Brooks Marathon Express - Fine-Tuning the Station Assignment

8. System Alignment Marathon Express
Fine-Tuning the Station Assignment Part Number: 605914 Rev. B
Fine-Tuning the Station Assignment
Formaterialtransportsystemsthathaveanaligner,thealigneristypicallyconsideredthe“centerof
theuniverse”fordefininglocationswithinthesystem.Thealigner’sabilitytopreciselymeasurethe
offsetofawaferfromitscenterofrotationalongwiththerobot’sabilitytocompensateforthisoffset
byexecutingadeltapickprovidesaverypowerfultoolforbothtransportingwafersandperforming
systemalignmentproceduresandchecks.
Using the Aligner as a True Position Reference
Thefollowingexampleshowshowthewaferalignmentphaseworksusingthesystemaligner.
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TheinitialstationassignmentforaProcessModuleisprogrammedintotherobot.Thisassignmentisa
“crude”assignmentasitonlyensuresthattherobotwillbeabletopickandplacewaferswithoutany
interferenceormechanicalcontact.
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AwaferisthenphysicallyplacedintheProcessModulesuchthatitisoptimallylocated.
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TherobotistheninstructedtopickthewaferfromtheProcessModuleandplaceitintothealigner.
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Thealignerdeterminesthewafer’soffsetfromtrueposition.
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TheoffsetisthenusedtorecalculateandupdatetheProcessModule’sstationassignmentstoredinthe
robot.
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ThenewlycalculatedandstoredstationassignmentfortheProcessModulewillallowthetransferof
wafersfromthealignertotheProcessModulewithessentiallyzeroerror.
Afterverifyingallvalues,testthepick/placeerrorbetweenthetwoarmsbyusingthefollowing
procedure.
NOTE: Becarefulwhenverifyingcalculatedaxesparametersforarm’B’asthese
variationscouldcausethearmorendeffectortomakephysicalcontactwithpartsof
thesystemthatarm’A’willnottouch.
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Step Action
1.
Pickawaferfromacassettewithpan’A’andplaceitonthealigner.
2.
Alignthewafer.
3.
Pickthewaferwithpan’A’andplaceitbackintothecassette.
4.
Pickthesamewaferwithpan’B’andplaceitonthealigner.
5.
Alignthewafer.Thewafershouldbe<0.014offcenter.
6.
Pickthewaferwithpan’B’andplaceitbackintothecassette.
7.
Repeatthealignmentprocedureforpan‘B’untiltheerroriswithinlimits.
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