In:
Materials Science Forum, Trans Tech Publications, Ltd., Vol. 1062 ( 2022-05-31), p. 528-532
Abstract:
Metal-oxide-semiconductor capacitors with single and multi-layer high-K gate dielectrics on Si (0001) face of n-type 4H-SiC substrates have been investigated. Multi-layered nanolaminated gate-stack comprises alternating ultrathin (6nm) Al 2 O 3 and HfO 2 . A 5nm thick interfacial silicon oxynitride is deposited prior to laminated films to investigate interface trap properties and tuning of flat band voltage. Total thickness of gate-stack films including interfacial layer is 55nm. The thermal stability of multi-layered nanolaminated film is investigated using XTEM. Localized crystallization of HfO 2 is visible after RTA at 900°C while Al 2 O 3 remains fully amorphous. Some of HfO 2 grains have extended into Al 2 O 3 layer but was not able to crossover. The measured accumulation capacitance of 55nm thick gate dielectric gives an effective dielectric constant value of 9.6 and an equivalent oxide thickness of 22nm from high-frequency capacitance-voltage measurements. A positive flat band voltage ( of 12.2V and 10.6V are observed from both single layer HfO 2 and Al 2 O 3 dielectrics, respectively due to presence of negatively charged oxygen interstitial defects generated during atomic layer deposition process. However, V FB shifted towards negative voltage-7.6V for multi-layered Al 2 O 3 /HfO 2 stacks probably associated with positive Al and Hf interstitials at interface of Al 2 O 3 /HfO 2. Ultrathin interfacial oxynitride films is effective to reduce D it to 3×10 11 /eVcm 2 and tuning of V FB . The breakdown field of stacked gate dielectric on 4H-SiC is 10.0 MV/cm.
Type of Medium:
Online Resource
ISSN:
1662-9752
Language:
Unknown
Publisher:
Trans Tech Publications, Ltd.
Publication Date:
2022
detail.hit.zdb_id:
2047372-2
