Threshold Voltage Scattering of Ion Implanted GaAs Metal Semi-Conductor Field Effect Transistors

Abstract

The Vth scattering of GaAs metal semi-conductor field effect transistors (MESFETs) by ion implantation process were evaluated. In the case of depletion-mode field effect transistors (D-FET) whose gate length (Lg) was 0.76 µm, the standard deviation of Vth average (<Vth>) for 147 wafers was 0.015 V and the average of the Vth standard deviation for each wafer (σVth) was 0.012 V. Regarding the enhancement-mode field effect transistors (E-FET) of 0.44 µm Lg, the Vth scattering level was confirmed to be almost the same as that of D-FET. The σVth of 54,000 D-FET arrays, which demonstrates the Vth micro distribution in a wafer, was 0.011 V. The Vth variation obtained in this study is sufficiently small to achieve a high yield of GaAs LSI.