Improvement in electrical characteristics of HfO2 gate dielectrics treated by remote NH3 plasma

We report the structural and electrical characteristics of hafnium oxide (HfO2) gate dielectrics treated by remote NH3 plasma under various radio-frequency (RF) powers at a low temperature. Significant increase of effective dielectric constant (keff), decrease of capacitance equivalent thickness (CET), reduction in leakage current density, and suppression of the interfacial layer thickness were observed with the increase of the RF power in the remote NH3 plasma treatment. The effects of hydrogen passivation and depassivation on the HfO2/Si interface due to the remote NH3 plasma treatment were also observed by the variation of photoluminescence (PL) intensity, indicating that the PL measurement is applicable to probe the interfacial properties. An ultrathin interfacial layer (∼0.3 nm), a high keff, (20.9), a low leakage current density (9 × 10−6 A/cm2), and a low CET (1.9 nm) in the nitrided HfO2 film were achieved, demonstrating that the nitridation process using remote NH3 plasma under a high RF power at a low temperature is a promising way to improve in electrical properties of high-K gate dielectrics.