Biomedical Engineering Reference
In-Depth Information
However, pertaining to the stability of the embedded organic FET, the best
option could be to replace the organic semiconductor with a non-organic
channel material having a good process compatibility with that of SU-8. So
Al- doped zinc oxide (AZO) as a channel later for CantiFET applications
have been explored [29].
h e process of this device started with RCA clean wafer followed by ther-
mal oxidation to grow a 900 nm silicon di-oxide as sacrii cial layer. Next
the encapsulation layer and contact via of the cantilever die was fabricated
using UV-exposure of SU-8 polymer layer. Using sputtering, Cr/Au layer of
thickness 10nm/90nm was deposited and patterned for gate electrode and
contact via. Another SU-8 layer of 900 nm was patterned for gate dielec-
tric. In the next process step, source/drain layer was fabricated as described
for gate electrode. A 150μm thick anchor was patterned using SU-8 2100.
h e cantilever die was released from the wafer by sacrii cial oxide etching
using 5:1 BHF. h e semiconducting layer of Al-doped ZnO was deposited
on the backside of the cantilever using sputtering. h e process l ow is given
in Figure
9.15 A. h e optical image is shown in Figure
9.15 B.
h e output characteristics for the ZnO TFT embedded CantiFET device
were recorded for gate voltage in the range of 0-40V (Figure
9.16a). h e
Figure 9.15
A. Fabrication process for AZO integrated SU-8 microcantilevers (a)
Sacrii cial layer (b) SU-8 2002 encapsulation layer (c) Contact Pad and Gate electrode
pattering using Cr/Au (d) Gate dielectric pattering (e) Source/Drain contact of Cr/Au
(f ) h ick SU8 pattering as anchor layer (g) Release of the device from the silicon wafer. B.
Optical image of ZnO TFT embedded cantilever[29].
