TWI679308B - Etching solution composition for silver and display substrate using the same - Google Patents

Abstract

The present invention relates to a silver etchant composition and a display substrate using the same, the composition including phosphoric acid, nitric acid, acetic acid, methyltetrazole, and deionized water, and the silver etchant composition prevents excessive etching of silver or silver by preventing The alloy layer can be used to prepare micropatterns, which is effective in controlling the process easily by controlling the etching rate, preventing the occurrence of residues and re-adsorption, and has excellent stability over time.

Description

Silver etching liquid composition and display substrate using the same Technical field

The present invention relates to a silver etchant composition and a display substrate using the same, and more particularly, to a silver etchant composition including phosphoric acid, nitric acid, acetic acid, methyltetrazole, and deionized water, and a display substrate using the same.

Background of the invention

With the advent of the age of comprehensive information, the field of displays that process and display large amounts of information has developed rapidly. In response to this phenomenon, various flat panel displays have been developed and attracted attention.

Examples of such a flat display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), an electroluminescent display device (ELD), an organic light emitting diode (OLED), etc. And the like, and such a flat display device is used for various uses not only in the field of consumer electronic devices such as televisions and videos but also in computers such as notebook computers, mobile phones, and the like. These flat panel display devices are rapidly replacing existing cathode ray tubes (NIT) due to their excellent properties such as thin shape, light weight, and low power consumption.

In particular, OLEDs can be driven at low voltages while emitting light from the device itself. Therefore, OLEDs have been rapidly used in small displays such as mobile devices. market. In addition, after commercialization in small displays, commercialization of OLEDs in large-sized TVs is coming.

At the same time, conductive metals such as indium tin oxide (ITO) and indium zinc oxide (IZO) have relatively excellent light transmittance and conductivity, and therefore, they have been widely used as electrodes for color filters used in flat panel display devices. . However, these metals also have high resistance, which is an obstacle to the expansion of flat panel display devices and the realization of high resolution by improving the response rate.

In addition, in the case of a reflecting plate, an aluminum (Al) reflecting plate is mainly used as a product, however, in order to obtain low power consumption by improving brightness, it has been engaged in changing the material to a metal having higher reflectance. For this reason, attempts have been made to use a silver (Ag: specific resistance of about 1.59 μΩ · cm) layer, silver alloy, or silver having a lower specific resistance and higher brightness than a metal used in a flat panel display device for a color filter electrode. Including their multiple layers, LCD or OLED wires and reflective plates have been made to achieve the expansion, high resolution, and low power consumption of flat panel display devices, and the development of etching solutions for the use of this material is required.

However, silver (Ag) has extremely poor adhesion to the underlying substrates such as insulating substrates such as glass, and semiconductor substrates formed of pure amorphous silicon, doped amorphous silicon, etc., so it is not easy to deposit, and it is easy to cause the wires to lift or peel off. . In addition, when a silver (Ag) conductive layer is deposited on the substrate, an etching solution is used to pattern the conductive layer. When an existing etchant is used here as such an etchant, silver (Ag) is excessively etched or unevenly etched, causing the lead to lift up or peel off, and the side profile of the lead is deteriorated.

The silver etchant disclosed in Korean Patent No. 10-0579421 utilizes phosphoric acid, nitric acid, and acetic acid, and together with the auxiliary oxide solvent and fluorocarbon-based surfactant as additives. However, the disadvantage is that the SO ₄ ^2- compound used as the auxiliary oxide solvent reacts with silver (Ag) and remains in the substrate in the form of silver sulfide (Ag ₂ S), and the use of ClO ₄ ^- compounds is problematic because These compounds are currently specified as materials subject to environmental regulations. In addition, the fluorocarbon-based surfactant has a problem in that when the lower layer of silver is an organic insulating film, the organic insulating film located on the edge of the substrate is easily eroded by the etchant and a peeling phenomenon occurs therefrom.

[Existing technical literature] [Patent Literature]

(Patent Document 1) Korean Patent No. 10-0579421

Summary of invention

An object of the present invention is to provide a silver etchant composition capable of forming a pixel electrode wire by preventing excessive etching of a metal layer including silver, and thus a wire having a micropattern can be formed.

Another object of the present invention is to provide a silver etchant composition that can facilitate program control by adjusting the etching rate of a metal layer including silver, can prevent silver re-adsorption, has no residue, and has excellent stability over time.

It is still another object of the present invention to provide a display substrate and a lead using a silver etchant composition.

In view of the above, one aspect of the present invention provides a silver etchant composition, which comprises 30 to 70% by weight of phosphoric acid, 0.5 to 10% by weight of nitric acid, and 0.5 to 30 with respect to the total weight of the silver etchant composition. Wt% acetic acid and 0.01 to 10 wt% methyltetrazole, and the balance of deionization Water so that the total weight of the composition becomes 100% by weight.

Another aspect of the present invention provides a display substrate including a metal layer etched using the silver etchant composition.

Yet another aspect of the present invention provides a wire etched with the silver etchant composition.

The objects and properties of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: FIG. 1 is not observed when etched with the silver etchant composition of the present invention SEM photograph of silver residue (without Ag residue); FIG. 2 is a SEM photograph of the presence of silver residue (Ag residue) when etched with a conventional silver etchant composition; FIG. 3 is when the silver etchant of the present invention is used When the composition was etched, no SEM photograph of silver re-adsorption was observed (without Ag re-adsorption); and FIG. 4 is an SEM photograph of silver re-adsorption observed when Ag etching was performed with a conventional silver etchant composition Adsorption).

detailed description

Hereinafter, the present invention will be described in more detail.

The present invention relates to a silver etching solution composition, which includes 30 to 70% by weight of phosphoric acid, 0.5 to 10% by weight of nitric acid, 0.5 to 30% by weight of acetic acid, and 0.01 to 30% by weight of the total amount of the silver etching solution composition. 10% by weight of methyltetrazole and the balance of deionized water make the total weight of the composition 100% by weight.

The silver etchant composition of the present invention can etch a single layer formed of silver (Ag) or a silver alloy, or a plurality of layers formed of the single layer and an indium oxide layer, and the plurality of layers can be etched simultaneously.

The silver alloy has silver as a main component, and may have various forms such as an alloy form including other metals such as Nd, Cu, Pd, Nb, Ni, Mo, Ni, Cr, Mg, W, and Ti, or nitrogen of silver Carbide, silicide, carbide, and oxide forms, but are not limited thereto.

In addition, the indium oxide is one or more selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and indium gallium zinc oxide (IGZO).

In addition, the multilayer may be a multilayer formed of an indium oxide layer / silver, an indium oxide layer / silver alloy, an indium oxide layer / silver / indium oxide layer, or an indium oxide layer / silver alloy / indium oxide layer, and because the etching is obtained The silver etchant composition of the present invention can be used for wet etching without damaging the uniformity.

Phosphoric acid (H ₃ PO ₄ )

Phosphoric acid (H ₃ PO ₄ ) included in the silver etchant composition of the present invention is a main etchant, and performs a role of generating oxidation and reduction reactions with silver (Ag) or a silver alloy when single or multiple layers are etched, and Wet etching is performed by dissociating the indium oxide layer.

The phosphoric acid accounts for 30 to 70% by weight, and preferably 40 to 60% by weight, with respect to the total weight of the silver etchant composition.

When the phosphoric acid accounts for less than 30% by weight, sufficient etching may not be achieved due to insufficient etching ability. In addition, when a certain amount or more of silver (Ag) is dissolved and introduced into the silver etchant composition as the procedure progresses, Silver (Ag) re-adsorption or silver (Ag) precipitation, which causes electrical shorts in subsequent procedures and may become the cause of defects.

When the phosphoric acid accounts for more than 70% by weight and etches a plurality of layers in which an indium oxide layer is laminated on a single layer of silver or a silver alloy, the etching rate of the indium oxide layer decreases, and the etching rate of the silver or silver alloy becomes too high, resulting in Excessive etching, therefore, may result in an amount of etching that cannot achieve the effect of the wire. In addition, a sharpness due to a difference between an etching rate of silver or a silver alloy and an etching rate of an indium oxide layer is generated, causing a problem in a subsequent procedure.

Nitric acid (HNO ₃ )

The nitric acid included in the silver etchant composition of the present invention is a component that performs an auxiliary etchant function, and when etching a single layer of silver or a silver alloy, or a multilayer in which an indium oxide layer is laminated on a single layer of silver or a silver alloy The effect of wet etching is performed by oxidizing the silver (Ag) or silver alloy and the indium oxide layer.

The nitric acid accounts for 0.5 to 10% by weight, and preferably 2 to 10% by weight, with respect to the total weight of the silver etchant composition.

When the nitric acid content is less than 0.5% by weight, the etching rate of the silver or silver alloy and the indium oxide layer decreases. As the subsequent processing progresses, electrical shorts, dark spot defects, and residual residue areas may appear dark due to the silver residue. phenomenon.

In addition, when the nitric acid content is more than 10% by weight, it is difficult to perform etching control in the program because the etching rate is excessive, and due to the occurrence of excessive etching, the function as a wire cannot be achieved.

Acetic acid (CH ₃ COOH)

The acetic acid (CH ₃ COOH) included in the silver etchant composition of the present invention functions as a buffer to control the reaction rate and the like, and controls the dissociation rate of nitric acid, and generally performs a role of reducing the dissociation rate of nitric acid.

The acetic acid accounts for 0.5 to 30% by weight, and preferably 1 to 20% by weight, with respect to the total weight of the silver etchant composition.

When the acetic acid accounts for less than 0.5% by weight, the uniformity of the wire etching of the display substrate, and more specifically the TFT array substrate, decreases, which may cause the wire resistance to increase due to the reduction of the straightness of the wire, or may cause defects in subsequent procedures, and because The etching rate in the substrate becomes non-uniform and the problem of smear formation occurs on the substrate.

In addition, when the acetic acid accounts for more than 30% by weight, the etching rate becomes very low, which causes a problem that it is difficult to control the maximum program time, that is, the maximum time for which the program is applicable.

Methyltetrazole (MTZ)

Methyltetrazole (MTZ) included in the silver etchant composition of the present invention is a component that performs a corrosion inhibitory action that slows down the etching rate of silver (Ag) or a silver alloy, and does not relatively decrease when etching multiple layers The rate of the indium oxide layer, so that the tip of the indium oxide layer can be suppressed, and the etching time in the program can be controlled. In addition, methyltetrazole is capable of forming fine pixel electrode wires by preventing excessive etching of silver (Ag), and can be used as an additive in an etchant composition and similar cases in which patterned micro wires are formed.

In addition, when a single layer of silver or a silver alloy is etched using an etchant composition without a barrier layer such as an indium oxide layer, over-etching has often occurred in the art in the past. To prevent this phenomenon, barrier layers are used on the upper and lower sides of the single layer, however, this causes an increase in cost in the procedure.

However, the silver etchant composition of the present invention uses methyltetrazole and thus can prevent over-etching. Therefore, there is no need to use a barrier layer, which can reduce process time and save raw materials, so that production costs can be reduced.

Relative to the total weight of the silver etching solution composition, methyltetrazole accounts for 0.01 to 10% by weight.

When the content of methyltetrazole is less than 0.01% by weight, the effect of lowering the etching rate may not be properly performed, and thus, when the wire is formed to have a micropattern, a wire loss defect due to excessive etching may occur.

In addition, when the content of methyltetrazole is more than 10% by weight, since the etching rate of silver or a silver alloy is significantly reduced, an electrical short circuit may occur, and the excess portion is not completely etched away, causing defects to appear. In addition, because the etching rate is reduced, residue is left. Therefore, after the subsequent process is carried out, when the product is manufactured, a defect called dark spots may be caused, that is, a phenomenon in which some areas appear black.

The deionized water included in the silver etching solution composition of the present invention uses water for semiconductor processing, and preferably 18 MΩ. cm or higher.

In addition to the components described above, the silver etchant composition of the present invention may further include one or more of an etching control agent and a pH adjuster commonly used in the art.

The etching control agent which may be further included is an acetate compound included in potassium acetate or sodium acetate, and the pH adjuster which may also be included is included in glycolic acid, glutamic acid, or glycine An organic acid compound.

In addition, the present invention provides a display substrate including a metal layer etched using the silver etchant composition of the present invention.

More specifically, the display device may be a thin film transistor (TFT) substrate of a liquid crystal display device (LCD) or an organic light emitting device (OLED).

In addition, the OLED may have a metal layer stacked on the upper and lower sides of the OLED, and the metal layer may be etched by using the etchant composition of the present invention. By adjusting the thickness of the metal layer, and then laminating the metal layer on the upper and lower sides, the metal layer can perform the functions of a reflective film and a semi-permeable film in the OLED.

The reflective film needs to have a thickness that hardly allows light transmission, and the semi-permeable film needs to have a thickness that transmits almost all light. Therefore, the metal layer preferably has a thickness of 50 Å to 5000 Å.

The metal layer is a single layer formed of silver (Ag) or a silver alloy, or a plurality of layers formed of the single layer and an indium oxide layer.

The silver alloy has silver as a main component, and may have various forms such as an alloy form including other metals such as Nd, Cu, Pd, Nb, Ni, Mo, Ni, Cr, Mg, W, and Ti, or nitrogen of silver Carbide, silicide, carbide, and oxide forms, but are not limited thereto.

In addition, the indium oxide is one or more selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and indium gallium zinc oxide (IGZO).

In addition, the multilayer may be a multilayer formed of an indium oxide layer / silver, an indium oxide layer / silver alloy, an indium oxide layer / silver / indium oxide layer, or an indium oxide layer / silver alloy / indium oxide layer.

In addition, the present invention provides a wire etched with the silver etchant composition of the present invention.

More specifically, the wire is a tracking wire that reads signals sensed mostly in X and Y coordinates in a touch screen panel (TSP), or a flexible silver nanowire.

In addition, the wire is a single layer formed of silver (Ag) or a silver alloy, or a plurality of layers formed of the single layer and an indium oxide layer.

The silver alloy has silver as a main component, and may have various forms such as an alloy form including other metals such as Nd, Cu, Pd, Nb, Ni, Mo, Ni, Cr, Mg, W, and Ti, or nitrogen of silver Carbide, silicide, carbide, and oxide forms, but are not limited thereto.

In addition, the indium oxide is one or more selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and indium gallium zinc oxide (IGZO).

In addition, the multilayer may be a multilayer formed of an indium oxide layer / silver, an indium oxide layer / silver alloy, an indium oxide layer / silver / indium oxide layer, or an indium oxide layer / silver alloy / indium oxide layer.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited to the following examples. The following embodiments may be appropriately modified or changed by those skilled in the art within the scope of the present invention.

<Preparation of silver etching solution composition> Examples 1 to 7 and Comparative Examples 1 to 11

The silver etchant composition is obtained by combining the components described in Table 1 below with Content is prepared by mixing.

Test example 1. Performance test of silver etchant composition

The test piece was prepared as follows: an organic insulating film was deposited on the substrate, and an ITO / Ag / ITO three-layer film was deposited thereon, and then the product was cut into a diamond knife 500X600mm.

Performance tests were performed using the silver etchant compositions of Examples 1 to 7 and Comparative Examples 1 to 11 as follows.

1. Measurement of the etching distance (S / E) on the side of the reflective film (or wire)

The silver etching solution compositions of Examples 1 to 7 and Comparative Examples 1 to 11 were each put into a spray etching type test equipment (model name: ETCHER (TFT), K.C. Tech Co., Ltd.). The temperature was set at 40 ° C and the temperature was raised. When the temperature reached 40 ± 0.1 ° C, the test piece was etched. The total etching time is 60 seconds.

After placing the substrate, spraying was started. When the etching time of 60 seconds had passed, the substrate was taken out, washed with deionized water, and then dried with a hot air dryer. After the substrate was washed and dried, the substrate was cut and its cross section was measured using a scanning electron microscope (SEM; model name: SU-8010, manufactured by HITACHI, Ltd.). As a measurement standard for the side etching distance, the width from the photoresist end to the inside of the cavity formed by etching the metal was measured and evaluated using the following standards. The results are shown in Table 2 below.

<Evaluation Criteria for Side Etching Distance Measurement>

Excellent: below 0.5μm

Good: greater than 0.5 μm and less than 1.0 μm

Difference: greater than 1.0 μm

2. Residue measurement

The silver etching solution compositions of Examples 1 to 7 and Comparative Examples 1 to 11 were each put into a spray etching type test equipment (model name: ETCHER (TFT), K.C. Tech Co., Ltd.). The temperature was set at 40 ° C and the temperature was raised. When the temperature reached 40 ± 0.1 ° C, the test piece was etched. The total etching time is 60 seconds.

Spraying was started after the substrate was placed. When the etching time of 60 seconds had elapsed, the substrate was taken out, washed with deionized water, and then dried with a hot air dryer, and was stripped with a photoresist stripper (PR stripping Agent) to remove the photoresist. After the substrate was washed and dried, a residue was measured using a scanning electron microscope (SEM; model name: SU-8010, manufactured by HITACHI, Ltd.), that is, unetched silver (Ag ) Residual phenomenon was evaluated using the following criteria. The results are shown in Table 2 below.

<Evaluation criteria for residue measurement>

Excellent: no residue (Figure 1)

Poor: Residues appear (residues are a phenomenon of incomplete etching and exist in an amorphous form on the entire substrate surface. Figure 2)

3. Measurement of etching rate

The silver etching solution compositions of Examples 1 to 7 and Comparative Examples 1 to 11 were each put into a spray etching type test equipment (model name: ETCHER (TFT), K.C. Tech Co., Ltd.). The temperature was set at 40 ° C and the temperature was raised. When the temperature reached 40 ± 0.1 ° C, the test piece was etched. The total etching time is 60 seconds.

The end point detection (EPD) was measured with the naked eye to obtain the etch rate (E / R) over time. When the thickness of the etched metal layer is divided by the EPD, an etch rate of Å (thickness) / second (time) (Å / sec) can be obtained. The evaluation was performed using the following criteria, and the results are shown in Table 2 below.

<Evaluation Criteria for Etching Rate>

Excellent: 100Å / sec or less

Good: greater than 100Å / sec and less than 200Å / sec

Difference: greater than 200Å / sec

4. Measurement of stability over time

A benchmark etching test was performed using the silver etchant compositions of Examples 1 to 7 and Comparative Examples 1 to 11, and the remaining silver etchant composition was stored at 25 ° C. for a specified date (in months). After that, etching was performed again using the stored silver etchant composition under the same conditions as the above-mentioned etching rate test, and the results were compared with those in the reference etching test. The evaluation was performed using the following criteria, and the results are shown in Table 2 below.

<Evaluation criteria for stability over time>

Excellent: Etching profile is good until 180 days

Good: Etched profile is good until 30 days

Poor: Etching profile is poor within 30 days

5. Measurement of resorption

The silver etching solution compositions of Examples 1 to 7 and Comparative Examples 1 to 11 were each put into a spray etching type test equipment (model name: ETCHER (TFT), K.C. Tech Co., Ltd.). The temperature was set at 40 ° C and the temperature was raised. When the temperature reached 40 ± 0.1 ° C, the test piece was etched. The total etching time is 60 seconds.

Spraying was started after the substrate was placed. When the etching time of 60 seconds had elapsed, the substrate was taken out, washed with deionized water, and then dried with a hot air dryer, and was stripped with a photoresist stripper (PR stripping Agent) to remove the photoresist. After the substrate is washed and dried, most of the etched silver (Ag) is adsorbed to, for example, the position where the data lines of different metals are exposed, or the specific position where friction may occur due to the winding phenomenon. , Analysis was performed by comprehensive observation using a scanning electron microscope (SEM; model name: SU-8010, manufactured by HITACHI, Ltd.). Evaluation using the following criteria, The results are shown in Table 2 below.

<Evaluation criteria for resorption measurement>

Excellent: no re-adsorption (Figure 3)

Poor: Re-adsorption occurs (silver re-adsorption is caused by reduction and is observed as a ball at the above-mentioned specific position. Figure 4)

According to the results of Table 2, the silver etchant compositions of Examples 1 to 7 of the present invention including methyltetrazole showed excellent or good results in all five evaluations.

Meanwhile, the silver etching solution combinations of Comparative Examples 1 to 11 including other types of azole compounds instead of methyltetrazole, or including phosphoric acid, nitric acid, acetic acid, and methyltetrazole in amounts lower or higher than the content range of the present invention Objects did not show excellent or good results in all five evaluations, but showed poor results in one or more evaluations.

Therefore, it can be seen from the test that, in the silver etchant composition of the present invention, no residue and re-adsorption occur when the metal layer including silver is etched, the etching rate is controllable, and the stability over time is excellent of.

The silver etching solution composition of the present invention prevents silver re-adsorption and the occurrence of residues, and is effective in obtaining excellent stability over time.

In addition, the silver etchant composition of the present invention can form a pixel electrode lead by preventing excessive etching of a metal layer including silver, and thus can form a lead having a micropattern.

In addition, the silver etchant composition of the present invention can easily control a program by controlling the etching rate of a metal layer including silver.

In addition, a display substrate including a metal layer etched with the silver etchant composition of the present invention has excellent driving properties.

Claims (5)

A silver etchant composition with respect to the total weight of the silver etchant composition, comprising: 30 to 70% by weight phosphoric acid; 0.5 to 10% by weight nitric acid; 0.5 to 30% by weight acetic acid; 0.01 to 10 % By weight of methyltetrazole; and the balance of deionized water such that the total weight of the composition becomes 100% by weight. The silver etching solution composition as claimed in claim 1, which is capable of etching a single layer formed of silver or a silver alloy, or a plurality of layers formed of the single layer and the indium oxide layer simultaneously. The silver etchant composition according to claim 2, wherein the indium oxide is one or more selected from the group consisting of indium tin oxide, indium zinc oxide, indium tin zinc oxide, and indium gallium zinc oxide. The silver etchant composition according to claim 2, wherein the multilayer formed by the single layer and the indium oxide layer is an indium oxide layer / silver, an indium oxide layer / silver alloy, an indium oxide layer / silver / indium oxide layer, or indium oxide Layer / silver alloy / indium oxide layer. The silver etchant composition as claimed in claim 1, further comprising: an etching control agent; or a pH adjusting agent.