KR102700443B1 - Etchant composition for silver thin layer and etching method and method for fabrication metal pattern using the same - Google Patents

Abstract

The present invention relates to a silver thin film etchant composition comprising (A) a silver etching accelerator; (B) an inorganic acid; (C) a bisulfate; and (D) water, and to an etching method and a method for forming a metal pattern using the same.

Description

{ETCHANT COMPOSITION FOR SILVER THIN LAYER AND ETCHING METHOD AND METHOD FOR FABRICATION METAL PATTERN USING THE SAME}

The present invention relates to a thin film etching composition, an etching method using the same, and a method for forming a metal pattern.

As we enter the full-fledged information age, the display field that processes and displays large amounts of information has developed rapidly, and in response, various flat panel displays have been developed and are receiving attention.

Examples of flat panel display devices include liquid crystal display devices (LCD), plasma display panel devices (PDP), field emission display devices (FED), electroluminescence display devices (ELD), and organic light emitting diodes (OLED). These flat panel display devices are used for a variety of purposes, not only in home appliances such as televisions and videos, but also in computers such as laptops and cell phones. These flat panel display devices are rapidly replacing the previously used cathode ray tubes (CRT) due to their superior performances such as thinness, weight reduction, and low power consumption.

In particular, OLEDs are rapidly being applied to the small display market for mobile devices, etc., because they emit light by themselves and can be operated at low voltages. In addition, OLEDs are on the verge of commercialization in large TVs beyond small displays.

Also, in the case of reflectors, aluminum (Al) reflectors have been mainly used in products in the past, but in order to realize low power consumption through improved brightness, a change in material to a metal with higher reflectivity is being sought. To this end, silver (Ag: resistivity approximately 1.59 μΩ cm) films, silver alloys, or multilayer films containing them, which have lower resistivity and higher brightness than the metals applied to flat panel displays, are being applied to electrodes of color filters, LCD or OLED wiring, and reflectors to realize large-scale flat panel displays, high resolution, and low power consumption, and therefore, the development of an etchant for the application of these materials has been required.

However, silver (Ag) has extremely poor adhesion to insulating substrates such as glass or semiconductor substrates made of intrinsic amorphous silicon or doped amorphous silicon, making deposition difficult and easily causing lifting or peeling of the wiring. In addition, even when a silver (Ag) conductive layer is deposited on a substrate, an etchant is used to pattern it. When a conventional etchant is used as this etchant, the silver (Ag) is excessively or unevenly etched, causing lifting or peeling of the wiring and a poor side profile of the wiring.

Additionally, there are difficulties in implementing low skew for high resolution implementation.

In particular, silver (Ag) is a metal that is easily reduced, so the etching speed must be fast so that etching can be performed without causing residue. However, it is difficult to form a taper angle after etching and it is difficult to secure the straightness of the etching pattern, so there are many limitations when forming wiring and patterns. In addition, when etching a silver thin film using a silver etchant composition, there is a problem that the etched silver particles are re-adsorbed on the metal film of the S/D portion exposed in the substrate, and in this case, an electrical short may occur in the subsequent process, which may become the cause of defects, which is problematic.

In this regard, phosphoric acid-based silver etchant compositions, which essentially use phosphoric acid as a main oxidizing agent, have been mainly developed, such as those disclosed in Korean Patent Publication No. 2008-0009866, but problems with the phosphoric acid-based etchant compositions, such as damage to the underlying film due to phosphoric acid, are occurring. Therefore, there is a need for the development of an etchant composition having excellent silver etching characteristics even without phosphoric acid, and in particular, there is a need for the development of a non-phosphoric acid-based silver etchant composition that can completely solve the major problems in the relevant technical field, such as residue and silver re-adsorption problems and the performance degradation of the etchant composition due to an increase in the number of treatments.

Republic of Korea Publication Patent No. 10-2008-0009866

The present invention is intended to improve the problems of the prior art described above, and aims to provide a silver thin film etchant composition that can be used for etching a single film made of silver (Ag) or a silver alloy and a multilayer film composed of the single film and a transparent conductive film, and that can reduce the amount of side etching and suppress the occurrence of silver residue and silver re-adsorption while allowing long-term repeated use.

In addition, the present invention aims to provide a silver thin film etching composition capable of etching the single film and the multilayer film simultaneously.

In addition, the present invention aims to provide a silver thin film etchant composition that can be usefully used in wet etching that exhibits etching uniformity without damaging the underlying film.

In addition, the present invention aims to provide an etching method and a method for forming a metal pattern using the silver thin film etching composition.

To achieve the above object, the present invention provides a silver thin film etching composition comprising: (A) a silver etching accelerator; (B) an inorganic acid; (C) a bisulfate; and (D) water.

In addition, the present invention provides an etching method using the silver thin film etching solution composition.

In addition, the present invention provides a method for forming a metal pattern using the silver thin film etching composition.

The silver thin film etchant composition of the present invention is used for etching a single film made of silver (Ag) or a silver alloy and a multilayer film composed of the single film and a transparent conductive film, thereby providing an effect of suppressing residue (e.g., silver residue and/or transparent conductive film residue, etc.) and silver re-adsorption.

In addition, the silver thin film etching composition of the present invention can maintain its fresh properties even after the number of treatments has accumulated, so it can be used repeatedly over a long period of time.

In addition, the silver thin film etching composition of the present invention can simultaneously etch the single film and the multilayer film, thereby improving the etching efficiency.

In addition, the silver thin film etching composition of the present invention can prevent overetching of the single film and the multilayer film, thereby reducing the side etch amount, thereby forming a fine pattern.

In addition, the silver thin film etchant composition of the present invention can be usefully used in wet etching that exhibits etching uniformity without damaging the underlying film.

The present invention relates to a silver thin film etchant composition comprising (A) a silver etching promoter, (B) an inorganic acid, and (C) a bisulfate, and (D) water as a solvent, and an etching method using the same and a method for forming a metal pattern.

The silver thin film etchant composition of the present invention and the etching method and metal pattern forming method using the same can be used for etching a single film made of silver (Ag) or a silver alloy and a multilayer film made of the single film and a transparent conductive film, and is particularly characterized in that, since it contains bisulfate, residues (for example, silver residues and/or transparent conductive film residues, etc.) and silver readsorption problems do not occur. The readsorption may mean a phenomenon in which etched silver particles are attached to a metal film of an S/D (source/drain) portion exposed within a substrate, and the metal film of the S/D portion exposed within the substrate may be a single film or multilayer film made of Mo, Cu, and an alloy thereof, and may be readsorption of silver on some or all of the upper Ti, the central Al, and the lower Ti of the triple film.

In addition, the silver thin film etchant composition of the present invention can maintain new liquid properties even after the number of processing runs has accumulated, so that it can be used repeatedly over a long period of time. Not only does the problem of residue and silver re-adsorption not occur even at the beginning of the etching process, but even when the number of processing runs is high due to the long-term etching process, no residue occurs and the silver re-adsorption prevention effect can be excellently maintained.

The silver thin film etchant composition of the present invention and the etching method and metal pattern forming method using the same can be used to etch the single film and the multilayer film simultaneously.

In addition, the silver thin film etching composition of the present invention can prevent overetching of the single film and the multilayer film, thereby reducing the side etch amount, thereby forming a fine pattern.

The above silver alloy may include an alloy form containing silver as a main component and other metals such as Nd, Cu, Pd, Nb, Ni, Mo, Ni, Cr, Mg, W, Pa, In, Zn, Sn, Al, and Ti; and may include silver nitrides, silicides, carbides, oxides, etc., but is not limited thereto.

The above transparent conductive film may include at least one 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).

The above multilayer film may include one formed of transparent conductive film/silver, transparent conductive film/silver alloy, transparent conductive film/silver/transparent conductive film, or transparent conductive film/silver alloy/transparent conductive film.

The silver thin film etchant composition of the present invention and the etching method using the same and the method for forming a metal pattern can be used for forming an OLED TFT array substrate for a reflective film, a trace wiring or nanowire wiring for a touch screen panel, and is not limited thereto, and can be used for electronic component materials including the single film and the multilayer film.

Below, the components included in the silver thin film etching composition of the present invention are described.

<Silver thin film etching solution composition>

The etchant composition of the present invention comprises (A) a silver etching accelerator, (B) an inorganic acid, and (C) a bisulfate, and may comprise (D) water as a solvent.

(A) Silver etching accelerator

The silver etching accelerator included in the silver thin film etching composition of the present invention serves as a main oxidizing agent and performs the function of wet etching by oxidizing the silver thin film and/or the transparent conductive film.

The silver etching accelerator of the present invention may include at least one selected from the group consisting of hydrogen peroxide and iron salts.

Examples of the iron salts include iron nitrate, ferric nitrate, iron sulfate, and ferric sulfate, with ferric nitrate being most preferred.

However, if the iron salt contains a chlorine compound (i.e., chlorine ion) such as FeCl ₃ , when etching a silver thin film with the thin film etchant composition of the present invention using it, a problem occurs in which silver precipitation occurs. Therefore, it is preferable that the iron salt in the present invention does not contain a chlorine compound such as FeCl ₃ .

The content of the above silver etching accelerator is included in an amount of 0.01 to 20 wt%, and preferably 1 to 5 wt%, based on the total weight of the composition. When the content of the silver etching accelerator is included within the above content range, the silver etching speed and the effect of preventing silver residue generation are excellent, and the etching balance for the silver thin film and the transparent conductive film is good during the etching of the multilayer film.

(B) Weapon acid

The inorganic acid included in the etchant composition of the present invention is a component used as an etching improver, and plays a role in wet etching by oxidizing a silver thin film and/or a transparent conductive film.

The above inorganic acid may more specifically include at least one selected from the group consisting of nitric acid and sulfuric acid, preferably at least two, and most preferably nitric acid and sulfuric acid.

The content of the above inorganic acid may be included in an amount of 0.1 to 20 wt%, and preferably 3 to 8 wt%, based on the total weight of the composition.

When the content of the inorganic acid is within the above content range, the etching speed and etching uniformity are excellent, so that a fine pattern can be formed.

(C) Bisulfate

The bisulfate included in the etchant composition of the present invention is a component used as a treatment water improvement agent, and plays a role in suppressing changes in etch characteristics due to an increase in Ag ⁺ ions during etching of a silver thin film.

The above bisulfate salt contains at least one cation selected from the group consisting of ammonium, potassium, and sodium, and examples thereof include potassium bisulfate, sodium bisulfate, and ammonium bisulfate.

The content of the above bisulfate may be included in an amount of 0.1 to 30 wt%, and preferably 3 to 8 wt%, based on the total weight of the composition. In the present invention, when the content of the bisulfate is within the above content range, the effect of chelating Ag ⁺ ions is excellent, and overetching due to an increase in the etching rate of a silver thin film can be prevented.

(D) Water

The water included in the silver thin film etching composition of the present invention may be deionized water for semiconductor processes, and preferably, deionized water having a density of 18 MΩ/cm or more may be used.

In the present invention, water may be included as a residual amount, and the residual amount means a residual amount such that the weight of the total composition including the essential components of the present invention and other components becomes 100% by weight.

For example, the present invention may be included in an amount of 30 to 99 weight % based on the total weight of the composition.

The silver thin film etching composition of the present invention is characterized in that it does not contain phosphoric acid that causes etching, and thus can exhibit excellent etching uniformity without damaging the underlying film when etching a single film made of silver (Ag) or a silver alloy and a multilayer film made of the single film and a transparent conductive film.

<Etching method using a thin film etchant composition>

In addition, the present invention provides an etching method using the silver thin film etching composition according to the present invention. The etching method of the present invention can form a pattern according to a known metal etching method, except that the silver thin film etching composition of the present invention is used.

For example, the etching method comprises: i) forming a single film made of silver or a silver alloy on a substrate, or a multilayer film composed of the single film and a transparent conductive film; ii) selectively leaving a photo-reactive material on the single film or the multilayer film; and iii) etching the single film or the multilayer film using a silver thin film etching composition according to the present invention.

< >Method for forming a metal pattern using a thin film etching composition

In addition, the present invention provides a method for forming a metal pattern using the silver thin film etching composition according to the present invention. The method for forming a metal pattern according to the present invention can form a pattern according to a known metal pattern forming method, except that the silver thin film etching composition according to the present invention is used.

For example, the method for forming the metal pattern includes: i) a step of forming a single film made of silver or a silver alloy, or a multilayer film composed of the single film and a transparent conductive film, on a substrate; and ii) a step of etching the single film or the multilayer film using a silver thin film etching composition according to the present invention.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to further explain the present invention, and the scope of the present invention is not limited by the following examples. The scope of the present invention is indicated in the claims, and furthermore, it includes all changes within the meaning and scope equivalent to the claims. In addition, "%" and "part" indicating the content in the following examples and comparative examples are based on mass unless specifically stated.

Examples and Comparative Examples: Preparation of a Silver Thin Film Etching Solution Composition

Silver thin film etching compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were prepared according to the compositions shown in Table 1 below, and the remaining amount of water was included to make 100 wt% (unit: wt%).

(A) Etch accelerator (B) Weapon Mountain (C) Bisulfate (D) Water ferric nitrate
(Ferric Nitrate) FeCl ₃ hydrogen peroxide nitric acid potassium bisulfate
(Potassium Bisufate) Example 1 2 5 5 Remaining amount Example 2 0.1 10 5 Remaining amount Example 3 5 1 2 Remaining amount Example 4 8 1 2 Remaining amount Example 5 2 7 5 Remaining amount Example 6 2 1 10 Remaining amount Example 7 10 5 5 Remaining amount Example 8 0.01 5 5 Remaining amount Example 9 2 5 0.01 Remaining amount Example 10 25 5 5 Remaining amount Example 11 2 30 5 Remaining amount Example 12 5 5 30 Remaining amount Comparative Example 1 5 5 Remaining amount Comparative Example 2 2 5 Remaining amount Comparative Example 3 2 5 Remaining amount Comparative Example 4 2 5 5 Remaining amount

Exam example

1. Processing Purchase Evaluation

The state immediately after the etchant compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were manufactured was referred to as a fresh solution, and the state in which 1000 ppm of silver powder was artificially dissolved (evaluated as the number of treatments) in the etchants of the Examples and Comparative Examples was assumed to have undergone an etching process for a long period of time was referred to as an old solution.

Side etch, silver residue, and silver resorption were evaluated using the following methods using each of the new and old solutions.

2. Side Etch Measurement

After forming an ITO (indium tin oxide)/silver/ITO triple film on a substrate, a photoresist was patterned on the triple film. The substrate was subjected to an etching process using a silver thin film etchant composition according to examples and comparative examples.

From the point in time when the etching of the transparent conductive film/silver/transparent conductive film triple layer in the area not covered by the photoresist was completed, an additional etch time of 100 seconds was advanced, and the distance from the edge of the patterned photoresist to the etched silver (Ag) film was measured using a scanning electron microscope (SEM; model name: SU-8010, HITACHI). The results are shown in Table 2.

[Based on the difference in lateral etching (i.e. skew difference)]

○: Good (Side Etch: Side etch ≤ 0.25㎛)

△: Normal (Side Etch: 0.25㎛ ＜ Side etch ≤ 0.50㎛)

Ⅹ: Defective (Side Etch: 0.50㎛ ≤ side Etch)

3. Silver residue measurement

The silver thin film etchant compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were each placed into a spray-type etching experiment device (model name: ETCHER (TFT), manufactured by SEMES), the temperature was set to 40°C, and the device was heated. When the temperature reached 40±0.1°C, the etching process of the specimens was performed. The total etching time was 85 seconds. The substrate was placed and spraying started, and when the etching time of 85 seconds was reached, it was taken out, washed with deionized water, dried using a hot air dryer, and the photoresist was removed using a photoresist stripper. After washing and drying, the residue, which is a phenomenon in which silver (Ag) remains unetched in areas not covered by the photoresist, was measured using a scanning electron microscope (SEM; model name: SU-8010, manufactured by HITACHI), and the results are shown in Table 2.

<Residue Measurement Evaluation Criteria>

Good: No residue

Defect: Residue generation

4. Silver resorption evaluation

The silver thin film etchant compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were each placed into a spray-type etching experiment device (model name: ETCHER (TFT), SEMES), the temperature was set to 40°C and increased, and when the temperature reached 40±0.1°C, the etching process of the specimens was performed. The total etching time was 85 seconds. The substrate was placed and spraying was started, and when the etching time of 85 seconds was reached, it was taken out, washed with deionized water, and dried using a hot air dryer. After washing and drying, the substrate was cut and the cross-section was measured using a scanning electron microscope (SEM; model name: SU-8010, manufactured by HITACHI). The number of silver particles adsorbed on the upper Ti of the Ti/Al/Ti triple film of the S/D portion exposed in the substrate due to the etching process was measured, and the results were evaluated according to the following criteria, and the results are shown in Table 2.

<Silver resorption evaluation criteria>

Good: less than 5

Normal: 5 or more but less than 50

Defective: 50 or more

New liquid Etching solution (after evaluation of treatment quantity) S/E (㎛) Ag residue Ag re-adsorption S/E (㎛) Ag residue Ag re-adsorption (Good/Bad) (Good/Average/Bad) (Good/Bad) (Good/Average/Bad) Example 1 ○ Good Good ○ Good Good Example 2 △ Good Good △ Good Good Example 3 △ Good Good △ Good Good Example 4 ○ Good Good ○ Good Good Example 5 ○ Good Good ○ Good Good Example 6 ○ Good Good ○ Good Good Example 7 ○ Good Good ○ Good Good Example 8 ○ Good Good ○ Good Good Example 9 ○ Good Good ○ Good Good Example 10 △ Good Good △ Good Good Example 11 △ Good Good △ Good Good Example 12 ○ Good Good △ Good Good Comparative Example 1 Ⅹ error error Ⅹ error error Comparative Example 2 ○ Good Good Ⅹ error error Comparative Example 3 Ⅹ error error Ⅹ error error Comparative Example 4 △ Good error △ Good error

As shown in the above table, the etchant compositions of Examples 1 to 12 not only had good/excellent side etch characteristics for both the new and old solutions, but also had excellent silver residue and silver re-adsorption effects, confirming excellent treatment capacity.

On the other hand, in Comparative Examples 1 to 3 that did not include some of the components included in the etchant composition of the present invention and Comparative Example 4 that used a compound containing chloride ions as a silver etching accelerator, it was confirmed that not only were the side etch, silver residue, and silver re-adsorption effects of the new etchant composition poor, but also the effect of the old etchant composition was poor.

Claims (12)

Regarding the total weight of the composition,
(A) 0.01 to 20 wt% of a silver etching accelerator;
(B) 0.1 to 20 wt% of an inorganic acid;
(C) 0.1 to 30 wt% of bisulfate; and
(D) A silver thin film etching composition containing a residual amount of water,
The above silver etching accelerator (A) comprises at least one selected from the group consisting of hydrogen peroxide and iron salts, wherein the iron salt does not contain a chlorine compound,
The above inorganic acid (B) includes at least one selected from the group consisting of sulfuric acid and nitric acid, and does not include phosphoric acid.
A silver thin film etching composition characterized in that the bisulfate (C) includes at least one selected from potassium bisulfate, sodium bisulfate, and ammonium bisulfate, and does not contain a peroxide. delete delete delete A silver thin film etching composition according to claim 1, wherein the iron salt comprises at least one selected from the group consisting of iron nitrate, ferric nitrate, iron sulfate, and ferric sulfate. delete delete In claim 1,
The above silver thin film etching composition is characterized in that it can simultaneously etch a single film made of silver or a silver alloy, or a multilayer film made of the single film and a transparent conductive film. In claim 8,
A silver thin film etching composition, characterized in that the transparent conductive film is at least one 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 claim 8,
A silver thin film etching composition including the multilayer film formed by transparent conductive film/silver, transparent conductive film/silver alloy, transparent conductive film/silver/transparent conductive film or transparent conductive film/silver alloy/transparent conductive film. A step of forming a single film made of silver or a silver alloy, or a multilayer film composed of the single film and a transparent conductive film, on a substrate;
A step of selectively leaving a photo-responsive material on the single film or the multilayer film; and
An etching method comprising a step of etching the single film or the multilayer film using the composition of claim 1. A step of forming a single film made of silver or a silver alloy, or a multilayer film composed of the single film and a transparent conductive film on a substrate; and
A method for forming a metal pattern, comprising the step of etching the single film or the multilayer film using the composition of claim 1.