Ph. D. THESIS 2009

(NA 1.25) in phase-contrast (a) and transmission (b).
In figure 7 we can see SEM views of dots deposited at 6mW and 6s exposure
time, recorder at 4000 order of magnitude and 5 m scale. We notice that the
results essentially depend on the total amount of laser energy sent. As already
discussed, we see that most of the produced dots are actually rings, only the
extremely small ones can be dots without hole.
Figure 7. (a) SEM image of a silver dots network fabricated at different laser
powers and exposure time ; (b) Silver dot obtained at 6mW and 6s exposure
time
3.6.2. 3D structures
Three dimensional silver structures were fabricated using the same chemical
system presented for dot and line fabrication.
The TPA reduction of silver ions was performed within a 12 hours old thick
film, obtained by deposition of a droplet of the solution on the substrate. The
surface of a 2.5x2.5 cm microscope slide was modified with polyimide in order
to improve the attachement of silver structure onto the surface during the
fabrication [29].
The 3D structure was written using a 100xPh3 immersed-oil objectiv lens
with 1.25 NA, to deliver 4-5 mW of power to the sample. The lines can be
generated by translating the stage in the XY-directions at a velocity of 0.5 m/s
and a DT of 2 ms.
Connection between XY translation and displacement of the sample holder in
the Z-direction with a computer programm allowed to obtain a woodpile-like
structure as a 10 degree tilted quadratic prism, with 20 m width of base along
x and y axis, and 14.4 m total height. The three-dimensional object consists of
12 layers, each layer containing 6 lines with 4 m period, oriented
alternatively, parallel, on X and Y, respectively. The height of each layer is
about 1.2 m, with a 0.4 m step size for Z-axis and 3 integer dz-units.
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