Browsing by Author "HO, TS"

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CHARGE LOSS DUE TO AC PROGRAM DISTURBANCE STRESSES IN EPROMS
(1993-09-01)
LIN, JK
;
CHANG, CY
;
WANG, TH
;
HUANG, HS
;
CHEN, KL
Charge loss in interpolyoxide erasable programmable read-only memories (EPROMs) due to program disturbance by alternating current pulses applied to the drain was studied for the first time. It was found that the charge loss due to ac stress is more severe than that due to dc stress. Experimental results reveal that the more positive the floating gate potential, the more severe is the drain ac disturbance observed. The main reason for the charge loss is the displacement current which agitates the charges in the floating gate, creating a leakage path from the floating gate to the drain, in which the drain-to-floating-gate overlapping capacitance C(fd) plays an important role. The drain dc stresses of interpolyoxide/nitride/oxide (ONO) EPROMs were also measured under different bias conditions and temperatures. The data show that higher dc electric field of the floating gate to the drain results in larger V(th) shift, which can be accelerated by elevated temperature. In addition, the control gate ac stress-enhanced drain dc disturbance was also measured. We proposed that the dc drain stress is applied during the ac gate stress, which results in a heating effect. The results support the concept of dielectric ac heating.
TRANSIENT AND STEADY-STATE CARRIER TRANSPORT UNDER HIGH-FIELD STRESSES IN SONOS EEPROM DEVICE
(1993-06-01)
LIN, JK
;
CHANG, CY
;
HUANG, HS
;
HO, TS
;
CHEN, KL
The carrier transport model of tunneling oxide in a polysilicon-oxide-nitride-oxide-silicon (SONOS) device has been developed. The model is deduced from WKB approximation, and uses Fermi-Dirac statistics. Using the J-E and accompanied by Arnett's trapping model, the switching behavior of the SONOS device can be predicted in a very wide range of switching times from 1 mus to 0.1 s. The steady-state charge distribution and electric field in Si3N4 are also calculated. From Arnett's fundamental equations of Si3N4, we deduce the steady-state equations which describe the electric field and trapping charges. The trapping parameters and detrapping factor v are discussed and the results are obtained via computer for different temperatures and stress voltages, which are based on the current measurement of SONOS devices. We find that the detrapping effect is somewhat less dominant compared to the trapping effect in our simulations.