Paper EM-TuA10
Characterization of the “Clean-Up” of the Germanium Surface by ALD using Trimethyl Aluminum and Water
Tuesday, November 10, 2009, 5:00 pm, Room B1
| Session: |
High-K Dielectrics on High Mobility Substrates |
| Presenter: |
M. Milojevic, University of Texas at Dallas |
| Authors: |
M. Milojevic, University of Texas at Dallas
R. Contreras-Guerrero, CINVESTAV-IPN, Mexico
M. Lopez-Lopez, CINVESTAV-IPN, Mexico
J. Kim, University of Texas at Dallas
R.M. Wallace, University of Texas at Dallas
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| Correspondent: |
Click to Email |
The “clean-up” effect on III-V substrates has recently been well documented.1 For the purpose of this study the “clean-up” of Ge oxides by ALD is explored using XPS. By interrupting the ALD process following individual precursor pulses for in-situ monochromatic XPS analysis the reaction mechanisms can be studied in unprecedented detail. As in the case of III-V substrates native germanium oxides are found to be reduced strongly by TMA. Interestingly if the sample is treated with a plasma nitridation technique a GeON layer is grown that appears impervious to this reaction. This is not unexpected given the reports of the stability of GeON formed by ion rather than radical based plasma processes.2 Oxide free germanium surfaces behave analogously to a surface with initial native oxides since they are oxidized measurably prior to the first TMA pulse due to residual oxidants in a commercial ALD chamber. The unique aspect of the TMA driven “clean-up” is exposed when comparing it to the reduction of interfacial oxides by a thin metallic aluminum layer.3,4,5,6 In this case in addition to the reduction of germanium oxides the aluminum layer also results in Ge-Al bond formation. In contrast “clean-up” of the oxide by TMA is characterized by a preferential reduction of higher oxidation states of germanium and the absence of any detectable reduction products on the surface.This work was supported by the FCRP Focus Center on Materials, Structures and Devices and the Texas Enterprise Fund.
REFERENCES
[1] Milojevic, et al., APL 93 (2008) 202902.
[2] Sugawara et al., J. Vac. Sci. Technol. B 2(5), Sep/Oct 2006.
[3] Larsson et al., J. Vac. Sci. Technol. A 7(3), May/June 1989.
[4] Waite et al., J. Vac. Sci. Technol. A 11(4), July/Aug 1993.
[5] Oshima et al., Vac. Sci. Technol. A 12(2), Mar/Apr 1994.
[6] Margaritondo et al., J. Vac. Sci. Technol. A 1(2), Apr/Jun 1983