Uniformity is set by the material being deposited and the geometry of the system: throw distance, target size, substrate rotation and deposition angle.
*In sputtering, uniformity is determined by throw distance and the shape of the deposition cone.
Denton and Lab 18 tools, smaller sources eject material from the face of a 3" target that is angled to cover around 1/2 of the substrate area. The substrate is rotated to coat the entire area. Varying the angle will vary the throw distance and change the amount deposited on the center and edge. The supplies have a set throw angle that is optimized for best uniformity.
**In the ALN tool, the wafer is centered over two targets which are larger than the substrate. Uniformity can be only be adjusted using the DC supply which raises and lowers the power to the center target.