) held in London on July 7
8 to 239).

The former relates to the production of two-color EL with a two-color insulation structure and is the first
The light emitting layer (ZnS: Mn orange) formed on the insulating layer is made of a photoresist, and a portion where the second color light emitting layer (ZnS: Sn red) is formed is removed by photolithography.

In the latter case, a reactive ion etching (RIE) method and an ion beam etching (IBE) method are recommended because the wet method should not be used for etching the light emitting layer. rear,
A resist pattern is formed by photolithography, and the light emitting layer is etched together with the second insulating layer. The history of the etching of the light emitting layer is short and there is no general method.

[Problems to be Solved by the Invention] Etching technology selection conditions include, for example, when etching using a resist pattern, do not affect the resist pattern, act on the material to be removed, do not damage other materials, and use chemicals. And leaving no impurities or damage from the process.

In a multilayer thin film element, for example, a thin film EL element, the transparent electrode and the light emitting layer are usually etched, but the insulating layer and the transparent substrate often must not be damaged. However, depending on the type, the insulating layer or the transparent substrate may be etched.

The wet method adopted by Yamauchi et al., That is, the solution method etching, has an advantage that fine speed and shape selectivity can be adjusted by changing the combination or composition of chemicals. Solution method etching of thin film EL devices has a double insulating structure, and the transparent electrodes and light emitting layers to be patterned are formed on transparent substrates and insulating layers with excellent chemical resistance, respectively. It is easy to choose, but in the case of MIS structure,
The light-emitting layer is formed on the transparent electrode, and the base material for forming the light-emitting layer, such as a II-VI compound semiconductor represented by ZnS or SrS, can be easily removed with an acid. Since the removal conditions of SnO ₂ and ITO are severe, if two layers are etched at the same time, side etching etc. will occur and the etching of the light emitting layer will progress too much, which is difficult. The complexity of patterning each time it is formed is unavoidable.

In addition, solution-based etching, for example, when a resist pattern is used, involves dissolution of the resist pattern or penetration (undercut) into the lower portion of the resist pattern, and has a disadvantage that sharp etching is difficult to be performed. Also, the treatment of waste liquids related to pollution is a problem.

In addition to this problem, it is generally known that the absorption of moisture in the light-emitting layer significantly reduces the luminance and life, and it is said that sufficient control of the moisture-proof surface is particularly important from the element manufacturing process and product management. That's right. Therefore, in addition to the patterning of the EL element, treatment with an aqueous solution or a highly hygroscopic solvent system should be basically avoided in each step of forming the EL element.

Mr. Yamauchi et al. Have succeeded in the wet etching of ZnS: Sn in the production of multicolor EL, but Mr. C. Brunel et al. Mentioned above have found it difficult to implement wet etching elements due to destruction of the elements, contamination and peeling of the light emitting layer. He further predicts that a luminescent layer based on alkaline earth metal sulfide will not be successful in the future.

On the other hand, among the dry methods recommended by C. Brunel, the RIE method is used for substances that generate volatile compounds including chlorine and fluorine by plasma, and chlorinated gas is suitable for ZnS but alkaline earth It is unsuitable for metals, and chlorine has a detrimental effect on EL characteristics and should be avoided. C.
Brunel et al. Recommend that the IBE method using chemically neutral Ar gas be used for processing any material because of its lack of selectivity, but there is a high risk of etching and damaging the underlayer of the light emitting layer. .

The present invention solves the above-mentioned problems relating to the etching of the functional layer such as the light-emitting layer and the transparent electrode, and does not affect the insulating layer or the transparent substrate in the multilayer thin film element or the like, and the functional layer such as the light-emitting layer or the transparent electrode is formed. It is an object of the present invention to provide a method and an apparatus for selectively etching at least one layer.

[Means for Solving the Problems] The inventor of the present invention has been keenly studying the etching of various materials using hydrogen plasma, and the hydrogen plasma is, for example, a base material of a II-VI group compound semiconductor, particularly ZnS. It is very easy to etch the EL light emitting layer, and also to etch the functional layer as a plasma extraction electric field by applying a DC power supply, or by applying a high frequency power supply in a low frequency range (for example, 15 KHz). (Less than,
The first etching method), the etching rate is increased and the etching is performed in a short time. On the other hand, it is practically used for an insulating layer typified by Al ₂ O ₃ , Ta ₂ O ₅ or the like, or a transparent substrate such as a glass or a plastic sheet. It has been found that the insulating layer and the like can be easily etched by applying a high frequency power in a high frequency region (for example, 13.56 MHz) and performing etching (hereinafter referred to as a second etching method).

Separately, it has already been found that hydrogen plasma treatment is an effective means for etching a transparent electrode (Japanese Patent Application No. 63-72).
785), together with this discovery, led to the present invention.

That is, in the method of etching a multilayer thin film element according to the present invention described in claim (1), when a thin film EL element is taken as an example, a light emitting layer or a transparent electrode to be patterned is formed in the process of forming the multilayer thin film element. An etching method using hydrogen plasma generated in a plasma generation chamber using an electron cyclotron resonance method for etching at least one layer of the functional layer.

In order to increase the etching rate, an inert gas or a reaction gas may be used in combination, if necessary, and furthermore, as described in claim (4), the extraction electric field for guiding the hydrogen plasma generated in the plasma generation chamber to the processing chamber. Change the frequency.

Further, in the etching apparatus of the present invention described in claim (7), microwaves are introduced into a evacuated plasma generation chamber,
Further, by applying a magnetic field from the outside, the hydrogen gas introduced into the plasma generation chamber and, if necessary, the combined gas are subjected to electron cyclotron resonance to produce plasma, and at least one of the active layers of the multilayer thin film element is etched in the processing chamber. A reaction gas introducing means for introducing various reaction gases into the processing chamber to promote an etching process in the processing chamber, if necessary, as described in claim (8); According to a tenth aspect of the present invention, there is provided a magnetic field applying means for generating a mirror magnetic field in the processing chamber in order to reduce the energy level of the hydrogen plasma generated in the plasma generating chamber.

[Operation] The etching method of the present invention will be described in detail below using a thin film EL element as an example of a multilayer thin film element.

The thin-film EL element mainly has a double insulation structure, and its basic configuration is as shown in FIG. The present invention provides a light emitting layer which is a type of a functional layer formed on a transparent substrate 51.
This is applied when patterning the transparent electrode 52 and / or 54. For example, when patterning a transparent electrode by a resist pattern method, a non-removed portion of the transparent electrode 2 uniformly formed on the transparent substrate 51 is covered with a resist pattern (not shown), and hydrogen plasma is applied from above the resist pattern. By irradiating the transparent electrode 52, the portion of the transparent electrode 52 not covered with the resist pattern is etched.
Even if the irradiation of hydrogen plasma is continued even after the transparent electrode 52 is removed, the transparent substrate 51 is not etched or damaged by the above-described first etching method. Thereafter, the resist pattern is removed by an appropriate method, for example, an organic solvent, oxygen plasma or the like.

Subsequently, the first insulating layer 53 is formed so as to cover the transparent electrode 52, and the light emitting layer 54 is further formed uniformly on the first insulating layer 53. The patterning of the light emitting layer 54 is the same procedure as the patterning of the transparent electrode 52.First, a resist pattern is formed in a predetermined pattern on the light emitting layer 54, and hydrogen plasma is applied to the light emitting layer 54 from above the resist pattern. Then, the light emitting layer 54 is etched. Even if irradiation with hydrogen plasma continues after the light-emitting layer 54 is removed, the first etching method does not etch or damage the underlying first insulating layer 53.

Since the gas system and processing conditions used for etching both the transparent electrode 52 and the light emitting layer 54 are basically the same, there is an advantage that the EL element manufacturing process is simplified.

Next, a second insulating layer 55 is formed, and a back electrode is formed by, for example, depositing aluminum or printing with aluminum foil or conductive ink.
If 56 is formed, a thin film EL device having a double insulating structure can be obtained.

The material of the back electrode 56 is not particularly limited, and may be a transparent electrode, but those having a highly reflective aluminum foil or an aluminum vapor-deposited film as the back electrode reflect the EL light generated in the light emitting layer 54 to the front. Therefore, it contributes to the brightness improvement. When patterning of the back electrode 56 is necessary, when an aluminum foil or an aluminum vapor-deposited film is used as the back electrode, a conventional etching method may be adopted.In the case of aluminum evaporation, the non-electrode formation portion is covered with a mask and the mask is deposited after the evaporation. A method of removing the conductive ink and a method of printing in a required electrode shape when a conductive ink is used can be employed.

Even in the IBE method using argon gas which C. Brunel makes the best, there is no selectivity of the etching target.For example, when removing the light emitting layer 54, according to the IBE method, the lower insulating layer 53 Etching results. Therefore, for example, the light emitting layer 54 is patterned in order to make a multicolor EL, a second insulating layer 55 and a second light emitting layer are formed, and the second light emitting layer is patterned by the IBE method. Is also slightly etched, which adversely affects the performance of the second insulating layer 55. However, the etching method of the present invention has good selectivity for an etching target, and if the first etching method is applied, the second insulating layer becomes It is not damaged and is extremely useful for the production of multicolor EL devices.

EL devices with such a multilayer insulation structure are expensive, have high drive voltages, require an AC power supply, and require a high-frequency power supply, which is usually difficult to obtain easily, in order to obtain sufficient luminance. It is difficult to apply to a display light source for a commercial frequency power supply or a DC power supply. Therefore, they are only used in limited applications such as expensive computer terminal displays.

Therefore, there is a demand for an EL element driven by high luminance, high luminous efficiency, low voltage driving, single-phase commercial frequency power supply or DC power supply, and a thin film EL having an MIS structure is expected to be an element satisfying various conditions.

The basic configuration of the MIS type thin film EL element is as shown in FIG. 3, and is usually formed in the order of the numbers in the figure. The present invention can be applied to patterning of a composite layer composed of the transparent electrode 52 and the light emitting layer 54 having the above configuration, and the transparent electrode 52 on the transparent substrate 51,
After forming the light-emitting layer 54, the non-removed portion is shielded and separated by a resist pattern or the like, for example, and then covered with the hydrogen plasma irradiation, whereby the composite layer including the light-emitting layer 54 and the transparent electrode 52 not covered with the resist pattern is etched. Removed. Even if the irradiation of hydrogen plasma is further continued, the first etching method does not etch or damage the transparent substrate under the composite layer. At this time, it is also possible to etch only the light emitting layer by selecting etching conditions as described later. Of course, the transparent electrode 52 and the light emitting layer 54 may be separately removed by etching.

As described above, it is difficult to simultaneously etch the transparent electrode and the light emitting layer because the solubility of the transparent electrode and the light emitting layer is greatly different in the solution method, and there is a problem of moisture absorption that has a fundamental adverse effect on the light emitting layer. However, since the etching method of the present invention is a dry method, there is no concern about performance degradation due to moisture absorption of the light emitting layer, and in addition, there is an advantage that the transparent electrode and the light emitting layer can be removed in one step, and the MIS type thin film EL element Is particularly useful as a method for etching at least the light emitting layer and / or the transparent electrode.

Furthermore, if the transparent electrode and the light emitting layer are etched using hydrogen plasma, the transparent electrode, which is a metal oxide, and the light emitting layer, which is a metal sulfide, are first reduced to a metal having a low evaporation temperature by the reducing action of active hydrogen in the plasma. If the irradiation with hydrogen plasma is continued, the metallized portion is easily and effectively removed by hydrogenation with active hydrogen or sputtering by hydrogen ions. That is, since the etching method of the present invention involves a reducing action by active hydrogen, the material constituting the electrode and the light emitting layer is more easily removed as the material is more easily reduced. According to the method of the present invention, since a tin oxide-based transparent electrode such as SnO ₂ or ITO, which is usually difficult to chemically etch by a wet method, is also easily reduced by active hydrogen,
SnO ₂ and ITO can also be removed more easily. The emission layer is also C
The light-emitting layer covering the entire visible light region, such as aS, SrS, etc., and having a base material of, for example, a II-VI compound semiconductor, can be removed. Above all, the method of the present invention has a feature that ZnS is particularly easy to remove.

ZnS is a material capable of realizing high luminance and high luminous efficiency, and since it is possible to exhibit each color of red, green and blue by selecting a dopant, it is important that ZnS has good etching properties for realizing a full-color EL.

On the other hand, Al ₂ O ₃ , Ta ₂ O ₅ ,
Y ₂ O ₃ , SiO _2, etc. are stable against the reducing action, they are not reduced even under irradiation of hydrogen plasma, and the transparent electrode and the light emitting layer are removed within a few minutes. Under the environment of the etching method, even if it is processed for tens of minutes, the color is slightly changed,
In addition, since hydrogen ions are light in mass and have low kinetic energy, sputter etching of the insulating layer does not occur, and the insulating layer is practically unaffected by hydrogen plasma irradiation. However, if the above-described second etching method is used, the insulating layer can be etched.

As described above, in the first etching method of the present invention, a functional layer such as a transparent electrode or a light emitting layer that requires patterning can be easily etched, and has no effect on an insulating layer that does not require patterning. The etching method of the present invention is a very convenient etching method for a thin film EL device, for example.

The hydrogen plasma used in the present invention can be of course used by any method such as a high-frequency glow discharge method, a direct current glow discharge method, an arc discharge method, etc., but the electron cyclotron resonance method (ECR) can be used. Method) is more desirable. That is, compared to other plasma generation methods,
This is because the ECR method is extremely suitable for etching in which a reducing action is effective because hydrogen plasma having an ionization rate of an order of magnitude is obtained. Other advantages of the ECR method include the ability to form sharp contours without side etching due to the directivity of hydrogen ion movement, and the application of a mirror magnetic field to generate relatively low energy plasma. Because it can be used and is easy to control, it is easy to select the optimum processing conditions, and thus it can be safely processed even in the case of a thin film EL element or the like using a plastic material having poor heat resistance as a substrate.

Since hydrogen plasma has a small mass and low kinetic energy, it is expected that it is inefficient to remove the reduced and metallized portion by sputtering, and it will take a long time to remove it.In fact, the removal of the transparent electrode is exactly the same. However, the removal of ZnS from the light emitting layer was contrary to expectations. That is, it is considered that hydride formation by active hydrogen is more involved in removing the metalized portion of ZnS due to reduction than sputtering by hydrogen ions.

When a heavy element, for example, an insoluble gas such as argon, was added to the hydrogen gas for the sputter removal of the metallized portion, the time required for removal of the transparent electrode (hereinafter referred to as the required etching time) could be reduced. However, there was no practical shortening effect in ZnS of the light emitting layer.

The use of an inorganic or organic substance, such as CC ₄ gas or butyl acetate gas, in addition to the inert gas, as described in claim 3, in combination with hydrogen gas is effective for greatly reducing the etching time. That is, these gases (hereinafter referred to as combined gases) are decomposed in the plasma generation chamber, and the products are turned into plasma or radicals. The hydrogen component in the gases is involved in the reduction action of the transparent electrode and the light emitting layer. This is because a methyl group component, an ethyl group component, or the like reacts with a metalized portion by a reducing action of a hydrogen component to generate an organic metal such as an ethyl compound, thereby promoting etching by a chemical reaction.

Further, in the case of a combined gas that produces an acidic product, that is, in the case of using a compound that produces an acidic product such as active fluorine or active chlorine in a plasma atmosphere with an acidic gas such as hydrogen halide, nitric acid, or sulfuric acid, The acid product of these concomitant materials and the portion where the transparent electrode or the luminescent layer is reduced and metallized by hydrogen plasma irradiation chemically react to remove the metallized portion, thereby shortening the etching time. Become.

However, etching is not performed favorably only with the combined gas, and it is important that hydrogen gas is present. For example, when only an alcohol gas is used, a carbon film is deposited on the wall surface of the plasma generation chamber, on the transparent electrode, or on the light emitting layer, and this seems to inhibit the etching. Even when Ce ₄ is used, there are problems of corrosion of the plasma generation chamber wall due to chlorine, deposition of a carbon film, and residual chlorine gas. It is considered that active hydrogen not only reduces the transparent electrode and the light emitting layer, but also removes these deposits and prevents them.
It is known that the combined use of oxygen-containing compound gas such as butyl acetate and acetone shortens the desired etching time,
The active oxygen generated in the plasma generation chamber also has the function of removing the deposited carbon film, and an amount of active hydrogen equivalent to the amount of the oxygen is used to reduce and metallize the transparent electrode and the light emitting layer. It is presumed to be.

Specific examples of such a combined gas include helium, neon, argon, krypton, and xenon for an inert gas, and methane, ethane, propane, butane, pentane, hexane, cyclohexane, ethylene, propylene, and butylene for a hydrocarbon. , Pentene, acetylene, benzene, toluene, xylene, alcohol for methanol, ethanol, propanol, isopropanol, butanol, isobutanol, ketone for acetone, methyl ethyl ketone, diethyl ketone, ester for ethyl acetate, propyl acetate,
Isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, dimethyl ether, diethyl ether, methyl ethyl ether for ether, fluorine and chlorine for halogen gas, hydrofluoric acid, hydrochloric acid, bromic acid for hydrogen halide For halogenated carbon, carbon tetrachloride, chlorotrifluoromethane,
Dichlorodifluoromethane, chlorofluoroethylene,
Dichlorotrifluoroethane, octafluoropropane, and chlorofluoroethylene; for halogenated carbon, methylene chloride, ethylene chloride, trichloroethylene, dichloroethylene, chloroform, chlorobenzene, metadichlorobenzene, paradichlorobenzene, sulfur Examples of the compound-based gas include sulfurous acid, sulfuric acid, sulfur hexafluoride, carbon disulfide, and hydrogen sulfide, and examples of the nitrogen oxide-based gas include ammonia, hydrazine, nitric oxide, nitrogen dioxide, nitric acid, and nitric anhydride. Needless to say, these substances can be mixed and used as necessary.

Further, they have found that a method of contacting and reacting a separately introduced reaction gas with a transparent electrode or a light emitting layer which is being irradiated with ECR hydrogen plasma can also shorten the time required for etching.

That is, when a combined gas is used for the ions and radicals of hydrogen extracted from the plasma generation chamber, the ions and radicals of the components generated by decomposition of the combined gas are separately introduced into the reaction gas. , Which decomposes the reaction gas into ions and radicals, some of which reduce metallization of the transparent electrode or light-emitting layer, and some of which metallize organic metal Or by hydride treatment, the acidic product is accompanied by a chemical removal effect and the other product is removed by sputtering together with the metallized portion. As a result, the time required for etching can be greatly reduced. In addition, as the specific example of the reaction gas, the same substance as the above-mentioned combined gas can be exemplified.

As for these combined gases and reaction gases, substances other than those exemplified above can be appropriately used, and there is no particular limitation. There are no particular restrictions on the specific examples of each of the exemplified substances, as well as proper substances other than the above can be used.

For example, the patterning of the transparent electrode and the light emitting layer is achieved by shielding and isolating at least a portion to be left from being irradiated with plasma or contacting with a reaction gas during the etching process.

Generally, as a method of shielding and isolating, a method of attaching a resist material to a required portion of the surface of a functional layer such as a transparent electrode or a light emitting layer to be patterned by printing or the like, a photolithography method, or a sheet excellent in etching resistance A method in which a pattern mask obtained by cutting out a sheet material into a required shape is coated on a transparent electrode or a light emitting layer with an etching resistant photosensitive resin, and is exposed and developed to form a resist pattern. Most of the resist material is a polymer material. The material is selected in consideration of etching conditions, and there is no particular limitation. However, this method of directly printing a resist is difficult to obtain high resolution. The method using a pattern mask has the advantage that a resist material is not required, but the adhesion is likely to be incomplete, and as a result, a wraparound (undercut) is likely to occur, and the accuracy around the pattern is deteriorated. Therefore, a method using a resist pattern is suitable for the implementation of the present invention, such as the reality of multicolor EL, so that a method using a resist pattern is suitable.However, the patterning of the light-emitting layer is performed by developing the resist pattern in order to avoid deterioration in performance due to moisture absorption. Regarding the removal treatment of the resist pattern after the etching, it is necessary to select an appropriate material and method, such as an organic solvent-based one, not depending on the aqueous solution.

However, the embodiment of the present invention is not particularly limited to the patterning method using a resist pattern, and it goes without saying that other methods can be implemented. At this time, as the material for forming the resist pattern, various materials are used without departing from the scope of the purpose, and there is no limitation.For example, a PMMA-based material can be exemplified. For example, a method using oxygen plasma can be used to remove the resist pattern.

Further, the present invention provides an etching method for changing the frequency of an extraction electric field applied to guide hydrogen plasma generated in a plasma generation chamber to a processing chamber.

According to the second etching method in which a high-frequency electric field in a high frequency region of, for example, 13.56 MHz is applied as an extraction electric field,
Physical etching based on the sputtering phenomenon is promoted, while, in the case of the first etching method in which a high-frequency electric field in a low frequency range of, for example, 15 KHz is applied, physical etching is suppressed, and as a result, a reducing action by active hydrogen, Furthermore, by performing chemical etching by forming hydrides or organometallics, etching can be performed efficiently according to the material of the layer to be etched. Therefore, by changing the frequency of the extraction electric field arbitrarily and changing the etching strength, it becomes possible to etch not only the transparent electrode and the light emitting layer but also the insulating layer and the transparent substrate if necessary. Further, since this chemical etching is sensitively dependent on the temperature of the material to be etched, controlling the temperature with a temperature control device provided in the sample stage is extremely effective for controlling the chemical etching.

The invention of claim (8) according to the present invention is a preferred apparatus for carrying out the invention of claim (1). It is needless to say that the present invention can take any form within the scope described in the claims.

As a material constituting each layer, a transparent substrate 51 is made of a transparent plastic sheet having excellent heat resistance and dimensional stability, such as a polyester sheet, in addition to a glass plate. SnO ₂ with excellent properties, tin oxide such as ITO, and the insulating layer 55 as Al ₂ O ₃ ,
Ta ₂ O ₅ , Y ₂ O ₃ , TiO ₂ , SiO _2, etc., and the light emitting layer 54 has a wide band gap II in order to obtain light emission in the entire visible light region.
-Group IV compound semiconductors, among which ZnS based which can realize the highest brightness and high luminous efficiency, Al foil, Al vapor deposited film tin paste ink etc. can be exemplified as the back electrode 56, and a film forming method of each layer except the back electrode 56 Examples thereof include a magnetron sputtering method capable of forming a uniform and high quality film at a low temperature at a high speed.

The material and film forming method of each layer exemplified above are merely examples, and it is needless to say that the material can be formed of other possible materials and film forming methods, and that the insulating layer is formed of a plurality of materials. There is no problem with the present invention.

At this time, the substrate and the electrode have been described as having transparency, but it is needless to say that a translucent or opaque material can be used depending on the application. The functional layer in the multilayer thin film element of the present invention is not particularly limited as long as it has a function of constituting the element. For example, the functional layer of the thin film EL element includes an electrode, a light emitting layer, an insulating layer, and a back electrode. And the like. Of course, it is possible to provide further functional layers necessary for the thin film EL element, the solar cell, and the like as needed, and these can all be regarded as functional layers according to the present invention.

FIG. 1 shows a preferred example for carrying out the present invention.

1 is a plasma generation chamber for converting gas into plasma.
Reference numeral 2 denotes a magnetic coil that generates a magnetic field described later in the plasma generation chamber 1 and is provided on the outer periphery of the plasma generation chamber 1. Reference numeral 3 denotes a microwave oscillator that oscillates a microwave of 2.45 GHz. The microwave oscillated by the microwave oscillator 3 passes through a waveguide 4 and is introduced into a microwave introduction window 5 (directly provided in a plasma generation chamber 1). (Introduction or antenna introduction). The introduction window 5 is provided with a partition wall made of an appropriate material that can keep airtightness and allow microwaves to pass therethrough. Reference numeral 6 denotes a hydrogen gas introduction pipe for introducing hydrogen gas to be converted into plasma into the plasma generation chamber 1, and reference numeral 7 denotes a combined gas introduction pipe for introducing a combined gas into the generation chamber 1. Reference numeral 8 denotes a cooling jacket for cooling the wall surface of the plasma generation chamber 1, and cooling water flows through the cooling jacket 8 via a jacket cooling water pipe 9.

Reference numeral 10 denotes a processing chamber in which an etching process is performed. Since the energy of the plasma generated in the plasma generation chamber is high and reaches several tens of eV, if the etching process is performed in this atmosphere, the sample and the equipment may be overheated or irradiated and damaged. And an etching process is performed. The processing chamber 10 and the plasma generation chamber 1 are in communication with each other via a plasma extraction window 11. 12 is processing room 10
A magnetic coil for generating a mirror magnetic field described below. It is provided on the outer periphery of the processing chamber 10. 13 is a sample stage,
Reference numeral 14 denotes a sample placed on the sample stage 13, and 15 denotes a fixed holder for holding the sample 14 on the sample stage. It is to be noted that if a sample supply device that allows the sample 14 to be taken in and out of the processing chamber 10 without breaking the vacuum is provided, it is more convenient and the productivity is improved.

Reference numeral 16 denotes a temperature control device for heating or cooling the sample 14, and is incorporated in the sample table 13. Reference numeral 17 denotes a reaction gas introduction pipe for introducing a reaction gas for promoting a reaction to the sample 14 to be etched. Reference numerals 18a and 18b denote electrodes, which are provided in the plasma extraction window 11. 19 is
This is a power supply device including a high-frequency power supply 19a and a DC power supply 19b, and one of the power supplies is applied between the electrode 18a and the electrode 18b provided on the sample stage 13 by switching a changeover switch 19c. As shown, the DC power supply 19b is configured to apply a negative electrode to the sample stage. 20
Is an exhaust port when the plasma generation chamber 1 and the processing chamber 10 are evacuated, and the degree of vacuum inside the plasma generation chamber 1 is such that when the introduced hydrogen gas contains electrons once within the mean free path. The rotation is maintained at, for example, about 10 ^-3 to 10 ^-4 Torr so that the rotation can be performed.

One of the features of the above-described apparatus is, as described in claim (8) of the present invention, a hydrogen gas supply device (not shown) for introducing a hydrogen gas for plasma into the plasma generation chamber 1 other than the piping 6. A combined gas supply device (not shown) and a piping 7 for introducing the combined gas described in claim (3) into the plasma generation chamber 1 as necessary are provided. This is to provide a reaction gas supply device (not shown) and the same pipe 17 for guiding the reaction gas to a position suitable for bringing the reaction gas into contact with, for example, the transparent electrode and / or the light emitting layer. When introducing a hydrogen gas and a combined gas into the plasma generation chamber, if a gas in which the hydrogen gas and the combined gas are mixed in a desired ratio in advance is used, a supply device and a piping for the combined gas are not required, but the mixing ratio is reduced. In order to arbitrarily change the gas at any time, it is more convenient to provide a supply device and the same pipe according to the number of types of gas used. In this case, it is of course possible to provide a system for mixing the gas outside the plasma generation chamber, and to provide a single system for the introduction pipe to the plasma generation chamber. Further, the number of gas introduction ports to the plasma generation chamber 1 can be provided in plural for each gas type, and there is no particular limitation.

Another feature is that the magnetic coil 12 for generating a mirror magnetic field can be used as required, as described in claim (11) or (12) of the present invention.
And an electrode 18a is provided on the plasma extraction window 11, and the sample table side is located between the electrode 18a and the electrode 18b provided on the sample table 13 for irradiating a functional layer such as a transparent electrode and / or a light emitting layer. This is to provide a power supply device 19 and a wiring for applying a DC voltage or a high-frequency voltage to be a negative polarity, and to form an extraction electric field with respect to a sample.

The mirror magnetic field pinches the divergent magnetic field to reduce the energy of the ions diffused from the plasma generation chamber and to enable the use of low energy level ions, thereby preventing irradiation damage and heating. If necessary, a permanent magnet can be arranged near the lower portion of the sample table 13 and replaced with a mirror magnetic field generating coil.

On the other hand, as a drawing electric field with respect to the sample, a plasma drawn out from the extraction window by applying a DC voltage or a high-frequency voltage between the sample stage 13 and the electrodes provided on the plasma extraction window 11 so that the sample stage side is a negative electrode. As the velocity of ions inside increases, the kinetic energy increases, and the amount of ions and radicals that reach the sample per unit time also increases, which not only significantly enhances the etching efficiency, but also enables uniform extraction with good directivity. In addition to being suitable for large-area processing, sharp etching with a cut etching wall surface can be realized. Further, when a high-frequency voltage is applied, an effect of reactivating the plasma to be neutralized by accompanying local discharge is expected. Note that the DC voltage and the high-frequency voltage applied to the power supply device 19 are merely examples, and other appropriate voltages can be used.

In short, when the energy of ions or radicals increases, heating of the sample and the irradiation target equipment and irradiation damage easily occur,
If the energy of ions or radicals is low, the desired etching time becomes long.

As described above, the apparatus according to the present invention can control the energy of ions and radicals smoothly over a wide range by applying a mirror magnetic field or adjusting the voltage applied to the electrodes 18a and 18b. Extremely high controllability.

[Example 1] Thickness on glass substrate by high frequency magnetron sputtering
A 110 nm tin oxide transparent conductive film was formed, and the ECR shown in FIG.
Placed on a sample stage of a hydrogen plasma etching system, (A) hydrogen gas as plasma generation gas, (B) 95% by volume ratio
Hydrogen gas and 5% argon gas, (C) 91% by volume ratio
Hydrogen gas and 9% carbon tetrachloride gas, (D)
% Hydrogen gas and 9% acetone gas, (E)
% Hydrogen gas and 45% butyl acetate gas were used to perform the etching treatment under the plasma generation and irradiation conditions shown in Table 1, and the etching results shown in Table 2 were obtained.

In the example (A) using hydrogen gas, the etching rate decreases with time. From the appearance, the portion that has been etched at the beginning has a metallic color and the resistance value is slightly lowered, which indicates that the metal is first metallized by the reducing action of hydrogen plasma and then etched by hydrogen plasma. In the example (B), it is found that the sputtering of argon gas works effectively, and in the example (C), the chemical reaction of chlorine ions and chlorine radicals generated by decomposition of carbon tetrachloride is added, so that the etching rate is further increased. You can see that. Examples (D) and (E) show that butyl acetate, which is an acetone gas containing heavy oxygen or methyl group in the molecule, has a large etching promoting effect.

Oxygen is radicalized, which is thought to act to remove the carbon film deposition seen when the organic gas is used as a plasma gas, and methyl groups and the like are radicalized and react with the metallized portion to form an organometallic compound. It is thought to be.

The "initial etching result" shown in Table 2 is a value calculated per minute from the depth etched in 30 seconds from the start of etching. In addition, in cases other than the example (A), the etching rate may increase with time, or may reach a maximum in the middle.

In the case of Table 1 (a) in which a high frequency voltage of 15 KHz is applied to the plasma extraction electrode, the initial etching rate and the desired etching time are both significantly reduced as compared with the case of Table 1 (b) in which no high frequency voltage is applied. . This is considered to be because the ECR hydrogen plasma was accelerated by the electric field and the number of hydrogen ions reaching the transparent tin oxide electrode per unit time increased. In addition, the kinetic energy increased and the sputtering efficiency improved.

It has also been confirmed that the introduction of the combined gas promoted the etching. Specific examples of the combined gas include methane, ethane, propane, butane, pentane, hexane, cyclohexane, ethylene, propylene, butylene, pentene, acetylene, benzene, toluene, and xylene for hydrocarbons, and methanol, ethanol, and propanol for alcohols. , Isopropanol, butanol, isobutanol, acetone, methyl ethyl ketone, diethyl ketone for ketone, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate for ester, dimethyl ether for ether, Diethyl ether and methyl ethyl ether; halogen gas for fluorine and chlorine; hydrogen halide for hydrofluoric acid, hydrochloric acid and bromic acid; halogenated carbon For carbon tetrachloride, chlorotrifluoromethane, dichlorodifluoromethane, chlorofluoroethylene, dichlorotrifluoroethane, octafluoropropane, chlorofluoroethylene, and for halogenated carbon, methylene chloride, ethylene chloride, trichloroethylene , Dichloroethylene, chloroform, clobezen, metadichlorobenzene, paradichlorobenzene, sulfur compound-based gas for sulfurous acid, sulfuric acid, sulfur hexafluoride, carbon disulfide, hydrogen sulfide, and nitrogen oxide-based gas for ammonia, Examples include hydrazine, nitric oxide, nitrogen dioxide, nitric acid, and nitric anhydride.

Example 2 A transparent electrode of antimony-doped tin oxide, a transparent electrode of fluorine-doped tin oxide, a transparent electrode of titanium oxide, a transparent electrode of indium oxide / tin, and a transparent electrode of aluminum-doped zinc oxide prepared by the same method as in Example 1 Are placed on the sample stage of the apparatus shown in FIG. 1, respectively, and carbon tetrachloride and butyl acetate are selected as reaction gases while irradiating ECR hydrogen plasma under the conditions shown in Table 1 (a) of Example 1 through a pipe 17. It was introduced into the processing chamber and brought into contact with the transparent electrode. The results are shown in Table 3.

It can be seen that in the example using this reaction gas, carbon tetrachloride gas or butyl acetate gas is as effective as or more effective than when introduced into the plasma generation chamber as a combined gas. This means that
The reaction gas is decomposed by collision with the hydrogen plasma, and the generated chlorine and the like are ionized and radicalized in the carbon tetrachloride, and the methyl radical is generated in the butyl acetate, and the electric field generated by the high-frequency voltage applied to the extraction electrode is further reduced. It is considered that as a result of further increasing the density and activity of these ions and radicals, the etching is physically and chemically promoted. Particularly, in the case of butyl acetate, the etching rate is high, but it is presumed that the generated methyl radical has a strong effect of chemically removing tin as an organometallic compound such as methylated tin. It can also be seen that the indium tin oxide transparent electrode and the aluminum-doped zinc oxide transparent electrode were also favorably etched by this method.

Both are well etched by this method,
In particular, the reason why the tin oxide-based transparent electrode is etched in a short time is considered to be due to its chemical property that it is particularly easily reduced by hydrogen as compared with the others. It has also been confirmed that the introduction of another reaction gas accelerates the etching. Examples of the reaction gas include the same substances as the above-mentioned combined gases.

The maximum etching rate shown in Table 4 is the maximum value calculated per minute from the depth etched in 30 seconds.

Example 3 An impurity-doped tin oxide transparent electrode formed on a commercially available glass substrate was etched by changing the type and concentration of a reaction gas introduced into a processing chamber under the etching conditions shown in Table 1 (a). did.

This transparent electrode had a forming temperature of about 550 ° C. and a film thickness of about 550 nm.

The average etching rate (value calculated per minute from the depth etched in 3 minutes) is the concentration of the reaction gas (the pressure ratio of the reaction gas to the sum of the pressure of the hydrogen gas and the pressure of the reaction gas in%). increases with shown), but there is a peak, the average etch rate peak and (nm / min) gas concentration at that time is different depending on the type of gas used, the example CC _4, the peak etch rate of 56
The reaction gas concentration at that time was 50% at nm / min, 42 nm / min and 20% for acetone, and 55 nm / min for ethyl alcohol.
Min, 40%, and butyl acetate at 57 nm, 45%. After the peak, the average etching rate decreases rapidly as the concentration of the reaction gas increases, but this is due to a shortage of the absolute amount of hydrogen.
It is presumed that the reduction action by hydrogen was reduced.

In short, the etching rate of the transparent electrode is remarkably accelerated by the reaction gas. However, the presence of hydrogen gas is important, and the etching rate accelerating action of the reaction gas has a peak, and the peak concentration varies depending on the type of gas. Etch productivity is therefore highest at concentrations where the average etch rate peaks.

7 (A) to 7 (D) show the reaction gas CH ₃ C
The graph shows the concentration dependence of the average etching rate for each of OCH ₃ , CC ₄ , CH ₃ COO (CH ₂ ) ₃ CH ₃ and C ₂ H ₅ OH.
As can be seen from these figures, the etching rate of each reaction gas reaches its maximum at a certain concentration, and Table 5 shows the concentration of the reaction gas and the average etching rate at that time.

The amount of the reaction gas exemplified in Example 1 is preferably about 10 to 70% (30 to 90% of hydrogen gas) in concentration, but it is needless to say that other values can be used.
In this example, etching was performed under the conditions shown in Table 1 (a).

Example 4 Under the same conditions as in Example 3, etching of the etching depth and etching rate of the tin oxide transparent electrode (film thickness 540 nm) when 60% by volume of hydrogen gas and 40% of butyl acetate gas were introduced. The time dependence is shown in FIG. At this time, the maximum etching rate is 175 nm / min, and the average etching rate is about
70 nm / min.

Example 5 A 400 nm-thick ZnS: Mn film was formed on a glass substrate by using a plasma focusing magnetic field applying type high-frequency magnetron sputtering apparatus.
(0.5 wt%) layer was formed. Ar was used as a sputtering gas, the gas pressure was 6 × 10 ⁻² Torr, and the substrate temperature was 250 ° C.

This was placed on the sample stage of the ECR hydrogen plasma etching apparatus shown in FIG.
(A) hydrogen gas, (B) 60% hydrogen gas and 40% by volume ratio
Table 1 (a) was subjected to the etching treatment under the plasma-generating irradiation conditions using the butyl acetate gas described above, and the time dependence of the respective etching rates and etching depths was examined. The results are shown in FIGS. 9 and 10, respectively.

In both cases (A) and (B), the ZnS: Mn light emitting layer is easily removed. However, as compared with the case where the transparent electrode is etched, the feature is that it can be easily removed only with hydrogen plasma, and the transparent electrode is etched. That is, the effect of promoting the etching of the combined gas and the reaction gas as observed in the case of the above, particularly, the dramatic effect when the butyl acetate gas is used is not observed.

This means that the ZnS: Mn layer is reduced by hydrogen plasma and the metallized part is removed by hydrogen ion sputtering rather than hydrogen ion generation, and when butyl acetate gas is used in combination, butyl acetate gas is decomposed. It is presumed that the chemical removal action such as the formation of a methylated product by the generated methyl radical is largely working.

This phenomenon can be used as a selective etching method of the light emitting layer when the composite layer of the transparent electrode and the light emitting layer is etched from the light emitting layer side.

Separately, the etching effect was examined under the conditions shown in Table 1 (a) when acetone was added as a combined gas to hydrogen gas, when carbon tetrachloride gas was added, and when ethyl alcohol was added. In both cases, it was recognized that the ZnS: Mn layer was easily and satisfactorily etched,
The use of argon gas alone did not etch, further reinforcing the above presumption that the removal of the metallized portion was based on a chemical removal action.

Example 6 The following experiment was performed to investigate the etching state of the insulating layer in the multilayer thin film element. That is, using the same apparatus as in Example 5, an aluminum oxide layer, a tantalum oxide layer, an yttrium oxide layer, and a silicon oxide layer, each of which is usually used as an insulating layer of an EL light emitting element, were formed on a glass substrate to a thickness of 300 nm. An argon gas containing 20% by volume of oxygen was used as a sputtering gas at a gas pressure of 1 × 10 ^-2 (Torr) and a substrate temperature of 200 ° C.

This was placed on the sample stage of the ECR hydrogen plasma etching apparatus shown in FIG. 1 and processed under the conditions shown in Table 1 (a) using hydrogen gas and applying a high-frequency electric field of 15 KHz, but was not etched at all. Even after treatment for several tens of minutes, slight coloration was observed in yttrium oxide, aluminum oxide, and tantalum oxide, and no change occurred in silicon oxide. Similar results were obtained when another gas such as butyl acetate was used in combination with hydrogen gas.

This is considered to be due to the chemical property that the above-mentioned oxide exemplified as the insulating layer of the thin-film EL element is chemically stable and is hardly subjected to a reducing action by hydrogen.

On the other hand, in the case of the conditions shown in Table 1 (c), that is, when a high-frequency electric field of 13.56 MHz is applied for plasma extraction, all are easily removed, and the time required for etching removal is 310 or less. there were. The results are shown in Table 6.

The conditions in Table 1 (C) are different from those in Table 1 (A).
It is considered that the fact that the frequency of the applied alternating current is orders of magnitude higher causes the physical sputter etching effect due to the collision of plasma to work mainly than the chemical etching effect in the case of Table 1 (a). This means that when a high frequency voltage of a relatively high frequency is applied to the plasma extraction electrode according to claim (12), a physical etching action based on a sputtering phenomenon is selected.
When a DC voltage or a high-frequency voltage of a relatively low frequency is applied, the etching time is significantly shortened as compared with the case where no voltage is applied, but since physical etching is suppressed,
Using the same gas and the same device in the same gas and the same device, depending on the use of the frequency of the power supply, such as the reduction action by active hydrogen, and the chemical etching action by forming hydrides or organometallics. This indicates that the present invention can be used in various other ways.

When no plasma extraction electric field is applied or when a high frequency electric field of a relatively low frequency is applied, the insulating layer is not affected by the hydrogen plasma.
When patterning a transparent electrode or a light emitting layer of an EL element with hydrogen plasma, an etching method that does not affect a layer below each layer, that is, a substrate or an insulating layer, is extremely convenient in terms of manufacturing management. If ECR plasma is used, the ion directivity is strong, so sharp walls may be formed on the electrodes and light emitting layer after etching, and patterning can be performed completely perfectly, which is effective for realizing full-color EL. Etching method.

Example 7 400 nm Z was applied on a commercially available fluorine-doped tin oxide transparent electrode (manufactured by Central Corporation) formed on a glass substrate using a magnetic field applying type high frequency magnetron sputtering apparatus for plasma focusing.
An nS; Mn (0.5 wt%) light emitting layer was formed.

On the light emitting layer thus formed, a character pattern of "EL" and a pattern corresponding to a lead wire connecting the transparent electrode of the character and an external power source are formed by a screen printing method using a PMMA-based resist. The sample was placed on a sample stage of an ECR hydrogen plasma etching apparatus shown in Table 2 and subjected to etching under the conditions shown in Table 1 (a) using a combined gas of 60% hydrogen and 40% butyl acetate gas as a combined gas. The light emitting layer and the transparent electrode other than the part covered with the PMMA-based resist were completely removed. The time required during this time was about 7 minutes.

The PMMA-based resist was removed with a mixed organic solvent, and then a 300-nm-thick tantalum oxide insulating layer was formed using a plasma focusing magnetic field-applied magnetron sputtering apparatus, and a back electrode was formed thereon by aluminum evaporation. . At that time, care was taken not to form an aluminum back electrode in a portion corresponding to a portion corresponding to a conductive wire connecting the transparent electrode and the external electrode of the above-mentioned “EL” character pattern.

When the MIS structure EL device thus produced was driven by a 5 KHz sine wave AC voltage, light emission with a clear outline in the character shape of "EL" was obtained, and the luminance was 100 V and a high luminance of 3000 nt or more. The light emission condition was compared with that of a separately prepared device that had not been subjected to a patterning process, but no difference was observed in appearance. It was found that the etching method of the present invention did not adversely affect the performance of the EL device.

Example 8 A 400 nm ZnS: Mn light emitting layer was formed on a commercially available ITO transparent electrode (manufactured by HOYA) in the same manner as in Example 7.

Using a PMMA-based resist on the above-mentioned light emitting layer, a character pattern of "EL" is formed by a screen printing method, and then placed on a sample stage for ECR hydrogen plasma etching production shown in FIG. Using gas, about 5
The plasma was irradiated for minutes. When the electrical resistance of the area not covered with the PMMA-based resist was measured,
Since it showed a value of 0Ω / □, it was found that the ZnS: Mn light emitting layer was removed and the underlying transparent electrode surface was exposed.

The PMMA-based resist was removed with a mixed organic solvent, then a 300 nm tantalum oxide insulating layer was formed in the same manner as in Example 8, and a back electrode was formed thereon by aluminum evaporation.

When the MIS structure EL device thus manufactured was driven by a 5 KHz sine wave AC voltage, light emission of a clearly defined "EL" character was obtained.

When an image is displayed by patterning the transparent electrode and / or the back electrode, the image contour may be blurred due to scattering of light from the light-emitting end of the light-emitting layer. If patterning is also performed, light scattering is eliminated, so that a clear image can be displayed.

As can be seen from this example, when the composite film of the transparent electrode and the light emitting layer is etched from the light emitting layer side, ZnS: Mn of the light emitting layer is very easily etched by hydrogen plasma, whereas in the case of the transparent electrode, hydrogen Unlike the case where a combined gas or a reaction gas is used, the plasma of a single gas has a much lower removal efficiency, so that the light emitting layer can be easily removed with the transparent electrode left.

Example 9 A 500 nm thick Ta ₂ O ₅ first insulating layer 63 was formed on a commercially available glass substrate 61 and an ITO transparent electrode (manufactured by HOYA) 62 by using a high-frequency magnetron sputtering apparatus for applying a magnetic field for plasma focusing. S400
A Zn: Mn light emitting layer 64 having a thickness of nm and a part of a Ta ₂ O ₅ second insulating layer 65 having a thickness of 200 nm were sequentially formed (FIG. 11). The conditions for forming each layer were the same as those in Examples 5 and 6.

Subsequently, an "EL" character pattern is formed on the second insulating layer 65 by a screen printing method using a PMMA-based resist 66, and then placed on a sample stage of an ECR hydrogen plasma etching apparatus shown in FIG. Using a hydrogen gas of 60% by volume and a butyl acetate gas of 40% as a combined gas, the treatment was carried out for 6 minutes under the conditions shown in Table 1 (c). The time of 6 minutes is the length of time during the removal of the second insulating layer 65 and the etching that extends to the light emitting layer 64, which was found in a previous test. Subsequently, the plasma irradiation time was switched to the condition shown in Table 1 (a) and
Irradiation was continued for one minute, and the light emitting layer 64 was removed (FIG. 12). First
Under the conditions shown in Table (1), the first insulating layer 63 is not affected, so that even if the treatment is performed for a long time, the function of the insulating layer 63 is not impaired, and the light emitting layer 64 can be completely removed. Since the ECR plasma has good directivity, no side etching of the light emitting layer 64 occurs.

Next, the resist 66 was removed with a mixed organic solvent (13th
Figure). Since the surface of the light-emitting layer 64 is covered with the second insulating layer 65 before and after the etching process, there is no concern that the surface of the light-emitting layer 64 will be contaminated or damaged during printing or removal of the resist 66.

Next, by forming Ta ₂ O ₅ with a thickness of 300 nm as the protective layer 67, the thickness of the second insulating layer 65 is set to 500 nm,
It covers the wall surface of the light emitting layer 64 exposed by etching. Further, a back electrode 68 was formed by a vacuum evaporation method to obtain a double-insulated thin film EL device (FIG. 14). When this device was driven by a sine wave AC voltage of 5 KHz, orange light emission of “EL” character having a clear contour was obtained as in Example 8.

Next, formation of a two-color EL element will be described. After the processing shown in FIG. 13, a ZnS: Sn light emitting layer 69 having a thickness of 400 nm and a Ta ₂ O ₅ insulating layer 70 having a thickness of 500 nm are formed, and thereafter, drawn by a screen printing method using a PMMA-based resist 71. By covering the parts other than the “EL” character pattern and placing it on the sample table of the ECR hydrogen plasma etching device again, and performing the same procedure as above,
Light-emitting layer 69 and insulating layer 7 formed on “EL” character pattern
0 was removed by etching (FIG. 15). Next, the resist 71 is removed with a solvent, and then the aluminum back electrode is formed by vapor deposition.
72 were formed (FIG. 16).

In the above embodiment, a thin film element is used as an example of a multilayer thin film element.
Although the description has been made using the EL element, the present invention is also applicable to etching of a functional layer in another multilayer thin film element such as a solar cell.

The present invention is characterized in that when a thin film EL element is formed, its functional layer is etched with hydrogen plasma.

For example, for example, a metal oxide constituting a transparent electrode of a thin film EL element, particularly a tin oxide-based one, or a
Group II metal sulfides, especially zinc sulfide, have the property of being easily reduced by active hydrogen in hydrogen plasma. When these hydrogen plasmas are irradiated, they are first reduced to a metal state having a low evaporation temperature. If you continue irradiation,
The metallized portion is hydrided or easily removed by a sputtering action of hydrogen ions. Here, regarding the removal efficiency of the metallized portion, a transparent electrode such as Sn
In the case of O _2, the effect of using the combined gas and the reaction gas is large, but the hydrogen plasma alone is very low. On the other hand, a light emitting layer,
For example, in the case of ZnS: Mn, the removal efficiency is high even with hydrogen plasma alone, so by operating the conditions around this,
For example, when etching a transparent electrode in the case of an MIS structure, for example, a composite layer of SnO ₂ and a light emitting layer, for example, ZnS: Mn, from the light emitting layer side, if necessary, for example, only hydrogen plasma under the conditions shown in Table 1 (a) , The luminescent layer can be removed preferentially.

On the other hand, for example, aluminum oxide, tantalum oxide, yttrium oxide, silicon oxide, etc., which constitute the insulating layer, are extremely stable when irradiated with hydrogen plasma, are not reduced by active hydrogen and are not metallized, and the mass of the hydrogen plasma is reduced. Since it is small and therefore has low kinetic energy, it is not sputtered when no plasma extraction electric field is applied or when a high frequency electric field having a relatively low frequency is applied. In fact, it does not change even if the insulating layer is left for a long time under the above-mentioned conditions under which the transparent electrode and the light emitting layer can be easily removed.

The above fact, that is, the fact that hydrogen plasma selectively removes a metal compound which is easily reduced by active hydrogen, is based on the fact that the etching method of the present invention, which employs hydrogen plasma, can be used for, for example, transparent thin film EL devices. This indicates that the method is extremely suitable for patterning a functional layer such as an electrode and / or a light emitting layer. The fact that the etching method of the present invention is a dry method is also suitable for the treatment of a light emitting layer that does not like to absorb moisture. Transparent electrode such as SnO ₂ layer and light emitting layer such as ZnS:
In an MIS type EL device in which Mn layers are combined, both layers can be removed safely and simultaneously, but if necessary, the metallized part by hydrogen plasma is more transparent electrode than by sputtering. The application of the present invention is particularly wide, since it is possible to preferentially remove the light-emitting layer by utilizing the property of the light-emitting layer (ZnS), which is particularly easily removed by hydride conversion.

In one embodiment of the present invention, the use of an argon gas having a large mass for the inefficiency of hydrogen plasma (especially in the case of a transparent electrode) with respect to the removal of the metallized portion by the sputtering action, and other appropriate combined gases. It proposes addition and use of a reaction gas. When a combined gas or a reaction gas other than the inert gas is used, the efficiency of the etching is greatly improved by not only improving the efficiency of the sputtering action but also accompanied by a chemical etching action such as formation of an organic metal compound.

In one embodiment of the present invention, etching is performed using hydrogen plasma generated by an ECR method. Compared to plasmas produced by other methods, hydrogen plasma by the ECR method has an order of magnitude higher in ionization rate, so it is suitable for the etching method of the present invention with a reducing action, and because the plasma density is uniform, it has a large area. Also, because it can generate plasma at gas pressures one or two orders of magnitude lower than other plasma generation methods, the mean free path of ions is longer and the ion flow is directional, Since sharp etching can be performed according to a pattern without side etching, precise patterning can be performed, which has a great effect.

The present invention also proposes a suitable apparatus for performing an etching method using hydrogen plasma, wherein the apparatus is an EC.
An R hydrogen plasma irradiation treatment apparatus, which is composed of a hydrogen plasma generation chamber and a processing chamber.As a feature of the apparatus of the present invention, the apparatus is provided with a combined gas or In addition to the inlet tube for introducing the reaction gas, a coil for applying a mirror magnetic field for extracting low-energy level plasma from the generation chamber to the processing chamber as needed, and increasing or decreasing the speed of ions to the sample as needed Means that can apply a plasma extraction electric field for the purpose, and as a result, the etching processing conditions can be controlled in a wide range and easily, so that the optimum etching conditions can be easily selected according to the configuration of the thin film EL element to be patterned. High productivity and a wide range of applications.

[Effects of the Invention] As described in detail above, the present invention provides a multilayer thin film device, for example, a thin film EL device using hydrogen plasma by the ECR method which has an etching effect on a material forming a functional layer such as a light emitting layer and an electrode layer. Since etching is performed, it is possible to accurately pattern a desired layer without damaging the substrate and the like, and particularly for a multilayer thin film element in which a substrate and a functional layer are formed in multiple layers, such as a multicolor EL light emitting element. Effective for manufacturing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an etching apparatus using ECR hydrogen plasma suitable for carrying out the etching method of a multilayer thin film element of the present invention, and FIG. 2 is an EL element having a double insulating structure. FIG. 3 is a cross-sectional view of an EL element having a MIS structure, and FIGS. 4 (A) to 4 (C) are cross-sectional views of the EL element.
FIGS. 5 (A) and 5 (B) are cross-sectional views showing an example of patterning in the device, FIGS. 5 (A) and 5 (B) are a plan view and a cross-sectional view of an XY matrix type EL device using stripe electrodes, and FIGS.
FIGS. 7 (A) to 7 (D) are plan views of the light emitting layer as a dot matrix system. FIGS. 7 (A) to 7 (D) show CH ₃ COCH ₃ , CC ₄ and CH ₃ (CH ₂ ) as reaction gases in the apparatus of FIG. ₃ CH ₃ and C
FIG. 8 shows the etching rate of the transparent electrode when using ₂ H ₅ OH, and FIG. 8 shows the etching depth and the etching rate of the tin oxide transparent conductive film when using butyl acetate gas as the reaction gas. FIGS. 9 and 10 show the etching depth and the etching rate of the ZnS: Mn light-emitting layer when hydrogen gas, 60% hydrogen gas and 40% butyl acetate gas by volume are used as the plasma generation gas, respectively. FIG. 11 to FIG.
FIG. 14 is a cross-sectional view illustrating a process of forming an EL element having a double insulating structure, and FIGS. 15 and 16 are cross-sectional views illustrating a process of forming a two-color EL element. 1 ... plasma generation chamber, 2, 12 ... magnetic coil, 3 ... microwave oscillator, 4 ... waveguide, 5 ... introduction window, 6 ...
Hydrogen gas introduction pipe, 7 ... combined gas introduction pipe, 8 ... cooling jacket, 9 ... jacket cooling water pipe, 10 ... processing chamber, 11 ... plasma extraction window, 13 ... sample table, 14 ... sample , 15 ... fixed holder, 16 ... temperature controller, 17 ... reaction gas introduction piping, 18a, 18b ... electrodes, 19a ... high frequency power supply, 19b ... DC power supply, 20 ... exhaust port, 51 ... ... Transparent substrate, 52 ... Transparent electrode, 53 ... First insulating layer,
54 ... light emitting layer, 55 ... second insulating layer, 56 ... back electrode.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23F 4/00 H01B 13/00 503 H01L 21/3065, 21/28 H01L 31/18

Claims (13)

(57) [Claims] 1. A method for etching a multi-layer thin film element, wherein at least one of the functional layers in the multi-layer thin film element is etched using hydrogen plasma generated in a plasma generation chamber using an electron cyclotron resonance method. . 2. Hydrogen plasma in a plasma generation chamber is composed of an inert gas, nitrogen, oxygen, hydrocarbon, alcohol, ketone, ester, ether, halogen gas, hydrogen halide, halogenated carbon, halogenated hydrocarbon, and sulfur compound. Claims (1) wherein a radical or plasma of at least one kind of gas selected from a gas and a nitrogen compound-based gas is used in combination.
3. The method for etching a multilayer thin film element according to item 1. 3. A hydrogen plasma generated in a plasma generation chamber is introduced into a processing chamber, and nitrogen, oxygen, hydrocarbon, alcohol, ketone, ester, ether, and halogen gas are used for etching a multilayer thin film element disposed in the processing chamber. 3. The method according to claim 1, wherein at least one gas selected from the group consisting of hydrogen halide, halogenated carbon, halogenated hydrocarbon, sulfur compound-based gas, and nitrogen compound-based gas is reacted as a reaction gas. The method for etching a multilayer thin film element according to any one of the above items. 4. The etching of the multilayer thin film element according to claim 3, wherein the etching strength is changed by changing the frequency of an extraction electric field applied to guide the hydrogen plasma generated in the plasma generation chamber to the processing chamber. Method. 5. The method according to claim 1, wherein a resist pattern is formed on a desired portion on the functional layer in the multilayer thin film element, and at least one layer of the functional layer other than the portion where the resist pattern is formed is selectively etched. The method for etching a multilayer thin film element according to any one of the above items 4). 6. The method for etching a multilayer thin film device according to claim 1, wherein the multilayer thin film device is a thin film EL device having at least a light emitting layer and a transparent electrode as functional layers. 7. A microwave is introduced into a evacuated plasma generation chamber, and a magnetic field is further applied from the outside. The plasma generation gas introduced into the plasma generation chamber is subjected to electron cyclotron resonance to generate plasma, and the plasma is generated in the processing chamber. An ECR plasma processing apparatus for etching at least a predetermined portion of at least one functional layer in a multilayer thin film element using the plasma, comprising a hydrogen gas introduction pipe for introducing hydrogen as a plasma generation gas. Etching equipment for multilayer thin film elements. 8. The etching apparatus for a multilayer thin film element according to claim 7, further comprising a reaction gas introducing means for introducing various reaction gases into the processing chamber in order to accelerate the etching process in the processing chamber. 9. The etching of a multilayer thin film element according to claim 7, wherein a device for adjusting the temperature is provided on the sample stage in order to control the temperature of the object to be etched. apparatus. 10. A magnetic field applying means for generating a mirror magnetic field in the processing chamber in order to reduce the energy level of hydrogen plasma generated in the plasma generating chamber.
An etching apparatus for a multilayer thin film element according to any one of claims (7) to (9). 11. An electrode is provided on a plasma extraction section for guiding hydrogen plasma generated in the plasma generation chamber to a processing chamber, and on a sample stage on which an object to be etched is arranged.
A power supply device for applying a high-frequency voltage or a DC voltage from the sample stage side to a negative electrode between the two electrodes, and applying a plasma extraction electric field to at least one of the functional layers in the thin film element. The etching apparatus for a multilayer thin film element according to any one of 10) to 10). 12. The etching apparatus for a multilayer thin film element according to claim 11, wherein the etching strength is changed by changing a frequency of a plasma extraction electric field applied to the electron cyclotron resonance hydrogen plasma. 13. The etching apparatus for a multilayer thin film element according to claim 7, wherein the multilayer thin film element is a thin film EL element having at least a light emitting layer and a transparent electrode as functional layers.