200
D. George and M. J. Madou
Photoresist (PS)
Substrate
Heat treatment
and developing
Heat treatment
and developing
Positive photoresist
Negative photoresist
Etching
Deposition
PS removal
Fig. 2 Photolithography-based fabrication
FIB
Sputtered
material
Laser
Shock wave
FIB-based material removal
Laser-based material removal
Direct writing-based
additive manufacturing
Dispensed material
Nozzle
Fig. 3 Additive manufacturing, and focused ion beam (FIB) and laser-based material removal
methods
writing technique can deliver complex three-dimensional shapes by implementing a
layer-by-layer writing approach [149]. With the recent advances in the field of direct
writing methods, many complex multi-material three-dimensional shapes with high
resolution are possible. However, achieving high aspect ratio structures with high
fidelity is still a challenge.
Another precursor film fabrication approach is through material removal, such
as by cutting of thin sheets. Traditional machine-based cutting is widely adopted
for the fabrication of various shapes owing to its centuries-old usage. However,
this traditional method lacks the capacity to machine tiny two-dimensional shapes.
Recently, numerous material removal techniques that utilize non-traditional methods
have emerged. For instance, thin sheets can be directly cut using lasers or focused