Method for cleaning non-conductive surfaces and use

Abstract

The present invention relates to a method for cleaning a non-conductive surface of a non-conductive layer for manufacturing an article having an integrated circuit, where the non-conductive layer is a composite material based on an organic polymer and a glass filler and comprises micro blind holes (BMVs), where the non-conductive surface comprises a non-conductive wall surface of the BMVs, wherein the non-conductive layer is attached to a copper layer and wherein the copper layer forms the bottom of the BMV, wherein the method comprises the steps in the following order: (i) providing the non-conductive surface of the non-conductive layer; (ii) treating the provided surface with a decontamination process comprising the following steps in this order: (t1) treating with a sweller 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 in order to remove the glass filler; wherein the aqueous alkaline detergent solution and (iv) drying the surface treated in step (iii) in order to obtain a dry surface, preferably an anhydrous surface; and uses 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, which is a composite material based on an organic polymer and a glass filler and comprises blind micro vias (BMVs), for manufacturing articles with integrated circuits, and its use. In particular, the method is used to remove glass fillers from non-conductive surfaces including the wall surfaces of blind micro vias and in particular to provide a cleaned surface for subsequent pretreatment and metal plating in the manufacture of articles, such as multilayer assemblies as printed circuit boards, especially fine line IC substrate boards, where circuit features as blind micro vias can be filled with metal. In particular, the method can be used for SAP applications. Background Art

[0002] Faced with the increasing demand for miniaturization, modern electronics manufacturers must pursue the trend of increasingly densely interconnected multilayer printed circuit boards. Epoxy composites are the preferred insulating materials due to their low cost and well-balanced physical, chemical and mechanical properties. The latest epoxy build-up laminates contain increasing amounts of spherical glass fillers, which are required to compensate for the CTE mismatch between the epoxy resin matrix and the electroplated copper circuits. In addition, their small size (about μm and below) allows for smoother surface morphology compared to glass fiber bundle reinforced matrix materials.

[0003] After inserting different recesses as traces, blind micro vias (BMVs) or through holes (THs) into a resin-based substrate containing glass fillers by mechanical or laser drilling, a series of different wet chemical processes are applied to the surface of the substrate. Such processes are wet chemical decontamination processes to remove the residues of the drilling process, followed by pretreatment processes to prepare the surface for subsequent electroless and / or electrolytic metal plating. During industrial decontamination processing, the adhesion of the glass fillers exposed at the surface of the substrate and at the surface of the recesses will be weakened and their anchoring in the surrounding resin matrix will be lost or damaged. If these fillers are not removed, the remaining weakly bonded or loose fillers can cause low adhesion of plated copper on epoxy resin, and contaminated copper-copper connections in micro blind vias or through holes (THs). This can affect the yield in production and the reliability of the final product.

[0004] Common methods to overcome glass filler contamination include fluoride etching solutions described in US2012 / 0298409 A1 and ultrasonic treatment described in US2007 / 0131243 A1. None of these strategies can be easily applied to the vertical mode of semi-additive processing (SAP). The significant health issues of fluoride etching solutions quickly disqualify them for use in much of the industry, while in the vertical mode, ultrasonic application, even in basket applications, is extremely difficult to employ in a uniform manner to have a large enough impact on each panel.

[0005] JP 2010-229536 A discloses a pretreatment agent for cleaning the surface of a resin substrate containing a silica-based filler, wherein the filler and the glass fiber exposed on the substrate surface after desmear treatment, etc. should be removed. The pretreatment agent includes an alkaline, nonionic ether-type surfactant and an amine-based complexing agent.

[0006] US2010 / 056416 A1 discloses a cleaning composition having a limited number of natural ingredients containing anionic surfactants, hydrophilic syndetic selected from C6 alkyl polyglucosides, nonionic surfactants and hydrophobic syndetics such as oleic acid or palmitic acid, wherein the composition has a pH of 7 to 13. The cleaning composition can be used for cleaning laundry, soft surfaces and hard surfaces.

[0007] Particularly in SAP applications, which require the entire surface of a non-conductive substrate to be metal plated to begin the SAP application, cleaning and plating of the substrate cannot be achieved with good reliability.

[0008] In addition to the problems mentioned of providing good cleaning and plating compositions for the constantly new substrate materials and process chemistries provided, the cleaning and plating processes also have to be constantly adapted. For example, due to the new materials, the decontamination process takes more and more time and requires more measures than the subsequent process steps in the pretreatment and metallization. In particular, a good handover from one part of the process sequence to another or from one process bath to another has problems due to evolving material properties after treatment, drag-out problems, different holding and processing times in the entire metallization process of non-conductive materials, etc.

[0009] Objectives of the invention

[0010] It is therefore an object of the present invention to overcome the disadvantages of the background art and to provide a way to achieve improved cleaning, which includes removing loose glass fillers from non-conductive surfaces of various composite materials with organic polymers and glass fillers, wherein the glass fillers are exposed on the surface of the composite materials after drilling recessed structures as micro blind vias or through holes and have low adhesion.

[0011] Another object of the invention is to provide a way for preparing a cleaned non-conductive surface after drilling recess structures as blind micro vias, which allows improving the peel strength results after metal plating.

[0012] Yet another object of the present invention is to provide a means for improving the removal of glass fillers which improves the handling of different process steps and the flexibility in using new treatment bath compositions.

[0013] Yet another object of the present invention is to improve adsorption and achieve uniform distributed deposition of the activator as a palladium catalyst onto the surface of the substrate, thereby imparting to the catalyst enhanced adhesion of subsequent copper plating and improved copper bonding reliability. At the same time, the consumption of the activator should be as low as possible.

[0014] Yet another object of the present invention is to use the method for manufacturing electronic articles as multilayer assemblies as fine line IC substrates, preferably based on SAP applications. Summary of the invention

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

[0016] In one aspect of the present invention, there is provided:

[0017] A method for cleaning a non-conductive surface of a non-conductive layer for manufacturing an article with an integrated circuit, wherein the non-conductive layer is a composite material based on an organic polymer and a glass filler and comprises blind micro vias (BMVs), wherein the non-conductive surface comprises a non-conductive wall surface of the BMVs, wherein the non-conductive layer is attached to a copper layer and wherein the copper layer forms the bottom of the BMVs, wherein the method comprises the steps in the following order:

[0018] (i) providing the non-conductive surface of the non-conductive layer;

[0019] (ii) treating the provided surface using a desmearing process, the desmearing process comprising the following steps in the stated order: treating with a swelling agent solution comprising water and an organic solvent, treating with an aqueous etching solution comprising an oxidizing agent, and treating with an aqueous reducing solution comprising a reducing agent, so as to obtain a desmeared surface;

[0020] (iii) treating the surface treated in step (ii) with an aqueous alkaline detergent solution to remove the glass filler, wherein the aqueous alkaline detergent solution comprises:

[0021] (a) at least one surfactant selected from the group consisting of saturated branched or unbranched C5 to C12 carboxylic acids or salts thereof, wherein the concentration of the at least one surfactant (a) is 0.9 to 1.7 g / L;

[0022] (b) at least one surfactant selected from the group consisting of saturated branched or unbranched C5 to C12 alkyl groups and saturated C3-C8 alkyl aminocarboxylates having a negatively charged group selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate;

[0023] (c) at least one compound having at least one hydroxyl group and at least one COC group, wherein the compound is selected from the group consisting of alkoxylated C5-C12 alkanols and glycosidic C5-C12 alkanols; and

[0024] (d) an alkali metal hydroxide, wherein the concentration of the (d) alkali metal hydroxide is 65 to 200 g / L;

[0025] (iv) drying the surface treated in step (iii) to obtain a dry surface, preferably a water-free surface.

[0026] In another aspect of the present invention, there is provided the use of the above method for SAP (semi-additive process) application in manufacturing an article with integrated circuits having line / space dimensions of 25 / 25 μm to 8 / 8 μm or less.

[0027] Further aspects of the invention can be learned from the dependent claims or the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Those skilled in the art will appreciate the features by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 Results illustrating cleaning performance on non-conductive surfaces by SEM. DETAILED DESCRIPTION

[0030] Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. The effects and features of the exemplary embodiments and methods for implementing the same will be described with reference to the accompanying drawings. In the accompanying drawings, similar element symbols represent similar elements, and redundant descriptions are omitted. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. In addition, the use of "may" when describing embodiments of the present invention refers to "one or more embodiments of the present invention."

[0031] In the following description of the embodiments of the present invention, unless the context clearly indicates otherwise, terms in the singular may include plural forms. For example, if "filler" or "blind micro hole" is used hereinafter, it includes "plurality of fillers" or "plurality of blind micro holes".

[0032] The following description also uses the term "substrate" or "non-conductive surface of the substrate" to simplify reading. In this context, the substrate is established by a non-conductive layer attached to a copper layer, wherein the substrate has a non-conductive surface of the non-conductive layer to be treated by the present invention and a copper surface of the copper layer, thereby also establishing the bottom of the micro blind vias drilled into the non-conductive layer.

[0033] An aqueous solution in the context of the present invention is a solution which contains more than 50% by weight of water.

[0034] In the context of the present invention, an oxidizing agent is suitable for oxidizing a compound or material, in particular a non-conductive surface of a non-conductive layer, wherein the oxidizing agent is reduced. In other words, the oxidizing agent is a substance that obtains or "accepts" / "receives" electrons from a reducing agent (e.g., a non-conductive surface or, more precisely, a material of the surface) in a redox chemical reaction.

[0035] In the context of the present invention, the reducing agent is suitable for reducing a compound, in particular a compound on the oxidized non-conductive surface of the non-conductive layer, wherein the reducing agent is oxidized. In other words, the reducing agent is a substance that donates the electrons of the reducing agent to the compound to be reduced, such as the compound on the non-conductive surface, in a redox chemical reaction.

[0036] The present invention is particularly suitable for use with a combination of a decontamination treatment and a glass filler removal treatment and prior to a pretreatment (preferably including palladium activation prior to treating the non-conductive surface according to the present invention), wherein the composite material comprises a glass filler in the form of a spherical glass filler, which is, for example, part of a SAP matrix material. Using the present invention, exposed glass fillers (which become loose or less adherent during the drilling and decontamination processes) can be removed from the surfaces (including the wall surfaces of the BMV and the through holes (TH)) and a treated surface is provided so that the adhesion of the subsequently deposited metal layer is improved. The present invention provides a cleaned surface of a non-conductive layer, including the non-conductive wall surfaces of the BMV and (TH) for a subsequent electroless and / or electrolytic metal plating process, which begins with a pre-treated dry surface.

[0037] In one embodiment, the non-conductive surface further comprises a wall surface of the TH, and the through hole is through from the surface of the non-conductive surface to the surface of the copper layer to establish the TH.

[0038] The invention allows in particular to separate the pretreatment process from the cleaning process within the complete metallization process, the cleaning process including the desmearing process, which is usually done in a wet in wet sequence in close follow-up of all the individual process steps. This results in greater flexibility between these two important processes in view of the longer time required for the desmearing process and / or in view of the alternative use of bath compositions for pretreatment.

[0039] The present invention leads to higher yield and better reliability of the manufactured multilayer assemblies as printed circuit boards, wherein the adhesive properties on industrial relevant IC substrates and printed circuit board substrates have shown significantly higher peel strength values ​​after treatment using the novel process.

[0040] In particular, the present invention enables the manufacture of electronic articles with integrated circuits, such as IC substrate articles with line / space dimensions (L / S) of 25 / 25 μm down to 8 / 8 μm, preferably 15 / 15 μm to 8 / 8 μm or more preferably less than 8 / 8 μm. At the same time, the process provides excellent coverage performance.

[0041] The present invention uses less hazardous components than those used in the background art. In addition, the present invention enables the manufacture of electronic products under milder conditions in view of the operating temperature and operating time. This results in significantly reduced energy consumption and improved yield. The lower temperature scheme also reduces equipment and maintenance costs.

[0042] One of the most desired benefits of cleaning non-conductive surfaces from loose glass fillers is to increase the adhesion of electroplated copper to the cleaned surface. An obvious reason for the expected increase in such adhesion would be to assume that the "loose" glass filler does not bond well to the substrate. This should be the case for less than half of the filler embedded in the surrounding epoxy resin after decontamination or for any re-adsorbed filler. Copper is then plated around the filler and, after applying a peeling force, it is easily lifted from the substrate. Surprisingly, the drying step further improves the adhesion of the subsequently deposited metal layer and also results in an improved distribution of the activator while reducing the amount of activator density. The last effect is particularly helpful in saving money and resources.

[0043] The invention can be used in various different substrates from different suppliers, wherein the non-conductive layer is a composite material based on organic polymers and glass fillers, to which the copper layer is attached, for example by lamination, which establishes the substrate to be processed.

[0044] Composite materials are based on mixtures of glass fillers and / or silica fillers with organic polymers in the form of resins and / or plastics and blends thereof. Resins and plastics include dielectric materials commonly used in the electronics industry to be metallized. Resins and plastics are preferably selected from epoxy, isocyanate, bismaleimide triazine and phenylene resins as epoxy resins; polyesters such as polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene, acrylonitrile-butadiene-styrene (ABS) copolymers, polyamides (PA), polycarbonates (PC), and mixtures and blends thereof.

[0045] The organic polymer more preferably comprises a polyimide resin or an epoxy resin, wherein the polyimide resin may be modified by adding polysiloxane, polycarbonate, polyester or the like. The epoxy resin may be a glass filler epoxy sheet material comprising a combination of an epoxy resin and a glass filler, or it may be modified to have low thermal expansion and a high glass transition temperature, thereby constituting a high glass transition temperature glass filler epoxy sheet material.

[0046] Suitable glass fillers are preferably selected from borosilicate glass, quartz glass, silica glass, fluoride glass. The sizes of the different fillers have diameters ranging from 0.01 μm to 5 μm, and preferably have a diameter of 0.5 μm on average.

[0047] Preferably, the composite material of the non-conductive layer is a build-up film, such as an epoxy matrix material. Detailed names will be provided when necessary. The size of the embedded glass filler has an average diameter of 0.5 μm and a maximum of 5.0 μm.

[0048] The substrate according to the invention may comprise a core layer. In such case, the copper layer attached to the non-conductive layer is further attached to the core layer. The core layer makes handling of the more flexible substrate easier and avoids undesired twisting of the substrate.

[0049] In another embodiment, two substrates may be attached to a core layer. In this case, the copper layer of each substrate is attached to the core layer while the non-conductive layer is the outer layer. This enables the non-conductive layers of two substrates comprising a core layer to be processed and multilayer assemblies to be built up from both sides of the core layer.

[0050] The core layer may be selected from the group consisting of printed circuit board substrates, circuit-carrying substrates, interconnect device substrates, and precursors for any of the foregoing. Such substrates and precursors include 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 PCB dielectric materials with good electrical specifications known to the skilled person, such as 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 high-temperature epoxy resin adhesive (FR-5); copper-clad materials, SAP materials, IC substrates, and laminates thereof, preferably, the core layer is FR4 material, SAP material, or IC substrate.

[0051] The decontamination process in step (ii) is carried out before step (iii), preferably without any further wet chemical steps as rinsing steps.

[0052] The decontamination process includes sub-steps (t1), (t2) and (t3),

[0053] wherein (t1) comprises treating the non-conductive surface of the non-conductive layer with a swelling agent solution comprising water and an organic solvent to obtain a swollen surface,

[0054] wherein (t2) comprises treating the swollen surface with an aqueous etching solution comprising an oxidizing agent to obtain an etched surface, and

[0055] Wherein (t3) comprises treating the etched surface with an aqueous reducing solution comprising a reducing agent to obtain a decontaminated surface.

[0056] By applying the corresponding sub-steps ( t1 ), ( t2 ) and ( t3 ), a particularly effective desmearing process can be ensured, wherein a major part of the residues deriving from the drilling process (the so-called smears) are removed.

[0057] The swelling agent solution penetrates the non-conductive surface of the non-conductive layer, which results in a swollen surface, where the bonding strength of (weakly) bound particles such as glass fillers or drilling residues within the surface will be further weakened. Preferably, the organic solvent of the swelling agent solution is selected as a glycol ether and / or a lactam and penetrates into the through holes and the exposed resin surface of the BMV. Most preferably, the solution is selected as the commercially available Securiganth MV swelling agent.

[0058] Preferably, the organic solvent is applied to the aqueous 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.

[0059] Preferably, the swelling agent solution has a pH of 9.5 to 12, preferably 10.5 to 11.5.

[0060] Preferably, (t1) is carried out at a temperature of 55 to 90°C, preferably 70 to 85°C, for a duration of 2 to 10 minutes, preferably 4 to 5 minutes.

[0061] The aqueous etching solution of (t2) may contain an oxidant, more preferably hydrogen peroxide and sulfuric acid. Preferably, the aqueous etching solution is selected as an alkaline aqueous etching solution, more preferably potassium hydroxide or sodium hydroxide solution, and contains an oxidant, more preferably potassium permanganate. Most preferably, the etchant is selected as commercially available Securiganth P500 or Securiganth MV P-Etch.

[0062] Preferably, (t2) treatment with an aqueous etching solution, preferably comprising 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.

[0063] 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.

[0064] The aqueous reducing solution (t3) comprises a reducing agent such as ammonium hydroxysulfate or hydrogen peroxide and is preferably an acid, most preferably sulfuric acid or hydrochloric acid, wherein the reducing agent is capable of reducing the metal leftover from the previous step. Optionally, the aqueous reducing solution (t3) may use a conditioning agent compound to obtain an aqueous reducing conditioning agent solution. The aqueous reducing conditioning agent solution preferably comprises an acid (such as sulfuric acid or hydrochloric acid), an agent such as manganese dioxide that is on the surface of the non-conductive surface after application of the aqueous etching solution (such as ammonium hydroxysulfate or hydrogen peroxide) of (t2), and a polymer containing quaternized nitrogen atoms. For example, the polymer commercially available from Atotech Deutschland GmbH can be used. MV reducing solution or MV reduction regulator.

[0065] Preferably, (t3) is performed at a temperature of 40°C to 55°C for a duration of 3 minutes to 7 minutes.

[0066] Step (iii) treating the surface treated in step (ii) with an aqueous alkaline detergent solution:

[0067] By applying said step (iii) after the desmearing process, the remaining part of the residues derived from the drilling process is removed, but now more importantly the loose glass fillers will be fully removed.

[0068] The concentration of the at least one surfactant (a) in the aqueous alkaline detergent solution is 0.9 to 1.7 g / L, preferably 1.0 to 1.5 g / L, more preferably 1.2 to 1.4 g / L. In the case where two or more surfactants are contained in the solution, the total concentration is also 0.9 to 1.7 g / L, preferably 1.0 to 1.5 g / L, more preferably 1.2 to 1.4 g / L. It should be understood that the surfactant can be added as an acid or a salt.

[0069] The concentration of the at least one surfactant (b) in the aqueous alkaline detergent solution is preferably 0.5 to 10 g / L, more preferably 1.5 to 9 g / L, most preferably 2 to 8 g / L. Other preferred concentration ranges are 0.5 to 1.2 g / L, preferably 0.7 to 1.1 g / L, more preferably 0.75 to 1.0 g / L. In the case where two or more surfactants are contained in the solution, the total concentration is also 0.5 to 10 g / L. In a preferred embodiment, the concentration of the at least one surfactant (b) selected from the group consisting of saturated branched or unbranched C5 to C12 alkyl groups having negatively charged groups selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate is in the range of 0.5 to 1.2 g / L, preferably 0.7 to 1.1 g / L, more preferably 0.75 to 1.0 g / L. In another preferred embodiment, the concentration of the at least one surfactant (b) selected from the group consisting of saturated C3-C8 alkylaminocarboxylates is in the range of 0.5 to 10 g / L, preferably 1.5 to 9 g / L, more preferably 2 to 8 g / L.

[0070] The concentration of the at least one compound (c) having at least one hydroxyl group and at least one COC group in the aqueous alkaline detergent solution is preferably 0.7 to 1.3 g / L, more preferably 0.8 to 1.2 g / L, most preferably 0.9 to 1.1 g / L. In the case where two or more alkanols are contained in the solution, the total concentration is also 0.7 to 1.3 g / L, preferably 0.8 to 1.2 g / L, more preferably 0.9 to 1.1 g / L.

[0071] The concentration of (d) alkali metal hydroxide results in a pH value that is strongly alkaline and has a calculated pH value higher than pH 14. The concentration of (d) alkali metal hydroxide in the aqueous alkaline detergent solution is 65 to 200 g / L, preferably 70 to 100 g / L, more preferably 75 to 90 g / L.

[0072] It should be noted that throughout the specification and claims, the numerical limits of the disclosed ranges and ratios may be combined and are deemed to include all intervening values. In addition, all numerical values ​​are deemed to be preceded by the modifier "about", whether or not the term is specifically noted.

[0073] The at least one surfactant is selected from the group consisting of saturated branched or unbranched C5 to C12 carboxylic acids or salts thereof and is preferably a saturated branched C6 to C10 carboxylic acid or salt, preferably hexanoic acid, octanoic acid and dodecanoic acid or salts thereof, more preferably hexanoic acid and octanoic acid or salts thereof. The surfactant selected from the group consisting of saturated unbranched C6 to C10 carboxylic acids or salts, more preferably saturated unbranched C6 to C8 carboxylic acids or salts is preferably unsubstituted hexanoic acid and octanoic acid.

[0074] The at least one surfactant selected from the group consisting of saturated branched or unbranched C5 to C12 alkyl groups having a negatively charged group selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate is preferably selected from the group consisting of saturated branched or unbranched C5 to C8 alkyl groups having a negatively charged group selected from sulfate, phosphate and carbonate, more preferably having a negatively charged group of sulfate (e.g., n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, n-heptyl or n-octyl), most preferably, the surfactant is sodium 2-ethylhexyl sulfate or sodium isoheptyl sulfate.

[0075] The positive counterion of the saturated branched or unbranched C5 to C12 alkyl group having a negatively charged group is preferably sodium or potassium, more preferably sodium.

[0076] The saturated C3-C8 alkylaminocarboxylate is preferably a compound of formula (III) or (IV)

[0077]

[0078] Wherein R is a branched or unbranched C4-C8 alkyl group, such as n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, n-heptyl, and n-octyl.

[0079] or

[0080]

[0081] wherein k is an integer from 3 to 8, preferably from 4 to 6, most preferably 6.

[0082] It will be appreciated that the surfactant is preferably added as a salt. The positive counterion of the saturated C3-C8 alkylaminocarboxylate is preferably sodium or potassium, more preferably sodium.

[0083] The at least one compound (c) is selected from the group consisting of alkoxylated C5-C12 alkanols and glycosidic C5-C12 alkanols.

[0084] The alkoxylated C5-C12 alkanol of compound (c) is preferably a compound of formula (I)

[0085]

[0086] 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, more preferably, p is 1, o is 5 to 7 and m is 5 to 7. Most preferably, the alkoxylated C5-C12 alkanol is ethoxylated hexanol or ethoxylated octanol, wherein o is 6.

[0087] The average MW (molecular weight) of the compound of formula (I) is 200 to 15000 g / mol, preferably 400 to 1000 g / mol, most preferably 300 to 600 g / mol.

[0088] The glycoside C5-C12 alkanol of compound (c) is preferably a compound of formula (II)

[0089]

[0090] wherein n is an integer from 1 to 5 and m is an integer from 4 to 9, preferably from 5 to 7. Preferably, the compound is an alkyl polyglucoside (APG) provided as CAS 54549-24-5.

[0091] Preferably, the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, more preferably sodium hydroxide.

[0092] 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 etasulfate), sodium isoheptyl sulfate and alkylaminocarboxylates of 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, wherein o is 6) and glycosidic 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.

[0093] In a more preferred embodiment, the aqueous alkaline cleaning agent solution of the present invention comprises the following combination: (b) sodium edetate and (c) ethoxylated hexan-1-ol; (b) 1-aminohexyl carboxylate and (c) ethoxylated and decan-1-ol; or (b) APG and (c) 2-ethylhexyl imine dipropionate. Preferably, these compositions are used together with (a) hexanoic acid and (d) sodium hydroxide. In an even more preferred embodiment, the aforementioned combination is used together with monoethanolamine. Most preferably, the aqueous alkaline cleaning agent solution of the present invention consists of the aforementioned combination.

[0094] Preferably, the aqueous alkaline detergent solution additionally comprises (e) at least one water-soluble alkanolamine selected from the group consisting of monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA), preferably 2-aminoethanol. By using water-soluble alkanolamines, turbidity of the solution can be avoided. In our experiments it could be shown that turbid solutions lead to undesirable plating results.

[0095] The concentration of the 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.

[0096] The method can be used in vertical and horizontal plating equipment. Preferably, the method is used in a vertical plating equipment, wherein the substrate is transported by a conveying device to be processed through a processing module of the plating equipment.

[0097] The method of the present invention is preferably used if the treatment (iii) is carried out at 55°C to 65°C for 3 to 7 minutes. Low temperatures reduce energy consumption and also equipment costs for using higher temperatures. In addition, evaporation of low-boiling components can be prevented and strong suction can be avoided.

[0098] 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, so as to obtain a dry surface. The drying step can be carried out by, for example, infrared heating, conventional heating, heated air blowing or a combination thereof.

[0099] It is important that the surface is dry, preferably free of water, to avoid undesired chemical or physical reactions and thus achieve the most optimal results for subsequent processing steps. The drying step surprisingly allows to postpone the following processing steps or to stop the entire process for a certain time, and then start the subsequent process steps without damaging, degrading or damaging the non-conductive surface while waiting. This is particularly useful if the decontamination processes should be performed separately (locally and / or in time) because of different requirements for chemicals and / or necessary process times. The separation performance can be achieved in different processing modules (one for cleaning and one for pretreatment).

[0100] In one embodiment, the method of the present invention further comprises a further step (vi) after step (iv) of treating the surface of step (iv) with an aqueous alkaline detergent solution comprising ethanolamine. The steps may be performed in a cleaning module, in a separate module or in a pretreatment module according to the following process steps. If step (vi) is performed in a cleaning module or in a separate module, the step may be omitted in the following pretreatment steps (v) to (ix).

[0101] Thus, the method of the present invention can be used as the first part of a metal plating process of the non-conductive surface, the metal plating process comprising cleaning, pretreatment and metal plating. The method of the present invention is preferably used before activating the non-conductive surface, for example by using a palladium activator solution, for subsequent metal plating to manufacture articles with integrated circuits (e.g., multilayer assemblies such as fine line IC substrate articles).

[0102] Thus, as a non-limiting example, the method may preferably further comprise a step after step (iv) for pre-treating the surface in order to prepare the surface for subsequent electroless and / or electrolytic metal plating, wherein the further steps comprise the following in this order:

[0103] - optional step (v) treating the surface of step (iv) with an aqueous alkaline detergent solution comprising ethanolamine;

[0104] - step (vi) treating the surface of step (v) with an aqueous etching cleaner solution comprising persulfate;

[0105] - step (vii) treating the surface of step (vi) with a pre-impregnation solution;

[0106] - step (viii) treating the surface of step (vii) with an activator solution, the activator solution preferably comprising noble metal ions, metal colloids or carbon-containing compounds; and

[0107] - step (ix) treating the surface of step (vii) with a reducing agent solution if the activator solution comprises noble metal ions.

[0108] If step (v) has been performed previously, it may be omitted.

[0109] In another embodiment of the present invention, step (v) is optional. In a preferred embodiment, step (v) is performed to further improve the subsequent metal plating results.

[0110] Step (v) is preferably performed at 50° C. to 70° C. for 3 to 7 minutes. In a preferred embodiment, the cleaning agent comprises 10 to 20 g / L sodium hydroxide and 10 to 16 g / L ethanolamine (MEA).

[0111] Step (vi) is preferably performed at 25° C. to 40° C. for 1 to 2 minutes. In a preferred embodiment, the cleaning agent comprises 100 to 150 g / L sodium persulfate and 30 to 45 g / L sulfuric acid.

[0112] The optional step (vii) is to treat the surface of step (vi) with a pre-dip solution. The pre-dip solution is an aqueous solution, preferably comprising a pH adjuster (preferably sulfuric acid and / or sodium bisulfate) and a non-ionic surfactant. The non-ionic surfactant is preferably a polyethylene glycol (PEG) compound, more preferably PEG 1500MW or PEG 10,000MW.

[0113] The pre-dip solution is preferably an acidic aqueous pre-dip solution, preferably having a pH of 2 to 4.

[0114] Step (viii) treating the surface of step (vii) with an activator solution, the activator solution preferably comprising noble metal ions, metal colloids or carbonaceous compounds. The activator solution is preferably an aqueous solution comprising noble metal ions or metal colloids. The activator solution is applied to the surface of the non-conductive layer, preferably treating the surface with an aqueous palladium activator solution, wherein a layer of palladium ions is deposited on the surface of the non-conductive layer of step (viii). Other useful activator solutions known in the art may comprise carbon, conductive polymers or metal colloids containing, for example, copper or palladium-tin for subsequent electrolytic direct metal plating.

[0115] The palladium activator solution comprises at least one palladium ion source. In addition, the solution may comprise other metal ion sources, such as ruthenium ion sources, rhodium ion sources, palladium ion sources, osmium ion sources, iridium ion sources, platinum ion sources, copper ion sources, silver ion sources, nickel ion sources, cobalt ion sources, gold ion sources and mixtures thereof. The palladium ions and the other metal ions are adsorbed on the surface of the substrate.

[0116] (ix) If a palladium activator solution is used, treating the substrate of step (viii) with a palladium reducing solution, wherein the deposited palladium ion layer of step (viii) is converted into a metallic palladium layer.

[0117] The treatment of the surface of the substrate comprising at least palladium ions is carried out with a palladium reducing solution comprising at least one reducing agent, wherein the reducing agent is suitable for reducing metal ions to a metallic state (at least the palladium ions) adsorbed on the surface of the substrate, and is selected from the group consisting of a boron-based reducing agent, a source of hypophosphite ions, hydrazine and hydrazine derivatives, ascorbic acid, isoascorbic acid, a formaldehyde source, glyoxylic acid, a glyoxylic acid source, glycolic acid, formic acid, sugars and salts of the aforementioned acids.

[0118] The method of the present invention further comprises a step (x) for electroless metal plating of said surface and / or a step (xi) for electrolytic metal plating of said surface after step (viii) or (ix) to obtain a metal-plated surface, preferably a copper surface. Step (x) is preferably carried out with an electroless copper plating bath to obtain a copper layer on the layer of step (ix).

[0119] In general, an electroless plating bath comprises a solvent, typically water, and a source of at least one metal ion to be deposited. Other optional components are complexing agents (or chelating agents) for the metal ions (such as those mentioned below), reducing agents for the metal ions, stabilizers, co-solvents, wetting agents, and functional additives such as brighteners, accelerators, inhibitors, anti-tarnish agents. Such baths and components are known in the art. The electroless copper plating bath may further comprise a source of nickel ions, a source of cobalt ions, and mixtures thereof.

[0120] The electrolytic metal plating of the surface in step (xi) after step (viii) is carried out with an electrolytic copper or nickel plating bath (if a layer of carbon or conductive polymer is deposited on the surface in step (vi) or (vii)) to obtain a copper layer or a nickel layer on the surface while filling the BMV with copper or nickel. The copper or nickel layer may be a copper alloy or a nickel alloy containing an alloying metal such as tungsten or silver.

[0121] If desired, additional steps may be performed between the above steps such as, for example, a rinse step using DI water or an aqueous acidic or alkaline solution; an etch cleaner step; a pre-dip step; and / or a drying step.

[0122] In addition to the solutions of the invention in the above steps, the bath compositions and solutions used are well known in the art per se. Suitable solutions for decontamination processes include palladium activator solutions, palladium reduction solutions, electroless and electrolytic copper solutions, which are known to the public and can be prepared, for example, as MV Cleaner PF, MV Etching Cleaner, MV activator, MV reducing agent, MV and AC was purchased from Atto Technology Co., Ltd.

[0123] In a preferred embodiment of the present invention, the electrolytic plating bath in step (xi) is an electrolytic copper plating bath to obtain a copper layer. The resulting substrate of step (xi) can be used to build a multilayer assembly by using the following steps of SAP application:

[0124] In one embodiment, the copper layer of step (xi) may be structured by known process steps including applying photoresist, structuring, patterning, stripping the photoresist and finally etching down to the surface of the non-conductive layer to obtain conductive structures on the non-conductive layer.

[0125] The invention will now be described with reference to the following figures and non-limiting examples.

[0126] Examples

[0127] The relative ratios of the compounds of the invention used in the examples were found to be preferably useful but should not be considered limiting. All components of the test solutions were diluted in DI (DI - deionized water).

[0128] Three groups of test samples were prepared—legs 1, 2, 3, 4, 5, 6, 9, and 10 (inventive example—legs 5 and 6, and comparative example—legs 1, 2, 3, 4, 9, and 10).

[0129] All test specimens (legs) were processed according to the decontamination process (t1 to t3), where (t3) was performed with conditioner (legs 1, 3, 5, and 9) and without conditioner (legs 2, 4, 6, and 10) according to the following scheme:

[0130]

[0131]

[0132] The Inventive Example (Inventive Example 1 (Legs 5 and 6) was treated with an aqueous alkaline detergent 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).

[0133] The comparative examples (legs 1 and 2) were not treated using step (iii) but were dried according to step (iv) at 90°C for 15 minutes.

[0134] The comparative examples (legs 9 and 10) were treated including step (iii) but without drying according to step (iv).

[0135] The comparative examples (legs 3 and 4) were treated using step (iii) but were dried at 90°C for 15 minutes prior to step (iii).

[0136] Example 1 of the invention using the aqueous alkaline detergent solution of step (iii) (legs 5, 6)

[0137] Concentration in the solution:

[0138]

[0139] 1. Naked eye visual inspection

[0140] A set of test samples were used to take SEM images, which are shown in Figure 1 (imaged by SEM, magnification = 5kx, showing the non-conductive surface of the non-conductive layer) to evaluate the glass filler removal performance (legs 1, 2, 3, 4, 5, 6, 9, 10).

[0141] It can be seen that the cleaning results for legs 1 and 2 are very poor, with much glass filler remaining on the surface. Legs 3 to 9 undergo all of step (iii) of use and therefore show good cleaning results comparable to legs 1 and 2. However, legs 5 and 6 achieve the most optimal cleaning results, with slightly more glass filler removed in direct comparison to legs 3, 4, 9 and 10.

[0142] 2. Plating results

[0143] Two groups of test cases were used to further process legs 1, 2, 3, 4, 5, 6, 9, 10 according to the following scheme according to steps (v) to (x):

[0144]

[0145]

[0146] After step (ix), a set of test example legs 1, 2, 3, 4, 5, 6, 9, 10 were used to determine the degree of palladium loading on the surface in [μg / dm 2 The results can be seen in Table 1.

[0147] After step (x), a set of test example legs 1, 2, 3, 4, 5, 6, 9, 10 were used to determine the degree of palladium loading on the surface in [μg / dm 2 The results can be seen in Table 1.

[0148] Table 1

[0149]

[0150]

[0151] As can be seen in Table 1, the highest peel strength results can be achieved for legs 5 and 6. Interestingly, these results can be achieved when the palladium loading on the surface is at a minimum. This saves palladium consumption, while on the other hand, can improve reliability due to better peel strength.

Claims

1. A method for cleaning a non-conductive surface of a non-conductive layer to manufacture an article with an integrated circuit, wherein the non-conductive layer is a composite material comprising an organic polymer and a glass filler and comprises a blind micro via (BMV), wherein the non-conductive surface comprises a non-conductive wall surface of the BMV, wherein the non-conductive layer is attached to a copper layer and wherein the copper layer forms the bottom of the BMV, wherein the method comprises the steps in the following order: (i) providing the non-conductive surface of the non-conductive layer; (ii) treating the provided surface using a decontamination process, the decontamination process comprising the following steps in this order: (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 detergent solution to remove the glass filler, wherein the aqueous alkaline detergent solution comprises: (a) at least one surfactant selected from the group consisting of saturated branched or unbranched C5 to C12 carboxylic acids or salts thereof, wherein the concentration of the at least one surfactant (a) is 0.9 to 1.7 g / L; (b) at least one surfactant selected from the group consisting of saturated branched or unbranched C5 to C12 alkyl groups having negatively charged groups selected from sulfate, sulfite, sulfonate, phosphate, phosphite and carbonate, and saturated C3-C8 alkyl aminocarboxylates; (c) at least one compound having at least one hydroxyl group and at least one COC group, wherein the compound is selected from the group consisting of alkoxylated C5-C12 alkanols and glycosidic C5-C12 alkanols; and (d) an alkali metal hydroxide, wherein the concentration of the (d) alkali metal hydroxide is 65 to 200 g / L; (iv) drying the surface treated in step (iii) to obtain a dry surface, preferably a water-free surface.

2. The method according to claim 1, wherein the treatment in step (iii) is performed at 55 to 65°C for 3 to 7 minutes.

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 to 20 minutes.

4. The method according to any one of the preceding claims, wherein the method further comprises, after step (iv), in order to prepare the surface for subsequent electroless and / or electrolytic metal coating, additionally - step (v) treating the surface of step (iv) with an aqueous alkaline detergent solution comprising ethanolamine.

5. The method according to any one of claims 1 to 3, wherein the method further comprises a step for pre-treating the surface after step (iv) in order to prepare the surface for subsequent electroless and / or electrolytic metal plating, wherein the further steps comprise in the following order: - optional step (v) treating the surface of step (iv) with an aqueous alkaline detergent solution comprising ethanolamine; - step (vi) treating the surface of step (v) with an aqueous etching cleaner solution comprising persulfate; - optional step (vii) treating the surface of step (vi) with a pre-dip solution; - step (viii) treating the surface of step (vii) with an activator solution, the activator solution preferably comprising noble metal ions, metal colloids or carbon-containing compounds; and - step (ix) treating the surface of step (vii) with a reducing agent solution if the activator solution comprises noble metal ions.

6. A method according to claim 5, wherein the method further comprises a step (x) for electroless metal coating of the surface and / or a step (xi) for electrolytic metal coating of the surface after step (viii) or (ix) to obtain a metal-coated surface, preferably a copper surface.

7. The method of any of the preceding claims, wherein the non-conductive layer attached to the copper layer is a build-up substrate, wherein the substrate has the non-conductive surface of the non-conductive layer and a copper surface of the copper layer.

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

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

10. The method according to any one of the preceding claims, wherein the (a) at least one surfactant is selected from the group consisting of saturated branched C6 to C10 carboxylic acids or salts, preferably unsubstituted caproic acid, caprylic acid and capric acid.

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

12. The process according to any one of the preceding claims, wherein the at least one compound (c) is an alkoxylated C5-C12 alkanol of formula (I) Where 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 And wherein the at least one compound (c) is a glycoside C5-C12 alkanol of formula (II) wherein n is an integer from 1 to 5 and m is an integer from 4 to 9.

13. The method according to any one of the preceding claims, wherein the aqueous alkaline detergent 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 (e) at least one water-soluble alkanolamine is used in a concentration of from 6.5 to 9.0 g / L, preferably from 7.5 to 8.5 g / L, more preferably from 7.8 to 8.2 g / L.

15. Use of a method according to any of the preceding claims for SAP (Semi-Additive Processing) applications in the manufacture of electronic articles with integrated circuits having line / space dimensions of 75 / 75 μm to 8 / 8 μm or less.

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