Biomedical Engineering Reference
In-Depth Information
then developed in the solution of methyl isobutyl ketone (MIBK)
and isopropyl alcohol (IPA) of MIBK:IPA with a ratio of 1:3 for
60 seconds, rinsed again (with IPA for 20 s), and blow-dried with
nitrogen gas. Once the development of the resist was completed, a
3 nm-thick gold (Au) film was sputter-deposited on the patterned
substrate. This was followed by thermal evaporation of another
27 nm of Au to bring the total thickness of the gold film to 30 nm.
Note that the sputtered 3 nm thick gold is used (instead of any
adhesion layer, such as Ti or Cr) between the gold film and the
glass substrate. This fabrication method is especially suitable for
our purposes, as the Ti or Cr layers usually change the resonance
featuresoftheTaijimark.Finally,suchfabricatedsamplewassoaked
in acetone for over 12 h, and then the un-patterned regions were
lifted off inan ultrasonic cleaner.
13.2.2
Taiji Mark Design
Figure13.2ashowsaSEMmicrographofthefabricatedTaijipattern;
a schematic drawing of the ideal Taiji pattern is shown in Fig. 13.2b.
Figure 13.2
(a) SEM image of a small region from the fabricated sample,
showing diameter of tails. (b) The ideal design of Taiji mark. (c) Magnified
viewofasinglecellintheSEMimageofframe(c)showingthefittingcurves
of a fabricated Taiji mark (R1
=
275 nm, R2
=
250 nm, D1
=
100 nm,
diameter of the tangent circle D2
=
60 nm).
