Spacer for Resonant Cavity

Imaging Biosensor

Elaine Mau, Rutgers University

� [How it works] Resonant Cavity

Imaging Biosensor

(RCIB)

Photodetector Array

Si Si-SiO2

reflector

Collimated

Light

Si

Cavity

Si-SiO2

reflector

microarray

Recorded

Signals

II

λ

I

λ

I

λ

I

λ

Methods

Part 1: Fabrication of the spacer

Part 2: Employment of wafer bonding techniques

a) Gravity

c) Photoresist

Part 3: Examining resonance to determine the viability

of each technique

a) Distance between Mirrors

b) Tilt

c) Stability

Spacer Specifications

Part 1: Fabrication of Spacer

Mask 1: Channels

Part 1: Fabrication of Spacer

Mask 2: Donuts

Front Side Etching

Part 1: Fabrication of Spacer

Mask 2: Donuts

Back Side Etching

Part 2: Employment of wafer bonding

techniques

Part 2: Employment of wafer bonding

techniques

� Gravity

� Photoresist

Part 3: Measurements

Part 3: Measurements

� Distance Between Two Mirrors

� Tilt

� Stability

ResultsGravity Photoresist

Qualities Gravity Photoresist

Average Mirror Separation 225 µm 210 µm

Tilt 2.2 nm/µm 0.22 nm/µm

Stability Somewhat Somewhat

Conclusion

� Alternative method performed for Deep Reactive Ion

Etching is not recommended

� Excessive handling

� Etching channels using method describe is possible

� Etching through for donuts using method describe may be

done using backside etching; however, there is lack of

alignment

� Using photoresist as adhesive is promising, but

further tests must be preformed

� Sandwich is tighter with photoresist

� Tilt of photoresist sandwich was ten times more

Acknowledgements

Thank you Professor Ruane,

David Bergstein, Phillip Spuhler,

Arthur Wu, and Abdol Hossein

Entekhobi

Boston University and National

Science Foundation for providing

this research opportunity!