Plasma etching of Hf-based high-k thin films. Part I. Effect of complex ions and radicals on the surface reactions
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095 (United States)
The effect of ion and radical compositions in BCl{sub 3}/Cl{sub 2} plasmas was assessed in this work with a focus on the formation of etch products in patterning hafnium aluminate, a potential high-k gate oxide material. The plasma composition became increasingly more complex as the percentage of boron trichloride was increased, which led to the formation of a significant amount of boron-containing species including B{sup +}, BCl{sup +}, BCl{sub 2}{sup +}, BCl{sub 3}{sup +}, B{sub 2}Cl{sub 3}{sup +}, and B{sub 2}OCl{sub 3}{sup +} in the plasma. The BCl{sub 2}{sup +} ions were found to be the dominant species in BCl{sub 3} containing plasmas at most conditions; however, increasing the pressure or decreasing the power led to an increase in the formation of higher mass ions. 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 as functions of ion energy and plasma composition. The etch product distributions were measured and the dominant metal-containing etch products were HfCl{sub x} and AlCl{sub x} in a Cl{sub 2} plasma and HfCl{sub x}, HfBOCl{sub 4}, and Al{sub x}Cl{sub y} in a BCl{sub 3} plasma, and their concentrations increased with increasing ion energy. Oxygen was detected removed in the form of ClO in Cl{sub 2} and as trichloroboroxin ((BOCl){sub 3}) in BCl{sub 3}. Both the etch rate and the etch product formation are enhanced in BCl{sub 3}/Cl{sub 2} plasmas, as compared to those in Cl{sub 2} plasmas, due to the change in the composition and reactivity of the dominant ions and radicals.
- OSTI ID:
- 21199656
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 27, Issue 2; Other Information: DOI: 10.1116/1.3065679; (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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