1100
am Cross
e angular
re errors
s a block.
1g bits as
of these
ld of the
th current
ontrast of
ular value
NO blocks
n case of
Jal angle.
rotational
length or
| check of
. Another
tected as
tinance is
. First we
ixels on a
t possible
s brighter
ture width |
an, yellow
parent for
ansparent
1995
transmission
Figure 16: Transmissivity of varnish
-
-
o0 o o
à... N' Oo —Q0
o
Un
0.
0.
0.
0.
31
for blue radiation and cyan is not
transparent for red light. The advantage of
color slides is the easy generation of
optimized’ spatial and speetral structures
for color sensor applications.
-—-
Second we coated thin glasses with
coloured resist, known from the silicon
fabrication. The advantage of the resist is
the possibility to form easily high precision
geometries on the semiconductor through
technological processing steps. We used
red and blue varnish, developed for silicon
fabrication, both from Hoechst The
absorption was quite low compared with
color slides. Thick varnish layers are very
difficult to process and additional mask
steps are required.
4}!
3 "
2n:
1
1 1 L 1
600 7 8 900 1000 1100
wavelength fnm]
Figure 16 shows the transmission for the
two investigated coloured resists. The
absorption is obviously small. For that reason no further experiments with varnish have been made.
Zhu et al. investigated voltage controlled color filters with nipin structures [9] fabricated with special processing steps.
Those structures are composed of doped n-layers and p-layers and intrinsic i-layers inbetween. As such structures are
not available within EUROCHIP, no experiments with nipin devices have been performed in our group.
ACKNOWLEDGEMENTS:
We wish to thank the Mikroelektronik Anwendungszentrum Hamburg and the groups of Semiconductor Technology and
Biomechanics at the Technical University of Hamburg-Harburg for their help in spectral measurements and
preparations of the color filters.
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[4]
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