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Browse Prior Art Database

Apparatus for Locating Particles on a Blank Wafer in a Scanning Electron Microscope

IP.com Disclosure Number: IPCOM000042552D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Cameron, DP: AUTHOR

Abstract

Fast and easy location of particles on a blank wafer in a SEM (scanning electron microscope) is achieved by interfacing the SEM to an LM (light microscope) whose stage carries an oblique light photograph of the same wafer. Blank wafers are exposed to the insides of semiconductor processing tools and to their environments to pick up particulate contamination. An oblique light photograph of an exposed wafer is a map of the particle locations. This photograph is placed on the stage of a 15X monocular LM with a crosshair eyepiece, as shown in the drawing. The stage has rectilinear potentiometers attached to it, which, when supplied with DC power, convert the X and Y positions to two voltages.

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Apparatus for Locating Particles on a Blank Wafer in a Scanning Electron Microscope

Fast and easy location of particles on a blank wafer in a SEM (scanning electron microscope) is achieved by interfacing the SEM to an LM (light microscope) whose stage carries an oblique light photograph of the same wafer. Blank wafers are exposed to the insides of semiconductor processing tools and to their environments to pick up particulate contamination. An oblique light photograph of an exposed wafer is a map of the particle locations. This photograph is placed on the stage of a 15X monocular LM with a crosshair eyepiece, as shown in the drawing. The stage has rectilinear potentiometers attached to it, which, when supplied with DC power, convert the X and Y positions to two voltages. These voltages are inputs to the stage positioning circuits of an SEM with a motor-driven stage, upon which has been placed the wafer previously photographed with oblique light. The analyst positions the LM stage so that a dot on the photograph (representing a particle) is at the crosshairs. The SEM stage follows, and positions the actual wafer so that the corresponding particle is brought into the field of view. The particle can then be photographed and analyzed for elements present by energy-dispersive X-ray spectroscopy. This method could be applied to objects other than blank wafers if: - The object has detail visible in the SEM at high magnification, but lacks detail visible in the LM. --OR-...