Yield sensitivity study of A1GaAs/GaAs high electron mobility transistor

Abstract

A simple graphical statistical method is presented and is used to study the statistical sensitivity of the AlGaAs/GaAs High Electron Mobility Transistor (HEMT) small-signal performances to physical model parameters, Using an analytical model and applying numerical techniques, the small-signal performances, transconductance, gate-to-source capacitance, current gain cut-off frequency, and the optimum cut-off frequency are calculated for four different HEMTs. These are then used as the device specifications in the Monte Carlo-based sensitivity analysis. Based on the model, a device simulator is developed in which the gate length, the gate width, and the carrier mobility are statistically varied simultaneously about their nominal values. The yield factor histograms for each small-signal parameter and its sensitivity to the process parameter variations are determined. In this work, we report that the current gain cut-off frequency increases as the carrier mobility increases, but it is almost independent of the gate width. We observe that the gate-to-source capacitance is independent of the carrier mobility, but it is strongly dependent on the transistor dimension. All the performance yields analyzed here go down as the gate length increases.