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
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,