Investigation of Multi-Layer Actuation Carlos R. Jimenez. California State Polytechnic University,...

Investigation of Multi-Layer Actuation

Carlos R. Jimenez.California State Polytechnic University, Pomona. Electrical Engineering, Fall 2006Faculty Mentor: Professor Andrei Shkel. Graduate Student Mentors: Max Perez,

Adam R. Schofield.Department of Mechanical Aerospace Engineering.

08-30-2005

© C. Jimenez 2005, IM-SURE

Motivations for out of plane actuation.

Currently fabricated X-Y axis gyroscope driven by in-plane actuation.

Desired X-Y-Z axis gyroscopes driven by in-plane and out-of-plane actuation.

X

Y

sense

direction

Y

Z

XDriving directio

n

Additional Sense

capabilities


Out of Plane Actuation has a wide range of applications

MEMS micro mirrorsFor optical switching.

X-Y-Z Gyroscopes for the aerospace and automotive

industry.


How are lateral combs actuated?

Regular lateral combs for in-plane actuation driven by an AC voltage signal.

Experimental concept for out-of-plane actuation driven by an AC voltage signal.

Vo

+Vo-

t

Vo

+Vo-

t


Motivations on using offset combs for out-of-plain actuation vs.

parallel plates. Limitations when fabricating structures in Silicon-

On-Insulator for out-of-plane actuations.

Si

Electrode

V

SiO2

Unfortunately current fabricating techniques do not allow placing an electrode under a

microstructure.


Target objectives for the research.

Model various lateral comb architectures in Finite Element Analysis Software along with MATLAB.

Design fabrication techniques to achieve lateral combs with different heights.

Fabricate test structures to observe the deepness differences in the combs.

Attempt to characterize structures.


Modeling Results contd..Force in the Z direction Vs Height of Ground Comb.

Changing Height 0-70um

Constant70 um


Modeling Results contd..

Force in the Z Direction Vs. Potential across Offset Combs

Ground

Variable PotentialFrom 0 to 100V


Modeling Contd..

Out of Plane Force Vs. Comb Displacement.

Displacement.

Force becomesNegative after A 25um rise.

-1.4e-12 N/um levitated


Fabrication parameters for force Maximization

Sensitivity Analysis from the standard model.

Standard@35umTests: 15, 35, & 55um

Standard Gap@10umTests: 5,10 & 15 um

Standard Gap @10um. Tests: 5, 10 & 15um


Designing test structuresMaking and evaluating masks.

First approach: Opaque combs were thought to partially protect combs from UV light when exposed.

Second approach: Create Structures with a two mask deposition.This mask was not successful for its

Unexpected roughness

Successful mask with 250um. resolution

Smooth mask used to fabricate the structure


Manufacturing devicesLithography and etch for two mask

process.

Apply a thick layer of Photo-Resist. Protect the high combs with a first mask and develop the wafer .

Hard Bake the wafer. Apply a thin layer of Photo-resist.

Protect all combs with a second mask and develop again

Deep etch for 90 minutes Si Deep etch for 45 more minutes.


Manufacturing ResultsEvaluating the etching process

Despite the significant height decrease, the final etch was not evenly across the exposed combs.

A Dektek 3 surface profiler was used to estimate the roughness on the small comb surfaces.

Very rough


Pre-CharacterizationIsolating the Moving Structure

Between the combs we deposited Sylgard182, an elastomer with flexible and isolating properties.

Three days after, the elastomer cured, giving the possibility for electrical isolation.

The Characterization of the test device was started but not fully completed.


How likely are offset combs to lift a structure?

Standard in-plane vs. out-of plane forces.


Full MEMS experience.

1.Idea 2.Concept.

3.Modeling

4.DesignLayout

6.Characterization

5.Fabrication


AcknowledgmentsThanks to:

Faculty Mentor: Prof. Andrei Shkel Graduate Student Mentors: Max Perez,

Adam Schofield. Lab: Jesper Eklund, Max Perez, Adam

R. Schofield, Alexander Trusov, Chandra S. Tupelly.

IM SURE: Said Shokair. Calit2: Goran Matijasevic.

Funded by: *National Science Foundation (NSF). *Undergraduate Research Opportunity

Program (UROP).


Questions?

Investigation of Multi-Layer Actuation Carlos R. Jimenez. California State Polytechnic University,...

Documents

Transcript of Investigation of Multi-Layer Actuation Carlos R. Jimenez. California State Polytechnic University,...