1. Interferometric Modulator Display Presentation 4: Anatomy of an iMod
Influenza del controllo d'imbardata sul rendimento degli aerogeneratori di piccola taglia
Interferometric Modulator Display
Presentation 4: Anatomy of an iMod
ACCOTO Celso
ADHAM Mohamed
LARRIEU JeanCharles
LE GROS Christophe
MAQUEDA LÓPEZ Mariazel
OTTONELLO BRIANO Floria
PIZZATO Daniel
SADRINI Jury
Team Members:
DIPARTIMENTO DI INGEGNERIA DELL’AUTOMAZIONE E DEI SISTEMI 1

2. Introduction Agenda: New Design Simulations Fabrication
Presentation 3:
We are designing a new MEMS based Display based on a Fabrey Perot Interferometer (iMod)
Previous Problems:
- Actuation voltage too high
- process: insulating material (PMMA)
would have melted…
Agenda:
New Design
Simulations
Fabrication

3. Improving the Design
Last time,
we planned to:
Changed physical design
Modify back electrode of device
Materials
More compliant materials
Thicknesses
Thinner back plate (technology issue)
Lengths
Resolution is a constraint
Boost V
Low power constraint

4. two beams support the reflective plate
New ANSYS Design
New single IMOD model:
two beams support the reflective plate
Former design

5. MATBLAB Simulations
Why did we simulate our model on MATLAB?
it’s difficult to set design parameters on ANSYS
to have an idea of the values that we will use on ANSYS
for the dynamic simulation
Hypothesis:
Static simulation: just a look at the final state of the system
▪ No viscosity forces
▪ No switching time analysis
2) Clamped beam modeling of the system
3) Everything is made with poly-Silicon

6. Displacement function of the voltage (3 to 6 V)
MATBLAB Results
Dimensions:
20 μm plate
Displacement function of the voltage (3 to 6 V)
Vertical position of beam along its length

7. MATBLAB Results New Design: Lenght Voltqge 8 μm 31.1 V 10 μm 22.3 V

8. 26 % improvement changing the design!
MATBLAB Results: comparison
Results:
@ 20 μm: from 30 V to 7.8V
26 % improvement changing the design!

9. Choice of the design
Adv: residual stress just twist the structure.
Dis: difficult to design.
Adv: beams instead of plate

10. ANSYS Design
New design:
From plate to beam
Less stiff system
Plate parallel to substrate

11. ANSYS Simulation Difficulties…
400 lines code
34 3-D points (102 positions)
Problems in the meshing
Problems assembling the system

12. Process Flow & Mask Design
New process flow:
Previous mistakes
New design
Mask modeling:
AutoCAD
Eg. of mask
... Still preliminary

13. Process Flow
Glass substrate
Silver deposition: sputtering

14. Process Flow
Silver deposition:
sputtering

15. Process Flow
Resist deposition

16. Process Flow
Mask 1

17. Process Flow
Etching

18. Process Flow
Dielectric layer

19. Process Flow
Mask 1
Resist+etch+resist removal

20. Process Flow
SiO2 layer:
PECVD

21. Process Flow
Mask 2
Resist: DQN

22. Process Flow
SiO2 etch 80 nm
exactly

23. Process Flow
Mask 3
Resist: DQN

24. Process Flow
SiO2 etch 50 nm
exactly

25. Process Flow
Remove DQN

26. Process Flow
Deposition of Al:
Reflective layer

27. Process Flow
Mask 4
Deposition of
protective squares

28. Process Flow
Etch of Al +
Removal of protective
squares

29. Process Flow
SiO2 deposition

30. Process Flow
Mask 5
Etching of SiO2

31. Process Flow
Mask 6
Etching of SiO2

32. Process Flow
SiN deposition

33. Process Flow
Mask 7
Etching of SiO2

34. Concept of the system Vhold V+ V- Processor TSP 65131 Battery
Column selection
Processor
TSP 65131
Vhold V+ V-
Row selection
“Operating Principles of Mirasol Displays: Interferometric Modulation (IMOD) Drive”, QUALCOMM December 2007

35. PSPICE Design
“Operating Principles of Mirasol Displays: Interferometric Modulation (IMOD) Drive”, QUALCOMM December 2007

36. Conclusions Mask is the 1st approximation of the fabrication process
Final masks for the process are under review
Ansys/Matlab:
Less stiff beams → lower activation voltage: 8V
Vibration analysis and switching time to be checked
PSPICE
Addressing circuit has been defined
Power consumption has been evaluated

37. Thank you
for your attention!