ASTM_F_1239_-_94.pdf

Designation:F 1239 94Standard Test Methods forOxygen Precipitation Characterization of Silicon Wafers byMeasurement of Interstitial Oxygen Reduction1This standard is issued under the fixed designation F 1239;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 These test methods cover complementary procedures fortesting the oxygen precipitation characteristics of silicon wa-fers.It is assumed that the precipitation characteristics arerelated to the amount of interstitial oxygen lost during specifiedthermal cycles.1.2 These test methods may be used to compare qualita-tively the precipitation characteristics of two or more groups ofwafers.1.3 These test methods may be applied to any n-or p-type,any orientation Czochralski silicon wafers whose thickness,resistivity,and surface finish are such as to permit the oxygenconcentration to be determined by infrared absorption andwhose oxygen concentration is such as to produce measurableoxygen loss.1.4 These test methods are not suitable for determining thewidth or characteristics of a“denuded zone,a region near thesurface of a wafer that is essentially free of oxide precipitates.1.5 Because these test methods are destructive,suitablesampling techniques must be employed.1.6 The values stated in SI units are regarded as standard.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.Specific hazardstatements are given in Section 8.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification For Reagent Water2F 416 Test Method for Detection of Oxidation InducedDefects in Polished Silicon Wafers3F 612 Practice for Cleaning Surfaces of Polished SiliconSlices4F 951 Test Method for Determination of Radial InterstitialOxygen Variation3F 1188 Test Method for Interstitial Atomic Oxygen Contentof Silicon by Infrared Absorption32.2SEMI Standards:C 1 Specifications for Reagents5C 3 Specifications for Gases52.3Other Standard:DIN 50 438,Part 1 Testing of Materials for SemiconductorTechnology Determination of Impurity Content in Semi-conductors by Infrared Absorption Oxygen in Silicon33.Summary of Test Method3.1 A representative sample is selected from each group ofwafers to be tested.3.2 The initial value of interstitial oxygen concentration ismeasured by the infrared absorption method at the desiredpoints on each wafer.3.3 The wafers are passed through one of two simulationthermal cycles.Cycle A consists solely of a precipitation step.Cycle B consists of a nucleation step followed by a precipita-tion step.3.4 After the thermal cycle,the oxide film is stripped andthe final value of oxygen concentration is measured at the samepoints on each wafer using the same technique and instrumen-tation as was used to determine the initial value.3.5 The oxygen reduction is determined for each wafer(orfor each point on each wafer)tested as the difference betweenthe initial and final values.3.6 If all samples have the same initial oxygen concentra-tion(within a narrow range),the average oxygen reduction foreach test condition(such as,group or position on wafer)iscomputed,and the appropriate comparisons made.3.7 If the samples have initial oxygen concentrations thatcover a relatively wide range,a plot of oxygen reductionagainst initial oxygen concentration is made for each group orposition.Again appropriate comparisons can be made.4.Significance and Use4.1 Oxide precipitates in the bulk of a silicon substratewafer can act as gettering sites for contamination that may be1These test methods are under the jurisdiction of ASTM Committee F-01 onElectronics and are the direct responsibility of Subcommittee F01.06 on SiliconMaterials and Process Control.Current edition approved Aug.15,1994.Published October 1994.Originallypublished as F 1239 89.Last previous edition F 1239 89.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 10.05.4Discontinued;see 1992 Annual Book of ASTM Standards,Vol 10.05.5Available from Semiconductor Equipment and Materials International,805 E.Middlefield Rd.,Mountain View,CA 94043.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMintroduced during manufacture of circuits and devices.Thiscontamination(usually metallic impurities)if not gettered,canreduce device manufacturing yields and degrade device orcircuit performance.Thus,the oxygen precipitation character-istics of the substrate wafer can significantly affect both yieldsand performance.4.2 Although interstitial oxygen concentratio