SEMATECH and NIST Collaborate on Chemical Analysis of Advanced Gate Dielectrics

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Figure 1. Si 1s spectra from 3nm HfO2 2nm SiO2 sample recorded with variable kinetic energy XPS illustrates depth profiling sensitivity and an interface effect near HfO2.
Figure 1. Si 1s spectra from 3nm HfO2/ 2nm SiO2 sample recorded with variable kinetic energy XPS illustrates depth profiling sensitivity and an interface effect near HfO2.

Nitrogen incorporation in thin HfO2/SiO2 film systems representative of high-k gate dielectric layers in advanced metal-oxide semiconductor field-effect transistors (MOSFETs) has been investigated by synchrotron x-ray photoelectron spectroscopy to elucidate variations in chemical composition between samples annealed in NH3 and N2 ambient as a function of temperature. In addition, depth profiling of core-level binding energy spectra has been obtained by variable kinetic energy x-ray photoelectron spectroscopy (VKE-XPS) with tunable photon energy. An HfO2/SiO2 “interface effect” has been detected in the Si 1s spectra characterized by a shift of the Si4+ feature to lower binding energy with no corresponding chemical state change observed in the Hf 4f spectra acquired over a broad range of electron take-off angles.


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