Observation and Utilization of Boron Segregation in Trench MOSFETs to Improve Figure of Merit (FOM)
We report the observation and utilization of boron segregation in trench MOSFETs (UMOS) to reduce on-resistance. A trenched LOCOS process has been applied to a UMOS structure to reduce the gate-to-source overlap capacitance (C gs), and it is observed that not only 40% reduction in C gs is achieved but also 45% reduction in specific on-resistance (R on, sp). Figure of merit is improved by 58%. TSUPREM-4 doping profile simulation at the silicon and oxide interface revealed the presence of boron segregation. On-resistance reduction is attributed by the shortened vertical channel length due to boron segregation.
UMOS transistors on
When common V-groove etching techniques are applied to
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.