Drawing Stick Diagrams.docx

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1、DrawingStickDiagrams·MaskLayoutandStickDiagramforaCMOSInverter·TransistorsAtransistorexistswhereapolysiliconstickcrosseseitheranNdiffusionstick(NMOStransistor)oraPdiffusionstick(PMOStransistor).Notethatthereisnodifferenceintheconstructionofatransistor

2、sourceandatransistordrain.Thesourceisdeterminedasthesourceofconductors(electronsforNMOS/holesforPMOS)whencurrentflowsthroughthechannel.Insomepasstransistorcircuits,thesourceanddrainmayswapoverduringuse.·ImpliedConnectionsandCrossoversWheretwosticksoft

3、hesamecolourmeetorcrossthereisalwaysaconnection.Wheretwosticksofdifferentcoloursmeetorcrossthereisnoimpliedconnection.NotethatNandPdiffusionsmaynotcrosseachother.Wherepolycrossesdiffusionwehaveatransistor(seeabove).·ContactsAconnectionmaybeexplicitlyd

4、efinedusingafilledblackcircle.Inthegeneralcaseaconnectionispermittedwherethemasklayerswillbeseparatedbyjustonelayerofinsulator(throughwhicha"contactcut"maybedefined).ThusPdiffusionmayconnecttoMetal1butnotdirectlytoMetal2.Inaprocesswherestackedcontacts

5、arepermitted,wemaydrawacontactbetweennon-adjacentconductors;e.g.betweenPolyandMetal3,inwhichcasetheconnectiontointermediatelayers(Metal1andMetal2)isimplied.·TapsThetaprepresentsaconnectiontosomethingwecan'tsee;eithertheN-Well(notshownonourstickdiagram

6、)orthewafersubstrate.Atapisdefinedusinganunfilledblacksquare.Heretherewillbeonlyoneconductorcrossingthesquare(Metal1powerorgroundrail).AnN-WellTapisinferredwheretheconnectionisfromapowerrailwhileaSubstrateTapisinferredwheretheconnectionisfromagroundra

7、il.·CombinedContacts&TapsWecanoftensavespacebyusingacombinedcontactandtap.HerethetapsharesthesameActiveAreaasthecontact.Acombinedcontactandtapisdefinedusingafilledblacksquareinplaceofthesourcecontact(filledblackcircle).Acombinedcontactandtapcanonlybeu

8、sedwheretheendofadiffusionstickcoincideswithacontacttothepowerorgroundrail.·StickDiagramColourCodePdiffusion:Yellow/BrownMetal1:BlueNdiffusion:GreenMetal2:Magenta/PurplePolysilicon:RedMetal3:Cyan/L.BlueContacts&Taps:Black·Ifyoudeviatefromthese