TW201712155A - Etchant composition for metal layer, method for etching copper-based metal layer using the composition, method for fabricating array substrate for liquid crystal display device, and array for liquid crystal display device produced by the method Substrate - Google Patents

Abstract

The present disclosure relates to an etchant composition for a metal layer, a method for etching a copper-based metal layer using the composition, a method for fabricating an array substrate for a liquid crystal display device, and for using the fabrication An array substrate for a liquid crystal display device produced by the method, wherein the etchant composition for a metal layer comprises: (a) phosphoric acid; (b) nitric acid; (c) acetic acid; (d) a fluorine-containing compound; e) a sulfuric acid compound; and (f) water, wherein the (e) sulfuric acid compound has a pKa value of -1 to 5.

Description

Etchant composition for metal layer, method for etching copper-based metal layer using the composition, method for fabricating array substrate for liquid crystal display device, and array for liquid crystal display device produced by the method Substrate

FIELD OF THE INVENTION The present invention relates to an etchant composition for a metal layer, and a method for fabricating an array substrate for a liquid crystal display device using the etchant composition.

BACKGROUND OF THE INVENTION In a semiconductor device, a method of forming a metal line on a substrate is generally formed by forming a metal layer by sputtering or the like, forming a light in a selective region by photoresist coating, exposure, and development. The resist is etched, and etched, and includes a cleaning process before and after each unit process, and the like. This etching step refers to leaving a metal layer in a selective region using a photoresist as a mask, and generally uses dry etching by plasma or the like or wet etching using an etchant composition.

In such semiconductor devices, metal wire resistance has recently become a main concern. Since the resistance value is the main factor causing the RC time delay, and especially in the thin film transistor liquid crystal display (TFT-LCD), in terms of technological development, the increase in panel size and the achievement of high resolution are key factors, therefore, The RC time delay necessary for the increase in TFT-LCD is reduced, and the development of low-resistance materials is critical. Chromium (Cr, resistivity: 12.7 × 10 ^-8 Ωm), molybdenum (Mo, resistivity: 5 × 10 ^-8 Ωm), aluminum (Al, resistivity: 2.65 × 10 ^-8 Ωm) commonly used in the art ) and its alloys are difficult to use in the gate lines and data lines used in large TFT-LCDs.

In view of the above, interest in a copper-based metal layer (for example, a copper layer and a copper-titanium layer) as a new low-resistance metal layer and an etchant composition thereof has been increased, and Korean Patent Application Publication No. 10-2013-0046065 Etchant compositions for a plurality of metal layers are disclosed, including phosphoric acid, nitric acid, acetic acid, and fluorochemicals. However, the control of glass substrate etching which occurs when a fluorine-containing compound is present in an etchant composition having a low pH has limitations and has the following limitations: it cannot be in a thick layer having a thickness of 5000 Å or more. Improve problems with contours and glass etching. [Prior Art Document] [Patent Literature]

(Patent Document 1) Korean Patent Application Publication No. 10-2013-0046065.

SUMMARY OF THE INVENTION The present invention is directed to an etchant composition for a metal layer which has excellent etching properties in terms of a thick layer having a copper layer thickness of 5000 Å or more to improve problems with respect to profile and glass etching.

The present invention also aims to provide a method for etching a copper-based metal layer using an etchant composition, and a method for fabricating an array substrate for a liquid crystal display device.

An aspect of the invention provides an etchant composition for a metal layer comprising: (a) phosphoric acid; (b) nitric acid; (c) acetic acid; (d) a fluorine-containing compound; (e) a sulfuric acid compound; Water, wherein the (e) sulfuric acid compound has a pKa value of -1 to 5.

Another aspect of the present invention provides a method for etching a copper-based metal layer using an etchant composition, and a method for fabricating an array substrate for a liquid crystal display device.

Yet another aspect of the present invention provides an array substrate for a liquid crystal display fabricated using the fabrication method of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present disclosure will be described in more detail.

The present disclosure relates to an etchant composition for a metal layer comprising: (a) phosphoric acid; (b) nitric acid; (c) acetic acid; (d) a fluorine-containing compound; (e) a sulfuric acid compound; and (f) water Wherein the (e) sulfuric acid compound has a pKa value of -1 to 5. In particular, it relates to an etchant composition for etching a thick layer having a copper-based metal layer thickness of 5000 Å or more, a method for etching the layer, and an array substrate for a liquid crystal display device And a method for fabricating an array substrate of a liquid crystal display device.

The inventors of the present disclosure have experimentally verified the following and completed the disclosure by adjusting the pKa by using a sulfuric acid compound such that the etching rate of the glass substrate under the metal layer caused by the fluorine-containing compound is lowered. The etchant composition of the present disclosure has excellent etching performance in terms of a thick layer having a copper layer thickness of 5000 Å or more in terms of problems with contour and glass etching.

The present disclosure is preferably used to etch a copper-based metal layer. The copper-based metal layer includes copper as one of the layer compositions, including a single layer and a plurality of layers (for example, a double layer), and is a thick layer having a copper layer thickness of 5000 Å or more. For example, a single layer including copper or a copper alloy, a titanium or titanium alloy layer, and a copper-titanium layer, a copper-titanium alloy layer or the like as a multilayer. The copper-titanium layer refers to a layer including a titanium layer and a copper layer formed on the titanium layer, and the copper-titanium alloy layer refers to a layer including a titanium alloy layer and a copper layer formed on the titanium alloy layer. Further, the titanium alloy layer refers to an alloy of titanium and one or more selected from the group consisting of, for example, molybdenum (Mo), tantalum (Ta), chromium (Cr), nickel (Ni), niobium (Nd), and the like.

The etchant composition of the present disclosure is an etchant composition for a copper-based metal layer capable of etching a gate, a gate line, and a source/drain and a data line together, and includes (a) phosphoric acid; (b) nitric acid (c) acetic acid; (d) a fluorine-containing compound; (e) a sulfuric acid compound; and (f) water.

The (e) sulfuric acid compound included in the etchant composition of the present disclosure enables the glass etching rate to be adjusted by adjusting the pKa.

Hereinafter, the present disclosure will be described in detail by the respective components. (a) Phosphoric acid

(a) Phosphoric acid (H ₃ PO ₄ ) included in the etchant of the present disclosure is a component used as a main oxidizing agent and functions to oxidize and wet-etch a metal layer.

The content of (a) phosphoric acid is from 10% by weight to 50% by weight, and preferably from 10% by weight to 30% by weight, based on the total weight of the etchant composition. A phosphoric acid content smaller than the above range may cause a decrease in the etching rate of copper and a defect caused by the residue; and a phosphoric acid content larger than the above range is disadvantageous in that the etching rate of the titanium layer is lowered and the etching rate of the copper layer is excessive. The increase causes residue in the titanium layer and over-etching in the copper layer, which causes problems in subsequent processing. (b) Nitric acid

Nitric acid (HNO ₃ ) included in the etchant of the present disclosure is used as a component of the auxiliary oxidizing agent and functions to oxidize and wet etch the metal layer.

The content of nitric acid is from 3% by weight to 8% by weight with respect to the total weight of the etchant composition. When the content of the nitric acid is less than 3% by weight, the etching rate of the metal layer is lowered, so that the etching uniformity in the substrate is deteriorated, causing enthalpy; and when the content is more than 8% by weight, the etching rate of the metal layer is increased, causing Over-etched. (c) acetic acid

Acetic acid (CH ₃ COOH) included in the etchant of the present disclosure is a component used as an auxiliary oxidizing agent, and functions to adjust the decomposition rate of nitric acid and to serve as a buffer for adjusting the reaction rate, etc., and usually To reduce the rate of decomposition.

The content of acetic acid is from 10% by weight to 60% by weight based on the total weight of the etchant composition. When the content of acetic acid is less than 10% by weight, there is a problem of bismuth due to uneven etching rate in the substrate; and a content of more than 60% by weight causes foam generation, and when foam is present in the substrate, complete etching cannot be achieved, which may be Causes problems in subsequent processing. (d) fluorochemicals

The fluorine-containing compound included in the etchant composition of the present disclosure means a compound capable of being dissociated in water and generating fluorine ions. The fluorine-containing compound functions to remove residues which are inevitably produced in the titanium and titanium alloy layers.

The fluorine-containing compound is not particularly limited as long as it is a material used in the art and can be dissociated into a fluoride ion or a polyvalent fluoride ion in a solution. However, the fluorine-containing compound is preferably selected from the group consisting of ammonium fluoride (NH ₄ F), sodium fluoride (NaF), potassium fluoride (KF), ammonium hydrogen fluoride (NH ₄ F∙HF), and sodium hydrogen fluoride (NaF). One, two or more types of the group consisting of ∙HF) and potassium fluorohydride (KF∙HF).

The fluorine-containing compound is included in an amount of 0.01% by weight to 2.0% by weight, and preferably 0.05% by weight to 1.0% by weight, based on the total weight of the etchant composition. When the fluorine-containing compound is included in a range smaller than the above range, the etching rate of the titanium and titanium alloy layers is lowered, resulting in generation of an etching residue. When the fluorine-containing compound is included in a range larger than the above range, there is a problem that the etching rate of the glass substrate increases. (e) Sulfuric acid compounds

The sulfuric acid compound included in the etchant composition of the present disclosure can adjust the pKa value according to the functional group of the compound, and the sulfuric acid compound having a pKa value serves to improve the metal by reducing the fluorine ion activity in the etchant The effect of the problem caused by glass etching under the layer. In order to function this, the sulfuric acid compound of the present disclosure may have a pKa value of -1 to 5.

Specifically, the sulfuric acid compound having a pKa value of -1 to 5 in the present disclosure may be a compound having the following structural formula: <Chemical Formula 1> 2-naphthalenesulfonic acid <Chemical Formula 2> Aminesulfonic acid <Chemical Formula 3> Sulfamic acid <Chemical Formula 4> 3-aminobenzenesulfonic acid <Chemical Formula 5> 4-hydroxybenzenesulfonic acid

A sulfuric acid compound having a pKa value of less than -1 is not effective in reducing the glass etching rate; and when the pKa value is more than 5, the etchant activity is lowered, which may have a negative effect on the etching rate for the metal layer.

The sulfuric acid compound is included in an amount of 0.01% by weight to 10.0% by weight and preferably 0.1% by weight to 5.0% by weight based on the total weight of the composition. When the sulfuric acid compound is contained in a range smaller than the above range, it is not effective in reducing the glass etching rate; and even when the sulfuric acid compound is included in a range larger than the above range, no further improvement effect can be obtained. (f) water

The water included in the etchant composition for the copper-titanium alloy layer of the present disclosure is included in the balance such that the total weight of the composition becomes 100% by weight. Here, when the water content is 30% by weight or more based on the total weight, the oxidizing ability of the etchant is remarkably lowered to cause etching defects. There is no particular limitation on water, however, it is preferred to use deionized water. As the water, it is advantageous to use deionized water having a water resistivity value (which represents a value of the degree of ion removal in water) of 18 MΩ/cm or more.

The phosphoric acid, nitric acid, acetic acid, fluorine-containing compound, sulfuric acid compound, water, and the like used in the present disclosure can be prepared by a method known in the art, and the etchant composition of the present disclosure preferably has a semiconductor processing. purity.

Further, the present disclosure relates to a method for etching a copper-based metal layer, comprising: I) forming a copper-based metal layer on a substrate; II) selectively leaving a photo-reactive material on the copper-based metal layer; and III The copper-based metal layer is etched using the etchant composition of the present disclosure.

In the etching method of the present disclosure, the photoreactive material is preferably a general photoresist material, and can be selectively left by using ordinary exposure and development processing.

Further, the present disclosure provides a method for fabricating an array substrate for a liquid crystal display device, comprising: a) forming a gate on a substrate; b) forming a gate insulating layer on a substrate including a gate; c) Forming a semiconductor layer on the pole insulating layer; d) forming a source/drain on the semiconductor layer; and e) forming a pixel electrode connected to the drain, wherein step a) includes forming a copper-based metal layer on the substrate and using the present The disclosed etchant composition etches a copper-based metal layer to form a gate line, and step d) includes forming a copper-based metal layer on the semiconductor layer and forming the copper-based metal layer by etching the etchant composition of the present disclosure Source and bungee.

The array substrate used for the liquid crystal display device may be a thin film transistor (TFT) array substrate.

Further, the present disclosure relates to an array substrate for a liquid crystal display device produced by the above-described fabrication method.

Array substrates for liquid crystal display devices can include gate lines and/or source and drain electrodes etched using the etchant compositions of the present disclosure.

Hereinafter, the present disclosure will be described in more detail with reference to the embodiments. However, the following examples are intended to more specifically describe the present disclosure, and the scope of the present disclosure is not limited to the following embodiments. The following embodiments can be modified and modified as appropriate by those skilled in the art within the scope of the present disclosure. <Verification of Excellent Etching Performance of Composition of the Present Disclosure> Example 1 and Example 2 and Comparative Example 1 to Comparative Example 9 : Preparation of Etchant Composition

The etchant compositions of the examples and comparative examples were prepared at 180 kg each according to the constituents (unit: % by weight) listed in Table 1 below. 【Table 1】 Test Example 1. Evaluation of performance of etching composition

After depositing a titanium alloy layer on a glass substrate (100 mm × 100 mm) and depositing a copper layer on the titanium alloy layer, a photoresist having a specific pattern is formed on the substrate by photolithography processing, and then used Each of the compositions of Example 1 and Example 2 and Comparative Example 1 to Comparative Example 9 was subjected to an etching process on the copper-based metal layer. The temperature of the etching composition was set at about 40 ° C during the etching using a spray type etching test apparatus (model name: ETCHER (TFT), manufactured by SEMES Co., Ltd.), however, according to other processing conditions and others The factors are changed to the appropriate temperature as needed. The etching time may vary depending on the etching temperature, however, the etching is usually performed for 50 seconds (s) to 180 seconds. The profile of the copper-based metal layer etched in the above etching process was examined using a cross-sectional SEM (manufactured by HITACHI, Ltd., model name: S-4700), and the results are listed in Table 2. <etching evaluation standard> Cu etching rate: O (200 Å/sec to 300Å/s), △ (less than 200Å/s, more than 300Å/s), X (unetched) Ti etching rate: O (10Å/s or more) , △ (less than 10Å/s), X (unetched) Cu etching uniformity: O (excellent), △ (general), X (poor) Glass etching rate: O (10Å/s or less), X (greater than 10Å/ s)

When the copper layer is not etched, the underlying Ti and glass etch rates and uniformity cannot be measured. 【Table 2】

As shown in Table 2, the etchant compositions of Example 1 and Example 2 exhibited excellent etching performance in terms of a thick layer having a copper layer thickness of 5000 Å or more in terms of improvement in profile and glass etching.

Meanwhile, in Comparative Example 1 to Comparative Example 9, the etching uniformity of the etching profile was poor and flaws occurred, and problems due to glass etching also occurred. <Evaluation of etching performance of etchant composition depending on pKa of sulfuric acid compound> Example 3 and Example 4 and Comparative Example 10 to Comparative Example 14 : Preparation of etchant composition

The etchant compositions of the examples and comparative examples were prepared in accordance with the constituents (unit: % by weight) listed in Table 3 below, respectively, and the pKa of each composition was listed. 【table 3】 Test Example 2. Evaluation of performance of etchant composition

The properties of the etchant compositions of the examples and the comparative examples were evaluated in the same manner as in Test Example 1, and the results are shown in Table 4. 【Table 4】

As shown in Table 4, the etchant compositions of Example 3 and Example 4 using a sulfuric acid compound having a pKa range of -1 to 5 were improved in the thick layer having a copper layer thickness of 5000 Å or more. The problem of glass etching shows excellent etching performance.

Meanwhile, in Comparative Examples 11 to 14 in which a sulfuric acid compound having a pKa range of -1 to 5 was used, the copper etching rate was insufficient in terms of etching profile, or problems due to glass etching occurred.

From the test results, it was verified that the etchant composition of the present disclosure has excellent etching properties by using a sulfuric acid compound having a pKa ranging from -1 to 5.

The etchant composition of the present disclosure has excellent etching performance in terms of a thick layer having a copper layer thickness of 5000 Å or more in terms of problems with contour and glass etching.

Claims (10)

An etchant composition for a metal layer, comprising: (a) phosphoric acid; (b) nitric acid; (c) acetic acid; (d) a fluorine-containing compound; (e) a sulfuric acid compound; and (f) water, wherein The (e) sulfuric acid compound has a pKa value of -1 to 5. An etchant composition for a metal layer according to claim 1, wherein the (e) sulfuric acid compound is one or more of the following compounds: <Chemical Formula 1> 2-naphthalenesulfonic acid <Chemical Formula 2> Aminesulfonic acid <Chemical Formula 3> Sulfamic acid <Chemical Formula 4> 3-aminobenzenesulfonic acid <Chemical Formula 5> 4-hydroxybenzenesulfonic acid. An etchant composition for a metal layer according to claim 1, wherein the (d) fluorine-containing compound is ammonium fluoride, sodium fluoride, potassium fluoride, ammonium hydrogen fluoride, sodium hydrogen fluoride, and potassium hydrogen fluoride. One or more. The etchant composition for a metal layer according to claim 1, comprising: (a) the phosphoric acid is 10% by weight to 50% by weight based on the total weight of the etchant composition; (b) the nitric acid 3% by weight to 8% by weight; (c) the acetic acid is 10% by weight to 60% by weight; (d) the fluorine-containing compound is 0.01% by weight to 2.0% by weight; (e) the sulfuric acid compound is 0.01% by weight to 10.0% by weight; and the balance of (f) water. An etchant composition for a metal layer according to claim 1, wherein the metal layer is a single-layer copper-based metal layer including copper or a copper alloy; or a group selected from the group consisting of a copper-titanium layer and a copper-titanium alloy layer. A layer of one or more layers in the middle. An etchant composition for a metal layer according to claim 1, wherein the metal layer is a copper-based metal layer having a thickness of 5000 Å or more. A method for etching a copper-based metal layer, comprising: I) forming a copper-based metal layer on a substrate; II) selectively leaving a photoreactive material on the copper-based metal layer; and III) using as requested The etchant composition for a metal layer of any one of items 1 to 6 etches the copper-based metal layer. A method for fabricating an array substrate for a liquid crystal display device, comprising: a) forming a gate on a substrate; b) forming a gate insulating layer on a substrate including the gate; c) at the gate Forming a semiconductor layer on the insulating layer; d) forming a source/drain on the semiconductor layer; and e) forming a pixel electrode connected to the drain; wherein the step a) includes forming a copper-based metal on the substrate And forming a gate line by etching the copper-based metal layer using an etchant composition for a metal layer according to any one of claims 1 to 6; and the step d) includes forming copper on the semiconductor layer The base metal layer and the source and drain are formed by etching the copper-based metal layer using the etchant composition for the metal layer. A method for fabricating an array substrate for a liquid crystal display device according to claim 8, wherein the array substrate for the liquid crystal display device is a thin film transistor array substrate. An array substrate for a liquid crystal display device, which is fabricated using the fabrication method of claim 8.