| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS2-TuA |
| Session: | Deep Etch Processes for Vias, Trenches and MEMS |
| Presenter: | R. Dussart, GREMI CNRS/Université d'Orléans, France |
| Correspondent: | Click to Email |
Plasma deep etching is a necessary process step for the fabrication of most of microelectronic components, especially in power microelectronics and in MEMS technology. Although several etching processes were developed for silicon, deep etching of other materials such as titanium and gallium nitride is also of interest for innovative microdevices.
In this paper, deep etching of silicon using the so-called cryogenic process will be presented and compared with other processes. We will show and explain our characterization experiments by mass spectrometry, ellipsometry and in-situ XPS, which were carried out to investigate physical and chemical mechanisms involved in the silicon cryoetching process. These results were also used to develop the so-called STiGer cryoetching process, which will be also introduced. This particular process offers some advantages of the standard cryogenic process and is more robust.
Titanium deep etching using both fluorine and chlorine based chemistries was investigated by our group. Titanium is particularly interesting for bio MEMS applications. We developed the so-called APETi process to avoid roughness and increase the etch rate. With this process, we were able to etch up to 300 µm deep ring structures.
Finally, we will also show our process capabilities for deep GaN etching. For this material, a chlorine based chemistry is necessary to form volatile species. Measurements by Langmuir probe, by optical emission spectroscopy and by mass spectrometry were carried out to characterize the plasma in the different tested conditions. We will show that the material of the coverplate can play an important role in the etching mechanisms. Three types of defect were observed: « cavity » defects, « columnar » defects and the « white GaN ». The appearance mechanisms of these defects were studied and will be explained. Although we showed, by Transmission Electron Microscopy analysis, that the two first types of defect are clearly linked to intrinsic defects of the material itself, it is still possible to avoid their appearance during the etching.