Biomedical Engineering Reference
In-Depth Information
Data
conversion
Substrate
prep
Design and
layout
Wafer
prep
Pattern generator
Photo-
lithography
Mask
Substrate
develop
Wafer
develop
Wafer
Figure 12.1
(See companion CD for color igure.)
. Cartoon. illustrating. the. different. roles. of. electron. beam. and.
photolithography.
approach.using.EBL.in.the.research.stage.needs.an.evolutionary.path.to.photolithography.
to.obtain.the.large.economies.of.scale.that.have.dominated.nanoelectronics.
The. remainder. of. this. chapter. will. introduce. the. nonspecialist. to. the. capabilities.
of. EBL. and. provide. practical. advice. for. anyone. planning. to. exploit. the. technology. for.
nanobiological.applications.
12.3 Basics of Electron Beam Lithography
There.are.four.broad.considerations.that.come.into.play.when.patterning.at.the.nanoscale..
They.are.image.idelity,.image.placement,.defects,.and.cost..These.do.not.exist.in.isolation;.
it.is.frequently.possible.to.achieve.improvement.in.one.area.at.the.expense.of.the.others..
In.the.next.sections,.we.will.examine.in.detail.the.factors.that.measure.the.performance.
in.each.of.these.categories.and.the.nature.of.the.trade-offs.involved..Figure.12.2.shows.
the.major.elements.of.a.generic.EBL.system..The.optical.subsystem.consists.of.the.source,.
the.condenser,.and.the.projection.optics..The.patterning.subsystem.consists.of.a.blanker,.
delector(s),.and.stage..The.blanker.is.a.pulse.width.controlled.modulator.that.regulates.
the.electron.current.according.to.the.demands.of.the.pattern..The.delection.subsystem.
is. used. to. sweep. the. beam. as. required. to. paint. the. geometrical. shapes. deined. by. the.
pattern.. Lens. aberrations. limit. the. range. over. which. the. beam. may. be. delected. while.
