ASTM_F_374_-_00a.pdf

Designation:F 374 00aStandard Test Method forSheet Resistance of Silicon Epitaxial,Diffused,Polysilicon,and Ion-implanted Layers Using an In-Line Four-Point Probewith the Single-Configuration Procedure1This standard is issued under the fixed designation F 374;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.1.Scope1.1 This test method covers the direct measurement of theaverage sheet resistance of thin layers of silicon with diametersgreater than 15.9 mm(0.625 in.)which are formed by epitaxy,diffusion,or implantation onto or below the surface of acircular silicon wafer having the opposite conductivity typefrom the thin layer to be measured or by the deposition ofpolysilicon over an insulating layer.Measurements are made atthe center of the wafer using a single-configuration of thefour-probe,that is,with the current being passed through theouter pins and the resulting potential difference being measuredwith the inner pins.1.2 This test method is known to be applicable on filmshaving thickness at least 0.2 m.It can be used to measuresheet resistance in the range 10 to 5000 V,inclusive.1.2.1 The principle of the test method can be extended tocover lower or higher values of sheet resistance;however,theprecision of the method has not been evaluated for sheetresistance ranges other than those given in 1.2.NOTE1The minimum value of the diameter is related to tolerances onthe accuracy of the measurement through the geometric correction factor.The minimum layer thickness is related to danger of penetration of theprobe tips through the layer during measurement.1.3 Procedures for preparing the specimen,for measuringits size,and for determining the temperature of the specimenduring the measurement are also given.Abbreviated tables ofcorrection factors appropriate to circular geometry are includedwith the method so that appropriate calculations can be madeconveniently.NOTE2The principles of this test method are also applicable to othersemiconductor materials,but neither the appropriate conditions nor theexpected precision have been determined.Other geometries can also bemeasured,but only comparative measurements using similar geometricalconditions should be used unless proper geometrical correction factors areknown.NOTE3Some relaxations of test conditions are mentioned in order toassist in applying the principles of the method to nonreferee applications,for which a complete nonreferee method has not yet been developed.Therelaxed test conditions given are consensus conditions only and their effecton measurement precision and accuracy has not been explored.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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.Specific hazardstatements are given in Section 9.2.Referenced Documents2.1 ASTM Standards:D 5127 Guide for Ultra Pure Water Used in the Elecrronicsand Semiconductor Industry2E 1 Specification for ASTM Thermometers3F 42 Test Method for Conductivity Type of Extrinsic Semi-conducting Materials4F 1529 Test Method for Sheet Resistance UniformityEvaluation by In-Line Four-Point Probe with the Duel-Configuration Procedure42.2SEMI Standard:C 3.15 Specifications for Nitrogen Gas5C 28 Specification for Hydrofluoric Acid5C 31 Specification for Methanol53.Terminology3.1 Definitions:3.1.1 four-point probean electrical probe arrangement fordetermining the resistivity of a material in which separate pairsof contacts are used(1)for passing current through thespecimen and(2)measuring the potential drop caused by thecurrent.3.1.1.1 DiscussionIt may consist of a unitized probe headholding all four probes or it may have each of the fourindividual probes attached to a separate cantilevered arm.1This test method is under the jurisdiction of ASTM Committee F01 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 374 74 T.Last previous edition F 374 00.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 14.03.4Annual Book of ASTM Standards,Vol 10.05.5Available from the Semiconductor Equipment and Materials Institute,625 EllisSt.,Suite 212,Mountain View,CA 94043.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.3.1.2 probe head,of a four-point probethe mounting that(1)fixes the position of the four-point probe in a specificpattern such as an in-line(collinear