KR100983060B1 - Etchants for Non-Hydrogen Peroxide Copper or Copper Alloy Films - Google Patents

Abstract

The present invention provides potassium persulfate (K ₂ O ₈ S ₂ ), sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), calcium perchlorate (Ca (ClO ₄ ) ₂ ), potassium peroxide (K ₂ O ₂ ), peroxide Sodium (Na ₂ O ₂ ), calcium peroxide (CaO ₂ ), ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), perchloric acid (HClO ₄ ), potassium permanganate ( 3-20 wt% peroxide selected from the group consisting of KMnO ₄ ), sodium permanganate (NaMnO ₄ ), potassium dichromate (K ₂ Cr ₂ O ₇ ), sodium dichromate (Na ₂ Cr ₂ O ₇ ), and mixtures thereof; Amino acid 1-15%; 0.01 to 1 wt% chelating agent; 0.01-5% by weight of an oxidative stabilizer; 0.1-5% by weight of lower alkanesulfonic acid having 1 to 6 carbon atoms; 0.001 to 0.5 wt% of a surfactant; and a copper or copper alloy film etchant comprising a residual amount of water.

By etching the copper and copper alloy films using the etchant according to the present invention, it is possible to obtain wirings in which the adhesion to the bottom of the multilayer film is maintained, has a good profile, and the copper layer is not corroded. In addition, as compared to the hydrogen peroxide type etching agent, the safety and life time is excellent, thereby increasing productivity and improving the process.

Etchants, Copper, Molybdenum, Titanium

Description

Etcher without hydrogen peroxide 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 alloy / other metals, other metal alloys or metal oxides containing other peroxides instead of hydrogen peroxide.

Flat panel displays such as LCDs, PDPs and OLEDs, in particular TFT-LCDs, are large screens, in order to reduce wiring resistance and increase adhesion with a silicon insulating film, or even a single film of copper or copper alloy, or even copper or copper Adoption of two or more multilayers of alloys / other metals, intermetal alloys or metal oxides has been widely studied. For example, a copper / molybdenum film, a copper / titanium film, or a copper / molybdenum-titanium film can form source / drain wirings that form the gate wiring and data lines of the TFT-LCD, thereby contributing to the large screen of the display. Can be. Accordingly, there is a demand for the development of an etchant (or “etchant”) capable of simultaneously removing these multiple films and leaving no etching solution and no 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 etchant based on hydrogen peroxide may have difficulty in securing stability and increasing productivity due to instant boiling under severe production conditions.

The present invention is to provide a copper or copper alloy film etchant having a fast etching rate and stability and easy control.

In particular, the present invention is to provide a copper or copper alloy film etchant having a taper less than 60 degrees, a CD loss of 1 μm or less, a pattern linearity having good profile characteristics, and a low resorption rate of metal residues.

In addition, the present invention is to provide an etchant for simultaneously etching two or more multilayers of copper or copper alloy films and other metal films.

According to the present invention, potassium persulfate (K ₂ O ₈ S ₂ ), sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), calcium perchlorate (Ca (ClO ₄ ) ₂ ), potassium peroxide (K ₂ O ₂ ) , Sodium peroxide (Na ₂ O ₂ ), calcium peroxide (CaO ₂ ), ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), perchloric acid (HClO ₄ ), permanganic acid 3-20 wt% peroxide selected from the group consisting of potassium (KMnO ₄ ), sodium permanganate (NaMnO ₄ ), potassium dichromate (K ₂ Cr ₂ O ₇ ), sodium dichromate (Na ₂ Cr ₂ O ₇ ) and mixtures thereof ; Amino acid 1-15%; 0.01 to 1 wt% chelating agent; 0.01-5% by weight of an oxidative stabilizer; 0.1-5% by weight of lower alkanesulfonic acid having 1 to 6 carbon atoms; 0.001 to 1% by weight of a surfactant; and a copper or copper alloy film etchant comprising a residual amount of water. If necessary, 0.001 to 0.5% by weight of the fluorine-based deduction agent is further included. 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 molybdenum, titanium, tungsten or an alloy thereof.

The peroxide is a material used as an oxidant of the etchant of the present invention serves to move the corrosion potential of copper to the anode to enable etching. In other words, it can be seen that the copper in the metal state is formed in a soluble passivation capable of Cu ionization. The peroxide of the present invention is preferably ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), perchloric acid (HClO ₄ ), potassium permanganate (KMnO ₄ ), sodium permanganate ( NaMnO ₄ ), potassium dichromate (K ₂ Cr ₂ O ₇ ), sodium dichromate (Na ₂ Cr ₂ O ₇ ) or mixtures thereof, preferably in an amount of 5 to 10% by weight.

The amino acid is preferably an amino acid having 1 to 12 carbon atoms, for example, glutamine, glycine, isoleucine, arginine, proline, tyrosine, glutamic acid, glutamine, glycine or cysteine. The content of amino acid is preferably used within 3-10w%. Amino acids provide an environment in which copper, molybdenum and laminated films can be etched simultaneously, and act as a buffer for metal ions as well as a buffer against acidity changes.

The chelating agent is preferably used in an amount of 0.01 to 0.1 w%, for example, nitrilotriacetic acid ("NTA"), ethylenediaminetetraacetic acid ("EDTA"), diethylenetriaminepentaacetic acid ("DTPA" "), Aminotri (methylenephosphonic acid) (" ATMP "), 1-hydroxyethane (1,1-diylbisproponic acid) (" HEDP "), 5-amino tetrazole ( "5-ATZ"), benzotriazole ("BTA"), ethylenediaminetetra (methyleneproponic acid) ("EDTMP"), diethylenetriaminepenta (methylenephosphonic acid) ("DTPMP") 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.

As glass etching continues, the peroxide-based materials used as oxidants start to decompose little by little, and thus an oxidation stabilizer is required to stabilize them, and glycol derivatives are used. Such glycol derivatives are represented by R ₁ (OR ₂ ) OH where R ₁ = C _n H _{2n +1} (n = 1-4) and R ₂ = C _m H _2m (m = 2-3). Preferably, HP-3 (trade name) which is one of 3M's HP-family is used. Depending on the addition of oxidizing stabilizer, the life time of the solution is 20 ~ 30% difference. Preferably 0.05 to 1% by weight is used.

Lower alkanesulfonic acids having 1 to 6 carbon atoms are preferably used in an amount of 0.1 to 1% by weight as an etching rate aid. Representative examples include methane sulfonic acid and ethanesulfonic acid A. The etching rate aid prevents contact corrosion, or galvanic phenomenon, between dissimilar metals by controlling the etching rate when etching the copper multilayer.

In the present invention, the surfactant adsorbs on the glass surface to quickly release the generated metal ions and does not reattach the dropped metal ions. The surfactant is preferably a fluorine-based surfactant. Fluorine-based surfactants also significantly improve 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 0.001 to 0.5w%. Excessive excess charges can generate a lot of foam, reduce efficiency and damage the glass plate.

As the fluorine ion providing agent, hydrofluoric acid, ammonium fluoride, sodium fluoride, potassium fluoride, etc. may be used, and preferably hydrofluoric acid may be used. The concentration of fluorine ions is preferably 0.001 to 0.5% by weight. When the molybdenum film is etched, small particles of residue are 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. The fluorine ion donor serves to remove the residue and 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.

The etchant of the present invention is applied to two or more multilayers of copper or copper alloy / other metals, other metal alloys or metal oxides. In the case of a two-layer film, it is specifically applied to Cu / Mo, Cu / Mo-Ti, Cu / Mo-W, Cu / Ti. In the case of a three-layer film, specifically, it can be applied to the film | membrane of copper / molybdenum / titanium which makes copper upper and molybdenum / titanium lower.

Referring to the case where the etchant of the present invention is applied to a Cu / Mo-Ti double layer, as illustrated in FIG. 1, Mo-Ti and Cu deposition are performed on a glass substrate, followed by coating a photoresist as shown in FIG. 2. 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.

By etching the copper and copper alloy films using the etchant according to the present invention, it is possible to obtain wirings in which the adhesion to the bottom of the multilayer film is maintained, has a good profile, and the copper layer is not corroded. In addition, as compared to the hydrogen peroxide type etching agent, the safety and life time is excellent, thereby increasing productivity and improving the process.

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

Examples 1 to 10

The board | substrate used for this invention is a glass plate which coated 300 micrometers of molybdenum-titanium 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 5.6 mJ
/ sec 110 ℃
/ 120sec 110 ℃ / 120sec TMAH2.38w%
/ 60sec

For the variety and practicality of the test, the test substrate was cut to 100 * 100mm 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, which can handle up to 5G glass substrates 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 etchant for testing the specimen is a composition ratio as shown in Table 1 and 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 50 liters average and may be less or more than this.

Next, photographs 1 to 4, taken as a criterion for evaluation of physical properties, are the results of precise photographing by FE-SEM. The specimen used at this time is a glass substrate which has been gated in the TFT circuit manufacturing of the liquid crystal display device, and the Mo-Ti on the glass 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.

Physical property test results are shown in Table 1.

Table 1.

division Composition (parts by weight)
Sodium persulfate / Acetyl cystein / BTA / HP-3 / MSA / ammonium fluoride / TFT Properties CD loss Taper Pattern straightness Residue room

city

Yes One 5/3 / 0.05 / 0.01 / 0.5 / 0.01 / 0.01 ◎ O ◎ ◎ 2 5/3 / 0.05 / 0.02 / 0.5 / 0.01 / 0.02 O ◎ △ △ 3 7/5 / 0.05 / 0.02 / 0.8 / 0.01 / 0.02 O ◎ ◎ ◎ 4 7/5 / 0.05 / 0.05 / 0.5 / 0.03 / 0.05 O O ◎ O 5 7/6 / 0.05 / 0.03 / 0.9 / 0.01 / 0.05 O △ ◎ O 6 7/7 / 0.08 / 0.02 / 0.7 / 0.01 / 0.01 ◎ ◎ O O 7 5/10 / 0.07 / 0.05 / 1 / 0.03 / 0.01 ◎ △ △ ◎ 8 5/10 / 0.09 / 0.04 / 1 / 0.03 / 0.04 △ ◎ △ ◎ 9 10/5 / 0.05 / 0.05 / 0.5 / 0.01 / 0.01 O O △ O 10 10/5 / 0.07 / 0.04 / 0.8 / 0.02 / 0.02 O △ O ◎

BTA: Benzotriazole

HP-3: HP-series (trade name of 3M company)

MSA: Methane sulfonic acid

TFT: 3M fluorine-based surfactant

◎: Within 500nm of CD loss O: Within 1um △: Within 1 ~ 1.5um x: Over 1.5um

◎: Taper: 40-50 degrees O: 50-60 degrees △: 60-70 degrees x: 70 degrees or more

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

FIG. 1 shows a specimen used in the present invention in which Mo / Ti deposition and Cu deposition are performed 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 / Ti residues remain when etching with an etchant according to the prior art.

Explanation of the Main References

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

Claims (5)

Potassium persulfate (K ₂ O ₈ S ₂ ), sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), calcium perchlorate (Ca (ClO ₄ ) ₂ ), potassium peroxide (K ₂ O ₂ ), sodium peroxide (Na ₂ O ₂ ), calcium peroxide (CaO ₂ ), ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), perchloric acid (HClO ₄ ), potassium permanganate (KMnO ₄ ) 3-20 wt% peroxide selected from the group consisting of sodium permanganate (NaMnO ₄ ), potassium dichromate (K ₂ Cr ₂ O ₇ ), sodium dichromate (Na ₂ Cr ₂ O ₇ ), and mixtures thereof; Amino acid 1-15%; 0.01 to 1 wt% chelating agent; 0.01-5% by weight of an oxidative stabilizer; 0.1-5% by weight of lower alkanesulfonic acid having 1 to 6 carbon atoms; 0.001 to 0.5 wt% of a surfactant; and a copper or copper alloy film etchant comprising a residual amount of water. The copper or copper alloy film etchant of claim 1, wherein the surfactant is a fluorine-based surfactant and the etchant further comprises 0.001 to 0.5% by weight of a fluorine ion donor. 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 3, wherein the other metal is titanium, molybdenum, or an alloy thereof. The method of claim 4, wherein the amino acid is selected from the group consisting of glutamine, glycine, isoleucine, arginine, proline, tyrosine, glutamic acid, cysteine and mixtures thereof, and the chelating agent is nitrilotriacetic acid ("NTA"), ethylenediamine Tetraacetic acid ("EDTA"), diethylenetriaminepentaacetic acid ("DTPA"), aminotri (methylenephosphonic acid) ("ATMP"), 1-hydroxyethane (1,1-diylbisproponic acid) (" HEDP "), 5-amino tetrazole (" 5-ATZ "), BenzoTriazole (" BTA "), ethylenediaminetetra (methyleneproponic acid) (" EDTMP ") or di Ethylenetriaminepenta (methylenephosphonic acid) (“DTPMP”), and the 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 And, 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.) and the lower alkane sulfonic acid is methane sulfonic acid or ethane sulfonic acid etchant.

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