Field-effect in large grain polysilicon transistors

The influence of grain boundaries on the electrical characteristics of polysilicon transistors is investigated. The grain size [a few microns) is assumed to be of the same order of magnitude as the channel dimensions, which is the case in laser recrystallized polysilicon films. A 2-D study of the band curvature near a grain boundary in a MOSFET was carried out in order to estimate the evolution of the grain-boundary-induced potential barrier versus Late voltage. Expressions of the drain current have been derived and are compared with device-measured characteristics. The viability of integrated circuits made in large grain polysilicon films is also discussed.