KR100883960B1 - Etchants of Copper or Copper Alloy Films - Google Patents

Abstract

The present invention relates to an etchant for two or more multilayers of copper or copper alloys / other metals or metal oxides, wherein 15 to 40% by weight of hydrogen peroxide, 1 to 20% by weight of one or more organic acids selected from the group consisting of carboxylic acids and amino acids, sulfates or A copper or copper alloy film consisting of 1 to 5% by weight of a fluorine salt, 0.01 to 3% by weight of a chelating agent, 0.0001 to 1% by weight of a fluorine-based surfactant, and a residual amount of water, and a double layer of other metal films or three or more multilayers in which these are alternately stacked. An etchant capable of etching at the same time is provided.

The etching agent according to the present invention can prevent process defects due to peeling and residue of the copper film by collectively etching the gate and the source / drain wiring. In addition, the etching speed can be freely controlled according to the temperature and process condition variables, and the taper and pattern can be straightened, the residue is removed, and the etching liquid life is excellent. have.

Description

Etch for layers of copper or copper alloy

The present invention relates to a Cu etchant, more particularly, an etchant of two or more multilayers of copper or copper alloys / other metals or metal oxides.

The process of forming a metal wiring on a substrate used for flat panel displays such as LCD, PDP and OLED is typically made of a metal film forming process by sputtering, a photoresist coating, an exposure and development process, an etching process and a cleaning process. . Particularly in the case of TFT-LCD, a single layer made of copper or a copper alloy, and further, two layers of copper or a copper alloy / other metal or a metal oxide, in order to reduce the wiring resistance and increase adhesion with a silicon insulating film while being large screened. Employment of the above multilayer film is widely examined. For example, the copper / molybdenum film and the copper / titanium film can form source / drain wirings constituting the gate wiring and the data line of the TFT-LCD, thereby contributing to the large screen of the display. Therefore, there is a demand for the development of an etchant which can simultaneously remove these multiple films and leaves no etching solution and metal residue on the substrate after washing.

Korean Patent Laid-Open Publication Nos. 2003-0084397 and 2004-0051502 disclose etching agents for copper / molybdenum films containing hydrogen peroxide, organic acids, phosphates, sulfates, nitrogen ring compounds and other nitrogen compounds. In addition, Korean Patent Publication No. 10-2006-0064481 (Patent Registration No. 708970) discloses 4-40 parts by weight of hydrogen peroxide + 0.1-10 parts by weight of organic acid + 0.1-10 parts by weight of triazole or tetrazole + 0.1-10 parts by weight of amino compound. An etchant using a minor + small amount of fluoride is disclosed. However, the above etchant did not satisfy the high requirements in terms of CD loss, taper, pattern straightness, and metal residue for the copper alloy.

The present invention is to provide a copper or copper alloy film etchant having good etching profile characteristics.

In particular, the present invention provides a copper or copper alloy film etchant having a taper of less than 60 degrees, a CD loss of 1 μm or less, a pattern linearity having good profile characteristics, and a long lifetime without damaging the glass plate as a substrate. It is for.

In addition, the present invention is to provide an etchant for simultaneously etching two or more multilayer films made of a copper or copper alloy film and another metal film.

According to the present invention, hydrogen peroxide 15-40w%, at least one organic acid selected from the group consisting of carboxylic acid and amino acid, 1-20w%, sulfate or fluorine salt 1-5w%, chelating agent 0.01-3w%, fluorine-based surfactant 0.0001 ~ There is provided a copper or copper alloy film etchant consisting of 1w% and the balance of water. The etchant may simultaneously etch a double film made of a copper or copper alloy film and another metal film or three or more multilayer films in which they are alternately stacked. The other metal is preferably titanium, molybdenum or alloys thereof. The hydrogen peroxide is preferably used in an amount of 20-25 w%.

The carboxylic acid preferably has 1 to 3 carboxyl groups having 1 to 12 carbon atoms, for example, acetic acid (C ₂ H ₄ O ₂ ), oxalic acid (C ₂ H ₂ O ₄ ), glycolic acid (C ₂ H ₄ O ₃ ), glutamic acid (C ₅ H ₉ NO ₄ ), butanoic acid (C ₄ H ₈ O ₂ ), malonic acid (C ₃ H ₄ O ₄ ), gluconic acid (C ₆ H ₁₂ O ₇ ) or succinic acid (C ₄ H ₆ O ₄ ). In addition, the amino acid is preferably an amino acid having 1 to 12 carbon atoms, for example, glutamine, glycine, isoleucine proline, tyrosine or arginine. The content of the organic acid is preferably used in the range of pH 0.5 to 5.5 within 1 to 5 w%. It helps to prevent self-decomposition of hydrogen peroxide, and provides an environment where copper, molybdenum and laminated films can be etched simultaneously. The main role of organic acids is to act as a buffer for metal ions and as a buffer against acidity changes.

Double salts such as sulphate or fluoride salts are advantageous for the formation of smooth profiles rather than affecting the etching power and are effective within the range not exceeding 3.0 w%, and are preferably used in an amount of 1 to 2 w%. . The double salt can control the etching rate of the molybdenum film, titanium film and serves to increase the margin in the process. As a double salt such as sulfate or fluorine salt, for example, KF, NaF, CaF, KHSO₄, KAl (SO ₄ ) ₂ , 2KHSO ₄ , K ₂ SO _4, etc. are used, It also functions as a residual metal chelating agent. If the double salt does not enter the proper content, it is not possible to control the etching rate and obtain the desired profile, which may be a cause of defects in the process.

The chelating agent is preferably used in an amount of 0.01 to 0.05 w%, for example, nitrilotriacetic acid ("NTA"), ethylenediaminetetraacetic acid ("EDTA"), diethylenetriaminepentaacetic acid ("DTPA" "), Aminotri (methylenephosphonic acid) (" ATMP "), 1-hydroxyethane (1,1-diylbisproponic acid) (" HEDP "), ethylenediaminetetra (methyleneproponic acid) (" EDTMP ") , Diethylenetriamine penta (methylenephosphonic acid) ("DTPMP") and the like are used. Cu is easily dissolved due to its properties of impurities easily attached to it, but if left as a metal that is easy to reattach, Cu is likely to remain a major factor that can cause defects in subsequent processes. In order to solve this problem, a chelating agent is added as the metal ion blocking agent in addition to the organic acid and the double salt.

Fluorine-based surfactants adsorb on the surface of the glass to quickly release the metal ions generated and prevent reattachment of the metal ions. It also significantly improves the cleaning efficiency. Fluorine-based surfactants include, for example, R _f CH ₂ CH ₂ SCH ₂ CH ₂ CO ₂ Li, (R _f CH ₂ CH ₂ O) P (O) (ONH ₄ ) ₂ , (R _f CH ₂ CH ₂ O) ₂ P (O) (ONH ₄ ), R _f CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H, R _f CH ₂ CH ₂ SO ₃ X, R _f CH ₂ CH ₂ NHSO ₃ X or mixtures thereof (Wherein y is an integer of 8 to 15, X is H or NH ₄ , R _f is F (CF ₂ CF ₂ ) _z , and z is an integer of 3 to 8). The surfactant is preferably used in an amount of 0.005 to 1 wt%, most preferably in an amount of 0.05 to 0.1 w%. If the surfactant is 1% by weight or more, a lot of bubbles are generated and the efficiency is lowered. When the molybdenum film is etched, a small particle form residue is generated due to the characteristics of the molybdenum film. This phenomenon becomes an important defect factor that causes an electrical short or decreases the luminance later (see FIG. 9). Thus, in the molybdenum film etching, the fluorine-based surfactant serves to remove the residue. In addition, the fluorine-based surfactant plays an essential role in the etching of Ti. The 300 Å thick Ti film is etched within 30 sec at room temperature (25 ° C). In view of this, fluorine-based surfactants are a major factor in removing molybdenum (Mo) residue on the substrate and etching of Ti.

Referring to the case where the etchant of the present invention is applied to a Cu / Mo double layer, Mo, Cu is deposited on a glass substrate as shown in FIG. 1, and then a photoresist is coated as shown in FIG. After the pattern is formed by photolithography as shown in FIG. 3 and the etching process as shown in FIG. 4 is removed, the photoresist is removed as shown in FIG.

The etching agent according to the present invention can prevent process defects due to peeling and residue of the copper film by collectively etching the gate and the source / drain wiring using hydrogen peroxide, organic acid series, double salt, and fluorine-based surfactants. In addition, the etching speed can be freely controlled according to the temperature and process condition variables, and the taper and pattern can be straightened, the residue is removed, and the etching liquid life is excellent. have.

Hereinafter, the present invention will be described in detail with reference to the following examples.

Example 1

The board | substrate used for this invention is a glass plate which coated 300 micrometers of molybdenum on non-alkali glass, and 2000 micrometers of copper film on it. The photoresist process to confirm the performance of the etchant is shown in the following table. Here, PR is an abbreviation of photoresist and novolak is a photoresist in which a portion exposed to the novolak photoresist melts during the development process. EOP is an abbreviation of End Of Point and the pattern is formed when it is exposed to the edge during exposure. S / B is an abbreviation of Soft baked. It is a baking process to volatilize the solvent after coating the photoresist, and H / B is a hard bake. As a medical term, it is a baking process for preservation and curing of patterns after development.

PR RPM EOP S / B H / B Develop Novolak 1500 rpm / 10sec 5.6mJ / sec 110 ℃ / 120sec 110 ℃ / 120sec TMAH2.38w% / 60sec

For the variety and practicality of the test, the test substrate was cut to 10 * 10mm size and tested. The above-described PR coating process and etching process are shown in FIGS. 1 to 5. The equipment used in this example is a large etchant designed for copper etching, capable of processing up to 5th generation glass substrate, and can store up to 200 liters of solution in acid resistant (Teflon) material suitable for use in strong acids. The tank is at the bottom and uses a magnetic pump (100 liters / min) designed for self-suction. In addition, the spray was evenly distributed through a horizontal spray nozzle composed of a full con type.

The device consists of a glass substrate inlet, etching zone, rinse zone, and drying zone. By using transparent PVC, the etching process can be visually checked, and the problem that may occur during the process and the etching process can be visually monitored. . The rinse zone adopts a drain method to minimize glass contamination by cleaning, and the control unit can automatically and manually adjust using a touch panel. It is designed to control heating and cooling automatically to prevent temperature rise.

The etching solution for testing the specimen is 22% hydrogen peroxide, 3w% gluconic acid, 1w% double salt (KF), 0.01w% chelating agent (NTA), fluorine-based surfactant Novec 4300 (trade name 3M) 0.05 as in Example 1 of Table 1 w%, the rest is deionized water. The combination order was combined in the same order as above. Since copper itself is strongly attached to impurities, the test was performed by filtering with a 0.1um filter. The test capacity is 25 liters on average and may be less or more than this.

Next, photographs taken as a criterion for evaluation of physical properties are shown in FIGS. 6 to 9 as a result of precise photographing using FE-SEM. The specimen used at this time is a glass substrate that has been gated in the manufacture of a TFT circuit of a liquid crystal display device. 300 Å and Cu 2000 Å were formed, PR was applied, dried, and then exposed and developed to complete the pattern formation. Profiles are evaluated with reference to the following criteria. The measurement of the CD loss and taper was measured by 3,000 ~ 40,000 magnification of the cross section of the specimen without peeling the PR. The straightness of the pattern and the residue were measured in the same manner as above after removing the PR with KOH 4w% solution.

Example 2

Proceed in the same manner as in Example 1, and the dosage and physical property test results are shown in Table 1.

Table 1.

division Composition (parts by weight) H2O2 / Organic acid (gluconic acid) / KF / NTA / Novec 4300 Properties CD Ross Taper Pattern straightness Residue Example One 22/3/1 / 0.01 / 0.05 ◎ O ◎ ◎ 2 22/3/1 / 0.05 / 0.05 O ◎ △ △ 3 23/4 / 1.5 / 0.03 / 0.1 O ◎ ◎ ◎ 4 23/4 / 1.5 / 0.05 / 0.07 O O ◎ O 5 25/5 / 1.5 / 0.05 / 0.05 O △ ◎ O 6 25/3 / 1.8 / 0.01 / 0.05 ◎ ◎ O O 7 25/3 / 1.8 / 0.05 / 0.1 ◎ △ △ ◎ 8 23/2/2 / 0.05 / 0.1 △ ◎ △ ◎ 9 20/2 / 1.5 / 0.05 / 0.07 O O △ O 10 20/2/1 / 0.05 / 0.07 O △ O ◎

CD Ross [◎: Within 1um O: Within 1 ~ 1.2um △: Within 1.2 ~ 1.5um x: Over 1.5um]

Taper [◎: 40 to 50 degrees O: 50 to 60 degrees △: 60 to 70 degrees x: 70 degrees or more]

Pattern Straightness & Residue [◎: Very good O: Good △: Normal x: Poor]

Examples 11-20

Except for using glycine as an amino acid instead of gluconic acid proceed in the same manner as in Example 1 and the dosage and physical properties test results are shown in Table 2.

Table 2.

division Composition (parts by weight) H2O2 / Amino acid (glycine) / KF / NTA / Novec 4300 Properties CD Ross Taper Pattern straightness Residue Example 11 24/1/1 / 0.02 / 0.05 ◎ ◎ ◎ O 12 24/2/1 / 0.05 / 0.05 O ◎ ◎ △ 13 25/2 / 1.5 / 0.03 / 0.1 O ◎ △ ◎ 14 25/2 / 1.7 / 0.05 / 0.07 O ◎ ◎ O 15 23/2/1 / 0.03 / 0.05 O ◎ △ O 16 23/2 / 1.5 / 0.05 / 0.05 ◎ O △ O 17 25/3 / 1.8 / 0.02 / 0.1 ◎ △ O ◎ 18 22/1 / 1.5 / 0.05 / 0.1 △ ◎ △ ◎ 19 20/2 / 1.5 / 0.03 / 0.07 ◎ O ◎ O 20 20 / 1.5 / 1 / 0.03 / 0.07 O O O ◎

CD Ross [◎: Within 1um, 0: Within 1 ~ 1.2um △: Within 1.2 ~ 1.5um x: Above 1.5um]

Taper [◎: 40 to 50 degrees 0: 50 to 60 degrees △: 60 to 70 degrees x: 70 degrees or more]

Pattern straightness and residue [◎: Very good 0: Good △: Normal x: Poor]

1 is a specimen used in the present invention, Mo deposition, Cu deposition on a glass substrate.

Figure 2 is a form coated with PR on the specimen.

Figure 3: The photolithography process is completed on the specimen

4 is a form after an etching process with an etchant according to the present invention.

Fig. 5: Form after peeling off the photoresist after etching according to the present invention.

6 is a photograph showing the straightness of the pattern according to the present invention.

7 is an enlarged photograph showing confirmation of straightness and no residue on the substrate.

8 is a photograph showing a profile without peeling off the photoresist after pattern formation. It shows the superiority of cd loss and taper.

9 is a photograph showing that Mo residues remain upon etching with an etchant according to the prior art.

Explanation of the Main References

10; Glass substrate 11; Mo deposited film 12; Cu deposited film 13; Photoresist

Claims (9)

15 to 40% by weight of hydrogen peroxide, 1 to 20% by weight of one or more organic acids selected from the group consisting of carboxylic acids and amino acids, 1 to 5% by weight of sulfates or fluorides, 0.01 to 3% by weight of chelating agents, 0.0001 to 1% by weight of fluorine-based surfactants Copper or copper alloy film etchant consisting of. The etchant according to claim 1, wherein the etchant is capable of simultaneously etching a double film made of a copper or copper alloy film and another metal film, or three or more multilayer films in which they are alternately stacked. The etchant of claim 2, wherein the other metal is preferably titanium, molybdenum or an alloy thereof. According to claim 3, wherein the hydrogen peroxide 20-25w%, the organic acid 1-5w%, the sulfate or fluorine salt 1-2%, the chelating agent 0.01 ~ 0.05w%, the fluorine-based surfactant 0.05 ~ 0.1w% The etchant which consists of residual amount of ionized water. The method of claim 4, wherein the carboxylic acid is acetic acid (C ₂ H ₄ O ₂ ), oxalic acid (C ₂ H ₂ O ₄ ), glycolic acid (C ₂ H ₄ O ₃ ), glutamic acid (C ₅ H ₉ NO ₄ ), Etchants that are butanoic acid (C ₄ H ₈ O ₂ ), malonic acid (C ₃ H ₄ O ₄ ), gluconic acid (C ₆ H ₁₂ O ₇ ) or succinic acid (C ₄ H ₆ O ₄ ) The etchant of claim 4, wherein the amino acid is glutamic acid, glutamine, glycine, isoleucine proline, tyrosine or arginine. The etchant according to claim 4, wherein the sulfate is KHSO ₄ , KAl (SO ₄ ) ₂ , 2KHSO ₄ or K ₂ SO ₄ and the fluorine salt is KF, NaF or CaF. The etchant of claim 4, wherein the chelating agent is NTA, EDTA, DTPA, ATMP, HEDP, EDTMP, or DTPMP. The method of claim 4, wherein the fluorine-based surfactant is R _f CH ₂ CH ₂ SCH ₂ CH ₂ CO ₂ Li, (R _f CH ₂ CH ₂ O) P (O) (ONH ₄ ) ₂ , (R _f CH ₂ CH ₂ O) ₂ P (O) (ONH ₄ ), R _f CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H, R _f CH ₂ CH ₂ SO ₃ X, R _f CH ₂ CH ₂ NHSO ₃ X Or a mixture thereof (wherein y is an integer from 8 to 15, X is H or NH ₄ , R _f is F (CF ₂ CF ₂ ) _z and again z is an integer from 3 to 8). My

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