Browsing by Author "Jong, FC"

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A study on the radiation hardness of flash cell with horn-shaped floating-gate
(1997-09-01)
Huang, TY
;
Jong, FC
;
Chao, TS
;
Lin, HC
;
Leu, LY
The effects of radiation on the characteristics of split-gate electrical erasable programmable read only memory (EEPROM)/flash cells with recently-proposed horn-shaped floating gates are studied in terms of cell read current; data retention, cycling endurance, program/erase efficiency, threshold voltage and junction leakage. Our results show that the cells appear to survive after 1 Mrad (Si) Co-60 irradiation. Moreover, the after-irradiation cell read current actually increases in the ''erase'' (i.e., low-threshold voltage, high-conducting) state (i.e., improves), albeit the cell read current also increases in the ''program'' (i.e., high-threshold voltage, low-conducting) state (i.e., a degradation). Our results also show that, despite an improvement in the initial read current in the ''erase'' state immediately after radiation, the write/erase cycling endurance of the flash cells is significantly impeded after irradiation, due to a much faster ''window closure'' rate in the ''erase'' state, although the cell read current is found to remain relatively stable in the ''program'' state after cycling.
A study on the radiation hardness of flash cell with horn-shaped floating-gate
(1997-09-01)
Huang, TY
;
Jong, FC
;
Chao, TS
;
Lin, HC
;
Leu, LY
The effects of radiation on the characteristics of split-gate electrical erasable programmable read only memory (EEPROM)/flash cells with recently-proposed horn-shaped floating gates are studied in terms of cell read current; data retention, cycling endurance, program/erase efficiency, threshold voltage and junction leakage. Our results show that the cells appear to survive after 1 Mrad (Si) Co-60 irradiation. Moreover, the after-irradiation cell read current actually increases in the ''erase'' (i.e., low-threshold voltage, high-conducting) state (i.e., improves), albeit the cell read current also increases in the ''program'' (i.e., high-threshold voltage, low-conducting) state (i.e., a degradation). Our results also show that, despite an improvement in the initial read current in the ''erase'' state immediately after radiation, the write/erase cycling endurance of the flash cells is significantly impeded after irradiation, due to a much faster ''window closure'' rate in the ''erase'' state, although the cell read current is found to remain relatively stable in the ''program'' state after cycling.
Effects of floating-gate doping concentration on flash cell performance
(1997-08-01)
Huang, TY
;
Jong, FC
;
Lin, HC
;
Chao, TS
;
Leu, LY
In this paper we report the effects on flash cell performance of the doping concentration of the horn-shaped floating-gate. It is demonstrated that the Boating-gate doping concentration not only determines the work function of the floating-gate, but also affects the resultant interpoly oxide. As a result, the Bash cell performance is affected by the Boating-gate doping concentration, and should therefore be carefully designed. It is shown that a low doping level (e.g., <1.7x10(18) cm(-3)) on the Boating-gate results in a high threshold voltage of the flash cell, low cell read current, and degraded write/erase cycling endurance. Flash cells with a medium (e.g., 1.7 x 10(19) cm(-3)) doping level, on the other hand, depict the lowest threshold voltage, and the highest cell read current; while Bash cells with the highest doping level (1.7x10(20) cm(-3)) used in this study depict a medium threshold voltage. This could be ascribed to the fact that both medium and high doping levels result in a degenerate polysilicon floating-gate with a similar work function; however, a higher doping concentration results in a thicker interpoly oxide, and therefore a higher threshold voltage, and lower read current.
Effects of N2O-annealed sacrificial oxide on the short-channel effects of nMOSFETs
(1998-02-19)
Jong, FC
;
Huang, TY
;
Chao, TS
;
Lin, HC
;
Wang, MF
The authors report the effects of N2O-annealed sacrificial oxide on nMOSFETs. It is demonstrated that by adding an N2O-annealing step to the sacrificial. oxide which was stripped off before growing the final gate oxide, the reverse short-channel effects (RSCE) can still be effectively suppressed.
Improved flash cell performance by N2O annealing of interpoly oxide
(1997-07-01)
Jong, FC
;
Huang, TY
;
Chao, TS
;
Lin, HC
;
Leu, LY
In this letter, we report the effects of N2O annealing of interpoly oxide on flash cell performance. It is demonstrated that by adding an N2O anneal after interpoly oxide formation, improved cycling endurance is achieved, The program and erase efficiencies are also improved significantly, compared to the control cell without N2O anneal. The cells with N2O anneal show higher cell current (i.e., drain current), which can be ascribed to a lower threshold voltage and higher transconductance, compared to the control cell.
Improving radiation hardness of EEPROM/flash cell by N2O annealing
(1998-07-01)
Huang, TY
;
Jong, FC
;
Chao, TS
;
Lin, HC
;
Leu, LY
The effects of an N2O anneal on the radiation effects of a split-gate electrical erasable programmable read only memory (EEPROM)/flash cell with a recently-proposed horn-shaped floating gate were studied. We have found that although the cells appear to survive 1 Mrad(Si) Co-60 irradiation without data retention failure, the write/erase cycling endurance was severely impeded after irradiation. Specifically, the write/erase cycling endurance was degraded to 20 K from the pre-irradiation value of 50 K, However, by adding an N2O annealing step after the interpoly oxidation, the after-irradiation write/erase cycling endurance of the resultant cell can be significantly improved to over 45 K, N2O annealing also improves the after-irradiation program and erase efficiencies. The N2O annealing step therefore presents a potential method for enhancing the robustness of the horn-shaped floating-gate EEPROM/flash cells for radiation-hard applications.
The effects of shallow germanium halo doping on N-channel metal oxide semiconductor field effect transistors
(1999-01-15)
Wang, MF
;
Chien, CH
;
Chao, TS
;
Lin, HC
;
Jong, FC
In this paper, we report the use of shallow germanium halo doping on improving the short-channel effects of deep submicron n-channel metal-oxide-semiconductor field effect transistors. It is demonstrated that by adding a shallow (i.e., 10 keV) germanium large-angle-tilt implant (LATID), V-th lowering in short-channel transistors is significantly improved. The improvement is found to increase with increasing germanium dose. A low germanium dose (e.g., 5 x 10(12) cm(-2)) is also found to effectively improve the drain-induced barrier lowering (DIBL) of the short-channel transistors. Our results also show that junction leakage degradation, which has been previously reported to accompany germanium implants using higher energy, can be minimized by the shallow low-dose implant used in this study.