ie3d教程chap6.docx

ie3d教程chap6.docx

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ie3d教程chap6

Chapter6ModelingofMMIC,RFICandPCBStructures

WehavelearnedthebasicskillstocreateandsimulatestructuresontheIE3Dinthepreviouschapters.Inthischapter,wewilldiscusstheapplicationsofIE3DindesigningMMIC,RFICandPCBstructures.

IE3DisageneralpurposeEMsimulatorwithextremecapability,flexibility,accuracyandefficiencyinmodelingdifferentkindsofhighfrequencystructures.ItiswidelyusedinMMIC,RFICandPCBdesignaswellasantennadesign.Inthischapter,wewillconcentrateonmodelingofMMICandRFICstructures.

MostMMICandRFICstructuresarequitecomplicated.ThelayoutmaybedoneinotherlayouttoolsandweneedtoimportthemintoIE3DandperformthehighaccuracyEMsimulationsonthem.Wewillstartthischapteronimporting.

Section1.DifferentImportandExportFormatsAvailableonIE3D.

ThemostpopularlayoutformatsintheelectronicindustryaretheGDSII（CalmaStream）format,DXF（AutoCad）format,GERBERformatandACISformat.IE3DhasbeenabletoimportandexportfilesinGDSIIformatandCIF（CalTechIntermediateForm）formatdirectly.Recently,wehaveimplementedtheADIXFormatConverter.Itcanperformbi-directionalIE3DGDSIIDXFGERBERACISconversion.

OntheFile->Exportcommand,wehavethefollowingoptions:

（1）DXF;

（2）GDS;（3）3DText（Zeland）;（4）ACIS;（5）GERBER;（6）CIF;（7）FIDELITY.The3DTextisaformatcreatedbyZelandSoftware,Inc.Basically,itallowsyoutowriteastructureasascriptfile.The3DTextformatisdiscussedinAppendixO.TheFIDELITYformatisforexportonly.Basically,youcanexportageometryinMGRIDintotheFIDELITYformatforourFIDELITYsimulator.Itallowsyoutodefinethicknesstopolygonsfor3Dobjects.Onlyhorizontalpolygons（z-directed）,x-andy-directedpolygonscanbeexported.Polygonsofotherorientationwillbeomitted.ExportedFIDELITYstructuresnormallyneedcleanuponFIDELITYbecauseasimulationcanbedone.Moreautomatedexportingwillbeavailableinthefuture.

Inthelastone-year,wehaveimplementedtheAutomaticGeometrytoIE3DFlow（orAGIF）.AGIFcando3jobs:

（1）ConvertGDSIIlayoutintoIE3Dmodelsdirectly.Aftertheconversion,theIE3Dgeometrycanbeafull-3Dmodelcontainingvias,wirebonds,solderballs,andportsandreadyforsimulation.UserscancreateonetemplateforoneMMICorRFICprocess.ThetemplatecanbeusedforalldifferentGDSIIfilesofthesameprocesstodobatchIE3DsimulationsdirectlyfromGDSIIfiles.

（2）PerformIE3DsimulationonacellorselectedpartofacellfromCadenceVirtuosoCustomICDesignPlatform.CadenceVirtuosoisthemostpopularRFICdesignlayouttool.AGIFcansimplifyEMsimulationsofRFICsignificantly.Intheautomaticconversion,AGIFcancleanthestructureforhighefficiencyIE3DEMsimulationswithoutlosingaccuracy.Forexample,pin-viasarepartsofmanysemiconductorprocesses.Simulatingthepin-viasexactlyisprohibitingbecauseofthelargenumberofpinviascankillthesimulationeasily.AGIFcanallowtheuserstomergepinviasintolargeviaswithoutchangingtheelectricalpropertiesofthestructure.Theprocessisdoneautomaticallywithspecificationsfromusers.TherearemanyotheradvancededitingcapabilitiesofIE3DfullyautomatedintoAGIFforstreamlinedIE3DsimulationsfromGDSIIandCadenceVirtuoso.（3）CreateIE3DmodelsdirectlyfromCadenceAllegroInterconnectDesignPlatformandCadenceAPD.CadenceAllegroisaPCBtoolandAPDisapackagingtool.AGIFallowsuserstodefineselectednetsascriticalnets,referencenetsandcouplednets.Then,itcanautomaticallybuildtheIE3Dmodelforthecriticalnetsincludingthereferencenets.Thecreatedmodelcanbereadyforsimulation.ThereisaseparatedocumentationonAGIF.Inthismenu,wemaygiveasimpleexampleofusingAGIFforautomatedIE3Dsimulation.

Inthelastcoupleyears,wehavealsoimplementedtheEMSockettogetherwithAppliedWaveResearch,Inc.EMSocketbasicallyallowsuserstocreatelayoutsfromMicrowaveOfficeofAWR,performIE3Dfull-waveEMsimulationsseamlessfromMWO.TheadvantagesofIE3DandMWOarecombinedtogethertomakeitconvenientfordesigners.EMSocketisavailableautomaticallytoIE3DandMWOusersfreeofcharge.

Inthenextsection,wewillshowtheimportingofaGDSIIfile.WewilluseasimpleMIMcapacitorasanexample.TheprocedureforimportingaDXFfileissimilarexceptyoumayneedtoscaletheimportedstructureafterimportingbecauseaDXFfilemaynotcarryabsolutedimensionalinformation.

Section2.ImportinganMIMCapacitorinGDSIIFormat.

TheshapeoftheMIMcapacitorisshowninFigure6.1.Thebottomplateisona100-micronGaAssubstrate.Thedielectricbetweenthetwoplatesisofthickness0.2micronsanddielectricconstant6.7.Thedimensionsofthetopplateare100micronsby100microns.Theairbridgeisat102-micronlevel.TheGDSIIfileisin.\ie3d\samples\mimcap.gds.

Step1RunMGRID.SelectFile->Importcommand.MGRIDwillpromptyoutheImportOptionsdialog.SelectGDSIIforImportFormat.ManyoftheoptionsaregrayedoutbecausetheyarefortheDXFconversion.

ForDXFimport,youmayhavetoselectLengthUnit.YoualsoneedtodefineCircularMinRadius（Rmin）andtheSegment（Smin）,CircularMaxRadius（Rmax）andtheSegment（Smax）.TheparametersareforconvertingcircularstructurestopolygonswhicharetheonlyobjectsacceptedbyIE3D.WhenweencounteracircularshapewithradiusR,wewillconvertitintoapolygonwithS-numberofsegment.TheSiscalculatedbasedupontheformulasinTable6.1.ItisbasicallyalinearinterpolationbaseduponR,Rmin,Rmax,SminandSmax.WeshouldchoosetheRmin,Rmax,SminandSmaxvalueswisely.Forsomeapplications,thecircularshapescanbeelectricallylarge,weshouldchooseSminandSmaxas12,16,24,36oreven64.Forsomeapplications,thecircularshapesarenormallyforviasandtheyareelectricallyverysmall.WecanchooseSminandSmaxas4,6or8.Normally,6isagoodnumber.ChoosingtoobiganumberwillcauseIE3Dcreatetoomanyunknownsandthesimulationtimewillincreasesubstantiallywhiletheaccuracyisnotimproved.

（a）Originalstructurewithtwoplates（b）Z-directionmagnifiedbyafactorof30

Figure6.1TheshapeoftheMIMcapacitortobebuiltfromimporting.

Table6.1TheformulaforSegments（S）baseduponRadius（R）.

RRange

SFormula

R

S=Smin

Rmin

S=Smin+（Smax–Smin）（R–Rmin）/（Rmax–Rmin）

R>Rmax

S=Smax

Step2ForGDSIIstructure,circularshapesarealreadyconvertedintopolygonshapes.Wedonotneedtoworryaboutit.PleaseselectOKtocontinue.MGRIDwillpromptyoufortheGDSIIfile.Selectfile.\ie3d\samples\mimcap.gds.SelectOKcontinue.MGRIDwillimportthestructurefromthefile.ItcomesupwiththeImportDataOptionsdialog（seeFigure6.2）.Itwilllistallthestructuresdetectedinthefile.

TheremightbemultiplestructuresinaGDSIIfile.Youcanselectwhichstructureyouwanttoimport.ForthisparticularGDSIIfile,thereisonlyonestructure:

mimcapanditischecked.Allthelayersdetectedinthestructureareshowninthelistboxattheright.Therearemanyparametersyouneedtoenter.

ThefirstgroupofparametersyouneedtoentertheBasicParametersforthestructure.Theycontainthesubstratesandthemetallicstriptypesandthemeshingparametersetc.Thesecondgroupofparametersyouneedtoenterarethelayerinformation.AGDSIIfilecontainsonlythelayerinformationandthe（X,Y）coordinates.ItdoesnotcontaintheZ-coordinates.WeneedtomapthelayerstoZ-coordinates.ItisalsopossibleaGDSIIfileusepolygonstodefinetheshapesofvias.However,theydonotcontainthethirddimensionalinformationabouthowtheviasareconnectingthelayers.

Figure6.2TheImportDataOptionsdialogbeforethetemplatefile.\ie3d\samples\mimcap.ctpisloaded.

WeneedtodefinealltheabovedataintheBasicParametersdialogfromthebutton,thelayerinformationdialogattherightandtheAutomaticVialistboxatthelowerrightcornerofFigure6.2.Certainly,wecandefinesometemporarydatafirst.AfterweimportthegeometryintoMGRID,wecanchangethelayerz-coordinates,redefinetheBasicParameters,andbuildtheviasusingthepolygonshapesusingtheAdvEdit->BuildHolesandViasfromSelectedPolygonscommand.Itcanbeatediousprocess.Fortunately,wehaveimplementedtheImportTemplateFile（.ctp）toeasetheprocess.

Step3WehavealreadycreatedtheImportTemplateFile:

.\ie3d\samples\mimcap.ctpfileforyou.PleaseselectLoadbutton.Selectthe.\ie3d\samples\mimcap.ctpfile.MGRIDwillloadthe.ctpfileandusetheinformationinthe.ctpfiletodefinetheBasicParametersandtheLayerInformationdialog（seeFigure6.3）.Allthelayersareplacedatthesupposedz-coordinatestheyshouldbeon.TheBasicParametersarealsodefined.IfyouchoosetheBasicParametersbutton,itwillshowyoutheGaAssubstrateconfiguration.

Incaseyouhavetomanuallyentertheimportoptionparameters,afteryoudefineallthedata,youcanselecttheSavebuttontosavethedefineddataintoanImportTemplateFile（.ctp）.Youcanusethe.ctpfileforfutureimportingofsimilarstructureswithoutgoingthroughthesameprocedure.Infact,wearedoingsousingthemimcap.ctpfileherenow.

Figure6.3TheimportDataOptionsdialogafterthetemplatefileisloaded.

Step4Pleaseun-checktheMergePolygonsoption.Ifyoucheckit,itwilltrytomergetheimportedpolygonsiftheyareconnected.Forthiscase,wewouldlikenottodoso.SelectOKtocontinue.MGRIDwillimportthestructurewithalltheBasicParam