Browsing by Author "Lin, Je-Hung"

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Study of thermal stability of HfOxNy/Ge capacitors using postdeposition annealing and NH3 plasma pretreatment
(2007)
Cheng, Chao-Ching
;
Chien, Chao-Hsin
;
Luo, Guang-Li
;
Yang, Chun-Hui
;
Kuo, Mei-Ling
We studied the thermal stability of the as-deposited HfOxNy thin films on the Ge substrate by employing rapid thermal annealing. After undergoing high-temperature processing, we observed several interesting physical and electrical features presented in the HfOxNy/Ge system, including a large Ge out-diffusion (>15 atom %) into high-k films, positive shift of the flatband voltage, severe charge trapping, and increased leakage current. These phenomena are closely related to the existence of GeOx defective layer and the degree of resultant GeO volatilization. We abated these undesirable effects, especially for reducing the amount of Ge incorporation (< 5 atom %) and the substoichiometric oxide at dielectric-substrate interface, through performing NH3 plasma pretreatment on the Ge surface. These improvements can be interpreted in terms of a surface nitridation process that enhanced the thermal stability of the high-k/Ge interface. In addition, we measured that the conductance loss in inversion was still high and it revealed independence with respect to gate bias, reflecting the fact that the minority carriers in Ge can rapidly respond either through a diffusion mechanism or through midgap trap states residing in Ge bulk substrates. (C) 2007 The Electrochemical Society.
Thermochemical reaction of ZrOx(N-y) interfaces on Ge and Si substrates
(2006-07-03)
Cheng, Chao-Ching
;
Chien, Chao-Hsin
;
Lin, Je-Hung
;
Chang, Chun-Yen
;
Luo, Guang-Li
We have studied the thermochemical characteristics of ZrOx(N-y)/Ge and Si interfaces by employing postdeposition annealing. We found that Ge oxide species severely desorbed from the inherent interfacial layer, which was speculated to retard the formation of Zr germanate during high-temperature processing. These unique features enable ZrOx(N-y)/Ge gate stack to show a better equivalent-oxide-thickness scalability as compared to ZrOx(N-y)/Si gate stack. However, the volatilization of GeOx-contained interfacial layer also caused the formation of small pits and/or holes in the overlying ZrOx(N-y) gate dielectrics, which was expected to cause deterioration in the electrical properties of fabricated high-k/Ge devices. (c) 2006 American Institute of Physics.
Ultrathin Si capping layer suppresses charge trapping in HfOxNy/Ge metal-insulator-semiconductor capacitors
(2007-01-01)
Cheng, Chao-Ching
;
Chien, Chao-Hsin
;
Luo, Guang-Li
;
Yang, Chun-Hui
;
Kuo, Mei-Ling
In this study the authors investigated the Ge outdiffusion characteristics of HfOxNy/Ge metal-insulator-semiconductor capacitors to determine their charge trapping behavior. Capping the Ge substrate with an ultrathin Si layer inhibits the incorporation of Ge into the high-k bulk dielectric in the form of GeOx, thereby diminishing the resultant oxide charge trapping. The thermal stability of the entire capacitor structure was also improved after performing an additional Si passivation process. (c) 2007 American Institute of Physics.