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Title: Inherent Si dangling bond defects at the thermal (110)Si/SiO2 interface
Authors: Keunen, Koen ×
Stesmans, Andre
Afanas'ev, Valeri #
Issue Date: Aug-2011
Publisher: Published by the American Physical Society through the American Institute of Physics
Series Title: Physical Review B, Condensed Matter and Materials Physics vol:84 issue:8 pages:1-15
Article number: 085329
Abstract: Stimulated by the growing manifestation in advanced semiconductor device development, an extensive multifrequency electron spin resonance (ESR) study has been carried out on the thermal (110)Si/SiO2 interface in terms of occurring paramagnetic point defects as a function of oxidation temperature T-ox (200-1125 degrees C), with seclusion of the H-passivation factor. The main type of defect observed is a P-b-type interface center closely related to the P-b((111)) and P-b0((100)) variants (Si-3 Si-center dot) characteristic for the (111) and (100) Si faces, respectively. The inferred principal g matrix values (g(//)= 2.0018 and g(perpendicular to) = 2.0082 for T-ox = 800 degrees C), splitting parameters of the resolved Si-29 hyperfine doublet, and line width behavior closely resemble those of P-b0((100)), from which the defect is typified as P-b0((110)). For low T-ox, an unexpectedly high density of P-b0((110)) defects (similar to 7 x 10(12) cm(-2)) is observed, which gradually dwindles for T-ox increasing above similar to 700 degrees C to approach similar to 4 x 10(12) cm(-2) for T-ox -> 1125 degrees C. The behavior is related to interfacial stress release as a result of global structural relaxation of the top SiO2 layer, an effect also signaled by attendant alterations in ESR parameters, including a drop in ESR line width and a change in line shape symmetry and g(perpendicular to). Comparison with previous ESR data on (111)Si/SiO2 and (100)Si/SiO2 interfaces indicates that, in terms of P-b type, the (110) face is the worst of all three low-index Si interfaces, i.e., [P-b0((100))] < [P-b((111))] < [P-b0((110))], in contrast with the common electrically inferred interface trap density order; only for T-ox >= 900 degrees C does the (110) face slightly improve on the (111) Si one, raising caution with the application of (110)Si/SiO2 in terms of vulnerability during device operation. The comparison further shows that, unlike a textbook quote, the density of occurring P-b(0) centers is not found to be proportional to Si surface areal atom density or available Si bond density. Instead, an empirically inferred matching criterion appears to be the surface areal Si atom density scaled by the number of bonds per atom directed into the oxide. Besides P-b0((110)), an apparently isotropic second type of interface center is revealed, baptized I-x, at g = 2.0048 with a density of similar to 1 x 10(12) cm(-2) that is rather independent of T-ox. Showing a similar passivation behavior in H-2 as the P-b0((110)) center, it is also interpreted as a Si dangling-bond-type defect, now residing in an interfacial randomized Si environment-a variant of the D center.
ISSN: 1098-0121
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Semiconductor Physics Section
× corresponding author
# (joint) last author

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