Browse Prior Art Database

VLSI/VCOS SEM Electron Charging Eliminator

IP.com Disclosure Number: IPCOM000109992D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Fredericks, EC: AUTHOR [+2]

Abstract

Present electron microscopy of non-conductive samples is achieved either by reduction of acceleration voltages or by use of coating techniques for surface conductivity modification. Reduction of accelerating voltages, or "low voltage scanning electron microscopy" has the undesirable effect of reducing final resolution and require different adjustment/centering of the electron beam column. Palladium coating is an acceptable alternative, but requires additional tooling, such as a sputter coater. It is also a destructive process since the sample, i.e., wafer, cannot be used again in the process, having been contaminated by the sputter tool vacuum system and the layer of deposited sputtered metal.

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VLSI/VCOS SEM Electron Charging Eliminator

       Present electron microscopy of non-conductive samples is
achieved either by reduction of acceleration voltages or by use of
coating techniques for surface conductivity modification.  Reduction
of accelerating voltages, or "low voltage scanning electron
microscopy" has the undesirable effect of reducing final resolution
and require different adjustment/centering of the electron beam
column.  Palladium coating is an acceptable alternative, but requires
additional tooling, such as a sputter coater.  It is also a
destructive process since the sample, i.e., wafer, cannot be used
again in the process, having been contaminated by the sputter tool
vacuum system and the layer of deposited sputtered metal.

      This article introduces a novel method for changing the surface
conductivity of observed specimens.  For example, photoresist-coated
and patterned wafers can be modified by selectively depositing a thin
layer of palladium on the portion of the specimen (wafer) surface
under investigation in the same SEM tool where the investigations are
conducted.  At completion of the investigation, the wafer is placed
in a potassium iodide solution, for complete removal of the palladium
film.  Final rinse follows and the wafer is then returned to the lot
for subsequent processing.

      This method is shown in connection with an apparatus in the
figure.  A small 1/8" diameter pencil-shaped deposition probe (a) is
at the...