Aqueous composition for copper etching, and etching method and method for producing substrate for semiconductor package using same

Abstract

The present invention relates to an aqueous composition for etching with which it is possible to selectively etch a seed layer that contains copper or a copper alloy and is formed through a sputtering method or electroless plating. An aqueous composition for copper etching according to the present invention is characterized by containing (A) hydrogen peroxide, (B) at least one selected from phosphoric acid and phosphonic acid, and (C) chloride ions, the mass ratio (A) / (B) of the (A) hydrogen peroxide and the (B) at least one selected from phosphoric acid and phosphonic acid being within the range of 0.03 to 0.7, the (C) chloride ion content being 1 to 500 ppm on the basis of the total amount of the aqueous composition, a compound having a disulfide bond or a mercapto group either being not contained or being contained at an amount less than 0.1 mass%, and the pH value being −1.0 to 1.5.

Description

Aqueous composition for copper etching, etching method using same, and method for manufacturing substrate for semiconductor package

[0001] The present invention relates to an aqueous composition for etching copper. The present invention also relates to an etching method and a method for manufacturing a substrate for a semiconductor package using the aqueous composition.

[0002] As semiconductors used in electronic devices become more powerful, copper wiring on semiconductor package substrates is becoming increasingly finer and denser. Furthermore, in high-speed data communications at high frequencies, such as those used in 5G, electrical signals are susceptible to transmission loss due to the roughness of the copper wiring surface, so copper wiring surfaces must be smoother. In the manufacture of semiconductor package substrates, a semi-additive process (hereinafter referred to as "SAP") is generally used to form fine copper wiring. SAP typically involves forming a seed layer containing copper or a copper alloy on an interlayer insulating material, forming a resist pattern on the surface, applying electrolytic copper plating, peeling off the resist pattern, and removing the exposed seed layer by etching to form copper wiring. Depending on the application, the seed layer containing copper or a copper alloy is formed by sputtering or electroless plating. Known etching solutions for copper or copper alloys include those described in Patent Documents 1 to 5, for example.

[0003] Japanese Patent Publication No. 2024-60565 Taiwan Patent No. I660030 Special Publication No. 2019-502824 Japanese Patent Publication No. 2015-120970 Japanese Patent No. 4632038

[0004] There is a need to provide an aqueous copper etching composition that can selectively etch a copper or copper alloy seed layer formed by sputtering or electroless plating.

[0005] The present inventors provide the following aqueous composition, an etching method using the same, and a method for manufacturing a substrate for a semiconductor package: [1] An aqueous composition for copper etching, comprising: (A) hydrogen peroxide, (B) at least one selected from phosphoric acid and phosphonic acid, and (C) chloride ions, wherein the mass ratio (A) / (B) of (A) hydrogen peroxide to (B) the at least one selected from phosphoric acid and phosphonic acid is in the range of 0.03 to 0.7, the content of (C) chloride ions is 1 to 500 ppm based on the total amount of the aqueous composition, the aqueous composition does not contain a compound having a disulfide bond or a mercapto group, or the content of the compound having a disulfide bond or a mercapto group is less than 0.1 mass%, and the aqueous composition has a pH value of -1.0 to 1.5. [2] The aqueous composition according to [1], containing, based on the total amount of the aqueous composition, (A) 0.5 to 30 mass% hydrogen peroxide, (B) 1 to 50 mass% at least one selected from phosphoric acid and phosphonic acid, and (C) 1 to 500 ppm chloride ions. [3] The aqueous composition according to [1] or [2], containing, based on the total amount of the aqueous composition, (A) 1 to 15 mass% hydrogen peroxide, (B) 10 to 40 mass% at least one selected from phosphoric acid and phosphonic acid, and (C) 1 to 200 ppm chloride ions. [4] The aqueous composition according to any one of [1] to [3], having a copper etching selectivity (copper seed layer / electrolytic copper plated layer) of 1.9 or more at a 50% overetching amount. [5] An etching method, comprising the step of etching a copper-containing seed layer formed by sputtering or electroless plating using the aqueous composition according to any one of [1] to [4]. [6] A method for manufacturing a substrate for a semiconductor package, comprising a step of etching a copper-containing seed layer formed by a sputtering method or electroless plating using the aqueous composition according to any one of [1] to [4].

[0006] The present invention provides an aqueous copper etching composition suitable for use in forming copper wiring on semiconductor package substrates. The present invention also provides an etching method using the aqueous composition and a method for manufacturing semiconductor package substrates. According to a preferred embodiment of the present invention, in forming copper wiring on semiconductor package substrates, etching using the aqueous composition of the present invention can selectively etch a copper or copper alloy seed layer (also referred to herein as a "copper seed layer") formed by sputtering or electroless copper plating while suppressing dissolution of a copper or copper alloy layer (also referred to herein as an "electrolytic copper plating layer"). According to a further preferred embodiment of the present invention, in forming copper wiring on semiconductor package substrates, removing the copper seed layer using the aqueous composition of the present invention can achieve one or more of the following: (i) reduced CD loss of the electrolytic copper plating layer; (ii) reduced surface roughness of the electrolytic copper plating layer; and (iii) suppressed undercut of the copper seed layer. Note that, as used herein, the term "copper alloy" is not particularly limited as long as it is copper to which one or more metallic or non-metallic elements have been added and has metallic properties. The copper concentration of the copper alloy is preferably 50 to 99.99 mass%, more preferably 60 to 99.99 mass%, even more preferably 70 to 99.99 mass%, and particularly preferably 80 to 99.99 mass%. Metal atoms other than copper contained in the copper alloy include zinc, tin, lead, aluminum, and nickel. Examples of copper alloys that are preferably used include brass, bronze, cupronickel, nickel silver, and beryllium copper.

[0007] 1 is a schematic diagram showing the side surface of a semiconductor package substrate before etching treatment used in evaluations in Examples and Comparative Examples, and FIG. 2 is a diagram showing the CD loss of an electrolytic copper plating layer and the roughness of the surface of the electrolytic copper plating layer caused by etching treatment in Examples and Comparative Examples.

[0008] The aqueous composition of the present invention will be specifically described below, but the present invention is not limited thereto and various modifications are possible without departing from the gist of the present invention.

[0009] <1. Aqueous Composition> The aqueous composition of the present invention contains at least (A) hydrogen peroxide, (B) at least one acid selected from phosphoric acid and phosphonic acid, and (C) chloride ions, wherein the mass ratio (A) / (B) of (A) hydrogen peroxide to (B) the at least one acid selected from phosphoric acid and phosphonic acid is in the range of 0.03 to 0.7, the content of (C) chloride ions is 1 to 500 ppm based on the total amount of the aqueous composition, the aqueous composition does not contain a compound having a disulfide bond or a mercapto group, or the content of the compound having a disulfide bond or a mercapto group is less than 0.1 mass%, and the aqueous composition has a pH value of -1.0 to 1.5.

[0010] According to a preferred embodiment of the present invention, the aqueous composition of the present invention can selectively etch a copper seed layer while suppressing dissolution of an electrolytic copper-plated layer in the formation of copper wiring on a substrate for a semiconductor package, thereby enabling selective removal of the copper seed layer from a laminate containing at least a copper seed layer and an electrolytic copper-plated layer. According to a further preferred embodiment of the present invention, the aqueous composition of the present invention can achieve one or more of the following: (i) reducing CD loss of the electrolytic copper-plated layer, (ii) reducing surface roughness of the electrolytic copper-plated layer, and (iii) suppressing undercut of the copper seed layer, thereby enabling the formation of fine and smooth copper wiring, and therefore can be suitably used for forming copper wiring on a substrate for a semiconductor package.

[0011] Each component contained in the aqueous composition of the present invention will be described in detail below.

[0012] (A) Hydrogen Peroxide In the aqueous composition of the present invention, hydrogen peroxide acts primarily as an oxidizing agent that oxidizes copper. The hydrogen peroxide contained in the aqueous composition is usually used as an aqueous solution of appropriate concentration, mixed with other components. The concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution is not particularly limited and may be, for example, 10 to 90%, preferably 35 to 60% in accordance with industrial standards. Hydrogen peroxide may contain up to about 0.01% by mass of a stabilizer; acceptable stabilizers include sulfuric acid and phosphoric acid. There are no limitations on the manufacturing process or source of hydrogen peroxide; for example, hydrogen peroxide manufactured by the anthraquinone method may be used.

[0013] The content of hydrogen peroxide is preferably 0.5 to 30 mass%, more preferably 0.5 to 20 mass%, even more preferably 1 to 15 mass%, and particularly preferably 1.0 to 15 mass%, 1.2 to 12 mass%, or 1.5 to 10 mass%, based on the total amount of the aqueous composition. The lower limit of the hydrogen peroxide content may be, for example, 0.5 mass%, 1.0 mass%, 1.1 mass%, 1.2 mass%, 1.3 mass%, 1.4 mass%, or 1.5 mass%, based on the total amount of the aqueous composition. The upper limit may be, for example, 30 mass%, 25 mass%, 20 mass%, 15 mass%, 10 mass%, 5 mass%, or 3 mass%, based on the total amount of the aqueous composition. The range of the hydrogen peroxide content can be selected from a range that combines the above-mentioned lower and upper limits. When the hydrogen peroxide content is within the above range, a good etching rate for the copper seed layer can be achieved and dissolution of the electrolytic copper plating layer can be suppressed.

[0014] (B) At least one selected from phosphoric acid and phosphonic acid. In the aqueous composition of the present invention, phosphoric acid and phosphonic acid mainly act as an etching agent for the copper seed layer oxidized by hydrogen peroxide. Phosphoric acid is represented by the chemical formula H ３ P.O. ４ Phosphonic acid is an inorganic acid represented by the chemical formula H ３ P.O. ３ The phosphoric acid and the phosphonic acid may be used alone or in combination of two or more.

[0015] The content of phosphoric acid and phosphonic acid is preferably 1 to 50 mass%, more preferably 5 to 45 mass%, even more preferably 10 to 40 mass%, and particularly preferably 10 to 35 mass%, 10 to 32 mass%, or 10 to 30 mass%, based on the total amount of the aqueous composition. The lower limit of the content of phosphoric acid and phosphonic acid may be, for example, 1.0 mass%, 2.0 mass%, 3.0 mass%, 4.0 mass%, 5.0 mass%, 6.0 mass%, 7.0 mass%, 8.0 mass%, 9.0 mass%, or 10.0 mass%, based on the total amount of the aqueous composition. The upper limit may be, for example, 50 mass%, 45 mass%, 40 mass%, 35 mass%, 30 mass%, 25 mass%, 20 mass%, or 15 mass%, based on the total amount of the aqueous composition. The range of the content of phosphoric acid and phosphonic acid can be selected from a range combining the above-mentioned lower and upper limits. When phosphoric acid and phosphonic acid are used in combination, the total content of the phosphoric acid and phosphonic acid may be within the above range, which allows for a good etching rate for the copper seed layer and suppresses dissolution of the electrolytic copper plating layer.

[0016] In the aqueous composition of the present invention, the mass ratio (A) / (B) of (A) hydrogen peroxide to (B) at least one selected from phosphoric acid and phosphonic acid is in the range of 0.03 to 0.7, preferably 0.04 to 0.6, more preferably 0.05 to 0.5, even more preferably 0.06 to 0.5, and particularly preferably 0.08 to 0.5. The lower limit of the mass ratio (A) / (B) may be, for example, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1, and the upper limit may be, for example, 0.7, 0.6, 0.5, or 0.4. The range of the mass ratio (A) / (B) can be selected from a range that combines the above-mentioned lower and upper limits. When the mass ratio (A) / (B) is in the above range, a good etching rate for the copper seed layer can be achieved and dissolution of the electrolytic copper plating layer can be suppressed.

[0017] (C) Chloride Ions: Chloride ions have the effect of reducing CD loss in the electrolytic copper plating layer. The chloride ion content is 1 to 500 ppm (0.0001 to 0.05 mass%), preferably 1 to 400 ppm, more preferably 1 to 200 ppm, even more preferably 1 to 150 ppm, and particularly preferably 1 to 100 ppm. The lower limit of the chloride ion content may be 1 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, etc., and the upper limit may be 500 ppm, 450 ppm, 400 ppm, 350 ppm, 300 ppm, 250 ppm, 200 ppm, 150 ppm, 100 ppm, etc. The chloride ion content range can be selected from the range combining the above-mentioned lower and upper limits. The chloride ion source is not particularly limited as long as it can supply chloride ions, and preferred examples include hydrochloric acid, ammonium chloride, sodium chloride, potassium chloride, calcium chloride, and cupric chloride. Among these, hydrochloric acid and sodium chloride are more preferred from the viewpoint of ease of availability. The chloride ion source may be used alone or in combination of two or more.

[0018] (D) Water The water contained in the aqueous composition of the present invention is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration, various adsorption treatments, etc., and pure water is more preferred, with ultrapure water being particularly preferred. The content of water in the aqueous composition is adjusted appropriately depending on the contents of other components in the aqueous composition, and is not particularly limited, but is, for example, 40 to 98 mass %, preferably 50 to 95 mass %, and more preferably 60 to 90 mass % based on the total amount of the aqueous composition.

[0019] In the aqueous composition of the present invention, the total content of (A) hydrogen peroxide, (B) at least one selected from phosphoric acid and phosphonic acid, and (D) water is preferably 95% by mass or more, more preferably 96% by mass or more, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.8% by mass or more, or 99.9% by mass or more, based on the total amount of the aqueous composition. In the aqueous composition of the present invention, the total content of (A) hydrogen peroxide, (B) at least one selected from phosphoric acid and phosphonic acid, (C) chloride ion, and (D) water is preferably 95% by mass or more, more preferably 96% by mass or more, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.8% by mass or more, or 99.9% by mass or more, based on the total amount of the aqueous composition.

[0020] (E) Additives The aqueous composition of the present invention may further contain additives such as hydrogen peroxide stabilizers, organic solvents, surfactants, chelating agents, antifoaming agents, alkalis, silicon-containing compounds, and pH adjusters in addition to the above components, as long as the effects of the aqueous composition of the present invention are not impaired. For example, known hydrogen peroxide stabilizers such as alcohols, urea, phenylurea, organic carboxylic acids, organic phosphonic acids, and organic phosphoric acids may be added as appropriate. These additives may be used alone or in combination of two or more.

[0021] The pH value of the aqueous composition of the present invention is in the range of -1.0 to 1.5, preferably -0.8 to 1.5, more preferably -0.5 to 1.5, even more preferably -0.5 to 1.2, and particularly preferably -0.5 to 1.0, -0.2 to 1.2, or -0.2 to 1.0. The pH value of the aqueous composition can be adjusted by appropriately adding a pH adjuster.

[0022] (F) Other Components The aqueous composition of the present invention does not contain a compound having a disulfide bond or a mercapto group, or the content of the compound having a disulfide bond or a mercapto group in the aqueous composition of the present invention is less than 0.1% by mass. These compounds have reducing properties and react with hydrogen peroxide, an oxidizing agent, which can cause a decrease in the concentration of hydrogen peroxide. Therefore, it is preferable that the aqueous composition of the present invention does not contain a compound having a disulfide bond or a mercapto group.

[0023] The aqueous composition of the present invention is preferably a solution, and preferably does not contain solid particles such as abrasive particles.

[0024] The aqueous composition of the present invention can selectively etch a copper seed layer while suppressing dissolution of the electrolytic copper plating layer, and therefore the aqueous composition of the present invention can be suitably used for removing a copper seed layer in the formation of copper wiring on a semiconductor package substrate having a copper seed layer and an electrolytic copper plating layer. According to a preferred embodiment of the present invention, by removing the copper seed layer using the aqueous composition of the present invention in the formation of copper wiring on a semiconductor package substrate, one or more of the following can be achieved: (i) reduction in CD loss of the electrolytic copper plating layer, (ii) reduction in surface roughness of the electrolytic copper plating layer, and (iii) suppression of undercut of the copper seed layer.

[0025] (i) The reduction in CD loss of the electrolytic copper plating layer can be evaluated by the copper etching selectivity (copper seed layer / electrolytic copper plating layer) at a 50% overetching amount (a time 1.5 times the Cu JET). The copper etching selectivity (copper seed layer / electrolytic copper plating layer) can be calculated according to the following formula (1) using the measurement method described below: copper seed layer thickness / both-side CD loss of electrolytic copper plating layer / 2 (1) In the aqueous composition of the present invention, the copper etching selectivity (copper seed layer / electrolytic copper plating layer) is preferably 1.9 or more, more preferably 2.0 or more, even more preferably 2.1 or more, and particularly preferably 2.5 or more.

[0026] Furthermore, (ii) the reduction in roughness of the surface of the electrolytic copper plating layer can be evaluated by the surface roughness Ra (nm) at 50% overetching. The surface roughness Ra (nm) is preferably 29 nm or less, more preferably 27 nm or less, even more preferably 24 nm or less, and particularly preferably 21 nm or less. The surface roughness Ra (nm) can be calculated by the measurement method described below.

[0027] Furthermore, (iii) the suppression of undercut in the copper seed layer can be evaluated by the amount of undercut measured by the measurement method described below. The amount of undercut in the copper seed layer is preferably 0.2 μm or less, more preferably 0.15 μm or less, and even more preferably 0.1 μm or less. Note that when an electrolytic copper plating layer is formed on the copper seed layer, undercut may occur in the electrolytic copper plating layer as well as the copper seed layer. However, according to a preferred embodiment of the present invention, undercut in both the copper seed layer and the electrolytic copper plating layer can be suppressed.

[0028] The aqueous composition of the present invention can be prepared by uniformly stirring (A) hydrogen peroxide, (B) at least one selected from phosphoric acid and phosphonic acid, (C) chloride ions, (D) water, and, if necessary, one or more additives (E). The method for stirring these components is not particularly limited, and any stirring method commonly used in the preparation of aqueous compositions can be used.

[0029] The aqueous composition of the present invention is suitable for use as an aqueous composition for etching a copper seed layer in the manufacture of a semiconductor package substrate. The aqueous composition of the present invention can selectively etch a copper seed layer while suppressing dissolution of the electrolytic copper plating layer, thereby enabling selective etching of the copper seed layer in the formation of copper wiring on a semiconductor package substrate comprising a copper seed layer and an electrolytic copper plating layer. Furthermore, according to a preferred embodiment of the present invention, the aqueous composition of the present invention enables the formation of fine and smooth copper wiring, and therefore can be suitable for use in the formation of copper wiring on a semiconductor package substrate.

[0030] 2. Etching Method The etching method of the present invention includes the step of etching a copper seed layer using the aqueous composition described above.

[0031] There are no particular restrictions on the temperature at which the aqueous composition is used in the etching step, but a temperature of 10 to 50°C is preferred, more preferably 20 to 45°C, and even more preferably 25 to 40°C. If the temperature of the aqueous composition is 10°C or higher, the etching rate is good, resulting in excellent production efficiency. On the other hand, if the temperature of the aqueous composition is 50°C or lower, changes in the liquid composition can be suppressed, and etching conditions can be maintained constant. Increasing the temperature of the aqueous composition increases the etching rate, but the optimal treatment temperature can be determined as appropriate, taking into consideration factors such as minimizing changes in the composition of the aqueous composition (decomposition of hydrogen peroxide).

[0032] Furthermore, there is no particular limit to the etching treatment time, but 10 to 150 seconds is preferred, and 30 to 120 seconds is more preferred. The treatment time may be appropriately selected depending on various conditions, such as the surface condition of the object to be etched, the concentration of the aqueous composition, the temperature, and the treatment method. For example, in the etching treatment of a copper seed layer, the treatment time can be set to the moment when the color of the exposed copper seed layer disappears (just etching time (JET)). If necessary, the treatment time may be set even longer than JET.

[0033] The etching target in the etching method of the present invention is not particularly limited as long as it contains a copper seed layer, but a laminate containing at least a copper seed layer and an electrolytic copper plating layer (i.e., a semiconductor package substrate before etching) is preferred. The method for contacting the etching target with the aqueous composition is not particularly limited. For example, wet etching methods such as contacting the etching target with the aqueous composition by dropping (single-wafer spin processing) or spraying the aqueous composition, or immersing the etching target in the aqueous composition can be used. Either method may be used in the present invention.

[0034] 3. Method for manufacturing a substrate for semiconductor package The method for manufacturing a substrate for semiconductor package of the present invention includes a step of etching a copper seed layer using at least the above-described aqueous composition. In one embodiment, the method for manufacturing a substrate for semiconductor package of the present invention includes the steps of: preparing a semiconductor substrate having, on its surface, a copper seed layer containing copper or a copper alloy formed by sputtering or electroless plating; forming a resist pattern having an opening pattern exposing a portion of the copper seed layer; forming a metal wiring layer containing at least an electrolytic copper plating layer on the surface of the copper seed layer exposed in the openings of the opening pattern of the resist pattern by electrolytic copper plating; removing the resist pattern; and contacting the exposed portion of the copper seed layer, obtained in the step of removing the resist pattern, without the electrolytic copper plating layer, with the aqueous composition to etch the exposed portion of the copper seed layer.

[0035] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0036] [Example 1] (A) Hydrogen peroxide (H ２ O ２ (B) Phosphoric acid, and (C) Sodium chloride were added to pure water and stirred to produce an aqueous composition for etching semiconductor package substrates. The addition rates of hydrogen peroxide, phosphoric acid, and sodium chloride were 1.5 mass%, 12 mass%, and 0.01 mass%, respectively, relative to the total amount of the aqueous composition for etching semiconductor package substrates. The pH of the aqueous etching composition was 0.8. The pH of the aqueous composition before etching was measured at 23°C using a benchtop pH meter (F-71) and a pH electrode (9615S-10D) manufactured by Horiba, Ltd.

[0037] [Examples 2 to 7 and Comparative Examples 1 to 12] Aqueous compositions for etching substrates for semiconductor packages were prepared by changing the components and amounts added as shown in Table 1. The additives used in Comparative Example 8 were as follows: Additive 1: "PEG400" (polyethylene glycol, molecular weight 400), obtained from Thermo Scientific Additive 2: "SPS" (bis-(3-sulfopropyl)-disulfide), obtained from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0038] [Evaluation] The aqueous compositions for etching substrates for semiconductor packages produced in Examples 1 to 7 and Comparative Examples 1 to 12 were evaluated for Cu JET (Just Etching Time), copper (Cu) etching selectivity (copper seed layer / electrolytic copper plating layer), surface roughness of the electrolytic copper plating layer after etching, the presence or absence of residues, and the presence or absence of undercut in the copper seed layer (Cu undercut) as follows.

[0039] [Evaluation Sample] A semiconductor package substrate 10 having the structure shown in FIG. 1 was used as the evaluation substrate. The semiconductor package substrate 10 includes a barrier metal layer 30 formed on a substrate 20, a copper seed layer 40 formed on the barrier metal layer 30, and a metal wiring layer 50 formed on the copper seed layer 40. A Ti layer (thickness: 0.1 μm) was used as the barrier metal layer 30. A sputtered copper layer (thickness: 0.15 μm) formed by sputtering was used as the copper seed layer 40. An electrolytic copper plating layer (thickness: 4 μm, wiring width: 2 μm, space width: 2 μm) formed by electrolytic copper plating was used as the metal wiring layer 50.

[0040] [Evaluation of Cu JET] The evaluation sample was placed in a size of 1 cm x 1 cm (immersion treatment area: 1 cm ２ ) was cut into a size of 1 / 4" x 1 / 4". Next, the evaluation sample was immersed in 50 g of the aqueous composition for etching semiconductor package substrates produced in Examples 1 to 7 and Comparative Examples 1 to 12 at 25°C for a predetermined time while being stirred with a stirrer at 350 rpm. During the immersion treatment, the evaluation sample was held with tweezers and positioned above the stirrer.

[0041] When the evaluation sample was immersed, the time required for the color of the substrate surface to change visually from orange to silver was measured and defined as Cu JET.

[0042] [Copper (Cu) Etching Selectivity] Evaluation samples were immersed in the aqueous compositions for etching semiconductor package substrates produced in Examples 1 to 7 and Comparative Examples 1 to 12 at 25°C for 1.5 times the Cu JET while stirring with a stirrer at 350 rpm. The evaluation samples after the immersion treatment were processed in a focused ion beam (FIB) device (Helios G4 UX (manufactured by Thermo Scientific)) to obtain cross sections of the wiring of the electrolytic copper plating layer. SEM images of the processed evaluation samples were then obtained using the Helios G4 UX (manufactured by Thermo Scientific). The Cu etching selectivity (copper seed layer / electrolytic copper plating layer) was calculated from the SEM images according to the following formula (1'): sputtered copper layer thickness (0.15 μm) / (CD loss on both sides of the electrolytic copper plating layer) / 2 (1')

[0043] [Surface Roughness of Electrolytic Copper Plating Layer After Etching] Evaluation samples were immersed in the aqueous compositions for etching semiconductor package substrates produced in Examples 1 to 7 and Comparative Examples 1 to 12 at 25°C for 1.5 times the time required for Cu JET (50% overetching (O.E.)) while stirring with a stirrer at 350 rpm. The evaluation samples after the treatment were observed with a laser microscope (VK-X3100) manufactured by Keyence Corporation, and the surface roughness of the electrolytic copper plating layer was measured. The surface of the electrolytic copper plating layer was scanned with a laser in a direction parallel to the wiring of the electrolytic copper plating layer over a distance of 73 μm, and the Ra (arithmetic mean roughness) value was measured. The same procedure was repeated at eight other locations on the wiring of the electrolytic copper plating layer, and the Ra values ​​were measured. The nine Ra values ​​were averaged to calculate the final Ra value.

[0044] [Presence or Absence of Residue] Evaluation samples were immersed in the aqueous compositions for etching semiconductor package substrates produced in Examples 1 to 7 and Comparative Examples 1 to 12 at 25°C for 1.5 times the Cu JET time (50% overetching (O.E.)) while stirring with a stirrer at 350 rpm. The evaluation samples after treatment were processed in an FIB device (Helios G4 UX (manufactured by Thermo Scientific)) to obtain cross sections of the electrolytic copper plating layer wiring. SEM images of the processed evaluation samples were then obtained using the Helios G4 UX (manufactured by Thermo Scientific). The SEM images were evaluated for the presence or absence of copper (Cu) residue at the bottom between the electrolytic copper plating layer wiring. In the table, the presence or absence of residue was indicated as "Yes" and "No," respectively.

[0045] [Amount of Cu Undercut] Evaluation samples were immersed in the aqueous compositions for etching semiconductor package substrates produced in Examples 1 to 7 and Comparative Examples 1 to 12 at 25°C for 1.5 times the Cu JET while stirring with a stirrer at 350 rpm. The evaluation samples after immersion were processed in an FIB device (Helios G4 UX (manufactured by Thermo Scientific)) to obtain cross sections of the electrolytic copper plating layer wiring. SEM images of the processed evaluation samples were then obtained using the Helios G4 UX (manufactured by Thermo Scientific). The SEM images were evaluated for the presence or absence of undercutting between the lower part of the electrolytic copper plating layer wiring and the copper seed layer. In the table, undercutting was indicated as "Yes" and no undercutting was indicated as "No."

[0046]

[0047] FIG. 2 is a diagram schematically showing the CD loss of an electrolytic copper plating layer and the roughness of the surface of the electrolytic copper plating layer (referred to as "Cu roughness" in the drawing).

[0048] As shown in Table 1, when etching was performed using the aqueous compositions of Examples 1 to 7, the copper seed layer was selectively etched while suppressing dissolution of the electrolytic copper plating layer. Furthermore, when etching was performed using the aqueous compositions of Examples 1 to 7, (i) CD loss of the electrolytic copper plating layer was reduced, (ii) surface roughness of the electrolytic copper plating layer was reduced, and (iii) undercut of the copper seed layer was suppressed. On the other hand, when etching was performed using the aqueous compositions of Comparative Examples 1 to 4 and 8 to 10, the copper etching selectivity was insufficient. Furthermore, in Comparative Examples 4, 5, 9, and 12, the surface roughness of the electrolytic copper plating layer could not be suppressed, and in Comparative Examples 3, 6, 7, 9, and 11, copper residue was present at the bottom between the electrolytic copper-plated wiring. Furthermore, in Comparative Example 8, not only was copper etching selectivity not achieved, but undercut occurred at the bottom of the electrolytic copper-plated wiring and the copper seed layer.

[0049] 10: Substrate for semiconductor package 20: Substrate 30: Barrier metal layer 40: Copper seed layer 50: Metal wiring layer

Claims

1. An aqueous composition for copper etching, comprising: (A) hydrogen peroxide; (B) at least one acid selected from phosphoric acid and phosphonic acid; and (C) chloride ions; wherein the mass ratio (A) / (B) of (A) hydrogen peroxide to (B) the at least one acid selected from phosphoric acid and phosphonic acid is in the range of 0.03 to 0.7; (C) the content of chloride ions is 1 to 500 ppm based on the total amount of the aqueous composition; the aqueous composition does not contain a compound having a disulfide bond or a mercapto group, or the content of the compound having a disulfide bond or a mercapto group is less than 0.1 mass%; and the aqueous composition has a pH value of -1.0 to 1.

5.

2. The aqueous composition according to claim 1, comprising, based on the total amount of the aqueous composition, (A) 0.5 to 30 mass% hydrogen peroxide, (B) 1 to 50 mass% of at least one selected from phosphoric acid and phosphonic acid, and (C) 1 to 500 ppm chloride ions.

3. The aqueous composition according to claim 1, comprising, based on the total amount of the aqueous composition, (A) 1 to 15 mass% hydrogen peroxide, (B) 10 to 40 mass% of at least one selected from phosphoric acid and phosphonic acid, and (C) 1 to 200 ppm chloride ions.

4. The aqueous composition according to claim 1, which has a copper etching selectivity (copper seed layer / electrolytic copper plated layer) of 1.9 or more at a 50% overetching amount.

5. An etching method comprising the step of etching a seed layer containing copper or a copper alloy formed by sputtering or electroless plating using the aqueous composition according to any one of claims 1 to 4.

6. A method for manufacturing a substrate for a semiconductor package, comprising the step of etching a seed layer containing copper or a copper alloy formed by sputtering or electroless plating using the aqueous composition according to any one of claims 1 to 4.

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