Abstracts Book - IMRC 2018

• SB4-P013
BENDING CYCLES STUDY OF HAFNIUM OXIDE CAPACITORS ON
DEFORMABLE SOFTENING POLYMER SUBSTRATE
Ovidio Rodriguez Lopez 1,2 , Gerardo Gutierrez Heredia 3,4 , Alexander J. Polednik 4 , Edgar
Guerrero 4 , Aldo Garcia Sandoval 1 , Walter Voit 1,4
1
The University of Texas at Dallas, Department of Biomedical Engineering, United States. 2 The
University of Texas at Dallas, Department of Electrical and Computer Engineering, United
States. 3 Centro de Investigaciones en Optica, Fotonica, Mexico. 4 The University of Texas at
Dallas, Department of Material Science and Engineering, United States.
The development of electronic devices on flexible substrates has been
increasing due to the broad field of applications this technology could be applied
to. In fact, biomedical applications have taken advantage of this technology with
the fabrication of chronical and implantable devices, such as neural interfaces
or implantable electrodes. However, in order to achieve the rigorous demand of
these applications, high performance, reliability, stable behavior and resilience
to the periodic mechanical stress are needed for the electronic circuits.
Therefore, further research in electronics components such as transistor and
diodes, among others devices, is needed to develop reliable complex circuits on
flexible substrates. This work presents the electrical performance of hafnium
oxide (HfO2) thin-film capacitors on a softening polymer, as a flexible substrate.
This softening polymer used as the substrate is a shape-memory polymer (SMP),
which has been previously used for implantable devices. SMP is well known to
retain a certain shape after deformed, and return to its original state when an
external stimulus is applied. The metal-insulator-metal capacitors were
fabricated using gold as top and bottom contacts and HfO2 as a dielectric,
deposited by atomic layer deposition at 100°C. The HfO2 dielectric properties
are evaluated after 10 2 , 10 3 , 10 4 and 10 5 cycles of bending. For the purpose of
this study, capacitance density, dielectric constant and current density of the
capacitors after each set of cycles were obtained. The dielectric constant
measured went ~18 before the bending cycles to ~16.5 after 10 5 cycles. On the
other hand, the leakage current remains between 3.5x10 -8 to 2.6x10 -8 A/cm 2 at
1MV/cm before and after the bending cycles. The results show the performance
and resilience of the ALD-HfO2 deposited at low temperature to mechanical
stress, and the capability of the SMP for the fabrication of flexible electronic
devices, such as thin-film transistors. This research will allow further studies of
thin film transistor using SMP as a mechanical substrate and assist in the