Stress induced defect generation implications of doping HfO2 with Al

Abstract

Display Omitted Investigation of the reliability implications of Al-doping, which has been show to increase the k-value of HfO2.Very little TDDB improvement.High stress induced leakage current, confirmed to be due to defects at the HfO2/SiO2 interface. In this work we detail the reliability implications of doping HfO2 fabricated for use as the gate dielectric in an advanced CMOS process with aluminium. Introducing two single pulses of an Al-precursor during ALD causes the HfO2 to crystallise into a higher dielectric constant phase allowing for up to a factor of 300 reduction in the initial leakage current for a given EOT. However this results in only a small increase in TDDB lifetime due to the fact that there is a relatively large stress induced leakage current (SILC) generated in the doped layers, which we find to be mostly due to shallow defects. Furthermore, charge pumping measurements show large Nit generation in Al-doped layers, particularly towards the HfO2/SiO2 interface.