- SEMI MF1809 - Guide for Selection and Use of Etching Solutions to Delineate Structural Defects in Silicon
This Standard was technically approved by the Silicon Wafer Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on August 31, 2015. Available at www.semiviews.org and www.semi.org in November 2015; originally published by ASTM International as ASTM F1809-97; previously published November 2010.
NOTICE: This Document was reapproved with minor editorial changes.
Structural defects formed in the bulk of a silicon wafer during its growth or induced by electronic device processing can affect the performance of the circuitry fabricated on that wafer. These defects take the form of dislocations, slip, stacking faults, shallow pits, or precipitates.
The exposure of the various defects found on or in a silicon wafer is often the first critical step in evaluating wafer quality or initiating failure analysis of an errant device structure. Etching often accomplishes this task. This Guide provides information on the selection and application of appropriate etching solutions.
This Guide covers the formulation, selection, and use of chemical solutions developed to reveal structural defects in silicon wafers.
Sample preparation, temperature control, etching technique, and choice of etchant are all key factors in the successful use of an etching method. This Guide provides information for several etching solutions and provides guidance for the user to select according to the need. Illustrations of results obtained with these etching solutions are provided in Figures 1 through 32.
This Guide is intended for use with other practices and test methods. SEMI MF1725 and SEMI MF1726 are practices for analysis of crystallographic perfection of silicon ingots and wafers, respectively, utilizing etching solutions found in this Guide, and followed by counting in accordance with the Test Method SEMI MF1810. SEMI MF1727 defines the procedures for oxidation of the wafer prior to etching, if that is required to expose the defect structures of interest. JIS H 0609 is a test method that covers the entire process of determining crystalline defects in silicon wafers.
Both this Guide and JIS H 0609 emphasize the use of etching solutions that do not contain chromic acid, which is biologically and ecologically very hazardous (see ¶ 7.6). Because of the hazardous nature of chrome containing etchants, the use of chromic acid containing etchants is prohibited in some jurisdictions located in various parts of the world.
Referenced SEMI Standards
SEMI C18 — Specification for Acetic Acid
SEMI C28 — Specifications for Hydrofluoric Acid
SEMI C35 — Specifications and Guideline for Nitric Acid
SEMI M59 — Terminology for Silicon Technology
SEMI MF523 — Practice for Unaided Visual Inspection of Polished Silicon Wafer Surfaces
SEMI MF1725 — Practice for Analysis of Crystallographic Perfection of Silicon Ingots
SEMI MF1726 — Practice for Analysis of Crystallographic Perfection of Silicon Wafers
SEMI MF1727 — Practice for Detection of Oxidation Induced Defects in Polished Silicon Wafers
SEMI MF1810 — Test Method for Counting Preferentially Etched or Decorated Surface Defects in Silicon Wafers