Method and Use for Cleaning a Non-Conductive Surface

Abstract

The present invention is a method for cleaning a non-conductive surface of a non-conductive layer, wherein the non-conductive layer is based on a composite of an organic polymer and a glass filler, includes blind microvias (BMVs) for the fabrication of articles having integrated circuits, the non-conductive surface includes non-conductive walls of the BMVs, the non-conductive layer is bonded to a copper layer, the copper layer forms the bottom of the BMVs, and in the following order: (i) preparing the non-conductive surface of the non-conductive layer; (ii) treating the surface prepared in step (i) using a desmear process including, in this order, the steps of (t1) treating the surface prepared using a swelling agent solution containing water and an organic solvent, (t2) treating the surface using an aqueous etching solution containing an oxidizing agent, and (t3) treating the surface using an aqueous reducing solution containing a reducing agent; (iii) treating the surface treated in step (ii) using an aqueous alkaline cleaning agent solution to remove the glass filler; and (iv) drying the surface treated in step (iii) to obtain a dry surface, preferably a water-free surface, and relates to the use of the method.

Description

Technical Field

[0001] The present invention relates to a novel method for cleaning the non-conductive surface of a non-conductive layer based on a composite of an organic polymer and a glass filler and including blind microvias (BMVs) for the fabrication of articles having integrated circuits, and to its use. In particular, the method is used for removing glass fillers from non-conductive surfaces including the walls of blind microvias and, in particular, for preparing a cleaned surface for subsequent pretreatment and metallization, in the fabrication of articles such as multi-layer assemblies as printed circuit boards, in particular fine-line IC substrate boards where circuit features as blind microvias can be filled with metal. In particular, the method is useful for SAP applications.

Background Art

[0002] Modern electronic device manufacturers are faced with the increasing demand for miniaturization and need to pursue the trend of more densely interconnected multi-layer printed circuit boards. Epoxy-based composites are the insulation materials of choice because of their low cost and well-balanced physico-chemical and mechanical properties. The latest epoxy build-up laminates have an increasing amount of spherical glass filler required to compensate for the CTE mismatch between the epoxy-based resin matrix and the electroplated copper circuits. Furthermore, their small size on the order of microns or less allows for a smoother surface topography compared to glass fiber bundle-reinforced base materials.

[0003] After inserting various recesses, such as traces, blind microvias (BMVs), or through-holes (THs), into a resin-based substrate containing a glass filler by mechanical or laser drilling, a series of different wet chemical processes are applied to the surface of the substrate. Such processes are a wet chemical desmear process that removes residues from the drilling process and a pretreatment process that prepares the surface for subsequent electroless and / or electrolytic metallization. During industrial desmear processing, the adhesion of the exposed glass filler on the surface of the substrate and the recesses weakens, and their anchoring in the surrounding resin matrix is lost or damaged. If these fillers are not removed, the remaining weakly bonded or loose fillers can cause a decrease in the adhesion of the plated copper on the epoxy resin, and moreover, the degradation of the copper-to-copper connection in the blind microvia or through-hole (TH) may occur. This may affect the manufacturing yield and the reliability of the final product.

[0004] Common approaches to overcome glass filler incorporation include the fluoride etching solution described in U.S. Patent Application Publication No. 2012 / 0298409 and ultrasonic treatment described in U.S. Patent Application Publication No. 2007 / 0131243. Neither of these strategies can be easily applied to the vertical mode of the semi-additive process (SAP). Due to the serious health problems of the fluoride etching solution, these become immediately ineligible in most parts of the industry. On the other hand, ultrasonic application in the vertical mode is very difficult to use in a homogeneous manner that gives a sufficient impact on each panel, even if it is a basket application.

[0005] Japanese Patent Application Laid-Open No. 2010-229536 discloses a pretreatment agent for cleaning the surface of a resin substrate containing a silica-based filler, which is intended to remove the filler and glass fibers exposed on the substrate surface after desmear treatment or the like. The pretreatment agent contains an alkali, a non-ionic ether-based surfactant, and an amine-based complexing agent.

[0006] U.S. Patent Application Publication No. 2010 / 056416 discloses a cleaning composition having a limited number of natural raw materials including an anionic surfactant, a hydrophilic synthetic compound selected from C6 alkyl polyglucosides, a nonionic surfactant, and a hydrophobic synthetic compound such as oleic acid or palmitic acid, the composition having a pH of 7 to 13. The cleaning composition can be used for cleaning laundry, soft surfaces, and hard surfaces.

[0007] In particular, in SAP applications that require metallization of the entire surface of a non-conductive substrate to initiate SAP application, reliable cleaning and plating of the substrate cannot be achieved.

[0008] The problems mentioned, of providing good cleaning and plating compositions for continuously new substrate materials and processing chemical techniques, remain a side issue, and the processes for cleaning and plating must be continuously adapted. For example, the desmear process requires increasingly long times and more precautions for new materials compared to subsequent process steps in pretreatment and metallization. In particular, good cross-exchange from one part of the process sequence to another, or from one processing bath to another, has problems in developing the material properties after treatment throughout the metallization process of non-conductive materials, and problems such as long drag-in of different holding times and processing times.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0010] Therefore, the present invention aims to overcome the drawbacks of the prior art and provide improved cleaning means including removing loose glass fillers from the non-conductive surfaces of various composites having organic polymers and glass fillers, where after drilling a recessed structure having low adhesiveness as a blind microvia or through-hole, the glass fillers are exposed on the composite surface.

[0011] Furthermore, it is an object of the present invention to provide means for preparing a cleaned non-conductive surface after drilling a recessed structure as a blind microvia that enables improved peel strength results after metallization.

[0012] Another object of the present invention is to provide means for improved removal of glass fillers that improve the handling and flexibility of different process steps in the use of a new treatment bath composition.

[0013] Another object of the present invention is to improve the adsorption and uniform deposition of an activator as a palladium catalyst on the surface of a substrate, providing a catalyst that enhances the adhesiveness of subsequent copper plating and improves copper adhesion reliability. At the same time, the consumption of the activator should be as low as possible.

[0014] Another object of the present invention is to use means for manufacturing electronic device articles as a multilayer assembly as a fine-line IC substrate, preferably based on SAP application.

Means for Solving the Problems

[0015] These objects are solved using the present invention.

[0016] In one aspect of the present invention, A method for cleaning a non-conductive surface of a non-conductive layer, wherein the non-conductive layer is based on a composite of an organic polymer and a glass filler and includes blind microvias (BMVs) for the fabrication of an article having an integrated circuit, the non-conductive surface includes non-conductive wall surfaces of the BMVs, the non-conductive layer is bonded to a copper layer, the copper layer forms the bottom of the BMVs, in the following order: (i) providing the non-conductive surface of the non-conductive layer; (ii) treating the surface prepared in step (i) using a desmear process that includes, in this order, treating with a swelling agent solution containing water and an organic solvent, treating with an aqueous etching solution containing an oxidizing agent, and treating with an aqueous reducing solution containing a reducing agent to obtain a desmeared surface; (iii) treating the surface treated in step (ii) with an aqueous alkaline cleaning agent solution to remove the glass filler, wherein the aqueous alkaline cleaning agent solution comprises: (a) at least one surfactant selected from the group consisting of saturated branched or unbranched C5-C12 carboxylic acids, or salts thereof, wherein the concentration of (a) one surfactant is 0.9-1.7 g / L; (b) at least one surfactant selected from the group consisting of saturated branched or unbranched C5-C12 alkyls having a negatively charged group selected from sulfates, sulfites, sulfonates, phosphates, phosphites and carbonates, and saturated C3-C8 alkylaminocarboxylates; (c) at least one compound having at least one hydroxyl group and at least one C-O-C group selected from the group consisting of alkoxylated C5-C12 alkanols and glycoside C5-C12 alkanols; and (d) a step comprising an alkali metal hydroxide having a concentration of 65-200 g / L; (iv) drying the surface treated in step (iii) to obtain a dry surface, preferably a water-free surface A method is provided that includes the above steps.

[0017] In another aspect of the present invention, there is provided the use of the above method for SAP (Semi-Additive Process) application in the fabrication of an article having an integrated circuit with line / space dimensions from 25 / 25 μm to 8 / 8 μm or less.

[0018] Further aspects of the present invention will be apparent to those skilled in the art from the dependent claims or the following description.

[0019] The features will become apparent to those skilled in the art by describing exemplary embodiments in detail with reference to the following accompanying drawings.

Brief Description of the Drawings

[0020]

Figure 1

Modes for Carrying Out the Invention

[0021] Here, reference is made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The effects and features of the exemplary embodiments, as well as the implementation methods thereof, will be described with reference to the accompanying drawings. In the drawings, like reference numerals denote like or similar elements, and duplicate descriptions are omitted. As used herein, the term "and / or" includes any combination of one or more of the associated listed items. Further, the use of "may be" when describing embodiments of the present invention refers to "one or more embodiments of the present invention".

[0022] In the following description of embodiments of the present invention, unless otherwise clearly indicated from the context, singular terms may include the plural. For example, when "filler" or "blind microvia" is used below, "a plurality of fillers" or "a plurality of blind microvias" are included.

[0023] In the following description, the terms "substrate" or "non-conductive surface of the substrate" are also used to simplify the reading. In this context, the substrate consists of a non-conductive layer bonded to a copper layer, and the substrate has a non-conductive surface of the non-conductive layer to be treated according to the present invention, as well as a copper surface of the copper layer that also constructs the bottom of the blind microvias drilled into the non-conductive layer.

[0024] An aqueous solution in the context of the present invention is a solution containing more than 50% by mass of water.

[0025] In the context of the present invention, an oxidizing agent is suitable for oxidizing a compound or material, particularly the non-conductive surface of the non-conductive layer where the oxidizing agent is reduced. In other words, an oxidizing agent is a substance that acquires or "receives" / "takes" electrons from a reducing agent, such as a non-conductive surface, or more precisely, the material of said surface, in a redox chemical reaction.

[0026] In the context of the present invention, a reducing agent is suitable for reducing a compound, particularly a compound on the oxidized non-conductive surface of the non-conductive layer where the reducing agent is oxidized. In other words, a reducing agent is a substance in a redox chemical reaction that imparts electrons to a compound to be reduced from the reducing agent, such as a compound on the non-conductive surface.

[0027] The present invention is particularly suitable for use with a desmear treatment combined with a glass filler removal treatment, preferably before a pretreatment including palladium activation before treatment of the non-conductive surface according to the present invention, where the composite contains a glass filler as a spherical glass filler that is part of, for example, an SAP-based material. Using the present invention, it is possible to remove the glass filler exposed from the surface including the walls of the BMV and also the through-hole (TH) where the bond has become loose or less during the drilling and desmear processes, and to provide a treated surface such that the adhesion of the subsequent deposited metal layer is improved. The present invention provides a cleaned surface of the non-conductive layer including the non-conductive walls of the BMV and also the TH for a subsequent electroless metallization process and / or an electrolytic metallization process starting from the pretreatment of the dry surface.

[0028] In one embodiment, when the non-conductive surface also includes the wall surface of the TH, a through-hole passes from the surface of the non-conductive surface to the surface of the copper layer to construct the TH.

[0029] The present invention particularly enables the separation of a cleaning process including a desmear process within a completed metallization process, which is typically performed in close succession in all single process steps in the wet series, from a pretreatment process. This provides greater flexibility between these two important processes in terms of the longer required time for the desmear process and / or in terms of alternative bath compositions used for pretreatment.

[0030] The present invention brings about a higher yield and good reliability of a multi-layer assembly fabricated as a printed circuit board, and the adhesion of industrially important IC substrates and printed circuit board substrates showed significantly high peel strength values after treatment using the new process.

[0031] The present invention particularly enables the fabrication of electronic device articles having integrated circuits, such as IC substrate articles having line / space dimensions (L / S) from 25 / 25 μm to 8 / 8 μm, preferably from 15 / 15 μm to 8 / 8 μm, or more preferably less than 8 / 8 μm. At the same time, the process provides excellent coating performance.

[0032] The present invention uses components that are less harmful than those used in the prior art. Further, the present invention enables the fabrication of electronic device articles under milder conditions in terms of working temperature and working time. This results in a significant reduction in energy consumption and improves throughput. The low-temperature scheme also reduces equipment costs and maintenance costs.

[0033] One of the most desirable benefits of cleaning a non-conductive surface from loose glass fillers is the increased adhesion of copper plated onto the cleaned surface. The obvious reason to expect this increased adhesion is to assume an insufficient bond of the "loose" glass filler to the substrate. This must be the case of a filler that is less than half embedded in the surrounding epoxy resin after desmear, or of some re-adsorbed filler. Copper is then plated around this filler, and when the peeling force acts, they are easily lifted from the substrate. Surprisingly, the drying process further improves the adhesion of the subsequent deposited metal layer and also results in an improved distribution of the activator while reducing the amount of activator density. The above-mentioned effects especially help to save funds and resources.

[0034] The present invention can be used in a wide variety of substrates from different suppliers where the non-conductive layer is based on a composite of an organic polymer and a glass filler, and the copper layer is bonded to the non-conductive layer, for example, by a laminate that constructs the substrate to be processed.

[0035] The composite is based on a mixture of glass fillers and / or silica fillers with an organic polymer as a resin and / or plastic and their blends. The resins and plastics include dielectric materials commonly used in the electronics industry that are to be metallized. The resins and plastics are preferably selected from epoxy, epoxy resins, isocyanate resins, bismaleimide triazine resins and phenylene resins; polyesters such as polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene, acrylonitrile-butadiene-styrene (ABS) copolymer, polyamide (PA), polycarbonate (PC) and mixtures and blends of the foregoing.

[0036] The organic polymer preferably includes a polyimide resin or an epoxy resin. The polyimide resin can be modified by the addition of polysiloxane, polycarbonate, polyester, etc. The epoxy resin may be a glass-filled epoxy board material including a combination of an epoxy resin and a glass filler, or may be modified to have low thermal expansion and a high glass transition temperature, which constitutes a glass-filled epoxy board material with a high glass transition temperature.

[0037] Suitable glass fillers are preferably selected from borosilicate glass, quartz glass, silica glass, and fluorinated glass. The sizes of various fillers have a diameter in the range of 0.01 μm to 5 μm, preferably with an average diameter of 0.5 μm.

[0038] Preferably, the composite of the non-conductive layer is an integrated film, for example, an epoxy-based material. The detailed name is indicated if necessary. The size of the embedded glass filler has an average diameter of 0.5 μm and a maximum of 5.0 μm.

[0039] The substrate according to the present invention may include a core layer. In this case, the copper layer bonded to the non-conductive layer is further bonded to the core layer. This core layer makes it easier to handle the more flexible substrate and avoids unwanted twisting of the substrate.

[0040] In a further embodiment, two substrates can be bonded to the core layer. In this case, the copper layer of each substrate is bonded to the core layer, but the non-conductive layer is the outer layer. This enables the non-conductive layers of two substrates including one core layer to be processed from both sides of the core layer to construct a multilayer assembly.

[0041] The foregoing core layer can be selected from the group consisting of a printed circuit board substrate, a circuit carrier substrate, an interconnect device substrate, and a precursor for any of the foregoing. Such substrates and precursors include, inter alia, flame retardant NEMA grade materials such as FR-1, FR-2, FR-3, FR-4, FR-5 (FR-1, FR-2, FR-3, FR-4, and FR-5 are, for example, PCB dielectric materials having good electrical specifications known to those skilled in the art, manufactured from paper and phenol-formaldehyde resin (FR-1), woven / non-woven glass fiber cloth impregnated with epoxy resin (FR-4), or glass fiber fabric reinforced with a high-temperature epoxy resin binder (FR-5)), copper-clad materials, SAP materials, IC substrates, and laminates thereof. Preferably, the core layer is an FR4 material, an SAP material, or an IC substrate.

[0042] The desmear process of step (ii) is preferably carried out as a rinsing process before step (iii) without any further wet chemical processes.

[0043] The desmear process includes sub-steps (t1), (t2), and (t3), (t1) includes treating the non-conductive surface of the non-conductive layer to obtain a swollen surface using a swelling agent solution containing water and an organic solvent on the non-conductive surface of the non-conductive layer, (t2) includes treating the swollen surface to obtain an etched surface using an aqueous etching solution containing an oxidizing agent, (t3) includes treating the etched surface to obtain a desmeared surface using an aqueous reducing solution containing a reducing agent.

[0044] By applying the corresponding sub-steps (t1), (t2), and (t3), a particularly effective desmear process can be ensured in which the major part of the residue (so-called smear) resulting from the drilling process is removed.

[0045] The swelling agent solution penetrates into the non-conductive surface of the non-conductive layer that results in a swollen surface, and the binding strength of the particles (weakly) bonded as a glass filler or the drilling residues in the said surface becomes even weaker. Preferably, the organic solvent of the swelling agent solution is selected as glycol ether and / or lactam, and penetrates into the exposed resin surfaces of the through holes and BMV. Most preferably, the solution is selected as the commercially available Securiganth MV Sweller (swelling agent).

[0046] Preferably, the organic solvent is applied to the water-containing swelling agent solution at a concentration of 300 ml / L to 650 ml / L, preferably 350 ml / L to 550 ml / L, more preferably 450 ml / L to 550 ml / L, based on the total volume of the swelling agent solution.

[0047] Preferably, the swelling agent solution has a pH of 9.5 to 12, preferably 10.5 to 11.5.

[0048] Preferably, (t1) is carried out at a temperature of 55 °C to 90 °C, preferably 70 °C to 85 °C, for a duration of 2 minutes to 10 minutes, preferably 4 to 5 minutes.

[0049] (t2)'s aqueous etching solution may contain an oxidizing agent, more preferably hydrogen peroxide and sulfuric acid. Preferably, the aqueous etching solution is selected as an alkaline aqueous etching solution, more preferably a potassium hydroxide solution or a sodium hydroxide solution, and contains an oxidizing agent, more preferably potassium permanganate. Most preferably, the etching agent is selected as the commercially available Securiganth P500 or Securiganth MV P-Etch.

[0050] Preferably, the treatment using the aqueous etching solution preferably containing permanganate is applied at a concentration of 50 g / L to 70 g / L, preferably 55 g / L to 65 g / L, based on the total volume of the aqueous etching solution.

[0051] Preferably, (t2) is carried out at a temperature of 70 °C to 90 °C for a duration of 5 minutes to 25 minutes, preferably 8 minutes to 15 minutes.

[0052] The aqueous reducing solution (t3) contains a reducing agent such as hydroxylammonium sulfate or hydrogen peroxide, and preferably an acid, most preferably sulfuric acid or hydrochloric acid, and the reducing agent can reduce metal residues from the previous step. Optionally, the aqueous reducing solution (t3) can use a conditioner compound to obtain an aqueous reducing conditioner solution. The aqueous reducing conditioner solution preferably contains an acid such as sulfuric acid or hydrochloric acid, for example, a reagent capable of reducing manganese dioxide on the surface of a non-conductive surface after applying the aqueous etching solution of (t2), such as hydroxylammonium sulfate or hydrogen peroxide, and a polymer containing a quaternized nitrogen atom. For example, Securiganth® MV Reduction Solution (reduction solution) or Securiganth® MV Reduction Conditioner (reduction conditioner) available from Atotech Deutschland GmbH can be used.

[0053] Preferably, (t3) is carried out at a temperature of 40 °C to 55 °C for a duration of 3 minutes to 7 minutes.

[0054] Step (iii) of treating the surface treated in step (ii) with an aqueous alkaline cleaning agent solution:

[0055] By applying step (iii) after the Desmia process, the remaining part of the residue from the drilling process is removed, but more importantly here, the loose glass filler is sufficiently removed.

[0056] The concentration of at least one surfactant (a) in the aqueous alkaline cleaning agent solution is used at 0.9 - 1.7 g / L, preferably 1.0 - 1.5 g / L, more preferably 1.2 - 1.4 g / L. In the case of two or more surfactants in the solution, the total concentration is 0.9 - 1.7 g / L, preferably 1.0 - 1.5 g / L, more preferably 1.2 - 1.4 g / L. It is understood that the surfactant can be added as an acid or a salt.

[0057] The concentration of at least one surfactant (b) in the aqueous alkaline cleaning agent solution is preferably used at 0.5 - 10 g / L, more preferably 1.5 - 9 g / L, most preferably 2 - 8 g / L. Other preferred concentration ranges are 0.5 - 1.2 g / L, preferably 0.7 - 1.1 mg / L, more preferably 0.75 - 1.0 g / L. In the case of two or more surfactants in the solution, the total concentration is also 0.5 - 10 g / L. In a preferred embodiment, the concentration range of at least one surfactant (b) selected from the group consisting of saturated branched or unbranched C5 - C12 alkyls having a negatively charged group selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate is 0.5 - 1.2 g / L, preferably 0.7 - 1.1 mg / L, more preferably 0.75 - 1.0 g / L. In another preferred embodiment, the concentration range of at least one surfactant (b) selected from the group consisting of saturated C3 - C8 alkylaminocarboxylic acids is 0.5 - 10 g / L, preferably 1.5 - 9 g / L, more preferably 2 - 8 g / L.

[0058] The concentration of at least one compound (c) having at least one hydroxyl group and at least one C - O - C group in the aqueous alkaline cleaning agent solution is preferably used at 0.7 - 1.3 g / L, more preferably 0.8 - 1.2 g / L, most preferably 0.9 - 1.1 g / L. In the case of two or more alkanols in the solution, the total concentration is also 0.7 - 1.3 g / L, preferably 0.8 - 1.2 g / L, more preferably 0.9 - 1.1 g / L.

[0059] (d) By concentrating the alkali metal hydroxide, a strongly alkaline pH value is brought about, having a pH value computationally higher than 14. The concentration of (d) alkali metal hydroxide in the aqueous alkaline cleaning agent solution is used at 65 - 200 g / L, preferably 70 - 100 g / L, more preferably 75 - 90 g / L.

[0060] Throughout this specification and the entire scope of the claims, it should be noted that the numerical limits of the disclosed ranges and ratios may be combined and are considered to include all intermediate values. Further, all numerical values are considered to be preceded by the modifier "about" whether or not this term is specifically stated.

[0061] At least one surfactant is selected from the group consisting of saturated branched or unbranched C5 - C12 carboxylic acids or their salts, preferably saturated branched C6 - C10 carboxylic acids or salts, preferably hexanoic acid, octanoic acid and decanoic acid or their salts, most preferably hexanoic acid and octanoic acid or their salts. Surfactants selected from the group consisting of saturated unbranched C6 - C10 carboxylic acids or salts, more preferably saturated unbranched C6 - C8 carboxylic acids or salts, are preferably unsubstituted hexanoic acid and octanoic acid.

[0062] At least one surfactant selected from the group consisting of saturated branched or unbranched C5 - C12 alkyls having a negatively charged group selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate is preferably one having a negatively charged group of sulfate, phosphate and carbonate, more preferably a saturated branched or unbranched C5 - C8 alkyl having a negatively charged group of sulfate, for example, selected from the group consisting of n - pentyl, isopentyl, n - hexyl, 2 - ethylhexyl, n - heptyl or n - octyl, and the surfactant is most preferably sodium 2 - ethylhexyl sulfate or sodium isoheptyl sulfate.

[0063] The positive counterion of a saturated branched or unbranched C5 - C12 alkyl having a negatively charged group is preferably sodium or potassium, more preferably sodium.

[0064] Saturated C3 - C8 alkylaminocarboxylates are preferably of formula (III) or (IV)

[0065]

Chemical formula

[0066] [wherein, R is a branched or unbranched C4 - C8 alkyl, such as n - pentyl, isopentyl, n - hexyl, 2 - ethylhexyl, n - heptyl, n - octyl] or

[0067]

Chemical formula

[0068] [wherein, k is an integer from 3 to 8, preferably from 4 to 6, and most preferably 6] and is a compound of.

[0069] It is understood that the surfactant is preferably added as a salt. The positive counterion of saturated C3 - C8 alkylaminocarboxylate is preferably sodium or potassium, more preferably sodium.

[0070] At least one compound (c) is selected from the group consisting of alkoxylated C5 - C12 alkanols and glycoside C5 - C12 alkanols.

[0071] The alkoxylated C5 - C12 alkanol of compound (c) is preferably of formula (I)

[0072]

Chemical formula

[0073] [In the formula, p is an integer from 1 to 2, o is an integer from 4 to 10, m is an integer from 4 to 9, more preferably, p is 1, o is from 5 to 7, and m is from 5 to 7] is a compound. Most preferably, the alkoxylated C5-C12 alkanol is ethoxylated hexanol or ethoxylated octanol where o is 6.

[0074] The average MW (molecular weight) of the compound of formula (I) is from 200 to 15000 g / mol, preferably from 400 to 1000 g / mol, and most preferably from 300 to 600 g / mol.

[0075] The glycoside C5-C12 alkanol of compound (c) is preferably of formula (II)

[0076] [Chemical formula]

[0077] [In the formula, n is an integer from 1 to 5, m is an integer from 4 to 9, preferably from 5 to 7] is a compound. Preferably, the compound is an alkyl polyglucoside (APG) provided by CAS 54549-24-5.

[0078] Preferably, the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, more preferably sodium hydroxide.

[0079] In a preferred embodiment, the aqueous alkaline cleaning agent solution of the present invention comprises: (a) at least one surfactant selected from the group consisting of hexanoic acid and octanoic acid or their salts; (b) at least one surfactant selected from the group consisting of sodium 2-ethylhexyl sulfate (sodium ethosulfate), sodium isoheptyl sulfate, and alkylaminocarboxylates according to formula (III) [wherein R is 2-ethylhexyl or n-octyl] and formula (IV) [wherein k is 4 to 6]; (c) at least one compound selected from the group consisting of alkoxylated C5-C12 alkanols which are compounds of formula (I) [wherein the compound is ethoxylated hexanol, ethoxylated octanol or ethoxylated decanol and wherein o is 6], and glycoside C5-C12 alkanols which are compounds of formula (II) [wherein n is an integer from 1 to 5 and m is an integer from 5 to 7]; and (d) sodium hydroxide. In a more preferred embodiment, the aqueous alkaline cleaning agent solution of the present invention further comprises (e) at least one water-soluble alkanolamine.

[0080] In a more preferred embodiment, the aqueous alkaline cleaning agent solution of the present invention comprises a combination of (b) sodium ethosulfate and (c) ethoxylated hexan-1-ol; (b) 1-amino-hexyl carboxylate and (c) ethoxylated decan-1-ol; or (b) APG and (c) 2-ethylhexyliminodipropionate. Preferably, these combinations are used together with (a) hexanoic acid and (d) sodium hydroxide. In an even more preferred embodiment, the aforementioned combinations are used together with monoethanolamine. Most preferably, the aqueous alkaline cleaning agent solution of the present invention consists of the aforementioned combinations.

[0081] Preferably, the aqueous alkaline cleaning agent solution additionally contains at least one water-soluble alkanolamine selected from the group consisting of (e) monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA), preferably 2-aminoethanol. By using the water-soluble alkanolamine, clouding of the solution can be avoided. In our own experiments, it was possible to show that cloudy solutions lead to undesirable plating results.

[0082] The concentration of at least one water-soluble alkanolamine is 6.5 to 9.0 g / L, preferably 7.5 to 8.5 g / L, more preferably 7.8 to 8.2 g / L.

[0083] The method can be used in vertical and horizontal plating equipment. Preferably, the method is used in vertical plating equipment, and the substrate is transported by a transport device and processed through the processing modules of the plating equipment.

[0084] The method of the present invention is preferably used when the treatment is carried out at 55 to 65 °C for 3 to 7 minutes. The low temperature reduces the energy consumption and also reduces the equipment cost for using a higher temperature. Moreover, evaporation of low-boiling components can be prevented, and strong suction can be avoided.

[0085] In a preferred embodiment of the method of the present invention, step (iv) is carried out at a temperature of 80 °C to 100 °C for 5 to 20 minutes, preferably at a temperature of 85 °C to 95 °C for 10 to 15 minutes, to obtain a dry surface. The drying step can be carried out, for example, by infrared heating, conventional heating, hot air spraying, or a combination thereof.

[0086] To avoid unwanted chemical or physical reactions and consequently achieve the best results for subsequent processing steps, it is important that the surface is dry and preferably free of water. The drying step surprisingly allows for delaying subsequent processing steps without damaging, deteriorating, or breaking the non-conductive surface during standby, or stopping the entire process for a certain period of time before starting from a subsequent process step. This is particularly useful when the desmear process is to be carried out separately (locally and / or in a timely manner) due to various requirements for chemical phenomena and / or required process times. The separation can be carried out in various processing modules, one for cleaning and one for pretreatment.

[0087] In one embodiment, the method of the invention further includes an additional step (vi) of treating the surface of step (iv) with an aqueous alkaline cleaning agent solution containing ethanolamine after step (iv). This step can be carried out within a cleaning module, an independent module, or a pretreatment module corresponding to the next process step. If step (vi) is carried out within a cleaning module or an independent module, it can be omitted within (ix) below from the pretreatment step (v).

[0088] Thus, the method of the invention can be used as a first part of the metallization process of a non-conductive surface including cleaning, pretreatment, and metallization. The method of the invention is preferably used as a fine-line IC substrate article, for example, before activating the non-conductive surface by using a palladium activator solution for subsequent metallization, for fabricating an article having an integrated circuit, such as a multilayer assembly.

[0089] Thus, the method may further include, as a non-limiting example, a step for pretreating the surface after step (iv), preferably for preparing the surface for subsequent electroless and / or electrolytic metallization, further steps: - An optional step (v) of treating the surface of step (iv) with an aqueous alkaline cleaning agent solution containing ethanolamine; Step (vi) of treating the surface of step (v) using an aqueous etching cleaning agent solution containing persulfate; Step (vii) of treating the surface of step (vi) using a preliminary immersion solution; Step (viii) of treating the surface of step (vii) using an activator solution preferably containing noble metal ions, metal colloids or carbon-containing compounds; and - When the activator solution contains noble metal ions, step (ix) of treating the surface of step (vii) using a reducing agent solution are included in this order.

[0090] Step (v) can be omitted if it has already been performed previously.

[0091] In another embodiment of the present invention, step (v) is optional. In a preferred embodiment, step (v) is further performed to improve subsequent metallization results.

[0092] Step (v) is preferably carried out at 50-70°C for 3-7 minutes. In a preferred embodiment, the cleaning agent contains 10-20 g / L of sodium hydroxide and 10-16 g / L of ethanolamine (MEA).

[0093] Step (vi) is preferably carried out at 25-40°C for 1-2 minutes. In a preferred embodiment, the cleaning agent contains 100-150 g / L of sodium persulfate and 30-45 g / L of sulfuric acid.

[0094] Optional step (vii) of treating the surface of step (vi) using a preliminary immersion solution. The preliminary immersion solution is preferably an aqueous solution containing sulfuric acid and / or sodium bisulfate and a pH regulator as a non-ionic surfactant. The non-ionic surfactant is preferably a polyethylene glycol (PEG) compound, more preferably PEG 1500MW or PEG 10,000MW.

[0095] The preliminary immersion solution is preferably an acidic aqueous preliminary immersion solution. The preferred pH is 2-4.

[0096] Step (viii), treating the surface of step (vii) with an activator solution preferably containing a noble metal ion, metal colloid or carbon-containing compound. The activator solution is preferably an aqueous solution containing a noble metal ion or metal colloid. The activator solution is applied onto the surface of the non-conductive layer, preferably treating the surface with an aqueous palladium activator solution, and a palladium ion layer is deposited onto the surface of the non-conductive layer in step (viii). Other useful activator solutions known in the art may include carbon, conductive polymers, or metal colloids containing, for example, copper or palladium tin for subsequent electroless direct metallization.

[0097] The palladium activator solution contains at least one palladium ion source. Additionally, the solution may include a ruthenium ion source, rhodium ion source, palladium ion source, osmium ion source, iridium ion source, platinum ion source, copper ion source, silver ion source, nickel ion source, cobalt ion source, gold ion source, and other metal ion sources as mixtures thereof. The palladium ions and the additional metal ions are adsorbed onto the surface of the substrate.

[0098] Step (ix), a step of treating the substrate of step (viii) when the palladium activator solution is used together with a palladium reducing solution, in which the deposited palladium ion layer in step (viii) is converted into a metallic palladium layer.

[0099] The treatment of the substrate surface containing at least palladium ions is carried out using a palladium reducing solution containing at least one reducing agent suitable for reducing the metal ions (at least palladium ions) adsorbed onto the surface of the substrate, selected from the group consisting of boron-based reducing agents, hypophosphite ion sources, hydrazine and hydrazine derivatives, ascorbic acid, isoascorbic acid, formaldehyde sources, glyoxylic acid, glyoxylic acid sources, glycolic acid, formic acid, sugars, and salts of the aforementioned acids.

[0100] The inventive method further comprises step (x) for electroless metallization of the surface and / or step (xi) for electrolytic metallization after step (viii) or (ix) in order to obtain a metallized surface, preferably a copper surface. Step (x) is preferably carried out using an electroless copper plating bath in order to obtain a copper layer on top of the layer of step (ix).

[0101] Generally, an electroless plating bath contains a solvent, typically water, and at least one metal ion source to be deposited. Further optional components are complexing agents (or chelating agents) for said metal ions (such as those described hereinafter), reducing agents for said metal ions, stabilizers, co-solvents, wetting agents, and functional additives such as brighteners, accelerators, inhibitors, anti-discoloration agents, etc. Such baths and components are known in the art. The electroless copper plating bath may further contain a nickel ion source, a cobalt ion source, and mixtures thereof.

[0102] In order to obtain a copper layer or a nickel layer on the surface during filling the BMV with copper or nickel, (when a layer of carbon or a conductive polymer is deposited on the surface of step ((vi) or (vii))), electrolytic copper or nickel plating baths are used and electrolytic metallization of the surface in step (xi) is carried out after step (viii). The copper or nickel layer may be a copper alloy or a nickel alloy containing alloying metals such as tungsten, silver, etc.

[0103] Additional steps can be carried out between the above steps, such as rinsing steps using, if necessary, for example DI water, or acidic or alkaline aqueous solutions; etching cleaner steps; pre-dipping steps; and / or drying steps.

[0104] Except for the solution of the present invention in the above process, the bath compositions and the solutions themselves used are well known in the art. Suitable solutions for the Desmear process, palladium activator solutions, palladium reduction solutions, electroless and electrolytic copper solutions are known and can be purchased, for example, from Atotech Deutschland GmbH as Securiganth® MV Cleaner PF, Neoganth® MV Etch Cleaner, Neoganth® MV Activator, Neoganth® MV Reducer, Printoganth® MV and Cupracid® AC.

[0105] In a preferred embodiment of the present invention, the electrolytic plating bath in step (xi) is an electrolytic copper plating bath for obtaining a copper layer. The substrate obtained as a result of step (xi) can be used to construct a multilayer assembly by using the following steps of SAP application.

[0106] In one embodiment, the copper layer in step (xi) can be structured by known process steps including photoresist coating, structuring, patterning, photoresist stripping and final etching to the non-conductive layer surface in order to obtain a conductive structure on the non-conductive layer.

[0107] Here, the present invention is illustrated by reference to the following figures and non-limiting examples.

Examples

[0108] The relative ratios of the compounds used in the present invention within the examples were found to be useful and preferred, but are not considered to be limited thereto. All components of the test solutions were diluted in DI (DI - deionized water).

[0109] Three sets of test examples - Samples 1, 2, 3, 4, 5, 6, 9, 10 (Examples of the invention - Samples 5 and 6, and Comparative examples - Samples 1, 2, 3, 4, 9 and 10) were prepared.

[0110] All test specimens (samples) were processed according to the desmear process (t1 - t3), and (t3) was carried out according to the following scheme using a conditioner for (samples 1, 3, 5, and 9) and without a conditioner for (samples 2, 4, 6, and 10):

[0111]

Table 1

[0112] Examples of the invention (Example 1 of the invention (samples 5 and 6)) were treated with an aqueous alkaline cleaning agent solution having a solution temperature of 60 °C and a residence time of 5 minutes (step (iii)) and dried at 90 °C for 15 minutes according to step (iv).

[0113] Comparative examples (samples 1 and 2) were treated without step (iii), but were dried at 90 °C for 15 minutes according to step (iv).

[0114] Comparative examples (samples 9 and 10) included step (iii) but were treated without drying by step (iv).

[0115] Comparative examples (samples 3 and 4) were treated using step (iii), but were dried at 90 °C for 15 minutes before step (iii).

[0116] Example 1 of the invention (samples 5, 6) using the aqueous alkaline cleaning agent solution of step (iii) Concentration of the solution: Hexanoic acid 1.4 g / L Sodium ethyl sulfate 0.8 g / L Ethoxylated hexan - 1 - ol (Cas 31726 - 34 - 8) 1.1 g / L Sodium hydroxide (NaOH) 84 g / L MEA - Monoethanolamine (>98%) 6.5 g / L

[0117] 1. Visual inspection with the naked eye To evaluate the glass filler removal performance, a set of test examples was used to take SEM photographs. This is shown in Figure 1. (SEM image, magnification = 5000 times, showing the non-conductive surface of the non-conductive layer) (Samples 1, 2, 3, 4, 5, 6, 9, 10).

[0118] The cleaning results of Samples 1 and 2 are very insufficient, and it can be seen that many glass fillers remain on the surface. Samples 3 to 9 all used Step (iii), thus showing that relatively good cleaning results in contrast to Samples 1 and 2 are produced. However, the best cleaning results were achieved for Samples 5 and 6, with somewhat more glass fillers removed compared directly to Samples 3, 4, 9, and 10.

[0119] 2. Results of plating Two sets of test examples were used to further process Samples 1, 2, 3, 4, 5, 6, 9, 10 according to the following scheme by Steps (v)-(x):

[0120] [Table 2]

[0121] After Step (ix), one set of test example Samples 1, 2, 3, 4, 5, 6, 9, 10 was used to determine the palladium loading level on the surface of [μg / dm 2 palladium. The results can be seen in Table 1.

[0122] After Step (x), one set of test example Samples 1, 2, 3, 4, 5, 6, 9, 10 was used to determine the palladium loading level on the surface of [μg / dm 2 palladium. The results can be seen in Table 1.

[0123] [Table 3]

[0124] In Table 1, it can be seen that for Samples 5 and 6, the highest peel strength results could be achieved. Interestingly, although the palladium loading level on the surface was at the lowest value, these results could be achieved. This saved palladium consumption, and on the other hand, the reliability could be improved with better peel strength.

Claims

Claim 1 A method for cleaning a non-conductive surface of a non-conductive layer, wherein the non-conductive layer comprises a composite of an organic polymer and a glass filler, and comprises blind microvias (BMVs) for the fabrication of articles having integrated circuits, the non-conductive surface comprising non-conductive wall surfaces of the BMVs, the non-conductive layer being bonded to a copper layer, the copper layer forming the bottom of the BMVs, in the following order: (i) providing the non-conductive surface of the non-conductive layer; and (ii) treating the surface prepared using a desmear process comprising, in this order, the steps of (t1) treating with a swelling agent solution comprising water and an organic solvent, (t2) treating with an aqueous etching solution comprising an oxidizing agent, and (t3) treating with an aqueous reducing solution comprising a reducing agent; (iii) treating the surface treated in step (ii) with an aqueous alkaline cleaning agent solution to remove the glass filler, the aqueous alkaline cleaning agent solution comprising: (a) at least one surfactant selected from the group consisting of saturated branched or unbranched C5-C12 carboxylic acids, or salts thereof, wherein the concentration of (a) one surfactant is 0.9-1.7 g / L; (b) at least one surfactant selected from the group consisting of saturated branched or unbranched C5-C12 alkyls having a negatively charged group selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate, and saturated C3-C8 alkylaminocarboxylates; (c) at least one compound having at least one hydroxyl group and at least one C-O-C group, selected from the group consisting of alkoxylated C5-C12 alkanols and glycoside C5-C12 alkanols; and (d) an alkali metal hydroxide having a concentration of 65-200 g / L; and (iv) drying the surface treated in step (iii) to obtain a dry surface, preferably a water-free surface. A method comprising the above steps. Claim 2 The method according to claim 1, wherein the treatment in step (iii) is carried out at 55-65 °C for 3-7 minutes. Claim 3 The method according to claim 1 or 2, wherein step (iv) is carried out at a temperature of 80 °C to 100 °C for 5-20 minutes. Claim 4 After step (iv), for preparing the surface for subsequent electroless and / or electrolytic metallization, The method according to any one of claims 1 to 3, further comprising an additional step (v) of treating the surface of step (iv) with an aqueous alkaline cleaning agent solution containing ethanolamine.

5. The method further comprising a step for pretreating the surface after step (iv) to prepare the surface for subsequent electroless and / or electrolytic metallization, the further step: - An optional step (v) of treating the surface of step (iv) with an aqueous alkaline cleaning agent solution containing ethanolamine; - A step (vi) of treating the surface of step (v) with an aqueous etching cleaning agent solution containing persulfate; - An optional step (vii) of treating the surface of step (vi) with a preliminary immersion solution; - A step (viii) of treating the surface of step (vii) with an activator solution preferably containing noble metal ions, metal colloids or carbon-containing compounds; and - When the activator solution contains noble metal ions, a step (ix) of treating the surface of step (vii) with a reducing agent solution is included in this order, the method according to any one of claims 1 to 3.

6. The method according to claim 5, further comprising a step (x) for electroless metallization of the surface and / or a step (xi) for electrolytic metallization of the surface after step (viii) or (ix) to obtain a metallized surface, preferably a copper surface.

7. The method according to any one of claims 1 to 6, wherein the non-conductive layer bonded to the copper layer constructs a substrate having the non-conductive surface of the non-conductive layer and the copper surface of the copper layer.

8. The method according to any one of claims 1 to 7, wherein the copper layer bonded to the non-conductive layer is further bonded to a core layer, and preferably, the core layer is FR-1, FR-2, FR-3, FR-4, FR-5, copper-clad material, SAP material or IC substrate, and laminates thereof.

9. The method according to any one of claims 1 to 8, wherein the concentration of the (b) at least one surfactant is used at 0.5 to 10 g / L, and / or the concentration of the (c) at least one compound is used at 0.6 to 1.3 g / L, preferably 0.65 to 1.2 g / L, more preferably 0.7 to 1.1 g / L.

10. The method according to any one of claims 1 to 9, wherein (a) at least one surfactant is selected from the group consisting of saturated branched C6-C10 carboxylic acids or salts, preferably unsubstituted hexanoic acid, octanoic acid, and decanoic acid.

11. The method according to any one of claims 1 to 10, wherein (b) at least one surfactant is selected from the group consisting of saturated branched or unbranched C5-C8 alkyls having negatively charged groups of sulfate, phosphate, and carbonate, and saturated C5-C8 alkylamine carboxylates, preferably 1-amino-(C5-C8)-alkyl carboxylates.

12. Wherein (c) at least one compound is an alkoxylated C5-C12 alkanol of formula (I) 【Chemical 1】 [wherein p is an integer from 1 to 2, o is an integer from 4 to 10, and m is an integer from 4 to 9], Wherein (c) at least one compound is a glycoside C5-C12 alkanol of formula (II) 【Chemical 2】 [wherein n is an integer from 1 to 5 and m is an integer from 4 to 9], the method according to any one of claims 1 to 11.

13. The method according to any one of claims 1 to 12, wherein the aqueous alkaline cleaning agent solution further comprises (e) at least one water-soluble alkanolamine selected from the group consisting of monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA), preferably 2-aminoethanol.

14. The method according to claim 13, wherein the concentration of (e) at least one water-soluble alkanolamine is used at 6.5 to 9.0 g / L, preferably 7.5 to 8.5 g / L, more preferably 7.8 to 8.2 g / L.

15. Use of the method according to any one of claims 1 to 14 for SAP (semi-additive process) application in the fabrication of electronic device articles having integrated circuits with line / space dimensions from 75 / 75 μm to 8 / 8 μm or less.

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