Abstract: The present disclosure provides a concentrate for use in chemical mechanical polishing slurries, and a method of diluting that concentrate to a point of use slurry. The concentrate comprises abrasive, complexing agent, and corrosion inhibitor, and the concentrate is diluted with water and oxidizer. These components are present in amounts such that the concentrate can be diluted at very high dilution ratios, without affecting the polishing performance.

Abstract: The present invention is directed to a microetching composition comprising a source of cupric ions, acid, a nitrile compound, and a source of halide ions. Other additive, including organic solvents, a source of molybdenum ions, amines, polyamines, and acrylamides may also be included in the composition of the invention. The present invention is also directed to a method of microetching copper or copper alloy surfaces to increase the adhesion of the copper surface to a polymeric material, comprising the steps of contacting a copper or copper alloy surface with the composition of the invention, and thereafter bonding the polymeric material to the copper or copper alloy surface.

Abstract: Chemical etching methods and associated modules for performing the removal of metal from the edge bevel region of a semiconductor wafer are described. The methods and systems apply liquid etchant in a precise manner at the edge bevel region of the wafer, so that the etchant is applied on to the front edge, the side edge and the back edge. The etchant thus does not flow or splatter onto the active circuit region of the wafer. An edge bevel removal embodiment involving that is particularly effective at obviating streaking, narrowing the metal taper and allowing for subsequent chemical mechanical polishing, is disclosed.

Abstract: A process for etching a metal or alloy surface which comprises applying an etch-resist ink by ink jet printing to selected areas of the metal or alloy, solidifying the etch-resist ink without the use of actinic light and/or particle beam radiation and then removing the exposed metal or alloy by a chemical etching process wherein the etch-resist ink comprises the components: A) 60 to 100 parts carrier vehicle comprising one or more components which contain at least one metal chelating group; D) 0 to 40 parts colorant; and E) 0 to 5 parts surfactant; wherein the ink has a viscosity of not greater than 30 cPs (mPa·s) at the firing temperature, all parts are by weight and the total number of parts A)+B)+C)=100.

Abstract: The present embodiments relate to an etchant and a method of fabricating an electric device including a thin film transistor. The etchant includes a fluorine ion (F?) source, hydrogen peroxide (H2O2), a sulfate, a phosphate, an azole-based compound, and a solvent. The etchant and method of fabricating an electric device including a thin film transistor, can etch a multi-layered film including copper layer, and a titanium or titanium alloy layer in a batch and can provide a thin film transistor having a good pattern profile at high yield. When reusing the etchant, uniform etching performance can be maintained with a long replacement period of the etchant, and therefore costs can be saved.

Abstract: A CMP composition containing a rheology agent, e.g., in combination with oxidizing agent, chelating agent, inhibiting agent, abrasive and solvent. Such CMP composition advantageously increases the materials selectivity in the CMP process and is useful for polishing surfaces of copper elements on semiconductor substrates, without the occurrence of dishing or other adverse planarization deficiencies in the polished copper.

Abstract: A composition that may be used for cleaning a metal containing conductor layer, such as a copper containing conductor layer, within a microelectronic structure includes an aqueous acid, along with an oxidant material and a passivant material contained within the aqueous acid. The composition does not include an abrasive material. The composition is particularly useful for cleaning a residue from a copper containing conductor layer and an adjoining dielectric layer that provides an aperture for accessing the copper containing conductor layer within a microelectronic structure.

Abstract: There is provided a method for removing molten and scattered Cu and overhang that are generated around a via opening during laser machining in a direct laser via forming method of directly machining an outer-layer copper foil. In a manufacturing method of a printed wiring board of machining the via by laser directly through the copper foil of a copper-clad laminate in which the copper foil is clad on a base material resin, a process for machining the via is carried out in a sequence of (a) a copper foil surface treatment step of forming an oxide film on the surface of said copper foil, (b) a laser via machining step, (c) an alkali treatment step and (d) a molten and scattered Cu etching step. It is desirable to carry out (e) a de-smearing treatment after the molten and scattered Cu etching.

Abstract: Provided are an etchant used for a transparent conductive oxide layer and a method for fabricating a liquid crystal display (LCD) using the etchant. The etchant includes 2-5 wt % sulfuric acid, 0.02-10 wt % hydrogen sulfate of alkali metal, and deionized water as the remainder.

Abstract: The present invention relates to a method of fabricating a nanogap and a nanogap sensor, and to a nanogap and a nanogap sensor fabricated using the method. The present invention relates to a method of fabricating a nanogap and a nanogap sensor, which can be realized by an anisotropic etching using a semiconductor manufacturing process. According to the method of present invention, the nanogap and nanogap sensor can be simply and cheaply produced in large quantities.

Abstract: Systematic and effective methodology to clean capacitively coupled plasma reactor electrodes and reduce surface roughness so that the cleaned electrodes meet surface contamination specifications and manufacturing yields are enhanced. Pre-cleaning of tools used in the cleaning process helps prevent contamination of the electrode being cleaned.

Abstract: An etchant for patterning composite layer containing copper is provided. The etchant includes peracetic acid being about 5% to 40% by weight and serving as a major component, a peracetic acid stabilizer being about 5% to 15% by weight, an organic acid being about 5% to 10% by weight, an inorganic acid being about 5% to 15% by weight, a salt being about 8% to 15% by weight, which are based on the total weight of the etchant.

Abstract: The invention is directed to a method and composition for providing chemically-resistant roughened copper surfaces suitable for subsequent multilayer lamination. In one embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, a topography modifier, and a sulfur-containing coating stabilizer. In another embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, and a topography modifier. Then, in a subsequent step, the roughened copper surface is contacted with an acid resistance promoting composition.

Abstract: Preferred embodiments provide a method for removing at least part of a copper comprising layer from a substrate, the substrate comprising at least a copper comprising surface layer. The method comprises in a first reaction chamber converting at least part of the copper comprising surface layer into a copper halide surface layer and in a second reaction chamber removing at least part of the copper halide surface layer by exposing it to a photon comprising ambient, thereby initiating formation of volatile copper halide products. During exposure to the photon comprising ambient, the method furthermore comprises removing the volatile copper halide products from the second reaction chamber to avoid saturation of the volatile copper halide products in the second reaction chamber. The method according to preferred embodiments may be used to pattern copper comprising layers.

Abstract: An electrochemical fabrication process for producing three-dimensional structures from a plurality of adhered layers is provided where each layer comprises at least one structural material (e.g. nickel) and at least one sacrificial material (e.g. copper) that will be etched away from the structural material after the formation of all layers have been completed. A copper etchant containing chlorite (e.g. Enthone C-38) is combined with a corrosion inhibitor (e.g. sodium nitrate) to prevent pitting of the structural material during removal of the sacrificial material. A simple process for drying the etched structure without the drying process causing surfaces to stick together includes immersion of the structure in water after etching and then immersion in alcohol and then placing the structure in an oven for drying.

Abstract: The present invention is directed to a microetching composition comprising a source of cupric ions, acid, a nitrile compound, and a source of halide ions. Other additive, including organic solvents, a source of molybdenum ions, amines, polyamines, and acrylamides may also be included in the composition of the invention. The present invention is also directed to a method of microetching copper or copper alloy surfaces to increase the adhesion of the copper surface to a polymeric material, comprising the steps of contacting a copper or copper alloy surface with the composition of the invention, and thereafter bonding the polymeric material to the copper or copper alloy surface.

Abstract: Disclosed is a method to construct a device that includes a plurality of nanowires (NWs) each having a core and at least one shell. The method includes providing a plurality of radially encoded NWs where each shell contains one of a plurality of different shell materials; and differentiating individual ones of the NWs from one another by selectively removing or not removing shell material within areas to be electrically coupled to individual ones of a plurality of mesowires (MWs). Also disclosed is a nanowire array that contains radially encoded NWs, and a computer program product useful in forming a nanowire array.

Abstract: A method of making nanoparticles includes reacting a first material powder with a second material vapor to form a surface coating on particles of the first material powder, and selectively removing the first material powder to convert the surface coating to third material nanoparticles.

Abstract: A method for processing a surface involves depositing at least one class of enzymes (2) onto the surface (1); introducing at least a reactant (3) into an environment of the surface (1), and causing interaction between the enzymes (2) and the reactant (3), thereby to cause processing of a region of the surface (1), the processed region of the surface (1) being defined with respect to a region thereof that is proximate (4) to where the enzymes (3) have been deposited.

Abstract: An etchant for copper and copper alloys, includes an aqueous solution containing: 14 to 155 g/liter of cupric ion source in terms of a concentration of copper ions; 7 to 180 g/liter of hydrochloric acid; and 0.1 to 50 g/liter of azole, the azole including nitrogen atoms only as heteroatoms residing in a ring. A method for producing a wiring by etching of copper or copper alloys, includes the step of: etching a portion of a copper layer on an electrical insulative member that is not covered with an etching resist using the above-described etchant so as to form the wiring. Thereby, a fine and dense wiring pattern with reduced undercut can be formed.

Abstract: A process for making an electronic device comprising a dielectric substrate laminated with an electrically conductive metal or alloy which comprises applying a non-aqueous etch-resistant ink by ink jet printing to selected areas of the metal or alloy, exposing the etch-resistant ink to actinic radiation and/or particle beam radiation to effect polymerisation, removing exposed metal or alloy by a chemical etching process and then removing the polymerised etch-resistant ink by alkali wherein the etch-resistant ink is substantially solvent free and comprises the components: A) 30 to 90 parts acrylate functional monomers free from acid groups comprising mono or higher functionality wherein 5-95% by weight is one or more mono-functional monomers; B) 1 to 30 parts acrylate functional monomer containing one or more acid groups; C) 0 to 20 parts polymer or prepolymer; D) 0 to 20 parts radical initiator; E) 0 to 5 parts colorant; F) 0 to 5 parts surfactant; and wherein the ink has a viscosity of not greater than 3

Abstract: A method for processing semiconductor wafers is disclosed. A semiconductor wafer is provided to a semiconductor processing stage where a block copolymer surfactant (BCS) is applied to the wafer surface. In one embodiment, the BCS includes a hydrophobic portion and a hydrophilic portion. Alternatively, the BCS may be a silicone-containing BCS. In one embodiment, the BCS is within an aqueous solution where the concentration of the BCS within the aqueous solution is less than one percent by weight. Also disclosed is an aqueous solution including abrasive particles and a BCS having a hydrophobic portion and a hydrophilic portion. The abrasive particles may include silica, alumina, or ceria.

Abstract: A circuitized substrate in which two conductive layers (e.g., electroplated copper foil) are bonded (e.g., laminated) to an interim dielectric layer. Each of the two foil surfaces which physically bond to the dielectric are smooth (e.g., preferably by chemical processing) and include a thin, organic layer thereon, while the outer surfaces of both foils are also smooth (e.g., preferably also using a chemical processing step). One of these resulting conductive layers may function as a ground or voltage plane while the other may function as a signal plane with a plurality of individual signal lines as part thereof. An electrical assembly and an information handling system utilizing such a circuitized substrate are also provided, as is a method of making the substrate.

Abstract: The present invention provides an aqueous composition useful for polishing nonferrous metal interconnects on a semiconductor wafer comprising oxidizer, inhibitor for a nonferrous metal, complexing agent for the nonferrous metal, modified cellulose, 0.01 to 5% by weight copolymer of acrylic acid and methacrylic acid, and balance water, wherein the copolymer of acrylic acid and methacrylic acid has a monomer ratio (acrylic acid/methacrylic acid) in the range of 1:30 to 30:1 and the copolymer has a molecular weight in the range of 1K to 1000K.

Abstract: In one method and embodiment of the present invention, at least one coil layer is formed in a write head, using a two-slurry step of copper damascene chemical mechanical polishing method with a first slurry step removing the undesirable copper that is on top of the tantalum barrier layer and on top of the trenches and a second slurry step removing the remainder of the undesirable copper, the tantalum barrier layer, the silicon dioxide hard mask layer, the hard baked photoresist layer, the magnetic alloy such as NiFe, CoFe, or CoNiFe, and alumina insulating layer for better thin film magnetic head performances.

Abstract: There is provided an etching solution comprised of a cupric chloride solution and a high-concentration triazole type compound added to the cupric chloride solution and capable of forming an etching-inhibiting coating. In a process of forming a circuit pattern by etching with the etching solution, an etching-inhibiting coating is selected formed on parts of a copper foil laid under the edge of an etching resist to effectively inhibit horizontal side-etching of the copper foil from the edge of the etching resist. Also, nonuniform irregularities formed on the side wall of the circuit pattern by the etching improves the adhesion between the circuit pattern and an insulating resin layer covering the circuit pattern.

Abstract: An etchant for patterning composite layer containing copper is provided. The etchant includes peracetic acid being about 5% to 40% by weight and serving as a major component, a peracetic acid stabilizer being about 5% to 15% by weight, an organic acid being about 5% to 10% by weight, an inorganic acid being about 5% to 15% by weight, a salt being about 8% to 15% by weight, which are based on the total weight of the etchant.

Abstract: An etchant for removing an indium oxide layer includes sulfuric acid as a main oxidizer, an auxiliary oxidizer such as H3PO4, HNO3, CH3COOH, HClO4, H2O2, and a Compound A that is obtained by mixing potassium peroxymonosulfate (2KHSO5), potassium bisulfate (KHSO4), and potassium sulfate (K2SO4) together in the ratio of 5:3:2, an etching inhibitor comprising an ammonium-based material, and water. The etchant may remove desired portions of the indium oxide layer without damage to a photoresist pattern or layers underlying the indium oxide layer.

Abstract: A substrate processing enables etching of a barrier metal film at around room temperature without application of a mechanical load and without excessive etching of a necessary portion of copper. The substrate processing flattens a copper film and a barrier metal film, both exposed on a surface of a substrate, by using an etching liquid capable of adjusting the etching rate ratio between the copper film and the barrier metal film.

Abstract: The invention provides chemical-mechanical polishing systems, and methods of polishing a substrate using the polishing systems, comprising (a) an abrasive, (b) a liquid carrier, and (c) a positively charged polyelectrolyte with a molecular weight of about 15,000 or more, wherein the abrasive comprises particles that are electrostatically associated with the positively charged polyelectrolyte.

Abstract: The present invention provides an aqueous composition useful for CMP of a semiconductor wafer containing a metal comprising oxidizer, inhibitor for a nonferrous metal, complexing agent for the nonferrous metal, modified cellulose, 0.001 to 10% by weight copolymer blends of a first copolymer and a second copolymer and balance water.

Abstract: A high-power BGA includes a printed circuit board with a through hole, connection pads formed on the bottom of the printed circuit board, matrix solder balls surrounding the through hole and adjacent to the connection pads, a heat spreader on the top surface of the printed circuit board that includes an insulating layer of a high thermal conductivity, a semiconductor chip mounted within the through hole on the bottom surface of the heat spreader that includes a number of contact pads for bonding with the connection pads using gold wires, and a passive film filling the through hole and around the semiconductor chip. By interposing a ceramic insulating layer between the semiconductor chip and the heat spreader, charge generation between the semiconductor chip and the heat spreader is sharply reduced, and defects such as ESD (electrostatic discharge) is reduced during testing and mounting of the package.

Abstract: An extrusion-free wet cleaning process for post-etch Cu-dual damascene structures is developed. The process includes the following steps: (1). providing a wafer having a silicon substrate and at least one post-etch Cu-dual damascene structure, the post-etch Cu-dual damascene structure having a via structure exposing a portion of a Cu wiring line electrically connected with an N+ diffusion region of the silicon substrate, and a trench structure formed on the via structure; (2). applying a diluted H2O2 solution on the wafer to slightly oxidize the surface of the exposed Cu wiring line; (3). washing away cupric oxide generated in the oxidation step by means of an acidic cupric oxide cleaning solution containing diluted HF, NH4F or NH2OH; and (4). providing means for preventing Cu reduction reactions on the Cu wiring line.

Abstract: A thin and flexible radio frequency (RF) antenna tag or label is disclosed which contains an RF circuit connected to an antenna which is created by demetallizing the area around the antenna pattern on a thin, metallized substrate such as a film or paper web. Antenna(s) may be formed on one or both sides of the substrate and can contain printed, holographic, optical variable device, diffractive, dot matrix, computer-generated holograms or computer-generated optical images. The demetallized RF antenna on the substrate can optionally further be transferred to a second substrate or web by means of a cold foil stamping process. The tag or label is thin and flexible, enabling a wide range of applications including RF tagging of anti-theft devices, product packaging of all types, credit cards, passports, admission tickets, stamps, vehicles, badges, fare cards, roadway tolls, customs and immigration checkpoints identification, and animal identification/tracking devices.

Abstract: The present invention relates to a method of manufacturing a semiconductor device. In the method, an etching-back layer consisting of aluminum or copper is formed on a base substrate and a multilayer wiring board is manufactured on the etching-back layer. After that the etching-back layer is etched to be removed under the condition that the multilayer wiring board and the base substrate are not etched, so that the base substrate is separated from the multilayer wiring board. Accordingly, the base substrate can be reused.

Abstract: The invention is directed to a method and composition for providing chemically-resistant roughened copper surfaces suitable for subsequent multilayer lamination. In one embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, a topography modifier, and a sulfur-containing coating stabilizer. In another embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, and a topography modifier. Then, in a subsequent step, the roughened copper surface is contacted with an acid resistance promoting composition.

Abstract: A lead-containing copper-based alloy is immersed into a weak acidic or neutral etching solution having a buffer effect which is formed by adding an organic acid into a complexing agent having a high ability to form a complexing ion with lead, and lead particles present on the surface of the lead-containing copper-based alloy are then removed. The complexing agent is one of an organic ammonium salt such as ammonium acetate, or ammonium citrate, or may be an organic sodium salt such as sodium acetate, sodium tartrate, and sodium citrate. Preferably, an immersion temperature of the alloy to the etching solution falls within a range of from 10 to 50° C. The etching solution is agitated with oxygen or a gas containing oxygen blown thereinto during the immersion of the alloy into the etching solution. An extremely low voltage of ?0.3 to +0.2 V vs. NHE is applied from outside to the lead-containing copper-based alloy as an anode.

Abstract: The present invention sets forth an improved method of microetching a metal substrate by contacting the substrate with an aqueous composition comprising a sodium persulfate or hydrogen peroxide oxidizing agent, acid, and one or more additives. When the oxidizing agent is sodium persulfate, the one or more additives generally comprise an aliphatic saturated dicarboxylic acid. When the oxidizing agent is hydrogen peroxide, the one or more additives generally comprise a stabilizer and amino tris(methylene phosphonic acid).

Abstract: Copper and copper alloys are etched to provide uniform and smooth surface by employing an aqueous composition that comprises an oxidant, a mixture of at least one weak complexant and at least one strong complexant for the copper or copper alloy, and water and has a pH of about 6 to about 12 so as to form an oxidized etch controlling layer and to uniformly remove the copper or copper alloy; and then removing the oxidized etch controlling layer with a non-oxidizing composition. Copper and copper alloy structure, having smooth upper surfaces are also provided.

Abstract: A method for forming a circuit pattern includes at least a step (a) of subjecting a non-conductor to electroless copper plating to form a copper film and a step (b) of etching the copper film so as to form a circuit pattern. As a catalyst for the electroless copper plating, a silver colloidal solution is used containing as essential components at least the following: (I) silver colloidal particles; (II) one or more of ions of metal having an electric potential which can reduce silver ions to metal silver in the solution and/or ions which result from oxidation of the ion at the time of reduction of the silver ions; and (III) one or more of hydroxycarboxylate, condensed phosphate and/or amine carboxylate ions. The silver colloidal particles (I) are produced by the ion (II) of the metal having an electric potential which can reduce silver ions to metal silver. The circuit pattern may be formed on a printed wiring board.

Abstract: A composition for chemical-mechanical polishing, comprising an aqueous solution and an abrasive that comprises polymer particles, is described. The polymer particles carry an electrical charge, such that nearby particles repel one another. Accordingly, aggregation of polymer particles may be reduced, minimized or eliminated. The composition may additionally comprise an oxidizing agent. A method of using the composition to polish a substrate surface, such as a substrate surface having a metal surface feature or layer, is also described. A substrate so polished may exhibit good surface characteristics, such as a relatively smooth surface or a reduced number of, or a lack of, microscratches on the surface of the substrate.

Abstract: Priorly, semiconductor devices wherein a flexible sheet with a conductive pattern was employed as a supporting substrate, a semiconductor element was mounted thereon, and the ensemble was molded have been developed. In this case, problems occur that a multilayer wiring structure cannot be formed and warping of the insulating resin sheet in the manufacturing process is prominent. In order to solve these problems, a laminated plate 10 in which a thin first conductive film 11 and a thick second conductive film 12 have been laminated via a third conductive film 13 is used.

Abstract: Non-chromate solutions for treating and/or etching metals, particularly, aluminum, aluminum alloys, steel and titanium, and method of applying same wherein the solutions include either a titanate or titanium dioxide as a “drop-in replacement” for a chromium-containing compound in a metal surface etching solution that otherwise would contain chromium.

Abstract: The present invention discloses an etchant for etching at least two different metal layers, the etchant comprising hydrogen peroxide (H2O2) and one of carboxylic acid, carboxylate salt, and acetyl group (CH3CO—).

Abstract: Non-chromate solutions for treating and/or etching metals, particularly, aluminum, aluminum alloys, steel and titanium, and method of applying same wherein the solutions include either a titanate or titanium dioxide as a “drop-in replacement” for a chromium-containing compound in a metal surface etching solution that otherwise would contain chromium.

Abstract: A wafer chuck includes alignment members that allows a semiconductor wafer to be properly aligned on the chuck without using a separate alignment stage. The alignment members may be cams, for example, attached to arms of the wafer chuck. These members may assume an alignment position when a robot arm places the wafer on the chuck. In this position, they guide the wafer into a proper alignment position with respect to the chuck. During rotation at a particular rotational speed, the alignment members move away from the wafer to allow liquid etchant to flow over the entire edge region of the wafer. At still higher rotational speeds, the wafer is clamped into position to prevent it from flying off the chuck. A clamping cam or other device (such as the alignment member itself) may provide the clamping.

Abstract: The present invention provides a chemical metal polishing (CMP) method with improved flexibility and improved processing window, especially as it relates to the chemical aspect of CMP technology. Broadly speaking, the invention has two aspects: according to one aspect, the invention provides a new CMP composition, comprising as an oxidizer, at least one of inorganic halogen derivative and dissolved oxygen while in a second aspect the invention provides an improved method for polishing metals.

Abstract: The invention is directed to a method and composition for providing chemically-resistant roughened copper surfaces suitable for subsequent multilayer lamination. In one embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, a topography modifier, and a sulfur-containing coating stabilizer. In another embodiment, a smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition comprising an oxidizer, a pH adjuster, and a topography modifier. Then, in a subsequent step, the roughened copper surface is contacted with an acid resistance promoting composition.

Abstract: Methods for adhering polyimide dielectric materials to copper-, titanium-, aluminum-, or copper-and-titanium-containing portions of a substrate are described. The methods include the steps of applying adhesion promoter to a clean surface of the substrate, and curing the adhesion promoter. SPIE varnish is applied over the cured adhesion promoter, and is itself cured. A further layer of adhesion promoter is applied over the cured SPIE varnish, and is cured. The polyimide dielectric material is then laminated to the adhesion promoter. Cleaning of the copper-containing substrate portions is performed by etching with etchant including cupric chloride, cleaning of the titanium-containing substrate portions is performed with etchant including HF, and cleaning of copper- and titanium-containing portions is performed by HF etching followed by cupric chloride etching. Aluminum-containing portions of the substrate are not etched.

Abstract: A liquid etchant and a method for roughening a copper surface each capable of providing copper with a roughened surface increased in acid resistance regardless of a chlorine ion in a short period of time, to thereby ensure firm adhesion between a copper conductive pattern and an outer layer material during manufacturing of a printed circuit board, resulting in the manufacturing being highly simplified. The liquid etchant includes a main component containing an oxo acid such as sulfuric acid and a peroxide such as hydrogen peroxide. Also, the liquid etchant includes an auxiliary component containing a tetrazole such as 5-aminotetrazole or the like, or a 1,2,3-azole. The liquid etchant permits a copper surface to be roughened in an acicular manner.