Development of a Oxygen Sensor for Marine ... - DTU Nanotech

58 CHAPTER 7. EVALUATION OF RESULTS AND MEASUREMENTS
process step, in case problems with the rest of the process should arise.
There was one small problem with the Pt, the exposure time in the photolithography
was originally set to 7 seconds instead of 4. As a result this,
both the working array and the temperature sensor had huge gaps, or were
missing entire as seen on Figure 7.1.
However once the exposure time was lowered to 4, the problem was solved,
and the fine structure and small dots of Pt was clearly evident, as seen on
Figure 7.2.
Figure 7.2: Pt are no longer missing and both the dots in the working and
the lines in the temperature sensor looks fine.
Beyond this however there was no real problem in fabricating the chip,
except for the problems already mentioned, also while the recipe for the
titanium silicide was new, it formed successfully.
7.2 Temperature Sensor
The temperature sensor was tested to see if it had the required linear dependency,
and to see if the TCR (Temperature Coefficient of Resistance) varied
from the standard and if so, how much it did. This is done in order to know
how much that needs to be compensated, since there is a titanium strip beneath
the platinum, and the gold contacts can also be expected to change it
a bit.
The experiment was done using 2 multimeter’s, a probestation, and a
heating plate. The chip measured on was placed in the probestation, and
the 2 multimeter’s was connected, one measuring the temperature of the chip,
and the other measuring the resistance through the temperature sensor. The
heating plate was then used to raise the temperature to around 50 o C, after
which it was cooled down. Measurements was made both while heating and
cooling.