Online proceedings - EDA Publishing Association

7-9 October 2009, Leuven, Belgium
by the isolation oxide, nitride layers, anchor metal and
IV. FEM METHODOLOGY & RESULTS
nickel layers.
To verify design concept and
device parameters, device
level FEM simulation methodology for the proposed
microgyroscope is devised in this section.
Thermoelectromechanical (TEM) analysis module of the
MEMS Design software IntelliSuite has been used for this
purpose.
3D Builder is used to build and mesh the three-
dimensional geometry of the
MEMS structure before
transferring to TEM module to assign material properties,
loads and boundaries to fully
analyze a device in the
static, frequency and dynamic domain. Simpler and faster
simulations like modal and static analyses were performed
prior to lengthy dynamic simulations to understand the
initial behavior of the device.
A. Modal Analysis
Fig. 3. Microgyroscope fabricated through MetalMUMPs process First of all modal analysis was carried out to predict the
using L-Edit of MEMSPro.
natural frequencies and their respective mode shape for
the proposed microgyroscope. While calculating natural
frequencies and associated mode shapes, a residual stress
of 100 MPa has been incorporated with other
thermophysical properties of nickel (Ni) for accurate
results [9].
Fig. 6, (a) and (b) show the respective drive and sense
mode shape at 5.73 kHz and 5.02 kHz. A slight difference
in the natural frequency of both drive and sense mode is
intentionally made to achieve a larger bandwidth,
compromising the drive displacement at resonance.
(a)
(b)
Fig. 4. Cross sectional views of a microgyroscope (a) 3D view and
(b) 2D view
(a)
Fig. 5. Process flow for the fabrication of microgyroscope using
MetalMUMPs in MEMSPro (a) N-type silicon wafer (b) 2µm
thick isolation oxide layer (c) patterning of Oxide
1 layers (d) patterning
of 0.7µm thick Polysilicon layer (e) patterning of
anchor metal layer (f)
patterning of 20µm electroplated structural layer of Ni and trench etch in
the substrate.
(b)
Fig. 6. Modal analysis results (a) Drive mode at 5.37 kHz and (b)
Sense mode at 5.02 kHz.
©EDA Publishing/THERMINIC 2009 42
ISBN: 978-2-35500-010-2