Plasma etching of Hf-based high-k thin films. Part II. Ion-enhanced surface reaction mechanisms
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095 (United States)
The mechanism for ion-enhanced chemical etching of hafnium aluminate thin films in Cl{sub 2}/BCl{sub 3} plasmas was investigated in this work, specifically how the film composition, ion energy, and plasma chemistry determine their etch rates. Several compositions of Hf{sub 1-x}Al{sub x}O{sub y} thin films ranging from pure HfO{sub 2} to pure Al{sub 2}O{sub 3} were etched in BCl{sub 3}/Cl{sub 2} plasmas and their etch rates were found to scale with {radical}(E{sub ion}) in both Cl{sub 2} and BCl{sub 3} plasmas. In Cl{sub 2} plasmas, a transition point was observed around 50 eV, where the etch rate was significantly enhanced while the linear dependence to {radical}(E{sub ion}) was maintained, corresponding to a change in the removal of fully chlorinated to less chlorinated reaction products. In BCl{sub 3} plasma, deposition dominates at ion energies below 50 eV, while etching occurs above that energy with an etch rate of three to seven times that in Cl{sub 2}. The faster etch rate in BCl{sub 3} was attributed to a change in the dominant ion from Cl{sub 2}{sup +} in Cl{sub 2} plasma to BCl{sub 2}{sup +} in BCl{sub 3}, which facilitated the formation of more volatile etch products and their removal. The surface chlorination (0-3 at. %) was enhanced with increasing ion energy while the amount of boron on the surface increases with decreasing ion energy, highlighting the effect of different plasma chemistries on the etch rates, etch product formation, and surface termination.
- OSTI ID:
- 21199657
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 27, Issue 2; Other Information: DOI: 10.1116/1.3065695; (c) 2009 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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