Thick silicon membrane technology for reliable and high performance operation of high voltage LIGBTs in Power ICs

A step change in performance and reliability of thick SOI membrane devices compared to earlier generation of devices on ultra-thin SOI membranes is reported in here. The membrane concept first reported offered a landmark improvement in the trade-off between switching losses and breakdown capability (in excess of 700V) but its current capability was limited by the thickness of the silicon membrane (around 30 A/cm² for LIGBTs on 0.25 mum silicon membranes, achieving a loss related power density approaching 100 W/cm² ). This paper reports on membrane power devices with current densities which approach the best of those offered by vertical devices (current density greater than 100 A/cm with power density of 180 W/cm² ), without sacrificing switching speed (t_off < 60 ns for 1.5 mum membranes). HTRB results showing 1000 h+ operation at 125degC at 80% of the rated voltage are also presented. Finally, it is shown that both the static and dynamic high temperature operation of thick membrane LIGBTs is superior to that of state-of-the-art integrated LDMOSFETs.