ASTM_F_81_-_00.pdf

Designation:F 81 00DIN 50435Standard Test Method forMeasuring Radial Resistivity Variation on Silicon Wafers1This standard is issued under the fixed designation F 81;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method2provides procedures for the determi-nation of relative radial variation of resistivity of semiconduc-tor wafers cut from silicon single crystals grown either by theCzochralski or floating-zone technique.1.2 This test method provides procedures for using TestMethod F 84 for the four-point probe measurement of radialresistivity variation.1.3 This test method yields a measure of the variation inresistivity between the center and selected outer regions of thespecimen.The amount of information obtained regarding themagnitude and form of the variation in the intervening regionswhen using the four-point probe array depends on the samplingplan chosen(see 7.2).The interpretation of the variationsmeasured as radial variations may be in error if azimuthalvariations on the wafer or axial variations along the crystallength are not negligible.1.4 This test method can be applied to single crystals ofsilicon in circular wafer form,the thickness of which is lessthan one-half of the average probe spacing,and the diameter ofwhich is at least 15 mm(0.6 in.).Measurements can be madeon any specimen for which reliable resistivity measurementscan be obtained.The resistivity measurement procedure of TestMethod F 84 has been tested on specimens having resistivitiesbetween 0.0008 and 2000 Vcm for p-type silicon and between0.0008 and 6000 Vcm for n-type silicon.Geometrical correc-tion factors required for these measurements are included forthe case of standard wafer diameters,and are available intabulated form for other cases.3NOTE1In the case of wafers whose thickness is greater than theaverage spacing of the measurement probes,no geometrical correctionfactor is available except for measurement at the center of the wafer face.1.5 Several sampling plans are given which specify sets ofmeasurement sites on the wafers being tested.The samplingplans allow differing levels of detail of resistivity variation tobe obtained.One of these sampling plans shall be selected andagreed upon by the parties to the measurement.The basicresistivity measurements of Test Method F 84 are then appliedat each site specified in the chosen sampling plan.1.6 Results are expressed as relative changes in resistivitybetween the several measurement sites.To obtain absolutevalues of resistivity it is necessary to measure and correct forspecimen temperature(see 11.1.4).1.7 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.8 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:F 84 Test Methods for Measuring Resistivity of SiliconWafers with an In-Line Four-Point Probe42.2SEMI Standard:Specifications M 1,S for Polished Monocrystalline SiliconWafers53.Summary of Test Method3.1 Resistivity measurements are made at specified sitesalong one or two diameters of a semiconductor specimen inaccordance with a sampling plan selected from the four given.Choice among the sampling plans is made on the basis of theextent of information required regarding possible resistivityvariations.The measured resistivity values are corrected forspecimen geometry and,if desired,for temperature,andsuitable differences are taken to obtain the resistivity variation.4.Significance and Use4.1 The radial resistivity variation of bulk semiconductormaterial is an important materials acceptance requirement for1This test method is under the jurisdiction of ASTM Committee F1 onElectronics,and is the direct responsibility of Subcommittee F01.06 on SiliconMaterials and Process Control.Current edition approved Dec.10,2000.Published February 2001.Originallypublished as F 81 67 T.Last previous edition F 81 95.2DIN 50435 is an equivalent method.It is the responsibility of DIN CommitteeNMP 221,with which Committee F-1 maintains close liaison.DIN 50435,Determination of the Radial Resistivity Variation of Silicon or Germanium Slices byMeans of a Four-Point DC-Probe,is available from Beuth Verlag GmbH,Burg-grafenstrasse 4-10,D-1000 Berlin 30,3Swartzendruber,L.J.,“Correction Factor Tables for Four-Point Probe Resis-tivity Measurements on Thin Circular Semiconductor Samples,”Technical Note199,NBTNA,National Bureau of Standards,April 15,1964.Available as AD 683408 from National Technical Information Service,Sp