Browsing by Author "Liu, Chee Wee"

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LDMOS Transistor High-Frequency Performance Enhancements by Strain
(2012-04-01)
Chen, Kun-Ming
;
Huang, Guo-Wei
;
Chen, Bo-Yuan
;
Chiu, Chia-Sung
;
Hsiao, Chih-Hua
The effects of mechanical stress on the dc and high-frequency performances of laterally diffused MOS (LDMOS) transistors with different layout structures were investigated by using the wafer bending method. A 3.1% peak cutoff frequency (f(T)) enhancement is achieved for the multifinger device under 0.051% biaxial tensile strain. For LDMOS with annular layout, the f(T) enhancement is increased to 3.7% due to the various channel directions. Our results suggest the strain technology can be adopted in LDMOS for RF applications. The transconductance and gate capacitance were also extracted to clearly demonstrate the f(T) variations.
The Dependence of the Performance of Strained NMOSFETs on Channel Width
(2009-11-01)
Yeh, Lingyen
;
Liao, Ming Han
;
Chen, Chun Heng
;
Wu, Jun
;
Lee, Joseph Ya-Min
The dependence of the performance of strained NMOSFETs on channel width was investigated. When the channel width was varied, the stress in the channel varied accordingly. This changed the electron effective mass and, consequently, the ON-state current I(on). By shrinking the channel width of a strained NMOSFET from 1 to 0.1 mu m and by keeping the channel length at 55 nm, the ON-state drain current per unit channel width was enhanced by 22%. The gate leakage current was also affected by the stress in the channel, which can be explained by the increase in hole barrier height at the Si/SiO(2) interface. Furthermore, when the film stress was increased by 1 GPa, the gate leakage current density J(g) of a strained NMOSFET with a channel width of 0.1 mu m and a length of 55 nm under a negative bias -3 V was reduced by 63%.