Demonstration of HfO₂-Based Gate Dielectric With ~0.8-nm Equivalent Oxide Thickness on Si_0.8Ge_0.2 by Trimethylaluminum Pre-Treatment and Al Scavenger

Abstract

We disclosed HfO2-based dielectric of superb electrical properties on p-type Si0.8Ge0.2 substrate using an interfacial layer (IL) formed by trimethylaluminum (TMA) pre-treatment and Al scavenger. Our results revealed that the interface trap density (Dit) value and the gate leakage current (JG) could be improved about 60 times and 100 times by tuning the gate electrode composition without sacrificing equivalent oxide thickness (EOT) performance. The mechanism underlying the ${\mathrm{ D}}_{\mathrm{ it}}$ improvement of the SiGe metal-oxide-semiconductor capacitors (MOSCAPs) might be owing to the Al metal scavenger and the minimization of the oxygen atoms diffusing to the high- $\kappa $ /SiGe IL, verified by x-ray photoelectron spectroscopy (XPS) analyses. In addition, the hysteresis levels of SiGe capacitors with various gate electrodes were measured to find out the optimized configuration of metal electrodes. This work demonstrated the Al scavenger effect from the aspects of both material and electrical properties and achieved an impressive EOT value of $\sim 0.8$ nm for the capacitors fabricated on the SiGe substrate.

Keywords

• Low EOT
• Al scavenger
• TMA pre-treatment
• SiGe channel