IMPLEMENTING VERTICALLY STANDING MIRRORS USING SOI MUMPS TECHNOLOGY

Simon Fraser University (Engineering Science)Group Members:Desmond CheungSunjaya DjajaNima JahediDaniel Kim

Motivation

Create vertically standing mirrors Categorized as optical MEMS MEMS: Micro-Electro-Mechanical Systems Optical MEMS used, for example, in

telecommunications/photonics systems

Challenge

Implement vertical mirrors using SOI MUMPS SOI: Silicon-on-Insulator Relatively easy to implement vertical structures

using POLY MUMPS for example Not so using SOI MUMPS SOI MUMPS has only one structural layer No conventional mechanisms like joints and

hinges are available making design difficult

Advantages of Using SOI MUMPS

Only one structural layer: lower cost, more reliable

Has a totally planar structure which is necessary for making micro-mirrors

For other technology, needs CMP before one can make mirrors on it

Previous Attempts

Consist a mirror, push pad, torsion hinge, suspension, locking mechanism, pulling ring and springs

Shortcomings of Previous Attempts

Faulty mechanism for latching mirror in upright position

Suspension springs broke resulting in important structures floating away during fabrication

Several critical features that are supposed to be in the same plane are misaligned

Design Work (1)

Intuitive ideas of how micro-mirrors can be propped are conceived

Building cardboard models to verify intuition Calculations of the dimensions of structures are

made Important thing to note is that things do not scale

from human scale to micro scale in an intuitive manner

Design Work (2)

Cadence Virtuoso Layout Tool is used for layout

Relatively easy laying out structures because SOI MUMPS has only one structural layer

New Design Features

New latch mechanism for holding mirror vertically

Reduction in number of operations needed to prop up mirror

Simplicity of design Increased reliability of mechanism

New Designs

There are a total of 2 new designs with several different variants on feature sizes

Animations of the design in action will be given

Limitations Encountered

Amount of trenches in SOI substrate must not exceed 33%

This is the most serious technology-related limitation

Technology-related limitation as opposed to design-related limitation

d1

d2

d1

d2

Pull and Release

Mirror

Desmond’s Design Animation

Desmond’s Design (1)

Desmond’s Design (2)

Desmond’s Design (3)

Sun’s Design (1)

Sun’s Design (2)

Daniel’s Design:

Presentation3.avi

Saewon’s Design

Nima’s Design (1)

Nima’s Design (2)

Nima’s Design (3)

Conclusion

The design was due on 23 June 2003 The design would be back sometime in

October 2003 Testing will then commence Depending on the success of the designs,

hopefully at least one paper would be published