Browsing by Author "Tu, Chun-Yuan"

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Achieving High-Scalability Negative Capacitance FETs with Uniform Sub-35 mV/dec Switch Using Dopant-Free Hafnium Oxide and Gate Strain
(2018-01-01)
Fan, Chia-Chi
;
Cheng, Chun-Hu
;
Tu, Chun-Yuan
;
Liu, Chien
;
Chen, Wan-Hsin
For the first time, we successfully demonstrated that the 4-nm-thick dopant-free HfO2 NCFETs using gate strain can implement an energy-efficient switch of a low gate overdrive voltage and a nearly hysteresis-free sub-40 mV/dec swing. The gate strain favorably rearranges oxygen vacancies and boosts orthorhombic phase transition. Furthermore, the dopant-free HfO2 NCFET can be further improved by in-situ nitridation process. The 4-nm-thick nitrided HfO2 NCFETs achieve a steep symmetric sub-35 mV/dec switch, a sustained sub-40 mV/dec SS distribution, and excellent stress immunity during NC switch. The high-scalability and dopant-free NCFET shows the great potential for the application of future highly-scaled 3D CMOS technology.
Implementation of Dopant-Free Hafnium Oxide Negative Capacitance Field-Effect Transistor
(2019-01-01)
Cheng, Chun-Hu
;
Fan, Chia-Chi
;
Tu, Chun-Yuan
;
Hsu, Hsiao-Hsuan
;
Chang, Chun-Yen
For the first time, we successfully demonstrated the dopant-free HfO2 negative capacitance (NC) transistor featuring a low gate-overdrive voltage and a nearly hysteresis-free sub-40 mV/dec swing. These excellent performances can be ascribed to the reduction of the monoclinic phase suppressed with the thickness scaling and gate stress engineering favorably rearranging oxygen vacancies to boost orthorhombic phase transition. The highly scalable and dopant-free NC transistor shows the potential for the application of advanced CMOS technology.
Interface Engineering of Ferroelectric Negative Capacitance FET for Hysteresis-Free Switch and Reliability Improvement
(2018-01-01)
Fan, Chia-Chi
;
Tu, Chun-Yuan
;
Lin, Ming-Huei
;
Chang, Chun-Yen
;
Cheng, Chun-Hu
In this work, we successfully achieve a hysteresis-free negative capacitance field effect transistors (NCFETs) by exploiting a defect passivation scheme. This research work simultaneously provides a new insight into the gate-oxide stress reliability of NCFET. The fluorine-passivated HfAlOx NCFET shows the excellent transistor characteristics including a steep subthreshold swing of sub-30-mV/dec, a negligible hysteresis-free switch of similar to 10mV and a large on/off current reatio (I-on/I-off) of >10(7). Most importantly, fluorine passivation for NC HfAlOx effectively suppress the generation of shallow traps during electrical stress test. Besides, it is favorable to maintain NC operation and SILC immunity by in-situ fluorine passivation, which has been verified by transient pulse I-V measurement.