Hello all,

the figure:  http://yuchin.kao.googlepages.com/02.jpg
Purple: teflon  black: Si   Blue: Si3N4    Red: metal

1. Deposit Si3N4 layer (3000A) on the double side of the wafer.
2. Photolithography process to pattern the cavity and etch through the
wafer(as the fighre)
    the width of the cavity is about 1.5mm and the depth is 400um(etch
through the wafer)
3. Deposit teflon on the topside(the thickness have not been designed.)
4. Remove teflon on Si3N4
5. Remove Si3N4 in the cavity to make the metal layer suspended (the
metal layer will be the bottom of the cavity )
    There are no teflon on the bottom of the cavity(metal layer)

Step 4 is a big problem for me. The cavity is too deep to coat PR. So I
can't use lift-off and photolithography process to pattern teflon.
If the adhesion between teflon and Si3N4 is weak,  maybe I can use
supersonic clean to lift off the teflon on Si3N4

Is there any method to solve this problem?


Thanks all.