Flashcards in QE14 Deck (13):
Name 5 MEMS or BioMEMS devices that have been successfully commericalized.
2. Pressure sensor
4. Flow sensor
5. Motion sensor
Suggest three good masking thin films for etching silicon in KOH.
1. Polycrystalline Silicon
2. Silicon Nitride
3. Silicon Dioxide
Name two advantages of capacitive pressure sensors as compared to piezoresistive ones.
1. Low voltage, current operation
2. No doping required
Name two advantages of ion implantation as compared to diffusion for doping silicon.
1. Better dose control
2. Lower temperature
3. More control over depth
Name a common silicon wet etchant and suggest a good masking layer for it.
KOH with a masking layer of polycrystalline silicon
Name one advantage and one disadvantage of Si-Si fusion bonding as compared to Si-Glass anodic bonding
1. No electric field present (advantage if have sensitive magnetic components)
2. Sensitive to surface defects or particles
What is SU8 and where is it used most often?
Commonly used negative-photoresist. Used to provide high-aspect ratio.
What is self-assembled monolayer (SAM) and where is it used in MEMS fabrication?
Used to prevent stiction and it is used in the drying process after etching.
Which one of the following polymers can be deposited in gas phase and exhibit conformal coverage?
Is PDMS hydrophilic or hydrophobic? How can you change the surface energy of PDMS for better bonding to another PDMS or glass?
Hydrophobic. By altering the mixing ratio.
1. Name two sources of stress in thin films and explain their source.
2. Draw a diagram explaining the difference.
1. Extrinsic - thermal stress
2. Intrinsic - lattice misfit, impurities
1. What actuation mechanism is good for situations that you need large travel range?
2. What about cases that the travel range is a few micron but you need very precise control over movement (nm)?
1. Thermal actuation