Thin film deposition techniques by aqu16527

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									Thin film deposition techniques
Vapor phase deposition techniques:
Thin film deposition: physical techniques
knudsen cell: provide atomic or molecular beams under well
controlled conditions of vacuum and substrate cleanliness.

Good control of thin film thickness and quality.
Homoepitaxy: thin film growth modes
Growth depends on energetically favourable sites a the surface.
At a surface an added adatom may find kink sites – steps –
clusters – vacancies – impurities.                                 High Ta: adatoms move to most
The dynamics of the atoms „select“ between these sites depending   favorable sites: step growth.,
on the substrate temperature: diffusion vs. nucleation.
Controlling the thermodynamics of the growth mechanism it is
possible to control growth modes.
                                                                   Lower Ta: adatoms move slowly;
                                                                   nucleation of clusters: 2D island
                                                                   growth.




                                                                   Effect of the Ehrlich-Schwoebel
                                                                   barrier: Adatoms remain on top of
                                                                   2D islands; 3D growth.
Heteroepitaxy: thin film growth modes




 3D growth is generally undesired.
 To avoid it: The surfactant effect.
Chemical Vapor Deposition
Use a precursor molecule:
                                                  Layer by layer growth in CVD.
Reaction at the heated substrate surface.
Good method of depositing isolators.
CVD requires detailed design of reactor design,
precursor materials,...

								
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