WO2019208461A1

WO2019208461A1 - Etching liquid for copper foils, method for producing printed wiring board using said etching liquid for copper foils, etching liquid for electrolytic copper layers, and method for producing copper pillar said etching liquid for electrolytic copper layers

Info

Publication number: WO2019208461A1
Application number: PCT/JP2019/016919
Authority: WO
Inventors: 一彰瀬戸; 聡玉井; 裕嗣松永
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2018-04-24
Filing date: 2019-04-22
Publication date: 2019-10-31
Also published as: CN112055759A; JP7230908B2; CN112055759B; TWI808158B; JPWO2019208461A1; KR20210002454A; TW201945591A

Abstract

The present invention relates to: an etching liquid for copper foils, which is capable of etching a copper foil, while suppressing the occurrence of side etching of a copper wiring line; and a method for etching a copper foil and a method for producing a printed wiring board, each of which uses this etching liquid for copper foils. The present invention also relates to: an etching liquid for electrolytic copper layers, which is capable of etching an electrolytic copper layer, while suppressing the occurrence of side etching of the electrolytic copper layer; and a method for etching an electrolytic copper layer and a method for producing a copper pillar, each of which uses this etching liquid for electrolytic copper layers. An etching liquid according to the present invention is characterized by containing (A) hydrogen peroxide, (B) sulfuric acid and (C) at least one azole compound that is selected from the group consisting of 5-amino-1H-tetrazole, 1, 5-pentamethylenetetrazole and 2-n-undecylimidazole. This etching liquid is also characterized in that: the molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is within the range of 6-30; the concentration of the azole compound (C) is within the range of 0.001-0.01% by mass; and phosphoric acid is not substantially contained therein.

Description

Etching solution for copper foil, method for producing printed wiring board using the same, etching solution for electrolytic copper layer, and method for producing copper pillar using the same

The present invention relates to an etching solution for copper foil and a method for producing a printed wiring board using the same. The present invention also relates to an electrolytic copper layer etching solution and a copper pillar manufacturing method using the same.

In a printed wiring board, an embedded trace substrate method (hereinafter referred to as “ETS method”) is known as one of the methods for miniaturizing copper wiring when forming copper wiring (hereinafter referred to as “ETS method”). References 1 and 2).
In the ETS method, the reduction of the copper wiring width is small and fine wiring can be formed. However, in the ETS method, etching of the copper wiring along the side wall of the interlayer insulating resin (side etching) may occur during etching of the copper foil, which is a problem (Patent Document 3).
In addition, in the manufacture of semiconductor packages, copper pillars that can handle narrower pitches instead of conventional solder bumps as connection terminals for flip chip mounting, which is a connection method between a semiconductor chip and a package interposer or a package substrate for mounting a semiconductor element Also known as “copper post” or “copper bump”. As a method for producing a copper pillar, a method is known in which a resist pattern is formed on a substrate on which a copper pillar is to be formed, and is formed by electrolytic copper plating in a gap between the resist patterns. In this method, after forming an electrolytic copper layer by electrolytic copper plating, there is usually a step of polishing the electrolytic copper layer and further etching the surface of the electrolytic copper layer to adjust the height of the obtained copper pillar. When this electrolytic copper layer is etched, the electrolytic copper layer may be etched (side etching) along the side walls of the resist constituting the resist pattern, which is a problem.

JP 2016-134622 A International Publication No. 2017/141985 Special table 2013-503965 gazette

Under such circumstances, when etching copper foil in the ETS method, a copper foil that does not cause side etching of copper wiring or suppresses side etching of copper wiring can be suppressed without using special equipment. It is desired to provide an etching solution for manufacturing and a method for producing a printed wiring board using the same.
Further, in the copper pillar manufacturing process, an electrolytic copper layer etching solution that does not cause side etching of the electrolytic copper layer during etching of the electrolytic copper layer, or that can suppress side etching of the electrolytic copper layer, and copper using the same It is desired to provide a method for manufacturing pillars.

The present invention provides the following copper foil etching solution, copper foil etching method and printed wiring board manufacturing method. Moreover, this invention provides the etching solution for electrolytic copper layers, the etching method of an electrolytic copper layer, and the manufacturing method of a copper pillar which are shown below.
[1] Hydrogen peroxide (A),
Sulfuric acid (B), and at least one azole compound (C) selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-undecylimidazole
An etching solution for copper foil containing
The molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6-30,
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass,
An etching solution for copper foil which does not substantially contain phosphoric acid.
[2] The copper foil etching solution according to [1], wherein the concentration of hydrogen peroxide (A) is in the range of 0.5 to 20% by mass.
[3] The copper foil etching solution according to [1] or [2], wherein the concentration of sulfuric acid (B) is in the range of 0.3 to 5% by mass.
[4] The etching solution according to any one of [1] to [3], which is for etching a copper foil in an embedded trace substrate method (ETS method).
[5] A method for etching a copper foil, which comprises etching the copper foil using the etching solution according to any one of [1] to [4] in the ETS method.
[6] A method for manufacturing a printed wiring board, comprising etching a copper foil using the etching solution according to any one of [1] to [4] in the ETS method.
[7] Hydrogen peroxide (A),
Electrolytic copper layer containing sulfuric acid (B) and at least one azole compound (C) selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-undecylimidazole Etching solution for
The molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6-30,
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass,
An electrolytic copper layer etching solution substantially free of phosphoric acid.
[8] The electrolytic copper layer etching solution according to [7], wherein the concentration of hydrogen peroxide (A) is in the range of 0.5 to 20% by mass.
[9] The electrolytic copper layer etching solution according to [7] or [8], wherein the concentration of sulfuric acid (B) is in the range of 0.3 to 5% by mass.
[10] The electrolytic copper layer etching solution according to any one of [7] to [9], which is used for etching the electrolytic copper layer in the copper pillar manufacturing process.
[11] A method for etching an electrolytic copper layer, comprising etching the electrolytic copper layer using the etching solution according to any one of [7] to [9] in a copper pillar manufacturing process.
[12] A method for producing a copper pillar, which includes etching the electrolytic copper layer using the etching solution according to any one of [7] to [9] in the copper pillar production process.

ADVANTAGE OF THE INVENTION According to this invention, the etching liquid for copper foils used suitably at the time of the etching of the copper foil in an ETS construction method can be provided.
According to a preferred aspect of the present invention, by using the etching solution of the present invention, the copper foil can be etched while suppressing the occurrence of side etching of the copper wiring in the ETS method, which corresponds to the miniaturization of the wiring. A printed wiring board can be manufactured.
Moreover, according to this invention, the etching liquid for electrolytic copper layers used suitably at the time of the etching of an electrolytic copper layer can be provided in the manufacturing process of a copper pillar.
Moreover, according to the preferable aspect of this invention, by using the etching liquid of this invention, an electrolytic copper layer can be etched in the copper pillar manufacturing process, suppressing generation | occurrence | production of the side etching of an electrolytic copper layer, desired. A copper pillar having the following shape can be manufactured.

It is the figure which showed an example of the process of the manufacturing method of the printed wiring board by an ETS construction method. It is the figure which showed an example of the process of the manufacturing method of the copper pillar using the construction method which forms a copper pillar by electrolytic copper plating. 2 is a scanning secondary electron micrograph of a wiring cross section when a copper foil is etched using the etching solution of Example 1. FIG. It is a scanning secondary electron micrograph of the wiring cross section when etching copper foil using the etching liquid of the comparative example 1. It is explanatory drawing for demonstrating the amount of side etching of copper wiring.

Hereinafter, the copper foil etching solution, the copper foil etching method and the printed wiring board manufacturing method, and the electrolytic copper layer etching solution, the electrolytic copper layer etching method and the copper pillar manufacturing method of the present invention are specifically described. Explained.

1. Etching Solution for Copper Foil Etching solution for copper foil of the present invention includes hydrogen peroxide (A), sulfuric acid (B), 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-un. Including at least one azole compound (C) selected from the group consisting of decylimidazole, wherein the molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6 to 30, and the azole compound (C) The concentration is in the range of 0.001 to 0.01% by mass and is characterized by substantially not containing phosphoric acid.

The etching solution of the present invention is used for etching copper foil. According to a preferred aspect of the present invention, the etching solution of the present invention contains the above components in a specific ratio, thereby suppressing the occurrence of side etching of the copper wiring during etching of the copper foil in the ETS method, Moreover, a flat etching process can be performed.

Hereinafter, each component contained in the etching solution for copper foil of the present invention will be described in detail.

[Hydrogen peroxide (A)]
In the present invention, hydrogen peroxide (A) (hereinafter sometimes simply referred to as component (A)) is a component that functions as an oxidizing agent for copper.
Hydrogen peroxide is not particularly limited, and various grades such as industrial and electronic industries can be used. In general, use as a hydrogen peroxide aqueous solution is preferable in terms of availability and operability.

The concentration (content) of hydrogen peroxide (A) in the etching solution is not particularly limited, but is preferably in the range of 0.5 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1. It is in the range of 5 to 5.0% by mass. When the concentration of hydrogen peroxide (A) is within the above range, the copper etching rate and the wiring shape are improved. Further, it is possible to suppress the occurrence of side etching of the copper wiring during the etching of the copper foil in the ETS method.

[Sulfuric acid (B)]
In the present invention, sulfuric acid (B) (hereinafter sometimes simply referred to as component (B)) is a component that acts as an etchant for copper oxidized by hydrogen peroxide.

The concentration (content) of sulfuric acid (B) in the etching solution is not particularly limited, but is preferably in the range of 0.3 to 5% by mass, more preferably 0.4 to 3% by mass, and still more preferably 0.5 to The range is 1% by mass. When the concentration of sulfuric acid (B) is within the above range, the etching rate and the wiring shape of copper are improved. Further, it is possible to suppress the occurrence of side etching of the copper wiring during the etching of the copper foil in the ETS method.

In the etching solution of the present invention, the molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6 to 30, more preferably 6.5 to 15, and further preferably 6 to 8. By controlling the blending ratio of hydrogen peroxide (A) and sulfuric acid (B), the etching rate and wiring shape of copper are improved. Further, it is possible to suppress the occurrence of side etching of the copper wiring during the etching of the copper foil in the ETS method.

[Azole compound (C)]
In the present invention, the azole compound (C) (hereinafter sometimes simply referred to as the component (C)) is considered to have a function of adsorbing to the copper surface and controlling the etching rate and etching shape of copper.
In the present invention, the azole compound (C) is at least one selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-undecylimidazole. These azole compounds may be used alone or in combination of two or more.

The concentration (content) of the azole compound (C) in the etching solution is in the range of 0.001 to 0.01% by mass, preferably 0.0015 to 0.007, more preferably 0.002 to 0.00. The range is 005. When the concentration of the azole compound (C) is within the above range, the copper etching rate and the wiring shape are improved. In addition, it is possible to suppress the occurrence of side etching of the copper wiring during the etching of the copper foil in the ETS method.

[phosphoric acid]
The etching solution of the present invention does not substantially contain phosphoric acid. When phosphoric acid is contained, the occurrence of side etching of the copper wiring may not be sufficiently suppressed during etching of the copper foil in the ETS method. Here, “substantially free of phosphoric acid” means that the content of phosphoric acid in the etching solution is less than 0.1% by mass, preferably less than 0.01% by mass, more preferably 0.001% by mass. Means less than. In the present invention, it is particularly preferable not to contain phosphoric acid.

[Other ingredients]
In addition to the above components, the etching solution of the present invention contains, as necessary, one or more of various additives usually used in water and other liquid compositions for etching, in a range that does not impair the effects of the liquid composition described above. Can be included.
For example, as water, those from which metal ions, organic impurities, particle particles, and the like have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, and the like are preferable, pure water is more preferable, and ultrapure water is particularly preferable. . The concentration (content) of water in the etching solution is the balance of the etching solution of the present invention, preferably 45 to 99% by mass, more preferably 75 to 98% by mass, and still more preferably 85 to 97% by mass. .
Further, a trace amount of alkali may be added as long as the pH does not change greatly.
Furthermore, known hydrogen peroxide stabilizers such as alcohols, phenylureas, organic carboxylic acids, organic amine compounds, and etching rate modifiers may be added to the etching solution of the present invention as necessary. .
The etching solution of the present invention is preferably a solution and does not contain solid particles such as abrasive particles.

The pH range of the etching solution of the present invention is preferably from 0.1 to 3, more preferably from 0.3 to 2, and even more preferably from 0.5 to 1.5.

[Preparation of etchant]
The etching solution of the present invention can be prepared by uniformly stirring the component (A), the component (B), the component (C), and other components as necessary. The stirring method of these components is not particularly limited, and a stirring method usually used in preparing an etching solution can be employed.

[Use of etching solution]
The etching solution of the present invention can be suitably used for etching copper foil. For example, the etching solution of the present invention can be suitably used when etching a copper foil in the ETS method. Moreover, the etching liquid of this invention can be used for the other use as which the etching of copper foil is requested | required besides the etching of the copper foil in an ETS construction method.
According to a preferable aspect of the present invention, etching is performed using the etching solution of the present invention, so that the etching rate and the wiring shape are improved. Moreover, when it uses for the etching of the copper foil in an ETS construction method, copper foil can be etched, suppressing generation | occurrence | production of the side etching of a copper wiring, and the printed wiring board corresponding to refinement | miniaturization of wiring can be obtained.

The copper foil to be etched is not particularly limited, but is preferably an electrolytic copper foil. The thickness of the copper foil is not particularly limited, but is usually 1.5 to 105 μm, preferably 1.5 to 5 μm, more preferably 1.5 to 3 μm.
The etching rate (also referred to as “etching rate”) of the copper foil is not particularly limited, but preferably 1 to 40 μm / min, more preferably 5 to 30 μm / min at a liquid temperature of 30 ° C., and further 5 to 20 μm / min. preferable. When the etching rate is 1 to 40 μm / min, high production efficiency can be maintained and the etching operation can be performed stably.

2. Etching method of copper foil The etching method of this invention includes etching copper foil using the etching liquid of this invention mentioned above. Especially the etching method of this invention can be used suitably at the time of the etching of the copper foil in an ETS construction method.

The use temperature of the etching solution of the present invention is not particularly limited, but a temperature of 10 to 50 ° C. is preferable, more preferably 20 to 45 ° C., and further preferably 25 to 40 ° C. When the temperature of the etching solution is 10 ° C. or higher, the etching rate is good, and thus excellent production efficiency is obtained. On the other hand, if the temperature of the etching solution is 50 ° C. or less, the change in the solution composition can be suppressed and the etching conditions can be kept constant. Although the etching rate increases by increasing the temperature of the etching solution, the optimum processing temperature should be appropriately determined in consideration of keeping the composition change of the etching solution (for example, decomposition of hydrogen peroxide) small. That's fine.

The etching time is not particularly limited, but is preferably 1 to 600 seconds, more preferably 5 to 300 seconds, further preferably 10 to 180 seconds, and particularly preferably 15 to 120 seconds. What is necessary is just to select processing time suitably by various conditions, such as the state of copper foil surface, the density | concentration of etching liquid, temperature, and a processing method.

The method for bringing the etching solution of the present invention into contact with the etching object is not particularly limited. For example, a wet etching method such as a method in which an etching target is brought into contact with an etching target by a method such as dropping (single-leaf spin processing) or spraying (spraying) of an etching solution, or a method in which an etching target is immersed in an etching solution. Can be adopted. Any method can be employed in the etching method of the present invention.

The object to be etched by the etching method of the present invention is a copper foil, preferably an electrolytic copper foil. The thickness of the copper foil etched by the etching method of the present invention is as described in “1. Etching solution for copper foil”.

3. The manufacturing method of a printed wiring board The manufacturing method of the printed wiring board of this invention includes etching a copper foil using the etching liquid of this invention mentioned above in the ETS method.

FIG. 1 is a diagram showing an example of a process of a method for manufacturing a printed wiring board by an ETS method.
First, as shown to Fig.1 (a), copper foil (3) with carrier foil (2) is laminated on a detached core (support substrate for circuit formation) (1). As the detached core, for example, a substrate containing a thermosetting resin can be used. Examples of the carrier foil (2) include an aluminum foil, a copper foil, a stainless steel foil, a resin film, a resin film whose surface is metal-coated, and a glass plate. As the copper foil (3), an electrolytic copper foil is preferable.
In addition, it can replace with a detached core and copper foil with a carrier foil, and the other thing which has an equivalent function can also be used.

Next, a dry film resist layer is formed on the surface of the copper foil (3), and is exposed and developed to form a resist pattern (4) as shown in FIG.
Then, as shown in FIG.1 (c), copper plating (5) is given to the exposed part of the copper foil (3) in which the resist pattern (4) is not formed. The copper plating may be electrolytic copper plating or electroless copper plating, but electrolytic copper plating is preferable from the viewpoint of cost and productivity.
Next, as shown in FIG. 1 (d), the resist pattern (4) is stripped with a stripping solution to form a copper wiring (5a).

Next, as shown in FIG. 1E, the obtained structure is inverted and the wiring (5a) is embedded in the interlayer insulating resin (6). The interlayer insulating resin (6) is not particularly limited as long as it is generally used for manufacturing printed wiring boards.
Then, as shown in FIG.1 (f), a detached core (1) and carrier foil (2) are peeled off.
Finally, as shown in FIG. 1 (g), the copper foil (3) is etched back using the etching solution of the present invention to obtain a printed wiring board (10) on which the copper wiring (5a) is formed. Can do.

According to a preferred aspect of the present invention, in the ETS method, side etching of the copper wiring (5a) along the side wall of the interlayer insulating resin (6) occurs by etching the copper foil using the etching solution of the present invention. The copper foil (3) can be etched while suppressing the above, and the printed wiring board (10) corresponding to the miniaturization of the wiring can be manufactured. According to the preferable aspect of this invention, the printed wiring board (10) corresponding to refinement | miniaturization of wiring can be manufactured, without using special equipment.

4). Electrolytic Copper Layer Etching Solution The electrolytic copper layer etching solution of the present invention includes hydrogen peroxide (A), sulfuric acid (B), 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n. -Containing at least one azole compound (C) selected from the group consisting of undecylimidazole, wherein the molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6-30, and the azole compound (C ) Is in the range of 0.001 to 0.01% by mass and substantially does not contain phosphoric acid.

The etching solution of the present invention is used for etching an electrolytic copper layer. According to a preferred aspect of the present invention, the etching solution of the present invention contains the above components in a specific ratio, so that in the copper pillar manufacturing process using a method of forming a copper pillar by electrolytic copper plating, Occurrence of side etching of the electrolytic copper layer during etching of the copper layer surface can be suppressed, and a flat etching process can be performed.

Each component contained in the etching solution for electrolytic copper layers of the present invention is the same as that described in the above-mentioned “1. Etching solution for copper foil”, and the content and specific examples of each component, as well as optional components, etc. The same applies to.

The etching solution of the present invention can be used for etching an electrolytic copper layer. For example, the etching solution of the present invention can be suitably used at the time of etching an electrolytic copper layer in a copper pillar manufacturing process using a method of forming a copper pillar by electrolytic copper plating. Moreover, the etching liquid of this invention can be used also for the other use (for example, formation of a wiring circuit) by which the etching of an electrolytic copper layer is requested | required.
According to a preferred aspect of the present invention, the etching rate of copper and the shape and surface shape of the copper pillar are improved by performing the etching treatment using the etching solution of the present invention. Moreover, in the manufacturing process of the copper pillar using the method of forming the copper pillar by electrolytic copper plating, when the etching solution of the present invention is used for etching the electrolytic copper layer, the generation of side etching of the electrolytic copper layer is suppressed. The electrolytic copper layer can be etched, and a copper pillar having a desired shape and surface shape can be obtained. By improving the shape and surface shape of the copper pillar, flip chip mounting (flip chip bonding) becomes easier.
In the present invention, the copper pillar is not particularly limited. The copper pillar is, for example, a connection terminal that can be flip-chip mounted, and includes a copper bump and a copper post.

In the present invention, the electrolytic copper layer is not particularly limited as long as it is a layer containing electrolytic copper. Further, the shape of the electrolytic copper layer to be etched is not particularly limited, and may be, for example, a cylindrical shape, a substantially square shape, or a wiring shape. The thickness of the electrolytic copper layer is not particularly limited, but is usually 1.5 to 105 μm, preferably 1.5 to 10 μm, more preferably 1.5 to 8 μm.
The etching rate (also referred to as “etching rate”) of the electrolytic copper layer is not particularly limited, but is preferably 1 to 40 μm / min, more preferably 5 to 30 μm / min at a liquid temperature of 30 ° C. Further preferred. When the etching rate is 1 to 40 μm / min, high production efficiency can be maintained and the etching operation can be performed stably.

5. Electrolytic Copper Layer Etching Method The etching method of the present invention includes etching the electrolytic copper layer using the above-described etching solution of the present invention. Especially the etching method of this invention can be used suitably at the time of the etching of the electrolytic copper layer in the manufacturing process of the copper pillar using the construction method which forms a copper pillar by electrolytic copper plating.

The use temperature of the etching solution of the present invention is not particularly limited, but a temperature of 10 to 50 ° C. is preferable, 20 to 45 ° C. is more preferable, and 25 to 40 ° C. is more preferable. When the temperature of the etching solution is 10 ° C. or higher, the etching rate is good, and thus excellent production efficiency is obtained. On the other hand, if the temperature of the etching solution is 50 ° C. or less, the change in the solution composition can be suppressed and the etching conditions can be kept constant. Although the etching rate increases by increasing the temperature of the etching solution, the optimum processing temperature should be appropriately determined in consideration of keeping the composition change of the etching solution (for example, decomposition of hydrogen peroxide) small. That's fine.

The etching treatment time is not particularly limited, but is preferably 1 to 600 seconds, more preferably 5 to 300 seconds, further preferably 10 to 180 seconds, and particularly preferably 15 to 120 seconds. What is necessary is just to select processing time suitably by various conditions, such as the height of a desired electrolytic copper layer, the state of the electrolytic copper layer surface, the density | concentration of etching liquid, temperature, and a processing method.

The object to be etched by the etching method of the present invention is an electrolytic copper layer. The thickness of the electrolytic copper layer etched by the etching method of the present invention is as described above in “4. Electrolytic copper layer etching solution”.

6). Copper Pillar Manufacturing Method The copper pillar manufacturing method of the present invention includes etching the electrolytic copper layer using the above-described etching solution of the present invention in the copper pillar manufacturing process.

FIG. 2 is a diagram illustrating an example of a process of a copper pillar manufacturing method using a method of forming a copper pillar by electrolytic copper plating.
The method of forming a copper pillar by electrolytic copper plating shown below is an example, and is not limited to this.
First, as shown in FIG. 2A, a resin substrate (11) having a copper wiring (11b) in the gap between the interlayer insulating resins (11a) is prepared. The resin substrate (11) may be formed on the chip as a part of the configuration of the semiconductor chip (semiconductor element), and may be formed on the package substrate as a part of the configuration of the semiconductor element mounting package substrate (printed wiring board). It may be formed.

Next, as shown in FIG. 2B, the surface of the resin substrate (11) is subjected to chemical copper plating to form a chemical copper layer (12).
Next, a dry film resist layer is formed on the surface of the chemical copper layer (12), and exposed and developed to form a resist pattern (13) as shown in FIG. 2 (c).
Thereafter, electrolytic copper plating is applied to the exposed portion of the chemical copper layer (12) where the resist pattern (13) is not formed, and an electrolytic copper layer (14) is formed as shown in FIG. In order to make the height of the obtained copper pillars uniform, the electrolytic copper layer (14) is usually formed to a height exceeding the resist pattern (13), and then polished using chemical mechanical polishing or the like to obtain a resist pattern (13 It is desirable to adjust the height to the same level.
Next, the surface of the electrolytic copper layer (14) is etched using the etching solution of the present invention, and as shown in FIG. 2 (e), the height of the electrolytic copper layer (14) is made higher than the height of the resist pattern (13). Also adjust it low. If the height of the electrolytic copper layer (14) is approximately the same as the height of the resist pattern (13), copper may remain on the resist pattern (13), making it difficult to peel off the next resist pattern (13). There is a case. Therefore, it is desirable to completely remove the copper on the resist pattern (13) by performing an etching process until the height of the electrolytic copper layer (14) becomes lower than the height of the resist pattern (13). Moreover, it is also possible to form another metal layer on the electrolytic copper layer (14) by performing etching until the height of the electrolytic copper layer (14) is lower than the height of the resist pattern (13). Become. What is necessary is just to select the height of an electrolytic copper layer (14) suitably according to the objective or a use.
Finally, as shown in FIG. 2 (f), the resist pattern (13) can be peeled off with a stripping solution to form a copper pillar (15) on the resin substrate (11) and the chemical copper layer (12). . Thereafter, the chemical copper layer (12) where the copper pillar (15) is not formed may be removed by flash etching.

According to a preferred embodiment of the present invention, in the copper pillar manufacturing process using a method of forming copper pillars by electrolytic copper plating, the electrolytic copper layer (14) is etched using the etching solution of the present invention (FIG. 2 (e)), etching the electrolytic copper layer (14) without causing side etching of the electrolytic copper layer (14) along the side wall of the resist pattern (13) or suppressing side etching. The copper pillar (15) having a desired shape / surface shape can be efficiently produced. When side etching of the electrolytic copper layer (14) occurs, it is necessary to reduce the reliability of electrical connection through the copper pillar, or to design a large connecting area of the pillar diameter in consideration of the side etching. However, according to a preferred embodiment of the present invention, since the connection terminal for flip chip mounting that can cope with a narrower pitch can be formed at a desired position on the substrate, the semiconductor device It is possible to meet the demand for higher density and higher integration of mounting components such as.

Hereinafter, the present invention will be specifically described by way of examples. However, as long as the effects of the present invention are exhibited, the embodiments can be appropriately changed.

[Fabrication of evaluation substrate (resin substrate with copper wiring and copper foil)]
The copper foil etching solution, the copper foil etching method, and the printed wiring board manufacturing method of the present invention can be evaluated using the substrate with the copper foil (3) shown in FIG.
Using the ETS method, a substrate with the copper foil (3) in FIG. 1 (f) formed by laminating a copper foil having a thickness of 5 μm on the prepreg was prepared as follows and used as an evaluation substrate. .
The evaluation substrate was produced as follows.
First, an ultrathin copper foil “MT18SD-H-T5” (manufactured by Mitsui Kinzoku Co., Ltd.) with a carrier foil having an ultrathin copper foil (corresponding to copper foil (3)) having a thickness of 5 μm is attached to a detachable core (base) (Material: “HL-832NSF”) (manufactured by Mitsubishi Gas Chemical Co., Inc.).
Next, a dry film resist was laminated on the ultrathin copper foil side of the laminated substrate, and the dry film resist was exposed with a wiring design of line / space (L / S) = 10/10 μm. The exposed dry film resist was developed using an aqueous sodium carbonate solution to form a resist pattern, and then pattern plating was performed so that the wiring height was 10 μm by electrolytic copper plating.
After pattern plating, the resist pattern was stripped using a dry film stripping solution “R-100S” (Mitsubishi Gas Chemical Co., Ltd.) to form a copper wiring.
The copper wiring was laminated so as to be embedded in a prepreg “GHPL-830NS SH65” (Mitsubishi Gas Chemical Co., Ltd.). In addition, although not shown in figure, as an outer layer copper foil laminated | stacked on the prepreg on the opposite side to the copper wiring used when laminating | stacking a prepreg, copper foil thickness ultra-thin copper foil with a carrier foil of 5 micrometers is " MT18Ex "(manufactured by Mitsui Mining & Smelting Co., Ltd.) was used with the 5 μm copper foil on the prepreg side. Thereafter, the detached core and the carrier foil were peeled off to produce a substrate with the copper foil (3) of FIG.
The obtained substrate was cut into a size of 30 mm × 30 mm with the processing design part as the center to obtain an evaluation substrate. In the prepreg of the evaluation substrate, copper wiring is formed with a wiring width of 10 to 10.5 μm at a pitch of 20 μm.

[Evaluation of side etching amount]
Evaluation of the side etching amount was judged from the wiring cross-sectional shape after etching.
About the wiring cross section of the board | substrate after performing the etching obtained by the Example and the comparative example, using a scanning electron microscope ("S3700N type (model number)"; Hitachi High-Technologies Corporation make) observation magnification 30,000 times ( Observation was performed at an acceleration voltage of 2 kV and an emission current of 10 μA. Based on the obtained SEM image, the side etching amount of the wiring cross section was examined. As shown in FIG. 4, the amount of side etching was determined and evaluated as follows. In the present specification, the “side etching amount” is the shortest distance from the upper end of the copper wiring to the resin in contact with the copper foil.
Excellent: All values are less than 0.1 μm Impossible: All values are 0.1 μm or more.

[Evaluation of etching rate of copper foil]
The value obtained by dividing the film thickness difference before and after the copper foil etching process by the processing time was defined as the copper foil etching rate, which was calculated and evaluated as follows.
A: 5 μm / min or more and 20 μm / min or less B: 1 μm / min or more and less than 5 μm / min, or more than 20 μm / min and less than 40 μm / min C: less than 1 μm / min, more than 40 μm / min A and B are acceptable products.

[Example 1]
In a 1 L glass beaker, 0.949 kg of pure water, hydrogen peroxide (A) (manufactured by Mitsubishi Gas Chemical Co., Ltd., 60% by mass, molecular weight 34) 0.033 kg, sulfuric acid (B) (Mitsubishi Gas Chemical) 0.017 kg of 46 mass% dilute sulfuric acid manufactured by Co., Ltd. and molecular weight 98) and 0.0003 kg of 5-amino-1H-tetrazole (Masuda Chemical Co., Ltd.) as the azole compound (C) were added. An etching solution was prepared by stirring to a uniform state.
Using this etching solution, the substrate for evaluation was subjected to a spray process for etching a copper foil having a thickness of 8 μm at a liquid temperature of 30 ° C. and a spray pressure of 0.15 MPa.

In order to determine the etching time of the copper foil having a thickness of 8 μm, the entire copper foil substrate (size: 40 mm × 40 mm) is sprayed at a liquid temperature of 30 ° C. for 60 seconds, and the etching rate (hereinafter referred to as “ER”) ”) And the number of processing seconds was calculated from ER.
ER [μm / min] = (mass before treatment [g] −mass after treatment [g]) / (treatment area [m ² ] × 8.96 [g / cm ³ ] (specific gravity of copper))
The required number of seconds for the etching process with a copper foil thickness of 8 μm = 8 [μm] × [60 seconds] / ER [μm / min]
The evaluation substrate after the etching treatment was broken, and the cross section of the substrate (wiring cross section) was observed using a scanning secondary electron microscope. A scanning secondary electron micrograph of the cross section of the substrate (wiring cross section) is shown in FIG. As shown in FIG. 3, when etching was performed using the etching solution of Example 1, the occurrence of side etching could be suppressed, and the shape of the copper wiring was good.

[Example 2]
An etching solution was prepared in the same manner as in Example 1 except that phenylurea was used at a quantitative ratio shown in Table 1, and the side etching amount was evaluated after spraying the evaluation substrate.

[Examples 3 and 4]
An etching solution was prepared and evaluated in the same manner as in Example 1 except that the amount ratio of the component (A) was changed and the molar ratio of the components (A) and (B) was changed to that shown in Table 1. After the substrate was sprayed, the side etching amount was evaluated.

[Examples 5 and 6]
An etching solution was prepared in the same manner as in Example 1 except that the components (A) and (B) were used in the quantitative ratios shown in Table 1, and the side etching amount was evaluated after spraying the substrate for evaluation. did.

[Examples 7 and 8]
(C) Except having used the compound of Table 1 as a component, the etching liquid was prepared like Example 1 and sprayed to the board | substrate for evaluation, Then, the side etching amount was evaluated.

[Example 9]
An etching solution was prepared in the same manner as in Example 1 except that the component (C) was used in the quantitative ratio shown in Table 1 and phenylurea was used in the quantitative ratio shown in Table 1, and sprayed onto the evaluation substrate. Then, the side etching amount was evaluated.

[Comparative Example 1]
An etching solution was prepared in the same manner as in Example 1 except that the component (C) was not used, and the side etching amount was evaluated after spraying the evaluation substrate. A scanning secondary electron micrograph of the cross section of the substrate (wiring cross section) is shown in FIG. As shown in FIG. 4, when etching was performed using the etching solution of Comparative Example 1, side etching occurred, and a copper wiring having a desired shape could not be obtained.

[Comparative Example 2]
(C) Etching solution was prepared in the same manner as in Example 2 except that the component was not used, and after spraying the evaluation substrate, the side etching amount was evaluated.

[Comparative Examples 3 to 8]
An etching solution was prepared and evaluated in the same manner as in Example 1 except that the amount ratio of the component (A) was changed and the molar ratio of the components (A) and (B) was changed to that shown in Table 1. After the substrate was sprayed, the side etching amount was evaluated.

[Comparative Examples 9 and 10]
An etching solution was prepared in the same manner as in Example 1 except that the amount ratio of the component (C) was changed to that shown in Table 1, and the side etching amount was evaluated after spraying the evaluation substrate.

[Comparative Examples 11 to 13]
(B) An etching solution was prepared in the same manner as in Example 1 except that the acid shown in Table 1 was used in the quantitative ratio shown in Table 1 instead of the component, and the substrate was subjected to spray treatment on the evaluation substrate. The etching amount was evaluated.

[Comparative Examples 14 to 21]
(C) Except having used the azole compound of Table 1 instead of the component, the etching liquid was prepared like Example 1 and sprayed on the board | substrate for evaluation, Then, the side etching amount was evaluated.

The evaluation results of the examples are shown in Table 1, and the evaluation results of the comparative examples are shown in Tables 2 and 3, respectively.

As shown in Table 1, in any of the etching solutions of Examples 1 to 8, the copper foil could be etched at a good etching rate, the side etching amount was suppressed, and the shape of the copper wiring after etching was also good. .
On the other hand, as shown in Tables 2 and 3, in the etching solutions of Comparative Examples 1 to 10 and 12 to 21, a large amount of side etching occurred in the copper wiring, and a copper wiring having a desired shape could not be obtained. Moreover, in the comparative example 11, the copper wiring center part was etched and the desired wiring shape was not obtained.

The above examples show that side etching did not occur on the copper foil using the etching solution of the present invention in the copper foil etching in the ETS method, but formed by the copper foil and electrolytic copper plating in the ETS method. Since the same copper pillar is the same electrolytic copper and the same etching reaction is considered to proceed chemically, it is considered that the occurrence of side etching of the electrolytic copper layer can be similarly suppressed in the manufacturing process of the copper pillar.

The etching solution of the present invention can be suitably used as an etching solution for a copper foil or an electrolytic copper layer. In particular, the etching solution of the present invention can be suitably used when etching a copper foil in the ETS method. According to a preferred aspect of the present invention, by using the etching solution of the present invention, the copper foil can be etched while suppressing the occurrence of side etching of the copper wiring in the ETS method, which corresponds to the miniaturization of the wiring. A printed wiring board can be manufactured. Moreover, the etching liquid of this invention can be used suitably at the time of the etching of an electrolytic copper layer in the manufacturing process of the copper pillar using the construction method which forms a copper pillar by electrolytic copper plating. According to a preferred embodiment of the present invention, by using the etching solution of the present invention, the electrolytic copper layer can be etched while suppressing the occurrence of side etching of the electrolytic copper layer in the manufacturing process of the copper pillar. A copper pillar having a shape can be produced.

DESCRIPTION OF SYMBOLS 1 Detachment core 2 Carrier foil 3 Copper foil 4 Resist pattern 5 Copper plating 5a Copper wiring 6 Interlayer insulation resin 10 Printed wiring board 11 Resin substrate 11a Interlayer insulation resin 11b Copper wiring 12 Chemical copper layer 13 Resist pattern 14 Electrolytic copper layer 15 Copper pillar

Claims

Hydrogen peroxide (A),
For copper foil containing sulfuric acid (B) and at least one azole compound (C) selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-undecylimidazole An etchant,
The molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6-30,
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass,
An etching solution for copper foil which does not substantially contain phosphoric acid.
The copper foil etching solution according to claim 1, wherein the concentration of hydrogen peroxide (A) is in the range of 0.5 to 20 mass%.
The copper foil etching solution according to claim 1 or 2, wherein the concentration of sulfuric acid (B) is in the range of 0.3 to 5 mass%.
The etching solution for copper foil according to any one of claims 1 to 3, which is for etching a copper foil in an embedded trace substrate method (ETS method).
In the embedded trace substrate construction method (ETS construction method), the etching method of copper foil including etching copper foil using the etching liquid as described in any one of Claim 1 to 3.
In the embedded trace substrate method (ETS method), the manufacturing method of a printed wiring board including etching copper foil using the etching liquid as described in any one of Claim 1 to 3.
Hydrogen peroxide (A),
Electrolytic copper layer containing sulfuric acid (B) and at least one azole compound (C) selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole and 2-n-undecylimidazole Etching solution for
The molar ratio of hydrogen peroxide (A) to sulfuric acid (B) is in the range of 6-30,
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass,
An electrolytic copper layer etching solution substantially free of phosphoric acid.
The electrolytic copper layer etching solution according to claim 7, wherein the concentration of hydrogen peroxide (A) is in the range of 0.5 to 20 mass%.
The electrolytic copper layer etching solution according to claim 7 or 8, wherein the concentration of sulfuric acid (B) is in the range of 0.3 to 5 mass%.
The electrolytic solution for an electrolytic copper layer according to any one of claims 7 to 9, which is for etching the electrolytic copper layer in a copper pillar manufacturing process.
The manufacturing method of a copper pillar WHEREIN: The etching method of an electrolytic copper layer including etching an electrolytic copper layer using the etching liquid as described in any one of Claim 7 to 9.
In the manufacturing process of a copper pillar, the manufacturing method of a copper pillar including etching an electrolytic copper layer using the etching liquid as described in any one of Claim 7 to 9.