Pulsed-laser atom probe tomography of p-type field effect transistors on Si-on-insulator substrates

Abstract

Forty-five nanometer gate length p-type field effect transistors fabricated on Si-on-insulator substrates were analyzed using three-dimensional pulsed laser atom probe tomography. An optimized sample preparation methodology involving spacer etching and a change in sample orientation to align the Si/buried-SiO2 interface with the analysis direction was developed to overcome the inherent difficulties in field evaporation of insulating materials present in the device structure. Atom probe tomography analysis of samples prepared in this cross-sectional orientation was used to observe B segregation to the gate SiO2 at 5 nm from the edge of the gate, from both the poly-Si gate doping as well as the source–drain extension ion-implantation following rapid thermal annealing at 900 °C for 16 or 32 s.