JP7105084B2 - Etchant composition - Google Patents

Description

The present invention relates to an etchant composition.

When forming a metal wiring such as copper on an insulating film made of an organic material or an inorganic material, the adhesion between the insulating film and the metal wiring may be insufficient due to elution of impurities in the insulating film. In order to compensate for this adhesion, a titanium layer is first placed on the insulating film, and a metal wiring such as copper is formed thereon. In order to remove the titanium layer other than the metal wiring portion, there is a demand for an etching composition that removes only the titanium layer without damaging the metal wiring layer such as copper.

US Pat. No. 5,300,001 discloses an etching composition for titanium comprising hydrofluoric acid. However, pyrazine is not disclosed, and a layer composed only of titanium on the silicide layer is etched, and although it is described that damage to the silicide layer is suppressed, the titanium layer is not disclosed in relation to the metal wiring. It is unclear whether only

US Pat. No. 6,200,009 discloses copper etching compositions containing piperazine. However, neither hydrofluoric acid nor pyrazine are disclosed and do not etch titanium layers.

Patent Document 3 discloses an etching composition for silicon containing hydrofluoric acid and a nitrogen-containing heteroaromatic compound, and describes pyrazine as the nitrogen-containing heteroaromatic compound. However, it does not etch the titanium layer.

JP 2016-127065 JP 2014-224303 JP 2016-162983

The present invention provides an etching composition that removes only the titanium layer without damaging metal interconnects such as copper. Furthermore, in a laminated body in which a titanium layer is laminated on an insulating film and a metal wiring such as copper is arranged on the titanium layer, side etching is performed under the metal wiring such as copper while removing an unnecessary titanium layer. A controllable etching composition is provided.

As a result of intensive studies, the present inventors have found an etchant composition containing (A) hydrofluoric acid and/or a salt thereof, (B) an organic acid and/or an inorganic acid, and (C) pyrazine and/or a derivative thereof. The present inventors have found that the material can remove only the titanium layer without damaging the metal wiring layer such as copper, and can suppress the side etching of the titanium layer, thereby completing the present invention.

That is, the present invention relates to an etchant composition containing (A) hydrofluoric acid and/or a salt thereof, (B) an organic acid and/or an inorganic acid, and (C) pyrazine and/or a derivative thereof.

(A) The salt of hydrofluoric acid is preferably at least one selected from the group consisting of ammonium fluoride, potassium fluoride, and sodium fluoride.

(B) The organic acid is preferably at least one selected from the group consisting of citric acid, acetic acid and oxalic acid.

(B) The inorganic acid is preferably at least one selected from the group consisting of perchloric acid, phosphoric acid, sulfuric acid, nitric acid and hydrochloric acid.

(C) the pyrazine derivative is from the group consisting of 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-methoxypyrazine, 2-aminopyrazine, pyrazinecarboxylic acid, and 2-chloropyrazine; At least one selected is preferred.

Preferably, the etching composition is for etching a titanium layer.

Since the etchant composition of the present invention contains pyrazine and/or its derivatives, it can remove only the titanium layer without damaging the metal wiring layer such as copper, and can suppress side etching of the titanium layer.

<<etching liquid composition>>
The present invention relates to an etchant composition containing (A) hydrofluoric acid and/or its salts, (B) organic and/or inorganic acids, and (C) pyrazine and/or its derivatives.

<(A) Hydrofluoric acid and/or its salt>
Hydrofluoric acid and/or its salts are sources of hydrogen fluoride that reduce the corrosion potential of the titanium layer and promote etching. Salts of hydrofluoric acid include, for example, water-soluble salts of hydrofluoric acid, and specific examples thereof include ammonium fluoride, potassium fluoride, sodium fluoride and the like. Among these, ammonium fluoride and potassium fluoride are preferable from the viewpoint of the stability of raw materials and the characteristics of the industrial field in which they are used. These hydrofluoric acids and/or salts thereof may be used alone, or two or more of them may be used in combination.

The amount of hydrofluoric acid and/or its salt is preferably such that the amount of hydrogen fluoride in the etching solution composition is 0.001 to 5.0% by weight, and 0.003 to 3.0% by weight. is more preferable. If the hydrogen fluoride content in the etchant composition is less than 0.001% by weight, the etching rate of Ti will be low, and substrate processing may take a long time. can be.

<(B) Organic Acid and/or Inorganic Acid>
The organic acid and/or inorganic acid are blended to acidify the etchant composition. Pyrazine and/or its derivatives are weakly basic, but the etchant composition must be acidic in order to achieve etching of the titanium layer by hydrofluoric acid and/or its salts. /or Incorporation of an inorganic acid is required.

Examples of inorganic acids include perchloric acid, phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid. Among these, perchloric acid and phosphoric acid are preferable from the viewpoint of suppressing deposition of dissolved Ti ions. These inorganic acids may be used alone or in combination of two or more.

Examples of organic acids include carboxylic acids such as citric acid, acetic acid, oxalic acid, formic acid, butanoic acid, gluconic acid, glycolic acid, malonic acid and pentanoic acid, and sulfonic acids such as methanesulfonic acid and benzenesulfonic acid. Among these, citric acid, acetic acid, and oxalic acid are preferable from the viewpoint of suppressing deposition of dissolved Ti ions. These organic acids may be used alone or in combination of two or more. Also, the organic acid and the inorganic acid may be used in combination.

The content of the organic acid and/or inorganic acid is preferably 0.05 to 15% by weight, more preferably 0.1 to 10.0% by weight, in the etching liquid composition. If the amount is less than 0.05% by weight or more than 15% by weight, the etching rate of the titanium layer may decrease.

The pH of the etchant composition is preferably 0-4.5, more preferably 0-3. If the pH exceeds 4.5, the etching rate of the titanium layer may decrease.

<(C) Pyrazine and/or its derivative>
By adding pyrazine and/or a derivative thereof, the titanium layer can be selectively removed and side etching of the titanium layer can be suppressed.

式（Ｉ）中、Ｒは特に限定されないが、例えばアルキル基、アルコキシ基、ハロゲン原子、カルボキシル基、アミノ基、アセチル基などが挙げられる。アルキル基は炭素数１～２が好ましい。アルコキシ基は炭素数１～２が好ましい。ハロゲン原子としてはＣｌ、Ｂｒ、Ｉが挙げられる。ｎは１～４である。ｎが２以上のとき、Ｒは同一であってもよく、異なっていてもよい。 Derivatives of pyrazine include compounds of formula (I) below.
Formula (I):

In formula (I), R is not particularly limited, but examples thereof include an alkyl group, an alkoxy group, a halogen atom, a carboxyl group, an amino group and an acetyl group. The alkyl group preferably has 1 to 2 carbon atoms. The alkoxy group preferably has 1 to 2 carbon atoms. Halogen atoms include Cl, Br and I. n is 1-4. When n is 2 or more, R may be the same or different.

Derivatives of pyrazine include 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-methoxypyrazine, 2-aminopyrazine, pyrazinecarboxylic acid, 2-chloropyrazine. Among these, 2-methylpyrazine, 2-aminopyrazine, and pyrazinecarboxylic acid are preferred from the viewpoint of stability. These pyrazines and/or derivatives thereof may be used alone or in combination of two or more.

The content of pyrazine and/or its derivative is preferably 0.005 to 2.0% by weight, more preferably 0.01 to 1.0% by weight, in the etching solution composition. If the amount is less than 0.005% by weight, the effect of suppressing side etching may not be obtained, and if it exceeds 2.0% by weight, the etching rate of the titanium layer may decrease.

The etchant composition of the present invention is an aqueous solution. The water is preferably water from which ionic substances and impurities have been removed, such as ion-exchanged water, pure water, and ultrapure water. The amount of water to be blended is the remainder excluding the components (A) to (C) described above and other components described later, and is preferably 60 to 99.5% by weight, more preferably 90 to 99.5% by weight. .

<Other ingredients>
The etching solution of the present invention may optionally contain other components in addition to (A) hydrofluoric acid and/or salts thereof, (B) organic acids and/or inorganic acids, and (C) pyrazine and/or derivatives thereof. may contain. Other components include, for example, surfactants, antifoaming agents, solvents, pH adjusters, oxidizing agents, anticorrosives and the like.

By adding a surfactant to the etchant composition, the wettability can be improved and uneven etching can be prevented. The surfactant is not particularly limited, but for example, nonionic surfactants such as polyoxyethylene alkyl ethers, surfactants containing fluorine in the lipophilic group, amphoteric surfactants such as betaine, fatty acid salts, Examples include anionic surfactants such as alkyl sulfates and alkyl phosphate salts, glycols, glycol ethers and their condensates. These surfactants may be used alone or in combination of two or more. When the etching solution composition contains a surfactant, its content is not particularly limited, but it is preferably 0.001 to 30% by weight in the etching solution composition.

By including an antifoaming agent in the etching liquid composition, antifoaming properties can be improved. Examples of antifoaming agents include, but are not particularly limited to, lower alcohols, polyoxyalkylene alkyl ethers, and the like. These antifoaming agents may be used alone or in combination of two or more. When the etchant composition contains an antifoaming agent, the content is not particularly limited, but is preferably 0.00001 to 0.1% by weight.

Although the etchant composition is an aqueous solution as described above, it may contain an additional solvent as long as it does not interfere with the ionization of titanium. Additional solvents include alcohols such as ethanol and methanol, ethers such as diethylene glycol monobutyl ether and diethylene glycol diethyl ether, and glycols such as ethylene glycol and diethylene glycol. These solvents may be used alone or in combination of two or more. When an additional solvent is contained, its content is not particularly limited, but is preferably 0.01 to 45% by weight, more preferably 1 to 30% by weight, based on the etching liquid composition.

Examples of pH adjusters include, but are not limited to, ammonium, monoethanolamine, diethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethanolisopropanolamine, diethanolisopropanolamine, ethanoldiisopropanolamine, and tetramethyl hydroxide. Examples include ammonium, amines such as hydroxylamine, and carboxylic acids such as glycolic acid. These pH adjusters may be used alone, or two or more of them may be used in combination. When the etching solution composition contains a pH adjuster, its content is not particularly limited, but it is preferably 0.001 to 30% by weight in the etching solution composition.

The etchant composition of the present invention can be prepared by mixing each component described above by a conventional method. The mixing order of each component is not particularly limited, and they may be mixed together.

<Application>
The etching composition of the present invention is used to etch the titanium layer other than the metal wiring portion from a laminate in which an insulating film, a titanium layer, and a metal wiring are laminated in this order on a substrate made of a semiconductor, glass, resin, or the like. It is preferably used for An electronic circuit layer such as TFT wiring may be further laminated between the substrate and the insulating film. Materials constituting the insulating film include inorganic materials such as silica and silicon nitride, and organic materials such as polyimide and acryl. The constituent metals of the metal wiring include copper and/or copper alloys. These constituent metals of the metal wiring may be used alone or in combination of two or more.

The titanium layer is made of metal titanium (Ti), titanium nitride (TiN), a titanium alloy, or the like. Examples of titanium alloys include alloys of titanium and aluminum, vanadium, and the like. Although the etching composition of the present invention can etch a titanium layer having a thickness of 800 nm or less, the thickness of the titanium layer is preferably 400 nm or less. The lower limit of the film thickness is not particularly limited.

<<etching method>>
The titanium layer can be etched by contacting the titanium layer with the etchant composition of the present invention. The etching conditions are not particularly limited, but the etching temperature is preferably 20 to 50° C., and the etching time is preferably 1 to 30 minutes. By using the etchant composition of the present invention, side etching of the titanium layer can be suppressed during wet etching.

The method of bringing the etching solution composition into contact with the titanium layer is not particularly limited, but examples thereof include methods such as a shower method, an immersion method, a rocking immersion method, and a US immersion method. The etching conditions may be automatically controlled by measuring the titanium ion concentration, oxidation-reduction potential, specific gravity, acid concentration, etc. in the etching solution composition.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

(Examples 1 to 18, Comparative Examples 1 to 8)
Each component was mixed at the weight ratio (the balance being water) shown in Table 1 below to obtain an etchant composition. The etchant composition of each example or each comparative example was brought into contact with the titanium layer of the substrate to etch the titanium layer. As a substrate, a substrate composed of Cu metal wiring (thickness 5 μm)/titanium layer (thickness 300 nm)/SiO ₂ silicon was used. The etching rate of the titanium layer was measured, and the etching process was performed at 30° C. for three times and six times the just etching time calculated from the etching rate. After the etching treatment, the substrate was cleaved and the cross section was confirmed with a scanning electron microscope. The side etching amount after performing the etching process for 3 times the time of the just etching time, and the side etching amount after performing the etching process for 6 times the time did not increase was evaluated as ○, and increased. Those that did were evaluated as x.

Since the etchant compositions of Comparative Examples 1 to 8 did not contain pyrazine or derivatives thereof, side etching occurred. Side etching was suppressed in the etchant compositions of Examples 1 to 18.

Claims (5)

(A) hydrofluoric acid and/or salts thereof, (B) organic and/or inorganic acids, and (C) pyrazine and/or derivatives thereof ,
An etchant composition for use in etching titanium layers . 2. The etching solution composition according to claim 1, wherein (A) the salt of hydrofluoric acid is at least one selected from the group consisting of ammonium fluoride, potassium fluoride, and sodium fluoride. 3. The etchant composition according to claim 1, wherein (B) the organic acid is at least one selected from the group consisting of citric acid, acetic acid, and oxalic acid. 3. The etching solution composition according to claim 1, wherein (B) the inorganic acid is at least one selected from the group consisting of perchloric acid, phosphoric acid, sulfuric acid, nitric acid and hydrochloric acid. (C) the derivative of pyrazine is from the group consisting of 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-methoxypyrazine, 2-aminopyrazine, pyrazinecarboxylic acid, and 2-chloropyrazine; The etchant composition according to any one of claims 1 to 4, which is at least one selected.