Reliability of 0.18 μm Gate GaAs-MESFETs Fabricated by i-Line Lithography Process

摘要

A 0.18-μm GaAs-MESFET fabrication process with low cost and high uniformity was established by means of i-line lithography and ion-implantation technology and high-speed operation of f_T > 100 GHz was achieved. As a result of the investigation of 0.18-μm GaAs-MESFET using the high-temperature accelerated life test, an activation energy of 1.54 eV and mean time to failure (MTTF) of 2.4 x 10~5 hours at a junction temperature of 150 ℃ were obtained. Gate sinking at the interface between the gate metal and GaAs substrate was revealed using the analysis of cross-sectional TEM and EDS. That failure mode is similar to GaAs-MESFET with a gate length of 0.8 μm. The amount of drain current degradation after burn-in test could not be quantitatively explained by the sinking of Ti to the GaAs substrate. We reveal the existence of a complex degradation mechanism related to the impact ionization at the drain access region.