Enhanced electrical and reliability characteristics in HfON gated Ge p-MOSFETs with H2 and NH3 plasma treated interfacial layers

Electrical and reliability characteristics of Ge pMOSFETs with H2, NH3 and NH3+H2 plasma treatments were studied in this work. The GeOx interfacial layer (IL) formation and HfON dielectric deposition were performed in atomic layer deposition (ALD) chamber. H2 and NH3 plasma treatments were in-situ performed on GeOx IL in ALD chamber. The equivalent oxide thickness (EOT) can be scaled down by H2 plasma treatment, and the interface trap density (Dit) is reduced with NH3 plasma treatment. The enhanced on current of devices with H2 plasma treatment can be attributed to its lower EOT. Reliability characteristics of devices are improved by H2 plasma treatment on IL due to effects of H+ passivation at GeO2/Ge interface. A Ge pMOSFET with an EOT of ∼0.47 nm and a high hole mobility of ∼401 cm2/V-s is demonstrated in this work by combining NH3 and H2 plasma treatments (NH3+H2).