Designation:F1724–96StandardTestMethodforMeasuringSurfaceMetalContaminationofPolycrystallineSiliconbyAcidExtraction-AtomicAbsorptionSpectroscopy1ThisstandardisissuedunderthefixeddesignationF1724;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthequantitativedeterminationofsurfacetracemetalcontaminationonthesurfaceofpoly-crystallinesiliconusinganacidtoextractthemetalsfromthesurface.Themetalscontentoftheacidisthenanalyzedbygraphitefurnaceatomic-absorptionspectroscopy.1.2Thistestmethodcanbeusedforvariousrod,chunk,granuleandchipsizes,forpolycrystallineorsinglecrystalsilicon,todeterminesurfacemetalcontaminants.Sincetheareaofirregularly-shapedchunks,chips,orgranulesisdifficulttomeasureaccurately,valuesarebasedonsampleweight.Usingasampleweightof300gallowsdetectionlimitsatthe0.1ppbw(partsperbillionweight)level.1.3Thestrength,composition,temperature,andexposuretimeoftheaciddeterminethedepthofsurfaceetchingandtheefficiencyoftheextractionofthecontaminantsfromthesurface.Lessthan1%ofthesampleweightisremovedinthistestmethod.1.4Thistestmethodisusefulfordeterminingthealkalielements,alkaliearth,andfirstseriestransitionelements,suchassodium,potassium,calcium,iron,chromium,nickel,copper,zinc,aswellasotherelementssuchasaluminum.Therecoveryoftheseelementsfromthesiliconsurfaceismeasuredasgreaterthan90%,usingcontrolstandardsintentionallyaddedtothepolysiliconsurface.1.5Thistestmethodsuggestsaparticularsamplesize,acidcomposition,etchcycle,testingenvironment,andinstrumentprotocol.Variationsintheseparametersmaybeused,butmayeffecttherecoveryefficiencyorretentionofmetalsduringprocessing.Inpractice,thistestmethodisusedforsampleweightsof25to5000g.Forrefereepurposes,thistestmethodspecifiesasampleweightof300g.Thistestmethodincludesguidelinestoalerttheanalysttot...
