Structure zone model calculator
Predict the morphology of sputtered metal films.
Use this interactive plot to determine the microstructure of sputtered metal films as predicted by the Thornton structure zone model, given a material, substrate temperature, and Ar pressure in the sputtering chamber.
Specify a material, substrate temperature, and Ar pressure to display the resulting structure zone. The pressure and temperature cursors can also be dragged.
- Open-voided tapered fibrous structure
- Limited adatom diffusion, yielding amorphous crystallographic structure
- Poor lateral strength and low density
- Films typically exhibit higher resistivity
- Densely packed, poorly defined fibrous grains
- Thermally enhanced surface diffusion begins to fill voids between columns
- Crystallographic structure of columns still amorphous
- Films typically exhibit high optical reflectance, low-to-moderate resistivity, compressive stress
- Wider faceted columnar grains separated by dense intercrystalline boundaries
- Thermally enhanced surface and grain-boundary diffusion yields higher column crystallinity
- Decreased effect of sputtering pressure on film morphology
- Film properties comparable to bulk material
- Recrystallised, near-equiaxed columnar grains
- Bulk and boundary adatom diffusion dominate film structure
- Negligible effect of sputtering pressure on film morphology
- Film properties very similar to bulk material
The Structure Zone Model (SZM) developed by J.A. Thornton relates the microstructure of sputtered metal films to the experimental sputtering conditions (chamber pressure and substrate temperature) [1,2]. Building on earlier work on evaporated films , Thornton's model originally described sputtered films 25–250 µm thick, but the major features of the SZM have been shown to apply to thin (>100 nm) sputtered films as well [4,5].
The SZM catalogs four zones of differing film morphologies as a function of the sputtering chamber pressure P and the homologous substrate temperature TH = T/Tm, where T is the substrate temperature and Tm is the melting point of the deposited material. This morphology in turn determines film properties of interest, such as optical constants, resistivity, and stress. Choosing appropriate sputtering deposition conditions is therefore important to achieve the film characteristics necessary for a given application.
In the above interactive plot, adapted from , the relevant structure zone for a sputtered film is identified upon specifying the material, substrate temperature, and argon pressure. The cursors for pressure and substrate temperature may also be dragged to explore different regions of the sputtering parameter space. A description and diagram of the film morphology are displayed for the corresponding zone.
N.B. The results of this calculator should only be taken as a rough guide to the expected film structure, particularly in the vicinity of the zone boundaries. In reality, these boundaries are not sharp and some variation is to be expected. SEM analysis is recommended to confirm the film morphology definitively for any critical applications.