Ultra High Aspect Ration SiN Etching

Since the establishment of the joint laboratory with STM in 2007, the team has supported this industrial partner and anticipated the implementation of breakthrough technologies. This axis was developed mainly within the framework of CIFRE theses or funded by the Nano 2012 and 2017 programs. For example, we analyzed the mechanisms leading to the degradation of the resin mask during the wet removal of the TiN grid and proposed solutions compatible with integration. We also worked on the defects appearing during the downstream plasma removal stage of post-implantation resin masks and proposed solutions. In both cases, the results led to technological transfers implemented by STM in its advanced CMOS sectors. We have also developed an ultra-selective SiN etching process compared to SiO2 in downstream plasma which makes it possible to empty trenches with an aspect ratio of 100 (Figure 3). We obtained remarkable results with this process in 2017, which motivated the purchase of a reactor for this application at STM and a new CIFRE thesis will start in 2019 on this theme. Finally, we assist STM in the development of reactor cleaning strategies in order to improve the reproducibility of etching processes for new materials (ITO, metals, etc.).

SiN trenches etched in downstream plasma :