Plasma enhanced atomic layer deposition of HfO2 with in situ plasma treatment

Plasma-enhanced atomic layer deposition was explored to produce thin HfO2 films, where oxygen plasma acted as oxidant. The interfacial layer (IL) was controlled by in situ pre-oxygen plasma treatment (PRO) and pre-ammonia plasma treatment (PRN). Post oxygen plasma treatment (POP) to HfO2 film was in situ executed. The IL thickness was 1.1 nm, which was detected to be HfSiON by X-ray photoelectron spectroscopy (XPS). With 4 nm thick amorphous HfO2 film, an equivalent oxide thickness (EOT) of total gate dielectric stacks of 0.87 nm was obtained. Small leakage current density of 0.02 mA/cm2 was measured at a gate bias of |Vg − Vfb| = 1 V.

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► HfO2 film was deposited by remote plasma enhanced ALD.
► A buffer layer was introduced by in situ PRO and PRN process before depositing HfO2.
► A in situ post oxygen plasma treatment was applied to reduce oxygen vacancies.
► An equivalent oxide thickness of 0.87 nm was obtained.
► Leakage current density of 0.02 mA/cm2 was measured at a gate bias of |Vg − Vfb| = 1 V.