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Chemical Bevelling For Determining the Defect-Free Zone

IP.com Disclosure Number: IPCOM000048585D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Cameron, DP: AUTHOR [+4]

Abstract

Chemical bevelling, preferential etching for defect delineation and SEM (Scanning Electron Microscope) observations allow precise characterization of defects for location, type, and number. Thus, a defect-free zone can be defined quantitatively in terms of a number within a certain thickness per unit length observed.

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Chemical Bevelling For Determining the Defect-Free Zone

Chemical bevelling, preferential etching for defect delineation and SEM (Scanning Electron Microscope) observations allow precise characterization of defects for location, type, and number. Thus, a defect-free zone can be defined quantitatively in terms of a number within a certain thickness per unit length observed.

A silicon sample such as a product wafer, with oxide or oxide/ nitride pattern- forming windows to silicon or Pt/Si, is etched anisotropically in a solution such as a mixture of NaOH + H(2)O Plus isopropyl alcohol at an elevated temperature of approximately 80 Degrees C. The duration of etching should be sufficient to remove sufficient silicon from the large windows. The amount of silicon removed from small windows is self-limiting because the anisotropic etching on (111) planes is extremely slow. This etching, thus, generates a well-defined etch pit in the area of the windows in the mask and the walls of such a pit are mostly (111) crystallographic planes.

A slight etching with a dislocation/defect-delineating etch brings out defects that can be observed with a SEM at high resolution. Counting of these defects in a defined region, for instance, up to 10 Mum below the surface, is relatively easy because most of the defects can be easily identified by the typical etch features they form. With this technique, it is possible to predefine the location of the chemical bevel by appropriate selection o...