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High-Voltage Electron Beam Column Optics for Chip Or Membrane Mask Fabrication

IP.com Disclosure Number: IPCOM000119660D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Gesley, MA: AUTHOR

Abstract

A combination of an improved electron gun and magnetic objective lens solves several problems in the fabrication of chip or membrane mask membranes by electron beam lithography. By operating at 100 kV, it drastically reduces proximity effects resist exposures caused by electron scattering. This has a beneficial effect by simplifying the dose correction assignment to the chip or mask membrane pattern. It improves the sidewall profile of thick single layer resists, thereby avoiding the more complicated multilevel resists systems otherwise needed in many cases. It provides the possibility of continued pattern reduction from 0.50 mm to 0.10 mm and below. It makes possible an increase in the writing speed of the electron beam lithography tool or the use of less sensitive resists in the pattern transfer to the membrane.

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High-Voltage Electron Beam Column Optics for Chip Or Membrane Mask
Fabrication

      A combination of an improved electron gun and magnetic
objective lens solves several problems in the fabrication of chip or
membrane mask membranes by electron beam lithography.  By operating
at 100 kV, it drastically reduces proximity effects resist exposures
caused by electron scattering.  This has a beneficial effect by
simplifying the dose correction assignment to the chip or mask
membrane pattern.  It improves the sidewall profile of thick single
layer resists, thereby avoiding the more complicated multilevel
resists systems otherwise needed in many cases. It provides the
possibility of continued pattern reduction from 0.50 mm to 0.10 mm
and below.  It makes possible an increase in the writing speed of the
electron beam lithography tool or the use of less sensitive resists
in the pattern transfer to the membrane.  It increases the exposure
field size for high resolution patterns and reduces objective lens
pole piece saturation problems that are associated with higher
demagnification systems which are forced to reduce objective lens
working distance to achieve similar resolution.

      The aforesaid improvements, as shown in the drawing, are
achieved by combining a high brightness field electron gun that can
operate in the 50 kV to 100 kV beam voltage range with a magnetic
objective lens in a column optics that optimizes resolution at the
wafer plane, increases current density and includes several features
that are either necessary or improve the utility of the electron
optical column.

      A key point of the design disclosed here is the doublet lens
system which is optimized for maximum current density at high
resolution.  This lens configuration simplifies beam alignment by
eliminating the two magnetic condenser lenses that normally are used
in conjunction with the objective lens to focus the...