Browse Prior Art Database

Fabrication of Vertically Aligned Apertures for E-Beam Microcolumn Application

IP.com Disclosure Number: IPCOM000114478D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Despont, M: AUTHOR [+3]

Abstract

A new process has been developed for machining electrostatic lenses to be used in a miniaturized electron-beam column. Typically, a focusing element consists of three holes in three electrodes separated by two spacers. Each electrode has a bore between 1 and 100 &mu.m. In a typical configuration, the microcolumn consists of two of these focusing elements, the source lens and the beam forming Einzel lens. Fig. 1 shows a schematic drawing of the source lens and the electric potentials applied to the electrodes.

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Fabrication of Vertically Aligned Apertures for E-Beam Microcolumn
Application

      A new process has been developed for machining electrostatic
lenses to be used in a miniaturized electron-beam column.  Typically,
a focusing element consists of three holes in three electrodes
separated by two spacers.  Each electrode has a bore between 1 and
100 &mu.m.  In a typical configuration, the microcolumn consists of
two of these focusing elements, the source lens and the beam forming
Einzel lens.  Fig. 1 shows a schematic drawing of the source lens and
the electric potentials applied to the electrodes.

      Key for a good lens are: smooth side walls (roughness < 10 nm)
and precise roundness (&Delta.r/r < 10 sup -2) of each bore and the
alignment of the electrodes against each other ( < 1 &mu.m of axis).
In order to achieve these requirements, the disclosed process employs
high-resolution e-beam lithography and RIE.  Masking is done with
high performance e-beam resist and silicon oxide.  The resist pattern
is transferred first into silicon oxide by CF sub 4 RIE and then into
the silicon membrane by Cl sub 2/Ar RIE.

      Aligning of individual lens elements at nanometer-scale
precision demands novel techniques.  In our approach, we propose to
build up the lens layer by layer and machine each layer only after
having it added to the stack.  For machining the second electrode,
resist is spun to the backside of this electrode.  Then the e-beam is
aligned to the center of the bore in the first electrode.  This is
done at low enough energies in order to avoid electron penetration
through both membranes After having aligned the beam, its energy must
be raised.  Now electrons can penetr...