TW201432092A - Method of forming etching solution, replenishment thereof and copper wiring - Google Patents

Abstract

Disclosed is a method of forming etching solution, replenishment thereof and copper wiring. The means provided by the instant disclosure is that, the etching solution is for etching copper, which comprises acid, oxidized metal ions and solution of compound A, and is characterized in: the compound A comprises at least one sulfur-containing functional group and amino group selected from the group including thiol group, sulfide group and disulfide group (wherein, sulfide group and disulfide group are formed by bounding a sulfur atom and an atom different from the sulfur atom with a single bond without forming the π conjugated group). The method of forming the copper wiring (1) is to etch the copper layer where is not coated by the etching protection layer (2), which is characterized in using the etching solution provided by the instant disclosure for etching.

Description

Etching liquid, replenishing liquid, and copper wiring forming method

The present invention relates to a copper etching solution, a replenishing liquid thereof, and a method of forming a copper wiring.

In the production of a printed wiring board, when a copper wiring pattern is formed by photolithography, a ferric chloride-based etching liquid, a copper chloride-based etching liquid, an alkaline etching liquid, or the like is used as an etching liquid. When such an etching liquid is used, the copper under the protective layer may be dissolved from the side surface of the wiring pattern, which is called side etching. That is, a portion (ie, a copper wiring portion) which is originally intended to be not removed by etching by an etching resist is removed by the etching liquid, so that the width is tapered along the bottom to the top of the copper wiring. phenomenon. Especially when the copper wiring pattern is fine, it is necessary to reduce the above side etching as much as possible. In order to suppress this side etching, an etching solution for azole compound has been proposed (see, for example, Patent Documents 1 and 2 below).

Advanced technical literature

Patent Document 1: Japanese Patent Laid-Open No. Hei 6-57453

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-330572

However, in the etching liquid described in Patent Document 1, the side etching suppression effect is still insufficient.

In addition, the etching liquid described in Patent Document 2 can suppress the side etching. However, when the etching liquid described in Patent Document 2 is used in a general method, the side surface of the copper wiring has a gap. When a gap is formed in the side surface of the copper wiring, the linearity of the copper wiring is lowered, and the copper wiring width is optically checked from above the printed wiring board, which may cause misunderstanding. Further, when the linearity is extremely deteriorated, the impedance characteristics of the printed wiring board are lowered.

As described above, in the conventional etching liquid, it is difficult to suppress side etching without impairing the linearity of the copper wiring.

The present invention has been made in view of the above circumstances, and provides a method for forming an etching liquid, a replenishing liquid, and a copper wiring which can suppress side etching without impairing the linearity of the copper wiring.

The etching liquid of the present invention is an etching solution for copper, which is an aqueous solution containing an acid, an oxidizing metal ion, and a compound A, wherein the compound A has a thiol group, a thioether group, and a disulfide selected from the group in the molecule. At least one sulfur-containing functional group in the group consisting of an ether group (wherein a thioether group and a disulfide-based sulfur atom and a hetero atom to which it is bonded is bonded by a single bond and which does not form a π-conjugated group) Amine.

The replenishing liquid of the present invention is a replenishing liquid added to the etching liquid when the etching liquid of the present invention is continuously or repeatedly used, and is an aqueous solution containing an acid and a compound A, wherein the compound A is in a molecule. And having a thiol group, a thioether group, and a disulfide group (wherein the thioether group and the disulfide group-based sulfur atom and a hetero atom attached thereto are bonded by a single bond and do not form a π-conjugated group) At least one sulfur-containing functional group and an amine group in the group formed.

The method for forming a copper wiring according to the present invention is a method of forming a copper wiring for etching a portion of a copper layer which is not covered with an etching protective layer, and is characterized by etching using the etching liquid of the present invention.

The "copper" of the present invention described above may be composed of copper or may be composed of a copper alloy. In addition, "copper" as used herein means copper or a copper alloy.

According to the present invention, it is possible to provide a method for forming an etching liquid, a replenishing liquid, and a copper wiring which can suppress side etching without impairing the linearity of the copper wiring.

1‧‧‧Bronze wiring

2‧‧‧ etching protection layer

3‧‧‧Protective membrane

Fig. 1 is a partial cross-sectional view showing an example of a copper wiring which is etched by the etching liquid of the present invention.

The etching solution of the present invention is an aqueous solution containing an acid, an oxidizing metal ion, and a compound A, wherein the compound A has a molecule selected from the group consisting of a thiol group, a thioether group, and a disulfide group. At least one sulfur-containing functional group and an amine group in the group consisting of a thioether group and a disulfide-based sulfur atom and a hetero atom to which it is bonded are bonded by a single bond and not forming a π-conjugated group.

Fig. 1 is a partial cross-sectional view showing an example of a copper wiring which is etched by the etching liquid of the present invention. An etching protection layer 2 is formed on the copper wiring 1. Further, a protective film 3 is formed on the side surface of the copper wiring 1 directly under the end portion of the etching protection layer 2. The protective film 3 is generally considered to be mainly formed by forming a monovalent copper ion and a salt thereof with the compound A in the etching liquid as the etching progresses. Since the etching liquid of the present invention contains the above-mentioned compound A, it is considered that a uniform protective film 3 is formed. As a result, since the gap of the copper wiring 1 is reduced, it is considered that the side etching is suppressed without impairing the linearity of the copper wiring 1. Therefore, the etching liquid of the present invention can improve the yield of the manufacturing steps of the printed wiring board. Further, the protective film 3 can be easily removed by treatment with a removal liquid after the etching treatment. The removal liquid is preferably a mixed solution of hydrogen peroxide and sulfuric acid, an acidic liquid such as hydrochloric acid, or an organic solvent such as dipropylene glycol monomethyl ether.

However, when the copper wiring is formed by the etching liquid of the above-mentioned Patent Document 2, it is considered that a protective film which is less uneven than that after the etching of the etching liquid of the present invention is formed thickly, and it is estimated that the linearity of the copper wiring is impaired.

In addition, when the etching liquid of the above-mentioned Patent Document 2 is used, since the etching rate is slow, the processing speed is lowered and the productivity is lowered, and the etching liquid of the present invention can be maintained and chlorinated with a general ferric chloride-based etching solution. Since the copper-based etching liquid has the same etching rate, the productivity can be improved without lowering the productivity.

The acid used in the etching solution of the present invention can be suitably selected from inorganic acids and organic acids. Examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and the like. Examples of the organic acid include formic acid, acetic acid, oxalic acid, maleic acid, benzoic acid, and glycolic acid. Among the above acids, hydrochloric acid is preferred from the viewpoint of stability of etching rate and solubility stability of copper.

The concentration of the above acid is preferably from 7 to 180 g/L, more preferably from 10 to 110 g/L. When the acid concentration is 7 g/L or more, since the etching rate is increased, copper can be quickly etched. Moreover, when the acid concentration is 180 g/L or less, the dissolution stability of copper can be maintained and the deterioration of the working environment can be suppressed.

The oxidizing metal ion used in the etching liquid of the present invention may be a metal ion which can oxidize metal copper, and examples thereof include a divalent copper ion or a ferric ion. From the viewpoint of suppressing side etching and stability of etching speed, it is preferred to use a divalent copper ion for the oxidizing metal ion.

The oxidizing metal ion may be contained in the etching solution by blending an oxidizing metal ion source. For example, when a divalent copper ion source is used as the oxidizing metal ion source, specific examples thereof include copper chloride, copper sulfate, copper bromide, a copper salt of an organic acid, and copper hydroxide. For example, when a ferric ion source is used as the oxidizing metal ion source, specific examples thereof include iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, and an iron salt of an organic acid.

The concentration of the oxidizing metal ion is preferably from 10 to 250 g/L, more preferably from 10 to 200 g/L, still more preferably from 15 to 160 g/L, most preferably from 30 to 160 g/L. When the concentration of the oxidizing metal ion is 10 g/L or more, since the etching rate is increased, copper can be quickly etched. Further, when the concentration of the oxidizing metal ion is 250 g/L or less, the dissolution stability of copper can be maintained.

In order to suppress side etching without impairing the linearity of the copper wiring, the etching liquid of the present invention is formulated to have at least one selected from the group consisting of a thiol group, a thioether group, and a disulfide group in the molecule. Compound A with a sulfur functional group and an amine group. Here, the thioether group and the disulfide group of the present invention mean that a sulfur atom and a hetero atom to which it is bonded are bonded by a single bond, and a π-conjugated group is not formed.

The compound A is not particularly limited as long as it has at least one sulfur-containing functional group and an amine group selected from the group consisting of a thiol group, a thioether group and a disulfide group in the molecule, but is preferably a Selected from an aliphatic compound. It is considered that an aliphatic compound has a higher solubility in an aqueous solution than an aromatic compound, so that a uniform protective film can be easily formed.

Specific examples of the above compound A include 2-amine ethanethiol, 2-(dimethylamino)ethanethiol, 2-(diethylamino)ethanethiol, and 2-(diisopropylamino)ethanethiol. a compound having a thiol group and an amine group; 2,2'-thiobis(ethylamine), 2-(ethylthio)ethylamine, tetramethylammoniumsulfide monosulfide, etc. having a thioether group and an amine group A compound having a disulfide group and an amine group such as cystamine or bis(2-dimethylaminoethyl) disulfide. The above compound A may also be in the form of a salt such as a hydrochloride or a sulfate. Further, the above compound A may be used in combination of two or more kinds. Among them, from the viewpoint of improving the linearity of the copper wiring and effectively suppressing the side etching, a compound having a thiol group and an amine group is preferable.

The concentration of the above compound A is preferably from 0.005 to 10 g/L, more preferably from 0.01 to 5 g/L. If it is within this range, the linearity of the copper wiring can be improved and the side etching can be effectively suppressed.

In order to improve the linearity of the copper wiring and effectively suppress the side etching, the etching liquid of the present invention can also be formulated. Alicyclic amine compounds. When the etchant of the present invention is formulated with an alicyclic amine compound, the concentration of the alicyclic amine compound in the etching solution is preferably from 0.01 to 10 g/L, more preferably from 0.02 to 5 g/L, based on the same viewpoint as above.

The alicyclic amine compound is preferably an alicyclic amine compound having a molecular weight of about 43 to 500, more preferably a pyrrole pyridine compound, from the viewpoint of improving the linearity of the copper wiring and effectively suppressing side etching. One or more alicyclic amine compounds of a piperidine compound and a piperazine compound.

Among them, in order to effectively suppress side etching and further improve the linearity of the copper wiring, it is preferred to use a piperazine compound such as piperazine, and it is more preferred to use a piperazine compound represented by the following formula (I).

[wherein R ¹ and R ² each independently represent hydrogen or a hydrocarbon-derived group having 1 to 6 carbon atoms. Here, at least one of R ¹ and R ² represents a hydrocarbon-derived group having 1 to 6 carbon atoms.

Here, the hydrocarbon-derived group means a hydrocarbon group composed of carbon and hydrogen, and a part of carbon or hydrogen may be replaced by another atom or a substituent. The hydrocarbon-derived group can be exemplified by, for example, a methyl group, an ethyl group, a propyl group, a butyl group, an amine methyl group, an amine ethyl group, an amine propyl group, a dimethylamine methyl group, a dimethylamine ethyl group, a dimethylaminopropyl group, or a hydroxyl group. Base, hydroxyethyl, hydroxypropyl, propenyl, ethylidene, phenyl, hydroxyethoxymethyl, hydroxyethoxyethyl, hydroxyethoxypropyl, and the like.

Specific examples of the piperazine compound represented by the above formula (I) include N-methylpiperazine, N-ethylpiperazine, N,N-dimethylpiperazine, N-propenylpiperazine, and N-iso Butyl piperazine, N-hydroxyethoxyethylpiperazine, N-phenylpiperazine, 1,4-bis(3-aminopropyl)piperazine, 1-(2-dimethylaminoethyl)- 4-methylpiperazine, N-(2-aminoethyl)piperazine, and the like. In the above formula (I), at least one of R ¹ and R ² is preferably a piperazine compound having an amine group, from the viewpoint of suppressing side etching and improving the linearity of the copper wiring. The piperazine compound like this can be exemplified by 1,4-bis(3-aminopropyl)piperazine, 1-(2-dimethylaminoethyl)-4-methylpiperazine, N-(2-aminoethyl) Piperazine and the like.

The pyrrolidine compound can be exemplified by pyrrolidine, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-aminoethyl)pyrrolidine, N-methylpyrrolidine, N-methylpyridylpyrrolidine, 3- Aminopyrrolidine, N-benzyl-3-aminopyrrolidine, and the like.

The above piperidine compound can be exemplified by piperidine, N-piperidineethanol, N-methylpiperidine, N-ethylpiperidine, 4-aminopiperidine, 4-piperidinecarboxylic acid, 4-aminomethylpiperidine. Wait.

In addition to the above components, the etching liquid of the present invention may contain other components in a range that does not impair the effects of the present invention. For example, a component stabilizer, an antifoaming agent, or the like may be added. When the above other ingredients are added, the concentration is about 0.001 to 5 g/L.

The etching solution can be easily prepared by dissolving the above components in water. The water is preferably water from which ionic substances and impurities have been removed, and is preferably, for example, ion-exchanged water, pure water, ultrapure water or the like.

The etchant may be formulated into a predetermined concentration at the time of use, or the concentrate may be prepared in advance and diluted before use. The method of using the etching liquid is not particularly limited, but from the viewpoint of effectively suppressing side etching, it is preferable to perform etching using a spray gun as will be described later. Moreover, although the temperature of the etching liquid at the time of use is not particularly limited, it is preferably 20 to 55 ° C from the viewpoint of maintaining high productivity and effectively suppressing side etching.

In the replenishing liquid of the present invention, when the etching liquid of the present invention is continuously or repeatedly used, the replenishing liquid added to the etching liquid contains an aqueous solution of an acid and a compound A. Each of the above replenishing liquids The composition is the same as that of the above-described etching solution of the present invention. By adding the above-mentioned replenishing liquid, the ratio of each component of the etching liquid can be maintained in an appropriate range, so that the effect of the etching liquid of the present invention described above can be stably maintained. Further, the replenishing liquid of the present invention may further contain a source of divalent copper ions such as copper chloride in a concentration range in which the concentration of divalent copper ions does not exceed 14 g/L. Further, in addition to the above components, the replenishing liquid of the present invention may be formulated with a component added to the etching solution.

The concentration of each component in the replenishing liquid is appropriately set depending on the concentration of each component in the etching liquid. However, from the viewpoint of stably maintaining the effect of the etching liquid of the present invention, the acid concentration is preferably 7 to 360 g/L. The concentration of Compound A is 0.005 to 10 g/L. Further, when the etching solution contains the above alicyclic amine compound, the above-mentioned replenishing liquid preferably contains the above alicyclic amine compound at a concentration of 0.01 to 10 g/L.

The method for forming a copper wiring according to the present invention is a method of forming a copper wiring for etching a portion of a copper layer which is not covered with an etching resist layer, and is characterized by etching using the etching liquid of the present invention. Thereby, as described above, side etching can be suppressed without impairing the linearity of the copper wiring. Further, in the copper wiring forming step using the method for forming a copper wiring of the present invention, when the etching liquid of the present invention is used continuously or repeatedly, it is preferred to perform etching while adding the above-described replenishing liquid of the present invention. The reason for this is that the effect of the above-described etching liquid of the present invention can be stably maintained because the ratio of each component of the etching liquid can be maintained in an appropriate range.

In the method for forming a copper wiring according to the present invention, it is preferable that the etching liquid is sprayed by a spray gun on a portion of the copper layer that is not covered with the etching protective layer. The reason is that the side etching can be effectively suppressed. At the time of spraying, the nozzle is not particularly limited, and a fan nozzle or a conical nozzle can be used.

When etching is performed using a spray gun, the spray pressure is preferably 0.04 MPa or more, more preferably 0.08 MPa or more. When the spray pressure is 0.04 MPa or more, a protective film having an appropriate thickness can be formed on the side surface of the copper wiring. Thereby, side erosion can be effectively prevented. Among them, from the viewpoint of preventing damage of the etching protective layer, The above spray pressure is preferably 0.30 MPa or less.

Example

Next, a comparative example will be described with reference to an embodiment of the present invention. However, the invention is not limited to the following examples.

Each of the etching liquids having the compositions shown in Tables 1 and 2 was etched under the conditions described later, and each item was evaluated by an evaluation method described later. Among them, the remaining portions of the etching liquids having the compositions shown in Tables 1 and 2 were ion-exchanged water. Further, the concentration of hydrochloric acid shown in Tables 1 and 2 is the concentration of hydrogen chloride.

(test substrate used)

A copper-clad laminate having a thickness of 12 μm electrolytic copper foil (JX Nippon Mining & Metal Co., Ltd., standard profile copper foil, trade name: JTC foil) is laminated, and the copper foil is treated with a palladium-containing catalyst (Okuno Pharmaceutical Co., Ltd.) The company name, product name: ADDCOPPER series) After the treatment, an electroless copper plating film was formed using an electroless copper plating solution (trade name: ADDCOPPER series, manufactured by Okuno Pharmaceutical Co., Ltd.). Next, an electroplated copper plating solution having a thickness of 13 μm was formed on the electroless copper plating film by using an electroplated copper plating solution (trade name: TOPUUCINA SF, manufactured by Okuno Chemical Co., Ltd.). Further, a dry film protective agent (manufactured by Asahi Kasei E-materials Co., Ltd., trade name: SUNFORTAQ-2559) was used on the obtained electroplated copper plating film to form an etching resist layer pattern having a thickness of 25 μm. At this time, the etching protective layer pattern was a pattern in which a protective layer pattern having a line/space (L/S)=45 μm/35 μm and a protective layer pattern of L/S=40 μm/150 μm were mixed.

(etching conditions)

The etching was carried out under the conditions of a spray pressure of 0.12 MPa and a treatment temperature of 40 ° C using a filling cone nozzle (manufactured by Ikebukuro Co., Ltd., trade name: ISJJX020). The etching processing time is set to a time at which the bottom width of the copper wiring after etching in the protective layer pattern region of L/S = 45 μm / 35 μm reaches 40 μm. point. After the etching, the mixture was washed with water and dried to carry out the evaluation shown below.

(side etching amount)

A part of each of the etched test substrates was cut, embedded in a cold-inserted resin, and polished to observe a cross section of the copper wiring. Then, the cross section was observed 200 times using an optical microscope, and the copper wiring top width (W1) and the copper wiring bottom width (W2) in the protective layer pattern region of L/S = 45 μm / 35 μm were measured, and the difference (W2-W1) was taken as Side erosion amount (μm). The results are shown in Tables 1 and 2.

(straight line)

Each of the etched test substrates was immersed in a 3 wt% aqueous sodium hydroxide solution for 60 seconds to remove the etching protective layer. Then, hydrochloric acid (hydrogen chloride concentration: 7 wt%) was used, and the protective film was removed by a fan nozzle (manufactured by Ikebukuro Co., Ltd., trade name: VP9020), a spray pressure of 0.12 MPa, a treatment temperature of 30 ° C, and a treatment time of 30 seconds. Then, the test substrate was observed 200 times with an optical microscope, and the copper wiring top wiring width in the protective layer pattern region of L/S = 40 μm / 150 μm was measured at intervals of 20 μm at 10 intervals, and the standard deviation was linear (μm). The results are shown in Tables 1 and 2.

As shown in Table 1, the examples of the present invention obtained good results in any of the evaluation items. On the other hand, as shown in Table 2, the comparative example obtained a result worse than the example in the partial evaluation item. From this result, it is understood that the side etching can be suppressed without impairing the linearity of the copper wiring according to the present invention.

1‧‧‧Bronze wiring

2‧‧‧ etching protection layer

3‧‧‧Protective membrane

Claims (11)

An etching solution, which is an etching solution for copper, which comprises an aqueous solution of an acid, an oxidizing metal ion, and a compound A having a selected from the group consisting of a thiol group, a thioether group, and a disulfide group. Here, at least one of the sulfur-containing functional group and the amine group in the group consisting of the thioether group and the disulfide-based sulfur atom and the hetero atom to which it is bonded is a single bond and does not form a π-conjugated group. The etching solution according to claim 1, wherein the acid is hydrochloric acid. The etching solution according to claim 1, wherein the oxidizing metal ion is a divalent copper ion. The etching solution according to claim 1, wherein the compound A is an aliphatic compound. The etching solution according to claim 1, wherein the concentration of the acid is 7 to 180 g/L, the concentration of the oxidizing metal ion is 10 to 250 g/L, and the concentration of the compound A is 0.005 to 10 g/L. The etching solution according to any one of claims 1 to 5, further comprising an alicyclic amine compound. The etching solution according to claim 6, wherein the alicyclic amine compound is one or more selected from the group consisting of a pyrrolidine compound, a piperidine compound, and a piperazine compound. The etching solution according to claim 7, wherein the piperazine compound is a compound represented by the following formula (I) [wherein R ¹ and R ² each independently represent hydrogen or a hydrocarbon-derived group having 1 to 6 carbon atoms; wherein at least one of R ¹ and R ² represents a hydrocarbon-derived group having 1 to 6 carbon atoms]. The etching solution according to claim 6, wherein the alicyclic amine compound has a concentration of 0.01 to 10 g/L. A replenishing liquid which is added to the replenishing liquid of the etching liquid when the etching liquid according to any one of claims 1 to 9 is continuously or repeatedly used, the replenishing liquid containing an acid, an aqueous solution of the compound A, the compound The A group has a thiol group, a thioether group, and a disulfide group selected from the group (wherein the thioether group and the disulfide group-based sulfur atom and the hetero atom to which it is bonded are connected by a single bond, and the π is not formed. At least one of the sulfur-containing functional groups and the amine group in the group formed by the yoke. A method of forming a copper wiring by etching a portion of the copper layer that is not covered with the etching protective layer, and etching using the etching solution according to any one of claims 1 to 9.