ASTM_F_533_-_02.pdf

Designation:F 533 02Standard Test Method forThickness and Thickness Variation of Silicon Wafers1This standard is issued under the fixed designation F 533;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.INTRODUCTIONWhen this test method was developed in the 1970s,non-contact thickness gages employing manualwafer positioning,which are the basis of this test method,were in routine use.More recently,faster,automated instruments have replaced these manual gages for most common uses in the semiconductorindustry.In these automatic systems,microprocessors or microcomputers are used to control waferpositioning,operate the instrument and to analyze the data.See Test Method F 1530.Despite the fact that this test method is not commonly used in its present form,it embodies all thebasic elements of this test method and a simple analysis of data.Thus,it provides useful guidance inthe fundamentals and appplication of differential non-contact wafer thickness measurements.1.Scope1.1 This test method2covers measurement of the thicknessof silicon wafers,polished or unpolished,and estimation of thevariation in thickness across the wafer.1.2 This test method is intended primarily for use withwafers that meet the dimension and tolerance requirements ofSEMI Specifications M 1.However,it can be applied tocircular silicon,wafers or substrates of any diameter andthickness that can be handled without breaking.1.3 This test method is suitable for both contact andcontactless gaging equipment.Precision statements have beenestablished for each.1.4 The values stated in inch-pound units are to be regardedas standard.The values in parentheses are for information only.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:F 1530 Test Method for Measuring Flatness,Thickness andThickness Variation on Silicon Wafers by AutomatedNoncontact Scanning32.2SEMI Standard:Specifications M 1,for Polished Monocrystalline SiliconWafers42.3Federal Standards:Fed.Std.No.209B Clean Room and Work Station Require-ments,Controlled Environment5Fed.Spec.GGG-G-15C Gage Blocks andAccessories(Inchand Metric),Nov.6,197063.Terminology3.1 Definitions:3.1.1 back surfaceof a semiconductor wafer,the exposedsurface opposite to that upon which active semiconductordevices have been or will be fabricated.3.1.2 front surfaceof a semiconductor wafer,the exposedsurface upon which active semiconductor devices have been orwill be fabricated.3.1.3 thicknessof a semiconductor wafer,the distancethrough the wafer between corresponding points on the frontand back surfaces.3.1.4 total thickness variation,TTVof a semiconductorwafer,the difference between the maximum and minimumvalues of the thickness of the wafer.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.06 on Electricaland Optical Measurement.Current edition approved Jan.10,2002.Published March 2002.Originallypublished as F 533 77 T.Last previous edition F 533 96.2DIN 50441/1 is an equivalent method.It is the responsibility of DIN CommitteeNMP 221,with which Committee F01 maintains close liaison.DIN 50441/1.Determinaton of the Geometric Dimensions of Semiconductor Slices;Measurementof Thickness,available from Beuth Verlag,Gmbh,Burggrafenstrasse 4-10,D-1000Berlin 30,Federal Republic of Germany.3Annual Book of ASTM Standards,Vol 10.05.4Available from Semiconductor Equipment and Materials International,805East Middlefield Rd.,Mountain View,CA 94043.5Available from GSA Business Service Centers in Boston,New York,Atlanta,Chicago,Kansas City,Mo.,Fort Worth,Denver,San Francisco,Los Angeles,andSeattle.6Available from the Superintendent of Documents,U.S.Government PrintingOffice,Washington,DC 20402.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.4.Summary of Test Method4.1 The thickness of the wafer is measured at its center andat four other sites whose positions are defined with respect tothe primary flat or other index mark.Two of the sites fall alonga diameter and two along a second diameter,perpendicular tothe first.4.2 The thickness measured at the center of the wafer isgenerally taken as the nominal thickness of the wafer.4.3 The maximum difference between any two of the fivethickness measurements is taken as the total thickness variationof the wafer.5.Significance and Use5.1 Wafer thickness and thickness variations must be con-trolled to suit the requirements of fixtures and equipment u