Depth profiling of chemical states and charge density in HfSiON by photoemission spectroscopy using synchrotron radiation

Abstract

We have investigated chemical states and charge density in HfSiON films as a function of depth using x-ray irradiation time-dependent photoemission spectroscopy. N 1s core-level photoemission spectra deconvoluted into three components depend on HfSiON thickness, indicating the component, which is attributed to the N atoms bonded to Hf atoms, has peak near the surface. On the other hand, charge density estimated from band bending in Si from Si 2p photoemission spectra is also distributed mainly near the surface. These results indicate that the origin of the negative charge trapping can be directly related to the presence of Hf–N bonds.

Effects of thermal annealing on charge density and N chemical states in HfSiON films

“…This dependence indicates a direct relationship between negative charge trapping and Hf-N bonds in HfSiON films. 5 Therefore, it is necessary to decrease in the number of Hf-N bonds in order to decrease the charge density. In this letter, we have investigated the annealing effects on the N chemical states and charge density in HfSiON/Si samples annealed at various oxygen gas partial pressures by performing timedependent PES measurements using synchrotron radiation.…”

“…The peak positions in the spectra shift toward lower binding energies indicating upward band bending in Si and trapping of negative charges in the HfSiON films due to x-ray irradiation, as shown in our previous study. 5 The annealing oxygen gas pressure dependence of the peak positions of the Si 2p 3/2 bulk components as a function of the x-ray irradiation time is shown in Fig. 1͑b͒.…”

Effects of the Interface-related and Bulk-fixed Charges in Ge/GeO₂ Stack on Band Bending of Ge Studied by X-ray Photoemission Spectroscopy

“…Importantly, the interplay between negative interface charges and positive fixed charges is responsible for the observed opposite band bending behavior. We also note that XPS has been widely used to investigate the influence of bulk fixed charges in dielectrics to the band bending at semiconductor/insulator hetero-junctions [7,8], while rare report has been published on the impact of interface charges. Our study shows that such interface charges are also very important especially for the materials which CNL position is below the mid-gap.…”

(Invited) Synchrotron Radiation Photoelectron Spectroscopy of Metal Gate/HfSiO(N)/SiO(N)/Si Stack Structures

“…Samples were dipped into a 0.01% HF solution for 3 s, 2 min, 3 min, 4 min, and 6 min to gradually decrease the thickness of HfSiON films. Figure 7(a) shows Si 2p 3/2 binding energy change as a function of SR irradiation time for HfSiON/SiON/Si and HfSiO/SiON/Si samples chemically etched-off (14). Only for the HfSiON/SiON/Si with the total thickness of 2 nm shows a drastic binding energy shift toward the lower binding energy, that is the larger kinetic energy, suggesting negative charging-up.…”