Surface Micromachining

Question 1

Surface micromachining

Answer 1

successive deposition and patterning of layers.
- Only get to design masks, not process!

Question 2

Structural layers

Answer 2

Materials that will not be removed during release

Question 3

Sacrificial (spacers)

Answer 3

layers that will be removed during the release step

Question 4

isotropic or conformal deposition

Answer 4

all uniform height

Question 5

anisotropic or directional deposition

Answer 5

uniform height in one direction

Question 6

planar deposition

Answer 6

forms a flat plane and fills all features

Question 7

planarization

Answer 7

uses chemical mechanical polishing to get a planar surface

Question 8

dimples

Answer 8

bumps beneath a freestanding plane that reduce contact area between the structures and the substrate
- lower incidence of stiction both post release and in use

Question 9

MUMPS

Answer 9

• Multi user MEMS processes
• 3 layer polyssilison surface
• 8 litho levels (including masks), 7 physical layers

Question 10

Mumps layers

Answer 10

• nitride
• poly 0
• 1st oxide
• poly 1
• 2nd oxide
• poly 2
• metal

Question 11

conformal growth issues

Answer 11

can block moving parts or work not as intended

Question 12

polystringers

Answer 12

left behind during the etch, we dont want these