Abstract:
This work focuses on the development of a method for probing the mechani-
cal response of thin film materials based on miniature tensile testing. A number
of mechanisms that may compromise the performance and potentially limit the
operational lifetime of MEMS devices which incorporate functional ferroelectric
ceramics were also identified and investigated. Reliability of piezo MEMS com-
ponents was studied at a wafer and at a device level through the development
of appropriate techniques based on miniature tensile testing, time- resolved mi-
cro RAMAN spectroscopy and laser Doppler vibrometry. Micro tensile testing
was further used for the extraction of the elastic properties of various thin film
materials.
A miniature tensile stage was developed in common with DEBEN UK for
the mechanical characterization of functional thin film materials like PZT and
ZnO ceramics, which are commonly used in MEMS fabrication. The stage is of-
fered with a piezo electric motor which can be fitted with interchangeable heads.
These can be combined with di.erent types of mounting jaws, enabling both con-
ventional tensile testing and compression testing to be performed. Strains and
displacements were measured in- situ using an optical, non destructive method
based on CCD imaging. The elastic constants of polymer (LCP), LCP-Au bi-
layers and electroplated Ni were defined in good agreement with the literature.
However yield of successfully released ceramic samples was rather poor so a col-
laboration with IMTEK at Germany was established. Using their facilities batch
processing of a large number of wafers was possible. Cont/d.
