Biomedical Engineering Reference
In-Depth Information
Diffused
waveguides
Photoresist
(AZ-1350)
Z-cut LiNbO
3
Photoresist spin coating
In-diffusion of titanium
Mask
UV
Patterning by UV exposure
Evaporation of SiO
2
Al
AZ-1350
SiO
2
Developing photoresist
Evaporation of aluminum;
photoresist spin-coating
Ti
Evaporation of titanium
UV exposure; developing
SiO
2
Electrodes
Ti
Lift-off of titanium
Etching of Al
FIGURE 5.20
Fabrication for channel waveguides using Ti:Indiffused LiNbO
3
.
After drying the resist is ready for exposure. There are two basic types
of photoresists: negative acting and positive acting. Both types function via
altering of the polymer solubility due to exposure. With exposure in selected
areas some regions will be soluble in the developing solutions while oth-
ers remain insoluble and form the resist surface. In negative acting resists
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