Mechanics and Tribology of MEMS Materials - prod.sandia.gov ...
Mechanics and Tribology of MEMS Materials - prod.sandia.gov ...
Mechanics and Tribology of MEMS Materials - prod.sandia.gov ...
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The effects <strong>of</strong> exposure conditions on the water contact angle for PFTS coatings are<br />
shown in Figure 7.6. For this coating, contact angles were generally near 120 degrees except for<br />
the<br />
Contact Angle, deg<br />
Contact Angle, deg<br />
120<br />
110<br />
100<br />
90<br />
80<br />
as-dep<br />
50 krad N2<br />
50 krad air<br />
500 krad N2<br />
500 krad air<br />
Fig. 7.5. Water contact angle for Si(100) samples coated with ODTS, after exposure to radiation<br />
(a) <strong>and</strong> heating to 300°C in various environments (b).<br />
120<br />
110<br />
100<br />
90<br />
80<br />
as-dep<br />
pre-XPS<br />
post-XPS<br />
pre-XPS<br />
post-XPS<br />
50 krad N2<br />
(a)<br />
50 krad air<br />
ODTS<br />
Co-60 exposure<br />
PFTS<br />
Co-60 exposure<br />
500 krad N2<br />
500 krad air<br />
Fig. 7.6. Water contact angle for Si(100) samples coated with PFTS, after exposure to radiation<br />
(a) <strong>and</strong> heating to 300°C in various environments (b).<br />
sample exposed to 500 krad in nitrogen. No such decrease is observed for the sample exposed to<br />
an equivalent dose in air, so it is believed that the reduced contact angle on this specimen is due<br />
to lower initial coverage <strong>of</strong> the PFTS. Although all samples were coated at the same time in the<br />
same solution, it is possible that the sample became oriented in such a way during a rinse step<br />
that the polished surface was directly in contact with the side <strong>of</strong> the crystal carrier, inhibiting<br />
access <strong>of</strong> the surface to the alkylsilane in solution. Excluding this data point, the results in<br />
Figure 7.6 show that radiation exposures up to a total dose <strong>of</strong> 500 krad have no significant<br />
impact on the contact angle <strong>of</strong> PFTS films. The thermal exposures also exhibit no impact <strong>of</strong><br />
68<br />
Contact Angle, deg<br />
Contact Angle, deg<br />
120 ODTS<br />
300 C Anneal<br />
110<br />
100<br />
90<br />
80<br />
120<br />
110<br />
100<br />
90<br />
80<br />
as-dep<br />
as-dep<br />
pre-XPS<br />
post-XPS<br />
60 min N2<br />
pre-XPS<br />
post-XPS<br />
60 min N2<br />
(a) (b)<br />
10 min dry air<br />
(b)<br />
10 min dry air<br />
10 min 13% RH air<br />
PFTS<br />
300 C Anneal<br />
10 min 13% RH air