Front- and Back-Interface Trap Densities and Subthreshold Swings of Fully Depleted Mode Metal-Oxide-Semiconductor Transistors Fabricated on Separation-by-Implanted-Oxygen Substrates

Abstract

By measuring the charge pumping current (I CP) and the subthreshold swing, we examined the front- and back-interface trap densities (D fit and D bit) of long channel N-type metal-oxide-semiconductor transistors fabricated on separation-by-implanted-oxygen (SIMOX) substrates, as a function of the total oxygen implantation dose. The front-channel subthreshold swing (S f) measured in the coupled condition was larger than that calculated with D fit and D bit obtained from I CP. However, dose dependences of the D fit and D bit obtained from I CP were consistent with those of the front- and back-channel peak mobilities, while those obtained from the subthreshold swings were not. These seemingly contradictory results can be satisfactorily explained by the existence of lateral nonuniformities (LNU) in the front- and the back-channel local threshold voltages. We propose that the experimentally determined S f can be used as an index of LNU in the SIMOX and other silicon-on-insulator substrates, just by comparing it with the theoretical value of S f.

Fin-Width Dependence of Ionizing Radiation-Induced Subthreshold-Swing Degradation in 100-nm-Gate-Length FinFETs

“…10 shows the subthreshold characteristics after irradiation and annealing with all terminals grounded for an 80-nm-finwidth, 100-nm-gate-length FinFET at room temperature after it had received a dose of 500 krd(SiO ). The characteristics shift in the positive direction during the annealing, which is consistent with neutralization of trapped-holes in the BOX [21], [24], [25]. The annealing experiments confirm the dominant effect of the trapped holes in modulating the subthreshold slope in irradiated FinFETs.…”

“…The SS increased by 10 mV/decade for 40-nm-fin-width FinFETs, compared to 40 mV/decade for 80-nm-wide devices at a dose of 500 krd(SiO ). Although a small amount of the stretchout may be caused by interface-trap formation, the majority of the stretchout is more likely due to nonuniform radiation-induced oxide trapped charge [21], [22]. Since the gate oxide is very thin, the density of interface traps is quite low [23].…”

Length and fin number dependence of ionizing radiation-induced degradation in bulk FinFETs

“…10 shows the subthreshold swing in the devices-undertest. Although a small amount of the stretchout may be caused by interface-trap formation, the majority of the stretch-out is more likely due to non-uniform radiation-induced oxide trapped charge [22,23]. Since the gate oxide is very thin, the density of interface traps is quite low [24].…”

Time-domain charge pumping on silicon-on-insulator MOS devices

“…23,24) However, the CP process in SOIs is rather complicated because the channel could be formed at the front, back, or at even both interfaces, depending on the bias conditions of the back gate. 25) Although CP on SOIs has been intensively investigated, [26][27][28][29][30][31] no studies have been performed on the charge flow, i.e., how and where the charges flow during the SOI CP sequence.…”