Improved interface properties and reliability for Hf-In-Zn-O semiconductor capacitors with an electric-double-layer gate dielectric by inserting a HfO2 interlayer

• Hf-In-Zn-O (HIZO) metal-oxide-semiconductor (MOS) capacitors studied
• Electric-double-layer (EDL) dielectric applied to MOS capacitors
• Large capacitance of 0.7 μF/cm2 and low gate leakage of 3 × 10− 6 A/cm2 achieved
• HfO2 interlayer can effectively improve interface quality of the HIZO/EDL interface
• HfO2/EDL stack gate dielectrics can enhance MOS capacitors' reliability

The electrical characteristics and reliability of Hf-In-Zn-O (HIZO) metal-oxide-semiconductor capacitors (MOSCAPs) with a microporous SiO2-based electric-double-layer (EDL) dielectric were investigated. Experimental results indicated that the HfO2 interlayer could effectively improve the interface quality, thus leading to reduced interface states, suppressed hysteresis and decreased gate leakage current. Improved performance was achieved for the HIZO MOSCAPs with HfO2/EDL stack gate dielectrics (HECAPs), such as a large capacitance density of 0.7 μF/cm2, an interface state density of 5.7 × 1011 eV− 1/cm2, a fixed charge density of 1.9 × 1012 cm− 2, a hysteresis voltage of 230 mV and a gate leakage current density of 3 × 10− 6 A/cm2 at + 1 V. Moreover, enhanced reliability of the HECAPs was obtained with an elevated dielectric breakdown voltage of 4.8 V and a small increase (< 15 %) of gate leakage after gate bias stressing at 2 V for 3600 s.