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Physical vapor deposition

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[[{{PAGENAME}}|Physical vapor deposition (PVD)]] is a type of deposition where source materials are transformed into a vapor or plasma using a physical process (typically heating or bombardment.) The vapor then moves towards a substrate where it condenses on the surface.
More details: [ LNF Technology seminarTech Talks]: PVD February 27, 2015: video recording and complete slides are available.
Bias can increase the energy of incoming atoms and change the stress of the film. Also, bias can cause collisions at the substrate level and redeposit atoms so it can be used to try and increase sidewall coverage.
==General Film Characteristics==
PVD films in generaly are dominated by island nucleation with low diffusion that then transforms into vertical fibers or columnar growth. Unless there is heating to temperatures that approach 50-70% of the melting point, the growth will not be crystalline with large grains. Evaporation typically grows with fibrous, domed structures while sputtering, which has a bit more energy and resputtering, approaches columnar growth.
If we combine the morphologicaly nature of the film with other factors (source size, gas collisions/mean free path and deposition angle) we can describe general trends in the film:
{| class="wikitable"
! style="font-weight: bold;" |Evaporation
! style="font-weight: bold;" |Sputtering
|'''Low Ion Energy'''
* Low heating/bombardment
* Pinholes at lower thicknesses
* Less energy for reactive films
|'''Higher Ion Energy'''
*Often denser films, better adhesion, smaller grain size
*Easier to make reactive films using injected gas.
|'''High Vacuum Process'''
*Higher directionality, poor step coverage
*Better for liftoff
*Lower impurity and less gas trapping
*Only optical/radiative heating
|'''Low Vacuum Process (process gas pressure)'''
*Less Directionality = better step coverage
*Chance of more gas entrapment in film
*Higher heat from plasma
|'''Point Source''' - poorer uniformity
|'''Larger source''' - better uniformity
|Rates dependent on melting point + vapor pressure - '''difficult to do alloys''' (co-dep recommended.) Some compounds dissociate with heating.
|Components typically sputter at similar rates when targets are alloyed to start with. Often knock off '''compounds as molecules'''.
==See also==
LabUser, OnlineAccess, PhysicalAccess, Staff, StoreManager, StoreUser


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