MEMS Basics

Question 1

Size of MEMS?

Answer 1

1 micron - 1milli

Question 2

What is a Transducer?

Answer 2

A device that converts one form of energy to another

Question 3

What is a sensor?

Answer 3

Converts a stimulus to electrical responses

Question 4

What is an actuator?

Answer 4

Converts electrical signals to non-electrical responses

Question 5

Classifications of Sensors

Answer 5

Thermal, Mechanical, Chemical, Electrical, Magnetic and Radiant.

Question 6

Actuator Types

Answer 6

Electrical Motors, Pneumatic Actuators, Hydraulic Actuators, Solenoid Valves

Question 7

Physical Phenomena

Answer 7

Electrostatics, Mechanical, Resonance, Piezoelectric/Electrostriction, Piezo-resistance, Fluidic Phenomena

Question 8

What is Piezoelectric?

Answer 8

A mechanical deformation causes an electrical charge. All peizoelectric materials exhibit electrostriction, where the direction of the E field matters

All peizoelectric materials exhibit electrostriction, where the directio

Question 9

What kind of materials are Piezoelectric?

Answer 9

Barium Titanate (BaTiO3)
Lead Zirconium Titanate (PZT)
PZT and BaTiO3 are ceramics
Zinc Oxide - n-type semiconductor
Gallium Nitrate
Polyvinylidene fluoride (PVDF)

Question 10

What is Electrostriction and what kind of materials are included?

Answer 10

An applied electric field causes mechanical deformation. All non-conducting materials and dielectrics

Question 11

What is piezoresistive and what kind of materials are included?

Answer 11

Mechanical Deformation causes a change in resistivity. Metals and Semiconductors

Question 12

Scaling Laws

Answer 12

Van der Waals, Diffusion, Distance, Surface Tension- Electrostatic Force- Friction-Piezoelectricity-Shape Memory Alloy, Mass-Gravity-Magnetism-Torque

Question 13

Interplanar Spacing

Answer 13

1/d=sqrt(h^2/a^2+k^2/b^2+l^2/c^2)

Question 14

Resonance Frequency

Answer 14

omega = sqrt(k/m)

Question 15

Strongest Plane

Answer 15

(1 1 1)

Question 16

When do you get good films on a substrate

Answer 16

when the d spacing is the same

Question 17

Define Anisotropy

Answer 17

When something is direction dependent, like electron movement in crystal

Question 18

What plane is invulnerable to Alkali etching/Vapor ethcing

Answer 18

(1 1 1)

Question 19

Memorize flats and wafers

Answer 19

Yes

Question 20

What is the easiest to etch

Answer 20

( 2 1 1)

Question 21

Hoe to find of three vectors are co planar?

Answer 21

(A x B) . C = 0

Question 22

Properties of Silicon

Answer 22

Brittle, not fluorescent

Question 23

What kind of material do latest transistors use?

Answer 23

Silcon Germanium. The germanium makes the lattice bigger to allow electrons to travel faster.

Question 24

Bandgap of Silicon

Answer 24

1.12 eV

Question 25

Lattice Parameter of Si

Answer 25

a = 0.54 nm

Question 26

At equilibrium, what is the formula for #holes and e-

Answer 26

n_0*p_0 = n_i^2

Question 27

Most common doping element for n-type and p-type

Answer 27

Phosphorus and Boron

Question 28

Relationship between Band Gap curvature and

Answer 28

The greater the curvature, the lower the effective mass of the electron. Curvature = 1/radius. Lower r = more curvature = less electron mass = more mobility

Question 29

Mobility Formula

Answer 29

mu = e*scattering time/effective mass

Question 30

Velocity?

Answer 30

v = mu*E

Question 31

sigma in terms of mobility?

Answer 31

e(n*mu_n+p*mu_p)

Question 32

J in terms of velocity

Answer 32

e(n*v_n+p*v_p)

Question 33

How does Photocurrent work and what is the total current?

Answer 33

If light is used to promote electrons, equal number of holes and electrons are made. I = Dark current + photocurrent

Question 34

Stress?

Answer 34

Sigma = Force/Area

Question 35

Strain?

Answer 35

Delta l/l

Question 36

Modulus?

Answer 36

stresss/strain

Question 37

Poisson Ratio

Answer 37

-Transverse Strain/Longitudinal Strain

Question 38

Regions in order on a stress/strain graph

Answer 38

Brittle Fracture, Yeild, Elastometric or flow region, Hardening, ductile fracture

Question 39

Tensile strength

Answer 39

stress at the maximum of the graph

Question 40

Toughness

Answer 40

Area under the stress strain graph

Question 41

Quality factor?

Answer 41

Energy stored/ Energy dissipated per unit cycle per radian