ASTM_F_398_-_92_1997.pdf

Designation:F 398 92(Reapproved 1997)Standard Test Method forMajority Carrier Concentration in Semiconductors byMeasurement of Wavenumber or Wavelength of the PlasmaResonance Minimum1This standard is issued under the fixed designation F 398;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.INTRODUCTIONAs originally published,this test method was written for infrared instruments with output in unitsof wavelength.Calibration data,as included,were based on infrared measurements in units ofwavelength and on a combination of concentration scale methods including Hall effect,neutronactivation analysis,and four-probe resistivity.These latter measurements were converted,using theempirical data of Irvin,from resistivity to“impurity concentration.”The result of this procedure iscalibration data that is a mixture of carrier concentration and impurity concentration values.While thedifferences between them is large only at very high concentrations,there are values in the originalcalibration plots for silicon(Fig.A1.1 and Fig.A1.2)that are above currently accepted solid-solubilitylimit values.Common practice current infrared spectrophotometers is to give output in units of wavenumbers(cm1).In order to relate this test method and its original calibration to current infrared units withoutintroducing numerical error(the calibration relation is not analytically invertible to wavenumbers),thedirect substitution of 10 000/wavenumber for wavelength is given in the analysis equation and in thetables of coefficients.This test method is not believed to have wide current use in the semiconductor industry.However,because this test method may be useful for some applications and because the calibration datacontained herein is believed to be available nowhere else in the archival literature,this test method isbeing retained as a standard.1.Scope1.1 This test method covers determination of the wavenum-ber of the plasma resonance minimum in the infrared reflec-tance of a doped semiconductor specimen,from which themajority carrier concentration can be obtained.1.2 This test method of determination of the wavenumberminimum is nondestructive and contactless.It is applicable ton-and p-type silicon,n-and p-type gallium arsenide,andn-type germanium.1.3 This test method gives a relative measurement in thatthe relation between the wavenumber of the plasma resonanceminimum and the majority carrier concentration is empirical.Such relations have been established for the several casessummarized in Annex A1.These relations are based upondeterminations of the plasma resonance minimum by theprocedure of this method and determinations of the Hallcoefficient according to Test Methods F 76(Section 2)orresistivity according to Test Methods F 43 or Test Method F 84(Section 2)as appropriate.1.4 These relations have been established over a majoritycarrier concentration range from 1.5 3 1018to 1.5 3 1021cm3for n-type silicon,from 3 3 1018to 5 3 1020for p-typesilicon,from 3 3 1018to 7 3 1019for n-type germanium,from1.5 3 1017to 1 3 1019for n-type gallium arsenide,and from2.6 3 1018to 1.3 3 1020cm3for p-type gallium arsenide.1.5 These relations can be extended or developed for othermaterials by measuring the wavelength of the plasma reso-nance minimum according to this procedure on specimenswhose majority carrier concentration has been determined byother means.1.6 This test method is applicable to both bulk and diffusedmaterial.However,since there is some controversy over theeffects of variations of junction depth on the measurement,itshould be applied to surface concentration measurements onshallow(1 m or less)diffusions only on a relative basis unless1This 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 May 15,1992.Published July 1992.Originallypublished as F 398 74 T.Last previous edition F 398 87e1.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.there is experimental corroboration of the results under theconditions of interest.1.7 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:E 275 Practice for Describing and Measuring Performanceof Ultraviolet,Visible,and Near Infrared Spectrophotom-eters2F 42 Test Methods for Conductivity Type of ExtrinsicSemiconducting Materials3F 43 Test Methods for Resistivity of Semiconductor Mate-rials3F 76 Test Methods fo