Technology CAD based statistical simulation of MOSFETs

The parametric yield of VLSI strongly depends on the statistical process fl uctuations. Thus, the statistical simulation is needed for robust process, device and circuit designs. This article describes the statistical simulation of MOSFETs using Technolo gy CAD (TCAD). Threshold voltage V-th and sheet resistance R-sh Obtained th rough the statistical simulation were compared with measurements. The mean values of the simulated V-th and R-sh agreed well with those of the experim ents within 2% error. The standard deviations sigma revealed sufficient agr eements within 30% error, except for n-ch V-th. For a conventional method, larger coverage factors based on the principal c omponent analysis are selected to generate worst-case corner models. We pro pose a new factor selection method which uses the sensitivity analysis of a small but critical circuit, a ring-oscillator, for obtaining BSIM3v3 worst -case models. In this example, the proposed method selected the factor rela ted to a gate oxidation temperature, whereas the conventional method select ed the factor related to a LDD side-wall thickness. The proposed method was applied to the estimations of worst-case performance of the inverter DC ch aracteristics and data-out of DRAM. (C) 2000 Elsevier Science Ltd. All righ ts reserved.