TWI405875B - Echant compositions for metal laminated films having titanium and aluminum layer - Google Patents

Abstract

The present invention aims to provide etchant compositions for metal laminated films on an insulating film substrate such as glass, a silicon substrate, or a semiconductor substrate, which includes a layer consisting of titanium or titanium alloy, and a layer consisting of aluminum or aluminum alloy formed films by sputtering method, wherein said etchants do not damage substrates under the metal laminated films, forming taper angles of between 30 and 90 degrees and etching in a lump metal laminated films. This aim is achieved by the present etchant compositions comprising at least one fluorine compound selected from the group consisting of metal salts of ammonium salts of hydrofluoric acid, hexafluorosilicic acid, metal salts or ammonium salts of hydrofluoric acid, tetrafluoroboric acid and metal salts of ammonium salts of tetrafluoric acid, and oxidizing agent.

Description

Etching liquid composition of titanium and aluminum metal laminated film

The present invention relates to an etching liquid composition for a metal laminated film which is used for a gate, a source, a drain electrode or the like of a liquid crystal display.

Aluminum or an alloy obtained by adding an impurity such as bismuth, antimony or copper to aluminum is inexpensive and has a very low electrical resistance. Therefore, it is used as a material for a gate, a source, and a drain electrode of a liquid crystal display.

However, aluminum or aluminum alloys are slightly inferior in adhesion to the base film, that is, the glass substrate, and are easily corroded by chemicals, heat, etc., so molybdenum or molybdenum is used in the upper and/or lower portions of the aluminum or aluminum alloy. The alloy film is used as an electrode material in the form of a laminated film, and the laminated film is collectively etched by using an etching solution such as phosphoric acid.

In recent years, titanium or titanium alloys have attracted attention because of the high price of molybdenum or molybdenum alloys and the demand for improved (resistance) corrosion due to chemical liquids, heat, and the like. The phosphoric acid or the like used for etching molybdenum cannot be used for etching titanium or a titanium alloy, and the semiconductor substrate is subjected to dry etching using reactive ion etching (Reactive Ion Etch; RIE) using a halogen-based gas as etching titanium-aluminum. A method of laminating a metal film. The RIE can be controlled to have a tapered (push-out) shape by anisotropic etching, but it is necessary to have an expensive vacuum device, a high-frequency generating device, etc., which is disadvantageous in terms of cost. Therefore, it is desired to develop a general etchant which can be more inexpensive and can also shorten the processing time.

On the other hand, in the process of a semiconductor device, when a metal thin film containing titanium as a main component is etched, it is known that a hydrofluoric acid-based etching liquid is generally used (for example, Patent Document 1). Further, it is also known that titanium or a titanium alloy can be etched by using an etching solution of ammonia water-hydrogen peroxide water (for example, Patent Document 2).

However, the hydrofluoric acid-based etching liquid cannot be used because the glass substrate, the tantalum substrate, and the compound semiconductor substrate of the substrate are damaged. Further, when ammonia water-hydrogen peroxide water is used, bubbles are generated due to the decomposition of hydrogen peroxide water, and the bubbles may adhere to the substrate, the etching may be incomplete, and the life of the etching liquid may be short, which may make it difficult to use.

In addition, unlike the use of the etching liquid of the present invention as a glass substrate or the like, it is disclosed that a composition (Patent Document 3) contains hydrogen peroxide, a fluoride, an inorganic acid, and a fluorine-based surfactant as essential components. Surface scaling and smoothing of titanium or titanium alloy used for decorative or electronic parts; but for etching a metal laminated film (containing a layer composed of titanium or an alloy containing titanium as a main component, and aluminum or There is no teaching about the layer of an alloy containing aluminum as a main component. Further, although an aqueous solution containing peroxodisulfate and fluoride is disclosed as an etching solution for etching a metal laminated film composed of a titanium layer and a copper layer (Patent Document 4), it is not related to etching by an aluminum layer. A metal laminated film made of a titanium layer.

An etching liquid (Patent Document 5) containing fluoric acid, periodic acid, and sulfuric acid as an etching liquid for collectively etching a titanium-aluminum metal laminated film is disclosed. However, since this etching liquid etches each metal film of the metal laminated film at the same etching rate, the taper (push-out) angle after etching is approximately 90 degrees. Recently, in order to prevent a disconnection of a source electrode line formed on a gate electrode line, a short circuit between a gate electrode line and a source electrode line, etc., the wiring on the substrate is often tapered (taper angle) It is less than 90 degrees (Patent Document 6), and the etching liquid of Patent Document 5 cannot cope with such a purpose. Moreover, such an etching liquid also has a problem that the glass substrate is damaged.

Generally, the etch rate of the etchant to aluminum or aluminum alloy is greater than the etch rate of titanium or titanium alloy. Therefore, it is not known at present that a metal laminated film containing a layer composed of titanium or a titanium alloy and a layer composed of aluminum or an aluminum alloy, for example, titanium or titanium alloy/aluminum or aluminum alloy/titanium or titanium alloy The metal laminated film of the three-layer structure which consists is collectively etched and it is a taper etching liquid.

[Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A No. Hei. No. Hei. No. Hei. No. Hei. [Patent Document 5] JP-A-2000-133635 (Patent Document 6) JP-A-2004-165289

That is, an object of the present invention is to provide an etching solution capable of collectively etching a titanium-aluminum-based metal laminated film and forming a tapered shape to solve the above problems.

In a concentrated review to solve the above problems, it was found that the combination is selected from a metal salt or an ammonium salt of hydrofluoric acid, a metal salt or an ammonium salt of hexafluoroantimonic acid, hexafluoroantimonic acid, a metal salt or ammonium of tetrafluoroboric acid and tetrafluoroboric acid. An etching solution comprising at least one fluorine compound and an oxidizing agent in a group consisting of a salt is suitable for collectively etching a metal laminated film containing a layer composed of titanium or an alloy containing titanium as a main component. Further, the present invention has been completed as a result of further investigation from a layer composed of aluminum or an alloy containing aluminum as a main component.

That is, the present invention relates to an etching liquid composition for collectively etching a metal laminated film (having a layer composed of titanium or an alloy containing titanium as a main component, and aluminum or aluminum as a main component). An etching liquid composition of a layer composed of an alloy; the etching liquid composition comprising: a metal salt or an ammonium salt selected from hydrofluoric acid, a metal salt or an ammonium salt of hexafluoroantimonic acid or hexafluoroantimonic acid, and PTFE At least one fluorine compound and an oxidizing agent in a group consisting of a metal salt or an ammonium salt of boric acid and tetrafluoroboric acid.

Further, the present invention relates to the aforementioned etching liquid composition, which is only used from a metal salt or an ammonium salt selected from hydrofluoric acid, a metal salt or an ammonium salt of hexafluoroantimonic acid or hexafluoroantimonic acid, tetrafluoroboric acid and tetrafluoroboric acid. At least one fluorine compound, an oxidizing agent, and water in the group consisting of a metal salt or an ammonium salt are used as a constituent raw material.

Furthermore, the present invention relates to the aforementioned etching liquid composition, wherein the oxidizing agent is selected from the group consisting of nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxydisulfate, perchloric acid, ammonium perchlorate, and perchloric acid. At least one of sodium, potassium perchlorate, periodic acid, sodium periodate, potassium periodate, methanesulfonic acid, hydrogen peroxide water, sulfuric acid and ethylenediamine sulfate.

Further, the present invention relates to the etching liquid composition, wherein the concentration of the fluoride is 0.01 to 5% by weight, and the concentration of the oxidizing agent is 0.1 to 50% by weight.

Further, the present invention relates to the aforementioned etching liquid composition, wherein the oxidizing agent is nitric acid or methanesulfonic acid.

Further, the present invention relates to the etching liquid composition, and further comprising a salt selected from the group consisting of ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxydisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, and At least one of potassium chlorate, periodic acid, sodium periodate, potassium periodate, hydrogen peroxide water, sulfuric acid and ethylenediamine sulfate is used as the oxidizing agent.

Moreover, the present invention relates to the etching liquid composition, and further contains at least one selected from the group consisting of amidosulfuric acid, acetic acid, and hydrochloric acid.

Moreover, the present invention relates to the etching liquid composition described above, wherein the base substrate is a glass substrate for a liquid crystal display.

Further, the present invention relates to the etching liquid composition, wherein the base substrate is a tantalum substrate or a compound semiconductor substrate for a semiconductor device.

Further, the present invention relates to the etching liquid composition for forming a metal laminated film (a layer composed of an alloy containing titanium or titanium as a main component, and an alloy containing aluminum or aluminum as a main component). The layer is etched to control the taper angle after etching to a range of 30 to 90 degrees.

Moreover, the present invention relates to the etching liquid composition, and is capable of controlling the taper angle in the range of 30 to 85 degrees.

As described above, the etching liquid composition of the present invention contains, as a constituent raw material, a metal salt or an ammonium salt selected from hydrofluoric acid, a metal salt or an ammonium salt of hexafluoroantimonic acid or hexafluoroantimonic acid, tetrafluoroboric acid and four At least one fluorine compound and an oxidizing agent in the group consisting of a metal salt or an ammonium salt of fluoroboric acid. The etching liquid composition of the present invention is configured by etching a metal laminated film (a layer composed of an alloy containing titanium or titanium as a main component, and an alloy containing aluminum or aluminum as a main component). In the case of layer), the etching rate can be made Ti>Al, whereby even a metal laminated film of a three-layer structure composed of, for example, titanium or titanium alloy/aluminum or aluminum alloy/titanium or titanium alloy can be collectively etched Form a cone shape.

In the present invention, since hydrofluoric acid is used as the fluorine compound constituting the raw material, the glass substrate is damaged. Therefore, in the present invention, hydrofluoric acid is not used as a constituent raw material. The oxidizing agent can be appropriately selected or combined in accordance with a desired taper angle. For example, when the taper angle is controlled to be 40 degrees or less, nitric acid or methanesulfonic acid can be used; when the taper angle is controlled to be 50 degrees or more, an oxidizing agent such as peroxodisulfate can be used. Further, by combining nitric acid or methanesulfonic acid with other oxidizing agents, it is also possible to control the taper angle to a desired taper angle.

The etching liquid of the present invention can collectively etch a layer composed of an alloy containing titanium or titanium as a main component and an alloy containing aluminum or aluminum as a main component in such a manner as not to adversely affect the base substrate. Since the metal laminated film of the layer formed has a taper angle, the coverage of the gate electrode can be improved, and the manufacture of a high-quality product can be made, and the economy can be excellent. Moreover, the control of the taper angle can also be easily performed.

[Best Mode for Carrying Out the Invention]

The etching liquid composition of the present invention is composed of a fluorine compound, an oxidizing agent, and water.

The fluorine compound used in the etching liquid of the present invention is considered to be mainly etched by dissolving titanium oxide on the metal laminated film which has been oxidized by the oxidizing agent in the composition of the etching liquid. The fluorine compound used in the etching solution of the present invention is selected from the group consisting of a metal salt or an ammonium salt of hydrofluoric acid, a metal salt or an ammonium salt of hexafluoroantimonic acid or hexafluoroantimonic acid, a metal salt of tetrafluoroboric acid and tetrafluoroboric acid. Or at least one of the group consisting of ammonium salts. The fluorine compound is, for example, preferably ammonium fluoride, potassium fluoride, calcium fluoride, ammonium hydrogen fluoride, potassium hydrogen fluoride, sodium fluoride, magnesium fluoride, lithium fluoride, hexafluoroantimonic acid or ammonium hexafluoroantimonate. And sodium hexafluoroantimonate, potassium hexafluoroantimonate, tetrafluoroboric acid, ammonium tetrafluoroborate, sodium tetrafluoroborate, potassium tetrafluoroborate, etc., particularly preferably ammonium fluoride or ammonium hydrogen fluoride.

Further, the oxidizing agent used in the etching liquid of the present invention serves as an etching initiator by using titanium or a titanium alloy on the metal oxide film. The oxidizing agent used in the etching solution of the present invention is selected from the group consisting of nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxydisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, At least one of periodic acid, sodium periodate, potassium periodate, methanesulfonic acid, hydrogen peroxide water, sulfuric acid and ethylenediamine sulfate is preferred, wherein nitric acid, ammonium peroxodisulfate, methanesulfonate The acid is better.

It is also possible to use a nitrogen-containing organic compound sulfate other than ammonium sulfate or ethylenediamine sulfate, for example, piperazine, 1-(2-aminoethyl)piperazine, 1-amino-methylpiperazine, etc. The sulfate is used as an oxidizing agent, but in terms of availability, ammonium sulfate or ethylenediamine sulfate is preferred.

Particularly preferred is nitric acid or methanesulfonic acid because the cone angle can be lowered even at a low concentration, for example, 40 degrees or less. Although nitric acid or an oxidizing agent other than methanesulfonic acid has a poor effect of lowering the taper angle, it is preferable because the damage to the photoresist is small and the amount of side etching can be controlled. The etching solution containing the fluorine compound and nitric acid or methanesulfonic acid can control the taper angle to 40 degrees or less, and further add an oxidizing agent selected from nitric acid and methanesulfonic acid, or an amine sulfuric acid or acetic acid. At least one of hydrochloric acid can control the taper angle between 30 and 90 degrees, preferably 30 degrees or more and less than 90 degrees, preferably 30 to 85 degrees, and preferably 30 to 80 degrees. .

In a preferred combination of the etching liquid composition of the present invention, in addition to ammonium fluoride and nitric acid, ammonium fluoride and methanesulfonic acid, when two or more kinds of oxidizing agents are used in combination, ammonium fluoride and nitric acid may be mentioned. Chloric acid, ammonium fluoride and nitric acid and sulfuric acid, ammonium fluoride and nitric acid, perchloric acid and methanesulfonic acid, ammonium fluoride and nitric acid, perchloric acid and sulfuric acid.

Further, in order to improve the wettability with the substrate, a commonly used surfactant or organic solvent may be added to the etching solution.

The etching solution of the present invention is suitable for etching a metal laminated film comprising a layer composed of titanium or an alloy containing titanium as a main component, and an alloy composed of aluminum or an alloy containing aluminum as a main component. a layer, for example, a metal laminated film made of titanium/aluminum, aluminum/titanium, titanium/aluminum/titanium, on an insulating substrate made of a glass substrate or the like, and on a germanium substrate or a compound semiconductor substrate, for example, by The concentration of the fluorine compound in the etching solution is 0.01 to 5% by weight, preferably 0.1 to 1% by weight, and the concentration of the oxidizing agent is 0.1 to 50% by weight, preferably 0.5 to 10% by weight.

When the concentration of the fluorine compound is 5% by weight or less, the base glass is not damaged; and the metal laminated film (the layer composed of an alloy containing titanium or titanium as a main component, and aluminum or aluminum) can be suppressed. When the amount of side etching of the layer composed of the alloy of the main component is 0.01% by weight or more, the etching unevenness of the alloy of titanium or titanium can be reduced, and the shape after etching is good. When the content of the oxidizing agent is 50% by weight or less, it is possible to suppress a metal laminated film (a layer composed of an alloy containing titanium or titanium as a main component, and a layer composed of aluminum or an alloy containing aluminum as a main component) The amount of side etching is not harmful to the photoresist. When the content is 0.1% by weight or more, the etching rate to titanium or titanium alloy is faster and more efficient.

Further, the taper angle is appropriately controlled, and particularly, in order to make it 30 to 90 degrees, it can be carried out by using nitric acid or methanesulfonic acid alone or in combination with nitric acid or methanesulfonic acid and other oxidizing agents as appropriate. In this case, the nitric acid or methanesulfonic acid is preferably 0.1 to 30% by weight, particularly preferably 0.5 to 15% by weight, and the other oxidizing agent is preferably 0.1 to 20% by weight, particularly preferably 0.5 to 15% by weight.

In particular, in order to make the taper angle 40 degrees or less, it is preferable to use nitric acid or methanesulfonic acid.

Further, in the case where at least one selected from the group consisting of aminosulfonic acid, acetic acid, and hydrochloric acid is contained, the concentration thereof is preferably 0.01 to 10% by weight, particularly preferably 0.5 to 5% by weight.

In the etching liquid of the present invention, the base substrate of the metal laminated film to be etched is not particularly limited. When a titanium or aluminum metal laminated film is used for a liquid crystal display, a glass substrate is preferable, and when used in a semiconductor device, a germanium substrate is used. It is preferably a compound semiconductor substrate.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the invention is not limited thereto.

[Examples] Example 1~26

As shown in Figure 1, the titanium (700) is prepared by sputtering. ) / aluminum (2500 ) / Titanium (200 A substrate formed by forming a film on a glass substrate (1).

Next, the glass/titanium/aluminum/titanium metal laminated film was patterned using a photoresist (4), and then immersed in the etching liquids of Examples 1 to 26 shown in Table 1 (containing the components described in the respective examples). In the aqueous solution) (etching temperature 30 ° C). Subsequently, it was washed with ultrapure water, and after drying with nitrogen, the shape of the substrate was observed by an electron microscope. The results are shown in Table 1.

Comparative example 1~2

The glass/titanium/aluminum/titanium which has been formed by the sputtering method on the glass substrate used in the examples was immersed in the etching liquid composed of the respective components of Comparative Examples 1 and 2 of Table 1, and was carried out. The example is processed in the same manner. The results are shown in Table 1.

As is clear from Table 1, by etching using the etching liquid of the present invention, it is possible to collectively etch a titanium/aluminum/titanium laminated film formed by a sputtering method in a short time. Further, it is known that the desired taper angle can be controlled by appropriately selecting the oxidizing agent.

Comparative example 3~5

In order to add the etching liquid of the test patent document 5, the etching liquid (aqueous solution) of the following composition is prepared.

Comparative Example 3: Hydrofluoric acid (0.3% by weight) + periodic acid (0.5% by weight) + sulfuric acid (0.54% by weight) Comparative Example 4: Hydrofluoric acid (15% by weight) + periodic acid (1.5% by weight) + Sulfuric acid (5.4% by weight) Comparative Example 5: hydrofluoric acid (0.03 wt%) + periodic acid (0.05 wt%) + sulfuric acid (0.06 wt%)

Next, an Al plate (Al alone system: 20 × 10 × 0.1 mm), a Ti plate (Ti alone system: 20 × 10 × 0.1 mm), and an Al/Ti contact substrate (Al-Ti) obtained by connecting these two sheets were prepared. Contact system), and glass plate (20 × 18 × 0.1 mm). Each of the four types of substrates was immersed in the etching liquids of Comparative Example 3 and Comparative Example 4, and the etching rate (etching temperature: 30 ° C) was measured. The results are shown in Table 2. Further, Ag/AgCl was used as a reference electrode, and a platinum plate was used as a counter electrode. The electrode potentials of titanium and aluminum in the etching liquid of Comparative Example 3 were measured to determine the potential difference between titanium and aluminum.

Next, the aluminum (1800) is prepared in order on the glass substrate by the ammonium splash method. ) and titanium (900 The film-formed substrate (glass/Al/Ti substrate) was immersed in the etching liquid of Comparative Examples 3 to 5, and it was confirmed that the time until the metal film was dissolved and the glass material was observed (JET: Appropriate etching (just Etching) time). Further, the etching shape of the laminated film after immersion of 1.25 times of each JET was observed. The results are shown in Table 3.

In the etching liquid of Comparative Example 3, the etching rate of the etching liquid described in Patent Document 5 was found to be Ti<<Al according to the comparison of the etching rates of the respective metal plates. When the film was laminated with different metals, the etching rate of the single metal and the contact system may differ depending on the battery effect. However, in the etching liquid of Comparative Example 3, it is considered that the etching rates of the individual systems and the contact systems are not significantly different. Even in the laminated substrate, the etching rate is Ti<<Al. Although it was confirmed that the potential difference obtained by measuring the electrode potentials of Al and Ti was within 400 mV, since the Ti of the upper layer was dissolved, the etching rate of the lower layer of Al was high, and the etching shape was not tapered but was substantially vertical. Moreover, the etching liquid of Comparative Example 4 severely eroded the glass substrate, and the glass/Al/Ti laminated substrate eroded the base glass even in a short time etching; the etching rate of the etching liquid of Comparative Example 5 was slow. None of them is practical.

[Possibility of industrial use]

In the process of an electronic device such as a semiconductor device or a liquid crystal display, the etching solution of the present invention can be used as an etching solution for forming a metal laminated film at the time of forming a wiring or an electrode.

(1). . . glass substrate

(2). . . Titanium or titanium alloy film

(3). . . Aluminum or aluminum alloy film

(4). . . Photoresist

(a). . . The gate electrode after etching by the etching solution of the present invention (substantially the same tapered shape and tapered shape below 40 degrees)

(b). . . a source or a drain electrode (90 degree taper angle) etched by the etching solution of the present invention

Fig. 1 is a wiring process for forming a metal laminated film formed on an insulating substrate; the metal laminated film contains a layer composed of titanium or an alloy containing titanium as a main component, and is made of aluminum or aluminum. A layer composed of an alloy of main components.

Claims (9)

An etching liquid composition for collectively etching a metal laminated film containing a layer composed of titanium or an alloy containing titanium as a main component, and an alloy containing aluminum or aluminum as a main component In the layer to be formed, the etching liquid composition is formed by using only a fluorine compound, an oxidizing agent, and water as a constituent material selected from the group consisting of a metal salt or an ammonium salt of hydrofluoric acid, hexafluoroantimonic acid, and hexafluoroantimonic acid. At least one selected from the group consisting of a metal salt or an ammonium salt, a tetrafluoroboric acid, and a metal salt or an ammonium salt of tetrafluoroboric acid selected from the group consisting of nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, and Potassium oxydisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodate, sodium periodate, potassium periodate, methanesulfonic acid, hydrogen peroxide, sulfuric acid and sulfuric acid At least one of the amines. The etching liquid composition of claim 1, wherein the concentration of the fluoride is 0.01 to 5% by weight, and the concentration of the oxidizing agent is 0.1 to 50% by weight. An etchant composition according to claim 1 or 2, wherein the oxidant is nitric acid or methanesulfonic acid. The etchant composition of claim 3, wherein the oxidizing agent further comprises a salt selected from the group consisting of ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxydisulfate, perchloric acid, ammonium perchlorate, and perchloric acid. At least one of sodium, potassium perchlorate, periodic acid, sodium periodate, potassium periodate, hydrogen peroxide water, sulfuric acid and ethylenediamine sulfate. Such as the etchant composition of claim 1 of the patent scope, which further includes There is at least one selected from the group consisting of aminosulfonic acid, acetic acid and hydrochloric acid. The etching liquid composition according to claim 1 or 2, wherein the base substrate is a glass substrate for a liquid crystal display. The etching liquid composition according to claim 1 or 2, wherein the base substrate is a tantalum substrate or a compound semiconductor substrate for a semiconductor device. An etching liquid composition according to claim 1 or 2, which is used for etching a metal laminated film, and capable of controlling a taper angle after etching to a range of 30 to 90 degrees, wherein the metal laminated film contains A layer composed of titanium or an alloy containing titanium as a main component, and a layer composed of aluminum or an alloy containing aluminum as a main component. For example, the etchant composition of claim 8 is capable of controlling the taper angle in the range of 30 to 85 degrees.