Transcript e-Beam Lithography - University of Guelph

e-Beam Lithography
Antony D. Han
Chem 750
U of Waterloo
06-02-07
What is lithography?
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Original meaning:
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Modern usage
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a process of printing using a non-polar ink applied to a hydrophilic
master plate patterned with a hydrophobic image.
The term is more generally applied to a number of methods for
replicating a predetermined master pattern on a substrate.
Replication is effected by first coating the substrate with a radiationsensitive polymer film (a resist) and then exposing the film to actinic
radiation in a pattern-wise manner. The radiation chemistry that results
alters the physical or chemical properties of the exposed areas of the
film such that they can be differentiated in a subsequent image
development step. Most commonly, the solubility of the film is modified
with the radiation chemistry either increasing the solubility of exposed
areas (yielding a positive image of the mask after develop) or
decreasing the solubility to yield a negative-tone image of the mask.
Widely used in semiconductor industry and IT industry.
Focused eBL: ~sub 50 nm resolution
Steps involved in the EBL process.
With a beam current of 600 pA and an accelerating voltage of 100 kV,
the beam diameter was approximately 3 nm.
J. Phys. Chem. B 2002, 106, 11463-11468
e-Beam Lithography
 Electron
source: SEM
 Equipment: SEM equipped with a pattern
generator and alignment system
 e-beam control:
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accelerating voltage (kV)
operation current (pA)
exposure dose (µC/cm2)
exposure dwell period (µs)
eBL followed by SA
Langmuir, Vol. 20, No. 9, 2004, 3495
eBL changes the properties of coating layers
Langmuir, Vol. 20, No. 9, 2004 3767
Applications of eBL
(a) Backscattered electron
(BSE) image of ZnO patterns
on SiOx substrates annealed
in air at 700 °C for 20 min
(b) secondary electron (SE)
image before annealing
(c) SE image after annealing
at 700 °C for 20 min in air
(d) SE image of annealed
patterns over a large area.
Nano Lett., Vol. 5, No. 9, 2005
Applications of eBL
Proceedings of SPIE Vol. 5184
Limitation
 Tradeoffs
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for high-resolution
Time and high resolution
 Improvement
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wrt this limitation
More sensitive resists
Cold developers (<10 ºC)
Thank you!
eBL applications
Langmuir, Vol. 20, No. 9, 2004 3767