EXPERIMENTAL-EVIDENCE FOR STATISTICAL-INHOMOGENEOUS DISTRIBUTED DOPANT ATOMS IN A SI METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR

We have experimentally and analytically studied the statistically inhomogeneous distributed dopant atoms in silicon metal-oxide-semiconductor field-effect transistors (MOSFETs) with very small dimensions, by investigating the threshold voltage characteristics. By interchanging the source and the drain terminals of an individual MOSFET in an 8192 MOSFET array within an area of less than 0.7 mm2, it was found that the asymmetry of the threshold voltage Vth of a MOSFET is observed only at high drain bias, and continues to increase with increasing the drain bias and scaling the channel length down. These results can be quantitatively explained by our analytical model in which the dopant atoms are inhomogeneously distributed along the channel and statistically fluctuated in the local region of the channel among 8192 MOSFETs. © 1995 American Institute of Physics.