Nickel has been selectively deposited on an alumina substrate without any pretreatment from a flow of a nickel acetate solution using the focused beam of an excimer laser. Nickel spots as well as nickel lines were drawn and subsequently plated with an electroless Ni-B coating. Excellent adhesion of the metallized layers was achieved, since with laser irradiation, both etching and deposition took place simultaneously

Boose, C.A.

Harteveld, C.

Kolster, B.H.

Meinders, B.

Shrivastva, P.B.

English

University of Twente Research Information

Surfaceand Coatings Technology,46 (1991) 131—138 131Selectivemetailization of alumina by laserP. B. Shrivastva*, C. A. Boose andB. H. KoistertFoundationfor AdvancedMetalsScience(SGM), P.O. Box 8039, 7550 KA Hengelo (TheNetherlands)C. Harteveld and B. MeindersDepartmentof Physics, University of Twente,Enschede(TheNetherlands)(ReceivedAugust 13, 1990)AbstractNickel hasbeenselectivelydepositedon an aluminasubstratewithout any pretreatmentfrom a flow of a nickel acetatesolution using the focusedbeamof an excimer laser.Nickel spotsaswell asnickel linesweredrawnandsubsequentlyplatedwith anelectrolessNi—B coating.Excellentadhesionof themetallizedlayerswas achieved,sincewith laserirradiation, both etchinganddepositiontook placesimultaneously.1. IntroductionMaskiesslaser-induceddepositionof metalson metafficandnon-metallicsubstrateshas recently becomea field of growing interest [1]. Processesusinglaser-inducedmetaldepositionfrom the gasphase[2, 3], solid phase[4—9] and liquid phase [10—161havebeenreported. Every techniquehasadvantagesand disadvantages,dependingon the application. Gas-phasedepositionis limited by the availabifity of volatile metal—organicor inorganicmaterials,by unwantedsidereactionswhichcausecontaminationof the metaldepositsand by the needfor specializedchambers[4]. Metallization fromthe solid or liquid phaseis thereforesuggestedas a better alternative.Depositionfrom the solid phasehasbeendemonstratedwith thin solidfilms of metallo-organicsor organometalliccomponents[4—9].Copperlineshave beendrawn from copperacetate [5] and formate [6, 7], palladiumfrom its acetate[8] andgold andplatinum from its metallo-organicmaterialscontainingink or resinates[4, 9]. In somecasesof laser-induceddepositionfrom thin solid films, the processis exothermicand leadsto irregular lineprofiles. To minimize this effect and to achievehigh purity, the precursorhas to be tailoredaccordingly [9].Depositionfrom the liquid phasehasthe advantageof being a simpletechnique.The preciousmetals gold andplatinum havebeendepositedby*On leavefrom BhabhaAtomic ResearchCentre, Bombay,India.‘Author to whom correspondenceshould be addressed.0257-8972/91/83.50 © ElsevierSequoia/Printedin The Netherlands132passinga laserbeamthrough aqueousand methanolic solutions of HAuC14andH2PtC16respectively[10]. Commercialelectrolessandelectroplatinggoldsolutions without use of external current have also been investigatedformetallization [11, 12]. Zahaviandcoworkers[121 havesuccessfullyobtainedgold featureson conducting(e.g. platinum), semiconducting(e.g. silicon,GaAs and SiC) and polymeric (e.g. polyimide) materials. However, on non-conductingsubstratessuch as Si3N4 andfused Si02 no depositioncould beachievedbecauseof a largerbandgap energythan that of the laserphotonenergy.The applicationof lasersin electroplatinggold and nickel solutionswith the use of an externalcurrent has beenreportedas a method of highspeedselective maskiessdeposition. [13—15]. Enhancementfor gold wasfound to be 100-fold whilst for nickel it was up to 600-fold with the useof this techniqueon conductingandvacuum-metallizednon-conductingsub-strates[141.Most of the studies in the literature dealwith the depositionof metallayers either on metallic substratesor on semiconductingsurfaces. Littlework has been done on direct metaffization of non-conductingceramicsubstrates,exceptingthe work of Harishet at. [5], in which copperacetatewasdecomposedon aluminaceramicfrom a thin film. Metallo-organicshavethe advantageof decomposingat lower temperatures.There havebeennoreports of metaUizationof metallo-organicsfrom a solution phasewhichwould be an interestingtopic to investigate.In this papera simple method is describedfor selectivedeposition ofnickel on alumina ceramicfrom the liquid phase,i.e. an aqueousacetatesolution.The resultsof lasermetallizationfrom acontinuousflow of aqueoussolution are presented.Metal featuresin the shapeof nickel spots as wellas line patternswereformedusingthe optimum conditionsof fluid flow andlaserpower. Thin layersof depositednickel thusformedwere usedas seedfor electrolesscoatings.2. Experimental detailsThe experimentalset-upconsistedof a lasersystemwith anX—Ymotionandan arrangementfor the substrateincluding a sampleholderalong whicha continuousflow of electrolyte was pumped,as shown in Fig. 1. A xenonchloride excimer laser (Lamda Physik, Model LPX 100) producing 25 ns.pulsesat 308 nm was used in the study. The laserbeamwas focused onthe substratewith a rectangularslit of size 18 mmX 5 mm and with twolensesof focal lengths 500 and 2000. The substrateusedwas commercialalumina of size 50 mmX5OmmXO.60mm, with a purity of 99.5% and of96.0%.The ceramic was thoroughly cleanedultrasonically in water beforelasermetallization. A saturatedsolution of A. R. grade nickel acetatewascirculated over the surfaceof the substrateby meansof a pump at a rate133x—vrcT1~ S~t~FLE~OEER ~Si~///Li~PRmR~E~JTRO..LERFig. 1. Schematicdiagramof experimentalset-up.of 1—1.5 ml s~.The substrateswere irradiated at energiesranging from10 to 110 mJ pulse’ and at a repetition varying from 10 to 100 Hz.The depositedlayerof nickel was cleanedthoroughlyin distified water,activatedin a PumaC-12 activator(Puma ChemicalCorporation,NewYork)andthenimmersedin an electrolessNi—B bath.Theelectrolessbathconsistedof nickel chloride, complexing agentsand dimethylamineborane [16], andwas operatedat pH 6.0 and at a temperatureof 65 °Cfor 1 h.Thethicknessof the depositedfilm wasmeasuredafter lasermetaffizationand also after electrolessNi—B coating using a surfaceproffler (DEKTAK3030) with a stylus of radius 12.5 ,ttm. The structureof the depositswasstudiedusingan opticalmicroscopeandscanningelectronmicroscope(SEM).The presenceof nickel in the metallizeci layer was investigatedby energy-dispersiveanalysis by X-ray (EDAX). The adhesionof the depositedfilmafter electrolessplating was measuredby the “tape peel off” method.3. Resultsand discussion3.1 Localized metaltizationIn the preliminarystudies,thealuminaceramicswere irradiatedfor spotmetallization of nickel from a closed loop flow of aqueousnickel acetatesolution. The laser beamwas focused at a constant energy and varyingrepetition rates and vice versa. Better results were obtainedwith a lowerenergyand a higher repetition rate. Visible metallic layerswere formed atenergiesof 40—60 mJ pulse1 and at frequenciesof 80—100 Hz.134It: 3~S Sc~n: 4mm \.~rt~:~ ~‘42ø~3S Sp~d: L~’ Vor~: 1’s) H~IIZ: .3’2Sumf~ (~1r~ : L~ ,r~jbL~rfl P~3EiEEi-.,ri. @ ~.~Ti41~rn(a)It: 324 5c~ri: 2mm Ve rt:c-.,1~3:3E3 24~2~~i 5pe~d: Lo~. V: rce: 1~ H~r 1 z: lE4lum~::_____iii~iiiilitiji iii ___ ___(c)Fig. 2. Surfaceproffle of (a)aluminaceramicsurface,(b) laser-irradiatedspotat63 mJpulse ~and (c) laser-irradiatedspot at 84 mJ pulse’.135RATE= ~8~CPS TIME= 1ØØLSECFS= 224CNT PRST~ 1ØØLSECA =BASEMATAl 2.I ~ ~~._..I~LLIri~Ii~2.00 4.00 6.00ØCNT 0 . OOKE’.) IOeI)/ch A EDAX(a)RATE= 7SOCPS TIME= IOOL.SECFS= 42BCNT PRST= 100LSECA ~2AAIK.~, L2.00 4.00 6.00OCNT 0 OOKE’J 0e~.)/ch A EDAX(b)Fig. 3. EDAX analysisof (a) alumina ceramicsurface and (b) metallized layer on aluminaceramic.The resultsof the examinationwith the SEM, EDAX andsurfaceprofilerare presentedin Figs. 2—4.Figure 2 shows the surfaceprofiles of a bare ceramicsurfaceand thelaser-irradiatedspots obtained at different energies. The stylus profiler,scanningover a 4 mm length of the bare ceramic,revealedconcavitiesinthe surfacewith an averageroughnessof about 0.39 ~m (Fig. 2(a)). Uponlaserirradiationat variouspowerdensitiesthe etchingof the ceramicsurfaceand depositionof metal over the etched surfaceseemedto occur simulta-neously. This could be clearly seenfrom the typical profiler plots of laser-irradiated spotsobtainedat energiesof 63 and 84 mJ pulse’ (Figs. 2(b)136-Fig. 4. SEM picture of a nickel metal layer on alumina ceramic.Fig. 5. Nickel line drawnon aluminaceramicby laser irradiation from a flow of nickel acetatesolution.and 2(c) respectively) where irregular deposition of the metal layeroccurred.The etching of the ceramic surfaceby meansof the laser irradiationwas also studiedusing the stylus profiler on spotsobtainedseparatelywitha flow of water insteadof an aqueousnickel acetatesolution. With higherpower densities,i.e. 80—100mJ pulse ~, deepetchingof the ceramicsurfaceup to about3 p~mwas observed;however,at energiesof 40—60 mJ pulse1etching was less than 0.3 ,um.The presenceof a metal layer on the irradiatedspots obtainedwith aflow of aqueousnickel acetatesolution was identified by EDAX (Fig. 3) andSEM (Fig. 4). The activated spotsthus obtained were subsequentlyplatedin anelectrolessNi—B bath,confirmingthepresenceof nickel on theirradiatedspots.The adhesionof the depositedelectrolessNi—B coatingwas measuredby a “tape peeloff” test,andit wasfound thatall the depositedfilms adheredwell.3.2 Formation of line patternOn the basis of the preliminary experimentsthe work was extendedtoobtain a line pattern. Initial trial runs with a higher scanrate showednometal line, becauseof the ablation of the metal after deposition. However,with lower scanrates of 200—300 ~m 5 and a laserpower of 40—60 mJpulse~at 100 Hz, gooddepositswith awidth of about 0.5mmwereobtained(Fig. 5).The thicknessof the line drawn (measuredby the surfaceprofiler) wasfound to vary between0.3 and 0.6 jim. Subsequently,the metallizedlayerswere plated to a thicknessof about 3 ~tm in an electrolessNi—B bath. Theadhesionof theselayers, measuredby the “tape peel off” method,passedthe test showinggood adhesionof the coatings.A surfaceprofile and anoptical micrographof the Ni—B coatedlayer are shown in Fig. 6 and Fig.7 respectively.137IL’: i~)~ S.:ar,: ~mm Vert: :34,696A1B:22 04/20/89 Speech: Lot.’ Force: 10 Horiz: B3Sum— - ~ 4Ø,~Ø~3~000— - __t_t~._ 20,000— — — — ___~ 10000~t______~ 0—— __-. -~ ~__ -10,0002~0 4m0 ~ 8u0 1m.~0 1’~i0 1&~0P. 2uir 8 133urn Avg Ht=2S.439~H. •ur~: :34.E:a~5~ 8 SGS.um~lcar t’EVT~-4Ii 3230 Rev. 1.3~I . TVI .2Fig.6. Surfaceproffleof anelectrolessNi—B coatingonaluminaceramicafterlasermetallization.Fig. 7. Optical micrograph of an elecLrulessNi—B coating (original magnification X 100).4. ConclusionsAlumina ceramicwasmetaffizedselectivelywith a nickel layerby laseractivation from a flow of aqueousnickel acetatesolution.Spotmetallizationas well as line patternswere obtained by laser irradiation at energiesof40—60 mJpulsej andat a frequencyof 100 Hz. During the lasertreatmentetching of the ceramic surfaceand depositionof the metal layer occurredsimultaneously,leading to excellent adhesionof the depositedlayer. Withthe optimum powerdensityof the laser, it is possibleto control the etchingof the surfaceto a maximum of 0.2—0.3 ~tm.The extent of depositionof the metal layersdependedon the duratio~nof irradiation. In the systemunderstudy, nickel layersof 0.3—0.6 j.tm wereachieved,which weresuccessfullyusedas seedfor electrolessNi—B plating.Since no pretreatmentof the ceramicsurfaceis required,this processcanbe suggestedas a simple technique for metaffization.138Work is in progress aimed at producing very thin line patterns with afaster scan rate. In addition, metallization with other metallo-organiccom-poundsfrom a flow of aqueoussolution is also in progress.The resultswillbe presentedsoon.AcknowledgmentsThe authorswould like to thank C. B. Jongelirig, H. Hulleman,W. H.J. Bruis and J. Jansenfor their suggestionsand measurements.References1 D. Bäuerle,ChemicalProcessingwith Lasers,Vol. 1, SpringerSeriesonMaterial Science,Springer, Berlin, 1986.2 D. J. Ehrlich and J. Y. Tsao,J. Vac. Sci. Technol. B, 1 (1983) 969.3 B. Markwalder, M. Widmer, D. Braichotte and H. van den Bergh,J. Appi. Phys.,65 (1989)2470.4 R. C. Sausa,A. Guptaand J. R. White, J. Electrochem.Soc., 134 (1987) 2707.5 C. M. Harish, V. Kumar and A. Prabhakar,J. Electrochem.Soc., 135 (1988) 2903.6 A. Guptaand R. Jagannathan,Appl. Phys. Lett., 51 (1987) 2254.7 P. Hoffmarm, B. Lecohier,S. Goldoni and H. van den Bergh, Appi. Surf Sci., 43 (1989)54.8 M. E. Gross,A. Appelbaum and P. K. Gallagher,J. Appl. Phys., 61 (1987) 1628.9 M. E. Gross,G. J. Fisanick, P. K. Gallagher,K. J. SchnoesandM. D. Fennell,Appi. Phys.Lett., 47 (1985) 923; M. E. Gross, A. Appelbaum and K. J. Schnoes,J. ApPI. Phys., 60(1986) 529.10 R. F. Karlicek, V. M. Donnelly and G. I. Collins, J. Appi. Phys., 53 (1982) 1084.11 H. R. Khan, M. U. Kittel and Ch. J. Raub,Plat. Surf Finish., 75 (1988) 58.12 J. Zahavi, S. Tamir andM. Halliwell, Plat. Surf Finish., 73 (1986)57; J. Zahavi,S. Tamir,M. Rotel, G. J. Campisi, M. Halliwell and P. E. Pehrsson,in Proc. 12th World Congr. onSurfaceFinishing, Interfinish ‘88, Association FrancaisedesIngenieurset Techniciensdo l’Electrolyse et des Traitementsde Surface, 1988, p. 329.13 R. J. von Gutfeld, E. E. Tynan,R. L. Melcher and S. E. Blum, Appi. Phys.Lett., 35 (1979)651. R. J. von Gutfeld, M. H. Gelchinski, L. T. Romankiwand D. R. Vigliotti, Appi. Phys.Lett., 43 (1983) 876.14 C. Bocking, Trans. Inst. Met. Finish., 66 (1988) 50.15 M. Fujita, M. Kobayashand S. Hoshinouchi, in Proc. 12th World Congr. on SurfaceFinishing, Interfinish ‘88, AssociationFrancaisedesIrigénieurset Techniciensde l’Elec-trolyse ci. desTraitementsde Surface, 1988, p. 203.16 P. B. Shrivastva,Ph.D. Thesis, Indian Institute of Technology, Bombay, 1986.

Selective metallization of alumina by laser

ChemicalProcessing with Lasers,

Surf Finish.,

https://doi.org/10.1016/0257-8972(91)90155-P

Selective metallization of alumina by laser

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