KR102279498B1 - Etchant composition for metal wire and method for preparing metal wire using the same - Google Patents

Abstract

Disclosed are a metal wiring etchant composition for forming gate and source-drain regions of a thin film transistor constituting a semiconductor circuit by etching a metal layer, and a method of forming a metal wiring using the same. The metal wiring etchant composition comprises 15 to 25 wt% of hydrogen peroxide, 0.1 to 1 wt% of a fluorine compound, 0.5 to 3 wt% of an amine containing a carboxyl group, 0.1 to 1 wt% of an azole compound, 0.01 to 2 wt% of a phosphoric acid-based compound or a salt thereof, 0.1 to 3% by weight of a sulfate, and the remainder of water.

Description

Metal wiring etchant composition and method of forming metal wiring using same {Etchant composition for metal wire and method for preparing metal wire using the same}

The present invention relates to a metal wiring etchant composition, and more particularly, a metal wiring etchant composition for forming gate and source-drain regions of a thin film transistor constituting a semiconductor circuit by etching a metal film, and a method of forming a metal wiring using the same is about

As the quality of flat panel display panels such as liquid crystal display devices (LCDs) increases, the picture quality increases, and the area increases, it is necessary to increase the response speed of the display panel. To this end, the gate (Gate) and source-drain (S/D) region of a thin film transistor (TFT) constituting the semiconductor circuit of the display panel is made of conventional chromium, aluminum and alloys thereof. However, by forming a copper metal having a low resistance, a method of increasing a channel formation rate between a source and a drain during operation of a gate electrode is being used. In addition, in order to improve adhesion between the copper metal film and the underlying glass substrate or silicon insulating film and to suppress diffusion of copper into the silicon film, molybdenum (Mo), molybdenum Although an intermediate metal film such as an alloy (Mo-alloy) is mixed, the molybdenum and residues of the molybdenum alloy must be removed to prevent a driving defect due to a short circuit of the wiring during a subsequent module process. The etchant composition for forming metal wiring by etching the metal film should have a high etching rate, an excellent etch profile of the etched metal wiring, and a large number of substrates to be processed. These conditions are met and stable storage at room temperature is possible. A possible composition is desired.

Accordingly, an object of the present invention is to provide a metal wiring etchant composition having excellent stability and a method for forming a metal wiring using the same.

Another object of the present invention is to provide a metal wiring etchant composition having a fast etching rate and excellent etching profile, and a method of forming a metal wiring using the same.

In order to achieve the above object, the present invention, 15 to 25% by weight of hydrogen peroxide; 0.1 to 1% by weight of a fluorine compound; 0.5 to 3% by weight of amines containing a carboxyl group; 0.1 to 1% by weight of an azole-based compound; 0.01 to 2% by weight of a phosphoric acid-based compound or a salt thereof; Provided is a metal wiring etchant composition comprising 0.1 to 3% by weight of sulfate and the remainder of water.

In addition, the present invention, the step of forming a metal film on the substrate; forming a photoresist pattern on the metal layer; and using the photoresist pattern as a mask to contact the metal layer with an etchant composition to etch the metal layer, wherein the etchant composition comprises 15 to 25 wt% of hydrogen peroxide, 0.1 to 1 wt% of fluorine Compound, 0.5 to 3% by weight of amines containing a carboxyl group, 0.1 to 1% by weight of an azole compound, 0.01 to 2% by weight of a phosphoric acid-based compound or a salt thereof, 0.1 to 3% by weight of a sulfate salt and the remainder of water A method for forming a phosphorus, metal wiring is provided.

The metal wiring etchant composition and the metal wiring forming method using the same according to the present invention, in the wiring formation of the metal film to be etched in a double film of copper / molybdenum and copper / molybdenum alloy, high stability and the resulting etchant By using an etchant composition containing hydrogen peroxide as a main component, which can maintain performance for a longer period of time, fast etching, excellent taper angle, and etching profile can be obtained. In addition, by removing the residue of the lower layer of molybdenum or molybdenum alloy, it is possible to block a driving defect due to a short circuit of the wiring during a subsequent module process.

1 is a scanning electron microscope photograph showing etching characteristics according to an embodiment and a comparative example of the present invention.
2 is a scanning electron microscope photograph showing the etching characteristics according to the number of days of storage of the etchant composition according to an embodiment of the present invention.
3 is a scanning electron microscope photograph showing the etching performance with respect to the number of treatment sheets of the etchant composition according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The metal wiring etchant composition according to the present invention etches a metal film such as copper (Cu), molybdenum (Mo), and molybdenum alloy (Mo-alloy) to form a metal wiring of a semiconductor circuit, for example, a thin film transistor. A composition for forming the gate electrode and the source-drain electrode of 15 to 25% by weight of hydrogen peroxide, 0.1 to 1% by weight of a fluorine compound, 0.5 to 3% by weight of an amine containing a carboxyl group, 0.1 to 1% by weight of an azole-based compound compound, 0.01 to 2% by weight of a phosphoric acid-based compound or a salt thereof, 0.1 to 3% by weight of a sulfate, and the remaining aqueous medium (in the present specification, as necessary, simply referred to as "water").

The hydrogen peroxide used in the etchant composition of the present invention is an oxidizing agent for the metal film, for example, oxidizes and etches a metal film containing copper (Cu) according to the following Reaction Formula 1, and the content of the hydrogen peroxide is, relative to 15 to 25% by weight, preferably 17 to 24% by weight, more preferably 19 to 23% by weight. If the content of the hydrogen peroxide is too small, there is a risk of insufficient etching of the metal film, and if too much, erosion occurs at the interface between the photoresist film used as a protective film and the metal film, and the taper angle may become too small. There is also a risk that the copper metal film may be excessively etched.

[Scheme 1]

Cu + H ₂ O ₂ → CuO + H ₂ O

The fluorine compound is used as an etch rate regulator and removal of residues that may be generated during etching of a metal film including a molybdenum metal film and a molybdenum alloy film as the lower layers in the double film. Specific examples of the fluorine compound include HF (hydrofluoric acid), NaF, NaHF ₂ , NH ₄ F (ammonium fluoride), NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , AlF ₃ , HBF ₄ , LiF ₄ , KBF ₄ , CaF _{2 ,} and mixtures thereof. The content of the fluorine compound is 0.1 to 1 wt%, preferably 0.11 to 0.8 wt%, more preferably 0.12 to 0.5 wt%, based on the total etchant composition. If the content of the fluorine compound is less than 0.1% by weight, the etching rate of the metal film may be slowed and there is a risk of residues, and if it exceeds 1% by weight, silicon formed together with a substrate such as glass on which a metal wiring is formed and a metal wiring It may cause damage to the insulating film containing it.

The amines including the carboxyl group serve to increase the number of treatments of the etchant by binding ligands with the primary copper ions during the etching of copper metal. Specific examples of the amines including the carboxyl group include alanine, aminobutyric acid, glutamic acid, iminodiacetic acid, nitrilotriacetic acid, and mixtures thereof. . The content of the amines including the carboxyl group is 0.5 to 3 wt%, preferably 1 to 2.5 wt%, more preferably 1.3 to 2.0 wt%, based on the total etchant composition. If the content of the amines including the carboxyl group is less than 0.5% by weight, there is a fear that the number of substrates to be processed may be reduced, and if it exceeds 3% by weight, the etching rate of molybdenum and molybdenum alloy may be slowed to cause residues there is

The azole compound (cyclic amine compound) suppresses the etching of the copper film in the etching of a double or multiple metal film (eg, a double film of a copper film and a molybdenum film) including a copper film, Controls the etching rate of the copper layer and other metal layers underneath. In addition, the azole-based compound reduces cut dimension loss (CD loss) of a metal line formed by etching, so that the formed metal line can be usefully used as a gate and a data line. The azole-based compound is a 5-membered heterocyclic ring compound containing a nitrogen atom, for example, benzotriazole, aminotetrazole (aminotetrazole, CH ₃ N ₅ ), aminotetrazole. Potassium salt (aminotetrazole of potassium salt), imidazole (imidazole), pyrazole (pyrazole), and mixtures thereof, and the like, and more preferably aminotetrazole. The content of the azole-based compound is 0.1 to 1 wt%, preferably 0.2 to 0.8 wt%, more preferably 0.3 to 0.6 wt%, based on the total etchant composition. When the content of the azole-based compound is included in the 0.1 to 1% by weight, it is possible to obtain an appropriate etching rate and excellent straightness of the wiring, If it is not added to the etchant or is less than 0.1% by weight, excessive etching occurs because the etching rate of copper cannot be controlled, the CD loss increases, or the straightness of the wiring decreases, causing serious problems when applying the mass production process, or formed metal wiring There is a fear that the etch profile of the etchant may be deteriorated, and when it exceeds 1 wt%, the etch rate may be slowed and the time of the etch process may be prolonged.

The phosphoric acid-based compound or a salt thereof serves to control the etching rate of copper and molybdenum and copper and molybdenum alloy, or to lower the taper angle of copper. Specific examples of the phosphoric acid-based compound or its salt, H ₃ PO ₂ , H ₃ PO ₃ , H ₃ PO ₄ and the H ₃ PO ₂ , H ₃ PO ₃ , H ₃ PO ₄ A hydrogen atom (H) is removed and Sodium (Na), potassium (K), lithium (Li), ammonium (NH ₄ ) and salts and mixtures thereof may be used, preferably phosphite. The content of the phosphoric acid-based compound or its salt is 0.01 to 2% by weight, preferably 0.1 to 1.5% by weight, more preferably 0.3 to 1% by weight, based on the total etchant composition. When the content of the phosphoric acid-based compound or its salt is less than 0.01% by weight, the etching rate of copper is lowered or the etching rate of the lower film, molybdenum and molybdenum alloy, is increased, so that the undercut (lower film (or substrate)) This excessive pitting phenomenon) may occur, and when it exceeds 2% by weight, the etching rate of copper is excessively increased, making it difficult to control the process, and the lower layer of the molybdenum and molybdenum alloy The etching rate may be reduced to cause residues.

The sulfate serves to control the etching rate and lower the taper angle of copper, and specific examples of the sulfate include H ₂ SO ₄ or SO ₄ and a compound formed by bonding of ammonium (NH _{4 ) and SO 4} and Al, There are compounds by metal bonding of Fe, Sb, Ba, Be, Cd, Cs, Ca, Ce, Cr, Co, Cu, Ni, K, Ag, Na, Sr, Sn, Zn, Zr, and mixtures thereof. . The content of the sulfate is 0.1 to 3% by weight, preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight, based on the total etchant composition. When the content of the sulfate is less than 0.1% by weight, the taper angle is high, and when it exceeds 3% by weight, the taper angle is too low, which may cause problems in the process.

In the etchant composition of the present invention, the remaining component is water, preferably deionized water (DI), distilled water, or the like. The etchant composition according to the present invention may further include conventional additives such as pH adjusters and corrosion inhibitors, if necessary, within the limits of achieving the object and effect of the present invention. The etchant composition according to the present invention may be prepared by any known method. For example, the fluorine compound, amine-containing carboxyl group, azole compound, phosphoric acid compound, or a salt and sulfate thereof are added to an aqueous medium such as deionized water or distilled water at the required concentration, and then hydrogen peroxide is added to the desired concentration. Thus, the composition of the present invention can be prepared.

The etchant composition according to the present invention is used to etch a metal film to form a metal wiring of a semiconductor circuit. The metal film etched by the composition of the present invention includes a single metal film including copper (Cu), an alloy film including a copper alloy film, and a copper film as an upper film, and at least one molybdenum film as a lower film. and a multilayer including a molybdenum alloy film and the like. In addition, when etching the multi-layer, it is possible to collectively etch the upper layer and the lower layer.

In the method for forming a metal wiring according to the present invention, in the manufacture of an integrated circuit such as a semiconductor, a metal film such as the copper single film or a multi-layer made of copper/molybdenum and copper/molybdenum alloy is formed on a substrate, A photoresist pattern is formed on the metal layer. Next, using the photoresist pattern as a mask, by contacting the etchant composition of the present invention to the metal film to etch the metal film, a metal wiring, for example, a gate electrode or a source-drain electrode may be formed. .

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are intended to illustrate the present invention, but the present invention is not limited by the following examples.

[Examples 1 to 5, Comparative Examples 1 to 5] Preparation of etchant composition

In order to evaluate the etching performance of the etchant composition, an etchant composition (Examples 1 to 5, Comparative Examples 1 to 5) including the compounds shown in Table 1 and the remaining water (deionized water) was prepared.

hydrogen peroxide
(wt%) Fluorine compound (wt%) Amines including carboxyl group (wt%) Azole compound (wt%) Phosphate (wt%) Sulfate (wt%) Example 1 21 0.1 1.5 0.4 0.4 (phosphite) One Example 2 21 0.1 1.5 0.4 1 (hypophosphite) One Example 3 21 0.1 1.5 0.4 0.4 (hypophosphite) One Example 4 21 0.1 1.5 0.4 0.4 (phosphite) 3 Example 5 21 0.2 3 0.4 0.4 (phosphite) One Comparative Example 1 11 0.1 1.5 0.15 0.4 (phosphite) One Comparative Example 2 21 0.1 4 0.4 0.4 (phosphite) One Comparative Example 3 21 0.1 1.5 0.4 0 One Comparative Example 4 21 0.1 1.5 0.7 2.5 (phosphite) One Comparative Example 5 21 0.1 1.5 0.4 0.4 (phosphite) 0

[Examples 1 to 5, Comparative Examples 1 to 5] Evaluation of the etchant composition

A photoresist pattern is formed on a copper / molybdenum and copper / molybdenum alloy double film, and the metal film is etched in excess of 60% (based on time) with the etchant composition of Examples 1 to 5 and Comparative Examples 1 to 5 ( overetching). The cross section of the etched metal film was observed with a scanning electron microscope, and the etching rate, CD bias (cut dimension bias), taper angle, and residues of molybdenum and molybdenum alloy are shown in Table 2 below. CD bias means the distance between the end of the photoresist pattern and the end of the copper film, and should be 0.5 to 0.7 µm for uniform taper etching with small steps, and the appropriate etching rate is about 75 to 85 Å/sec based on the copper film should have a speed of In addition, the taper angle is a slope viewed from the side of the etched metal film, and should be 45 to 50°, and there should be no residue of molybdenum (Mo) or molybdenum alloy (Mo-alloy).

Etching rate of copper film CD bias taper angle Residue of molybdenum (Mo) or molybdenum alloy (Mo-alloy) Example 1 very good very good very good very good Example 2 very good very good very good very good Example 3 very good very good very good very good Example 4 very good very good very good very good Example 5 very good very good very good very good Comparative Example 1 bad Great bad bad Comparative Example 2 very good very good very good bad Comparative Example 3 bad bad bad very good Comparative Example 4 bad bad very good bad Comparative Example 5 bad Great Great very good

- Very good: (etch rate: 75 to 85 Å/sec, CD bias: 0.5 to 0.79 μm, taper angle: 45 to 50°, Mo or Mo-Alloy residue: X)

- Excellent: (etch rate: 65 to 74 Å/sec, CD bias: 0.8 to 0.99 μm, taper angle: 51 to 55°)

- Defect: (Etch rate: 64 Å/sec or less or 86 Å/sec or more, CD bias: 1.0 μm or more, Taper angle: 56° or more, Mo or Mo-Alloy residue: O)

1 is a scanning electron microscope photograph showing etching characteristics according to an embodiment and a comparative example of the present invention. Referring to Table 2 and FIG. 1, in Examples 1 and 2, all etching properties were very excellent, and in Example 3 using hypophosphite, the etching rate was slow compared to the same amount of phosphite, In Example 4 with increased sulfate, the CD-bias of the copper film was increased. In the case of Example 5, residues of molybdenum (Mo) or molybdenum alloy (Mo-alloy), which may be generated by increasing the content of amines including carboxyl groups, were prevented by increasing the fluorine content. However, as in Comparative Example 1 out of the etching composition ratio range, when the content of hydrogen peroxide and the azole-based compound is reduced, the etching rate is remarkably slowed, the taper angle is lowered, and molybdenum (Mo) or a molybdenum alloy (Mo-alloy) ) was generated, and in Comparative Example 2 in which the content of amines including carboxyl groups was increased, a large amount of residues of molybdenum (Mo) or molybdenum alloy (Mo-alloy) were generated. As in Comparative Examples 3 and 4, when no phosphite is added or 2% or more of phosphate is used, the etching rate of the upper copper film and the lower molybdenum (Mo) or molybdenum alloy (Mo-alloy) was not properly controlled, resulting in undercuts or over-etching of the copper film and residues of molybdenum (Mo) or molybdenum alloys (Mo-alloy). In addition, in Comparative Example 5 in which sulfate was not used, the taper angle was increased, and thus a problem occurred in that the taper angle was not appropriate.

Storage stability evaluation of etchant composition

In order to prepare the composition of Example 1 and evaluate storage stability and etching performance for the treatment medium, it was carried out at 18 °C (low temperature storage) for 30 days and at 27 °C (room temperature storage) for 15 days, respectively, as shown in Table 3 below. The results are shown.

storage temperature 18℃ storage days 0 days 5 days 10 days 15th 20 days 25 days 30 days Cu/Mo-alloy
Etching rate (sec) 35/25 35/25 35/25 35/25 35/25 35/25 35/25 CD-bias (㎛) 0.722 0.740 0.704 0.725 0.721 0.716 0.718 Taper angle (˚) 46 47 46 47 46 46 46 storage temperature 27℃ storage days 0 days 3 days 6 days 9 days 12 days 15th Cu/Mo-alloy
Etching rate (sec) 35/25 35/25 35/25 35/25 35/25 35/25 CD-bias (㎛) 0.722 0.747 0.724 0.714 0.727 0.725 Taper angle (˚) 46 46 46 45 46 46

2 is a scanning electron microscope photograph showing the etching characteristics according to the number of days of storage of the etchant composition according to an embodiment of the present invention. As shown in Table 3 and FIG. 2, using the etchant composition according to the present invention, performance similar to the initial without change in etching characteristics, respectively, for 30 days at low temperature storage (18 ℃) and 15 days at room temperature storage (27 ℃) was maintained, and no precipitation occurred.

Evaluation of the etching performance for the treatment number of the etchant composition

In order to prepare the composition of Example 1 and evaluate the etching performance with respect to the treatment medium, the copper ions were contaminated at a rate of 1000 ppm per hour for 5 hours, and the results are shown in Table 4 below.

Copper contamination (ppm) 0 1000 2000 3000 4000 5000 Cu/Mo-alloy etch rate (sec) 35/25 35/15 35/15 35/15 34 of 14 32/12 CD-bias (㎛) 0.722 0.721 0.722 0.730 0.732 0.759 Taper angle (˚) 46 48 52 53 53 55

3 is a scanning electron microscope photograph showing the etching performance with respect to the number of treatment sheets of the etching solution composition according to an embodiment of the present invention. As shown in Table 4 and FIG. 3, as a result of over-etching the copper/molybdenum alloy double-layer substrate using the etchant composition according to the present invention, the etching characteristics were changed until the copper ion concentration reached 5000 ppm. can confirm that there is no As such, the etchant composition according to the present invention can maintain the same performance as the initial stage even when a plurality of copper/molybdenum alloy double films are etched in batches.

Claims (9)

15 to 25% by weight of hydrogen peroxide;
0.1 to 1% by weight of a fluorine compound;
0.5 to 3% by weight of amines containing a carboxyl group;
0.1 to 1% by weight of an azole-based compound;
0.01 to 2% by weight of H ₃ PO ₂ , H ₃ PO ₃ and the H ₃ PO ₂ , H ₃ PO ₃ salts in which hydrogen atoms are removed and bonded to sodium, potassium, lithium, ammonium, and mixtures thereof a phosphoric acid-based compound selected from or a salt thereof;
0.1 to 3% by weight of sulfate; and
A metal wiring etchant composition comprising the remainder of water. The method according to claim 1, The fluorine compound, HF (hydrofluoric acid), NaF, NaHF ₂ , NH ₄ F (ammonium fluoride), NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , AlF ₃ , HBF ₄ , LiF ₄ , KBF ₄ , CaF _{2 ,} and a mixture thereof, which is selected from the group consisting of, a metal wiring etchant composition. The metal wiring etchant composition of claim 1, wherein the amines containing a carboxyl group are selected from the group consisting of alanine, aminobutyric acid, glutamic acid, iminodiacetic acid, nitrilotriacetic acid, and mixtures thereof. The metal wiring etchant composition of claim 1, wherein the azole-based compound is selected from the group consisting of benzotriazole, aminotetrazole, aminotetrazole potassium salt, imidazole, pyrazole, and mixtures thereof. delete The method according to claim 1, wherein the phosphoric acid-based compound or a salt thereof is a phosphite, the metal wiring etchant composition. The method according to claim 1, wherein the sulfate is H ₂ SO ₄ or SO ₄ and a compound formed by combining ammonium and SO ₄ with Al, Fe, Sb, Ba, Be, Cd, Cs, Ca, Ce, Cr, Co, Cu , Ni, K, Ag, Na, Sr, Sn, Zn, Zr by metal bonding compound and mixtures thereof, the metal wiring etchant composition. The method according to claim 1, wherein the metal wiring comprises a single metal film including copper, an alloy film including a copper alloy film, and a copper film as an upper film, and a multilayer including a molybdenum film and a molybdenum alloy film as a lower film. Which is selected from the group consisting of a film, a metal wiring etchant composition. forming a metal film on the substrate;
forming a photoresist pattern on the metal film; and
Using the photoresist pattern as a mask to contact the etchant composition to the metal film, comprising the step of etching the metal film,
The etchant composition is 15 to 25% by weight of hydrogen peroxide, 0.1 to 1% by weight of a fluorine compound, 0.5 to 3% by weight of an amine containing a carboxyl group, 0.1 to 1% by weight of an azole-based compound, 0.01 to 2% by weight of H ₃ PO ₂ , H ₃ PO ₃ and the H ₃ PO ₂ , H ₃ PO ₃ A phosphoric acid-based compound selected from the group consisting of salts in which a hydrogen atom is removed and bonded to sodium, potassium, lithium, and ammonium, and mixtures thereof, or its salt, 0.1 to 3% by weight sulfate, and the balance water.

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