Low-temperature annealing behavior of iron-related deep levels in n-type silicon wafers

Abstract

The iron-related deep levels in n-type silicon and their thermal stabilities were investigated by deep-level transient spectroscopy (DLTS). Three deep energy levels at E c − 0.35, E c − 0.41, and E c − 0.48 eV were observed and classified into two types from the annealing behavior at room temperature and a low temperature of 200 °C. We found for the first time that only one iron-related deep level at E c − 0.35 eV was highly stable at room temperature and 200 °C, while other iron-related deep levels were unstable. We also found that the concentration of the deep energy level at E c − 0.41 eV gradually decreased at room temperature. These results suggest that the origin of the thermally stable level at E c − 0.35 eV is attributed to the substitutional iron-related level, and those of the thermally unstable levels at E c − 0.41 and E c − 0.48 eV are attributed to interstitial iron-related complexes such as iron-acceptor pairs in p-type silicon.

Iron-related deep electron traps in epitaxial silicon resolved by Laplace-transform deep level transient spectroscopy

“…The parameters of the Fe1 and Fe2 electron traps (table 1) are in good agreement with those of the B and C traps whose deep energy levels were found to be located at E c − 0.41 and E c − 0.48 eV, respectively, detected in phosphorus-doped n-type epitaxial silicon purposely contaminated with iron [14]. The net donor concentration in the 10 μm thick epitaxial layers was ∼1.7×10 14 cm −3 .…”

“…We observe a substantial decrease in the Fe1 and Fe3 traps concentrations in time to the values of 1.9×10 10 and 1.1×10 10 cm −3 , respectively, which indicates that the long term RT annealing of these traps occurs and as a result of this annealing the Fe2 trap is observed at a concentration of 1.8×10 10 cm −3 . The concentrations of B(0.41 eV) and C(0.48 eV) electron traps reported in [14] were also found to decrease in time when stored at RT. The initial concentrations of these traps were 2.2×10 10 and 2.5×10 10 cm −3 , respectively and after 200 d storage at RT, these traps concentrations dropped to 1.3×10 10 and 2.3×10 10 cm −3 , respectively.…”

Effect of low-oxygen-concentration layer on iron gettering capability of carbon-cluster ion-implanted Si wafer for CMOS image sensors

“…Ohmic contacts were obtained by rubbing Ga on the back surfaces. The Fe-related deep levels in the n-type Si obtained by DLTS were located at E c − 0.35, E c − 0.41, and E c − 0.48 eV in the upper half of the Si band gap, 26) then the ungettered Fe concentration was evaluated as the sum of three Fe-related deep energy levels. The concentration data of Fe was obtained within 7 µm from the sample surfaces.…”

Electrical property of iron-related defects in n-type dislocated Czochralski silicon crystal used for solar cells

“…In addition, the existence of substitutional iron atoms may be responsible for deep level at E c -0.35 eV but the existence of substitution iron has not been confirmed by experiments. 31)…”