Sputtering Geometry

The geometry of the sputtering system is useful to know when designing processes such as lift-off. The deposition of material in a sputtering system is directional with some spread. The AJA ATC 2200 UHV sputtering system is equipped with 6 guns and a rotating chuck. The guns are arranged in a ring around the chuck. The angles of the guns are adjustable. The chuck position is adjustable. Figure 1 is a diagram of the sputtering system.

Figure 1: System Geometry

Figure 1: The diagram depicts the arrangement of the components in the sputtering system.

The gun angle is adjustable using a linear drive. The actuator settings are in units of [mm], which corresponds to the linear displacement of a rod. The table below correlates the linear drive settings to the actual gun angle, θ in Figure 1. An approximation of the gun angle is:
θ = -1.5*X + 39,
where X is the linear drive setting.

Linear Drive Setting [mm] Angle [°]
25 0
20 8.3
15 16.2
10 23.8
5 31.3
0 38.8

The chuck position is controlled by a linear drive. The settings on the chuck position corresponds to the position of the rod. It does not correspond to the sample to gun distance, but it does have a certain relationship. In the diagram in Figure 1, the chuck position is set at Z = 50 [mm]. When Z is changed to 30 [mm], the chuck is displaced by 20 [mm] downwards along the shaft. Although the chuck is closer to the guns, it is not 20 [mm] closer. To further complicate this the wafer to gun distance also depends on the chuck used. A wafer on the 3" magnetic chuck is 10 [mm] lower than a wafer on the 3" Inconel chuck. Nonetheless, if the working distance is important, it can be estimated from the information provided by the diagram in Figure 1.