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Browse Prior Art Database

Noise-Reduced Registration in Corpuscular Beam Lithography

IP.com Disclosure Number: IPCOM000101285D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Bohlen, H: AUTHOR [+4]

Abstract

In corpuscular beam proximity printing, mask and wafer must be rapidly aligned with submicron accuracy to ensure a high yield and throughput. Conventional registration systems, such as those described in U.S. Patent 4,370,554, afford the necessary precision but require several time- consuming sweeps to eliminate the influence of current noise in the registration signal.

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Noise-Reduced Registration in Corpuscular Beam Lithography

       In corpuscular beam proximity printing, mask and wafer
must be rapidly aligned with submicron accuracy to ensure a high
yield and throughput.  Conventional registration systems, such as
those described in U.S.  Patent 4,370,554, afford the necessary
precision but require several time- consuming sweeps to eliminate the
influence of current noise in the registration signal.

      The figure shows a new arrangement of registration marks 3
which are separated from wafer 5 by an insulating layer 4.  The
individual registration marks 3 are electrically connected in
parallel by a conductor 6 which is also defined lithographically on
layer 4 and which is accessible via a terminal pad for signal
extraction. Conductor 6 collects all electrons absorbed in
registration marks 3 from electron beam 1 which is projected through
a registration pattern in mask 2 onto marks 3; the registration
signal is measured in ammeter 7.  The pattern of registration marks 3
is preferably inverted to the registration pattern in mask 2,
resulting in a minimum registration current at optimum alignment.  As
in conventional systems, electron beam 1 may be tilted at an angle a
for fine alignment.

      For a strong registration current, the thickness of
registration marks 3 should be of the same order as the penetration
depth of the electrons, say, some 0.1 micrometer for 10 keV
electrons.  Different sets of (identical) regi...