FIB

Question 1

channeling

Answer 1

some ions go between atoms in columns thus penetrate much deeper than modelled by SRIM

Question 2

colour due to channeling

Answer 2

darker areas - ions travel further and it is more difficult for them to escape

Question 3

particle flux

Answer 3

sputtered neutral atoms
secondary ions -SIMS
secondary electrons
photons

Question 4

Why Galium for liquid ion metal source?

Answer 4

low melting T - limited reactions between W and Ga
low volatility - doesnt eveaporate and has high purity
excellent mechanical and electrical properties
Low surface energy - viscous behaviour on W needle

Question 5

Ga emission

Answer 5

Ga heated by electrical coil
flows down to W tip
field applied to tip to create sharp cones (taylor cone, 5 nm diameter)
one electrostatic and surface tension forces balance, extraction voltage can pull Ga from W
As Ga extracted it ionised by field evaporation
Ions accelerated and focused by lenses down column to target

Question 6

brightness as figure of merit

Answer 6

high current good, high current density better,
high brightness is best
can be used

Question 7

Applications

Answer 7

Observing defect

sectioning of porous electrode and 3D reconstruction

Question 8

fib resolution

Answer 8

4 nm