Overview of Nanofabrication Techniques

Experimental Methods ClubMonday, July 7, 2014

Evan Miyazono

Outline

• Addition (deposition)• Subtraction (etching, milling)• Patterning

Deposition• figures of merit– uniform– conformal/edge coverage– deposition temperature– deposition material– lattice mismatch & / built in strain

Deposition

• Thermal evaporation• e-beam evaporation• Sputtering

Other deposition

• chemical vapor deposition (CVD)

• vapor liquid solid (VLS) method of nanowire growth

Deposition tricks

Etching

• figures of merit– isotropy/anisotropy– selectivity– redeposition?• check volatility/solubility of products

Dry Etching• reactive ion etching (RIE)• inductively coupled plasma (ICP)• sputtering– includes FIB Ga+ milling

• chemical assisted ion beam etching

ICP RIERIE FIB

CAIBE

Exotic Dry Etches

Burek et al., Nano. Lett. 2012, 12, 6084-6089

Angled ICP

Wet Etching

• often more selective & isotropic– some etch along crystal planes

• ion beam enhanced etching

KOH etching of silicon

He+

LiNbO/YSO

Patterning

• e-beam lithography• photolithography

• patterning a uniform layer– polymer used as etch mask

• patterning something hard to etch?– deposit on polymer and lift-off unwanted material

Beating patterning limitations

• cheating positive feature limits with sacrificial masks & conformal deposition

• cheating negative feature limits with built in stress and

Case Study: SOI

Silicon on insulator

Wafer bonding: plasma clean + heat + pressure

Dry etchDevelop resist

Strip resist

Spin coat photoresistHF undercut

Transfer to REI host

photoresist

My GaAs/YSO device Fabrication

AlGaAs

GaAs

GaAs

Strip photoresistapply e-beam resistDirect write

e-