Reliability of ALD Hf_(1-x)Zr_xO_2 Deposited by Intermediate Annealing or Intermediate Plasma Treatment

摘要

The reliability of atomic layer deposited Hf_(1-x)Zr_xO_2 with x=0.8 on a SiON interfacial layer (TL) has been analyzed in detail for three different oxide deposition processes, (ⅰ) DADA: samples were subjected to dielectric deposition and thermal annealing in a cyclical process; (ⅱ) DSDS: samples were subjected to similar cyclical process with dielectric deposition and exposure to Ar plasma; and (ⅲ) As-Dep: the dielectric for the control samples was deposited without any intermediate step. Capacitance-voltage and current-voltage characteristics of the MOS capacitors (MOSCAP) with metal gate (TiN), subjected to a constant field stress of 2.75 × 10~7 V/cm in the gate injection mode, show that the flat-band voltage shift (△V_(FB)) and stress induced leakage current (SILC) below 100 s stress is the lowest for DSDS samples whereas the worst degradation was observed for DADA samples. However, identical degradation was observed in all sample types when stress was increased to 1000 s. Intermediate plasma exposure (DSDS process) seems to supress the oxide trap formation as it provides EOT downscaling ability and good reliability performance. The reliability characteristics, when compared with pure HfO_2, seem to improve with the addition of ZrO_2.