Direct deposition of uniform high-κ dielectrics on graphene.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhou P
PROVIDER: S-EPMC4650933 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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Project description:Current status and challenges of aggressive equivalent-oxide-thickness (EOT) scaling of high-κ gate dielectrics via higher-κ ( > 20) materials and interfacial layer (IL) scavenging techniques are reviewed. La-based higher-κ materials show aggressive EOT scaling (0.5-0.8 nm), but with effective workfunction (EWF) values suitable only for n-type field-effect-transistor (FET). Further exploration for p-type FET-compatible higher-κ materials is needed. Meanwhile, IL scavenging is a promising approach to extend Hf-based high-κ dielectrics to future nodes. Remote IL scavenging techniques enable EOT scaling below 0.5 nm. Mobility-EOT trends in the literature suggest that short-channel performance improvement is attainable with aggressive EOT scaling via IL scavenging or La-silicate formation. However, extreme IL scaling (e.g., zero-IL) is accompanied by loss of EWF control and with severe penalty in reliability. Therefore, highly precise IL thickness control in an ultra-thin IL regime ( < 0.5 nm) will be the key technology to satisfy both performance and reliability requirements for future CMOS devices.
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Project description:High-k materials such as Al2O3 and HfO2 are widely used as gate dielectrics in graphene devices. However, the effective work function values of metal gate in graphene FET are significantly deviated from their vacuum work function, which is similar to the Fermi level pinning effect observed in silicon MOSFETs with high-k dielectric. The degree of deviation represented by a pinning factor was much worse with HfO2 (pinning factor (S)?=?0.19) than with Al2O3 (S?=?0.69). We propose that the significant pinning-like behaviors induced by HfO2 are correlated with the oxygen exchange reactions occurred at the interface of graphene and HfO2.
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