Investigation of amorphous hydrogenated carbon layers as sacrificial structures for MEMS applications

This work presents a novel approach that utilizes amorphous hydrogenated carbon (a-C:H) layers as sacrificial structures for MEMS applications. The a-C:H layer serves as a buried sacrificial layer in the fabrication process. With the removal of the a-C:H by plasma etching processes, the movable structures are released. The fabrication of test structures is based on silicon surface micromachining technology. On those test structures, etch rates were determined for two different etch chemistries. The use of a-C:H as a sacrificial layer offers several advantages such as dry release capabilities accompanied by a high thermal and mechanical stability of the sacrificial layer and thus the possibility to integrate those layers in standard CMOS technology. Consequently, the proposed dry removal techniques prevent movable structural components from stiction problems associated with wet processing. The newly developed sacrificial layer process is suitable for a wide range of MEMS applications.