ThreeDimensional Nanospring for Electromechanical Sensors

1
Three-Dimensional Nanospring for
Electromechanical Sensors

• D.J Bell,Y.Sun,L.Zhang,L.X.Dong,B.J.Nelson,and
  D,Grutzmacher
• ETH,University of Toronto,PSI,Villigen
• TRANSDUCERS05
• ?????? 9533579

2
Outlines

• Introduction
• Fabrication
• Characterization experiments
• Result and discussion
• Conclusions

3
Introduction

• 3-D Helical structures
• Piezoresistance change
• Displacement

4
Fabrication
Substrate
Dry etching
(a)
(f)
Epitaxial deposition of SiGe
(b)
Remove Photoresist
(g)
Epitaxial deposition of Si
(c)
Use NH4OH etching
Photoresist
(h)
(d)
E-Beam/Photolithography
lt100gt
(i)
(e)
5
Characterization experiment

• Manipulation
• (b) - (e)
• Stiffness
• measure with
• AFM cantilever

6
Characterization experiment
Conductivity change caused by the deformationof
nanospring, such as in bending
7
Results and discussion

• Axial force vs. nanospring elongation from
  experiment

0.176 µN 4.5µm
8
Results and discussion

• Finite element simulation
• Stiffness
• 4 turns 0.0302N/m
• 5 turns 0.0191N/m
• Exp. Result0.0233N/m

9
Results and discussion

• I-V curve of nanospring with 11turns

10
Conclusions

• A satisfactory agreement between the experiment
  and simulation.
• Low stiffness.
• The increasing additional metal layer increases
  the diameter of the helication.
• The high resolution.
• By varying n-turns, thickness, diameter, or
  pitch, the required stiffness can be designed.