Title :
Effect of bias on thermally stimulated current (TSC) in irradiated MOS devices
Author :
Fleetwood, D.M. ; Reber, R.A., Jr. ; Winokur, P.S.
Author_Institution :
Sandia Nat. Lab., Albuquerque, NM, USA
fDate :
12/1/1991 12:00:00 AM
Abstract :
The electric-field dependence of thermally stimulated current (TSC) in irradiated MOS capacitors for TSC fields ranging from -3 MV/cm to +2 MV/cm was studied. TSC measurements at negative bias following positive-bias irradiation provide useful estimates of the net oxide-trap charge, ΔGot, if the TSC bias is large enough to overcome trapped-hole space-charge effects. Very little TSC is observed for positive-bias irradiation. Under proper TSC bias conditions, TSC and C-V estimates of ΔGot agree well for thick, soft oxides, but differ significantly for thin, hard oxides. Differences between TSC and C-V estimates of ΔG ot for thin, hard oxides are attributed to electron injection into the oxide and capture at trap sites associated with the radiation-induced trapped holes. It is shown that TSC measurements can provide insight into the location of hole traps in MOS oxides that cannot be obtained from standard C-V tests
Keywords :
X-ray effects; electron traps; hole traps; interface electron states; metal-insulator-semiconductor devices; semiconductor device testing; thermally stimulated currents; C-V characteristics; MOS capacitors; TSC bias; X-ray irradiation; electric-field dependence; electron capture; electron injection; hard oxides; negative bias; net oxide-trap charge; positive-bias irradiation; radiation-induced trapped holes; soft oxides; thermally stimulated current; trapped-hole space-charge effects; Capacitance-voltage characteristics; Charge measurement; Circuits; Current measurement; Density measurement; Electron traps; MOS devices; MOSFETs; Measurement standards; Performance evaluation;
Journal_Title :
Nuclear Science, IEEE Transactions on