it is all about the magnetic configuration..  (balanced vs unbalanced)

if your substrates are flat, linear magnetrons (rotating cathodes) for an inline process is most advisable. at least this is industrial standard.

for 3D samples, the coating machines also use big linear cathodes because of chamber design (see Hauzer company  or Cemecon , Ionbond). Many samples are put on big 'caroussel' (merry go round) and have many fold rotation. Big linear targets are mounted In the doors/sidewalls of the vacuum vessel .

Batch mode machines..

Now if you have a process which is fast enough, you may think of a part-2-part machine. A smaller chamber perfectly matched to your sample. In that case round targets may be of advantage..

Do some magnetic simulation to check how homogeneous the plasma can be.

Good Luck

lukas

First please think of the physical location of the substrate.

Second please think about whether you will use CMS or FTS.

Thirdly, think about the magnetic field (balanced or unbalanced). You can make a closed field configuration by combinning S-N-S with N-S-N if you are thinking FTS.

You also think of deposition rate and the applied power source whether DC or AC or RF.

For larger substrates in dynamic configuration (substrate is moving past the deposition sources in a continuous way), I would always advise linear, cyindrical, rotatable cathodes (cylindrical, tube shaped target which rotates during deposition and static magnet array inside). Very often dynamic depositon rate (DDR) is better for rotary cathodes and in many cases the magnetic field is better balanced than for planar magnetrons. Especially small disk shaped magnetrons are often extremely badly balanced.