| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2+TF-ThM |
| Session: | Atomic Layer Etching (ALE) and Low-Damage Processing |
| Presenter: | Gottlieb Oehrlein, University of Maryland, College Park |
| Correspondent: | Click to Email |
We discuss use of low pressure plasma surface interaction mechanisms aimed at achieving atomic scale precision in etching materials. Using a steady-state Ar plasma in conjunction with periodic injection of a defined number of C4F8 molecules and synchronized plasma-based Ar+ ion bombardment, we have shown that one tenth of a nanometer precision in etching of SiO2 is possible.1 For low energy Ar+ ion bombardment conditions giving a maximum ion energy of about 20eV, the physical sputter rate of SiO2 vanishes whereas for an FC-coated SiO2 surface, chemical modifications of the SiO2 surface take place and SiO2 etching is initiated. Precise management of C4F8 supply enables control of the deposited fluorocarbon (FC) layer thickness in the 1 to several Ångstrom range. We will discuss the temporal variation of the chemically enhanced etch rate of SiO2 for Ar+ ion energies below 30 eV as a function of fluorocarbon surface coverage which enables controlled removal of Ångstrom-thick SiO2 layers per process cycle. We will also discuss silicon underlayer etch rate measurements and challenges connected with this approach.
1 D. Metzler, R. Bruce, S. Engelmann, E. A. Joseph, and G. S. Oehrlein, J Vac Sci Technol A 32, 020603 (2014)
* Based on collaborations with D. Metzler, C. Li, S. Engelmann, R. Bruce, E. Joseph, E. Godyak, and M. Kushner. We gratefully acknowledge funding from National Science Foundation (CBET-1134273) and US Department of Energy (DE-SC0001939).