ASTM_F_1726_-_97.pdf

Designation:F 1726 97Standard Guide forAnalysis of Crystallographic Perfection of Silicon Wafers1This standard is issued under the fixed designation F 1726;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 guide covers the determination of the density ofcrystallographic defects in unpatterned polished and epitaxialsilicon wafers.Epitaxial silicon wafers may exhibit disloca-tions,hillocks,shallow pits or epitaxial stacking faults,whilepolished wafers may exhibit several forms of crystallographicdefects or surface damage.Use of this practice is based uponthe application of several referenced standards in a prescribedsequence to reveal and count microscopic defects or structures.1.2 Materials for which this practice is applicable may bedefined by the limitations of the referenced documents.1.2.1 This practice is suitable for use with epitaxial orpolished wafers grown in either 111 or 100 direction anddoped either p or n-type with resistivity greater than 0.005V-cm.1.2.2 This practice is suitable for use with epitaxial waferswith layer thickness greater than 0.5 m.1.3 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:D 5127 Guide for Electronic Grade Water2F 95 Test Method for Thickness of Lightly Doped SiliconEpitaxial Layers on Heavily Doped Silicon SubstratesUsing an Infrared Dispersive Spectrophotometer3F 523 Practice for Unaided Visual Inspection of PolishedSilicon Wafers Surfaces3F 1241 Terminology of Silicon Technology3F 1809 Guide for Selection and Use of Etching Solutions toDelineate Structural Defects in Silicon3F 1810 Test Method for Counting Preferentially Etched orDecorated Surface Defects in Silicon Wafers32.2SEMI Specifications:SEMI C-1 Specification for Reagents43.Terminology3.1 Defect-related terminology may be found in Terminol-ogy F 1241.4.Summary of Guide4.1 Clean,unprocessed polished or epitaxial wafers areselected.The wafers are examined under bright light illumina-tion to ensure the sample is free from contamination andobvious surface damage.Epitaxial wafers may also be micro-scopically inspected before etching to count and classifyvisible imperfections.Wafers are then etched in a preferentialdefect etchant solution.The etched surface is again examinedunder bright light illumination to identify patterns that may berelated to contamination or improper handling.The imperfec-tions highlighted by the preferential etchant are then micro-scopically counted and classified.5.Significance and Use5.1 The use of silicon crystals in many semiconductordevices requires a consistent atomic lattice structure.Crystaldefects disturb local lattice energy conditions that are the basisfor semiconductor behavior.These defects have distinct effectson essential semiconductor-device manufacturing processessuch as alloying and diffusion.5.2 Epitaxial growth processes are used extensively in themanufacture of silicon electronic devices.Stacking faultsintroduced during epitaxial growth can cause“soft”electricalcharacteristics and preferential micro plasma breakdowns indiodes.5.3 Epitaxial defects are more clearly delineated with theuse of this destructive etching procedure.Epitaxial wafers mayhowever be classified nondestructively by this method withoutthe destructive preferential etching and inspection steps.5.4 This guide along with the referenced standards may beused for process control,research and development,andmaterial acceptance purposes.6.Apparatus6.1 Safety Equipment and Facility,for defect etching aredescribed in Guide F 1809.1This guide is under the jurisdiction ofASTM Committee F-1 on Electronics andis the direct responsibility of Subcommittee F01.06 on Silicon Materials and ProcessControl.Current edition approved June 10,1997.Published August,1997.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 10.05.4Available from Semiconductor Equipment and Materials International,805 EMiddlefield 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 ASTM6.2 Wafer Inspection Facilities and Handling Equipment,shall be consistent with industry practice and suitable for usewith Practice F 523.7.Reagents and Materials7.1 All chemicals for which such specifications exist shallconform to SEMI Specifications C-1.7.2 Reference to water shall be understood to mean eitherdistilled water or deionized water,meeting the requirements ofType I water as defined by Gu