ASTM_F_1723_-_96.pdf

Designation:F 1723 96Standard Practice forEvaluation of Polycrystalline Silicon Rods by Float-ZoneCrystal Growth and Spectroscopy1This standard is issued under the fixed designation F 1723;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis practice replaces Method F 574,and Practice F 41.Method F 574 and Practice F 41 areobsolete,describing multi-pass zoning and vacuum zoning practices,and resistivity measurements forthe calculation of impurity concentrations.One pass zoning and analysis by spectrophotometrictechniques to identify and quantify the acceptor and donor elements have replaced the obsoletemethods.Expanded sampling plans,the use of reference specimens,and practices for sampling ofingots are improvements made to these standards.1.Scope1.1 This practice recommends procedures for samplingpolycrystalline silicon rods and growing single crystals fromthese samples by the float-zone technique.The resultant singlecrystal ingots are analyzed by spectrophotometric methods todetermine the trace impurities in polysilicon.These traceimpurities are acceptor(usually boron or aluminum,or both),donor(usually phosphorus or arsenic,or both),and carbonimpurities.1.2 The useful range of impurity concentration covered bythis practice is 0.002 to 100 parts/billion atomic(ppba)foracceptor and donor impurities,and 0.05 to 5 parts/millionatomic(ppma)for carbon impurity.These impurities areanalyzed in the ingot samples by infrared or photolumines-cence spectroscopy.1.3 This practice is applicable only to evaluation of poly-silicon ingots grown by a method that utilizes a slim silicon rod(filament)upon which polycrystalline silicon is deposited.1.4 This practice uses hot acid to etch away the surface ofthe polysilicon rod.The etchant is potentially harmful and mustbe handled in an acid exhaust fume hood with utmost care at alltimes.Hydrofluoric acid solutions particularly are hazardousand should not be used by anyone who is not familiar with thespecific preventative measures and first aid treatments given inthe appropriate Material Safety Data Sheet.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 5127 Guide for Electronic Grade Water2F 26 Test Methods for Determining the Orientation of aSemiconductive Single Crystal3F 47 Test Method for Crystallographic Perfection of Siliconby Preferential Etch Techniques3F 397 Test Method for Resistivity of Silicon Bars Using aTwo-Point Probe3F 723 Practice for Conversion Between Resistivity andDopant Density for Boron-Doped and Phosphorus-DopedSilicon3F 1241 Terminology of Silicon Technology3F 1389 Test Method for Photoluminescence Analysis ofSingle Crystal Silicon for III-V Impurities3F 1391 Test Method for Substitutional Carbon Content ofSilicon by Infrared Absorption3F 1630 Test Method for Low Temperature FT-IR Analysisof Single Crystal Silicon for III-V Impurities32.2Federal Standards:Federal Standard 209EAirborne Particulate CleanlinessClasses in Cleanrooms and Clean Zones42.3SEMI Standards:C 3 Specification for Gases5C 7 Specification for Reagents53.Terminology3.1 Definitions:Terms used in this practice are defined inTerminology F 1241 or below.1This practice is under the jurisdiction of ASTM Committee F-1 on Electron-icsand is the direct responsibility of Subcommittee F01.06 on Silicon Materials andProcess Control.Current edition approved July 10,1996.Published September 1996.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 10.05.4Available from Superintendent of Documents,U.S.Government PrintingOffice,Washington,DC 20402.5Book of SEMI Standards,available from Semiconductor Equipment andMaterials International,805 E.Middlefield Road,Mountain View,CA 94043.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTM3.2 Definitions of Terms Specific to This Standard:3.2.1 control rod,na cylinder of polysilicon taken from apolysilicon rod with a uniform deposition layer,having knownamounts of boron,phosphorus,and carbon from repeatedanalysis.3.2.2 core,na cylinder of polysilicon obtained from alarger piece of polysilicon by drilling with a hollow diamonddrill.3.2.3 deposition layer(growth layer),nthe layer of poly-silicon surrounding the filament,extending to the outer diam-eter of the poly rod.3.2.4filament,slim rod,na small diameter silicon rod,assembled into a U-shape,used to provide a substrate or seedfor the deposition of polycrystallin