ASTM_F_672_-_88_1995e1.pdf

Designation:F 672 88(Reapproved 1995)e1Standard Test Method forMeasuring Resistivity Profiles Perpendicular to the Surfaceof a Silicon Wafer Using a Spreading Resistance Probe1This standard is issued under the fixed designation F 672;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.e1NOTEKeywords were added editorially in January 1995.INTRODUCTIONThe measurement of resistivity profile by means of a spreading resistance probe is a complexprocedure,with a number of commonly accepted options for carrying out the component measure-ments.ASTM Committee F-1 on Electronics has designed this test method to allow a range of choices,consistent with good practice,for the electronic configuration,type of specimen preparation,andmethod for measuring bevel angle.Items not specified by this test method are to be agreed upon bythe parties to the test,usually from a specified set of choices in the context of a general restriction.Themeasurement of bevel angle is particularly difficult to specify,as the selection of an appropriatemethod depends not only on the range of angle measured but also on the quality of the instrumentationavailable for that method.Although ideally the beveled surface and the original surface should be twoplanes intersecting along a straight line,the actual geometry may differ from this ideal,furthercomplicating the measurement.These points are recognized in the section on interferences and inAppendix X1 and associated references on the bevel-angle measurement.1.Scope1.1 This test method covers measurement of the resistivityprofile perpendicular to the surface of a silicon wafer of knownorientation and type.NOTE1This test method may also be applicable to other semicon-ductor materials,but feasibility and precision have been evaluated only forsilicon and germanium.1.2 This test method may be used on epitaxial films,substrates,diffused layers,or ion-implanted layers,or anycombination of these.1.3 This test method is comparative in that the resistivityprofile of an unknown specimen is determined by comparingits measured spreading resistance value with those of calibra-tion standards of known resistivity.These calibration standardsmust have the same surface preparation,conductivity type,andcrystallographic orientation as the unknown specimen.1.4 This test method is intended for use on silicon wafers inany resistivity range for which there exist suitable standards.Polished,lapped,or ground surfaces may be used.1.5 This test method is destructive in that the specimen mustbe beveled.1.6 Correction factors,which take into account the effects ofboundaries or local resistivity variations with depth,are neededprior to using calibration data to calculate resistivity from thespreading resistance values.NOTE2This test method extends Method F 525 to depth profiling.NOTE3This test method provides means for directly determining theresistivity profile of a silicon specimen normal to the specimen surface.Unlike Method F 84 and Test Methods F 374 and F 419,it can providelateral spatial resolution of resistivity on the order of a few micrometres,and an in-depth spatial resolution on the order of 10 nm(100 A).This testmethod can be used to profile through p-n junctions.1.7 This test method is primarily a measurement for deter-mining the resistivity profile in a silicon wafer.However,common practice is to convert the resistivity profile informa-tion to a density profile.For such purposes,a conversionbetween resistivity and majority carrier density is provided inAppendix X2.1.8 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.Specific hazardstatements are given in Section 9.2.Referenced Documents2.1 ASTM Standards:1This test method is under the jurisdiction of ASTM Committee F-1 onElectronicsand is the direct responsibility of Subcommittee F01.06 on SiliconMaterial and Process Control.Current edition approved Oct.31,1988.Published December 1988.Originallypublished as F672 80.Last previous edition F672 87.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMD 1125 Test Methods for Electrical Conductivity and Re-sistivity of Water2E 1 Specification for ASTM Thermometers3F 26 Test Methods for Determining the Orientation of aSemiconductive Single Crystal4F 42 Test Method for Conductivity Type of Extrinsic Semi-conducting Materials4F 84 Test Method for Measuring Resistivity of SiliconSlices with an In-Line Four-Point Probe4F 374 Test Method for Sheet Resistance of Sili