Precise determination of band offsets and chemical states in SiN∕Si studied by photoemission spectroscopy and x-ray absorption spectroscopy

Abstract

We have investigated chemical states and band offsets in SiN∕Si by photoemission spectroscopy and x-ray absorption spectroscopy. N1s photoemission spectra in SiN for three kinds of layer-thickness films are fitted by a single component, suggesting that a nitrogen atom is surrounded by three silicon and nine nitrogen atoms for the first and the second nearest neighbor, respectively. Valence-band offsets between SiN and the Si substrates are determined to be 1.6 eV using valence-band spectra by subtracting the contribution from Si substrates. Band gap of SiN is estimated to be 5.6–5.7 eV from valence-band, N1s core level, and NK-edge-absorption spectra. Furthermore, time-dependent measurements of N1s photoemission spectra reveal that the x-ray irradiation time is a significant factor to determine the precise valence-band offsets excluding the differential charging effects.

Analysis of x‐ray irradiation effect in high‐k gate dielectrics by time‐dependent photoemission spectroscopy using synchrotron radiation

“…It is reported that the peak top of the first derivative XAS spectrum is valid for estimation of conduction band minimum. [13] In the first derivative XAS spectrum of the HfSiON/Si, the peak at 2.5 eV indicates the conduction band minimum for the HfSiON film as shown in Fig. 2.…”

“…The E v changes by 0.4 eV at a maximum for HfSiON during x-ray irradiation, which is larger compared to that of conventional SiO 2 -based dielectrics. [13] In addition, band offsets of high-k dielectric films are relatively small. Using the band offsets and the dielectric layer thickness for HfSiON in this study and other parameters, [20] the estimated gate leakage increases by about one hundred times when the band offset decreases by 0.4 eV.…”

“…In order to avoid the ambiguities, it is reported that conduction band offsets can be determined using x-ray absorption spectroscopy (XAS). [13] In this study, we have performed x-ray irradiation time-dependent measurements of PES spectra and XAS measurements using synchrotron radiation, and precisely determined the band offsets for HfO 2 , HfSiO, and HfSiON by eliminating the x-ray irradiation effect.…”

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

“…213,214 This difference can be partially attributed to the ultra-low defect densities 215 typically achieved in gate-dielectric-quality SiO 2 and the two times larger bandgap for SiO 2 (∼9 eV) 216 relative to Si 3 N 4 (∼5.5 eV). 217 Interestingly, TAT and FN tunneling have also been reported as the dominant leakage mechanisms in a number of investigations of the electrical properties for Al 2 O 3 films deposited by a variety of methods. 188,[218][219][220] This is consistent with the similar IV characteristics exhibited by the thermal SiO 2 and ALD Al 2 O 3 films in Fig.…”

Determining factor of effective work function in metal/bi-layer high-k gate stack structure studied by photoemission spectroscopy

“…Time-dependent core-level shifts due to photo-induced carrier-trapping phenomena are reported to be more than 100 meV for various gate insulator films on Si substrates. 10,11 For this reason, we have performed timedependent core-level photoemission analysis during irradiation of incident light source. Sufficient signal-to-noise ratio is obtained in our experimental setup despite the very short data acquisition time for metal/high-k gate stack structures on Si substrates.…”