| AVS 56th International Symposium & Exhibition | |
| MEMS and NEMS | Friday Sessions |
| Session MN-FrM |
| Session: | Multi-scale Interactions of Materials and Fabrication at the Micro- and Nano-scale |
| Presenter: | J.-F. Veyan, University of Texas at Dallas |
| Authors: | J.-F. Veyan, University of Texas at Dallas K. Roodenko, University of Texas at Dallas Y. Gogte, University of Texas at Dallas X.-M. Yan, Qualcomm MEMS Technologies, Inc. Y. Chabal, University of Texas at Dallas |
| Correspondent: | Click to Email |
Etching sacrificial material during MENS and NEMS manufacturing constitute an important processing step. XeF2 is a commonly used chemical etchant because of its selective interaction with pure compounds and their oxides. Practically, realistic systems are characterized by multicomponent films with interfaces, and side reactions have to be taken into account in the study of the complex chemistry taking place during the etching process. We have studied XeF2 etching of pure Silicon, pure Molybdenum, and Molybdenum deposited on Silicon oxide and Al substrates, in pressures consistent with industrial conditions (~ Torr range) using in-situ time-resolved IR reflection spectroscopy and ex-situ XPS.
We find that Si and Mo react with XeF2 in very different ways. For Si, F atoms penetrate deep inside the Si lattice, for Mo they stay at the surface. These differences greatly affect the etching kinetics, involving bulk-controlled etching process for Si, and a surface controlled etching for Mo.
After XeF2 etching and removal of Mo and Si films deposited on Al substrates, the surfaces exhibit residual molybdenum (oxy) fluoride and silicon oxide layers. F1s core level spectra indicated excess fluorine atoms on all surfaces. CFx contaminations have been found on Si/Al and on Mo/Al surfaces after etching, but not on bare Al substrates, even after XeF2 exposures. The stability of etched surfaces is also studied.