Analysis of the effect of germanium preamorphization on interface defects and leakage current for high-k metal-oxide-semiconductor field-effect transistor

In this article, the authors analyze the impact of germanium amorphization on the interface defect concentration of state of the art high- k metal gate metal-oxide-semiconductor field-effect transistors. The gate etch is a crucial process step for the high- k gate first integration approach. Germanium implantation is used to amorphize the annealed and, therefore, nanocrystalline hafnium silicon oxide. This ensures a well controlled wet etch removal. The quality of the gate oxide to the channel interface of the transistor samples is monitored by charge pumping. The influence of the damage caused by the germanium implant at the unprotected gate edge is analyzed for different gate stacks by measuring the gate induced drain leakage. The defect concentration at the gate edge can be reduced by adjusting the germanium amorphization energy.