Nitrogen

Nitrogen • Non-Metals

Primary XPS region: N1s
Overlapping regions: Ta4p_3/2, Mo3p_3/2, Cd3d_5/2
Binding energies of common chemical states:

• The N1s region may be overlapped by peaks from tantalum, molybdenum, or cadmium.
  • In the case of molybdenum, collect the full Mo3p / N1s region (370–455eV), making sure both Mo3p_3/2 and Mo3p_1/2 components are acquired.
  • In the case of tantalum, it will be sufficient to collect only the Ta4p_3/2 / N1s region (370–450eV).
• When analyzing nitrogen-containing hafnium compounds (e.g., nitrided hafnium silicate), the plasmon loss from the Hf4p_3/2 feature badly overlaps the N1s region.
  • Acquire the N1s / Hf4p_3/2 region and the associated hafnium plasmon (365–410eV).
• During sputter profiling, if nitrogen is observed when it should not be present, this probably indicates a leak in the argon supply.

• A variety of nitrogen bonding states may be observed as received silicon oxynitride samples.
  • Higher binding energy states (with oxygen atoms substituted in place of silicon) are thermodynamically unstable^[1] (and are typically not observed for annealed silicon oxynitride samples).
  • These states decay rapidly with Ar+ sputtering, even at low beam energies.
    • Sputter profiling cannot be used to depth-profile these states.
  • Angle-resolved XPS is the appropriate method for identifying the depth distributions of the nitrogen chemical states.

• N1s peak shapes for metal nitrides (e.g. TiN) can be complex and unusual, possibly with presence of surface oxynitrides.
  • In the case of as received TiN, the oxidized nitride state in the N1s region is observed at lower binding energy compared to the pure nitride state.
    • Oxidation normally moves components to higher binding energy (e.g. NiSi₂O compared to NSi₃).