Method for manufacturing structure

Abstract

The present invention addresses the problem of providing a method for manufacturing a structure capable of achieving excellent post-exposure delay stability when used as an anisotropic conductive joining member. The method for manufacturing a structure of the present invention is a method for manufacturing a structure having: an insulating substrate made of an inorganic material; and a plurality of conductive paths made of a conductive member, which are insulated from each other penetrating the insulating substrate in the thickness direction, the method comprising a protruding step for bringing each of the conductive paths into contact with an organic acid-containing composition to form a protruding portion protruding from the surface of the insulating substrate, wherein each of the conductive paths has the protruding portion.

Description

Manufacturing method of the structure

[0001] The present invention relates to a method for manufacturing a structure.

[0002] Structures (devices) formed by filling micropores in an insulating substrate with a conductive material have recently attracted attention in the field of nanotechnology, and are expected to be used, for example, as anisotropically conductive bonding materials. This anisotropically conductive bonding material can be inserted between an electronic component such as a semiconductor element and a circuit board and electrically connected therebetween simply by applying pressure. Therefore, it is widely used as an electrical connection material for electronic components such as semiconductor elements, and as an inspection connector for functional testing. In particular, electronic components such as semiconductor elements are being significantly downsized. Conventional methods for directly connecting a wiring board, such as wire bonding, flip-chip bonding, and thermocompression bonding, cannot adequately ensure connection stability. Therefore, anisotropically conductive bonding materials are attracting attention as electronic connection materials.

[0003] As a microstructure that can be used for such an anisotropic conductive bonding member, for example, Patent Document 1 discloses a "1×10 ６ ~1 x 10 １０ / mm ２ The document states that "a microstructure is made of an insulating substrate having through micropores with a pore diameter of 10 to 500 nm at a density of 1000 nm, wherein the through micropores are filled with a metal at a filling rate of 30% or more, and a layer made of a polymer is provided on at least one surface of the insulating substrate" ([Claim 1]), and that natural oxidation of the metal is prevented by configuring the protruding portions of the filled metal (conductive paths) to be covered with a polymer layer (

[0038] ).

[0004] JP 2010-067589 A

[0005] The inventors have examined the microstructure described in Patent Document 1 and have found that there is room for improvement in terms of suppressing oxidation of the protruding portions of the conductive paths, i.e., in terms of the stability when used as an anisotropic conductive joining member.

[0006] Therefore, an object of the present invention is to provide a method for manufacturing a structure that can achieve excellent drag-and-place stability when used as an anisotropically conductive bonding member.

[0007] As a result of intensive research aimed at achieving the above object, the present inventors have found that a structure having excellent shelf stability can be produced by forming the protruding portions of each conductive path protruding from the surface of an insulating substrate while contacting the protruding portions with a composition containing an organic acid, and have thus completed the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0008] [1] A method for producing a structure having an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member that penetrate the insulating base material in the thickness direction and are insulated from one another, wherein each conductive path has a protruding portion that protrudes from the surface of the insulating base material, and the method includes a protruding step of forming the protruding portion by contacting the insulating base material with a composition containing an organic acid. [2] A method for producing a structure according to [1], wherein the organic acid contains an organic acid that does not contain a nitrogen atom. [3] A method for producing a structure according to [1] or [2], wherein the organic acid contains an oxycarboxylic acid. [4] A method for producing a structure according to [3], wherein the oxycarboxylic acid contains at least one selected from the group consisting of lactic acid, malic acid, citric acid, glycolic acid, 2-hydroxymalonic acid, and tartaric acid. [5] A method for producing a structure according to any one of [1] to [4], wherein the content of the organic acid relative to the total mass of the composition is 0.5 mass% or more.

[0009] As will be described below, the present invention can provide a method for producing a structure that can achieve excellent drag-and-place stability when used as an anisotropically conductive bonding member.

[0010] Fig. 1 is a schematic front view showing an example of a preferred embodiment of a structure produced by the method for producing a structure of the present invention, and Fig. 2 is a cross-sectional view taken along the line IB-IB in Fig. 1.

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the upper and lower limits. In this specification, the upper or lower limit of a numerical range described in a stepwise manner may be replaced with the upper or lower limit of another stepwise manner. In this specification, the upper or lower limit of a numerical range described in a stepwise manner may be replaced with a value shown in the Examples. In this specification, each component may be a single substance corresponding to the component, or two or more substances may be used in combination. When two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified.

[0012] [Method for manufacturing a structure] The method for manufacturing a structure of the present invention (hereinafter also abbreviated as "the manufacturing method of the present invention") is a method for manufacturing a structure having an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member that penetrate the insulating base material in the thickness direction and are insulated from one another (hereinafter also formally abbreviated as "the structure of the present invention"). Furthermore, each conductive path in the structure of the present invention has a protruding portion that protrudes from the surface of the insulating base material. The manufacturing method of the present invention further includes a protruding step of forming a protruding portion of each conductive path by contacting the insulating base material with a composition containing an organic acid.

[0013] In the present invention, as described above, a structure having excellent shelf stability can be produced by forming the protruding portions of each conductive path that protrude from the surface of the insulating substrate while contacting the insulating substrate with a composition containing an organic acid. The mechanism behind this is not clear in detail, but is presumed to be roughly as follows. That is, because the surface of the protruding portions of the conductive paths is made of a conductive material, oxidation progresses over time. It is believed that oxidation over time also progresses even when the protruding portions of the conductive paths are embedded in a polymer layer. In the present invention, by forming the protruding portions of the conductive paths while contacting the insulating substrate with a composition containing an organic acid, an antioxidant film is formed on the surface of the protruding portions of the conductive paths by the organic acid simultaneously with or immediately after the formation of the protruding portions of the conductive paths, thereby suppressing oxidation over time. As a result, it is believed that a structure having excellent shelf stability can be produced.

[0014] Next, the configuration of the structure of the present invention will be described with reference to FIGS. 1 and 2 . The structure 1 shown in FIGS. 1 and 2 includes an insulating substrate 2 and a plurality of conductive paths 3 made of a conductive material. As shown in FIGS. 1 and 2 , the conductive paths 3 are insulated from one another and penetrate the insulating substrate 2 in a thickness direction Z (Z1: the direction from the back surface to the front surface in FIG. 1 , Z2: the direction from the front surface to the back surface in FIG. 1 ). As shown in FIG. 2 , the conductive paths 3 have protruding portions 3a and 3b protruding from surfaces 2a and 2b of the insulating substrate 2, respectively, and an antioxidant film 4 is formed on the surfaces of the protruding portions 3a and 3b. Here, "insulated from one another" means that the conductive paths present inside the insulating substrate (in the thickness direction) are insulated from one another within the insulating substrate. Furthermore, the form in which the antioxidant film 4 is formed on the surfaces of the protruding portions 3a and 3b may be the form shown in Figure 2, i.e., the form in which the antioxidant film 4 is formed on the surfaces of the protruding portions 3a and 3b and on the surfaces 2a and 2b of the insulating substrate 2, or the form in which the antioxidant film 4 is formed only on the surfaces of the protruding portions 3a and 3b.

[0015] [Insulating Substrate] The insulating substrate of the structure of the present invention is made of an inorganic material and has an electrical resistivity (10 １４ There are no particular limitations on the insulating base material as long as it has a resistivity of about Ω cm. Note that the phrase "made of an inorganic material" does not limit the insulating base material to one made of only inorganic materials, but rather refers to an insulating base material whose main component is an inorganic material (50 mass % or more).

[0016] Examples of the insulating substrate include a metal oxide substrate, a metal nitride substrate, a glass substrate, a ceramic substrate (e.g., silicon carbide, silicon nitride, etc.), a carbon substrate (e.g., diamond-like carbon, etc.), a polyimide substrate, and composite materials thereof. The insulating substrate may also be a material in which a film is formed on an organic material having through holes with an inorganic material containing 50 mass % or more of a ceramic material or a carbon material.

[0017] In the present invention, the insulating substrate is preferably a metal oxide substrate, more preferably an anodized film of a valve metal, because micropores having a desired average opening diameter are formed as through-holes, and the conductive paths described below are easily formed. Specific examples of the valve metal include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, an anodized film of aluminum (substrate) is preferred because it has good dimensional stability and is relatively inexpensive.

[0018] In the present invention, the thickness of the insulating substrate (the portion indicated by reference numeral 6 in FIG. 2) is preferably 1 μm to 1000 μm, more preferably 5 μm to 500 μm, and even more preferably 10 μm to 300 μm. When the thickness of the insulating substrate is within this range, the insulating substrate becomes easy to handle. Here, the thickness of the insulating substrate refers to the average value of thicknesses measured at 10 points when the cross section of the structure is observed with a field emission scanning electron microscope.

[0019] Furthermore, in the present invention, the spacing between the conductive paths in the insulating substrate is preferably 5 nm to 800 nm, more preferably 10 nm to 200 nm, and even more preferably 20 nm to 60 nm. When the spacing between the conductive paths in the insulating substrate is within this range, the insulating substrate functions satisfactorily as an insulating partition wall. Here, the spacing between the conductive paths refers to the width between adjacent conductive paths (the portion indicated by reference numeral 7 in FIG. 2 ), and refers to the average value of the width between adjacent conductive paths measured at 10 points when the cross section of the structure is observed at 200,000 times magnification using a field emission scanning electron microscope.

[0020] [Conductive Paths] The conductive paths of the structure of the present invention are made of conductive materials, penetrate the insulating base material in the thickness direction, and are insulated from one another. The conductive paths have protruding portions that protrude from the surface of the insulating base material, and an antioxidant film (described later) is formed on the surface of the protruding portion of each conductive path.

[0021] <Conductive Member> The conductive member constituting the conductive path has an electrical resistivity of 10 ３ There are no particular limitations on the material as long as it has a resistivity of Ω cm or less, and specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni), indium-doped tin oxide (ITO), etc. Among these, from the viewpoint of electrical conductivity, copper, gold, aluminum, and nickel are preferred, copper and gold are more preferred, and copper is even more preferred.

[0022] <Protruding Portion> The protruding portion of the conductive path is a portion where the conductive path protrudes from the surface of the insulating substrate, and an antioxidant film, which will be described later, is formed on the surface of the protruding portion.

[0023] In the present invention, when the structure is used as an anisotropic conductive bonding member, the aspect ratio of the protruding portion of the conductive path (height of the protruding portion / diameter of the protruding portion) is preferably 0.5 or more and less than 50, more preferably 0.8 to 20, and even more preferably 1 to 10, for the reason that sufficient insulation in the planar direction can be ensured in the event that the protruding portion is crushed when connecting (bonding) the structure to an electrode by a method such as crimping.

[0024] Furthermore, in the present invention, when the structure is used as an anisotropic conductive bonding member, from the viewpoint of conforming to the surface shape of the semiconductor chip or wiring substrate to be connected, the height of the protruding portion of the conductive path is preferably 50 nm to 3000 nm, more preferably 100 to 2000 nm, and even more preferably 200 to 1000 nm. Similarly, the diameter of the protruding portion of the conductive path is preferably greater than 5 nm and not greater than 10 μm, more preferably 20 nm to 1000 nm. Here, the height of the protruding portion of the conductive path refers to the average value obtained by observing the cross section of the structure with a field emission scanning electron microscope at a magnification of 20,000 times and measuring the height of the protruding portion of the conductive path at 10 points. Similarly, the diameter of the protruding portion of the conductive path refers to the average value obtained by observing the cross section of the structure with a field emission scanning electron microscope and measuring the diameter of the protruding portion of the conductive path at 10 points.

[0025] <Other Shapes> The conductive paths are columnar, and the diameter thereof (the portion indicated by reference numeral 8 in FIG. 2) is preferably more than 5 nm and not more than 10 μm, similar to the diameter of the protruding portion, and more preferably 20 nm to 1000 nm.

[0026] The conductive paths are insulated from one another by the insulating substrate, and their density is 20,000 / mm ２ It is preferable that the number of particles is 2 million or more per mm. ２ More preferably, it is 10 million particles / mm or more. ２ More preferably, it is 50 million particles / mm or more. ２ It is particularly preferable that the density is 100 million / mm or more. ２ This is most preferable.

[0027] Furthermore, the center-to-center distance between adjacent conductive paths (the portion indicated by reference numeral 9 in FIGS. 1 and 2) is preferably 20 nm to 500 nm, more preferably 40 nm to 200 nm, and even more preferably 50 nm to 140 nm.

[0028] [Antioxidation Film] In the structure of the present invention, an antioxidation film is formed on the surface of the protruding portion of the conductive path. Here, the antioxidation film is a film formed from a composition containing an organic acid used in the protruding step described below. The thickness of the antioxidation film is not particularly limited, but is preferably 0.1 to 10 nm, and more preferably 0.1 to 5 nm. The thickness of the antioxidation film refers to the average value of thicknesses measured at 10 points when the cross section of the structure is observed with a transmission electron microscope.

[0029] [Steps in the manufacturing method] The manufacturing method of the present invention is not particularly limited as long as it includes a protruding step of forming protruding portions of each conductive path by contacting a composition containing an organic acid. For example, the manufacturing method may include a conductive path forming step of causing a conductive material to be present in through holes provided in an insulating substrate to form conductive paths, and a protruding step of contacting a composition containing an organic acid to partially remove only the surface of the insulating substrate after the conductive path forming step, thereby forming protruding portions of the conductive paths.

[0030] <Preparation of insulating substrate> The insulating substrate can be, for example, a glass substrate (Through Glass Via: TGV) having a through hole as it is. However, from the viewpoint of setting the opening diameter of the conductive path and the aspect ratio of the protruding portion within the above-mentioned range, a method of subjecting a valve metal to anodizing treatment is preferred. For example, when the insulating substrate is an anodized aluminum film, the anodizing treatment can be performed by anodizing the aluminum substrate, and then, after the anodizing treatment, perforating the micropores formed by the anodizing treatment. In the present invention, the aluminum substrate used to prepare the insulating substrate and the respective treatment steps performed on the aluminum substrate can be similar to those described in paragraphs

[0041] to

[0121] of JP 2008-270158 A.

[0031] <Conductive Path Forming Step> The conductive path forming step is a step of filling the through holes formed in the insulating substrate with the conductive material. Examples of methods for filling the through holes include those described in paragraphs

[0123] to

[0126] and FIG. 4 of JP 2008-270158 A (electrolytic plating or electroless plating). In electrolytic plating or electroless plating, it is preferable to provide an electrode layer made of gold, nickel, copper, or the like in advance. Examples of methods for forming this electrode layer include gas-phase processes such as sputtering; liquid-phase processes such as electroless plating; and combinations of these processes. The metal filling step provides a structure before the formation of the protruding portions of the conductive paths.

[0032] On the other hand, instead of the method described in JP 2008-270158 A, the conductive path forming step may be a method including, for example, an anodizing step of anodizing one surface (hereinafter also referred to as "one side") of an aluminum substrate to form an anodized film on one side of the aluminum substrate, the anodized film having micropores present in the thickness direction and a barrier layer present at the bottom of the micropores; a barrier layer removal step of removing the barrier layer of the anodized film after the anodizing step; a metal filling step of performing electrolytic plating after the barrier layer removal step to fill the micropores with metal; and a substrate removal step of removing the aluminum substrate after the metal filling step to obtain a structure.

[0033] (Anodizing Treatment Step) The anodizing treatment step is a step of anodizing one side of the aluminum substrate to form an anodized film having micropores present in the thickness direction and a barrier layer present at the bottom of the micropores on one side of the aluminum substrate. The anodizing treatment in the manufacturing method of the present invention can be performed using a conventionally known method, but from the viewpoint of increasing the regularity of the micropore arrangement and ensuring anisotropic conductivity, it is preferable to use a self-ordering method or constant voltage treatment. Here, the self-ordering method and constant voltage treatment of the anodizing treatment can be the same as the respective treatments described in paragraphs

[0056] to

[0108] and [Figure 3] of JP 2008-270158 A.

[0034] (Barrier Layer Removal Step) The barrier layer removal step is a step of removing the barrier layer of the anodized film after the anodizing step. By removing the barrier layer, a portion of the aluminum substrate is exposed through the micropores. The method for removing the barrier layer is not particularly limited, and examples thereof include a method of electrochemically dissolving the barrier layer at a potential lower than the potential in the anodizing step (hereinafter also referred to as "electrolytic removal treatment"); a method of removing the barrier layer by etching (hereinafter also referred to as "etching removal treatment"); and a combination of these (particularly, a method of performing electrolytic removal treatment and then removing the remaining barrier layer by etching removal treatment).

[0035] <Electrolytic Removal Treatment> The electrolytic removal treatment is not particularly limited as long as it is an electrolytic treatment carried out at a potential lower than the potential (electrolytic potential) used in the anodizing treatment in the anodizing treatment step. In the present invention, the electrolytic dissolution treatment can be carried out continuously with the anodizing treatment, for example, by lowering the electrolytic potential at the end of the anodizing treatment step.

[0036] The electrolytic removal treatment can employ the same electrolytic solution and treatment conditions as those for the conventionally known anodizing treatment described above, except for the electrolytic potential. In particular, when the electrolytic removal treatment and the anodizing treatment are performed consecutively as described above, it is preferable to use the same electrolytic solution for the treatments.

[0037] The electrolytic potential in the electrolytic removal treatment is preferably lowered continuously or stepwise (in steps) to a potential lower than the electrolytic potential in the anodizing treatment. Here, the reduction width (step width) when the electrolytic potential is reduced stepwise is preferably 10 V or less, more preferably 5 V or less, and even more preferably 2 V or less, from the viewpoint of the withstand voltage of the barrier layer. Furthermore, the voltage reduction rate when the electrolytic potential is reduced continuously or stepwise is preferably 1 V / sec or less, more preferably 0.5 V / sec or less, and even more preferably 0.2 V / sec or less, from the viewpoint of productivity, etc.

[0038] <Etching Removal Treatment> The etching removal treatment is not particularly limited, and may be a chemical etching treatment in which dissolution is performed using an acid aqueous solution or an alkaline aqueous solution, or may be a dry etching treatment.

[0039] The barrier layer can be removed by chemical etching, for example, by immersing the structure after the anodizing process in an acidic or alkaline aqueous solution, filling the micropores with the acidic or alkaline aqueous solution, and then contacting the surface of the anodized film on the micropore opening side with a pH buffer solution, thereby selectively dissolving only the barrier layer.

[0040] When an acidic aqueous solution is used, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, or hydrochloric acid, or a mixture thereof. The concentration of the acidic aqueous solution is preferably 1 to 10% by mass. The temperature of the acidic aqueous solution is preferably 15 to 80°C, more preferably 20 to 60°C, and even more preferably 30 to 50°C. On the other hand, when an alkaline aqueous solution is used, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 10 to 60°C, more preferably 15 to 45°C, and even more preferably 20 to 35°C. The alkaline aqueous solution may contain zinc or other metals. Specifically, for example, a 50 g / L phosphoric acid aqueous solution at 40°C, a 0.5 g / L sodium hydroxide aqueous solution at 30°C, or a 0.5 g / L potassium hydroxide aqueous solution at 30°C is preferably used. As the pH buffer solution, a buffer solution corresponding to the above-mentioned acidic aqueous solution or alkaline aqueous solution can be used appropriately.

[0041] The immersion time in the acid or alkaline aqueous solution is preferably 8 to 120 minutes, more preferably 10 to 90 minutes, and even more preferably 15 to 60 minutes.

[0042] The dry etching process is performed using, for example, Cl ２ It is preferable to use a gas species such as a mixed gas of Ar and Ar.

[0043] (Metal Filling Step) The metal filling step is a step of filling the micropores in the anodized film with metal by performing an electrolytic plating process after the barrier layer removal step, and examples thereof include methods similar to those described in paragraphs

[0123] to

[0126] and [Figure 4] of JP 2008-270158 A (electrolytic plating method or electroless plating method). In the electrolytic plating method or electroless plating method, the aluminum substrate exposed through the micropores after the barrier layer removal step can be used as an electrode.

[0044] (Substrate Removal Step) The substrate removal step is a step of removing the aluminum substrate after the metal filling step to obtain a structure. Examples of a method for removing the aluminum substrate include a method of using a treatment liquid to dissolve only the aluminum substrate without dissolving the metal filled inside the micropores in the metal filling step or the anodized film serving as an insulating base material.

[0045] Examples of the treatment solution include aqueous solutions of mercury chloride, bromine / methanol mixtures, bromine / ethanol mixtures, aqua regia, and hydrochloric acid / copper chloride mixtures, with hydrochloric acid / copper chloride mixtures being preferred. The concentration of the treatment solution is preferably 0.01 to 10 mol / L, more preferably 0.05 to 5 mol / L. The treatment temperature is preferably −10° C. to 80° C., and more preferably 0° C. to 60° C.

[0046] <Protrusion Step> The protrusion step is a step that follows the conductive path forming step, in which a composition containing an organic acid (hereinafter also referred to as a "protrusion treatment liquid") is brought into contact with the insulating substrate to partially remove only the surface of the insulating substrate, thereby forming protruding portions of the conductive paths. Here, the organic acid refers to an organic compound having one or more acidic groups per molecule, and examples of the acidic group include a carboxyl group, a sulfonic acid group, and a phosphate group.

[0047] In the present invention, the organic acid preferably contains an organic acid having no nitrogen atoms, because this ensures sufficient bonding strength when the fabricated structure is used as an anisotropically conductive bonding member.

[0048] In the present invention, the organic acid preferably contains an oxycarboxylic acid because this improves shelf stability. Here, the oxycarboxylic acid refers to a compound having a carboxy group and a hydroxyl group in one molecule. Suitable examples of the oxycarboxylic acid include lactic acid, malic acid, citric acid, glycolic acid, 2-hydroxymalonic acid, and tartaric acid because this improves shelf stability. These may be contained alone or in combination of two or more.

[0049] Furthermore, in the present invention, the content of the organic acid is preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and even more preferably 0.7% by mass or more, based on the total mass of the projecting treatment solution, for the reason that the stability during storage is improved. The upper limit of the content of the organic acid is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total mass of the projecting treatment solution.

[0050] The composition containing an organic acid (protrusion treatment liquid) may contain an inorganic acid and / or a base in addition to the organic acid described above, as long as the organic acid does not dissolve the metal that constitutes the conductive paths. Specific examples of inorganic acids include sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid. Specific examples of bases include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide, strontium hydroxide, and barium hydroxide; and the like. When the protrusion treatment liquid contains an inorganic acid, the content of the inorganic acid is preferably 1 to 10% by mass, based on the total mass of the protrusion treatment liquid. When the protrusion treatment liquid contains a base, the content of the base is preferably 1 to 10% by mass, based on the total mass of the protrusion treatment liquid.

[0051] The composition containing an organic acid is preferably an aqueous solution containing the above-mentioned organic acid and any inorganic acid and / or base, and more preferably an aqueous solution containing the above-mentioned organic acid and / or base (particularly, an alkali metal hydroxide).

[0052] The method for contacting the sample with the organic acid-containing composition is not particularly limited, but examples include immersing the sample after the conduit formation step in the organic acid-containing composition. The immersion time in the organic acid-containing composition is not particularly limited, as it varies depending on the height of the protruding portion of the conduit to be formed. It is preferably 8 to 120 minutes, more preferably 10 to 90 minutes, and even more preferably 15 to 60 minutes. When short-term immersion treatments are repeated, the immersion time refers to the total immersion time. A cleaning treatment may be performed between each immersion treatment. The temperature of the organic acid-containing composition is not particularly limited, but it is preferably 15 to 60°C, more preferably 15 to 50°C, and even more preferably 15 to 40°C.

[0053]

[0033] <Optional Step> In the manufacturing method of the present invention, when the height of the protruding portion of the conductive path is to be strictly controlled in the protruding step, it is preferable to process the insulating substrate and the end of the conductive path so as to be flush with each other after the conductive path forming step, and then to remove only a portion of the surface of the insulating substrate by contacting it with a composition containing an organic acid. Here, examples of methods for processing the insulating substrate and the end of the conductive path to be flush with each other include physical polishing (e.g., free abrasive polishing, back grinding, surface planing, etc.), electrochemical polishing, and polishing using a combination of these.

[0054] Furthermore, in the manufacturing method of the present invention, after the above-mentioned conductive path forming step or protruding step, a heat treatment can be performed to reduce distortion in the conductive paths caused by filling with metal. The heat treatment is preferably performed in a reducing atmosphere to suppress oxidation of the metal, and more preferably in an oxygen concentration of 20 Pa or less, and more preferably in a vacuum. Here, vacuum refers to a space state in which the gas density or air pressure is lower than that of the atmosphere. Furthermore, the heat treatment is preferably performed while pressurizing the material for the purpose of straightening.

[0055] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0056] [Example 1] <Preparation of Aluminum Substrate> A molten aluminum alloy containing 0.06% by mass of Si, 0.30% by mass of Fe, 0.005% by mass of Cu, 0.001% by mass of Mn, 0.001% by mass of Mg, 0.001% by mass of Zn, and 0.03% by mass of Ti, with the remainder being Al and unavoidable impurities, was prepared. The molten aluminum alloy was then treated and filtered, and an ingot 500 mm thick and 1200 mm wide was produced by DC (Direct Chill) casting. The surface was then scraped off to an average thickness of 10 mm using a facing mill, and the ingot was then soaked at 550°C for approximately 5 hours. When the temperature dropped to 400°C, it was rolled into a 2.7 mm thick plate using a hot rolling mill. Further, the aluminum substrate was subjected to heat treatment at 500°C using a continuous annealing machine, and then cold-rolled to a thickness of 1.0 mm to obtain an aluminum substrate of JIS 1050. This aluminum substrate was cut to a width of 1030 mm and then subjected to the following treatments.

[0057] <Electrolytic Polishing Treatment> The aluminum substrate was subjected to electrolytic polishing treatment using an electrolytic polishing solution having the following composition under conditions of a voltage of 25 V, a solution temperature of 65°C, and a solution flow rate of 3.0 m / min. A carbon electrode was used as the cathode, and a GP0110-30R (manufactured by Takasago Machinery Co., Ltd.) was used as the power source. The flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation). (Electrolytic Polishing Solution Composition) 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 mL, pure water 160 mL, sulfuric acid 150 mL, and ethylene glycol 30 mL

[0058] <Anodizing Treatment Step> Next, the aluminum substrate after electrolytic polishing treatment was subjected to anodizing treatment by the self-ordering method according to the procedure described in JP 2007-204802 A. The aluminum substrate after electrolytic polishing treatment was subjected to a pre-anodizing treatment for 5 hours in a 0.50 mol / L oxalic acid electrolytic solution under conditions of a voltage of 40 V, a solution temperature of 16 ° C, and a solution flow rate of 3.0 m / min. Thereafter, the aluminum substrate after pre-anodizing treatment was subjected to a film removal treatment by immersing it in a mixed aqueous solution (liquid temperature: 50 ° C) of 0.2 mol / L chromic anhydride and 0.6 mol / L phosphoric acid for 12 hours. Thereafter, a re-anodizing treatment was performed for 3 hours and 45 minutes in a 0.50 mol / L oxalic acid electrolytic solution under conditions of a voltage of 40 V, a solution temperature of 16 ° C, and a solution flow rate of 3.0 m / min, to obtain an anodized film with a film thickness of 30 μm. In both the pre-anodizing treatment and the re-anodizing treatment, a stainless steel electrode was used as the cathode, and a GP0110-30R power supply (manufactured by Takasago Machinery Co., Ltd.) was used. A NeoCool BD36 (manufactured by Yamato Scientific Co., Ltd.) was used as the cooling device, and a Pair Stirrer PS-100 (manufactured by EYELA Tokyo Rikakikai Co., Ltd.) was used as the stirring / heating device. Furthermore, the flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation).

[0059] <Barrier Layer Removal Step> After the anodizing step, the aluminum substrate was subjected to an etching treatment by immersion in an alkaline aqueous solution prepared by dissolving zinc oxide in a sodium hydroxide aqueous solution (50 g / L) to a concentration of 2000 ppm at 30°C for 150 seconds, thereby removing the barrier layer at the bottom of the micropores in the anodized film and simultaneously depositing zinc on the exposed surface of the aluminum substrate. The average thickness of the anodized film after the barrier layer removal step was 30 µm.

[0060] <Metal Filling Step> Next, electrolytic plating was performed using the aluminum substrate as the cathode and platinum as the cathode. Specifically, a copper plating solution having the composition shown below was used, and constant-current electrolysis was performed to produce a structure in which nickel was filled into the interior of the micropores. Here, constant-current electrolysis was performed using a plating device manufactured by Yamamoto Plating Tester Co., Ltd. and a power supply (HZ-3000) manufactured by Hokuto Denko Corporation. After confirming the deposition potential by performing cyclic voltammetry in the plating solution, the process was performed under the conditions shown below. (Copper Plating Solution Composition and Conditions) Copper sulfate 100 g / L Sulfuric acid 50 g / L Hydrochloric acid 15 g / L Temperature 25°C Current density 10 A / dm ２

[0061] <Protrusion Step (Surface)> The structure after the metal filling step was immersed in a protrusion treatment solution prepared by dissolving citric acid to a concentration of 1 mass % in an aqueous potassium hydroxide solution (concentration: 5 mass %, liquid temperature: 20°C). The immersion time was adjusted so that the height of the protruding portions would be 400 nm, thereby selectively dissolving the surface of the anodized aluminum film, causing the filling metal, copper, to protrude, and producing a structure in which an antioxidant film was formed on the surface of the protruding copper portions.

[0062] <Resin substrate forming step> A thermally peelable resin substrate with an adhesive layer (REVALPHA 3195MS, manufactured by Nitto Denko Corporation) was attached to the surface on the side where the aluminum substrate was not provided. This resin substrate is a substrate for supporting the structure produced in the above-mentioned "protrusion step (surface)" during the "substrate removal step" described below.

[0063] The aluminum substrate was then removed by immersion in a mixed solution of copper chloride and hydrochloric acid to produce a structure having an average thickness of 30 μm. The conductive paths in the structure had a diameter of 60 nm, a pitch of 100 nm, and a density of 57.7 million / mm.

[0064] <Protrusion Step (Back Side)> After the substrate removal step, the structure was immersed in a protrusion treatment solution prepared by dissolving citric acid to a concentration of 1 mass % in an aqueous sodium hydroxide solution (concentration: 5 mass %, liquid temperature: 20°C). The immersion time was adjusted so that the height of the protruding portions would be 400 nm, thereby selectively dissolving the surface of the anodized aluminum film, causing the copper filling metal to protrude, and producing a structure in which an antioxidant film was formed on the surface of the protruding copper portions.

[0065] <Thermal Peeling Step> After the protruding step (rear surface), the resin substrate was peeled off by heating at 110° C. for 1 minute in the atmosphere to prepare a structure.

[0066] [Examples 2 to 8 and Comparative Example 1] Structures were produced in the same manner as in Example 1, except that the type and concentration of the organic acid in the protrusion treatment solution used in the protrusion process (front surface) and the protrusion process (rear surface) were changed to those shown in Table 1 below.

[0067] [Storage Stability] Each of the fabricated structures was left in an atmospheric environment at 35°C for one month. Then, a cross section of each structure was cut using a focused ion beam (FIB) to obtain ultrathin sections. The obtained ultrathin sections were observed using a transmission electron microscope (TEM) to measure the thickness of the oxide film at the protruding portion of the conductive path. The storage stability was evaluated based on the oxide film thickness using the following criteria. <Evaluation Criteria> A: Oxide film thickness is 5 nm or less B: Oxide film thickness is more than 5 nm and less than 10 nm C: Oxide film thickness is more than 10 nm and less than 20 nm D: Oxide film thickness is more than 20 nm

[0068]

[0069] The results shown in Table 1 above indicate that when a composition containing an organic acid was not used in the protrusion process, the oxide film thickness exceeded 20 nm, resulting in poor shelf stability (Comparative Example 1). In contrast, when a composition containing an organic acid was used in the protrusion process, the oxide film thickness was 20 nm or less, resulting in poor shelf stability (Examples 1 to 8). In particular, comparison of Examples 1, 2, and 4 to 8 indicates that the shelf stability is improved when the organic acid is an oxycarboxylic acid. Furthermore, comparison of Example 1 and Example 3 indicates that the shelf stability is improved when the organic acid content is 0.5% by mass or more relative to the total mass of the protrusion treatment solution.

[0070] REFERENCE SIGNS LIST 1 Structure 2 Insulating substrate 2a, 2b Surface of insulating substrate 3 Conductive path 3a, 3b Protruding portion of conductive path 4 Antioxidant film 6 Thickness of insulating substrate 7 Spacing between conductive paths 8 Diameter of conductive path 9 Center-to-center distance (pitch) of conductive paths

Claims

1. A method for producing a structure having an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member that penetrate the insulating base material in the thickness direction and are insulated from one another, wherein each of the conductive paths has a protruding portion that protrudes from a surface of the insulating base material, and the method for producing a structure comprises a protruding step of contacting the insulating base material with a composition containing an organic acid to form the protruding portion.

2. The method for producing the structure according to claim 1, wherein the organic acid includes an organic acid having no nitrogen atom.

3. The method for producing the structure according to claim 1, wherein the organic acid includes a hydroxycarboxylic acid.

4. The method for producing a structure according to claim 3, wherein the oxycarboxylic acid includes at least one selected from the group consisting of lactic acid, malic acid, citric acid, glycolic acid, 2-hydroxymalonic acid, and tartaric acid.

5. A method for producing a structure according to any one of claims 1 to 4, wherein the content of the organic acid relative to the total mass of the composition is 0.5 mass% or more.

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