TW201945591A - 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 producing method thereof - Google Patents

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

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

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

As one of the methods for miniaturizing copper wirings when forming copper wirings in printed wiring boards, an embedded trace substrate method (hereinafter referred to as "ETS method") is known (Patent Documents 1 and 2) .
In the ETS method, fine wiring can be formed without reducing the width of the copper wiring. However, in the ETS method, when copper foil is etched, copper wiring along the side wall of the interlayer insulating resin may be etched (side etched). This is a problem (Patent Document 3).
Moreover, in the manufacture of semiconductor packages, as for a flip-chip-mounted connection terminal of a connection method between a semiconductor wafer and a package interposer or a package substrate for mounting a semiconductor element, copper pillars are known which can correspond to a narrower pitch. (Also known as "copper posts" or "copper bumps") instead of conventional solder bumps. As for a method for manufacturing a copper pillar, the following method is known: forming a photoresist pattern on a substrate on which a copper pillar is to be formed, and forming a gap between the photoresist pattern by electroplating copper. In this method, after the electrolytic copper layer is formed by electroplating copper, there is usually a step of grinding the electrolytic copper layer, further etching the surface of the electrolytic copper layer, and adjusting the height of the obtained copper pillar. When the electrolytic copper layer is etched, the electrolytic copper layer may be etched (side etched) along the sidewall of the photoresist constituting the photoresist pattern. This is a problem.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-134622
[Patent Document 2] International Publication No. 2017/141985
[Patent Document 3] Japanese Patent Publication No. 2013-503965

[Problems to be Solved by the Invention]

In such a situation, it is desirable to provide an etching solution for copper foil and a method for manufacturing a printed wiring board using the same. When etching copper foil in the ETS method, no special equipment is used, and the side of the copper wiring is not etched. , Or can suppress the occurrence of side etching of copper wiring.
In the manufacturing steps of the copper pillars, it is desirable to provide an etching solution for an electrolytic copper layer and a method for manufacturing the copper pillars using the etching solution: when the electrolytic copper layer is etched, side etching of the electrolytic copper layer does not occur, or electrolytic copper can be suppressed The side of the layer is etched.
[Means for solving problems]

The present invention provides a copper foil etching solution, a copper foil etching method, and a printed wiring board manufacturing method described below. In addition, the present invention provides an etching solution for an electrolytic copper layer, an etching method for an electrolytic copper layer, and a method for manufacturing a copper pillar as described below.
[1] An etching solution for copper foil, which contains hydrogen peroxide (A), sulfuric acid (B), and selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole, and 2-n At least one azole compound (C) in the group consisting of undecylimidazole,
The molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is in the range of 6 to 30.
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass.
The etching solution for copper foil contains substantially no phosphoric acid.
[2] The etching solution for copper foil according to [1], wherein the concentration of the hydrogen peroxide (A) is within a range of 0.5 to 20% by mass.
[3] The etching solution for copper foil according to [1] or [2], wherein the concentration of the sulfuric acid (B) is in a range of 0.3 to 5% by mass.
[4] The etching solution for copper foil according to any one of [1] to [3], which is used to etch copper foil in the Embedded Trace Substrate method (ETS method).
[5] An etching method of copper foil, including the step of using a copper foil etching solution according to any one of [1] to [4] to etch the copper foil in an embedded circuit board method (ETS method).
[6] A method for manufacturing a printed wiring board, including the step of etching a copper foil using an etching solution for a copper foil according to any one of [1] to [3] in an embedded circuit board method (ETS method) .
[7] An etching solution for an electrolytic copper layer, comprising hydrogen peroxide (A), sulfuric acid (B), and a member selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole, and 2- At least one azole compound (C) in the group consisting of n-undecylimidazole,
The molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is in the range of 6 to 30.
The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass.
This etching solution for an electrolytic copper layer does not substantially contain phosphoric acid.
[8] The etching solution for an electrolytic copper layer according to [7], wherein the concentration of the hydrogen peroxide (A) is in a range of 0.5 to 20% by mass.
[9] The etching solution for an electrolytic copper layer according to [7] or [8], wherein the concentration of the sulfuric acid (B) is in a range of 0.3 to 5% by mass.
[10] The etching solution for an electrolytic copper layer according to any one of [7] to [9], which is used to etch the electrolytic copper layer in a manufacturing step of a copper pillar.
[11] An etching method for an electrolytic copper layer, including the step of etching the electrolytic copper layer using an etching solution for an electrolytic copper layer according to any one of [7] to [9] in a manufacturing step of a copper pillar.
[12] A method for manufacturing a copper pillar, including the step of etching the electrolytic copper layer using an etching solution for an electrolytic copper layer according to any one of [7] to [9] in the manufacturing steps of the copper pillar.
[Effect of the invention]

According to the present invention, it is possible to provide an etchant for a copper foil that can be used for etching a copper foil in the ETS method.
According to an ideal aspect of the present invention, by using the etching solution of the present invention, in the ETS method, it is possible to etch copper foil while suppressing the occurrence of side etching of copper wiring, and to produce printed wiring corresponding to the miniaturization of wiring. board.
In addition, according to the present invention, an etching solution for an electrolytic copper layer suitable for etching an electrolytic copper layer can be provided in a manufacturing step of a copper pillar.
In addition, according to an ideal aspect of the present invention, by using the etching solution of the present invention, in the manufacturing process of the copper pillar, it is possible to etch the electrolytic copper layer while suppressing the occurrence of side etching of the electrolytic copper layer, and it is possible to manufacture the electrode with a desired Shaped copper pillar.

The following specifically describes the etching solution for copper foil, the etching method of copper foil and the manufacturing method of printed wiring board, the etching solution for electrolytic copper layer, the etching method of electrolytic copper layer, and the manufacturing method of copper pillar. Instructions.

1. Copper foil etching solution The copper foil etching solution of the present invention is characterized by containing hydrogen peroxide (A), sulfuric acid (B), and selected from the group consisting of 5-amino-1H-tetrazole, 1,5- At least one azole compound (C) in the group consisting of pentamethylenetetrazole and 2-n-undecylimidazole; the molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is 6 Within the range of -30; the concentration of the azole compound (C) is within the range of 0.001 to 0.01% by mass; and the etching solution for copper foil does not substantially contain phosphoric acid.

The etching solution of the present invention is used for etching copper foil. According to an ideal aspect of the present invention, the etching solution of the present invention can suppress the occurrence of side etching of the copper wiring when the copper foil is etched in the ETS method by containing the above components at a specific ratio, and can perform a flat etching process.

Hereinafter, each component contained in the etching solution for copper foils of this invention is demonstrated in detail.

[Hydrogen peroxide (A)]
In the present invention, hydrogen peroxide (A) (hereinafter sometimes referred to as (A) component) is a component that functions as an oxidant for copper.
There is no particular limitation on hydrogen peroxide, and various grades such as industrial and electronic industries can be used. Generally speaking, from the viewpoints of availability and operability, it is suitable to use it in the form of an aqueous hydrogen peroxide solution.

The concentration (content) of hydrogen peroxide (A) in the etching solution is not particularly limited, and is preferably in the range of 0.5 to 20% by mass, more preferably in the range of 0.5 to 10% by mass, and more preferably in the range of 1.5 to 5.0% by mass. . When the concentration of hydrogen peroxide (A) is within the above range, the etching rate and wiring shape of copper are good. In addition, it is possible to suppress side etching of the copper wiring from occurring when the copper foil is etched in the ETS method.

[Sulfuric acid (B)]
In the present invention, sulfuric acid (B) (hereinafter sometimes referred to as (B) component) is a component that functions as an etchant for copper that is 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 in the range of 0.4 to 3% by mass, and more preferably in the range of 0.5 to 1% by mass. When the concentration of sulfuric acid (B) is within the above range, the etching rate and wiring shape of copper are good. In addition, it is possible to suppress side etching of the copper wiring from occurring when the copper foil is etched 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 still more preferably 6 to 8. By controlling the blending ratio of hydrogen peroxide (A) and sulfuric acid (B), the etching speed and wiring shape of copper become good. In addition, it is possible to suppress side etching of the copper wiring from occurring when the copper foil is etched in the ETS method.

[Azole compound (C)]
The azole compound (C) (hereinafter sometimes referred to as (C) component) in the present invention is considered to be adsorbed on the surface of copper and has a function of controlling the etching speed and shape of copper.
The azole compound (C) in the present invention 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, more preferably 0.0015 to 0.007, and still more preferably 0.002 to 0.005. When the concentration of the azole compound (C) is within the above range, the etching rate and the wiring shape of copper become more favorable. In addition, it is possible to suppress side etching of the copper wiring from occurring when the copper foil is etched in the ETS method.

[Phosphoric acid]
The etching solution of the present invention does not substantially contain phosphoric acid. If phosphoric acid is contained, there is a case where the side etching of the copper wiring cannot be sufficiently suppressed during the etching of the copper foil in the ETS method. Here, "substantially does not contain phosphoric acid" means that the content of phosphoric acid in the etching solution is less than 0.1% by mass, more preferably less than 0.01% by mass, and more preferably less than 0.001% by mass. In the present invention, it is particularly preferable that it does not contain phosphoric acid.

[Other ingredients]
The etching solution of the present invention may contain, in addition to the above-mentioned components, at least one of various additives that are generally used in water and other liquid composition for etching, as long as the effects of the liquid composition are not impaired.
For example, in terms of water, it is preferable to remove metal ions, organic impurities, particulates, etc. by distillation, ion exchange treatment, filtration treatment, various adsorption treatments, etc., more preferably pure water, especially ultrapure water. The concentration (content) of water in the etching solution is a residual portion 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.
In addition, as long as the pH is within a range that does not significantly change, a small amount of alkali may be added.
Furthermore, in the etching solution of the present invention, known hydrogen peroxide stabilizers such as alcohols, phenylureas, organic carboxylic acids, organic amine compounds, etc., and etching rate adjusters may be added as needed.
The etching solution of the present invention is preferably a dissolving solution and does not contain solid particles such as abrasive particles.

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

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

[Use of etching solution]
The etching solution of the present invention is applicable to etching of copper foil. For example, the etching solution of the present invention is applicable to the etching of copper foil in the ETS method. In addition, the etching solution of the present invention can be used for other applications requiring copper foil etching in addition to the copper foil etching by the ETS method.
According to an ideal aspect of the present invention, by using the etching solution of the present invention for etching, the etching speed and the wiring shape become better. In addition, when the copper foil is etched by the ETS method, the copper foil can be etched while suppressing the occurrence of side etching of the copper wiring, and a printed wiring board corresponding to the miniaturization of the wiring can be obtained.

The copper foil to be etched is not particularly limited, and 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, and more preferably 1.5 to 3 μm.
The etching rate of copper foil (also known as "etching rate") is not particularly limited. It is preferably 1 to 40 μm / min, more preferably 5 to 30 μm / min, and more preferably 5 to 20 μm at a liquid temperature of 30 ° C. / min. When the etching rate is 1 to 40 μm / min, a stable etching operation can be performed while maintaining high production efficiency.

2. Copper foil etching method The etching method of the present invention includes the step of etching the copper foil using the aforementioned etching solution of the present invention. The etching method of the present invention is particularly applicable to the etching of copper foil in the ETS method.

The use temperature of the etching solution of the present invention is not particularly limited, and is preferably a temperature of 10 to 50 ° C, more preferably 20 to 45 ° C, and still more preferably 25 to 40 ° C. If the temperature of the etching solution is 10 ° C or higher, the etching rate will be improved, and excellent production efficiency can be obtained. On the other hand, if the temperature of the etching solution is 50 ° C. or lower, changes in the liquid composition can be suppressed, and the etching conditions can be kept constant. By increasing the temperature of the etching solution, the etching rate will increase. Taking into consideration that the composition change of the etching solution (for example, decomposition of hydrogen peroxide) is kept small, the optimum processing temperature may be appropriately determined.

In addition, the etching processing time is not particularly limited, but is preferably 1 to 600 seconds, more preferably 5 to 300 seconds, still more preferably 10 to 180 seconds, and particularly preferably 15 to 120 seconds. The processing time may be appropriately selected depending on various conditions such as the state of the copper foil surface, the concentration of the etching solution, the temperature, and the processing method.

The method for bringing the etching solution of the present invention into contact with an object to be etched is not particularly limited. For example, a wet method such as a method in which an etching solution is dropped (single-piece rotation processing) or spray coating (spray processing) and the method is used to contact the etching target, or a method of immersing the etching target in the etching solution is used. ) Etching method. In the etching method of the present invention, any method may be used.

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

3. Manufacturing method of printed wiring board The manufacturing method of printed wiring board of the present invention includes the aforementioned ETS method, which uses the etching solution of the present invention to etch copper foil.

FIG. 1 is a diagram showing an example of steps of a method for manufacturing a printed wiring board using the ETS method.
First, as shown in FIG. 1 (a), a carrier foil (2) and a copper foil (3) are laminated on a detach core (support substrate for circuit formation) (1). For detaching the 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 metal-coated resin film, and a glass plate. The copper foil (3) is preferably an electrolytic copper foil.
In addition, other articles with equivalent functions can be used instead of the detachable core and the copper foil with a carrier foil.

Then, a dry film photoresist layer is formed on the surface of the copper foil (3), and exposed and developed to form a photoresist pattern (4) as shown in FIG. 1 (b).
Then, as shown in FIG. 1 (c), copper plating (5) is applied to the exposed portion of the copper foil (3) where the photoresist pattern (4) is not formed. Copper plating can be either electroplated copper or electroless copper, and it should be electroplated copper in view of cost and productivity.
Then, as shown in FIG. 1 (d), the photoresist pattern (4) is peeled by a peeling liquid to form a copper wiring (5 a).

Then, as shown in FIG. 1 (e), the obtained structure is inverted, and the wiring (5a) is buried in the interlayer insulating resin (6). The interlayer insulating resin (6) is not particularly limited as long as it is a manufacturer generally used for printed wiring boards.
Thereafter, as shown in FIG. 1 (f), the detached core (1) and the 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) formed with copper wiring (5a).

According to an ideal aspect of the present invention, in the ETS method, by using the etching solution of the present invention to etch the copper foil, the side etching of the copper wiring (5a) along the side wall of the interlayer insulating resin (6) can be suppressed, The copper foil (3) is etched while the printed wiring board (10) corresponding to the miniaturization of wiring can be manufactured. According to an ideal aspect of the present invention, a printed wiring board (10) corresponding to miniaturization of wiring can be manufactured without using special equipment.

4. Etching solution for electrolytic copper layer The etching solution for electrolytic copper layer of the present invention is characterized by containing hydrogen peroxide (A), sulfuric acid (B), and selected from the group consisting of 5-amino-1H-tetrazole, 1,5 -At least one azole compound (C) in the group consisting of pentamethylenetetrazole and 2-n-undecylimidazole, the molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is between In the range of 6 to 30, the concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass, and the etching solution for copper foil does not substantially contain phosphoric acid.

The etching solution of the present invention is used for etching an electrolytic copper layer. According to an ideal aspect of the present invention, the etching solution of the present invention can suppress the electrolytic copper layer in the manufacturing step of the copper pillar using the method of forming a copper pillar by electroplating copper by containing the above-mentioned components at a specific ratio. When the surface is etched, the electrolytic copper layer is etched sideways, and flat etching 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 "1. Etching solution for copper foil", and the same applies to the content and specific examples of each component, and further to any component.

The etching solution of the present invention can be used for etching the electrolytic copper layer. For example, the etching solution of the present invention is applicable to the etching of an electrolytic copper layer in a manufacturing process of a copper pillar using a method for forming a copper pillar by electroplating copper. In addition, the etching solution of the present invention can also be used in other applications (such as the formation of wiring circuits) that require etching of an electrolytic copper layer.
According to an ideal aspect of the present invention, by using the etching solution of the present invention for the etching treatment, the etching speed of copper, the shape of the copper pillars, and the surface shape become better. In addition, in a manufacturing process of a copper pillar using a method for forming a copper pillar by electroplating copper, when the etching solution of the present invention is used to etch an electrolytic copper layer, it is possible to etch the electrolytic solution while suppressing side etching of the electrolytic copper layer. Copper layer, and can obtain copper pillars with desired shape and surface shape. As the shape and surface shape of the copper pillars become better, flip-chip mounting (flip-chip bonding) becomes easier.
In the present invention, the copper pillar is not particularly limited. The copper post is, for example, a connection terminal capable of flip-chip mounting, and also 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. The shape of the electrolytic copper layer to be etched is not particularly limited, and may be, for example, a cylindrical shape, a substantially angular shape, or a wiring shape. The thickness of the electrolytic copper layer is not particularly limited, but is generally 1.5 to 105 μm, preferably 1.5 to 10 μm, and more preferably 1.5 to 8 μm.
The etching rate (also called "etching rate") of the electrolytic copper layer is not particularly limited. It is preferably 1 to 40 μm / min, more preferably 5 to 30 μm / min, and more preferably 5 at a liquid temperature of 30 ° C. ~ 20μm / min. If the etching rate is 1 to 40 μm / min, the high productivity can be maintained, and the etching operation can be performed stably.

5. Etching method of electrolytic copper layer The etching method of the present invention includes the step of etching the electrolytic copper layer using the aforementioned etching solution of the present invention. The etching method of the present invention is particularly suitable for etching an electrolytic copper layer in a manufacturing process of a copper pillar using a method for forming a copper pillar by electroplating copper.

The use temperature of the etching solution of the present invention is not particularly limited, and is preferably a temperature of 10 to 50 ° C, more preferably 20 to 45 ° C, and still more preferably 25 to 40 ° C. If the temperature of the etching solution is 10 ° C. or higher, the etching rate becomes good, and therefore excellent production efficiency can be obtained. On the other hand, if the temperature of the etching solution is 50 ° C. or lower, changes in the liquid composition can be suppressed, and the etching conditions can be kept constant. By setting the temperature of the etching solution to be high, the etching rate will be increased, and the optimum processing temperature may be appropriately determined, taking into consideration that the composition change of the etching solution (eg, decomposition of hydrogen peroxide) is kept small.

In addition, the etching treatment time is not particularly limited, but is preferably 1 to 600 seconds, more preferably 5 to 300 seconds, still more preferably 10 to 180 seconds, and particularly preferably 15 to 120 seconds. The processing time may be appropriately selected according to various conditions such as the desired height of the electrolytic copper layer, the state of the surface of the electrolytic copper layer, the concentration of the etching solution, the temperature, and the processing method.

The method for bringing the etching solution of the present invention into contact with an object to be etched is not particularly limited. For example, a wet method such as a method in which an etching solution is brought into contact with an etching target by dripping (single-piece rotation processing) or spraying (spraying processing), or a method in which the etching target is immersed in the etching solution (such as wet) etching method. In the etching method of the present invention, any method may be adopted.

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 to be etched by the etching method of the present invention is as described in the aforementioned "4. Etching solution for electrolytic copper layer".

6. Manufacturing method of copper pillar The manufacturing method of the copper pillar of the present invention includes a step of etching the electrolytic copper layer using the aforementioned etching solution of the present invention in the manufacturing step of the copper pillar.

FIG. 2 is a diagram showing an example of steps of a manufacturing method of a copper pillar using a method of forming a copper pillar by electroplating copper.
The following is an example of a method for forming a copper pillar by electroplating copper, and is not limited thereto.
First, as shown in FIG. 2 (a), a resin substrate (11) having a copper wiring (11b) provided in a gap between the interlayer insulating resin (11a) is prepared. The resin substrate (11) may be formed on a wafer as a part of a structure of a semiconductor wafer (semiconductor element), or may be formed on a package substrate as a part of a structure of a package substrate (printed wiring board) for mounting a semiconductor element.

Then, as shown in FIG. 2 (b), electroless copper plating is applied on the surface of the resin substrate (11) to form a chemical copper layer (12).
Then, a dry film photoresist layer is formed on the surface of the chemical copper layer (12), and exposed and developed to form a photoresist pattern (13) as shown in FIG. 2 (c).
Thereafter, electroplated copper is applied to the exposed portion of the chemical copper layer (12) where the photoresist pattern (13) is not formed, and as shown in FIG. 2 (d), an electrolytic copper layer (14) is formed. In order to make the height of the obtained copper pillars average, the electrolytic copper layer (14) is usually formed until it exceeds the height of the photoresist pattern (13). Thereafter, it should be polished by chemical mechanical polishing and adjusted to the photoresist pattern ( 13) The same height.
Then, the surface of the electrolytic copper layer (14) is etched by using the etching solution of the present invention. As shown in FIG. 2 (e), the height of the electrolytic copper layer (14) is adjusted to be higher than the height of the photoresist pattern (13). Lower. If the height of the electrolytic copper layer (14) is equal to the height of the photoresist pattern (13), there may be cases where copper remains on the photoresist pattern (13), and the next photoresist pattern (13) When peeling becomes difficult. Therefore, it is suitable to perform treatment until the height of the electrolytic copper layer (14) is lower than the height of the photoresist pattern (13), and completely remove the copper on the photoresist pattern (13). In addition, by performing an etching process until the height of the electrolytic copper layer (14) is lower than the height of the photoresist pattern (13), it is also possible to form another metal layer on the electrolytic copper layer (14). The height of the electrolytic copper layer (14) can be appropriately selected according to the purpose or application.
Finally, as shown in FIG. 2 (f), the photoresist pattern (13) is peeled using a stripping solution, so that a copper pillar (15) can be formed on the resin substrate (11) and the chemical copper layer (12). After that, the chemical copper layer (12) of the portion where no copper pillars (15) are formed can be removed by rapid etching.

According to an ideal aspect of the present invention, in a manufacturing step of a copper pillar using a method for forming a copper pillar by electroplating copper, an electrolytic copper layer (14) is etched by using an etching solution of the present invention (FIG. 2 ( e)), the side of the electrolytic copper layer (14) along the side wall of the photoresist pattern (13) can be prevented from being etched, or the electrolytic copper layer (14) can be etched while suppressing the occurrence of side etching, which can be manufactured with good efficiency A copper pillar (15) having a desired shape and surface shape. When the electrolytic copper layer (14) is side-etched, the reliability of the electrical connection between the copper pillars will be reduced, or it is necessary to design the connection area of the pillar diameter to be large in consideration of the side etching, which is not suitable for the high density of the copper pillars. However, according to an ideal aspect of the present invention, connection terminals for flip-chip mounting can be formed at a desired position on the substrate, even if the pitch is narrower. Therefore, it can respond to the height of mounted components such as semiconductor devices. Requirements for density and high volume.
[Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the embodiments can be appropriately changed within the scope of the effect of the present invention.

[Production of evaluation substrate (resin substrate provided 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. 1 (f).
Using the ETS method, a substrate with a copper foil (3) of FIG. 1 (f), in which a copper foil with a thickness of 5 μm was laminated on the prepreg, was prepared as follows, and used as an evaluation substrate.
The evaluation substrate was produced as follows.
First, a carrier with a very thin copper foil (equivalent to copper foil (3)) with a thickness of 5 μm is attached to a 100 μm detachable core (base material: “HL-832NSF”) (manufactured by Mitsubishi Gas Chemical Co., Ltd.) The ultra-thin copper foil "MT18SD-H-T5" (manufactured by Mitsui Metals Mining Co., Ltd.) was laminated so as to contact the carrier foil side.
Then, the dry film photoresist was laminated on the ultra-thin copper foil side of the laminated substrate, and the dry film photoresist was exposed with a line / space pattern (L / S) = 10/10 μm wiring design. The exposed dry film photoresist was developed using an aqueous sodium carbonate solution to form a photoresist pattern, and then a plating pattern was performed so that the wiring height became 10 μm.
After the pattern plating, the photoresist pattern was peeled using a dry film stripping solution "R-100S" (manufactured by Mitsubishi Gas Chemical Co., Ltd.) to form copper wiring.
The copper wiring was laminated to a prepreg "GHPL-830NS SH65" (manufactured by Mitsubishi Gas Chemical Co., Ltd.). Also, although not shown in the figure, it is used for laminating a prepreg and is laminated on the outer side of the prepreg with a copper foil on the side opposite to the copper wiring. The copper foil "MT18Ex" (manufactured by Mitsui Metals Mining Co., Ltd.) is used so that a copper foil of 5 μm becomes the prepreg side. After that, the detached core and the carrier foil are peeled off to produce a substrate with a copper foil (3) as shown in FIG. 1 (f).
The obtained substrate was cut into a size of 30 mm × 30 mm with the processing design portion as the center, to obtain a substrate for evaluation. In addition, copper wiring was formed in the prepreg of the evaluation substrate with a pitch of 20 μm and a wiring width of 10 to 10.5 μm.

[Evaluation of the amount of side etching]
The evaluation of the side etching amount is judged from the cross-sectional shape of the wiring after the etching.
A scanning electron microscope ("S3700N-shaped (model)"; manufactured by Hitachi High-Tech Science Co., Ltd.) was used to observe the wiring cross-sections of the substrates obtained after etching in the examples and comparative examples. The acceleration voltage was 2 kV and the emission current was 10 μA). Based on the SEM image obtained, the amount of etching on the side of the wiring cross section was investigated. As shown in FIG. 4, the side etching amount was calculated | required, and it evaluated as follows. In the present specification, the "side etching amount" means the shortest distance from the upper end of the copper wiring to the resin in contact with the copper foil.
Excellent: Any value is less than 0.1 μm
Impossible: Any value is above 0.1μm.

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

[Example 1]
0.949 kg of pure water, 0.033 kg of hydrogen peroxide (A) (manufactured by Mitsubishi Gas Chemical Co., Ltd., 60% by mass product, molecular weight 34), 0.017 kg of sulfuric acid (B) (manufactured by Mitsubishi Gas Chemical Co., Ltd., 46% by mass of dilute sulfuric acid, molecular weight 98), and 0.0003 kg of 5-amino-1H-tetrazole (made by Masuda Chemical Industry Co., Ltd.) as the azole compound (C) were put into a glass beaker having a capacity of 1 L. The etching solution is prepared by stirring and making it a uniform state.
Using this etching solution, a copper foil with a thickness of 8 μm was etched at a liquid temperature of 30 ° C. and a spray pressure of 0.15 MPa.

In order to determine the processing time for etching copper foil with a thickness of 8 μm, the entire copper foil substrate (size 40mm × 40mm) was spray-coated at a liquid temperature of 30 ° C for 60 seconds, and the etching rate of copper dissolution amount per 60 seconds (hereinafter It is called "ER"), and the processing seconds are 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 number of seconds required to etch a copper foil with a thickness of 8 μm = 8 [μm] × [60 seconds] / ER [μm / min]
The evaluation substrate after the etching treatment was disconnected, and the cross section (wiring cross section) of the substrate was observed using a scanning secondary electron microscope. A scanning secondary electron microscope photograph of the cross section (wiring cross section) of the substrate is shown in FIG. 3. As shown in FIG. 3, when the etching is performed using the etching solution of Example 1, the occurrence of side etching can be suppressed, and the shape of the copper wiring is also good.

[Example 2]
Etching liquid was prepared in the same manner as in Example 1 except that the amount ratios described in Table 1 were used for phenylurea, and the substrates for evaluation were spray-treated, and the side etching amount was evaluated.

[Examples 3 and 4]
An etching solution was prepared in the same manner as in Example 1 except that the molar ratio of the component (A) was changed, and the molar ratios of the component (A) and the component (B) were changed to those described in Table 1. Evaluation was performed. After spraying the substrate, the amount of side etching was evaluated.

[Examples 5 and 6]
An etching solution was prepared in the same manner as in Example 1 except that the component (A) and the component (B) were used in the amount ratios described in Table 1. After the substrate for evaluation was spray-treated, the side etching amount was evaluated.

[Examples 7 and 8]
An etching solution was prepared in the same manner as in Example 1 except that the compounds described in Table 1 were used as the component (C), and the substrate for evaluation was spray-treated, and then the amount of side etching was evaluated.

[Example 9]
The component (C) was used in the amount ratios described in Table 1, and phenylurea was used in the amount ratios described in Table 1. An etching solution was prepared in the same manner as in Example 1, and the substrate for evaluation was spray-treated. 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. After the substrate for evaluation was spray-treated, the amount of side etching was evaluated. A scanning secondary electron microscope photograph of the cross section (wiring cross section) of the substrate is shown in FIG. 4. As shown in FIG. 4, when etching is performed using the etching solution of Comparative Example 1, side etching occurs, and copper wiring of a desired shape cannot be obtained.

[Comparative Example 2]
An etching solution was prepared in the same manner as in Example 2 except that the component (C) was not used. After the substrate for evaluation was spray-treated, the amount of side etching was evaluated.

[Comparative Examples 3 to 8]
An etching solution was prepared in the same manner as in Example 1 except that the molar ratio of the component (A) was changed, and the molar ratios of the component (A) and the component (B) were changed to those described in Table 1. After the substrate was spray-treated, the amount of side etching was evaluated.

[Comparative Examples 9, 10]
An etching solution was prepared in the same manner as in Example 1 except that the amount ratio of the (C) component was changed to those described in Table 1. After the substrate for evaluation was spray-treated, the side etching amount was evaluated.

[Comparative Examples 11 to 13]
An etching solution was prepared in the same manner as in Example 1 except that the acid described in Table 1 was used in place of the component (B) in the amount ratio shown in Table 1. After the substrate for evaluation was spray-treated, the side etching amount was evaluated. .

[Comparative Examples 14 to 21]
An etching solution was prepared in the same manner as in Example 1 except that the azole compound described in Table 1 was used in place of the component (C), and the substrate for evaluation was spray-treated, and the amount of side etching 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.

[Table 1]

[Table 2]

[table 3]

As shown in Table 1, any of the etching solutions of Examples 1 to 8 can etch the copper foil at a good etching rate, and the amount of side etching is suppressed, and the shape of the copper wiring after etching is 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, large side etching occurred on the copper wiring, and copper wiring of a desired shape could not be obtained. In Comparative Example 11, the center portion of the copper wiring was etched, and a desired wiring shape could not be obtained.

The above example shows that in the copper foil etching in the ETS method, side etching will not occur on the copper foil using the etching solution of the present invention. The copper foil in the ETS method and the copper pillars formed by electroplating copper are electrolytic copper. It can be considered that the same etching reaction will be carried out chemically, so it can be considered that the side etching of the electrolytic copper layer can also be suppressed in the manufacturing process of the copper pillar.
[Industrial availability]

The etching solution of the present invention can be used as an etching solution for a copper foil or an electrolytic copper layer. In particular, the etching solution of the present invention is applicable to the etching of copper foil in the ETS method. According to an ideal aspect of the present invention, by using the etchant of the present invention, in the ETS method, side etching of copper wiring can be suppressed while copper foil is etched, and a printed wiring board corresponding to the miniaturization of wiring can be manufactured. . In addition, the etching solution of the present invention is applicable to the etching of an electrolytic copper layer in a manufacturing process of a copper pillar using a method of forming a copper pillar by electroplating copper. According to an ideal aspect of the present invention, by using the etching solution of the present invention, in the manufacturing steps of the copper pillar, the electrolytic copper layer can be inhibited from being side-etched while the electrolytic copper layer is etched, and a desired shape can be manufactured. Copper pillar.

1‧‧‧ Detach the core

2‧‧‧ carrier foil

3‧‧‧ copper foil

4‧‧‧Photoresist 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‧‧‧Photoresist pattern

14‧‧‧ electrolytic copper layer

15‧‧‧ copper pillar

[Fig. 1] (a) to (g) are diagrams showing an example of the steps of a method for manufacturing a printed wiring board using the ETS method.

[Fig. 2] (a) to (f) are diagrams showing an example of steps of a manufacturing method of a copper pillar using a method of forming a copper pillar by electroplating copper.

[Fig. 3] This is a scanning secondary electron microscope photograph of a wiring cross section when the copper foil is etched using the etching solution of Example 1.

[Fig. 4] This is a scanning secondary electron microscope photograph of a wiring cross section when the copper foil is etched using the etching solution of Comparative Example 1. [Fig.

[Fig. 5] It is an explanatory diagram for explaining a side etching amount of a copper wiring.

Claims (12)

An etching solution for copper foil, containing hydrogen peroxide (A), sulfuric acid (B), and selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole, and 2-n-undecyl At least one azole compound (C) in the group consisting of imidazole, The molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is in the range of 6 to 30. The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass. The etching solution for copper foil contains substantially no phosphoric acid. For example, the copper foil etching solution in the scope of the first patent application, wherein the concentration of the hydrogen peroxide (A) is in the range of 0.5 to 20% by mass. For example, the copper foil etching solution for item 1 or 2 of the patent application range, wherein the concentration of the sulfuric acid (B) is in the range of 0.3 to 5 mass%. For example, the copper foil etching solution according to any one of claims 1 to 3 is used for etching copper foil in the Embedded Trace Substrate method (ETS method). A copper foil etching method includes a step of etching a copper foil using an etching solution for copper foil according to any one of claims 1 to 3 in an embedded circuit board method (ETS method). A method for manufacturing a printed wiring board includes a step of etching a copper foil using an etching solution for a copper foil according to any one of claims 1 to 3 in an embedded circuit board method (ETS method). An etching solution for an electrolytic copper layer, which contains hydrogen peroxide (A), sulfuric acid (B), and is selected from the group consisting of 5-amino-1H-tetrazole, 1,5-pentamethylenetetrazole, and 2-n-undecyl. At least one azole compound (C) in the group consisting of imidazole, The molar ratio of the hydrogen peroxide (A) to the sulfuric acid (B) is in the range of 6 to 30. The concentration of the azole compound (C) is in the range of 0.001 to 0.01% by mass. This etching solution for an electrolytic copper layer does not substantially contain phosphoric acid. For example, the etching solution for an electrolytic copper layer according to item 7 of the application, wherein the concentration of the hydrogen peroxide (A) is within a range of 0.5 to 20% by mass. For example, the etching solution for an electrolytic copper layer according to item 7 or 8 of the scope of patent application, wherein the concentration of the sulfuric acid (B) is in the range of 0.3 to 5 mass%. For example, an etching solution for an electrolytic copper layer in any one of the items 7 to 9 of the scope of application for a patent is used to etch the electrolytic copper layer in the manufacturing process of a copper pillar. An etching method of an electrolytic copper layer includes a step of etching an electrolytic copper layer using an etching solution for an electrolytic copper layer as described in any one of claims 7 to 9 in a manufacturing process of a copper pillar. A method for manufacturing a copper pillar includes the step of etching the electrolytic copper layer using an etching solution for an electrolytic copper layer according to any of claims 7 to 9 in a manufacturing process of the copper pillar.