Title :
Comparison of charge trapping in undoped oxides made by low- and high-temperature deposition techniques
Author :
Mrstik, B.J. ; Hughes, H.L. ; Lawrence, R.K. ; McMarr, P.J. ; Gouker, P.
Author_Institution :
Naval Res. Lab., Washington, DC, USA
fDate :
12/1/2001 12:00:00 AM
Abstract :
Charge trapping has been studied in a series of undoped low-pressure deposited oxides made using either silane and oxygen in a low-temperature oxidation (LTO) process or pure tetraethylorthosilicate (TEOS) in a high-temperature process. The extent of charge trapping was determined by measuring the flatband voltage shift ΔVfb, resulting from injection of either holes or electrons separately (using photo-assisted injection techniques) or from exposure to 10 keV X-rays, in which holes and electrons are simultaneously created in the oxide. It is found that hole trapping is similar in identically annealed LTO and TEOS oxides, but that electron trapping is much larger in the TEOS oxides. Electron trapping in TEOS oxides is also found to depend inversely on the electric field. These results are used to explain the observation that X-ray exposure results in much smaller changes in ΔVfb in TEOS oxides than in LTO oxides at low applied fields, but to equivalent changes in ΔV fb at high applied fields. O2 anneals, but not N 2 anneals, are found to decrease the extent of electron trapping in the TEOS oxides, supporting previous suggestions that the electron traps result from carbon in the TEOS gas
Keywords :
X-ray effects; annealing; dielectric thin films; electron traps; high-temperature techniques; hole traps; oxidation; silicon compounds; 10 keV; LTO oxides; LTO process; N2; N2 anneals; O2; O2 anneals; SiO2-Si; TEOS gas carbon content; TEOS high-temperature process; TEOS oxides; X-ray exposure; annealed oxides; applied fields; charge trapping; electric field; electron injection; electron trapping; electron traps; flatband voltage shift; high-temperature deposition techniques; hole injection; hole trapping; low-temperature deposition techniques; photo-assisted injection techniques; silane/oxygen low-temperature oxidation process; tetraethylorthosilicate high-temperature process; undoped low-pressure deposited oxides; undoped oxides; Annealing; Boron; Charge carrier processes; Electron traps; Laboratories; Oxidation; Paramagnetic materials; Paramagnetic resonance; Temperature; X-rays;
Journal_Title :
Nuclear Science, IEEE Transactions on