Sacrificial Layer Removal
Constructing three-dimensional microstructures requires a so-called sacrificial layer, which acts as a scaffolding while the structures are built. Once the structures are complete, the scaffolding is removed to relief the MEMS structure, allowing the structure to assume it’s designed function, such as gyros, sensors or actuators.
One of the advantages with microwave plasma is the unique capability for the process radicals to enter even through very small orifices, removing the sacrificial layer from a large cavity as shown in the processing sequence on the right hand side. As our direct microwave application allows the radicals to be created near or even inside the structure to be cleaned from resist, this process is very effective even for large cavities with a relatively small opening.
Removing SU-8* as a very special resist for MEMS devices has been proven successfully in many cases for R&D as well as in production.
* SU-8 is a trademark from Microchem
The example shows a medical device for drug application, where the needles created using SU-8 are covered with metal. After metal deposition the Tepla system is used to remove the SU-8 from within the needles through a very small opening in the top of the structures.