CN104562009A - Metal wiring etchant composition and method for forming metal wiring using the same - Google Patents

Abstract

The present invention discloses a metal wiring etching liquid composition for etching a metal film to form the gate and source-drain regions of a thin-film transistor constituting a semiconductor circuit, and a method for forming metal wiring using the composition. The metal wiring etching liquid composition comprises: 15 to 25 weight percent hydrogen peroxide; 0.1 to 1 weight percent fluorine compound; 0.5 to 3 weight percent carboxyl group-containing amine; 0.1 to 1 weight percent azole compound; 0.01 to 2 weight percent phosphoric acid compound or its salt; 0.1 to 3 weight percent sulfate; and the remaining weight percent water.

Description

Metal wiring etchant composition and method for forming metal wiring using the same

technical field

The present invention relates to a metal wiring etchant composition, and more specifically, relates to a metal that etches a metal film to form a gate (gate) and a source-drain (source-drain) region of a thin film transistor constituting a semiconductor circuit. Wiring etchant composition and method for forming metal wiring using the composition (Etchant composition for metal wire and method for preparing metal wire using the same).

Background technique

As flat panel display panels such as liquid crystal displays (LCDs) become higher in quality, higher in definition, and larger in size, it is necessary to increase the response speed of the display panel. To this end, the following method is used: the gate (Gate) and source-drain (Source-Drain, S/D) regions of the thin film transistor (Thin film Transistor, TFT) constituting the semiconductor circuit of the display panel It is formed of the existing chromium, aluminum and their alloys, copper metal with low resistance, so as to increase the channel formation speed between the source and the drain when the gate is in operation. In addition, molybdenum (Mo), molybdenum alloy (Mo-alloy), etc. are mixed in the lower part of the above-mentioned copper metal film in order to improve the adhesion between the above-mentioned copper metal film and the lower glass substrate or silicon insulating film and to suppress the diffusion of copper into the silicon film. The intermediate metal film, but the molybdenum and molybdenum alloy residues must be removed to avoid poor drive caused by short circuit wiring in the subsequent module process. As far as the etchant composition for etching the above-mentioned metal film to form metal wires is concerned, the etching speed should be fast, the etched metal wires should have excellent etching profiles, and the number of substrates to be processed should be large. Compositions satisfying these conditions and capable of being stored stably at room temperature are required.

Contents of the invention

technical problem

Therefore, an object of the present invention is to provide a metal wiring etching liquid composition excellent in stability and a metal wiring forming method using the composition.

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

technical problem solving

In order to achieve the above object, the present invention provides a metal wiring etchant composition comprising: 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 azole compounds; 0.01 to 2% by weight of phosphoric acid compounds or salts thereof; 0.1 to 3% by weight of sulfate; and, the remaining weight% of water.

Furthermore, the present invention provides a metal wiring forming method comprising: a step of forming a metal film on a substrate; a step of forming a photoresist pattern on the metal film; and forming the above photoresist pattern A step of etching the above-mentioned metal film by using an etching solution composition in contact with the above-mentioned metal film as a mask, the above-mentioned etching solution composition comprising: 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 carboxyl groups; 0.1 to 1% by weight of azole compounds; 0.01 to 2% by weight of phosphoric acid compounds or salts thereof; 0.1 to 3% by weight of sulfates; water.

beneficial effect

According to the metal wiring etchant composition of the present invention and the metal wiring forming method using the composition, in the wiring formation of a metal film that needs to be etched simultaneously with copper/molybdenum and copper/molybdenum alloy double films, the following An etchant composition mainly composed of hydrogen peroxide, the hydrogen peroxide can maintain high stability and the performance of the etchant based on the high stability for a longer period of time, so that rapid etching can be achieved and excellent taper angle and etching profile can be obtained. Furthermore, by removing residues of molybdenum or molybdenum alloy that is the lower film, it is possible to avoid poor driving due to short-circuiting of wiring in subsequent module processes.

Description of drawings

FIG. 1 is a scanning electron micrograph showing etching characteristics according to an example of the present invention and a comparative example.

FIG. 2 is a scanning electron micrograph showing etching properties of an etching solution composition according to an example of the present invention according to storage days.

FIG. 3 is a scanning electron micrograph showing the etching performance with respect to the number of sheets processed of an etching liquid composition according to an embodiment of the present invention.

detailed description

The present invention will be described in detail below.

The metal wiring etchant composition according to the present invention is used to etch metal films such as copper (Cu), molybdenum (Mo), and molybdenum alloy (Mo-alloy) to form metal wiring of semiconductor circuits such as gate electrodes of thin film transistors. And the composition of the source-drain electrode, the metal wiring etching liquid composition comprises: 15 to 25% by weight of hydrogen peroxide; 0.1 to 1% by weight of fluorine compound; 0.5 to 3% by weight of amine containing carboxyl group 0.1 to 1% by weight of azole compounds; 0.01 to 2% by weight of phosphoric acid compounds or their salts; 0.1 to 3% by weight of sulfate; and, the remaining weight% of the aqueous medium (in the present invention, as required referred to as "water").

The above-mentioned hydrogen peroxide used in the etching solution composition of the present invention is an oxidizing agent for a metal film, for example, it oxidizes and etches a metal film containing copper (Cu) according to the following reaction formula 1, and the content of the above-mentioned hydrogen peroxide is relatively The total amount of the etching solution composition is 15 to 25% by weight, preferably 17 to 24% by weight, more preferably 19 to 23% by weight. If the content of the above-mentioned hydrogen peroxide is too small, there is a risk that the metal film cannot be etched sufficiently, and if it is excessive, the interface between the photoresist film and the metal film used as a protective film will be corroded, resulting in a cone angle ( Taper Angle) is too small, and there is also a risk that the copper metal film will be over-etched.

Reaction 1

Cu+H ₂ O ₂ →CuO+H ₂ O

The fluorine compound is used as a remover and an etching rate regulator for the residue that may be generated when etching the metal film including the molybdenum metal film and the molybdenum alloy film that is the lower layer of the double film. Specific examples of the aforementioned fluorine compounds 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 their mixtures, etc. The content of the above-mentioned fluorine compound is 0.1 to 1% by weight relative to the total amount of the etching solution composition, preferably 0.11 to 0.8% by weight, more preferably 0.12 to 0.5% by weight. If the content of the above-mentioned fluorine compound is less than 0.1% by weight, the etching rate of the metal film will be slow and there is a risk of residues. If it exceeds 1% by weight, the substrate such as glass on which the metal wiring is formed may be damaged and the substrate formed together with the metal wiring may be damaged. Insulating film containing silicon.

The above-mentioned carboxyl group-containing amines perform ligand binding with primary copper ions when etching copper metal, thereby increasing the number of sheets of etching solution to be processed. Specific examples of the above-mentioned carboxyl group-containing amines include alanine, aminobutyric acid, glutamic acid, iminodiacetic acid, nitrilotriacetic acid, and their mixtures etc. The content of the above carboxyl-containing amines is 0.5 to 3% by weight, preferably 1 to 2.5% by weight, more preferably 1.3 to 2.0% by weight relative to the total amount of the etching solution composition. If the content of the above-mentioned carboxyl group-containing amines is less than 0.5% by weight, the number of substrates to be processed may decrease, and if it exceeds 3% by weight, the etching rate of molybdenum and molybdenum alloys will be slowed down and residues may be generated.

The above-mentioned azole compound (cyclic amine compound) inhibits the etching of the copper film and regulates the copper film on the upper part and the lower part in the etching of a double or multiple metal film (for example, a double film of a copper film and a molybdenum film) including a copper film. The etching rate of other metal films. Also, the above-mentioned azole compound reduces cut dimension loss (CD loss) of metal wiring formed by etching, so that the formed metal wiring can be effectively used as a gate line and a data line. The above-mentioned azole compounds are 5-membered heterocyclic ring (5-membered heterocyclic ring) compounds containing nitrogen atoms, such as benzotriazole (benzotriazole), aminotetrazole (aminotetrazole, CH ₃ N ₅ ), aminotetrazole potassium salt ( aminotetrazole of potassium salt), imidazole (imidazole), pyrazole (pyrazole), and their mixtures, etc., preferably aminotetrazole. The content of the above-mentioned azole compound is 0.1 to 1 wt%, preferably 0.2 to 0.8 wt%, more preferably 0.3 to 0.6 wt%, relative to the total amount of the etching solution composition. If the content of the above-mentioned azole compound is included in the above-mentioned 0.1 to 1% by weight, then an appropriate etching rate and excellent wiring straightness can be obtained. If the above-mentioned azole compound is not contained in the etching solution or the content is less than 0.1% by weight, Then, because the etching rate of copper cannot be adjusted, there is a danger of: excessive etching occurs; or CD loss becomes large; or wiring flatness decreases, which causes serious problems when it is applied to a mass production process; or the formed metal wiring If the content of the above-mentioned azole compound exceeds 1% by weight, the etching rate will slow down, thereby prolonging the time of the etching process.

The above-mentioned phosphoric acid compound or its salt plays the role of adjusting the etching rate of copper and molybdenum and copper and molybdenum alloy, or reducing the cone angle of copper. Specific examples of the above-mentioned phosphoric acid compounds or their salts include H ₃ PO ₂ , H ₃ PO ₃ , H ₃ PO ₄ , sodium (Na), potassium (K), lithium (Li), and ammonium (NH4) instead. As the salts of hydrogen atoms (H) in H ₃ PO ₂ , H ₃ PO ₃ , and H ₃ PO ₄ , mixtures thereof, and the like, phosphite can be preferably used. The content of the phosphoric acid compound or its salt is 0.01 to 2% by weight relative to the total amount of the etching solution composition, preferably 0.1 to 1.5% by weight, more preferably 0.3 to 1% by weight. If the content of the above-mentioned phosphoric acid compound or its salt is less than 0.01% by weight, there is a danger that the etching rate of copper is reduced; (or the phenomenon of excessive depression of the substrate), if the content of the above-mentioned phosphoric acid compound or its salt exceeds 2% by weight, the etching rate of copper is excessively increased and it is difficult to adjust in the process, and the lower film, that is, the above-mentioned molybdenum and molybdenum alloy The etching rate is lowered to cause residues.

The above-mentioned sulfate plays the role of adjusting the etching rate of copper and reducing the cone angle. As specific examples of the above-mentioned sulfate, there are compounds through the combination of H2SO4 or _SO4 and ammonium (NH4), and metals Al, Fe, Sb through SO4. , Ba, Be, Cd, Cs, Ca, Ce, Cr, Co, Cu, Ni, K, Ag, Na, Sr, Sn, Zn, Zr combined compounds, and mixtures thereof. The content of the above-mentioned sulfate is 0.1 to 3% by weight relative to the total amount of the etching solution composition, preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight. If the content of the above-mentioned sulfate is less than 0.1% by weight, the taper angle will increase, and if it exceeds 3% by weight, the taper angle will decrease excessively, which may cause problems in the process.

In the etching solution composition according to the present invention, the remaining components are water, preferably deionized water (DI), distilled water and the like. The etchant composition according to the present invention may further contain common additives such as a pH adjuster and a preservative as necessary within the range in which the objects and effects of the invention are achieved. The etchant composition according to the present invention can be prepared by any known method. For example, the above-mentioned fluorine compounds, carboxyl-containing amines, azole compounds, phosphoric acid compounds or their salts, and sulfates can be added to aqueous media such as deionized water and distilled water according to the required concentration, and then added with the desired concentration. The composition of the present invention is prepared by using the above-mentioned hydrogen peroxide at a comparable concentration.

The etchant composition according to the present invention is used to etch a metal film to form metal wiring of a semiconductor circuit. Examples of the metal film to be etched by the composition of the present invention include a single metal film including copper (Cu), an alloy film including a copper alloy film, and at least one of a copper film as an upper film and a lower film. Multiple films such as molybdenum film and molybdenum alloy film, etc. Furthermore, when etching the above-mentioned multiple film, the above-mentioned upper film and the above-mentioned lower film may be etched together.

According to the metal wiring forming method of the present invention, in manufacturing an integrated circuit such as a semiconductor, a metal film such as the above-mentioned copper single film or a multiple film composed of copper/molybdenum and copper/molybdenum alloy is formed on the substrate, and the metal film is formed on the above-mentioned metal film. A photoresist pattern is formed on it. Next, the above-mentioned photoresist pattern is used as a mask, and the etching solution composition of the present invention is brought into contact with the above-mentioned metal film to etch the above-mentioned metal film, so that metal wiring such as a gate electrode or a source-drain can be formed. pole electrode.

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

[Examples 1-5, Comparative Examples 1-5] Preparation of Etching Solution Composition

In order to evaluate the etching performance of the etching liquid composition, the etching liquid composition (embodiments 1 to 5, comparative example 1) comprising the compound shown in the following table 1 and the water (deionized water, deionized water) of the remaining weight % was prepared. ~5).

Table 1

[Examples 1-5, Comparative Examples 1-5] Evaluation of etching solution composition

Form a photoresist pattern on copper/molybdenum and copper/molybdenum alloy double film, and carry out more than 60% (with time as benchmark) overetching (overetching). The cross-section of the etched metal film was observed with a scanning electron microscope, and Table 2 below shows the etching rate, cut dimension bias (CD bias, cut dimension bias), taper angle, and molybdenum and molybdenum alloy residues. The cutting dimension deviation (CD bias) refers to the distance between the end of the photoresist pattern and the end of the copper film, which should be 0.5 to 0.7 μm for small and uniform taper etching. In terms of etching speed, the copper film should have roughly 75 to /sec speed. Moreover, the taper angle is an inclination angle when viewed from the side of the etched metal film, which should be 45 to 50°, and residues of molybdenum (Mo) or molybdenum alloy (Mo-alloy) should not appear.

Table 2

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

- Excellent: (Etching speed: 65 to /sec, CD bias: 0.8 to 0.99μm, taper angle: 51 to 55°)

- bad: ( etch rate: /sec or less /sec or more, cutting dimension deviation (CDbias): 1.0 μm or more, taper angle: 56° or more, Mo or Mo-Alloy residue: O)

FIG. 1 is a scanning electron micrograph showing etching characteristics according to an example of the present invention and a comparative example. Referring to the above-mentioned Table 2 and Fig. 1, in Example 1 and Example 2, the etching characteristics shown are all very good, and in the case of Example 3 using hypophosphite, the etching rate is higher than that using the same content of Phosphite slows down, and in Example 4 where sulfate is added, the cutting dimension deviation (CD-bias) of the copper film has increased. In the case of Example 5, the residue of molybdenum (Mo) or molybdenum alloy (Mo-alloy) which may be generated by increasing the content of carboxyl group-containing amines was prevented by increasing the fluorine content. However, when reducing the content of hydrogen peroxide and azole compounds as in Comparative Example 1, which exceeded the proportion of the etching solution, the etching rate was obviously slow, the cone angle became smaller, and molybdenum (Mo) or molybdenum alloy (Mo -alloy) residue, in Comparative Example 2 in which the content of carboxyl group-containing amines was increased, a large amount of molybdenum (Mo) or molybdenum alloy (Mo-alloy) residue was generated. In the case of not adding phosphite or using more than 2% of phosphate as in Comparative Example 3 and Comparative Example 4, since the upper copper film and the lower molybdenum (Mo) or molybdenum alloy (Mo- The etching rate of alloy) produces an under-cut in the lower part, or over-etching of the copper film and residues of molybdenum (Mo) or molybdenum alloy (Mo-alloy). Also, in Comparative Example 5 in which no sulfate was used, the taper angle increased to have a problem of having an unsuitable taper angle.

Storage Stability Evaluation of Etching Solution Composition

The composition of Example 1 was prepared and stored at 18°C (low temperature storage) for 30 days and at 27°C (normal temperature storage) for 15 days in order to evaluate the storage stability and the etching performance with respect to the number of sheets processed. are shown in Table 3 below.

table 3

FIG. 2 is a scanning electron micrograph showing etching properties of an etching solution composition according to an example of the present invention according to storage days. As shown in the above Table 3 and FIG. 2, the etchant composition according to the present invention was stored at a low temperature (18° C.) for 30 days and at a normal temperature (27° C.) for 15 days. As a result, the etching characteristics did not change. The performance similar to the initial stage was maintained, and no precipitates were generated.

Evaluation of etching performance with respect to the number of treated sheets of etching liquid composition

The composition of Example 1 was prepared, and copper ions were co-contaminated at a rate of 1000 ppm/h for 5 hours in order to evaluate the etching performance with respect to the number of sheets processed, and the results are shown in Table 4 below.

Table 4

FIG. 3 is a scanning electron micrograph showing the etching performance with respect to the number of sheets processed of an etching liquid composition according to an embodiment of the present invention. The copper/molybdenum alloy double film substrate was over-etched using the etchant composition according to the present invention. As a result, as shown in the above-mentioned Table 4 and FIG. Variety. In this way, the etching solution composition according to the present invention can maintain the same performance as the initial stage even if a plurality of copper/molybdenum alloy double films are etched together.

Claims (9)

1. a metal wiring etchant, is characterized in that, comprises:

The hydrogen peroxide of 15 to 25 % by weight;

The fluorine cpd of 0.1 to 1 % by weight;

The amine containing carboxyl of 0.5 to 3 % by weight;

The azole compounds of 0.1 to 1 % by weight;

The phosphate compound of 0.01 to 2 % by weight or its salt;

The vitriol of 0.1 to 3 % by weight; And,

All the other water of % by weight.

2. metal wiring etchant according to claim 1, is characterized in that,

Above-mentioned fluorine cpd are selected from by HF (hydrofluoric acid), NaF, NaHF ₂, NH ₄f (Neutral ammonium fluoride), NH ₄hF ₂, NH ₄bF ₄, KF, KHF ₂, AlF ₃, HBF ₄, LiF ₄, KBF ₄, CaF ₂, and they mixture composition group in.

3. metal wiring etchant according to claim 1, is characterized in that,

The above-mentioned amine containing carboxyl is selected from the group be made up of L-Ala, aminobutyric acid, L-glutamic acid, iminodiethanoic acid, nitrilotriacetic acid(NTA) and their mixture.

4. metal wiring etchant according to claim 1, is characterized in that,

Above-mentioned azole compounds is selected from the group be made up of benzotriazole, amino tetrazole, amino tetrazole sylvite, imidazoles, pyrazoles and their mixture.

5. metal wiring etchant according to claim 1, is characterized in that,

Above-mentioned phosphate compound or its salt are selected from by H ₃pO ₂, H ₃pO ₃, H ₃pO ₄, instead of above-mentioned H with sodium, potassium, lithium, ammonium ₃pO ₂, H ₃pO ₃, H ₃pO ₄in the salt of hydrogen atom and their mixture composition group in.

6. metal wiring etchant according to claim 5, is characterized in that,

Above-mentioned phosphate compound or its salt are phosphites.

7. metal wiring etchant according to claim 1, is characterized in that,

Above-mentioned vitriol is selected from by passing through H ₂sO ₄or SO ₄with the compound of the combination of ammonium, pass through SO ₄in the group formed with compound and their mixture of the combination of metal A l, Fe, Sb, Ba, Be, Cd, Cs, Ca, Ce, Cr, Co, Cu, Ni, K, Ag, Na, Sr, Sn, Zn, Zr.

8. metal wiring etchant according to claim 1, is characterized in that,

Above-mentioned metal wiring is selected from the group be made up of the single metallic membrane comprising copper, the multiple film of alloy film and the copper film comprised as upper membrane and the molybdenum film as lower film and molybdenum alloy film that comprises tin-copper alloy film WU.

9. a metal wiring formation method, is characterized in that, comprising:

Substrate is formed the step of metallic membrane;

Above-mentioned metallic membrane is formed the step of photo-resist pattern; And,

Above-mentioned photo-resist pattern is used as mask, and makes etchant and above-mentioned metal diaphragm contacts and the step of etching metal film,

Above-mentioned etchant comprises: the hydrogen peroxide of 15 to 25 % by weight; The fluorine cpd of 0.1 to 1 % by weight; The amine containing carboxyl of 0.5 to 3 % by weight; The azole compounds of 0.1 to 1 % by weight; The phosphate compound of 0.01 to 2 % by weight or its salt; The vitriol of 0.1 to 3 % by weight; And, all the other water of % by weight.