Ion Beam Trimming
When trimming surfaces with ion beams, the surface is selectively and locally etched, so that almost any surface topographies can be achieved.
The achievable layer thickness distribution on the substrate after correction typically lies in the sub-nanometer range.
In particular, trimming is used in the manufacturing of SAW and BAW filters to tune the surface properties and thus the frequency. Here, as in the production of piezoelectric resonators and read/write modules, the procedure has been established as a key manufacturing step.
Further options include processes such as ion beam figuring that is applied to curved optical substrates and freeform surfaces. For demanding large substrates a special ICP-based ion beam source was developed with a large radius of action. This allows the movement of the ion beam source over static, not moving substrates (face-down processing, substrate static). Thus, for example, sensitive and large mirrors for astronomical and other applications can be processed.