I met a problem with polyimide based humidity sensors
I used polyimide to be a dielectric layer.
The bottom electrode is gold pattern and the top electrode is either copper or
gold.
I used thermal evaporator to coat with copper layer and the sensors work very
well after the polyimide absorpt the moisture.(i.e, I can see the huge
capacitance change).
But I used e-beam evaporator to coat with gold; and every sensor is
shorted.(i.e, there is a resistance between these two electrodes)
The curing process of polyimide is that heat it at 150C for 30 min and increase
the temp. to 350C for 30 min.
Should it be fully cured?? but I skip one step that is to cure and ramp to 350C
in inert gas.
Is it possible the ion-beam attacking the polyimide or is there some problem due
to the curing process ??
Is there someone who can tell me the reason why e-beam evaporation doesn't work
and make my sensors short.
Any possible reason is welcomed.

Lung-hao Hu

Graduate Student

Dept.of Mechanical Engineering
Univ.of Colorado Boulder
UCB 427 CO 80309 U.S.A
Email:[email protected]
Tel:303-786-1702(H)
    303-492-6107(O)
Fax:303-492-3498