Ultrathin Al sub(2)O sub(3) and HfO sub(2) gate dielectrics on surface-nitrided Ge

We have studied ultrathin Al sub(2)O sub(3) and HfO sub(2) gate dielectrics on Ge grown by ultrahigh vacuum-reactive atomic-beam deposition and ultraviolet ozone oxidation. Al sub(2)O sub(3)-Ge gate stack had a t sub(eq) similar to 23 Aa, and three orders of magnitude lower leakage current compared...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2004-01, Vol.51 (9)
Main Authors: Jer-Hueih Chen, James, Bojarezuk, NA Jr, Shang, Huiling, Copel, M, Hannon, J B, Karasinski, J, Preisler, E, Banerjee, S K, Guha, S
Format: Article
Language:English
Subjects:
Annealing
Deposition
Dielectrics
Gates
Germanium
Hafnium oxide
Leakage current
Silicon dioxide
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Summary:We have studied ultrathin Al sub(2)O sub(3) and HfO sub(2) gate dielectrics on Ge grown by ultrahigh vacuum-reactive atomic-beam deposition and ultraviolet ozone oxidation. Al sub(2)O sub(3)-Ge gate stack had a t sub(eq) similar to 23 Aa, and three orders of magnitude lower leakage current compared to SiO sub(2). HfO sub(2)-Ge allowed even greater scaling, achieving t sub(eq) similar to 11 Aa and six orders of magnitude lower leakage current compared to SiO sub(2). We have carried out a detailed study of cleaning conditions for the Ge wafer, dielectric deposition condition, and anneal conditions and their effect on the electrical properties of metal-gated dielectric-Ge capacitors. We show that surface nitridation is important in reducing hysteresis, interfacial layer formation and leakage current. However, surface nitridation also introduces positive trapped charges and/or dipoles at the interface, resulting in significant flatband voltage shifts, which are mitigated by post-deposition anneals.
ISSN:0018-9383
DOI:10.1109/TED.2004.833593